101 Aquarii

This article is about b³ Aquarii. For other star systems with this Bayer designation, see b Aquarii.

101 Aquarii (abbreviated 101 Aqr) is a star in the equatorial constellation of Aquarius. 101 Aquarii is the Flamsteed designation, although it also bears the Bayer designation b³ Aquarii. 101 Aqr is a double star with the designation B 1900. The combined apparent visual magnitude of the pair is 4.71,^[2] which is bright enough to be seen with the naked eye from the suburbs. The distance of this star from Earth is estimated as 290 light-years (89 parsecs) based upon parallax measurements.^[1]

101 Aquarii

Location of 101 Aquarii (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Aquarius
Right ascension	23h 33m 16.62300s[1]
Declination	−20° 54′ 52.2155″[1]
Apparent magnitude (V)	4.71[2]
Characteristics
Spectral type	A0 V[3]
U−B color index	+0.00[2]
B−V color index	+0.02[2]
Astrometry
Radial velocity (Rv)	+15[4] km/s
Proper motion (μ)	RA: −3.41[1] mas/yr Dec.: +8.46[1] mas/yr
Parallax (π)	11.11±0.67 mas
Distance	290 ± 20 ly (90 ± 5 pc)
Details
Rotational velocity (v sin i)	180[5] km/s
Other designations
BD−21 6437, HD 221565, HIP 116247, HR 8939, SAO 191988[6]
Database references
SIMBAD	data

The brighter member of this system has an apparent magnitude of 4.81. It is an A-type main sequence star with a stellar classification of A0 V.^[3] This star is spinning rapidly with a projected rotational velocity of 1 km/s.^[5] The fainter companion is a magnitude 7.43 star at an angular separation of 0.840 arcseconds.^[7]