TY - JOUR
T1 - Uncovering fossils of the distant Milky Way with UNIONS
T2 - NGC 5466 and its stellar stream
AU - Jensen, Jaclyn
AU - Thomas, Guillaume
AU - McConnachie, Alan W.
AU - Starkenburg, Else
AU - Malhan, Khyati
AU - Navarro, Julio
AU - Martin, Nicolas
AU - Famaey, Benoit
AU - Ibata, Rodrigo
AU - Chapman, Scott
AU - Cuillandre, Jean Charles
AU - Gwyn, Stephen
N1 - Publisher Copyright:
© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
PY - 2021/10/1
Y1 - 2021/10/1
N2 - We examine the spatial clustering of blue horizontal branch (BHB) stars from the u-band of the Canada-France Imaging Survey (CFIS, a component of the Ultraviolet Near-Infrared Optical Northern Survey, or UNIONS). All major groupings of stars are associated with previously known satellites, and among these is NGC 5466, a distant (16 kpc) globular cluster. NGC 5466 reportedly possesses a long stellar stream, although no individual members of the stream have previously been identified. Using both BHBs and more numerous red giant branch stars cross-matched to Gaia Data Release 2, we identify extended tidal tails from NGC 5466 that are both spatially and kinematically coherent. Interestingly, we find that this stream does not follow the same path as the previous detection at large distances from the cluster. We trace the stream across 31° of sky and show that it exhibits a very strong distance gradient in the range 10 < Rhelio < 30 kpc. We compare our observations to simple dynamical models of the stream and find that they are able to broadly reproduce the overall path and kinematics. The fact that NGC 5466 is so distant, traces a wide range of Galactic distances, has an identified progenitor, and appears to have recently had an interaction with the Galaxy's disc makes it a unique test-case for dynamical modelling of the Milky Way.
AB - We examine the spatial clustering of blue horizontal branch (BHB) stars from the u-band of the Canada-France Imaging Survey (CFIS, a component of the Ultraviolet Near-Infrared Optical Northern Survey, or UNIONS). All major groupings of stars are associated with previously known satellites, and among these is NGC 5466, a distant (16 kpc) globular cluster. NGC 5466 reportedly possesses a long stellar stream, although no individual members of the stream have previously been identified. Using both BHBs and more numerous red giant branch stars cross-matched to Gaia Data Release 2, we identify extended tidal tails from NGC 5466 that are both spatially and kinematically coherent. Interestingly, we find that this stream does not follow the same path as the previous detection at large distances from the cluster. We trace the stream across 31° of sky and show that it exhibits a very strong distance gradient in the range 10 < Rhelio < 30 kpc. We compare our observations to simple dynamical models of the stream and find that they are able to broadly reproduce the overall path and kinematics. The fact that NGC 5466 is so distant, traces a wide range of Galactic distances, has an identified progenitor, and appears to have recently had an interaction with the Galaxy's disc makes it a unique test-case for dynamical modelling of the Milky Way.
KW - Galaxy: halo
KW - Galaxy: kinematics and dynamics
KW - Galaxy: structure
KW - globular clusters: individual: NGC 5466
UR - http://www.scopus.com/inward/record.url?scp=85116574140&partnerID=8YFLogxK
U2 - 10.1093/mnras/stab2325
DO - 10.1093/mnras/stab2325
M3 - Article
AN - SCOPUS:85116574140
SN - 0035-8711
VL - 507
SP - 1923
EP - 1936
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 2
ER -