Bibcode
Gallart, C.
Bibliographical reference
American Astronomical Society, 191st AAS Meeting, #26.04; Bulletin of the American Astronomical Society, Vol. 29, p.1253
Advertised on:
12
1997
Citations
0
Refereed citations
0
Description
Recently, huge photometric databases are being obtained for the
Magellanic Clouds and other Local Group galaxies. These data allow, not
only to study in great detail the star formation history of these
systems, but also provide important information on details of stellar
evolution theory. In the case of the LMC, two structures not previously
noticed in color magnitude diagrams have been interpreted by Zaritszky
& Lin (1997) and Alcock et al (1997) as the possible signature of an
intervening population towards the LMC. Beaulieu & Sackett (1997)
have shown that one of them corresponds to the location of the blue
loops of few Myr old stars. In this paper we show that the other one,
associated till now with the RGB-bump predicted by theory and observed
in globular clusters, is actually produced during the AGB evolution. We
will call this newly observed structure AGB-bump. In addition to the
LMC, the AGB-bump has been observed in some M 31 halo fields and in some
well populated color-magnitude diagrams of dSph galaxies and globular
clusters. The AGB-bump is produced when low and intermediate-mass stars
approach the Hayashi Line at the beginning of the AGB phase. The
penetration and posterior recession of the convective envelope slows
down the evolution of the star momentarily, producing changes in the
luminosity function of the stars. These changes are very small, and have
been detected only when the stellar samples are large enough. We will
compare the stellar evolution predictions of the position and strength
of the AGB-bump with the observed structures in the LMC, in M 31 and in
globular clusters.