Search Publications
Bright flares in supergiant fast X-ray transients
Sidoli, L.; Postnov, K.; Paizis, A. +1 more
At steady low-luminosity states, supergiant fast X-ray transients (SFXTs) can be at the stage of quasi-spherical settling accretion on to slowly rotating magnetized neutron stars from the OB-companion winds. At this stage, a hot quasi-static shell is formed above the magnetosphere, the plasma entry rate into magnetosphere is controlled by (ineffic…
The Broad-band X-Ray Spectrum of IC 4329A from a Joint NuSTAR/Suzaku Observation
Harrison, F. A.; Stern, D.; Zhang, W. W. +16 more
We have obtained a deep, simultaneous observation of the bright, nearby Seyfert galaxy IC 4329A with Suzaku and NuSTAR. Through a detailed spectral analysis, we are able to robustly separate the continuum, absorption, and distant reflection components in the spectrum. The absorbing column is found to be modest ({\sim }6 \times 10^{21} {\, cm^{-2}\…
Dawn-dusk asymmetries in the coupled solar wind-magnetosphere-ionosphere system: a review
Wing, S.; Haaland, S.; Soucek, J. +8 more
Dawn-dusk asymmetries are ubiquitous features of the coupled solar-wind-magnetosphere-ionosphere system. During the last decades, increasing availability of satellite and ground-based measurements has made it possible to study these phenomena in more detail. Numerous publications have documented the existence of persistent asymmetries in processes…
Titan’s internal structure inferred from its gravity field, shape, and rotation state
Tobie, Gabriel; Lefèvre, Axel; Baland, Rose-Marie +1 more
Several quantities measured by the Cassini-Huygens mission provide insight into the interior of Titan: the second-degree gravity field coefficients, the shape, the tidal Love number, the electric field, and the orientation of its rotation axis. The measured obliquity and tides, as well as the electric field, are evidence for the presence of an int…
No Evidence of Chemical Anomalies in the Bimodal Turnoff Cluster NGC 1806 in the Large Magellanic Cloud
Dalessandro, E.; Mucciarelli, A.; Origlia, L. +2 more
We have studied the chemical composition of NGC 1806, a massive, intermediate-age globular cluster that shows a double main sequence turnoff. We analyzed a sample of high-resolution spectra (secured with FLAMES at the Very Large Telescope) for eight giant stars, members of the cluster, finding an average iron content of [Fe/H] = -0.60 ± 0.01 dex a…
Observational Evidence of Torus Instability as Trigger Mechanism for Coronal Mass Ejections: The 2011 August 4 Filament Eruption
Mierla, M.; Seaton, D. B.; Poedts, S. +4 more
Solar filaments are magnetic structures often observed in the solar atmosphere and consist of plasma that is cooler and denser than their surroundings. They are visible for days—even weeks—which suggests that they are often in equilibrium with their environment before disappearing or erupting. Several eruption models have been proposed that aim to…
Relating jet structure to photometric variability: the Herbig Ae star HD 163296
Mendigutía, I.; Kaper, L.; Podio, L. +21 more
Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability. This "jet fossil record" can be used to reconstruct the outflow history. We present the first optical to nea…
Revisiting CoRoT RR Lyrae stars: detection of period doubling and temporal variation of additional frequencies
Poretti, E.; Baglin, A.; Szabó, R. +7 more
Context. High-precision, space-based photometric missions like CoRoT and Kepler have revealed new and surprising phenomena in classical variable stars. Such discoveries were the period doubling in RR Lyrae stars and the frequent occurrence of additional periodicities some of which can be explained by radial overtone modes, but others are discordan…
Spectroscopic Redshifts of Galaxies within the Frontier Fields
Ebeling, Harald; Ma, Cheng-Jiun; Barrett, Elizabeth
We present a catalog of 1921 spectroscopic redshifts measured in the fields of the massive galaxy clusters MACSJ0416.1-2403 (z = 0.397), MACSJ0717.5+3745 (z = 0.546), and MACSJ1149.5+2223 (z = 0.544), i.e., three of the four clusters selected by Space Telescope Science Institute as the targets of the Frontier Fields (FFs) initiative for studies of…
Standard Clock in primordial density perturbations and cosmic microwave background
Namjoo, Mohammad Hossein; Chen, Xingang
Standard Clocks in the primordial epoch leave a special type of features in the primordial perturbations, which can be used to directly measure the scale factor of the primordial universe as a function of time a (t), thus discriminating between inflation and alternatives. We have started to search for such signals in the Planck 2013 data using the…