Alpha Sextantis

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α Sextantis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Sextans
Right ascension 10h 07m 56.29556s[1]
Declination −0° 22′ 17.8621″[1]
Apparent magnitude (V) 4.49[2]
Characteristics
Spectral type A0 III[3]
U−B color index −0.07[2]
B−V color index −0.04[2]
Astrometry
Radial velocity (Rv) 10.00[4] km/s
Proper motion (μ) RA: −25.83[1] mas/yr
Dec.: −4.25[1] mas/yr
Parallax (π) 11.51 ± 0.98[1] mas
Distance 280 ± 20 ly
(87 ± 7 pc)
Details
Mass 2.96±0.12[5] M
Radius 4.5[6] R
Luminosity 120[7] L
Surface gravity (log g) 3.55[8] cgs
Temperature 9,984[7] K
Metallicity [Fe/H] −0.03±0.18[8] dex
Rotational velocity (v sin i) 21[9] km/s
Age 295[10] Myr
Other designations
α Sex, 15 Sextantis, BD+00° 2615, FK5 2814, HD 87887, HIP 49641, HR 3981, SAO 137366.[11]
Database references
SIMBAD data

Alpha Sextantis (α Sex, α Sextantis) is the brightest star in the equatorial constellation of Sextans.[12] It is visible to the naked eye on a dark night with an apparent visual magnitude of 4.49.[2] The distance to this star, as determined from parallax measurements,[1] is around 280 light years. This is considered an informal "equator star", as it lies less than a quarter of a degree south of the celestial equator. In 1900, it was 7 minutes of arc north of the equator. As a result of a shift in the Earth's axial tilt, it crossed over to the Southern Hemisphere in December 1923.[13]

This is an evolved A-type giant star with a stellar classification of A0 III.[3] It has around three[5] times the mass of the Sun and 4.5[6] times the Sun's radius. The abundance of elements is similar to that in the Sun.[8] It radiates 120 times the solar luminosity from its outer atmosphere at an effective temperature of 9,984 K.[7] Alpha Sextantis is around 295[10] million years old with a projected rotational velocity of 21 km/s.[9]

References[edit]

  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Mermilliod, J.-C. (1986), Compilation of Eggen's UBV data, transformed to UBV (unpublished), SIMBAD, Bibcode:1986EgUBV........0M. 
  3. ^ a b Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819. 
  4. ^ Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35,495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. 
  5. ^ a b Gerbaldi, M.; et al. (June 1999), "Search for reference A0 dwarf stars: Masses and luminosities revisited with HIPPARCOS parallaxes", Astronomy and Astrophysics Supplement, 137: 273−292, Bibcode:1999A&AS..137..273G, doi:10.1051/aas:1999248. 
  6. ^ a b Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics", Astronomy and Astrophysics, 367: 521–524, arXiv:astro-ph/0012289Freely accessible, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451. 
  7. ^ a b c 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:1208.2037Freely accessible, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x. 
  8. ^ a b c Pintado, O. I.; Adelman, S. J. (August 2003), "Elemental abundance analyses with the EBASIM spectrograph of the 2.1-m CASLEO Observatory Telescope. I. The late B and early A stars vec xi Octantis, alpha Sextantis, and 68 Tauri", Astronomy and Astrophysics, 406: 987−994, Bibcode:2003A&A...406..987P, doi:10.1051/0004-6361:20030813. 
  9. ^ a b 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/0205255Freely accessible, Bibcode:2002A&A...393..897R, doi:10.1051/0004-6361:20020943. 
  10. ^ a b Su, K. Y. L.; et al. (December 2006), "Debris Disk Evolution around A Stars", The Astrophysical Journal, 653 (1): 675−689, arXiv:astro-ph/0608563Freely accessible, Bibcode:2006ApJ...653..675S, doi:10.1086/508649. 
  11. ^ "alf Sex -- Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2016-12-12. 
  12. ^ "Sextans (abbr. Sex, gen. Sextantis)", The Internet Encyclopedia of Science, retrieved 2016-12-12. 
  13. ^ Kaler, James B., "Alpha Sextantis", Stars, University of Illinois, retrieved 2016-12-12. 

External links[edit]