Search Publications
Incoherent fast variability of X-ray obscurers. The case of NGC 3783
Kaastra, J. S.; Kriss, G. A.; Arav, N. +22 more
Context. Obscuration events caused by outflowing clumps or streams of high column density and low ionised gas, shown to absorb the X-ray continuum heavily, have been witnessed across a number of Seyfert galaxies.
Aims: We report on the X-ray spectral-timing analysis of the December 2016 obscuration event in NGC 3783, which was aimed at probin…
Searching for central stars of planetary nebulae in Gaia DR2
Walton, N. A.; Chornay, N.
Context. Accurate distance measurements are fundamental to the study of planetary nebulae (PNe) but they have long been elusive. The most accurate and model-independent distance measurements for galactic PNe come from the trigonometric parallaxes of their central stars, which were only available for a few tens of objects prior to the Gaia mission.…
Tidal tails of open star clusters as probes to early gas expulsion. II. Predictions for Gaia
Kroupa, Pavel; Dinnbier, František
Aims: We study the formation and evolution of the tidal tail released from a young star Pleiades-like cluster, due to expulsion of primordial gas in a realistic gravitational field of the Galaxy. The tidal tails (as well as clusters) are integrated from their embedded phase for 300 Myr. We vary star formation efficiencies (SFEs) from 33% to 1…
Optical and near-infrared observations of the Fried Egg Nebula. Multiple shell ejections on a 100 yr timescale from a massive yellow hypergiant
Millour, F.; de Wit, W. -J.; Szczerba, R. +15 more
Context. The fate of a massive star during the latest stages of its evolution is highly dependent on its mass-loss rate and geometry and therefore knowing the geometry of the circumstellar material close to the star and its surroundings is crucial.
Aims: We aim to provide insight into the nature (i.e. geometry, rates) of mass-loss episodes, a…
VVVX-Gaia discovery of a low luminosity globular cluster in the Milky Way disk
Minniti, D.; Rejkuba, M.; Ripepi, V. +21 more
Context. Milky Way globular clusters (GCs) are difficult to identify at low Galactic latitudes because of high differential extinction and heavy star crowding. The new deep near-infrared (IR) images and photometry from the VISTA Variables in the Via Láctea Extended Survey (VVVX) allow us to chart previously unexplored regions.
Aims: Our long …
ORIGIN: Blind detection of faint emission line galaxies in MUSE datacubes
Bacon, Roland; Piqueras, Laure; Mary, David +2 more
Context. One of the major science cases of the Multi Unit Spectroscopic Explorer (MUSE) integral field spectrograph is the detection of Lyman-alpha emitters at high redshifts. The on-going and planned deep fields observations will allow for one large sample of these sources. An efficient tool to perform blind detection of faint emitters in MUSE da…
Cataloging accreted stars within Gaia DR2 using deep learning
Hopkins, P. F.; Ostdiek, B.; Necib, L. +6 more
Aims: The goal of this study is to present the development of a machine learning based approach that utilizes phase space alone to separate the Gaia DR2 stars into two categories: those accreted onto the Milky Way from those that are in situ. Traditional selection methods that have been used to identify accreted stars typically rely on full 3…
Estimating the size of X-ray lamppost coronae in active galactic nuclei
Done, C.; Petrucci, P. -O.; Matt, G. +3 more
Aims: We report estimates of the X-ray coronal size of active galactic nuclei in the lamppost geometry. In this commonly adopted scenario, the corona is assumed for simplicity to be a point-like X-ray source located on the axis of the accretion disc. However, the corona must intercept a number of optical/UV seed photons from the disc consiste…
Possible ∼0.4 h X-ray quasi-periodicity from an ultrasoft active galactic nucleus
Xue, Y. Q.; Shu, X. W.; Wang, T. G. +6 more
RX J1301.9+2747 is an ultrasoft active galactic nucleus (AGN) with unusual X-ray variability that is characterized by a long quiescent state and a short-lived flare state. The X-ray flares are found to recur quasi-periodically on a timescale of 13-20 ks. Here, we report the analysis of the light curve in the quiescent state from two XMM-Newton obs…
Mitigating flicker noise in high-precision photometry. I. Characterization of the noise structure, impact on the inferred transit parameters, and predictions for CHEOPS observations
Veronig, A.; Fossati, L.; Lendl, M. +4 more
Context. In photometry, the short-timescale stellar variability ("flicker"), such as that caused by granulation and solar-like oscillations, can reach amplitudes comparable to the transit depth of Earth-sized planets and is correlated over the typical transit timescales. It can introduce systematic errors on the inferred planetary parameters when …