Phi2 Hydrae
Star in the constellation Hydra
Phi2 Hydrae , Latinized from φ2 Hydrae , is a star in the constellation Hydra . It originally received the Flamsteed designation of 1 Crateris before being placed in the Hydra constellation.[ 10] Based upon an annual parallax shift of 4.31 mas as seen from Earth, it is located roughly 760 light years from the Sun . The star is faintly visible to the naked eye with an apparent visual magnitude of 6.09.[ 3] It forms a triangle with the fainter φ1 Hydrae and the brighter φ3 Hydrae , between μ Hydrae and ν Hydrae .
Pulsations[ 6]
Period (days)
Amplitude (magnitude)
11.0
0.008
110.3
0.012
153.6
0.015
This is an evolved red giant star with a stellar classification of M1 III.[ 11] It is currently on the asymptotic giant branch ,[ 11] and is a semiregular variable that undergoes changes in luminosity according to three pulsation periods.[ 6] The star is radiating an estimated 703[ 8] times the Sun's luminosity from its photosphere at an effective temperature of 3,791 K.[ 8]
Phi2 Hydrae has a faint visual companion: a magnitude 12.20 star at an angular separation of 3.50 arc seconds along a position angle of 280°, as of 1959.[ 12]
References
^ EAS (1997). "The HIPPARCOS and TYCHO catalogues" . Astrometric and Photometric Star Catalogues Derived from the ESA Hipparcos Space Astrometry Mission . ESA SP Series. 1200 . Noordwijk, Netherlands: ESA Publications Division. Bibcode :1997HIP...C......0E . ISBN 9290923997 . Retrieved 14 December 2024 .
^ 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&A...474..653V , doi :10.1051/0004-6361:20078357 , S2CID 18759600 .
^ a b c de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics , 546 : 14, arXiv :1208.3048 , Bibcode :2012A&A...546A..61D , doi :10.1051/0004-6361/201219219 , S2CID 59451347 , A61.
^ Houk, Nancy; Smith-Moore, M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars , vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode :1988mcts.book.....H .
^ a b Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data , SIMBAD , Bibcode :1986EgUBV........0M .
^ a b c Tabur, V.; et al. (2009), "Long-term photometry and periods for 261 nearby pulsating M giants", Monthly Notices of the Royal Astronomical Society , 400 (4): 1945–61, arXiv :0908.3228 , Bibcode :2009MNRAS.400.1945T , doi :10.1111/j.1365-2966.2009.15588.x , S2CID 15358380 .
^ 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 c d McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society , 427 (1): 343–57, arXiv :1208.2037 , Bibcode :2012MNRAS.427..343M , doi :10.1111/j.1365-2966.2012.21873.x , S2CID 118665352 .
^ "* phi02 Hya" . SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2017-03-17 .{{cite web }}
: CS1 maint: postscript (link )
^ Wagman, M. (August 1987), "Flamsteed's Missing Stars", Journal for the History of Astronomy , 18 (3): 216, Bibcode :1987JHA....18..209W , doi :10.1177/002182868701800305 , S2CID 118445625 .
^ a b Eggen, Olin J. (July 1992), "Asymptotic giant branch stars near the sun", Astronomical Journal , 104 (1): 275–313, Bibcode :1992AJ....104..275E , doi :10.1086/116239 .
^ Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal , 122 (6): 3466–3471, Bibcode :2001AJ....122.3466M , doi :10.1086/323920 .