HD 114762

HD 114762 is a triple star system[4][5] approximately 126 light-years (38.6 pc) away in the constellation Coma Berenices. It consists of a yellow-white F-type main-sequence star (HD 114762 A) and two red or brown dwarf companions (HD 114762 Ab & HD 114762 B) approximately 0.36 & 130 AU distant.[4][5] Both are low-metal subdwarfs. Planets around such metal-poor stars are rare (three known cases are HD 22781, HD 111232, and HD 181720).[6] A telescope or strong binoculars are needed to view the primary. HD 114762 had been used by scientists as a "standard star", one whose radial velocity is well established, but with the discovery of the spectroscopic companion HD 114762 Ab its usefulness as a standard has been called into question.[7]

HD 114762
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Coma Berenices
Right ascension 13h 12m 19.7428s[1]
Declination +17° 31′ 01.654″[1]
Apparent magnitude (V) 7.30
Characteristics
A
Evolutionary stage Main sequence
Spectral type F9V
U−B color index -0.05
B−V color index 0.54
V−R color index 0.29
R−I color index 0.20
J−H color index 0.25
J−K color index 0.33
B
Evolutionary stage Main sequence
Spectral type M6?V
J−K color index 0.70
Astrometry
Radial velocity (Rv)51.03±0.14 km/s
Proper motion (μ) RA: −582.611±0.041[1] mas/yr
Dec.: −0.520±0.039[1] mas/yr
Parallax (π)25.88 ± 0.46[1] mas
Distance126 ± 2 ly
(38.6 ± 0.7 pc)
Details[2]
Mass0.84 M☉
Radius1.24±0.1 R☉
Temperature5934.0±80.0 K
Metallicity [Fe/H]−0.71±0.08 dex
Age11.8±3.9 Gyr
Other designations
BD+18 2700, HD 114762, HIP 64426, SAO 100458, 2MASS J13121982+1731016[3]
Database references
SIMBADdata
Exoplanet Archivedata
ARICNSdata
Extrasolar Planets
Encyclopaedia		data

Spectroscopic companion

In 1989, a companion object, HD 114762 Ab, was found orbiting HD 114762 A by Latham, et al., using Doppler spectroscopy,[8] but its existence was not confirmed until 1991 by Cochran, et al.[9] It has a minimum mass of 10.69 MJ, and thus was originally thought to be a massive exoplanet; however, in 2019, its inclination was determined by Gaia astrometry, giving it a true mass of 107 MJ. This makes it a red dwarf star, or a massive brown dwarf.[5] A 2020 study provided further confirmation of this, and revised the mass updwards to 147 MJ.[10] Its orbital distance and revolution is similar to that of Mercury, though it has twice the eccentricity.[9]

The HD 114762 planetary system[5][10]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 147.0+39.3
−42.0 MJ		 0.363±0.0121 83.9151±0.0030 0.566+0.012
−0.011		 4.940+1.773
−0.942°		 —

References
  1. Brown, A. G. A.; et al. (2016). "Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties". Astronomy and Astrophysics. 595. A2. arXiv:1609.04172. Bibcode:2016A&A...595A...2G. doi:10.1051/0004-6361/201629512. S2CID 1828208. Gaia Data Release 1 catalog entry.
  3. "HD 114762". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-01-16.
  4. Patience, J.; White, R. J.; Ghez, A. M.; McCabe, C.; McLean, I. S.; et al. (December 2002). "Stellar Companions to Stars with Planets". The Astrophysical Journal. 581 (1): 654–665. arXiv:astro-ph/0207538. Bibcode:2002ApJ...581..654P. doi:10.1086/342982. S2CID 119519887.
  5. Kiefer, Flavien (17 October 2019). "Determining the mass of the planetary candidate HD 114762 b using Gaia". Astronomy & Astrophysics. 632: L9. arXiv:1910.07835. Bibcode:2019A&A...632L...9K. doi:10.1051/0004-6361/201936942. S2CID 204743831.
  6. Adibekyan, Vardan (2019), "Heavy Metal Rules. I. Exoplanet Incidence and Metallicity", Geosciences, 9 (3): 105, arXiv:1902.04493, Bibcode:2019Geosc...9..105A, doi:10.3390/geosciences9030105, S2CID 119089419
  7. Maugh II, Thomas H. (4 August 1988). "Other Planets, Other Suns: Astronomers Say Star's Wobble Tells a Story". Los Angeles Times. Retrieved 7 September 2014.
  8. Latham, David W.; Mazeh, Tsevi; Stefanik, Robert P.; Mayor, Michel; Burki, Gilbert (May 1989). "The unseen companion of HD114762 - A probable brown dwarf". Nature. 339 (6219): 38–40. Bibcode:1989Natur.339...38L. doi:10.1038/339038a0. S2CID 4324036.
  9. Cochran, William D.; Hatzes, Artie P.; Hancock, Terry J. (10 October 1991). "Constraints on the Companion Object to HD 114762". The Astrophysical Journal. 380: L35–L38. Bibcode:1991ApJ...380L..35C. doi:10.1086/186167.
  10. Kiefer, Flavien; Hébrard, Guillaume; Lecavelier, Alain; Martioli, Eder; Dalal, Shweta; Vidal-Madjar, Alfred (2021). "Determining the true mass of radial-velocity exoplanets with Gaia 9 planet candidates in the brown-dwarf/stellar regime and 27 confirmed planets". Astronomy & Astrophysics. A7: 645. arXiv:2009.14164. doi:10.1051/0004-6361/202039168. S2CID 221995447.

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