EDP Sciences
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Volume 441, Number 1, October I 2005
Page(s) 153 - 158
Section Interstellar and circumstellar matter
DOI http://dx.doi.org/10.1051/0004-6361:20041721

A&A 441, 153-158 (2005)
DOI: 10.1051/0004-6361:20041721

Ambipolar diffusion in self-gravitating filaments

H.-E. Fröhlich

Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
    e-mail: HEFroehlich@aip.de

(Received 23 July 2004 / Accepted 10 May 2005)

One-dimensional similarity solutions for a collapsing, homogeneous, infinitely long cylinder that is subject to ambipolar diffusion are given. There is an analytical solution with infinite density being reached after 4.3 free-fall times. In that case the magnetic field strength Bz on the axis scales like $B_z\propto\rho^{2/3}$ with density $\rho$. The analytical solution proves "attractive". Even if the initial conditions depart slightly from those of the analytical solution, that solution is nevertheless approached through damped oscillations.

Key words: magnetohydrodynamics (MHD) -- stars: formation -- ISM: clouds -- ISM: magnetic fields

© ESO 2005