Arp 104 – Keenan’s system

Arp 104, also known as Keenan’s System, consists of the two spiral galaxies NGC 5216 (bottom) and NGC 5218 (top). The two are connected by a thin stream of gas, in which new stars are forming. The stream was created when the two galaxies passed by each other, their mutual gravity pulling the gas out. The newly formed hot, massive stars turn the stream blue. The stream is about 150,000 light years in length. Keenan’s System has been well-studied but you’ll find they have rarely been imaged. What has been captured even less so, are the tidal streams at the opposite sides of this stellar bridge. I was able to bring out this signal by applying excessive stretching and local noise reduction. Keenan’s System lies about 17.3 million light-years away. 


Arp 104 and NGC 5205 (bottom right corner)

Telescope: 16″ f3.75 Dream Scope
Camera: FLI ML16803
Mount: ASA DDM85
Exposure: 6.7 hours (50x300s L + 3x10x300s RGB)
Acquisition: February 2019 – Processing: January 2023
Location: Southern Alps, France


The inverted and highly stretched Luminance layer, showing the opposite tidal streams

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