Spitzer Space Telescope - General Observer Proposal #3607


KH 15D:  Infrared Emission from Gas and Dust, Near and Far 

Principal Investigator: Drake Deming
           Institution: NASA's Godddard Space Flight Center

Co-Investigators: 
David Charbonneau, California Institute of Technology                 
Eugene Chiang, Univ. of California at Berkeley                        
Joseph Harrington, Cornell University                                 

Science Category: circumstellar/debris disks 
 Observing Modes: IrsStare MipsPhot 
  Hours Approved: 2.1 

Abstract:
The unusual eclipsing object KH 15D is a weak-lined T Tauri star
showing deep periodic eclipses, which must be produced by
circumstellar matter.  Although weak-lined T Tauri stars are not
usually undergoing significant accretion, KH 15D has other
spectroscopic properties normally associated with actively accreting
stars.  For example, it exhibits a rich spectrum of shocked molecular
hydrogen emission, rivaled only by T Tauri itself.  Moreover, the
nature of the KH 15D eclipses is varying with time.  The system has
recently been explained as a spectroscopic binary in which a
nodally-precessing circumbinary ring is gradually blocking the binary
star.  This model immediately calls for mid-IR observations to detect
the thermal emission of the circumbinary ring, and verify its
existence.  We propose low spectral resolution observations using IRS
and MIPS to detect thermal emission from the dusty ring which lies in
the inner environment of the system, and high resolution
long-wavelength spectroscopy to search for forbidden atomic lines, and
rotational lines of molecular hydrogen, formed in the outer
environment of the system.