Enter the Dragonfly

There’s some fantastic news this morning about new results with the Dragonfly Telephoto Array, a collection of tightly clustered low-reflectivity telephoto lenses that have been deployed on a remote mountaintop in southern New Mexico. The Array is the brainchild of Toronto professor Roberto Abraham and Yale professor Pieter van Dokkum, and they are cleverly exploiting the high quality optics and anti-reflective coatings of commercially available, high-end telephoto lenses to image the sky. The advantage of these kinds of lenses is that they are very sensitive to the light from large-scale, diffuse structures, ones that are not so easy to see with conventional telescopes. Indeed, this cool project has opened up a new window into the universe and is revealing things never before seen, especially in the outer reaches of known galaxies. For example, new Astronomy Technology postdoctoral fellow Deborah Lokhorst developed a novel filter system for Dragonfly for her Toronto dissertation where a narrow-band filter was placed in front of the apertures of three lenses, and could be carefully angled to allow slightly different wavelengths (and source velocities) to be imaged. In the trial observations that focused on red emission from hydrogen atoms, Deborah and company discovered a previously unseen gigantic cloud of ionized gas outside the galaxy M82, one that is larger than the Moon in the sky!

The galaxies M81 and M82 are about 12 million lightyears from Earth, and this mysterious cloud has a projected distance of about 130,000 lightyears from the centre of M82 and is about 180,000 lightyears long and 30,000 lightyears wide. You can see this cloud, the H-alpha shell, above M82 n the below image labeled as “H-alpha shell.” The gas of this cloud may have been gravitationally yoinked out of M82 during a close passage by its neighbour galaxy M81 or perhaps M82’s relatively intense star formation activity resulted in “superwind” that blew the gas out of the galaxy instead. Meanwhile, Deborah’s Yale-based colleague Imad Pasha used the same filter system to detect what appears to be a very diffuse, small galaxy (about 2,000 lightyears wide) forming in the outskirts of M82, here in a known streamer of gas pulled out from the larger galaxy. If you look carefully at the image below, you can see this small galaxy as a small compact red blob on the left side of M82, labeld as “Nascent TDG,” where TDG stands for Tidally Disrupted Galaxy. Deborah and her Dragonfly colleagues are now working to expand the number of telephoto lenses equipped with these narrow-band filters. Indeed, the Dragonfly project itself recently obtained funding from the Canada Foundation for Innovation to expand from 48 lenses to 168 lenses, making it even more sensitive in future. Here are links to Deborah’s paper and Imad’s paper, and the link to the Yale press release about these results, for those who’d like to read more. Congratulations, Deborah!

Credit: Dragonfly team (Toronto/Yale)