Stars with masses greater than about ten solar masses are thought to end their lives either in a supernova or in a direct gravitational collapse process, either of which could have a black hole as a remnant. But there is as yet no direct observational evidence to support either gravitational collapse in general or the formation of black hole

In planar symmetry (one-dimensional peculiar motions), using the Eulerian perturbative framework and an arbitrary initial profile, we compute the analytical evolution of the peculiar velocity and the density contrast up to the fourth order (E1-E4 approximations). From these results and the exact (Lagrangian) solutions, the accuracy of the Ej (j

Inclusive as well as exclusive energy spectra of the light charged particles emitted in the $^{28}$Si ($E_{lab}$=112.6 MeV) + $^{12}$C reaction has been measured using the {f ICARE} multidetector array. The data have been analysed by statistical-model calculations using a spin-dependent level density parametrization. The results suggest

Observations taken at Calar Alto and Loiano led to the possible identification of the GRB 971227 optical counterpart. Details on the observations are presented.

This paper announces the release at CDS of a substantial set of point sources detected by the DENIS project. DENIS is the first astronomical survey of the Southern sky in two near-infrared bands (J at 1.25 mu m, and K_s at 2.15 mu m) and one optical band (Gunn-i at 0.82 mu m), conducted by a European consortium, using the 1m telescope at ESO, La

We have analyzed in detail the discovery measurements of the X-ray burster SAX J1750.8-2900 by the Wide Field Cameras on board BeppoSAX in spring 1997, at a position ~1.2d off the Galactic center. The source was in outburst on March 13 when the first observation started and showed X-ray emission for ~2 weeks. A total of nine bursts were detected