We derive the size and temperature profile of the accretion disk of the lensed quasar SBS 0909+532 by measuring the wavelength dependence (chromaticity) of the microlensing magnification produced by the stars in the lens galaxy. After correcting for extinction using the flux ratios of 14 emission lines, we observe a marked change in the B-A flux

We present a method for the determination of [α/Fe] ratios from low-resolution (R = 2000) SDSS/SEGUE stellar spectra. By means of a star-by-star comparison with degraded spectra from the ELODIE spectral library and with a set of moderately high-resolution (R = 15, 000) and medium-resolution (R = 6000) spectra of SDSS/SEGUE stars, we demonstrate

More than 450 stars hosting planets are known today but only approximately 30 planetary systems were discovered around stars beyond the Main Sequence. The Pennsylvania-Toruń Planet Search, putting an emphasis on extending studies of planetary system formation and evolution to intermediate-mass stars, is oriented towards the discoveries of

Context. The sudden optical brightening of two young stellar objects, HBC 722 and VSX J205126.1+440523, located in the North America/Pelican Nebula Complex, was announced in August 2010. Early photometric and spectroscopic observations of these objects indicated that they may belong to the FUor or EXor class of young eruptive stars. The eruptions

To get insight into the nature of the ionized gas in the nuclear region of LINERs, we performed a study of HST Hα imaging of 32 LINERs. The main conclusion from this analysis is that, for the large majority of LINERs (84%), an unresolved nuclear source has been identified along with extended emission with equivalent sizes ranging from a few tens to

We present new measurements of the magnitude of the main sequence turn off and the red giant branch bump in the luminosity function of a sample of Galactic globular clusters with updated estimates of [Fe/H] and [α/Fe], employing photometric data collected with the Advanced Camera for Survey onboard the HST. We compare measured and predicted values