Sagittarius stream 3-d kinematics from SDSS Stripe 82

TL;DR

This paper uses multi-epoch SDSS Stripe 82 data to measure precise 3D kinematics of the Sagittarius stellar stream, enhancing understanding of its motion and structure.

Contribution

It provides the first detailed proper motion measurements of the Sgr stream in Stripe 82, distinguishing between its two main components with high precision.

Findings

Proper motions measured to ~0.1 mas/yr accuracy.

Separation of the two Sgr streams in proper motion.

Enhanced constraints on the 3D kinematics of the Sgr stream.

Abstract

Using multi-epoch observations of the Stripe 82 region done by Sloan Digital Sky Survey, we measure precise statistical proper motions of the stars in the Sagittarius stellar stream. The multi-band photometry and SDSS radial velocities allow us to efficiently select Sgr members and thus enhance the proper motion precision to ~0.1 mas/yr. We measure separately the proper motion of a photometrically selected sample of the main sequence turn-off stars, as well as of a spectroscopically selected Sgr giants. The data allow us to determine the proper motion separately for the two Sgr streams in the South found in Koposov et al.(2012). Together with the precise velocities from SDSS, our proper motion provide exquisite constraints of the 3-D motions of the stars in the Sgr streams.