Astronomy:Phi Aquilae

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Short description: Binary star system in the constellation Aquila
Phi Aquilae
Location of φ Aquilae (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Aquila[1]
Right ascension  19h 56m 14.252s[2]
Declination +11° 25′ 25.40″[2]
Apparent magnitude (V) +5.28[3]
Characteristics
Spectral type A1 IV[4] + K1 V to M1 V[5]
U−B color index −0.02[3]
B−V color index +0.00[3]
Astrometry
Radial velocity (Rv)−27.2±0.9[6] km/s
Proper motion (μ) RA: +32.745[2] mas/yr
Dec.: +5.630[2] mas/yr
Parallax (π)14.7474 ± 0.0869 mas
Distance221 ± 1 ly
(67.8 ± 0.4 pc)
Absolute magnitude (MV)+1.14[1]
Orbit[5]
Period (P)3.320669±0.000017 d
Eccentricity (e)0
Periastron epoch (T)2459445.0916±0.0011 JD
Argument of periastron (ω)
(secondary)		43[7]°
Semi-amplitude (K1)
(primary)		36.48±0.07 km/s
Details
A
Mass2.39[8] M☉
Radius1.8–2.5[9] R☉
Luminosity28.2+0.6−0.7[5] L☉
Surface gravity (log g)4.30[10] cgs
Temperature9,484±13[5] K
Metallicity [Fe/H]+0.47[10] dex
Rotational velocity (v sin i)27[11] km/s
Age280[8] Myr
B
Mass0.40[8] M☉
Other designations
φ Aquilae, φ Aql, 61 Aql, BD+11°4055, FK5 3590, GC 27604, HD 188728, HIP 98103, HR 7610, SAO 105438, PPM 137250, WDS J19562+1125AB[12]
Database references
SIMBADdata

Phi Aquilae is a binary star[13] system in the equatorial constellation of Aquila. Its name is a Bayer designation that is Latinized from φ Aquilae, and abbreviated Phi Aql or φ Aql. The system has an apparent visual magnitude of +5.28[3] and is visible to the naked eye as a faint point of light. With an annual parallax shift of 14.7 mas,[2] this star is located at a distance of approximately 221 light-years (68 parsecs) from Earth. It is drifting closer with a radial velocity of −27 km/s.[6] Based on its motion through space, this system is a candidate member of the nearby Argus association of co-moving stars, although it may be too old.[14]

Phi Aquilae is a single-lined spectroscopic binary with an orbital period of 3.32067 days.[5] The pair have a projected separation of 190.4 astronomical unit|AU as of 2008.[8] The primary component is a subgiant star with a stellar classification of A1 IV.[4] The star is around 280[8] million years old and is spinning with a projected rotational velocity of 27 km/s.[11] It has 2.39[8] times the mass of the Sun and somewhere in the range of 1.8–2.5[9] times the Sun's radius. The outer atmosphere has an effective temperature of 9,509 K,[10] giving it the white-hued appearance of an A-type star.[15] It is radiating 34[1] 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.[16] It has 40% of the mass of the Sun.[8] Based on photometric data from the TESS mission, the pair may undergo grazing eclipses. This implies an orbital inclination of at least 79°, and constrains the mass of the secondary to 0.5 M☉.[5]

A third component of this system was detected during the VAST survey. This faint component lies at an angular separation of 2.83 arcseconds, for a projected separation of 190 astronomical unit|AU and an estimated orbital period of over 1,500 years.[5]

References

  1. ↑ 1.0 1.1 1.2 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A. 
  2. ↑ 2.0 2.1 2.2 2.3 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  3. ↑ 3.0 3.1 3.2 3.3 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. 
  4. ↑ 4.0 4.1 Cowley, A. et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal 74: 375–406, doi:10.1086/110819, Bibcode: 1969AJ.....74..375C. 
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 Miroshnichenko, Anatoly S. et al. (January 2023), "Refining Orbits of Bright Binary Systems", Galaxies 11 (1): id. 8, doi:10.3390/galaxies11010008, Bibcode: 2023Galax..11....8M. 
  6. ↑ 6.0 6.1 Wilson, Ralph Elmer (1953), "General catalogue of stellar radial velocities", Carnegie Institute Washington D.C. Publication (Carnegie Institution of Washington), Bibcode: 1953GCRV..C......0W. 
  7. ↑ Lucy, L. B.; Sweeney, M. A. (August 1971), "Spectroscopic binaries with circular orbits", Astronomical Journal 76: 544–556, doi:10.1086/111159, Bibcode: 1971AJ.....76..544L. 
  8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 8.6 De Rosa, R. J. et al. (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, doi:10.1093/mnras/stt1932, Bibcode: 2014MNRAS.437.1216D. 
  9. ↑ 9.0 9.1 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, doi:10.1051/0004-6361:20000451, Bibcode: 2001A&A...367..521P. 
  10. ↑ 10.0 10.1 10.2 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, doi:10.1051/0004-6361/201014247, Bibcode: 2010A&A...515A.111S. 
  11. ↑ 11.0 11.1 Royer, F. et al. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics 463 (2): 671–682, doi:10.1051/0004-6361:20065224, Bibcode: 2007A&A...463..671R. 
  12. ↑ "phi Aql". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=phi+Aql. 
  13. ↑ 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, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E. 
  14. ↑ Zuckerman, B. (January 2019), "The Nearby, Young, Argus Association: Membership, Age, and Dusty Debris Disks", The Astrophysical Journal 870 (1): 8, doi:10.3847/1538-4357/aaee66, 27, Bibcode: 2019ApJ...870...27Z. 
  15. ↑ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html, retrieved 2012-01-16 
  16. ↑ 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, doi:10.1111/j.1365-2966.2011.18765.x, Bibcode: 2011MNRAS.415..854D. 



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