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An Orbit for a Massive Wolf-Rayet Binary in the LMC: An Example of Binary Evolution
Breelyn Cocke, Philip Massey, Nidia I. Morrell +6
Wolf-Rayet (WR) stars are helium-burning, evolved massive stars which have had most of their hydrogen-rich outer layers removed either through stellar winds and/or binary stripping…
The Stellar Content of NGC~3603 Revisited: Is the IMF Top Heavy?
Philip Massey, Nidia I. Morrell, Kathryn F. Neugent +3
Studies of the resolved stellar populations of young massive clusters have shown that the slope of the initial mass function appears to be the same everywhere, with no dependence o…
A New Determination of the Mass of NGC 3603-A1: the Most Massive Binary Known?
Philip Massey, Sarah Bodansky, Laura R. Penny +2
The star NGC 3603-A1 has long been known to be a very massive binary, consisting of a pair of O2-3If*/WN5-6 stars, which show Wolf-Rayet-like emission due to their luminosities bei…
The Nature of a Recently Discovered Wolf-Rayet Binary: Archetype of Stripping?
Philip Massey, Kathryn F. Neugent, Nidia I. Morrell +2
LMCe055-1 was recently discovered in a survey for WRs in the Large Magellanic Cloud, and classified as a WN4/O4, a lower excitation version of the WN3/O3 class discovered as part o…
Binary Yellow Supergiants in the Magellanic Clouds I: Photometric Candidate Identification
Anna J. G. O'Grady, Maria R. Drout, Kathryn F. Neugent +3
Recent works have constrained the binary fraction of evolved populations of massive stars in local galaxies such as red supergiants and Wolf-Rayet stars, but the binary fraction of…
Physical Properties of 5,000 Cool LMC Supergiants with Gaia XP Spectra: A Detailed Portrait of the Upper HR Diagram Hints at Missing Supernova Progenitors
Trevor Z. Dorn-Wallenstein, Kathryn F. Neugent, Emily M. Levesque
Characterizing the physical properties of cool supergiants allows us to probe the final stages of a massive star's evolution before it undergoes core collapse. Despite their import…
Constraints on the Binarity of the WN3/O3 Class of Wolf-Rayet Stars
Philip Massey, Kathryn F. Neugent, Nidia I. Morrell
The WN3/O3 Wolf-Rayet (WR) stars were discovered as part of our survey for WRs in the Magellanic Clouds. The WN3/O3s show the emission lines of a high-excitation WN star and the ab…
A Survey for C II Emission-Line Stars in the Large Magellanic Cloud. II. Final Results and the Origin of C II Emission in [WC] Spectra
Bruce Margon, Nidia Morrell, Philip Massey +2
We present the final results of an imaging and spectroscopic search for stars in the Large Magellanic Cloud (LMC) with C II 7231, 7236 emission lines. The goal is to identify and s…
The Time-Averaged Mass-Loss Rates of Red Supergiants As Revealed by their Luminosity Functions in M31 and M33
Philip Massey, Kathryn F. Neugent, Sylvia Ekstrom +2
Mass-loss in red supergiants (RSGs) is generally recognized to be episodic, but mass-loss prescriptions fail to reflect this. Evolutionary models show that the total amount of mass…
Cool, Luminous, and Highly Variable Stars in the Magellanic Clouds. II: Spectroscopic and Environmental Analysis of Thorne-Żytkow Object and Super-AGB Star Candidates
Anna J. G. O'Grady, Maria R. Drout, B. M. Gaensler +9
In previous work we identified a population of 38 cool and luminous variable stars in the Magellanic Clouds and examined 11 in detail in order to classify them as either Thorne-Żyt…
The Properties of Fast Yellow Pulsating Supergiants: FYPS Point the Way to Missing Red Supergiants
Trevor Z. Dorn-Wallenstein, Emily M. Levesque, James R. A. Davenport +3
Fast yellow pulsating supergiants (FYPS) are a recently-discovered class of evolved massive pulsator. As candidate post-red supergiant objects, and one of the few classes of pulsat…
WO-Type Wolf-Rayet Stars: the Last Hurrah of Massive Star Evolution
Erin Aadland, Philip Massey, D. John Hillier +3
Are WO-type Wolf Rayet (WR) stars in the final stage of massive star evolution before core-collapse? Although WC- and WO-type WRs have very similar spectra, WOs show a much stronge…
Locating Red Supergiants in the Galaxy NGC 6822
Tzvetelina A. Dimitrova, Kathryn F. Neugent, Philip Massey +1
Using archival near-IR photometry, we identify 51 of the K-band brightest red supergiants (RSGs) in NGC 6822 and compare their physical properties with stellar evolutionary model p…
Testing Evolutionary Models with Red Supergiant and Wolf-Rayet Populations
Philip Massey, Kathryn F. Neugent, Trevor Z. Dorn-Wallenstein +3
Despite the many successes that modern massive star evolutionary theory has enjoyed, reproducing the apparent trend in the relative number of red supergiants (RSGs) and Wolf-Rayet…
The Red Supergiant Content of M31 and M33
Philip Massey, Kathryn F. Neugent, Emily M. Levesque +2
We identify red supergiants (RSGs) in our spiral neighbors M31 and M33 using near-IR (NIR) photometry complete to a luminosity limit of log L/Lo=4.0. Our archival survey data cover…
Short Term Variability of Evolved Massive Stars with TESS II: A New Class of Cool, Pulsating Supergiants
Trevor Z. Dorn-Wallenstein, Emily M. Levesque, Kathryn F. Neugent +3
Massive stars briefly pass through the yellow supergiant (YSG) phase as they evolve redward across the HR diagram and expand into red supergiants (RSGs). Higher-mass stars pass thr…
The Red Supergiant Binary Fraction of the Large Magellanic Cloud
Kathryn F. Neugent, Emily M. Levesque, Philip Massey +2
The binary fraction of unevolved massive stars is thought to be 70-100% but there are few observational constraints on the binary fraction of the evolved version of a subset of the…
A Survey for C II Emission-Line Stars in the Large Magellanic Cloud
Bruce Margon, Philip Massey, Kathryn F. Neugent +1
We present a narrow-band imaging survey of the Large Magellanic Cloud, designed to isolate the C II 7231, 7236 emission lines in objects as faint as . Th…
The Luminosity Function of Red Supergiants in M31
Kathryn F. Neugent, Philip Massey, Cyril Georgy +5
The mass-loss rates of red supergiant stars (RSGs) are poorly constrained by direct measurements, and yet the subsequent evolution of these stars depends critically on how much mas…
The Wolf-Rayet Content of the Galaxies of the Local Group and Beyond
Kathryn F. Neugent, Philip Massey
Wolf-Rayet stars (WRs) represent the end of a massive star's life as it is about to turn into a supernova. Obtaining complete samples of such stars across a large range of metallic…
Binary Red Supergiants II: Discovering and Characterizing B-type Companions
Kathryn F. Neugent, Emily M. Levesque, Philip Massey +1
The percentage of massive main sequence OB stars in binary systems is thought to be as high as 100%. However, very few Galactic binary red supergiants (RSGs) have been identified,…
A Runaway Giant in the Galactic Halo
Philip Massey, Stephen E. Levine, Kathryn F. Neugent +3
New evidence provided by the Gaia satellite places the location of the runaway star J01020100-7122208 in the halo of the Milky Way (MW) rather than in the Small Magellanic Cloud as…
Shedding Light on the Isolation of Luminous Blue Variables
Erin Aadland, Philip Massey, Kathryn F. Neugent +1
In the standard view of massive star evolution, luminous blue variables (LBVs) are transitional objects between the most massive O-type stars and Wolf-Rayet (WR) stars. With short…
Binary Red Supergiants: A New Method for Detecting B-type Companions
Kathryn F. Neugent, Emily M. Levesque, Phil Massey
With the exception of a few well-known and studied systems, the binary population of red supergiants (RSGs) remains relatively uncharacterized. Famous systems such as VV Cep, 31 Cy…