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标题：HST Astrometry in the 30 Doradus Region. II. Runaway Stars from New Proper Motions in the Large Magellanic Cloud
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作者：Imants Platais ; Daniel J. Lennon ; Roeland P. van der Marel 等
期刊名称：The Astronomical journal
印刷版ISSN：0004-6256
电子版ISSN：1538-3881
出版年度：2018
卷号：156
期号：3
页码：1-13
DOI：10.3847/1538-3881/aad280
语种：English
出版社：American Institute of Physics
摘要：We present a catalog of relative proper motions for 368,787 stars in the 30 Doradus region of the Large MagellanicCloud (LMC), based on a dedicated two-epoch survey with the Hubble Space Telescope and supplemented withproper motions from our pilot archival study. We demonstrate that a relatively short epoch difference of three yearsis sufficient to reach a level of precision of ∼0.1mas yr −1 or better. A number of stars with relative proper motionsexceeding a 3σ error threshold represent a mixture of Milky Way denizens and 18 potential LMC runaway stars.Based upon 183 VFTS OB stars with the best proper motions, we conclude that none of them moves faster than∼0.3 mas yr −1 in each coordinate—equivalent to ∼70 km s −1 . Among the remaining 351 VFTS stars with lessaccurate proper motions, only one candidate OB runaway can be identified. We rule out any OB star in our samplemoving at a tangential velocity exceeding ∼120 kms −1 . The most significant result of this study is finding 10 starsover a wide range of masses that appear to have been ejected from the massive star cluster R136 in the tangentialplane to angular distances from 35″ out to 407″, equivalent to 8–98 pc. The tangential velocities of these runawaysappear to be correlated with apparent magnitude, indicating a possible dependence on the stellar mass. Lastly, acomparison to proper motions from Gaia DR 2 shows that for several relatively bright stars the DR 2 has anunexpected scatter that cannot be accounted for by the formal errors.
关键词：astrometry;galaxies: Magellanic Clouds;galaxies: individual (30 Dor);proper motions