Kinematic Discovery of a Stellar Stream located in Pisces

TL;DR

This paper reports the discovery and characterization of the Pisces Stellar Stream, a narrow, metal-poor, kinematically cold tidal stream in the Milky Way halo, identified through SDSS data and confirmed with photometric and spectroscopic analysis.

Contribution

The paper presents the first kinematic detection and detailed properties of the Pisces Stellar Stream, linking it to the Triangulum stream and clarifying its distinction from other substructures.

Findings

PSS is a narrow, cold tidal stream with 8 km/s velocity dispersion.

Located at approximately 35 kpc from the Sun.

Metallicity of [Fe/H] = -2.2 with 0.3 dex dispersion.

Abstract

We report the kinematic discovery of the Pisces Stellar Stream (PSS), at Galactic longitude of roughly l=135 degrees and longitude between -39 < b < -36 deg. We originally identified this halo substructure from velocities of red giant branch stars in Sloan Digital Sky Survey (SDSS) Data Release 8, and confirmed its presence in turnoff stars from SDSS photometric data. The PSS is a narrow, kinematically cold tidal stream, with a velocity dispersion of 8 km/s. Its metallicity is [Fe/H]=-2.2, with ~0.3 dex dispersion. The color-magnitude signature of the stream turnoff, combined with our measured metallicity, places the PSS at a distance of 35+/-3 kpc. The Pisces Stellar Stream is the same as the previously announced "Triangulum stream" and part of the proposed "stream a". We rule out an association of the PSS with other previously known Milky Way substructures in the same region of the sky.