38 Aquarii

This article is about e Aquarii and is not to be confused with ε (epsilon) Aquarii.

38 Aquarii is a star in the equatorial constellation of Aquarius. 38 Aquarii is its Flamsteed designation; its Bayer designation is e Aquarii. It is a faint star but visible to the naked eye, with an apparent visual magnitude of +5.43.^[2] Based on parallax measurements, it is around 450 light-years (140 parsecs) away;^[1] it is 0.28 degree south of the ecliptic.

38 Aquarii

Location of 38 Aquarii (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Aquarius
Right ascension	22h 10m 37.48206s[1]
Declination	−11° 33′ 53.7754″[1]
Apparent magnitude (V)	+5.43[2]
Characteristics
Spectral type	B5 III[3]
B−V color index	−0.12[4]
Astrometry
Radial velocity (Rv)	+1.5[2] km/s
Proper motion (μ)	RA: +29.29[1] mas/yr Dec.: +8.76[1] mas/yr
Parallax (π)	7.25±0.33 mas[1]
Distance	450 ± 20 ly (138 ± 6 pc)
Absolute magnitude (MV)	−0.26[5]
Details
Radius	5.6[6] R☉
Luminosity	219.16[5] L☉
Surface gravity (log g)	4.00[3] cgs
Temperature	13,860[3] K
Metallicity [Fe/H]	–0.26[3] dex
Rotational velocity (v sin i)	20[7] km/s
Other designations
38 Aqr, BD−12°6196, FK5 3771, HD 210424, HIP 109472, HR 8452, SAO 164910[8]
Database references
SIMBAD	data

The spectrum of 38 Aquarii matches a stellar classification of B5 III.^[3] A luminosity class of III indicates that this is an evolved giant star. It has 5.6^[6] times the radius of the Sun and is spinning with a projected rotational velocity of 20 km/s.^[7] The outer atmosphere of the star has a blue-white glow from an effective temperature of 13,860 K.^[3]