Upsilon Octantis

υ Octantis

Location of υ Octantis (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Octans
Right ascension	22^h 31^m 37.5152^s[1]
Declination	−85° 58′ 02.1104″[1]
Apparent magnitude (V)	5.75±0.01[2]
Characteristics
Spectral type	K0 III[3]
U−B color index	+0.88[4]
B−V color index	+1.02[4]
Astrometry
Radial velocity (Rv)	19±7.8[5] km/s
Proper motion (μ)	RA: −37.556 mas/yr[1] Dec.: +61.431 mas/yr[1]
Parallax (π)	9.5042 ± 0.0351 mas[1]
Distance	343 ± 1 ly (105.2 ± 0.4 pc)
Absolute magnitude (MV)	+0.77[6]
Details[7]
Mass	2.12±0.07 M☉
Radius	10.3±0.2 R☉
Luminosity	56±1.1 L☉
Surface gravity (log g)	2.7±0.1 cgs
Temperature	4,910±42 K
Metallicity [Fe/H]	0.00±0.03 dex
Rotational velocity (v sin i)	1.5±1.3[8] km/s
Other designations
υ Oct, 71 G. Octantis[9], CPD−86°406, FK5 1670, GC 31327, HD 211539, HIP 111196, HR 8505, SAO 258932[10]
Database references
SIMBAD	data

Upsilon Octantis (Upsilon Oct), Latinized from υ Octantis, is a solitary star[11] in the southern circumpolar constellation Octans. It is faintly visible to the naked eye with an apparent magnitude of 5.75[2] and is located 343 light years away from the Solar System.[1] However, it is receding with a heliocentric radial velocity of 19 km/s.[5]

Upsilon Oct has a stellar classification of K0 III,[3] indicating that it is a red giant. At present it has 2.12 times the mass of the Sun but has expanded to 10.3 times its girth.[7] It shines with a luminosity of 56 L_☉ from its enlarged photosphere at an effective temperature of 4,910 K,[7] giving a yellowish orange hue when viewed at night. Upsilon Oct has a solar metallicity, with an iron abundance equivalent to the Sun's.[7] It spins leisurely with a poorly-constrained projected rotational velocity of 1.5 km/s.[8]

References

1. Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
2. Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27 – L30. Bibcode:2000A&A...355L..27H. ISSN 0004-6361.
3. Houk, N.; Cowley, A. P. (1975). University of Michigan Catalogue of two-dimensional spectral types for the HD stars. Volume I. Declinations -90_ to -53_ƒ0. Bibcode:1975mcts.book.....H.
4. 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. Bibcode:1966CoLPL...4...99J.
5. Kharchenko, N.V.; Scholz, R.-D.; Piskunov, A.E.; Röser, S.; Schilbach, E. (November 2007). "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations". Astronomische Nachrichten. 328 (9): 889–896. arXiv:0705.0878. Bibcode:2007AN....328..889K. doi:10.1002/asna.200710776. ISSN 0004-6337.
6. Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. ISSN 1063-7737. S2CID 119257644.
7. Ottoni, G.; Udry, S.; Ségransan, D.; Buldgen, G.; Lovis, C.; Eggenberger, P.; Pezzotti, C.; Adibekyan, V.; Marmier, M.; Mayor, M.; Santos, N. C.; Sousa, S. G.; Lagarde, N.; Charbonnel, C. (January 2022). "CORALIE radial-velocity search for companions around evolved stars (CASCADES): I. Sample definition and first results: Three new planets orbiting giant stars". Astronomy & Astrophysics. 657: A87. arXiv:2201.01528. Bibcode:2022A&A...657A..87O. doi:10.1051/0004-6361/202040078. ISSN 0004-6361.
8. 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. arXiv:1312.3474. Bibcode:2014A&A...561A.126D. doi:10.1051/0004-6361/201220762. ISSN 0004-6361.
9. Gould, Benjamin Apthorp (1878). "Uranometria Argentina : brillantez y posicion de las estrellas fijas, hasta la septima magnitud, comprendidas dentro de cien grados del polo austral : con atlas". Resultados del Observatorio Nacional Argentino. 1. Bibcode:1879RNAO....1.....G.
10. "ups Oct". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved July 1, 2022.
11. 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. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. eISSN 1365-2966. ISSN 0035-8711.