Predictions suggested the total eclipse phase of epsilon Aurigae should have arrived as early as mid-December [JD 2,455,190], but observers are still reporting a slow fade even now in late January [JD 2,455,220]! What's going on?
The answer includes the notorious "out of eclipse" variations -OOE- which are still lurking in the eclipse light curve. These have amplitude of one-tenth magnitude (or more) and a quasi period of two or more months. By using a 5 to 10 day mean in plotting the visual light curve data, you can see evidence for at least one local maximum around JD 2,455,160. The excursion from a straight line during ingress is only ~0.05 mag, but it takes only a small size variation or an even smaller temperature variation in the F star to cause that kind of variation.Read more
The chat transcript to the January 12, 2010 chat discussing the remaining questions after the exciting press releases at the AAS meeting is attached as a pdf document to this blog posting. It was really an exciting chat with several good questions being asked! The original chat advertisement follows:Read more
Observers are reporting signs that epsilon Aurigae's light has plateau'd during the past week or so, suggestive that second contact was reached - that is, the dark disk now stretches across the nearly 1.5 astronomical unit diameter F star. Exact time of second contact can only be determined in hindsight, but the change in the rate of decline is noteworthy. Comparison with last eclipse is informative, although the data density is somewhat less. In part, second contact was not the final, minimum brightness for the system. Rather, another drop of 0.03 mags happened about a month after the initial minimum, then a slow decline over several months until so-called mid-eclipse brightening started around mid-eclipse (and the seasonal close approach of sunlight made those observations very difficult).Read more
This morning, Donald Hoard (Spitzer Science Center) reported on an analysis of a large set of multi-wavelength measurements (ultraviolet, optical and infrared) that provide important insight into the components that comprise the epsilon Aurigae system. Dr.Hoard spoke about this work at the Adler meeting of Citizen Sky August 2009 and you can find the video of his talk on the website.Read more
Citizen Sky has issued a press release (in english and espanol) with an update on the project and including new artwork (including one image created by the aesthetic solutions team). This is being released at the Jan. 3-7 American Astronomical Society (AAS) meeting, billed as the largest meeting of astronomers ever. Citizen Sky will be well represented there through posters, talks and press conferences. We will also be wandering the halls looking for neat news updates to bring you regarding epsilon Aurigae and other astrophysical phenomenon. Stay tuned during the week for reports!
And don't forget to continue your observations!Read more
Did you observe the palindromic date this weekend, 01- 02- 20 10 ?
If you have been observing the steady decline of the light of epsilon Aurigae this autumn, you might wonder if it too will be palindromic - that is, the brightness symmetricaly rising during egress early in 2011, as steadily as it declined during ingress autumn 2009. Short answer, probably not. Among the many wonderful conundrums surrounding epsilon Aurigae is that the eclipse is asymmetrical - egress tending to be fast than ingress.
This difference is thought to be due to asymmetries in the disk - somewhat less well defined on the trailing edge that we'll see later in 2010 and during early 2011 as eclipse ends, relative to the leading edge this past few months.Read more