Inside and outside of supernovae

A newly formed neutron star in a supernova finds itself in a dense environment, in which the gravitational energy of accreting matter can be lost to neutrinos. For the conditions in SN 1987A, 0.1M may have fallen back onto the central neutron star on a timescale of hours after the explosion, after which the accretion rate is expected to drop sharply. Radiation is trapped in the flow until the mass accretion rate drops to 2×10^–4 M yr^–1 at which point radiation can begin to escape from the shocked envelope at an Eddington limit luminosity. Between this neutrino limit and the Eddington limit, 3×10^–8 M yr^–1, there are no steady, spherical solutions for neutron star accretion. SN 1987A should have reached the neutrino limit within a year of the explosion; the current lack of an Eddington luminosity can be attributed to black hole formation or to a clearing of the neutron star envelope. There is no evidence for newly formed neutron stars in supernovae. Radio supernovae, which were initially interpreted as pulsar activity, probably involve circumstellar interaction; SN 1993J shows especially good evidence for outer shock phenomena.     

Supernova remnants

Optical observations of young supernova remnants can give information on the abundance structure of the supernova ejecta, from which properties of the supernova explosion can be deduced. Young remnants also act as laboratories for fast shock wave phenomena. Observations of X-ray and optical line emission show that while a collisionless shock wave does form, it is far from thermal equilibrium. Some young remnants are promising candidates for particle acceleration in shock waves, while in other remnants a central compact object is probably responsible for particle acceleration.     

Future concepts for electromagnetic detection: fromspace-time-frequency resources management to wideband radars

An overview of the key operational and technical factors governing future radar evolution is given, in order to identify main lines along which research and development effort should be oriented     

Optical identifications of faint X-ray sources: New CCD candidates for 0918-549, 1822-000 and 1905+000

We present preliminary results of multicolor CCD imaging within the error boxes of several unidentified faint galactic X-ray sources. New, faint ultraviolet stars have been found lying within the combined SAS-3/HEAO A-3 error boxes of Reid et al. (1980) for 0918-549, 1822-000 and the X-ray burster 1905+000.Based on observations collected at the European Southern Observatory, La Silla, Chile.Visiting Astronomer, Canada-France-Hawaii Telescope, administered by NRC of Canada, CNRS of France and U. of Hawaii     

An IR,optical and X-ray study of the two state behaviour of GX 339-4

We review results of correlated IR, optical and X-ray observations of GX 339-4 made from March 1981 through May 1984. In the soft X-ray state, the object does not show outstanding optical and X-ray variability. Night-to-night smooth optical variations of 0.3 magnitudes were however present during one observing run. In contrast, the hard X-ray state is characterised by strong erratic optical and X-ray fluctuations on time scales from 20 milliseconds to seconds, as well as 7 to 20 second quasi-periodic oscillations. The optical counterpart appears much redder in the IR during the hard state. Particular attention is drawn to the hard to soft X-ray transition which occured in June 1981. The shape of the IR to X-ray energy distribution is discussed. The unusual features of this black hole candidate are examined in the framework of the current theories of accretion.Based partly on observations obtained at the European Southern Observatory, La Silla, Chile.     

Superluminous Supernovae

Superluminous supernovae are a new class of supernovae that were recognized about a decade ago. Both observational and theoretical progress has been significant in the last decade. In this review, we first briefly summarize the observational properties of superluminous supernovae. We then introduce the three major suggested luminosity sources to explain the huge luminosities of superluminous supernovae, i.e., the nuclear decay of ⁵⁶Ni, the interaction between supernova ejecta and dense circumstellar media, and the spin down of magnetars. We compare these models and discuss their strengths and weaknesses.     

Total solar irradiance absolute level from DIARAD/SOVIM on the International Space Station

Current measurements from DIARAD/VIRGO, PMO6V/VIRGO and ACRIM3 radiometers are of the same order of magnitude, but differ from TIM/SORCE by about 4.5 W m⁻². This difference is higher than the sum of the claimed individual absolute uncertainties of the instruments. In this context, the SOLAR payload on the International Space Station embarks the SOVIM package. We give the results of the differential absolute radiometer DIARAD/SOVIM and discuss its associated uncertainties. Compared to DIARAD/VIRGO, all possible efforts have been made to improve the absolute accuracy. Substantial progress has been made in the aperture area and electrical power measurements. The measured TSI value from the left channel of DIARAD/SOVIM during three days of June 2008 is 1364.50 ± 1.38 W m⁻² (Total) or ±0.49 W m⁻² (if we combine the individual contributions in quadrature). The right channel gives 1364.75 W m⁻² with the same uncertainties. These values are about 1.2 W m⁻² lower than DIARAD/VIRGO and about 4 W m⁻² higher than TIM/SORCE. The difference between the left and right channels measurements is as low as 0.25 W m⁻² which is within the improved uncertainty limits.