Groombridge 34

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
Groombridge 34
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Groombridge 34 A
Right ascension 00h 18m 22.8850s[1]
Declination +44° 01′ 22.6373″[1]
Apparent magnitude (V) 8.119[2]
Groombridge 34 B
Right ascension 00h 18m 25.8244s[3]
Declination +44° 01′ 38.0912″[3]
Apparent magnitude (V) 11.007[2]
Spectral type M1.4V + M4.1V[2]
U−B color index +1.24/+1.40[4]
B−V color index +1.56/+1.80[4]
Variable type Flare stars
Groombridge 34 A
Radial velocity (Rv)+11.62±0.08[5] km/s
Proper motion (μ) RA: 2891.525±0.061[1] mas/yr
Dec.: 411.903±0.034[1] mas/yr
Parallax (π)280.6902 ± 0.0429[1] mas
Distance11.620 ± 0.002 ly
(3.5626 ± 0.0005 pc)
Groombridge 34 B
Proper motion (μ) RA: 2863.284±0.069[3] mas/yr
Dec.: 336.529±0.039[3] mas/yr
Parallax (π)280.7866 ± 0.0519[3] mas
Distance11.616 ± 0.002 ly
(3.5614 ± 0.0007 pc)
CompanionGroombridge 34 B
Period (P)2,600 yr
Semi-major axis (a)41.15″
Eccentricity (e)0.00
Inclination (i)61.4°
Longitude of the node (Ω)45.3°
Periastron epoch (T)1745
GX And
Mass0.404[7] M
Radius0.3863 ± 0.0021[8] R
Luminosity (bolometric)0.02589[note 1] L
Luminosity (visual, LV)0.00637[note 2] L
Habitable zone inner limit0.112[9] AU
Habitable zone outer limit0.239[9] AU
Surface gravity (log g)4.89[7] cgs
Temperature3,730 ± 49[7] K
Metallicity [Fe/H]-0.32 dex
GQ And
Mass0.159[2] M
Radius0.192[2] R
Luminosity (bolometric)~0.00262[note 1] L
Luminosity (visual, LV)0.00041[note 2] L
Habitable zone inner limit0.048[9] AU
Habitable zone outer limit0.103[9] AU
Temperature3,218[2] K
Metallicity [Fe/H]−0.30[2] dex
Other designations
GX/GQ Andromedae, BD+43° 44, GCTP 49, GJ 15 A/B, G 171-047/171-048, HD 1326, HIP 1475, LHS 3/4, LTT 10108/10109, SAO 36248.[10]
Database references
GJ 15 Ab
GJ 15 B
GJ 15 B

Groombridge 34 is a binary star system in the northern constellation of Andromeda. It was listed as entry number 34 in A Catalogue of Circumpolar Stars, published posthumously in 1838 by British astronomer Stephen Groombridge.[11] Based upon parallax measurements taken by the Gaia spacecraft, the system is located about 11.6 light-years from the Sun. This positions the pair among the nearest stars to the Solar System.

Both components are small, dim red dwarf stars that are too faint to be seen with the naked eye. They orbit around their common barycenter in a nearly circular orbit with a separation of about 147 AU and a period of around 2,600 years.[6] Both stars exhibit random variation in luminosity due to flares and they have been given variable star designations: the brighter member Groombridge 34 A is designated GX And, while the smaller component is designated GQ And.[12]

The star system has a relatively high proper motion of 2.9 arc seconds per year,[13] and is moving away from the Solar System at a velocity of 11.6 km/s.[5] It achieved perihelion some 15,000 years ago when it came within 11 ly (3.5 pc) of the Sun.[13]

Planetary system[edit]

In August 2014, a planet orbiting around Groombridge 34 A was reported.[8] The planet's existence was deduced from analysis of the radial velocities of the parent Star by the Eta-Earth Survey using HIRES at Keck Observatory.

The planet is thought to have a minimum mass of 5.35 ± 0.75 Earth masses,[14] and at its discovery was the sixth-nearest known exoplanet.

Using the CARMENES spectrograph combined with the measurements of the HARPS and HIRES spectrographs, researchers failed to detect the purported Groombridge 34 Ab. However, they did propose another that another planet (Groombridge 34 Ac, GJ 15 Ac) with a mass of 51.8 Earth masses and a long orbital period of about 7,026 days, could be orbiting the parent star.[15]

The Groombridge 34 A planetary system[15]
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
Ab (disputed) ≥ 5.35±0.75 M 0.0717±0.0034 11.4433±0.0017 0.12?
Ac 51.8+5.5

See also[edit]


  1. ^ a b From , where is the luminosity, is the radius, is the effective surface temperature and is the Stefan–Boltzmann constant
  2. ^ a b Using the absolute visual magnitude of Gliese 15 A, , and Gliese 15 B, , with the absolute visual magnitude of the Sun, , the two visual luminosities of the stars can be calculated by


  1. ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. ^ a b c d e f g Mann, Andrew W.; et al. (May 2015), "How to Constrain Your M Dwarf: Measuring Effective Temperature, Bolometric Luminosity, Mass, and Radius", The Astrophysical Journal, 804 (1): 38, arXiv:1501.01635, Bibcode:2015ApJ...804...64M, doi:10.1088/0004-637X/804/1/64, 64.
  3. ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  4. ^ a b Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV data. SIMBAD, Bibcode:1986EgUBV........0M.
  5. ^ a b Nidever, David L.; et al. (August 2002), "Radial Velocities for 889 Late-Type Stars", The Astrophysical Journal Supplement Series, 141 (2): 503–522, arXiv:astro-ph/0112477, Bibcode:2002ApJS..141..503N, doi:10.1086/340570.
  6. ^ a b Lippincott, S. L. (March 1972), "Parallax and orbital motion of the two nearby long period visual binaries Groombridge 34 and ADS 9090.", Astronomical Journal, 77: 165–168, Bibcode:1972AJ.....77..165L, doi:10.1086/111261.
  7. ^ a b c Berger, D. H.; et al. (2006). "First Results from the CHARA Array. IV. The Interferometric Radii of Low-Mass Stars". The Astrophysical Journal. 644 (1): 475&ndash, 483. arXiv:astro-ph/0602105. Bibcode:2006ApJ...644..475B. doi:10.1086/503318.
  8. ^ a b Howard, Andrew W.; et al. (October 2014), "The NASA-UC-UH ETA-Earth Program. IV. A Low-mass Planet Orbiting an M Dwarf 3.6 PC from Earth", The Astrophysical Journal, 794 (1): 9, arXiv:1408.5645, Bibcode:2014ApJ...794...51H, doi:10.1088/0004-637X/794/1/51, 51.
  9. ^ a b c d Cantrell, Justin R.; et al. (October 2013), "The Solar Neighborhood XXIX: The Habitable Real Estate of Our Nearest Stellar Neighbors", The Astronomical Journal, 146 (4): 99, arXiv:1307.7038, Bibcode:2013AJ....146...99C, doi:10.1088/0004-6256/146/4/99.
  10. ^ "V* GX And". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-02-09.
  11. ^ Groombridge, Stephen (1838), Airy, George Biddell, ed., A Catalogue of Circumpolar Stars, J. Murray, p. 2.
  12. ^ Petit, M. (October 1990), "Catalogue des étoiles variables ou suspectes dans le voisinage du Soleil", Astronomy and Astrophysics Supplement (in French), 85 (2): 971, Bibcode:1990A&AS...85..971P.
  13. ^ a b Bailer-Jones, C. A. L. (March 2015). "Close encounters of the stellar kind". Astronomy & Astrophysics. 575: 13. arXiv:1412.3648. Bibcode:2015A&A...575A..35B. doi:10.1051/0004-6361/201425221. A35.
  14. ^ Howard, Andrew; et al. (2014), "The NASA-UC-UH Eta-Earth Program: IV. A Low-mass Planet Orbiting an M Dwarf 3.6 PC from Earth", Astrophysics Earth and Planetary Astrophysics, 794: 51, arXiv:1408.5645, Bibcode:2014ApJ...794...51H, doi:10.1088/0004-637X/794/1/51.
  15. ^ a b Trifonov, T; Kürster, M; Zechmeister, M; Tal-Or, L; Caballero, J; Quirrenbach, A; Ribas, I; Reiners, A (2017). "The CARMENES search for exoplanets around M dwarfs. First visual-channel radial-velocity measurements and orbital parameter updates of seven M-dwarf planetary systems". Astronomy & Astrophysics. 609: A117. arXiv:1710.01595. Bibcode:2018A&A...609A.117T. doi:10.1051/0004-6361/201731442.

External links[edit]