45 Aquilae

45 Aquilae, abbreviated 45 Aql, is a triple star system in the equatorial constellation of Aquila. 45 Aquilae is its Flamsteed designation. It is located 350 light-years (110 parsecs) away from Earth, give or take a 6 light-year margin of error, and has a combined apparent visual magnitude of 5.7.^[2] The system is moving closer to the Earth with a heliocentric radial velocity of -46 km/s.^[5]

45 Aquilae

Observation data Epoch J2000      Equinox J2000
Constellation	Aquila
Right ascension	19h 40m 43.31912s[1]
Declination	–00° 37′ 16.3868″[1]
Apparent magnitude (V)	5.656[2] (5.9 + 7.6)[3]
Characteristics
Spectral type	A3 IV[4]
U−B color index	+0.09[2]
B−V color index	+0.11[2]
Astrometry
Radial velocity (Rv)	-46[5] km/s
Proper motion (μ)	RA: +15.683[1] mas/yr Dec.: +5.323[1] mas/yr
Parallax (π)	9.3151 ± 0.1561 mas[1]
Distance	350 ± 6 ly (107 ± 2 pc)
Absolute magnitude (MV)	0.49[6]
Orbit[7]
Primary	5 Aql Aa
Companion	5 Aql Ab
Period (P)	20.31 ± 0.17 yr
Semi-major axis (a)	0.0850 ± 0.0020″
Eccentricity (e)	0.054 ± 0.047
Inclination (i)	158.3 ± 7.9°
Longitude of the node (Ω)	202.0 ± 15.0°
Periastron epoch (T)	1996.06 ± 0.92
Argument of periastron (ω) (secondary)	346.0 ± 25.0°
Details
45 Aql Aa
Mass	2.63±0.10[8] M☉
Luminosity	75.8+13.8 −11.7[8] L☉
Temperature	9,016+167 −165[8] K
Rotational velocity (v sin i)	75[8] km/s
Other designations
45 Aql, BD−00° 3813, FK5 3573, HD 185762, HIP 96807, HR 7480, SAO 14367, WDS J19407-0037[9]
Database references
SIMBAD	data

Based upon a stellar classification of A3 IV,^[4] the primary component of this system is a subgiant star that is in the process of evolving away from the main sequence. The star has 2.6^[8] times the mass of the Sun and is spinning with a projected rotational velocity of 75 km/s.^[8] It has an orbiting companion with a period of 20.31 years and an eccentricity of 0.054. At an angular separation of 42.2 arcseconds from this pair is a 12.7 magnitude tertiary companion.^[10]

References

1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051.
2. Nicolet, B. (1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System", Astronomy and Astrophysics Supplement Series, 34: 1–49, Bibcode:1978A&AS...34....1N.
3. Malkov, O. Yu.; et al. (2012), "Dynamical Masses of a Selected Sample of Orbital Binaries", Astronomy and Astrophysics, 546: 5, Bibcode:2012A&A...546A..69M, doi:10.1051/0004-6361/201219774, A69.
4. 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.
5. Wilson, Ralph Elmer (1953), "General catalogue of stellar radial velocities", Carnegie Institute Washington D.C. Publication, Carnegie Institution of Washington, Bibcode:1953GCRV..C......0W.
6. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
7. Mason, Brian D.; Hartkopf, William I.; Tokovinin, Andrei (September 2010), "Binary Star Orbits. IV. Orbits of 18 Southern Interferometric Pairs", The Astronomical Journal, 140 (3): 735–743, Bibcode:2010AJ....140..735M, doi:10.1088/0004-6256/140/3/735.
8. Zorec, J.; Royer, F. (2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789.
9. "* 45 Aql". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-26.
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. S2CID 14878976.

External links

• HR 7480
• CCDM 19407-0037
• Image 45 Aquilae