Search Publications
LoTSS/HETDEX: Optical quasars. I. Low-frequency radio properties of optically selected quasars
Prandoni, I.; Callingham, J. R.; Shimwell, T. W. +17 more
The radio-loud/radio-quiet (RL/RQ) dichotomy in quasars is still an open question. Although it is thought that accretion onto supermassive black holes in the centre the host galaxies of quasars is responsible for some radio continuum emission, there is still a debate as to whether star formation or active galactic nuclei (AGN) activity dominate th…
Extended halo of NGC 2682 (M 67) from Gaia DR2
Jordi, C.; Cantat-Gaudin, T.; Balaguer-Núñez, L. +8 more
Context. NGC 2682 is a nearby open cluster that is approximately 3.5 Gyr old. Dynamically, most open clusters are expected to dissolve on shorter timescales of ≈1 Gyr. That it has survived until now means that NGC 2682 was likely much more massive in the past and is bound to have an interesting dynamical history.
Aims: We investigate the spat…
The RWST, a comprehensive statistical description of the non-Gaussian structures in the ISM
Boulanger, F.; Levrier, F.; Zhang, S. +5 more
The interstellar medium (ISM) is a complex nonlinear system governed by the interplay between gravity and magneto-hydrodynamics, as well as radiative, thermodynamical, and chemical processes. Our understanding of it mostly progresses through observations and numerical simulations, and a quantitative comparison between these two approaches requires…
Transiting exocomets detected in broadband light by TESS in the β Pictoris system
Zwintz, K.; Kennedy, G. M.; Zieba, S. +1 more
Aims: We search for signs of falling evaporating bodies (FEBs, also known as exocomets) in photometric time series obtained for β Pictoris after fitting and removing its δ Scuti-type pulsation frequencies.
Methods: Using photometric data obtained by the TESS satellite we determined the pulsational properties of the exoplanet host star β …
Stokes inversion based on convolutional neural networks
Asensio Ramos, A.; Díaz Baso, C. J.
Context. Spectropolarimetric inversions are routinely used in the field of solar physics for the extraction of physical information from observations. The application to two-dimensional fields of view often requires the use of supercomputers with parallelized inversion codes. Even in this case, the computing time spent on the process is still very…
Quasars as standard candles II. The non-linear relation between UV and X-ray emission at high redshifts
Vignali, C.; Lusso, E.; Salvestrini, F. +2 more
A tight non-linear relation between the X-ray and the optical-ultraviolet (UV) emission has been observed in active galactic nuclei (AGN) over a wide range of redshift and several orders of magnitude in luminosity, suggesting the existence of an ubiquitous physical mechanism regulating the energy transfer between the accretion disc and the X-ray e…
Non-LTE chemical abundances in Galactic open and globular clusters
Ting, Yuan-Sen; Kovalev, Mikhail; Rix, Hans-Walter +1 more
Aims: We study the effects of non-local thermodynamic equilibrium (NLTE) on the determination of stellar parameters and abundances of Fe, Mg, and Ti from the medium-resolution spectra of FGK stars.
Methods: We extended the Payne fitting approach to draw on NLTE and LTE spectral models. These were used to analyse the spectra of the Gaia-E…
Stringent limits on the magnetic field strength in the disc of TW Hya. ALMA observations of CN polarisation
Testi, L.; Williams, J. P.; Facchini, S. +8 more
Despite their importance in the star formation process, measurements of magnetic field strength in proto-planetary discs remain rare. While linear polarisation of dust and molecular lines can give insight into the magnetic field structure, only observations of the circular polarisation produced by Zeeman splitting provide a direct measurement of m…
Spatial segregation of dust grains in transition disks. SPHERE observations of 2MASS J16083070-3828268 and RXJ1852.3-3700
Pinte, C.; Ménard, F.; Dent, W. R. F. +27 more
Context. The mechanisms governing the opening of cavities in transition disks are not fully understood. Several processes have been proposed, but their occurrence rate is still unknown.
Aims: We present spatially resolved observations of two transition disks, and aim at constraining their vertical and radial structure using multiwavelength ob…
Blobs, spiral arms, and a possible planet around HD 169142
Henning, T.; Fantinel, D.; D'Orazi, V. +24 more
Context. Young planets are expected to cause cavities, spirals, and kinematic perturbations in protostellar disks that may be used to infer their presence. However, a clear detection of still-forming planets embedded within gas-rich disks is still rare.
Aims: HD 169142 is a very young Herbig Ae-Be star surrounded by a pre-transitional disk, c…