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Omicron Aquarii

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(Redirected from Kae Uh) Variable B-type star in the constellation Aquarius
Omicron Aquarii
Location of ο Aquarii (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius
Right ascension 22 03 18.84403
Declination –02° 09′ 19.3067″
Apparent magnitude (V) +4.71
Characteristics
Spectral type B7 IVe
U−B color index –0.39
B−V color index –0.11
Variable type γ Cas
Astrometry
Radial velocity (Rv)+11.0 km/s
Proper motion (μ) RA: +24.66 mas/yr
Dec.: –11.16 mas/yr
Parallax (π)7.49 ± 0.23 mas
Distance440 ± 10 ly
(134 ± 4 pc)
Absolute magnitude (MV)−0.89
Details
Mass4.2 M☉
Radius4.0±0.3 R☉
Luminosity340 L☉
Surface gravity (log g)3.13 cgs
Temperature13,464±164 K
Metallicity −0.16 dex
Rotational velocity (v sin i)282±20 km/s
Other designations
ο Aqr, 31 Aquarii, BD–02 5681, FK5 3765, HD 209409, HIP 108874, HR 8402, SAO 145837
Database references
SIMBADdata

Omicron Aquarii, Latinized from ο Aquarii, is the Bayer designation for a variable star in the equatorial constellation of Aquarius. Visible to the naked eye, it has an apparent visual magnitude of +4.71. Parallax measurements put it at a distance of roughly 440 light-years (130 parsecs) from Earth. It is drifting further away with a radial velocity of +11 km/s. The star is a candidate member of the Pisces-Eridanus stellar stream.

It has the traditional star name Kae Uh, from the Chinese 蓋屋 (Mandarin pronunciation Gài Wū). In Chinese astronomy, 蓋屋 is the rooftop, an asterism consisting of ο Aquarii and 32 Aquarii. Consequently, the Chinese name for ο Aquarii itself is 蓋屋一 (Gài Wū yī, English: the First Star of Roofing.)

A light curve for Omicron Aquarii, plotted from TESS data

The spectrum of Omicron Aquarii fits a stellar classification of B7 IVe; the luminosity class of IV suggests that this is a subgiant star that is exhausting the supply of hydrogen at its core and is in the process of evolving into a giant star. The 'e' suffix on the class indicates that the spectrum shows emission lines of hydrogen, thus categorizing this as a Be star. It is rotating rapidly with an equatorial rotational velocity of 368 km/s, which is ~96% of the star's critical rotation velocity of 391 km/s. The emission lines are being generated by a decreted circumstellar disk of hot hydrogen gas. This disk has been globally stable for at least twenty years, as of 2020. It is likely a single star, with no stellar companions.

Omicron Aquarii has 4.2 times the mass of the Sun, four times the Sun's radius, and is radiating 340 times the luminosity of the Sun from its photosphere at an effective temperature of 13,464 K. It is classified as a Gamma Cassiopeiae type variable star and its brightness varies from magnitude +4.68 down to +4.89.

References

  1. ^ 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.
  2. ^ Feinstein, A.; Marraco, H. G. (November 1979), "The photometric behavior of Be Stars", Astronomical Journal, 84: 1713–1725, Bibcode:1979AJ.....84.1713F, doi:10.1086/112600.
  3. ^ Lesh, Janet Rountree (December 1968). "The Kinematics of the Gould Belt: an Expanding Group?". Astrophysical Journal Supplement. 17: 371. Bibcode:1968ApJS...17..371L. doi:10.1086/190179.
  4. ^ "omi Aqr", General Catalogue of Variable Stars, Sternberg Astronomical Institute, retrieved 2012-07-03. Note: type = GCAS.
  5. ^ Wielen, R.; et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veroeffentlichungen des Astronomischen Rechen-Instituts Heidelberg, 35 (35), Astronomisches Rechen-Institut Heidelberg: 1, Bibcode:1999VeARI..35....1W.
  6. ^ 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.
  7. ^ de Almeida, E. S. G.; et al. (April 2020), "Visible and near-infrared spectro-interferometric analysis of the edge-on Be star o Aquarii", Astronomy & Astrophysics, 636: 23, arXiv:2002.09552, Bibcode:2020A&A...636A.110D, doi:10.1051/0004-6361/201936039, S2CID 211258993, A110
  8. Soubiran, C.; Le Campion, J.-F.; Cayrel de Strobel, G.; Caillo, A. (June 2010), "The PASTEL catalogue of stellar parameters", Astronomy and Astrophysics, 515: A111, arXiv:1004.1069, Bibcode:2010A&A...515A.111S, doi:10.1051/0004-6361/201014247, S2CID 118362423.
  9. ^ Underhill, A. B.; et al. (November 1979), "Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars", Monthly Notices of the Royal Astronomical Society, 189 (3): 601–605, Bibcode:1979MNRAS.189..601U, doi:10.1093/mnras/189.3.601.
  10. ^ Meilland, A.; Millour, F.; Kanaan, S.; Stee, Ph.; Petrov, R.; Hofmann, K.-H.; Natta, A.; Perraut, K. (February 2012), "First spectro-interferometric survey of Be stars. I. Observations and constraints on the disk geometry and kinematics", Astronomy & Astrophysics, 538: A110, arXiv:1111.2487, Bibcode:2012A&A...538A.110M, doi:10.1051/0004-6361/201117955, S2CID 64777633.
  11. "omi Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-03.
  12. Curtis, Jason L.; et al. (August 2019), "TESS Reveals that the Nearby Pisces-Eridanus Stellar Stream is only 120 Myr Old", The Astronomical Journal, 158 (2): 11, arXiv:1905.10588, Bibcode:2019AJ....158...77C, doi:10.3847/1538-3881/ab2899, S2CID 166228270, 77.
  13. Allen, R. H. (1963), Star Names: Their Lore and Meaning (Reprint ed.), New York: Dover Publications Inc, p. 53, ISBN 0-486-21079-0, retrieved 2010-12-12.
  14. (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  15. (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 16 日 Archived 2011-05-22 at the Wayback Machine
  16. "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
  17. Hutter, D. J.; Tycner, C.; Zavala, R. T.; Benson, J. A.; Hummel, C. A.; Zirm, H. (2021). "Surveying the Bright Stars by Optical Interferometry. III. A Magnitude-limited Multiplicity Survey of Classical Be Stars". The Astrophysical Journal Supplement Series. 257 (2): 69. arXiv:2109.06839. Bibcode:2021ApJS..257...69H. doi:10.3847/1538-4365/ac23cb. S2CID 237503492.
  18. Ruban, E. V.; et al. (September 2006), "Spectrophotometric observations of variable stars", Astronomy Letters, 32 (9): 604–607, Bibcode:2006AstL...32..604R, doi:10.1134/S1063773706090052, S2CID 121747360.

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