GJ 3021

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GJ 3021
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Hydrus
Right ascension 00h 16m 12.68s[1]
Declination −79° 51′ 04.2″[1]
Apparent magnitude (V) 6.59
Characteristics
Spectral type G6 V
B−V color index 0.749
Astrometry
Proper motion (μ) RA: +433.92 ± 0.30[1] mas/yr
Dec.: -56.74 ± 0.29[1] mas/yr
Parallax (π) 57.15 ± 0.29[1] mas
Distance 57.1 ± 0.3 ly
(17.50 ± 0.09 pc)
Absolute magnitude (MV) 5.37 ± 0.01[2]
Details
Mass 1.00 ± 0.10[3] M
Radius 0.86 ± 0.07[3] R
Luminosity 0.64[3] L
Surface gravity (log g) 4.58 ± 0.09[3] cgs
Temperature 5,572 ± 40[3] K
Metallicity [Fe/H] 0.12 ± 0.04[3] dex
Rotational velocity (v sin i) 5.5 km/s
Age 800[4] Myr
Other designations
2 G. Hydri, GJ 3021, HD 1237, HIP 1292.
Database references
SIMBAD data

GJ 3021 (2 G. Hydri) is a binary star system approximately 57 light-years away in the constellation of Hydrus (the Water Snake).

The visible star in the system, A, is considered to be a Solar twin. As of 2000, it has been confirmed that an extrasolar planet orbits the star. It is of note for being a relatively Sun-like star not very far from the Sun that is home to an extrasolar planet.[5]

Stellar components[edit]

As a nearby Sun-like star, the last decade has seen GJ 3021 A being studied carefully for the first time, especially after its substellar companion was discovered. It is currently believed that it is 800 million years old, though age estimates range from 150 million to 8.8 billion years old depending on the method used for the determination.[4] The star is more enriched with iron than the Sun, is chromospherically active, and rotates around its axis more quickly than the Sun.

The secondary star GJ 3021 B is a M4 red dwarf star at a projected physical separation of 68 AU.[6]

Planetary system[edit]

Announced in 2000, the Jovian planet GJ 3021 b orbits about 0.5 astronomical units from GJ 3021 A with a minimum mass 3.37 times that of Jupiter, as determined by measuring variations in the radial velocity of the star. A study published in 2001 suggested that the usual inability to determine the orbital inclination of an extrasolar planet through radial velocity measurement had caused this mass to be severely underestimated.[7] The astrometric orbit gives an orbital inclination of 11.8° and a mass of 16 Jupiter masses, which would make the object a brown dwarf. However later analysis showed that Hipparcos was not sensitive enough to accurately determine astrometric orbits for substellar companions, which means the inclination (and hence the true mass) of the planet are still unknown.[8]

The GJ 3021 planetary system[5]
Companion
(in order from star)
Mass Semimajor axis
(AU)
Orbital period
(days)
Eccentricity Inclination Radius
b >3.37 MJ 0.49 133.71 ± 0.20 0.511 ± 0.017

See also[edit]

References[edit]

  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. ^ Holmberg et al. (2009). "HD 1237". Geneva-Copenhagen Survey of Solar neighbourhood III. Retrieved 2010-12-04. 
  3. ^ a b c d e f Ghezzi, L. et al. (September 2010), "Stellar Parameters and Metallicities of Stars Hosting Jovian and Neptunian Mass Planets: A Possible Dependence of Planetary Mass on Metallicity", The Astrophysical Journal 720 (2): 1290–1302, arXiv:1007.2681, Bibcode:2010ApJ...720.1290G, doi:10.1088/0004-637X/720/2/1290 
  4. ^ a b Saffe, C. et al. (2005). "On the Ages of Exoplanet Host Stars". Astronomy and Astrophysics 443 (2): 609–626. arXiv:astro-ph/0510092. Bibcode:2005A&A...443..609S. doi:10.1051/0004-6361:20053452. 
  5. ^ a b Naef, D. et al. (2001). "The CORALIE survey for southern extrasolar planets V. 3 new extrasolar planets". Astronomy and Astrophysics 375 (1): 205–218. arXiv:astro-ph/0106255. Bibcode:2001A&A...375..205N. doi:10.1051/0004-6361:20010841. 
  6. ^ Chauvin, G. et al. (2007). "Characterization of the long-period companions of the exoplanet host stars: HD 196885, HD 1237 and HD 27442". Astronomy and Astrophysics 475 (2): 723–727. arXiv:0710.5918. Bibcode:2007A&A...475..723C. doi:10.1051/0004-6361:20067046. 
  7. ^ Han et al. (2001). "Preliminary astrometric masses for proposed extrasolar planetary companions". The Astrophysical Journal 548 (1): L57–L60. Bibcode:2001ApJ...548L..57H. doi:10.1086/318927. 
  8. ^ Pourbaix, D. and Arenou, F. (2001). "Screening the Hipparcos-based astrometric orbits of sub-stellar objects". Astronomy and Astrophysics 372 (3): 935–944. arXiv:astro-ph/0104412. Bibcode:2001A&A...372..935P. doi:10.1051/0004-6361:20010597. 

External links[edit]

Coordinates: Sky map 00h 16m 12.6775s, −79° 51′ 04.254″