相关论文: Star Formation Thresholds
The spherical gravitational collapse and virialization of arbitrary density fluctuations in an expanding universe is studied. In the context of the standard cosmological model and the peak $ansatz$, disk galaxies are supposed to be the…
The formation of stellar clusters dictates the pace at which galaxies evolve, and solving the question of their formation will undoubtedly lead to a better understanding of the Universe as a whole. While it is well known that star clusters…
Stars form when filaments and dense cores in molecular clouds fragment and collapse due to self-gravity. In the most basic analyses of gravitational stability, the competition between self-gravity and thermal pressure sets the critical…
How stars are born from clouds of gas is a rich physics problem whose solution will inform our understanding of not just stars but also planets, galaxies, and the universe itself. Star formation is stupendously inefficient. Take the Milky…
The spatial range for feedback from star formation varies from molecular cloud disruption on parsec scales to supershells and disk blowout on kiloparsec scales. The relative amounts of energy and momentum given to these scales is important…
(Abridged) The formation of molecular clouds (MCs) from the diffuse interstellar gas appears to be a necessary step for star formation, as young stars invariably occur within them. However, the mechanisms controlling the formation of MCs…
Most stars form in dense star clusters deeply embedded in residual gas. These objects must therefore be seen as the fundamental building blocks of galaxies. With this contribution some physical processes that act in the very early and also…
We review galaxy formation and dynamics under the MOND hypothesis of modified gravity, and compare to similar galaxies in Newtonian dynamics with dark matter. The aim is to find peculiar predictions both to discriminate between various…
Understanding the formation of the first stars and galaxies is a key problem in modern cosmology. In these lecture notes, we will derive some of the basic physical principles underlying this emerging field. We will consider the basic…
We study the large-scale triggering of star formation in galaxies. We find that the largest mass-scale not stabilized by rotation, a well defined quantity in a rotating system and with clear dynamical meaning, strongly correlates with the…
Cosmological simulations predict that during the evolution of galaxies, the specific star formation rate continuously decreases. In a previous study we showed that generally this is not caused by the galaxies running out of cold gas but…
The origin of supermassive black holes is an open question that has been explored considering gas- and collision-based formation channels to explain the high number of quasars observed in the early Universe. According to numerical…
Star formation rates on the galactic scale are described phenomenologically by two distinct relationships, as emphasized recently by Elmegreen (2002). The first of these is the Schmidt law, which is a power-law relation between the star…
Massive stars are very rare, but their extreme luminosities make them both the only type of young star we can observe in distant galaxies and the dominant energy sources in the universe today. They form rarely because efficient radiative…
We offer a simple parameterization of the rate of star formation in galaxies. In this new approach, we make explicit and decouple the timescales associated (a) with disruptive effects the star formation event itself, from (b) the timescales…
Star formation laws are empirical relations between the cold gas (HI+H$_2$) content of a galaxy and its star formation rate (SFR), being crucial for any model of galaxy formation and evolution. A well known example of such laws is the…
Observations show that galaxies and their interstellar media are pervaded by strong magnetic fields with energies in the diffuse component being at least comparable to the thermal and even as large or larger than the turbulent energy. Such…
The radial profiles of gas, stars, and far ultraviolet radiation in 20 dwarf Irregular galaxies are converted to stability parameters and scale heights for a test of the importance of two-dimensional (2D) instabilities in promoting star…
Star formation laws, like i.e. the Schmidt law relating star formation rate and total gas density, have been studied in several spiral galaxies but the underlying physics are not yet well understood. M51, as a nearby face-on, grand design…
We aim at studying the abundance gradients along the Galactic disk and their dependence upon several parameters: a threshold in the surface gas density regulating star formation, the star formation efficiency, the timescale for the…