Astronomy:Alpha Sextantis
  | |
| Observation data 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) |
| Absolute magnitude (MV) | −0.29±0.21[5] |
| Details | |
| Mass | 2.57±0.32[6] M☉ |
| Radius | 3.07[6] R☉ |
| Luminosity | 90[6] L☉ |
| Surface gravity (log g) | 3.55[7] cgs |
| Temperature | 9,984[8] K |
| Metallicity [Fe/H] | −0.03±0.18[7] dex |
| Rotational velocity (v sin i) | 21[9] km/s |
| Age | 385[6] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Alpha Sextantis (α Sex, α Sextantis) is the brightest star in the equatorial constellation of Sextans.[11] 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.[12]
The variability of Alpha Sextantis was discovered by Aven Magded Hamadamen and included in the International Variable Star Index.[13] The star undergoes pulsations with a period of 9.1 hours.[6]
This is an evolved A-type giant star with a stellar classification of A0 III.[3] It has around 2.5[6] times the mass of the Sun and three[6] times the Sun's radius. The abundance of elements is similar to that in the Sun.[7] It radiates 90 times the solar luminosity[6] from its outer atmosphere at an effective temperature of 9,984 K.[8] Alpha Sextantis is nearing the end of its life as a main-sequence star; it is around 385[6] million years old with a projected rotational velocity of 21 km/s.[9]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 2.2 2.3 Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data (SIMBAD), Bibcode: 1986EgUBV........0M.
- ↑ 3.0 3.1 Cowley, A. et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal 74: 375–406, doi:10.1086/110819, Bibcode: 1969AJ.....74..375C.
- ↑ 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. doi:10.1134/S1063773706110065. Bibcode: 2006AstL...32..759G.
- ↑ Gerbaldi, M. et al. (June 1999), "Search for reference A0 dwarf stars: Masses and luminosities revisited with HIPPARCOS parallaxes", Astronomy and Astrophysics Supplement 137 (2): 273–292, doi:10.1051/aas:1999248, Bibcode: 1999A&AS..137..273G.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 Monier, Richard; Bowman, Dominic M.; Lebreton, Yveline; Deal, Morgan (2023). "The Unexpected Optical and Ultraviolet Variability of the Standard Star α Sex (HD 87887)". The Astronomical Journal 166 (2): 73. doi:10.3847/1538-3881/acdee4. Bibcode: 2023AJ....166...73M.
- ↑ 7.0 7.1 7.2 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 (3): 987–994, doi:10.1051/0004-6361:20030813, Bibcode: 2003A&A...406..987P.
- ↑ 8.0 8.1 McDonald, I. et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society 427 (1): 343–57, doi:10.1111/j.1365-2966.2012.21873.x, Bibcode: 2012MNRAS.427..343M.
- ↑ 9.0 9.1 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, doi:10.1051/0004-6361:20020943, Bibcode: 2002A&A...393..897R.
- ↑ "alf Sex". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=alf+Sex.
- ↑ Sextans (abbr. Sex, gen. Sextantis), http://www.daviddarling.info/encyclopedia/S/Sex.html, retrieved 2016-12-12.
- ↑ Kaler, James B., "Alpha Sextantis", Stars (University of Illinois), http://stars.astro.illinois.edu/sow/alphasext.html, retrieved 2016-12-12.
- ↑ "VSX : Detail for alf Sex". https://www.aavso.org/vsx/index.php?view=detail.top&oid=2227107.
External links
 |  |
