Supergiant Fast X-ray Transients have been recently unveiled as a new class of High Mass X-ray Binaries thanks to the excellent survey capabilities of the INTEGRAL/IBIS instrument. Although there is a general agreement on explaining the behavior of supergiant Fast X-ray Transients as the result of accretion by a compact object from the wind of a

The spectral predictions of stellar population models are not as accurate in the ultra-violet (UV) as in the optical wavelength domain. One of the reasons is the lack of high-quality stellar libraries. The New Generation Stellar Library (NGSL), recently released, represents a significant step towards the improvement of this situation. To prepare

I describe the modeling of stellar ensembles in terms of probability distributions. This modeling is primary characterized by the number of stars included in the considered resolution element, whatever its physical (stellar cluster) or artificial (pixel/IFU) nature. It provides a solution of the direct problem of characterizing probabilistically

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We present the most extensive combined photometric and spectroscopic study to date of the enormous globular cluster (GC) system around M87, the central giant elliptical galaxy in the nearby Virgo Cluster. Using observations from DEIMOS and the Low Resolution Imaging Spectrometer at Keck, and Hectospec on the Multiple Mirror Telescope, we derive new

Widefield surveys have always provided a rich hunting ground for the coolest stars and brown dwarfs. The single epoch surveys at the beginning of this century greatly expanded the parameter space for ultracool dwarfs. Here we outline the science possible from new multi-epoch surveys which add extra depth and open the time domain to study.