111. Eruptive mass loss less than a year before the explosion of superluminous supernovae : I. The cases of SN 2020xga and SN 2022xgcA. Gkini, C. Fransson, Ragnhild Lunnan, S. Schulze, F. Poidevin, N. Sarin, R. Könyves-Tóth, Jesper Sollerman, Mateusz Bronikowski, Tanja Petrushevska, 2025, original scientific article Abstract: We present photometric and spectroscopic observations of SN 2020xga and SN 2022xgc, two hydrogen-poor superluminous supernovae (SLSNe-I) at z = 0.4296 and z = 0.3103, respectively, which show an additional set of broad Mg II absorption lines, blueshifted by a few thousands kilometer second−1 with respect to the host galaxy absorption system. Previous work interpreted this as due to resonance line scattering of the SLSN continuum by rapidly expanding circumstellar material (CSM) expelled shortly before the explosion. The peak rest-frame g-band magnitude of SN 2020xga is −22.30 ± 0.04 mag and of SN 2022xgc is −21.97 ± 0.05 mag, placing them among the brightest SLSNe-I. We used high-quality spectra from ultraviolet to near-infrared wavelengths to model the Mg II line profiles and infer the properties of the CSM shells. We find that the CSM shell of SN 2020xga resides at ∼1.3 × 1016 cm, moving with a maximum velocity of 4275 km s−1, and the shell of SN 2022xgc is located at ∼0.8 × 1016 cm, reaching up to 4400 km s−1. These shells were expelled ∼11 and ∼5 months before the explosions of SN 2020xga and SN 2022xgc, respectively, possibly as a result of luminous-blue-variable-like eruptions or pulsational pair instability (PPI) mass loss. We also analyzed optical photometric data and modeled the light curves, considering powering from the magnetar spin-down mechanism. The results support very energetic magnetars, approaching the mass-shedding limit, powering these SNe with ejecta masses of ∼7 − 9 M⊙. The ejecta masses inferred from the magnetar modeling are not consistent with the PPI scenario pointing toward stars > 50 M⊙ He-core; hence, alternative scenarios such as fallback accretion and CSM interaction are discussed. Modeling the spectral energy distribution of the host galaxy of SN 2020xga reveals a host mass of 107.8 M⊙, a star formation rate of 0.96−0.26+0.47 M⊙ yr−1, and a metallicity of ∼0.2 Z⊙.
Keywords: eruptive mass, loss, supernovae
Published in RUNG: 04.03.2025; Views: 566; Downloads: 7
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112. Characterization of brown carbon absorption in different European environments through source contribution analysisHector Navarro-Barboza, Jordi Rovira, Vincenzo Obiso, Andrea Pozzer, Marta Via, Andrés Alastuey, Xavier Querol, Jesús Yus-Díez, Matic Ivančič, Martin Rigler, 2025, original scientific article Abstract: Brown carbon (BrC) is a fraction of organic aerosol (OA) that absorbs radiation in the ultraviolet and short visible wavelengths. Its contribution to radiative forcing is uncertain due to limited knowledge of its imaginary refractive index (k). This study investigates the variability of k for OA from wildfires, residential, shipping, and traffic emission sources over Europe. The Multiscale Online Nonhydrostatic Atmosphere Chemistry (MONARCH) model simulated OA concentrations and source contributions, feeding an offline optical tool to constrain k values at 370 nm. The model was evaluated against OA mass concentrations from aerosol chemical speciation monitors (ACSMs) and filter sample measurements, as well as aerosol light absorption measurements at 370 nm derived from an Aethalometer™ from 12 sites across Europe. Results show that MONARCH captures the OA temporal variability across environments (regional, suburban, and urban background). Residential emissions are a major OA source in colder months, while secondary organic aerosol (SOA) dominates in warmer periods. Traffic is a minor primary OA contributor. Biomass and coal combustion significantly influence OA absorption, with shipping emissions also notable near harbors. Optimizing k values at 370 nm revealed significant variability in OA light absorption, influenced by emission sources and environmental conditions. Derived k values for biomass burning (0.03 to 0.13), residential (0.008 to 0.13), shipping (0.005 to 0.08), and traffic (0.005 to 0.07) sources improved model representation of OA absorption compared to a constant k. Introducing such emission source-specific constraints is an innovative approach to enhance OA absorption in atmospheric models.
Keywords: aerosols, brown carbon, source contribution analysis
Published in RUNG: 04.03.2025; Views: 569; Downloads: 6
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113. Algebraic structures and graph theoryscientific monograph Keywords: groups, ring, field, lattice, hypergroups, hyperring, hyperfield, graph, hypergraph, equivalence relation, operation, hyperoperation
Published in RUNG: 04.03.2025; Views: 509; Downloads: 5
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120. On some differences between clitic climbing and clitic fronting : lecture at the IGG50, 50th Incontro di Grammatica Generativa, University of Padova (Italy), February 19, 2025Franc Marušič, Rok Žaucer, 2025, unpublished conference contribution Keywords: clitics, clitic climbing, clitic fronting, restructuring
Published in RUNG: 03.03.2025; Views: 421; Downloads: 0
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