The Hidden Past of M92: Detection and Characterization of a Newly Formed 17° Long Stellar Stream Using the Canada–France Imaging Survey

Abstract

We present an analysis of the structure, kinematics, and orbit of a newly found stellar stream emanating from the globular cluster M92 (NGC 6341). This stream was discovered in an improved matched-filter map of the outer Galaxy, based on a “color–color–magnitude” diagram, created using photometry from the Canada–France Imaging Survey and the Pan-STARRS 1 3 π survey. We find the stream to have a length of 17° (2.5 kpc at the distance of M92), a width dispersion of 0.°29(42 pc), and a stellar mass of [3.17 ± 0.89] × 10 4 M ⊙ (10% of the stellar mass of the current main body of M92). We examine the kinematics of main-sequence, red giant, and blue horizontal branch stars belonging to the stream and that have proper motion measurements from the second data release of Gaia. N -body simulations suggest that the stream was likely formed very recently (during the last ∼500 Myr) forcing us to question the orbital origin of this ancient, metal-poor globular cluster.