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hi I'm Stephanie Mila a research

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scientist working with NASA's Swift

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satellite at Goddard Space Flight Center

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in Greenbelt Maryland

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this is m31 the nearest large spiral

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galaxy to our own is about two and a

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half million light-years away

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and more than 220 thousand light-years

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across this is how we're used to seeing

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it in the visible light captured by

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ground-based telescopes but visible

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light never tells the whole story so

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between May and July 2008 Swift's

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ultraviolet optical telescope captured

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330 images of m31

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and three ultraviolet wavelengths the

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total exposure time 24 hours we combined

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these images into this mosaic it's the

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most detailed view of m31 in the

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ultraviolet to date the first thing you

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notice is the striking difference

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between the galaxy's central bulge and

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its spiral arms the bulges smoother and

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redder because it's full of older and

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cooler stars very few new stars form

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here because most of the materials

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needed to make them have been depleted

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in contrast and 31 spiral arms sparkly

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with dense glasses of hot young blue

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stars as in our own galaxy the disks

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conspire arms contain most of the gas

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and dust needed to produce new

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m31 x' clusters are especially plentiful

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in a giant ring around the galaxy it's

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about a hundred and fifty thousand light

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years across this Ring of Fire exists

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because of tile interactions with small

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satellite galaxies speaking of which

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this is m32

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one of many dwarf galaxies orbiting m31

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these galaxies are usually not very

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bright in the ultraviolet because they

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lack young stars but m32 score is so

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bright in the UV because it likely

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contains many blue and old stars the

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Swift mosaic reveals some twenty

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thousand UV sources it's important to

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study star formation processes in nearby

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galaxies so we can understand by

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breathing in distant galaxies this rich

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portray in three different ultraviolet

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wavelength allows us to study how m31