Search Publications
1RXS J173021.5-055933: a cataclysmic variable with a fast-spinning magnetic white dwarf
Mukai, K.; Haberl, F.; Gänsicke, B. T. +8 more
Aims:We present the first X-ray observations with the XMM-Newton and INTEGRAL satellites of the recently discovered cataclysmic variable 1RXS J173021.5-055933, together with simultaneous UV and coordinated optical photometry aiming at characterising its broad-band temporal and spectral properties and classifying this system as a magnetic one.
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Young stars and brown dwarfs surrounding Alnilam (ɛ Orionis) and Mintaka (δ Orionis)
Caballero, J. A.; Solano, E.
Aims: We look for new regions to search for substellar objects.
Methods: Two circular areas, 45 arcmin-radius each, centred on the young massive star systems Alnilam and Mintaka in the Orion Belt, were explored. The regions are very young (less than 10 Ma), have low extinction, and are neighbours to σ Orionis (~3 Ma), a young open cluster very…
Capabilities of Philae, the Rosetta Lander
Biele, J.; Ulamec, S.
In situ (and sample return) space missions are the most promising tools to investigate the origin and evolution of comet nuclei. We present the instruments and investigations that will be performed with PHILAE (the ROSETTA Lander) on comet 67P Churyumov Gerasimenko, starting in November 2014, ten years after launch. The rationale and the performan…
Hadronic versus leptonic origin of the gamma-ray emission from supernova remnant RX J1713.7-3946
Völk, H. J.; Berezhko, E. G.
Aims: The hadronic vs. leptonic origin of the gamma-ray emission from the Supernova Remnant RX J1713.7-3946 is discussed both in the light of new observations and from a theoretical point of view.
Methods: The existing good spatial correlation of the gamma-ray emission and the nonthermal X-ray emission is analyzed theoretically. In addition, t…
Average Fe Kα emission from distant AGN
Ebrero, J.; Page, M. J.; Barcons, X. +7 more
Context: One of the most important parameters in the XRB (X-ray background) synthesis models is the average efficiency of accretion onto SMBH (super-massive black holes). This can be inferred from the shape of broad relativistic Fe lines seen in X-ray spectra of AGN (active galactic nuclei). Several studies have tried to measure the mean Fe emissi…
Spectral Hardening in Large Solar Flares
Benz, A. O.; Grigis, P. C.
Observations by the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) are used to quantitatively study the hard X-ray evolution in five large solar flares selected for spectral hardening in the course of the event. The X-ray bremsstrahlung emission from nonthermal electrons is characterized by two spectroscopically distinct phases: impulsive …
Suzaku observations of Markarian 335: evidence for a distributed reflector
Larsson, J.; Ponti, G.; Fabian, A. C. +3 more
We report on a 151-ks net exposure Suzaku observation of the narrow-line Seyfert 1 galaxy Mrk 335. The 0.5-40 keV spectrum contains a broad Fe line, a strong soft excess below about 2 keV and a Compton hump around 20-30 keV. We find that a model consisting of a power law and two reflectors provides the best fit to the time-averaged spectrum. In th…
The Ly-α profile and center-to-limb variation of the quiet Sun
Curdt, W.; Teriaca, L.; Tian, H. +2 more
Aims: We study the emission of the hydrogen Lyman-α line in the quiet Sun, its center-to-limb variation, and its radiance distribution. We also compare quasi-simultaneous Ly-α and Ly-β line profiles.
Methods: We used the high spectral and spatial resolution of the SUMER spectrometer and completed raster scans at various locations along the dis…
Total Solar Irradiance Measurement and Modelling during Cycle 23
Mekaoui, S.; Dewitte, S.
During solar cycle 23, which is now close to its end, variations of the total solar irradiance were measured by six different instruments, providing four independent time series of the irradiance variation over the complete solar cycle. A new composite time series constructed using five of these six instruments provides unprecedented instrument st…
Spatially Resolved Stellar Kinematics of Field Early-Type Galaxies at z = 1: Evolution of the Rotation Rate
van der Wel, Arjen; van der Marel, Roeland P.
We use the spatial information of our previously published VLT/FORS2 absorption-line spectroscopy to measure mean stellar velocity and velocity dispersion profiles of 25 field early-type galaxies at a median redshift z = 0.97 (full range 0.6 < z < 1.2). This provides the first detailed study of early-type galaxy rotation at these redshifts. …