Tatyana N. Dorokhova

The Dushak-Erekdag Survey of roAp Stars

The search of roAp stars at Mt. Dushak-Erekdag Observatory was started in 1992 using the 0.8 m Odessa telescope equipped with a two-star high-speed photometer. We have observed more than a dozen stars so far and discovered HD 99563 as roAp star while BD+8087 is suspected to have rapid oscillations. Negative results of our observations for the search of rapid oscillations in four stars in NGC 752 are also discussed.

Chemical Composition and Differential Time-Series CCD Photometry of V2314 Ophiuchi: A New λ Bootis-Type Star

We investigated V2314 Oph using high-resolution (R = 45,000) spectral observations. The atmospheric parameters were determined using iron-line abundance analysis. We derived a mean effective temperature of Teff = 7510 K, mean surface gravity of log g = 3.30, metallicity of [Fe/H] = -0.59, and rotation velocity of v sin i = 38 km s-1. The abundances of 19 chemical elements were determined. The abundance pattern of V2314 Oph was found to be similar to that of λ Bootis-type stars. V2314 Oph is also a variable star, as are a majority of λ Bootis stars. A frequency analysis of 10 selected nights of precise differential photometry has preliminarily revealed four pulsational modes. The multiperiodic solution of the light curve is probably more similar to a low-amplitude Population I δ Scuti variable pattern, as is apparent for many λ Bootis stars. For asteroseismic investigations of the star it is necessary to obtain more prolonged, continuous time-series observations. These features, as well as the small proper motion and relatively large rotational velocity of V2314 Oph, specify the star as not likely to be a field SX Phoenicis Population II variable, as was suggested previously.