Phi Aquilae

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Phi Aquilae
Diagram showing star positions and boundaries of the Aquila constellation and its surroundings
Cercle rouge 100%.svg

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
Distance 219 ± 4 ly
(67 ± 1 pc)
Orbit[5]
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
Radius 1.8–2.5[6] R
Surface gravity (log g) 4.30[7] cgs
Temperature 9,509[7] K
Metallicity [Fe/H] +0.47[7] dex
Rotational velocity (v sin i) 27[8] km/s
Other designations
phi Aql, 61 Aquilae, BD+11 4055, FK5 3590, HD 188728, HIP 98103, HR 7610, SAO 105438.[9]

Phi Aquilae (φ Aql, φ Aquilae) is the Bayer designation of a binary star[10] 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 is a single-lined spectroscopic binary with an orbital period of 3.32068 days.[5] 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,[7] giving it a white-hued appearance of an A-type star.[11] 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.[12]

References[edit]

  1. ^ a b c d e 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. ^ a b c d 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. ^ a b 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:1953QB901.W495...... 
  5. ^ a b 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. 
  6. ^ 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. 
  7. ^ a b c d 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. 
  8. ^ 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. 
  9. ^ "phi Aql -- Star", SIMBAD (Centre de Données astronomiques de Strasbourg), retrieved 2012-07-21. 
  10. ^ 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. 
  11. ^ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, retrieved 2012-01-16 
  12. ^ 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. 

External links[edit]