Psi2 Aquarii

For other stars with this Bayer designation, see ψ Aquarii.
ψ2 Aquarii
Location of ψ2 Aquarii (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius
Right ascension 23h 17m 54.21372s[1]
Declination −09° 10′ 57.0675″[1]
Apparent magnitude (V) 4.403[2]
Characteristics
Spectral type B5 Vn[3]
U−B color index −0.561[2]
B−V color index −0.146[2]
Variable type λ Eri[4]
Astrometry
Radial velocity (Rv)−6[5] km/s
Proper motion (μ) RA: +17.13[1] mas/yr
Dec.: −11.70[1] mas/yr
Parallax (π)8.12 ± 0.38 mas[1]
Distance400 ± 20 ly
(123 ± 6 pc)
Absolute magnitude (MV)−1.04[6]
Details
Radius4.6[7] R☉
Luminosity565[6] L☉
Temperature15,212 ± 288[7] K
Rotational velocity (v sin i)341[8] km/s
Other designations
ψ2 Aqr, 93 Aquarii, BD−09°6160, HD 219688, HIP 115033, HR 8858, SAO 146620.[9]
Database references
SIMBADdata

Psi2 Aquarii, Latinized from ψ2 Aquarii, is the Bayer designation for a star in the equatorial constellation of Aquarius. It is visible to the naked eye with an apparent visual magnitude of 4.4.[2] Based upon parallax measurements made during the Hipparcos mission, the distance to this star is roughly 400 light-years (120 parsecs).[1]

A light curve for Psi2 Aquarii, plotted from TESS data[10]

This is a B-type main sequence star with a stellar classification of B5 Vn.[3] The 'n' suffix indicates that the absorption lines in the spectrum are being broadened by Doppler shift from the star's rapid rotation rate. The projected rotational velocity of the star is 341 km/s.[8] Psi2 Aquarii is 4.6[7] times as large as the Sun with an effective temperature of 15,212 K[7] in its outer envelope.

It is a λ Eridani variable, or periodic Be star, with a pulsation cycle lasting 1.073 days.[4] The amplitude of the variation is 0.024 in magnitude.[11]

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