Phi Octantis

φ Octantis
	Location of Phi Oct on the map (circled)
Observation data; Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Octans
Right ascension	18h 23m 36.44874s
Declination	−75° 02′ 39.3975″
Apparent magnitude (V)	5.46±0.01
Characteristics
Spectral type	A0 V
U−B color index	+0.04
B−V color index	+0.02
Astrometry
Radial velocity (Rv)	5.0±4.2 km/s
Proper motion (μ)	RA: +4.621 mas/yr ; Dec.: +19.730 mas/yr
Parallax (π)	16.8258±0.0636 mas
Distance	193.8 ± 0.7 ly ; (59.4 ± 0.2 pc)
Absolute magnitude (MV)	+1.60
Details
Mass	2.86 M☉
Radius	1.74±0.08 R☉
Luminosity	21.1±0.1 L☉
Surface gravity (log g)	4.48±0.14 cgs
Temperature	9,352±122 K
Metallicity [Fe/H]	−0.22 dex
Rotational velocity (v sin i)	295 km/s
Age	7 Myr
Other designations
	φ Oct, 33 G. Octantis[12], CPD−75°1417, GC 24999, HD 167468, HIP 90133, HR 6829, SAO 257584
Database references
SIMBAD	data

Phi Octantis, Latinized from φ Octantis, is a solitary star^[14] located in the southern circumpolar constellation Octans. It has an apparent magnitude of 5.46,^[2] making it faintly visible to the naked eye if viewed under ideal conditions. The object is located relatively close at a distance of 194 light years based on Gaia DR3 parallax measurements,^[1] but it is receding with a heliocentric radial velocity of approximately 5 km/s.^[5] At its current distance, Phi Octantis' brightness is diminished by 0.26 magnitudes due to interstellar extinction and it has an absolute magnitude of +1.60.^[6]

Phi Octantis has a stellar classification of A0 V,^[3] indicating that it is an ordinary A-type main-sequence star that is generating energy via hydrogen fusion at is core. At present it has 2.7 times the mass of the Sun^[7] and 1.74 times the radius of the Sun.^[8] It radiates at 21.1 times the luminosity of the Sun^[1] from its photosphere at an effective temperature of 9,352 K,^[9] giving it a white hue when viewed in the night sky. Phi Octantis is a relatively young star with an age of only 7 million years^[7] and it spins rapidly with a projected rotational velocity of 295 km/s.^[11] It has a metallicity only 60% of the Sun's at [Fe/H] = −0.22.

References

^ ^a ^b ^c ^d ^e ^f ^g Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 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. S2CID 17128864.
^ ^a ^b Houk, N.; Cowley, A. P. (1975). University of Michigan Catalogue of two-dimensional spectral types for the HD stars: Declinations −90° to −53°. Vol. 1. 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. eISSN 1562-6873. ISSN 1063-7737. S2CID 119231169.
^ ^a ^b 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 ^e David, Trevor J.; Hillenbrand, Lynne A. (12 May 2015). "The Ages of Early-type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146. ISSN 0004-637X.
^ ^a ^b 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. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A. ISSN 0004-6361.
^ ^a ^b Stassun, Keivan G.; et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467. eISSN 1538-3881. hdl:1721.1/124721. S2CID 166227927.
^ Anders, F.; et al. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics. 628: A94. arXiv:1904.11302. Bibcode:2019A&A...628A..94A. doi:10.1051/0004-6361/201935765. eISSN 1432-0746. ISSN 0004-6361. S2CID 131780028.
^ ^a ^b Levato, O. H. (August 1972). "Rotational Velocities and Spectral Types of Some A-Type Stars". Publications of the Astronomical Society of the Pacific. 84: 584. Bibcode:1972PASP...84..584L. doi:10.1086/129336. eISSN 1538-3873. ISSN 0004-6280. S2CID 122833746.
^ 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.
^ "* phi Oct". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved April 2, 2022.
^ 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. S2CID 14878976.

[GaiaDR3-1] ^ ^a ^b ^c ^d ^e ^f ^g Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 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. S2CID 17128864.

[Houk1975-3] Houk, N.; Cowley, A. P. (1975). University of Michigan Catalogue of two-dimensional spectral types for the HD stars: Declinations −90° to −53°. Vol. 1. Bibcode:1975mcts.book.....H.

[Johnson1966-4] 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.

[Gontcharov2006-5] 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. eISSN 1562-6873. ISSN 1063-7737. S2CID 119231169.

[Anderson2012-6] 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 255204555.

[David2015-7] David, Trevor J.; Hillenbrand, Lynne A. (12 May 2015). "The Ages of Early-type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146. ISSN 0004-637X.

[A.P1999-8] 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. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A. ISSN 0004-6361.

[Stassun2019-9] Stassun, Keivan G.; et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467. eISSN 1538-3881. hdl:1721.1/124721. S2CID 166227927.

[starhorse-10] Anders, F.; et al. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics. 628: A94. arXiv:1904.11302. Bibcode:2019A&A...628A..94A. doi:10.1051/0004-6361/201935765. eISSN 1432-0746. ISSN 0004-6361. S2CID 131780028.

[Levato1972-11] Levato, O. H. (August 1972). "Rotational Velocities and Spectral Types of Some A-Type Stars". Publications of the Astronomical Society of the Pacific. 84: 584. Bibcode:1972PASP...84..584L. doi:10.1086/129336. eISSN 1538-3873. ISSN 0004-6280. S2CID 122833746.

[Gould1879-12] 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.

[SIMBAD-13] "* phi Oct". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved April 2, 2022.

[Eggleton2008-14] 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. S2CID 14878976.

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Observation data Epoch J2000.0 Equinox J2000.0 (ICRS)
Location of Phi Oct on the map (circled)
Constellation	Octans
Right ascension	18^h 23^m 36.44874^s^[1]
Declination	−75° 02′ 39.3975″^[1]
Apparent magnitude (V)	5.46±0.01^[2]
Characteristics
Spectral type	A0 V^[3]
U−B color index	+0.04^[4]
B−V color index	+0.02^[4]
Astrometry

Radial velocity (R_v)	5.0±4.2^[5] km/s
Proper motion (μ)	RA: +4.621 mas/yr^[1] Dec.: +19.730 mas/yr^[1]
Parallax (π)	16.8258±0.0636 mas^[1]
Distance	193.8 ± 0.7 ly (59.4 ± 0.2 pc)
Absolute magnitude (M_V)	+1.60^[6]

Details

Mass	2.86^[7] `M`_☉
Radius	1.74±0.08^[8] `R`_☉
Luminosity	21.1±0.1^[1] `L`_☉
Surface gravity (log g)	4.48±0.14^[7] cgs
Temperature	9,352±122^[9] K
Metallicity [Fe/H]	−0.22^[10] dex
Rotational velocity (v sin i)	295^[11] km/s
Age	7^[7] Myr

Other designations
φ Oct, 33 G. Octantis [12], CPD−75°1417, GC 24999, HD 167468, HIP 90133, HR 6829, SAO 257584^[13]
Database references
SIMBAD	data

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