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]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Pyxis[1] |
| Right ascension | 09h 01m 12.493s[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 | |
| Database references | |
| SIMBAD | data |
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
editIn 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]
| 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
edit- ^ a b c d e 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.
- ^ a b c d e f 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.
- ^ a b 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.
- ^ a b c d 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
- ^ a b c 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.
- ^ a b 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.
- ^ "HD 77338". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-01-19.
- ^ Kushniruk, I. O.; et al. (2015), Abundances in the atmosphere of the metal-rich planet-host star HD 77338, arXiv:1505.05843
- ^ a b 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
- ^ 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
- ^ 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