Search Publications
Dynamical parallax, physical parameters, and evolutionary status of the components of the bright eclipsing binary α Draconis
Bodensteiner, J.; Bowman, D. M.; Tkachenko, A. +13 more
Aims: Both components of the bright eclipsing binary α Dra have been resolved using long baseline interferometry and the secondary component has been shown to contribute approximately 15% of the total flux; however, a spectroscopic detection of the companion star has so far been unsuccessful. We aim for a firm spectroscopic detection of the s…
Lithium on the lower red giant branch of five Galactic globular clusters
Salaris, M.; Pancino, E.; Monaco, L. +3 more
Context. Lithium is one of the few elements produced during Big Bang nucleosynthesis in the early universe. Moreover, its fragility makes it useful as a proxy for stellar environmental conditions. As such, the lithium abundance in old systems is at the core of various astrophysical investigations.
Aims: Stars on the lower red giant branch are…
Asteroid astrometry by stellar occultations: Accuracy of the existing sample from orbital fitting
Tanga, P.; Spoto, F.; Herald, D. +2 more
Context. The technique of stellar occultations, greatly enhanced by the publication of the Gaia data releases, permits not only the determination of asteroid size and shape, but also the retrieval of additional, very accurate astrometry, with a possible relevant impact on the study of dynamical properties. The use of Gaia as reference catalogue an…
Photometric properties of nuclear star clusters and their host galaxies in the Fornax cluster
Janz, Joachim; Peletier, Reynier F.; Salo, Heikki +2 more
Aims: We aim to investigate the relations between nuclear star clusters (NSCs) and their host galaxies and to offer a comparison between the structural properties of nucleated and non-nucleated galaxies. We also address the environmental influences on the nucleation of galaxies in the Fornax main cluster and the Fornax A group.
Methods: …
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 …