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]
| 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 | |
| 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]