Theta Pyxidis

Theta Pyxidis (Theta Pyx, θ Pyxidis, θ Pyx) is a red M-type giant in the constellation Pyxis. It is approximately 500 ± 30 light years from Earth.[1] It is of spectral type M1III and semi-regular variable with two measured periods of 13 and 98.3 days, and an average visual magnitude of 4.71,[4] It shines with a luminosity approximately 970 times that of the Sun and has a surface temperature of 3825 K.[8] It has a diameter around 54 times that of the Sun.[7]

Theta Pyxidis
Location of θ Pyxidis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Pyxis
Right ascension 09h 21m 29.60s[1]
Declination –25° 57′ 55.5″[1]
Apparent magnitude (V) 4.718[2]
Characteristics
Spectral type M0.5 III Ba0.5[3]
U−B color index +1.984[2]
B−V color index +1.651[2]
Variable type semiregular variable[4]
Astrometry
Radial velocity (Rv)+20.0±2.8[5] km/s
Proper motion (μ) RA: –12.24 ± 0.40[1] mas/yr
Dec.: –9.29 ± 0.37[1] mas/yr
Parallax (π)6.49 ± 0.45[1] mas
Distance500 ± 30 ly
(150 ± 10 pc)
Absolute magnitude (MV)−1.22[6]
Details
Radius54[7] R☉
Luminosity970[8] L☉
Temperature3,825[8] K
Other designations
θ Pyx, CPD−25° 4152, FK5 1243, GC 12916, HD 80874, HIP 45902, HR 3718, SAO 177322, PPM 256035
Database references
SIMBADdata

Theta Pyxidis is moving through the Galaxy at a speed of 22.8 km/s relative to the Sun. Its projected Galactic orbit carries it between 21,200 and 24,700 light years from the center of the Galaxy. It came closest to the Sun 5.8 million years ago when it had brightened to magnitude 3.12 from a distance of 241 light years.

References
  1. van 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
  2. Gutierrez-Moreno, Adelina; et al. (1966), "A System of photometric standards", Publications of the Department of Astronomy University of Chile, Publicaciones Universidad de Chile, Department de Astronomy, 1: 1–17, Bibcode:1966PDAUC...1....1G.
  3. Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS...71..245K. doi:10.1086/191373.
  4. Tabur, V.; Bedding, T.R. (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.
  5. 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.
  6. 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.
  7. Pasinetti Fracassini, L. E.; Pastori, L.; Covino, S.; Pozzi, A. (2001). "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics". Astronomy & Astrophysics. 367 (2): 521–24. arXiv:astro-ph/0012289. Bibcode:2001A&A...367..521P. doi:10.1051/0004-6361:20000451. S2CID 425754.
  8. McDonald, I.; Zijlstra, A. A.; Boyer, M. L. (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.
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