Omicron Aquarii

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Template:Short description

Omicron Aquarii
Template:Location mark
Location of ο Aquarii (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius[1]
Right ascension Template:RA[2]
Declination Template:DEC[2]
Apparent magnitude (V) +4.71[3]
Characteristics
Spectral type B7 IVe[4]
U−B Template:Engvar −0.39[3]
B−V Template:Engvar −0.11[3]
Variable type γ Cas[5]
Astrometry
Radial velocity (Rv)+11.0[6] km/s
Proper motion (μ) RA: +24.593 mas/yr[2]
Dec.: −11.720 mas/yr[2]
Parallax (π)6.9984±0.1424 mas[2]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)−0.89[1]
Details
Mass4.2[7] Template:Solar mass
Radius4.0±0.3[7] Template:Solar radius
Luminosity340[1] Template:Solar luminosity
Surface gravity (log g)3.13[8] cgs
TemperatureScript error: No such module "val".[9] K
Metallicity [Fe/H]−0.16[1] dex
Rotational velocity (v sin i)211±26[9] km/s
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist[10]
Database references
SIMBADdata

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Omicron Aquarii is a variable star in the equatorial constellation of Aquarius. Its name is a Bayer designation that is Latinized from ο Aquarii, and abbreviated Omicron Aqr or ο Aqr. Visible to the naked eye, it has an apparent visual magnitude of +4.71.[3] Parallax measurements put it at a distance of roughly Script error: No such module "convert". from Earth.[2] It is drifting further away with a radial velocity of +11 km/s.[6] The star is a candidate member of the Pisces-Eridanus stellar stream of co-moving stars.[11]

It has the traditional star name Kae Uh, from the Chinese Script error: No such module "Lang". (Mandarin pronunciation Script error: No such module "Lang".).[12] In Chinese astronomy, Script error: No such module "Lang". is the rooftop, an asterism consisting of ο Aquarii and 32 Aquarii.[13] Consequently, the Chinese name for ο Aquarii itself is Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx.)[14]

Properties

File:OmicronAqrLightCurve.png
A light curve for Omicron Aquarii, plotted from TESS data[15]

The spectrum of Omicron Aquarii fits a stellar classification of B7 IVe;[4] 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.

Omicron Aquarii has 4.2 times the mass of the Sun and four[7] times the Sun's radius. It is radiating 340[1] times the luminosity of the Sun from its photosphere at an effective temperature of 11,145 K.[9] This is classified as a Gamma Cassiopeiae type[5] variable star and its brightness varies from magnitude +4.68 down to +4.89.[16] It is likely a single star, with no stellar companions.[17]

This star is spinning rapidly with an equatorial rotational velocity of 368 km/s, which is ~96% of the star's critical rotation velocity of 391 km/s.[7] This is creating an equatorial bulge with a radius of Script error: No such module "val". compared to a polar radius of Script error: No such module "val".. As a result, the polar temperature Script error: No such module "val".; higher than the equator.[9]

The emission lines are being generated by a Template:Not a typo circumstellar disk of hot hydrogen gas.[18] This disk has been globally stable for at least twenty years, as of 2020.[7] It is inclined at an angle of Script error: No such module "val". to the plane of the sky. 90% of the hydrogen emission comes from within 9.5 stellar radii of the host star, and the disk has an estimated mass of Script error: No such module "val". of the star's mass.[19]

References

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  1. ↑ a b c d e Script error: No such module "citation/CS1".
  2. ↑ a b c d e Template:Cite Gaia DR3
  3. ↑ a b c d Script error: No such module "citation/CS1".
  4. ↑ a b Script error: No such module "citation/CS1".
  5. ↑ a b Script error: No such module "citation/CS1". Note: type = GCAS.
  6. ↑ a b Script error: No such module "citation/CS1".
  7. ↑ a b c d e Script error: No such module "citation/CS1".
  8. ↑ Script error: No such module "citation/CS1".
  9. ↑ a b c d Script error: No such module "citation/CS1".
  10. ↑ Template:Cite simbad
  11. ↑ Script error: No such module "citation/CS1".
  12. ↑ Script error: No such module "citation/CS1".
  13. ↑ Template:In lang 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, Template:ISBN.
  14. ↑ Template:In lang AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 16 日 Template:Webarchive
  15. ↑ Script error: No such module "citation/CS1".
  16. ↑ Script error: No such module "citation/CS1".
  17. ↑ Script error: No such module "citation/CS1".
  18. ↑ Script error: No such module "citation/CS1".
  19. ↑ Script error: No such module "citation/CS1".

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External links

Template:Stars of Aquarius

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