15 Aquarii

15 Aquarii, abbreviated 15 Aqr, is a single,^[12] blue-white star in the zodiac constellation of Aquarius. 15 Aquarii is the Flamsteed designation. It is a dim star that is just visible to the naked eye under good viewing conditions, having an apparent visual magnitude of 5.83.^[2] Based upon an annual parallax shift of 4.6 mas,^[1] it is located around 710 light years away. At that distance, the visual magnitude is diminished by an extinction of 0.18 due to interstellar dust.^[13] It is moving closer to the Earth with a heliocentric radial velocity of −9 km/s.^[5] Relative to its neighbors, 15 Aqr has a peculiar velocity of 28.7+2.9
−3.1 km/s and may (62% chance) be a runaway star.^[7]

15 Aquarii

Observation data Epoch J2000      Equinox J2000
Constellation	Aquarius
Right ascension	21h 18m 11.07309s[1]
Declination	−04° 31′ 10.1276″[1]
Apparent magnitude (V)	5.83[2]
Characteristics
Spectral type	B7 III[3] or B5 V[4]
B−V color index	−0.130±0.005[2]
Astrometry
Radial velocity (Rv)	−9.0±1.0[5] km/s
Proper motion (μ)	RA: +12.11[6] mas/yr Dec.: +12.94[6] mas/yr
Parallax (π)	4.5632±0.1345 mas[1]
Distance	710 ± 20 ly (219 ± 6 pc)
Absolute magnitude (MV)	−1.62[2]
Details
Mass	5.7±0.2[7] M☉
Radius	3.4[8] R☉
Luminosity	821.67[2] L☉
Surface gravity (log g)	3.84[9] cgs
Temperature	14,318[9] K
Rotational velocity (v sin i)	20[10] km/s
Age	65.2±25.1[7] Myr
Other designations
15 Aqr, BD−05°5512, HD 202753, HIP 105164, HR 8141, SAO 145278[11]
Database references
SIMBAD	data

Hube (1970) found a stellar classification of B7 III^[3] for this star, which would suggest it is a B-type giant star. However, the Bright Star Catalogue (1964) listed it as a B-type main-sequence star with a class of B5 V,^[4] and multiple sources use this instead.^{[7][10][8][9]} The star is roughly 65^[7] million years old with a projected rotational velocity of 20 km/s.^[10] It has an estimated 5.7^[7] times the mass of the Sun and about 3.4^[8] times the Sun's radius. 15 Aquarii is radiating 822^[2] times the Sun's luminosity from its photosphere at an effective temperature of 14,318 K.^[9]