Four New Stellar Debris Streams in the Galactic Halo

TL;DR

This paper reports the discovery of four new stellar debris streams and a dwarf galaxy candidate in the Galactic halo, expanding our understanding of the Milky Way's accretion history and stellar halo structure.

Contribution

It introduces four newly identified stellar streams and a dwarf galaxy candidate, providing detailed descriptions and potential progenitor insights, which were previously unknown.

Findings

Four new stellar debris streams identified in SDSS data.

Streams range from 3 to 45 kpc in distance and 37 to 84 degrees in sky coverage.

A potential progenitor, Bootes III, may be dissolving into the Styx stream.

Abstract

We report on the detection of four new stellar debris streams and a new dwarf galaxy candidate in the Sloan Digital Sky Survey. Three of the streams, ranging between 3 and 15 kpc in distance and spanning between 37 and 84 degrees on the sky, are very narrow and are most probably tidal streams originating in extant or disrupted globular clusters. The fourth stream is much broader, roughly 45 kpc distant, at least 53 degrees in length, and is most likely the tidal debris from a dwarf galaxy. As the streams each span multiple constellations, we extend tradition and designate them the Acheron, Cocytos, Lethe, and Styx streams. At the same distance and apparently embedded in the Styx stream is a ~1 kpc-wide concentration of stars with a similar color-magnitude distribution which we designate Bootes III. Given its very low surface density, its location within the stream, and its apparently disturbed morphology, we argue that Bootes III may be the progenitor of Styx and in possibly the final throes of tidal dissolution. While the current data do not permit strong constraints, preliminary orbit estimates for the streams do not point to any likely progenitors among the known globular clusters and dwarf galaxies.