Phi Aquilae
Location of φ Aquilae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila
Right ascension 19h 56m 14.25183s[1]
Declination +11° 25′ 25.3931″[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: +32.826[1] mas/yr
Dec.: +6.162[1] mas/yr
Parallax (π)14.1980 ± 0.1579 mas
Distance230 ± 3 ly
(70.4 ± 0.8 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
A
Mass2.39[7] M☉
Radius1.8–2.5[8] R☉
Luminosity34[5] L☉
Surface gravity (log g)4.30[9] cgs
Temperature9,509[9] K
Metallicity [Fe/H]+0.47[9] dex
Rotational velocity (v sin i)27[10] km/s
Age280[7] Myr
B
Mass0.40[7] M☉
Other designations
φ Aql, 61 Aql, BD+11° 4055, FK5 3590, HD 188728, HIP 98103, HR 7610, SAO 105438[11]
Database references
SIMBADdata

Phi Aquilae, Latinized from φ Aquilae, is the Bayer designation of a binary star[12] 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 14.198 mas,[1] this star is located at a distance of approximately 230 light-years (71 parsecs) from Earth. It is drifting closer with a radial velocity of –27 km/s.[4] Based on its motion through space, this system is considered a possible member of the nearby Argus association of co-moving stars, although it may be too old.[13]

Phi Aquilae is a single-lined spectroscopic binary with an orbital period of 3.32068 days.[6] The pair have a projected separation of 190.4 AU as of 2008.[7] The primary component is a subgiant star with a stellar classification of A1 IV.[3] The star is around 280[7] million years old and is spinning with a projected rotational velocity of 27.[10] It has 2.39[7] times the mass of the Sun and somewhere in the range of 1.8–2.5[8] times the Sun's radius. The outer atmosphere has an effective temperature of 9,509 K,[9] giving it the white-hued appearance of an A-type star.[14] It is radiating 34[5] times the luminosity of the Sun.

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.[15] It has 40% of the mass of the Sun.[7]

References

  1. 1 2 3 4 5 Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. 1 2 3 4 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. 1 2 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. 1 2 Wilson, Ralph Elmer (1953), "General catalogue of stellar radial velocities", Carnegie Institute Washington D.C. Publication, Carnegie Institution of Washington, Bibcode:1953GCRV..C......0W.
  5. 1 2 3 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, S2CID 119257644.
  6. 1 2 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. 1 2 3 4 5 6 7 De Rosa, R. J.; Patience, J.; Wilson, P. A.; Schneider, A.; Wiktorowicz, S. J.; Vigan, A.; Marois, C.; Song, I.; Macintosh, B.; Graham, J. R.; Doyon, R.; Bessell, M. S.; Thomas, S.; Lai, O. (2014), "The VAST Survey - III. The multiplicity of A-type stars within 75 pc", Monthly Notices of the Royal Astronomical Society, 437 (2): 1216–1240, arXiv:1311.7141, Bibcode:2014MNRAS.437.1216D, doi:10.1093/mnras/stt1932.
  8. 1 2 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 (2): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
  9. 1 2 3 4 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, S2CID 118362423.
  10. 1 2 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, S2CID 18475298.
  11. ↑ "phi Aql -- Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2012-07-21.
  12. ↑ 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, S2CID 14878976.
  13. ↑ Zuckerman, B. (January 2019), "The Nearby, Young, Argus Association: Membership, Age, and Dusty Debris Disks", The Astrophysical Journal, 870 (1): 8, arXiv:1811.01508, Bibcode:2019ApJ...870...27Z, doi:10.3847/1538-4357/aaee66, S2CID 119452542, 27.
  14. ↑ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on March 18, 2012, retrieved 2012-01-16
  15. ↑ 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, S2CID 84181878.
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