We present Spitzer/IRS spectra of a small sample of galactic OHPNe. This is a rare class of transition sources displaying both radio continuum and OH maser emission at 1612 MHz. Our observations show that they are heavily obscured O-rich stars whose mid-infrared spectra are dominated by the simultaneous presence of strong and broad amorphous

We present results of the X-ray spectral analysis of the ˜370 ksec deep survey obtained with XMM-Newton on the Chandra Deep Field South (CDFS). Using sample of 127 sources with redshift identifications and with a raw count limit of 100 (pn detector) we explored both the physical properties of individual sources, and the general properties of two

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We discuss methods and preliminary results in a search for variable stars in the Carina dSph galaxy. This galaxy presents a complex star formation history and hosts a unique sample of variable stars. We collected B,V time series data during different runs, from 1999 to 2004, with the MOSAICII camera available at 4m CTIO telescope. The methodology

In addition to optical photometry of unprecedented quality, the Sloan Digital Sky Survey (SDSS) is also producing a massive spectroscopic database. We discuss determination of stellar parameters, such as effective temperature, gravity and metallicity from SDSS spectra, describe correlations between kinematics and metallicity, and study their