Epsilon Aurigae's transit

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Epsilon Aurigae's transit

Post by Stalker on 28th August 2009, 5:40 am

News is a bit ancient

Every 27,1 years, an unknown star eclipses the star Epsilon Aurigae. New eclipse began 6 aout.

The second star may be twin B stars surrounding by a disk of dust. the disk is hollow in the center and planets can form in the disk.

Phenomenon is visible with any instrument and even in the bare eye.
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Re: Epsilon Aurigae's transit

Post by Sirius_Alpha on 28th August 2009, 8:45 am

Do you know if there's any attempt to look for planet transits?

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Re: Epsilon Aurigae's transit

Post by Stalker on 28th August 2009, 10:01 am

Sirius_Alpha wrote:Do you know if there's any attempt to look for planet transits?

Why not? I know that the material of the disc becomes thinner every time and that some people think that it is because of a planet
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Re: Epsilon Aurigae's transit

Post by Lazarus on 28th August 2009, 1:49 pm

I really doubt there's any possibility of detecting a transiting planet. The supergiant is huge, so any transit dip would be very small anyway, and it is also variable. The secondary star or stars contribute negligibly to the light of the system, plus B-type stars aren't exactly small either, and you may well have two of them located close together.
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Re: Epsilon Aurigae's transit

Post by Sedna on 28th August 2009, 2:55 pm

It's not impossible that the system has or will have planets (I am watching an artist's rendering of the system while I write these words), but if it has planets, these planets are in a very bad place, 'cause the star will explode to a supernova in a near future. And it's not impossible that it already exploded to a supernova (remember the distance of 2,000 ly).

If there are planets far enough of the star so that they will be not completely destroyed, we will be able to detect the remaining cores of these planets (while their gaseous enveloppes will have been wiped out) when the star will be a pulsar (but looking at its mass, there's more chance that the star will become a small black hole).

The best we can do in 2009 and in the next decades is to wait and hope that when the system's judgement day happened (maybe in a hundred years or in a thousand years) there will be a A. Wolszczan-type guy who will look at the remnants of the Epsilon Aurigae system.

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Re: Epsilon Aurigae's transit

Post by EDG on 22nd March 2010, 12:24 am

Can planets even form in such a short timescale, especially around a B star with pretty strong stellar winds? (tbh I'm surprised there's still a disk around the B Star in the first place)

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Re: Epsilon Aurigae's transit

Post by Sirius_Alpha on 22nd March 2010, 2:21 pm

I'd expect you could get a few planets through disk instability, that tends to be a rapid planet-forming process, but usually only puts out high mass planets or brown dwarfs. This assumes a massive disk.

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Re: Epsilon Aurigae's transit

Post by Sirius_Alpha on 22nd March 2010, 9:45 pm

Some news.
http://arxiv.org/abs/1003.3694

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Re: Epsilon Aurigae's transit

Post by Stalker on 23rd March 2010, 2:57 am

a 2.2+0.9/-0.8 Msun F type
post-asymptotic giant branch star, and a 5.9+/-0.8 Msun B5+/-1 type main
sequence star

WTF? The 5.9 Msun star might be more evolved than the 2.2 Msun star! Weird...
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Re: Epsilon Aurigae's transit

Post by Sirius_Alpha on 23rd March 2010, 3:35 am

The 5.9 M_sol star burns its fuel faster, progressing along the HZ diagram at an accelerated rate.

But apparently the lighter star is more evolved.
Hmm.

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Re: Epsilon Aurigae's transit

Post by Lazarus on 23rd March 2010, 11:24 am

What's so weird about the less massive star being more evolved? It happens all the time. E.g. to take an example from one of the nearest star systems, Sirius A = 2 solar masses, Sirius B = 1 solar mass. Sirius B is the more evolved star, being a white dwarf.

Mass loss is a well-known phenomenon at the end of stellar lifetime, and if the F-type star in Epsilon Aurigae is a post-AGB star, it has undergone and is probably still undergoing significant mass loss.

(And that's even before you get to the fun you can have with mass transfers in close binary systems, e.g. Algol paradox)
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Re: Epsilon Aurigae's transit

Post by EDG on 26th March 2010, 12:20 am

Yeah, but this one's really weird. Post-AGB stars should be (a) red and (b) on their way to becoming white dwarfs, but this one's had an internal hiccup and has started burning hydrogen again somehow, which is making it yellow/white instead. I don't really get why this makes it 135 solar radii though.

The B5 V isn't "more evolved" though, it's still a main sequence star - the F star is more evolved because it's at the end of its lifespan. It probably started off as a 7-9 solar mass star (an early B V).

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Re: Epsilon Aurigae's transit

Post by Edasich on 26th March 2010, 9:49 am

Dunno if offtopic, but I post Epsilon Aurigae model of mine. To be accepted at Celestia Motherlode Smile

Bright third star in background is LY Aurigae, a luminous eclispsing binary of B spectral type, 360 light years away from Epsilon Aurigae.




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Re: Epsilon Aurigae's transit

Post by Sirius_Alpha on 7th April 2010, 5:01 pm

Well that is cool.
http://www.universetoday.com/2010/04/07/astronomers-image-mysterious-dark-object-that-eclipses-epsilon-aurigae/

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Re: Epsilon Aurigae's transit

Post by Lazarus on 8th April 2010, 5:19 pm

Sirius_Alpha wrote:Well that is cool.
Seconded. Interferometry is amazing.
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