Jump to content

EW Aquarii

From Wikipedia, the free encyclopedia
EW Aquarii

Sixvisual bandlight curvesof for EW Aquarii, adapted from Hobartet al.(1989)[1]
Observation data
EpochJ2000EquinoxJ2000
Constellation Aquarius
Right ascension 21h11m41.33844s[2]
Declination −14° 28′ 20.5590″[2]
Apparent magnitude(V) 6.47[3](6.41 - 6.48)[4]
Characteristics
Spectral type A8 III[4]orFm δ Del[5]
U−Bcolor index 0.15[6]
B−Vcolor index 0.316±0.007[3]
Variable type δ Sct[4]
Astrometry
Radial velocity(Rv)−39.2±2.9[3]km/s
Proper motion(μ)RA:+39.263[2]mas/yr
Dec.:+0.614[2]mas/yr
Parallax(π)7.4366 ± 0.0435mas[2]
Distance439 ± 3ly
(134.5 ± 0.8pc)
Absolute magnitude(MV)0.825[7]
Details
Mass2.203[7]M☉
Radius3.99±0.20[2]R☉
Luminosity37.026±0.314[2]L☉
Surface gravity(logg)3.91[8]cgs
Temperature7,640[8]K
Rotational velocity(vsini)134[6]km/s
Other designations
BD−15°5908,FK55868,HD201707,HIP104634,HR8102,SAO164204[9]
Database references
SIMBADdata

EW Aquarii,or HR 8102, is avariable starin theequatorialconstellationofAquarius.With anapparent visual magnitudethat fluctuates around 6.47,[3]it is a dim star near the lower limit of visibility to the naked eye. The star is located at a distance of approximately 439light yearsfrom theSunbased onparallax,but is drifting closer with aradial velocityof −39 km/s.[3]The star is positioned near theeclipticand thus is subject tolunar occultations.[10]It may be a member of theHyades Group.[11]

In 1969, HR 8102 was flagged as a suspected metal-linedDelta Delphini star[12]and was catalogued as such.[13]During a search for ultra-short periodCepheid variablesin 1974, this star was found to vary in brightness[11]and was determined to be a low amplitudeDelta Scuti variable.[14][8]In 1977, it was catalogued in the 62nd name-list of variable stars with thedesignationEW Aqr.[15]The star varies between magnitudes 6.41 and 6.48 with a primary period of 2.16 hours.[4]There are three known variation periods of 0.09664, 0.1087, and 0.2121 days with amplitudes of 0.013, 0.010, and 0.007 magnitudes, respectively. The pattern of variations indicate it is a non-radial pulsator.[13]

Thestellar classificationof EW Aqr isFm δ Del,indicating anF-typeAm starof the Delta Delphini type.[5]It has 2.2[7]times themass of the Sunand four[2]times theSun's radius.The star has a high rate of spin, showing aprojected rotational velocityof 134 km/s.[6]On average, it is radiating 37[2]times theluminosity of the Sunfrom itsphotosphereat aneffective temperatureof 7,640 K.[8]

References

[edit]
  1. ^Hobart, M. A.; Pena, J. H.; Peniche, R. (December 1989)."EW Aqr, a non radial Delta Scuti pulsator".Revista Mexicana de Astronomía y Astrofísica.17:103–108.Bibcode:1989RMxAA..17..103H.Retrieved16 October2021.
  2. ^abcdefghiBrown, A. G. A.;et al. (Gaia collaboration) (August 2018)."GaiaData Release 2: Summary of the contents and survey properties ".Astronomy & Astrophysics.616.A1.arXiv:1804.09365.Bibcode:2018A&A...616A...1G.doi:10.1051/0004-6361/201833051.Gaia DR2 record for this sourceatVizieR.
  3. ^abcdeAnderson, 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.S2CID119257644.
  4. ^abcdWatson, Christopher (4 January 2010)."EW Aquarii".The International Variable Star Index.American Association of Variable Star Observers.Retrieved4 June2015.
  5. ^abHouk, Nancy; Smith-Moore, M. (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.
  6. ^abcRodríguez, E.; et al. (June 2000)."A revised catalogue of δ Sct stars".Astronomy and Astrophysics Supplement.144(3): 469–474.Bibcode:2000A&AS..144..469R.doi:10.1051/aas:2000221.hdl:10261/226673.
  7. ^abcBalona, L. A.; Evers, E. A. (January 1999)."Mode identification and asteroseismology of delta Scuti stars".Monthly Notices of the Royal Astronomical Society.302(2): 349–361.Bibcode:1999MNRAS.302..349B.doi:10.1046/j.1365-8711.1999.02125.x.
  8. ^abcdKilambi, G. C.; et al. (April 1978)."uvby analysis of HR 8102".Publications of the Astronomical Society of the Pacific.90:194–200.Bibcode:1978PASP...90..194K.doi:10.1086/130307.S2CID119675836.
  9. ^"HD 199603".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved20 August2018.
  10. ^Edwards, D. A.; et al. (April 1980). "Photoelectric observations of lunar occultations. XI".Astronomical Journal.85:478–489.Bibcode:1980AJ.....85..478E.doi:10.1086/112700.See run #5217, for example.
  11. ^abEggen, O. J. (October 1974). "Photometry of Possible Ultrashort Period Cepheids in the Disk Populations".Information Bulletin on Variable Stars.935:1.Bibcode:1974IBVS..935....1E.
  12. ^Cowley, A. P.; et al. (December 1968). "Further Bright Peculiar A Stars".Publications of the Astronomical Society of the Pacific.80(477): 746.Bibcode:1968PASP...80..746C.doi:10.1086/128719.S2CID122523455.
  13. ^abHobart, M. A.; et al. (December 1989). "EW Aqr, a non radial Delta Scuti pulsator".Revista Mexicana de Astronomía y Astrofísica.17:103–108.Bibcode:1989RMxAA..17..103H.
  14. ^Kilambi, G. C. (July 1975). "H beta-photometry of HR 8024 and HR 8102".Information Bulletin on Variable Stars.1024:1.Bibcode:1975IBVS.1024....1K.
  15. ^Kukarkin, B. V.; et al. (March 1977). "62nd Name-List of Variable Stars".Information Bulletin on Variable Stars.1248:1.Bibcode:1977IBVS.1248....1K.
Retrieved from "https://en.wikipedia.org/w/index.php?title=EW_Aquarii&oldid=1193283554"