Bibcode
Pietarila, A.; Socas-Navarro, H.; Bogdan, T.
Bibliographical reference
The Physics of Chromospheric Plasmas ASP Conference Series, Vol. 368, Proceedings of the conference held 9-13 October, 2006 at the University of Coimbra in Coimbra, Portugal. Edited by P. Heinzel, I. Dorotovič, and R. J. Rutten. San Francisco: Astronomical Society of the Pacific, 2007., p.139
Advertised on:
5
2007
Citations
3
Refereed citations
3
Description
The Ca II infrared (IR) triplet lines are a promising candidate for
studying chromospheric magnetism and dynamics. To study how good of a
diagnostic the lines are for chromospheric magnetism in the quiet Sun we
have constructed a MHD simulation in the high plasma-β regime,
analyzed quiet Sun spectropolarimetric data of the lines and used a
non-local thermodynamic equilibrium (nLTE) inversion code on the
observations. In the simulation, where shocking acoustic waves dominate
the dynamics, the Ca lines show a time-varying pattern of disappearing
and reappearing Stokes V lobes. Waves are seen in the observations as
well, but the dynamics are more complex. Unlike in the simulation, the
observed Ca lines do not have similar shapes and the Stokes V
asymmetries are determined by the local magnetic topology, not the phase
of the wave. The fundamental differences between the observations and
the simulation lead one to conclude that a 1D plane parallel atmosphere
is not a valid approximation for the chromosphere. Nor can the effects
of magnetic fields on the dynamics be neglected. This is further
supported by the inversions failure to reproduce line profile
asymmetries caused by gradients in the velocity and/or magnetic field.
To explain the asymmetries, 3D structures and strongly localized
gradients need to be included. The work presented here will be published
in more detail elsewhere.