Theta Tucanae: a binary with a Scuti primary *
K. De Mey 1,
** 1 and
Received 26 January 1998 / Accepted 11 March 1998
Using seven four-hour time series of high-resolution spectra, the binary nature and the oscillations of Tuc are investigated. The spectrum is double-lined, proving the binarity. Tuc is a binary with a circular orbit and with an anomalous mass ratio q=0.09. The for the first time determined orbital elements are P=7.1036 days, =8.6 km/s and =95.6 km/s.
The oscillations of the Scuti-type main component are spectroscopically investigated. Line-profile variations are discovered, and radial-velocity variations reveal a main oscillation frequency of =20.27 c/d which corresponds to the main oscillation 20.2806 c/d in photometry. Another frequency, =18.82 c/d found in the spectroscopic data and not present in the photometric dataset, needs to be investigated more profoundly.
Key words: stars: binaries: spectroscopic stars: individual: Tuc stars: oscillations stars: variables: ffi Sct
* Based on observations collected at the European Southern Observatory, La Silla, Chile. (Observing proposals 57 E-0269 and 58 D-0150)
© European Southern Observatory (ESO) 1998
Online publication: July 20, 1998