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] | |
Companion | 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 | |
Database references | |
SIMBAD | data |
Exoplanet Archive | data |
ARICNS | data |
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]
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]