Related papers: Helium Emissions Observed in Ground-Based Spectra …
Even quiescent solar prominences may become active and sometimes erupt. These events are occasionally linked to coronal mass ejections. However we know very little about the plasma properties during the activation and eruption processes. We…
We present a comprehensive set of spectral data from two quiescent solar prominences observed in parallel from space and ground: with the VTT, simultaneous two-dimensional imaging of H-beta 4862 and Ca II 8542 yields a constant ratio,…
This paper presents observational evidence of the different dynamical behavior of neutral and ionized species in solar prominences. The analysis of a time-series of Sr II 4078 A and Na D spectra in a quiescent prominence yields…
Solar prominences contain a significant amount of neutral species. The dynamics of the ionised and neutral fluids composing the prominence plasma can be slightly different if the collisional coupling is not strong enough. Large-scale…
Active prominences exhibit plasma motions, resulting in difficulties with the interpretation of spectroscopic observations. These solar features being strongly influenced by the radiation coming from the solar disk, Doppler dimming or…
We estimate the electron density, n_e, and its spatial variation in quiescent prominences from the observed emission ratio of the resonance lines Na I 5890 (D2) and Sr II 4078. For a bright prominence (tau_alpha ~ 25) we obtain a mean n_e ~…
We aim at studying the effect of radial motions on the spectrum emitted by moving prominences in the helium resonance lines and at facilitating the interpretation of observations, in order to improve our understanding of these dynamic…
We report observations of a unique, large prominence eruption that was observed in the He II 304 {\AA} passband of the the Extreme Ultraviolet Imager/Full Sun Imager telescope aboard Solar Orbiter on 15-16 February 2022. Observations from…
We study spectral lines in exceptionally bright solar limb prominences with pronounced sodium and magnesium emission. We find that most prominences with significant NaD2 and Mgb2 emission show centrally reversed profiles of H-alpha and…
Context. Theoretical calculations have shown that when solar prominences move away from the surface of the Sun, their radiative output is affected via the Doppler dimming or brightening effects. Aims. In this paper we ask whether…
The He I 5876A absorption line recently discovered in the spectrum of the companion to the millisecond pulsar PSR J1740-5340 is tentatively attributed to electron impact excitations due to the irradiation of its atmosphere by gamma-rays…
We observe simultaneously the Ca II K, Ca II 8542 and H-beta emissions in solar prominences at high spatial and spectral resolution. We confirm a branching in the emission relations of Ca II and H-beta. This is related to non-thermal line…
In this study we show how hydrogen and helium lines modelling can be used to make a diagnostic of active and eruptive prominences. One motivation for this work is to identify the physical conditions during prominence activation and…
We present synthetic spectra corresponding to a 2.5D magnetohydrodynamical simulation of a rotating prominence in the Ca II 8542 \r{A}, H$\alpha$, Ca II K, Mg II k, Ly $\alpha$, and Ly $\beta$ lines. The prominence rotation resulted from…
We present direct spectroscopic modeling of 44 Type Iax supernovae (SNe Iax) using spectral synthesis code SYNAPPS. We confirm detections of helium emission in the early-time spectra of two SNe Iax: SNe 2004cs and 2007J. These He I features…
Balmer-dominated shocks in Type Ia supernova remnants offer powerful probes into collisionless shock physics and hints towards supernova progenitor environments. Prior studies focused on the hydrogen Balmer lines, which manifest as a…
The diagnosis of new high-resolution spectropolarimetric observations of solar prominences made in the visible and near-infrared mainly, requires a radiative modelling taking into account for both multi-dimensional geometry and complex…
We present the results of several collisional-radiative models describing optically-thin emissivities of the main lines in neutral helium formed by recombination, for a grid of electron temperatures and densities, typical of H II regions…
The Prominence-Corona Transition Region (PCTR) plays a key role in the thermal and pressure equilibrium of solar prominences. Our knowledge of this interface is limited and several major issues remain open, including the thermal structure…
We show how the observed hydrogen Balmer and Lyman emission lines constrain the modeling of quiescent solar prominences. We compare space observations of Lyman lines with ground-based observations of Balmer lines for quiescent solar…