We have examined the wind momentum problem of O-type stars in the Galaxy. It is shown that the discrepancy between theoretical and empirical mass loss rates and terminal velocities can be reversed by using recently updated values of force multiplier parameters. With these new values, the momentum problem found by former investigators is reversed so

We present contemporaneous optical and infrared (IR) photometric observations of the Type IIn SN 1998S covering the period between 11 and 146d after discovery. The IR data constitute the first ever IR light curves of a Type IIn supernova. We use blackbody and spline fits to the photometry to examine the luminosity evolution. During the first 2-3

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We have carried out an optical follow-up of twelve ROSAT discovered candidate members of the Coma Berenices open cluster. VRI photometry and low resolution ( ~ 3 Å) spectroscopy in the range 3800-7000 Åwere performed to obtain colour-magnitude diagrams, proper motions, spectral types, chromospheric activity levels and radial velocities that allow

We present the polarization monitoring carried out for two SNe associated with GRBs: XRF060218/SN2006aj and XRF080109/SN2008D. For XRF060218/SN2006aj we measured a mean polarization of P˜4% at 2.6-5.6 days after the X-ray event. This is the highest polarization value ever measured for a supernova. We derived the intrinsic polarization of XRF080109

We searched for X-ray counterparts of optical novae detected in M 31 and M 33. We combined an optical nova catalogue from the WeCAPP survey with optical novae reported in the literature and correlated them with the most recent X-ray catalogues from ROSAT, XMM-Newton, and Chandra, and in addition searched for nova correlations in archival data. We