相关论文: A chromospheric conundrum?
We study off-limb emission of the lower solar atmosphere using high-resolution imaging spectroscopy in the H$\beta$ and Ca II 8542 \r{A} lines obtained with the CHROMospheric Imaging Spectrometer (CHROMIS) and the CRisp Imaging…
This paper presents an analysis of three-dimensional vector currents and temperatures observed in a sunspot from the photosphere to the chromosphere, spanning a range of heights of approximately 1500 km. With this unique dataset, based on…
In this topical review I revisit the "chromospheric flare." This should currently be an outdated concept, because modern data seem to rule out the possiblity of a major flare happening independently in the chromosphere alone, but the…
The propagation length of high-energy photons through the Universe is limited by $e^+e^-$ pair production on the extragalactic background radiation. Previous studies reported discrepancies between predicted and observed attenuation,…
Observations of chromospheric spectral lines near and beyond the solar limb provide information on the solar chromosphere without any photospheric contamination. For ground-based observations near and off the limb with real-time image…
UV, optical, and near-IR spectra of Vega have been combined to test our understanding of stellar atmospheric opacities, and to examine the possibility of constraining chemical abundances from low-resolution UV fluxes. We have carried out a…
Angle resolved photoelectron spectroscopic measurements have been performed on an insulating cuprate Ca_2CuO_2Cl_2. High resolution data taken along the \Gamma to (pi,pi) cut show an additional dispersive feature that merges with the known…
We aim to gain insight into the effect of network and faculae on solar irradiance from their apparent intensity. Taking full-disc observations from the Solar Dynamics Observatory, we examined the intensity contrast of network and faculae in…
Differential rotation is the basis of the solar dynamo theory. Synoptic maps of He I intensity from Carrington rotations 2032 to 2135 are utilized to investigate the differential rotation of the solar chromosphere in the He I absorption…
We present near-infrared long-slit spectra of eight optically-dim X-ray sources obtained with ISAAC on the Very Large Telescope. Six of the sources have hard X-ray emission with a significant fraction of the counts emerging above 2 keV. All…
The intermittent dissipation of interstellar turbulence is an important energy source in the diffuse ISM. Though on average smaller than the heating rates due to cosmic rays and the photoelectric effect on dust grains, the turbulent cascade…
The complex spectropolarimetric patterns around strong chromospheric lines, the result of subtle spectroscopic and transport mechanisms, are sensitive, sometimes in unexpected ways, to the presence of magnetic fields in the chromosphere,…
Eclipses are very favourable for the photosphere- chromosphere and corona interface observation as the occultation takes place in space, free of parasitic light coming from the occulting disk (the Moon). Independently, EUV filtergrams of…
In sunspot umbrae, the core of some chromospheric lines exhibits periodic brightness enhancements known as umbral flashes. The consensus is that they are produced by the upward propagation of shock waves. This view has recently been…
Active regions often host large-scale gas flows in the chromosphere presumably directed along curved magnetic field lines. Spectropolarimetric observations of these flows are critical to understanding the nature and evolution of their…
We investigate the relationship between the continuum enhancement and the hard X-ray (HXR) emission of a white-light flare on 2002 September 29. By reconstructing the RHESSI HXR images in the impulsive phase, we find two bright conjugate…
We investigate intensity oscillations observed simultaneously in the quiet chromosphere and in the corona, above an enhanced network area at the boundary of an equatorial coronal hole. A Fourier analysis is applied to a sequence of images…
\ion{Ca}{2} H emission is a well-known indicator of magnetic activity in the Sun and other stars. It is also viewed as an important signature of chromospheric heating. However, the \ion{Ca}{2} H line has not been used as a diagnostic of…
High-spectral resolution observations using the VTT echelle spectrograph in the chromospheric H$\alpha$ line were obtained in the early growth phase of active region NOAA 12722. Noise-stripped H$\alpha$ line profiles yield maps of line-core…
We analyze the spectral asymmetry of Stokes V (circularly polarized) profiles of an individual network patch in the quiet Sun observed by Sunrise/IMaX. At a spatial resolution of 0.15"-0.18", the network elements contain substructure which…