71 Aquilae

From Wikipedia, the free encyclopedia
Jump to: navigation, search
"l Aquilae" redirects here. It is not to be confused with Lambda Aquilae or L'Aquila.
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]
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
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]
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)
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]


  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]