Groombridge 34

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Groombridge 34
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension 00h 18m 22.89s[1]
Declination +44° 01′ 22.6″[1]
Apparent magnitude (V) 8.119/11.007[2]
Spectral type M1.4V + M4.1V[2]
U−B color index 1.24
B−V color index 1.56
Variable type Flare stars
Radial velocity (Rv) +12.0 km/s
Proper motion (μ) RA: +2888.92 ± 0.60[1] mas/yr
Dec.: +410.10 ± 0.48[1] mas/yr
Parallax (π) 278.76 ± 0.77[1] mas
Distance 11.70 ± 0.03 ly
(3.587 ± 0.010 pc)
Companion Groombridge 34 B
Gl 15 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
Mass 0.404[3] M
Radius 0.3863 ± 0.0021[4] R
Luminosity (bolometric) 0.02589[note 1] L
Luminosity (visual, LV) 0.00637[note 2] L
Surface gravity (log g) 4.89[3] cgs
Temperature 3,730 ± 49[3] K
Metallicity [Fe/H] -0.32 dex
GQ And
Mass 0.159[2] M
Radius 0.192[2] R
Luminosity (bolometric) ~0.00262[note 1] L
Luminosity (visual, LV) 0.00041[note 2] L
Temperature 3,218[2] K
Metallicity [Fe/H] −0.30[2] dex
Other designations
GX/GQ Andromedae, BD+43° 44, GCTP 49, GJ 15 A/B, Gl 171-047/171-048, HD 1326, HIP 1475, LHS 3/4, LTT 10108/10109, LFT 31/32, SAO 36248, Vys 085 A/B.[5]

Groombridge 34 is a binary star system in the northern constellation of Andromeda. Based upon parallax measurements taken by the Hipparcos spacecraft, they are located about 11.7 light-years from the Sun. Both components are small, faint 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. 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, and the other member is designated GQ And.

Planetary system[edit]

In August 2014, a planet orbiting around Groombridge 34 A was reported.[4] 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,[6] and at its discovery was the sixth nearest known exoplanet.

The Groombridge 34 A planetary system
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b ≥ 5.35±0.75 M 0.0717±0.0034 11.4433±0.0017 0.12?

See also[edit]


  1. ^ a b From \begin{smallmatrix}L=4 \pi R^2 \sigma T_{\rm eff}^4 \end{smallmatrix}, where \begin{smallmatrix}L \end{smallmatrix} is the luminosity, \begin{smallmatrix}R \end{smallmatrix} is the radius, \begin{smallmatrix}T_{\rm eff}\end{smallmatrix} is the effective surface temperature and \begin{smallmatrix}\sigma \end{smallmatrix} is the Stefan–Boltzmann constant
  2. ^ a b Using the absolute visual magnitude of Gliese 15 A, \scriptstyle M_{V_{\ast}}=10.32, and Gliese 15 B, \scriptstyle M_{V_{\ast}}=13.29, with the absolute visual magnitude of the Sun, \scriptstyle M_{V_{\odot}}=4.83, the two visual luminosities of the stars can be calculated by \scriptstyle \frac{L_{V_{\ast}}}{L_{V_{\odot}}}=10^{0.4\left(M_{V_{\odot}} - M_{V_{\ast}}\right)}


  1. ^ a b c d e 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.  Vizier catalog entry
  2. ^ a b c d e f 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 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): 475–483. arXiv:astro-ph/0602105. Bibcode:2006ApJ...644..475B. doi:10.1086/503318. 
  4. ^ 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. 
  5. ^ "V* GX And -- Flare Star", SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), retrieved 2016-02-09. 
  6. ^ Howard, Andrew; et al., "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, arXiv:1408.5645. 

External links[edit]