The Close Binary Frequency of Wolf-Rayet Stars as a Function of Metallicity in M31 and M33

Neugent, Kathryn F.; Massey, Philip

doi:10.1088/0004-637x/789/1/10

Cited by 40 publications

(18 citation statements)

References 53 publications

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“…More recently, in 2014, Neugent et al obtained multi-epoch spectra of nearly all of the WRs in M31 and M33 and searched for short period binary systems by observing radial velocity variations within the prominent emission and hydrogen absorption lines. Such hydrogen lines tend to suggest the presence of an O-type star companion (with the notable exceptions being the WN3/O3s, and some hydrogen-rich WRs found in the Galaxy and in the SMC) [134]. This study found that ∼30% of the WRs within M31 and M33 were in short-period binary systems.…”

Section: Binaritymentioning

confidence: 61%

The Wolf–Rayet Content of the Galaxies of the Local Group and Beyond

Neugent

Massey

2019

Galaxies

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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 metallicities poses observational challenges, but presents us with an exacting way to test current stellar evolutionary theories. A technique we have developed and refined involves interference filter imaging combined with image subtraction and crowded-field photometry. This helps us address one of the most controversial topics in current massive star research: the relative importance of binarity in the evolution of massive stars and formation of WRs. Here we discuss the current state of the field, including how the observed WR populations match with the predictions of both single and binary star evolutionary models. We end with what we believe are the most important next steps in WR research.

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Section: Binaritymentioning

confidence: 61%

The Wolf–Rayet Content of the Galaxies of the Local Group and Beyond

Neugent

Massey

2019

Galaxies

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“…We find no evidence that this separation is due to a gradient in exposure time or detector location in the observations. Instead, the separation may point to a metallicity effect, as there is a known chemical abundance gradient in M33, with the highest metallicities occurring at galaxy center and decreasing outwards (Magrini et al 2007;Neugent & Massey 2014). In particular, (Magrini et al 2007) measure this gradient as comprised of two slopes with the break occurring at R ∼ 3 kpc, similar to the radius at which we see the separation between the two histograms in Figure 14.…”

Section: Detectabilitymentioning

confidence: 67%

Supernova remnants in M33: X-ray properties as observed by XMM–Newton

Garofali

Williams

Plucinsky

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We have carried out a study of the X-ray properties of the supernova remnant (SNR) population in M33 with XMM-Newton, comprising deep observations of 8 fields in M33 covering all of the area within the D 25 contours, and with a typical luminosity of 7.1×10 34 erg s −1 (0.2-2.0 keV) . Here we report our work to characterize the X-ray properties of the previously identified SNRs in M33, as well as our search for new X-ray detected SNRs. With our deep observations and large field of view we have detected 105 SNRs at the 3σ level, of which 54 SNRs are newly detected in X-rays, and three are newly discovered SNRs. Combining XMM-Newton data with deep Chandra survey data allows detailed spectral fitting of 15 SNRs, for which we have measured temperatures, ionization timescales, and individual abundances. This large sample of SNRs allows us to construct an X-ray luminosity function, and compare its shape to luminosity functions from host galaxies of differing metallicities and star formation rates to look for environmental effects on SNR properties. We conclude that while metallicity may play a role in SNR population characteristics, differing star formation histories on short timescales, and small-scale environmental effects appear to cause more significant differences between X-ray luminosity distributions. In addition, we analyze the X-ray detectability of SNRs, and find that in M33 SNRs with higher [SII]/Hα ratios, as well as those with smaller galactocentric distances, are more detectable in X-rays.

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“…The relative importance of either channel remains however an ongoing debate (e.g. Vanbeveren et al 1998;Neugent & Massey 2014;Shenar et al 2020). In this context, establishing the evolutionary status of WRs in binary systems is of particular interest as it may offer ways to better constrain the impact of multiplicity on its evolutionary history and, from there, refine our physical understanding of binary evolution.…”

Section: Introductionmentioning

confidence: 99%

BAT99 126: A multiple Wolf-Rayet system in the Large Magellanic Cloud with a massive near-contact binary

Janssens

Shenar

Mahy

et al. 2021

A&A

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Context. BAT99 126 is a multiple system in the Large Magellanic Cloud containing a Wolf-Rayet (WR) star, which has a reported spectroscopic (orbital) period of 25.5 days and a photometric (orbital) period of 1.55 days, and hence is potentially one of the shortest WR binaries known to date. Such short-period binary systems that contain a WR star in low-metallicity environments are prime candidate progenitors of black-hole (BH) mergers. Aims. By thoroughly analysing the spectroscopic and photometric data, we aim to establish the true multiplicity of BAT99 126, to characterise the orbit(s) of the system, to measure the physical properties of its individual components, and to determine the overall evolutionary status of the system. Methods. Using newly acquired high resolution spectra taken with the Ultraviolet and Visual Echelle Spectrograph mounted on the Very Large Telescope, we measured radial velocities via cross-correlation and line-profile fitting and performed a spectral analysis of the individual components using model atmosphere codes. We estimated the age of the system and derived an evolutionary scenario for the 1.55-day system. Results. BAT99 126 comprises at least four components. The 1.55-day photometric signal originates in an eclipsing binary that consists of two O-type stars of spectral types O4 V and O6.5 V, which are both rapid rotators (295 km s −1 and 210 km s −1 , respectively). From the broad emission lines of the WR star, we derived a spectral type WN2.5-3. We further reject the previously reported 25.5-d period for the WR star and find that there is no detectable orbital motion within our uncertainties. The presence of additional narrow Si iii and O ii lines in the composite spectrum corresponds to a fourth component, a B1 V star. There is clear evidence that the B-type star shows a radial velocity variation; however, the data do not allow for a determination of the orbital parameters. The configurations of the B-type star, the WR star, and possible additional undetected components remain unknown. We derived masses for the O-type components of 36 ± 5M and 15 ± 2M , respectively, and estimated the age of the system to be 4.2 Myr. We find evidence of previous or ongoing mass-transfer between the two O-type components and infer initial masses of 23M for the O4 V star and 29M for the O6.5 V star. The O+O binary likely went through a phase of conservative mass transfer and is currently a near-contact system. Conclusions. We show that BAT99 126 is a multiple-quadruple or higher-order-system with a total initial mass of at least 160 M. The 1.55-day O+O binary most likely will not evolve towards a BH+BH merger, but instead will merge before the collapse of components to BHs.

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The Close Binary Frequency of Wolf-Rayet Stars as a Function of Metallicity in M31 and M33

Cited by 40 publications

References 53 publications

The Wolf–Rayet Content of the Galaxies of the Local Group and Beyond

The Wolf–Rayet Content of the Galaxies of the Local Group and Beyond

Supernova remnants in M33: X-ray properties as observed by XMM–Newton

BAT99 126: A multiple Wolf-Rayet system in the Large Magellanic Cloud with a massive near-contact binary

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