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تسجيل مستخدم جديدDetection of a 45 Degree Tidal Stream Associated with the Globular Cluster NGC 5466
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We report on the detection in Sloan Digital Sky Survey data of a 45 degree tidal stream of stars, extending from Bootes to Ursa Major, which we associate with the halo globular cluster NGC 5466. Using an optimal contrast, matched filter technique, we find a long, almost linear stellar stream with an average width of 1.4 degrees. The stream is an order of magnitude more tenuous than the stream associated with Palomar 5. The streams orientation on the sky is consistent to a greater or lesser extent with existing proper motion measurements for the cluster.
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The distribution of stars in the outer part of the sparse globular cluster NGC 5466 provides evidence for possible tidal mass loss after a recent disk-shock near the solar circle.
The study of substructure in the stellar halo of the Milky Way has made a lot of progress in recent years, especially with the advent of surveys like the Sloan Digital Sky Survey. Here, we study the newly discovered tidal tails of the Galactic globul
ar cluster NGC 5466. By means of numerical simulations, we reproduce the shape, direction and surface density of the tidal tails, as well as the structural and kinematical properties of the present-day NGC 5466. Although its tails are very extended in SDSS data (> 45 degrees), NGC 5466 is only losing mass slowly at the present epoch and so can survive for probably a further Hubble time. The effects of tides at perigalacticon and disc crossing are the dominant causes of the slow dissolution of NGC 5466, accounting for about 60 % of the mass loss over the course of its evolution. The morphology of the tails provides a constraint on the proper motion -- the observationally determined proper motion has to be refined (within the stated error margins) to match the location of the tidal tails.
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