Search Publications
Cosmological parameters from strong gravitational lensing and stellar dynamics in elliptical galaxies
Grillo, C.; Lombardi, M.; Bertin, G.
Context: Observations of the cosmic microwave background, light element abundances, large-scale distribution of galaxies, and distant supernovae are the primary tools for determining the cosmological parameters that define the global structure of the Universe.
Aims: Here we illustrate how the combination of observations related to strong gravi…
A synchrotron self-Compton scenario for the very high energy γ-ray emission of the radiogalaxy M 87. Unifying the TeV emission of blazars and other AGNs?
Boisson, C.; Sol, H.; Katarzyński, K. +1 more
Context: M 87 is the first extragalactic source detected in the TeV range that is not a blazar. With the increasing performances of ground-based Čerenkov telescopes, we can now probe the variability in the γ-ray flux on small timescales, thus putting strong constraints on the size of the emitting zone. The large scale jet of M 87 is misaligned wit…
Hinode EUV spectroscopic observations of coronal oscillations
Erdélyi, R.; Taroyan, Y.
Context: Waves offer a unique opportunity to understand and diagnose the properties of the solar coronal plasma.
Aims: Hinode/EIS observations are analysed to detect wave and oscillatory motions in the solar corona.
Methods: The EIS observations were carried out using a selection of EUV lines. Hinode/XRT images are taken concurrently.
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Discovery of a bipolar X-ray jet from the T Tauri star DG Tauri
Audard, M.; Güdel, M.; Briggs, K. R. +2 more
Aims:We have obtained and analyzed Chandra ACIS-S observations of the strongly accreting classical T Tauri star DG Tau. Our principal goals are to map the immediate environment of the star to characterize possible extended X-rays formed in the jet, and to re-visit the anomalous, doubly absorbed X-ray spectrum of DG Tau itself.
Methods: We comb…
Outer edges of debris discs. How sharp is sharp?
Thébault, P.; Wu, Y.
Context: Rings or annulus-like features have been observed in most imaged debris discs. Outside the main ring, while some systems (e.g., β Pictoris and AU Mic) exhibit smooth surface brightness profiles (SB) that fall off roughly as ~r-3.5, others (e.g. HR 4796A and HD 139664) display large drops in luminosity at the ring's outer edge a…
Disks around CQ Tauri and MWC 758: dense PDR or gas dispersal?
Chapillon, E.; Guilloteau, S.; Dutrey, A. +1 more
Context: The overall properties of disks surrounding intermediate PMS stars (HAe) are not yet well constrained by current observations. The disk inclination, which significantly affects spectral energy distribution modeling, is often unknown.
Aims: We attempted to resolve the disks around CQ Tau and MWC 758 to provide accurate constraints on t…
Hinode XRT observations of a long-lasting coronal sigmoid
Canfield, R. C.; McKenzie, D. E.
Aims:Coronal sigmoids are important sources of eruptions into interplanetary space, and a handful of models have been proposed to explain their characteristic S shape. However, the coronal X-ray images available to date have generally not had sufficient resolution to distinguish between these models. The goal of the present investigation is to det…
Magnetic flux cancellation associated with a recurring solar jet observed with Hinode, RHESSI, and STEREO/EUVI
Young, P. R.; Mason, H. E.; Krucker, S. +7 more
Aims: We study the physical properties of a recurring solar active region jet observed in X-rays and extreme-ultraviolet (EUV).
Methods: Multi-wavelength data from all three instruments on board Hinode were analysed. X-ray imaging and spectroscopy of the microflaring emission associated with the jets was performed with the Reuven Ramaty High E…
The red clump absolute magnitude based on revised Hipparcos parallaxes
Groenewegen, M. A. T.
Context: Over the past decade the use of the red clump (RC) as distance indicator has increased in importance as this evolutionary phase is well populated and a good local calibration exists.
Aims: The absolute calibration of the RC in the I and K band is investigated again based on the recently published revised Hipparcos parallaxes.
Meth…
The multiple quasar Q2237+0305 under a microlensing caustic
Schmidt, R. W.; Anguita, T.; Wambsganss, J. +5 more
We use the high magnification event seen in the 1999 OGLE campaign light curve of image C of the quadruply imaged gravitational lens Q2237+0305 to study the structure of the quasar engine. We have obtained g'- and r'-band photometry at the Apache Point Observatory 3.5 m telescope where we find that the event has a smaller amplitude in the r'-band …