75 Ceti

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75 Ceti
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Cetus
Right ascension 02h 32m 09.42241s [1]
Declination −01° 02′ 05.6166″ [1]
Apparent magnitude  (V)+5.36 [2]
Characteristics
Spectral type K1 III [3]
B−V color index +1.004±0.002 [2]
Astrometry
Radial velocity (Rv)−6.34±0.13 [1]  km/s
Proper motion (μ)RA: −23.268  mas/yr [1]
Dec.: −30.987  mas/yr [1]
Parallax (π)12.1717 ± 0.0962  mas [1]
Distance 268 ± 2  ly
(82.2 ± 0.6  pc)
Absolute magnitude  (MV)0.808 [4]
Details
Mass 1.85±0.05 [5]   M☉
Radius 10.38+0.15
−0.26 [6]   R☉
Luminosity 56.1±0.6 [7]   L☉
Surface gravity (log g)2.67±0.04 [5]   cgs
Temperature 4,846+163
−128 [7]   K
Metallicity [Fe/H]0.00±0.06 [5]   dex
Age 1.41±0.01 [5]   Gyr
Other designations
75 Cet, BD–01°353, GC  3043, HD  15779, HIP  11791, HR  739, SAO  129959 [8]
Database references
SIMBAD data
Exoplanet Archive data

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 MJ and 1 MJ, 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]

The 75 Ceti planetary system [6]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b≥2.479+0.074
−0.090  MJ 		1.912+0.002
−0.003		696.62+1.33
−1.69		0.093+0.026
−0.042		——
c≥0.912+0.088
−0.143  MJ 		3.929+0.058
−0.052		2051.62+45.98
−40.47		0.023+0.191
−0.003		——

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<span class="mw-page-title-main">Xi Aquilae</span> Red-clump giant star in the constellation Aquila

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<span class="mw-page-title-main">Eta Ceti</span> Star in the constellation Cetus

Eta Ceti is a star in the equatorial constellation of Cetus. It has the traditional name Deneb Algenubi or Algenudi. The apparent visual magnitude of this star is +3.4, making it the fourth-brightest star in this otherwise relatively faint constellation. The distance to this star can be measured directly using the parallax technique, yielding a value of 120.5 light-years.

HD 210702 is a star with an orbiting exoplanet in the northern constellation of Pegasus. It has an apparent visual magnitude of 5.93, which is bright enough that the star is dimly visible to the naked eye. The distance to HD 210702 is 177 light years based on parallax measurements, and it is drifting further away with a radial velocity of 18.5 km/s. It is a probable member of the Ursa Major moving group, an association of co-moving stars.

<span class="mw-page-title-main">Gamma Piscium</span> G-type giant star in the constellation Pisces

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<span class="mw-page-title-main">14 Andromedae b</span> Extrasolar planet in Andromeda constellation

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<span class="mw-page-title-main">Chi Piscium</span> Yellow-hued giant star in the constellation Pisces

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HD 5608 is an orange-hued star in the northern constellation of Andromeda with one known planet, HD 5608 b. It is a dim star near the lower limit of visibility to the naked eye, having an apparent visual magnitude of +5.98. The distance to HD 5608, as estimated from an annual parallax shift of 17.07 mas, is 191 light-years. It is moving closer to the Earth with a heliocentric radial velocity of −23 km/s, and is expected to make its closest approach in 1.285 million years when it comes to within 124 light-years.

HD 100655 is a star in the zodiac constellation of Leo, located 449 light years away from the Sun. It has an apparent visual magnitude of +6.45, which makes it a challenge to see with the naked eye under ideal viewing conditions. The star is moving closer to the Earth with a heliocentric radial velocity of −5 km/s. It has one confirmed planet.

HD 180314 is a star with an orbiting substellar companion in the northern constellation of Lyra. It is near the lower limit of visibility to the naked eye with an apparent visual magnitude of 6.61. The distance to this system is 401 light years based on parallax measurements, but it is drifting closer with a heliocentric radial velocity of −73.9 km/s. With high probability it is a member of the Hercules stream of co-moving stars.

HD 120084 is a star with an orbiting exoplanet in the northern constellation of Ursa Minor. With an apparent magnitude of 5.91, it is just visible to the naked eye in suburban skies. The distance to this system is 339 light years based on parallax measurements, but it is drifting closer to the Sun with a radial velocity of −9 km/s.

HD 145457 is a star located in the northern constellation of Corona Borealis at a distance of around 442 light-years from the Sun, as determined through parallax measurements. It has been formally named Kamuy by the IAU, after a spiritual or divine being in Ainu mythology. With an apparent magnitude of 6.57, it is barely visible to the unaided eye on dark nights clear of light pollution. It is drifting closer to the Sun with a radial velocity of −3.2 km/s.

References

  1. 1 2 3 4 5 6 7 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 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. ↑ 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 .
  5. 1 2 3 4 5 6 7 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.
  6. 1 2 3 4 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.
  7. 1 2 3 4 5 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.
  8. ↑ "75 Cet". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2019-08-01.
  9. ↑ 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.
  10. ↑ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 11 日
  11. 1 2 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.
  12. ↑ Square root of luminosity means that an Earth like planet would have to be >7 AU from the star.
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