| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Virgo |
| Right ascension | 12h 13m 53.3962s[1] |
| Declination | −00° 23′ 36.5534″[1] |
| Apparent magnitude (V) | 8.951[2] |
| Characteristics | |
| Evolutionary stage | Main sequence |
| Spectral type | F5V[3] |
| B−Vcolor index | 0.45[2] |
| Astrometry | |
| Radial velocity (Rv) | −3.2±0.3[1] km/s |
| Proper motion (μ) | RA: −2.36±0.03mas/yr[1] Dec.: 11.943±0.019mas/yr[1] |
| Parallax (π) | 9.1725±0.0221 mas[1] |
| Distance | 355.6 ± 0.9 ly (109.0 ± 0.3 pc) |
| Details | |
| Mass | 1.105+0.028 −0.036[4] M☉ |
| Radius | 1.286+0.049 −0.040[4] R☉ |
| Luminosity | 2.432+0.057 −0.234[4] L☉ |
| Surface gravity (log g) | 4.261+0.027 −0.024[4] cgs |
| Temperature | 6,300±37[4] K |
| Metallicity [Fe/H] | −0.268+0.060 −0.071[4] dex |
| Rotation | 4.78±0.15[5] |
| Rotational velocity (v sin i) | 12.9±0.4[4] km/s |
| Age | 3.987+0.802 −0.516[4] Gyr |
| Other designations | |
| BD+00 2910,HD 106316,TYC 4940-868-1,GSC 04940-00868,2MASS J12135339-0023365, K2-109, Gaia DR3 3698307419878650240[6] | |
| Database references | |
| SIMBAD | data |
HD 106315, or K2-109, is a singlestar with a pair of close-orbitingexoplanets, located in theconstellation ofVirgo. Based onparallax measurements, this system lies at a distance of 356 light years from the Sun.[1] At that range, the star is too faint to be seen with the naked eye, as it has anapparent visual magnitude of 8.95.[2] But it is slowly drifting closer with aradial velocity of −3 km/s.[1] As of 2020[update], multiplicity surveys have not detected any stellar companions to HD 106315.[5]
Thespectrum of HD 106315 presents as an ordinaryF-type main-sequence star with astellar classification of F5V,[3] indicating it is generating energy throughhydrogen fusion at itscore. It is estimated to be roughly four[4] billion years old but is spinning quickly with arotation period of 5 days. The star is relatively metal-poor, having 60% of solar concentration of iron. It has only a low level ofmagnetic activity in itschromosphere, showing a minimal level ofstar spot coverage.[5] 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 itsphotosphere at aneffective temperature of 6,300 K.[4]
Two planets were detected by thetransit method in 2017,[4] using data from the extendedKepler mission (K2). Their large planetary radii imply both planets have a massive steam atmosphere for planetb and hydrogen-helium atmosphere for planetc.[5] The planetary system of HD 106315 is rather unstable and current planetary orbits are the outcome of violent dynamical history,[7] strongly affected by relativistic effects.[8] The orbits of planets are nearly coplanar, and orbit ofc is well aligned with the equatorial plane of the star, misalignment been equal to -10+3.6
−3.8°.[9]
Since 2017, a third outer planet with mass above 45ME is suspected to exist in the system.[2]
| Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 10.5±3.1[5] 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[5] M🜨 | 0.1565+0.0019 −0.0020 | 21.05652±0.00012 | 0 | 88.89+0.69 −0.51° | 4.379±0.086 R🜨 |
