Collaborative Research: Through the Gas Darkly: Birth and Death in the Milky Way

University Of California-Davis, Davis CA

Investigators

Abstract

AST 0206309 Becker The majority of stellar births and stellar deaths in the Milky Way take place shrouded from the view of optical telescopes. Centimeter radio waves and hard X-rays can penetrate the gas and dust which obscure our vision, but the limited angular resolution and sensitivity of all previous searches has left us peering through the gas darkly in an attempt to construct a census of star formation and demise in the Galaxy. Drs. David Helfand, at Columbia University, and Robert Becker, at the University of California at Davis, will carry out a new survey of the Galactic Plane with the Very Large Array (VLA), as well as extensive optical and near-infrared follow up observations, to complement a new hard X-ray Galactic plane survey now underway using the XMM-Newton satellite. All of this group's observations (approved and proposed, at X-ray and radio wavelengths) are nonproprietary, and they intend to follow the FIRST survey model in creating a public website which will make available all reduced images as soon as they are constructed and verified. Thus, the survey will provide databases of use to any astronomer working in Galactic astronomy. However, these researchers have identified a number of specific problems on which they intend to focus: a complete census of Galactic supernova remnants, a census of massive star formation, and the definition of complete samples of accretion-powered binary systems. The surveys will open a new window on massive star formation in the Milky Way. All HII regions powered by stars more massive than B0 will be clearly visible to the solar circle on the opposite side of the Galaxy as radio sources coincident with infrared emission detected in the MSX satellite mid-infrared maps of the plane; in addition, many of these star formation complexes will be detectable in the XMM-Newton maps, providing a distance estimate from the X-ray absorption column density. This group will follow up all HII region candidates with a new infrared camera on the MDM 2.4m telescope. The result will be the most complete census yet of massive star formation in the Galaxy. Luminosity functions for several classes of X-ray transients and steady binaries, derived from extensive optical and near-infrared follow up of selected samples of X-ray point sources from the XMM Newton images, will extend 2-3 orders of magnitude fainter than existing data allow, providing important new constraints on close-binary evolution and models for accretion. With both X-ray and radio observing time already allocated, with a new 8K optical camera and a near-infrared imager/spectrometer on the MDM 2.4m telescope and access to the Lick and Keck Observatories, these researchers have the resources in place to provide a striking new view of the Milky Way. ***