EW Aquarii
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] |
Distance | 439 ± 3ly (134.5 ± 0.8pc) |
Absolute magnitude(MV) | 0.825[7] |
Details | |
Mass | 2.203[7]M☉ |
Radius | 3.99±0.20[2]R☉ |
Luminosity | 37.026±0.314[2]L☉ |
Surface gravity(logg) | 3.91[8]cgs |
Temperature | 7,640[8]K |
Rotational velocity(vsini) | 134[6]km/s |
Other designations | |
Database references | |
SIMBAD | data |
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]- ^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.
- ^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.
- ^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.
- ^abcdWatson, Christopher (4 January 2010)."EW Aquarii".The International Variable Star Index.American Association of Variable Star Observers.Retrieved4 June2015.
- ^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.
- ^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.
- ^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.
- ^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.
- ^"HD 199603".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved20 August2018.
- ^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.
- ^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.
- ^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.
- ^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.
- ^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.
- ^Kukarkin, B. V.; et al. (March 1977). "62nd Name-List of Variable Stars".Information Bulletin on Variable Stars.1248:1.Bibcode:1977IBVS.1248....1K.