Open Group Seminar: Emma Dodd (University of Groningen)

11:00 am–12:00 pm ERC 517

Host: Alexander Ji

Emma Dodd (University of Groningen) "Low mass stellar streams populating the local stellar halo"

Galaxies stellar haloes are known to build up through the accretion of smaller systems, with stars from a single merger being deposited onto similar orbits. Since orbits can be characterised by their integrals of motion such as energy or angular momenta, we can thus search for the stellar debris of past accretion events by looking for over-densities in integrals of motion space (IOM). Using the Gaia DR3 data set we identify such merger debris in the Milky Way halo near the Sun including several new smaller substructures, that prove interesting both dynamically and chemically. These substructures have loosely bound orbits (with high energy) suggestive of an accreted origin.

For some of these substructures, the limited metallicity information hints at a small spread which is suggestive of a disrupted globular cluster origin (e.g. ED-2). Some of the other substructures overlap with regions where one might expect debris from Gaia Sausage Enceladus, although this depends on the exact configuration of the merger. I will present and discuss the information we have on these streams and how chemical abundances are needed for us to be able to characterise them further. What is the nature of these streams and how do they link with previously identified debris?

Event Type


Sep 4