Astronomy:Phi Octantis

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Short description: Star in the constellation Octans
φ Octantis
Octans constellation map.svg
Red circle.svg
Location of Phi Oct on the map (circled)
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Octans
Right ascension  18h 23m 36.44874s[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 (Rv)5.0±4.2[5] km/s
Proper motion (μ) RA: +4.621[1] mas/yr
Dec.: +19.730[1] mas/yr
Parallax (π)16.8258 ± 0.0636[1] mas
Distance193.8 ± 0.7 ly
(59.4 ± 0.2 pc)
Absolute magnitude (MV)+1.60[6]
Details
Mass2.86[7] M☉
Radius1.74±0.08[8] R☉
Luminosity21.1±0.1[1] L☉
Surface gravity (log g)4.48±0.14[7] cgs
Temperature9,352±122[9] K
Metallicity [Fe/H]−0.22[10] dex
Rotational velocity (v sin i)295[11] km/s
Age7[7] Myr
Other designations
φ Oct, CPD−75°1417, GC 24999, HD 167468, HIP 90133, HR 6829, SAO 257584[12]
Database references
SIMBADdata

Phi Octantis, Latinized from φ Octantis, is a solitary star[13] 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

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 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. Bibcode: 2000A&A...355L..27H. 
  3. ↑ 3.0 3.1 Houk, N.; Cowley, A. P. (1975). University of Michigan Catalogue of two-dimensional spectral types for the HD stars: Declinations −90° to −53°. 1. Bibcode: 1975mcts.book.....H. 
  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. Bibcode: 1966CoLPL...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. Bibcode: 2006AstL...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. Bibcode: 2012AstL...38..331A. 
  7. ↑ 7.0 7.1 7.2 7.3 7.4 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. doi:10.1088/0004-637X/804/2/146. ISSN 0004-637X. Bibcode: 2015ApJ...804..146D. 
  8. ↑ 8.0 8.1 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. Bibcode: 1999A&A...352..555A. 
  9. ↑ 9.0 9.1 Stassun, Keivan G. et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal 158 (4): 138. doi:10.3847/1538-3881/ab3467. Bibcode: 2019AJ....158..138S. 
  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. doi:10.1051/0004-6361/201935765. ISSN 0004-6361. Bibcode: 2019A&A...628A..94A. 
  11. ↑ 11.0 11.1 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. doi:10.1086/129336. ISSN 0004-6280. Bibcode: 1972PASP...84..584L. 
  12. ↑ "* phi Oct". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+phi+Oct. 
  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. Bibcode: 2008MNRAS.389..869E. 
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