HD 24071

HD 24071 and HD 24072 form a binary[7] or possibly a triple star system in the equatorial constellation of Eridanus. It is visible to the naked eye, with component HD 24071 having an apparent visual magnitude of 5.25 and HD 24072 a magnitude of 4.72.[2] As of 2009, the pair had an angular separation of 8.40″ along a position angle of 216°.[8] The annual parallax shift of HD 24071 is 19.0 mas, which provides a distance estimate to the system of 172 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.[2]

HD 24071 and HD 24072

Observation data Epoch J2000      Equinox J2000
Constellation	Eridanus
Right ascension	03^h 48^m 35.47784^s[1]
Declination	−37° 37′ 19.2039″[1]
Apparent magnitude (V)	HD 24071: 5.246 ± 0.009 HD 24072: 4.721 ± 0.009[2]
Characteristics
HD 24071
Spectral type	A1 Va[3]
HD 24072
Spectral type	B9.5 Van[3]
Astrometry
Proper motion (μ)	RA: +63.251[1] mas/yr Dec.: −8.658[1] mas/yr
Parallax (π)	18.9981 ± 0.1200[1] mas
Distance	172 ± 1 ly (52.6 ± 0.3 pc)
Absolute magnitude (MV)	HD 24071: 1.719 ± 0.190 HD 24072: 1.194 ± 0.190[2]
Details
HD 24071
Rotational velocity (v sin i)	39[4] km/s
Age	45±4[2] Myr
HD 24072
Rotational velocity (v sin i)	225[4] km/s
Age	45±4[2] Myr
Other designations
f Eridani, CD−38 1297, HIP 17797, WDS J03486-3737
HD 24071: HR 1189, SAO 194550[5]
HD 24072: HR 1190, SAO 194551[6]
Database references
SIMBAD	data
	HD 24071
	HD 24072

HD 24071 is an A-type main-sequence star with a stellar classification of A1 Va.[3] It is a suspected variable star of unknown type showing an amplitude of 0.05 magnitude,[9] and is a source of X-ray emission, which may originate from a companion of class G2-5V.[10] The brighter component, HD 24072, is a B-type main-sequence star with a classification of B9.5 Van.[3] The n suffix indicates "nebulous" absorption lines due to rapid rotation. It has a projected rotational velocity of 225 km/s.[4]

References

1. 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.
2. 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.
3. 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.
4. 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.
5. "HD 24071". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-07-22.
6. "HD 24072". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-07-22.
7. 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.
8. Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode:2001AJ....122.3466M, doi:10.1086/323920
9. 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.
10. 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.