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Astron. Astrophys. 331, 995-1001 (1998)
Pulsating and nonpulsating stars in Hyades observed by Hipparcos satellite *
E. Antonello 1 and
L.E. Pasinetti Fracassini 2
1 Osservatorio Astronomico di Brera, Via E. Bianchi
46, I-22055 Merate, Italy (elio@merate.mi.astro.it)
2 Dipartimento di Fisica, Università degli Studi di
Milano, Via Celoria 16, I-20133 Milano, Italy
(pasinetti@mi.infn.it)
Received 2 October 1997 / Accepted 18 November 1997
Abstract
A study of the stars in the instability strip of Hyades cluster has
been performed taking into account the new estimate of the stellar
parallaxes. For taking advantage of the improved accuracy of the
distances and hence absolute magnitudes it is necessary to separate
the photometric effects of close companions, which appear quite common
in Hyades. The ![[FORMULA]](img1.gif)
Scuti stars, differently from
nonpulsating stars, appear to be located also above the main sequence,
and this is due probably to their large rotational velocity. The
comparison of the rotational effects on the star position in the
color-magnitude diagram with theoretical model predictions tends to
confirm the importance of differential rotation. A brief discussion of
![[FORMULA]](img2.gif)
Tau and some remarks on the X-ray emission of
other two Scuti stars are also reported.
Key words: binaries:
general 
stars:
distances
stars: fundamental
parameters
stars: rotation
open clusters and associations: individual: Mel 25
* Based on data from Hipparcos astrometry satellite
Send offprint requests to: E. Antonello
Contents
- 1. Introduction
- 2. Stars
- 3. Discussion
- 3.1. Membership
- 3.2. Color-magnitude diagram
- 3.3. Variable and nonvariable stars
- 4. Conclusion
- Acknowledgements
- References
© European Southern Observatory (ESO) 1998
Online publication: March 3, 1998
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