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A&A Supplement series, Vol. 122, April I 1997, 131-147

Received January 2; accepted July 19, 1996

Spectroscopic survey of tex2html_wrap_inline2167 Scuti stars

I. Rotation velocities and effective temperaturesgif

E.  Solanotex2html_wrap2205 - J.  Fernleytex2html_wrap2207

Send offprint request: E. Solano;

tex2html_wrap2209  INSA, ESA-IUE Observatory, P.O. Box 50727, 28080 Madrid, Spain
tex2html_wrap2211  IUE Observatory, P.O. Box 50727, 28080 Madrid, Spain


Projected rotational velocities and effective temperatures for tex2html_wrap_inline2171 Sct stars as well as 41 non-variable stars of similar spectral type and luminosity are presented here. The rotational velocities have been calculated following the method developed in Gray (1992) and effective temperatures have been derived using the Balmer line profiles. The temperatures obtained from this method are shown to be in reasonable agreement with those calculated using the Infrared Flux Method (IRFM) or spectrophotometric methods. This result has allowed us to use our temperatures to compare different tex2html_wrap_inline2173 photometric calibrations. We find that the calibration given by Moon & Dworetsky (1985) is the most consistent. In the second part of this paper we have studied the relation between the pulsational properties (periods and amplitudes) and the physical parameters (tex2html_wrap_inline2175 and tex2html_wrap_inline2177). Where pulsation modes have been determined, the low amplitude tex2html_wrap_inline2179 Scutis tend to be multimode (radial and non-radial) pulsators, consistent with the theory that non-linear coupling between modes acts to limit the amplitude in these stars. We have compared the distribution of tex2html_wrap_inline2181 for low amplitude tex2html_wrap_inline2183 Scutis and non-variable stars. This shows the tex2html_wrap_inline2185 Scutis have a broader distribution in tex2html_wrap_inline2187 suggesting that a high rotation velocity may favour pulsation. We find that the large amplitude tex2html_wrap_inline2189 Scuti stars tend to have longer periods, cooler temperatures and lower rotation velocities. Given that the large amplitude stars are also relatively rare all the above are consistent with the hypothesis that these stars are more evolved (sub-giants) than the low amplitude tex2html_wrap_inline2191 Scutis (main sequence or early post-main sequence).

keywords: stars: rotation -- stars: fundamental parameters -- stars: variables: tex2html_wrap_inline2193 Sct

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