Properties of the Lower Segment of M31's North West Stream
Abstract
We present a kinematic and spectroscopic analysis of 40 red giant branch stars, in 9 fields, exquisitely delineating the lower segment of the North West Stream (NW-K2), which extends for 80 kpc from the centre of the Andromeda galaxy. We measure the stream's systemic velocity as -439.3 km/s with a velocity dispersion = 16.4 km/s that is in keeping with its progenitor being a dwarf galaxy. We find no detectable velocity gradient along the stream. We determine 1.30.1 <[Fe/H]> 1.20.8 but find no metallicity gradient along the stream. We are able to plausibly associate NW-K2 with the globular clusters PandAS-04, PandAS-09, PAndAS-10, PAndAS-11, PandAS-12 but not with PandAS-13 or PandAS-15 which we find to be superimposed on the stream but not kinematically associated with it.
Cite
@article{arxiv.2409.07410,
title = {Properties of the Lower Segment of M31's North West Stream},
author = {Janet Preston and Denis Erkal and Michelle L. M. Collins and Rodrigo Ibata and R. Michael Rich},
journal= {arXiv preprint arXiv:2409.07410},
year = {2025}
}
Comments
14 pages, 8 figures