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HD 81799

January 01, 1970

HD 81799 (G Hydrae) is a suspected astrometric binary[8] star system in the equatorial constellation of Hydra. It is visible to the naked eye with an apparent visual magnitude of 4.69.[2] The distance to this system, as determined from an annual parallax shift of 19.9 mas,[1] is 164 light years. It is moving further away from the Earth with a heliocentric radial velocity of 29 km/s.[1] The system has a relatively high rate of proper motion, traversing the celestial sphere at the rate of 233±19 mas/yr along a position angle of 136°.[9]

HD 81799
Observation data
Epoch J2000      Equinox J2000
Constellation Hydra
Right ascension 09h 27m 18.43258s[1]
Declination −22° 20′ 37.4967″[1]
Apparent magnitude (V) 4.69[2]
Characteristics
Spectral type K2+ IIIb[3]
B−V color index 1.154[4]
Astrometry
Radial velocity (Rv)29.05±0.28[1] km/s
Proper motion (μ) RA: +160.160[1] mas/yr
Dec.: −173.131[1] mas/yr
Parallax (π)19.8887 ± 0.3128 mas[1]
Distance164 ± 3 ly
(50.3 ± 0.8 pc)
Absolute magnitude (MV)1.32[5]
Details
Radius10.6[6] R☉
Luminosity41.97[5] L☉
Surface gravity (log g)2.43[2] cgs
Temperature4,490[2] K
Metallicity [Fe/H]−0.01[2] dex
Other designations
G Hya, BD−21° 2802, HD 81799, HIP 46371, HR 3749, SAO 177469, LTT 3479[7]
Database references
SIMBADdata

The stellar classification of the visible component is K2+ IIIb,[3] which matches an evolved K-type giant star. It is a red clump star, which indicates it is on the horizontal branch and is generating energy through helium fusion at its core.[4] The interferometry-measured angular diameter of the primary, after correcting for limb darkening, is 1.96±0.03 mas,[10] which, at its estimated distance, equates to a physical radius of about 10.6 times the radius of the Sun.[6] It is radiating 42[5] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,490 K.[2]

The system is a likely (99.4% chance) source of the X-ray emission coming from these coordinates.[11]

References edit

  1. ^ a b c d e f g h 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.
  2. ^ a b c d e f Soubiran, C.; Le Campion, J.-F.; Cayrel de Strobel, G.; Caillo, A. (June 2010), "The PASTEL catalogue of stellar parameters", Astronomy and Astrophysics, 515: A111, arXiv:1004.1069, Bibcode:2010A&A...515A.111S, doi:10.1051/0004-6361/201014247, S2CID 118362423.
  3. ^ a b Keenan, P.; McNeil, R. (October 1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245–266, Bibcode:1989ApJS...71..245K, doi:10.1086/191373
  4. ^ a b Alves, David R. (August 2000), "K-Band Calibration of the Red Clump Luminosity", The Astrophysical Journal, 539 (2): 732–741, arXiv:astro-ph/0003329, Bibcode:2000ApJ...539..732A, doi:10.1086/309278, S2CID 16673121.
  5. ^ a b c 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.
  6. ^ a b Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R*) is given by:
     
  7. ^ "HD 81799". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-07-24.
  8. ^ Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  9. ^ Wroblewski, H.; Torres, C. (March 1998), "New proper motion determination of Luyten catalogue stars (LTT) with declination between -5° and -30° and right ascension between 0h and 13h 30m", Astronomy and Astrophysics Supplement, 128: 457–458, Bibcode:1998A&AS..128..457W, doi:10.1051/aas:1998157.
  10. ^ Richichi, A.; et al. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039
  11. ^ Haakonsen, Christian Bernt; Rutledge, Robert E. (September 2009), "XID II: Statistical Cross-Association of ROSAT Bright Source Catalog X-ray Sources with 2MASS Point Source Catalog Near-Infrared Sources", The Astrophysical Journal Supplement, 184 (1): 138–151, arXiv:0910.3229, Bibcode:2009ApJS..184..138H, doi:10.1088/0067-0049/184/1/138, S2CID 119267456.

January 01, 1970
81799, hydrae, suspected, astrometric, binary, star, system, equatorial, constellation, hydra, visible, naked, with, apparent, visual, magnitude, distance, this, system, determined, from, annual, parallax, shift, light, years, moving, further, away, from, eart. HD 81799 G Hydrae is a suspected astrometric binary 8 star system in the equatorial constellation of Hydra It is visible to the naked eye with an apparent visual magnitude of 4 69 2 The distance to this system as determined from an annual parallax shift of 19 9 mas 1 is 164 light years It is moving further away from the Earth with a heliocentric radial velocity of 29 km s 1 The system has a relatively high rate of proper motion traversing the celestial sphere at the rate of 233 19 mas yr along a position angle of 136 9 HD 81799 Observation dataEpoch J2000 Equinox J2000 Constellation Hydra Right ascension 09h 27m 18 43258s 1 Declination 22 20 37 4967 1 Apparent magnitude V 4 69 2 Characteristics Spectral type K2 IIIb 3 B V color index 1 154 4 AstrometryRadial velocity Rv 29 05 0 28 1 km sProper motion m RA 160 160 1 mas yr Dec 173 131 1 mas yrParallax p 19 8887 0 3128 mas 1 Distance164 3 ly 50 3 0 8 pc Absolute magnitude MV 1 32 5 DetailsRadius10 6 6 R Luminosity41 97 5 L Surface gravity log g 2 43 2 cgsTemperature4 490 2 KMetallicity Fe H 0 01 2 dex Other designationsG Hya BD 21 2802 HD 81799 HIP 46371 HR 3749 SAO 177469 LTT 3479 7 Database referencesSIMBADdata The stellar classification of the visible component is K2 IIIb 3 which matches an evolved K type giant star It is a red clump star which indicates it is on the horizontal branch and is generating energy through helium fusion at its core 4 The interferometry measured angular diameter of the primary after correcting for limb darkening is 1 96 0 03 mas 10 which at its estimated distance equates to a physical radius of about 10 6 times the radius of the Sun 6 It is radiating 42 5 times the Sun s luminosity from its enlarged photosphere at an effective temperature of 4 490 K 2 The system is a likely 99 4 chance source of the X ray emission coming from these coordinates 11 References edit a b c d e f g h Brown A G A et al Gaia collaboration August 2018 Gaia Data Release 2 Summary of the contents and survey properties Astronomy amp Astrophysics 616 A1 arXiv 1804 09365 Bibcode 2018A amp A 616A 1G doi 10 1051 0004 6361 201833051 a b c d e f Soubiran C Le Campion J F Cayrel de Strobel G Caillo A June 2010 The PASTEL catalogue of stellar parameters Astronomy and Astrophysics 515 A111 arXiv 1004 1069 Bibcode 2010A amp A 515A 111S doi 10 1051 0004 6361 201014247 S2CID 118362423 a b Keenan P McNeil R October 1989 The Perkins catalog of revised MK types for the cooler stars Astrophysical Journal Supplement Series 71 245 266 Bibcode 1989ApJS 71 245K doi 10 1086 191373 a b Alves David R August 2000 K Band Calibration of the Red Clump Luminosity The Astrophysical Journal 539 2 732 741 arXiv astro ph 0003329 Bibcode 2000ApJ 539 732A doi 10 1086 309278 S2CID 16673121 a b c 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 a b Lang Kenneth R 2006 Astrophysical formulae Astronomy and astrophysics library vol 1 3rd ed Birkhauser ISBN 3 540 29692 1 The radius R is given by 2 R 10 3 50 3 1 96 AU 0 0046491 AU R 21 2 R displaystyle begin aligned 2 cdot R amp frac 10 3 cdot 50 3 cdot 1 96 text AU 0 0046491 text AU R bigodot amp approx 21 2 cdot R bigodot end aligned nbsp HD 81799 SIMBAD Centre de donnees astronomiques de Strasbourg Retrieved 2018 07 24 Eggleton P P Tokovinin A A 2008 A catalogue of multiplicity among bright stellar systems Monthly Notices of the Royal Astronomical Society 389 2 869 arXiv 0806 2878 Bibcode 2008MNRAS 389 869E doi 10 1111 j 1365 2966 2008 13596 x S2CID 14878976 Wroblewski H Torres C March 1998 New proper motion determination of Luyten catalogue stars LTT with declination between 5 and 30 and right ascension between 0h and 13h 30m Astronomy and Astrophysics Supplement 128 457 458 Bibcode 1998A amp AS 128 457W doi 10 1051 aas 1998157 Richichi A et al February 2005 CHARM2 An updated Catalog of High Angular Resolution Measurements Astronomy and Astrophysics 431 2 773 777 Bibcode 2005A amp A 431 773R doi 10 1051 0004 6361 20042039 Haakonsen Christian Bernt Rutledge Robert E September 2009 XID II Statistical Cross Association of ROSAT Bright Source Catalog X ray Sources with 2MASS Point Source Catalog Near Infrared Sources The Astrophysical Journal Supplement 184 1 138 151 arXiv 0910 3229 Bibcode 2009ApJS 184 138H doi 10 1088 0067 0049 184 1 138 S2CID 119267456 Retrieved from https en wikipedia org w index php title HD 81799 amp oldid 1143453300, wikipedia, wiki, book, books, library,

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