EW Aquarii

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Template:Short description

EW Aquarii
File:EWAqrLightCurve.png
Six visual band light curves of for EW Aquarii, adapted from Hobart et al. (1989)[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius
Right ascension Template:RA[2]
Declination Template:DEC[2]
Apparent magnitude (V) 6.47[3] (6.41 - 6.48)[4]
Characteristics
Spectral type A8 III[4] or Fm δ Del[5]
U−B Template:Engvar 0.15[6]
B−V Template:Engvar Script error: No such module "val".[3]
Variable type δ Sct[4]
Astrometry
Radial velocity (Rv)Script error: No such module "val".[3] km/s
Proper motion (μ) RA: +39.263[2] mas/yr
Dec.: +0.614[2] mas/yr
Parallax (π)7.4366±0.0435 mas[2]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)0.825[7]
Details
Mass2.203[7] Template:Solar mass
RadiusScript error: No such module "val".[2] Template:Solar radius
LuminosityScript error: No such module "val".[2] Template:Solar luminosity
Surface gravity (log g)3.91[8] cgs
Temperature7,640[8] K
Rotational velocity (v sin i)134[6] km/s
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist[9]
Database references
SIMBADdata

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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

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  5. ↑ a b Script error: No such module "citation/CS1".
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  7. ↑ a b c Script error: No such module "Citation/CS1".
  8. ↑ a b c d Script error: No such module "Citation/CS1".
  9. ↑ Template:Cite simbad
  10. ↑ Script error: No such module "Citation/CS1". See run #5217, for example.
  11. ↑ a b Script error: No such module "Citation/CS1".
  12. ↑ Script error: No such module "Citation/CS1".
  13. ↑ a b Script error: No such module "Citation/CS1".
  14. ↑ Script error: No such module "Citation/CS1".
  15. ↑ Script error: No such module "Citation/CS1".

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Template:Stars of Aquarius

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