Galactic Structure and Interstellar Medium Science Working Group


Rubin First Look Image featuring Lagoon and Trifid Nebulae

Introduction and Contact Information

The Galactic Structure and Interstellar Medium Science Working Group [GSISM SWG] is part of the LSST Stars, Milky Way, and Local Volume Science Collaboration. We have a presence on the Discovery Alliance Slack workspace and an e-mail list on Google Groups.
  • Discovery Alliance slack channel: #smwlv-galstruct-ism
  • Google Groups: smwlv-galstruct
GSISM meets on Zoom every two weeks, alternating between Fridays at 08:00 Pacific for Americas/Europe, and Thursdays at 16:00 Pacific for Asia/Pacific, see the SMWLV General Google Calendar.

Science Themes

The GSISM SWG concerns the study of Galactic stellar populations in the field, i.e., in the bulge, disk, and halo, in addition to the interstellar medium in general. The precision astrometry and photometry delivered by the Rubin Observatory will enhance studies of Galactic structure and archaeology including detailed examination of stellar streams, disk asymmetries and oscillations, and of the bar and bulge

Galactic Stellar Populations in the Field

The focus of the GSISM SWG on stellar population studies includes interfaces with the other SMWLV science working groups in the following ways:
  • Star Clusters - GSISM is concerned with field populations, not those in OC/GC environments.
  • Solar Neighborhood - intrinsically faint stellar and substellar objects are covered here. Boundaries with GSISM and the science working group are likely fuzzy.
  • Local Volume (Magellanic Clouds and Near Field Cosmology) - stellar streams trace accretion and assembly history, but also inform us about DM distribution (LV), star formation and populations and dynamics of dwarf satellites (Including MCs),etc.
  • Variable Stars - the working model has been:
    • TVS Variable Stars - more concerned with identification and characterization.
    • SMWLV Variable Stars - more concerned with what variable stars tell us about stellar populations and Galactic structure. Quoting from Variable Stars SWG: “Our focus is to characterize samples of variable stars in the local volume, considering for instance, RR Lyrae and Cepheids, which had been widely used in estimating distances due to their period-luminosity relations, allowing to constrain the structure of their host galaxies. Variable stars have been also used as tracers of chemical abundances. Beyond periodic variables, several transients have been used to trace the underlying large scale structure of the cosmic web.”

GAIA-LSST

This is your home for astrometry. The Vera C. Rubin Observatory Legacy Survey of Space and Time [LSST] will measure new photometry and astrometry for objects that are too faint for Gaia, enabling further exploration of Galactic and Local Group structure and evolution as these observations will place constraints on stellar masses, ages, kinematics, and metallicities.

The Interstellar Medium

LSST photometry of stars can be utilized to map the 3-D distribution of interstellar dust and to infer variations in properties such as grain size. In addition, galactic diffuse emission, including low surface brightness structures, can be mapped using multi-band broad imaging. Temporal changes in morphology and spectral energy distributions will also be detected in Herbig-Haro Objects and other structures.
  • Software for the measure of the optical fluxes from galactic diffuse medium
  • Galactic cirri in deep optical imaging
  • Cirrus and nearby dust
  • ISM in the time domain

Task Forces

GSISM also connects with several cross-collaboration Task Forces:
  • Crowded Stellar Fields (with TVS)
  • Low Surface Brightness (mostly Galaxies, but relevant to ISM photometry)
  • DESC Dark Matter Stellar Streams (DESC led, also SMWLV Local Volume SWG)

Seminar Series

The LSST Galactic Structure and Interstellar Medium science working group is hosting talks during its biweekly meetings. Please refer to our current speaker and topic schedule.

Co-Chairs