Astronomy:HD 77338

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Short description: Star in the constellation Pyxis
HD 77338
Observation data
Equinox J2000.0]] (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 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[2] mas/yr
Dec.: −271.640[2] mas/yr
Parallax (π)21.8739 ± 0.0192[2] mas
Distance149.1 ± 0.1 ly
(45.72 ± 0.04 pc)
Absolute magnitude (MV)5.58[1]
Details[4]
Mass0.942 M
Radius0.97±0.02[5] R
Luminosity0.708 L
Surface gravity (log g)4.42 cgs
Temperature5,315 K
Metallicity [Fe/H]0.16 dex
Rotation33.4±10.0 d[6]
Rotational velocity (v sin i)1.3 km/s
Age9.5 Gyr
Other designations
CD−25 6797, HD 77338, HIP 44291, TYC 6589-761-1, 2MASS J09011248-2531371[7]
Database references
SIMBADdata

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. 1.0 1.1 1.2 1.3 1.4 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode2012AstL...38..331A. 
  2. 2.0 2.1 2.2 2.3 2.4 2.5 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode2021A&A...649A...1G.  Gaia EDR3 record for this source at VizieR.
  3. 3.0 3.1 Houk, Nancy; Smith-Moore, M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode1988mcts.book.....H. 
  4. 4.0 4.1 4.2 4.3 Pavlenko, Y. V. et al. (2019), "Masses, oxygen, and carbon abundances in CHEPS dwarf stars", Astronomy & Astrophysics 621: A112, doi:10.1051/0004-6361/201834138, Bibcode2019A&A...621A.112P 
  5. 5.0 5.1 5.2 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, doi:10.3847/1538-3881/aa5df3, Bibcode2017AJ....153..136S. 
  6. 6.0 6.1 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, doi:10.1093/mnras/stv1441, Bibcode2015MNRAS.452.2745S. 
  7. "HD 77338". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+77338. 
  8. Kushniruk, I. O. et al. (2015), Abundances in the atmosphere of the metal-rich planet-host star HD 77338 
  9. 9.0 9.1 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, doi:10.1088/0004-637X/766/2/67, Bibcode2013ApJ...766...67J 
  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, doi:10.3847/1538-3881/aa5df3, Bibcode2017AJ....153..136S 

Coordinates: Sky map 09h 01m 12.4938s, −25° 31′ 37.4333″