f Eridani is a binary,[1] or possibly a triple, star system in the equatorial constellation of Eridanus, consisting of stars HD 24071 and HD 24072. They share a single Hipparcos catalogue entry, HIP 17797, but have separate Bright Star Catalogue listings, HR 1189 and 1190. f Eridani is the Bayer designation of the pair.

f Eridani is visible to the naked eye as a single star with a magnitude of 4.25.[2] HD 24071 has an apparent visual magnitude of 5.25 and HD 24072 a magnitude of 4.72.[3] As of 2009, the pair had an angular separation of 8.40 arcsecond along a position angle of 216°.[4] Both stars have an annual parallax shift 18.8 mas, which provides a distance estimate to the system of 173 light years. The pair are members of the Tucana-Horologium moving group, a 45 million year old set of stars that share a common motion through space.[3]

The brighter component, HD 24072, is a B-type main-sequence star with a classification of B9.5 Van.[5] The n suffix indicates "nebulous" absorption lines which are caused by its rapid rotation. It has a projected rotational velocity of 225 km/s.[6]

HD 24071 may itself be a spectroscopic binary. The visible component is an A-type main-sequence star with a stellar classification of A1 Va.[5] It is a suspected variable star of unknown type showing an amplitude of 0.05 magnitude,[7] and is a source of X-ray emission, which may originate from a companion of class G2-5V.[8]

References

  1. ^ Eggleton, P. P. & Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society. 389 (2): 869, arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976
  2. ^ Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers. 42 (2): 443. Bibcode:2014JAVSO..42..443M
  3. ^ Bell, Cameron P. M. et al. (November 2015), "A self-consistent, absolute isochronal age scale for young moving groups in the solar neighbourhood", Monthly Notices of the Royal Astronomical Society. 454 (1): 593–614, arXiv:1508.05955. Bibcode:2015MNRAS.454..593B. doi:10.1093/mnras/stv1981. S2CID 55297862
  4. ^ Mason, B. D. et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal. 122 (6): 3466, Bibcode:2001AJ....122.3466M. doi:10.1086/323920
  5. ^ Gray, R. O. & Garrison, R. F. (December 1987), "The Early A-Type Stars: Refined MK Classification, Confrontation with Stroemgren Photometry, and the Effects of Rotation", Astrophysical Journal Supplement. 65: 581, Bibcode:1987ApJS...65..581G. doi:10.1086/191237
  6. ^ Royer, F. et al. (October 2002), "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i", Astronomy and Astrophysics. 393: 897–911, arXiv:astro-ph/0205255. Bibcode:2002A&A...393..897R. doi:10.1051/0004-6361:20020943. S2CID 14070763
  7. ^ Adelman, S. J. et al. (November 2000), "On the Variability of A0-A2 Luminosity Class III-V Stars", Information Bulletin on Variable Stars. 4984: 1, Bibcode:2000IBVS.4984....1A
  8. ^ Schröder, C. & Schmitt, J. H. M. M. (November 2007), "X-ray emission from A-type stars", Astronomy and Astrophysics. 475 (2): 677–684, Bibcode:2007A&A...475..677S. doi:10.1051/0004-6361:20077429