The structure and dynamics of small vertical photospheric magnetic flux concentrations has been often treated in the framework of an approximation based upon a low-order truncation of the Taylor expansions of all quantities in the horizontal direction, together with the assumption of instantaneous total pressure balance at the boundary to the non

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Using the T-matrix theory, we have performed an analytical study of the collective fast normal modes of an arbitrary system of loops. The obtained results allow to assess the dynamical effects of the interaction of loops and the frequency shifts with respect to the individual loops in an arcade as a function of the number of tubes. Furthermore, the

As part of our ongoing Chandra/HST M31 transient program we report on a Chandra ACIS observation of M31 containing the new transient source reported by Pietsch et al. (2008, ATel #1674). A single 5ks observation was performed on 2008-09-01.32 UT. The Chandra coordinates for this source (subject to the boresight correction) are RA(J2000) 00:43:20

We report the discovery of 2 previously unseen X-ray sources detected in a 5ks Chandra/ACIS observation starting on 2008-09-01.32 UT as part of our ongoing Chandra/HST M31 transient program (see also ATel #1693 for more results from this observation). Due to the low count-rate, no spectral fitting was possible. The reported luminosities have been

Context: Analysis of bulges to redshifts of up to z ˜ 1 have provided ambiguous results as to whether bulges as a class are old structures akin to elliptical galaxies or younger products of the evolution of their host disks. Aims: We aim to define a sample of intermediate-z disk galaxies harbouring central bulges, and a complementary sample of disk