Search Publications
The Opacity of Nearby Galaxies from Counts of Background Galaxies. II. Limits of the Synthetic Field Method
Loinard, Laurent; Allen, Ronald J.; Muller, Sébastien +1 more
Recently, we have developed and calibrated the Synthetic Field Method to derive the total extinction through disk galaxies. The method is based on the number counts and colors of distant background field galaxies that can be seen through the foreground object; it is the only method capable of determining extinction without a priori assumptions abo…
An XMM-Newton observation of the flare star AU MIC
Mewe, R.; Audard, M.; Güdel, M. +1 more
Preliminary results from an XMM- Newton observation of the active flare star AU Mic are presented. During the observation six flares were observed, along with numerous smaller-scale events. Coronal densities have been obtained using the density-sensitive He-like line triplet of O VII, for both the full observation and the final four flares. High b…
CDS/SoHO multi-line observation of a solar active region: Detection of a hot stable loop and of a cool dynamic loop
Peres, G.; Reale, F.; Di Giorgio, S.
We analyze a space-, time- and spectral-resolved SoHO/CDS observation of the evolution of an active region over a time lapse of approximately three hours in various spectral lines emitted in the interval of temperature 1.3 x 104 < T < 2.5 x 106 K. We identify and characterize two structures of interest: a longer coronal…
First results from TOO observations of the Aql X-1 field with INTEGRAL
Lutovinov, A.; Molkov, S.; Grebenev, S.
We present results of observations of the Aql X-1 field performed in March-April 2003 with the INTEGRAL observatory. This TOO (Target Of Opportunity) INTEGRAL observations was initiated upon receiving an indication from the ASM/RXTE that the source started an outburst. Thirteen X-ray sources were detected by the INTEGRAL imagers, JEM-X and IBIS, d…
Preferential Heating of Particles by H-Cyclotron Waves Generated by a Global Magnetohydrodynamic Mode in Solar Coronal Holes
Zhang, T. X.
Preferential heating of particles by H-cyclotron waves is investigated to explain the recent measurements of anisotropic heating of ions in solar coronal holes. First, the dispersion relation of H-cyclotron waves generated by a global MHD mode in the solar coronal hole is numerically studied. Then, heating of H, O+5, and Mg+9…
Coronal Oscillations above Sunspots?
Doyle, J. G.; Dzifćáková, E.; Madjarska, M. S.
Observational data clearly indicate the presence of 3-min oscillations in sunspots in spectral lines covering a vast temperature range from the low chromosphere to those lines normally associated with coronal temperatures. We show that after folding in the sunspot plume emission measure distribution, the contribution functions for lines normally f…
TRIFFID observations of the cores of the three globular clusters M15, M92 and NGC 6712
Shearer, A.; Tuairisg, S. Ó.; Butler, R. F. +3 more
We present the results of TRIFFID simultaneous V- and B-band observations of the cores of the globular clusters M15, M92 and NGC 6712. A variability search of their dense centres was made feasible through performing post-exposure image sharpening on the images, increasing the image resolution by a factor of ~2. The ISIS implementation of the image…
Dynamical evolution of the inner heliosphere approaching solar activity maximum: interpreting Ulysses observations using a global MHD model
Riley, P.; Linker, J. A.; Mikic, Z.
In this study we describe a series of MHD simulations covering the time period from 12 January 1999 to 19 September 2001 (Carrington Rotation 1945 to 1980). This interval coincided with: (1) the Sun's approach toward solar maximum; and (2) Ulysses' second descent to the southern polar regions, rapid latitude scan, and arrival into the northern pol…
Launch of solar coronal mass ejections and submillimeter pulse bursts
Rovira, M.; Levato, H.; Kaufmann, Pierre +4 more
The rapid solar spikes (100-500 ms) recently discovered at submillimeter waves bring new possibilities to investigate energetic processes near the solar surface that might have an important role in the launch and propelling of ionized mass away from the Sun. We present a study on the association between the launch time of coronal mass ejections (C…
Neutron-induced nuclear reactions and degradation in germanium detectors
Cordier, B.; Jean, P.; von Ballmoos, P. +15 more
We have measured cross sections of neutron-induced nuclear reactions leading to the delayed production of gamma -ray lines similar to the ones of astrophysical interest. Conclusions were drawn concerning the expected background in the 26Al 1809 keV line and the 7Be 478 keV line in SPI. The neutron-induced degradation of Ge de…