υ Sgr is a binary system with an orbital period of 137.939 days and is approximately 1,800 light years from Earth. The primary star dominates the visible radiation and spectrum, but the secondary is hotter and more massive. Some sources consider the "invisible" component to be the primary on the basis of its mass.[8] There is also a disc of material being stripped from the primary and transferring material to the secondary, but no eclipses[9]
The system is classified as a single-lined spectroscopic binary, but high excitation lines from the secondary can be detected in the ultraviolet.[10] Radial velocity variations were discovered in 1899,[13] The first orbit was calculated in 1914, reasonably close to modern understanding of the system.[14] Analysis of optical interferometry finds the two stars to be separated by 1.3 mas and have a difference in brightness of about 3.5 magnitudes.[7]
Properties
Light curves for Upsilon Sagittarii, adapted from Malcolm and Bell (1986)[4]
The primary component appears as an A typesupergiant, although published spectral types vary from F2p to B5II.[8] Contrasting components in the spectrum may originate from disc material, polar jets, or the star itself. The low mass and unusual chemical composition are also thought to produce misleading spectral calibrations, with the star not as massive or as luminous as the Ia luminosity class would suggest.[3]
The visible component is a helium star, almost entirely deficient of hydrogen.[15] It has also been described as a neon star, due to the very high relative levels of that element.[16] It has been stripped of its outer hydrogen layers after it expanded away from the main sequence.[15] It is thought to have originated as a main sequence star with around 8 M☉, expanded when it exhausted its core hydrogen, and now only 2.5 M☉ remains, highly inflated and giving the appearance of a supergiant star.[11] Other estimates give higher masses, as much as 5.45 M☉ and 8.56 M☉ at the known inclination of 50°.[8]
The supergiant component is also classified as an PV Telescopii variable, although it was originally catalogued as an eclipsing binary. It shows apparent magnitude fluctuations between +4.51 and +4.65 with a period of approximately 20 days.[5][17]
The companion is more massive than the supergiant primary, but so dim at visible frequencies as to be undetectable, although it can be seen in ultraviolet spectra. It is thought to be a B-type main sequence star accreting mass from the primary.[8]
^ abcdeVan Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
^ abcDucati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
^ abcdKipper, Tõnu; Klochkova, Valentina G. (2012). "High-Resolution Spectroscopy of the Hydrogen-Deficient Binary Upsilon Sgr". Baltic Astronomy. 21 (3): 219. Bibcode:2012BaltA..21..219K. doi:10.1515/astro-2017-0382.
^ abMalcolm, G. J.; Bell, S. A. (1986). "Evidence for pulsation in the hydrogen-deficient binary Upsilon Sagittarii". Monthly Notices of the Royal Astronomical Society. 222 (3): 543. Bibcode:1986MNRAS.222..543M. doi:10.1093/mnras/222.3.543.
^ abSamus, 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.
^Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.
^ abcHutter, D. J.; Tycner, C.; Zavala, R. T.; Benson, J. A.; Hummel, C. A.; Zirm, H. (2021). "Surveying the Bright Stars by Optical Interferometry. III. A Magnitude-limited Multiplicity Survey of Classical be Stars". The Astrophysical Journal Supplement Series. 257 (2): 69. arXiv:2109.06839. Bibcode:2021ApJS..257...69H. doi:10.3847/1538-4365/ac23cb. S2CID 237503492.
^ abcdeKoubský, P.; Harmanec, P.; Yang, S.; Netolický, M.; Škoda, P.; Šlechta, M.; Korčáková, D. (2006). "Properties and nature of Be stars. 25. A new orbital solution and the nature of a peculiar emission-line binary υ Sagittarii". Astronomy and Astrophysics. 459 (3): 849. Bibcode:2006A&A...459..849K. doi:10.1051/0004-6361:20065274.
^ abNetolický, M.; Bonneau, D.; Chesneau, O.; Harmanec, P.; Koubský, P.; Mourard, D.; Stee, P. (2009). "The circumbinary dusty disk around the hydrogen-deficient binary star υ Sagittarii". Astronomy and Astrophysics. 499 (3): 827. Bibcode:2009A&A...499..827N. doi:10.1051/0004-6361/200811192.
^ abcDudley, R. E.; Jeffery, C. S. (1990). "The Mass Ratio of Upsilon-Sagittarii from Ultraviolet Radial Velocities". Monthly Notices of the Royal Astronomical Society. 247: 400. Bibcode:1990MNRAS.247..400D.
^ abcLeushin, V. V. (2001). "Atmospheric Iron Abundance in the Primary Component of upsilon Sgr". Astronomy Letters. 27 (10): 634–644. Bibcode:2001AstL...27..634L. doi:10.1134/1.1404457. S2CID 122291723.
^ abcdefghiGilkis, Avishai; Shenar, Tomer (2023). "Ups!... I did it again: Unveiling the hidden companion in Upsilon Sagittarii, a unique binary system at a second mass transfer stage". Monthly Notices of the Royal Astronomical Society. 518 (3): 3541–3555. arXiv:2209.14315. Bibcode:2023MNRAS.518.3541G. doi:10.1093/mnras/stac3375.
^Campbell, W. W. (1895). "Stars whose spectra contain both bright and dark hydrogen lines". Astrophysical Journal. 2: 177. Bibcode:1895ApJ.....2..177C. doi:10.1086/140127.
^Wilson, R. E. (1915). "The orbit of the spectroscopic binary upsilon Sagittarii". Lick Observatory Bulletin. 8: 132–133. Bibcode:1915LicOB...8..132W. doi:10.5479/ADS/bib/1915LicOB.8.132W.
^ abLeushin, V. V.; Snezhko, L. I.; Chuvenkov, V. V. (1998). "History of the chemical evolution of the primary component of the binary system υ Sagittarius". Astronomy Letters. 24 (1): 39. Bibcode:1998AstL...24...39L.
^Leushin, V. V. (2000). "The primary component of υ Sagittarius is a neon star". Bulletin of the Special Astrophysical Observatory. Russian Academy of Sciences. 50: 60. Bibcode:2000BSAO...50...60L.
^Jeffery, C. Simon (2008). "Variable Star Designations for Extreme Helium Stars". Information Bulletin on Variable Stars. 5817: 1. Bibcode:2008IBVS.5817....1J.
^(in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 11 日
Further reading
Dudley, R. E., Jeffery, C. S., 1990. Mon. Not. R. astr. Soc.247, 400
January 24, 2023
upsilon, sagittarii, confused, with, cepheid, variable, sagittarii, upsilon, sagittarii, spectroscopic, binary, star, system, constellation, sagittarius, prototypical, hydrogen, deficient, binary, only, four, such, systems, known, unusual, spectrum, hydrogen, . Not to be confused with the Cepheid variable U Sagittarii Upsilon Sagittarii Upsilon Sgr y Sagittarii y Sgr is a spectroscopic binary star system in the constellation Sagittarius Upsilon Sagittarii is the prototypical hydrogen deficient binary HdB and one of only four such systems known The unusual spectrum of hydrogen deficient binaries has made stellar classification of Upsilon Sagittarii difficult Upsilon SagittariiLocation of y Sgr circled Observation dataEpoch J2000 Equinox J2000Constellation SagittariusRight ascension 19h 21m 43 62284s 1 Declination 15 57 18 0625 1 Apparent magnitude V 4 61 2 CharacteristicsSpectral type A2 Ia B2 Vpe 3 U B color index 0 53 2 B V color index 0 10 2 Variable type PV Tel 4 b Lyr 5 AstrometryRadial velocity Rv 8 9 6 km sProper motion m RA 1 34 1 mas yr Dec 6 25 1 mas yrParallax p 1 83 0 23 mas 1 Distanceapprox 1 800 ly approx 550 pc Absolute magnitude MV 4 73 1 14 7 Orbit 8 Period P 137 9 daysSemi major axis a 270 8 R Eccentricity e 0Inclination i 50 9 Semi amplitude K1 primary 49 6 10 km sSemi amplitude K2 secondary 29 7 10 km sDetails visible Mass2 5 4 11 M Radius23 12 R Luminosity4 700 12 L Surface gravity log g 1 2 12 cgsTemperature12 300 3 KMetallicity Fe H 0 2 3 dexRotational velocity v sin i 10 12 km sAge52 11 Myr invisible Mass6 2 7 M Radius2 2 12 R Luminosity1 300 12 L Surface gravity log g 1 0 12 cgsTemperature23 000 12 KRotational velocity v sin i 250 12 km sOther designationsy Sagittarii y Sgr Upsilon Sgr 46 Sagittarii BD 16 5283 FK5 727 GC 26697 HD 181615 HD 181616 HIP 95176 HR 7342 PPM 235885 SAO 162518Database referencesSIMBADdata Contents 1 System 2 Properties 3 Naming 4 References 5 Further readingSystem Edity Sgr is a binary system with an orbital period of 137 939 days and is approximately 1 800 light years from Earth The primary star dominates the visible radiation and spectrum but the secondary is hotter and more massive Some sources consider the invisible component to be the primary on the basis of its mass 8 There is also a disc of material being stripped from the primary and transferring material to the secondary but no eclipses 9 The system is classified as a single lined spectroscopic binary but high excitation lines from the secondary can be detected in the ultraviolet 10 Radial velocity variations were discovered in 1899 13 The first orbit was calculated in 1914 reasonably close to modern understanding of the system 14 Analysis of optical interferometry finds the two stars to be separated by 1 3 mas and have a difference in brightness of about 3 5 magnitudes 7 Properties Edit Light curves for Upsilon Sagittarii adapted from Malcolm and Bell 1986 4 The primary component appears as an A type supergiant although published spectral types vary from F2p to B5II 8 Contrasting components in the spectrum may originate from disc material polar jets or the star itself The low mass and unusual chemical composition are also thought to produce misleading spectral calibrations with the star not as massive or as luminous as the Ia luminosity class would suggest 3 The visible component is a helium star almost entirely deficient of hydrogen 15 It has also been described as a neon star due to the very high relative levels of that element 16 It has been stripped of its outer hydrogen layers after it expanded away from the main sequence 15 It is thought to have originated as a main sequence star with around 8 M expanded when it exhausted its core hydrogen and now only 2 5 M remains highly inflated and giving the appearance of a supergiant star 11 Other estimates give higher masses as much as 5 45 M and 8 56 M at the known inclination of 50 8 The supergiant component is also classified as an PV Telescopii variable although it was originally catalogued as an eclipsing binary It shows apparent magnitude fluctuations between 4 51 and 4 65 with a period of approximately 20 days 5 17 The companion is more massive than the supergiant primary but so dim at visible frequencies as to be undetectable although it can be seen in ultraviolet spectra It is thought to be a B type main sequence star accreting mass from the primary 8 Naming Edity Sagittarii has two entries in the Henry Draper Catalogue HD 181615 and HD 181616 In Chinese 建 Jian meaning Establishment refers to an asterism consisting of y Sagittarii 3 Sagittarii o Sagittarii p Sagittarii 43 Sagittarii and r Sagittarii Consequently the Chinese name for y Sagittarii itself is 建六 Jian liu English the Sixth Star of Establishment 18 References Edit a b c d e Van Leeuwen F 2007 Validation of the new Hipparcos reduction Astronomy and Astrophysics 474 2 653 664 arXiv 0708 1752 Bibcode 2007A amp A 474 653V doi 10 1051 0004 6361 20078357 S2CID 18759600 a b c Ducati J R 2002 VizieR Online Data Catalog Catalogue of Stellar Photometry in Johnson s 11 color system CDS ADC Collection of Electronic Catalogues 2237 Bibcode 2002yCat 2237 0D a b c d Kipper Tonu Klochkova Valentina G 2012 High Resolution Spectroscopy of the Hydrogen Deficient Binary Upsilon Sgr Baltic Astronomy 21 3 219 Bibcode 2012BaltA 21 219K doi 10 1515 astro 2017 0382 a b Malcolm G J Bell S A 1986 Evidence for pulsation in the hydrogen deficient binary Upsilon Sagittarii Monthly Notices of the Royal Astronomical Society 222 3 543 Bibcode 1986MNRAS 222 543M doi 10 1093 mnras 222 3 543 a b 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 Wilson Ralph Elmer 1953 General catalogue of stellar radial velocities Washington Bibcode 1953GCRV C 0W a b c Hutter D J Tycner C Zavala R T Benson J A Hummel C A Zirm H 2021 Surveying the Bright Stars by Optical Interferometry III A Magnitude limited Multiplicity Survey of Classical be Stars The Astrophysical Journal Supplement Series 257 2 69 arXiv 2109 06839 Bibcode 2021ApJS 257 69H doi 10 3847 1538 4365 ac23cb S2CID 237503492 a b c d e Koubsky P Harmanec P Yang S Netolicky M Skoda P Slechta M Korcakova D 2006 Properties and nature of Be stars 25 A new orbital solution and the nature of a peculiar emission line binary y Sagittarii Astronomy and Astrophysics 459 3 849 Bibcode 2006A amp A 459 849K doi 10 1051 0004 6361 20065274 a b Netolicky M Bonneau D Chesneau O Harmanec P Koubsky P Mourard D Stee P 2009 The circumbinary dusty disk around the hydrogen deficient binary star y Sagittarii Astronomy and Astrophysics 499 3 827 Bibcode 2009A amp A 499 827N doi 10 1051 0004 6361 200811192 a b c Dudley R E Jeffery C S 1990 The Mass Ratio of Upsilon Sagittarii from Ultraviolet Radial Velocities Monthly Notices of the Royal Astronomical Society 247 400 Bibcode 1990MNRAS 247 400D a b c Leushin V V 2001 Atmospheric Iron Abundance in the Primary Component of upsilon Sgr Astronomy Letters 27 10 634 644 Bibcode 2001AstL 27 634L doi 10 1134 1 1404457 S2CID 122291723 a b c d e f g h i Gilkis Avishai Shenar Tomer 2023 Ups I did it again Unveiling the hidden companion in Upsilon Sagittarii a unique binary system at a second mass transfer stage Monthly Notices of the Royal Astronomical Society 518 3 3541 3555 arXiv 2209 14315 Bibcode 2023MNRAS 518 3541G doi 10 1093 mnras stac3375 Campbell W W 1895 Stars whose spectra contain both bright and dark hydrogen lines Astrophysical Journal 2 177 Bibcode 1895ApJ 2 177C doi 10 1086 140127 Wilson R E 1915 The orbit of the spectroscopic binary upsilon Sagittarii Lick Observatory Bulletin 8 132 133 Bibcode 1915LicOB 8 132W doi 10 5479 ADS bib 1915LicOB 8 132W a b Leushin V V Snezhko L I Chuvenkov V V 1998 History of the chemical evolution of the primary component of the binary system y Sagittarius Astronomy Letters 24 1 39 Bibcode 1998AstL 24 39L Leushin V V 2000 The primary component of y Sagittarius is a neon star Bulletin of the Special Astrophysical Observatory Russian Academy of Sciences 50 60 Bibcode 2000BSAO 50 60L Jeffery C Simon 2008 Variable Star Designations for Extreme Helium Stars Information Bulletin on Variable Stars 5817 1 Bibcode 2008IBVS 5817 1J in Chinese AEEA Activities of Exhibition and Education in Astronomy 天文教育資訊網 2006 年 5 月 11 日Further reading EditDudley R E Jeffery C S 1990 Mon Not R astr Soc 247 400 Retrieved from https en wikipedia org w index php title Upsilon Sagittarii amp oldid 1131049107, wikipedia, wiki, book, books, library,
