Search Publications
X-rays from magnetic intermediate mass Ap/Bp stars
Robrade, Jan
The X-ray emission of magnetic intermediate mass Ap/Bp stars is reviewed and put into context of intrinsic as well as extrinsic hypotheses for its origin. New X-ray observations of Ap/Bp stars are presented and combined with an updated analysis of the available datasets, providing the largest sample of its type that is currently available. In the …
XMM-Newton study of the Draco dwarf spheroidal galaxy
Sasaki, Manami; Saeedi, Sara; Ducci, Lorenzo
Aims: We present the results of the analysis of five XMM-Newton observations of the Draco dwarf spheroidal galaxy (dSph). The aim of the work is the study of the X-ray population in the field of the Draco dSph.
Methods: We classified the sources on the basis of spectral analysis, hardness ratios, X-ray-to-optical flux ratio, X-ray variab…
Analytical model of Europa's O2 exosphere
Mura, Alessandro; Plainaki, Christina; Milillo, Anna +5 more
The origin of the exosphere of Europa is its water ice surface. The existing exosphere models, assuming either a collisionless environment (simple Monte Carlo techniques) or a kinetic approach (Direct Monte Carlo Method) both predict that the major constituent of the exosphere is molecular oxygen. Specifically, O2 is generated at the su…
Calibration of the Voyager Ultraviolet Spectrometers and the Composition of the Heliosphere Neutrals: Reassessment
Holberg, J. B.; Ben-Jaffel, Lotfi
The data harvest from the Voyagers’ (V 1 and V 2) Ultraviolet Spectrometers (UVS) covers encounters with the outer planets, measurements of the heliosphere sky-background, and stellar spectrophotometry. Because their period of operation overlaps with many ultraviolet missions, the calibration of V1 and V2 UVS with other spectrometers is invaluable…
X-ray deficiency on strongly accreting T Tauri stars. Comparing Orion with Taurus
Bouy, H.; Manara, C. F.; Merín, B. +3 more
Context. Depending on whether a T Tauri star accretes material from its circumstellar disk or not, different X-ray emission properties can be found. The accretion shocks produce cool heating of the plasma, contributing to the soft X-ray emission from the star.
Aims: Using X-ray data from the Chandra Orion Ultra-deep Project and accretion rate…
Solution structure of the isolated histone H2A-H2B heterodimer
Moriwaki, Yoshihito; Yamane, Tsutomu; Ohtomo, Hideaki +6 more
During chromatin-regulated processes, the histone H2A-H2B heterodimer functions dynamically in and out of the nucleosome. Although detailed crystal structures of nucleosomes have been established, that of the isolated full-length H2A-H2B heterodimer has remained elusive. Here, we have determined the solution structure of human H2A-H2B by NMR coupl…
Spatial distribution of Langmuir waves observed upstream of Saturn's bow shock by Cassini
Gurnett, D. A.; Hospodarsky, G. B.; Kurth, W. S. +3 more
We present the spatial distribution and spectral properties of Langmuir waves observed upstream of Saturn's bow shock by the Cassini spacecraft. The entire 10 kHz wideband data set obtained between June 2004 and December 2014 has been analyzed using an automated procedure. Almost 106 waveform snapshots with intense narrowband emissions …
Two giant outbursts of V0332+53 observed with INTEGRAL
Kretschmar, Peter; Pottschmidt, Katja; Wilms, Jörn +7 more
Context. In July 2015, the high-mass X-ray binary V0332+53 underwent a giant outburst, a decade after the previous one. V0332+53 hosts a strongly magnetized neutron star. During the 2004-2005 outburst, an anti-correlation between the centroid energy of its fundamental cyclotron resonance scattering features (CRSFs) and the X-ray luminosity was obs…
A Direct Linkage between AGN Outflows in the Narrow-line Regions and the X-Ray Emission from the Accretion Disks
Wang, J.; Wei, J. Y.; Xu, D. W.
The origin of outflow in the narrow-line region (NLR) of the active galactic nucleus (AGN) is studied in this paper by focusing on the relationship between the [O III]λ5007 line profile and the hard-X-ray (in a bandpass of 2-10 keV) emission from the central super-massive black hole (SMBH) in type-I AGNs. A sample of 47 local X-ray selected type-I…
Reconstructing thawing quintessence with multiple datasets
Liddle, Andrew R.; Parkinson, David; Sahlén, Martin +1 more
In this work we model the quintessence potential in a Taylor series expansion, up to second order, around the present-day value of the scalar field. The field is evolved in a thawing regime assuming zero initial velocity. We use the latest data from the Planck satellite, baryonic acoustic oscillations observations from the Sloan Digital Sky Survey…