Holes in the Galactic Plane
Warm atomic hydrogen gas - the bright material in this picture - is a major constituent of our Galaxy, but it is peppered with holes. This image, made with the Australia Telescope Compact Array and the Parkes radio telescope, shows a structure called GSH 277+00+36 - a void in the atomic hydrogen more than 2,000 light-years across. It lies 21,000 light-years from the Sun on the edge of the Sagittarius-Carina spiral arm in the outer Milky Way.
The void was probably formed by winds and supernova explosions from
about 300 massive stars over the course of several million years. It
eventually grew so large that it broke out of the disk of the Galaxy,
forming a "chimney". GSH 277+00+36 is one of only a handful of chimneys
known in the Milky Way and the only one known to have exploded out of
both sides of the Galactic plane. It extends more than 3,000 light years
out of the disk of the Galaxy.
ATCA and Parkes image in HI by N. McClure-Griffiths and the Southern Galactic Plane Survey team.
Original: Bob Sault (13-Dec-2002)
Modified: Bob Sault (13-Dec-2002)