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parallaxicality
2010-Mar-19, 10:21 AM
We're about halfway through the eclipse period; I would have thought there'd be some info by now?

Hungry4info
2010-Mar-19, 08:25 PM
I would have figured they would wait until it was finished to write up papers.

EDG
2010-Mar-22, 02:32 AM
Hm? What's interesting about Eps Aurigae? (genuine curiosity, I've not heard anything about it)

Sardonicone
2010-Mar-22, 02:56 AM
Hm? What's interesting about Eps Aurigae? (genuine curiosity, I've not heard anything about it)

What he said. Now I have to go a-googlin' to see what the fuss is about.

EDG
2010-Mar-22, 03:20 AM
looking it up, here's what wikipedia says is the latest news about it:

from: http://en.wikipedia.org/wiki/Epsilon_Aurigae

At the January 2010 meeting of the American Astronomical Society, Donald Hoard of NASA's Spitzer Science Center at the California Institute of Technology in Pasadena has reported that observations from NASA's Spitzer Space Telescope along earlier observations point to the primary being a post-asymptotic giant branch star with about 2.2–3.3 times the mass of the Sun periodically eclipsed by just a single B class star inside a disk.[1] This was accomplished by pointing Spitzer at the star using the corner of four of Spitzer's pixels, instead of directly at one, to effectively reduce the telescope's sensitivity and preventing the star from overloading the telescope, then using exposures of one-hundredth of a second, the shortest duration images that can be obtained by Spitzer. The data supports the presence of the companion star's disk, and establish the particle sizes as being like gravel rather than like fine dust.[7]

Hungry4info
2010-Mar-22, 04:10 AM
Some discussion (http://solar-flux.forumandco.com/extrasolar-news-and-discoveries-f2/epsilon-aurigae-s-transit-t367.htm) on it.

Hungry4info
2010-Mar-23, 01:45 AM
Some news.
http://arxiv.org/abs/1003.3694

EDG
2010-Mar-23, 03:44 AM
What's a "post AGB star", exactly? I thought the AGB phase was the last one before the star became a white dwarf (or exploded as the case may be)?

EDIT: Huh. so if I follow the paper correctly, the F component was a 7 solar mass B V star originally, that evolved into a red giant and AGB, but overflowed the roche lobe and lost about 5 solar masses (possibly from the L2 Lagrange point of the system) and then additionally had a stellar 'hiccup' that caused it to dredge up some hydrogen and start burning that again which explains why it's an F giant and not an M giant, but is somehow bloated in size way more than it should be for a star of this mass.

Seems a bit... unusual, but I guess weird things can happen once somewhere, right ;)

Hungry4info
2010-Mar-23, 04:27 AM
What's a "post AGB star", exactly? I thought the AGB phase was the last one before the star became a white dwarf (or exploded as the case may be)?

Pretty much. AGB is the Asymptotic Giant Branch, describes the shape of the line of AGB stars on the HR diagram. Post AGB stars have given up being red giants (social pressure, "ha ha you're fat"), and are becoming white dwarfs. Not quite degenerate yet, but soon.

(all that being IIRC)

EDG
2010-Apr-07, 07:22 PM
This is on UT today (http://www.universetoday.com/2010/04/07/astronomers-image-mysterious-dark-object-that-eclipses-epsilon-aurigae/), but wow! Look at those images! That is quite spectacular, seems pretty certain that there's a dark disk around Eps Aur.

http://www.cbc.ca/technology/story/2010/04/07/tech-space-star-eclipse.html

AtomicGogol
2010-Apr-08, 02:43 AM
I just checked that out. Based on what those photos show, wouldn't the dark object have to be something orbiting an object that is itself orbiting Epsilon Aurigae? I'm basing that on the appearance, from our perspective, that the object is sort of elliptical, and that wouldn't be the expected shape of a uniform disk orbiting EA itself.

Then again, that may be just what they WANT us to think...

01101001
2010-Apr-08, 04:53 AM
[...] wouldn't the dark object have to be something orbiting an object that is itself orbiting Epsilon Aurigae?

Pretty much the prevailing.


One theory has been that a large opaque disk seen nearly edge-on eclipses the primary star. The new images from an instrument developed at the University of Michigan appear to confirm that theory.
[...]
Because astronomers hadn't observed much light from it, one theory is [...] But the prevailing theory labeled it a smaller star orbited edge-on by a thick disk of dust.

EDG
2010-Apr-08, 05:42 AM
I'm just amazed that they can actually make out that the disk is partially eclipsing the star!