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Description: This is the nearby Sc spiral (in fact, perhaps the
textbook example of a luminous so-called luminosity class I spiral) NGC 5457
or Messier 101, in
Ursa Major. It has several extremely luminous star-forming (H II) regions in
the outer spiral arms, some sporting their own NGC numbers. It
dominates a small group of galaxies, with some of its neighbors such as NGC
5474 showing wear and tear attributed to the tidal effects of M101.
M101 itself is further noteworthy for its extensive and lopsided
distribution of neutral hydrogen gas, and for showing evidence of gas
falling into its
disk at high speeds.
Credit: Peter Bunclark (IoA) and Nik Szymanek.
Date: 1998.
Technical information:
Telescope: 2.5-m Isaac Newton Telescope.
Instruments: Wide-Field Camera.
Detectors: Mosaic of 4 EEVs.
Filters and exposure times: 3*2 minute exposures in Harris R, V and B.
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