Search Publications
Ground-based variability surveys towards Centaurus A: worthwhile or not?
Héraudeau, P.; de Jong, J. T. A.; Kuijken, K. H.
Context: Difference imaging has proven to be a powerful technique for detecting and monitoring the variability of unresolved stellar sources in M 31. Using this technique in surveys of galaxies outside the Local Group could have many interesting applications.
Aims: The goal of this paper is to test difference imaging photometry on Centaurus A,…
Radiance and Doppler shift distributions across the network of the quiet Sun
Tu, C. -Y.; Tian, H.; He, J. -S. +1 more
Aims: The radiance and Doppler-shift distributions across the solar network provide observational constraints of two-dimensional modeling of transition-region emission and flows in coronal funnels. These distributions have not, however, been studied in detail and we attempt an investigation for a quiet Sun region.
Methods: Two different method…
The complex galaxy cluster Abell 514: New results obtained with the XMM-Newton satellite
Schindler, S.; Gitti, M.; Dolag, K. +1 more
Aims: We study the X-ray morphology and dynamics of the galaxy cluster Abell 514. Also, the relation between the X-ray properties and Faraday Rotation measures of this cluster are investigated in order to study the connection of magnetic fields and the intra-cluster medium.
Methods: We use two combined XMM-Newton pointings that are split into …
The unusual UV continuum of quasar Ton 34 and the possibility of crystalline dust absorption
Binette, L.; Krongold, Y.
Context: Luminous quasars are known to display a sharp steepening of the continuum near 1100 Å. This spectral feature is not well fitted by current accretion disk models, unless Comptonization of the disk emission is invoked. Absorption by carbon crystalline dust has been proposed to account for this feature.
Aims: Ton 34 (zq = 1.92…
The 26 year-long X-ray light curve and the X-ray spectrum of the BL Lacertae object 1E 1207.9+3945 in its brightest state
Tramacere, A.; Giommi, P.; Maselli, A. +4 more
Aims:We studied the temporal and spectral evolution of the synchrotron emission from the high energy peaked BL Lac object 1E 1207.9+3945.
Methods: Two recent observations have been performed by the XMM-Newton and Swift satellites; we carried out X-ray spectral analysis for both of them, and photometry in optical-ultraviolet filters for the Swi…
Small-scale flows in SUMER and TRACE high-cadence co-observations
Doyle, J. G.; Madjarska, M. S.
Context: We report on the physical properties of small-scale transient flows observed simultaneously at high cadence with the SUMER spectrometer and the TRACE imager in the plage area of an active region.
Aims: Our major objective is to provide a better understanding of the nature of transient phenomena in the solar atmosphere by using high-ca…
On the ultraviolet signatures of small scale heating in coronal loops
Young, P. R.; Parenti, S.
Aims: Studying the statistical properties of solar ultraviolet emission lines could provide information about the nature of small scale coronal heating. We expand on previous work to investigate these properties. We study whether the predicted statistical distribution of ion emission line intensities produced by a specified heating function is aff…
EROs found behind lensing clusters. II. Empirical properties, classification, and SED modelling based on multi-wavelength observations
Kneib, J. -P.; Schaerer, D.; Pelló, R. +5 more
Aims:We study the properties and nature of extremely red galaxies (ERO, R-K≥5.6) found behind two lensing clusters and compare them with other known galaxy populations.
Methods: New HST/ACS, Spitzer (IRAC and MIPS), and Chandra/ACIS observations of the two lensing clusters Abell 1835 and AC114 have been obtained, combined with our earlier opti…
Spatial distribution of dust in the shell elliptical NGC 5982
Del Burgo, C.; Carter, D.; Sikkema, G.
Aims:Shells in Ellipticals are peculiar faint sharp edged features that are thought to be formed by galaxy mergers. We determine the shell and dust distributions, and colours of a well-resolved shell and the underlying galaxy in NGC 5982, and compare the spatial distributions of the dust and gas phases, in order to investigate the origin of shells…
Near-infrared polarization images of the Orion proplyds
Eckart, A.; Ott, T.; Rost, S.
Aims: The aim is to study structure and polarization properties of the stars and planet systems in the active Orion H II-region.
Methods: We performed AO-assisted high-resolution imaging polarimetry on selected Orion proplyds close to the Trapezium stars in the J, H, and K bands. Differential polarimetric images of one of the largest and brigh…