December 23, 2011
Somewhere above you, light is arriving from places so distant their names feel like poetry.
Shell Galaxy NGC 7600
Birthday · December 23, 2011
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APOD published December 23, 2011. Credit: Rancho Del Sol Observatory. A publication-date match, not a photo taken on your date. Independent of NASA.
Similar in size to the Milky Way, elliptical galaxy NGC 7600 is about 160 million light-years distant. In this deep image, spanning about 1/2 degree on the sky toward the constellation Aquarius, NGC 7600 sports a remarkable outer halo of nested shells and broad circumgalactic structures. The tantalizing features can be explained by the accretion of dark matter and stars on a cosmic timescale. In fact, a movie generated by simulating galaxy formation using a cosmological model with cold dark matter for the halos of merging galaxies reproduces the appearance of NGC 7600 in amazing detail. The remarkable simulation movie is available here on Vimeo and here in other formats. It presents compelling evidence that detailed features of galaxy mergers observed with small, wide field telescopes on planet Earth, are natural consequences of galaxy formation and fundamental properties of dark matter.
Image credit: Rancho Del Sol Observatory