Tau1 Aquarii
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquarius |
| Right ascension | 22h 47m 42.769s |
| Declination | −14° 03′ 23.14″ |
| Apparent magnitude (V) | +5.66 |
| Characteristics | |
| Spectral type | B9 V |
| U−B color index | −0.25 |
| B−V color index | −0.05 |
| Variable type | Constant |
| Astrometry | |
| Radial velocity (Rv) | +15 km/s |
| Proper motion (μ) | RA: +30.413 mas/yr Dec.: −9.053 mas/yr |
| Parallax (π) | 9.1322±0.0557 mas |
| Distance | 357 ± 2 ly (109.5 ± 0.7 pc) |
| Absolute magnitude (MV) | +0.74 |
| Details | |
| Mass | 2.68±0.05 M☉ |
| Radius | 2.0 R☉ |
| Luminosity | 63.5 L☉ |
| Temperature | 10,617 K |
| Rotational velocity (v sin i) | 185 km/s |
| Age | 100 Myr |
| Other designations | |
| τ1 Aqr, 69 Aquarii, BD−14 6346, GC 31802, HD 215766, HIP 112542, HR 8673, SAO 165298, PPM 240758, ADS 16268, WDS J22477-1403A | |
| Database references | |
| SIMBAD | data |
Tau1 Aquarii is a solitary star in the equatorial constellation of Aquarius. Its name is a Bayer designation that is Latinized from τ1 Aquarii, and abbreviated Tau1 Aqr or τ1 Aqr. With an apparent visual magnitude of 5.66, it is a faint naked eye target that requires dark suburban skies for viewing. Parallax measurements yield a distance estimate of approximately 357 light-years (109 parsecs) from the Sun. The star is drifting further away with a radial velocity of +15 km/s. It is a candidate member of the Pisces-Eridanus stellar stream.
The stellar classification of τ1 Aquarii is B9 V; at the borderline between a B- and A-type main sequence star. This is a candidate silicon star; a type of Ap star of class CP2 that shows a magnetic field. It is around 100 million years old and is spinning rapidly with a projected rotational velocity of 185 km/s. The star has 2.7 times the mass of the Sun and double the Sun's radius. It is radiating 63.5 times the luminosity of the Sun from its photosphere at an effective temperature of 10,617 K. When examined in the infrared band, it displays an excess emission that is a characteristic of stars with an orbiting debris disk. The model that best fits the data suggests there are two concentric circumstellar disks.