25 research outputs found
Cosmic-ray ionization rate versus Dust fraction: Which plays a crucial role in the early evolution of the circumstellar disk?
We study the formation and early evolution of young stellar objects (YSOs)
using three-dimensional non-ideal magnetohydrodynamic (MHD) simulations to
investigate the effect of cosmic ray ionization rate and dust fraction (or
amount of dust grains) on circumstellar disk formation. Our simulations show
that a higher cosmic ray ionization rate and a lower dust fraction lead to (i)
a smaller magnetic resistivity of ambipolar diffusion, (ii) a smaller disk size
and mass, and (iii) an earlier timing of outflow formation and a greater
angular momentum of the outflow. In particular, at a high cosmic ray ionization
rate, the disks formed early in the simulation are dispersed by magnetic
braking on a time scale of about 104 years. Our results suggest that the cosmic
ray ionization rate has a particularly large impact on the formation and
evolution of disks, while the impact of the dust fraction is not significant.Comment: 8 pages, 10 figures, accepted for publication in MNRA
Formation of unipolar outflow and in magnetized turbulent molecular cloud cores
Observed protostellar outflows exhibit a variety of asymmetrical features,
including remarkable unipolar outflows and bending outflows. Revealing the
formation and early evolution of such asymmetrical protostellar outflows,
especially the unipolar outflows, is essential for a better understanding of
the star and planet formation because they can dramatically change the mass
accretion and angular momentum transport to the protostars and protoplanetary
disks. Here, we perform the three-dimensional non-ideal magnetohydrodynamics
simulations to investigate the formation and early evolution of the
asymmetrical protostellar outflows in magnetized turbulent isolated molecular
cloud cores. We find, for the first time to our knowledge, that the unipolar
outflow forms even in the single low-mass protostellar system. The results show
that the unipolar outflow is driven in the weakly magnetized cloud cores with
the dimensionless mass-to-flux ratios of and . Furthermore, we find
the of the unipolar outflow, which is
similar to the launch and propulsion of a rocket. The unipolar outflow ejects
the protostellar system from the central dense region to the outer region of
the parent cloud core, and the ram pressure caused by its ejection suppresses
the driving of additional new outflows. In contrast, the bending bipolar
outflow is driven in the moderately magnetized cloud core with . The
ratio of the magnetic to turbulent energies of a parent cloud core may play a
key role in the formation of asymmetrical protostellar outflows.Comment: 24 pages, 6 figures, accepted for publication in Ap
Pseudo dilated cardiomyopathy: Dilated cardiomyopathy‐like changes due to a combination of stuck mechanical mitral valve and coronary microvascular dysfunction—An autopsy case
Key Clinical Message Thrombus formation in the microvessels and endocardium was suggestive of endothelial cell damage, myocardial ischemia, and a decreased coronary flow reserve. Sustained pulmonary hypertension due to thrombosis worsened the biventricular dysfunction
Formation of Unipolar Outflow and Protostellar Rocket Effect in Magnetized Turbulent Molecular Cloud Cores
Observed protostellar outflows exhibit a variety of asymmetrical features, including remarkable unipolar outflows and bending outflows. Revealing the formation and early evolution of such asymmetrical protostellar outflows, especially the unipolar outflows, is essential for a better understanding of the star and planet formation because they can dramatically change the mass accretion and angular momentum transport to the protostars and protoplanetary disks. Here we perform three-dimensional nonideal magnetohydrodynamics simulations to investigate the formation and early evolution of the asymmetrical protostellar outflows in magnetized turbulent isolated molecular cloud cores. We find, for the first time to our knowledge, that the unipolar outflow forms even in the single low-mass protostellar system. The results show that the unipolar outflow is driven in the weakly magnetized cloud cores with the dimensionless mass-to-flux ratios of μ = 8 and 16. Furthermore, we find the protostellar rocket effect of the unipolar outflow, which is similar to the launch and propulsion of a rocket. The unipolar outflow ejects the protostellar system from the central dense region to the outer region of the parent cloud core, and the ram pressure caused by its ejection suppresses the driving of additional new outflows. In contrast, the bending bipolar outflow is driven in the moderately magnetized cloud core with μ = 4. The ratio of the magnetic to turbulent energies of a parent cloud core may play a key role in the formation of asymmetrical protostellar outflows
Application of Diluted Electrode Method to Sodium-ion Insertion into Hard Carbon Electrode
Herein, the diluted-electrode method is applied to a hard carbon (HC) electrode to estimate sodium-ion (Na+) insertion kinetics. As metallic nickel (Ni) particles do not accommodate Na+ ions in the potential range of 0–2.0 V vs. Na+/Na, the HC powder electrode is diluted by adding inert Ni particles, enabling the adjustment of the HC concentration while maintaining the composite electrode structure. By examining the rate capabilities of the HC electrodes with different dilutions, we confirm that the Na+ insertion rate for the highly diluted electrode is 10 times higher than that for the undiluted electrode. These improved kinetics can be attributed to the alleviation of Na+ depletion, which results in insignificant concentration polarization under dilute conditions. For a highly diluted electrode, the Na+ insertion kinetics must be controlled by the Na+ mobility in the HC particles and across the HC/electrolyte interface. Therefore, our study reveals that the inherent kinetics of Na+ insertion into HC is very high and provides a basis for developing high-power Na-ion batteries