Epsilon Pyxidis

Epsilon Pyxidis (ε Pyxidis) is quadruple[11] star system in the southern constellation of Pyxis. It is faintly visible to the naked eye, having a combined apparent visual magnitude of +5.60.[2] Based upon an annual parallax shift of 15.39 mas as seen from Earth,[1] it is located around 212 light years from the Sun. The system is deemed to be a member of the Sirius supercluster of stars that share a common motion through space.[5]

Epsilon Pyxidis
Location of ε Pyxidis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Pyxis
Right ascension  09h 09m 56.41024s[1]
Declination −30° 21′ 55.4460″[1]
Apparent magnitude (V) +5.60[2]
Characteristics
Spectral type A4 IV[3]
U−B color index +0.16[2]
B−V color index +0.16[2]
Astrometry
Radial velocity (Rv)−9.7±0.3[4] km/s
Proper motion (μ) RA: −1.93[1] mas/yr
Dec.: −48.99[1] mas/yr
Parallax (π)15.39 ± 0.30[1] mas
Distance212 ± 4 ly
(65 ± 1 pc)
Absolute magnitude (MV)+2.00[5]
Details
ε Pyx A
Mass2.07[6] M☉
Luminosity19[7] L☉
Surface gravity (log g)3.26[8] cgs
Temperature6368±1806[8] K
Metallicity [Fe/H]+0.04[8] dex
Rotational velocity (v sin i)108.3±0.3[9] km/s
Age560[6] Myr
Other designations
ε Pyx, CPD−29° 2933, FK5 1241, HD 78922, HIP 45001, HR 3644, SAO 200047, WDS J09099-3022A[10]
Database references
SIMBADdata

The primary, component A, is a white-hued A-type subgiant star with a stellar classification of A4 IV.[3] It is a microvariable, showing a 0.0056 change in magnitude with a frequency of 0.16245 times per day.[12] Epsilon Pyxidis has been catalogued as an Am star,[2] although this remains uncertain.[13] It has double[6] the mass of the Sun and radiates 19[7] times the Sun's luminosity from its photosphere at an effective temperature of 6,368 K.[8]

In addition to a close companion of unknown type at an angular separation of 0.17 arc seconds, the primary shares an orbit with a binary star system, components B and C, that lie at an angular separation of 17.8 arc seconds. At the estimated distance of this system, this corresponds to a projected separation of around 1,150 AU.[6] The B/C pair consist of visual magnitude 10.5 and 10.8 stars with a mean separation of 0.3 arc seconds.[11] They have estimated mass of 90% and 95% that of the Sun, respectively.[6]

References
  1. 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.
  2. Mendoza, E. E.; et al. (June 1978), "UBVRI photometry of 225 AM stars", Astronomical Journal, 83: 606–614, Bibcode:1978AJ.....83..606M, doi:10.1086/112242.
  3. Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, 3, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1982mcts.book.....H.
  4. 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, A61.
  5. Eggen, Olin J. (August 1998), "The Sirius Supercluster and Missing Mass near the Sun", The Astronomical Journal, 116 (2): 782–788, Bibcode:1998AJ....116..782E, doi:10.1086/300465.
  6. De Rosa, R. J.; et al. (2013), "The VAST Survey – III. The multiplicity of A-type stars within 75 pc", Monthly Notices of the Royal Astronomical Society, 437 (2): 1216, arXiv:1311.7141, Bibcode:2014MNRAS.437.1216D, doi:10.1093/mnras/stt1932.
  7. 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.
  8. Casagrande, L.; et al. (2011), "New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey", Astronomy & Astrophysics, 530 (A138): 21, arXiv:1103.4651, Bibcode:2011A&A...530A.138C, doi:10.1051/0004-6361/201016276.
  9. Díaz, C. G.; et al. (July 2011), "Accurate stellar rotational velocities using the Fourier transform of the cross correlation maximum", Astronomy & Astrophysics, 531: A143, arXiv:1012.4858, Bibcode:2011A&A...531A.143D, doi:10.1051/0004-6361/201016386.
  10. "eps Pyx". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-07-18.
  11. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  12. Koen, Chris; Eyer, Laurent (2002), "New periodic variables from the Hipparcos epoch photometry", Monthly Notices of the Royal Astronomical Society, 331: 45, arXiv:astro-ph/0112194, Bibcode:2002MNRAS.331...45K, doi:10.1046/j.1365-8711.2002.05150.x.
  13. Renson, P.; Manfroid, J. (May 2009), "Catalogue of Ap, HgMn and Am stars" (PDF), Astronomy and Astrophysics, 498 (3): 961–966, Bibcode:2009A&A...498..961R, doi:10.1051/0004-6361/200810788.
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