104 Aquarii
Star in the constellation Aquarius
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104 Aquarii (abbreviated 104 Aqr) is a star in the equatorial constellation of Aquarius. 104 Aquarii is the Flamsteed designation, although it also bears the Bayer designation A2 Aquarii. Based on an annual parallax shift of only 3.89 ± 0.25 milliarcseconds, the distance to this star is about 840 light-years (260 parsecs).[9] At that range, the brightness of the star in the V-band is reduced by 0.10 magnitudes as a result of extinction caused by intervening gas and dust.[5]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquarius |
| Right ascension | 23h 41m 45.80579s[1] |
| Declination | â17° 48â² 59.5175â³[1] |
| Apparent magnitude (V) | 4.83[2] |
| Characteristics | |
| Spectral type | G2 Ib/II[3] |
| UâB color index | +0.49[2] |
| BâV color index | +0.82[2] |
| Astrometry | |
| Radial velocity (Rv) | +6.52±0.15[4] km/s |
| Proper motion (μ) | RA: +14.872[1] mas/yr Dec.: +0.862[1] mas/yr |
| Parallax (Ï) | 4.5774±0.1882 mas[1] |
| Distance | 710 ± 30 ly (218 ± 9 pc) |
| Absolute magnitude (MV) | â2.49[4] |
| Details | |
| Mass | 4.23[5] Mâ |
| Radius | 31.9±2.3[4] Râ |
| Luminosity | 447[5] Lâ |
| Surface gravity (log g) | 2.20[4] cgs |
| Temperature | 5,444±14[4] K |
| Metallicity [Fe/H] | +0.05[6] dex |
| Rotational velocity (v sin i) | 15[7] km/s |
| Age | 135[5] Myr |
| Other designations | |
| BDâ18 6358, HD 222574, HIP 116901, HR 8982, SAO 165836[8] | |
| Database references | |
| SIMBAD | data |
The star has a stellar classification of G2 Ib/II,[3] which places it on the borderline between the bright giant and lower luminosity supergiant stars. It has passed the first dredge-up and may be undergoing Cepheid-like pulsations.[4] With more than four times the mass of the Sun,[5] this is an evolved star that has reached its current stage after only 135 million years.[5] It has expanded to around 32 times the Sun's radius[4] and is radiating 447âfold the luminosity of the Sun.[5] This energy is being emitted from its outer atmosphere at an effective temperature of 5,478 K,[6] giving it the golden-hued glow of a G-type star.[10] It is a suspected variable star.[11]
There is an optical companion, HD 222561, a magnitude 8.5 star with an angular separation of 119 arcseconds from the primary. It is an unrelated background star, with a smaller parallax and different proper motion.[12]