The dwarf irregular galaxy IC10 in Cassiopeia, is the youngest available starburst galaxy and home to many X-ray sources. Using the Gemini multi-object spectrograph (GMOS), in the wavelength range containing H-alpha, we obtained spectra of twenty five stars that are positionally coincident with X-ray sources, at the 95% significance level. The

After a decade of intense studies using the latest X-ray and optical telescopes, the nature of ultraluminous X-ray sources (ULXs) is still largely unknown. No definitive answer has emerged on the question of the mass of the black hole powering these objects (intermediate-mass or supercritical stellar-mass?). Further, we lack even basic knowledge

The neutron star transient and 11 Hz X-ray pulsar IGR J17480-2446, recently discovered in the globular cluster Terzan 5, showed unprecedented bursting activity during its 2010 October-November outburst. We analyzed all X-ray bursts detected with the Rossi X-ray Timing Explorer and confirmed their thermonuclear origin, despite the fact that many do

We compare multi-wavelength star formation rate (SFR) indicators out to z ~ 3 in the GOODS-South field. Our analysis uniquely combines U to 8 μm photometry from FIREWORKS, MIPS 24 μm and PACS 70, 100, and 160 μm photometry from the PEP, and Hα spectroscopy from the SINS survey. We describe a set of conversions that lead to a continuity across SFR

Determining the redshift of astronomical sources is fundamental for cosmological studies, since it allows deriving distances to the observer. However, the distance-redshift relationship commonly used is obtained from the isotropic, homogeneous Friedmann-Lemaitre-Robertson-Walker (FLRW) metric. By fitting this distance-redshift relations to

We present a complete study of the morphology of post-Asymptotic Giant Branch (post-AGB) stars. Post-AGB is a very short evolutionary phase between the end of the AGB and the beginning of the Planetary Nebula (PN) stage (between 100 and 10,000 yrs). We have defined the end of the post-AGB phase and the beginning of the PN phase as when the star