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| Paper: |
Structure and Population of the NGC 55 Stellar Halo from a Subaru/Suprime-Cam Survey |
| Volume: |
458, Galactic Archaeology: Near-Field Cosmology and the Formation of the Milky Way |
| Page: |
279 |
| Authors: |
Tanaka, M.; Chiba, M.; Komiyama, Y.; Guhathakurta, P.; Kalirai, J. S. |
| Abstract: |
As part of our survey of galactic stellar halos, we investigate the
structure and stellar populations of the north part of the stellar halo
in NGC 55, using deep and wide-field V- and I-band images taken with
Subaru/Suprime-Cam.
From the stellar density maps, we detect the asymmetric disturbed disk structure and the two metal-poor
overdense substructures in the north region of NGC 55, which may correspond to
remnants of the hierarchical formation process of NGC 55's halo.
In addition, we identify a diffuse metal-poor halo extended out to at least z ∼ 16 kpc.
We derive the metallicity distributions (MDs) of these structures
on the basis of the photometric comparison of RGB stars with the theoretical
stellar evolutionary model. The MDs of the thick disk structures show
the peak metallicity of [Fe/H]peak ∼ –1.4 and
the mean metallicity of [Fe/H]mean ∼ –1.7,
while the outer substructures show more metal-poor features than the thick disk structures.
Finally, we discuss the differences of the stellar population and the formation scenario
along the Hubble sequence, by comparing with our previous studies of M31's halo. |
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