“But regardless of whether a galaxy is very big or very small, if you could sit on the extreme edge of its disk as it spins, it would take you about a billion years to go all the way round.”
Prof Meurer explained how all galaxies of the same size have the same average interior density.
“Discovering such regularity in galaxies really helps us to better understand the mechanics that make them tick – you won’t find a dense galaxy rotating quickly, while another with the same size but lower density is rotating more slowly,” he added.
Prof Meurer’s team also discovered that older stars were living out their last years on the very edge of the galaxies they examined.
“Based on existing models, we expected to find a thin population of young stars at the very edge of the galactic disks we studied,” he said.
“But instead of finding just gas and newly formed stars at the edges of their disks, we also found a significant population of older stars along with the thin smattering of young stars and interstellar gas.”
“This is an important result because knowing where a galaxy ends means we astronomers can limit our observations and not waste time, effort and computer processing power on studying data from beyond that point,” he said. Sky More….
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