A New Faint Milky Way Satellite Discovered in the Pan-STARRS1 3 pi Survey

TL;DR

This paper reports the discovery of a faint new Milky Way satellite, Laevens 2/Triangulum II, identified in Pan-STARRS1 data, with follow-up observations confirming its properties and potential connection to local stellar structures.

Contribution

It introduces a newly discovered faint satellite, expanding the known population and providing detailed photometric measurements and context for its significance.

Findings

Discovery of Laevens 2/Triangulum II in Pan-STARRS1 data

Satellite's properties similar to other faint Milky Way satellites

Potential link to Triangulum-Andromeda stellar structures

Abstract

We present the discovery of a faint Milky Way satellite, Laevens 2/Triangulum II, found in the Panoramic Survey Telescope And Rapid Response System (Pan-STARRS 1) 3 pi imaging data and confirmed with follow-up wide-field photometry from the Large Binocular Cameras. The stellar system, with an absolute magnitude of M_V=-1.8 +/-0.5, a heliocentric distance of 30 +2/-2 kpc, and a half-mass radius of 34 +9/-8 pc, shows remarkable similarity to faint, nearby, small satellites such as Willman 1, Segue 1, Segue 2, and Bo\"otes II. The discovery of Laevens 2/Triangulum II further populates the region of parameter space for which the boundary between dwarf galaxies and globular clusters becomes tenuous. Follow-up spectroscopy will ultimately determine the nature of this new satellite, whose spatial location hints at a possible connection with the complex Triangulum-Andromeda stellar structures.