Search Publications
Unveiling the past evolution of the progenitor of the Helmi streams
Helmi, A.; Cassisi, S.; Gallart, C. +2 more
Aims: We aim to determine unique features that characterise the past evolution of the progenitor of the Helmi streams through the analysis of star formation histories (SFHs).
Methods: From the 5D Gaia EDR3 dataset, we extracted local samples of stars dominated by the Helmi streams, the Galactic (thick and thin) disc, and the local retrog…
The super-soft source phase of the recurrent nova V3890 Sgr
Ness, J. -U.; Pinto, C.; Singh, K. P. +9 more
Context. The 30-yr recurrent symbiotic nova V3890 Sgr exploded on 2019 August 28 and was observed with multiple X-ray telescopes. Swift and AstroSat monitoring revealed slowly declining hard X-ray emission from shocks between the nova ejecta and the stellar wind of the companion. Later, highly variable super-soft-source (SSS) emission was seen. An…
Multicomponent DHOST analysis in galaxy clusters
Umetsu, Keiichi; Salzano, Vincenzo; Laudato, Enrico
Extended theories of gravity with additional scalar degrees of freedom have recently acquired increasing interest due to the presence of a screening mechanism that allows suppressing at small scales (e.g. the Solar system scale) every modification restoring general relativity (GR). In this work, we consider a second-order extended theory of gravit…
7Be in the outburst of the ONe nova V6595 Sgr
Bonifacio, P.; Hernanz, M.; D'Odorico, V. +7 more
We report on the search for the 7Be II isotope in the outbursts of the classical nova V6595 Sgr by means of high-resolution Ultraviolet and Visual Echelle Spectrograph (UVES) observations taken at the European Southern Observatory's Very Large Telescope in 2021 April, about two weeks after its discovery and under difficult circumstances…
The formation of the Milky Way halo and its dwarf satellites: A NLTE-1D abundance analysis. V. The Sextans galaxy
Jablonka, P.; Yakovleva, S. A.; Belyaev, A. K. +3 more
We present a homogeneous set of accurate atmospheric parameters for a sample of eleven very metal-poor (-3.32 ≤ [Fe/H] ≤-2.61) stars in the Sextans dwarf spheroidal galaxy (dSph) and the non-local thermodynamic equilibrium (NLTE) abundances of, at least, seven chemical elements based on high-resolution UVES/VLT and HDS/Subaru spectra. For each sta…
Testing High-energy Emission Models for Blazars with X-Ray Polarimetry
Liodakis, Ioannis; Peirson, Abel L.; Romani, Roger W.
Both leptonic and hadronic emission processes may contribute to blazar jet emission; which dominates in blazars' high-energy emission component remains an open question. Some intermediate synchrotron peaked blazars transition from their low- to high-energy emission components in the X-ray band making them excellent laboratories to probe both compo…
Searching for TESS Photometric Variability of Possible JWST Spectrophotometric Standard Stars
Gordon, Karl D.; Hermes, J. J.; Fleming, Scott W. +7 more
We use data from the Transiting Exoplanet Survey Satellite (TESS) to search for, and set limits on, optical to near-infrared photometric variability of the well-vetted, candidate James Webb Space Telescope (JWST) spectrophotometric standards. Our search of 37 of these candidate standards has revealed measurable periodic variability in 15 stars. Th…
Photometric and Spectroscopic Study of the EXor-like Eruptive Young Star Gaia19fct
Pál, András; Lee, Jeong-Eun; Ábrahám, Péter +19 more
Gaia19fct is one of the Gaia-alerted eruptive young stars that has undergone several brightening events. We conducted monitoring observations using multifilter optical and near-infrared photometry, as well as near-infrared spectroscopy, to understand the physical properties of Gaia19fct and investigate whether it fits into the historically defined…
The family pictures of our neighbours: investigating the mass function and dynamical parameters of nearby open clusters
Sollima, A.; Haghi, H.; Ebrahimi, H.
We determine the mass functions (MFs) and the dynamical parameters of 15 nearby open clusters (OCs), using the unprecedented data set of the Gaia Early Data Release 3. We select the members of each cluster by combining the photometric (colour and magnitude) and astrometric (parallax and proper motions) parameters of stars, minimizing the contamina…
A Light-curve Analysis of the X-Ray Flash First Observed in Classical Novae
Kato, Mariko; Hachisu, Izumi; Saio, Hideyuki
An X-ray flash, expected in a very early phase of a nova outburst, was at last detected with the SRG/eROSITA in the classical nova YZ Reticuli 2020. The observed flash timescale, luminosity, and blackbody temperature substantially constrain the nova model. We present light-curve models of the X-ray flash for various white dwarf (WD) masses and mas…