THE ORBIT OF THE CLASSICAL CEPHEID U AQUILAE

A total of 62 new radial-velocity observations ofthe classical Cepheid U Aql have been obtained during the interval 1969-86. We present the first determination of a spectroscopic binary orbit for this star. The orbital elements derived from both new and published velocities are: P= 1856.4 ± 4.3 days...

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Bibliographic Details
Published in:Publications of the Astronomical Society of the Pacific 1987-07, Vol.99 (617), p.610-616
Main Authors: WELCH, DOUGLAS L., EVANS, NANCY R., LYONS, RON W., HARRIS, HUGH C., BARNES, THOMAS G., SLOVAK, MARK H., MOFFETT, THOMAS J.
Format: Article
Language:English
Subjects:
Astronomy
Cepheids
Cepheids (delta cephei, w virginis)
Earth, ocean, space
Ephemerides
Exact sciences and technology
Observatories
Orbital elements
Orbital evolution
Orbital velocity
Phase shift
Radial velocity
Stars
Telescopes
Variable and peculiar stars (including novae)
Wavelengths
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Summary:A total of 62 new radial-velocity observations ofthe classical Cepheid U Aql have been obtained during the interval 1969-86. We present the first determination of a spectroscopic binary orbit for this star. The orbital elements derived from both new and published velocities are: P= 1856.4 ± 4.3 days K1 = 7.81 ± 0.22 km s−1 γ =1.15 ± 0.15 km s−1 e = 0.165 ± 0.027 ω = 190.5 ± 7.7 deg T = 2442754 ± 38 JD a1 sin i = 196.7 ± 5.5 Gm = 1.311 ± 0.037 AU f(m) = 0.0881 ± 0.0074 M⊙ IUE observations reported by Böhm-Vitense and Proffitt (1985) indicate the presence of an early-type main-sequence companion. The orbital elements combined with estimates ofthe companion mass result in upper limits for the mass of the Cepheid in the range 6.4-8.8 M⊙. The possibility of spatially resolving the system using interferometric techniques is discussed.
ISSN:0004-6280
1538-3873
DOI:10.1086/132022