AAS 205th Meeting, 9-13 January 2005
Session 142 Galactic Structure, Halo and High Velocity
Poster, Thursday, January 13, 2005, 9:20am-4:00pm, Exhibit Hall

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[142.05] Tidal Streams in the Outer Galactic Halo: Pieces of a 500-degree Long Trailing Sagittarius Tidal Tail?

S. L. Pakzad, S. R. Majewski, P. M. Frinchaboy (Univ. of Virginia), C. B. Hummels (Wesleyan Univ.), Z. Ivezic (Univ. of Washington), K. V. Johnston (Wesleyan Univ.), D. R. Law (Caltech), R. J. Patterson (Univ. of Virginia), F. Prada (Inst. de Astrofisica de Andalucia), M. F. Skrutskie (Univ. of Virginia)

The Two Micron All-Sky Survey (2MASS) and Sloan Digital Sky Survey (SDSS) have each proven extremely useful for finding and tracing halo substructure within 50 kpc. However, by combining the databases we identified several halo overdensities beyond 50 kpc that, by their radial velocity trends, we show to have the character of distant tidal stream structures. The positions and velocities of the structures are also consistent with being outlying pieces of a fully wrapped, greater than 510 degree-long trailing tail from the Sagittarius (Sgr) galaxy, for which there is some tantalizing evidence based on a stream-like alignment of distant 2MASS M giant candidates near the Sgr orbital plane. To check this hypothesis, we have used the CAHA 3.5-m, the Blanco 4-m and the Mayall 4-m to obtain the radial velocities of additional distant M giant candidates that appear to lie in possible "connecting strands" to the originally identified overdensities and which, all together, may constitute a continuous, second wrap of the Sgr trailing arm. Such a long debris arm would strengthen considerably the constraints on the orbit of the Sgr core as well as shape and lumpiness of the Milky Way halo potential.

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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.