7 Ceti

7 Ceti is a single,[9] variable star in the equatorial constellation of Cetus. It has the variable star designation AE Ceti.[10] The star is visible to the naked eye with a baseline apparent visual magnitude of 4.44.[2] Based upon an annual parallax shift of only 7.3 mas,[1] it is located roughly 450 light years away. It is moving closer to the Sun with a heliocentric radial velocity of −23 km/s.[5] Eggen (1965) listed it as a probable member of the Wolf 630 group of co-moving stars.[11]

7 Ceti
Observation data
Epoch J2000      Equinox J2000
Constellation Cetus
Right ascension  00h 14m 38.41655s[1]
Declination −18° 55′ 58.3145″[1]
Apparent magnitude (V) 4.44[2] (4.26–4.46)[3]
Characteristics
Spectral type M1 III[4]
B−V color index 1.640±0.044[2]
Variable type LB:[3]
Astrometry
Radial velocity (Rv)−22.9±1.0[5] km/s
Proper motion (μ) RA: −26.15[1] mas/yr
Dec.: −73.58[1] mas/yr
Parallax (π)7.29 ± 0.28[1] mas
Distance450 ± 20 ly
(137 ± 5 pc)
Absolute magnitude (MV)–1.24[2]
Details
Radius54[6] R☉
Luminosity1019.14[7] L☉
Temperature3,800[7] K
Other designations
3 Cet, AE Ceti, BD−19°21, HD 1038, HIP 1170, HR 48, SAO 147169[8]
Database references
SIMBADdata

This is an aging red giant star with a stellar classification of M1 III,[4] currently on the asymptotic giant branch.[12] Samus et al. (2017) has it classed as a slow irregular variable of type LB:, and ranges in magnitude from 4.26 down to 4.46.[3] Tabur et al. (2009) list it as a semiregular variable with four known periods ranging in frequency from 19.2 to 41.7 days.[10] The stellar atmosphere of 7 Ceti has expanded to an estimated 54[6] times the Sun's radius. It is radiating around 1,019[7] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,800 K.[7]

Luminosity variation[10]
Period
(Days)		 Amplitude
(Mag.)
19.20.018
19.60.020
27.10.018
41.70.017

References
  1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. 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.
  3. Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S.
  4. 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, Bibcode:1988mcts.book.....H.
  5. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  6. Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (Third ed.), 367 (2): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451.
  7. McDonald, I.; et al. (2012), "Fundamental parameters and infrared excesses of Hipparcos stars", Monthly Notices of the Royal Astronomical Society, 427: 343, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x.
  8. "7 Cet". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved December 26, 2018.
  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.
  10. Tabur, V.; et al. (December 2009), "Long-term photometry and periods for 261 nearby pulsating M giants", Monthly Notices of the Royal Astronomical Society, 400 (4): 1945–1961, arXiv:0908.3228, Bibcode:2009MNRAS.400.1945T, doi:10.1111/j.1365-2966.2009.15588.x.
  11. Eggen, O. J. (October 1965), "The Wolf 630 group", The Observatory, 85: 191–195, Bibcode:1965Obs....85..191E,
  12. Eggen, O. J. (1992), "Asymptotic giant branch stars near the sun", The Astronomical Journal, 104: 275, Bibcode:1992AJ....104..275E, doi:10.1086/116239.
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