The Crab Nebula is one of the most studied objects on the sky. Yet, many of its properties still confound scientists. For example, it seems that the total mass and energy of the supernova remnant are lower than expected. Anestis Tziamtzis, graduate student at the Department of Astronomy, and his colleagues have looked for a possible halo of ejected material from the supernova explosion that could now surround the visible nebula. If such a halo exists, it could solve these problems.

The group has used the 2.2 meter MPG/ESO telescope in Chile and the 2.56 meter Nordic Optical Telescope (NOT) on La Palma to produce deep images in the H-alpha line of hydrogen to try to detect the shell. Detailed image analysis has made it possible to obtain one of the best limits on the mass of the shell. The mass limit that they establish allows for that the Crab nebula was formed in a regular supernova explosion. The method of the analysis made by the group is also useful for studies of matter around other large objects with faint haloes, such as some types of galaxies.

Original article:
Observational and theoretical constraints for an H-alpha-halo around the Crab Nebula Contact:

Anestis Tziamtzis,
Peter Lundqvist, Tel: 08-5537 8518,