Bibcode
Platais, I.; Lennon, Daniel J.; van der Marel, Roeland P.; Bellini, Andrea; Sabbi, Elena; Watkins, Laura L.; Sohn, Sangmo T.; Walborn, Nolan R.; Bedin, Luigi R.; Evans, Christopher J.; de Mink, Selma E.; Sana, Hugues; Herrero, A.; Langer, Norbert; Crowther, Paul
Bibliographical reference
The Astronomical Journal, Volume 156, Issue 3, article id. 98, 13 pp. (2018).
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9
2018
Citations
16
Refereed citations
16
Description
We present a catalog of relative proper motions for 368,787 stars in the
30 Doradus region of the Large Magellanic Cloud (LMC), based on a
dedicated two-epoch survey with the Hubble Space Telescope and
supplemented with proper motions from our pilot archival study. We
demonstrate that a relatively short epoch difference of three years is
sufficient to reach a level of precision of ∼0.1 mas
yr‑1 or better. A number of stars with relative proper
motions exceeding 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 less accurate proper motions, only one
candidate OB runaway can be identified. We rule out any OB star in our
sample moving at a tangential velocity exceeding ∼120 km
s‑1. The most significant result of this study is
finding 10 stars over a wide range of masses that appear to have been
ejected from the massive star cluster R136 in the tangential plane to
angular distances from 35″ out to 407″, equivalent to
8–98 pc. The tangential velocities of these runaways appear to be
correlated with apparent magnitude, indicating a possible dependence on
the stellar mass. Lastly, a comparison to proper motions from Gaia DR 2
shows that for several relatively bright stars the DR 2 has an
unexpected scatter that cannot be accounted for by the formal errors.
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Sergio
Simón Díaz