HD 1237

HD 1237 is a binary star system approximately 57 light-years away in the constellation of Hydrus (the Water Snake).

HD 1237
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Hydrus
Right ascension 00h 16m 12.6791s[1]
Declination −79° 51′ 04.2447″[1]
Apparent magnitude (V) 6.59
Characteristics
HD 1237 A
Spectral type G6 V
B−V color index 0.749
HD 1237 B
Spectral type M4 V[2]
Astrometry
Radial velocity (Rv)−5.2±0.2[3] km/s
Proper motion (μ) RA: 433.908±0.044[1] mas/yr
Dec.: −56.322±0.039[1] mas/yr
Parallax (π)56.9319 ± 0.0235[1] mas
Distance57.29 ± 0.02 ly
(17.565 ± 0.007 pc)
Absolute magnitude (MV)5.37 ± 0.01[4]
Details
HD 1237 A
Mass1.00 ± 0.10[5] M☉
Radius0.86 ± 0.07[5] R☉
Luminosity0.64[5] L☉
Surface gravity (log g)4.58 ± 0.09[5] cgs
Temperature5,572 ± 40[5] K
Metallicity [Fe/H]0.12 ± 0.04[5] dex
Rotation7.0±0.7 d[3]
Rotational velocity (v sin i)5.3±1.0[3] km/s
Age800[6] Myr
HD 1237 B
Mass0.13[2] M☉
Other designations
2 G. Hydri, CD−80° 9, GJ 3021, HD 1237, HIP 1292, SAO 258219
Database references
SIMBADdata

The visible star in the system, A, is considered to be a solar analog due close mass to the sun. HD 1237 differs from the sun in that HD 1237 is much younger, has high metallicity, has much cooler temperature and is in a binary system. 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.[7]

Stellar components

As a nearby Sun-like star, the last decade has seen HD 1237 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.[6] 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 was discovered in 2006 during a deep imaging survey conducted at the European Southern Observatory using the Very Large Telescope.[8] HD 1237 B is a M4 red dwarf star at a projected separation of 68 AU.[2]

Planetary system

Announced in 2000, the Jovian planet GJ 3021 b (GJ 3021 being an alternate less-used designation for this star) orbits about 0.5 astronomical units from HD 1237 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.[9] 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.[10]

The HD 1237 planetary system[7]
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

References
  1. 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. 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.
  3. Alvarado-Gómez, J. D.; et al. (2015). "Activity and magnetic field structure of the Sun-like planet-hosting star HD 1237". Astronomy and Astrophysics. 582. A38. arXiv:1507.04117. Bibcode:2015A&A...582A..38A. doi:10.1051/0004-6361/201525771. S2CID 39311967.
  4. Holmberg; et al. (2009). "HD 1237". Geneva-Copenhagen Survey of Solar neighbourhood III. Retrieved 2010-12-04.
  5. 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, S2CID 118565025
  6. 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. S2CID 11616693.
  7. 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. S2CID 16606841.
  8. Chauvin, G.; et al. (2006). "Probing long-period companions to planetary hosts". Astronomy and Astrophysics. 456 (3): 1165–1172. arXiv:astro-ph/0606166. Bibcode:2006A&A...456.1165C. doi:10.1051/0004-6361:20054709. S2CID 15611548.
  9. 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.
  10. Pourbaix, D.; 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. S2CID 378792.

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