Search Publications
Gaia reference frame amid quasar variability and proper motion patterns in the data
Lindegren, L.; Hobbs, D.; Bachchan, R. K.
Context. Gaia's very accurate astrometric measurements will allow the optical realisation of the International Celestial Reference System to be improved by a few orders of magnitude. Several sets of quasars are used to define a kinematically stable non-rotating reference frame with the barycentre of the solar system as its origin. Gaia will also o…
The XXL Survey. XII. Optical spectroscopy of X-ray-selected clusters and the frequency of AGN in superclusters
Altieri, B.; Valtchanov, I.; Pierre, M. +13 more
Context. This article belongs to the first series of XXL publications. It presents multifibre spectroscopic observations of three 0.55 deg2 fields in the XXL Survey, which were selected on the basis of their high density of X-ray-detected clusters. The observations were obtained with the AutoFib2+WYFFOS (AF2) wide-field fibre spectrogra…
Linking low- to high-mass young stellar objects with Herschel-HIFI observations of water
Braine, J.; van Dishoeck, E. F.; Johnstone, D. +7 more
Context. Water probes the dynamics in young stellar objects (YSOs) effectively, especially shocks in molecular outflows. It is therefore a key molecule for exploring whether the physical properties of low-mass protostars can be extrapolated to massive YSOs, an important step in understanding the fundamental mechanisms regulating star formation.
Prospects for high-z cluster detections with Planck, based on a follow-up of 28 candidates using MegaCam at CFHT
Dahle, H.; Aussel, H.; Aghanim, N. +13 more
The Planck catalogue of SZ sources limits itself to a significance threshold of 4.5 to ensure a low contamination rate by false cluster candidates. This means that only the most massive clusters at redshift z> 0.5, and in particular z> 0.7, are expected to enter into the catalogue, with a large number of systems in that redshift regime being…
Testing the theory of colliding winds: the periastron passage of 9 Sagittarii. I. X-ray and optical spectroscopy
Gosset, E.; Blomme, R.; Nazé, Y. +7 more
Context. The long-period, highly eccentric O-star binary 9 Sgr, known for its non-thermal radio emission and its relatively bright X-ray emission, went through its periastron in 2013.
Aims: Such an event can be used to observationally test the predictions of the theory of colliding stellar winds over a broad range of wavelengths.
Methods…
Modeling the shock-cloud interaction in SN 1006: Unveiling the origin of nonthermal X-ray and γ-ray emission
Miceli, M.; Decourchelle, A.; Orlando, S. +9 more
Context. The supernova remnant SN 1006 is a source of high-energy particles and its southwestern limb is interacting with a dense ambient cloud, thus is a promising region for γ-ray hadronic emission.
Aims: We aim at describing the physics and the nonthermal emission associated with the shock-cloud interaction to derive the physical parameter…
Multi-wavelength observations of IGR J17544-2619 from quiescence to outburst
Campana, S.; Stella, L.; Chaty, S. +12 more
In this paper we report on a long multi-wavelength observational campaign of the supergiant fast X-ray transient prototype IGR J17544-2619. A 150 ks-long observation was carried out simultaneously with XMM-Newton and NuSTAR, catching the source in an initial faint X-ray state and then undergoing a bright X-ray outburst lasting approximately 7 ks. …
Magnetic field geometry of an unusual cometary cloud Gal 110-13
Neha, S.; Soam, A.; Maheswar, G. +2 more
Aims: We carried out optical polarimetry of an isolated cloud, Gal 110-13, to map the plane-of-the-sky magnetic field geometry. The main aim of the study is to understand the most plausible mechanism responsible for the unusual cometary shape of the cloud in the context of its magnetic field geometry.
Methods: When unpolarized starlight …
Luminous blue variables: An imaging perspective on their binarity and near environment
Rivinius, Thomas; Baade, Dietrich; Mérand, Antoine +18 more
Context. Luminous blue variables (LBVs) are rare massive stars with very high luminosity. They are characterized by strong photometric and spectroscopic variability related to transient eruptions. The mechanisms at the origin of these eruptions is not well known. In addition, their formation is still problematic and the presence of a companion cou…
Prestellar core modeling in the presence of a filament. The dense heart of L1689B
Henning, Th.; Bacmann, A.; Steinacker, J. +1 more
Context. Lacking a paradigm for the onset of star formation, it is important to derive basic physical properties of prestellar cores and filaments like density and temperature structures.
Aims: We aim to disentangle the spatial variation in density and temperature across the prestellar core L1689B, which is embedded in a filament. We want to …