相关论文: Sirius A: turbulence or mass loss?

In this study we investigate the formation and properties of prestellar and protostellar cores using hydrodynamic, self-gravitating Adaptive Mesh Refinement simulations, comparing the cases where turbulence is continually driven and where…

Evolutionary trends in the surface abundances of heavier elements have recently been identified in the globular cluster NGC 6397 ([Fe/H]=-2), indicating the operation of atomic diffusion in these stars. Such trends constitute important…

Proto-planetary discs, the birth environment of planets, are an example of a structure commonly found in astrophysics, accretion discs. Identifying the mechanism responsible for accretion is a long-standing problem, dating back several…

We investigate a sample of 6 Herbig Ae/Be stars belonging to the Orion OB1 association, as well as 73 low mass objects, members of the $\sigma$ Orionis cluster, in order to explore the angular momentum evolution at early stages of…

We investigate turbulent gas motions in spiral galaxies and their importance to star formation in far outer disks, where the column density is typically far below the critical value for spontaneous gravitational collapse. Following the…

I review basic observational features in Population I stars which strongly implicate rotation as a mixing agent; these include dispersion at fixed temperature in coeval populations and main sequence lithium depletion for a range of masses…

We investigate whether it is possible to explain the wide range of observed gradients in early type galaxies in the framework of monolithic models. To do so, we extend the set of hydrodynamical simulations by Pipino et al. (2008a) by…

Aims. To investigate the star formation activity and the gas and stellar dynamics on scales of a few parsecs in the nucleus of the Circinus Galaxy. Methods.Using the adaptive optics near infrared integral field spectrometer SINFONI on the…

Recent accurate abundance analyses of B-type main sequence stars in the solar vicinity has shown that abundances derived from these stellar objects are more homogeneous and metal-rich than previously thought. We investigate whether the…

Recent surveys show that protoplanetary disks have lower levels of turbulence than expected based on their observed accretion rates. A viable solution to this is that magnetized disk winds dominate angular momentum transport. This has…

In this study I assess how existing data for the solar analogues 16 Cyg A and B, in particular the asteroseismic measurements obtained from \emph{Kepler}, constrain theoretical stellar models. The goal is two-fold: first to use these stars…

We present the results of non linear, hydrodynamic simulations, in three dimensions, of the tidal perturbation of accretion discs in binary systems where the orbit is circular and not necessarily coplanar with the disc mid-plane. The…

We have undertaken a survey of H alpha emission in a substantially complete sample of CGCG galaxies of types Sa and later within 1.5 Abell radii of the centres of 8 low-redshift Abell clusters. Some 320 galaxies were surveyed, of which 116…

Motivated by unexplained observations of low sulphur abundances in planetary nebulae (PNe) and the PG1159 class of post asymptotic giant branch (AGB) stars, we investigate the possibility that sulphur may be destroyed by nucleosynthetic…

We conduct a comprehensive theoretical and numerical investigation of the pollution of pristine gas in turbulent flows, designed to provide new tools for modeling the evolution of the first generation of stars. The properties of such…

Turbulent mixing of chemical elements by convection has fundamental effects on the evolution of stars. The standard algorithm at present, mixing-length theory (MLT), is intrinsically local, and must be supplemented by extensions with…

AR Aur A+B is a close binary of astrophysical interest, because dissimilar surface compositions are reported between similar late B-type dwarfs. A new spectroscopic study on this system was carried out based on the disentangled spectra, in…

Context. Massive stars are generally believed to form in supersonic turbulent environment. However, recent observations have challenged this traditional view. High spatial and spectral resolution observations of the Orion Molecular Cloud…

With the aim of understanding the role of outflows in star formation, we performed a statistical study of the physical parameters of outflows in eleven massive protoclusters associated with ultra-compact HII regions. A total of 106 outflow…

We present a model to explain the mass segregation and shallow mass functions observed in the central parts of dense and young starburst stellar clusters. The model assumes that the initial pre-stellar cores mass function resulting from the…