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

Abstract

The numbers and types of evolved massive stars found in nearby galaxies provide an exacting test of stellar evolution models. Because of their proximity and rich massive star populations, the Magellanic Clouds have long served as the linchpins for such studies. Yet the continued accidental discoveries of Wolf-Rayet (WR) stars in these systems demonstrate that our knowledge is not as complete as usually assumed. Therefore, we undertook a multi-year survey for WRs in the Magellanic Clouds. Our results from our first year (reported previously) confirmed nine new LMC WRs. Of these, six were of a type never before recognized, with WN3-type emission combined with O3-type absorption features. Yet these stars are 2-3 magnitudes too faint to be WN3+O3 V binaries. Here we report on the second year of our survey, including the discovery of four more WRs, two of which are also WN3/O3s, plus two "slash" WRs. This brings the total of LMC WRs known to 152, 13 (8.2%) of which were found by our survey, which is now 60% complete. We find that the spatial distribution of the WN3/O3s are similar to that of other WRs in the LMC, suggesting that they are descended from the same progenitors. We call attention to the fact that five of the 12 known SMC WRs may in fact be similar WN3/O3s rather than the binaries they have often assumed to be. We also discuss our other discoveries: a newly found Onfp-type star, and a peculiar emission-line object. Finally, we consider the completeness limits of our survey.

arXiv commentApJ, in press

References in corpus (26)

• The Fourth US Naval Observatory CCD Astrograph Catalog (UCAC4)
• Astrometry.net: Blind astrometric calibration of arbitrary astronomical images
• The Galactic O-Star Spectroscopic Survey (GOSSS). II. Bright Southern Stars
• The Magellanic Clouds Photometric Survey: The Large Magellanic Cloud Stellar Catalog and Extinction Map
• The Galactic O-Star Spectroscopic Survey. I. Classification System and Bright Northern Stars in the Blue-Violet at R~2500
• The Magellanic Clouds Photometric Survey: The Small Magellanic Cloud Stellar Catalog and Extinction Map
• Stellar Population Effects on the Inferred Photon Density at Reionization
• The Wolf-Rayet stars in the Large Magellanic Cloud: A comprehensive analysis of the WN class
• The MagE Spectrograph
• The Progenitor Masses of Wolf-Rayet Stars and Luminous Blue Variables Determined from Cluster Turn-offs. I. Results from 19 OB Associations in the Magellanic Clouds
• A Survey of Local Group Galaxies Currently Forming Stars: II. UBVRI Photometry of Stars in Seven Dwarfs and a Comparison of the Entire Sample
• Spectral Classification of O2-3.5If*/WN5-7 stars
• Yellow and Red Supergiants in the Large Magellanic Cloud
• Early Results from the Galactic O-Star Spectroscopic Survey: C III Emission Lines in Of Spectra
• The Deep Lens Survey Transient Search I : Short Timescale and Astrometric Variability
• NGC 1624-2: A slowly rotating, X-ray luminous Of?cp star with an extraordinarily strong magnetic field
• A Modern Search for Wolf-Rayet Stars in the Magellanic Clouds: First Results
• Yellow Supergiants in the Small Magellanic Cloud (SMC): Putting Current Evolutionary Theory to the Test
• The Wolf-Rayet Content of M33
• The Wolf-Rayet Content of M31
• The Onfp Class in the Magellanic Clouds
• The Discovery of a Twelfth Wolf-Rayet Star in the Small Magellanic Cloud
• Massive Stars in the Galaxies of the Local Group
• Astronomical Spectroscopy
• The Discovery of a Rare WO-type Wolf-Rayet Star in the Large Magellanic Cloud
• A New Class of Wolf-Rayet Stars: WN3/O3s

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• Ejection of the massive Hydrogen-rich envelope timed with the collapse of the stripped SN2014C
• Metamorphosis of SN 2014C: Delayed Interaction Between a Hydrogen Poor Core-collapse Supernova and a Nearby Circumstellar Shell
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• A Modern Search for Wolf-Rayet Stars in the Magellanic Clouds. IV. A Final Census
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• Clues about the scarcity of stripped-envelope stars from the evolutionary state of the sdO+Be binary system phi Persei
• A Spectroscopic Survey of Massive Stars in M31 and M33
• The Evolution and Physical Parameters of WN3/O3s: a New Type of Wolf-Rayet Star
• SN 2016coi (ASASSN-16fp): an energetic H-stripped core-collapse supernova from a massive stellar progenitor with large mass loss
• Jets in Hydrogen-poor Super-luminous Supernovae: Constraints from a Comprehensive Analysis of Radio Observations
• Low-metallicity massive single stars with rotation. II. Predicting spectra and spectral classes of chemically-homogeneously evolving stars
• A Modern Search for Wolf-Rayet Stars in the Magellanic Clouds. III. A Third Year of Discoveries
• A Dark Energy Camera Search for Missing Supergiants in the LMC After the Advanced LIGO Gravitational Wave Event GW150914
• Extreme isolation of WN3/O3 stars and implications for their evolutionary origin as the elusive stripped binaries
• The Evolution of Massive Stars: Bridging the Gap in the Local Group
• Revealing the nebular properties and Wolf-Rayet population of IC10 with Gemini/GMOS
• The Wolf-Rayet star population in the dwarf galaxy NGC 625
• A deep near-infrared spectroscopic survey of the Scutum-Crux arm for Wolf-Rayet stars
• Newly Discovered Wolf-Rayet Stars in M31
• He II Emission from Wolf-Rayet Stars as a Tool for Measuring Dust Reddening
• A Survey for C II Emission-Line Stars in the Large Magellanic Cloud
• Constraints on the Binarity of the WN3/O3 Class of Wolf-Rayet Stars
• The emission-line regions in the nucleus of NGC 1313 probed with GMOS-IFU: a supergiant/hypergiant candidate and a kinematically cold nucleus
• The Stripped-Star Ultraviolet Magellanic Cloud Survey (SUMS): The UV Photometric Catalog and Stripped Star Candidate Selection
• Testing Evolutionary Models with Red Supergiant and Wolf-Rayet Populations
• The Evolutionary Status of WN3/O3 Wolf-Rayet Stars