Search Publications
X-ray emission from classical T Tauri stars: accretion shocks and coronae?
Liefke, C.; Schmitt, J. H. M. M.; Robrade, J. +1 more
Context: Classical T Tauri stars (CTTS) are surrounded by actively accreting disks. According to current models material falls along the magnetic field lines from the disk with more or less free-fall velocity onto the star, where the plasma heats up and generates X-rays.
Aims: We want to quantitatively explain the observed high energy emission…
Cosmic shear analysis of archival HST/ACS data. I. Comparison of early ACS pure parallel data to the HST/GEMS survey
Simon, P.; Heymans, C.; Schrabback, T. +9 more
Context: This is the first paper of a series describing our measurement of weak lensing by large-scale structure, also termed “cosmic shear”, using archival observations from the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST).
Aims: In this work we present results from a pilot study testing the capabilities of the …
Properties of sunspots in cycle 23. I. Dependence of brightness on sunspot size and cycle phase
Solanki, S. K.; Martínez Pillet, V.; Krivova, N. A. +1 more
Aims:In this paper we investigate the dependence of umbral core brightness, as well as the mean umbral and penumbral brightness on the phase of the solar cycle and on the size of the sunspot.
Methods: Albregtsen & Maltby (1978, Nature, 274, 41) reported an increase in umbral core brightness from the early to the late phase of solar cycle f…
Spectrophotometric analysis of Ellerman bombs in the Ca II, Hα, and UV range
Schmieder, B.; Pariat, E.; Wang, S. +4 more
Context: Even if Ellerman bombs have been observed in the Hα line within emerging magnetic flux regions since the early 20th century, their origin and the mechanisms that lead to their formation have been strongly debated. Recently, new arguments in favor of chromospheric magnetic reconnection have been advanced. Ellerman bombs seem to be the sign…
IGR J18483-0311: an accreting X-ray pulsar observed by INTEGRAL
Hill, A. B.; Masetti, N.; Bird, A. J. +8 more
Context: IGR J18483-0311 is a poorly known transient hard X-ray source discovered by INTEGRAL during observations of the Galactic Center region performed between 23-28 April 2003.
Aims: To detect new outbursts from IGR J18483-0311 using INTEGRAL and archival Swift XRT observations and finally to characterize the nature of this source using the…
A CFH12k lensing survey of X-ray luminous galaxy clusters. II. Weak lensing analysis and global correlations
Smail, I.; Kneib, J. -P.; Smith, G. P. +5 more
Aims:We present a wide-field multi-color survey of a homogeneous sample of eleven clusters of galaxies for which we measure total masses and mass distributions from weak lensing. This sample, spanning a small range in both X-ray luminosity and redshift, is ideally suited to determining the normalisation of scaling relations between X-ray propertie…
Proper-motion binaries in the Hipparcos catalogue. Comparison with radial velocity data
Jorissen, A.; Frankowski, A.; Jancart, S.
Context: This paper is the last in a series devoted to the analysis of the binary content of the Hipparcos Catalogue.
Aims: The comparison of the proper motions constructed from positions spanning a short (Hipparcos) or long time (Tycho-2) makes it possible to uncover binaries with periods of the order of or somewhat larger than the short time…
Large amplitude oscillatory motion along a solar filament
Veronig, A. M.; Vršnak, B.; Thalmann, J. K. +1 more
Context: Large amplitude oscillations of solar filaments is a phenomenon that has been known for more than half a century. Recently, a new mode of oscillations, characterized by periodical plasma motions along the filament axis, was discovered.
Aims: We analyze such an event, recorded on 23 January 2002 in Big Bear Solar Observatory Hα filterg…
High-resolution X-ray spectroscopy of T Tauri stars in the Taurus-Auriga complex
Audard, M.; Güdel, M.; Briggs, K. R. +2 more
Context: Differences have been reported between the X-ray emission of accreting and non-accreting stars. Some observations have suggested that accretion shocks could be responsible for part of the X-ray emission in classical T Tauri stars (CTTS).
Aims: We present high-resolution X-ray spectroscopy for nine pre-main sequence stars in order to t…
High-resolution FUSE and HST ultraviolet spectroscopy of the white dwarf central star of Sh 2-216
Rauch, T.; Werner, K.; Kruk, J. W. +5 more
Context: We perform a comprehensive spectral analysis of
Aims: