Search Publications

Enhanced timing accuracy for Cluster data

Walker, S. N.; Yearby, K. H.; Balikhin, M. A.

The standard timing accuracy for the Cluster mission is ±2 ms. However for inter-spacecraft comparisons of waveform data, a much higher accuracy is needed - for example a timing error of 1 ms results in a phase error of 65° for a signal at 180 Hz. Most Cluster data are recorded on an onboard solid state recorder and time-stamped using an onboard c…

Direct model fitting to combine dithered ACS images

Wucknitz, O.; Mahmoudian, H.

The information lost in images of undersampled CCD cameras can be recovered with the technique of "dithering". A number of subexposures is taken with sub-pixel shifts in order to record structures on scales smaller than a pixel. The standard method to combine such exposures, "Drizzle", averages after reversing the displacements, including rotation…

Elemental abundances of the supergiant stars σ Cygnus and η Leonis

Tanrıverdi, Taner

This study aims to analyse the elemental abundances for the late B type supergiant star σ Cyg and the early A-type supergiant η Leo using ATLAS9 (Kurucz, 1995; Sbordone et al., 2004), assuming local thermodynamic equilibrium (LTE). The spectra used in this study are obtained from Dominion Astrophysical Observatory and have high resolution and sign…

Scaling relations with a complete sample of galaxy groups

Lovisari, L.; Reiprich, T. H.

Galaxy clusters are an attractive tool to constrain cosmological parameters and well-determined scaling relations between X-ray observables and cluster mass give us a precious diagnostic to study the thermodynamical history of the intra-cluster medium (ICM). We are in the process of improving the accuracy of scaling relations using a complete samp…

The spectroscopic orbit of the K-giant binary γ Canis Minoris

Strassmeier, K. G.; Weber, M.; Pourbaix, D. +2 more

We have determined an improved orbit for the bright, evolved, double lined binary γ Canis Minoris. The system has an orbital period of 389.31 days and an eccentricity of 0.2586. We have revised the secondary to primary mass ratio to 0.987. The spectral types of the primary and secondary are K4 III and K1: III, respectively, and the components have…

Sequential clustering of star formations in IC 1396

Li, Jin-Zeng; Huang, Ya-Fang

We present a comprehensive study of the H II region IC 1396 and its star forming activity, in which multi-wavelength data ranging from the optical to the near- and far-infrared were employed. The surface density distribution of all the 2MASS sources with a certain detection toward IC 1396 indicates the existence of a compact cluster spatially cons…

Hot Gas Halos in Early-Type Galaxies and Environments

Kim, Eunbin; Kim, Sungsoo S.; Choi, Yun-Young

The ``Sausage'' and ``Toothbrush'' clusters of galaxies and the prospects of LOFAR observations of clusters of galaxies

Brunetti, G.; Tasse, C.; Cassano, R. +27 more

LOFAR, the Low Frequency Radio Array, is a new pan-European radio telescope that is almost fully operational. One of its main drivers is to make deep images of the low frequency radio sky. To be able to do this a number of challenges need to be addressed. These include the high data rates, removal of radio frequency interference, calibration of th…

Quasi-adiabatic dynamics of ions in a bifurcated current sheet

Malova, H. V.; Zelenyi, L. M.; Kartsev, Yu. I. +1 more

The study is devoted to ion dynamics in bifurcated current sheets with a two-peak current-density distribution observed in the Earth's magnetotail and solar wind. The ion motion is described by a Hamiltonian system with two degrees of freedom. The presence of a small parameter κ characterizing the ratio between the amplitudes of the normal and tan…

The influence of the ionosphere in subsurface Martian soil sounding experiments and a method of its correction

Smirnov, V. M.; Yushkova, O. V.

The problem of radar sounding of the Martian soil from an orbiting spacecraft is analyzed. The influence of the ionosphere on the results of remote sounding is revealed through the results of numerical modeling and actual subsurface soil sounding experiments carried out using the MARSIS radar sounder aboard the Mars-Express spacecraft. A method of…