The detection of 1.809 MeV gamma-ray line emission from the Vela region by the COMPTEL telescope presents a direct prove of recent nucleosynthesis activity in this region. It has been suggested that the observed 1.809 MeV emisson could arise from the radioactive decay of 26Al produced by the Vela SNR and/or the nearby Wolf-Rayet star γ2 Vel

Results from a new multi-wavelength evolutionary synthesis model including the γ-ray line emission from various radioactive isotopes (26Al, 60Fe) are presented. In particular the predicted γ-ray line observations combined with measurements of ionising fluxes can efficiently constrain the age of a stellar population, and help to identify the primary

M31 has been monitored by a Chandra GTO program, which used both the HRC and ACIS from 1999 to 2001 and a GO program, which used ACIS-S during 2000-2001. We report here the lightcurves of X-ray sources in M31 during the past two years. X-ray sources in M31, like in our Galaxy, exhibit variability on long timescales (days to months). Some sources

We present K-band photometry and low-resolution near-infrared spectroscopy from 1.44 to 2.45 μm of isolated planetary-mass candidate members in the σ Orionis cluster found by Zapatero Osorio et al. The new data have been obtained with NIRC at the Keck I telescope. All of our targets, except for one, are confirmed as likely cluster members. Hence

Coded Aperture System performances are defined by the geometry of the code, detector pixel geometry relationship and focal length. Physical Coded Aperture Systems deviate from the ideal ones on two basic aspects: uncertainties on pixel location and size coming form the manufacturing process and deviations from their theoretical transparency/opacity

We derive some element abundances for the central star of the planetary nebula K648 from analysis of Hubble Space Telescope Faint Object Spectrograph spectra (1200-3300 Å). Carbon is found to be approximately 4 times overabundant with respect to solar values, while oxygen is underabundant and silicon about solar, and He/H=0.6. The stellar continuum