Found 4 talks width keyword Hertzsprung-Russell diagram

Thursday October 13, 2022
Technion University, Israel


Exciting things may have happened sometimes to the stars we see in the sky today. For example, Betelgeuse, also known as Alpha-Ori, an M-type red supergiant, the 10th brightest sky in the sky (usually), may well have been a binary star in the past. Its rapid rotation, peculiarly large Galactic velocity, and unusual chemical abundances all point to it being kicked out from the birth environment and merging as a binary star. By comparing a Monte-Carlo stellar cluster population model with the observed populations of Galactic O- and B- type stars (progenitors of red supergiants), I will show that the story of Betelgeuse is not at all uncommon. In distant galaxies, closely related scenarios may give rise to peculiar core-collapse supernovae. I will conclude by briefly discussing how the diversity of such binary and triple stellar evolution histories reflects in the variety of the currently discovered core-collapse supernovae.

Thursday November 20, 2014
INAF-Osservatorio Astronomico di Teramo


Since the early 50' of last century the study of Horizontal Branch stars in Galactic GCs has been of pivotal relevance since the core He-burning stage is an 'amplifier' of any evolutionary/physical process occurring during the early evolutionary stages. Thanks to the huge observational effort devoted to this issue many outstanding 'anomalies' have been discovered concerning the physical properties of GC HB stars. The situation is becoming more complex when accounting for the discovery of the Multiple Population phenomenon in Galactic GCs. We will review the main anomalies related to the HB evolutionary stage, their (when available) theoretical interpretations, and current shortcomings. We will also discuss how the discovery of the Multiple Population Phenomenon offers a new approach for interpreting many observational evidence.

Thursday October 18, 2012


The basis of stellar population modeling was established around 40 years ago somehow
optimized to the technical facilities and observational data available at that epoch. Since then,
it has been used extensively in astronomy and there has been great improvements relating
their associated ingredients in concordance with the development of more powerful computational
and observational facilities.
However, there has been no similar improvements in the understanding about what is
actually modeling neither in improve the modeling itself to include the current technical advances
to obtain more accurate result in the physical inferences obtained from them.
In this talk I present some advances in the subject of stellar
population modeling and how to take advantage of current facilities to obtain more robust
and accurate inferences from stellar systems at different scales
covering the continuum between fully resolved populations to fully unresolved ones in a unified framework.

Thursday January 12, 2012
Universidad Pontificia de Chile, Chile


A serious limitation in the study of the Galactic inner halo and bulge globular clusters has been the existence of large and differential extinction by foreground dust. We have mapped the differential extinction and removed its effects, using a new dereddening technique, in a sample of 25 clusters in the direction of the inner Galaxy, observed in the optical using the Magellan 6.5m telescope and the Hubble Space Telescope. We have also observed a sample of 33 inner Galactic globular clusters in the framework of the VVV survey that is currently being conducted with the new Vista 4m telescope, in infrared bands where the extinction is highly reduced. Using these observations we have produced high quality color-magnitude diagrams of these poorly studied clusters that allow us to determine these clusters relative ages, distances and chemistry more accurately and to address important questions about the formation and the evolution of the inner Galaxy.

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