Astronomy:HD 114762
HD 114762 is a triple star system[3][4] approximately 125 light-years (38.2 pc) away in the constellation Coma Berenices. It consists of a yellow-white F-type main-sequence star (HD 114762 A) and two red dwarf companions (HD 114762 Ab & HD 114762 B) approximately 0.36 & 130 AU distant.[3][4] Both are low-metal subdwarfs. Planets around such metal-poor stars are rare (three known cases are HD 22781, HD 111232, and HD 181720).[9] 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.[10]
The red dwarf companion is classified as an ultra-cool dwarf, with a spectral type around M9.[5] With a visual magnitude of 15 and separated from the primary by only three arcseconds, it can only be seen with a powerful telescope.[3] It is estimated to be around 10 billion years old, although the properties of such low-mass stars are very similar across a wide range of ages. It is calculated have only 8% of the mass of the Sun, a tenth of its radius, and with a temperature of about 2,645 K it produces less than a thousandth of its luminosity.[5]
Spectroscopic companion
In 1989, a companion object, HD 114762 Ab, was found orbiting HD 114762 A by Latham, et al., using Doppler spectroscopy,[11] but its existence was not confirmed until 1991 by Cochran, et al.[12] Its orbital distance and revolution is similar to that of Mercury, though it has twice the eccentricity.[12] It has a minimum mass of 10.69 |♃|J}}}}}}, 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 |♃|J}}}}}}. This makes it a red dwarf star, or a massive brown dwarf.[4] A 2020 study provided further confirmation of this, and revised the mass upwards to 147 MJ,[7] and in 2022 this mass was revised upwards still further, to 0.293 M☉, based on Gaia DR3 data and a similar upwards revision to the mass of the primary star.[6]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 Kane, Stephen R. et al. (2011). "Revised Orbit and Transit Exclusion for HD 114762b". The Astrophysical Journal Letters 735 (2): L41. doi:10.1088/2041-8205/735/2/L41. Bibcode: 2011ApJ...735L..41K.
- ↑ 3.0 3.1 3.2 3.3 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. doi:10.1086/342982. Bibcode: 2002ApJ...581..654P.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Kiefer, Flavien (17 October 2019). "Determining the mass of the planetary candidate HD 114762 b using Gaia". Astronomy & Astrophysics 632: L9. doi:10.1051/0004-6361/201936942. Bibcode: 2019A&A...632L...9K.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 Bowler, Brendan P.; Liu, Michael C.; Cushing, Michael C. (2009). "The Benchmark Ultracool Subdwarf HD 114762B: A Test of Low-metallicity Atmospheric and Evolutionary Models". The Astrophysical Journal 706 (2): 1114. doi:10.1088/0004-637X/706/2/1114. Bibcode: 2009ApJ...706.1114B.
- ↑ 6.0 6.1 6.2 6.3 Winn, Joshua N. (September 2022). "Joint Constraints on Exoplanetary Orbits from Gaia DR3 and Doppler Data". The Astronomical Journal 164 (5): 196. doi:10.3847/1538-3881/ac9126. Bibcode: 2022AJ....164..196W.
- ↑ 7.0 7.1 7.2 Kiefer, F. et al. (January 2021). "Determining the true mass of radial-velocity exoplanets with Gaia. Nine planet candidates in the brown dwarf or stellar regime and 27 confirmed planets". Astronomy & Astrophysics 645. doi:10.1051/0004-6361/202039168. Bibcode: 2021A&A...645A...7K.
- ↑ "HD 114762". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+114762.
- ↑ Adibekyan, Vardan (2019), "Heavy Metal Rules. I. Exoplanet Incidence and Metallicity", Geosciences 9 (3): 105, doi:10.3390/geosciences9030105, Bibcode: 2019Geosc...9..105A
- ↑ Maugh II, Thomas H. (4 August 1988). "Other Planets, Other Suns: Astronomers Say Star's Wobble Tells a Story". Los Angeles Times. http://articles.latimes.com/1988-08-04/news/mn-10212_1_standard-stars.
- ↑ 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. doi:10.1038/339038a0. Bibcode: 1989Natur.339...38L.
- ↑ 12.0 12.1 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. doi:10.1086/186167. Bibcode: 1991ApJ...380L..35C.
Coordinates: 
13h 12m 19.7427s, +17° 31′ 01.643″
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