19 papers
A broadband outburst of the compact steep-spectrum quasar 3C 138 in 2024-2026
T. V. Mufakharov, Yu. V. Sotnikova, V. V. Vlasyuk +20
After several decades of relative quiescence, the compact steep-spectrum quasar 3C 138 entered an active phase in 2024-2026, exhibiting strong broadband flaring. We investigate its…
Cepheid metallicities from low-resolution near-infrared spectra: validation against the optical reference scale
M. A. Urbaneja, R. P. Kudritzki, N. Przybilla
Classical Cepheid metallicities trace recent chemical enrichment and help assess systematics in Cepheid-based distance measurements. They are derived mainly from high-resolution op…
Unveiling the period-bounce population of cataclysmic variables: Spectroscopic and time-domain follow-up of eROSITA-selected candidates
S. Hernández-DÃaz, B. Stelzer, A. Schwope +9
The paper presents spectroscopic and time‑domain follow‑up of eROSITA‑selected cataclysmic variable candidates, confirming 24 new systems and showing they are consistent with perio…
The X-ray-Weak Tail of the Quasar Population: Physical Properties and Redshift Evolution of Variability-Selected AGN in eFEDS
P. Arévalo, J. Buchner, M. Salvato +10
The paper examines AGN identified through optical variability in the eROSITA eFEDS survey, comparing those detected in X‑rays to those that are not, and finds that a substantial hi…
Multi-Wavelength Diagnostics of Pre-Flare Evolution with Aditya-L1: From the Solar Chromosphere to the Corona
Adithya H. N., Sreejith Padinhatteeri, Soumya Roy +13
The pre-flare phase of solar flares provides important insight into the processes that drive active regions toward instability. We investigate chromospheric pre-flare activity usin…
Chemical modelling of interstellar MgS
M. Rey-Montejo, I. Jimenez-Serra, T. Millar +8
The detection of magnesium sulphide (MgS) and sodium sulphide (NaS) towards the Galactic Center molecular cloud G+0.693 constitutes the first detection of metal sulphides in the in…