About S5

Mapping stellar streams of the Milky Way with the Anglo-Australian Telescope

S5 is a spectroscopic survey that began in 2018 using the 2dF/AAOmega spectrograph on the 3.9-metre Anglo-Australian Telescope at Siding Spring Observatory. The aim is to map the kinematics and chemistry of stellar streams in the Southern Hemisphere. The initial focus has been on recently identified streams within the footprint of the Dark Energy Survey (DES), with the eventual goal of surveying the entire southern sky.

The streams represent material tidally striped from dwarf galaxies and globular clusters and hence are essential dynamical probes of the dark matter distribution of the Milky Way, as well as providing a detailed snapshot of its accretion history.

The 350 science fibres of the 2dF fibre positioner, the precise photometry of DES DR1, and the superb proper motions from Gaia DR2 allow us to conduct an efficient spectroscopic survey to map these DES streams. In addition to the stream survey, we use spare fibres on each pointing to undertake a Milky Way halo survey, and a low-redshift galaxy survey.

The S5 Surveys

S5 pointing map

S5-Streams

The main survey. The goal is to measure radial velocities and metallicities of stream members. So far S5 has mapped 9 DES streams and 3 streams outside of DES; the former are the first spectroscopic observations of these recently discovered streams.

Artist impression of The Milky Way

S5-Halo

We are able to use some spare fibres for a Milky Way halo survey. This has the aim of observing interesting objects in the halo such as hyper-velocity stars, extremely metal-poor stars, RR Lyraes, and white dwarfs.

(Credit: ESO/L. Calçada)
Low-z galaxy images

S5-LowZ

Nearby faint galaxies are difficult to distinguish from the far more numerous background galaxy population via photometry alone. The goal of including low-redshift (low-z) galaxy targets in S5 is to increase the number of spectroscopically confirmed low-z galaxies in order to better train photometric selection algorithms, and help build a statistic sample of very low-z galaxies.

(Credit: SDSS)
Artist impression of The Milky Way

S5-HiRes

We are also using Magellan/MIKE to obtain high-resolution spectra of bright stream members in order to derive stellar parameters and precise elemental abundances. These will enable us to understand the stream progenitors and chemical evolution.

(Credit: Jennifer Johnson • CC BY-SA-4.0)

Publications

Here are papers from S5:

Data

S5 plan to have the first public data release at the end of 2020.
If you are interested in any S5 data, please contact Ting Li to make your special request.

Below we provide machine-readable versions of large tables published in our papers.

T. S. Li et al (2019)

S5 Membership

The S5 Collaboration consists of roughly 30 members spread across many institutions.

S5 is a collaboration between the members of the DES Milky Way Working Group and a group of Australian astronomers.

If you are interested in getting involved in S5, please contact Ting Li or other members in the S5 leadership team.

S5 leadership

S5 leadership team helps to coordinate the operational and scientific efforts of the collaboration.

Daniel Zucker

Daniel Zucker

Geraint Lewis

Geraint Lewis

Kyler Kuehn

Kyler Kuehn

Other team members

Denis Erkal

Denis Erkal

S5 Dynamical modeling coordinator

Alex Ji

Alex Ji

S5 HIRES coordinator

Sergey Koposov

Sergey Koposov

S5 Data release coordinator

Yao-Yuan Mao

Yao-Yuan Mao

S5 LOWZ
coordinator

Jeremy Mould

Jeremy Mould

Nora Shipp

Nora Shipp

S5 Proper motion coordinator

Jeffrey Simpson

Jeffrey Simpson

S5 Website coordinator

and

Sahar Allam, Eduardo Balbinot, Keith Bechtol, Vasily Belokurov, Andrew Casey, Lara Cullinane, Gary Da Costa, Gayandhi De Silva, Alex Drlica-Wagner, Marla Geha, Dougal Mackey, Sarah Martell, Andrew Pace, Sanjib Sharma, Josh Simon, Douglas Tucker, Kathy Vivas, Zhen Wan, Risa Wechsler, Brian Yanny