Search Publications
Non-damping oscillations at flaring loops
Li, D.; Zhang, Q. M.; Ning, Z. J. +3 more
Context. Quasi-periodic oscillations are usually detected as spatial displacements of coronal loops in imaging observations or as periodic shifts of line properties (i.e., Doppler velocity, line width and intensity) in spectroscopic observations. They are often applied for remote diagnostics of magnetic fields and plasma properties on the Sun.
Temperature constraints from inversions of synthetic solar optical, UV, and radio spectra
Leenaarts, J.; da Silva Santos, J. M.; de la Cruz Rodríguez, J.
Context. High-resolution observations of the solar chromosphere at millimeter wavelengths are now possible with the Atacama Large Millimeter Array (ALMA), bringing with them the promise of tackling many open problems in solar physics. Observations from other ground and space-based telescopes will greatly benefit from coordinated endeavors with ALM…
Rotating network jets in the quiet Sun as observed by IRIS
Srivastava, A. K.; Murawski, K.; Dwivedi, B. N. +1 more
Aims: We perform a detailed observational analysis of network jets to understand their kinematics, rotational motion, and underlying triggering mechanism(s). We analyzed the quiet-Sun (QS) data.
Methods: IRIS high-resolution imaging and spectral observations (slit-jaw images: Si IV 1400.0 Å; raster: Si IV 1393.75 Å) were used to analyze …
Emission of solar chromospheric and transition region features related to the underlying magnetic field
Barczynski, K.; Peter, H.; Chitta, L. P. +1 more
Context. The emission of the upper atmosphere of the Sun is closely related to magnetic field concentrations at the solar surface.
Aims: It is well established that this relation between chromospheric emission and magnetic field is nonlinear. Here we investigate systematically how this relation, characterised by the exponent of a power-law fi…
Effects of resonant scattering of the Si IV doublet near 140 nm in a solar active region
Vial, J. -C.; Gontikakis, C.
Aims: In a previous study we analysed the C IV 1548.189 Å and 1550.775 Å lines observed with the Solar Ultraviolet Measurements of Emitted Radiation (SUMER), showing cases where the 1548.189 Å spectral profile was noticeably different from the 1550.775 Å one, profiles that we dubbed differentially shaped profiles. We explained this differenti…
Statistical analysis of UV spectra of a quiescent prominence observed by IRIS
Heinzel, P.; Jejčič, S.; Gunár, S. +2 more
Context. The paper analyzes the structure and dynamics of a quiescent prominence that occurred on October 22, 2013 and was observed by several instruments including the Interface Region Imaging Spectrograph (IRIS).
Aims: We aim to determine the physical characteristics of the observed prominence using Mg II k and h (2796 and 2803 Å), C II (13…
Chromospheric counterparts of solar transition region unresolved fine structure loops
De Pontieu, Bart; Hansteen, Viggo H.; Rouppe van der Voort, Luc +1 more
Low-lying loops have been discovered at the solar limb in transition region temperatures by the Interface Region Imaging Spectrograph (IRIS). They do not appear to reach coronal temperatures, and it has been suggested that they are the long-predicted unresolved fine structures (UFS). These loops are dynamic and believed to be visible during both h…
Structure of sunspot light bridges in the chromosphere and transition region
Rezaei, R.
Context. Light bridges (LBs) are elongated structures with enhanced intensity embedded in sunspot umbra and pores.
Aims: We studied the properties of a sample of 60 LBs observed with the Interface Region Imaging Spectrograph (IRIS).
Methods: Using IRIS near- and far-ultraviolet spectra, we measured the line intensity, width, and Doppler …
Non-equilibrium ionization by a periodic electron beam. II. Synthetic Si IV and O IV transition region spectra
Dudík, Jaroslav; Dzifčáková, Elena
Context. Transition region (TR) spectra typically show the Si IV 1402.8 Å line to be enhanced by a factor of 5 or more compared to the neighboring O IV 1401.2 Å, contrary to predictions of ionization equilibrium models and the Maxwellian distribution of particle energies. Non-equilibrium effects in TR spectra are therefore expected.
Aims: To …
Propagating wave in active region-loops, located over the solar disk observed by the Interface Region Imaging Spectrograph
Zhang, J.; Zhang, B.; Hou, Y. J.
Aims: We aim to ascertain the physical parameters of a propagating wave over the solar disk detected by the Interface Region Imaging Spectrograph (IRIS).
Methods: Using imaging data from the IRIS and the Solar Dynamic Observatory (SDO), we tracked bright spots to determine the parameters of a propagating transverse wave in active region …