Astronomy:Omega2 Aquarii

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Short description: Star in the constellation Aquarius
For other stars with this Bayer designation, see ω Aquarii.
Omega2 Aquarii
Location of ω2 Aquarii (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Aquarius[1]
Right ascension  23h 42m 43.345s[2]
Declination −14° 32′ 41.66″[2]
Apparent magnitude (V) 4.49[3]
Characteristics
Spectral type B9 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: +98.578[2] mas/yr
Dec.: −66.231[2] mas/yr
Parallax (π)20.8948 ± 0.1589[2] mas
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 equatorial constellation 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. ↑ 1.0 1.1 1.2 1.3 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 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.
  3. ↑ 3.0 3.1 3.2 3.3 Nicolet, 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. ↑ 4.0 4.1 Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode: 1988mcts.book.....H. 
  5. ↑ 5.0 5.1 5.2 Gahm, 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, doi:10.1134/S1063773706110065, Bibcode: 2006AstL...32..759G. 
  7. ↑ 7.0 7.1 7.2 7.3 Gullikson, Kevin et al. (2016), "The Close Companion Mass-ratio Distribution of Intermediate-mass Stars", The Astronomical Journal 152 (2): 40, doi:10.3847/0004-6256/152/2/40, Bibcode: 2016AJ....152...40G. 
  8. ↑ 8.0 8.1 8.2 8.3 8.4 Fitzpatrick, 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, doi:10.1086/427855, Bibcode: 2005AJ....129.1642F. 
  9. ↑ 9.0 9.1 Günther, 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, doi:10.3847/1538-3881/ab5d3a, ISSN 0004-6256, Bibcode: 2020AJ....159...60G. 
  10. ↑ 10.0 10.1 Royer, F. et al. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics 463 (2): 671–682, doi:10.1051/0004-6361:20065224, Bibcode: 2007A&A...463..671R. 
  11. ↑ "105 Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=105+Aqr. 
  12. ↑ 12.0 12.1 Chini, R. et al. (2012), "A spectroscopic survey on the multiplicity of high-mass stars", Monthly Notices of the Royal Astronomical Society 424 (3): 1925, doi:10.1111/j.1365-2966.2012.21317.x, Bibcode: 2012MNRAS.424.1925C. 
  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, doi:10.1086/145697, Bibcode: 1953ApJ...117..313J. 
  14. ↑ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html, 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, doi:10.1086/378164, Bibcode: 2003AJ....126.1996M. 



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