EW Aquarii

EW Aquarii
	; Six visual band light curves of for EW Aquarii, adapted from Hobart et al. (1989)
Observation data; Epoch J2000 Equinox J2000
Constellation	Aquarius
Right ascension	21h 11m 41.33844s
Declination	−14° 28′ 20.5590″
Apparent magnitude (V)	6.47 (6.41 - 6.48)
Characteristics
Spectral type	A8 III or Fm δ Del
U−B color index	0.15
B−V color index	0.316±0.007
Variable type	δ Sct
Astrometry
Radial velocity (Rv)	−39.2±2.9 km/s
Proper motion (μ)	RA: +39.263 mas/yr ; Dec.: +0.614 mas/yr
Parallax (π)	7.4366 ± 0.0435 mas
Distance	439 ± 3 ly ; (134.5 ± 0.8 pc)
Absolute magnitude (MV)	0.825
Details
Mass	2.203 M☉
Radius	3.99±0.20 R☉
Luminosity	37.026±0.314 L☉
Surface gravity (log g)	3.91 cgs
Temperature	7,640 K
Rotational velocity (v sin i)	134 km/s
Other designations
	BD−15°5908, FK5 5868, HD 201707, HIP 104634, HR 8102, SAO 164204
Database references
SIMBAD	data

EW Aquarii, or HR 8102, is a variable star in the equatorial constellation of Aquarius. With an apparent visual magnitude that 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 439 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −39 km/s.^[3] The star is positioned near the ecliptic and thus is subject to lunar occultations.^[10] It may be a member of the Hyades Group.^[11]

In 1969, HR 8102 was flagged as a suspected metal-lined Delta Delphini star^[12] and was catalogued as such.^[13] During a search for ultra-short period Cepheid variables in 1974, this star was found to vary in brightness^[11] and was determined to be a low amplitude Delta Scuti variable.^[14]^[8] In 1977, it was catalogued in the 62nd name-list of variable stars with the designation EW 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]

The stellar classification of EW Aqr is Fm δ Del, indicating an F-type Am star of the Delta Delphini type.^[5] It has 2.2^[7] times the mass of the Sun and four^[2] times the Sun's radius. The star has a high rate of spin, showing a projected rotational velocity of 134 km/s.^[6] On average, it is radiating 37^[2] times the luminosity of the Sun from its photosphere at an effective temperature of 7,640 K.^[8]

References

^ 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. Retrieved 16 October 2021.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data 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 source at VizieR.
^ ^a ^b ^c ^d ^e 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 Watson, Christopher (4 January 2010). "EW Aquarii". The International Variable Star Index. American Association of Variable Star Observers. Retrieved 4 June 2015.
^ ^a ^b Houk, 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.
^ ^a ^b ^c Rodríguez, 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.
^ ^a ^b ^c Balona, 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.
^ ^a ^b ^c ^d Kilambi, 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. S2CID 119675836.
^ "HD 199603". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 20 August 2018.
^ 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.
^ ^a ^b Eggen, 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. S2CID 122523455.
^ ^a ^b Hobart, 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.

[Hobart-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. Retrieved 16 October 2021.

[GaiaDR2-2] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data 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 source at VizieR.

[Anderson_Francis_2012-3] 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.

[AAVSOEW-4] Watson, Christopher (4 January 2010). "EW Aquarii". The International Variable Star Index. American Association of Variable Star Observers. Retrieved 4 June 2015.

[Houk_Smith-Moore_1978-5] Houk, 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.

[Rodríguez_et_al_2000-6] Rodríguez, 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.

[Balona_Evers_1999-7] Balona, 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.

[Kilambi1978-8] Kilambi, 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. S2CID 119675836.

[SIMBAD-9] "HD 199603". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 20 August 2018.

[Edwards_et_al_1980-10] 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.

[Eggen1974-11] Eggen, 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_et_al_1968-12] 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. S2CID 122523455.

[Hobart1989-13] Hobart, 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.

[Kilambi1024-14] 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.

[Kukarkin_et_al_1977-15] Kukarkin, B. V.; et al. (March 1977). "62nd Name-List of Variable Stars". Information Bulletin on Variable Stars. 1248: 1. Bibcode:1977IBVS.1248....1K.

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EW Aquarii

References

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