相关论文: On the time variability of the star formation effi…
We investigate the formation of both clustered and distributed populations of young stars in a single molecular cloud. We present a numerical simulation of a 10,000 solar mass elongated, turbulent, molecular cloud and the formation of over…
We propose a simple analytic theory for environmentally-dependent molecular cloud lifetimes, based on the large-scale (galactic) dynamics of the interstellar medium. Within this theory, the cloud lifetime is set by the time-scales for…
We present an analytical determination of the star formation rate (SFR) in molecular clouds, based on a time-dependent extension of our analytical theory of the stellar initial mass function (IMF). The theory yields SFR's in good agreement…
Molecular clouds have broad linewidths suggesting turbulent supersonic motions in the clouds. These motions are usually invoked to explain why molecular clouds take much longer than a free-fall time to form stars. It has classically been…
The contraction processes of metal-free molecular clouds of starlike mass (or cloud cores) are investigated. We calculate radiative transfer of the H_2 lines and examine quasi-static contraction with radiative cooling. Comparing two…
We compute the star formation rate (SFR) in molecular clouds (MCs) that originate {\it ab initio} in a new, higher-resolution simulation of supernova-driven turbulence. Because of the large number of well-resolved clouds with…
Observations show that star formation in galaxies is closely correlated with the abundance of molecular hydrogen. Modeling this empirical relation from first principles proves challenging, however, and many questions regarding its…
We discuss problems with some observational estimates indicating long protostellar core lifetimes and large stellar age spreads in molecular clouds. We also point out some additional observational constraints which suggest that protostellar…
We investigate encounters between giant molecular clouds (GMCs) and star clusters. We propose a single expression for the energy gain of a cluster due to an encounter with a GMC, valid for all encounter distances and GMC properties. This…
The formation of massive objects via gravitational collapse is relevant both for explaining the origin of the first supermassive black holes and in the context of massive star formation. Here, we analyze simulations of the formation of…
In previous contributions, we have presented an analytical model describing the evolution of molecular clouds (MCs) undergoing hierarchical gravitational contraction. The cloud's evolution is characterized by an initial increase in its…
Recent radio observations towards nearby galaxies started to map the whole disk and to identify giant molecular clouds (GMCs) even in the regions between galactic spiral structures. Observed variations of GMC mass functions in different…
Recent radio observations show that the giant molecular cloud (GMC) mass functions noticeably vary across galactic disks. High-resolution magnetohydrodynamics simulations show that multiple episodes of compression are required for creating…
Observations of both star-forming regions and young, gas-free stellar associations indicate that most nearby molecular clouds form stars only over a short time span before dispersal; large-scale flows in the diffuse interstellar medium have…
We present a two-zone theory for feedback-regulated star formation in galactic discs, consistently connecting the galaxy-averaged star formation law with star formation proceeding in giant molecular clouds (GMCs). Our focus is on galaxies…
The nature of turbulence in molecular clouds is one of the key parameters that control star formation efficiency: compressive motions, as opposed to solenoidal motions, can trigger the collapse of cores, or mark the expansion of Hii…
In this paper we investigate the level of star formation activity within nearby molecular clouds. We employ a uniform set of infrared extinction maps to provide accurate assessments of cloud mass and structure and compare these with…
We model the combined effects of photoionization and momentum--driven winds from O--stars on molecular clouds spanning a parameter space of initial conditions. The dynamical effects of the winds are very modest. However, in the lower--mass…
The study of star cluster evolution necessitates modeling how their density profiles develop from their natal gas distribution. Observational evidence indicates that many star clusters follow a Plummer-like density profile. However, most…
Recent observations have demonstrated that giant molecular clouds (GMCs) are short-lived entities, surviving for the order of a dynamical time before turning a few percent of their mass into stars and dispersing, leaving behind an isolated…