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Another Look at the Eastern Banded Structure: A Stellar Debris Stream and a Possible Progenitor

Grillmair, C. J. (2011) Another Look at the Eastern Banded Structure: A Stellar Debris Stream and a Possible Progenitor. Astrophysical Journal, 738 (1). Art. No. 98. ISSN 0004-637X.

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Using the Sloan Digital Sky Survey Data Release 7, we re-examine the Eastern Banded Structure (EBS), a stellar debris stream first discovered in Data Release 5 and more recently detected in velocity space by Schlaufman et al. The visible portion of the stream is 18° long, lying roughly in the Galactic Anticenter direction and extending from Hydra to Cancer. At an estimated distance of 9.7 kpc, the stream is ≈170 pc across on the sky. The curvature of the stream implies a fairly eccentric box orbit that passes close to both the Galactic center and to the Sun, making it dynamically distinct from the nearby Monoceros, Anticenter, and GD-1 streams. Within the stream is a relatively strong, 2°-wide concentration of stars with a very similar color-magnitude distribution that we designate Hydra I. Given its prominence within the stream and its unusual morphology, we suggest that Hydra I is the last vestige of EBS's progenitor, possibly already unbound or in the final throes of tidal dissolution. Though both Hydra I and the EBS have a relatively high-velocity dispersion, given the comparatively narrow width of the stream and the high frequency of encounters with the bulge and massive constituents of the disk that such an eccentric orbit would entail, we suggest that the progenitor was likely a globular cluster and that both it and the stream have undergone significant heating over time.

Item Type:Article
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Grillmair, C. J.0000-0003-4072-169X
Additional Information:© 2011 The American Astronomical Society. Received 2011 June 24; accepted 2011 June 24; published 2011 August 16. The author is grateful to an anonymous referee for constructive and insightful comments. Thanks also go to Kevin Schlaufman for providing the positions of ECHOS member stars. Funding for the creation and distribution of the SDSS Archive has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Aeronautics and Space Administration, the National Science Foundation, the U.S. Department of Energy, the Japanese Monbukagakusho, and the Max Planck Society. Facility: Sloan
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Alfred P. Sloan FoundationUNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
Japanese MonbukagakushoUNSPECIFIED
Max Planck SocietyUNSPECIFIED
Subject Keywords:Galaxy: halo; Galaxy: structure; globular clusters: general
Issue or Number:1
Classification Code:PACS: 98.20.Gm; 98.35.Jk; 98.35.Gi
Record Number:CaltechAUTHORS:20110908-132114920
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Official Citation:Another Look at the Eastern Banded Structure: A Stellar Debris Stream and a Possible Progenitor C. J. Grillmair 2011 ApJ 738 98
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:25261
Deposited By: Ruth Sustaita
Deposited On:08 Sep 2011 20:45
Last Modified:03 Oct 2019 03:04

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