Gamma Leonis (γ Leonis, abbreviated Gamma Leo, γ Leo), also named Algieba/ælˈdʒiːbə/,[8][9] is a binary star system in the constellation of Leo. In 2009, a planetary companion around the primary was announced.
Double star γ Leonis rho(ρ):4.7 arc" Thêta(θ):125,9°
γ Leonis (Latinised to Gamma Leonis) is the star's Bayer designation. The A and B components of the binary are often referred to as γ1 Leonis and γ2 Leonis, respectively.
It also bore the traditional name Algieba or Al Gieba, which originated from the ArabicالجبهةAl-Jabhah, meaning 'the forehead' (despite this meaning, the star actually appears in the mane of Leo). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[10] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[11] included a table of the first two batches of names approved by the WGSN, which included Algieba for this star.
The star's traditional Latin name was Juba. It is known as 軒轅十二 (the Twelfth Star of Xuanyuan) in Chinese (Xuanyuan is the name of the Yellow Emperor).[citation needed]
The bright binary system in Leo with orange-red and yellow or greenish-yellow components is visible through a modest telescope under good atmospheric conditions. To the naked eye, the Algieba system shines at mid-second magnitude, but a telescope easily splits the pair. The brighter component has an apparent magnitude of +2.28 and is of spectral class K1-IIIbCN-0.5. The giant K star has a surface temperature of 4,470 K, a luminosity 180 times that of the Sun, and a diameter 23 times that of the Sun. The companion star has an apparent magnitude of +3.51 and belongs to the spectral class G7IIICN-I. The giant G star has a temperature of 4,980 K, a luminosity of 50 times that of the Sun, and a diameter 10 times that of the Sun. With angular separation of just over 4″, the two stars are at least 170 AU apart (four times the distance between the Sun and Pluto), and have an orbital period of over 500 years.[7] Because the orbital period is so long, only a fraction of the full path has been observed since discovery.
Both stars are almost certainly true giants, meaning that they have stopped fusinghydrogen to helium in their cores and have expanded to great proportions. Although there has been too little observation of their orbit to calculate their masses, comparison with evolutionary calculations suggests that each is about double the mass of the Sun. Originating from the same interstellar cloud some two billion years ago, the stars have iron contents about a third that of the Sun. It is hard to tell how far along they might be in their life cycle. They both may be fusing helium in their cores, or they could be giants in development, with quiet helium cores that are waiting to fire up. The chemical composition at the surface, which is influenced by age, suggests the former.[citation needed]
VariabilityEdit
γ Leonis is a suspected variable star, with a visual magnitude range of 1.84 to 2.03. It is not known which of the two components is variable.[4] In 1959, the star was mistakenly published as an eclipsing binary due to a typographical error when referring to Y Leonis.[13]
Planetary systemEdit
On November 6, 2009, the discovery of a planetary companion around primary star γ1 Leonis (γ Leonis A) was announced.[3] The radial velocity measurements suggest two additional periodicities of 8.5 and 1,340 days. The former is likely due to stellar pulsation, whereas the latter could be indicative of the presence of an additional planetary companion with 2.14 Jupiter masses, moderate eccentricity (e=0.13) and located at 2.6 AU away from the giant star. Nevertheless, the nature of such a signal is still unclear and further investigations are needed to confirm or rule out an additional substellar companion.
^ abcdevan Leeuwen, F. (November 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.
^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): 3466–3471. Bibcode:2001AJ....122.3466M. doi:10.1086/323920. ISSN 0004-6256.
^ abcdefHan, Inwoo; Lee, B. C.; Kim, K. M.; Mkrtichian, D. E.; Hatzes, A. P.; Valyavin, G. (2010). "Detection of a Planetary Companion around the giant star γ-1 Leonis". Astronomy and Astrophysics. 509: A24. arXiv:0911.0968. Bibcode:2010A&A...509A..24H. doi:10.1051/0004-6361/200912536. S2CID 118962986.
^ 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.
^Famaey, B.; et al. (January 2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", Astronomy and Astrophysics, 430: 165–186, arXiv:astro-ph/0409579, Bibcode:2005A&A...430..165F, doi:10.1051/0004-6361:20041272, S2CID 17804304
^ abcdefgMcWilliam, Andrew (December 1990), "High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances", Astrophysical Journal Supplement Series, 74: 1075–1128, Bibcode:1990ApJS...74.1075M, doi:10.1086/191527
^ abMason; Hartkopf, William I.; Wycoff, Gary L.; Holdenried, Ellis R. (2006). "Speckle Interferometry at the US Naval Observatory. XII". The Astronomical Journal. 132 (5): 2219–2230. Bibcode:2006AJ....132.2219M. doi:10.1086/508231.
^Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN978-1-931559-44-7.
^"IAU Catalog of Star Names". Retrieved 28 July 2016.
^"IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
^"Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.
^Proctor, Mary (July 1896), "Evenings with the Stars", Popular Astronomy, 4: 565
^"Reports of Observatories". Astronomical Journal. 64: 273. 1959. Bibcode:1959AJ.....64..273.. doi:10.1086/107936.
External linksEdit
Algieba at Jim Kaler's Stars
Astronomical Reference from Author David Darling
October 20, 2023
gamma, leonis, leonis, abbreviated, gamma, also, named, algieba, binary, star, system, constellation, 2009, planetary, companion, around, primary, announced, leonislocation, leonis, circled, observation, dataepoch, j2000, equinox, j2000constellation, leoright,. Gamma Leonis g Leonis abbreviated Gamma Leo g Leo also named Algieba ae l ˈ dʒ iː b e 8 9 is a binary star system in the constellation of Leo In 2009 a planetary companion around the primary was announced g LeonisLocation of g Leonis circled Observation dataEpoch J2000 Equinox J2000Constellation LeoRight ascension 10h 19m 58 35056s 1 Declination 19 50 29 3468 1 Apparent magnitude V 2 08 2 37 3 64 2 CharacteristicsSpectral type K1 III 3 G7 IIIbU B color index 1 00B V color index 1 14Variable type Suspected 4 AstrometryRadial velocity Rv 36 24 0 18 5 km sProper motion m RA 304 30 1 mas yr Dec 154 28 1 mas yrParallax p 25 07 0 52 mas 1 Distance130 3 ly 39 9 0 8 pc Absolute magnitude MV 0 27 0 98 6 Orbit 3 7 Period P 510 3 yrSemi major axis a 4 24 Eccentricity e 0 845Inclination i 76 0 Longitude of the node W 143 4 Periastron epoch T 1671 3Detailsg Leo AMass1 23 3 M Radius31 88 3 R Luminosity320 3 L Surface gravity log g 2 35 6 cgsTemperature4 470 6 KMetallicity Fe H 0 49 0 12 6 dexg Leo BRadius10 citation needed R Luminosity40 citation needed L Surface gravity log g 2 98 6 cgsTemperature4 980 6 KMetallicity Fe H 0 52 0 11 6 dexOther designationsAlgieba g Leonis 41 Leo BD 20 2467 GCTP 2423 00 HIP 50583 NSV 4823 LTT 12764 12765 WDS 10200 1950g Leo A g1 Leonis HD 89484 HR 4057 SAO 81298g Leo B g2 Leonis HD 89485 HR 4058 SAO 81299Database referencesSIMBADdataExoplanet ArchivedataExtrasolar PlanetsEncyclopaediadata Contents 1 Nomenclature 2 Stellar system 3 Variability 4 Planetary system 5 References 6 External linksNomenclature Edit nbsp Double star g Leonis rho r 4 7 arc Theta 8 125 9 g Leonis Latinised to Gamma Leonis is the star s Bayer designation The A and B components of the binary are often referred to as g1 Leonis and g2 Leonis respectively It also bore the traditional name Algieba or Al Gieba which originated from the Arabic الجبهة Al Jabhah meaning the forehead despite this meaning the star actually appears in the mane of Leo In 2016 the International Astronomical Union organized a Working Group on Star Names WGSN 10 to catalog and standardize proper names for stars The WGSN s first bulletin of July 2016 11 included a table of the first two batches of names approved by the WGSN which included Algieba for this star The star s traditional Latin name was Juba It is known as 軒轅十二 the Twelfth Star of Xuanyuan in Chinese Xuanyuan is the name of the Yellow Emperor citation needed Algieba along with Zeta Leonis Regulus Mu Leonis Epsilon Leonis and Eta Leonis have collectively been called the Sickle which is an asterism that marks the head of Leo 12 Stellar system EditThe bright binary system in Leo with orange red and yellow or greenish yellow components is visible through a modest telescope under good atmospheric conditions To the naked eye the Algieba system shines at mid second magnitude but a telescope easily splits the pair The brighter component has an apparent magnitude of 2 28 and is of spectral class K1 IIIbCN 0 5 The giant K star has a surface temperature of 4 470 K a luminosity 180 times that of the Sun and a diameter 23 times that of the Sun The companion star has an apparent magnitude of 3 51 and belongs to the spectral class G7IIICN I The giant G star has a temperature of 4 980 K a luminosity of 50 times that of the Sun and a diameter 10 times that of the Sun With angular separation of just over 4 the two stars are at least 170 AU apart four times the distance between the Sun and Pluto and have an orbital period of over 500 years 7 Because the orbital period is so long only a fraction of the full path has been observed since discovery Both stars are almost certainly true giants meaning that they have stopped fusing hydrogen to helium in their cores and have expanded to great proportions Although there has been too little observation of their orbit to calculate their masses comparison with evolutionary calculations suggests that each is about double the mass of the Sun Originating from the same interstellar cloud some two billion years ago the stars have iron contents about a third that of the Sun It is hard to tell how far along they might be in their life cycle They both may be fusing helium in their cores or they could be giants in development with quiet helium cores that are waiting to fire up The chemical composition at the surface which is influenced by age suggests the former citation needed Variability Editg Leonis is a suspected variable star with a visual magnitude range of 1 84 to 2 03 It is not known which of the two components is variable 4 In 1959 the star was mistakenly published as an eclipsing binary due to a typographical error when referring to Y Leonis 13 Planetary system EditOn November 6 2009 the discovery of a planetary companion around primary star g1 Leonis g Leonis A was announced 3 The radial velocity measurements suggest two additional periodicities of 8 5 and 1 340 days The former is likely due to stellar pulsation whereas the latter could be indicative of the presence of an additional planetary companion with 2 14 Jupiter masses moderate eccentricity e 0 13 and located at 2 6 AU away from the giant star Nevertheless the nature of such a signal is still unclear and further investigations are needed to confirm or rule out an additional substellar companion The g1 Leonis planetary system Companion in order from star Mass Semimajor axis AU Orbital period days Eccentricity Inclination Radiusb 8 78 MJ 1 19 429 0 14 c unconfirmed 2 14 MJ 2 6 1 340 0 13 References Edit a b c d e van Leeuwen F November 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 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 3471 Bibcode 2001AJ 122 3466M doi 10 1086 323920 ISSN 0004 6256 a b c d e f Han Inwoo Lee B C Kim K M Mkrtichian D E Hatzes A P Valyavin G 2010 Detection of a Planetary Companion around the giant star g 1 Leonis Astronomy and Astrophysics 509 A24 arXiv 0911 0968 Bibcode 2010A amp A 509A 24H doi 10 1051 0004 6361 200912536 S2CID 118962986 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 Famaey B et al January 2005 Local kinematics of K and M giants from CORAVEL Hipparcos Tycho 2 data Revisiting the concept of superclusters Astronomy and Astrophysics 430 165 186 arXiv astro ph 0409579 Bibcode 2005A amp A 430 165F doi 10 1051 0004 6361 20041272 S2CID 17804304 a b c d e f g McWilliam Andrew December 1990 High resolution spectroscopic survey of 671 GK giants I Stellar atmosphere parameters and abundances Astrophysical Journal Supplement Series 74 1075 1128 Bibcode 1990ApJS 74 1075M doi 10 1086 191527 a b Mason Hartkopf William I Wycoff Gary L Holdenried Ellis R 2006 Speckle Interferometry at the US Naval Observatory XII The Astronomical Journal 132 5 2219 2230 Bibcode 2006AJ 132 2219M doi 10 1086 508231 Kunitzsch Paul Smart Tim 2006 A Dictionary of Modern star Names A Short Guide to 254 Star Names and Their Derivations 2nd rev ed Cambridge Massachusetts Sky Pub ISBN 978 1 931559 44 7 IAU Catalog of Star Names Retrieved 28 July 2016 IAU Working Group on Star Names WGSN Retrieved 22 May 2016 Bulletin of the IAU Working Group on Star Names No 1 PDF Retrieved 28 July 2016 Proctor Mary July 1896 Evenings with the Stars Popular Astronomy 4 565 Reports of Observatories Astronomical Journal 64 273 1959 Bibcode 1959AJ 64 273 doi 10 1086 107936 External links EditAlgieba at Jim Kaler s Stars Astronomical Reference from Author David Darling Retrieved from https en wikipedia org w index php title Gamma Leonis amp oldid 1179291737, wikipedia, wiki, book, books, library,
