Abstract
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 language | English (US) |
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Article number | L1 |
Journal | Astrophysical Journal Letters |
Volume | 846 |
Issue number | 1 |
DOIs | |
State | Published - Sep 1 2017 |
Keywords
- globular clusters: individual (NGC 1866)
- stars: emission-line, Be
- stars: rotation
- techniques:spectroscopic
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science