Phi Aquarii
Star in the constellation Aquarius / From Wikipedia, the free encyclopedia
Phi Aquarii, Latinized from φ Aquarii, is the Bayer designation for a binary star[8] system in the equatorial constellation of Aquarius. It is visible to the naked eye with a combined apparent visual magnitude of +4.223.[2] Parallax measurements indicate its distance from Earth is roughly 222 light-years (68 parsecs),[1] and it is drifting further away with a radial velocity of +2.5 km/s.[4] It is 1.05 degrees south of the ecliptic so it is subject to lunar occultations.[9]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Aquarius |
Right ascension | 23h 14m 19.35965s[1] |
Declination | –06° 02′ 56.3986″[1] |
Apparent magnitude (V) | +4.223[2] |
Characteristics | |
Spectral type | M1.5 III[3] |
U−B color index | +1.897[2] |
B−V color index | +1.563[2] |
Astrometry | |
Radial velocity (Rv) | +2.48±0.32[4] km/s |
Proper motion (μ) | RA: +35.391[1] mas/yr Dec.: –196.862[1] mas/yr |
Parallax (π) | 14.6670 ± 0.4099 mas[1] |
Distance | 222 ± 6 ly (68 ± 2 pc) |
Absolute magnitude (MV) | 0.30±0.120[5] |
Details | |
Mass | 1.00±0.03[6] M☉ |
Radius | 34.77+1.83 −2.04[6] R☉ |
Luminosity | 207.7±25.2[6] L☉ |
Surface gravity (log g) | 1.5[4] cgs |
Temperature | 3715±48[6] K |
Rotational velocity (v sin i) | 6.7[4] km/s |
Age | 10.97±0.83[6] Gyr |
Other designations | |
Database references | |
SIMBAD | data |
This is a spectroscopic binary star system with an estimated period of 2,500 days.[10] The primary component is a red giant star with a stellar classification of M1.5 III.[3] The outer envelope of this evolved star has expanded to 35 times the size of the Sun. The star has the same mass as the Sun.[6] It is radiating 208 times the luminosity of the Sun at an effective temperature of 3,715 K,[6] giving it the reddish hue of an M-type star.[11]