Pi Aquilae
Star in the constellation Aquila
From Wikipedia, the free encyclopedia
Pi Aquilae is a binary star[3] system in the equatorial constellation of Aquila, about 3° to the north of the bright star Altair.[4] Its name is a Bayer designation that is Latinised from π Aquilae, and abbreviated Pi Aql or π Aql. The apparent visual magnitude of the system is 5.85,[3] making it faintly visible to the naked eye from dark suburban skies. Based upon an annual parallax shift of 6.39 mas, the distance to this system is approximately 511 light-years (157 parsecs).[2]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquila[1] |
| Right ascension | 19h 48m 42.059s[2] |
| Declination | +11° 48′ 57.22″[2] |
| Apparent magnitude (V) | 5.85 (6.47 + 6.75)[3] |
| Characteristics | |
| Spectral type | G8 III: + A1 V[3][4] |
| Astrometry | |
| π Aql A | |
| Radial velocity (Rv) | +12.6[4] km/s |
| Proper motion (μ) | RA: +17.838 mas/yr[2] Dec.: −9.891 mas/yr[2] |
| Parallax (π) | 6.3883±0.0342 mas[2] |
| Distance | 511 ± 3 ly (156.5 ± 0.8 pc) |
| Absolute magnitude (MV) | −0.22[1] |
| Details | |
| π Aql A | |
| Luminosity | 108[1] L☉ |
| Temperature | 5,937+1,255 −569[5] K |
| π Aql B | |
| Radius | 10.9+0.5 −0.9[6] R☉ |
| Luminosity | 74.3±0.9[6] L☉ |
| Surface gravity (log g) | 4.5[6] cgs |
| Temperature | 5,128+226 −105[6] K |
| Other designations | |
| π Aql, 52 Aquilae, BD+11 3994, HIP 97473, HR 7544, SAO 105282, WDS J19487+1149A[7] | |
| A: HD 187259 | |
| B: HD 187260 | |
| Database references | |
| SIMBAD | data |
| A | |
| B | |
The binary nature of this system was first discovered by William Herschel in 1785.[4] The primary component is a magnitude 6.47[3] giant star with a stellar classification of G8 III:.[3] A companion star at an angular separation of 1.437 arcseconds is an A-type main-sequence star with a classification of A1 V.[3] It is slightly fainter, with an apparent magnitude of 6.75.[3]