The >100 kpc Distant Spur of the Sagittarius Stream and the Outer Virgo Overdensity, as Seen in PS1 RR Lyrae Stars
Abstract
We report the detection of spatially distinct stellar density features near the apocenters of the Sagittarius (Sgr) stream's main leading and trailing arm. These features are clearly visible in a high-fidelity stellar halo map that is based on RR Lyrae from Pan-STARRS1: there is a plume of stars 10 kpc beyond the apocenter of the leading arm, and there is a "spur" extending to 130 kpc, almost 30 kpc beyond the previously detected apocenter of the trailing arm. Such an apocenter substructure is qualitatively expected in any Sgr stream model, as stars stripped from the progenitor at different pericenter passages become spatially separated there. The morphology of these new Sgr stream substructures could provide much-needed new clues and constraints for modeling the Sgr system, including the level of dynamical friction that Sgr has experienced. We also report the discovery of a new, presumably unrelated halo substructure at 80 kpc from the Sun and 10° from the Sgr orbital plane, which we dub the outer Virgo overdensity.
Additional Information
© 2017 American Astronomical Society. Received 2017 June 11; revised 2017 June 26; accepted 2017 June 28; published 2017 July 17. B.S. would like to dedicate this work to his son, Elon. B.S. would also like to thank his family, friends, and colleagues for supporting him over 15 years in Astronomy. B.S., N.H., and H.-W.R. acknowledge funding from the European Research Council under the European Unions Seventh Framework Programme (FP 7) ERC Grant Agreement No. [321035]. M.F. acknowledges support through HST grant GO-13443. The Pan-STARRS1 Surveys (PS1) have been made possible through contributions by the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, the Queen's University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, and the National Aeronautics and Space Administration under grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation grant No. AST-1238877, the University of Maryland, Eotvos Lorand University (ELTE), and the Los Alamos National Laboratory.Attached Files
Published - Sesar_2017_ApJL_844_L4.pdf
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Additional details
- Eprint ID
- 79129
- Resolver ID
- CaltechAUTHORS:20170717-110103429
- 321035
- European Research Council (ERC)
- GO-13443
- NASA
- University of Hawaii
- Pan-STARRS Project Office
- Max-Planck Society
- Max Planck Institute for Astronomy
- Max Planck Institute for Extraterrestrial Physics
- Johns Hopkins University
- Durham University
- University of Edinburgh
- Queens University Belfast
- Harvard-Smithsonian Center for Astrophysics
- Las Cumbres Observatory Global Telescope Network Incorporated
- National Central University of Taiwan
- Space Telescope Science Institute
- NNX08AR22G
- NASA
- AST-1238877
- NSF
- University of Maryland
- Eotvos Lorand University
- Los Alamos National Laboratory
- Created
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2017-07-17Created from EPrint's datestamp field
- Updated
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2021-11-15Created from EPrint's last_modified field