A Cold Milky Way Stellar Stream in the Direction of Triangulum

TL;DR

This paper reports the discovery of a new cold stellar stream in the Milky Way, identified through SDSS data, which provides insights into the galaxy's halo structure and gravitational potential.

Contribution

The paper introduces the Triangulum stream, a newly identified stellar tidal stream in the Milky Way halo, detected using a matched-filter technique on SDSS data.

Findings

The stream is approximately 26 kpc away from the Sun.

It has a width consistent with a globular cluster remnant.

The stellar population is old and metal-poor (~12 Gyr, [Fe/H] ~ -1.0).

Abstract

We present evidence for a new Milky Way stellar tidal stream in the direction of the Andromeda and Triangulum (M31 and M33) galaxies. Using a matched-filter technique, we search the Sloan Digital Sky Survey Data Release 8 by creating stellar density maps which probe the Milky Way halo at distances between 8 and 40 kpc. A visual search of these maps recovers all of the major known stellar streams, as well as a new stream in the direction of M31/M33 which we name the Triangulum stream. The stream spans 0.2 deg by 12 deg on the sky, or 75 pc by 5.5 kpc in physical units with a best fitting distance of 26+/-4 kpc. The width of the stream is consistent with being the tidal remnant of a globular cluster. A color magnitude diagram of the stream region shows an overdensity which, if identified as a main sequence turn-off, corresponds to an old (~12 Gyr) and metal-poor ([Fe/H] \sim -1.0 dex) stellar population. Future kinematic studies of this and similar cold streams will provide tight constraints on the shape of the Galactic gravitational potential.