Star in the constellation Cetus
75 Ceti is a single[ 9] star in the equatorial constellation of Cetus with at least two planets.[ 6] It is visible to the naked eye as a dim, orange-hued star with an apparent visual magnitude of +5.36.[ 2] The star is located 268 light-years (82 parsecs ) distant from the Sun, based on parallax , but is drifting closer with a radial velocity of −6 km/s.[ 1]
In Chinese , 天囷 (Tiān Qūn ), meaning Circular Celestial Granary , refers to an asterism consisting of α Ceti , κ1 Ceti , λ Ceti , μ Ceti , ξ1 Ceti , ξ2 Ceti , ν Ceti , γ Ceti , δ Ceti , 75 Ceti, 70 Ceti , 63 Ceti and 66 Ceti . Consequently, 75 Ceti itself is known as the Tenth Star of Circular Celestial Granary.[ 10]
This is an aging giant star with a stellar classification of K1 III,[ 3] having exhausted the supply of hydrogen at its core and expanded to 10.6[ 7] times the Sun's radius , or 0.05 AU . It is a red clump giant,[ 5] which indicates it is on the horizontal branch and is generating energy through helium fusion at the core. The star is 1.4[ 5] billion years old with 1.9[ 5] times the Sun's mass . It is radiating 56[ 7] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,846 K.[ 7]
Planetary system
A planetary companion was discovered by Doppler measurements at the Okayama Astrophysical Observatory , and announced in 2012. The planet's discoverers consider the planet, designated 75 Ceti b, to be "typical" of gas giants .[ 11] Note that (like many recorded planets) b takes in much more insolation than does Jupiter and, indeed, Earth.[ 12]
There may be additional periodic factors in the data, corresponding to m sin i of around 0.4 M J and 1 M J , at distances of ~0.9 AU and ~4 AU, where i is the orbital inclination and m is the planet's actual mass.[ 11] In 2023, the presence of a second, Jupiter-mass planet orbiting at 4 AU (75 Ceti c) was confirmed, which is more irradiated than Earth as well. The shorter period signal corresponding to a possible planet at 0.9 AU was found to be an alias of the true period of planet c.[ 6]
References
^ a b c d e f 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 .
^ a b c 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 Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey . 5 . Bibcode :1999MSS...C05....0H .
^ Liu, Y. J.; et al. (2007). "The abundances of nearby red clump giants" . Monthly Notices of the Royal Astronomical Society . 382 (2): 553–66. Bibcode :2007MNRAS.382..553L . doi :10.1111/j.1365-2966.2007.11852.x .
^ a b c d e f g Gallenne, A.; et al. (August 2018). "Fundamental properties of red-clump stars from long-baseline H-band interferometry". Astronomy & Astrophysics . 616 : 12. arXiv :1806.09572 . Bibcode :2018A&A...616A..68G . doi :10.1051/0004-6361/201833341 . S2CID 119331707 . A68.
^ a b c d Teng, Huan-Yu; Sato, Bun'ei; et al. (August 2023). "Revisiting Planetary Systems in Okayama Planet Search Program: A new long-period planet, RV astrometry joint analysis, and multiplicity-metallicity trend around evolved stars". Publications of the Astronomical Society of Japan . arXiv :2308.05343 . doi :10.1093/pasj/psad056 .
^ a b c d e Brown, A. G. A. ; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties" . Astronomy & Astrophysics . 616 . A1. arXiv :1804.09365 . Bibcode :2018A&A...616A...1G . doi :10.1051/0004-6361/201833051 . Gaia DR2 record for this source at VizieR .
^ "75 Cet" . SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2019-08-01 .
^ Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems" . Monthly Notices of the Royal Astronomical Society . 389 (2): 869–879. arXiv :0806.2878 . Bibcode :2008MNRAS.389..869E . doi :10.1111/j.1365-2966.2008.13596.x . S2CID 14878976 .
^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 11 日 Archived 2012-02-04 at the Wayback Machine
^ a b Sato, Bun'ei; et al. (2012). "Substellar Companions to Seven Evolved Intermediate-Mass Stars". Publications of the Astronomical Society of Japan . 64 (6). 135. arXiv :1207.3141 . Bibcode :2012PASJ...64..135S . doi :10.1093/pasj/64.6.135 . S2CID 119197073 .
^ Square root of luminosity means that an Earth like planet would have to be >7 AU from the star.