7 Dwarf Galaxies Found With New Type of Telescope


Seven brand new dwarf galaxies were found the other day using a Dragonfly Telephoto Array type telescope. This proved quite exciting for Yale astronomer chair Pieter van Dokkum. Along with University of Toronto astronomer Roberto Abraham, they used the eight telephoto-lensed device to hunt down the smaller galaxies which appear to be arranged around the M101 galaxy in the photo above.

This new type of telescope is used to suppress internally scattered light, making it more able to view very diffuse, low surface brightness, like you would find in the dwarf galaxies because their star gives off less light, so the new telescope would make such galaxies more easy to see. Dwarf galaxies are usually harder to spot using conventional telescopes, which are better suited to seeing brighter objects.

“We got exciting result in our first images,” said Allison Merrit, a Yale graduate student and lead author of a paper about the dwarf galaxies discovery in the Astrophysical Journal Letters.

The telescope itself was built in 2012, and designed after similar equipment used at sporting events, they just decided to aim upwards. They dubbed it the “dragonfly” because the lenses resemble the compound eye of an insect.

The Yale students intend to search for debris from long-ago galaxy collisions and other types of objects which don’t give off as much light, including the seven newfound galaxies encircling the M101 spiral galaxy. (Here is an article that explains spiral galaxies a bit better.)

Some of the key questions they’d like to answer during further study include whether or not the galaxies just happen to be near M101, or if perhaps they’re not all as close as they seem and just look as though they are.

The exciting part of the discovery is, they got the results on the first try, and none of the galaxies had ever been discovered before because of the new nature of the telescope they were using. It opens up the possibility that there are many more such galaxies littering the sky that remain to be found.

“It’s a new domain. We’re exploring a region of parameter space that had not been explored before,” van Dokkum said. “I’m confident that some of them will turn out to be a new class of objects. I’d be surprised if all seven of them are satellites of M101.”

In light of the discovery that dwarf galaxies may have played a large role in the formation of our universe, it’s quite exciting to have a means to look at them more closely almost as soon as that role was discovered. These small galaxies are over 1000 times less massive than the Milky way, and contributed nearly a third of the UV light present during re-ionization (an epoch which occurred roughly a billion years after the big bang).

It was UV light which began to split neutral hydrogen into electrons and protons, and the process took around 800 million years. When finished, it marked the last major change to gas in the universe, which remains ionized even today, over 12 billion years later, according to researchers at the Georgia Institute of Technology. They say that back then, the smaller galaxies were so plentiful that most of the light came from them.