71 Aquilae

"l Aquilae" redirects here. Not to be confused with Lambda Aquilae or L'Aquila.

71 Aquilae

Location of 71 Aquilae (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Aquila
Right ascension	20^h 38^m 20.28206^s[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 mas[1]
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
BD-01 4016, HD 196574, HIP 101847, HR 7884, SAO 144649.[9]
Database references
SIMBAD	data

71 Aquilae (abbreviated 71 Aql) is a binary star in the equatorial constellation of Aquila. 71 Aquilae is its Flamsteed designation though it also bears the Bayer designation l Aquilae. 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 spectral lines 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

1. 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, S2CID 18759600.
2. Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
3. 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 Washington D.C. Publication, Carnegie Institute of Washington, D.C., Bibcode:1953GCRV..C......0W.
5. 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, S2CID 17821279.
6. 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, S2CID 15123997.
7. 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): 1, Bibcode:1970CoAsi.239....1B.
9. "* l Aql". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-23.