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View Full Version : Whatever happened to SO25300.5+165258 ?



tracer
2004-Mar-18, 07:05 AM
Remember SO25300.5+165258 (http://arxiv.org/abs/astro-ph/0302206/)? The red dwarf star Teegarden et al. found about a year ago? And when they measured the trigonometric parallax, they found that the star was only 7.6 light-years away, making it the 3rd closest star to the sun? The one that was spectral class M6.5, but whose absolute magnitude, assuming their distance measurement was correct, was a full 1.2 magnitudes dimmer than an M6.5 main-sequence star ought to be?

Well ... whatever happened with that little star? Did it turn out that their parallax measurements were screwy, and the star was actually a considerably greater distance farther away? Did it turn out to be one of the less-common Luminosity Class VI subdwarfs with low metallicity that we see from time to time? Or did it turn out to be ... <insert ominous music here> ... a whole new kind of red dwarf that might be very common in space but which we hadn't detected before because they're so dim?

(I bring up the last possibility because, if true, it means we may have severely underestimated the amount of luminous material in our galaxy and in other galaxies. The presence of a huge number of these super-dim red dwarfs that before went uncounted could go a long way towards explaining the "missing mass" seen within many galaxies without the need to resort to "dark matter" -- even if it can't help to explain the missing mass in intergalactic space.)

Eroica
2004-Mar-18, 08:18 AM
Good question. I tried googling, but failed to turn up any recent updates. :-?

TriangleMan
2004-Mar-18, 11:53 AM
Any way of emailing the authors of the article?

Anthrage
2004-Mar-18, 03:40 PM
This (http://www.sciscoop.com/story/2003/5/22/111226/413) is the most recent reference I can find, with a few (http://www.smh.com.au/articles/2003/05/22/1053585646997.html)links (http://www.astronomy.com/Content/Dynamic/Articles/000/000/001/337btnqj.asp) from it itself.

Ah, here's (http://www.bangornews.com/editorialnews/articles/406612_082803septembersmellowm_cwood.cfm) a somewhat more recent reference, from August 2003, but it's only that - a passing reference. Still looking...

September 2003's Sky & Telescope (http://skyandtelescope.com/magazinearchive/search/results.asp?start_date=&end_date=&terms=teegarden& title=&author=&start_date_month=09&start_date_year =2003&end_date_month=09&end_date_year=2003&go.x=41 &go.y=10) has an article...if anyone has a copy laying around, perhaps there are furrther details therein. Now you've got me curious. ;)

A-ha! Here's (http://www.nojum.net/news/newse.asp?newsid=25) a very recent reference, 2 months ago. Seems they refined the distance to 12.4 light-years. Also an entry in Wikipedia (http://en.wikipedia.org/wiki/Teegarden's_Star), with out of date distance.

A brown dwarf was also discovered not long ago, fairly close by. I'm not sure MACHO's account for the majority of missing mass, but it appears they do account for more than once recently expected. Interesting stuff.

TheGalaxyTrio
2004-Mar-18, 04:03 PM
http://www.solstation.com/stars/so025300.htm

SO 025300.5+165258.

Not to be confused with SO 025300.5+165259. I'm always getting those two mixed up.

tracer
2004-Mar-18, 05:07 PM
A-ha! Here's (http://www.nojum.net/news/newse.asp?newsid=25) a very recent reference, 2 months ago. Seems they refined the distance to 12.4 light-years.
Aha, indeed! That greater distance means that the star's intrinsic luminosity is 2.5 times greater than originally thought. That's a whole stellar magnitude -- this almost completely accounts for the 1.2 magnitude discrepancy alleged to exist between this star and a "normal" M6.5 dwarf when it was originally discovered.

Something else from that article catches my eye, though:

"The most surprising result of RECONS so far is the realization of the extent to which red dwarfs are the real rulers of the universe, both in numbers and total mass. Within 10 parsecs of the Sun there are no hot, bright O and B stars, just 4 white A stars and 6 yellow-white F stars, 21 G stars similar to our Sun, 45 orange K dwarfs — and a whopping 236 cool, orange-red M dwarfs like Proxima Centauri (which still ranks as the Sun's closest neighbor). There are also 20 white dwarfs. That means that for every other star in the universe, there are no less than 2.5 red M dwarfs."

I thought so! The first time I started leafing through the Gliese catalog, my impression was, "Good gravy, look at all the red dwarfs!" It looks like RECONS has vindicated my gut feeling there. And my guess is, the calculated "luminous mass" of a galaxy is based on assumptions of what percentage of the stars are red dwarfs. Have we now revised upward our estimates of all galaxies' Luminous Mass because of this?

Grand Vizier
2004-Mar-18, 05:14 PM
I thought so! The first time I started leafing through the Gliese catalog, my impression was, "Good gravy, look at all the red dwarfs!" It looks like RECONS has vindicated my gut feeling there. And my guess is, the calculated "luminous mass" of a galaxy is based on assumptions of what percentage of the stars are red dwarfs. Have we now revised upward our estimates of all galaxies' Luminous Mass because of this?

I've seen a recent comment to the effect that we could, in fact, have missed one or more very dim red dwarfs that are closer in than Proxima, which surprised me - I thought we had that all sewn up. Can't trace where I saw it, though. Of course, there could easily be singleton brown dwarfs closer than 4.2ly, too.

I wouldn't dare to hope for something at, say, 2ly - but it certainly would help with interstellar mission planning...

tracer
2004-Mar-18, 05:22 PM
Here's the RECONS article on the distance to SO25300.5+165258:

http://www.chara.gsu.edu/RECONS/new.SO025300.5+165258.htm

Apparently, the distance to this star is still a puzzle.

Spacedog
2004-May-30, 05:00 PM
hi

passing amateur nu-B here
nice place

so
just how fast is this red dwarf moving?
especially since it seems to be about as far away as it should be
- but still largest proper motion ever, at what, 10-12ly?
and is that the reason why it was originally sed to be so near ?
- that someone couldn’t deal with the implied velocity?
[-X

the reason why i ask is
i'm researching local stars for a 3D starmap i'm making, in Bryce
- kinda like tiddly winks, or a virtual ship inna bottle
n i noticed u hafta check the dates for some of em
- as apparent position n mileages may vary
8-[

so if anyone’s got a more solid estimate as to distance
that would be a huge help for me little hobby
:wink:

anyways
i wish this star had a name
might i suggest Fluffy?
or how bout Corvette or Ferrarri?
- for something fast n red
:lol:

in other news
i've decided there should be a space station
just to the left of Luyten, on the road to Tau Ceti
as there's kinda a crossroads intersection with the roads:
Luyten - Eta Eridani
Sol - Tau Ceti
neat, huh?

the AVI will be sizeable
but for now, all roads lead to Sol
8)