Pi Aquilae

Pi Aquilae, Latinized from π Aquilae, is the Bayer designation for a binary star[2] system in the equatorial constellation of Aquila, about 3° to the north of the bright star Altair.[3] The apparent visual magnitude of the system is 5.85,[2] making it faintly visible to the naked eye from dark suburban skies. Based upon an annual parallax shift of 6.34 mas, the distance to this system is roughly 510 light-years (160 parsecs).[1]

Pi Aquilae
Location of π Aquilae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila
Right ascension  19h 48m 42.05765s[1]
Declination +11° 48′ 57.2177″[1]
Apparent magnitude (V) 5.85 (6.47/6.75)[2]
Characteristics
Spectral type G8 III: + A1 V[2][3]
Astrometry
Radial velocity (Rv)+12.6[3] km/s
Proper motion (μ) RA: +16.16[1] mas/yr
Dec.: –10.60[1] mas/yr
Parallax (π)6.34 ± 0.52[1] mas
Distance510 ± 40 ly
(160 ± 10 pc)
Absolute magnitude (MV)−0.22[4]
Details
Luminosity108[4] L☉
Other designations
π Aql, 52 Aquilae, BD+11 3994, HIP 97473, HR 7544, SAO 105282[5]
A: HD 187259
B: HD 187260
Database references
SIMBADdata
A
B

The binary nature of this system was first discovered by William Herschel in 1785.[3] The primary component of is a magnitude 6.47[2] giant star with a stellar classification of G8 III:.[2] A companion star at an angular separation of 1.437 arcseconds is an A-type main sequence star with a classification of A1 V.[2] It is slightly fainter, with an apparent magnitude of 6.75.[2]

References
  1. van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  3. Griffin, R.; Griffin, R. (December 1989), "Composite Spectra - Part Three - Pi-Aquilae", Journal for the History of Astronomy, 10 (4): 433, Bibcode:1989JApA...10..433G, doi:10.1007/BF02715077
  4. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  5. "* pi. Aql". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-20.
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