HD 106315
Star in the constellation Virgo
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HD 106315, or K2-109, is a single star with a pair of close-orbiting exoplanets, located in the constellation of Virgo. Based on parallax measurements, this system lies at a distance of 356 light years from the Sun.[2] At that range, the star is too faint to be seen with the naked eye, as it has an apparent visual magnitude of 8.95.[3] But it is slowly drifting closer with a radial velocity of −3 km/s.[2] As of 2020[update], multiplicity surveys have not detected any stellar companions to HD 106315.[6]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Virgo[1] |
| Right ascension | 12h 13m 53.3962s[2] |
| Declination | −00° 23′ 36.553″[2] |
| Apparent magnitude (V) | 8.951[3] |
| Characteristics | |
| Evolutionary stage | Main sequence[2] |
| Spectral type | F5V[4] |
| B−V color index | 0.45[3] |
| Astrometry | |
| Radial velocity (Rv) | −3.2±0.3[2] km/s |
| Proper motion (μ) | RA: −2.36±0.03 mas/yr[2] Dec.: 11.943±0.019 mas/yr[2] |
| Parallax (π) | 9.1725±0.0221 mas[2] |
| Distance | 355.6 ± 0.9 ly (109.0 ± 0.3 pc) |
| Details | |
| Mass | 1.105+0.028 −0.036[5] M☉ |
| Radius | 1.286+0.049 −0.040[5] R☉ |
| Luminosity | 2.432+0.057 −0.234[5] L☉ |
| Surface gravity (log g) | 4.261+0.027 −0.024[5] cgs |
| Temperature | 6,300±37[5] K |
| Metallicity [Fe/H] | −0.268+0.060 −0.071[5] dex |
| Rotation | 4.78±0.15[6] |
| Rotational velocity (v sin i) | 12.9±0.4[5] km/s |
| Age | 3.987+0.802 −0.516[5] Gyr |
| Other designations | |
| BD+00 2910, HD 106316, TYC 4940-868-1, GSC 04940-00868, 2MASS J12135339-0023365, K2-109, Gaia DR3 3698307419878650240[7] | |
| Database references | |
| SIMBAD | data |
The spectrum of HD 106315 presents as an ordinary F-type main-sequence star with a stellar classification of F5V,[4] indicating it is generating energy through hydrogen fusion at its core. It is estimated to be roughly four[5] billion years old but is spinning quickly with a rotation period of 5 days. The star is relatively metal-poor, having 60% of solar concentration of iron. It has only a low level of magnetic activity in its chromosphere, showing a minimal level of star spot coverage.[6] The star has 11% more mass and a 29% larger radius than the Sun. It is radiating 2.4 times the luminosity of the Sun from its photosphere at an effective temperature of 6,300 K.[5]
Planetary system
Two planets were detected by the transit method in 2017,[5] using data from the extended Kepler mission (K2). Their large planetary radii imply both planets have a massive steam atmosphere for planet b and hydrogen-helium atmosphere for planet c.[6] The planetary system of HD 106315 is rather unstable and current planetary orbits are the outcome of violent dynamical history,[8] strongly affected by relativistic effects.[9] The orbits of planets are nearly coplanar, and orbit of c is well aligned with the equatorial plane of the star, misalignment been equal to -10+3.6
−3.8°.[10]
Since 2017, a third outer planet with mass above 45M🜨 is suspected to exist in the system.[3]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 10.5±3.1[6] M🜨 | 0.0924+0.0011 −0.0012 |
9.55288±0.00021 | 0 | 87.6+3.0 −1.7° |
2.4±0.2 R🜨 |
| c | 12.0±3.8[6] M🜨 | 0.1565+0.0019 −0.0020 |
21.05652±0.00012 | 0 | 88.89+0.69 −0.51° |
4.379±0.086 R🜨 |