We introduce the log(Hα/[SII]λλ6717+6731) versus log(Hα/[NII]λ6583) (S2N2) diagnostic diagram as a metallicity and ionization parameter indicator for HII regions in external galaxies. The location of HII regions in the S2N2 diagram was studied both empirically and theoretically. We found that, for a wide range of metallicities, the S2N2 diagram

Context: The masses previously obtained for the X-ray binary 2S 0921-630 inferred a compact object that was either a high-mass neutron star or low-mass black-hole, but used a previously published value for the rotational broadening (v sin i) with large uncertainties. Aims: We aim to determine an accurate mass for the compact object through an

We present the results of a study on the properties and evolution of massive (M* > 1011Msolar) galaxies at z ~ 0.4-2 utilizing Keck spectroscopy, near-infrared Palomar imaging, and Hubble, Chandra and Spitzer data covering fields targeted by the DEEP2 galaxy spectroscopic survey. Our sample is K-band selected and stellar mass limited, based on wide

The observed parameters of the young super star cluster M82-A1 and its associated compact H II region are here shown to indicate a low heating efficiency or immediate loss, through radiative cooling, of a large fraction of the energy injected by stellar winds and supernovae during the early evolution of the cluster. This implies a bimodal

We observed the neutron star transient SAX J1810.8-2609 with Swift-XRT on November 3rd and 5th, in order to follow its way to quiescence. The source was not detected during the individual ~1.6 ksec and ~1.9 ksec observations. We place 95% upper limits on its 0.5-10 keV unabsorbed flux of [3.4-4.2]E-13 erg/cm2/s (November 3rd.) and [2.9-3.6]E-13 erg

We present mid-infrared data of a sample of 57 AGNs obtained with the instrument ISOCAM on board the Infrared Space Observatory (ISO) satellite. The images were obtained through the LW2 (6.75 μm) and LW7 (9.62 μm) filters. This is a new analysis of the Clavel et al. galaxy sample, which is divided into 26 type 1 (1.5) Seyfert galaxies, plus three