M51 (also known as Whirlpool Galaxy) are two interacting galaxies in constellation Canes Venatici. The larger one (M51A or NGC 5194) is a spiral galaxy. Its smaller companion (M51B or NGC 5195) is a dwarf galaxy that is highly distorted from the interaction with M51A. The galaxy pair lies at a distance about 25 million light years. The diameter of the visible disk of larger galaxy is about 90,000 light years. The smaller dwarf galaxy is about half as large. M51A is the brightest member of the M51 group.
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By toggling between the images (click on the button) it can be seen that the HII regions (reddish) correlate with bluish regions. That's because the HII gas clouds typically contain many young (blue) stars which are also responsible for the ionization. Furthermore the HII regions also emit [OIII] and H-beta light
which is collected by the blue filter.
It seems that M51A contains many young (bluish stars) while M51B and its tidal streams mainly consists in older (brownish grey) stars (better visible in the version without H-alpha).
Furthermore it can be seen that the dust band of the upper arm of M51A obfuscates M51B, i.e. obviously M51B lies behind M51A.
FOV: | 0.44° × 0.44° (full view) | ||||||||
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Date: | 2020-2022 | ||||||||
Location: | Pulsnitz, Germany | ||||||||
Instrument: | 400mm Newton at f=1520mm | ||||||||
Camera Sensor: | Panasonic MN34230 | ||||||||
Orientation: | North is up (exactly) | ||||||||
Scale: | 0.8 arcsec/pixel | ||||||||
Total exposure times: |
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Image processing steps where:
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