Omega2 Aquarii

Omega² Aquarii
	Location of ω2 Aquarii (circled)
Observation data; Epoch J2000 Equinox J2000
Constellation	Aquarius
Right ascension	23h 42m 43.34473s
Declination	−14° 32′ 41.6523″
Apparent magnitude (V)	4.49
Characteristics
Spectral type	B9 V
U−B color index	−0.12
B−V color index	−0.04
Astrometry
Radial velocity (Rv)	+3 km/s
Proper motion (μ)	RA: +99.28 mas/yr ; Dec.: −66.32 mas/yr
Parallax (π)	21.96 ± 0.26 mas
Distance	149 ± 2 ly ; (45.5 ± 0.5 pc)
Absolute magnitude (MV)	+1.20
Details
Radius	1.94 ± 0.06 R☉
Luminosity	37 L☉
Surface gravity (log g)	4.22 ± 0.03 cgs
Temperature	10,504 ± 91 K
Rotational velocity (v sin i)	148 km/s
Other designations
	ω2 Aqr, 105 Aquarii, BD–15 6476, FK5 894, GJ 9836, HD 222661, HIP 116971, HR 8988, SAO 165842
Database references
SIMBAD	data

Omega² Aquarii, Latinised from ω² Aquarii, is the Bayer designation for a triple star^[9] 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^[6] and is spinning rapidly with a projected rotational velocity of 148 km/s.^[7] The outer atmosphere has an effective temperature of 10,504 K,^[6] giving it the blue-white hue of a B-type star.^[10]

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.^[9] 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.^[11]

References

^ ^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, S2CID 18759600.
^ ^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.
^ ^a ^b Houk, 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.
^ Wilson, Ralph Elmer (1953), "General Catalogue of Stellar Radial Velocities", Carnegie Institute Washington D.C. Publication, Washington: Carnegie Institution of Washington, Bibcode:1953GCRV..C......0W.
^ ^a ^b Anderson, 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.
^ ^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, S2CID 119512018.
^ ^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, S2CID 18475298.
^ "105 Aqr -- Star in double system", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2008-05-16.
^ ^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, S2CID 14878976.
^ "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.
^ 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

Image Omega2 Aquarii

[aaa474_2_653-1] ^ ^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, S2CID 18759600.

[aass34_1-2] 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.

[houk1978-3] Houk, 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.

[gcsrv-4] Wilson, Ralph Elmer (1953), "General Catalogue of Stellar Radial Velocities", Carnegie Institute Washington D.C. Publication, Washington: Carnegie Institution of Washington, Bibcode:1953GCRV..C......0W.

[Anderson2012-5] Anderson, 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.

[aj129_3_1642-6] 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, S2CID 119512018.

[aaa463_2_671-7] 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, S2CID 18475298.

[SIMBAD-8] "105 Aqr -- Star in double system", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2008-05-16.

[mnras389_2_869-9] 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, S2CID 14878976.

[csiro-10] "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.

[aj126_4_1996-11] 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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Omega2 Aquarii

References

External links

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