Omega2 Aquarii

For other star systems with this Bayer designation, see Omega Aquarii.
Omega2 Aquarii
Diagram showing star positions and boundaries of the Aquarius constellation and its surroundings


Location of ω2 Aquarii (circled)

Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius
Right ascension 23h 42m 43.34473s[1]
Declination –14° 32′ 41.6523″[1]
Apparent magnitude (V) 4.49[2]
Characteristics
Spectral type B9 V[3]
U−B color index –0.12[2]
B−V color index –0.04[2]
Astrometry
Radial velocity (Rv)+3[4] km/s
Proper motion (μ) RA: +99.28[1] mas/yr
Dec.: –66.32[1] mas/yr
Parallax (π)21.96 ± 0.26[1] mas
Distance149 ± 2 ly
(45.5 ± 0.5 pc)
Details
Radius1.94 ± 0.06[5] R☉
Surface gravity (log g)4.22 ± 0.03[5] cgs
Temperature10,504 ± 91[5] K
Rotational velocity (v sin i)148[6] km/s
Other designations
105 Aquarii, BD–15 6476, FK5 894, GJ 9836, HD 222661, HIP 116971, HR 8988, SAO 165842.[7]

Omega2 Aquarii (ω2 Aqr, ω2 Aquarii) is the Bayer designation for a triple star[8] system in the equatorial constellation of Aquarius. It can be seen with the naked eye, having an apparent visual magnitude of 4.49.[2] The approximate distance to this star, 149 light-years (46 parsecs), is known from parallax measurements taken during the Hipparcos mission.[1]

The primary component of this system is a massive, B-type main sequence star with a stellar classification of B9 V.[3] This star has nearly double the radius of the Sun[5] and is spinning rapidly with a projected rotational velocity of 148 km/s.[6] The outer atmosphere has an effective temperature of 10,504 K,[5] giving it the blue-white hue of a B-type star.[9]

There is a close orbiting stellar companion of unknown type, with a third component at an angular separation of 5.7 arcseconds. The latter is a K-type main sequence star with a visual magnitude of 9.5.[8] This system is among the 100 strongest stellar X-ray sources within 163 light-years (50 pc) of the Sun. It is emitting an X-ray luminosity of 1.2 × 1030 erg s−1.[10]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. ↑ 2.0 2.1 2.2 2.3 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.
  3. ↑ 3.0 3.1 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.
  4. ↑ Wilson, Ralph Elmer (1953), General Catalogue of Stellar Radial Velocities, Washington: Carnegie Institution of Washington, Bibcode:1953QB901.W495......
  5. ↑ 5.0 5.1 5.2 5.3 5.4 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, arXiv:astro-ph/0412542, Bibcode:2005AJ....129.1642F, doi:10.1086/427855.
  6. ↑ 6.0 6.1 Royer, F.; Zorec, J.; Gómez, A. E. (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.
  7. ↑ "105 Aqr -- Star in double system", SIMBAD (Centre de Données astronomiques de Strasbourg), retrieved 2008-05-16.
  8. ↑ 8.0 8.1 Eggleton, P. P.; Tokovinin, A. A. (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.
  9. ↑ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, retrieved 2012-01-16.
  10. ↑ 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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