Helical Fields and Filamentary Molecular Clouds

Details Helical Fields and Filamentary Molecular Clouds Helical Fields and Filamentary Molecular Clouds

1999-01-08

arxiv.org/abs/astro-ph/9901096v3

Astronomy and Astrophysics

Astrophysics

21 pages, 8 eps figures, submitted to MNRAS. Significant streamlining of text

Scientific paper

10.1046/j.1365-8711.2000.03066.x

We study the equilibrium of pressure truncated, filamentary molecular clouds that are threaded by rather general helical magnetic fields. We first derive a new virial equation appropriate for magnetized filamentary clouds, which includes the effects of non-thermal motions and the turbulent pressure of the surrounding ISM. When compared with the data, we find that many filamentary clouds have a mass per unit length that is significantly reduced by the effects of external pressure, and that toroidal fields play a significant role in squeezing such clouds. We also develop exact numerical MHD models of filamentary molecular clouds with more general helical field configurations than have previously been considered. We also examine the effects of the equation of state by comparing ``isothermal'' filaments, with constant total (thermal plus turbulent) velocity dispersion, with equilibria constructed using a logatropic equation of state. We perform a Monte Carlo exploration of our parameter space to determine which choices of parameters result in models that agree with the available observational constraints. We find that both equations of state result in equilibria that agree with the observational results. Moreover, we find that models with helical fields have more realistic density profiles than either unmagnetized models or those with purely poloidal fields; we find that most isothermal models have density distributions that fall off as r^{-1.8} to r^{-2}, while logatropes have density profiles that range from r^{-1} to r^{-1.8}. We find that purely poloidal fields produce filaments with steep density gradients that not allowed by the observations.

Affiliated with

Also associated with

No associations

Rating

Helical Fields and Filamentary Molecular Clouds does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Helical Fields and Filamentary Molecular Clouds, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Helical Fields and Filamentary Molecular Clouds will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-391051