A team of scientists led by members of the Instituto de Astrofisica de Canarias (IAC), in collaboration with the Universidad Nacional Autonoma de Mexico (UNAM), have detected and measured a complete "carpet" of expanding bubbles in the interstellar medium of the "Antennae", a pair of galaxies in interaction which will eventually merge. The work, published in Monthy Notices of the Royal Astronomical Society is based on observations with GHaFaS on the William Herschel Telescope (WHT). This instrument is capable of making a map of the velocities of a complete galaxy using the emission from the ionized hydrogen in its interstellar medium.

For the past twenty years observers have been trying to test the effects of the predicted dark matter halos on the bars in barred galaxies. The basic idea is that according to simulation models which include the halos, these should have acted as a gravitational brake and slowed down the rotation of the bars during the lifetimes of galaxy discs. This could be tested by measuring the corotation radius corresponding to the bar, which is the radius at which the angular pattern speed of the bar is equal to the angular speed of the stars in the disc. The problem has been the difficulty of measuring the corotation radius. However, a group at the Instituto de Astrof

A group of astronomers, led by researchers at the Instituto de Astrofisica de Canarias (IAC), has found the first known case of three supernova remnants one inside the other. Using a method developed within the group for detecting huge expanding bubbles of gas in interstellar space, they were observing the galaxy M33 in our Local Group of galaxies and found an example of a triple-bubble. The results help to understand the feedback phenomenon, a fundamental process controlling star formation and the dissemination of metals produced in massive stars.

Using Fabry-Perot optical interferometers, including GHaFaS on the William Herschel Telescope, and observing a sample of over a hundred nearby galaxies, astronomers have discovered that there are more density waves than predicted by theory, and that there are relations between them forming a complex pattern of resonances, which orchestrate the Music of the Galaxies.

From July 6th to July 12th a new private instrument for the WHT, GHaFaS, saw its first run.The acronym GHaFaS stands for Galaxy Halpha Fabry-Perot System, and gives an idea of the nature and the prime use of the instrument. It is a new generation FP interferometer, whose chief and powerful advantage over traditional systems which have been used on telescopes is the high sensitivity photon counting detector