Abstract
view Abstract Citations (45) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Main-Sequence Pulsation in Open Clusters Breger, Michel Abstract Studies of short-period pulsation in open clusters show that pulsation occurs in clusters of all ages provided stars are present in the instability strip (A2 V-F0 V). This includes -sequence stars. The value of the pulsation constant Q is similar in the clusters studied, i.e., (Q) = 0.026 days. This points toward pulsation in the first overtone. About 30 percent of the main-sequence cluster stars inside the instability strip show detectable variability. Hyades-type stars may show a particularly high incidence of pulsation, possibly connected to a high helium abundance. Statistically extremely significant correlations between slow rotation, metallicity, and pulsational stability are established for different clusters. The observed relations can be explained by a diffusion hypothesis: (i) Slowly rotating A dwarfs usually possess extreme stability in some subsurface zones which causes element segregation. This leads to metallicism as well as increased pulsational stability because of the low helium content iii the critical He ii ionization zone. (ii) Low rotation, however, is not a sufficient condition to cause metallicism. Some examples are given. These slow rotators may, and often do, pulsate. (ili) Dwarfs with rotational velocities greater than 100 km 1 may pulsate and do not become Am stars. These stars, however, are so close to stability that less than 50 percent have detectable variability. Publication: The Astrophysical Journal Pub Date: September 1972 DOI: 10.1086/151642 Bibcode: 1972ApJ...176..373B full text sources ADS | data products SIMBAD (23)
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