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Broad-band X-ray properties of black holes GRS 1758-258 and 1E 1740.7-2942: AstroSat and NuSTAR results
Agrawal, Vivek K.; Mandal, Samir; Nandi, Anuj +4 more
We present the results on broad-band X-ray properties of persistent black hole binaries GRS 1758-258 and 1E 1740.7-2942 using AstroSat, NuSTAR, and Swift-XRT observations carried out during 2016-2022. We perform spectral modelling of both sources after eliminating the contamination in their LAXPC spectra from nearby X-ray sources. Preliminary spec…
UOCS. X. Rich collection of post-mass-transfer systems in NGC 6791
Jadhav, Vikrant V.; Subramaniam, Annapurni; Sagar, Ram
Aims: NGC 6791 is one of the richest old open clusters in the Milky Way. Its position above the Galactic plane and its number density make it an interesting middle ground between Galactic open and globular clusters. We aim to detect the UV-bright population of NGC 6791 using AstroSat/UVIT images in near-UV and far-UV filters and characterise …
Star-disk interactions in the strongly accreting T Tauri star S CrA N
Dougados, C.; Bouvier, J.; Alencar, S. H. P. +11 more
Context. Classical T Tauri stars are thought to accrete material from their surrounding protoplanetary disks through funnel flows along their magnetic field lines. The classical T Tauri stars with high accretion rates (∼10−7 M⊙ yr−1) are ideal targets for testing this magnetospheric accretion scenario in a sustaine…
Spatial structure and dynamical state of the old open cluster Collinder 261 based on a clustering method
Gao, Xinhua
In this paper, we investigate the memberships, spatial structure, and dynamical state of the old open cluster Collinder 261 (8 Gyr) based on Gaia-DR3 data. We develop a robust clustering method to calculate membership probabilities for 24858 sample stars within 20' of the cluster center. We can identify 2619 likely cluster members (including 54 bl…
Disc wind or disc line? The extraordinary Fe-K feature of Mrk 1513
Bianchi, S.; Braito, V.; Nardini, E. +4 more
We discuss the origin of a very unusual spectral structure observed in the Fe-K band of the Seyfert galaxy Mrk 1513, a local (z = 0.063) active galactic nucleus (AGN) that is efficiently accreting matter onto its central supermassive black hole (Lbol/LEdd ∼ 0.5). We consider the highest quality X-ray observation of this sourc…
Investigating the Origin of the Absorption-line Variability in the Narrow-line Seyfert 1 Galaxy WPVS 007
Komossa, S.; Gallagher, Sarah C.; Terndrup, Donald M. +5 more
Broad absorption line quasars are actively accreting supermassive black holes that have strong outflows characterized by broad absorption lines in their rest-UV spectra. Variability in these absorption lines occurs over months to years depending on the source. WPVS 007, a low-redshift, low-luminosity narrow-line Seyfert 1 (NLS1) shows strong varia…
Anisotropic Ionizing Illumination from an M-type Pre-main-sequence Star, DM Tau
Tamura, Motohide; Liu, Hauyu Baobab; Hashimoto, Jun +6 more
The powerful, high-energy magnetic activities of young stars play important roles in the magnetohydrodynamics in the innermost parts of the protoplanetary disks. In addition, the associated UV and X-ray emission dictates the photochemistry; moreover, the corona activities can affect the atmosphere of a newborn extrasolar planet. How the UV and X-r…
Nonequilibrium Ionization Effects on Synthetic Spectra in the AWSoM Solar Corona
Landi, E.; van der Holst, B.; Szente, J.
In this work, we combined AWSoM's nonequilibrium ionization (NEI) calculations from Szente et al. with the synthetic spectral computations of SPECTRUM to predict nonequilibrium line intensities across the entire domain of the AWSoM 3D global model. We find that the resulting spectra are strongly affected by nonequilibrium effects in the fast-wind …
Can Clay Mimic the High Reflectivity of Briny Water Below the Martian SPLD?
Caprarelli, Graziella; Pettinelli, Elena; Cosciotti, Barbara +6 more
It has recently been suggested that clay minerals, which are widespread on the Martian surface, could be the possible source of the basal bright reflections detected by MARSIS at Ultimi Scopuli, instead of briny water. This hypothesis is based on dielectric measurements on a wet Ca-Montorillonite (STx-1b) sample conducted at 230 K, which reported …
Expulsion of Counter Evershed Flows from Sunspot Penumbrae
Solanki, S. K.; Korpi-Lagg, A.; Castellanos Durán, J. S.
In addition to the Evershed flow directed from the umbra toward the outer boundary of a sunspot, under special circumstances a counter Evershed flow (CEF) in the opposite direction also occurs. We aim to characterize the proper motions and evolution of three CEFs observed by the Solar Optical Telescope on board the Japanese Hinode spacecraft and t…