A Pan-STARRS1 View of the Bifurcated Sagittarius Stream

TL;DR

This paper utilizes Pan-STARRS1 data to provide an extensive panoramic view of the Sagittarius tidal stream in the southern Galactic hemisphere, revealing its bifurcation and comparing observations with existing models.

Contribution

It offers the first detailed panoramic mapping of the southern Sagittarius stream, including the bifurcation, and measures distances to its arms, confirming and extending previous models.

Findings

Southern stream visible over 60 degrees, nearly double SDSS coverage.

Faint bifurcated arm is visible over at least 30 degrees.

Distances to stream arms match existing N-body models, with the faint arm closer by ~5 kpc.

Abstract

We use data from the Pan-STARRS1 survey to present a panoramic view of the Sagittarius tidal stream in the southern Galactic hemisphere. As a result of the extensive sky coverage of Pan-STARRS1, the southern stream is visible along more than 60 degrees of its orbit, nearly double the length seen by the SDSS. The recently discovered southern bifurcation of the stream is also apparent, with the fainter branch of the stream visible over at least 30 degrees. Using a combination of fitting both the main sequence turn-off and the red clump, we measure the distance to both arms of the stream in the south. We find that the distances to the bright arm of the stream agree very well with the N-body models of Law & Majewski (2010). We also find that the faint arm lies ~5 kpc closer to the Sun than the bright arm, similar to the behavior seen in the northern hemisphere.