Astronomy:Beta Sextantis

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Short description: Star in the constellation Sextans
β Sextantis
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A light curve for Beta Sextantis, plotted from TESS data,[1]
Observation data
Equinox J2000.0]] (ICRS)
Constellation Sextans
Right ascension   10h 30m 17.48029s[2]
Declination −00° 38′ 13.3145″[2]
Apparent magnitude (V) 5.07[3]
Characteristics
Evolutionary stage Main sequence[4]
Spectral type B6 V[5] or B5 IV/V[6]
U−B color index −0.51[3]
B−V color index −0.14[3]
Variable type α2 CVn[7]
Astrometry
Radial velocity (Rv)11.6±2.8[8] km/s
Proper motion (μ) RA: −39.290[2] mas/yr
Dec.: −23.582[2] mas/yr
Parallax (π)8.8899 ± 0.1477[2] mas
Distance367 ± 6 ly
(112 ± 2 pc)
Absolute magnitude (MV)−0.38[9]
Details
Mass4.01±0.07[4] M☉
Radius3.00[10] R☉
Luminosity330[4] L☉
Surface gravity (log g)4.21[11] cgs
Temperature13,870[4] K
Metallicity [Fe/H]0.19[11] dex
Rotational velocity (v sin i)85±4[11] km/s
Age216[12] Myr
Other designations
β Sex, 30 Sextantis, BD+00°2663, FK5 2841, HD 90994, HIP 51437, HR 4119, SAO 137608[13]
Database references
SIMBADdata

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 8.89 mas,[2] is around 367 light years.

This star served as a primary standard in the MK spectral classification system with a stellar classification of B6 V,[5] 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.[6] Stellar evolution models support this is a main sequence star.[4] It has served as a uvby photometric standard, but is also categorized as an Alpha2 Canum Venaticorum variable[7] 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][5]

References

  1. ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  3. ↑ 3.0 3.1 3.2 3.3 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. doi:10.1086/111220. Bibcode: 1971AJ.....76.1058C. 
  4. ↑ 4.0 4.1 4.2 4.3 4.4 Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy and Astrophysics 537: A120. doi:10.1051/0004-6361/201117691. Bibcode: 2012A&A...537A.120Z. 
  5. ↑ 5.0 5.1 5.2 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. 
  6. ↑ 6.0 6.1 Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey (Ann Arbor, Michigan: Department of Astronomy, University of Michigan) 5. Bibcode: 1999MSS...C05....0H. 
  7. ↑ 7.0 7.1 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. 
  8. ↑ 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. 
  9. ↑ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A  XHIP record for this object at VizieR.
  10. ↑ McDonald, I.; Zijlstra, A. A.; Watson, R. A. (2017-10-01). "Fundamental parameters and infrared excesses of Tycho-Gaia stars". Monthly Notices of the Royal Astronomical Society 471: 770–791. doi:10.1093/mnras/stx1433. ISSN 0035-8711. Bibcode: 2017MNRAS.471..770M. 
  11. ↑ 11.0 11.1 11.2 11.3 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. doi:10.1051/0004-6361:20030889. Bibcode: 2003A&A...408.1065H. 
  12. ↑ Gontcharov, G. A. (2012). "Dependence of kinematics on the age of stars in the solar neighborhood". Astronomy Letters 38 (12): 771. doi:10.1134/S1063773712120031. Bibcode: 2012AstL...38..771G. 
  13. ↑ "bet Sex". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=bet+Sex. 

Coordinates: Sky map 10h 30m 17.48s, −00° 38′ 13.3″



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