SIMBAD references

1997A&A...323..429B - Astronomy and Astrophysics, volume 323429-441 (1997/7-2)

A spectroscopic search for high azimuthal-order pulsation in broad-lined late F- and early G-stars.

BAADE D. and KJELDSEN H.

Abstract (from CDS):

During 3 consecutive nights, 13 southern F- and G-type dwarfs and giants outside the conventional δ Scuti instability strip were observed at high spectral (3km/s) and medium temporal (10-15min) resolution. The stars were selected for their reported broad spectral lines (vsini≥40km/s) so that pulsation in higher azimuthal-order nonradial harmonics could, via the rotational Doppler effect, reveal itself by line profile variability. Two stars turned out to have very narrow lines, one was confirmed as a short-period double-lined binary. Line profile ondulations typical of pulsation with azimuthal order 8≤m≤14 were detected in δ Aql and ε2 Ara. In addition, ε2 Ara displayed line profile distortions at a larger scale as they would result from a mode with m∼4. The observational sampling of all three variabilities constrains possible periods only poorly. However, if the variations are periodic, they may well be too slow for p-mode oscillations. This would suggest a relation to the new class of γ Dor variables in which g-modes seem to be excited. If so, the two stars could be the first γ Dor stars with detected higher nonradial-harmonic pulsation. While uvby photometry places δ Aql still just within the δ Scuti strip, ε2 Ara would be the reddest candidate γ Dor star to date. For the remaining 8 stars, upper amplitude limits between 2 and 6km/s were derived for nonradial mode orders 6≤m≤16 and p-modes with periods ∼20minutes. In 3 stars narrow absorption lines were detected which probably are due to a cool companion.

Abstract Copyright: ∼

Journal keyword(s): stars: oscillations - stars: δ Sct - Sun: oscillations - stars: individual: delta Aql, ε2 Ara (HD 153580)

Simbad objects: 13

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