Astronomy:7 Ceti

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Short description: Star in the constellation Cetus
7 Ceti
Location of 7 Ceti (circled in red)
Observation data
Equinox J2000.0]] (ICRS)
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
Evolutionary stage AGB[4]
Spectral type M1 III[5]
B−V color index 1.640±0.044[2]
Variable type LB:[3]
Astrometry
Radial velocity (Rv)−22.9±1.0[6] 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
Radius69[7] R☉
Luminosity1,011[7] L☉
Surface gravity (log g)0.77[8] cgs
Temperature3,909[7] K
Metallicity [Fe/H]+0.50[8] dex
Other designations
3 Cet, AE Ceti, BD−19°21, HD 1038, HIP 1170, HR 48, SAO 147169[9]
Database references
SIMBADdata

7 Ceti is a single,[10] variable star in the equatorial constellation of Cetus. It has the variable star designation AE Ceti.[11] 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.[6] Eggen (1965) listed it as a probable member of the Wolf 630 group of co-moving stars.[12]

A light curve for AE Ceti, plotted from data presented by Tabur, et al. (2009)[11]

This is an aging red giant star with a stellar classification of M1 III,[5] currently on the asymptotic giant branch.[4] In 1959, Alan William James Cousins announced the detection of variability in the brightness of 7 Ceti.[13] It was given its variable star designation in 1973.[14] 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.[11] The stellar atmosphere of 7 Ceti has expanded to an estimated 69 times the Sun's radius.[7] It is radiating around 1,011 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,909 K.[7]

Luminosity variation[11]
Period
(Days) 		Amplitude
(Mag.)
19.2 0.018
19.6 0.020
27.1 0.018
41.7 0.017

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V. 
  2. ↑ 2.0 2.1 2.2 2.3 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A. 
  3. ↑ 3.0 3.1 3.2 Samus, N. N. et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1 61 (1): 80–88, doi:10.1134/S1063772917010085, Bibcode: 2017ARep...61...80S. 
  4. ↑ 4.0 4.1 Eggen, O. J. (1992), "Asymptotic giant branch stars near the sun", The Astronomical Journal 104: 275, doi:10.1086/116239, Bibcode: 1992AJ....104..275E. 
  5. ↑ 5.0 5.1 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, Bibcode: 1988mcts.book.....H. 
  6. ↑ 6.0 6.1 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, doi:10.1051/0004-6361/201219219, A61, Bibcode: 2012A&A...546A..61D. 
  7. ↑ 7.0 7.1 7.2 7.3 7.4 Fetherolf, Tara; Pepper, Joshua; Simpson, Emilie; Kane, Stephen R.; Močnik, Teo; English, John Edward; Antoci, Victoria; Huber, Daniel et al. (2023). "Variability Catalog of Stars Observed during the TESS Prime Mission". The Astrophysical Journal Supplement Series 268 (1): 4. doi:10.3847/1538-4365/acdee5. Bibcode: 2023ApJS..268....4F. 
  8. ↑ 8.0 8.1 Cardiel, Nicolás; Zamorano, Jaime; Bará, Salvador; Sánchez De Miguel, Alejandro; Cabello, Cristina; Gallego, Jesús; García, Lucía; González, Rafael et al. (2021). "Synthetic RGB photometry of bright stars: Definition of the standard photometric system and UCM library of spectrophotometric spectra". Monthly Notices of the Royal Astronomical Society 504 (3): 3730. doi:10.1093/mnras/stab997. Bibcode: 2021MNRAS.504.3730C. 
  9. ↑ "7 Cet". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=7+Cet. 
  10. ↑ 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, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E. 
  11. ↑ 11.0 11.1 11.2 11.3 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, doi:10.1111/j.1365-2966.2009.15588.x, Bibcode: 2009MNRAS.400.1945T. 
  12. ↑ Eggen, O. J. (October 1965), "The Wolf 630 group", The Observatory 85: 191–195, Bibcode: 1965Obs....85..191E, 
  13. ↑ Cousins, A. W. J. (1959). "Measures of Bright Southern Stars on UBV System". Monthly Notes of the Astronomical Society of South Africa 18: 46-47. Bibcode: 1959MNSSA..18...46C. 
  14. ↑ Kukarkin, B. V.; Kholopov, P. N.; Kukarkina, N. P.; Perova, N. B. (October 1973). "59th Name-List of Variable Stars". Information Bulletin on Variable Stars 834: 1-22. Bibcode: 1973IBVS..834....1K. https://ibvs.konkoly.hu/pub/ibvs/0801/0834.pdf. Retrieved 24 January 2025. 



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