Groombridge 1618

Starbox begin
name=Groombridge 1618 Starbox observe
epoch=J2000.0
constell=Ursa Major
ra=RA|10|11|22.1411cite web
url=http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=Groombridge+1618
title=SIMBAD Query Result: NSV 4765 -- Flare Star
publisher=Centre de Données astronomiques de Strasbourg
accessdate=2007-06-24 ]
dec=DEC| +49|27|15.252
appmag_v=6.61 Starbox character
class=K5 V
b-v=1.38
u-b=1.28
variable=Flare star Starbox astrometry
radial_v=-26.1
prop_mo_ra=-1361.65
prop_mo_dec=-505.14
parallax=205.23
p_error=0.81
parallax_footnote=
absmag_v=8.17 Starbox detail
age=1 × 10⁹
metal=191% Sun [cite journal
author=Woolf, V.; Wallerstein, G.
title=Metallicity measurements using atomic lines in M and K dwarf stars
journal="Monthly Notices of the Royal Astronomical Society
year=2005
volume=356
pages=963–968
url=http://adsabs.harvard.edu/abs/2005MNRAS.356..963W
accessdate=2007-02-04 | doi=10.1111/j.1365-2966.2004.08515.x]
mass=0.64 [cite web
author=Staff | date=June 8, 2007
url=http://www.chara.gsu.edu/RECONS/
title=RECONS | publisher=Georgia State University
accessdate=2007-06-24 ]
radius=0.59±0.03 [cite journal
last=Perrin | first=M.-N. | coauthors=Karoji, H.
title=Stellar radius determination from IRAS 12-micron fluxes
journal=Astronomy and Astrophysics
year=1987 | volume=172 | pages=235–240
url=http://adsabs.harvard.edu/abs/1987A&A...172..235P
accessdate=2008-05-05 ]
rotation=8.7-28.1 days
(0.9-2.9 km/s)
gravity=4.5
luminosity=0.046
temperature=4,000 Starbox catalog
names=BD+50°1725, GCTP 2390.00, GJ 380, HD 88230, HIP 49908, IRAS 10082+4942, LFT 696, LHS 280, LTT 12732, SAO 43223

Groombridge 1618 is a star in the constellation Ursa Major. It is located relatively close to Earth, at a distance of less than 16 light years. This is an orange dwarf star of spectral type K5 V.

This star has a relatively high proper motion across the sky, making it an early candidate for parallax measurement. In 1884 the parallax was measured at 0″.322 ± 0″.023 (which is larger than the modern value of 0″.205). [cite journal
last = Ball | first = Robert S.
title=On the Annual Parallax of Groombridge 1618
journal=Dunsink Observatory Publications
year=1884 | volume=5
issue=2 | pages=187–217
url=http://adsabs.harvard.edu/abs/1884DunOP...5..187B
accessdate=2007-02-04 ]

It is a flare star with behavior similar to UV Ceti. The chromosphere has been shown to be active and possesses star spots comparable to a Sun spot. It has a greater luminosity than most flare stars, which are typically red dwarfs, but is less active. The level of activity may suggest that this is a somewhat youthful star.

A search for an excess amount of infrared emission from this star by the Infrared Space Observatory came upnegative, implying that Groombridge 1618 does not possessa debris disk (such as Vega). [cite journal
author=R.J. Laureijs "et al"
title=A 25 micron search for Vega-like disks around main-sequence stars with ISO
journal=Astronomy & Astrophysics | year=2002
volume=387 | pages=L285–L293
url=http://www.aanda.org/articles/aa/full/2002/19/aa1808/aa1808.right.html
accessdate=2007-02-04
doi=10.1051/0004-6361:20020366 ] If this star does have a companion, astrometric measurements appear to place an upper bound of 3–12 times the mass of Jupiter on such a hypothetical object (for orbital periods in the range of 5–50 years). [cite journal
author=Hershey, J. L.; Borgman, E. R.
title=Upper Limits on the Mass of a Dark Companion of Groombridge 1618 from the 40-year Sproul Plate Series
journal=Bulletin of the American Astronomical Society,
year=1978
volume=10
pages=630
url=http://adsabs.harvard.edu/abs/1978BAAS...10..630H
accessdate=2007-06-24 ]

ee also

* Stephen Groombridge
* List of nearest stars
* Groombridge 1618 in fiction

References

External links

*cite web
url=http://www.solstation.com/stars/groo1618.htm
title=Groombridge 1618 | publisher=Sol Company
accessdate=2007-06-24
*cite web
url=http://www.ari.uni-heidelberg.de/aricns/cnspages/4c00785.htm
title=ARICNS 4C00785
publisher=Astronomisches Rechen-Institut
accessdate=2007-06-24