相关论文: Solar Activity and Cloud Opacity Variations: A Mod…
We investigate the implications of the intergalactic opacity for the evolution of the cosmic UV luminosity density and its sources. Our main constraint is our measurement of the Lya forest opacity at redshifts 2<z<4.2 from 86…
Simulations of molecular clouds often begin from highly idealised initial conditions, such as a uniform-density sphere with an artificially imposed turbulent velocity field. While the resulting structures may appear qualitatively similar to…
We present results from radiation non-ideal magnetohydrodynamics (MHD) calculations that follow the collapse of rotating, magnetised, molecular cloud cores to stellar densities. These are the first such calculations to include all three…
The cosmic-ray Sun shadow, which is caused by high-energy charged cosmic rays being blocked and deflected by the Sun and its magnetic field, has been observed by various experiments, such as Argo-YBJ, HAWC, Tibet, and IceCube. Most notably,…
Observations have shown that continuous radio emission and also sporadic H-alpha and X-ray emission are prominent in singular, low-mass objects later than spectral class M. These activity signatures are interpreted as being caused by…
Observations of molecular clouds in metal-poor environments typically find that they have much higher star formation rates than one would expect based on their observed CO luminosities and the molecular gas masses that are inferred from…
Due to non-homogeneous mass distribution and non-uniform velocity rate inside the Sun, the solar outer shape is distorted in latitude. In this paper, we analyze the consequences of a temporal change in this figure on the luminosity. To do…
Recent revisions of the determination of the solar composition have resulted in solar models in marked disagreement with helioseismic inferences. The effect of the composition change on the model is largely caused by the change in the…
Neumayer et al. established the existence of a blue-shifted cloud in the core of Centaurus A, within a few parsecs of the nucleus and close to the radio jet. We propose that the cloud has been impacted by the jet, and that it is in the…
We apply gravity-based and density-based methods to identify clouds in numerical simulations of the star-forming, three-phase interstellar medium (ISM), and compare their properties and their global correlation with the star formation rate…
Polarized 850 micron thermal emission data of the region OMC-3 in the Orion A molecular cloud are presented. These data, taken in 1998 with the SCUBA polarimeter mounted on the James Clerk Maxwell Telescope, have been re-reduced using…
The correlation between optical starlight polarization and polarized thermal dust emission can be used to infer intrinsic dust properties. This correlation is quantified by the ratio Rp/p, which has been measured to be 5.42 +/- 0.05 MJy…
A number of transiting exoplanets have featureless transmission spectra that might suggest the presence of clouds at high altitudes. A realistic cloud model is necessary to understand the atmospheric conditions under which such…
The cosmic-ray ionization rate ($\zeta_2$) is one of the key parameters in star formation, since it regulates the chemical and dynamical evolution of molecular clouds by ionizing molecules and determining the coupling between the magnetic…
The physical properties of the faint and extremely tenuous plasma in the far outskirts of galaxy clusters, the circumgalactic media of normal galaxies, and filaments of the cosmic web, remain one of the biggest unknowns in our story of…
A search has been made for a contribution of the changing cosmic ray intensity to the global warming observed in the last century. The cosmic ray intensity shows a strong 11 year cycle due to solar modulation and the overall rate has…
We extend our previous SPH parameter study of the effects of photoionization from O-stars on star-forming clouds to include initially unbound clouds. We generate a set of model clouds in the mass range $10^{4}-10^{6}$M$_{\odot}$ with…
We construct solar models with the newly calculated radiative opacities from the Opacity Project (OP) and recently determined (lower) heavy element abundances. We compare results from the new models with predictions of a series of models…
As long as magnetic fields remain frozen into the gas, the magnetic braking prevents the formation of protostellar discs. This condition is subordinate to the ionisation fraction characterising the inmost parts of a collapsing cloud. The…
Dissociation of molecular hydrogen by secondary electrons produced by cosmic ray or X-ray ionization plays a crucial role in the chemistry of the densest part of molecular clouds. Here we study the effect of the mean kinetic energy of…