Search for photospheric footpoints of quiet Sun transition region loops

¹ Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain e-mail: jos@iac.es
² Max-Planck-Institut für Sonnensystemforschung, Max-Plank Str. 2, 37191 Katlenburg-Lindau, Germany e-mail: [teriaca;schuehle]@mps.mpg.de
³ Sterrenkundig Instituut, Universiteit Utrecht, PO Box 80000, 3508 TA Utrecht, The Netherlands e-mail: [P.Suetterlin;R.J.Rutten]@astro.uu.nl
⁴ INAF-Osservatorio Astrofisico di Catania, 95123 Catania, Italy e-mail: dspadaro@oact.inaf.it

Received: 20 June 2007
Accepted: 18 September 2007

Abstract

Context. The footpoints of quiet Sun Transition Region (TR) loops do not seem to coincide with the photospheric magnetic structures appearing in traditional low-sensitivity magnetograms.

Aims.We look for the so-far unidentified photospheric footpoints of TR loops using G-band bright points (BPs) as proxies for photospheric magnetic field concentrations.

Methods.We compare TR measurements with SoHO/SUMER and photospheric magnetic field observations obtained with the Dutch Open Telescope.

Results.Photospheric BPs are associated with bright TR structures, but they seem to avoid the brightest parts of the structure. BPs appear in regions that are globally redshifted, but they avoid extreme velocities. TR explosive events are not clearly associated with BPs.

Conclusions. The observations are not inconsistent with the BPs being footpoints of TR loops, although
we have not succeeded to uniquely identify particular BPs with specific TR loops.