Astronomy:25 Sextantis

From HandWiki
Short description: Alpha2 Canum Venactiorum variable
25 Sextantis
Location of 25 Sex on the map (circled)
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Sextans
Right ascension  10h 23m 26.47823s[1]
Declination −04° 04′ 26.5182″[1]
Apparent magnitude (V) 5.97[2] (5.94 - 5.98)[3]
Characteristics
Evolutionary stage main sequence star[4]
Spectral type B9p Si(CrSr)[5]
U−B color index −0.17[2]
B−V color index −0.10[2]
Variable type α2 CVn[3]
Astrometry
Radial velocity (Rv)23.0±3.4[6] km/s
Proper motion (μ) RA: −50.818[1] mas/yr
Dec.: +4.114[1] mas/yr
Parallax (π)9.4414 ± 0.0598[1] mas
Distance345 ± 2 ly
(105.9 ± 0.7 pc)
Absolute magnitude (MV)+0.86[7]
Details
Mass2.48±0.07[4] M☉
Radius2.22±0.11[8] R☉
Luminosity45.7+13.2−10.2[9] L☉
Surface gravity (log g)4.14[10] cgs
Temperature11,500[11] K
Metallicity [Fe/H]−0.19[10] dex
Rotational velocity (v sin i)24±3[9] km/s
Age309+54−80[4] Myr
Other designations
25 Sex, SS Sextantis, BD−03°2911, FK5 388, GC 14268, HD 90044, HIP 50885, HR 4082, SAO 137533[12]
Database references
SIMBADdata

25 Sextantis (HD 90044; HR 4082; 43 G. Sextantis), or simply 25 Sex, is a star located in the equatorial constellation Sextans; it also bears the variable star designation SS Sextantis (SS Sex). With an average apparent magnitude of 5.97,[2] 25 Sex is barely visible to the naked eye, even under ideal conditions. Gaia DR3 parallax measurements imply a distance of 345 light-years,[1] and it is currently drifting away with a heliocentric radial velocity of approximately 23 km/s.[6] At its current distance, 25 Sex's average brightness is diminished by an interstellar extinction of 0.17 magnitudes and it has an absolute magnitude of +0.86.[7]

A light curve for SS Sextantis, plotted from TESS data.[13] The 4.37 day rotation period is shown in red.

The star was first discovered to be variable in 1980 by French astronomers P. Renson & J. Manfroid. They observed a 4.37 day period for 25 Sex and a flucation of 0.03 magnitudes in optical light.[14] The next year, it was confirmed to be variable and it was given the variable star designation SS Sextantis.[15] J. Manfroid and G. Mathys refined the period of 25 Sextantis to be slightly longer than previously measured; the period of SS Sextantis was measured at 4.39 days but with a larger uncertainty.[16] In 1993, D. A. Bohlender and colleagues measured the magnetic field of the star and found that it varied between 650 and 1,200 gauss, although with some uncertainty about the variation.[17] Subsequent observations provide a much wider range between 1 and -1,000 gauss.[18]

25 Sex has a stellar classification of B9pSi(CrSr),[5] indicating that it is a Bp star with abundance of silicon, chromium, and strontium in its spectrum. It has 2.48 times the mass of the Sun[4] and 2.22 times the radius of the Sun.[8] It radiates 45.7 times the luminosity of the Sun[9] from its photosphere at an effective temperature of roughly 11,500 K,[11] giving it a bluish-white hue when viewed in the night sky. 25 Sex is metal deficient with an iron abundance 64.6% of the Sun's[10] and it is estimated to be 309 million years old.[4] At that age, it has completed 56% of its main sequence lifetime.[4] Like many chemically peculiar stars it spins modestly—having a projected rotational velocity of 24 km/s.[9]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 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.
  2. ↑ 2.0 2.1 2.2 2.3 Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system.". VizieR Online Data Catalog 2237. Bibcode: 2002yCat.2237....0D. 
  3. ↑ 3.0 3.1 Samus', N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (January 2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports 61 (1): 80–88. doi:10.1134/S1063772917010085. ISSN 1063-7729. Bibcode: 2017ARep...61...80S. 
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 Kochukhov, O.; Bagnulo, S. (10 April 2006). "Evolutionary state of magnetic chemically peculiar stars". Astronomy and Astrophysics 450 (2): 763–775. doi:10.1051/0004-6361:20054596. ISSN 0004-6361. Bibcode: 2006A&A...450..763K. 
  5. ↑ 5.0 5.1 Cowley, A.; Cowley, C.; Jaschek, M.; Jaschek, C. (April 1969). "A study of the bright stars. I. A catalogue of spectral classifications.". The Astronomical Journal 74: 375. doi:10.1086/110819. ISSN 0004-6256. Bibcode: 1969AJ.....74..375C. 
  6. ↑ 6.0 6.1 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. ISSN 1063-7737. Bibcode: 2006AstL...32..759G. 
  7. ↑ 7.0 7.1 Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331–346. doi:10.1134/S1063773712050015. ISSN 1063-7737. Bibcode: 2012AstL...38..331A. 
  8. ↑ 8.0 8.1 Kervella, P.; Thévenin, F.; Di Folco, E.; Ségransan, D. (April 8, 2004). "The angular sizes of dwarf stars and subgiants: Surface brightness relations calibrated by interferometry". Astronomy & Astrophysics 426 (1): 297–307. doi:10.1051/0004-6361:20035930. ISSN 0004-6361. Bibcode: 2004A&A...426..297K. 
  9. ↑ 9.0 9.1 9.2 9.3 Netopil, Martin; Paunzen, Ernst; Hümmerich, Stefan; Bernhard, Klaus (17 March 2017). "An investigation of the rotational properties of magnetic chemically peculiar stars". Monthly Notices of the Royal Astronomical Society 468 (3): 2745–2756. doi:10.1093/mnras/stx674. ISSN 0035-8711. Bibcode: 2017MNRAS.468.2745N. 
  10. ↑ 10.0 10.1 10.2 Anders, F. et al. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics 628: A94. doi:10.1051/0004-6361/201935765. ISSN 0004-6361. Bibcode: 2019A&A...628A..94A. 
  11. ↑ 11.0 11.1 Floquet, M. (August 1981). "Effective temperature of AP stars.". Astronomy and Astrophysics 101: 176–183. ISSN 0004-6361. Bibcode: 1981A&A...101..176F. 
  12. ↑ "25 Sextantis". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=25+Sextantis. 
  13. ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html. 
  14. ↑ Manfroid, J.; Renson, P. (July 1980). "Nouvelle Recherche de Periodes D'etoiles Ap Observees a l'ESO-V". Information Bulletin on Variable Stars 1824: 1. ISSN 0374-0676. Bibcode: 1980IBVS.1824....1M. 
  15. ↑ Kholopov, P. N.; Samus', N. N.; Kukarkina, N. P.; Medvedeva, G. I.; Perova, N. B. (November 1981). "66th Name-List of Variable Stars". Information Bulletin on Variable Stars 2042: 1. ISSN 0374-0676. Bibcode: 1981IBVS.2042....1K. 
  16. ↑ Manfroid, J.; Mathys, G. (March 1985). "New period determinations for variable CP stars.". Astronomy and Astrophysics Supplement Series 59: 429–432. ISSN 0365-0138. Bibcode: 1985A&AS...59..429M. 
  17. ↑ Bohlender, D. A.; Landstreet, J. D.; Thompson, Ian B. (March 1993). "A study of magnetic fields in AP SI and He weak stars.". Astronomy and Astrophysics 269: 355–376. ISSN 0004-6361. Bibcode: 1993A&A...269..355B. 
  18. ↑ Leone, F.; Catanzaro, G. (2001). "Spectropolarimetric measurements of the mean longitudinal magnetic field of chemically peculiar stars: II. Phase relating the magnetic and luminosity variabilities". Astronomy & Astrophysics 365 (2): 118–127. doi:10.1051/0004-6361:20000450. ISSN 0004-6361. Bibcode: 2001A&A...365..118L. 
Cite error: <ref> tag with name "Gould1879" defined in <references> is not used in prior text.



Retrieved from "https://handwiki.org/wiki/index.php?title=Astronomy:25_Sextantis&oldid=3926154"