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Diffuse solar coronal features and their spicular footpoints
Peter, H.; Chitta, L. P.; Milanović, N.
Context. In addition to a component of the emission that originates from clearly distinguishable coronal loops, the solar corona also exhibits extreme-ultraviolet (EUV) and X-ray ambient emission that is rather diffuse and is often considered undesirable background. Importantly, unlike the generally more structured transition region and chromosphe…
A multi-band AGN-SFG classifier for extragalactic radio surveys using machine learning
Wang, L.; Vaccari, M.; Morganti, R. +7 more
Context. Extragalactic radio continuum surveys play an increasingly more important role in galaxy evolution and cosmology studies. While radio galaxies and radio quasars dominate at the bright end, star-forming galaxies (SFGs) and radio-quiet active galactic nuclei (AGNs) are more common at fainter flux densities.
Aims: Our aim is to develop …
VLT-MUSE spectroscopy of AGNs misclassified by BPT diagnostic or with weak emission lines
Janowiecki, Steven; Boquien, Médéric; Salim, Samir +3 more
Despite powerful X-ray emission, some active galactic nuclei (AGNs) are known to either lack optical emission lines (so-called 'optically dull' AGNs) or have lines that fall on the star-forming branch of the Baldwin-Phillips-Terlevich (BPT) diagram ('misclassified' AGNs). Aperture effects have been proposed to explain such atypical spectra, especi…
eRASSt J040515.6 − 745202, an X-ray burster in the Magellanic Bridge
Haberl, F.; Ray, P. S.; Ducci, L. +13 more
Context. During the third all-sky survey (eRASS3), eROSITA, the soft X-ray instrument aboard Spectrum-Roentgen-Gamma, detected a new hard X-ray transient, eRASSt J040515.6 − 745202, in the direction of the Magellanic Bridge.
Aims: We arranged follow-up observations and searched for archival data to reveal the nature of the transient.
Met…
New insights from cross-correlation studies between solar activity indices and cosmic-ray flux during Forbush decrease events
Savić, Mihailo; Veselinović, Nikola; Dragić, Aleksandar +5 more
Observed galactic cosmic ray intensity can be subjected to a transient decrease. These so-called Forbush decreases are driven by coronal mass ejection induced shockwaves in the heliosphere. By combining in situ measurements by space borne instruments with ground-based cosmic ray observations, we investigate the relationship between solar energetic…
Resonant Effects of a Bar on the Galactic Disk Kinematics Perpendicular to Its Plane
Vieira, Katherine; Carraro, Giovanni; Korchagin, Vladimir +2 more
Detailed analysis of kinematics of the Milky Way disk in the solar neighborhood based on the GAIA DR3 catalog reveals the existence of peculiarities in the stellar velocity distribution perpendicular to the galactic plane. We study the influence of resonances—the outer Lindblad resonance and the outer vertical Lindblad resonance—of a rotating bar …
The [O III] Profiles of Far-infrared Active and Inactive Optically Selected Green Valley Galaxies
Pović, Mirjana; Väisänen, Petri; Márquez, Isabel +8 more
We present a study of the [O III] λ5007 line profile in a subsample of eight active galactic nuclei (AGNs) and six non-AGNs in the optically selected green valley at z < 0.5 using long-slit spectroscopic observations obtained with the 11 m Southern African Large Telescope. Gaussian decomposition of the line profile was performed to study its di…
An interferometric SETI observation of Kepler-111 b
Gajjar, Vishal; Garrett, Michael A.; Wandia, Kelvin +8 more
The application of very long baseline interferometry (VLBI) to the search for extraterrestrial intelligence (SETI) has been limited to date, despite the technique offering many advantages over traditional single-dish SETI observations. In order to further develop interferometry for SETI, we used the European VLBI network (EVN) at 21 cm to observe …
New photometric solutions of contact binaries HX UMa and FP Boo
Yıldırım, M. F.
By using different databases (TESS, SuperWASP, KWS and ASAS-SN), light curve analyzes of HX UMa and FP Boo systems were performed, and the changes in the orbital period of the systems were also examined. The light curve analyzes of the systems were conducted simultaneously with the radial velocities using the Wilson and Devinney (WD) code. As a re…
Dark halos around solar active regions. I. Emission properties of the dark halo around NOAA 12706
Andretta, V.; Del Zanna, G.; Murabito, M. +1 more
Context. Dark areas around active regions (ARs) were first observed in chromospheric lines more than a century ago and are now associated with the Hα fibril vortex around ARs. Nowadays, large areas surrounding ARs with reduced emission relative to the quiet Sun (QS) are also observed in spectral lines emitted in the transition region (TR) and the …