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Variations in Oscillation Frequencies From Minimum to Maximum of Solar Activity
Jain, Kiran; Bhatnagar, A.
The temporal variation in intermediate-degree-mode frequencies is analysed using helioseismic data which cover the minimum to the maximum phase of the current solar cycle. To study the variation in detail, the measured frequency shifts of f and p modes are decomposed into two components, viz., oscillatory and non-oscillatory. The f-mode frequencie…
Photospheric flows measured with TRACE II. Network formation
Roudier, T.; Krijger, J. M.
We analyse a 7 d (167 h) sequence of TRACE white-light images with 1 arcsec angular resolution taken at 1 min cadence. The TRACE resolution and the fast cadence allows us to produce maps of the horizontal flow fields with high angular (1 arcsec) and temporal resolution (5 min). The field of view of 128arcsec x 128arcsec (~93 Mm x 93 Mm) covers app…
The corona of V390 Aurigae (HD 33798)
Gondoin, P.
V390 Aurigae (HD 33798) is a rapidly rotating, lithium rich, late-type giant whose distinctive characteristics include a high X-ray luminosity observed by the XMM-Newton space observatory. Series of lines of highly ionized Fe and several Lyman lines of hydrogen-like ions and triplet lines of helium-like ions are visible in the reflection grating s…
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…