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arXiv · 1708.03386

NGC 1866: First Spectroscopic Detection of Fast Rotating Stars in a Young LMC Cluster

A. K. Dupree·A. Dotter·C. I. Johnson·A. F. Marino·A. P. Milone·J. I. Bailey III·J. D. Crane·M. Mateo·E. W. Olszewski
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Abstract

High-resolution spectroscopic observations were taken of 29 extended main sequence turn-off (eMSTO) stars in the young ($\sim$200 Myr) LMC cluster, NGC 1866 using the Michigan/Magellan Fiber System and MSpec spectrograph on the Magellan-Clay 6.5-m telescope. These spectra reveal the first direct detection of rapidly rotating stars whose presence has only been inferred from photometric studies. The eMSTO stars exhibit H-alpha emission (indicative of Be-star decretion disks), others have shallow broad H-alpha absorption (consistent with rotation $\gtrsim $150 km s$^{-1}$), or deep H-alpha core absorption signaling lower rotation velocities ($ \lesssim $150 km s$^{-1}$ ). The spectra appear consistent with two populations of stars - one rapidly rotating, and the other, younger and slowly rotating.

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A. K. Dupree, A. Dotter, C. I. Johnson, A. F. Marino, A. P. Milone, J. I. Bailey III, J. D. Crane, M. Mateo, E. W. Olszewski. 2017-08-10. NGC 1866: First Spectroscopic Detection of Fast Rotating Stars in a Young LMC Cluster. https://doi.org/10.3847/2041-8213/aa85dd

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