Is the magnetic field in quiescent prominences force-free?
1
Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85740 Garching, Germany e-mail: ula@mpa-garching.mpg.de
2
Astronomical Institute, Academy of Sciences of the Czech Republic, 25165 Ondřejov, Czech Republic
Received:
27
November
2006
Accepted:
23
February
2007
Aims.We describe under which conditions the magnetic fields of quiescent prominences are force-free and under which gravity plays the dominant role.
Methods.The existing observational determinations of the magnetic field are summarised and the calculation of the plasma β is outlined. We derive the dependence of β on the prominence weight and the field strength.
Results.We show that in many cases of well-developed quiescent prominences the field can deviate substantially from the force-free situation and gravity fully determines the structure of the magnetic dips.
Key words: Sun: prominences / Sun: magnetic fields / Sun: filaments
© ESO, 2007