27 Aquilae

27 Aquilae
Diagram showing star positions and boundaries of the Aquila constellation and its surroundings


Location of 27 Aquilae (circled)

Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Aquila
Right ascension 19h 20m 35.68321s[1]
Declination −00° 53′ 31.8067″[1]
Apparent magnitude (V) 5.49[2]
Characteristics
Spectral type B9 III[3]
U−B color index −0.23[2]
B−V color index −0.04[2]
Astrometry
Radial velocity (Rv)−27[4] km/s
Proper motion (μ) RA: 5.42[1] mas/yr
Dec.: 2.83[1] mas/yr
Parallax (π)7.45 ± 0.28[1] mas
Distance440 ± 20 ly
(134 ± 5 pc)
Absolute bolometric
magnitude (Mbol)		2.04–2.27[5]
Details
Surface gravity (log g)3.61 ± 0.50[6] cgs
Temperature11,500[6] K
Rotational velocity (v sin i)55[7] km/s
Other designations
27 Aql, d Aquilae, d Aql, BD−01 3716, GC 26673, HD 181440, HIP 95073, HR 7336, PPM 180629, SAO 143292.[8]

27 Aquilae (27 Aql) is the Flamsteed designation for a star in the equatorial constellation of Aquila. It has an apparent visual magnitude of 5.49,[2] which is faintly visible to the naked eye. Based upon parallax measurements made during the Hipparcos mission, this star is at a distance of 440 light-years (130 parsecs) from Earth, give or take a 20 light-year margin of error.[1] At this distance, the brightness of the star is diminished from extinction caused by interstellar gas and dust.[5]

The spectrum of 27 Aquilae fits a stellar classification of B9 III,[3] with the luminosity class of III typically indicating this is an evolved giant star. As it lies within the field of view of the CoRoT satellite,[6] close observation have been made of its luminosity. The star shows a multiperiodic variability with at least six pulsation frequencies discovered.[9] It has a high rate of rotation with a projected rotational velocity of 55 km/s.[7] The outer atmosphere is radiating energy into space at an effective temperature of around 11,500 K,[6] giving it the blue-white hue of a B-type star.

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 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. ↑ 2.0 2.1 2.2 2.3 Johnson, H. L. et al. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory 4 (99). Bibcode:1966CoLPL...4...99J.
  3. ↑ 3.0 3.1 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.
  4. ↑ Wilson, Ralph Elmer (1953), General catalogue of stellar radial velocities, Carnegie Institution of Washington, Bibcode:1953QB901.W495......
  5. ↑ 5.0 5.1 van Belle, G. T. et al. (May 2008), "The Palomar Testbed Interferometer Calibrator Catalog", The Astrophysical Journal Supplement Series 176 (1): 276–292, arXiv:0711.4194, Bibcode:2008ApJS..176..276V, doi:10.1086/526548.
  6. ↑ 6.0 6.1 6.2 6.3 Lefever, K. et al. (June 2010), "Spectroscopic determination of the fundamental parameters of 66 B-type stars in the field-of-view of the CoRoT satellite", Astronomy and Astrophysics 515: A74, arXiv:0910.2851, Bibcode:2010A&A...515A..74L, doi:10.1051/0004-6361/200911956.
  7. ↑ 7.0 7.1 Abt, Helmut A.; Levato, Hugo; Grosso, Monica (July 2002), "Rotational Velocities of B Stars", The Astrophysical Journal 573 (1): 359–365, Bibcode:2002ApJ...573..359A, doi:10.1086/340590.
  8. ↑ "d Aql -- Star", SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), retrieved 2012-07-21.
  9. ↑ Degroote, P. et al. (December 2011), "CoRoT's view on variable B8/9 stars: spots versus pulsations. Evidence for differential rotation in HD 174648", Astronomy & Astrophysics 536: A82, arXiv:1110.5601, Bibcode:2011A&A...536A..82D, doi:10.1051/0004-6361/201116802.