Canada France Hawaii Telescope | 2020 Oct 14
A team of astronomers using the Canada-France-Hawaii Telescope discovered a new stellar stream emanating from the M92 globular cluster. This new stream suggests that M92 is actively being disrupted by tidal forces caused by our Milky Way Galaxy. This discovery utilized high quality data obtained as part of the Canada-France-Imaging-Survey (CFIS) using MegaCam at CFHT and from the Pan-STARRS 1 (PS1) survey on Haleakalā, Maui. The discovery of a stellar stream around M92 raises the question of the cluster's origin and could be used in the future to probe the innermost region of our Galaxy. The team estimates that stellar stream has a mass equivalent to ~10% of the mass of the entire M92 cluster.
Stellar streams are long thin streams of stars formed as globular clusters or dwarf galaxies are ripped apart by the immense gravity of the Milky Way. The structures formed by these tidal forces are stable over many billions of years. Their longevity allows astronomers to use their presence to better understand the formation of galaxies like the Milky Way as a guide to determine the role of galactic cannibalism in galaxy formation. Additionally, stellar streams are excellent tools to probe the gravitational potential of our Galaxy and study the distribution of dark matter around it. ...
The team identified the 17° long stellar stream from the M92 globular cluster stream using an improved matched-filter method. This method aims to highlight a specific known signal in a noisy dataset and proves to be an extremely efficient tool to detect stellar streams around the Milky Way Galaxy.
Despite previous observations in this region, the newly discovered M92 stellar stream was hidden by the high number of foreground stars from the Milky Way disk. It was discovered because of the combination of high quality images from both CFIS and Pan-STARRS. The team also used proper motions obtained by the European space mission Gaia to confirm the existence of the stream. ...
The Hidden Past of M92: Detection and Characterization of a Newly Formed
17° Long Stellar Stream Using the Canada–France Imaging Survey ~ Guillaume F. Thomas et al