Alpha Aquilae
 Altair in the constellation of Aquila. |
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| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) |
|
|---|---|
| Constellation | Aquila |
| Pronunciation | /ˈæltɛər/, /ˈæltaɪər/ |
| Right ascension | 19h 50m 46.99855s |
| Declination | +08° 52′ 05.9563″ |
| Apparent magnitude (V) | 0.76 |
| Characteristics | |
| Evolutionary stage | Main sequence |
| Spectral type | A7 V |
| U−B color index | +0.09 |
| B−V color index | +0.22 |
| V−R color index | +0.14 |
| R−I color index | +0.13 |
| Variable type | Delta Scuti |
| Astrometry | |
| Radial velocity (Rv) | −26.1 ± 0.9 km/s |
| Proper motion (μ) |
RA: +536.23 mas/yr Dec.: +385.29 mas/yr |
| Parallax (π) | 194.95 ± 0.57mas |
| Distance | 16.73 ± 0.05 ly (5.13 ± 0.01 pc) |
| Absolute magnitude (MV) | 2.22 |
| Details | |
| Mass | 1.79 ± 0.018 M☉ |
| Radius | 1.63 to 2.03 R☉ |
| Luminosity | 10.6 L☉ |
| Surface gravity (log g) | 4.29 cgs |
| Temperature | 6,900 to 8,500 K |
| Metallicity [Fe/H] | −0.2 dex |
| Rotation | 8.9 hours |
| Rotational velocity (v sin i) | 240 km/s |
| Age | 1.2 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Altair (/ˈæltɛər, -taɪər, ælˈtɛər, -ˈtaɪər/), also designated Alpha Aquilae (α Aquilae, abbreviated Alpha Aql, α Aql), is the brightest star in the constellation of Aquila and the twelfth brightest star in the night sky. It is currently in the G-cloud—a nearby accumulation of gas and dust known as an interstellar cloud. Altair is an A-type main sequence star with an apparent visual magnitude of 0.77 and is one of the vertices of the asterism known as the Summer Triangle (the other two vertices are marked by Deneb and Vega). It is 16.7 light-years (5.13 parsecs) from the Sun and is one of the closest stars visible to the naked eye.
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