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Abstract: We show that the Sagittarius dwarf tidal stream can be traced with very redK-M-giant stars selected from SDSS photometry. A subset of these stars arespectroscopically confirmed with SEGUE and SDSS spectra, and the distance scaleof 2MASS and SDSS M giants is calibrated to the RR Lyrae distance scale. Theabsolute g band magnitude of the K-M-giant stars at the tip of the giant branchis M g=-1.0. The line-of-sight velocities of the M giant and BHB stars that arespatially coincident with the Sgr dwarf tidal stream are consistent with thoseof previous authors, reinforcing the need for new models that can explain allof the Sgr tidal debris stream observations. We estimate stellar densitiesalong the tidal tails that can be used to help constrain future models. TheK-M-giant, BHB, and F-turnoff stars in the lower surface brightness tidalstream that is adjacent to the main leading Sgr dwarf tidal tail havevelocities and metallicities that are similar to those of the stars in theleading tidal tail. The ratio of K-M giants to BHBs and BHBs to F-turnoff starsare also similar for both branches of the leading tidal tail. We show thatthere is an additional low-metallicity tidal stream near the Sgr trailing tidaltail.



Author: Brian Yanny, Heidi Jo Newberg, Jennifer A. Johnson, Young Sun Lee, Timothy C. Beers, Dmitry Bizyaev, Howard Brewington, Paola Re

Source: https://arxiv.org/







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