Groombridge 1830

Groombridge 1830

Groombridge 1830 (circled in red) in Ursa Major
Detailed position of HR 4550 ( = Groombridge 1830; bottom-left edge) related to χ UMa and ψ UMa
Observation data Epoch J2000       Equinox J2000
Constellation	Ursa Major [1]
Right ascension	11h 52m 58.76734s [2]
Declination	+37° 43′ 07.2541″ [2]
Apparent magnitude  (V)	6.44 [3]
Characteristics
Evolutionary stage	main sequence [2]
Spectral type	K1V Fe−1.5 [4]
U−B color index	+0.16 [3]
B−V color index	+0.75 [3]
Variable type	Suspected [5]
Astrometry
Radial velocity (Rv)	−98.05±0.12 [2] km/s
Proper motion (μ)	RA: +4,002.7 mas/yr [2] Dec.: −5,817.8 mas/yr [2]
Parallax (π)	109.0296±0.0197  mas [2]
Distance	29.914 ± 0.005  ly (9.172 ± 0.002  pc)
Absolute magnitude  (MV)	6.64 [6]
Details [7]
Mass	0.63±0.02  M☉
Radius	0.586±0.004  R☉
Luminosity	0.221±0.005  L☉
Surface gravity (log g)	4.702±0.015  cgs
Temperature	5,174±32  K
Metallicity [Fe/H]	−1.26±0.07  dex
Rotation	32.2 [8]
Rotational velocity (v sin i)	0.5 [8]  km/s
Age	4.7–5.3 [9]   Gyr
Other designations
Groombridge 1830, Argelander's Star, CF UMa, BD+38 2285, FK5 1307, GJ 451, HD 103095, HIP 57939, HR 4550, SAO 62738, LHS 44, LTT 13276, PLX 2745 [10]
Database references
SIMBAD	data

Groombridge 1830 is a star 29.9 light-years away in the constellation Ursa Major. With an apparent magnitude of 6.4, it is near the limit of naked eye visibility under ideal conditions. It has a low metallicity and is thought to be a superflare star.

Discovery and naming

The star was catalogued by British astronomer Stephen Groombridge with the Groombridge Transit Circle between 1806 and the 1830s and published posthumously in his star catalog, Catalogue of Circumpolar Stars (1838). The designation Groombridge 1830 comes from this catalog; in older sources it is sometimes written as 1830 Groombridge. ^[11] Its high proper motion was noted by Friedrich Wilhelm Argelander in 1842, ^[12] and so it is sometimes called Argelander's Star, a name first used in an 1853 paper. ^[11]

Other designations for this star include HD 103095, HR 4550, and Gliese 451. It has the variable star designation CF Ursae Majoris, which originally referred to a supposed flaring companion star that is no longer believed to exist. ^{[10] [13] [14]}

Description

Groombridge 1830 has been variously classified as a K-type main-sequence star, ^[4] a G-type main-sequence star, ^[15] or a G-type subdwarf. ^[14] The low metallicity of this star makes some of its spectral lines resemble those of a G-class star, ^[16] and it has been given as a spectral standard for the class G7V. ^[15]

It is 29.9 light-years (9.2 parsecs ) from the Sun as measured by the Gaia spacecraft, ^[2] which, as the distance is nearly 10 parsecs, means its absolute magnitude is almost equal to its apparent magnitude. It is a member of the galactic halo; such stars account for only 0.1 to 0.2 percent of the stars near the Sun. Like most halo stars, it has a low abundance of elements other than hydrogen and helium—what astronomers term a metal-poor star. ^[17]

Once suspected to be a binary star with a red dwarf flare star companion, ^[18] the current consensus is that it is single. ^[14] Previous observations of stellar flares, suspected to be from a companion star, were probably "superflares" on the primary star—analogous to the Sun's solar flares, but hundreds to millions of times more energetic. It was one of the first nine identified superflare stars. ^{[17] [19]}

Proper motion

When discovered, Groombridge 1830 had the highest known proper motion of any star, replacing 61 Cygni. Kapteyn's Star and Barnard's Star have since been identified as having even higher proper motions. It is considerably farther away than either of those stars, however, which means its transverse velocity is greater.^{[ citation needed ]}

See also

• List of star systems within 25–30 light-years

References

1. Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific . 99 (617): 695. Bibcode:1987PASP...99..695R. doi: 10.1086/132034 . Constellation record for this object at VizieR.
2. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
3. Argue, A. N. (1966). "UBV photometry of 550 F, G and K type stars". Monthly Notices of the Royal Astronomical Society. 133 (4): 475–493. Bibcode:1966MNRAS.133..475A. doi: 10.1093/mnras/133.4.475 .
4. Gray, R. O.; Corbally, C. J.; Garrison, R. F.; McFadden, M. T.; Robinson, P. E. (2003). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I.". The Astronomical Journal. 126 (4): 2048. arXiv: astro-ph/0308182 . Bibcode:2003AJ....126.2048G. doi:10.1086/378365.
5. Kukarkin, B. V.; et al. (1981). "Catalogue of suspected variable stars". Nachrichtenblatt der Vereinigung der Sternfreunde. Moscow, USSR: Academy of Sciences. Bibcode:1981NVS...C......0K.
6. Holmberg, J.; et al. (July 2009). "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics". Astronomy and Astrophysics. 501 (3): 941–947. arXiv: 0811.3982 . Bibcode:2009A&A...501..941H. doi:10.1051/0004-6361/200811191. S2CID   118577511.
7. Karovicova, I.; White, T. R.; Nordlander, T.; Casagrande, L.; Ireland, M.; Huber, D.; Jofré, P. (2020-08-01). "Fundamental stellar parameters of benchmark stars from CHARA interferometry - I. Metal-poor stars". Astronomy & Astrophysics. 640: A25. arXiv: 2006.05411 . Bibcode:2020A&A...640A..25K. doi:10.1051/0004-6361/202037590. ISSN   0004-6361.
8. Marsden, S. C.; Petit, P.; Jeffers, S. V.; Morin, J.; Fares, R.; Reiners, A.; Do Nascimento, J. -D.; Aurière, M.; Bouvier, J.; Carter, B. D.; Catala, C.; Dintrans, B.; Donati, J. -F.; Gastine, T.; Jardine, M.; Konstantinova-Antova, R.; Lanoux, J.; Lignières, F.; Morgenthaler, A.; Ramìrez-Vèlez, J. C.; Théado, S.; Van Grootel, V.; BCool Collaboration (2014). "A BCool magnetic snapshot survey of solar-type stars". Monthly Notices of the Royal Astronomical Society. 444 (4): 3517. arXiv: 1311.3374 . Bibcode:2014MNRAS.444.3517M. doi: 10.1093/mnras/stu1663 .
9. Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008). "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics". The Astrophysical Journal. 687 (2): 1264–1293. arXiv: 0807.1686 . Bibcode:2008ApJ...687.1264M. doi:10.1086/591785. S2CID   27151456.
10. "HD 103095". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 22 April 2025.
11. Peters, C. A. F. (December 1853). "On the Parallax of Argelander's Star". Monthly Notices of the Royal Astronomical Society . 14 (2): 49. Bibcode:1853MNRAS..14...49P. doi: 10.1093/mnras/14.2.49 .
12. Argelander, Friedrich Wilhelm August (1842). "Schreiben des Herrn Professors Argelander Directors der Sternwarte in Bonn, an den Herausgeber". Astronomische Nachrichten (in German). 19 (26): 393. Bibcode:1842AN.....19..393A. doi:10.1002/asna.18420192604.
13. "CF UMa". General Catalog of Variable Stars - VizieR . Retrieved 22 April 2025.
14. Heintz, W. D. (July 1984). "Astrometric study of the subdwarf HR 4550". Publications of the Astronomical Society of the Pacific . 96: 557–558. Bibcode:1984PASP...96..557H. doi:10.1086/131379.
15. Keenan, Philip C.; Keller, Geoffrey (1953). "Spectral Classification of the High-Velocity Stars". The Astrophysical Journal. 117: 241. Bibcode:1953ApJ...117..241K. doi:10.1086/145687.
16. Abt, Helmut A. (1986). "Spectral Classification of Weak-lined Stars Discovered Photometrically". The Astrophysical Journal. 309: 260. Bibcode:1986ApJ...309..260A. doi:10.1086/164597.
17. "Groombridge 1830". SolStation. Archived from the original on 6 December 2023.
18. Beardsley, W. R.; Gatewood, G.; Kamper, K. W. (December 1974). "A study of an early flare, radial velocities, and parallax residuals for possible orbital motion of HD 103095 (Groombridge 1830)". Astrophysical Journal . 194: 637–643. Bibcode:1974ApJ...194..637B. doi:10.1086/153284.
19. Rubenstein, Eric P. (February 2001). "Superflares and Giant Planets". American Scientist. 89 (1): 38. arXiv: astro-ph/0101573 . Bibcode:2001AmSci..89...38R. doi:10.1511/2001.1.38. S2CID   119439101.

Further reading

• Israelian, Garik; García López, Ramon J.; Rebolo, Rafael (1998). "Oxygen Abundances in Unevolved Metal-poor Stars from Near-Ultraviolet OH Lines". Astrophysical Journal . 507 (2): 805–817. arXiv: astro-ph/9806235 . Bibcode:1998ApJ...507..805I. doi:10.1086/306351. S2CID   18215356.
• Petersen, A. C. (1843). "Beobachtungen des Cometen auf der Altonaer Sternwarte. Von Herrn Observator Ritter Petersen". Astronomische Nachrichten (in German). 20 (10): 163. Bibcode:1843AN.....20..163P. doi:10.1002/asna.18430201003.
• Jürgensen, Louis Urban (1843). "L'Idée de parvenir à l'isochronisme des vibrations du pendule à l'aide du ressort auquel le pendule estsuspendu, est concue par Urbain-Jürgensen, et émise dans le numéro 49 des Astr. Nachr. 1823 Par Mr. Louis Urbain Jürgensen". Astronomische Nachrichten (in French). 20: 279. Bibcode:1843AN.....20..279J. doi:10.1002/asna.18430201703.