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planetaryscience
2015-Aug-29, 12:39 AM
I'm posting this here because I don't know who else I should report this to, but about 4 months ago I was inspecting the galactic core for X-ray sources, to make a catalog of X-ray binaries in the milky way (which is another story) and while looking in the area near NGC 6624, I happened upon an interesting X-ray source not typical of X-ray binary stars. When I investigated the source, all that showed up in the area was an otherwise unremarkable pair of stars in a large star field, not even the brightest in the area. So I looked it up on Simbad and found it had been identified as 2MASS J18352154-3123385 (shortened from this point as J1835) Interestingly, though, it had a proper motion of half an arcsecond, and it was a binary star with both stars having approximately the same proper motion.

I quickly did a spectral analysis based on an assumed V-band magnitude of 12 and 12.5 for each star, and arrived at a spectral type of M5/M7 or M6/M8 for each star. Therefore, they must be nearby and one of the nearest binary stars. Moreso, they are likely one of the last undiscovered nearby stars in the sky. However I had no idea who to report this to, so it remained as such for a few months.

However, more recently I renewed my attempts to get data on the star. Looking through old data on the star, I put an estimate to the stars' orbital period as about 150-200 years. However while looking at WISE image of the star, I noticed that excessive emission near the star which I had though to be J1835B (the second star) was actually unrelated. I attempted to match it with a nearby magnitude 14 star, but found it not to be centered on that. It was in fact coming from a 16.5th magnitude star near J1835. A spectral analysis using old data from Vizier puts it at spectral type M9 or L0, and it even appears to have been the source of the X-ray emission, not J1835. While about magnitude 16 in WISE, it is actually the brightest infrared object in the area. The nature of it as an X-ray source suggests that it might be a flare star, and is in fact consistent with other flare stars (which also emit x-rays) in brightness and color. However, of surveys that included it, the two that measured its proper motion with any accuracy put a proper motion of below 40 mas/yr, far below the expected proper motion of it to be orbiting J1835, even if it was orbiting the stars in the opposite direction of its proper motion.

I had been hoping the Gaia survey would clear up any uncertainty in the stars' distances, possible relation, and other information but now gather that it won't be released until Summer of 2016, maybe later, so I have nearly a year of observations to make before accurate data of any sort is released on it. In the mean time, if anyone has a large telescope, could you attempt to make observations of the star, noting its location between now and next year? I could easily view it under a dark sky with a 6'' telescope, and a larger telescope would be useful for more accurate locations.

A telescope isn't all I need though, if anyone can help me find the orbits and proper motions of the stars using old Vizier data, perhaps I could determined their distance relatively accurately that way too.

antoniseb
2015-Aug-29, 12:50 AM
This is an interesting post. Most of my astronomy is on paper, but hopefully someone here will look to join in your success.

schlaugh
2015-Aug-29, 01:04 AM
Could you possibly arrange to have observations made on a University scope? Example: http://fsc.fernbank.edu/observatory.htm
Maybe a college student could use some hands-on (eyes-on?) experience.

The Buice scope may not be the best option since it sits in the middle of a large city, but there are others (http://www.astro.gsu.edu/HLCO/). You would need to contact the schools and whoever runs the astronomy department.

What additional equipment is required? Simply capturing images of the star(s) over a year's time?

planetaryscience
2015-Aug-29, 01:36 AM
What additional equipment is required? Simply capturing images of the star(s) over a year's time?

Well that would be the basic requirement, but preferably would include taking it over multiple points that aren't over a years time, so that I can additionally determine its parallax. Plus a spectrograph would be useful to determine its spectral type

kzb
2015-Sep-02, 11:37 AM
It's seems common for there to be pre-discovery images of "new" objects. If you could find archived telescope photos and images of this area of sky going back several decades you might be able to tie down the proper motions better ? I apologise if I am stating the obvious BTW.

planetaryscience
2015-Sep-05, 03:49 PM
It's seems common for there to be pre-discovery images of "new" objects. If you could find archived telescope photos and images of this area of sky going back several decades you might be able to tie down the proper motions better ? I apologise if I am stating the obvious BTW.

Vizier I know for sure has found precovery images dating back to ~1900, but the locations are not as precise and I can't accurately determine which of the stars the observations see, so while I can get an idea of their total proper motion, one of the reasons I had wanted to find their proper motion - to determine their orbit - would be very difficult in this case.

kzb
2015-Sep-07, 11:59 AM
Is the RECONS list any help?

List of nearest 100 stellar systems as of 01-JAN-2012:

http://www.recons.org/TOP100.posted.htm

http://www.recons.org/