15 Aquilae

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15 Aquilae
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila
Right ascension 19h 04m 57.67233s[1]
Declination –04° 01′ 53.1059″[1]
Apparent magnitude (V) 5.41[2]
Spectral type K1 III[3]
U−B color index +1.01[2]
B−V color index +1.12[2]
Radial velocity (Rv) –23.17 ± 0.61[4] km/s
Proper motion (μ) RA: +21.90[1] mas/yr
Dec.: -26.05[1] mas/yr
Parallax (π) 11.27 ± 0.36[1] mas
Distance 289 ± 9 ly
(89 ± 3 pc)
Absolute magnitude (MV) 0.414[5]
Radius 14[4] R
Luminosity 83[4] L
Surface gravity (log g) 2.65[3] cgs
Temperature 4,560[3] K
Metallicity [Fe/H] –0.25[3] dex
Rotational velocity (v sin i) 3.4[4] km/s
Age 4.09 ± 2.07[5] Gyr
Other designations
h Aql, 15 Aql, BD–04 4684, HD 177463, HIP 93717, HR 7225, SAO 142996.[6]

15 Aquilae is the Flamsteed designation for a star in the equatorial constellation of Aquila. It has the Bayer designation h Aquilae. The apparent visual magnitude of this star is 5.41,[2] meaning that it is faintly visible to the naked eye. It has a nearby optical companion, HD 177442.[7] The distance to 15 Aquilae can be estimated from its annual parallax shift of 11.27 mas,[1] yielding a range of approximately 289 light-years (89 parsecs) from Earth with a 9 light-year margin of error.

With a stellar classification of K1 III,[3] the spectrum of 15 Aquilae matches a giant star with an estimated age of roughly four billion years.[5] At this stage of its evolution, the outer atmosphere of the star has expanded to 14[4] times the radius of the Sun. It is radiating 83[4] times the Sun's luminosity into space at an effective temperature of 4,560 K.[3] This heat gives it the orange-hued glow of a K-type star.[8]

This star is most likely a member of the thin disk population of the Milky Way. It is orbiting through the galaxy with an eccentricity of 0.06, which carries it as close as 24.30 kly (7.45 kpc) to the Galactic Core, and as far away as 27.60 kly (8.46 kpc). The orbital inclination carries it no more than 196 ly (60 pc) from the galactic plane.[5]


  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 Cousins, A. W. J. (1964), "Photometric Data for Stars in the Equatorial Zone (Seventh List)", Monthly Notes of the Astronomical Society of Southern Africa 23: 175, Bibcode:1964MNSSA..23..175C. 
  3. ^ a b c d e f Frasca, A. et al. (December 2009), "REM near-IR and optical photometric monitoring of pre-main sequence stars in Orion. Rotation periods and starspot parameters", Astronomy and Astrophysics 508 (3): 1313–1330, Bibcode:2009A&A...508.1313F, doi:10.1051/0004-6361/200913327. 
  4. ^ a b c d e f Massarotti, Alessandro et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209. 
  5. ^ a b c d Soubiran, C. et al. (2008), "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants", Astronomy and Astrophysics 480 (1): 91–101, arXiv:0712.1370, Bibcode:2008A&A...480...91S, doi:10.1051/0004-6361:20078788. 
  6. ^ "h Aql -- Star in double system", SIMBAD Astronomical Object Database (Centre de Données astronomiques de Strasbourg), retrieved 2012-07-22. 
  7. ^ 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. 
  8. ^ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, retrieved 2012-07-21. 

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