(Proposal ID) S13A-069

(PI) Tanaka, Mikito

(Proposal Title)
Resolving the stellar halo of an interacting edge-on spiral, NGC4631/NGC4656

(Abstract)
We propose to carry out a high-resolution, deep wide-field survey of a stellar 
halo of an edge-on spiral galaxy (Sc), NGC4631, which is accompanying 
interacting dwarf galaxies such as NGC4656, using Suprime-Cam on Subaru 
telescope in each of the B, V and I_c bands. Since these galaxies are 
obviously in a dynamical interacting state characterized by elongated H_I 
clouds, thickened disk structures and tidal dwarf galaxies surrounding the 
galaxies, this observation enables us to directly explore an on-going halo 
formation associated with minor merger process and violent star formation. Our 
main goal in this study is to explore a spatial distribution of resolved 
old/young stellar populations around NGC4631, and to estimate several 
fundamental properties of NGC4631's halo, such as distance, stellar density 
distribution and metallicity. These parameters help us to compare structure 
and formation scenario of the halo of the interacting galaxy, NGC4631, with 
those of the halos of well-known samples in nearby galaxy groups such as 
NGC55, NGC6503, M31 and Milky Way. This study will provide important clues to 
understanding how a galactic halo forms in such an on-going minor merger.