Gamma2 Octantis

γ² Octantis
Observation data; Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Octans
Right ascension	23h 57m 32.8617s
Declination	−82° 10′ 11.310″
Apparent magnitude (V)	5.72±0.01
Characteristics
Evolutionary stage	red clump
Spectral type	K0 III
U−B color index	+0.92
B−V color index	+1.05
Astrometry
Radial velocity (Rv)	27.2±2.9 km/s
Proper motion (μ)	RA: −22.246 mas/yr ; Dec.: −23.235 mas/yr
Parallax (π)	10.1771±0.0345 mas
Distance	320 ± 1 ly ; (98.3 ± 0.3 pc)
Absolute magnitude (MV)	+0.87
Details
Mass	1.15±0.15 M☉
Radius	10.54±0.28 R☉
Luminosity	52.6±1.3 L☉
Surface gravity (log g)	2.53±0.13 cgs
Temperature	4,788±58 K
Metallicity [Fe/H]	−0.04±0.04 dex
Rotational velocity (v sin i)	2.8±1.1 km/s
Other designations
	γ2 Oct, 87 G. Octantis, CPD−82°907, HD 224362, HIP 118114, HR 9061, SAO 258996
Database references
SIMBAD	data

γ² Octantis, Latinized to Gamma² Octantis (Gamma² Oct), is a solitary^[12] star in the southern circumpolar constellation Octans. It has an apparent magnitude of 5.72,^[2] allowing it to be faintly seen with the naked eye. Parallax measurements place the object at a distance of 320 light years^[1] and is currently receding with a heliocentric radial velocity of 27 km/s.^[6]

Gamma² Oct has a stellar classification of K0 III,^[4] indicating that it is a red giant. At present it has 115% the mass of the Sun but has expanded to 10.54 times its girth.^[8] It shines at 52.6 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,788 K,^[8] giving it a yellow-orange glow. Gamma² Oct has a metallicity around 91% that of the Sun^[8] and spins with a projected rotational velocity of about 3 km/s.^[9]

References

^ ^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.
^ ^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.
^ Gontcharov, G. A. (2009). "Red giant clump in the Tycho-2 catalogue". Astronomy Letters. 34 (11): 785–796. arXiv:1607.00619. Bibcode:2008AstL...34..785G. doi:10.1134/S1063773708110078. S2CID 73524157.
^ ^a ^b Houk, N.; Cowley, A. P. (1975). University of Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume I. Bibcode:1975mcts.book.....H.
^ ^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.
^ ^a ^b 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. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. ISSN 1063-7737. S2CID 119231169.
^ 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 255204555.
^ ^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. (2022). "CORALIE radial-velocity search for companions around evolved stars (CASCADES). I. Sample definition and first results: Three new planets orbiting giant stars". Astronomy and Astrophysics. 657: A87. arXiv:2201.01528. Bibcode:2022A&A...657A..87O. doi:10.1051/0004-6361/202040078.
^ ^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.
^ "HD 46568". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 7 June 2022.
^ 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.
^ 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.

[EDR3-1] 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.

[Tycho2000-2] 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.

[Gontcharov2008-3] Gontcharov, G. A. (2009). "Red giant clump in the Tycho-2 catalogue". Astronomy Letters. 34 (11): 785–796. arXiv:1607.00619. Bibcode:2008AstL...34..785G. doi:10.1134/S1063773708110078. S2CID 73524157.

[Houk1975-4] Houk, N.; Cowley, A. P. (1975). University of Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume I. Bibcode:1975mcts.book.....H.

[Johnson1966-5] 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.

[Gontcharov2006-6] 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. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. ISSN 1063-7737. S2CID 119231169.

[Anderson2012-7] 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 255204555.

[Ottoni2022-8] 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. (2022). "CORALIE radial-velocity search for companions around evolved stars (CASCADES). I. Sample definition and first results: Three new planets orbiting giant stars". Astronomy and Astrophysics. 657: A87. arXiv:2201.01528. Bibcode:2022A&A...657A..87O. doi:10.1051/0004-6361/202040078.

[DeMederios2014-9] 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.

[SIMBAD-10] "HD 46568". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 7 June 2022.

[Gould1879-11] 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.

[Eggleton2008-12] 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.

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Observation data Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Octans
Right ascension	23^h 57^m 32.8617^s^[1]
Declination	−82° 10′ 11.310″^[1]
Apparent magnitude (V)	5.72±0.01^[2]
Characteristics
Evolutionary stage	red clump^[3]
Spectral type	K0 III^[4]
U−B color index	+0.92^[5]
B−V color index	+1.05^[5]
Astrometry

Radial velocity (R_v)	27.2±2.9^[6] km/s
Proper motion (μ)	RA: −22.246 mas/yr^[1] Dec.: −23.235 mas/yr^[1]
Parallax (π)	10.1771±0.0345 mas^[1]
Distance	320 ± 1 ly (98.3 ± 0.3 pc)
Absolute magnitude (M_V)	+0.87^[7]

Details^[8]

Mass	1.15±0.15 `M`_☉
Radius	10.54±0.28 `R`_☉
Luminosity	52.6±1.3 `L`_☉
Surface gravity (log g)	2.53±0.13 cgs
Temperature	4,788±58 K
Metallicity [Fe/H]	−0.04±0.04 dex
Rotational velocity (v sin i)	2.8±1.1^[9] km/s

Other designations
γ² Oct, 87 G. Octantis, CPD−82°907, HD 224362, HIP 118114, HR 9061, SAO 258996^[10]^[11]
Database references
SIMBAD	data

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