HD 77338

HD 77338

Observation data Epoch J2000      Equinox J2000
Constellation	Pyxis[1]
Right ascension	09^h 01^m 12.493^s[2]
Declination	−25° 31′ 37.43″[2]
Apparent magnitude (V)	8.63[1]
Characteristics
Evolutionary stage	subgiant star
Spectral type	K0 IV[3]
B−V color index	0.833±0.002[1]
Astrometry
Radial velocity (Rv)	8.209[2] km/s
Proper motion (μ)	RA: 40.095 mas/yr[2] Dec.: −271.640 mas/yr[2]
Parallax (π)	21.8739 ± 0.0192 mas[2]
Distance	149.1 ± 0.1 ly (45.72 ± 0.04 pc)
Absolute magnitude (MV)	5.58[1]
Details[4]
Mass	0.942 M☉
Radius	0.97±0.02[5] R☉
Luminosity	0.708 L☉
Surface gravity (log g)	4.42 cgs
Temperature	5,315 K
Metallicity [Fe/H]	0.16 dex
Rotation	33.4±10.0 d[6]
Rotational velocity (v sin i)	1.3 km/s
Age	9.5 Gyr
Other designations
CD−25 6797, HD 77338, HIP 44291, TYC 6589-761-1, 2MASS J09011248-2531371[7]
Database references
SIMBAD	data

HD 77338 is a star with a close orbiting exoplanet companion in the southern constellation of Pyxis. It is too dim to be visible with the naked eye, having an apparent visual magnitude of 8.63.[1] The system is located at a distance of 149 light years, and it is drifting further away with a heliocentric radial velocity of 8.2 km/s.[2]

The spectrum of this star presents as a K-type subgiant with a stellar classification of K0 IV.[3] This indicates the star has exhausted the supply of hydrogen at its core and has begun to evolve away from the main sequence. It has 94%[4] of the mass of the Sun and 97% of the Sun's girth.[5] The star is spinning with a rotation period of roughly 33 days.[6] It is radiating 71% of the luminosity of the Sun from its photosphere at an effective temperature of 5,315 K.[4]

HD 77338 is enriched in its concentration of elements more massive than helium compared to the Sun, with a metallicity of 0.16,[5] but is much older at an age of 9.5 billion years.[4] It is unusually enriched in heavy elements for a star of its age. The anomalously high abundance of ions of manganese may indicate the star has recently passed through the common shell stage (engulfed a planet).[8]

Planetary system

In 2012, a planet, named HD 77338b, was discovered by the radial velocity method on a tight orbit with uncertain eccentricity.[9] Its equilibrium temperature is 954.8 K.[10]

The HD 77338 planetary system[11][9]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	≥15.9^+4.7 −5.3 M🜨	0.0614^+0.0031 −0.0034	5.73610±0.0015	0.09^+0.22 −0.09	—	—

References

1. 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.
2. 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.
3. Houk, Nancy; Smith-Moore, M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.
4. Pavlenko, Y. V.; et al. (2019), "Masses, oxygen, and carbon abundances in CHEPS dwarf stars", Astronomy & Astrophysics, 621: A112, arXiv:1811.05011, Bibcode:2019A&A...621A.112P, doi:10.1051/0004-6361/201834138, S2CID 119103484
5. Stassun, Keivan G.; et al. (2016), "Accurate Empirical Radii and Masses of Planets and Their Host Stars with Gaia Parallaxes", The Astronomical Journal, 153 (3): 136, arXiv:1609.04389, Bibcode:2017AJ....153..136S, doi:10.3847/1538-3881/aa5df3, S2CID 119219062.
6. Suárez Mascareño, A.; et al. (2015), "Rotation periods of late-type dwarf stars from time series high-resolution spectroscopy of chromospheric indicators", Monthly Notices of the Royal Astronomical Society, 452 (3): 2745–2756, arXiv:1506.08039, Bibcode:2015MNRAS.452.2745S, doi:10.1093/mnras/stv1441.
7. "HD 77338". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-01-19.
8. Kushniruk, I. O.; et al. (2015), Abundances in the atmosphere of the metal-rich planet-host star HD 77338, arXiv:1505.05843
9. Jenkins, J. S.; et al. (2013), "A Hot Uranus Orbiting the Super Metal-Rich Star Hd 77338 and the Metallicity-Mass Connection", The Astrophysical Journal, 766 (2): 67, arXiv:1207.1012, Bibcode:2013ApJ...766...67J, doi:10.1088/0004-637X/766/2/67, S2CID 16971803
10. HD 77338 b is an exoplanet orbiting the star HD 77338, located about 149.3 light-years (45.8 pc) away from Solar System. Its discovery was publicly announced on 2012
11. Stassun, Keivan G.; et al. (2017), "Accurate Empirical Radii and Masses of Planets and Their Host Stars with Gaia Parallaxes", The Astronomical Journal, 153 (3): 136, arXiv:1609.04389, Bibcode:2017AJ....153..136S, doi:10.3847/1538-3881/aa5df3, S2CID 119219062