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Stellar ‘generation gap’ revealed in nearby galaxy

Baby stars rub elbows with their wizened elders in a newly released image that melds ultraviolet and infrared data from two space observatories
A composite image of the Andromeda galaxy reveals cool, dusty areas with embryonic stars (red) and older stars (green)
A composite image of the Andromeda galaxy reveals cool, dusty areas with embryonic stars (red) and older stars (green)
(Image: NASA/JPL-Caltech)

Stellar newborns and wizened old stars rub elbows in a newly released image of our neighbouring galaxy, Andromeda.

The picture combines images taken in ultraviolet light from NASA鈥檚 Galaxy Evolution Explorer (GALEX) and in infrared light from its Spitzer Space Telescope.

GALEX鈥檚 ultraviolet measurements reveal relatively old stars as green dots, with a particularly dense retirement community of these stars emitting the yellow glow at the galaxy鈥檚 centre.

Meanwhile, Spitzer detected cool, dusty stellar nurseries, which are denoted in red. Young, hot, massive stars appear blue.

In the pinkish purple areas in Andromeda鈥檚 spiral arms, hot, high-mass stars live together with cooler stars shielded by dust.