42 Aquilae

42 Aquilae, abbreviated 42 Aql, is a single[8] star in the equatorial constellation of Aquila. 42 Aquilae is its Flamsteed designation. It is a dim star but visible to the naked eye under suitable viewing conditions, having an apparent visual magnitude of 5.45.[2] 42 Aql is located some 104.6 light years away, as determined from its annual parallax shift of 31.2 mas.[1] it is moving closer to the Earth with a heliocentric radial velocity of −38 km/s,[4] and is predicted to come to within 52 light-years of the Sun in around 752,000 years.[2]

42 Aquilae
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila
Right ascension  19h 37m 47.31770s[1]
Declination −04° 38′ 51.5072″[1]
Apparent magnitude (V) 5.45[2]
Characteristics
Spectral type F3 IV/V[3]
B−V color index 0.429±0.003[2]
Astrometry
Radial velocity (Rv)−37.6±1.8[4] km/s
Proper motion (μ) RA: +105.381[1] mas/yr
Dec.: –53.557[1] mas/yr
Parallax (π)31.1671 ± 0.1422[1] mas
Distance104.6 ± 0.5 ly
(32.1 ± 0.1 pc)
Absolute magnitude (MV)2.98[5]
Details
Mass1.26[6] M☉
Luminosity5.76[2] L☉
Surface gravity (log g)4.00[6] cgs
Temperature6,749±80[4] K
Metallicity [Fe/H]0.17[4] dex
Rotational velocity (v sin i)87.0±4.4[5] km/s
Age1.283[6] Gyr
Other designations
42 Aql, BD−04° 4861, HD 185124, HIP 96556, HR 7460, SAO 143621[7]
Database references
SIMBADdata

The stellar classification of this star is F3 IV/V,[3] which matches an F-type star with blended spectral traits of a main sequence star and a subgiant star. It is around 1.3[6] billion years old with a relatively high rate of rotation, having a projected rotational velocity of 87 km/s.[5] The star has 1.26[6] times the mass of the Sun and is radiating 5.76[2] times the Sun's luminosity from its photosphere at an effective temperature of 6,749 K.[4] These coordinates are a source of X-ray emission, which is most likely (99.3% chance) coming from the star.[9]

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. 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.
  3. Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars", Michigan Spectral Survey, 5, Bibcode:1999MSS...C05....0H.
  4. Casagrande, L.; et al. (June 2011), "New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey", Astronomy and Astrophysics, 530: A138, arXiv:1103.4651, Bibcode:2011A&A...530A.138C, doi:10.1051/0004-6361/201016276.
  5. Ammler-von Eiff, M.; Reiners, A. (June 2012), "New measurements of rotation and differential rotation in A-F stars: are there two populations of differentially rotating stars?", Astronomy & Astrophysics, 542: A116, arXiv:1204.2459, Bibcode:2012A&A...542A.116A, doi:10.1051/0004-6361/201118724.
  6. David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146.
  7. "42 Aql". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved October 31, 2018.
  8. 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.
  9. Haakonsen, Christian Bernt; Rutledge, Robert E. (September 2009), "XID II: Statistical Cross-Association of ROSAT Bright Source Catalog X-ray Sources with 2MASS Point Source Catalog Near-Infrared Sources", The Astrophysical Journal Supplement, 184 (1): 138–151, arXiv:0910.3229, Bibcode:2009ApJS..184..138H, doi:10.1088/0067-0049/184/1/138.
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