Groombridge 34

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Groombridge 34
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension 00h 18m 22.88532s[1]
Declination +44° 01′ 22.6282″[1]
Apparent magnitude (V) 8.119/11.007[2]
Characteristics
Spectral type M1.4V + M4.1V[2]
U−B color index +1.24/+1.40[3]
B−V color index +1.56/+1.80[3]
Variable type Flare stars
Astrometry
Radial velocity (Rv) +11.62±0.08[4] 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)
Orbit[5]
Companion Groombridge 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
Details
GX And
Mass 0.404[6] M☉
Radius 0.3863 ± 0.0021[7] R☉
Luminosity (bolometric) 0.02589[note 1] L☉
Luminosity (visual, LV) 0.00637[note 2] L☉
Habitable zone inner limit 0.112[8] AU
Habitable zone outer limit 0.239[8] AU
Surface gravity (log g) 4.89[6] cgs
Temperature 3,730 ± 49[6] 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☉
Habitable zone inner limit 0.048[8] AU
Habitable zone outer limit 0.103[8] AU
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.[9]

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.[10] Based upon parallax measurements taken by the Hipparcos spacecraft, the system is located about 11.7 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.[5] 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.[11]

The star system has a relatively high proper motion of 2.9 arc seconds per year,[12] and is moving away from the Solar System at a velocity of 11.6 km/s.[4] It achieved perihelion some 15,000 years ago when it came within 11 ly (3.5 pc) of the Sun.[12]

Planetary system

In August 2014, a planet orbiting around Groombridge 34 A was reported.[7] 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,[13] and at its discovery was the sixth nearest known exoplanet.

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

See also

Notes

  1. ↑ 1.0 1.1 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. ↑ 2.0 2.1 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)}

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Lua error in package.lua at line 80: module 'strict' not found. Vizier catalog entry
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ 3.0 3.1 Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ 4.0 4.1 Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ 5.0 5.1 Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ 6.0 6.1 6.2 Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ 7.0 7.1 Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ 8.0 8.1 8.2 8.3 Lua error in package.lua at line 80: module 'strict' not found.
  9. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  11. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  12. ↑ 12.0 12.1 Lua error in package.lua at line 80: module 'strict' not found.
  13. ↑ Lua error in package.lua at line 80: module 'strict' not found.

External links

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