A Tale of a Tail: A Tidally-Disrupting Ultra-Diffuse Galaxy in the M81 Group
Rokas \v{Z}emaitis, Annette M. N. Ferguson, Sakurako Okamoto,, Jean-Charles Cuillandre, Connor J. Stone, Nobuo Arimoto, Mike J. Irwin

TL;DR
This paper reports the discovery of a tidal tail associated with the ultra-diffuse galaxy F8D1 in the M81 Group, revealing evidence of recent disruption likely caused by a close passage to M81, and highlighting the importance of deep imaging in understanding UDG evolution.
Contribution
The study provides the first detailed observation of a tidal tail in an ultra-diffuse galaxy, suggesting tidal disruption as a formation mechanism for some UDGs.
Findings
Discovered a giant tidal tail associated with F8D1.
Estimated that 30-36% of F8D1's luminosity is in the tail.
F8D1 likely experienced recent disruption due to a close passage to M81.
Abstract
We present the discovery of a giant tidal tail of stars associated with F8D1, the closest known example of an ultra-diffuse galaxy (UDG). F8D1 sits in a region of the sky heavily contaminated by Galactic cirrus and has been poorly studied since its discovery two decades ago. The tidal feature was revealed in a deep map of resolved red giant branch stars constructed using data from our Subaru Hyper Suprime-Cam survey of the M81 Group. It has an average surface brightness of mag arcsec and can be traced for over a degree on the sky (60 kpc at the distance of F8D1) with our current imagery. We revisit the main body properties of F8D1 using deep multiband imagery acquired with MegaCam on CFHT and measure effective radii of kpc, central surface brightnesses of mag and a stellar mass of . Assuming a symmetric feature on…
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Taxonomy
TopicsGalaxies: Formation, Evolution, Phenomena · Astronomy and Astrophysical Research · Stellar, planetary, and galactic studies
