81 Ceti

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81 Ceti
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Cetus
Right ascension 02h 37m 41.80208s [1]
Declination –03° 23′ 46.2259″ [1]
Apparent magnitude  (V)5.65 [2]
Characteristics
Evolutionary stage horizontal branch
Spectral type K0III [3] or G5III [4]
B−V color index 1.021±0.001 [2]
Variable type None
Astrometry
Radial velocity (Rv)+9.14±0.12 [1] km/s
Proper motion (μ)RA: 41.765 mas/yr [1]
Dec.: −43.379 mas/yr [1]
Parallax (π)9.5199±0.0756  mas [1]
Distance 343 ± 3  ly
(105.0 ± 0.8  pc)
Absolute magnitude  (MV)0.82 [2]
Details [5]
Mass 1.6±0.2  M☉
Radius 11.1±0.3  R☉
Luminosity 60.0±0.8  L☉
Surface gravity (log g)2.5±0.1  cgs
Temperature 4,825±41  K
Metallicity [Fe/H]0.00±0.04 [6]   dex
Rotational velocity (v sin i)1.20±0.47 [6]  km/s
Age 2.5±0.9  Gyr
Other designations
81 Cet, BD−04°436, GC 3158, HD 16400, HIP 12247, HR 771, SAO 130026
Database references
SIMBAD data
Exoplanet Archive data

81 Ceti is a star located approximately 343  light-years away from the Sun in the equatorial constellation of Cetus. 81 Ceti is the Flamsteed designation for this object. It is visible to the naked eye as a dim, yellow-hued point of light with an apparent visual magnitude of 5.65. [2] The star is drifting further away from the Earth with a heliocentric radial velocity of +9 km/s. [2]

Contents

This is an aging K-type giant star with a stellar classification of K0III, [3] having exhausted the supply of hydrogen at its core and expanded to 11 [5] times the Sun's radius. It is a red clump giant, [7] which indicates it is on the horizontal branch and is generating energy from core helium fusion. The star is now 2.5 billion years old with 1.6 times the mass of the Sun. [5] It is radiating 60 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,825 K. [5]

Planetary system

In July 2008, the planet 81 Ceti b was announced by Sato and collaborators, along with 14 Andromedae b and 6 Lyncis b. The planet was found to be a super-Jupiter, with 5.3 times the mass of Jupiter. It takes 953 days for it to complete its orbit around the star. [4] The planetary parameters were updated in 2023. [8]

The 81 Ceti planetary system [8]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥3.307+0.078
−0.067  MJ 		2.104±0.0031005.57+1.84
−1.94		0.037+0.015
−0.025		——

See also

References

  1. 1 2 3 4 5 6 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. 1 2 3 4 5 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.
  3. 1 2 Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey. 5. Bibcode:1999MSS...C05....0H.
  4. 1 2 Sato, Bun'ei; et al. (2008). "Planetary Companions to Evolved Intermediate-Mass Stars: 14 Andromedae, 81 Ceti, 6 Lyncis, and HD167042". Publications of the Astronomical Society of Japan. 60 (6): 1317–1326. arXiv: 0807.0268 . Bibcode:2008PASJ...60.1317S. doi:10.1093/pasj/60.6.1317. S2CID   67841762.
  5. 1 2 3 4 Bonfanti, A.; et al. (2015). "Revising the ages of planet-hosting stars". Astronomy and Astrophysics. 575. A18. arXiv: 1411.4302 . Bibcode:2015A&A...575A..18B. doi:10.1051/0004-6361/201424951. S2CID   54555839.
  6. 1 2 Jofré, E.; et al. (2015). "Stellar parameters and chemical abundances of 223 evolved stars with and without planets". Astronomy & Astrophysics. 574: A50. arXiv: 1410.6422 . Bibcode:2015A&A...574A..50J. doi:10.1051/0004-6361/201424474. S2CID   53666931.
  7. ↑ Mishenina, T. V.; et al. (September 2006), "Elemental abundances in the atmosphere of clump giants", Astronomy and Astrophysics, 456 (3): 1109–1120, arXiv: astro-ph/0605615 , Bibcode:2006A&A...456.1109M, doi:10.1051/0004-6361:20065141, S2CID   18764566
  8. 1 2 Teng, Huan-Yu; Sato, Bun'ei; et al. (August 2023). "Revisiting planetary systems in the Okayama Planet Search Program: A new long-period planet, RV astrometry joint analysis, and a multiplicity-metallicity trend around evolved stars". Publications of the Astronomical Society of Japan . 75 (6): 1030–1071. arXiv: 2308.05343 . Bibcode:2023PASJ...75.1030T. doi:10.1093/pasj/psad056.
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