Alpha Scuti
Star in the constellation Scutum
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Alpha Scuti, Latinized from α Scuti, is an orange-hued star in the southern constellation of Scutum. Originally part of the Aquila constellation, Alpha Scuti was a latter designation of 1 Aquilae.[9] It is faintly visible to the naked eye with an apparent visual magnitude of 3.83.[3] Based upon an annual parallax shift of 16.38 mas as seen from the Earth,[2] it is located around 199 light years from the Sun. It is moving away from the Sun with a radial velocity of +36.5 km/s.[5]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Scutum[1] |
| Right ascension | 18h 35m 12.42776s[2] |
| Declination | −08° 14′ 38.6529″[2] |
| Apparent magnitude (V) | 3.83[3] |
| Characteristics | |
| Spectral type | K3III[4] |
| U−B color index | +1.53[3] |
| B−V color index | +1.34[3] |
| Astrometry | |
| Radial velocity (Rv) | +36.50[5] km/s |
| Proper motion (μ) | RA: −17.00[2] mas/yr Dec.: −313.52[2] mas/yr |
| Parallax (π) | 16.38±0.22 mas[2] |
| Distance | 199 ± 3 ly (61.1 ± 0.8 pc) |
| Absolute magnitude (MV) | −0.08[1] |
| Details | |
| Mass | 1.33[6] M☉ |
| Radius | 20[6] R☉ |
| Luminosity | 186[1] L☉ |
| Surface gravity (log g) | 1.96[6] cgs |
| Temperature | 4,315[7] K |
| Metallicity [Fe/H] | −0.04[1] dex |
| Rotational velocity (v sin i) | 1.7[8] km/s |
| Other designations | |
| α Sct, BD−08°4638, FK5 1482, GC 25385, HD 171443, HIP 91117, HR 6973, LTT 7377, NSV 11056, SAO 142408 | |
| Database references | |
| SIMBAD | data |
Properties
With a stellar classification of K3 III,[4] the spectrum indicates it is an evolved giant star of type K. Alpha Scuti is a suspected variable star with magnitude range reported as 3.81 to 3.87.[10] The star has an estimated 1.33 times the mass of the Sun, but the outer envelope has expanded to 20 times the Sun's radius.[6] It is radiating 186[1] times the Sun's luminosity from its inflated photosphere at an effective temperature of 4,315 K.[7]