Interloper Stars in the Large Magellanic Cloud
Dana Casetti, Terry Girard, William van Altena
A recent radial-velocity study (Olsen et al. 2011) of ~5900 red giants and supergiants in the LMC has uncovered a population of a few hundred stars that have distinct kinematics from the stars of the LMC disk. Metallicities of a subsample of these stars were found to be similar to stars in the Small Magellanic Cloud. This led the authors to suggest the stars were captured from the SMC by the LMC in a previous interaction of the Clouds.
We have used SPM4 proper motions to analyze the extra two velocity dimensions of these stars. Combining the proper motions and radial velocities, we were able to determine that the SMC-captured stars rotate in the same sense as the LMC disk, but at an inclination of about 50 degrees with respect to the disk. The existence of these stars, together with other facts, point to an off-center, moderate to highly inclined collision of the SMC with the LMC disk some 100 to 200 million years ago.
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03.15.2013 Priyamvada Natarajan, Professor of Astronomy, has been elected to an Honorary Professorship for life at the University of Delhi Congratulations! MORE INFO |
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02.25.2013 Yale astrophysicist elected head of American Astronomical Society Astrophysicist C. Megan Urry, Chair of Yale’s Physics Department and Director of the Center for Astronomy & Astrophysics, has been elected the next president of the world’s premier national astronomical society. MORE INFO |
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02.20.2013 Astronomers find smallest known planet — smaller than Mercury A team of scientists including two Yale University astronomers has discovered the smallest planet yet detected. MORE INFO |
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© 2013 Yale University. All Rights Reserved.