Star in the constellation Perseus
21 Persei is a single,[ 10] variable star in the northern constellation of Perseus , located about 331 light years away from the Sun. It is visible to the naked eye as a faint, white-hued star with an apparent visual magnitude of 5.10 km/s.[ 2] The object is moving further from the Earth with a heliocentric radial velocity of +8.5 km/s.[ 6] It has the variable star designation LT Persei ; 21 Persei is the Flamsteed designation .
A light curve for LT Persei, plotted from Hipparcos data[ 11]
This is an Ap star with a stellar classification of A2VspSiEu,[ 3] where the A2V indicates it is an A-type main-sequence star , 's' means narrow "sharp" absorption , and SiEu shows abundance anomalies of the elements silicon and europium. The star is an Alpha2 Canum Venaticorum variable , meaning that the star has a strong magnetic field chromium , silicon , and strontium spectral lines. 21 Persei's period of variability is approximately 2.88 days.[ 12]
^ a b c d e Brown, A. G. A. ; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties" . Astronomy & Astrophysics . 616 . A1. arXiv :1804.09365 . Bibcode :2018A&A...616A...1G . doi :10.1051/0004-6361/201833051 . Gaia DR2 record for this source at VizieR .
^ a b c d Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters . 38 (5): 331. arXiv :1108.4971 . Bibcode :2012AstL...38..331A . doi :10.1134/S1063773712050015 . S2CID 119257644 . Vizier catalog entry
^ a b Abt, Helmut A.; Morrell, Nidia I. (1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars" . Astrophysical Journal Supplement . 99 : 135. Bibcode :1995ApJS...99..135A . doi :10.1086/192182 .
^ a b Mermilliod, J. C. (2006). "VizieR Online Data Catalog: Homogeneous Means in the UBV System (Mermilliod 1991)". VizieR On-line Data Catalog: II/168. Originally Published in: Institut d'Astronomie . 2168 . Bibcode :2006yCat.2168....0M . Vizier catalog entry
^ Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S . 1 . Bibcode :2009yCat....102025S .
^ a b Gontcharov, G. A. (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 . S2CID 119231169 .
^ a b c d David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal . 804 (2): 146. arXiv :1501.03154 . Bibcode :2015ApJ...804..146D . doi :10.1088/0004-637X/804/2/146 . S2CID 33401607 . Vizier catalog entry
^ Wu, Yue; Singh, H. P.; Prugniel, P.; Gupta, R.; Koleva, M. (2010). "Coudé-feed stellar spectral library – atmospheric parameters". Astronomy & Astrophysics . 525 : A71. arXiv :1009.1491 . Bibcode :2011A&A...525A..71W . doi :10.1051/0004-6361/201015014 . S2CID 53480665 .
^ "21 Per" . SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2019-03-29 .
^ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society , 389 (2): 869–879, arXiv :0806.2878 , Bibcode :2008MNRAS.389..869E , doi :10.1111/j.1365-2966.2008.13596.x , S2CID 14878976 . {{citation }}
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^ Catalano, F. A.; Renson, P.; Leone, F. (1993). "Third supplement to the catalogue of observed periods of Ap stars". Astronomy and Astrophysics Supplement Series . 98 (2): 269–273. Bibcode :1993A&AS...98..269C .