Related papers: Ellerman Bombs at high resolution: II. Visibility,…
In order to investigate the near wing of the Lyman-alpha line, accurate line profile calculations and molecular data are both required due to the existence of a close line satellite responsible for its asymmetrical shape. Lyman-alpha lines…
Magnetic reconnection at small spatial scales is a fundamental driver of energy release and plasma dynamics in the lower solar atmosphere. We present observations of a brightening in an active region, captured in high-resolution data from…
Context. Since the mechanism of energy release from solar flares is still not fully understood, the study of fine-scale features developing during flares becomes important for progressing towards a consistent picture of the essential…
The focus of this investigation is to quantify the conversion of magnetic to thermal energy initiated by a quiet Sun cancellation event and to explore the resulting dynamics from the interaction of the opposite polarity magnetic features.…
Optical and near-UV continuum emissions in flares contribute substantially to flare energy budget. Two mechanisms play an important role for continuum emission in flares: hydrogen recombination after sudden ionization at chromospheric…
Increase in the Balmer continuum radiation during solar flares was predicted by various authors but never firmly confirmed observationally using ground-based slit spectrographs. Here we describe a new post-focal instrument - Image Selector…
From H\alpha narrow band observations, we identified three H\alpha emitting regions in the direction of Magellanic Stream IV (MS IV). They consist of three parallel filaments with 2 arcmin width and 6 -- 30 arcmin length at 12 arcmin…
Red-shifted components of chromospheric emission lines in the hard X-ray impulsive phase of solar flares have recently been studied through their 30 s evolution with the high resolution of IRIS. Radiative-hydrodynamic flare models show that…
Transition-region explosive events (EEs) are characterized by non-Gaussian line profiles with enhanced wings at Doppler velocities of 50-150 km/s. They are believed to be the signature of solar phenomena that are one of the main…
Burst-like events with signatures in the UV are often observed co-spatial to strong line-of-sight photospheric magnetic fields. Several authors, for example, have noted the spatial relationship between Ellerman bombs (EBs) and Moving…
A high quality Keck spectrum of the Halpha line in NGC 4395 reveals symmetric exponential wings, fv\propto e^{-v/sigma}, with sigma~500km/s. The wings extend out to >2500km/s from the line core, and down to a flux density of <10^-3 of the…
Deep H$\alpha$ images of a faint emission complex 4.0 x 5.5 degrees in angular extent and located far off the Galactic plane at l = 70.0 degrees, b=-21.5 degrees reveal numerous thin filaments suggestive of a supernova remnant's shock…
Flare loops form an integral part of eruptive events, being detected in the range of temperatures from X-rays down to cool chromospheric-like plasmas. While the hot loops are routinely observed by the Solar Dynamics Observatory's…
We present a detailed multi-wavelength study of observations from X-ray, near-infrared to centimeter wavelengths to probe the star formation processes in the S237 region. Multi-wavelength images trace an almost sphere-like shell morphology…
We present the first detection of solar flare emission at middle-ultraviolet wavelengths around 2000 A by the channel 2 of the Large-Yield RAdiometer (LYRA) onboard the PROBA2 mission. The flare (SOL20170906) was also observed in the…
We present orbit-resolved spectroscopic and photometric observations of the polar ST LMi during its recent low and high states. In the low state spectra, we report the presence of blue and red satellites to the H-alpha emission line; the…
We report on our observing program to capture simultaneous spectra of Ca II and Balmer lines in a sample of nearby M3 dwarfs. Our goal is to investigate the chromospheric temperature structure required to produce these lines at the observed…
Radiative transfer in hydrogen lines in supernova remnant (SNR) shock waves is studied taking into account the population of the hydrogen atom 2s-state. Measurements of Balmer line emission, especially of H~$\alpha$, are often relied upon…
Very precise satellite photometry has revealed a large number of variable stars whose variability is caused either by surface spots or by binarity. Detailed studies of such variables provide insights into the physics of these objects. We…
A multi-wavelength spatial and temporal analysis of solar high energy electrons is conducted using the August 20, 2002 flare of an unusually flat (gamma=1.8) hard X-ray spectrum. The flare is studied using RHESSI, Halpha, radio, TRACE, and…