29 Aquarii

29 Aquarii is a binary star system located around 590 light years away from the Sun in the equatorial constellation of Aquarius. 29 Aquarii is the Flamsteed designation; the system also bears the variable star designation DX Aquarii. It is a challenge to view with the naked eye, appearing as a dim star with a combined apparent visual magnitude of 6.39.^[3] The system is moving further from the Earth with a heliocentric radial velocity of about +15 km/s.^[3]

29 Aquarii

The light curve of 29 Aquarii, from Hipparcos data[1]
Observation data Epoch J2000      Equinox J2000
Constellation	Aquarius
Right ascension	22h 02m 26.24845s[2]
Declination	−16° 57′ 53.3959″[2]
Apparent magnitude (V)	6.39[3]
Characteristics
Spectral type	A2 V + K0 III[4]
B−V color index	0.447±0.022[3]
Astrometry
Radial velocity (Rv)	+15.0±4.3[3] km/s
Proper motion (μ)	RA: +5.292[2] mas/yr Dec.: +1.256[2] mas/yr
Parallax (π)	5.5489±0.1285 mas[5]
Distance	590 ± 10 ly (180 ± 4 pc)
Orbit[6]
Period (P)	0.945 d
Eccentricity (e)	0.00
Periastron epoch (T)	2,436,814.418±1.0 JD
Semi-amplitude (K1) (primary)	97.9 km/s
Other designations
BD−17°6422, HD 209278, HIP 108797, HR 8396, SAO 164830, WDS J22024-1658[7]
Database references
SIMBAD	data

This is a spectroscopic binary system with a close circular orbit taking just 0.945 days to complete.^[6] Despite their proximity, this does not appear to be a contact binary system.^[8] The orbital plane of the two stars lies near the line of sight, so they form an Algol-type eclipsing binary. The first component of the system is an A-type main sequence star with a stellar classification of A2 V. Its companion is giant star with a classification of K0 III.^[4]

The variability of this system was first noticed in 1965 by W. Strohmeier of Remeis-Observatory in Bamberg, Germany.^[9] He later discovered that the variability was caused by a binary companion eclipsing the primary star.^[10]