Spectrophotometric Evolution of Old Stellar Systems

Spectrophotometric Evolution of Old Stellar Systems

New HST Views at Old Stellar Systems

HST has recently revealed that many among the most massive globular clusters harbor multiple stellar populations, and –most surprisingly– some of them are extremely helium rich. How these clusters managed to generate such complex stellar populations, and what processes let to so dramatic helium enrichment, is today one of the most exciting puzzles in the astrophysics of stellar systems. HST has...

Spectrophotometric Resolution of Stellar Surfaces with Microlensing

Microlensing is a powerful tool for studying stellar atmospheres, because as the source crosses regions of formally inÐnite magniÐcation (caustics), the surface of the star is resolved, thereby allowing one to measure the radial intensity proÐle both photometrically and spectroscopically. However, caustic crossing events are relatively rare and monitoring them requires intensive application of ...

Spectrophotometric Resolution of Stellar Atmospheres with Microlensing

Microlensing is a powerful tool for studying stellar atmospheres because as the source crosses regions of formally infinite magnification (caustics) the surface of the star is resolved, thereby allowing one to measure the radial intensity profile, both photometrically and spectroscopically. However, caustic crossing events are relatively rare, and monitoring them requires intensive application ...

Noise-driven evolution in stellar systems: Theory

We present a theory for describing the evolution of a galaxy caused by stochastic events such as weak mergers, transient spiral structure, orbiting blobs, etc. This noise excites large-scale patterns that drives the evolution of the galactic density profile. In dark-matter haloes, the repeated stochastic perturbations preferentially ring the lowest-order modes of the halo with only a very weak ...