Letters to the Editor

Are solar chromospheric fibrils tracing the magnetic field?

¹ Institute for Solar Physics, Royal Swedish Academy of Sciences, AlbaNova University Center, 106 91 Stockholm, Sweden
e-mail: jaime@astro.su.se
² Department of Astronomy, Stockholm University, AlbaNova University Center, 106 91 Stockholm, Sweden
³ Instituto de Astrofísica de Canarias, Avda Vía Láctea S/N, La Laguna 38200, Tenerife, Spain
⁴ Departamento de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife, Spain

Received: 29 October 2010
Accepted: 17 January 2011

Abstract

Fibrils are thin elongated features visible in the solar chromosphere in and around magnetized regions. Because of their visual appearance, they have been traditionally considered a tracer of the magnetic field lines. For the first time, we challenge that notion by comparing their orientation to that of the magnetic field, obtained via high-resolution spectropolarimetric observations of Ca ii lines. The short answer to the question posed in the title is that mostly yes, but not always.