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 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.[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
- ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b c Kane, Stephen R.; et al. (2011). "Revised Orbit and Transit Exclusion for HD 114762b". The Astrophysical Journal Letters. 735 (2). L41. arXiv:1106.1434. Bibcode:2011ApJ...735L..41K. doi:10.1088/2041-8205/735/2/L41. S2CID 118409104.
- ^ a b c d 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.
- ^ a b c d e f g h 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.
- ^ a b c d e f g h i j 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. arXiv:0910.1604. Bibcode:2009ApJ...706.1114B. doi:10.1088/0004-637X/706/2/1114. S2CID 119112746.
- ^ a b c d Winn, Joshua N. (September 2022). "Joint Constraints on Exoplanetary Orbits from Gaia DR3 and Doppler Data". The Astronomical Journal. 164 (5): 196. arXiv:2209.05516. Bibcode:2022AJ....164..196W. doi:10.3847/1538-3881/ac9126. S2CID 252211643.
- ^ a b c 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 A7. arXiv:2009.14164. Bibcode:2021A&A...645A...7K. doi:10.1051/0004-6361/202039168. S2CID 221995447.
- ^ "HD 114762". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-01-16.
- ^ 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
- ^ 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.
- ^ 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.
- ^ a b 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.
