Search Publications
Coronal origin of the polarization of the high-energy emission of Cygnus X-1
Chaty, S.; Romero, G. E.; Vieyro, F. L.
Context. Cygnus X-1 is the candidate with the highest probability of containing a black hole among the X-ray binary systems in the Galaxy. It is also by far the most often studied of these objects. Recently, the International Gamma-Ray Astrophysics Laboratory Imager on board the Integral satellite (INTEGRAL/IBIS) detected strong polarization in th…
The central dynamics of M3, M13, and M92: stringent limits on the masses of intermediate-mass black holes
Roth, M. M.; Kamann, S.; Wisotzki, L. +4 more
We used the PMAS integral field spectrograph to obtain large sets of radial velocities in the central regions of three northern Galactic globular clusters:
An interferometric study of the post-AGB binary 89 Herculis. II. Radiative transfer models of the circumbinary disk
Regibo, S.; Wevers, T.; Verhoelst, T. +6 more
Context. The presence of stable disks around post-asymptotic giant branch (post-AGB) binaries is a widespread phenomenon. Also, the presence of (molecular) outflows is now commonly inferred in these systems.
Aims: In the first paper of this series, a surprisingly large fraction of optical light was found to be resolved in the 89 Her post-AGB …
The radial gradient of the near-surface shear layer of the Sun
Schou, J.; Gizon, L.; Barekat, A.
Context. Helioseismology has provided unprecedented information about the internal rotation of the Sun. One of the important achievements was the discovery of two radial shear layers: one near the bottom of the convection zone (the tachocline) and one near the surface. These shear layers may be important ingredients for explaining the magnetic cyc…
Vertical velocities from proper motions of red clump giants
López-Corredoira, M.; Figueras, F.; Garzón, F. +1 more
Aims: We derive the vertical velocities of disk stars in the range of Galactocentric radii of R = 5 - 16 kpc within 2 kpc in height from the Galactic plane. This kinematic information is connected to dynamical aspects in the formation and evolution of the Milky Way, such as the passage of satellites and vertical resonance and determines wheth…
The return to the hard state of GX 339-4 as seen by Suzaku
Petrucci, P. -O.; Fender, R.; Koerding, E. +2 more
Disk recession is of prime importance to understand the physics of the state transitions in X-ray binaries. The microquasar GX 339-4 was observed by Suzaku five times spaced by a few days during its transition back to the hard state at the end of its 2010-2011 outburst. The 2-10 keV source flux decreases by a factor ~10 between the beginning and t…
Can the magnetic field in the Orion arm inhibit the growth of instabilities in the bow shock of Betelgeuse?
Decin, L.; van Marle, A. J.; Meliani, Z.
Context. Many evolved stars travel through space at supersonic velocities, which leads to the formation of bow shocks ahead of the star where the stellar wind collides with the interstellar medium (ISM). Herschel observations of the bow shock of α-Orionis show that the shock is almost free of instabilities, despite being, at least in theory, subje…
PKS 1510-089: a rare example of a flat spectrum radio quasar with a very high-energy emission
Barnacka, Anna; Moderski, Rafal; Behera, Bagmeet +2 more
Context. The blazar
The low-high-low trend of type III radio burst starting frequencies and solar flare hard X-rays
Kontar, Eduard P.; Vilmer, Nicole; Reid, Hamish A. S.
Aims: Using simultaneous X-ray and radio observations from solar flares, we investigate the link between the type III radio burst starting frequency and hard X-ray spectral index. For a proportion of events the relation derived between the starting height (frequency) of type III radio bursts and the electron beam velocity spectral index (dedu…
An empirical mass-loss law for Population II giants from the Spitzer-IRAC survey of Galactic globular clusters
Dalessandro, E.; Valenti, E.; Rich, R. M. +4 more
Aims: The main aim of the present work is to derive an empirical mass-loss (ML) law for Population II stars in first and second ascent red giant branches.
Methods: We used the Spitzer InfraRed Array Camera (IRAC) photometry obtained in the 3.6-8 µm range of a carefully chosen sample of 15 Galactic globular clusters spanning the ent…