HD 106315
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−V color index 0.45[2]
Astrometry
Radial velocity (Rv)−3.2±0.3[1] km/s
Proper motion (μ) RA: −2.36±0.03 mas/yr[1]
Dec.: 11.943±0.019 mas/yr[1]
Parallax (π)9.1725 ± 0.0221 mas[1]
Distance355.6 ± 0.9 ly
(109.0 ± 0.3 pc)
Details
Mass1.105+0.028
−0.036[4] M☉
Radius1.286+0.049
−0.040[4] R☉
Luminosity2.432+0.057
−0.234[4] L☉
Surface gravity (log g)4.261+0.027
−0.024[4] cgs
Temperature6,300±37[4] K
Metallicity [Fe/H]−0.268+0.060
−0.071[4] dex
Rotation4.78±0.15[5]
Rotational velocity (v sin i)12.9±0.4[4] km/s
Age3.987+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
SIMBADdata

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.[1] 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.[2] But it is slowly drifting closer with a radial velocity of −3 km/s.[1] As of 2020, multiplicity surveys have not detected any stellar companions to HD 106315.[5]

The spectrum of HD 106315 presents as an ordinary F-type main-sequence star with a stellar classification of F5V,[3] indicating it is generating energy through hydrogen fusion at its core. It is estimated to be roughly four[4] 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.[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 its photosphere at an effective temperature of 6,300 K.[4]

Planetary system

Two planets were detected by the transit method in 2017,[4] 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.[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 of c 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 45MEarth is suspected to exist in the system.[2]

The HD 106315 planetary system
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🜨

References

  1. 1 2 3 4 5 6 7 8 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.
  2. 1 2 3 4 Crossfield, Ian J. M.; et al. (2017). "Two Small Transiting Planets and a Possible Third Body Orbiting HD 106315". The Astronomical Journal. 153 (6): 255. arXiv:1701.03811. Bibcode:2017AJ....153..255C. doi:10.3847/1538-3881/aa6e01. S2CID 55601944.
  3. 1 2 Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey. 5. Bibcode:1999MSS...C05....0H.
  4. 1 2 3 4 5 6 7 8 9 10 11 Rodriguez, Joseph E.; et al. (2017). "A Multi-planet System Transiting the V = 9 Rapidly Rotating F-Star HD 106315". The Astronomical Journal. 153 (6): 256. arXiv:1701.03807. Bibcode:2017AJ....153..256R. doi:10.3847/1538-3881/aa6dfb. S2CID 118983037.
  5. 1 2 3 4 5 6 Kosiarek, Molly R.; et al. (2021). "Physical Parameters of the Multiplanet Systems HD 106315 and GJ 9827". The Astronomical Journal. 161 (1): 47. arXiv:2009.03398. Bibcode:2021AJ....161...47K. doi:10.3847/1538-3881/abca39. S2CID 221534625.
  6. ↑ "HD 106315", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 26 July 2022
  7. ↑ Turrini, D.; et al. (2020). "Normalized angular momentum deficit: A tool for comparing the violence of the dynamical histories of planetary systems". Astronomy and Astrophysics. 636: A53. arXiv:2003.05366. Bibcode:2020A&A...636A..53T. doi:10.1051/0004-6361/201936301. S2CID 212657397.
  8. ↑ Marzari, F.; Nagasawa, M. (2020). "Secular evolution of close-in planets: The effects of general relativity". Monthly Notices of the Royal Astronomical Society. 493 (1): 427. arXiv:2001.09801. Bibcode:2020MNRAS.493..427M. doi:10.1093/mnras/staa271.
  9. ↑ Zhou, George; et al. (2018). "The Warm Neptunes around HD 106315 Have Low Stellar Obliquities". The Astronomical Journal. 156 (3): 93. arXiv:1807.00024. Bibcode:2018AJ....156...93Z. doi:10.3847/1538-3881/aad085. S2CID 118864208.
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