A Modern Search for Wolf-Rayet Stars in the Magellanic Clouds. III. A Third Year of Discoveries

Philip Massey (1), Kathryn F. Neugent (1), and Nidia Morrell (2)

(1) Lowell Observatory, and Dept of Physics & Astronomy, Northern Arizona University, (2) Las Campanas Observatory, Carnegie Observatory

For the past three years we have been conducting a survey for WR stars in the Large and Small Magellanic Clouds (LMC, SMC). Our previous work has resulted in the discovery of a new type of WR star in the LMC, which we are calling WN3/O3. These stars have the emission-line properties of a WN3 star (strong N V but no N IV), plus the absorption-line properties of an O3 star (Balmer hydrogen plus Pickering He II, but no He I). Yet these stars are 15× fainter than an O3 V star would be by itself, ruling out these being WN3+O3 binaries. Here we report the discovery of two more members of this class, bringing the total number of these objects to 10, 6.5% of the LMC’s total WR population. The optical spectra of nine of these WN3/O3s are virtually indistinguishable from each other, but one of the newly found stars is significantly different, showing a lower excitation emission and absorption spectrum (WN4/O4-ish). In addition, we have newly classified three unusual Of-type stars, including one with a strong C III λ4650 line, and two rapidly rotating “Oef” stars. We also “rediscovered” a low mass x-ray binary, RX J0513.9-6951, and demonstrate its spectral variability. Finally, we discuss the spectra of ten low priority WR candidates that turned out not to have He II emission. These include both a Be star and a B[e] star.

Reference: ApJ, in press
Status: Manuscript has been accepted

Weblink: https://arxiv.org/pdf/1701.07815v1.pdf


Email: phil.massey@lowell.edu