HD 114762
Triple star system in the constellation Coma Berenices
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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]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Coma Berenices |
| Right ascension | 13h 12m 19.74107s[1] |
| Declination | +17° 31′ 01.6303″[1] |
| Apparent magnitude (V) | 7.30[2] + 15.00[3] |
| Characteristics | |
| A | |
| Evolutionary stage | Main sequence |
| Spectral type | F9V[4] |
| B−V color index | 0.525[2] |
| B | |
| Evolutionary stage | Main sequence |
| Spectral type | sdM9[5] |
| J−K color index | 0.70 |
| Astrometry | |
| Radial velocity (Rv) | 49.63±0.18[1] km/s |
| Proper motion (μ) | RA: −580.999 mas/yr[1] Dec.: 1.062 mas/yr[1] |
| Parallax (π) | 26.1979±0.1082 mas[1] |
| Distance | 124.5 ± 0.5 ly (38.2 ± 0.2 pc) |
| Orbit[6] | |
| Name | HD 114762 Ab |
| Period (P) | 83.91712±0.00064 d |
| Semi-major axis (a) | 0.361±0.012 AU[7] |
| Eccentricity (e) | 0.3442±0.0012 |
| Inclination (i) | 2.8±0.6° |
| Periastron epoch (T) | 2449969.202±0.048 |
| Argument of periastron (ω) (primary) | 201.3±1.0[7]° |
| Semi-amplitude (K1) (primary) | 0.6201±0.00085 km/s |
| Details | |
| HD 114762 A | |
| Mass | 1.046±0.040[6] M☉ |
| Radius | 1.24±0.05[2] R☉ |
| Surface gravity (log g) | 4.18±0.03[4] cgs |
| Temperature | 5869±13[4] K |
| Metallicity [Fe/H] | −0.72+0.05 −0.07[4] dex |
| Age | 12±4[4] Gyr |
| HD 114762 Ab | |
| Mass | 0.293+0.103 −0.056[6] M☉ |
| HD 114762 B | |
| Mass | 0.0879[5] M☉ |
| Radius | 0.100[5] R☉ |
| Luminosity | 0.00043[5] L☉ |
| Surface gravity (log g) | 5.381[5] cgs |
| Temperature | 2,645[5] K |
| Metallicity [Fe/H] | −0.71[5] dex |
| Age | ~10[5] Gyr |
| Other designations | |
| BD+18 2700, HD 114762, HIP 64426, SAO 100458, 2MASS J13121982+1731016[8] | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
| ARICNS | data |
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]