Issue |
A&A
Volume 424, Number 2, September III 2004
|
|
---|---|---|
Page(s) | 565 - 570 | |
Section | Galactic structure, stellar clusters, and populations | |
DOI | https://doi.org/10.1051/0004-6361:20040431 | |
Published online | 23 August 2004 |
Seed fields for galactic dynamos by the magnetorotational instability
1
Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482, Potsdam, Germany e-mail: [gruediger;lkitchatinov]@aip.de
2
Institute for Solar-Terrestrial Physics, PO Box 4026, Irkutsk 664033, Russian Federation e-mail: kit@iszf.irk.ru
Received:
12
March
2004
Accepted:
13
May
2004
A linear but global numerical model for the magnetorotational
instability (MRI) in a disk geometry is considered to estimate the instability
parameters for galaxies. Similarity rules suggested by a local analysis
are applied to reveal a universal behavior of the
results of global calculations for large magnetic Prandtl
numbers. The findings are used to estimate the MRI characteristics for galaxies with their very large magnetic
Prandtl numbers which cannot be attained in any numerical simulations.
The resulting minimum field for the instability, G, is small compared to any seed fields currently
discussed. The growth times of MRI are estimated to be on the order of
the rotation period of the inner rigidly-rotating core,
i.e. ~100 Myr. Global MRI excites preferentially magnetic
field modes of quadrupolar symmetry.
Key words: magnetohydrodynamics (MHD) / galaxies: magnetic fields / galaxies: evolution
© ESO, 2004
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.