The Whirlpool Galaxy (M51)
M51 is one of the most studied galaxy pairs in the sky, but familiarity doesn’t make it a straightforward target. Located about 23 million light-years away in Canes Venatici, the gravitational interaction between M51a and its companion M51b is ongoing and active, sculpting the spiral arms, driving star formation, and producing tidal streams that require serious integration time to pull out of the noise.
This image is a step forward from the DSC’s previous M51 project in 2023, with deeper data and improved processing techniques throughout.
What the data revealed
The most significant find in this dataset is what we’re calling the Hydrogen-Alpha Cliffs, faint emission nebulae on the right side of the galaxy produced by the tidal interaction between the two galaxies. With close to 400 hours of H-alpha data at 1,300-second sub-exposures, these structures are visible in a level of detail that rarely makes it into amateur images.
Beyond the cliffs, the image captures the tidal streams of stars, gas, and dust flowing between M51a and M51b, along with faint Integrated Flux Nebula threading through the wider field. A blue stellar arc to the north of M51, produced by galactic shocks, is also visible. The background is populated with distant galaxies throughout, which become more apparent at full resolution.
My role
I handled the data processing, integrating the H-alpha data with the broadband LRGB layers and working to preserve the natural colour and texture of the galaxy while keeping the faint structures legible. With 17 contributors across multiple telescope systems, the main challenge was bringing everything into a consistent result.
Credits
Tim Schaeffer (coordination), Carl Björk (stacking, nearly 3,000 files), Steeve Body (processing). Photographers: Fabian Neyer, Aki Jain, Ryan Wierckx, Paul Kent, Brian V., Antoine and Dalia Grelin, Nicolas Puig, Stephen Guberski, Mike Hamende, Julian Shapiro, John Dziuba, Mikhail Vasilev, Bogdan Borz, Adrien Keijzer.
Full image and additional projects at https://deepskycollective.com/gallery.
