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Has anyone seem Gamma Andromedae C?

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#1 azure1961p

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Posted 04 October 2013 - 11:03 PM

Has anyone recently been able to see the companion to Gamma Andromedae B? In the 90's when the distance was 0.5" between them I not only saw the differing sized spurious discs but a distinct color contrast - B was of course that vivid blue and the companion was an ashy grey white. The grey was a contrast effect of the brighter primary and it looked for all the world like it was a birthing from Gamma B. Perhaps the most beautiful sub arc second view Ive ever had. Now its buried in the blue. I look at the Delta-M and give up on even attempting such a close seperation: 0.1". But that's with an 8" scope. Some of you guys out there have some serious aperture.

Can ANYONE here see gamma Andromedae C? Even a bump?


Thanks in advance.


Pete

#2 fred1871

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Posted 06 October 2013 - 08:03 PM

Pete, it seems very unlikely that Gamma Andromedae BC is within range at present for the usual run of telescopes that amateur astronomers can muster. Maybe if someone has access to the Lick 36-inch refractor on a suitably steady night.... otherwise, I think it'll be a waiting game until the pair get wider (a comparative term in this case) again.

The ephemeris (6th orbit Catalog) gives ~0.1" and closing at present; down to 0.02" (yep, 2/100 of an arc second) for 2015.0; so getting back to the realm of likely amateur observations will be a few years away yet.

Running a version of the orbit ephemeris (estimate, not claimed dead accurate), the pair will hit 0.2" by 2020 (within reach for David Gray and Christopher Taylor and...who else???); 0.3" around the end of 2022; and will reach 0.4" by 2027. Widest separation, just over 0.5"/approaching 0.6", will be in the 2040s.

The fun is finding at what stage of the orbital widening it can be seen double with a particular telescope. An 8-inch will likely show it as a bare contact pair (Dawes Limit effect) by the late 2030s. The 8-inch, for a 0.5-Rayleigh elongation (~0.35") can make the attempt in 2024, a much shorter wait. To match David Gray's view of A2145, well elongated at 0.17", that'll be the separation for Gamma And BC in late 2018 - only 5 years away.

And to make it a bit easier, the stars are not hugely different in brightness - delta-m ~1.2 - more like Chi Aquilae than - ummm... - BU 67 in Cygnus (Dm ~3.0) or 90 Her (Dm 3.5) - to not mention the "he who must not be named" pair. :grin:

#3 David Gray

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Posted 07 October 2013 - 07:22 AM

I used to enjoy showing this off with the D-K to experienced visitors. Last, rather casual look, was some 5/6 years back when it would have been c.0.3" and got them well: near-split. Often got C as a little more toward green than striking-blue B.

Looked two nights back in 8/10 seeing -quite round!

David.

#4 azure1961p

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Posted 07 October 2013 - 07:37 AM

Thanks Dave. I was hoping you'd respond here given the aperture and all.
So its not even hinted at with a 16" - oh well - such is an orbit.

Pete






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