Understand
We detect a tidal stream generated by the globular cluster NGC 3201 extending over ~140 degrees on the sky, using the Gaia DR2 data, with the maximum likelihood method we presented previously to study the M68 tidal stream.
- Most of the detected stream is the trailing one, which stretches in the southern Galactic hemisphere and passes within a close distance of 3.2 kpc from the Sun, therefore making the stream highly favorable for discovering relatively bright member stars, while the leading arm is further from us and behind a disk foreground that is harder to separate from.
- The cluster has just crossed the Galactic disk and is now in the northern Galactic hemisphere, moderately obscured by dust, and the part of the trailing tail closest to the cluster is highly obscured behind the plane.
- We obtain a best-fit model of the stream which is consistent with the measured proper motion, radial velocity and distance to NGC 3201, and show it to be the same as the previously detected Gj\"oll stream by Ibata et al.