Upsilon Octantis

Upsilon Octantis (Upsilon Oct), Latinized from υ Octantis, is a solitary star in the southern circumpolar constellation Octans. It is faintly visible to the naked eye with an apparent magnitude of 5.75 and is located 343 light years away from the Solar System. However, it is receding with a heliocentric radial velocity of 19 km/s. Upsilon Oct has a stellar classification of K0 III, 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. It shines with a luminosity of 56 L☉ from its enlarged photosphere at an effective temperature of 4,910 K, giving a yellowish orange hue when viewed at night. Upsilon Oct has a solar metallicity, with an iron abundance equivalent to the Sun's. It spins leisurely with a poorly-constrained projected rotational velocity of 1.5 km/s.

Star in the constellation of Octans

υ Octantis

Location of υ Octantis (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Octans
Right ascension	22h 31m 37.5152s[1]
Declination	−85° 58′ 02.110″[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

[edit]

1. ^ ^{a b c d e} 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. ^ ^{a b} 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. ^ ^{a b} 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. ^ ^{a b} 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. ^ ^{a b} 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. ^ ^{a b c d} 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. ^ ^{a b} 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.