Sergey E. Koposov, V. Belokurov, N. W. Evans, G. Gilmore, M. Gieles, M. J. Irwin, G. F. Lewis, M. Niederste-Ostholt, J. Peñarrubia, M. C. Smith, D. Bizyaev, E. Malanushenko, V. Malanushenko, D. P. Schneider, R. F. G. Wyse
The structure of the Sagittarius stream in the Southern Galactic hemisphere
is analysed with the Sloan Digital Sky Survey Data Release 8. Parallel to the
Sagittarius tidal track, but ~ 10deg away, there is another fainter and more
metal-poor stream. We provide evidence that the two streams follow similar
distance gradients but have distinct morphological properties and stellar
populations. The brighter stream is broader, contains more metal-rich stars and
has a richer colour-magnitude diagram with multiple turn-offs and a prominent
red clump as compared to the fainter stream. Based on the structural properties
and the stellar population mix, the stream configuration is similar to the
Northern "bifurcation". In the region of the South Galactic Cap, there is
overlapping tidal debris from the Cetus Stream, which crosses the Sagittarius
stream. Using both photometric and spectroscopic data, we show that the blue
straggler population belongs mainly to Sagittarius and the blue horizontal
branch stars belong mainly to the Cetus stream in this confused location in the
halo.
View original:
http://arxiv.org/abs/1111.7042
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