Hi, all. Been a long time! I’m starting my fourth year in grad school and beginning dissertation work. The end is within sight, after which I hope to return to some level of activity. I’m using what few brain cells are left to think up some new, crazy stuff. But until that day eventually comes, I wanted to let you know about this other, crazy new project I’ve begun at my work: Citizen Sky.

This is not your average citizen science project. We are not asking simply for data. We also want to help YOU analyze the data and to help YOU publish YOUR results in professional journals! The idea is that citizen scientists get to experience the entire scientific process, not just one stage.

To help, we are developing tutorials, java-based analysis software with slick GUIs, building online collaborative tools, etc. We are also holding two public workshops. The first is this August at the Adler Planetarium in Chicago. That one is focused on data collection and E/PO. The second will be at the California Academies of Science in San Francisco in spring, 2010. That one will be focused on analysis and paper writing. Travel grants are available for each.

Our scientific target is epsilon Aurigae, a VERY bright star that undergoes an eclipse about every 27 years. No one understands the eclipse and there are some neat theories, include one that involves swallowing planets. The system is too bright for the vast majority of professional (and even amateur) telescopes, so we are recruiting the public to monitor the 1-2 year eclipse. Hence the citizen, in citizen science.

This is a big project. We needed the National Science Foundation to fund a grant proposal so we could do it all. The proposal itself took months for me to write, with help from a small army of collaborators. Now the NSF is going to fund us to run this project for 3 years and then, hopefully, expand into other citizen science projects. But the core is this: we want your help as real scientists, more than just data collectors (although you can stick with that if you want).

If interested, register for an account at Citizen Sky. Lots of new announcements will be posted there soon, including the opening of public forums similar to the old ones we had here once upon a time.

Universe Today reports that this technique was successful in finding a planet orbiting another star. They measured the star wobbling back and forth across their images over a 12-year time period. The star is 20 light years away, which is pretty close in astronomical terms, but it is also small, cool and dim, compared to the sun.

So that’s cool. That makes for at least 2 good planet-finding techniques using only imaging, something you can do from your backyard.

I, too, have recollections of great photometrists, having spent time with Dr. Arne Henden and, more recently, Dr. Arlo Landolt. It is a strange science that has given us a great deal of insight into our universe and stars in particular.

From http://hubblesite.org/servicing_mission_4/

As you know, it is the International Year of Astronomy (IYA) as well as the 400th anniversary of the astronomical telescope. There is a very cool telescope that is part of these celebrations, the Galileoscope, and it is only $15 and takes just a few minutes to assemble.

If you are an educator, troop leader or other person in front of young people, you can order the scopes in bulk and receive a discount. Or, if you are a generous sort, you could buy some for your school, church or club. If you order > 99 they cost only $12.50 each!

This is a great project. None of us are doing this for the money. This is not a commercial. This is a great learning experience just waiting to happen and/or just a cool little toy to own.

Buy some!

(picked this up from Dick’s Rocket Dungeon)

We have a new podcast heading your way soon!

The 100 Hours of Astronomy is going on right now! Go see what is near you!

I have to say, we are in good company! On the list in positions 1 through 4 are Phil “Please Digg This” Plait, Alan Boyle of Cosmic Log, who seems like a very smart guy despite the fact that he is an actual journalist, Astronomy Blog, manned by the Brit, Stuart, who is a nice fellow who speaks the Queen’s English and NASA Watch, a web site which does not have any connection whatsoever with, endorsement by, or authorization from, the National Aeronautics and Space Administration nor does any product or service being offered or made available to the public have the authorization, support, sponsorship, or endorsement of, or the development, use, or manufacture by or on behalf of the National Aeronautics and Space Administration.

And then, gloriously, the heaven’s part, angels sing, John Williams conducts and Slacker Astronomy is listed as #5! By this one guy! Sah-weet!

So thank you, some guy. You are tops #5 in our book, too.

Eta Carinae is an enigma. Look it up, it totally is. And it doesn’t look like that is going to change anytime soon! The image at right shows 3 cycles of the X-ray light curve. You can see the most recent event is quite different than previous events. We are watching one of the most massive stars possible changing on ridiculously short times scales.

What is going on? We don’t know.

People familiar with Slacker Astronomy have probably heard of Dr. Roberta Humphreys from my interviews with her. She is a professional astronomer at the University of Minnesota and she is a very well-connected and influential astronomer.

When Roberta Humphreys arrived at the University in 1972, the newly hired 28-year-old assistant professor of astronomy was, as she recalls, “the fifth and youngest woman faculty member in IT.

Her accolades are seriously impressive:

INSTITUTE OF TECHNOLOGY DISTINGUISHED PROFESSOR 2001-, ASSOCIATE DEAN FOR ACADEMIC AFFAIRS, INSTITUTE OF TECHNOLOGY 2002-2007; Fellow, AAAS 1980, Humboldt Senior Scientist Award, Federal Republic of Germany, 1988, George W. Taylor Research Award, Institute of Technology, 1985. AAS Tinsley Prize Committee 1994-96, Chair 1995-96; AAS Nominating Committee 1998-2000, Chair, 2000; NASA UV/Optical Review Panel 1995; NASA Senior Review (Office of Space Science) 2001; NASA Senior Review (The Universe) 2006; NSF Special Review for AURA 2000, NSF Special Review Panel for ITR/NVO 2001; NVO Science Definition Team 2001-02; University of Minnesota Member Representative to AURA 2001- 2010, AURA Nominating Committee 2006, Space Telescope Institute Council (AURA) 2004-2010. Senate/Faculty Consultative Committee 1995-96, 1998-2000, Vice-Chair University/Faculty senate 1995-96, 1999-2000;

I am writing about her for several reasons. She has been very kind and supportive of me, a lowly amateur astronomer who wanted to get involved with professional research. She is discussed in the book Lonely Hearts of the Cosmos about her time working with (and disagreeing with) Sandage on the determination the Hubble constant. The “Humphreys-Davidson Limit“, an empirical upper limit of the mass of stars which can become a red supergiant, is named after her and her husband, Dr. Kris Davidson. She is someone that everyone in the astronomical world knows is formidable and not to be trifled with. She is a consummate professional and a brilliant astronomer. Her work on massive stars is unequaled.

Further, she has worked her entire career not just on astronomy but on broadening the role of women in science in general.

She is a (short) giant and I am very grateful that I have been able to work with her and get to know her.

It was almost like looking at old love letters. I felt sad and nostalgic. These were the love letters that started my love affair with astronomy. After my girlfriend got me a telescope, I became an absolutely voracious amateur astronomer. I was part of the “every clear night club” — heading out to observe every clear night, regardless of the temperature, often observing in temperatures -15F (-26C). I eventually built an observatory, spent a fair amount of money on a great telescope, mount and CCD camera and started imaging and eventually doing photometry.

But that’s not all! I joined the Minnesota Astronomical Society, the AAVSO, the AAS (eventually) and the ASP. I started doing research in the department at the University of Minnesota. I started taking calculus and physics classes, eventually getting a BS in Astrophysics.

I got the bug big time.

When all of this started I was single. Eventually I got married and had one kid and then another. I started a new business along the way, which grew from $0 in revenue to $5M and from 4 people to 35. So my life, during my quest to learn as much as I could about astronomy, changed a lot. Suffice to say, I am no longer a member of the “every clear night club”. I’ve also satisfied a lot of my initial curiosity about astronomy. I got a BS in Astrophysics because I wanted to know how math could explain stars. I took classes on stars, galaxies, cosmology, computational physics — it was awesome. I learned (to some minor extent) about things like thermodynamics, quantum mechanics and relativity. I could read entire paragraphs of Chandrasakar and understand it!

I also got gigabytes of data at my observatory. I plotted light curves, made periodograms and Fourier spectra. I wrote code to reduce data, learned IRAF and presented posters at professional meetings. I even got involved with Slacker Astronomy!

I’m not bragging, in case that is what it seems. I still know much less than every PhD student of astronomy in the world. I’m no genius and am probably not particularly gifted at astrophysics. But I love it and I loved learning about it.

But in some small way I burned out. The pressure of going to my observatory (which is 45 minutes away by car) while taking classes and going to meetings, all the while raising a family and building a business, was too much. Eventually my observing had to go — I couldn’t keep up with my classes and be up all night. Then, after I got my degree, I found I still wasn’t observing much, and when I did, I didn’t even bother to reduce the data.

What had happened to me? Did this love affair with astronomy die…?

The answer, I know, is no. There is a time for everything and there is nothing to be gained by trying to cram things in when it doesn’t feel right. I need to take care of my family and my business. In the meantime, I am exploring hobbies that I can enjoy closer to home. Someday…a day I look forward to very much…I will live in a place where my observatory can be in my backyard. Someday my kids will grow up, my business will be sold and I will be back in my mistress’s arms again, through the long, beautiful night.

We have some new podcasts in the works…check the feed soon for some new audio.

Busy busy!

M.

You, as their constituent, have more voice than you are probably aware. If you go to your City Council or equivalent they will listen to you. They won’t necessarily act in your favor but they will, for sure, listen to you.

Light pollution is a lose-lose scenario. Said more positively, smart lighting saves money and is more safe than lights which create light pollution. You don’t have to be an astronomer to understand that light should be directed where needed and should not shine where/when it is not needed or unwelcome. To me, that is just obvious.

So the International Dark Sky Association (IDA) is doing a very, very smart thing. They are creating a model lighting ordinance that you can propose to your City Council. Just print it out, go to a meeting (or even meet with City Councilors individually) and tell them you want them to put this on the agenda, debate it and bring it to a vote. Insist that they do so. If they seem unwilling to listen to you, get a bunch of your neighbors to sign a petition saying you insist that they consider adopting an ordinance based on the model lighting ordinance.

The IDA is currently seeking feedback on the model lighting ordinance. If you are an astronomer, a developer, a corporation, lobbyist, public servant or someone who lives somewhere, take a moment to read the ordinance and let the IDA know if you think it can be improved.

I really believe that we can ultimately win the war against light pollution and bring the beauty of the night sky back to our cities. At the same time we will be safer and we’ll be saving money. I applaud the IDA for working towards this goal.

Check out some of these titles:

Armchair Astronauts Exploring the Solar System
Five Years of Spirit on Mars
Galileo Discovers Jupiter’s Moons, Going to Disneyworld
Gosh, Dim It All!
Have a Plan
How to be an Armchair Astronaut
January’s Garnet Star
Massive Stars with Dr. Roberta Humphreys
Observing Quasars with Nature’s Telescope
Pulsars
Radio Astronomy. What’s That
Space Telescope of the Future: The Space Interferometry Mission
The Link Between Beer and Space Settlement
The Man Who Beat Galileo
The North Star
The Seasons and Solar System Geometry
The Spacewriter’s Top Ten Reasons Why Stargazing is Cool
Tips For Your First Telescope
Understanding Variable Stars
Voyage Past the Sideways Planet
What is Astrobiology
Who Ordered the Dark Matter and Dark Energy

It’s all been really great stuff. Maybe I’ll link those titles when I have time.

Anyway, if you are not listening, it’s not too late. Since the podcasts are only 10 minutes or so, you can listen to a week’s worth in about an hour.

So get on it!

If Apple can’t survive without Steve Jobs Apple can’t survive. I hope Steve Jobs is at Apple for another couple of decades, but if he has to leave the leadership of the company, I am confident he has created a company and a culture that will survive him and thrive after he moves on.

So if you are within driving distance of the Rock Bottom Brewery in Long Beach, CA, USA, stop by and say hi!

You can also follow the action on Twitter.

[A] team of scientists says it has found new evidence that a comet triggered [an] extinction …13,000 years ago, when humans were around to witness the event and suffer its terrible consequences.

The researchers also think that when the comet exploded above the planet’s surface—ultimately killing off mammoths, saber-toothed tigers and other large mammals that roamed North America…

The paper, published in Science magazine, is also discussed at Scientific American.

If you haven’t already, you should head over to http://365daysofastronomy.org/ and subscribe to the daily astronomy podcast. The first episode is on the feed with another scheduled to publish tomorrow, and so on, every day for the rest of the year.

There’s also a calendar of events which is growing every day. Lots to see and do!

Two Eyes, 3D

It’s about stereoscopic vision and technology, what most people associated with “3D glasses”. It’s the center of my research interest in grad school. So if you are into that sort of stuff, check it out.

I guess it will have something to do with astronomy. My first stereoscopic research was done at the Adler Planetarium (hopefully to be published soon so you can read it) and my next research will likely involve galaxy simulations. I’ll describe it all in detail at the other blog. And I hope to write more for Slacker also. I’m done with classes in grad school now!

In summary:

Maximum Altitude Definition of 150 kilometers or 492,120 feet. This is in place of old rules about the maximum burn time below.
Suborbital Requirement. You can’t go into orbit without upping the amount of papework!
Not Cross International Boundary. Related to the above, you can’t cross borders with your rockets.
Elimination of Burn Time and Ballistic Coefficient Requirements. You don’t have to compute the density of your rocket or limit it by burn time.
Revision of Amateur Rocket Classes. There are now 4 classes of rockets, “Model”, “High-Power Rockets, “Advanced High-Power Rockets” and “Other”. The model rocket category no longer requires any notification to the FAA for launches. The maximum weight of a model rocket has gone from 16 oz. to 53 oz. and the maximum propellent from 4 oz. to 4.4 oz.

Here is a screenshot of the new classes of rockets:

All in all it looks like pretty good news for amateur rocketeers, especially those flying smaller rockets.

The article at The New Scientist makes a good point for commercial rocket programs as well:

The main importance of this for the entrepreneurial space community is the removal of the burn-time limit. With that change, many small rocket vehicles qualify as amateur rockets, at least for early development testing.

Now if we could only get the ATF to lighten up on the hobby.

As listeners know, I like to critique poor astronomy press releases. Part of the problem stems from writers who base entire articles on those press releases, with doing no vetting on their own. Can you imagine if political writers did that? They do? Okay, you’re making it hard to make my point, so I’ll distract you with shiny things and dangling string and get back to the topic at hand…

I want to throw a shout out to Clara Moskowitz at Wired.com for this article. It is a very simple article about naked eye astronomy this week. I find it a practically perfect astronomy piece. It doesn’t hype it but it still puts the event in perspective. It’s clear, correct and to-the-point. This conjunction was especially beautiful and I know many non-astro friends who commented on it to me. It was so well placed that the public was interested. Look at the comments she got on that post: 81 vs. the comments she got on her most recent post before that: 10. A story like hers will be a great gateway for the general public to learn a bit more - and perhaps come back later for more.

I only took points off for the obligatory Star of Bethlehem reference that every astronomy news outlet trots out every twelve months. But I can hardly fault her for getting into the Christmas spirit.

I haven’t read her stories before, so I’ve bookmarked her column and look forward to more. I checked out a couple of her most recent and they seem similarly clear, with some light humor thrown into each piece. She seems especially handy at headline writing.

Kudos to Clara. Wired, take care of her!

This is a little video from a project I’ve been working on. It’s, um, kinda-sorta related to space and stuff?

I could go on and on about Eta Car. It’s a fascinating system and one of the likely candidates for a nearby supernova in our lifetimes. For more info, a great place to start is the HST Treasury Program on Eta Carinae.

* 1664 Isaac Barrow
* 1669 Sir Isaac Newton
* 1702 William Whiston
* 1711 Nicholas Saunderson
* 1739 John Colson
* 1760 Edward Waring
* 1798 Isaac Milner
* 1820 Robert Woodhouse
* 1822 Thomas Turton
* 1826 Sir George Biddell Airy
* 1828 Charles Babbage
* 1839 Joshua King
* 1849 Sir George Stokes
* 1903 Sir Joseph Larmor
* 1932 Paul Dirac
* 1969 Sir James Lighthill
* 1979 Stephen Hawking

I wonder who is next?

PS - there’s a new podcast on the feed. Will be posting it here soon.

If you like astronomy and you like listening to podcasts then 2009 is going to be a very, very good year for you. Slacker Astronomy is going to be a strong supporter and contributor to The 365 Days of Astronomy Podcast, the Daily Podcast of the IYA.

The 365 Days of Astronomy Podcast is a project that will publish one podcast per day, 5 to 10 minutes in duration, for all 365 days of 2009. The podcast will be made available through an RSS feed. The podcast episodes will be written, recorded and produced by people around the world.
…
We are looking for individuals, schools, companies and clubs to provide 5 - 10 minutes of audio for our daily podcast. You can do as few as 1 episode or up to 12 episodes (one per month, subject, of course, to our editorial discretion). Our goal is to encourage people to sign up for a particular day (or days) of 2009.

So tell your mom, dad, child, grandfather, friend, school, troop, club or friend that you want to make one measly 10 minute podcast about astronomy to help out and, perhaps, be famous.

Ears around the world are counting on you.

So join in!

Hubble Space Telescope malfunctions, space shuttle repair mission uncertain, NASA says

I wanted to post the cartoon in this post but they probably don’t like that.

The 46 billion year part is only off by a factor of 4 or so.

In the meantime, I was thinking, it’s time to solicit openly what we’ve all been thinking — why is there no asteroid named “slacker” or “slackerastronomy”? We need some ambitious and slightly demented asteroid chaser to step up to the table and name an asteroid after us! Don’t you agree?

Cassini images reveal the existence of a faint arc of material orbiting with Saturn’s small moon Anthe.

The moon is moving downward and to the right in this perspective. In this image, most of the visible material in the arc lies ahead of Anthe (2 kilometers, 1 mile across) in its orbit. However, over time the moon drifts slowly back and forth with respect to the arc.

The arc extends over about 20 degrees in longitude (about 5.5 percent of Anthe’s orbit) and appears to be associated with a gravitational resonance caused by the moon Mimas. Micrometeoroid impacts on Anthe are the likely source of the arc material.

Andrew Fraknoi over at the ASP has put together a nice collection about women in astronomy. He describes it as “…a resource for those educators and students who wish to explore the challenges and triumphs of women [in astronomy] of the past and present.”

There are tons of really smart, really cool women astronomers doing outstanding work in astronomy. Often when you read about women in astronomy it’s about women of the past. It’s nice to see focus on today’s women astronomers. There are people like Wendy Freedman, pictured above, out there kicking professional astronomy ass as we speak.

Speaking of which, here is a YouTube video I found of one of my favorite astronomers, irrespective of gender, Dr. Roberta Humphreys, talking about women in astronomy.

Emily sums it up perfectly:

The longer I listened to the “great planet debate” last week, the more strongly I felt that if it were up to me, I would define “planet” to mean “everything in the universe that’s smaller than a star.” The fact of the matter is, every time I speak about any object visited by a spacecraft, I make frequent slips of the tongue. I call Titan a planet. I call Enceladus a planet. I’ve even called Tempel 1 a planet. They’re all wanderers, all places to visit. Subdivide it however you like — it makes sense to speak of giant (or Jovian) planets, ice giant planets, major planets, terrestrial planets, minor planets, dwarf planets, binary planets, whatever. But just look around at the people who call themselves “planetary scientists” and see what they study. It’s all of the above.

Then she goes on to show the relative sizes of some interesting “planets” in the solar system, using her interesting definition. Definitely worth a read.

We present the first resolved images of the eclipsing binary Beta Lyrae, obtained with the CHARA Array interferometer and the MIRC combiner in the H band. The images clearly show the mass donor and the thick disk surrounding the mass gainer at all six epochs of observation. The donor is brighter and generally appears elongated in the images, the first direct detection of photospheric tidal distortion due to Roche-lobe filling.

This is the beginning of a new era of imaging systems that have hitherto been observed (somewhat) indirectly. We understand systems like Beta Lyrae very, very well. But resolving the components is something new and quite exciting. The image on the right is Figure 2 from the paper and shows the images from both instruments as well as a model of the system.

So add this one to Google Reader and you’ll get a firehose of great astronomy blogging.

UPDATE: D’oh, I’m not the sharpest tool in the shed. Right now there is no RSS feed and eventually the site will be password-protected and access granted by request to editors of astro club newsletters and websites. So get it while you can!

I was going to write up a post about Polaris aka the North Star but Simostronomy beat me to it. In a nutshell, Polaris is a Cepheid variable star with a very low amplitude, so the brightness does not change very much. A new paper points out that the amplitude is increasing and Mike does a very nice job of explaining it.

One thing I like to do when under a dark sky like at a camp fire or floating in a boat is ask people to point at the North Star. Most people look for the brightest star and will point to it without giving any thought to the direction to which they are pointing! The North Star is due north of you everywhere you can see it and it is not the brightest star, by far. Its altitude above the horizon is equal to your latitude so here in Minneapolis it is 45 degrees above the horizon.

Besides it’s important (and temporary) role as the North Star, Polaris is one of the brighter Cephied stars and it appears to be going through changes in human time scales, which is always fun for astronomers.

So, thanks Mike! Now instead of blogging I can go play some Age of Conan.

If you have no idea what I’m talking about just ignore me!

The PayPal account I’m using I had set up previously and is called Tribe of Angels. It should be clear that you are donating to Slacker Astronomy but don’t get confused if you see references to Tribe of Angels.

Doug and I, with occasional contributions from Aaron, Beth, Travis and, perhaps, YOU, will continue to provide you with the road-less-traveled of astronomy news, interviews and commentary. Stay tuned and thank you for your support!

Dr. Vasily Belokurov of Cambridge University and his collaborators reveal the answer to be no in their recent submission entitled “Leo V: A Companion of a Companion of the Milky Way Galaxy” found
here. Interestingly, the head-shot of this newly discovered dwarf galaxy shows … nothing! The foreground field stars greatly outnumber the few much more distant evolved stars in the cluster and there is no visible concentration on the image.

Seems like a hard sell, but it isn’t. Belokurov’s team has mined a vast and very influential database of object brightnesses, colors, and spectra known as the Sloan Digital Sky Survey and then obtained follow-up observations to confirm their discovery. The database provides the ability to select out stars from the only-slightly-fuzzy, much-more-distant background galaxies and also precise color information. This latter capability was key to the success of locating the new dwarf galaxy - its stars were sufficiently metal-poor that many of the evolved ones were so-called “blue horizontal branch” stars. The concentration of BHB stars on the sky does make this patch of sky stand out - it indicates a grouping of stars of similar age and metal abundance.

The final clincher was getting radial velocities for the handful of brightest, coolest stars in the galaxy - the so-called “red giant branch” (RGB) stars. Objects within the dwarf galaxy are only moving a few km/sec relative to each other. On the other hand, foreground field stars from the Milky Way have radial velocity differences of tens to hundreds of km/sec since they are orbiting the Milky Way’s much more massive center at various distances and on a variety of orbits. Belokurov’s team obtained 247 spectra on the 6.5m MMT telescope on Mount Hopkins in Arizona and found five RGB stars close to the dwarf galaxy center with near-identical velocities. Score!

The new pup - not to be confused with pope - christened “Leo V” is 180 kpc (about 600,000 light years) distant and is moving away from us at a speed of 132 km/sec. But that radial velocity includes a component of the Sun’s motion around the center of the Milky Way galaxy. When solar orbital component is removed, Leo V ends up moving only about 60 km/sec relative to the center of mass of Local Group galaxies.

Intriguingly, Leo V is found projected on the sky only three degrees away from a very similar beast with the very distinctive name Leo IV - also discovered by Dr. Belokurov and his collaborators! The researchers point out that the proximity of these objects in Local Group space may foreshadow additional discoveries along a stream of such apparently faint and intrinsically low-luminosity objects which could then inform our ideas of the formation of the Milky Way galaxy.

I must point out another very cool use of Local Group galaxy data. You may recall from high school or college physics that if you know velocities and positions of objects and the forces acting on them, you can predict where they were in the past and where they will be in the future. For galaxies, the force is gravity and you can get good estimates of their masses from their brightnesses (corrected by a dark matter fraction). You can also assume that at some time around 10 billion years ago, all of the present-day galaxies were essentially at rest with respect to each other. Given 1) their three-dimensional positions now, 2) their radial velocities now, and the assumption of zero initial velocities way back when, you have enough “boundary conditions” to solve each of their paths in the interim. But - and this is a big but - there is no simple way to do it! One has to try out many, many configurations of starting locations, run the system forward and see if the radial velocities and positions you end up with are similar to those we see now. If not, throw the galaxies back in the box, shake and try again! If you are interested in such games, check out the references and citations in this paper. Leo V can now be added to the list of objects used, so we now have an excuse to re-run these models!

You’ve maybe heard of cataclysmic variable stars. They are binary systems where one of the stars is stealing material from the other star due to their close proximity. This material forms a pancake around the star called an accretion disk. We’ve never imaged one of these systems but we have a very, very good theoretical model of how they work.

Every once in a while that accretion disk gets unstable and essentially blows up in what we call an outburst. Sometimes these outbursts are extra bright and carry a signature in their light curve called “superhumps”. These are large oscillations in the light curve at a period very near, but not exactly equal to, the orbital period of the system.

On 6/30/08 one of these systems, VY Aqr, went into a superoutburst. This is a fairly infrequent event for this star. The outbursts themselves happen every few years and the superoutbursts less often than that.

I was heading out to my observatory when the word came in so I slewed my fancy 0.212m telescope (doesn’t that sound more impressive than 8.3″?) and got some data. So did a few other people and I downloaded all of their data from the AAVSO. If you click the image above a light curve will open in a new window. Let me explain it to you.

This is a phase plot using the superhump period of this star (P_sh = 92.7 minutes). So anything that happens 92.7 minutes after something else is plotted at the same phase. So the X axis is the phase of the superhump period and the Y axis is the brightness of the star. Because the star is getting dimmer, each day’s data is lower on the graph than the previous day. So each night is folded upon itself but each subsequent night is below the previous night.

You can see there are some interesting things going on! The superhump amplitude and phase change over time as the systems fades.

The latest papers on this object included Doppler tomography, new parallax measurements and spectroscopy from the Hubble Space Telescope. There is a lot of interesting physics in these systems and they are the subject of on-going study by astronomers. Including me!

The AAVSO has posted their Variable Star of the Season and this time around it’s FG Sagittae, a star that has given us an opportunity to watch it evolve over human timescales, something very rare in stellar evolution.

…many papers have detailed the remarkable evolution of FG Sge from a faint, hot, blue post-asymptotic giant branch star and planetary nebula in the making to a much cooler and brighter yellow supergiant. Even more exciting for variable star observers, following FG Sge’s four-magnitude brightening and several decades of relative constancy, the star now appears to exhibit the dramatic and seemingly random fluctuations and fadings of the R Coronae Borealis class of variable stars. FG Sge is clearly a star undergoing extreme changes, and we’re fortunate to be treated to its amazing show.

If you have access to a telescope you can go take a look for yourself!

Go read up and tell us what you think!

In order of receipt by yours truly and in the own very words of the author, notwithstanding some minor editorial discretion, here, then, are the proceedings:

From Slacker Astronomy:

Hi Michael,

Here you go - hot off the keyboard!

Regulus - Just when you think you know a star

Cheers,
Doug

From astroENGINE:

Hi Fraser,

My entry:
Title: “No Doomsday in 2012: The Reason Why Science Will Not Win”

Just a brief discussion about the recent 2012 articles and why science is fighting a loosing battle against the scaremongers

Cheers, Ian

From 21st Century Waves:

Hi Fraser,
Here’s a post: State of the Wave, Friday 6/20/08

I hereby officially volunteer to host the Carnival.

Best regards…
Bruce Cordell

From Centauri Dreams:

Hi Fraser,

I’ll send “Alpha Centauri and the Long Haul“:

This one is a look at projects in human history that have involved lengthy time spans, with relation to interstellar concepts like the Ultimate Project, a multi-generational starship that might take 10,000 years to reach its destination. The idea of long-term thinking in a short-term culture is explored.

All best,

Paul

From Music of the Spheres:

GeoEye-1 and TMA Notes

Music of the Spheres looks at the soon-to-launch commercial Earth-imaging satellite GeoEye-1 and at some details of its high-resolution optics.

From Free Space:

humm …

how ’bout this for this week: Metaphysically Speaking

Congress may force NASA to fly a canceled dark matter experiment, but it’ll have to be without a rescue shuttle available.

Thanks!

Irene

From Start With A Bang!:

The Moon looks huge!!
Because who doesn’t love the moon, really?

From Space Feeds:

This week’s space video of the week is the 1997 sci-fi/fantasy film The Fifth Element.

Space Video of the Day - 080623

Ed

From Nextbigfuture:

Article Title: The Space elevator games and the lunar lander contest preview for 2008

Summary: The Space elevator power beaming (climber) competition is on Sept 27, 2008 and the lunar lander contest is Oct 24, 25 2008. The main focus is on the space elevator climber teams and the progress towards a tether.

Brian Wang

From Orbiting Frog:

Fraser,

Crikey, the sixtieth must be coming up!

My entry this week would have to be the ‘Font Sizes of the Planets‘

Thanks,
Rob

From Cumbrian Sky:

Hi,

I’d like to submit this Blog post for your consideration for this week’s Carnival, please.

Title of Post: “The future’s not orange, it’s ICY…”

Summary: As exciting and important as it was, contrary to what many media reports have claimed, Phoenix’s spotting of ice on Mars wasn’t actually a “discovery” - ice had been seen on Mars by other probes over the years. But while the celebrations got into full swing in Arizona, NASA quietly released another “icy image” that received almost no attention at all, yet illustrated something possibly even more profound, giving us a tantalising glimpse into the future of space exploration and Mankind…

Stuart Atkinson

From Dynamics of Cats:

Holy Vanishing Crumbs, Phoenix!
yet another entry on Phoenix lander stuff

From A Babe in the Universe:

Aloha Carnival!
Endeavour returned to Earth June 14 with some spectacular photos from the Space Station.
“Photos From STS-124”

Mission STS-124 successfully installed the Japanese Kibo module. Human figures work on the Station in the ultimate high-rise project. We see the Shuttle docked at the Station, and a view of a place an earlier Endeavour once charted.

Thank you for hosting this week’s Carnival.
LOUISE RIOFRIO

From: Tyler at The Planetary Society:

Hi there,
Here’s my latest astronomy blog posting for the Carnival of Space.

Stop 14: Bryce Canyon National Park, Utah

This one talks about light pollution and astronomy outreach within the national parks.

Cheers,
Tyler

From the weblog of Columbus State University’s Coca-Cola Space Science Center:

Would you like to swing ’round a star?

Thanks!
– Rosa Williams

From Jeff Gortatowsky:

Star Party season…Or also know as fire season here in California. However being optimistic, it is star party season in the northern hemisphere. Coming up next week are two big star parties in northern California. The Golden State Star Party (GSSP) and the Shingletown Star Party (SSP). Both are held in an area that is one of of the darkest yet still accessible areas of the state. GSSP is currently booked up. SSP however still has room and day/night passes are available at the gate.

(Editor’s Note: It appears that SSP is “postponed until at least the end of August 2008″, according to their web site.)

From Astroblog:

G’Day

Title of Post: The Odyssey and the Celestial Clock

Brief summary: Has the date of homers Odyssey been found using the patterns of planets in the sky?

Cheers! Ian

From Emily Lakdawalla at The Planetary Society Weblog:

Hi there,

This week I’ll change things up and suggest you link to my weekly “What’s up” post, highlighting the current activities of all 20 of the active planetary space probes in and beyond the solar system. For the curious, that list includes: MESSENGER, Venus Express, Chang’e 1, Kaguya, Spirit, Opportunity, Phoenix, 2001 Mars Odyssey, Mars Express, Mars Reconnaissance Orbiter, Rosetta, Stardust, Dawn, Deep Impact, Hayabusa, Genesis, Cassini, New Horizons, and Voyager 1 and 2.

Happy Mars solstice! (And Earth, too.)

What’s up in the solar system for the week of June 23

–Emily

From Catholic Sensibility:

Hi Fraser,

If it’s not too late, here’s my entry for the carnival:

Satellite Imagination 1.6: Meet The Louisians

Cheers to all at UT

Todd

From goodSchist:

Hopefully this isn’t too late:

The importance of being Ivuna

Cheers,
-Chris

From Twisted Physics

This is a neat one with great discussion - Sean Caroll over at Cosmic Variance vetted the scientific points Jennifer discusses:

Devourer of Worlds

Best,
~Dave

From Beth Katz:

Hanny’s Voorwerp is an intriguing green blob that looks very much like “The Incredible Hulk”. You, too, can explore the Galaxy Zoo.

A little closer to home, aurora watchers have been forlornly hoping that the sun will get past its solar minimum and get some sunspots. In January 2008, NASA reported that Solar Cycle 24 had started. It seems that there has been little activity since then unless you count Tiny Tims. But the STEREO spacecraft caught stereo images of twisting solar jets. Those spacecraft have some amazing images. Maybe by the time the Solar Cycle 24 Conference rolls around in December we’ll see a few more spots.

Too many clouds? Test your knowledge of lunar phases with the lunar cycle matching phase game or these lunar phase activities.

UPDATE Oh noes! I forgot one!

Did I break some rule or offend the Gods?

I sent a blog to Fraser and one to you. You said you’d pick.
Did they both suck or what?

–
Mike Simonsen
Development Director
American Association of Variable Star Observers
www.aavso.org

So…

From Simostronomy:

Hey Michael,

You may have received an entry for me for the carnival, but you might consider this one in its place.

What Are Variable Stars?

–
Mike Simonsen
Development Director
American Association of Variable Star Observers
www.aavso.org

Many thanks to the hard work and good thinking of our submitters. It’s a lot of great reading for us to digest. I’ve never hosted a carnival before so I probably did it wrong. Please be kind to my mistakes. Authors, let me know if I made any errors or omissions with your submission and I will promptly correct.

Wanna join the Carnival of Space? Just send the URL of your entry via electronic Internet email message to carnivalofspace@gmail.com.

Cheers, beers and clear skies,
Michael

Regulus is the 22nd brightest star in the sky to the naked-eye. Since it lies along the path followed by the Sun, Moon and planets (called the “ecliptic”), bright planets frequently pass close to the line of sight to this majestic star. In fact, it is so close to the ecliptic that the Sun passes within a half degree of it every August. (Don’t go looking for this event visually! If you want to see how close, check out the movie from the SOHO satellite here. The brightest object - besides the Sun! - is Saturn. Regulus pops out from behind the occulting disk right at the end of the MPEG.)

I first became more closely acquainted with Regulus during my postdoctoral fellowship at the Dominion Astrophysical Observatory in Victoria, British Columbia (Canada). I would frequently use the 1.2m telescope with its fantastic high-resolution spectrograph. One of the shortcomings of filament bulbs is that there is precious little light emitted at the blue end of the spectrum - if you want to calibrate the pixel-to-pixel sensitivity of your detector, you can’t get enough blue signal without saturating the red end. What to do, what to do … One fine solution is to observe a bright blue star which is rotating so quickly that all of its spectral lines are smeared out over many, many pixels. Enter Regulus! The few spectral lines in its spectrum were already broad hydrogen lines and the rotation rate of over 300 km/sec smeared them out even more. A great star for calibration.

And a very poor one for measuring the line-of-sight (”radial”) velocity using the Doppler shift! In fact, astronomers last studied it for binarity in 1912-1913 - almost a century ago! Many hot stars are far enough away that lines from interstellar gas can be used as reference points for radial velocities. Not so Regulus - it is only 24 parsecs away and there just isn’t enough gas along the line-of-sight to this neighbor of the Sun.

Regulus came back into favor when its shape and the brightness distribution could be measured by a very cool kind of optical instrument called an interferometer. Work by McAlister and collaborators using the CHARA long-baseline optical inteferometer they created on Mount Wilson found that Regulus is rotationally-flattened and it spinning at 86% of the speed at which the surface gas would cease to be bound to the star. They were able to show that it was darker along the equator of the star, too. This high rotation rate was an anomaly for a star that was as old as Regulus (apparently 150 million years - pretty old for a star of this mass) since similar stars seemed to be fast rotators only early in their lifetimes.

So Doug Gies and his collaborators embarked on a new study using modern instrumentation to see if there was any evidence of it orbiting the center-of-mass of a binary system containing it and a hitherto-unknown companion. As a bright star, there was plenty of light available to be dispersed by high-resolution spectrographs. They used several in their study including two “unusual ones” - the Kitt Peak National Observatory Coude Feed Telescope and the Multiple-Telescope Telescope!

Let me briefly describe these two instruments. A Coude room is very high-resolution spectrograph capable of tearing the light from a telescope into very fine shreds of color. It was designed to be “fed” by the 2.1m telescope at Kitt Peak. However, observatories tend to do deep imaging around the time of New Moon (i.e. when the sky is dark) and the 2.1m served a variety of such needs. It was realized that the a smaller telescope could “feed” the spectrograph during these periods and that brighter stars could be observed with that smaller telescope plus Coude spectrograph while the big telescope was busy imaging!

The Multiple-Telescope Telescope at Hard Labor Creek in Georgia is another ingenious system for bright star spectroscopy. It has nine relatively inexpensive 0.33m mirrors which focus onto nine optical fibers which then feed a stable, bench spectrograph. Since it only studies bright stars, the mirror pointings can each be individually-tweaked to center up on the bright star. It uses a cheap alt-azimuth mount and collects as much useful light as a 1.0 telescope for a tiny fraction of the cost of such a large telescope.

So - you are asking - what did Doug Gies and his collaborators find? They found that Regulus was indeed a spectroscopic binary. Once every 40.11 days, the system completes one orbit. Regulus itself has a mass of about 3.4 times that of the Sun. The companion of Regulus is much less massive - only about 0.30 solar masses. Such a small mass object is either a low-mass star or a white dwarf. The latter possibility provides an explanation for Regulus’ rapid rotation! The idea is that the companion was once the more massive member of the pair and when it finished hydrogen burning in its core, it expanded dramatically and started losing mass to Regulus in a manner which “spun it up”. A mass of 0.30 solar masses is very low for a white dwarf - such objects are found only in systems where it is clear that much mass has been transferred.

A final piece of the puzzle fell into place when spectra taken using the far-ultraviolet Spanish satellite MINISAT-01 were re-examined. When the expected contribution from Regulus was removed, light remained in the ultraviolet region of interest - consistent with a white dwarf but not a cool low-mass star. So Regulus joins the list of bright stars in the sky (which includes Sirius and Procyon) having white dwarf companions and proves once again that “three out of every two stars is a binary”!

Their paper has been accepted for publication in the prestigious Astrophysical Journal Letters.

A Spectroscopic Orbit for Regulus
Doug Gies (GSU) et al

If you’ve got a space-related blog, you should really join the carnival. Just email an entry to carnivalofspace@gmail.com, and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community - and community is what blogging is all about.

Get thee to thy keyboard and get insightful on our asses! We need your awesomeness in our greedy little hands before June 26th, 2008.

What do you think of this?

We are entering a new age of Slacker Astronomy where we want to have the resources to travel and have support for acquiring the technology necessary to make interviews and other podcasts possible.

There are 2 main choices for this, that I know of:

1. Accept advertising
2. Solicit donations from listeners
3. All of the above

The only other possibility I can think of is a kinder, gentler version of #1 as is done by NPR and the like.

I think experience has shown that #2 is a hard nut to crack. People will show occasional financial support some of the time, but in terms of having on on-going revenue stream to support operations, everyone I know who makes money makes it via #1.

Which I think is both good and bad. The bad is web sites and RSS feeds which are littered with advertising. On some sites it is literally hard to find the content among the ads. Ads are annoying and advertisers getting more annoying all the time.

The good news is — I’m as reluctant to write checks as you are! If Meade or Swinburne can foot the bill, it makes it easier, in a way, for everyone. Most advertisers in the science/astronomy world are pretty good so you usually aren’t presented annoying, distasteful ads.

The bottom line for everyone doing podcasting and video podcasting is that you can achieve more with more resources at your disposal. So to the extent we want to do more and should do more, a little funding becomes important.

So brace yourself, I guess, for one of the above! We do want to do more with Slacker Astronomy so we will be thinking of ways to increase the resources at our disposal.

I had heard of Chris Lintott but I didn’t really know why. It turns out he is an astronomical celebrity in the UK due to his work on The Sky At Night. He is also one of the main people behind the very clever crowdsourcing project called Galaxy Zoo.

To the right is a photo of Chris and I at the AAS Meeting in St. Louis where we co-presented on several IYA New Media discussions and panels. We also drank a little too much one evening but on that subject I will say no more…

He was in Saint Louis and we had a lot of laughs. Apparently hanging out with me, Aaron, Phil, Pamela and Chris was infectious because Mike got home and started a blog: Simostronomy. Check it out!

Our friends Pamela Gay, Nancy Atkinson and Phil Plait have all the latest from this week’s meeting of the American Astronomical Society in Saint Louis.

I have a whole bunch of great video that I’ll be uploading in the next few days or weeks as well.

Interview: Rick Fienberg of Sky and Telescope (MP4, 42.8MB, 5:50)

I just came back from the astro-drinking-blogger meetup. It was a lot of fun. With apologies to the people my brain is too dim to name individually, there was a very nice group of people there including Phil, Pamela, Chris, Sean, Nick and Nancy.

I’ve had a couple of beers, if you’ll excuse me, but we are really lucky to have such a thriving and friendly community of astro-blogging. Note I don’t mean the bloggers, I mean you, the people who enjoy reading about astronomy.

The life astronomy improves is your own. I hear over and over from people — one of the major joys of astronomy are the human connections that we weave together. Understanding the universe is a compelling and important goal and I don’t understand why all people aren’t astronomers. Then I remember — they are. Everyone loves astronomy because you have to be bat-sh*t crazy to not appreciate the wonder, beauty and complexity of the universe.

So here’s a toast to you, Mr. and Ms. Astronomy Enthusiast. We aren’t just on a quest, we are on a quest together. It’s a lot of fun.

From AAS in St. Louis.

This is a walk through Pamela Gay’s very lovely house during a party she threw for astronomers in town for the AAS meeting. Who can you spot?

So limber up your pint lifting arm and c’mon down to the KitchenK Restaurant at 7pm on Tuesday, June 3rd, 2008.

So go visit the the 56th Carnival of Space! Maybe the Slackers can host it one of these days…

I upgraded the wiki software that runs Slackerpedia Galactica. Everything seems to be working OK. We had problems before where people couldn’t register as new users. I just tested that and it seems to work fine. Let me know if you have a different experience.

Let me say, the Slackerpedia Galactica astronomy wiki is really cool! It’s entertaining and informative and I don’t know of anything else like it. So please, take another look, add some articles, edit some articles and have some fun.

We also have a very simple Slackerpedia Galactica Facebook app.

Let’s bring it back to life. C’mon, everyone, follow me!

A Friendly Reminder: Spyside, the rock-duo featuring Ken Gardiner and Travis Searle (http://www.myspace.com/spysideband), appears this weekend on the television talent showcase “Community Auditions: Star of the Day” - http://www.communityauditions.com.

You have a few chances to watch, depending on where you are. For those not in the Boston/Providence/Portland area, we’re told that clips of individual performances will be available online at the Community Auditions website. (See URL above.)

FRIDAY MAY 16th -
9:30pm on TV38 WSBK Boston

SATURDAY MAY 17th -
10:30pm on WPXT The CW Portland, Maine
Midnight on WBZ-TV CBS Boston

SUNDAY MAY 18th -
Noon on TV38 WSBK Boston
7:30pm on NECN Boston Area

VOTE FOR US.
Voting is active from Friday after the episode premiers and lasts until airs to the following Friday morning, May 23rd. Votes count toward being included in the final episodes, where contestants compete for a car and a professionally produced record. **Everyone should vote as much as they can all week. Seriously. There’s no limit to how often or how many times you can vote, whether you saw the show or not.** Plus, voting is easy! You can do it in your spare time! Again, the website is:http://www.communityauditions.com/.

Feel free to pass this news on to any and all who might be interested. Thanks for the support!

–
TS/KG

Hell, just email us and we’ll help you pick out a great star. You want something hot? Massive? With or without a companion? Would you like an accretion disk with that? Or some planets perhaps?

Go ahead, name a star. Just don’t pay for it.

Whatever the hell is Slacker Astronomy (MP3, 17MB, 18:30)

As always, we welcome your feedback so email us if anything comes to mind.

Our own Doug Welch wrote a very nice article in the latest issue of Sky and Telescope called “How to Hunt for Supernova Fossils in the Milky Way“. I can’t find a link to the article itself but S&T has a post about the article.

It’s really cool stuff — an accidental discovery of supernova light echos in the LMC has led to a new way to look for and study supernovae here in our own galaxy.

Doug discusses in detail how you can help hunt for these elusive light echoes. It would be a great multi-year project for a small college astronomy program or for accomplished astrophotographers with a bunch of really nice equipment.

Doug also describes in the article what happens if you find a light echo:

What happens if you find a candidate light echo? You become my new best friend!

How can you pass that up?!?

Your driving down the road in an automobile. You have an odometer in the car which tells you how far you’ve gone (x). You have a speedometer which tells you how fast you are going (v). When you punch the gas pedal or hit the brakes, your car accelerates (a), getting faster or slower. All of these quantities are related through calculus. Let’s say you start at x=0 and drive at v=40 miles per hour for t=15 minutes.

x = vt
x = (40mph*0.25 hours)=10 miles

We can write this as x/t = v. The velocity is the ratio of the change in position (x) to the change in time (t).

In math instead of saying “change in x” we say “delta-x” . In calculus we take this delta to be infinitely small and instead of saying “delta-x” we say “dee-x” (and write dx). So when I write dx I just mean a ridiculously small change in position. dt means an instantaneously small slice of time. The equation v=x/t can be written with this notation as v=dx/dt. This means the same thing as above, it’s the same definition of velocity, but we are implying these infinitely small deltas.

Another way of saying dx/dt is to say “the time derivative of x”. This just means “how x changes with time”. If we assume that we are talking about time we can use a shorthand which means “how x changes with time” and that shorthand is simply a single apostrophe like this: x’.

Now we can write our equation above like this:

v = x’

But your velocity can change over time, too. If you are going 40 mph and accelerate to 60 mph, your velocity changes as a function of time.

v = at

For some length of time (t) you accelerated at a rate (a) and your new velocity is your original velocity plus (a) times (t). If we rewrite:

a = v/t

and using our notion of infinitely small deltas:

a = dv/dt

we find that (a) has the same relationship to (v) that (v) had to (x) and thus

a = v’ = x”

So we have:

x The position
x’ The velocity
x” The acceleration

The velocity is referred to as the “first derivative of x” and the acceleration is referred to as the “second derivative of x”. These derivatives have a mathematical relationship that is beyond the scope of this article.

Now to differential equations. These are equations where we see complicated relationships between values and their derivatives. An example is a falling object (m) reaching terminal velocity due to wind resistance. The force on this object (F=ma) is the difference between the gravity (g) of Earth pulling it down (-mg) and the wind resistance (k) getting stronger as the object falls faster (kv):

ma = kv - mg

For simlicity we divide by m and just let k = k/m:

a = kv - g

and now use our fancy notation from above:

x” = kx’ - g

or equivalently:

v’ = kv - g

In this equation the change in velocity is a function of the velocity itself. So to know the acceleration you need to know the velocity but to know the velocity you need to know the acceleration!

This is the conundrum of differential equations. Finding functions that, when you find their derivative, give themselves back.

If you solve the equation v’ = kv - g the answer you get is the velocity as a function of time. If you plug in a very long time, the velocity reaches a limiting value — the terminal velocity.

You can’t really solve this problem without differential equations. It turns out there are many, many things in the real world, in physics, biology and engineering, that can be explained with differential equations. From orbits to population growth to thermodynamics, differential equations are actually quite useful.

Congratulations if you stuck with me! If you guys are interested we can talk a little about differential equations in astronomy next time.

Thank you!

We have a new show in the works.

Michael

So, cheers, my brethren. Please toast my absence with proper British ale. For you dear readers on the right side of the pond, think about heading up to Cambridge tomorrow!

M.

Coupled together, these two items indicate that if there is an ocean beneath the frozen crust of the moon, then it’s reasonably warm, and rich in organic compounds. We don’t know how life started on Earth, but it’s a good guess that an ocean thick with organic compounds was involved at some point.

We don’t know how common life is and the possibility that life exists on Enceladus is quite small. Still, research in the solar system and in the deep oceans of Earth are suggesting some exciting new possibilities for environments suitable for life.

There’s more info from NASA and the AAVSO High Energy Network.

I’ve always wanted to take a shot of the moon during a total eclipse because it is the only time you can get stars in the background. Usually the moon is so bright that it drowns out all the stars. So I snapped a few photos tonight with my wife’s digital SLR. It didn’t have as much zoom as I wanted but I still got a bit of the effect I was hoping for. Make sure you click the image to see the large size. I’m looking forward to looking at all the other images that are popping up around the net.

The eclipse was very nice here in Minneapolis although it was cold  at around -2F (-19C). Did you get a change to take a look?

And then get out and experience the eclipse tomorrow!

Tom was a unique character and TASS was a project I got involved in early in my amateur astronomy days. He was recently awarded an honorary lifetime membership to the AAVSO, something that made him very happy. I had sent this to him when he told us about it on the TASS list:

Tom, I want to add my congratulations. TASS was the thing that accelerated my interest in variable stars. The AAVSO was there, too, but it was working on new TASS variables that really lit the fire under me. I’ve enjoyed your philosophy, as well, that the errors, mistakes and misfires should be just as public as the successes. It is too bad more researchers don’t share that view.

Thanks for the data, Tom. I know you enjoyed yourself and that is all that matters.

Check out CASSIE (Cassini at Saturn Interactive Explorer). It uses some weird plugin but once installed you can zoom around the Cassini timeline and watch the view from the spacecraft.

(Thanks Ben!)

Via Cosmic Log:

Ten years after supernovae provided the first evidence that the expansion of the universe is accelerating, a survey of more than 10,000 galaxies has provided independent confirmation that the cosmic speed-up factor known as dark energy is for real.

Cosmic Log provides a very nice analysis of this press release from the European Organisation for Astronomical Research (ESO).

So it seems that the expansion of the universe is indeed accelerating. This means that cosmological constant is non-zero and dark energy, or some alternate explanation, is necessary to explain the observations. Our cosmology seems to be consistent and correct in terms of what is happening, we just don’t know why it is happening.

In this case it looks like they got lucky and were able to catch RS Oph, a recurrent nova, in outburst. The surprise was — the dust:

The nuller saw no dust in the bright zone, presumably because the nova’s blast wave vaporized dust particles. But farther from the white dwarf, at distances starting around 20 times the Earth-sun distance, the nuller recorded the spectral chemical signature of silicate dust. The blast wave had not yet reached this zone, so the dust must have pre-dated the explosion.

“This flies in the face of what we expected. Astronomers had previously thought that nova explosions actually create dust,” said Richard Barry of Goddard, lead author of the paper on the observations that will appear in the Astrophysical Journal.

The team thinks the dust is created as the white dwarf plows through the red giant’s wind, creating a pinwheel pattern of higher-density regions that is reminiscent of galaxy spiral arms.

Novae have been studied for a long time and we thought we had them pretty much figured out. If confirmed, this result could trigger a lot of activity in the variable star community.

This was the Messenger spacecraft’s first of three 200km high fly-bys of Mercury. The next will be October 6, 2008, and the third will be September 29, 2009. Each fly-by slows the spacecraft as it heads to orbiting Mercury in March 2011.

Kevin B. Marvel, Executive Officer

The AAS is now making the invited and prize lectures at each AAS meeting available online for those who could not attend the meeting, but would still like to benefit from the invited and prize talks.

Audio and video versions are available at:
http://aas211.showmaestro.com/

The talks will be indexed on iTunes (under podcasts) by mid-March and also available on the AAS webpage.

These are very interesting talks by notable professional astronomers. At least one of the talks is aimed at the general public but almost all of them will be interesting to amateur astronomers in some way.

Thank you AAS! Nice to see you are “getting it” when it comes to making your content widely available on the Internet.

The BBC is reporting on an announcement from last week’s AAS meeting:

A giant cloud of hydrogen gas is racing towards a collision with the Milky Way, astronomers have announced.

Smith’s Cloud, as it is known, may set off spectacular fireworks when it smacks into our galaxy in 20-40 million years.

30 million years is tomorrow in astronomical terms. This interaction is taking place as we speak. These kinds of collisions, like our eventual collision with the Andromeda Galaxy, will keep our galaxy interesting for a very long time. In fact, it’s possible that our very existence is a result of a wave of star formation from such a collision.

So getting knocked around a bit is actually a good thing if you are a galaxy.

Our friends Pamela Gay and Fraser Cain from Astronomy Cast, along with astronomer/sex symbol/author Phil “The Bad Astronomer” Plait have all the latest from this week’s meeting of the American Astronomical Society.

My personal favorite of their reports: Hubble Sees a Double Einstein Ring

Are you on facebook? If so, you can add a new, highly-useless application which lets you view a random Slackerpedia Galactica article in facebook.

I wrote this just to test out facebook’s developer API, and it has been a fun little project. There is some really funny stuff in Slackerpedia Galactica and I’m glad we can share it easily with the facebook community.

So check out Slackerpedia Galactica on facebook!

In this case, a level 4 advisory would be issued at this time for asteroid 2007 WD5. Current calculations indicate a 1-in-75 chance that the asteroid will impact Mars around 10:55 UT on 30 January 2008 (all times Earth-based).

Earth scientists blame light from Earth’s Moon for impeding their observations of 2007 WD5. By early January 2008, they hope to have additional observations that will further refine the asteroid’s path. If Earth had an observatory on the far side of the Moon, maybe these calculations would take place in a more timely manner.

2007 WD5 passed by Earth in early November 2007 and was discovered on 20 November 2007 by the Catalina Sky Survey. It is estimated to be about 50 meters across.

Although the center of the asteroid’s predicted path appears to miss Mars by 50,000 km, that path’s uncertainty region is large enough to graze the planet. In comparison, 2007 WD5 missed Earth by 7.5 million km.

Earth scientists believe that the over-achieving Earth spacecraft that are on Mars are not in danger. MER Opportunity is near, but not in, the possible impact zone.

For further details, pictures, orbital animations, and updates refer to the NASA JPL’s Near Earth Object Program including this report on 21 December 2007.

In the beginning t equaled zero seconds (t=0). A Big Bang-like thing happened and the universe began expanding. It was very hot and very dense cold and empty^[1]. The universe expanded exponentially in a period known as inflation. Inflation ended around t=0.000000000000000000000000000000001 seconds.The universe was so hot that everything was relativistic and “radiation like”, so the universe was considered radiation-dominated.

At around t=1s neutrinos decoupled, meaning they stopped interacting with matter or radiation and just continued on their way forever. This is the elusive CNB — the cosmic neutrino background. Around the same time the ratio of protons to neutrons “froze out”.

At around t=200 seconds the temperature had dropped enough that deuterium could start to form. These were the first nuclei in the universe. This is the beginning of the era known as Big Bang Nucleosynthesis (or BBN). After less than 15 minutes, BBN ceased and the initial ratio of helium to hydrogen was established. The universe was now about 20 minutes old and for the next 50,000 years it was a hot bath of radiation and light elements that continued to expand and cool.

At t=50,000 years or so, the temperature got low enough that matter started to dominate the universe and by t=350,000 years the universe was entirely transparent to radiation, giving rise to the “last scattering surface” which we see as the CMB (cosmic microwave background).

By t=250,000,000 years or so, stars and galaxies had formed. The universe continued to expand and cool even as the the universe evolved to what we see today.

At about t=10,000,000,000 years, about 75% of the present age of the universe, matter ceased to dominate the universe and Λ (lambda) know as the ominous “Dark Energy” began to take over. Thus, the universe is not just expanding, it’s expansion is accelerating.

Currently t=13.7 billion years and the energy density of the universe is comprised of roughly 0.00008% radiation, 30% matter and 70% Λ, the temperature is T=2.7 degrees Kelvin and the Hubble rate, which is a measure of the expansion of the universe, is H=70 km/s per megaparsec.

^[1] My cosmology professor was kind enough to read my post and to this point he said “The universe wasn’t hot during inflation. It was actually cold and empty; the inflaton field was a condensate, totally different from a thermal bath; the best analogy is a Bose-Einstein condensate at T = 0. The condensate at the time t =0.000000….1 you say decayed. The decay products then thermalized to very high temperature.”

Black holes are the most likely source of the mysterious ultra high-energy cosmic rays that bombard the planet… Observations at the world’s largest cosmic ray detector suggest the particles are emitted by huge black holes in the middle of nearby galaxies. 

Cosmic rays are a pain in the ass for spectroscopy, astrophotography and other CCD-based astronomy. Especially spectroscopy is plagued by cosmic rays. There are 3 kinds of cosmic rays that I’m aware of, electrons, protons and Helium nuclei (or alpha particles). The cosmic rays discussed in this article are high-energy and create a shower of interactions when they slam into the earth’s atmosphere.Pretty cool that we are starting to see results out of the Pierre Auger Observatory.

Comet Holmes…was no brighter than magnitude 17 in mid-October…But the comet’s brightness has suddenly rocketed all the way up to 3rd-magnitude, brightening nearly 400,000-times in less than 24-hours!

Go try see it.

Lord knows we need more logic in this world!

This is only my second primary authored paper in a major astronomy journal. My others have all been in smaller journals. Many were refereed journals of good quality, but they tend to be limited in scope and/or size. PASP is a general astronomy journal. But even it has some areas where it is more known, two examples of which are astronomical equipment and variable stars. My paper, naturally, involves the latter.

SS Cyg is one of the most popular variable stars. It’s a binary system where a white dwarf is pulling material from a smaller, red dwarf companion. The material builds up in an accretion disc and leads to an eventual outburst, where the star grows in brightness by around 4 magnitudes or so. It’s fun to watch SS Cyg in a backyard telescope. Day after day it is faint, then one day BOOM, it’s one of the brightest stars in the field.

The best part is that we don’t know exactly why this occurs nor can we predict it with better than ~20% accuracy.

In 2005, I suckered invited some amateur observers to observe SS Cyg as much as possible, all night long, for four months. They observed many hours per night, in V and Ic (near infrared) filters. The idea was to look for any kind of activity that could be a precursor to an outburst.

The four months stretched into two years thanks to the dedication of this team (who are all coauthors on the paper). Thousands of observing hours were spent on this star. I don’t know of any star that has had this much coverage (other than our Sun of course). The amount of data broke our web server half way through the campaign! And it took me 4 weeks of 40-hour/week work just to clean the data and get it into a state to be analyzed.

The paper was written as part of an independent study class with a professor in the physics department at Tufts. A draft was done in May, polished over the summer and submitted in mid June. The referee returned comments about a week after submission. It took me about two weeks to respond to the comments and resubmit. After that, another week for notification of official acceptance and assignment of a publication date.

The result? We didn’t find a precursor. But we learned a ton and were able to place lots of limits. The referee said it would be an “important contribution” to SS Cyg. Lots of science (most?) is null results. But the null results lead to the positive results. We did find one significant result in the paper, though. There is a correlation between intervals between outbursts and a long (>1000 day) period in the long-term light curve of SS Cyg.

We are planning to apply for a grant to expand this project for three years. The goal will be to constrain the models even more with better and more precise coverage.

This will probably be my last primary-authored astronomy research paper in many years as I shift focus to education and psychology research. I have one more paper that is pending my corrections to a referee report, but I don’t know if that will happen given my time constraints. And I have one more idea in my head that I really want to do, because it would be fun and neat. But, again, time probably won’t let it happen. I have my first field study in the social sciences planned for this January at the Adler Planetarium in Chicago. After that, I’ll need to analyze and publish THAT data. Dealing with human subject data is a completely different world than data from the natural sciences. Even the statistical methods are different.

Onward… and upward?

Nothing could be further from the truth. Cosmology is a physical science and it is a rigorous science. While there are certainly mysteries and unknowns, cosmology is on a very firm basis and really doesn’t resemble philosophy in the slightest.

If you are interested, our textbook is very readable and was recommended to me previously by another cosmology researcher. It’s Introduction to Cosmology by Barbara Ryden. Dr. Ryden does a very nice job of laying out the context in the early chapters and then delving into the details of physical cosmology in the later parts of the book.

Today in class we talked about the evolution of the universe in 3 main eras — the radiation dominated early universe, the long matter dominated universe, when galaxies formed and the present era where the universe is dominated by “dark energy” (known to cosmologists as Λ). The radiation dominated era was quite brief, lasting only about 50,000 years. The matter dominated era was about 9 billion years long and Λ has dominated for about the last 4 or 5 billion years or so.

We know this.

Now, we can watch the International Space Station (ISS) and a wide variety of artificial satellites fly by. I’ve taken pictures of the ISS and Space Shuttle flying side-by-side. To me, it’s awesome that there are people living up there in space.

The Space Station is easy to spot when you know when to look and have good skies. Even a slacker can do it. It doesn’t zip by. You usually have enough time to find it moving slowly and steadily like a plane without flashing lights. It’s usually rather bright (around magnitude -1 to 1). Its shine is reflection of sunlight because it’s getting sun while you are in the dark. Sometimes you’ll see it big and bright and then “poof!” — it slips into the Earth’s shadow.

Visit Heavens-Above (http://www.heavens-above.com/) and find your location. Then under Satellites, click on 10-day predictions for ISS. If there are any passes over your location, you’ll get a table listing them. Realize that the times are in 24-hour time, so 5:47 will be 5:47am (too early for many slackers). A time like 19:54 is 7:54pm. Much better for slackers. Click on the date to get a map showing where to look. It’s easiest to see the passes that have a maximum altitude (center column) of 50-90 degrees but even the 15 degree high passes are readily visible.

In these crisp days of fall and spring, it’s fun to observe the skies above us with our own eyes rather than through a computer screen. Check it out.

In 1998 observations of Type Ia supernovae suggested that the expansion of the universe is speeding up. In the past few years, these observations have been corroborated by several independent sources: the cosmic microwave background, gravitational lensing, age of the universe and large scale structure, as well as improved measurements of the supernovae.

When Einstein developed general relativity, as is well known, he added a factor to his equation because it was necessary to reproduce the universe he thought we lived in — a static universe with no expansion or contraction. When we observed that the universe was not only expanding but accelerating in its expansion, that extra term in the equation was already there to express it.

That term is capital lambda (Λ). It’s a pressure term, in one way of thinking. Just like a gas or a fluid has pressure, it appears the universe has some sort of pressure. In another way of thinking, Λ is an energy because pressure and energy density are related in a linear way. So there is an apparently uncompensated energy that results in a universe that is out of balance — it’s being very slowly blown apart.

So, like dark matter, dark energy is “real”, in this case “real” meaning that it’s a name for something that we really do observe. Some people are uncomfortable with this. They think, in the example of dark energy, that we don’t need an extra term in the equation, the rest of the equation is somehow wrong. That is, of course, another perfectly valid option. Either physics is wrong or dark matter/energy exist or both!

But don’t be fooled — the phenomena are real. We really do find an unaccounted for gravitational influence (dark matter) and we really do see something acting like a pressure in our cosmology (dark energy). This is not philosophy, it’s science and it’s very good science at that. The fact that there are still things we don’t know is the fun part!

The thought I had was — would ancient people have been able to figure out that artificial satellites are artificial? That they are the products of design and not a part of the natural world? With the whole faux debate about evolution vs. intelligent design, the question arises: would scientists recognize design if they found it? Could Kepler have figured out that an artificial satellite was artificial?

I believe the answer is yes. In one sense, an artificial satellite behaves exactly like a natural satellite. But not quite. The geometry of a man made object is more perfect. I believe one could map the brightness changes, just like we do with asteroids, and come up with a good model of the shape of the object. It would take time and precise observations, but the non-natural nature would eventually become apparent.

So to the rescue are Michael, Doug and Travis. They will keep things running and add some new ideas of their own. I’ll try to contribute where I can, in between weekend benders of coffee and red bull.

Rebekah is still here, but she has been in another state most of the summer experiencing a fabulous surge in her professional acting/singing/dancing career. She even has achieved qualification for the much sought after actor’s equity card. Congrats to her!

Here is a glimpse into some of the stuff I’m doing at Tufts. The symposium is next week and I’ll post a report. Astronomy education research is a relatively immature field with lots of varying interests and philosophies.

We are going to decommission this discussion area. We are doing it for a few reasons. One, there just isn’t that much activity here and we don’t really use it for much on an official basis. Two, we’d like to start opening up comments on the blog posts. People are very used to that form of interaction. Three, we’d like you to consider writing an occasional blog post for the blog! If you register and ask us, we’ll promote you to a Contributor. You can write blog posts and if we like ‘em, we’ll put them on the blog.

There are tons of great astronomy discussion forums on the web, such as the Bad Astronomy and Universe Today Forum. Feel free to suggest others in the comments. We’d like to bring discussion here at Slacker Astronomy back into the blog, so please don’t be afraid to get discussions going in the comments of blog posts.

What makes this site such a good watch, or listen, or read, is that as well as being jokey and enthusiastic, there is a real depth of knowledge.

Thanks, Kate!

A while back I wrote a post about energy.

Here’s another example of energy that I think is interesting. When you take an automobile which is initially at rest and get it going 55 miles per hour, it gains kinetic energy. KE = (1/2)mv^2. So a car that weighs 2000 lbs. (900 kg) going 55 mpg (25 m/s) would have KE=(1/2)(900)(625)=280 kJ (kilo-joules) of energy. That energy comes at the expense of gasoline — chemical energy — exactly 281 kJ’s worth. Excluding all the messiness of friction and air resistance and such, we used exactly the same amount of chemical energy as we gained in kinetic energy. So it doesn’t matter if you use gasoline, hydrogren, electricity or biodiesel, it takes 281 kJ of energy to get your car going 55 mph.

Now you see a stop sign and you hit the brakes. You take all of that kinetic energy and put it into heat, given off by your brakes. The energy went from the gas into your car’s kinetic energy and then the friction from your brakes heated up the air. What some hybrids do, which is really cool, is instead of putting that energy into heating up the air, they put it back into the car. In some cases they literally spin up a big, heavy gyroscope. So they put the kinetic energy of the car into kinetic energy of a big spinning thing. Then when you hit the accelerator, it puts that energy back into the drive shaft and you accelerate back up to 55 mph without starting from zero energy. Cars that do this get “free” energy compared to cars that don’t. When we accelerate and brake, back and forth, all day long in our cars, we are throwing away ridiculous amounts of energy.

If you were flying in space instead, once you got going 55 mph you could turn off that gas and you’d keep going 55 mph forever (or until some force started messing with you). The reason you can’t do this on earth is because all sort of things steal the energy. The heat from your engine, friction in the moving parts, air resistance — they all steal energy that you have to keep putting back with your engine.

So one of the challenges facing us with our on-going “energy crisis” is figuring out how not to turn energy into a form that is not usable to us. The classical example is heat, like the brakes on our car. Anything that gives off heat is wasting energy. Your laptop wastes tons of energy in heat. If they could make CPU’s that didn’t heat up, your battery would last for days.

There is no shortage of energy on earth. The Sun rains down something like 1 kilowatt per square meter. There is tons of kinetic energy in the wind and ocean. We like to burn things like coal and oil –they are ridiculously finite compared to the Sun, the wind and the ocean. Renewable energy isn’t just a good idea, it’s the only long term option.

The BBC reports: Dark matter clues in oldest stars:

“In cold dark matter the particles move very slowly; in warm dark matter they move very quickly,” he explained.

“We found that if the dark matter consists of these fast moving particles, then the first stars form in very long, thin filaments…Some of the stars that formed within the filaments would have had a relatively low mass, which is of interest to astronomers as they have a long lifespan and could still survive today.

Dr Theuns added: “In stark contrast, what happens in (the simulation with) cold dark matter is very, very different. Here, the first stars formed in little lumps of dark matter, and just one star per dark matter lump. And these stars are probably very massive as well: 100 solar masses. Because these stars are so massive, they die very quickly; so you wouldn’t find such stars in the Milky Way today,” he said.

Everything I’ve read about the “1st stars” (or Population III stars) is that they would have been very massive because they lack metals (elements heavier than Helium). The stars that followed them (Pop. II and Pop. I) had access to heavier elements created by the supernovae of the Pop. III stars and evolved differently as a result.

What’s important here, as I read it, is that we have a “1st stars” option which creates low-mass stars that could still exist today. So finding such stars could tell us something about dark matter.