University of Michigan, Ann Arbor | 2019 Jan 09
Long ago in a galaxy far, far away, fewer galaxies were born than expected—and that could create new questions for galaxy physics, according to a new University of Michigan study.Color images of the two recently discovered satellite galaxies around M94. The images
were taken with Hyper Suprime-Cam on the Subaru telescope, located at nearly 14,000
ft above sea level on the summit of Mauna Kea in Hawaii. Credit: Smercina et al 2018
The study examined the satellite galaxies of Messier 94, or M94, a galaxy similar in size to our Milky Way. Researchers have long known the Milky Way has about 10 smaller, satellite galaxies surrounding it, each with at least a million stars, and up to more than a billion, such as the Magellanic Clouds.
Now, with the powerful Subaru telescope, astronomers can peer at galaxies five or 10 times the distance from the Milky Way, such as M94. They then can use the physics of how satellite galaxies form around the Milky Way to predict how many satellite galaxies a similar-sized galaxy such as M94 may have.
When U-M astronomers examined M94, they expected to find a similar number of satellite galaxies. However, they detected just two galaxies near M94, with very few stars each. ...
A Lonely Giant: The Sparse Satellite Population of M94 Challenges Galaxy Formation ~ Adam Smercina et al