相关论文: The Dynamics of Ultracompact HII Regions

We propose that a significant fraction of the ultracompact HII regions found in massive star-forming clouds are the result of the interaction of the wind and ionizing radiation from a young massive star with the clumpy molecular cloud gas…

Cometary ultracompact HII regions have been modelled as the interaction of the hypersonic wind from a moving star with the molecular cloud which surrounds the star. We here show that a similar morphology can ensue even if the star is…

The dynamical evolution of HII regions with and without stellar motion in dense, structured molecular clouds is studied. Clouds are modeled in hydrostatic equilibrium, with gaussian central cores and external halos that obey r**-2 and r**-3…

Here we discuss the interaction of massive stars with their parental molecular clouds. A summary of the dynamical evolution of HII regions and wind-driven bubbles in high-pressure cloud cores is given. Both ultracompact HII regions and…

The observed parameters of the young superstar cluster M82-A1 and its associated compact HII region are here shown to indicate a low heating efficiency or immediate loss, through radiative cooling, of a large fraction of the energy inserted…

We have modelled the evolution of cometary HII regions produced by zero-age main-sequence stars of O and B spectral types, which are driving strong winds and are born off-centre from spherically symmetric cores with power-law ($\alpha = 2$)…

The hypothesis that massive stars form by accretion can be investigated by simple analytical calculations that describe the effect that the formation of a massive star has on its own accretion flow. Within a simple accretion model that…

Ultracompact and hypercompact HII regions appear when a star with a mass larger than about 15 solar masses starts to ionize its own environment. Recent observations of time variability in these objects are one of the pieces of evidence that…

Winds from young massive stars contribute a large amount of energy to their host molecular clouds. This has consequences for the dynamics and observable structure of star-forming clouds. In this paper, we present radiative…

Ultracompact HII regions are signposts of massive star formation and their properties provide diagnostics for the characteristics of very young O stars embedded in molecular clouds. While radio observations have given us a good picture of…

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…

Interstellar bubbles around O stars are driven by a combination of the star's wind and ionizing radiation output. The wind contribution is uncertain because the boundary between the wind and interstellar medium is difficult to observe.…

In this paper we make predictions for the behaviour of wind bubbles around young massive stars using analytic theory. We do this in order to determine why there is a discrepancy between theoretical models that predict that winds should play…

The formation of massive stars may take place at relatively low accretion rates over a long period of time if the accretion can continue past the onset of core hydrogen ignition. The accretion may continue despite the formation of an…

The steady state numerical solution and two dimensional hydrodynamic calculations of supergalactic winds generated by super star clusters are presented. Two possible regimes: quasi-adiabatic and strongly radiative are thoroughly discussed.…

A group of four compact HII regions associated with the well-known 50 km/s molecular cloud is the closest site of on-going star formation to the dynamical center of the Galaxy, at a projected distance of ~6 pc. We present a study of ionized…

We present Chandra/ACIS images of several high-mass star-forming regions. The massive stellar clusters powering these HII regions are resolved at the arcsecond level into hundreds of stellar sources, similar to those seen in closer young…

In this paper we explore the dynamics of ionization bounded planetary nebulae after the termination of the fast stellar wind. When the stellar wind becomes negligible, the hot, shocked bubble depressurizes and the thermal pressure of the…

Using a code that employs a self-consistent method for computing the effects of photo-ionization on circumstellar gas dynamics, we model the formation of wind-driven nebulae around massive stars. We take into account changes in stellar…

We present numerical radiation-hydrodynamic simulations of cometary HII regions for a number of champagne flow and bowshock models. For the champagne flow models we study smooth density distributions with both steep and shallow gradients.…