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Determination of fundamental asteroseismic parameters using the Hilbert transform
Roth, Markus; Schad, Ariane; Kiefer, René +1 more
Context. Solar-like oscillations exhibit a regular pattern of frequencies. This pattern is dominated by the small and large frequency separations between modes. The accurate determination of these parameters is of great interest, because they give information about e.g. the evolutionary state and the mass of a star.
Aims: We want to develop a…
Comparisons of electron acceleration efficiency among different structures during magnetic reconnection: a Cluster multicase study
Li, H.; Zhou, M.; Li, T. +2 more
Magnetic reconnection has long been believed to be an efficient engine for energetic electrons production. Four different structures have been proposed for electrons being energized: flux pileup region, density cavity located around the separatrix, magnetic island and thin current sheet. In this paper, we compare the electron acceleration efficien…
The legacy of Venus Express: highlights from the first European planetary mission to Venus
Drossart, Pierre; Montmessin, Franck
The ESA/Venus Express mission spent more than 8 years in orbit around Venus to extensively study its atmosphere, ionosphere and plasma environment and unveil new aspects of its surface. Extensive reviews of the work of Venus Express are underway, to cover in-depth studies of the new face of Venus revealed by Venus Express and ground-based concurre…
Revised cosmological parameters after BICEP 2 and BOSS
Das, Santanu; Souradeep, Tarun; Mukherjee, Suvodip
Estimation of parameters of the 'standard' model of cosmology have dramatically improved over past few decades due to increasingly exquisite measurements made by Cosmic Microwave Background (CMB) experiments. Recent data from Planck matches well with the minimal ΛCDM model. A likelihood analysis using Planck, WMAP and a selection of high resolutio…
Subdominant Dark Matter sterile neutrino resonant production in the light of PLANCK
Popa, L. A.; Tonoiu, D.
Few independent detections of a weak X-ray line at an energy of ~ 3.5 keV seen toward a number of astrophysical sites have been reported. If this signal will be confirmed to be the signature of decaying DM sterile neutrino with a mass of ~ 7.1 keV, then the cosmological observables should be consistent with its properties.
A young star cluster in the Leo A galaxy
Narbutis, D.; Vansevičius, V.; Bridžius, A. +2 more
We report a serendipitous discovery of a star cluster in the dwarf irregular galaxy Leo A. Young age ( ∼28 Myr) and low mass ( ∼510 M⊙) estimates are based on the isochrone fit assuming a metallicity derived for H II regions (Z=0.0007). The color-magnitude diagrams of the stars, located in and around the cluster area, and the results of…
Spacecraft Doppler tracking with possible violations of LLI and LPI: upper bounds from one-way measurements on MEX
Xie, Yi; Huang, Yong
We analyze the post-fit residuals of one-way Doppler tracking data from the Mars Express (MEX) spacecraft to test possible violations of local Lorentz invariance (LLI) and local position invariance (LPI). These one-way Doppler observations were carried out on 2011 August 7 for about 20 minutes at Sheshan Station of Shanghai Astronomical Observator…
Revealing the cold dust in low-metallicity environments (Corrigendum). I. Photometry analysis of the Dwarf Galaxy Survey with Herschel
Ciesla, L.; Boquien, M.; Roussel, H. +21 more
X-rays from the oxygen-type Wolf-Rayet binary WR 30a
Skinner, Stephen L.; Zhekov, Svetozar A.
We present an analysis of XMM-Newton X-ray data of WR 30a (WO+O), a close massive binary that harbours an oxygen-rich Wolf-Rayet star. Its spectrum is characterized by the presence of two well-separated broad peaks, or `bumps', one peaking at energies between 1 and 2 keV and the other between 5 and 7 keV. A two-component model is required to match…
Self-consistent electrostatic simulations of reforming double layers in the downward current region of the aurora
Gunell, H.; Andersson, L.; De Keyser, J. +1 more
The plasma on a magnetic field line in the downward current region of the aurora is simulated using a Vlasov model. It is found that an electric field parallel to the magnetic fields is supported by a double layer moving toward higher altitude. The double layer accelerates electrons upward, and these electrons give rise to plasma waves and electro…