The orbit and companions of the classical Cepheid FF Aql
- York Univ., North York (Canada) Computer Sciences Corp., Silver Spring, MD (USA) McMaster Univ., Hamilton (Canada) Victoria Univ. (Canada) Computer Sciences Corp., Lanham, MD (USA)
New radial velocities of the classical Cepheid FF Aql have been obtained and combined with previous observations to provide a revised orbit. A companion has been detected at 1800 A in IUE spectra with a spectral type of A9 V to F3 V. If the Cepheid has an evolutionary mass, then the mass ratio is M1/M2 = 3.8. A companion recently detected by speckle interferometry is in a longer-period orbit if it is a physical companion. In this case it is also an evolved star. The possible fourth member of the system, the visual companion, is unlikely to be a member of the system. The companion at 6 arcsec is unlikely to be a physical companion. Cepheids (in the 'free-fall' descending branch of the light curve) and nonvariable supergiants are shown to have a different spectral slope between 2900 and 1800 A for the same (B-V)0. IUE spectra of Polaris are rediscussed using other Cepheid spectra as comparison stars, and it is concluded that there is probably no sign of a companion. 44 refs.
- OSTI ID:
- 6700700
- Journal Information:
- Astronomical Journal; (USA), Vol. 99; ISSN 0004-6256
- Country of Publication:
- United States
- Language:
- English
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GENERAL PHYSICS
CEPHEIDS
ORBITS
BINARY STARS
INTERFEROMETRY
LUMINOSITY
MASS
RADIAL VELOCITY
STAR EVOLUTION
SUPERGIANT STARS
ULTRAVIOLET SPECTRA
GIANT STARS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PULSATING VARIABLE STARS
SPECTRA
STARS
VARIABLE STARS
VELOCITY
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
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