Variable star in the constellation Andromeda
GY Andromedae (GY And) is anα2 Canum Venaticorum type binary variable star in the northernconstellation Andromeda . Its brightness fluctuates invisual magnitude between 6.27m and 6.41m , making it a challenge to view with the naked eye even ingood seeing conditions . Themagnetic activity on this star shows an unusually long period of variability, cycling about once every 23 years.[ 10] parallax measurements, this star is located at a distance of about 460light-years (140parsecs ) from theEarth .[ 2]
This isclassified as anAp/Bp star , with apeculiar spectrum [ 10] lines ofchromium andeuropium that change in intensity over a period matching the variability cycle, although opposite inphase .[ 11] promethium in itsemission spectrum . All isotopes of this element areradioactive withhalf lives of 17.7 years or less. The promethium in the outer envelope may be generated by the spontaneousfission of higher masstransuranic elements .[ 12]
Based onradial velocity measurements taken at theDominion Astrophysical Observatory between 1927 and 1935 Canadian astronomerWilliam Edmund Harper strongly suspected that this star was aspectroscopic binary .[ 13] Horace W. Babcock confirmed the binary nature of the star.[ 14] eccentricity of 0.47. The two components are separated by an estimated distance of at least3.74 × 107 km , or 0.25Astronomical Units .[ 9]
^ Metlova, N. V.; Bychkov, V. D.; Bychkova, L. V.; Madej, J. (23 August 2014)."Photometric and Magnetic Variability of the Ap Star GY And" Astrophysical Bulletin .69 (3):315– 320.Bibcode :2014AstBu..69..315M .doi :10.1134/S1990341314030067 . Retrieved25 August 2024 . ^a b c d e f Brown, A. G. A. ; et al. (Gaia collaboration) (2021)."Gaia Early Data Release 3: Summary of the contents and survey properties" .Astronomy & Astrophysics 649 : A1.arXiv :2012.01533 Bibcode :2021A&A...649A...1G .doi :10.1051/0004-6361/202039657 S2CID 227254300 . (Erratum: doi :10.1051/0004-6361/202039657e ) . Gaia EDR3 record for this source atVizieR .^a b c Nicolet, B. (1978). "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System".Astronomy and Astrophysics Supplement Series .34 :1– 49.Bibcode :1978A&AS...34....1N . ^a b "V* GY And -- Variable Star of alpha2 CVn type" ,SIMBAD ,Centre de Données astronomiques de Strasbourg , retrieved2012-01-01 ^ Wilson, R. E. (1953), "General Catalogue of Stellar Radial Velocities",Carnegie Institute Washington D.C. Publication , Carnegie Institute of Washington, D.C.,Bibcode :1953GCRV..C......0W ^a b c d e North, P. (June 1998), "Do SI stars undergo any rotational braking?",Astronomy and Astrophysics ,334 :181– 187,arXiv :astro-ph/9802286 Bibcode :1998A&A...334..181N ^a b Aller, M. F. (July 1972), "A model atmosphere analysis of the Ap star HR 465",Astronomy and Astrophysics ,19 :248– 260,Bibcode :1972A&A....19..248A ^ 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/0205255 Bibcode :2002A&A...393..897R ,doi :10.1051/0004-6361:20020943 ,S2CID 14070763 ^a b Scholz, G. (1978), "Spectroscopic investigations of the magnetic AP star HD 9996",Astronomische Nachrichten ,299 (2):81– 85,Bibcode :1978AN....299...81S ,doi :10.1002/asna.19782990204 ^a b Leroy, J. L. (November 1995), "Linear polarimetry of AP stars. V. A general catalogue of measurements",Astronomy and Astrophysics Supplement ,114 : 79,Bibcode :1995A&AS..114...79L ^ Preston, George W.; Wolff, Sidney C. (June 1970), "The Very Slow Spectrum, Magnetic, and Photometric Variations of HD 9996",Astrophysical Journal ,160 : 1071,Bibcode :1970ApJ...160.1071P ,doi :10.1086/150494 ^ Mitalas, R.; Marlborough, J. M. (April 1973), "Some tests and consequences of the identification of promethium in HR 465",Astrophysical Journal ,181 :475– 480,Bibcode :1973ApJ...181..475M ,doi :10.1086/152063 ^ Harper, W. E. (1937)."The radial velocities of 917 stars" .Publications of the Dominion Astrophysical Observatory Victoria B.C .7 :1– 97.Bibcode :1937PDAO....7....1H . ^ Babcock, Horace W. (1958)."A Catalog of Magnetic Stars" .Astrophysical Journal Supplement .3 :141– 210.Bibcode :1958ApJS....3..141B .doi :10.1086/190035
