Chi Aquarii, Latinized from χ Aquarii, is the Bayer designation of a star in the equatorial constellation of Aquarius. The distance to this star, based upon parallax measurements with a 7% margin of error, is roughly 610 light-years (190 parsecs). It is visible to the naked eye with an apparent visual magnitude of about 5.
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquarius |
| Right ascension | 23h 16m 50.93916s[1] |
| Declination | −07° 43′ 35.4023″[1] |
| Apparent magnitude (V) | 4.75 - 5.10[2] |
| Characteristics | |
| Spectral type | M3 III[3] |
| U−B color index | +1.60[4] |
| B−V color index | +1.60[4] |
| Variable type | SRb?[2] |
| Astrometry | |
| Radial velocity (Rv) | −13.72 ± 0.86[5] km/s |
| Proper motion (μ) | RA: −19.18[1] mas/yr Dec.: −14.10[1] mas/yr |
| Parallax (π) | 5.32 ± 0.37 mas[1] |
| Distance | 610 ± 40 ly (190 ± 10 pc) |
| Absolute magnitude (MV) | −1.43[6] |
| Details | |
| Radius | 142[7] R☉ |
| Luminosity | 2,598[7] L☉ |
| Surface gravity (log g) | 0.128[7] cgs |
| Temperature | 3,456[7] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is a red giant star with a spectral classification of M3 III.[3] The interferometry-measured angular diameter of this star is 6.70 ± 0.15 mas,[10] which, at its estimated distance, equates to a physical radius of about 137 times the radius of the Sun.[a] It is classified as a semi-regular variable star and its brightness varies by an amplitude of 0.0636 in magnitude.[11] The identified pulsation periods are 32.3, 38.5, and 44.9 days.[12]