Aluminium-26 is a short-lived radionuclide with a half-life of 0.72Myr, which is observed today in the Galaxy via gamma-ray spectroscopy and is inferred to have been present in the early Solar System via analysis of meteorites. Massive stars are considered the main contributors of Al26. Although most massive stars are found in binary systems, the effect, however, of binary interactions on the Al26 yields have not been investigated since Braun & Langer (1995). Here we aim to fill this gap. We have used the MESA stellar evolution code to compute massive (10Msun<=M<=80Msun), non-rotating, single and binary stars of solar metallicity (Z=0.014). We computed the wind yields for the single stars and for the binary systems where mass transfer plays a major role. Depending on the initial mass of the primary star and orbital period, the Al26 yield can either increase or decrease in a binary system. For binary systems with primary masses up to ~35-40Msun, the yield can increase significantly, especially at the lower mass-end, while above ~45Msun the yield becomes similar to the single star yield or even decreases. Our preliminary results show that compared to supernova explosions, the contribution of mass-loss in binary systems to the total Al26 abundance produced by a stellar population is minor. On the other hand, if massive star mass-loss is the origin of Al26 in the early Solar System, our results will have significant implications for the identification of the potential stellar, or stellar population, source.
Radioactive nuclei were present in the early Solar System, as inferred from analysis of meteorites. Many are produced in massive stars, either during their lives or their final explosions. In the first paper in this series (Brinkman et al. 2019), we focused on the production of $^{26}$Al in massive binaries. Here, we focus on the production of another two short-lived radioactive nuclei, $^{36}$Cl and $^{41}$Ca, and the comparison to the early Solar System data. We used the MESA stellar evolution code with an extended nuclear network and computed massive (10-80 M$ _{\odot} $), rotating (with in…
Discovery of the most rapidly-rotating, non-degenerate, magnetic massive star by the MiMeS collaboration
我们讨论了最近检测到的一个强大的，有组织的磁场在明亮的，宽线B2V星，HD 142184，使用ESPaDONS分光偏振仪CFHT的大质量恒星（MiMeS）调查的磁性的一部分。我们发现它的自转周期为0.50833天，这使它成为迄今为止发现的自转最快的非简并磁星。像之前的快速旋转记录保持者HR 7355（也是由MiMeS发现的：Oksala et al. 2010，Rivinius et al. 2010）一样，这颗恒星的发射线变化是结构化磁层的诊断。
Both rotation and interactions with binary companions can significantly affect massive star evolution, altering interior and surface abundances, mass loss rates and mechanisms, observed temperatures and luminosities, and their ultimate core-collapse fates. The Geneva and BPASS stellar evolution codes include detailed treatments of rotation and binary evolutionary effects, respectively, and can illustrate the impact of these phenomena on massive stars and stellar populations. However, a direct comparison of these two widely-used codes is vital if we hope to use their predictions for interpretin…
The transport of angular momentum for massive stars I. Formation of slowly rotating WNE stars
Yunnan Observatories, Chinese Academy of Sciences（中国科学院云南天文台）；University of Chinese Academy of Sciences（中国科学院大学）；Key Laboratory for Structure and Evolution of Celestial Objects, Chinese Academy of Sciences（中国科学院天体结构与演化重点实验室）；International Centre of Supernovae, Yunnan Key Laboratory（国际超新星中心云南省重点实验室）；Center for Astronomical Mega-Science, Chinese Academy of Sciences（中国科学院天文大科学研究中心）
The study of the long-dead early generations of massive stars is crucial in order to obtain a complete picture of the chemical evolution of the Universe, hence the origin of the elements. The nature of these stars can be inferred indirectly by investigating the origin of low-mass metal-poor stars observed in our Galaxy, some of which are almost as old as the Universe. The peculiar extremely iron-poor Carbon-Enhanced Metal-Poor (CEMP) stars, whose precise origin is still debated, are thought to have formed with the material ejected by only one or very few previous massive stars. The main aim of…
The first massive stars triggered the onset of chemical evolution by releasing the first metals (elements heavier than helium) in the Universe. The nature of these stars and how the early chemical enrichment took place is still largely unknown. Rotational-induced mixing in the stellar interior can impact the nucleosynthesis during the stellar life of massive stars and lead to stellar ejecta having various chemical compositions. We present low and zero-metallicity 20, 25 and 40 $M_{\odot}$ stellar models with various initial rotation rates and assumptions for the nuclear reactions rates. With i…
Recent studies show that rotation significantly affects the s-process in massive stars. We provide tables of yields for non-rotating and rotating massive stars between 10 and 150 $M_{\odot}$ at $Z=10^{-3}$ ([Fe/H] $=-1.8$). Tables for different mass cuts are provided. The complete s-process is followed during the whole evolution with a network of 737 isotopes, from Hydrogen to Polonium. A grid of stellar models with initial masses of 10, 15, 20, 25, 40, 60, 85, 120 and 150 $M_{\odot}$ and with an initial rotation rate of both 0 or 40$~\%$ of the critical velocity was computed. Three extra mode…
We report a new mechanism for the \textsl{s} in rotating massive metal-poor stars. Our models show that above a critical rotation speed, such stars evolve in a quasi-chemically-homogeneous fashion, which gives rise to a prolific \textsl{s}-process. Rotation-induced mixing results in primary production of $^{13}$C, which subsequently makes neutrons via $^{13}\mathrm{C}(α,\mathrm{n})^{16}\mathrm{O}$ during core He burning. Neutron capture can last up to $\sim 10^{13}\,\mathrm{s}$ ($\sim 3\times 10^{5}$~yr) with the peak central neutron density ranging from $\sim10^7$ to $10^{8}\,\mathrm{cm}^{-3}…
Fast-spinning massive black holes from slowly rotating low-metallicity stars: Implications for GW231123
University of Malaya（马来亚大学）；Universiti Malaya（马来亚大学）；Keele University（基尔大学）；University of Tokyo（东京大学）；Universitat de València（瓦伦西亚大学）；University of Geneva（日内瓦大学）
Recent large-scale spectropolarimetric surveys have established that a small but significant percentage of massive stars host stable, surface dipolar magnetic fields with strengths on the order of kG. These fields channel the dense, radiatively driven stellar wind into circumstellar magnetospheres, whose density and velocity structure can be probed using ultraviolet (UV) spectroscopy of wind-sensitive resonance lines. Coupled with appropriate magnetosphere models, UV spectroscopy provides a valuable way to investigate the wind-field interaction, and can yield quantitative estimates of the wind…
Stellar evolution models predict that internal mixing should cause some sodium overabundance at the surface of red giants more massive than ~ 1.5--2.0 Msun. The surface aluminium abundance should not be affected. Nevertheless, observational results disagree about the presence and/or the degree of the Na and Al overabundances. In addition, Galactic chemical evolution models adopting different stellar yields lead to quite different predictions for the behavior of [Na/Fe] and [Al/Fe] versus [Fe/H]. Overall, the observed trends of these abundances with metallicity are not well reproduced. We readd…
In massive stars, rotation and oscillatory waves can have a tight interplay. In order to assess the importance of additional angular momentum transport mechanisms other than rotation, we compare the asteroseismic properties of a uniformly rotating model and a differentially rotating one. Accordingly, we employ the observed period spacing of 36 dipole g-modes in the Kepler $\sim3.2$ M$_\odot$ target KIC 7760680 to discriminate between these two models. We favor the uniformly rotating model, which fully satisfies all observational constraints. Therefore, efficient angular momentum transport by a…
Large-scale variability in macroturbulence driven by pulsations in the rapidly rotating massive star Zeta Oph from high-cadence ESPRESSO spectroscopy and TESS photometry
Slowly rotating magnetic massive stars develop "dynamical magnetospheres" (DM's), characterized by trapping of stellar wind outflow in closed magnetic loops, shock heating from collision of the upflow from opposite loop footpoints, and subsequent gravitational infall of radiatively cooled material. In 2D and 3D magnetohydrodynamic (MHD) simulations the interplay among these three components is spatially complex and temporally variable, making it difficult to derive observational signatures and discern their overall scaling trends.Within a simplified, steady-state analysis based on overall cons…
Aims: Recent observations have challenged our understanding of rotational mixing in massive stars by revealing a population of fast-rotating objects with apparently normal surface nitrogen abundances. However, several questions have arisen because of a number of issues, which have rendered a reinvestigation necessary; these issues include the presence of numerous upper limits for the nitrogen abundance, unknown multiplicity status, and a mix of stars with different physical properties, such as their mass and evolutionary state, which are known to control the amount of rotational mixing. Method…
Most radiatively-driven massive star winds can be modelled with m-CAK theory resulting in so called fast solution. However, those most rapidly rotating among them, especially when the stellar rotational speed is higher than $\sim 75\%$ of the critical rotational speed, can adopt a different solution called $Ω$-slow solution characterized by a dense and slow wind. Here, in this work we study the transition region of the solutions where the fast solution changes to the $Ω$-slow. Using both time-steady and time-dependent numerical codes, we study this transition region for different equatorial mo…
Zonal and meridional axisymmetric flows can deeply impact the rotational and chemical evolution of stars. Therefore, momentum exchanges between waves propagating in stars, differential rotation, and meridional circulation must be carefully evaluated. In this work, we study axisymmetric mean flows in rapidly and initially uniformly rotating massive stars driven by small amplitude non-axisymmetric $κ$-driven oscillations. We treat them as perturbations of second-order of the oscillation amplitudes and derive their governing equations as a set of coupled linear ordinary differential equations. Th…
The VLT-FLAMES survey of massive stars: constraints on stellar evolution from the chemical compositions of rapidly rotating Galactic and Magellanic Cloud B-type stars
Aims: Past observations of fast-rotating massive stars exhibiting normal nitrogen abundances at their surface have raised questions about the rotational mixing paradigm. We revisit this question thanks to a spectroscopic analysis of a sample of bright fast-rotating OB stars, with the goal of quantifying the efficiency of rotational mixing at high rotation rates. Method: Our sample consists of 40 fast rotators on the main sequence, with spectral types comprised between B0.5 and O4. We compare the abundances of some key element indicators of mixing (He, CNO) with the predictions of evolutionary …
Spectroscopic studies of Galactic O and B stars show that many stars with masses above 8 M$_{\odot}$ are observed in the HR diagram just beyond the Main-Sequence (MS) band predicted by stellar models computed with a moderate overshooting. This may be an indication that the convective core sizes in stars in the upper part of the HR diagram are larger than predicted by these models. Combining stellar evolution models and spectroscopic parameters derived for a large sample of Galactic O and B stars, including brand new information about their projected rotational velocities, we reexamine the ques…
We investigate the integrated properties of massive (>10 Msun), rotating, single-star stellar populations for a variety of initial rotation rates (v/vcrit=0.0, 0.2, 0.4, 0.5, and 0.6). We couple the new MESA Isochrone and Stellar Tracks (MIST) models to the Flexible Stellar Population Synthesis (FSPS) package, extending the stellar population synthesis models to include the contributions from very massive stars (>100 Msun), which can be significant in the first ~4 Myr after a starburst. These models predict ionizing luminosities that are consistent with recent observations of young nuclear sta…
We investigate the effects of the core-collapse supernova ejecta on a rapidly rotating and massive companion star. We show that the stripped mass raises by twice when compare with a massive but non-rotating companion star. In close binaries with orbital periods of about 1 day, the stripped masses reach up to $\sim 1 M_\odot$. By simulating the evolutions of the rotational velocities of the massive companion stars based on different stripped masses, we find that the rotational velocity decreases greatly for stripped mass that is higher than about $1 M_\odot$. Of all the known high mass X-ray bi…
We present a chemical abundance analysis of a metal-poor star, ROA 276, in the stellar system omega Centauri. We confirm that this star has an unusually high [Sr/Ba] abundance ratio. Additionally, ROA 276 exhibits remarkably high abundance ratios, [X/Fe], for all elements from Cu to Mo along with normal abundance ratios for the elements from Ba to Pb. The chemical abundance pattern of ROA 276, relative to a primordial omega Cen star ROA 46, is best fit by a fast-rotating low-metallicity massive stellar model of 20 Msun, [Fe/H] = -1.8, and an initial rotation 0.4 times the critical value; no ot…
The decomposition of the Solar system abundances of heavy isotopes into their s- and r- components plays a key role in our understanding of the corresponding nuclear processes and the physics and evolution of their astrophysical sites. We present a new method for determining the s- and r- components of the Solar system abundances, fully consistent with our current understanding of stellar nucleosynthesis and galactic chemical evolution. The method is based on a study of the evolution of the solar neighborhood with a state-of-the-art 1-zone model, using recent yields of low and intermediate mas…
There is solid observational evidence on the existence of massive, $M\sim 1~M_\odot$, highly magnetized white dwarfs (WDs) with surface magnetic fields up to $B\sim 10^9$ G. We show that, if in addition to these features, the star is fast rotating, it can become a rotation-powered pulsar-like WD and emit detectable high-energy radiation. We infer the values of the structure parameters (mass, radius, moment of inertia), magnetic field, rotation period and spin-down rates of a WD pulsar death-line. We show that WDs above the death-line emit blackbody radiation in the soft X-ray band via the magn…
In this work, we study the properties and structure of a massive and rapidly rotating protoneutron star (PNS) with hyperon content. We follow several stages of quasi-stationary evolution in an approximate way at four discrete steps. We use a density-dependent (DD) relativistic mean field theory (RMF) model and calculate different quantities such as mass, equatorial radius, moment of inertia, and quadrupole moment to get different rotating configurations upto the mass-shedding limit. We study the effect of the appearance of $Λ$, the lightest of all hyperons, on each of the evolutionary stages o…
We perform for the first time a 3D hydrodynamics simulation of the evolution of the last minutes pre-collapse of the oxygen shell of a fast-rotating massive star. This star has an initial mass of 38 M$_\odot$, a metallicity of $\sim$1/50 Z$_\odot$, an initial rotational velocity of 600 km s$^{-1}$, and experiences chemically homogeneous evolution. It has a silicon- and oxygen-rich (Si/O) convective layer at (4.7-17)$\times 10^{8}$ cm, where oxygen-shell burning takes place. The power spectrum analysis of the turbulent velocity indicates the dominance of the large-scale mode ($\ell \sim 3$), wh…
We have performed 3D isothermal MHD simulation of a magnetic rotating massive star with a non-zero dipole obliquity and predicted the radio/sub-mm observable lightcurves and continuum spectra for a frequency range compatible with ALMA. From these results we also compare the model input mass-loss to that calculated from the synthetic thermal emission. Spherical and cylindrical symmetry is broken due to the obliquity of the stellar magnetic dipole resulting in an inclination and phase dependence of both the spectral flux and inferred mass-loss rate, providing testable predictions of variability …
We present a new grid of presupernova models of massive stars extending in mass between 13 and 120 Msun, covering four metallicities (i.e. [Fe/H]=0, -1, -2 and -3) and three initial rotation velocities (i.e. 0, 150 and 300 km/s). The explosion has been simulated following three different assumptions in order to show how the yields depend on the remnant mass - initial mass relation. An extended network from H to Bi is fully coupled to the physical evolution of the models. The main results can be summarized as follows. a) At solar metallicity the maximum mass exploding as Red Super Giant (RSG) i…
The s-process in massive stars, producing nuclei up to $A\approx 90$, has a different behaviour at low metallicity if stellar rotation is significant. This enhanced s-process is distinct from the s-process in massive stars around solar metallicity, and details of the nucleosynthesis are poorly known. We investigated nuclear physics uncertainties in the enhanced s-process in metal-poor stars within a Monte-Carlo framework. We applied temperature-dependent uncertainties of reaction rates, distinguishing contributions from the ground state and from excited states. We found that the final abundanc…
Context. We have recently investigated the origin of chemical signatures observed in Galactic halo stars by means of a stochastic chemical evolution model. We have found that rotating massive stars are a promising way to explain several signatures observed in these fossil stars. Aims. In the present paper we discuss how the extremely metal-poor halo star TYC 8442-1036-1, for which we have now obtained detailed abundances from VLT-UVES spectra, fits into the framework of our previous work. Methods. We apply a standard 1D LTE analysis to the spectrum of this star. We measure the abundances of 14…
We discuss the influence of rotation on the combined synthesis of Ti44 and Ni56 in massive stars. While Ni56 is significantly produced by both the complete and incomplete explosive Si burning, Ti44 is mainly produced by the complete explosive Si burning, with a minor contribution (in standard non rotating models) from the incomplete explosive Si burning and the O burning (both explosive and hydrostatic). We find that, in most cases, the thickness of the region exposed to the incomplete explosive Si burning increases in rotating models (v_ini=300 km/s) and since Ni56 is significantly produced i…
WD J005311 is a newly identified white dwarf (WD) in a mid-infrared nebula. The spectroscopic observation indicates the existence of a neon-enriched carbon/oxygen wind with a terminal velocity of $v_{\infty,\rm obs}\sim 16,000\,\rm km\,s^{-1}$ and a mass loss rate of $\dot M_{\rm obs}\sim 3.5\times 10^{-6}\,M_\odot$ yr$^{-1}$. Here we consistently explain the properties of WD J005311 using a newly constructed wind solution, where the optically thick outflow is launched from the carbon burning shell on an oxygen-neon core and accelerated by the rotating magnetic field to become supersonic and u…
Most neutron capture elements have a double production by r- and s-processes, but the question of production sites is complex and still open. Recent studies show that including stellar rotation can have a deep impact on nucleosynthesis. We studied the evolution of Sr and Ba in the Milky Way. A chemical evolution model was employed to reproduce the Galactic enrichment. We tested two different nucleosynthesis prescriptions for s-process in massive stars, adopted from the Geneva group and the Rome group. Rotation was taken into account, studying the effects of stars without rotation or rotating w…
Long-duration gamma-ray bursts (lGRBs) originate in relativistic collimated outflows -- jets -- that drill their way out of collapsing massive stars. Accurately modeling this process requires realistic stellar profiles for the jets to propagate through and break out of. Most previous studies have used simple power laws or pre-collapse models for massive stars. However, the relevant stellar profile for lGRB models is in fact that of a star after its core has collapsed to form a compact object. To self-consistently compute such a stellar profile, we use the open-source code GR1D to simulate the …
The Phoenix stellar stream has a low intrinsic dispersion in velocity and metallicity that implies the progenitor was probably a low mass globular cluster. In this work we use Magellan/MIKE high-dispersion spectroscopy of eight Phoenix stream red giants to confirm this scenario. In particular, we find negligible intrinsic scatter in metallicity ($σ(\mathrm{[Fe~II/H]}) = 0.04^{+0.11}_{-0.03}$) and a large peak-to-peak range in [Na/Fe] and [Al/Fe] abundance ratios, consistent with the light element abundance patterns seen in the most metal-poor globular clusters. However, unlike any other globul…
