Spitzer Space Telescope - General Observer Proposal #50600


The First Mid-Infrared Spectrum of a Low Mass X-Ray Binary

Principal Investigator: Joel Bregman
           Institution: Univerisity of Michigan

     Technical Contact: Joel Bregman, Univerisity of Michigan

Co-Investigators: 
Jon Miller, University of Michigan                                    
Ed Cackett, University of Michigan                                    

Science Category: compact objects 
 Observing Modes: IrsStare 
  Hours Approved: 3.1 

Abstract:
Roche lobe overflow from a low-mass star to a neutron star produces immense
amounts of continuum radiation from an accretion disk. The accretion disk emits
primarily in the X-ray region, although the outer part of the disk dominates the
emission in the UV-optical region, and the Rayleigh-Jeans tail extends into the
mid-infrared region, as seen in Sco X-1. Line emission is also important, as it
reveals critical properties of the accretion disk, the hot wind (if present),
and the local environment. Line emission in the mid-infrared has never been
observed for any LMXB but it can provide critical insights to the object's
environment. For the first time, we propose to measure mid-IR lines from a LMXB
by using the best target, Sco X-1, the brightest persistent X-ray source in the
sky.