相关论文: A Morphological Diagnostic for Dynamical Evolution…
Infrared Herschel imaging and spectroscopic observations of the nebula M1-67 around the Wolf-Rayet star WR 124 have been obtained along with optical imaging observations. The infrared images reveal a clumpy dusty nebula that extends up to 1…
Optical emission-line ratios in star-forming galaxies at $z \sim 3$-8, such as [OIII]/H$\beta$ and [OIII]/[OII], are strongly offset from those at $z \sim 0$-2, pointing to more extreme ionization and ISM conditions in the early Universe.…
Recent results for Galactic and Magellanic Cloud Wolf-Rayet stars are summarised based on line blanketed, clumped model atmospheres together with UV, optical and IR spectroscopy. The trend towards earlier WN and WC spectral types with…
Wolf-Rayet (WR) stars are the evolved descendants of massive O-type stars and are considered to be progenitor candidates for Type Ib/c core-collapse supernovae (SNe). Recent results of our HST/WFC3 survey of Wolf-Rayet stars in M101 are…
Hydrostatic models of Wolf-Rayet stars typically contain low-density outer envelopes that inflate the stellar radii by a factor of several and are capped by a denser shell of gas. Inflated envelopes and density inversions are hallmarks of…
We investigate Wolf-Rayet (WR) stars as a source of feedback contributing to the removal of natal material in the early evolution of massive star clusters. Despite previous work suggesting that massive star clusters clear out their natal…
Massive Wolf-Rayet stars are recognized today to be in a very common, but short, evolutionary phase of massive stars. While our understanding of Wolf-Rayet stars has increased dramatically over the past decades, it remains unclear whether…
Massive stars shape their surrounding medium through the force of their stellar winds, which collide with the circumstellar medium. Because the characteristics of these stellar winds vary over the course of the evolution of the star, the…
The WN3/O3 Wolf-Rayet (WR) stars were discovered as part of our survey for WRs in the Magellanic Clouds. The WN3/O3s show the emission lines of a high-excitation WN star and the absorption lines of a hot O-type star, but our prior work has…
Wolf-Rayet (WR) stars are luminous massive blue stars thought to be immediate precursors to the supernova terminating their brief lives. The existence of dust shells around such stars has been enigmatic since their discovery some 30 years…
NGC 2359 is a Wolf-Rayet (W-R) nebula partially bound by a rather dense and warm molecular cloud. We present the results derived from CO and $^{13}$CO fully sampled maps of the molecular material with angular resolutions up to 12". We have…
The propagation of a shock wave into a medium is expected to heat the material beyond the shock, producing noticeable effects in intensity line ratios such as [O III]/Halpha. To investigate the occurrence of shocks in planetary nebulae…
Fast rotating Wolf-Rayet stars are expected to be progenitors of long duration gamma-ray bursts. However, the observational test of this model is problematic. Spectral lines of Wolf-Rayet stars originate in expanding stellar wind, therefore…
Winds from massive stars (> 8 solar masses) result in the formation of wind-blown "bubbles" around these stars. In this paper we study, via two-dimensional numerical hydrodynamic simulations, the onset and growth of turbulence during the…
Vigorous mass loss in the classical Wolf-Rayet (WR) phase is important for the late evolution and final fate of massive stars. We develop spherically symmetric time-dependent and steady-state hydrodynamical models of the radiation-driven…
The environments surrounding nine Wolf-Rayet stars were studied in molecular emission. Expanding shells were detected surrounding these WR stars (see left panels of Figure 1). The average masses and radii of the molecular cores surrounding…
We demonstrate that it is crucial to account for the evolution of the starburst population in order to derive reliable numbers of O stars from integrated spectra for burst ages t > 2 - 3 Myr. In these cases the method of Vacca & Conti…
We continue our numerical analysis of the morphological and energetic influence of massive stars on their ambient interstellar medium for a 35 solar mass star that evolves from the main sequence through red supergiant and Wolf-Rayet phases,…
Wolf-Rayet stars are evolved massive stars, and the relative number of WC-type and WN-type WRs should vary with the metallicity of the host galaxy, providing a sensitive test of stellar evolutionary theory. However, past studies of the WR…
We present a sample of 2865 emission line galaxies with strong nebular He II 4686 emissions in Sloan Digital Sky Survey Data Release 7 and use this sample to investigate the origin of this line in star-forming galaxies. We show that…