A white dwarf in the making

By Michael on July 8, 2008 at 2:28 pm | In Astrophysics, Blog Posts |

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!


2 Comments »

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  1. Sure, you can take a look for yourself, but you’ll need a pretty large telescope. The star is currently below 15th magnitude, so something in the 16″-20″ range, or larger, would be advisable. And you’ll need a better chart than the AAVSO one linked here, which is for a small telescope and only shows stars down to magnitude 10.

    But, that said, FG Sge is certainly an amazing variable. I remember observing it in the 1970s, when it was an easy object in a small telescope. Even at that time, the idea that it seemed to be racing across the HR diagram like an express train seemed totally unbelievable.

    Peter Hornby

    Comment by phornby — July 8, 2008 #

  2. Yes, it is a bit dim lately, isn’t it. But that could change! :)

    Comment by michael — July 9, 2008 #

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