Groombridge 1830

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Groombridge 1830
Ursa Major constellation map.svg
Location dot red.svg
The red dot shows the location of Groombridge 1830 in Ursa Major.
HR 4550 Pos.gif
Detailed position of HR 4550 ( = Groombridge 1830; bottom-left edge) related to Chi UMa and Psi UMa.
Observation data
Epoch J2000      Equinox J2000
Constellation Ursa Major
Right ascension  11h 52m 58.76931s[1]
Declination +37° 43′ 07.2343″[1]
Apparent magnitude (V) 6.44[2]
Spectral type G8VIp[3]
U−B color index +0.16[2]
B−V color index +0.75[2]
Variable type Suspected[4]
Radial velocity (Rv)–98.0[5] km/s
Proper motion (μ) RA: 4,003.98[1] mas/yr
Dec.: −5,813.62[1] mas/yr
Parallax (π)109.99 ± 0.41[6] mas
Distance29.7 ± 0.1 ly
(9.09 ± 0.03 pc)
Absolute magnitude (MV)6.64[7]
Mass0.661[8] M
Radius0.681 ± 0.006[9] R
Luminosity0.212 ± 0.002[9] L
Surface gravity (log g)4.68[10] cgs
Temperature4,759 ± 20[9] K
Metallicity [Fe/H]–1.33[10] dex
Age4.7–5.3[11] Gyr
Other designations
BD+38 2285, FK5 1307, GCTP 2745.00, GJ 451, HIP 57939, HR 4550, HD 103095, LHS 44, LTT 13276, SAO 62738, 1830 Groombridge, Argelander's Star
Database references

Groombridge 1830 (also known as 1830 Groombridge or Argelander's Star)[12] is a star in the constellation Ursa Major.


It is a yellow-hued class G8 subdwarf 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). Its high proper motion was noted by Friedrich Wilhelm Argelander in 1842.

It is 29.9 light-years (9.2 parsecs) from the Sun as measured by the Hipparcos astrometry satellite,[1][13] 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.[14]

Once suspected of being a binary star with a period of 175 days, current consensus is that it is single. 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.[14][15] It had one of the first nine identified superflares.

Proper motion[edit]

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.

See also[edit]


  1. ^ a b c d e Perryman, M. A. C.; et al. (1997). "The Hipparcos Catalogue". Astronomy & Astrophysics. 323: L49–L52. Bibcode:1997A&A...323L..49P.
  2. ^ a b c Argue, A. N. (1966). "UBV photometry of 550 F, G and K type stars". Monthly Notices of the Royal Astronomical Society. 133: 475–493. Bibcode:1966MNRAS.133..475A. doi:10.1093/mnras/133.4.475.
  3. ^ Johnson, H. L.; Morgan, W. W. (1953). "Fundamental stellar photometry for standards of spectral type on the revised system of the Yerkes spectral atlas". Astrophysical Journal. 117: 313–352. Bibcode:1953ApJ...117..313J. doi:10.1086/145697.
  4. ^ Kukarkin, B. V.; et al. (1981). Catalogue of suspected variable stars. Moscow, USSR: Academy of Sciences. Bibcode:1981NVS...C......0K.
  5. ^ Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". In Batten, Alan Henry; Heard, John Frederick (eds.). Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. University of Toronto: International Astronomical Union. Bibcode:1967IAUS...30...57E.CS1 maint: Uses editors parameter (link)
  6. ^ van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  7. ^ 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.
  8. ^ Takeda, Genya; Ford, Eric B.; Sills, Alison; Rasio, Frederic A.; Fischer, Debra A.; Valenti, Jeff A. (February 2007). "Structure and Evolution of Nearby Stars with Planets. II. Physical Properties of ~1000 Cool Stars from the SPOCS Catalog". The Astrophysical Journal Supplement Series. 168 (2): 297–318. arXiv:astro-ph/0607235. Bibcode:2007ApJS..168..297T. doi:10.1086/509763.
  9. ^ a b c Boyajian, Tabetha S.; et al. (February 2012), "Stellar Diameters and Temperatures. I. Main-sequence A, F, and G Stars", The Astrophysical Journal, 746 (1): 101, arXiv:1112.3316, Bibcode:2012ApJ...746..101B, doi:10.1088/0004-637X/746/1/101. See Table 10.
  10. ^ a b Soubiran, C.; Bienaymé, O.; Mishenina, T. V.; Kovtyukh, V. V. (March 2008). "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants". Astronomy and Astrophysics. 480 (1): 91–101. arXiv:0712.1370. Bibcode:2008A&A...480...91S. doi:10.1051/0004-6361:20078788.
  11. ^ 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.
  12. ^ Peters, C. A. F.; "On the Parallax of Argelander's Star", Monthly Notices of the Royal Astronomical Society, December 1853, v.50, p.302, Bibcode1853MNRAS..14...49P
  13. ^ Perryman, Michael (2010), "The Making of History's Greatest Star Map", Astronomers' Universe, Heidelberg: Springer-Verlag,, doi:10.1007/978-3-642-11602-5
  14. ^ a b "Groombridge 1830". SolStation.
  15. ^ 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.

External links[edit]