Cartography of Triangulum-Andromeda using SDSS stars

TL;DR

This paper maps the Triangulum-Andromeda substructure in the Galactic halo using SDSS data, revealing multiple overdensities and proposing possible origins, including tidal debris or disk oscillations.

Contribution

It provides a detailed mapping of TriAnd using SDSS data and identifies new potential overdensities, advancing understanding of Galactic halo substructures.

Findings

Multiple overdensities associated with TriAnd identified

Potential new stellar overdensity discovered

Discussion of alternative origin hypothesis for TriAnd

Abstract

The outer Galactic halo is home to a number of substructures which still have an uncertain origin, but most likely are remnants of former interactions between the Galaxy and its former satellites. Triangulum-Andromeda (TriAnd) is one of these halo substructures, found as an overdensity of 2MASS M giants. We analyzed the region of Triangulum-Andromeda using photometric data from the Ninth Data Release of Sloan Digital Sky Survey (SDSS DR9). By comparing the observations with simulations from the TRILEGAL Galactic model, we were able to identify and map several scattered overdensities of main sequence stars that seem to be associated with TriAnd over a large area covering $\sim 500$ deg$^2$. One of these excesses may represent a new stellar overdensity. We also briefly discuss an alternative hypothesis, according to which TriAnd is one of the troughs of oscillation rings in the Galactic disk.