Search Publications

Global Climate Models of the Terrestrial Planets

Forget, F.; Lebonnois, S.

Constraining the luminosity function of faint undetected i-dropout galaxies

Koekemoer, A. M.; Stiavelli, M.; Morelli, L. +5 more

We present a new technique to quantify the light contribution coming from the faint high-redshift (z ∼ 6) galaxies below the detection threshold of imaging data, set conventionally at S/N = 4.5. We illustrate the technique with an application to Hubble Space Telescope Advanced Camera for Surveys images in the F775W and F850LP filters of the Ultra …

An XMM-Newton view of the M 17 nebula

Mernier, F.; Rauw, G.

We present the analysis of an XMM-Newton observation of the M 17 nebula. The X-ray point source population consists of massive O-type stars and a population of probable low-mass pre-main sequence stars. CEN 1a,b and OI 352, the X-ray brightest O-type stars in M 17, display hard spectra (kT of 3.8 and 2.6 keV) consistent with a colliding wind origi…

Variations of Magnetic Bright Point Properties with Longitude and Latitude as Observed by Hinode/SOT G-band Data

Veronig, A.; Utz, D.; Hanslmeier, A. +4 more

Small-scale magnetic fields can be observed on the Sun in high-resolution G-band filtergrams as magnetic bright points (MBPs). We study Hinode/Solar Optical Telescope (SOT) longitude and latitude scans of the quiet solar surface taken in the G-band in order to characterise the centre-to-limb dependence of MBP properties (size and intensity). We fi…

Coherent amplitude modulation of electron-beam-driven Langmuir waves

Baumgärtel, K.

A linear approach to the phenomenon of irregular amplitude modulation of beam-driven Langmuir waves, developed in a previous paper, is extended to explain periodic modulation as well. It comes about by beating of the fastest growing mode of the instability with beam-aligned plasma oscillations. They are naturally generated in a uniform domain of b…

XMM-Newton observations of RR Telescopii: evidence for wind signatures and shocked gas emission

Selvelli, P.; González-Riestra, R.; Cassatella, A.

RR Telescopii is the prototype of the symbiotic novae class. Since its outburst in 1944, it has been slowly fading, and its emission-line spectrum has evolved significantly. In this paper we discuss XMM-Newton observations of RR Tel taken in April 2009. These are the first X-ray high-resolution spectra of this system, and they provide important in…

Nonlinear interaction of kinetic Alfvén wave and whistler: Turbulent spectra and anisotropic scaling

Sharma, R. P.; Kumar Dwivedi, Navin

In this work, we are presenting the excitation of oblique propagating whistler wave as a consequence of nonlinear interaction between whistler wave and kinetic Alfvén wave (KAW) in intermediate beta plasmas. Numerical simulation has been done to study the transient evolution of magnetic field structures of KAW when the nonlinearity arises due to p…

An analysis of CoRoT multicolour photometry of exoplanets

Poretti, E.; Borsa, F.

We analysed the chromatic data of the planetary transits observed with CoRoT to supply homogeneous time series in each of the CoRoT colours. In a first step, we cleaned the chromatic light curves from the contamination of nearby stars and removed outliers and trends caused by anything different from the planetary transits. Then, we simultaneously …

A comprehensive study of NGC 2023 with XMM-Newton and Spitzer

Pérez-González, P. G.; Albacete-Colombo, J. F.; López-Santiago, J. +2 more

Nearby star-forming regions are ideal laboratories to study high-energy emission of different stellar populations, from very massive stars to brown dwarfs. NGC 2023 is a reflection nebula situated to the south of the Flame Nebula (NGC 2024) and at the edge of the H ii region IC 434, which also contains the Horsehead Nebula (Barnard 33). NGC 2023, …

On the role of current dissipation in the energization of coronal bright points

Adamson, E.; Otto, A.; Büchner, J.

Aims: In the context of the contributions by DC dissipation to the energization of solar coronal X-ray and EUV bright points, we analyze the role of Joule heating in the formation of X-ray and EUV coronal bright points through current dissipation due to anomalous resistivity.
Methods: We utilized the improved resistive MHD simulation cod…