15 Aquilae

15 Aquilae (abbreviated 15 Aql) is a star in the equatorial constellation of Aquila. 15 Aquilae is the Flamsteed designation; it also bears the Bayer designation h Aquilae. The apparent visual magnitude is 5.41,^[2] so it is faintly visible to the naked eye. An optical companion, HD 177442, is 39 arc seconds away from it^[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.

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]
Characteristics
Spectral type	K1 III[3]
U−B color index	+1.01[2]
B−V color index	+1.12[2]
Astrometry
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 mas[1]
Distance	289 ± 9 ly (89 ± 3 pc)
Absolute magnitude (MV)	0.414[5]
Details
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 Aquilae, BD–04° 4684, HD 177463, HIP 93717, HR 7225, SAO 142996.[6]
Database references
SIMBAD	data

With a stellar classification of K1 III,^[3] the spectrum of 15 Aquilae matches a giant star with an 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 Center, 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]

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. 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. 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, arXiv:0911.0760, Bibcode:2009A&A...508.1313F, doi:10.1051/0004-6361/200913327, S2CID 118361131.
4. 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, S2CID 121883397.
5. 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, S2CID 16602121.
6. "15 Aql", SIMBAD, 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, S2CID 14878976.
8. "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on February 22, 2012, retrieved 2012-07-21.

External links

• Image 15 Aquilae