Groombridge 1830

Starbox begin
name=Groombridge 1830 Starbox observe
epoch=J2000
ra=11^h 52^m 58.8^s
dec=+37° 43′ 07″
appmag_v=6.42
constell=Ursa Major Starbox character
class=G8 VIp
b-v=0.75
u-b=0.17
variable=Suspected Starbox astrometry
radial_v=-98.8
prop_mo_ra=4,003.69
prop_mo_dec=-5,813.00
parallax=109.78
p_error=0.70
absmag_v=6.62 Starbox detail
mass=0.6
radius=0.64
luminosity=0.19
temperature=5,030
metal=3-10%
rotation=?
age=5.4 × 10⁹ Starbox catalog
names=GJ 451, HR 4550, BD +38°2285, HD 103095, CF UMa, LHS 44, LTT 13276, GCTP 2745.00, SAO 62738, FK5 1307, Giclas 122-51, G 148-18, LFT 855, Gmb 1830, HIP 57939.

Groombridge 1830 is a star in the constellation Ursa Major.

It is a yellowish class G8 subdwarf catalogued by Stephen Groombridge in the 1830s. Its high proper motion was noted by Friedrich Wilhelm Argelander in 1842.

It is 29.7 light years from Earth's Solar System, which means its absolute magnitude is almost equal to its apparent magnitude. It is a halo star; such stars account for only 0.1 to 0.2 percent of the stars near the Sun. Like most halo stars, it is old (at least 10 Ga) and metal-poor. [http://www.solstation.com/stars/groo1830.htm Groombridge 1830 ] ]

Once suspected of being a binary star with a period of 175 days, current consensus is that it is single. In fact, previous suspected observations of a stellar companion were probably "superflares"--analogous to the Sun's solar flares, but hundreds to millions of times more energetic., [ [http://arxiv.org/abs/astro-ph/0101573 [astro-ph/0101573 Superflares and Giant Planets ] ]

When discovered, it had the highest proper motion of any star known, replacing 61 Cygni in that department. Later it dropped to second place after the discovery of Kapteyn's Star, and still later to third place after the discovery of Barnard's Star. It is considerably farther away than either of those stars, however, which means its transverse velocity is greater.

Actually, it is the Sun which is following the motion of galaxy rotation by revolving around the center of the Milky Way; halo stars like Groombridge 1830 do not follow this galaxy rotation and thus are "standing still" and appear to be moving in "retrograde direction" at high speed.

References

* Garik Israelian "et al", 1998, "Oxygen Abundances in Unevolved Metal-poor Stars from Near-Ultraviolet OH Lines", "Astrophysical Journal", 507, November.

ee also

* Space
*

External links

* [http://www.solstation.com/stars/groo1830.htm SolStation.com: Groombridge 1830]

Discovery of high proper motion

* [http://adsabs.harvard.edu//full/seri/AN.../0019//0000202.000.html AN 19 (1842) 393/394] (in German)
* [http://adsabs.harvard.edu//full/seri/AN.../0020//0000091.000.html AN 20 (1843) 163/164] (in German)
* [http://adsabs.harvard.edu//full/seri/AN.../0020//0000155.000.html AN 20 (1843) 279/280]