71 Aquilae

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71 Aquilae
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila
Right ascension 20h 38m 20.28206s[1]
Declination −01° 06′ 18.4311″[1]
Apparent magnitude (V) 4.33[2]
Characteristics
Spectral type G8 III[3]
U−B color index +0.68[2]
B−V color index +0.96[2]
R−I color index 0.46
Astrometry
Radial velocity (Rv) -5.6[4] km/s
Proper motion (μ) RA: +14.84[1] mas/yr
Dec.: -16.45[1] mas/yr
Parallax (π) 9.67 ± 0.75[1] mas
Distance 340 ± 30 ly
(103 ± 8 pc)
Absolute magnitude (MV) –1.03[5]
Orbit[6]
Period (P) 205.2 days
Semi-major axis (a) 3.82 ± 0.81 mas
Eccentricity (e) 0.000
Inclination (i) 147.70° ± 5.90°
Longitude of the node (Ω) 314.00 ± 1.30°
Periastron epoch (T) 2423358.0 HJD
Argument of periastron (ω)
(secondary)
0.00°
Details
Surface gravity (log g) 2.87[7] cgs
Temperature 5,060[7] K
Metallicity [Fe/H] –0.13[7] dex
Rotational velocity (v sin i) 10[8] km/s
Other designations
l Aql, BD-01 4016, HD 196574, HIP 101847, HR 7884, SAO 144649.[9]

71 Aquilae is the Flamsteed designation for a binary star in the equatorial constellation of Aquila. It has the Bayer designation l Aquilae (l Aql). The apparent visual magnitude of the system is 4.33,[2] making it bright enough to be viewed by the naked eye. It has an annual parallax shift of 9.67 mas,[1] which equates to a physical distance of 340 light-years (100 parsecs) from Earth, give or take a 30 light-year margin of error. At this distance, the brightness of the system is diminished by 0.065 in visual magnitude from extinction caused by interstellar gas and dust.[5]

This is a spectroscopic binary system where the presence of an orbiting companion is revealed by shifts in the spectrum caused by the Doppler effect. The primary component is a giant star with a stellar classification of G8 III.[3] The secondary is following a circular orbit with a period of 205.2 days.[6]

References[edit]

  1. ^ a b c d e f 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 Johnson, H. L. et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory 4 (99), Bibcode:1966CoLPL...4...99J. 
  3. ^ a b Herbig, George H.; Spalding, John F., Jr. (January 1955), "Axial Rotation and Line Broadening in Stars of Spectral Types F0-K5", Astrophysical Journal 121: 118, Bibcode:1955ApJ...121..118H, doi:10.1086/145969. 
  4. ^ Wilson, R. E. (1953), General Catalogue of Stellar Radial Velocities, Carnegie Institute of Washington, D.C., Bibcode:1953GCRV..C......0W. 
  5. ^ a b Ryon, Jenna; Shetrone, Matthew D.; Smith, Graeme H. (August 2009), "Comparing the Ca ii H and K Emission Lines in Red Giant Stars", Publications of the Astronomical Society of the Pacific 121 (882): 842–856, arXiv:0907.3346, Bibcode:2009PASP..121..842R, doi:10.1086/605456. 
  6. ^ a b Jancart, S. et al. (October 2005), "Astrometric orbits of SB^9 stars", Astronomy and Astrophysics 442 (1): 365–380, arXiv:astro-ph/0507695, Bibcode:2005A&A...442..365J, doi:10.1051/0004-6361:20053003. 
  7. ^ a b c McWilliam, Andrew (December 1990), "High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances", Astrophysical Journal Supplement Series 74: 1075–1128, Bibcode:1990ApJS...74.1075M, doi:10.1086/191527. 
  8. ^ Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", Contributi Osservatorio Astronomico di Padova in Asiago 239 (1), Bibcode:1970CoAsi.239....1B. 
  9. ^ "l Aql -- Star", SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), retrieved 2012-07-23. 

External links[edit]