Prof. Tushar Prabhu
Professor-in-charge, Indian Astronomical Observatory, Hanle, Indian Institute of Astrophysics, Bangalore
5:00 PM, 22nd of September 2009
"Bright star, would I were steadfast as thou art", said Keats, in 1838.
Awareness about the story of the intriguingly variable and anything but steadfast - Epsilon Aurigae - starts around that time. And, variable stars were known to humanity, perhaps, from the earliest times that the oldest science of all - Astronomy - used simple naked eye observations of the sky as a beginnner's tool.
A number of stars were observed, to have varying brightness. Keener studies revealed that the variations in brightness could have many causes - some stars were deduced to be in a binary or a multiple system and went through regular periodic eclipses, some stars were intrinsically variable, arising from pulsations of the star and large variations in it radius and surface area, some were cataclysmically or irregularly variable, and so on.
Not usually so interesting as intrinsically variable stars, eclipsing variable stars are well understood in terms of the partial eclipsing of the brightness of the primary component, and the patterns in these variations are in general rationalised satisfactorily. Except for one puzzling object which defies all the usual understanding of binary or mutiple star systems. This object is Epsilon Aurigae - a relatively bright and well known star whose brightness varies over timescales of about 27 years!
Be at the Planetarium, to go through a tour of variable stars and their intricacies, and in particular, understand the whirligig of puzzling observations from Epsilon Aurigae.
What is more, be at the planetarium for this public lecture at 5 PM on the 22nd of September and also for the workshop to be held from 9:00 AM - 12:30 PM on the 4th of October, which will help anyone with a little interest in the skies, to contribute some citizen observations of this star, as part of a worldwide project.
The above is an image of the constellation Auriga taken from the vicinity of the Sound and Light show at Amber Fort, Jaipur. The bright star is capella. Epsilon Auriga, the apex of the small triangle of stars known as "Kids of Capella" can be seen. The inset going out from this star leads to an illustration of this system adapted from the Sky and Telescope - which depicts a thin disk of dark material in a binary orbit around the star Epsilon Auriga.
Well, this is the current wisdom about this star. But, there are unanswered questions!