Astronomy:Chi Octantis

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Short description: Star in the constellation Octans
χ Octantis
Octans IAU.svg
Red circle.svg
Location of χ Oct (circled)
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Octans
Right ascension  18h 54m 47.14062s[1]
Declination −87° 36′ 21.0359″[1]
Apparent magnitude (V) 5.28±0.01[2]
Characteristics
Spectral type K3 III[3]
U−B color index +1.60[4]
B−V color index +1.28[4]
Astrometry
Radial velocity (Rv)33.6±3.1[5] km/s
Proper motion (μ) RA: −36.555[1] mas/yr
Dec.: −135.715[1] mas/yr
Parallax (π)12.5114 ± 0.0730[1] mas
Distance261 ± 2 ly
(79.9 ± 0.5 pc)
Absolute magnitude (MV)+0.81[6]
Details
Mass1.25±0.33[7] M
Radius15.6±0.8[8] R
Luminosity73.6±0.7[9] L
Surface gravity (log g)2.19[10] cgs
Temperature4,266+99−97[7] K
Metallicity [Fe/H]+0.10[10] dex
Rotational velocity (v sin i)<1[11] km/s
Other designations
χ Oct, CD−87°92, CPD−87°274, FK5 922, GC 25207, HD 164461, HIP 92824, HR 6721, SAO 258799[12]
Database references
SIMBADdata

Chi Octantis, Latinized from χ Octantis, is a solitary star[13] located in the southern circumpolar constellation Octans. It is faintly visible to the naked eye as an orange-hued star with an apparent magnitude of 5.28.[2] The object is located relatively close at a distance of 261 light years based on Gaia EDR3 parallax measurements,[1] but it is receding with a heliocentric radial velocity 33.6 km/s.[5] At its current distance, Chi Octantis' brightness is diminished by 0.24 magnitudes due to interstellar dust.[14] It has an absolute magnitude of +0.81.[6]

Chi Octantis is an evolved red giant with a stellar classification of K3 III.[3] It has 125% the mass of the Sun and an enlarged radius of 14.45 R due to its evolved state.[7] It radiates 73.6 times the luminosity of the Sun[9] from its photosphere at an effective temperature of 4,266 K.[7] Chi Octantis is metal enriched with an iron abundance 126% that of the Sun ([Fe/H] = +0.10)[10] and spins slowly with a projected rotational velocity less than 1 km/s−1.[11]

References

  1. 1.0 1.1 1.2 1.3 1.4 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode2021A&A...649A...1G.  Gaia EDR3 record for this source at VizieR.
  2. 2.0 2.1 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27–L30. ISSN 0004-6361. Bibcode2000A&A...355L..27H. 
  3. 3.0 3.1 Keenan, Philip C.; McNeil, Raymond C. (October 1989). "The Perkins catalog of revised MK types for the cooler stars". The Astrophysical Journal Supplement Series 71: 245. doi:10.1086/191373. ISSN 0067-0049. Bibcode1989ApJS...71..245K. 
  4. 4.0 4.1 Johnson, H. L.; Mitchell, R. I.; Iriarte, B.; Wisniewski, W. Z. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory 4: 99–110. Bibcode1966CoLPL...4...99J. 
  5. 5.0 5.1 Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters 32 (11): 759–771. doi:10.1134/S1063773706110065. ISSN 1063-7737. Bibcode2006AstL...32..759G. 
  6. 6.0 6.1 Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation" (in en). Astronomy Letters 38 (5): 331–346. doi:10.1134/S1063773712050015. ISSN 1063-7737. Bibcode2012AstL...38..331A. 
  7. 7.0 7.1 7.2 7.3 Allende Prieto, C.; Lambert, D. L. (December 1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: masses, radii and effective temperatures". Astronomy and Astrophysics 352: 555–562. ISSN 0004-6361. Bibcode1999A&A...352..555A. 
  8. Kervella, P.; Thévenin, F.; Di Folco, E.; Ségransan, D. (October 2004). "The angular sizes of dwarf stars and subgiants". Astronomy & Astrophysics 426 (1): 297–307. doi:10.1051/0004-6361:20035930. ISSN 0004-6361. Bibcode2004A&A...426..297K. 
  9. 9.0 9.1 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  10. 10.0 10.1 10.2 Anders, F.; Khalatyan, A.; Chiappini, C.; Queiroz, A. B.; Santiago, B. X.; Jordi, C.; Girardi, L.; Brown, A. G. A. et al. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics 628: A94. doi:10.1051/0004-6361/201935765. ISSN 0004-6361. Bibcode2019A&A...628A..94A. 
  11. 11.0 11.1 De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (January 2014). "A catalog of rotational and radial velocities for evolved stars: V. Southern stars⋆⋆⋆". Astronomy & Astrophysics 561: A126. doi:10.1051/0004-6361/201220762. ISSN 0004-6361. Bibcode2014A&A...561A.126D. 
  12. "chi Octantis". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=chi+Octantis. 
  13. Eggleton, P. P.; Tokovinin, A. A. (11 September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society 389 (2): 869–879. doi:10.1111/j.1365-2966.2008.13596.x. ISSN 0035-8711. Bibcode2008MNRAS.389..869E. 
  14. Gontcharov, George A.; Mosenkov, Aleksandr V. (28 September 2017). "Verifying reddening and extinction for Gaia DR1 TGAS main sequence stars". Monthly Notices of the Royal Astronomical Society 472 (4): 3805–3820. doi:10.1093/mnras/stx2219. ISSN 0035-8711. Bibcode2017MNRAS.472.3805G. 
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