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The >100 kpc Distant Spur of the Sagittarius Stream and the Outer Virgo Overdensity, as Seen in PS1 RR Lyrae Stars

Sesar, Branimir and Hernitschek, Nina and Dierickx, Marion I. P. and Fardal, Mark A. and Rix, Hans-Walter (2017) The >100 kpc Distant Spur of the Sagittarius Stream and the Outer Virgo Overdensity, as Seen in PS1 RR Lyrae Stars. Astrophysical Journal Letters, 844 (1). Art .No. L4. ISSN 2041-8213. doi:10.3847/2041-8213/aa7c61.

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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.

Item Type:Article
Related URLs:
URLURL TypeDescription
Sesar, Branimir0000-0002-0834-3978
Hernitschek, Nina0000-0003-1681-0430
Dierickx, Marion I. P.0000-0002-3519-8593
Rix, Hans-Walter0000-0003-4996-9069
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.
Funding AgencyGrant Number
European Research Council (ERC)321035
University of HawaiiUNSPECIFIED
Max-Planck SocietyUNSPECIFIED
Max Planck Institute for AstronomyUNSPECIFIED
Max Planck Institute for Extraterrestrial PhysicsUNSPECIFIED
Johns Hopkins UniversityUNSPECIFIED
Durham UniversityUNSPECIFIED
University of EdinburghUNSPECIFIED
Queens University BelfastUNSPECIFIED
Harvard-Smithsonian Center for AstrophysicsUNSPECIFIED
Las Cumbres Observatory Global Telescope Network IncorporatedUNSPECIFIED
National Central University of TaiwanUNSPECIFIED
Space Telescope Science InstituteUNSPECIFIED
University of MarylandUNSPECIFIED
Eotvos Lorand UniversityUNSPECIFIED
Los Alamos National LaboratoryUNSPECIFIED
Subject Keywords:Galaxy: halo – Galaxy: stellar content – Galaxy: structure – stars: variables: RR Lyrae
Issue or Number:1
Record Number:CaltechAUTHORS:20170717-110103429
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:79129
Deposited By: Ruth Sustaita
Deposited On:17 Jul 2017 20:55
Last Modified:15 Nov 2021 17:45

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