Search Publications
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…
The HST view of the broad line region in low luminosity AGN
Capetti, A.; Balmaverde, B.
We analyze the properties of the broad line region (BLR) in low luminosity AGN by using HST/STIS spectra. We consider a sample of 24 nearby galaxies in which the presence of a BLR has been reported from their Palomar ground-based spectra. Following a widely used strategy, we used the [S II] doublet to subtract the contribution of the narrow emissi…
CLASH: Photometric redshifts with 16 HST bands in galaxy cluster fields
Infante, L.; Zheng, W.; Molino, A. +35 more
Context. The Cluster Lensing And Supernovae survey with Hubble (CLASH) is a Hubble Space Telescope (HST) Multi-Cycle Treasury programme thatobserves 25 massive galaxy clusters, 20 of which were X-ray-selected to preferably choose dynamically relaxed clusters, and 5 additional "high magnification" clusters, which were selected based on their optica…
Origin and z-distribution of Galactic diffuse [C II] emission
Langer, W. D.; Velusamy, T.
Context. The [C ii] emission is an important probe of star formation in the Galaxy and in external galaxies. The GOT C+ survey and its follow up observations of spectrally resolved 1.9 THz [C ii] emission using Herschel HIFI provides the data needed to quantify the Galactic interstellar [C ii] gas components as tracers of star formation.
Aims…