HD 27631

HD 27631

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Horologium
Right ascension	04^h 19^m 45.46920^s[1]
Declination	–41° 57′ 36.9527″[1]
Apparent magnitude (V)	8.243±0.012[2]
Characteristics
Spectral type	G3IV[2]
B−V color index	0.721±0.009[2]
Astrometry
Radial velocity (Rv)	21.04±0.13[1] km/s
Proper motion (μ)	RA: –41.139 mas/yr[1] Dec.: –91.908 mas/yr[1]
Parallax (π)	19.9263 ± 0.0160 mas[1]
Distance	163.7 ± 0.1 ly (50.18 ± 0.04 pc)
Absolute magnitude (MV)	4.97[3]
Details[2]
Mass	0.944±0.032 M☉
Radius	0.923±0.033 R☉
Luminosity	0.97[3] L☉
Surface gravity (log g)	4.455±0.038 cgs
Temperature	5,737±36 K
Metallicity [Fe/H]	−0.12±0.05 dex
Rotation	~31 d
Age	4.010±2.892 Gyr
Other designations
CD−42°1464, HD 27631, HIP 20199, SAO 216753[4]
Database references
SIMBAD	data
Exoplanet Archive	data

HD 27631 is a star with an orbiting exoplanet in the southern constellation of Horologium. It is too faint to be visible to the naked eye, having an apparent visual magnitude of 8.24.^[2] The distance to this system is 164 light years based on parallax measurements. It is drifting further away with a radial velocity of 21 km/s.^[1]

This is a G-type star with a stellar classification of G3IV,^[2] suggesting it is a subgiant star that is evolving off the main sequence after exhausting the supply of hydrogen at its core. It is smaller than the Sun, with 94% of its mass and 92% of the radius.^[2] The star is radiating 97%^[3] of the luminosity of the Sun from its photosphere at an effective temperature of 5,737 K.^[2] The estimated age is roughly 4.4 billion years^[5] and it is spinning slowly with a rotation period of around 31 days.^[2]

A survey in 2015 has ruled out the existence of any stellar companions at projected distances above 40 astronomical units.^[6]

Planetary system

From 1998 to 2012, the star was under observation from the CORALIE echelle spectrograph at La Silla Observatory. In 2012, a long-period, wide-orbiting exoplanet was deduced by radial velocity. This was published in November.^[5] In 2023, the inclination and true mass of HD 27631 b were determined via astrometry.^[7] This is a super-jovian planet with around 1.6 times the mass of Jupiter. It is orbiting the host star at a separation of 3.22 AU with an eccentricity (ovalness) of 0.16 and an orbital period of six years.

The HD 27631 planetary system^[7]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (years)	Eccentricity	Inclination	Radius
b	1.56+0.2 −0.15 MJ	3.22+0.065 −0.064	5.95+0.13 −0.12	0.163±0.057	74+11 −15 or 106+15 −11°	—

References

1. 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. Barbato, D.; et al. (August 2018). "Exploring the realm of scaled solar system analogues with HARPS". Astronomy & Astrophysics. 615: 21. arXiv:1804.08329. Bibcode:2018A&A...615A.175B. doi:10.1051/0004-6361/201832791. S2CID 119099721. A175.
3. 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.
4. "HD 27631". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2023-12-12.
5. Marmier, M.; et al. (2013). "The CORALIE survey for southern extrasolar planets XVII. New and updated long period and massive planets". Astronomy and Astrophysics. 551. A90. arXiv:1211.6444. Bibcode:2013A&A...551A..90M. doi:10.1051/0004-6361/201219639. S2CID 59467665.
6. Mugrauer, M.; Ginski, C. (12 May 2015). "High-contrast imaging search for stellar and substellar companions of exoplanet host stars". Monthly Notices of the Royal Astronomical Society. 450 (3): 3127–3136. Bibcode:2015MNRAS.450.3127M. doi:10.1093/mnras/stv771. hdl:1887/49340. Retrieved 19 June 2020.
7. Xiao, Guang-Yao; Liu, Yu-Juan; et al. (March 2023). "The Masses of a Sample of Radial-Velocity Exoplanets with Astrometric Measurements". Research in Astronomy and Astrophysics. 23 (5). arXiv:2303.12409. Bibcode:2023RAA....23e5022X. doi:10.1088/1674-4527/accb7e.

External links

• "HD 27631 b". Extrasolar Planets Encyclopaedia. 2013.