Search Publications
Differential emission measures from the regularized inversion of Hinode and SDO data
Hannah, I. G.; Kontar, E. P.
Aims: To demonstrate the capabilities of regularized inversion to recover differential emission measures (DEMs) from multi-wavelength observations provided by telescopes such as Hinode and SDO.
Methods: We develop and apply an enhanced regularization algorithm, used in RHESSI X-ray spectral analysis, to constrain the ill-posed inverse pr…
Spatially coupled inversion of spectro-polarimetric image data. I. Method and first results
van Noort, M.
Context. When inverting solar spectra, image degradation effects that are present in the data are usually approximated or not considered.
Aims: We develop a data reduction method that takes these issues into account and minimizes the resulting errors.
Methods: By accounting for the diffraction PSF of the telescope during the inversions, …
Observations and simulations of longitudinal oscillations of an active region prominence
Chen, P. F.; Zhang, Q. M.; Xia, C. +1 more
Context. Filament longitudinal oscillations have been observed in Hα observations of the solar disk.
Aims: We intend to find an example of the longitudinal oscillations of a prominence, where the magnetic dip can be seen directly, and examine the restoring force of this type of oscillations.
Methods: We carry out a multiwavelength data a…
Coronal hole boundaries at small scales. IV. SOT view. Magnetic field properties of small-scale transient brightenings in coronal holes
Doyle, J. G.; Madjarska, M. S.; Huang, Z. +1 more
Context. We study the magnetic properties of small-scale transients in coronal holes and a few in the quiet Sun identified in X-ray observations and spectroscopic data in two previous papers.
Aims: We aim to investigate the role of small-scale transients in the evolution of the magnetic field in an equatorial coronal hole.
Methods: Two s…
Benchmarking atomic data for the CHIANTI atomic database: coronal lines observed by Hinode EIS
Del Zanna, G.
The coronal lines that are observable in the Hinode EUV Imaging Spectrometer (EIS) wavelengths are assessed with new atomic data that have recently become available for a range of important ions. EIS spectral lines are identified based on their spatial variation across different solar regions, their wavelengths, and their intensities. Two off-limb…
Atomic data for astrophysics: Fe xii soft X-ray lines
Mason, H. E.; Del Zanna, G.; Storey, P. J. +1 more
We present new large-scale R-matrix (up to n = 4) and distorted-wave (DW, up to n = 6) scattering calculations for electron collisional excitation of Fe xii. The first aim is to provide accurate atomic data for the soft X-rays, where strong decays from the n = 4 levels are present. As found in previous work on Fe x, resonances attached to n = 4 le…
Coronal hole boundaries evolution at small scales. III. EIS and SUMER views
Doyle, J. G.; Madjarska, M. S.; Huang, Z. +1 more
Context. We report on the plasma properties of small-scale transient events identified in the quiet Sun, coronal holes and their boundaries.
Aims: We aim at deriving the physical characteristics of events that were identified as small-scale transient brightenings in XRT images.
Methods: We used spectroscopic co-observations from SUMER/So…
Horizontal flow fields observed in Hinode G-band images. II. Flow fields in the final stages of sunspot decay
Liu, C.; Wang, H.; Shimizu, T. +4 more
Context. Generation and dissipation of magnetic fields is a fundamental physical process on the Sun. In comparison to flux emergence and the initial stages of sunspot formation, the demise of sunspots still lacks a comprehensive description.
Aims: The evolution of sunspots is most commonly discussed in terms of their intensity and magnetic fi…
Scaling laws for magnetic fields on the quiet Sun
Stenflo, J. O.
The Sun's magnetic field is structured over a range of scales that span approximately seven orders of magnitudes, four of which lie beyond the resolving power of current telescopes. Here we have used a Hinode SOT/SP deep mode data set for the quiet-Sun disk center in combination with constraints from the Hanle effect to derive scaling laws that de…
Quasi full-disk maps of solar horizontal velocities using SDO/HMI data
Roudier, Th.; Malherbe, J. M.; Gizon, L. +6 more
Aims: For the first time, the motion of granules (solar plasma on the surface on scales larger than 2.5 Mm) has been followed over the entire visible surface of the Sun, using SDO/HMI white-light data.
Methods: Horizontal velocity fields are derived from image correlation tracking using a new version of the coherent structure tracking al…