Non-isothermal effects on the static equilibria of magnetized layers of molecular clouds
Abstract
The molecular clouds (MCs), which are observed as Giant Molecular Clouds, Isolated Bok Globules and/or Infrared Dark Clouds, are the nurseries for forming stars and planets. Observations show that the MCs are influenced by diverse forms of magnetic field lines. The magnetic field gradients can produce the ambipolar diffusion mechanism through the MCs. Nejad-Asghar (2019) showed that considering the heating due to ambipolar diffusion in the MCs, the local thermal balance leads to a local loosely constrained power-law relation between the pressure and density P ∝ ρ1+χ, where -0.4≤ χ≤ 0.05 depends on the functional form of the net cooling function. Physically, the value of χ depends on the power of dependence of magnetic field to the density, and also on the value of the magnetic field gradient. For a strong magnetic field and/or a large field gradient, the value of χ decreases, and vice versa. The substructures through the MCs have complex morphologies from layers to filaments and semi-spheres. Here, for simplicity, we use stratified layer approximation to investigate the effect of the non-isothermal parameter χ on the substructure of the MCs. The results show that considering the non-isothermal equation of state with smaller χ (i.e., stronger magnetic field and/or larger field gradient) transfers the magnetic field lines to the outer cloud regions, and hence decreases the density in the central regions of the cloud. We conclude that the stronger magnetic field and/or larger field gradient can disperse the density fluctuations through the MCs.
- Publication:
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Bulgarian Astronomical Journal
- Pub Date:
- July 2021
- Bibcode:
- 2021BlgAJ..35...28B
- Keywords:
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- ISM: structure;
- ISM: clouds;
- ISM: magnetic fields;
- stars: formation;
- (Galaxy:) local interstellar matter