Omega2 Aquarii
Omega2 Aquarii
Location of ω2 Aquarii (circled)
Observation dataEpoch J2000      Equinox J2000
ConstellationAquarius[1]
Right ascension23h 42m 43.345s[2]
Declination−14° 32′ 41.66″[2]
Apparent magnitude (V)4.49[3]
Characteristics
Spectral typeB9 V[4] + A5V[5]
U−B color index−0.12[3]
B−V color index−0.04[3]
Astrometry
Radial velocity (Rv)+3.2±2.3[6] km/s
Proper motion (μ)RA: +98.578mas/yr[2]Dec.: −66.231mas/yr[2]
Parallax (π)20.8948±0.1589 mas[2]
Distance156 ± 1 ly (47.9 ± 0.4 pc)
Absolute magnitude (MV)+1.20[1]
Details
A
Mass2.6+0.15−0.14[7] M☉
Radius1.94±0.06[8] R☉
Luminosity37[1] L☉
Surface gravity (log g)4.22±0.03[8] cgs
Temperature10,504±91[8] K
Rotation10.6546 h[9]
Rotational velocity (v sin i)148[10] km/s
Age109+90−70[7] Myr
Other designations
ω2 Aqr, 105 Aquarii, BD−15 6476, FK5 894, GC 32931, GJ 9836, HD 222661, HIP 116971, HR 8988, SAO 165842, PPM 242001, WDS J23427-1433A[11]
Database references
SIMBADdata

Omega2 Aquarii is a star[12] system in the equatorialconstellation of Aquarius. Its name is a Bayer designation that is Latinised from ω2 Aquarii, and abbreviated Omega2 Aqr or ω2 Aqr. The system can be seen with the naked eye as a faint point of light, having an apparent visual magnitude of 4.49.[3] The approximate distance to this star, 149 light-years (46 parsecs), is known from parallax measurements.[2]

This is a B-type main-sequence star with a stellar classification of B9 V.[4] In 1953, astronomers H. L. Johnson and W. W. Morgan selected it as the MK standard for stars of class B9.5V.[13] It has an estimated age of 109[7] million years and is spinning rapidly with a projected rotational velocity of 148 km/s,[10] giving it a rotation period of 10.6546 h.[9] The star has 2.6[7] times the Sun's mass and nearly double the radius of the Sun.[8] It is radiating 37[1] times the luminosity of the Sun from its photosphere at an effective temperature of 10,504 K,[8] giving it the blue-white hue of a B-type star.[14]

In 1983, this was catalogued as a spectroscopic binary star system with components classed B9V and B9.5V.[5] However, a 2012 survey by R. Chini et al found the star to have a constant radial velocity.[12] There is a companion star at an angular separation of 5.7 arcseconds that shares a common proper motion with the primary. It is an A-type main-sequence star with a visual magnitude of 9.5.[5] This system is among the 100 strongest stellar X-ray sources within 163 light-years (50 parsecs) of the Sun. It is emitting an X-ray luminosity of 1.2×1030 erg·s−1. The source for this X-ray emission is unknown.[15]

References

  1. ^ abcdAnderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  2. ^ abcdeVallenari, 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.
  3. ^ abcdNicolet, B. (1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System", Astronomy and Astrophysics Supplement Series, 34: 1–49, Bibcode:1978A&AS...34....1N.
  4. ^ abHouk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.
  5. ^ abcGahm, G. F.; et al. (1983), "A study of visual double stars with early type primaries. I. Spectroscopic results", Astronomy and Astrophysics Supplement Series, 51: 143, Bibcode:1983A&AS...51..143G.
  6. ^Gontcharov, G. A. (2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
  7. ^ abcdGullikson, Kevin; et al. (2016), "The Close Companion Mass-ratio Distribution of Intermediate-mass Stars", The Astronomical Journal, 152 (2): 40, arXiv:1604.06456, Bibcode:2016AJ....152...40G, doi:10.3847/0004-6256/152/2/40, S2CID 119179065.
  8. ^ abcdeFitzpatrick, E. L.; Massa, D. (March 2005), "Determining the Physical Properties of the B Stars. II. Calibration of Synthetic Photometry", The Astronomical Journal, 129 (3): 1642–1662, arXiv:astro-ph/0412542, Bibcode:2005AJ....129.1642F, doi:10.1086/427855, S2CID 119512018.
  9. ^ abGünther, Maximilian N.; et al. (January 20, 2020), "Stellar Flares from the First TESS Data Release: Exploring a New Sample of M Dwarfs", The Astronomical Journal, 159 (2): 60, arXiv:1901.00443, Bibcode:2020AJ....159...60G, doi:10.3847/1538-3881/ab5d3a, ISSN 0004-6256.
  10. ^ abRoyer, F.; et al. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224, S2CID 18475298.
  11. ^"105 Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2008-05-16.
  12. ^ abChini, R.; et al. (2012), "A spectroscopic survey on the multiplicity of high-mass stars", Monthly Notices of the Royal Astronomical Society, 424 (3): 1925, arXiv:1205.5238, Bibcode:2012MNRAS.424.1925C, doi:10.1111/j.1365-2966.2012.21317.x, S2CID 119120749.
  13. ^Johnson, H. L.; Morgan, W. W. (May 1953), "Fundamental stellar photometry for standards of spectral type on the Revised System of the Yerkes Spectral Atlas", Astrophysical Journal, 117: 313, Bibcode:1953ApJ...117..313J, doi:10.1086/145697.
  14. ^"The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on March 18, 2012, retrieved 2012-01-16.
  15. ^Makarov, Valeri V. (October 2003), "The 100 Brightest X-Ray Stars within 50 Parsecs of the Sun", The Astronomical Journal, 126 (4): 1996–2008, Bibcode:2003AJ....126.1996M, doi:10.1086/378164.
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