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, J. D. Crane, M. Mateo, E. W. Olszewski

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58 Scopus citations


High-resolution spectroscopic observations were taken of 29 extended main-sequence turnoff (eMSTO) stars in the young (∼200 Myr) Large Magellanic Cloud (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 Hα emission (indicative of Be-star decretion disks), others have shallow broad Hα absorption (consistent with rotation 150 km s-1), or deep Hα core absorption signaling lower rotation velocities (≲150 km s-1). The spectra appear consistent with two populations of stars - one rapidly rotating, and the other, younger and slowly rotating.

Original languageEnglish (US)
Article numberL1
JournalAstrophysical Journal Letters
Issue number1
StatePublished - Sep 1 2017


  • globular clusters: individual (NGC 1866)
  • stars: emission-line, Be
  • stars: rotation
  • techniques:spectroscopic

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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