low graphics version feedback help You are in: Sci/Tech Front Page World UK ... AudioVideo Monday, 4 June, 2001, 17:07 GMT 18:07 UK Spiral galaxy stays young at heart The offending bulge in M33 By BBC News Online science editor Dr David Whitehouse Observations of a neighbouring galaxy have thrown doubt on accepted theories about galactic structure and evolution. Astonomers observing the spiral galaxy have realised it has a much smaller central bulge of older stars than was expected. This finding makes us question the role of a bulge in spiral galaxy formation Andrew Stephens, Ohio State University Before now it was thought that the central bulge and disk of spiral galaxies were made up of stars of different ages. Astronomers thought that older stars inhabited the central bulge and younger stars were to be found in the disk. But some of the first images of galaxy M33 have shown that it has far fewer than expected older stars in its bulging heart. Cosmic corpulence Astronomers have long thought that a typical galactic disk is made up of stars of all ages. The central 'bulge' of a disk normally contains old stars from the time the galaxy formed. This is one reason why studying bulges can tell astronomers about how galaxies formed and evolved. According to current theory, spiral galaxies begin as a giant rotating mass of gas and dust, which starts out in a roughly spherical shape before the edges flatten into a disk. | |
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