ﻻ يوجد ملخص باللغة العربية
We present a three-dimensional, fully parallelized, efficient implementation of ionizing UV radiation for smoothed particle hydrodynamics (SPH) including self-gravity. Our method is based on the SPH/tree code VINE. We therefore call it iVINE (for Ionization + VINE). This approach allows detailed high-resolution studies of the effects of ionizing radiation from e.g. young massive stars on their turbulent parental molecular clouds. In this paper we describe the concept and the numerical implementation of the radiative transfer for a plain-parallel geometry and we discuss several test cases demonstrating the efficiency and accuracy of the new method. As a first application, we study the radiatively driven implosion of marginally stable molecular clouds at various distances of a strong UV source and show that they are driven into gravitational collapse. The resulting cores are very compact and dense exactly as it is observed in clustered environments. Our simulations indicate that the time of triggered collapse depends on the distance of the core from the UV source. Clouds closer to the source collapse several $10^5$ years earlier than more distant clouds. This effect can explain the observed age spread in OB associations where stars closer to the source are found to be younger. We discuss possible uncertainties in the observational derivation of shock front velocities due to early stripping of proto-stellar envelopes by ionizing radiation.
We present EvoL, the new release of the Padova N-body code for cosmological simulations of galaxy formation and evolution. In this paper, the basic Tree + SPH code is presented and analysed, together with an overview on the software architectures. Ev
Since the Universe is inhomogeneous on scales well below the Hubble radius, light bundles from distant galaxies are deflected and distorted by the tidal gravitational field of the large-scale matter distribution as they propagate through the Universe
The installation of the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST) allows for the first time two-dimensional optical and ultraviolet slitless spectroscopy of faint objects from space. The STIS Parallel Survey (SPS
Debris discs are a consequence of the planet formation process and constitute the fingerprints of planetesimal systems. Their solar systems counterparts are the asteroid and Edgeworth-Kuiper belts. The DUNES survey aims at detecting extra-solar analo
The chemical composition of Earths atmosphere has undergone substantial evolution over the course of its history. It is possible, even likely, that terrestrial planets in other planetary systems have undergone similar changes; consequently, the age d