The sagittarius streams in the southern galactic hemisphere

Sergey E. Koposov, V. Belokurov, N. W. Evans, G. Gilmore, M. Gieles, M. J. Irwin, G. F. Lewis, M. Niederste-Ostholt, J. Pẽarrubia, M. C. Smith, D. Bizyaev, E. Malanushenko, V. Malanushenko, D. P. Schneider, R. F.G. Wyse

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Abstract

The structure of the Sagittarius stream in the southern Galactic hemisphere is analyzed with the Sloan Digital Sky Survey Data Release 8. Parallel to the Sagittarius tidal track, but 10° 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 color-magnitude diagram with multiple turnoffs 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.

Original languageEnglish (US)
Article number80
JournalAstrophysical Journal
Volume750
Issue number1
DOIs
StatePublished - May 1 2012

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Koposov, S. E., Belokurov, V., Evans, N. W., Gilmore, G., Gieles, M., Irwin, M. J., Lewis, G. F., Niederste-Ostholt, M., Pẽarrubia, J., Smith, M. C., Bizyaev, D., Malanushenko, E., Malanushenko, V., Schneider, D. P., & Wyse, R. F. G. (2012). The sagittarius streams in the southern galactic hemisphere. Astrophysical Journal, 750(1), [80]. https://doi.org/10.1088/0004-637X/750/1/80