Search Publications
The observational evidence that all microflares that accelerate electrons to high energies are rooted in sunspots
Krucker, Säm; Veronig, Astrid M.; Ryan, Daniel F. +6 more
Context. In general, large solar flares are more efficient at accelerating high-energy electrons than microflares. Nonetheless, sometimes microflares that accelerate electrons to high energies are observed. Their origin is unclear. Aims. We statistically characterized microflares with strikingly hard spectra in the hard X-ray (HXR) range, which me…
A multi-instrument study of UV bursts and associated surges in AR 12957
Solanki, S. K.; Berghmans, D.; Calchetti, D. +6 more
Context. The relationship between UV bursts and solar surges is complex, with these events sometimes being observed together and sometimes being observed independently. Why this sporadic association exists is unknown; however, it likely relates to the physical conditions at the site of the energy release that drives these events. Aims. Here, we ai…
OGLE-GD-CEP-0516: The most metal-poor lithium-rich Galactic Cepheid
Salaris, M.; Ripepi, V.; Catanzaro, G. +1 more
Context. Classical Cepheids (DCEPs) are important astrophysical objects not only as standard candles for the determination of the cosmic distance ladder but also as a test-bed for stellar evolution theory thanks to the connection between their pulsation (periods, amplitudes) and stellar (luminosity, mass, effective temperature, metallicity) parame…
Measurement of interstellar extinction for classical T Tauri stars using far-UV H2 line fluxes
France, K.; Eislöffel, J.; Schneider, P. C. +3 more
Understanding the interstellar and potentially circumstellar extinction in the sight lines of classical T Tauri stars is an important ingredient for constructing reliable spectral energy distributions, which catalyze protoplanetary disk chemistry, for example. Therefore, some attempts of measuring AV toward individual stars have been ma…
In pursuit of precise Ca II H&K chromospheric surface fluxes: A gravity and temperature dependence
Schröder, K. -P.; Jack, D.; Rosas-Portilla, F.
The emission lines of the Ca II H&K doublet present one of the most important channels of radiative cooling for the chromospheres of cool stars. Although most other line emissions (Mg II h&k and numerous iron lines) populate the far-UV and require a very competitive space-born observing time, the Ca II H&K lines in the optical UV are easily access…
Upper limit of the solar wind protons backscattering efficiency from Comet 67P/Churyumov-Gerasimenko
Wieser, Martin; Wieser, Gabriella Stenberg; Canu-Blot, Romain
Context. Solar wind ions backscattering is a fundamental plasma-surface interaction process that may occur on all celestial bodies exposed to the solar wind and lacking a significant atmosphere or magnetosphere. Yet, observations have been limited to the regolith-covered Moon and Phobos, one of the Martian moons.
Aims: We aim to expand our kn…
A blind search for intraday gamma-ray transients with Fermi-LAT: Detections of GRB and solar emissions
Prokhorov, D. A.; Moraghan, A.
We present a search for intraday transient γ-ray signals using 15.4 yr of the Fermi Large Area Telescope data. The search is based on a recently developed variable-size sliding-time-window (VSSTW) analysis and is aimed at studying variable γ-ray emission from gamma-ray bursts (GRBs) and the Sun. We refined the algorithm for searches for transient …
An acceleration-radiation model for nonthermal flares from Sgr A*
Ponti, Gabriele; Petropoulou, Maria; Stel, Giovanni +1 more
Context. Sgr A⋆ is the electromagnetic counterpart of the accreting supermassive black hole in the Galactic center. Its emission is variable in the near-infrared (NIR) and X-ray wavelengths on short timescales (several minutes to a few hours). The NIR light curve displays red-noise variability, while the X-ray light curve exhibits brigh…
Molecular gas budget of strongly magnified low-mass star-forming galaxies at cosmic noon
Sharon, K.; Bayliss, M.; Mahler, G. +9 more
Aims. The aim of this study is to investigate the molecular gas content of strongly magnified low-mass star-forming galaxies (SFGs) around the cosmic noon period (z ∼ 2) through observations of carbon monoxide (CO) emission lines and dust continuum emission, both of which serve as tracers of molecular gas (H2). Methods. We observed 12 s…
The stellar population of a z ∼ 3.25 Lyα-emitting group associated with a damped Lyα absorber
Rafelski, Marc; Fumagalli, Michele; Fossati, Matteo +4 more
We present near-infrared observations, acquired with the Wide Field Camera 3 (WFC3) on board the Hubble Space Telescope (HST), of a Lyα-emitting double-clumped nebula at z ≈ 3.25 associated with a damped Lyα absorber (DLA). With the WFC3/F160W data we observe the stellar continuum around 3600 Å in the rest frame of a galaxy embedded in the west cl…