U Aquilae

From Wikipedia, the free encyclopedia
Jump to: navigation, search
U Aquilae
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila
Right ascension 19h 29m 21.3603s[1]>
Declination −07° 02′ 38.710″[1]
Apparent magnitude (V) 6.61[2] (6.08 - 6.86[3])
Spectral type F5-G1 I-II[4] + B9.8V[5]
U−B color index 0.70[2]
B−V color index 1.10[2]
Variable type δ Cep[3]
Radial velocity (Rv) -6.5[1] km/s
Proper motion (μ) RA: -0.99[1] mas/yr
Dec.: -9.14[1] mas/yr
Parallax (π) 3.63 ± 0.96[1] mas
Distance 614[5] pc
Absolute magnitude (MV) −3.68[5]
Period (P) 1,856
Semi-major axis (a) 1.311"
(6.1 AU)
Eccentricity (e) 0.165
Inclination (i) 74°
Longitude of the node (Ω) 190°
Mass 5.7[5] M
Radius 55[6] R
Luminosity 2,570[5] L
Surface gravity (log g) 1.3[7] cgs
Temperature 5,440-6,640[7] K
Metallicity [Fe/H] 0.17[8] dex
Mass 2.3[5] M
Radius 2.1[6] R
Temperature 9,300[6] K
Other designations
GCRV 11912, IDS 19240-0715, TYC 5143-1372-1, IRAS 19266-0708, UBV M 23815, ADS 12503, GSC 05143-01372, LS IV -07 35, UBV 21626, ALS 10306, HD 183344, 2MASS J19292135-0702387, uvby98 100183344 ABV, BD-07°4968, PLX 4556, YZ 97 6771, CCDM J19294-0703, PPM 202954, AAVSO 1924-07, CSI-07 4968 1, HIP 95820, SAO 143454, GC 26905, HR 7402
Database references
Data sources:
Hipparcos Catalogue,
CCDM (2002),
Bright Star Catalogue (5th rev. ed.)

U Aquilae is a binary star system in the constellation Aquila, Located approximately 614 parsecs (2,000 ly) away from Earth.

The primary star (component A) is a yellow supergiant with a radius of 55 R and a luminosity of 2,570 L. The secondary (component B) is a blue main-sequence star, twice the mass of the sun and around thirty times more luminous. It is hotter than the primary star at 9,300 K, but much smaller and fainter. The two stars orbit every five years and their separation varies from five to seven astronomical units in a mildly eccentric orbit.

u Aql A is a classical Cepheid variable star ranging between magnitudes 6.08 and 6.86 over a period of 7.02 days. It is an evolved star which has exhausted its core hydrogen and is now fusing helium into carbon.[9]


  1. ^ a b c d e f Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. 
  2. ^ a b c Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237: 0. Bibcode:2002yCat.2237....0D. 
  3. ^ a b Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/gcvs. Originally published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S. 
  4. ^ Simpson, P. (2012). "The Eagle and its Errands". Guidebook to the Constellations. Patrick Moore's Practical Astronomy Series. p. 373. doi:10.1007/978-1-4419-6941-5_9. ISBN 978-1-4419-6940-8. 
  5. ^ a b c d e f Evans, Nancy Remage (2013). "BINARY CEPHEIDS: SEPARATIONS AND MASS RATIOS IN 5 M ☉ BINARIES". The Astronomical Journal. 146 (4): 93. arXiv:1307.7123Freely accessible. Bibcode:2013AJ....146...93R. doi:10.1088/0004-6256/146/4/93. 
  6. ^ a b c d Welch, D. L.; Evans, N. R.; Lyons, R. W.; Harris, H. C.; Barnes, T. G. , I. I.; Slovak, M. H.; Moffett, T. J. (1987). "The orbit of the classical Cepheid U Aquilae". Publications of the Astronomical Society of the Pacific. 99: 610. Bibcode:1987PASP...99..610W. doi:10.1086/132022. 
  7. ^ a b Kiss, L. L.; Szatmary, K. (1998). "A photometric and spectroscopic study of the brightest northern Cepheids -- II. Fundamental physical parameters". Monthly Notices of the Royal Astronomical Society. 300 (2): 616. Bibcode:1998MNRAS.300..616K. doi:10.1046/j.1365-8711.1998.01943.x. 
  8. ^ Groenewegen, M. A. T. (2013). "Baade-Wesselink distances to Galactic and Magellanic Cloud Cepheids and the effect of metallicity". Astronomy & Astrophysics. 550: A70. arXiv:1212.5478Freely accessible. Bibcode:2013A&A...550A..70G. doi:10.1051/0004-6361/201220446. 
  9. ^ Kiss, L. L. (1998). "A photometric and spectroscopic study of the brightest northern Cepheids -- I. Observations". Monthly Notices of the Royal Astronomical Society. 297 (3): 825. Bibcode:1998MNRAS.297..825K. doi:10.1046/j.1365-8711.1998.01559.x.