HD 77338
Star in the constellation Pyxis
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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 ICRS | |
|---|---|
| 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 | main sequence[2] |
| 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 |
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]
| 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 |
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