Search Publications
The multi-thermal emission in solar active regions
Del Zanna, G.
We present simultaneous SDO AIA and Hinode EIS observations of the hot cores of active regions (ARs) and assess the dominant contributions to the AIA EUV bands. This is an extension of our previous work. We find good agreement between SDO AIA, EVE and EIS observations, using our new EIS calibration and the latest EVE v.3 data. We find that all the…
A revised radiometric calibration for the Hinode/EIS instrument
Del Zanna, G.
An assessment of the in-flight radiometric calibration of the Hinode EUV Imaging Spectrometer (EIS) is presented. This is done with the line ratio technique applied to a wide range of observations of the quiet Sun, active regions, and flares from 2006 until 2012. The best diagnostic lines and the relevant atomic data are discussed in detail. Radia…
Structure of sunspot penumbral filaments: a remarkable uniformity of properties
Lagg, Andreas; Solanki, Sami K.; Tiwari, Sanjiv Kumar +1 more
Context. The sunspot penumbra comprises numerous thin, radially elongated filaments that are central for heat transport within the penumbra, but whose structure is still not clear.
Aims: We aim to investigate the fine-scale structure of these penumbral filaments.
Methods: We perform a depth-dependent inversion of spectropolarimetric data…
Quiet Sun magnetic fields observed by Hinode: Support for a local dynamo
Solanki, S. K.; Lagg, A.; Buehler, D.
Context. The Hinode mission has revealed copious amounts of horizontal flux covering the quiet Sun. Local dynamo action has been proposed to explain the presence of this flux.
Aims: We sought to test whether the quiet Sun flux detected by Hinode is due to a local or the global dynamo by studying long-term variations in the polarisation signal…
Peripheral downflows in sunspot penumbrae
Solanki, S. K.; Lagg, A.; van Noort, M. +1 more
Context. Sunspot penumbrae show high-velocity patches along the periphery.
Aims: The high-velocity downflow patches are believed to be the return channels of the Evershed flow. We aim to investigate their structure in detail using Hinode SOT/SP observations.
Methods: We employ Fourier interpolation in combination with spatially coupled h…
Returning magnetic flux in sunspot penumbrae
Ruiz Cobo, B.; Asensio Ramos, A.
Aims: We study the presence of reversed polarity magnetic flux in sunspot penumbra.
Methods: We applied a new regularized method to deconvolve spectropolarimetric data observed with the spectropolarimeter SP onboard Hinode. The new regularization is based on a principal component decomposition of the Stokes profiles. The resulting Stokes…
Observationally driven 3D magnetohydrodynamics model of the solar corona above an active region
Peter, H.; Bingert, S.; Bourdin, Ph. -A.
Context.
Aims: The goal is to employ a 3D magnetohydrodynamics (MHD) model including spectral synthesis to model the corona in an observed solar active region. This will allow us to judge the merits of the coronal heating mechanism built into the 3D model.
Methods: Photospheric observations of the magnetic field and horizontal velocities…
Accuracy of magnetic energy computations
Démoulin, P.; Masson, S.; Pariat, E. +1 more
Context. For magnetically driven events, the magnetic energy of the system is the prime energy reservoir that fuels the dynamical evolution. In the solar context, the free energy (i.e., the energy in excess of the potential field energy) is one of the main indicators used in space weather forecasts to predict the eruptivity of active regions. A tr…
Dynamics of the solar atmosphere above a pore with a light bridge
Heinzel, P.; Jurčák, J.; Berrilli, F. +3 more
Context. Solar pores are small sunspots lacking a penumbra that have a prevailing vertical magnetic-field component. They can include light bridges at places with locally reduced magnetic field. Like sunspots, they exhibit a wide range of oscillatory phenomena.
Aims: A large isolated pore with a light bridge (NOAA 11005) is studied to obtain …
Magnetic field strength distribution of magnetic bright points inferred from filtergrams and spectro-polarimetric data
Veronig, A.; Utz, D.; Hanslmeier, A. +3 more
Context. Small scale magnetic fields can be observed on the Sun in G-band filtergrams as magnetic bright points (MBPs) or identified in spectro-polarimetric measurements due to enhanced signals of Stokes profiles. These magnetic fields and their dynamics play a crucial role in understanding the coronal heating problem and also in surface dynamo mo…