Beta Sextantis

Beta Sextantis, Latinized from β Sextantis, is a variable star in the equatorial constellation of Sextans. With an apparent visual magnitude of 5.07,^[3] it is faintly visible to the naked eye on a dark night. According to the Bortle scale, it can be viewed from brighter lit suburban skies. The distance to this star, based upon an annual parallax shift of 8.96 mas,^[2] is around 364 light years.

β Sextantis

A light curve for Beta Sextantis, plotted from TESS data,[1]
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Sextans
Right ascension	10h 30m 17.48s[2]
Declination	−00° 38′ 13.30″[2]
Apparent magnitude (V)	5.07[3]
Characteristics
Spectral type	B6 V[4] or B5 IV/V[5]
U−B color index	−0.51[3]
B−V color index	−0.14[3]
Variable type	α2 CVn[6]
Astrometry
Radial velocity (Rv)	11.6±2.8[7] km/s
Proper motion (μ)	RA: −38.805[2] mas/yr Dec.: −24.290[2] mas/yr
Parallax (π)	8.9613 ± 0.2448 mas[2]
Distance	364 ± 10 ly (112 ± 3 pc)
Absolute magnitude (MV)	−0.38[8]
Details
Radius	3.2[9] R☉
Luminosity	184[10] L☉
Surface gravity (log g)	4.21[11] cgs
Temperature	14,570[11] K
Metallicity [Fe/H]	0.19[11] dex
Rotational velocity (v sin i)	85±4[11] km/s
Other designations
β Sex, 30 Sextantis, BD+00° 2663, FK5 2841, HD 90994, HIP 51437, HR 4119, SAO 137608.[12]
Database references
SIMBAD	data

This star served as a primary standard in the MK spectral classification system with a stellar classification of B6 V,^[4] indicating that it is a B-type main sequence star. However, Houk and Swift (1999) list a classification of B5 IV/V, suggesting it may be transitioning into a subgiant star.^[5] It has served as a uvby photometric standard, but is also categorized as an Alpha² Canum Venaticorum variable^[6] with a suspected period of 15.4 days. This lengthy a period conflicts with a relatively high projected rotational velocity of 85 km/s, leaving the explanation for the variance unresolved.^[11][4]

References

1. "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 27 August 2024.
2. 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. Gaia DR2 record for this source at VizieR.
3. Crawford, D. L.; et al. (1971), "Four-color, H-beta, and UBV photometry for bright B-type stars in the northern hemisphere", The Astronomical Journal, 76: 1058, Bibcode:1971AJ.....76.1058C, doi:10.1086/111220.
4. Mathys, G.; et al. (March 1986), "Photometric variability of some early-type stars", Astronomy and Astrophysics Supplement Series, 63 (3): 403–416, Bibcode:1986A&AS...63..403M.
5. Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars", Michigan Spectral Survey, 5, Ann Arbor, Michigan: Department of Astronomy, University of Michigan, Bibcode:1999MSS...C05....0H.
6. Kholopov, P. N.; et al. (April 1989), "The 69th Name-List of Variable Stars", Information Bulletin on Variable Stars, 3323 (3323): 1, Bibcode:1989IBVS.3323....1K.
7. 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.
8. 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, S2CID 119257644.
9. Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics, 367 (2) (3rd ed.): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
10. McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
11. Hempel, M.; Holweger, H. (September 2003), "Abundance analysis of late B stars. Evidence for diffusion and against weak stellar winds", Astronomy and Astrophysics, 408 (3): 1065–1076, Bibcode:2003A&A...408.1065H, doi:10.1051/0004-6361:20030889.
12. "bet Sex -- Variable Star of alpha2 CVn type", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2016-12-13.