The Origin of the Bifurcation in the Sagittarius Stream
نویسنده
چکیده
The latest Sloan Digital Sky Survey data reveal a prominent bifurcation in the distribution of debris of the Sagittarius dwarf spheroidal (Sgr) beginning at a right ascension of α ≈ 190. Two branches of the stream (A and B) persist at roughly the same heliocentric distance over at least 50 of arc. There is also evidence for a more distant structure (C) well behind the A branch. This paper provides the first explanation for the bifurcation. It is caused by the projection of the young leading (A) and old trailing (B) tidal arms of the Sgr, whilst the old leading arm (C) lies well behind A. This explanation is only possible if the halo is close to spherical, as the angular difference between the branches is a measure of the precession of the orbital plane. Subject headings: Galaxy: halo — Galaxy: structure — galaxies: dwarf — galaxies: individual Sgr dSph
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The latest Sloan Digital Sky Survey data tracing the tidal stream from the Sagittarius dwarf spheroidal (dSph) reveals a bifurcation in the distribution of debris. The branching is caused by the projection of the old trailing and young leading tidal arms of the Sagittarius dSph. The angular difference between the branches is a measure of the precession of the orbital plane and hence the aspheri...
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