Search Publications
Multi-wavelength observations and modelling of a canonical solar flare
Klimchuk, J. A.; Gallagher, P. T.; Milligan, R. O. +1 more
Aims: We investigate the temporal evolution of temperature, emission measure, energy loss, and velocity in a C-class solar flare from both observational and theoretical perspectives.
Methods: The properties of the flare were derived by following the systematic cooling of the plasma through the response functions of a number of instruments - th…
High-energy characteristics of the schizophrenic pulsar PSR J1846-0258 in Kes 75. Multi-year RXTE and INTEGRAL observations crossing the magnetar-like outburst
Kuiper, L.; Hermsen, W.
Aims: PSR J1846-0258 is a young rotation-powered pulsar with one of the highest surface magnetic field strengths, located in the centre of SN-remnant Kes-75. In June 2006 a magnetar-like outburst took place. Using multi-year RXTE and INTEGRAL observations covering the epoch of the outburst, we aim to study the temporal and spectral characteristics…
The X-ray view of giga-hertz peaked spectrum radio galaxies
Guainazzi, M.; Piconcelli, E.; Grandi, P. +5 more
Context: This paper presents the X-ray properties of a flux- and volume-limited complete sample of 16 giga-hertz peaked spectrum (GPS) galaxies.
Aims: This study addresses three basic questions in our understanding of the nature and evolution of GPS sources: a) What is the physical origin of the X-ray emission in GPS galaxies? b) Which physica…
The velocity field of sunspot penumbrae. I. A global view
Franz, M.; Schlichenmaier, R.
Aims. We investigated the vertical penumbral plasma flow on small spatial scales using data recorded by the spectropolarimeter of the solar optical telescope onboard Hinode.
Methods: We computed maps of apparent Doppler velocities by comparing the spectral positions of the Fe I 630.15 nm & Fe I 630.25 nm lines with the averaged line profil…
Properties of WNh stars in the Small Magellanic Cloud: evidence for homogeneous evolution
Martins, F.; Hillier, D. J.; Foellmi, C. +4 more
Aims: We aim to assess the nature of three WNh stars in the SMC, to constrain stellar evolution beyond the main sequence at low metallicity, and to investigate the metallicity dependence of the clumping properties of massive stars.
Methods: We compute atmosphere models to derive the stellar and wind properties of the three WNh targets. A FUV/U…
Keck spectroscopic survey of strongly lensed galaxies in Abell 1703: further evidence of a relaxed, unimodal cluster
Jullo, E.; Richard, J.; Kneib, J. P. +2 more
Context: Strong gravitational lensing is a unique tool that can be used to accurately model the inner mass distribution of massive galaxy clusters. In particular, clusters with large Einstein radii provide a wealth of multiply imaged systems in the cluster core. Measuring the redshift of these multiple images provides strong constraints for precis…
Spatially resolved mid-infrared observations of the triple system T Tauri
Wolf, S.; Ábrahám, P.; Henning, Th. +6 more
Aims: The aim of this study is to enhance our knowledge of the characteristics and distribution of the circumstellar dust associated with the individual components of the young hierarchical triple system T Tau.
Methods: To reach this goal, observations in the N-band (8-13 µm) with the two-telescope interferometric instrument MIDI at the …
A binary engine fuelling HD 87643's complex circumstellar environment. Determined using AMBER/VLTI imaging
Waters, L. B. F. M.; Weigelt, G.; Hofmann, K. -H. +19 more
Context: The star HD 87643, exhibiting the “B[e] phenomenon”, has one of the most extreme infrared excesses for this object class. It harbours a large amount of both hot and cold dust, and is surrounded by an extended reflection nebula.
Aims: One of our major goals was to investigate the presence of a companion in HD87643. In addition, the pre…
EX Lupi in quiescence
Ábrahám, P.; Kóspál, Á.; Kun, M. +5 more
Aims: EX Lupi is the prototype of EXors, a subclass of low-mass pre-main sequence stars whose episodic eruptions are attributed to temporarily increased accretion. In quiescence the optical and near-infrared properties of EX Lup cannot be distinguished from those of normal T Tau stars. Here we investigate whether it is the circumstellar disk struc…
The possible role of vortex shedding in the excitation of kink-mode oscillations in the solar corona
Nakariakov, V. M.; Aschwanden, M. J.; van Doorsselaere, T.
We propose a model for the excitation of horizontally polarised transverse (kink) magnetoacoustic oscillations of solar coronal loops by upflows associated with coronal mass ejections. If the magnetic field in the plasma that is dragged in the vertical direction by the flow is parallel to the loop, the phenomenon of vortex shedding causes the appe…