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Caught on the hook

5 Jan 2021, 12:36 UTC
Caught on the hook
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A curving arm of the spiral galaxy NGC 2442 trails into extragalactic space in this glorious image from the Hubble Space Telescope.
The galaxy, which is about 50 million light years away in the Southern Hemisphere constellation of Volans, the Flying Fish, is also known as the Meathook Galaxy, thanks to the shape of its asymmetrical spiral arms, particularly its northern arm, which has been pulled out from the galaxy to form a distinctive ‘hook’ shape. We can get a sense of that in this image, with clear space between the inner part of the galaxy and the spiral arm, seemingly held rigid by a thick skeleton of dark dust. In hydrogen-alpha light, the northern spiral arm is also the most prominent, as it interacts with the extragalactic medium. There’s even a cloud of hydrogen gas, visible only at radio wavelengths, that has also been ripped from NGC 2442.
Image: ESA/Hubble and NASA/Stephen Smartt et al.
This all hints at the presence of an unseen companion galaxy that has had a close encounter with NGC 2442, the gravitational tidal forces between the two causing NGC 2442’s spiral structure to unravel. Models suggest that in a few hundred million years’ time, ...

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