Search Publications
On-axis spectroscopy of the host galaxies of 20 optically luminous quasars at z ~ 0.3
Magain, P.; Jahnke, K.; Jablonka, P. +4 more
We present the analysis of a sample of 20 bright low-redshift quasars (MB < -23 and z < 0.35) observed spectroscopically with the Very Large Telescope (VLT). The Focal Reducer/low dispersion Spectrograph (FORS1) spectra, obtained in Multi-Object Spectroscopy (MOS) mode, allow to observe simultaneously the quasars and several refer…
XMM-Newton Discovery of 7 s Pulsations in the Isolated Neutron Star RX J1856.5-3754
Mereghetti, Sandro; Tiengo, Andrea
Thanks to the high counting statistics provided by a recent XMM-Newton observation of RX J1856.5-3754, we have discovered that this isolated neutron star pulsates at a period of 7.055 s. This confirms that RX J1856.5-3754 is similar in nature to the other six thermally emitting, nearby neutron stars discovered in soft X-rays with ROSAT. The pulsat…
Valley formation on martian volcanoes in the Hesperian: Evidence for melting of summit snowpack, caldera lake formation, drainage and erosion on Ceraunius Tholus
Head, James W.; Fassett, Caleb I.
Ceraunius Tholus, a Hesperian-aged volcano in the Tharsis region, is characterized by small radial valleys on its flanks, and several larger valleys originating near its summit caldera. All of these large valleys drain from near the lowest present portion of the caldera rim and down the flanks of the volcano. The largest valley debauches into Rahe…
The Magnificent Seven in the dusty prairie: The role of interstellar absorption on the observed neutron star population
Haberl, F.; Neuhäuser, R.; Turolla, R. +3 more
The Magnificent Seven have all been discovered by their exceptional soft X-ray spectra and high ratios of X-ray to optical flux. They all are considered to be nearby sources. Searching for similar objects with larger distances, one expects larger interstellar absorption resulting in harder X-ray counterparts. Current interstellar absorption treatm…
The first high-resolution X-ray spectrum of a Herbig star: AB Aurigae
Audard, M.; Güdel, M.; Briggs, K. R. +3 more
Context: The X-ray emission from Herbig Ae/Be stars remains to be explained. In later-type T Tauri stars, X-rays are thought to be produced by magnetically trapped coronal plasma, although accretion-shock induced X-rays have also been suggested. In earlier-type (OB) stars, shocks in unstable winds are thought to produce X-rays.
Aims: We presen…
High-redshift Fanaroff-Riley type II radio sources: large-scale X-ray environment
Hardcastle, M. J.; Croston, J. H.; Worrall, D. M. +1 more
We investigate the properties of the environment around 20 powerful radio galaxies and quasars at redshifts between 0.45 and 1. Using XMM-Newton and Chandra observations we probe the spatial distribution and the temperature of the cluster gas. We find that more than 60 per cent of powerful radio sources in the redshift range of our sample lie in a…
Physical parameters and multiplicity of five southern close eclipsing binaries
Mészáros, Sz.; Csizmadia, Sz.; Kiss, L. L. +2 more
Aims:We detected tertiary components of close binaries from spectroscopy and light curve modelling, investigated the light-travel time effect and the possibility of magnetic activity cycles, measured mass ratios for unstudied systems, and derived absolute parameters.
Methods: We carried out new photometric and spectroscopic observations of fiv…
X-rays from RU Lupi: accretion and winds in classical T Tauri stars
Schmitt, J. H. M. M.; Robrade, J.
Context: Low-mass stars are known to exhibit strong X-ray emission during their early evolutionary stages. This also applies to classical T Tauri stars (CTTS), whose X-ray emission differs from that of main-sequence stars in a number of aspects.
Aims: We study the specific case of RU Lup, a well known accreting and wind-driving CTTS. In compar…
Global view of dayside magnetic reconnection with the dusk-dawn IMF orientation: A statistical study for Double Star and Cluster data
Lucek, E.; Dunlop, M. W.; Rème, H. +14 more
Double Star/TC-1 and Cluster data show that both component reconnection and anti-parallel reconnection occur at the magnetopause when the interplanetary magnetic field (IMF) is predominantly dawnward. The occurrence of these different features under these very similar IMF conditions are further confirmed by a statistical study of 290 fast flows me…
ACS Photometry of Newly Discovered Globular Clusters in the Outer Halo of M31
Mackey, A. D.; Tanvir, N. R.; Ferguson, A. M. N. +6 more
We report the first results from deep ACS imaging of 10 classical globular clusters in the far outer regions (15 kpc<~Rp<~100 kpc) of M31. Eight of the clusters, including two of the most remote M31 globular clusters presently known, are described for the first time. Our F606W, F814W color-magnitude diagrams extend ~3 mag below th…