The comet is growing

A nice time series of Comet Holmes from a fellow member of the Minnesota Astronomical Society.

Orbit

Where’s the comet? Right here.

Naked Eye Comet

The folks over at space.com are reporting on a comet that has brightened ridiculously and is now visible to the unaided eye.

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.

Speaking of EPO…

Education and public outreach (EPO) is very important. If it interests you, you may want to check out the new issue of Astronomy Education Review, which describes itself as “a lively electronic compendium of research, news, resources and opinion”. One article that looks interesting is entitled Teaching Scientific Logic: Theories and Observations.

Lord knows we need more logic in this world!

Publishing

I’ve had a paper accepted for publication in the December, 2007 issue of PASP, a top tier astronomy journal. You can read it here. (Notice a fellow slackerpede in the coauthor list.)

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?

Physical Cosmology

I am taking a cosmology course, which explains my recent (and probably upcoming) posts on cosmology. One thing people ask often is whether cosmology is metaphysics or philosophy more so than a science. It is hard for people to comprehend that we can test our theories in cosmology even though we can’t rerun the experiment.

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.

Spotting the Space Station

Until I saw the movie “October Sky,” I hadn’t realized that people went out and saw Sputnik fly overhead 50 years ago.

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.

Dark Energy

“Dark energy” is the phrase we use to describe an observed phenomena. That phenomena is the acceleration of the expansion of the universe. Wikipedia explains:

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!

Wow

Check out these amazing photos of the recent space shuttle mission.

A Question of Design

We recently passed the 50 year anniversary of Sputnik. The fact that we (the human race) were able to get an artificial satellite orbiting the planet represented a major leap forward. You need to understand physics and harness a lot of energy in just the right way to get out of the gravity well. We did it and the 50 years since have been amazing as a result. We currently have over 3000 satellites orbiting the earth.

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.