Phi Aquilae

Phi Aquilae, Latinized from φ Aquilae, is the Bayer designation of a binary star[11] system in the equatorial constellation of Aquila. It has an apparent visual magnitude of +5.28[2] and is visible to the naked eye. With an annual parallax shift of 14.86 mas,[1] this star is located at a distance of approximately 219 light-years (67 parsecs) from Earth.

Phi Aquilae
Location of φ Aquilae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila
Right ascension  19h 56m 14.25182s[1]
Declination +11° 25′ 25.3942″[1]
Apparent magnitude (V) +5.28[2]
Characteristics
Spectral type A1 IV[3]
U−B color index –0.02[2]
B−V color index +0.00[2]
Astrometry
Radial velocity (Rv)–27.2[4] km/s
Proper motion (μ) RA: +32.29[1] mas/yr
Dec.: +4.44[1] mas/yr
Parallax (π)14.86 ± 0.25 mas
Distance219 ± 4 ly
(67 ± 1 pc)
Absolute magnitude (MV)+1.14[5]
Orbit[6]
Period (P)3.32068 days
Eccentricity (e)0.025
Periastron epoch (T)JD 2423210.628
Argument of periastron (ω)
(secondary)		43°
Semi-amplitude (K1)
(primary)		37.2 km/s
Details
Radius1.8–2.5[7] R☉
Luminosity34[5] L☉
Surface gravity (log g)4.30[8] cgs
Temperature9,509[8] K
Metallicity [Fe/H]+0.47[8] dex
Rotational velocity (v sin i)27[9] km/s
Other designations
φ Aql, φ Aql, 61 Aql, BD+11° 4055, FK5 3590, HD 188728, HIP 98103, HR 7610, SAO 105438.[10]
Database references
SIMBADdata

Phi Aquilae is a single-lined spectroscopic binary with an orbital period of 3.32068 days.[6] The primary component is a subgiant star with a stellar classification of A1 IV.[3] The outer atmosphere has an effective temperature of 9,509 K,[8] giving it the white-hued appearance of an A-type star.[12] The orbiting companion may be the source of the X-ray emission from this system, as stars similar to the primary component do not generally produce detectable levels of X-rays.[13]

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. Oja, T. (April 1983), "UBV photometry of FK4 and FK4 supplement stars", Astronomy and Astrophysics Supplement Series, 52: 131–134, Bibcode:1983A&AS...52..131O.
  3. Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819.
  4. Wilson, Ralph Elmer (1953), General catalogue of stellar radial velocities, Carnegie Institution of Washington, Bibcode:1953GCRV..C......0W.
  5. 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.
  6. Lucy, L. B.; Sweeney, M. A. (August 1971), "Spectroscopic binaries with circular orbits", Astronomical Journal, 76: 544–556, Bibcode:1971AJ.....76..544L, doi:10.1086/111159.
  7. Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics", Astronomy and Astrophysics, 367: 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451.
  8. Soubiran, C.; Le Campion, J.-F.; Cayrel de Strobel, G.; Caillo, A. (June 2010), "The PASTEL catalogue of stellar parameters", Astronomy and Astrophysics, 515: A111, arXiv:1004.1069, Bibcode:2010A&A...515A.111S, doi:10.1051/0004-6361/201014247.
  9. Royer, F.; Zorec, J.; Gómez, A. E. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224.
  10. "phi Aql -- Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2012-07-21.
  11. 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.
  12. "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on March 10, 2012, retrieved 2012-01-16
  13. De Rosa, R. J.; et al. (July 2011), "The Volume-limited A-Star (VAST) survey - I. Companions and the unexpected X-ray detection of B6-A7 stars", Monthly Notices of the Royal Astronomical Society, 415 (1): 854–866, arXiv:1103.4363, Bibcode:2011MNRAS.415..854D, doi:10.1111/j.1365-2966.2011.18765.x.
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