Stellar explosions are astrophysical phenomena of great importance and interest, for their impact on the dynamics and chemical evolution of galaxies . In
the case of novae and thermonuclear supernovae, the exploding star is a white dwarf. These stars are the last stages of stellar evolution of stars with
masses below about 10 M_sol . Should be isolated , their final destination is to cool and disappear, while when in compact binary systems, the accretion
of matter from the companion star can destabilize the white dwarf. In the case of novae, the fusion of accreted hydrogen in degenerate conditions at the
base of the envelope, causes a thermonuclear runaway and the ejection of the outer layers at high speeds. The emission at high energies reveals details
of the explosion. Furthermore, it has been discovered that nova can produce cosmic rays. The previous stages of stellar evolution leading to the
formation of white dwarfs are crucial to understanding the properties of the white dwarf just exploding. Since years we have been working on the
characterization of novae and supernovae in X-rays and gamma-rays, with use of space missions. But in the MeV range, where nuclear transitions
occur, there has been not much progress from the instrumental point of view, given the intrinsic difficulties in this energy: the instrumental noise is very
loud and matter - radiation cross section of interaction (the Compton effect is dominant ) is very low. One of the instrumental concepts that would allow a
significant advance would be a gamma lens, combined with a Compton camera. Moreover, it is necessary to advance in the study of radiation detectors
in the range of hard X-rays/sift gamma-rays (up to 1 MeV) , and so our group is involved in this study (CdTe detectors ), with wide applications in other
fields (safety and medicine). As for X -rays, a possibility of significant progress would be LOFT (the Large Observatory for X-ray Timing, able to study
time variability with high accuracy) and also Athena + , the successor to the XMM-Newton satellite.PI and Co-PI: Hernanz, M.
, Serenelli, A.Participants:
Álvarez, L., Artigues, G., Delgado, L.
, Morales-Garoffolo, A., Vinyoles, N.
, Tatischeff, V., Jean, P., Elías de la Rosa, N., Alvarez, J.M., Gálvez, J.Funding Institution:
CSNSM (IN2P3-CNRS & UNI. PARIS SUD) FRANCE, IRAP (CNRS-CNES-UNI- TOULOUSE III PAUL SABATIER), FRANCE; INAF - PADOVA ASTRONOMICAL OBS., ITALIA; CENTRO DE LASERES PULSADOS ULTRACORTOS ULTRAINTENSOS, SALAMANCA