64 Eridani

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This article is about S Eridani. For s Eridani, see HD 16754.
64 Eridani

A light curve for S Eridani, adapted from Koen and Eyer (2002)[1]
Observation data
Epoch J2000      Equinox
Constellation Eridanus[2]
Right ascension 04h 59m 55.73680s[3]
Declination −12° 32′ 14.7004″[3]
Apparent magnitude (V) 4.77 – 4.79[4]
Characteristics
Evolutionary stage subgiant[5]
Spectral type F0 V[6]
B−V color index 0.266[7]
Variable type δ Sct[8][4]
Astrometry
Radial velocity (Rv)−8.9±4.2[9] km/s
Proper motion (μ) RA: +39.894[3] mas/yr
Dec.: −87.358[3] mas/yr
Parallax (π)11.5441±0.0851 mas[3]
Distance283 ± 2 ly
(86.6 ± 0.6 pc)
Absolute magnitude (MV)+0.03[2]
Details
Mass2.33[10] M☉
Radius5.22[11] R☉
Luminosity65[11] L☉
Surface gravity (log g)3.37[10] cgs
Temperature7,346±250[10] K
Rotational velocity (v sin i)212[12] km/s
Age756[10] Myr
Other designations
64 Eri, S Eri, BD−12°1047, HD 32045, HIP 23231, HR 1611, SAO 150064[13]
Database references
SIMBADdata

64 Eridani is a single,[14] yellow-white hued star in the constellation Eridanus having variable star designation S Eridani. It is faintly visible to the naked eye with an apparent visual magnitude of 4.8.[7] The annual parallax shift is measured at 12.01 mas, which equates to a distance of about 283 light years.[3] In addition to its proper motion, it is moving closer to the Sun with a radial velocity of around −9 km/s.[9]

This is an F-type star with a stellar classification of F0 V.[6] It is catalogued a low amplitude Delta Scuti variable with a primary period of 0.273 days.[8] It was originally classified, tentatively, as an RR Lyrae variable of type 'c'.[15]

64 Eridani is spinning rapidly with a projected rotational velocity of 212 km/s.[12] This is giving the star an oblate shape with an equatorial bulge; its equatorial radius is 8% larger than its polar radius.[16] The star is an estimated 756 million years old with 2.3 times the mass of the Sun.[10] It is radiating 65 times the Sun's luminosity[11] from its photosphere at an effective temperature of roughly 7,346 K.[10]

References

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  1. ^ Koen, Chris; Eyer, Laurent (March 2002). "New periodic variables from the Hipparcos epoch photometry". Monthly Notices of the Royal Astronomical Society. 331 (1): 45–59. arXiv:astro-ph/0112194. Bibcode:2002MNRAS.331...45K. doi:10.1046/j.1365-8711.2002.05150.x.
  2. ^ a b 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. XHIP record for this object at VizieR.
  3. ^ 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.
  4. ^ a b "S Eri". International Variable Star Index. AAVSO. Retrieved 2025-09-17.
  5. ^ Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy and Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691.
  6. ^ a b Houk, Nancy; Smith-Moore, M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.
  7. ^ a b Høg, E.; et al. (2000), "The Tycho-2 catalogue of the 2.5 million brightest stars", Astronomy and Astrophysics, 355: L27, Bibcode:2000A&A...355L..27H, doi:10.1888/0333750888/2862.
  8. ^ a b Rodríguez, E.; Breger, M. (January 2001), "delta Scuti and related stars: Analysis of the R00 Catalogue", Astronomy and Astrophysics, 366: 178–196, Bibcode:2001A&A...366..178R, doi:10.1051/0004-6361:20000205.
  9. ^ a b 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, S2CID 59451347, A61.
  10. ^ a b c d e f David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
  11. ^ a b c Fetherolf, Tara; Pepper, Joshua; Simpson, Emilie; Kane, Stephen R.; Močnik, Teo; English, John Edward; Antoci, Victoria; Huber, Daniel; Jenkins, Jon M.; Stassun, Keivan; Twicken, Joseph D.; Vanderspek, Roland; Winn, Joshua N. (2023). "Variability Catalog of Stars Observed during the TESS Prime Mission". The Astrophysical Journal Supplement Series. 268 (1): 4. arXiv:2208.11721. Bibcode:2023ApJS..268....4F. doi:10.3847/1538-4365/acdee5.
  12. ^ a b Royer, F.; et al. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224, S2CID 18475298.
  13. ^ "64 Eri". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-01-29.
  14. ^ 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.
  15. ^ Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869, retrieved 2019-08-06.
  16. ^ Belle, G. T. (2012). "Interferometric observations of rapidly rotating stars". The Astronomy and Astrophysics Review. 20 (1): 51. arXiv:1204.2572. Bibcode:2012A&ARv..20...51V. doi:10.1007/s00159-012-0051-2. S2CID 119273474.