In this Letter, we introduce a technique for finding resonance radii in a disk galaxy. We use a two-dimensional velocity field in Hα emission obtained with Fabry-Perot interferometry, derive the classical rotation curve, and subtract it off, leaving a residual velocity map. As the streaming motions should reverse sign at corotation, we detect these

The theory of magnetohydrodynamic (MHD) waves in solar coronal slabs in a zero- β configuration and for parallel propagation of waves does not allow the existence of surface waves. When oblique propagation of perturbations is considered, both surface and body waves are able to propagate. When the perpendicular wavenumber is larger than a certain

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We have digitally co-added APM scans of 13 Kodak TechPan films of the SE region of the Virgo cluster of galaxies. The ~ 6.2degr x 6.2degr field of the R-band films combined with the resolution of ~ 2 arcsec pixel(-1) results in data file sizes of about 222 MBytes. The 13 scanned films have been aligned, co-added, corrected for vignetting effects

Context. The design of modern instruments does not only imply thorough studies of instrumental effects but also a good understanding of the scientific analysis planned for the data. Aims: We investigate the reliability of Milne-Eddington (ME) inversions of high-resolution magnetograph measurements such as those to be obtained with the Imaging

We present an automated morphological classification in 4 types (E, S0, Sab, Scd) of ˜ 700,000 galaxies from the SDSS DR7 spectroscopic sample based on support vector machines. The main new property of the classification is that we associate a probability to each galaxy of being in the four morphological classes instead of assigning a single class