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Pinwheel spins with starbirth

It's hard to imagine a more glorious galaxy than NGC 3982, a face-on spiral that's swirling like a pinwheel 68 million light-years away in the northern constellation Ursa Major. It's a classic target for high-powered telescopes. This picture of the galaxy, released today by the Hubble Heritage team, was assembled from near-infrared and visible-light data captured by the Hubble Space Telescope's Wide Field Planetary Camera 2 between 2000 and 2009.

The colors have been adjusted to emphasize star-forming regions, rich in hydrogen gas (in pink), as well as hot young stars (in blue). Older stars are concentrated in the galaxy's white-yellow nucleus. This earlier rendering from Hubble shows the pinwheel in natural colors.

NGC 3982 is more than just a pretty face: Observations of a special kind of star inside the galaxy, known as a Cepheid variable, were used to fine-tune astronomers' best estimates of the Hubble constant -- a number that describes the universe's expansion rate. For what it's worth, the current value of the Hubble constant is judged to be somewhere around 73 kilometers per second per megaparsec. But don't worry: There won't be a quiz.

More about galaxies, cosmology and Hubble:


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