Search Publications
A robust automated machine-learning method for the identification of star clusters in the central region of the Small Magellanic Cloud
Hatzidimitriou, D.; Zezas, A.; Antoniou, V. +3 more
Aims: We developed a cluster-detection method based on the code DBSCAN to identify star clusters in the central region of the Small Magellanic Cloud (SMC).
Methods: Two approaches were used to determine the values of the free parameters of DBSCAN. They agree well with each other and can be used in the fields that are studied without any …
Validation of up to seven TESS planet candidates through multi-colour transit photometry using MuSCAT2 data
Tamura, M.; Pallé, E.; Béjar, V. J. S. +62 more
The TESS mission searches for transiting exoplanets by monitoring the brightness of hundreds of thousands of stars across the entire sky. M-type planet hosts are ideal targets for this mission due to their smaller size and cooler temperatures, which makes it easier to detect smaller planets near or within their habitable zones. Additionally, M dwa…
Lifetime of starspots on detached eclipsing binaries: Detecting the effects of tides on stellar activity
Zong, Weikai; Wang, Jiaxin; Pan, Yang +5 more
Context. Tidal deformation breaks the axisymmetric structure of stars, and this may affect stellar activity. This effect has been demonstrated in theoretical analyses and simulations, but it lacks observational support. In this paper, we use spot-modulated detached binaries to study the effect of tides on stellar activity. We show this effect by a…
X-ray occultations in active galactic nuclei: Physical properties of eclipsing clouds as part of the broad-line region cloud ensemble
Risaliti, G.; Pietrini, P.; Torricelli-Ciamponi, G.
Context. Short-term X-ray variability in active galactic nuclei (AGNs) can be explained as being due to varying X-ray absorption induced by the temporary occultation of the primary X-ray source, when moving absorbing clouds cross the line of sight to the X-ray source itself. Earlier work suggests that these absorbing clouds have physical propertie…
The near-infrared degree of polarization in debris disks. Toward a self-consistent approach to model scattered light observations
Bayo, A.; Henning, Th.; Milli, J. +2 more
Context. Debris disks provide a unique opportunity to probe the properties of small µm-sized particles, allowing us to peer into the constituents of their parent bodies, namely the young analogs of comets and the asteroids of our Solar System.
Aims: In the past, studies of the total intensity phase function - that is, the brightness of …
Determination of the SO/PHI-HRT wavefront degradation using multiple defocused images
Schmidt, W.; Woch, J.; Solanki, S. K. +50 more
Context. The Polarimetric and Helioseismic Imager on board the Solar Orbiter mission (SO/PHI) offers refocusing capabilities to cope with the strongly varying thermal environment of the optical system along the spacecraft's elliptical orbit. The series of images recorded during in-flight focus calibrations can be employed for phase diversity analy…
XMM-Newton and NuSTAR discovery of a likely IP candidate XMMU J173029.8–330920 in the Galactic disc
Hailey, Charles J.; Mori, Kaya; Rea, Nanda +7 more
Aims. We aim to characterise the population of low-luminosity X-ray sources in the Galactic plane by studying their X-ray spectra and periodic signals in the light curves. Methods. We are performing an X-ray survey of the Galactic disc using XMM-Newton, and the source XMMU J173029.8–330920 was serendipitously discovered in our campaign. We perform…
AT 2021hdr: A candidate tidal disruption of a gas cloud by a binary super massive black hole system
Bauer, F. E.; Chavushyan, V.; Arévalo, P. +25 more
With a growing number of facilities able to monitor the entire sky and produce light curves with a cadence of days, in recent years there has been an increased rate of detection of sources whose variability deviates from standard behavior, revealing a variety of exotic nuclear transients. The aim of the present study is to disentangle the nature o…
A soft and transient ultraluminous X-ray source with six-hour modulation in the NGC 300 galaxy
Tiengo, A.; de Martino, D.; Pinto, C. +13 more
We investigate the nature of CXOU J005440.5−374320 (J0054), a peculiar bright (∼4 × 1039 erg s−1) and soft X-ray transient in the spiral galaxy NGC 300 with a six-hour periodic flux modulation that was detected in a 2014 Chandra observation. Subsequent observations with Chandra and XMM-Newton, as well as a large observational…
Reconciling concentration to virial mass relations
Saha, Prasenjit; Ferreras, Ignacio; Leier, Dominik +1 more
Context. The concentration-virial mass (c-M) relation is a fundamental scaling relation within the standard cold dark matter (ΛCDM) framework well established in numerical simulations. However, observational constraints of this relation are hampered by the difficulty of characterising the properties of dark matter haloes. Recent comparisons betwee…