Spitzer Space Telescope - General Observer Proposal #60088


Spitzer/IRAC Study of Stellar Streams Around Nearby Galaxies

Principal Investigator: Seppo Laine
           Institution: Caltech

     Technical Contact: Seppo Laine, Caltech

Co-Investigators: 
Steven Majewski, U. Virginia                                          
Carl Grillmair, Spitzer Science Center                                
Matthew Ashby, CfA/Harvard                                            
David Martinez-Delgado, IAC, Spain                                    
Richard Arendt, CRESST/UMBC/GSFC                                      
R. Jay GaBany, Blackbird Observatory                                  

Science Category: nearby galaxies (z<0.05, v_sys<15,000 km/s) 
 Observing Modes: IRAC Post-Cryo Mapping
  Hours Approved: 23.1 

Abstract:
Minor mergers and satellite accretion events have the ability to dramatically
change the appearance of the parent galaxy and even cause substantial evolution
from bulgeless galaxies toward early-type disk galaxies and ellipticals. They
also presumably take place at a much higher frequency than the more spectacular
major mergers. We propose to characterize the stellar populations of
extragalactic tidal stellar streams with ultra-deep IRAC channel 1 observations
. These observations take advantage of IRAC's unique capability to detect
extended, faint surface brightness emission, and will push IRAC to new
frontiers. We seek to observe two edge-on disk galaxies which have known visible
light stellar streams, and determine the visible light - infrared colors of the
streams. This will help us to determine the structural types and stellar masses
of the disrupted companion galaxies, which has immediate significance on the
understanding of bulge formation, halo build-up and numerous other important
topics that have been proposed to occur with the help of minor mergers. We ask
for a total of 23.1 hours of observing time with IRAC.