arXiv subjects

E. Laplace

Publications and source records attributed to E. Laplace.

At least 19 recordsLinked to original sources

arXiv2026

A clear detection of proper motion confirms that the claimed $\mathbf{z\simeq32}$ galaxy candidate, "Capotauro'', is a Y-type brown dwarf

The compact red source ``Capotauro'', discovered in deep JWST imaging in 2025, has been suggested as a possible galaxy candidate at redshift $z\simeq32$ on account of its extreme NIRCam colours. However, given the lack of evidence that this source is spatially resolved, a very cool brown dwarf, at a distance consistent with the scale-height of the Milky Way stellar disc ($\simeq 500$ pc), provides an alternative explanation of the observed photometry. Here we exploit new medium-band NIRCam imaging obtained $\simeq 3.5$ years after the discovery data to test this hypothesis. Using filter-dependent point-spread-function fitting, a robust local relative astrometric frame defined by 68 compact reference sources, and a joint four-image injection-recovery analysis, we show that Capotauro has moved by $132 \pm 20$ mas over the 3.5-yr interval span of the observations, ruling out the possibility that it is an extragalactic source (galaxy, AGN, or supernova) at $> 6 \sigma$. The observed apparent proper motion is $(\mu_\xi,\mu_\eta)=(+9.4^{+6.4}_{-4.8},-35.6^{+5.1}_{-5.9})$ mas yr$^{-1}$, or $37.6^{+5.5}_{-5.6}$ mas yr$^{-1}$ in total. Through comparison of its photometric spectral energy distribution with empirical templates, we find that Capotauro is best described as a brown dwarf of spectral type Y$1.0\pm0.5$ ($T_{\rm eff}\approx350$ K) at a distance of $730\pm110$ pc (although the existing data and spectral templates are insufficient to rule out an even colder, later-type brown dwarf). Capotauro is thus one of the most distant Y dwarfs found to date, as expected given its discovery in a deep JWST extragalactic survey field. This result demonstrates the value of multi-epoch imaging for identifying substellar contaminants among the most extreme photometric-redshift candidates.

astro-ph.GA↗

arXiv2026

Reframing the Wide Eccentric Binary Problem: Eccentricity as a Probe of Mass-transfer Physics

Observations of wide post-interaction binaries show an unexpected feature; orbital eccentricity, which is not understood theoretically. A promising resolution to this long-standing puzzle is eccentric mass transfer (MT). Here the first complete framework for MT in orbits with arbitrary eccentricity, the general mass-transfer (GeMT) model, is confronted with the latest observations of hot subdwarfs of spectral type B (sdB) with main-sequence (MS) companions in wide orbits. SdBs are excellent benchmarks for binary evolution models, since their progenitors provide unique constraints on their formation histories. We isolate the effects of eccentric MT from other physical process and we show that it explains the observed orbital-parameter distributions and their correlations seen in wide sdB+MS binaries. To quantitatively constrain their orbital parameters, stellar evolution and tides should be included in future studies, yet it is encouraging that the GeMT model provides the first mechanism that qualitatively reproduces the observed distributions. We further demonstrate that post-MT eccentricities depend directly on key MT parameters, including transferred mass, accretion efficiency, and angular momentum loss. Given the multitude of eccentric post-MT binaries with components ranging from low- to high-mass stars to compact objects, we propose that post-MT eccentricities offer a new window onto binary evolution, presenting a powerful tool to constrain highly uncertain binary-evolution parameters and mass-transfer formation histories across diverse populations. Post-MT eccentricity should therefore be embraced as a key observable, rather than treated as a problem to be corrected.

astro-ph.SR↗

arXiv2025

Rethinking mass transfer: a unified semianalytical framework for circular and eccentric binaries. II. Orbital evolution due to nonconservative mass transfer

Although mass transfer (MT) has been studied primarily in circular binaries, observations show that it also occurs in eccentric systems. We investigate orbital evolution during nonconservative MT in eccentric orbits, a process especially relevant for binaries containing compact objects (COs). We examined four angular momentum loss (AML) modes: Jeans, isotropic reemission, orbital-AML, and $L_2$ mass loss, with the last mode being the most efficient AML mode. For a fixed AML mode and accretion efficiency, orbital evolution is correlated: orbits either widen while becoming more eccentric, or shrink while circularizing. Jeans mode generally yields orbital widening and eccentricity pumping, whereas $L_2$ mass loss typically leads to orbital shrinkage and eccentricity damping. Isotropic reemission and orbital-AML show an intermediate behavior. Adopting isotropic reemission, we demonstrate that eccentric MT produces compact binaries that merge via gravitational waves (GW) within a Hubble time, whereas the same systems would instead merge during MT under traditional modeling. We further show that, in eccentric orbits, the gravitational potential at $L_2$ becomes lower than at $L_1$ across a wide range of mass ratios and eccentricities, naturally linking eccentricity to $L_2$ mass loss. Eccentric MT may therefore lead to the formation of the circumbinary disks observed around eccentric post-red-giant-branch and post-asymptotic-giant-branch systems. Since interacting binaries containing COs are frequently eccentric, $L_2$ mass loss offers a new robust pathway to orbital tightening during eccentric MT, contributing to the formation rate of GW sources. This model can treat orbital evolution due to conservative and nonconservative MT in arbitrary eccentricities, with applications ranging from MT on the main sequence to GW progenitors.

astro-ph.SR↗

arXiv2025

Rethinking mass transfer: a unified semi-analytical framework for circular and eccentric binaries. I. Orbital evolution due to conservative mass transfer

Mass transfer (MT) is a fundamental process in stellar evolution. While MT in circular orbits is well studied, observations indicate that it also occurs in eccentric ones, where theoretical models are limited. We present a new semi-analytic framework for the secular orbital evolution of mass-transferring binaries, treating stars either as point-masses or as extended bodies. For the first time, a MT model is applicable to both circular and eccentric orbits and accommodates conservative and non-conservative MT across a broad range of mass ratios and stellar spins. We derive secular, orbit-averaged equations describing the orbital evolution by treating MT, mass loss, and angular momentum (AM) loss as perturbations to the general two-body problem. Assuming conservative MT, we compare our results to previous models and validate them against numerical integrations. Our model predicts eccentric post-MT systems in wider orbits than classical results. Compared to other eccentric MT frameworks we find a broader parameter space for orbital widening and eccentricity pumping. Accounting for extended bodies yields stronger semimajor axis and eccentricity growth at a given mass ratio, and further broadens the parameter space for orbital widening and eccentricity pumping. Whether extended bodies are considered or not, eccentric MT naturally predicts higher eccentricities at longer orbital periods, a correlation observed in numerous post-MT systems, providing a robust mechanism for their formation. Our model can be integrated into binary evolution and population synthesis codes to consistently treat conservative and non-conservative MT in arbitrarily eccentric orbits with applications ranging from MT on the main sequence to gravitational-wave progenitors.

astro-ph.SR↗

arXiv2025

New gravitational-wave data support a bimodal black-hole mass distribution

Detailed stellar evolution and supernova models yield a bimodal black-hole mass distribution with a narrow peak around 10 solar masses from stars within a narrow range of progenitor properties and a second broader peak starting around 20 solar masses from very massive progenitors. This bimodal black-hole mass distribution leads to a characteristic distribution of chirp masses of merging binary black holes, with two main peaks arising from the merger of two black holes where both come either from the low- or the high-mass peak and a smaller peak in between from the mixed merger of a low-mass and a high-mass black hole. We carry out a population synthesis study of binary black hole formation and compare the results to the observed chirp masses of gravitational-wave events. We find that only the bimodal black-hole mass prescription is able to reproduce the structure of peaks and gaps in the observed chirp-mass distribution, which is not matched by predictions from other remnant mass prescriptions in the literature.

astro-ph.HE↗

arXiv2025

Explosions of pulsating red supergiants: a natural pathway for the diversity of Type II-P/L supernovae

Red supergiants (RSGs), which are progenitors of hydrogen-rich Type II supernovae (SNe), have been known to pulsate from both observations and theory. The pulsations can be present at core collapse and affect the resulting SN. However, SN light curve models of such RSGs commonly use hydrostatic progenitor models and ignore pulsations. Here, we model the final stages of a 15 solar-mass RSG and self-consistently follow the hydrodynamical evolution. We find the growth of large amplitude radial pulsations in the envelope. After a transient phase where the envelope restructures, the pulsations settle to a steady and periodic oscillation with a period of 817 days. We show that they are driven by the $κγ$-mechanism, which is an interplay between changing opacities and the release of recombination energy of hydrogen and helium. This leads to complex and non-coherent expansion and contraction in different parts of the envelope, which greatly affect the SN progenitor properties, including its location in the Hertzsprung-Russell diagram. We simulate SN explosions of this model at different pulsations phases. Explosions in the compressed state result in a flat light curve (Type II-P). In contrast, the SN light curve in the expanded state declines rapidly, reminiscent of a Type II-L SN. For cases in between, we find light curves with various decline rates. Features in the SN light curves are directly connected to features in the density profiles. These are in turn linked to the envelope ionization structure, which is the driving mechanism of the pulsations. We predict that some of the observed diversity in Type II SN light curves can be explained by RSG pulsations. For more massive RSGs, we expect stronger pulsations that might even lead to dynamical mass ejections of the envelope and to an increased diversity in SN light curves.

astro-ph.SR↗

arXiv2025

Explodability criteria for the neutrino-driven supernova mechanism

Massive stars undergoing iron core-collapse at the end of their evolution terminate their lives either in successful or failed supernovae (SNe). The physics of core-collapse supernovae (CCSNe) is complex, and their understanding requires computationally expensive simulations. Using these to predict CCSN outcomes over large, densely sampled parameter spaces of SN progenitors, as is needed e.g. for population synthesis studies, is thus not feasible. To remedy this situation, we present explodability criteria that allow us to predict the final fates of stars by evaluating stellar structure variables at the onset of core-collapse. The criteria are calibrated to predictions of a semi-analytical SN model, evaluated over a set of $\sim$~3,900 heterogeneous stellar progenitors (single, binary-stripped and accretor stars). Over these, the criteria achieve an accuracy of >99\% agreement with the semi-analytical model. The criteria are tested on 29 state-of-the-art 3D CCSN simulation outcomes from two different groups. Furthermore, we find that all explodability proxies needed for our pre-SN structure-based criteria have two distinct peaks and intervening valleys as a function of the carbon-oxygen (CO) core mass $M_\mathrm{CO}$, which coincide with failed and successful SNe, respectively. The CO core masses of explodability peaks shift systematically with metallicity, $Z$, and with timing of hydrogen-rich envelope removal by binary mass transfer. With these, we identify critical values in $M_\mathrm{CO}$ that define windows over which black holes form by direct collapse and formulate a CCSN recipe based on $M_\mathrm{CO}$ and $Z$, applicable for rapid binary population synthesis and other studies. Our explodability formalism is consistent with observations of Type~IIP, IIb/Ib and Ic supernova progenitors and partially addresses the missing Red Supergiant Problem by direct black hole formation.

astro-ph.SR↗

arXiv2025

Supernovae from stellar mergers and accretors of binary mass transfer: Implications for Type IIP, 1987A-like and interacting supernovae

As most massive stars are born in binary and other multiple-star systems, many are expected to exchange mass with a companion star or merge with it during their lives. This means that most supernovae (SNe) are from such binary products. Here, we focus on hydrogen-rich Type II SNe from accretors of binary mass transfer and stellar mergers. We compute various SN properties such as the explosion energies, nickel yields, and neutron star (NS) kick velocities, but also consider NS masses. We find tight correlations between these parameters and, e.g., the central specific entropy and core compactness. However, there is no obvious relation between these explosion properties and the evolutionary history of the pre-SN stars. We find linear relations between the nickel mass and the SN explosion energy and the NS remnant mass. We further group our models into progenitors of SNe IIP, SN 1987A-like and interacting SNe, predict their SN and SN-progenitor properties and compare to observations. Accretors of binary mass transfer and stellar mergers naturally produce SNe IIP with long plateau durations from progenitors with relatively small CO-cores but large envelope masses (c.f. SN 2015ba). Our models give rise to tight relations between the plateau luminosity and the nickel mass as well as the SN ejecta velocity as inferred observationally for SNe IIP. We speculate that cool/red supergiants at $\log\,L/L_\odot\,{\geq}\,5.5$ encounter enhanced mass loss due to envelope instabilities and could then explode in interacting SNe IIn. The rate of such SNe from our models seems compatible with observations. Some of our binary models explode as $10^6\,L_\odot$ blue supergiants that may have encountered enhanced and/or eruptive mass loss shortly before their SNe and could thus help understand interacting SNe such as SN 1961V and SN 2005gl but also superluminous Type II SNe such as SN 2010jl. [abridged]

astro-ph.HE↗

arXiv2024

Finding the Fuse: Prospects for the Detection and Characterization of Hydrogen-Rich Core-Collapse Supernova Precursor Emission with the LSST

Enhanced emission in the months to years preceding explosion has been detected for several core-collapse supernovae (SNe). Though the physical mechanisms driving the emission remain hotly debated, the light curves of detected events show long-lived ($\geq$50 days), plateau-like behavior, suggesting hydrogen recombination may significantly contribute to the total energy budget. The Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) will provide a decade-long photometric baseline to search for this emission, both in binned pre-explosion observations after an SN is detected and in single-visit observations prior to the SN explosion. In anticipation of these searches, we simulate a range of eruptive precursor models to core-collapse SNe and forecast the discovery rates of these phenomena in LSST data. We find a detection rate of ~40-130 yr$^{-1}$ for SN IIP/IIL precursors and ~110 yr$^{-1}$ for SN IIn precursors in single-epoch photometry. Considering the first three years of observations with the effects of rolling and observing triplets included, this number grows to a total of 150-400 in binned photometry, with the highest number recovered when binning in 100-day bins for 2020tlf-like precursors and in 20-day bins for other recombination-driven models from the literature. We quantify the impact of using templates contaminated by residual light (from either long-lived or separate precursor emission) on these detection rates, and explore strategies for estimating baseline flux to mitigate these issues. Spectroscopic follow-up of the eruptions preceding core-collapse SNe and detected with LSST will offer important clues to the underlying drivers of terminal-stage mass loss in massive stars.

astro-ph.HE↗

arXiv2024

It's written in the massive stars: The role of stellar physics in the formation of black holes

In the age of gravitational-wave (GW) sources and newly discovered local black holes (BH) and neutron stars (NS), understanding the fate of stars is a key question. Not every massive star is expected to successfully explode as a supernova and leave behind a NS; some stars form BHs. The remnant depends on explosion physics but also on the final core structure, often summarized by the compactness parameter or iron core mass, where high values have been linked to BH formation. Several groups have reported similar patterns in these parameters as a function of mass, characterized by a prominent compactness peak followed by another peak at higher masses, pointing to a common underlying physical mechanism. Here, we investigate its origin by computing single-star models from 17 to 50 solar masses with MESA. The first and second compactness increases originate from core carbon and neon burning, respectively, becoming neutrino dominated, which enhances the core contraction and ultimately increases the iron-core mass and compactness. An early core neon ignition during carbon burning, and an early silicon ignition during oxygen burning help counter the core contraction and decrease the final iron core mass and compactness. Shell mergers between C/Ne and O-burning shells further decrease the compactness and we show that they are due to an enhanced entropy production in these layers. We find that the final structure of massive stars is not random but already written in their cores at core helium exhaustion. The same mechanisms determine the final structure of any star in this core mass range, including binary products, though binary interactions systematical shift the range of expected BH formation. Finally, we discuss the role of stellar physics uncertainties and how to apply these findings to studies of GW sources. [Abridged]

astro-ph.SR↗

arXiv2024

Pre-supernova evolution and final fate of stellar mergers and accretors of binary mass transfer

The majority of massive stars are expected to exchange mass or merge with a companion during their lives. This immediately implies that most supernovae (SNe) are from such post-mass-exchange objects. Here, we explore how mass accretion and merging affect the pre-SN structures of stars and their final fates. We use the stellar evolution code MESA, infer the outcome of core-collapse using a neutrino-driven SN model, and apply a rapid-accretion model. Our models cover initial masses from 11 to 70 Msun and the accreted mass ranges from 10-200% of the initial mass. We find that mass accretion in particular onto post-main-sequence (post-MS) stars can lead to a long-lived blue supergiant (BSG) phase. In comparison to genuine single stars, post-MS accretors have small core-to-total mass ratios, regardless of whether they end their lives as BSGs or cool supergiants (CSGs), and they can have genuinely different pre-SN core structures. As in single and binary-stripped stars, we find black-hole (BH) formation for the same characteristic CO core masses M_CO of ~7 Msun and >13 Msun. In models with the largest mass accretion, the BH-formation landscape as a function of M_CO is shifted by about 0.5 Msun to lower masses. We find a tight relation between our neutron-star (NS) masses and the central entropy of the pre-SN models, suggesting a universal relation that is independent of the evolutionary history of stars. Post-MS accretors explode both as BSGs and CSGs, and we show how to understand their pre-SN locations in the Hertzsprung--Russell diagram. Some BSGs that avoid the luminous-blue-variable (LBV) regime are predicted to collapse into BHs of up to 50 Msun while others explode in supernovae and eject up to 40 Msun, greatly exceeding ejecta masses from single stars. These masses can be even higher at lower metallicities, and they may fall into the pair-instability-supernova mass gap. [abridged]

astro-ph.SR↗

arXiv2023

Convective-core overshooting and the final fate of massive stars

Massive stars can explode in powerful supernovae (SNe) forming neutron stars but they may also collapse directly into black holes (BHs). Understanding and predicting their final fate is increasingly important, e.g, in the context of gravitational-wave astronomy. The interior mixing of stars in general and convective boundary mixing remain some of the largest uncertainties in their evolution. Here, we investigate the influence of convective boundary mixing on the pre-SN structure and explosion properties of massive stars. Using the 1D stellar evolution code Mesa, we model single, non-rotating stars of solar metallicity with initial masses of $5-70\mathrm{M_\odot}$ and convective core step-overshooting of $0.05-0.50H_\mathrm{P}$. Stars are evolved until the onset of iron core collapse, and the pre-SN models are exploded using a parametric, semi-analytic SN code. We use the compactness parameter to describe the interior structure of stars at core collapse. Larger convective core overshooting shifts the location of the compactness peak by $1-2\mathrm{M_\odot}$ to higher $M_\mathrm{CO}$. As the luminosity of the pre-SN progenitor is determined by $M_\mathrm{CO}$, we predict BH formation for progenitors with luminosities $5.35<\log(L/\mathrm{L_\odot})<5.50$ and $\log(L/\mathrm{L_\odot})>5.80$. The luminosity range of BH formation agrees well with the observed luminosity of the red supergiant star N6946BH1 that disappeared without a bright SN and likely collapsed into a BH. While some of our models in the luminosity range $\log(L/\mathrm{L_\odot})=5.1-5.5$ indeed collapse to form BHs, this does not fully explain the lack of observed SN~IIP progenitors at these luminosities, ie the missing red-supergiant problem. Convective core overshooting affects the BH masses, the pre-SN location of stars in the Hertzsprung-Russell diagram, the plateau luminosity and duration of SN~IIP lightcurves.[Abridged]

astro-ph.SR↗

arXiv2023

X-Shooting ULLYSES: massive stars at low metallicity. I. Project Description

Observations of individual massive stars, super-luminous supernovae, gamma-ray bursts, and gravitational-wave events involving spectacular black-hole mergers, indicate that the low-metallicity Universe is fundamentally different from our own Galaxy. Many transient phenomena will remain enigmatic until we achieve a firm understanding of the physics and evolution of massive stars at low metallicity (Z). The Hubble Space Telescope has devoted 500 orbits to observe 250 massive stars at low Z in the ultraviolet (UV) with the COS and STIS spectrographs under the ULLYSES program. The complementary ``X-Shooting ULLYSES'' (XShootU) project provides enhanced legacy value with high-quality optical and near-infrared spectra obtained with the wide-wavelength coverage X-shooter spectrograph at ESO's Very Large Telescope. We present an overview of the XShootU project, showing that combining ULLYSES UV and XShootU optical spectra is critical for the uniform determination of stellar parameters such as effective temperature, surface gravity, luminosity, and abundances, as well as wind properties such as mass-loss rates in function of Z. As uncertainties in stellar and wind parameters percolate into many adjacent areas of Astrophysics, the data and modelling of the XShootU project is expected to be a game-changer for our physical understanding of massive stars at low Z. To be able to confidently interpret James Webb Space Telescope (JWST) spectra of the first stellar generations, the individual spectra of low Z stars need to be understood, which is exactly where XShootU can deliver.

astro-ph.SR↗

arXiv2023

Nucleosynthesis of binary-stripped stars

The cosmic origin of the elements, the fundamental chemical building blocks of the Universe, is still uncertain. Binary interactions play a key role in the evolution of many massive stars, yet their impact on chemical yields is poorly understood. Using the MESA stellar evolution code we predict the chemical yields ejected in wind mass loss and the supernovae of single and binary-stripped stars. We do this with a large 162 isotope nuclear network at solar-metallicity. We find that binary-stripped stars are more effective producers of the elements than single stars, due to their increased mass loss and an increased chance to eject their envelopes during a supernova. This increased production by binaries varies across the periodic table, with Fluorine and Potassium being more significantly produced by binary-stripped stars than single stars. We find that the C12/C13 could be used as an indicator of the conservativeness of mass transfer, as C13 is preferentially ejected during mass transfer while C12 is preferentially ejected during wind mass loss. We identify a number of gamma-ray emitting radioactive isotopes that may be used to help constrain progenitor and explosion models of core-collapse supernovae with next-generation gamma-ray detectors. For single stars we find V44 and Mn52 are strong probes of the explosion model, while for binary-stripped stars it is Cr48. Our findings highlight that binary-stripped stars are not equivalent to two single stars and that detailed stellar modelling is needed to predict their final nucleosynthetic yields.

astro-ph.SR↗

arXiv2022

Horizons: Nuclear Astrophysics in the 2020s and Beyond

Nuclear Astrophysics is a field at the intersection of nuclear physics and astrophysics, which seeks to understand the nuclear engines of astronomical objects and the origin of the chemical elements. This white paper summarizes progress and status of the field, the new open questions that have emerged, and the tremendous scientific opportunities that have opened up with major advances in capabilities across an ever growing number of disciplines and subfields that need to be integrated. We take a holistic view of the field discussing the unique challenges and opportunities in nuclear astrophysics in regards to science, diversity, education, and the interdisciplinarity and breadth of the field. Clearly nuclear astrophysics is a dynamic field with a bright future that is entering a new era of discovery opportunities.

nucl-ex↗

arXiv2021

TULIPS: a Tool for Understanding the Lives, Interiors, and Physics of Stars

Understanding the lives and interior structures of stellar objects is a fundamental objective of astrophysics. Research in this domain often relies on the visualization of astrophysical data, for instance, the results of theoretical simulations. However, the diagrams commonly employed to this effect are usually static, complex, and can sometimes be non-intuitive or even counter-intuitive to newcomers in the field. To address some of these issues, this paper introduces TULIPS, a python package that generates novel diagrams and animations of the structure and evolution of stellar objects. TULIPS visualizes the output of one-dimensional physical simulations and is currently optimized for the MESA stellar evolution code. Utilizing the inherent spherical symmetry of such simulations, TULIPS represents the physical properties of stellar objects as the attributes of circles. This enables an intuitive representation of the evolution, energy generation and loss processes, composition, and interior properties of stellar objects, while retaining quantitative information. Users can interact with the output videos and diagrams. The capabilities of TULIPS are showcased by example applications that include a Sun-like star, a massive star, a low-metallicity star, and an accreting white dwarf. Diagrams generated with TULIPS are compared to the Hertzsprung-Russell diagram and to the Kippenhahn diagram, and their advantages and challenges are discussed. TULIPS is open source and free. Aside from being a research tool, it can be used for preparing teaching and public outreach material.

astro-ph.IM↗

arXiv2021

Different to the core: the pre-supernova structures of massive single and binary-stripped stars

The majority of massive stars live in binary or multiple systems and will interact during their lifetimes, which helps to explain the observed diversity of core-collapse supernovae. Donor stars in binary systems can lose most of their hydrogen-rich envelopes through mass transfer, which not only affects the surface properties, but also the core structure. However, most calculations of the core-collapse properties of massive stars rely on single-star models. We present a systematic study of the difference between the pre-supernova structures of single stars and stars of the same initial mass (11 - 21\Msun) that have been stripped due to stable post-main sequence mass transfer at solar metallicity. We present the pre-supernova core composition with novel diagrams that give an intuitive representation of the isotope distribution. As shown in previous studies, at the edge of the carbon-oxygen core, the binary-stripped star models contain an extended gradient of carbon, oxygen, and neon. This layer originates from the receding of the convective helium core during core helium burning in binary-stripped stars, which does not occur in single-star models. We find that this same evolutionary phase leads to systematic differences in the final density and nuclear energy generation profiles. Binary-stripped star models have systematically higher total masses of carbon at the moment of core collapse compared to single star models, which likely results in systematically different supernova yields. In about half of our models, the silicon-burning and oxygen-rich layers merge after core silicon burning. We discuss the implications of our findings for the explodability, supernova observations, and nucleosynthesis from these stars. Our models will be publicly available and can be readily used as input for supernova simulations. [Abridged]

astro-ph.SR↗

arXiv2021

The cosmic carbon footprint of massive stars stripped in binary systems

The cosmic origin of carbon, a fundamental building block of life, is still uncertain. Yield predictions for massive stars are almost exclusively based on single star models, even though a large fraction interact with a binary companion. Using the MESA stellar evolution code, we predict the carbon ejected in the winds and supernovae of single and binary-stripped stars at solar metallicity. We find that binary-stripped stars are twice as efficient at producing carbon (1.5-2.6 times, depending on choices on the slope of the initial mass function and black hole formation). We confirm that this is because the convective helium core recedes in stars that have lost their hydrogen envelope, as noted previously. The shrinking of the core disconnects the outermost carbon-rich layers created during the early phase of helium burning from the more central burning regions. The same effect prevents carbon destruction, even when the supernova shock wave passes. The yields are sensitive to the treatment of mixing at convective boundaries, specifically during carbon-shell burning (variations up to 40%) and improving upon this should be a central priority for more reliable yield predictions. The yields are robust (variations less than 0.5%) across our range of explosion assumptions. Black hole formation assumptions are also important, implying that the stellar graveyard now explored by gravitational-wave detections may yield clues to better understand the cosmic carbon production. Our findings also highlight the importance of accounting for binary-stripped stars in chemical yield predictions and motivates further studies of other products of binary interactions.

astro-ph.SR↗