We present hydrodynamical simulations of multiple shell planetary nebulae (MSPN) formation using evolutionary models of 1, 1.5, 2, 2.5, 3.5 and 5 M_odot. Stellar evolution from the AGB (Vassiliadis & Wood 1993) to the post-AGB phase (Vassiliadis & Wood 1994) was followed. Included in our simulations are the effect of stellar evolution and fast wind

In order to compare the use of the classical Fourier Transform and the Homomorphic Deconvolution (HD), ring diagram analysis using both techniques has been applied to a time series of a solar section to obtain the 3-dimensional power spectrum (kx - ky - ω). The series has a total span of 1536 minutes and the section covers about 15 times 15 degrees

I describe how the principles of lexicography have been applied in limited ways in astronomy and look at the revision work under way for the third edition of the Oxford English Dictionary, which, when completed, will contain the widest and most detailed coverage of the astronomical lexicon in the English language. Finally, I argue the need for a

Not Available

The circumnuclear regions of some barred galaxies show strong bursts of star formation organized into miniature spiral arms or rings. Recent work has shown the relation between such regions and the structure of the galaxies. This relation has important implications for our understanding not only of galaxy dynamics, but also of central activity. We

The power spectrum of ~630 days of full-disk solar velocity data, provided by the GOLF spectrophotometer aboard SOHO, has revealed the presence of mode-like structure well beyond the acoustic cut-off frequency for the solar atmosphere (nuac ~5.4 mHz). This kind of structure has already been observed in intermediate and high spatial resolution