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25 Sextantis

From Wikipedia, the free encyclopedia
Alpha2 Canum Venactiorum variable.
25 Sextantis
Location of 25 Sex on the map (circled)
Observation data
EpochJ2000.0      EquinoxJ2000.0 (ICRS)
ConstellationSextans
Right ascension10h 23m 26.47823s[1]
Declination−04° 04′ 26.5182″[1]
Apparent magnitude (V)5.97[2] (5.94 - 5.98)[3]
Characteristics
Evolutionary stagemain sequence star[4]
Spectral typeB9p Si(CrSr)[5]
U−Bcolor index−0.17[2]
B−Vcolor index−0.10[2]
Variable typeα2 CVn[3]
Astrometry
Radial velocity (Rv)23.0±3.4[6] km/s
Proper motion (μ)RA: −50.818mas/yr[1]
Dec.: +4.114mas/yr[1]
Parallax (π)9.4414±0.0598 mas[1]
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,43 G. Sextantis[12],SS Sextantis,BD−03°2911,FK5 388,GC 14268,HD 90044,HIP 50885,HR 4082,SAO 137533,TIC 1712781[13]
Database references
SIMBADdata

25 Sextantis (HD 90044; HR 4082; 43 G. Sextantis), or simply25 Sex, is astar located in theequatorialconstellationSextans; it also bears thevariable star designationSS Sextantis (SS Sex). With an averageapparent magnitude of 5.97,[2] 25 Sex is barely visible to thenaked eye, even under ideal conditions.Gaia DR3parallax measurements imply a distance of 345light-years,[1] and it is currently drifting away with a heliocentricradial velocity of approximately23 km/s.[6] At its current distance, 25 Sex's average brightness is diminished by aninterstellar extinction of 0.17magnitudes and it has anabsolute magnitude of +0.86.[7]

Alight curve for SS Sextantis, plotted fromTESS data.[14] The 4.37 day rotation period is shown in red.

The star was first discovered to be variable in 1980 byFrenchastronomers P. Renson & J. Manfroid. They observed a 4.37day period for 25 Sex and a flucation of 0.03 magnitudes inoptical light.[15] The next year, it was confirmed to be variable and it was given the variable star designation SS Sextantis.[16] 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.[17] In 1993, D. A. Bohlender and colleagues measured themagnetic field of the star and found that it varied between 650 and 1,200gauss, although with some uncertainty about the variation.[18] Subsequent observations provide a much wider range between 1 and -1,000 gauss.[19]

25 Sex has astellar classification of B9pSi(CrSr),[5] indicating that it is aBp star with abundance ofsilicon,chromium, andstrontium in its spectrum. It has 2.48 times themass of the Sun[4] and 2.22 times theradius of the Sun.[8] It radiates 45.7 times theluminosity of the Sun[9] from itsphotosphere at aneffective temperature of roughly11,500 K,[11] giving it a bluish-white hue when viewed in thenight sky. 25 Sex is metal deficient with aniron abundance 64.6% of theSun's[10] and it is estimated to be 309million years old.[4] At that age, it has completed 56% of itsmain sequence lifetime.[4] Like manychemically peculiar stars it spins modestly—having aprojected rotational velocity of24 km/s.[9]

References

[edit]
  1. ^abcdeVallenari, A.; et al. (Gaia collaboration) (2023)."Gaia Data Release 3. Summary of the content and survey properties".Astronomy and Astrophysics.674: A1.arXiv:2208.00211.Bibcode:2023A&A...674A...1G.doi:10.1051/0004-6361/202243940.S2CID 244398875. Gaia DR3 record for this source atVizieR.
  2. ^abcdDucati, 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. ^abSamus', 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.Bibcode:2017ARep...61...80S.doi:10.1134/S1063772917010085.eISSN 1562-6881.ISSN 1063-7729.S2CID 125853869.
  4. ^abcdefKochukhov, O.; Bagnulo, S. (10 April 2006)."Evolutionary state of magnetic chemically peculiar stars".Astronomy and Astrophysics.450 (2):763–775.arXiv:astro-ph/0601461.Bibcode:2006A&A...450..763K.doi:10.1051/0004-6361:20054596.eISSN 1432-0746.ISSN 0004-6361.S2CID 18596834.
  5. ^abCowley, 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.Bibcode:1969AJ.....74..375C.doi:10.1086/110819.ISSN 0004-6256.S2CID 121555804.
  6. ^abGontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35,495 Hipparcos stars in a common system".Astronomy Letters.32 (11):759–771.arXiv:1606.08053.Bibcode:2006AstL...32..759G.doi:10.1134/S1063773706110065.eISSN 1562-6873.ISSN 1063-7737.S2CID 119231169.
  7. ^abAnderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation".Astronomy Letters.38 (5):331–346.arXiv:1108.4971.Bibcode:2012AstL...38..331A.doi:10.1134/S1063773712050015.eISSN 1562-6873.ISSN 1063-7737.S2CID 119257644.
  8. ^abKervella, 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.arXiv:astro-ph/0404180.Bibcode:2004A&A...426..297K.doi:10.1051/0004-6361:20035930.eISSN 1432-0746.ISSN 0004-6361.S2CID 6077801.
  9. ^abcdNetopil, 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.arXiv:1703.05218.Bibcode:2017MNRAS.468.2745N.doi:10.1093/mnras/stx674.eISSN 1365-2966.ISSN 0035-8711.S2CID 119215348.
  10. ^abcAnders, F.; et al. (August 2019)."Photo-astrometric distances, extinctions, and astrophysical parameters forGaia DR2 stars brighter thanG = 18".Astronomy & Astrophysics.628: A94.arXiv:1904.11302.Bibcode:2019A&A...628A..94A.doi:10.1051/0004-6361/201935765.eISSN 1432-0746.ISSN 0004-6361.S2CID 131780028.
  11. ^abFloquet, M. (August 1981). "Effective temperature of AP stars".Astronomy and Astrophysics.101:176–183.Bibcode:1981A&A...101..176F.ISSN 0004-6361.
  12. ^Gould, Benjamin Apthorp (1878). "Uranometria Argentina : brillantez y posicion de las estrellas fijas, hasta la septima magnitud, comprendidas dentro de cien grados del polo austral : con atlas".Resultados del Observatorio Nacional Argentino.1.Bibcode:1879RNAO....1.....G.
  13. ^"25 Sextantis".SIMBAD.Centre de données astronomiques de Strasbourg. RetrievedFebruary 2, 2024.
  14. ^"MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved4 July 2024.
  15. ^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.Bibcode:1980IBVS.1824....1M.ISSN 0374-0676.
  16. ^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.Bibcode:1981IBVS.2042....1K.ISSN 0374-0676.
  17. ^Manfroid, J.; Mathys, G. (March 1985). "New period determinations for variable CP stars".Astronomy and Astrophysics Supplement Series.59:429–432.Bibcode:1985A&AS...59..429M.ISSN 0365-0138.
  18. ^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.Bibcode:1993A&A...269..355B.ISSN 0004-6361.
  19. ^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.Bibcode:2001A&A...365..118L.doi:10.1051/0004-6361:20000450.ISSN 0004-6361.
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