Delta2 Lyrae (δ2 Lyr) is a 4th magnitude star in the constellation Lyra, approximately 900 light years away from Earth. It is one of the M4II spectral standard stars,[7] meaning it is a bright giant star with a surface temperature around 3,600 kelvins. It puts out more energy than 10,000 suns, although more than 90% of it at longer than visual wavelengths. Direct angular measurements, combined with the Hipparcos parallax, give a radius of 1.1[8] - 1.3[9]astronomical units, comparable to the size calculated from other observed data.
It began life as a hot blue main sequence star, but now is a large cool asymptotic giant branch star with a degenerate carbon-oxygen core. It is a semi-regular variable star that has its brightness change by 0.2 magnitudes over an ill-defined period. Delta2 Lyrae was once thought to form a visual binary with the star Delta1 Lyrae, but it does not, only appearing to do so if seen from earth's direction.[citation needed]
δ2 Lyrae is a variable star, probably a semiregular variable. It has a magnitude range of 4.22 to 4.33.[1] It is the brightest member of the scattered open clusterStephenson 1, also known as the δ Lyrae Cluster. Other known members include δ1 Lyrae, a handful of 8th-9th magnitudes stars, and at least thirty other stars down to 14th magnitude.[10][2]
Multiple star catalogues list several companions to δ2 Lyrae, with designations such as ADS 11825. Two of them are a close pair of 10th magnitude stars about 87" from δ2, designated components B and C.[11] The spectral type of the pair suggests that they are at the same distance as Delta2 Lyrae, which could mean that the three stars form a triple star system. In this case, the ADS 11825BC pair would be 24,000 AU away from δ2 Lyrae, and it would take 24,000 years for it to make an orbit. The two stars in the BC system take at least 10,500 years to make an orbit and are separated by 600AU.[citation needed]
References
^ abcdSamus, 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.
^ abEggen, O. J. (April 1968). "Photometric evidence for the existence of a delta Lyrae cluster". Astrophysical Journal. 152: 77. Bibcode:1968ApJ...152...77E. doi:10.1086/149525.
^ abcTsuji, T. (2007). "Isotopic abundances of Carbon and Oxygen in Oxygen-rich giant stars". Proceedings of the International Astronomical Union. 2: 307–310. arXiv:astro-ph/0610180. Bibcode:2007IAUS..239..307T. doi:10.1017/S1743921307000622. S2CID 119362842.
^ abcBlum, R. D.; Ramirez, S. V.; Sellgren, K.; Olsen, K. (2003). "Really Cool Stars and the Star Formation History at the Galactic Center". The Astrophysical Journal. 597 (1): 323–346. arXiv:astro-ph/0307291. Bibcode:2003ApJ...597..323B. doi:10.1086/378380. S2CID 5664467.
^ abLevesque, E. M.; Massey, P.; Olsen, K. A. G.; Plez, B.; Josselin, E.; Maeder, A.; Meynet, G. (2005). "The Effective Temperature Scale of Galactic Red Supergiants: Cool, but Not as Cool as We Thought". The Astrophysical Journal. 628 (2): 973–985. arXiv:astro-ph/0504337. Bibcode:2005ApJ...628..973L. doi:10.1086/430901. S2CID 15109583.
^"/ftp/cats/more/HIP/cdroms/cats". Centre de Données astronomiques de Strasbourg. Strasbourg astronomical Data Center. Retrieved 15 October 2022.
^Garcia, B. (1989). "A list of MK standard stars". Bulletin d'Information du Centre de Données Stellaires. 36: 27. Bibcode:1989BICDS..36...27G.
^ Dyck, H. M.; Benson, J. A.; Van Belle, G. T.; Ridgway, S. T. (1996). "Radii and Effective Temperatures for K and M Giants and Supergiants". The Astronomical Journal. 111: 1705. Bibcode:1996AJ....111.1705D. doi:10.1086/117910.
^ Richichi, A.; Percheron, I.; Khristoforova, M. (2005). "CHARM2: An updated Catalog of High Angular Resolution Measurements". Astronomy and Astrophysics. 431 (2): 773. Bibcode:2005A&A...431..773R. doi:10.1051/0004-6361:20042039.
^Stephenson, C. B. (1959). "A Possible New Galactic Cluster Involving δ Lyrae". Publications of the Astronomical Society of the Pacific. 71 (419): 145. Bibcode:1959PASP...71..145S. doi:10.1086/127349.
^Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
March 11, 2023
delta2, lyrae, other, stars, with, this, bayer, designation, lyrae, magnitude, star, constellation, lyra, approximately, light, years, away, from, earth, m4ii, spectral, standard, stars, meaning, bright, giant, star, with, surface, temperature, around, kelvins. For other stars with this Bayer designation see d Lyrae Delta2 Lyrae d2 Lyr is a 4th magnitude star in the constellation Lyra approximately 900 light years away from Earth It is one of the M4II spectral standard stars 7 meaning it is a bright giant star with a surface temperature around 3 600 kelvins It puts out more energy than 10 000 suns although more than 90 of it at longer than visual wavelengths Direct angular measurements combined with the Hipparcos parallax give a radius of 1 1 8 1 3 9 astronomical units comparable to the size calculated from other observed data d2 LyraeLocation of d2 Lyrae circled Observation dataEpoch J2000 0 Equinox J2000 0Constellation LyraRight ascension 18h 54m 30 2838sDeclination 36 53 55 007 Apparent magnitude V 4 22 4 33 1 CharacteristicsSpectral type M4 II 1 U B color index 1 65B V color index 1 68Variable type SRc 1 AstrometryRadial velocity Rv 25 55 km sProper motion m RA 7 36 mas yr Dec 4 06 mas yrParallax p 4 43 0 18 masDistance740 30 ly 226 9 pc Absolute magnitude MV 3 3 2 DetailsMass7 3 3 M Radius286 3 381 4 R Luminosity12 900 3 23 100 4 L Surface gravity log g 0 5 cgsTemperature3 550 5 3 650 4 KOther designationsDelta2 Lyrae 12 Lyrae HR 7139 BD 36 3319 HD 175588 SAO 67559 HIP 92791 GC 25959 CCDM J18545 3654 WDS J18545 3654Database referencesSIMBADdataLyra with the d Lyrae pair and surrounding cluster stars left of centre A light curve for Delta2 Lyrae plotted from Hipparcos data 6 It began life as a hot blue main sequence star but now is a large cool asymptotic giant branch star with a degenerate carbon oxygen core It is a semi regular variable star that has its brightness change by 0 2 magnitudes over an ill defined period Delta2 Lyrae was once thought to form a visual binary with the star Delta1 Lyrae but it does not only appearing to do so if seen from earth s direction citation needed d2 Lyrae is a variable star probably a semiregular variable It has a magnitude range of 4 22 to 4 33 1 It is the brightest member of the scattered open cluster Stephenson 1 also known as the d Lyrae Cluster Other known members include d1 Lyrae a handful of 8th 9th magnitudes stars and at least thirty other stars down to 14th magnitude 10 2 Multiple star catalogues list several companions to d2 Lyrae with designations such as ADS 11825 Two of them are a close pair of 10th magnitude stars about 87 from d2 designated components B and C 11 The spectral type of the pair suggests that they are at the same distance as Delta2 Lyrae which could mean that the three stars form a triple star system In this case the ADS 11825BC pair would be 24 000 AU away from d2 Lyrae and it would take 24 000 years for it to make an orbit The two stars in the BC system take at least 10 500 years to make an orbit and are separated by 600AU citation needed References Edit a b c d 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 Eggen O J April 1968 Photometric evidence for the existence of a delta Lyrae cluster Astrophysical Journal 152 77 Bibcode 1968ApJ 152 77E doi 10 1086 149525 a b c Tsuji T 2007 Isotopic abundances of Carbon and Oxygen in Oxygen rich giant stars Proceedings of the International Astronomical Union 2 307 310 arXiv astro ph 0610180 Bibcode 2007IAUS 239 307T doi 10 1017 S1743921307000622 S2CID 119362842 a b c Blum R D Ramirez S V Sellgren K Olsen K 2003 Really Cool Stars and the Star Formation History at the Galactic Center The Astrophysical Journal 597 1 323 346 arXiv astro ph 0307291 Bibcode 2003ApJ 597 323B doi 10 1086 378380 S2CID 5664467 a b Levesque E M Massey P Olsen K A G Plez B Josselin E Maeder A Meynet G 2005 The Effective Temperature Scale of Galactic Red Supergiants Cool but Not as Cool as We Thought The Astrophysical Journal 628 2 973 985 arXiv astro ph 0504337 Bibcode 2005ApJ 628 973L doi 10 1086 430901 S2CID 15109583 ftp cats more HIP cdroms cats Centre de Donnees astronomiques de Strasbourg Strasbourg astronomical Data Center Retrieved 15 October 2022 Garcia B 1989 A list of MK standard stars Bulletin d Information du Centre de Donnees Stellaires 36 27 Bibcode 1989BICDS 36 27G Dyck H M Benson J A Van Belle G T Ridgway S T 1996 Radii and Effective Temperatures for K and M Giants and Supergiants The Astronomical Journal 111 1705 Bibcode 1996AJ 111 1705D doi 10 1086 117910 Richichi A Percheron I Khristoforova M 2005 CHARM2 An updated Catalog of High Angular Resolution Measurements Astronomy and Astrophysics 431 2 773 Bibcode 2005A amp A 431 773R doi 10 1051 0004 6361 20042039 Stephenson C B 1959 A Possible New Galactic Cluster Involving d Lyrae Publications of the Astronomical Society of the Pacific 71 419 145 Bibcode 1959PASP 71 145S doi 10 1086 127349 Mason Brian D Wycoff Gary L Hartkopf William I Douglass Geoffrey G Worley Charles E 2001 The 2001 US Naval Observatory Double Star CD ROM I The Washington Double Star Catalog The Astronomical Journal 122 6 3466 Bibcode 2001AJ 122 3466M doi 10 1086 323920 Retrieved from https en wikipedia org w index php title Delta2 Lyrae amp oldid 1122522294, wikipedia, wiki, book, books, library,
