Forums / General Discussion Forums / Citizen Sky in General / W UMa - another eclipsing binary star
W UMa - another eclipsing binary star
Over on the AAVSO web site they have posted a new Variable Star of the Season article about W UMa.
Like our friend epsilon Aurigae, W UMa is an eclipsing binary star. It's so popular that it is actually the prototype star of an entire class of variable star. When astronomers discover a new star and say "That's a W UMa", they mean it's an eclipsing binary like this one. But it has lots of differences with epsilon Aurigae too. For example, W UMa consists of two stars that are so close together that their period is on the order of 8 hours. Compare that to epsilon Aurigae's 27 years! In fact, they are so close that most astronomers think they actually touch each other. What does that tell you about their orbital speed? What might that type of speed do to a star's structure?
This cool illustration of a W UMa system is by Dr. Dirk Terrell. He's an astronomer with an expertise in eclipsing binary systems who also happens to have a nice touch with the canvas. :) Maybe we'll see if we can get him to join us for an upcoming chat session.
Check out the article for a nice description of the history of the system, the unanswered questions and other neat background on eclipsing binary stars. Then come back here and post any questions/comments you have!
There are lots of fun W UMa stars to observe. I put them on my observing list regularly. Here are my 4 favorite Winter stars of this type. You need a telescope to observe them, but YY Eri can be done with 15X or higher binoculars. EQ Tau is right outside the eyepiece field for the Pleiades, M45. YY Eri is in the same eyepiece field as #39 Eri. RZ Tau is just north of Aldeberan (Alpha Tau). ER Ori is between the 2 bright stars Rigel (Beta Ori) and Beta Eri. YY Eri and ER Ori are 2 of my absolute favorite eclipsing binary stars. I have observed them for for over 30 years. You can check the AAVSO web site for predictions of times of minima. http://www.aavso.org/observing/programs/eclipser/eb2010.pdf (Bookmark this web address- it covers all of 2010) Enjoy these 4 stars and submit the observations via WebObs on the AAVSO web site www.aavso.org Each star should be observed every 10 minutes for 1.5 hours before minimum light and 1.5 hours after minimum light. Each of these will take 3-4 hours to observe and will give a nice light curve. Charts can be generated from the VSP Variable Star Plotter on the AAVSO web site. Good Observing. Chris Stephan Robert Clyde Observatory Sebring, Florida USA