Astron. Astrophys. 336, 518-526 (1998)

Simultaneous intensive photometry and high resolution spectroscopy of Scuti stars

III. Mode identifications and physical calibrations in HD 2724 ^*

M. Bossi ¹, L. Mantegazza ¹ and N.S. Nuñez <sup>1, 2

1</sup> Osservatorio Astronomico di Brera, Via Bianchi 46, I-23807 Merate LC, Italy
² Observatorio Astronómico P. Buenaventura Suarez, C.C. 1129, Asunción, Paraguay

Received 25 March 1998 / Accepted 25 May 1998

Abstract

On the basis of our new simultaneous photometry and spectroscopy (885 uvby differential measurements in 11 nights and 154 spectrograms of the FeII4508 region in 5 nights), we can detect 12 probable periodicities in the variability pattern of this star, determining the frequencies of 7 without any ambiguity. Through a direct fit of pulsational models to our data, we estimate the inclination of rotational axis to be about 50^o and get a reliable identification of 4 modes as well as useful bits of information about the others: no retrograde mode is visible, whereas the star seems to show a certain preference for purely sectorial prograde oscillations. Finally, the attribution of our lowest frequency to the radial fundamental pulsation allows a new calibration of physical parameters. In particular, the gravity can be determined with unusual accuracy and the luminosity evaluation becomes more consistent with the Hipparcos astrometry.

Key words: methods: data analysis stars: fundamental parameters stars: individual: HD 2724 stars: oscillations ffi Sct

* This work is based on observations performed at the European Southern Observatory (ESO), La Silla, Chile.

Send offprint requests to: M. Bossi, (bossi@merate.mi.astro.it)

© European Southern Observatory (ESO) 1998

Online publication: July 20, 1998

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