27 Aquilae
27 Aquilae (abbreviated 27 Aql) is a star in the equatorial constellation of Aquila. 27 Aquilae is its Flamsteed designation though it also bears the Bayer designation d Aquilae. 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]
| 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 mas[1] |
| Distance | 440 ± 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 |
| Temperature | 11,500[6] K |
| Rotational velocity (v sin i) | 55[7] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
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 edit
- ^ 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, S2CID 18759600.
- ^ a b c d Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
- ^ a b 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.
- ^ Wilson, Ralph Elmer (1953), "General catalogue of stellar radial velocities", Carnegie Institute Washington D.C. Publication, Carnegie Institution of Washington, Bibcode:1953GCRV..C......0W.
- ^ a b van Belle, G. T.; et al. (PTI Collaboration) (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, S2CID 10713221.
- ^ a b c d 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, S2CID 54028925.
- ^ a b 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.
- ^ "d Aql". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-21.
- ^ 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, S2CID 54570565.