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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 742660.0, MPI für Astronomie / Publikationen_mpia
Feeling the Pull: A study of natural Galactic accelerometers. II. Kinematics and mass of the delicate stellar stream of the Palomar 5 globular cluster
Authors:Ibata, R. A.; Lewis, G. F.; Thomas, G.; Martin, N. F.; Chapman, S.
Date of Publication (YYYY-MM-DD):2017
Title of Journal:The Astrophysical Journal
Start Page:id. 120 (12 pp)
Audience:Not Specified
Abstract / Description:We present two spectroscopic surveys of the tidal stellar stream of the Palomar 5 globular cluster undertaken with the VLT/FLAMES and AAT/AAOmega instruments. We use these data in conjunction with photometric data presented in the previous contribution in this series to classify the survey stars in terms of their probability of belonging to the Palomar 5 stellar stream. We find that high-probability candidates are only found in a very narrow spatial interval surrounding the locus of the stream on the sky. PanSTARRS RR Lyrae stars in this region of the sky are also distributed in a similar manner. The absence of significant “fanning” of this stellar stream confirms that Palomar 5 does not follow a chaotic orbit. Previous studies have found that Palomar 5 is largely devoid of low-mass stars, and we show that this is true also of the stellar populations along the trailing arm out to 6^\circ . Within this region, which contains 73% of the detected stars, the population is statistically identical to the core, implying that the ejection of the low-mass stars occurred before the formation of the stream. We also present an updated structural model fit to the bound remnant, which yields a total mass of 4297+/- 98{M}ȯ and a tidal radius 0.145+/- 0.009 {kpc}. We estimate the mass of the observed system including the stream to be 12,200 ± 400 M , and the initial mass to have been ~47,000 ± 1500 M . These observational constraints will be employed in our next study to model the dynamics of the system in detail. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada–France–Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institute National des Sciences de l’Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 081.B-0258(A) and ID 083.B-0403(A).
Free Keywords:Galaxy: halo; globular clusters: individual: Palomar 5
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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