Omega2 Aquarii

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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
Cercle rouge 100%.svg

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
Distance 149 ± 2 ly
(45.5 ± 0.5 pc)
Details
Radius 1.94 ± 0.06[5] R
Surface gravity (log g) 4.22 ± 0.03[5] cgs
Temperature 10,504 ± 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 Aquarii2 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[edit]

  1. ^ a b c d e f 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. ^ a b c d 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. ^ a b 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. ^ a b c d e 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. ^ a b 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. ^ a b 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. 

External links[edit]