Search Publications
Toward an X-ray inventory of nearby neutron stars
Santangelo, A.; Pavlov, G. G.; Posselt, B. +1 more
Context. The X-ray emission of neutron stars enables a probe of their temperatures, geometries and magnetospheric properties. The current number of X-ray emitting pulsars is insufficient to rule out observational biases that may arise from poorly known distance, age, or location of the neutron stars. One approach to overcome such biases is to crea…
Extending the FIP bias sample to magnetically active stars. Challenging the FIP bias paradigm
van Driel-Gesztelyi, L.; Kriskovics, L.; Baker, D. +6 more
Context. The different elemental abundances of the photosphere and the corona are striking features of not only the Sun, but of other stars as well. This phenomenon is known as the first ionisation potential (FIP) effect, and its strength can be characterized by the FIP bias, the logarithmic abundance difference between low- and high-FIP elements …
Transient obscuration event captured in NGC 3227. III. Photoionization modeling of the X-ray obscuration event in 2019
Kaastra, J. S.; Kriss, G. A.; Bianchi, S. +16 more
Context. A growing number of transient X-ray obscuration events in type I active galactic nuclei suggest that our line of sight to the central engine is not always free. Multiple X-ray obscuration events were reported in the nearby Seyfert 1.5 galaxy NGC 3227 from 2000 to 2016. In late 2019, another X-ray obscuration event was identified with Swif…
A spectroscopic follow-up for Gaia19bld
Gromadzki, M.; Rybicki, K.; Kruszyńska, K. +11 more
Context. Due to their scarcity, microlensing events in the Galactic disk are of great interest and high-cadence photometric observations, supplemented by spectroscopic follow-up, are necessary for constraining the physical parameters of the lensing system. In particular, a precise estimate of the source characteristics is required to accurately me…
Peculiar X-ray transient SRGA J043520.9+552226/AT2019wey discovered with SRG/ART-XC
Gilfanov, M. R.; Medvedev, P. S.; Sunyaev, R. A. +24 more
Context. During its ongoing all-sky survey, the Mikhail Pavlinsky ART-XC (Astronomical Roentgen Telescope - X-ray Concentrator) telescope on board the Spectrum-Roentgen-Gamma (SRG) observatory is set to discover new X-ray sources, many of which can be transient. Here we report the discovery and multiwavelength follow-up of a peculiar X-ray source …
Random Forest classification of Gaia DR3 white dwarf-main sequence spectra: A feasibility study
Rebassa-Mansergas, Alberto; Torres, Santiago; Echeverry, David +1 more
Aims: The third Gaia data release provides low-resolution spectra for around 200 million sources. It is expected that a sizeable fraction of them contain a white dwarf (WD), neither isolated, or in a binary system with a main-sequence (MS) companion, that is a white dwarf-main sequence (WDMS) binary. Taking advantage of a consolidated Random …
Apsidal motion in massive eccentric binaries in NGC 6231. The case of HD 152219
Farnir, M.; Dupret, M. -A.; Rauw, G. +2 more
Context. The measurement of the apsidal motion in close eccentric massive binary systems provides essential information to probe the internal structure of the stars that compose the system.
Aims: Following the determination of the fundamental stellar and binary parameters, we make use of the tidally induced apsidal motion to infer constraints…
Observational evidence for two-component distributions describing solar magnetic bright points
Utz, Dominik; Gömöry, Peter; Kuckein, Christoph +6 more
Context. High-resolution observations of the solar photosphere reveal the presence of fine structures, in particular the so-called Magnetic Bright Points (MBPs), which are small-scale features associated with strong magnetic field regions of the order of kilogauss (kG). It is especially relevant to study these magnetic elements, which are extensiv…
The eROSITA Final Equatorial-Depth Survey (eFEDS). The first archetypal quasar in the feedback phase discovered by eROSITA
Silverman, J. D.; Georgakakis, A.; Salvato, M. +18 more
Theoretical models of the co-evolution of galaxies and active galactic nuclei (AGNs) ascribe an important role in the feedback process to a short, luminous, obscured, and dust-enshrouded phase during which the accretion rate of the supermassive black hole is expected to be at its maximum and the associated AGN-driven winds are also predicted to be…
A strong H− opacity signal in the near-infrared emission spectrum of the ultra-hot Jupiter KELT-9b
Schlawin, E.; Pino, L.; Désert, J. -M. +11 more
We present the analysis of a spectroscopic secondary eclipse of the hottest transiting exoplanet detected to date, KELT-9b, obtained with the Wide Field Camera 3 aboard the Hubble Space Telescope. We complement these data with literature information on stellar pulsations and Spitzer/Infrared Array Camera and Transiting Exoplanet Survey Satellite e…