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C*2801

thn's picture
thn
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Joined: 2013-08-17

Hello!

Lately I'm observing carbon stars and I stumbled about this exotic object from a list of carbon stars by C. Buil. It is originally mentioned in the study: STEPHENSON C.B., New carbon stars found in a hemispheric survey, Astron. J., 90, 784-786 (1985). This object is cataloged by Simbad as C*2801 with Bmag: 16.3, Vmag: 8.3. It can be found on images of the DSS as a bright object (brighter than HD 338995, see below). Since then this object must have lost magnitude. It is cataloged as GSC2.3 N2F7000066 (2006) with Bmag: 16.23, Vmag: 11.6.

I looked it up in the sky on Sunday with a 10"-reflector but could only find the neighboring star HD 338995, Vmag:10.63. Question: Is anything more known about this object? Has it been observed over a longer time? Is it worth observing?

If this is not the correct forum for this inquiry, please put it at the right place. Thanks in advance for any help.

Greetings, Thomas

ASAS J194845+2608.4
Sebastian Otero's picture
Sebastian Otero
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Joined: 2010-09-19

Hi, Thomas,

It is in VSX as ASAS J194845+2608.4.
http://www.aavso.org/vsx/index.php?view=detail.top&oid=116954

It varies between V= 11.7 and 12.6.
This is its light curve in the ASAS-3 survey:

http://www.astrouw.edu.pl/cgi-asas/asas_variable/194845+2608.4,asas3,175.4,4320,500,0,0

Forget about the 8.3 mag. figure. It's probably a mistake or a non standard magnitude.
It may have been slightly brighter or fainter but consider it as a 12th mag. star.
That's why you didn't find it.

Cheers,
Sebastian

C*2801 DSS-picture
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thn
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Joined: 2013-08-17

Thank you, Sebastian. I was referring to this, probably rather old, picture of C*2801 and surroundings (downloaded and edited by me): https://dl.dropboxusercontent.com/u/15892273/C2801dss.jpg So I imagined I would see a "double star" there. But this in all likelyhood won't be the case anymore.

Thanks again, Thomas

Plates and colors
Sebastian Otero's picture
Sebastian Otero
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Joined: 2010-09-19

Hi, Thomas,
it is not that the star was bright before and now it is faint (you seem to imply that when you say "it won't be the case anymore"). I think that due to its deep red color, its magnitude depends on the plate sensitivity. If you look at an R-like image you will see a double star, if you look at a V image you'll see a difference of more than 1 magnitude between the two stars.
The image you show is probably an R image, where both stars have mag. 10 or so.

Cheers,
Sebastian

Thanks
thn's picture
thn
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Joined: 2013-08-17

again, Sebastian. No more questions!

Greetings, Thomas

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