HD 4313

HD 4313

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Pisces
Right ascension	00^h 45^m 40.3578^s[1]
Declination	+07° 50′ 42.075″[1]
Apparent magnitude (V)	7.83[2]
Characteristics
Evolutionary stage	Subgiant[3]
Spectral type	K2 IV^[citation needed]
B−V color index	0.963±0.017[2]
Astrometry
Radial velocity (Rv)	14.48±0.23[2] km/s
Proper motion (μ)	RA: −6.281 mas/yr[1] Dec.: 6.566 mas/yr[1]
Parallax (π)	7.3090 ± 0.0879 mas[1]
Distance	446 ± 5 ly (137 ± 2 pc)
Absolute magnitude (MV)	2.17[2]
Details
Mass	1.61^+0.13 −0.12[4] M☉
Radius	5.15^+0.18 −0.17[5] R☉
Luminosity	15.81[2] L☉
Surface gravity (log g)	3.24[6] cgs
Temperature	4,966±40[5] K
Metallicity [Fe/H]	0.05±0.10[5] dex
Rotational velocity (v sin i)	1.91±0.25[6] km/s
Age	2.03^+0.64 −0.45[5] Gyr
Other designations
BD+07°104, Gaia DR2 2557541493057378048, HD 4313, HIP 3574, 2MASS J00454035+0750421[7]
Database references
SIMBAD	data

HD 4313 is a star with an orbiting exoplanetary companion in the constellation of Pisces. It has an apparent visual magnitude of 7.83,[2] which is too faint to be reading visible to the unaided eye. The systam is located at a distance of 446 light years based on parallax, and is drifting further away with a radial velocity of 14.5 km/s.[2] This is a single star, which means it has no binary partners, at least in range of projected separations from 6.85 to 191.78 AU.[8] It hosts an extrasolar planet.

This is an aging K-type star with a mass of nearly twice the Sun, although different methods give mass estimates which differ as much as 0.5 M_☉.[5] It is a swollen star with 5.14 times the radius of the Sun, and has a cool effective temperature of 4,966±40 k. The "IV" in the spectral class means it's a K-type subgiant[3] star which has exhausted the hydrogen at its core, and cooling and expanding to become a red giant. It is around two billion years in age and is spinning with a projected rotational velocity of 1.9 km/s.

Planetary system

HD 4313 has a superjovian exoplanet orbiting it. This exoplanet was discovered in 2010.[9] It is orbiting the star at a distance of 1.16 AU with an orbital period of 356 days and an eccentricity (ovalness) of 0.15. As the orbital inclination is unknown, only a lower bound on the mass can be determined. The exoplanet has at least 1.2 times the mass of Jupiter.[3]

The HD 4313 planetary system[3]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	≥ 1.927±0.090 MJ	1.157±0.097	356.21±0.88	0.147±0.047	—	1.2 RJ

References

1. Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
2. Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
3. Luhn, Jacob K.; et al. (2019). "Retired A Stars and Their Companions. VIII. 15 New Planetary Signals around Subgiants and Transit Parameters for California Planet Search Planets with Subgiant Hosts". The Astronomical Journal. 157 (4). 149. arXiv:1811.03043. Bibcode:2019AJ....157..149L. doi:10.3847/1538-3881/aaf5d0. S2CID 102486961.
4. Malla, Sai Prathyusha; Stello, Dennis; Huber, Daniel; Montet, Benjamin T.; Bedding, Timothy R.; Fredslund Andersen, Mads; Grundahl, Frank; Jessen-Hansen, Jens; Hey, Daniel R.; Palle, Pere L.; Deng, Licai; Zhang, Chunguang; Chen, Xiaodian; Lloyd, James; Antoci, Victoria (2020). "Asteroseismic masses of four evolved planet-hosting stars using SONG and TESS: Resolving the retired A-star mass controversy". Monthly Notices of the Royal Astronomical Society. 496 (4): 5423–5435. arXiv:2006.07649. doi:10.1093/mnras/staa1793.
5. North, Thomas S. H.; Campante, Tiago L.; Miglio, Andxsrea; Davies, Guy R.; Grunblatt, Samuel K.; Huber, Daniel; Kuszlewicz, James S.; Lund, Mikkel N.; Cooke, Benjamin F.; Chaplin, William J. (2017). "The masses of retired a stars with asteroseismology: Kepler and K2 observations of exoplanet hosts". Monthly Notices of the Royal Astronomical Society. 472 (2): 1866–1878. arXiv:1708.00716. doi:10.1093/mnras/stx2009.
6. "Exoplanet Archive". exoplanetarchive.ipac.caltech.edu. Retrieved 2020-12-11.
7. "HD 4313". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2023-12-11.
8. Wittrock, Justin M.; Kane, Stephen R.; Horch, Elliott P.; Howell, Steve B.; Ciardi, David R.; Everett, Mark E. (2017). "Exclusion of Stellar Companions to Exoplanet Host Stars". The Astronomical Journal. 154 (5): 184. arXiv:1709.05315. Bibcode:2017AJ....154..184W. doi:10.3847/1538-3881/aa8d69. S2CID 55789971.
9. Johnson, John Asher; Howard, Andrew W.; Bowler, Brendan P.; Henry, Gregory W.; Marcy, Geoffrey W.; Wright, Jason T.; Fischer, Debra A.; Isaacson, Howard (2010). "Retired a Stars and Their Companions. IV. Seven Jovian Exoplanets from Keck Observatory1". Publications of the Astronomical Society of the Pacific. 122 (892): 701–711. arXiv:1003.3445. Bibcode:2010PASP..122..701J. doi:10.1086/653809. S2CID 188131.