Ejecta Of Core-collapse Supernovae Research Articles

The universal variability of the stellar initial mass function probed by the TIMER survey

The debate about the universality of the stellar initial mass function (IMF) revolves around two competing lines of evidence. While measurements in the Milky Way, an archetypal spiral galaxy, seem to support an invariant IMF, the observed properties of massive early-type galaxies (ETGs) favor an IMF somehow sensitive to the local star-formation conditions. However, the fundamental methodological and physical differences between the two approaches have hampered a comprehensive understanding of IMF variations. Here, we describe an improved modeling scheme that, for the first time, allows consistent IMF measurements across stellar populations with different ages and complex star-formation histories (SFHs). Making use of the exquisite MUSE optical data from the TIMER survey and powered by the MILES stellar population models, we show the age, metallicity Mg/Fe and IMF slope maps of the inner regions of NGC\,3351, a spiral galaxy with a mass similar to that of the Milky Way. The measured IMF values in NGC\,3351 follow the expectations from a Milky Way-like IMF, although they simultaneously show systematic and spatially coherent variations, particularly for low-mass stars. In addition, our stellar population analysis reveals the presence of metal-poor and Mg-enhanced star-forming regions that appear to be predominantly enriched by the stellar ejecta of core-collapse supernovae. Our findings therefore showcase the potential of detailed studies of young stellar populations to provide the means to better understand the early stages of galaxy evolution and, in particular, the origin of the observed IMF variations beyond and within the Milky Way.

Dust survival rates in clumps passing through the Cas A reverse shock – II. The impact of magnetic fields

ABSTRACTDust grains form in the clumpy ejecta of core-collapse supernovae where they are subject to the reverse shock, which is able to disrupt the clumps and destroy the grains. Important dust destruction processes include thermal and kinetic sputtering as well as fragmentation and grain vaporization. In the present study, we focus on the effect of magnetic fields on the destruction processes. We have performed magnetohydrodynamical simulations using AstroBEAR to model a shock wave interacting with an ejecta clump. The dust transport and destruction fractions are computed using our post-processing code Paperboats, in which the acceleration of grains due to the magnetic field and a procedure that allows partial grain vaporization have been newly implemented. For the oxygen-rich supernova remnant Cassiopeia A, we found a significantly lower dust survival rate when magnetic fields are aligned perpendicular to the shock direction compared to the non-magnetic case. For a parallel field alignment, the destruction is also enhanced but at a lower level. The survival fractions depend sensitively on the gas density contrast between the clump and the ambient medium and on the grain sizes. For a low-density contrast of 100, e.g. 5 nm silicate grains are completely destroyed while the survival fraction of $1\,\mu{\rm m}$ grains is 86 per cent. For a high-density contrast of 1000, 95 per cent of the 5 nm grains survive while the survival fraction of $1\,\mu{\rm m}$ grains is 26 per cent. Alternative clump sizes or dust materials (carbon) have non-negligible effects on the survival rate but have a lower impact compared to density contrast, magnetic field strength, and grain size.

Evidence for Enrichment of Niobium-92 in the Outer Protosolar Disk

The short-lived radionuclide, niobium-92 (92Nb), has been used to estimate the site of nucleosynthesis for p-nuclei and the timing of planetary differentiation, assuming that it was uniformly distributed in the early solar system. Here, we present the internal niobium–zirconium (Nb–Zr) isochron dating of Northwest Africa (NWA) 6704, an achondrite thought to form in the outer protosolar disk due to nucleosynthetic isotope similarities with carbonaceous chondrites. The isochron defines an initial 92Nb/93Nb ratio of (2.72 ± 0.25) × 10−5 at the NWA 6704 formation, 4562.76 ± 0.30 million years ago. This corresponds to a 92Nb/93Nb ratio of (2.96 ± 0.27) × 10−5 at the time of solar system formation, which is ∼80% higher than the values obtained from meteorites formed in the inner disk. The results suggest that a significant proportion of the solar 92Nb was produced by a nearby core-collapse supernova (CCSN) and that the outer disk was more enriched in CCSN ejecta, which could account for the heterogeneity of short-lived 26Al and nucleosynthetic stable-isotope anomalies across the disk. We propose that NWA 6704 serves as the best anchor for mapping relative Nb–Zr ages of objects in the outer solar system onto the absolute timescale.

Isotopic ratios for C, N, Si, Al, and Ti in C-rich presolar grains from massive stars

ABSTRACT Certain types of silicon carbide (SiC) grains, e.g. SiC-X grains, and low density (LD) graphites are C-rich presolar grains that are thought to have condensed in the ejecta of core-collapse supernovae (CCSNe). In this work, we compare C, N, Al, Si, and Ti isotopic abundances measured in presolar grains with the predictions of 21 CCSN models. The impact of a range of SN explosion energies is considered, with the high energy models favouring the formation of a C/Si zone enriched in 12C, 28Si, and 44Ti. Eighteen of the 21 models have H ingested into the He-shell and different abundances of H remaining from such H-ingestion. CCSN models with intermediate to low energy (that do not develop a C/Si zone) cannot reproduce the 28Si and 44Ti isotopic abundances in grains without assuming mixing with O-rich CCSN ejecta. The most 28Si-rich grains are reproduced by energetic models when material from the C/Si zone is mixed with surrounding C-rich material, and the observed trends of the 44Ti/48Ti and 49Ti/48Ti ratios are consistent with the C-rich C/Si zone. For the models with H-ingestion, high and intermediate explosion energies allow the production of enough 26Al to reproduce the 26Al/27Al measurements of most SiC-X and LD graphites. In both cases, the highest 26Al/27Al ratio is obtained with H still present at XH ≈ 0.0024 in He-shell material when the SN shock is passing. The existence of H in the former convective He-shell points to late H-ingestion events in the last days before massive stars explode as a supernova.

Feeding post-core collapse supernova explosion jets with an inflated main sequence companion

ABSTRACT We simulate the response of a main sequence star to the explosion of a stripped-envelope (type Ib or Ic) core-collapse supernova (CCSN) when the main sequence star orbits the core at a distance of $10 \, \mathrm{R}_\odot$ or $20 \, \mathrm{R}_\odot$ at explosion. We use the stellar evolution code mesa to follow the response of main sequence stars of masses $3 \, \mathrm{M}_\odot$ and $7\, \mathrm{M}_\odot$ to energy deposition and mass removal. The collision of the CCSN ejecta with the main sequence star deposits energy and inflate the main sequence star. If the binary system stays bound after the CCSN explosion, the inflated main sequence star might engulf the newly born neutron star (NS). We assume that the NS accretes mass through an accretion disc and launches jets. The jets remove mass from the inflated main sequence star and collide with the CCSN ejecta. Although this scenario is rare, it adds up to other rare scenarios to further support the notion that many stripped envelope CCSNe are powered by late jets. The late jets can power these CCSNe-I for a long time and might power bumps in their light curve. The jets might also shape the inner ejecta to a bipolar morphology. Our results further support suggestions that there are several ways to feed an NS (or a black hole) to launch the late jets in superluminous supernovae.

Postexplosion Positive Jet-feedback Activity in Inner Ejecta of Core Collapse Supernovae

We conduct three-dimensional hydrodynamical simulations of weak jets that we launch into a core collapse supernova (CCSN) ejecta half an hour after the explosion and find that the interaction of the fast jets with the CCSN ejecta creates high-pressure zones that induce a backflow that results in mass accretion onto the newly born neutron star. In cases of weak jets, with a total power of ≈1045–1046 erg, the backflow mass accretion might power them up to more energetic jets by an order of magnitude. In total, the jets of the two postexplosion jet-launching episodes have enough energy to influence the morphology of the very inner ejecta, with a mass of ≈0.1 M ⊙. Our results imply that in some, probably a minority of, CCSN remnants the very inner regions might display a bipolar structure that results from postexplosion weak jets. The regions outside this part might display the morphology of jittering jets.

Imprints of the Jittering Jets Explosion Mechanism in the Morphology of the Supernova Remnant SNR 0540-69.3

I identify a point-symmetric structure in recently published VLT/MUSE velocity maps of different elements in a plane along the line of sight at the center of the supernova remnant SNR 0540-69.3, and argue that jittering jets that exploded this core collapse supernova shaped this point-symmetric structure. The four pairs of two opposite clumps that compose this point symmetric structure suggest that two to four pairs of jittering jets shaped the inner ejecta in this plane. In addition, intensity images of several spectral lines reveal a faint strip (the main jet-axis) that is part of this plane of jittering jets and its similarity to morphological features in a few other SNRs and in some planetary nebulae further suggests shaping by jets. My interpretation implies that in addition to instabilities, jets also mix elements in the ejecta of core collapse supernovae. Based on the point-symmetric structure and under the assumption that jittering jets exploded this supernova, I estimate the component of the neutron star natal kick velocity on the plane of the sky to be ≃ 235 km s−1, and at an angle of ≃47° to the direction of the main jet-axis. I analyze this natal kick direction together with 12 other SNRs in the frame of the jittering jets explosion mechanism.

Heavy element contributions of rotating massive stars to interstellar medium

Employing the stellar evolution code Modules for Experiments in Stellar Astrophysics (MESA), we calculate yields of heavy elements from massive stars via stellar wind and core−collapse supernova (CCSN) ejecta to the interstellar medium (ISM). In our models, the initial masses (M ini) of massive stars are taken from 13 to 80 M ⊙, their initial rotational velocities (V) are 0, 300 and 500 km s−1, and their metallicities are [Fe/H] = –3, –2, –1 and 0. The yields of heavy elements coming from stellar winds are mainly affected by stellar rotation which changes the chemical abundances of stellar surfaces via chemically homogeneous evolution, and enhances mass-loss rate. We estimate that the stellar wind can produce heavy element yields of about 10−2 (for low metallicity models) to a mass of several M ⊙ (for low metallicity and rapid rotation models). The yields of heavy elements produced by CCSN ejecta also depend on the large amount of remnant mass which is mainly determined by the mass of the CO-core. Our models calculate that the yields of heavy elements produced by CCSN ejecta can get up to several M ⊙. Compared with stellar wind, CCSN ejecta has a greater contribution to the heavy elements in ISM. We also compare the 56Ni yields calculated in this work with the observational estimate. Our models only explain the 56Ni masses produced by faint SNe or normal SNe with progenitor mass lower than about 25 M ⊙, and greatly underestimate the 56Ni masses produced by stars with masses higher than about 30 M ⊙.

A nearby galaxy perspective on dust evolution

Context. The efficiency of the different processes responsible for the evolution of interstellar dust on the scale of a galaxy are, to date, very uncertain, spanning several orders of magnitude in the literature. Yet, precise knowledge of the grain properties is key to addressing numerous open questions about the physics of the interstellar medium and galaxy evolution. Aims. This article presents an empirical statistical study, aimed at quantifying the timescales of the main cosmic dust evolution processes as a function of the global properties of a galaxy. Methods. We modeled a sample of ≃800 nearby galaxies, spanning a wide range of metallicities, gas fractions, specific star formation rates, and Hubble stages. We derived the dust properties of each object from its spectral energy distribution. Through an additional level of analysis, we inferred the timescales of dust condensation in core-collapse supernova ejecta, grain growth in cold clouds, and dust destruction by shock waves. Throughout this paper, we have adopted a hierarchical Bayesian approach, resulting in a single large probability distribution of all the parameters of all the galaxies, to ensure the most rigorous interpretation of our data. Results. We confirm the drastic evolution with metallicity of the dust-to-metal mass ratio (by two orders of magnitude), found by previous studies. We show that dust production by core-collapse supernovae is efficient only at very low metallicity, a single supernova producing on average less than ≃0.03 M⊙/SN of dust. Our data indicate that grain growth is the dominant formation mechanism at metallicity above ≃1/5 solar, with a grain growth timescale shorter than ≃50 Myr at solar metallicity. Shock destruction is relatively efficient, a single supernova clearing dust on average in at least ≃1200 M⊙/SN of gas. These results are robust when assuming different stellar initial mass functions. In addition, we show that early-type galaxies are outliers in several scaling relations. This feature could result from grain thermal sputtering in hot X-ray emitting gas, which is a hypothesis supported by a negative correlation between the dust-to-stellar mass ratio and the X-ray photon rate per grain. Finally, we confirm the well-known evolution of the aromatic-feature-emitting grain mass fraction as a function of metallicity and interstellar radiation field intensity. Our data indicate that the relation with metallicity is significantly stronger. Conclusions. Our results provide valuable constraints for simulations of galaxies. They imply that grain growth is the likely dust production mechanism in dusty high-redshift objects. We also emphasize the determinant role of local, low metallicity systems in order to address these questions.

Simulating the inflation of bubbles by late jets in core collapse supernova ejecta

ABSTRACT We conducted 3D hydrodynamical simulations to study the interaction of two late opposite jets with the ejecta of a core collapse supernova (CCSN), and study the bipolar structure that results from this interaction as the jets inflate hot-low-density bubbles. The newly born central object, a neutron star (NS; or a black hole), launches these jets at about 50 to 100 d after explosion. The bubbles cross the photosphere in the polar directions at much earlier times than the regions at the same radii near the equatorial plane. The hot bubbles releases more radiation and the photosphere recedes more rapidly in the tenuous bubble. Our results strengthen earlier claims that were based on toy models that such an interaction might lead to a late peak in the light curve, and that an equatorial observer might see a rapid drop in the light curve. Our results might have implications to much earlier jets that explode the star, either jets that the newly born NS launches in a CCSN, or jets that an NS companion that merges with the core of a massive star launches in a common envelope jets supernova (CEJSN) event. Our results add indirect support to the CEJSN scenario for fast blue optical transients, e.g. AT2018cow, ZTF18abvkwla, and CSS161010.

Low-energy core-collapse supernovae in the frame of the jittering jets explosion mechanism

ABSTRACT We relate the pre-explosion binding energy of the ejecta of core-collapse supernovae (CCSNe) of stars with masses in the lower range of CCSNe and the location of the convection zones in the pre-collapse core of these stars, to explosion properties in the frame of the jittering jets explosion mechanism. Our main conclusion is that in the frame of the jittering jets explosion mechanism the remnant of a pulsar in these low-energy CCSNe has some significance, in that the launching of jets by the newly born neutron star (NS) spins-up the NS and create a pulsar. We crudely estimated the period of the pulsars to be tens of milliseconds in these cases. The convective zones seed perturbations that lead to accretion of stochastic angular momentum that in turn is assumed to launch jittering jets in this explosion mechanism. We calculate the binding energy and the location of the convective zones with the stellar evolution code mesa. For the lowest stellar masses, we study, MZAMS ≃ 8.5–11 M⊙, the binding energy above the convective zones is low, and so is the expected explosion energy in the jittering jets explosion mechanism that works in a negative feedback cycle. The expected mass of the NS remnant is MNS ≈ 1.25–1.6 M⊙, even for these low-energy CCSNe.

Dust survival rates in clumps passing through the Cas A reverse shock – I. Results for a range of clump densities

ABSTRACT The reverse shock in the ejecta of core-collapse supernovae is potentially able to destroy newly formed dust material. In order to determine dust survival rates, we have performed a set of hydrodynamic simulations using the grid-based code astrobear in order to model a shock wave interacting with clumpy supernova ejecta. Dust motions and destruction rates were computed using our newly developed external, post-processing code paperboats, which includes gas drag, grain charging, sputtering, and grain–grain collisions. We have determined dust destruction rates for the oxygen-rich supernova remnant Cassiopeia A as a function of initial grain sizes and clump gas density. We found that up to $30\,\mathrm{{{\ \rm per\ cent}}}$ of the carbon dust mass is able to survive the passage of the reverse shock if the initial grain size distribution is narrow with radii around ∼10–50 nm for high gas densities, or with radii around $\sim 0.5\!-\!1.5\,\mathrm{\mu m}$ for low and medium gas densities. Silicate grains with initial radii around 10–30 nm show survival rates of up to $40\,\mathrm{{{\ \rm per\ cent}}}$ for medium- and high-density contrasts, while silicate material with micron-sized distributions is mostly destroyed. For both materials, the surviving dust mass is rearranged into a new size distribution that can be approximated by two components: a power-law distribution of small grains and a lognormal distribution of grains having the same size range as the initial distribution. Our results show that grain–grain collisions and sputtering are synergistic and that grain–grain collisions can play a crucial role in determining the surviving dust budget in supernova remnants.

Impact of clumping on core-collapse supernova radiation

There is both observational and theoretical evidence that the ejecta of core-collapse supernovae (SNe) are structured. Rather than being smooth and homogeneous, the material is made of over-dense and under-dense regions of distinct composition. Here, we have explored the effect of clumping on the SN radiation during the photospheric phase using 1D non-local thermodynamic equilibrium radiative transfer and an ejecta model arising from a blue-supergiant explosion (yielding a Type II-peculiar SN). Neglecting chemical segregation, we adopted a velocity-dependent volume-filling factor approach that assumes that the clumps are small but does not change the column density along any sightline. We find that clumping boosts the recombination rate in the photospheric layers, leading to a faster recession of the photosphere, an increase in bolometric luminosity, and a reddening of the SN colors through enhanced blanketing. The SN bolometric light curve peaks earlier and transitions faster to the nebular phase. On the rise to maximum, the strongest luminosity contrast between our clumped and smooth models is obtained at the epoch when the photosphere has receded to ejecta layers where the clumping factor is only 0.5 – this clumping factor may be larger in nature. Clumping is seen to have a similar influence in a Type II-Plateau SN model. As we neglected both porosity and chemical segregation, our models underestimate the true impact of clumping. These results warrant further study of the influence of clumping on the observables of other SN types during the photospheric phase.

Can Dust Injected by SNe Explain the NIR–MIR Excess in Young Massive Stellar Clusters?

Abstract We present a physically motivated model involving the different processes affecting supernova dust grains as they are incorporated into the thermalized medium within young massive star clusters. The model is used to explain the near- to mid-infrared (NIR–MIR) excess found in such clusters and usually modeled as a blackbody with temperature ∼ ( 400 – 1000 ) K. In our approach, dust grains are efficiently produced in the clumpy ejecta of core-collapse supernovae, shattered into small pieces ( ≲ 0.05 μm) as they are incorporated into the hot and dense ISM, heated via frequent collisions with electrons and the absorption of energetic photons. Grains with small sizes can more easily acquire the high temperatures (∼1000 K) required to produce an NIR–MIR excess with respect to the emission of foreground PAHs and starlight. However, the extreme conditions inside young massive clusters make it difficult for these small grains to have a persistent manifestation at NIR–MIR wavelengths as they are destroyed by efficient thermal sputtering. Nevertheless, the chances for a persistent manifestation are increased by taking into account that small grains become increasingly transparent to their impinging ions as their sizes decrease. For an individual SN event, we find that the NIR–MIR excess lasts longer if the time required to incorporate all the grains into the thermalized medium is also longer, and, in some cases, comparable to the characteristic interval between supernova explosions. Our models can successfully explain the near-infrared excesses found in the star clusters observed in M33 assuming a low heating efficiency and mass loading. In this scenario, the presence of the NIR–MIR excess is an indication of efficient dust production in SNe and its subsequent destruction.

Effects of the Core-collapse Supernova Ejecta Impact on a Rapidly Rotating Massive Companion Star

Abstract We investigate the effects of the core-collapse supernova (CCSN) ejecta on a rapidly rotating and massive companion star. We show that the stripped mass is twice as high as that of a massive but nonrotating companion star. In close binaries with orbital periods of about 1 day, the stripped masses reach up to . 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 a stripped mass higher than about . Of all the known high-mass X-ray binaries (HMXBs), Cygnus X-3 and 1WGA J0648.024418 have the shortest orbital periods, 0.2 and 1.55 days, respectively. The optical counterpart of the former is a Wolf-Rayet star, whereas it is a hot subdwarf for the latter. Applying our model to the two HMXBs, we suggest that the hydrogen-rich envelopes of their optical counterparts may have been stripped by CCSN ejecta.

PROBING THE PHYSICAL CONDITIONS OF SUPERNOVA EJECTA WITH THE MEASURED SIZES OF PRESOLAR Al 2 O 3 GRAINS

A few particles of presolar Al2O3 grains with sizes above 0.5 mum are believed to have been produced in the ejecta of core-collapse supernovae (SNe). In order to clarify the formation condition of such large Al2O3 grains, we investigate the condensation of Al2O3 grains for wide ranges of the gas density and cooling rate. We first show that the average radius and condensation efficiency of newly formed Al2O3 grains are successfully described by a non-dimensional quantity "Lambda_on" defined as the ratio of the timescale with which the supersaturation ratio increases to the collision timescale of reactant gas species at dust formation. Then, we find that the formation of submicron-sized Al2O3 grains requires at least ten times higher gas densities than those presented by one-dimensional SN models. This indicates that presolar Al2O3 grains identified as a SN origin might be formed in dense gas clumps, allowing us to propose that the measured sizes of presolar grains can be a powerful tool to constrain the physical conditions in which they formed. We also briefly discuss the survival of newly formed Al2O3 grains against the destruction in the shocked gas within the SN remnants.

The evolution of dust in the local and high-redshift universe

AbstractDust is a ubiquities component of the interstellar medium (ISM) of galaxies, and manifests itself in many different ways. Yet, its origin, composition, and size distribution are still a matter of great debate. Most of the thermally condensed dust is produced in the explosively expelled ejecta of core collapse supernovae (CCSNe) and in the quiescent winds of AGB stars. Following its injection into the ISM it is destroyed by supernova (SN) shock waves. Knowing the relative rates of these processes is crucial for understanding the nature and evolution of dust in galaxies. In the following we will review three aspects of the evolution of dust in galaxies: the evolution of dust in the ejecta of SN1987A; the rates of dust production and destruction rates in the Magellanic Clouds (MCs), and the evolution of dust in CLASH 2882, a gravitationally-lensed galaxy at z=1.

CARBON-RICH PRESOLAR GRAINS FROM MASSIVE STARS: SUBSOLAR 12 C/ 13 C AND 14 N/ 15 N RATIOS AND THE MYSTERY OF 15 N

Carbon-rich grains with isotopic anomalies compared to the Sun are found in primitive meteorites. They were made by stars, and carry the original stellar nucleosynthesis signature. Silicon carbide grains of Type X and C, and low-density graphites condensed in the ejecta of core-collapse supernovae. We present a new set of models for the explosive He shell and compare them with the grains showing 12C/13C and 14N/15N ratios lower than solar. In the stellar progenitor H was ingested into the He shell and not fully destroyed before the explosion. Different explosion energies and H concentrations are considered. If the SN shock hits the He-shell region with some H still present, the models can reproduce the C and N isotopic signatures in C-rich grains. Hot-CNO cycle isotopic signatures are obtained, including a large production of 13C and 15N. The short-lived radionuclides 22Na and 26Al are increased by orders of magnitude. The production of radiogenic 22Ne from the decay of 22Na in the He shell might solve the puzzle of the Ne-E(L) component in low-density graphite grains. This scenario is attractive for the SiC grains of type AB with 14N/15N ratios lower than solar, and provides an alternative solution for SiC grains originally classified as nova grains. Finally, this process may contribute to the production of 14N and 15N in the Galaxy, helping to produce the 14N/15N ratio in the solar system.

ARE MODELS FOR CORE-COLLAPSE SUPERNOVA PROGENITORS CONSISTENT WITH THE PROPERTIES OF SUPERNOVA REMNANTS?

The recent discovery that the Fe-K line luminosities and energy centroids observed in nearby SNRs are a strong discriminant of both progenitor type and circumstellar environment has implications for our understanding of supernova progenitor evolution. Using models for the chemical composition of core-collapse supernova ejecta, we model the dynamics and thermal X-ray emission from shocked ejecta and circumstellar material, modeled as an $r^{-2}$ wind, to ages of 3000 years. We compare the X-ray spectra expected from these models to observations made with the Suzaku satellite. We also model the dynamics and X-ray emission from Type Ia progenitor models. We find a clear distinction in Fe-K line energy centroid between core-collapse and Type Ia models. The core-collapse supernova models predict higher Fe-K line centroid energies than the Type Ia models, in agreement with observations. We argue that the higher line centroids are a consequence of the increased densities found in the circumstellar environment created by the expansion of the slow-moving wind from the massive progenitors.

Presolar graphite from the Murchison meteorite: An isotopic study

We studied presolar graphite grains from four density fractions, KE3 (1.65–1.72g/cm3), KFA1 (2.05–2.10g/cm3), KFB1 (2.10–2.15g/cm3), and KFC1 (2.15–2.20g/cm3), extracted from the Murchison (CM2) meteorite, with the ion microprobe. One of the most interesting features of presolar graphite is that isotopic features depend on density. There are grains with 15N and 18O excesses, Si isotopic anomalies, high 26Al/27Al ratios (∼0.1), and Ca and Ti isotopic anomalies, including the initial presence of short-lived 41Ca and 44Ti. These isotopic features are qualitatively explained by nucleosynthesis in core collapse supernovae. We estimate that 76%, 50%, 7% and 1% of the KE3, KFA1, KFB1 and KFC1 grains, respectively, are supernova grains. We performed 3- and 4-zone supernova mixing calculations to reproduce the C, O (18O/16O) and Al isotopic ratios of the KE3 grains, using 15M⊙ model calculations by Rauscher et al. (2002). Isotopic ratios of grains with high 12C/13C ratios (>200) can be reproduced, whereas those of grains with ratios ⩽200 are hard to explain if we assume that graphite grains form in C-rich conditions.We compared the distributions of the 12C/13C ratios of KFB1 and KFC1 grains and their s-process 86Kr/82Kr ratios inferred from bulk noble gas analysis to model calculations of asymptotic giant branch (AGB) stars with a range of mass and metallicity. We conclude that KFB1 grains with 12C/13C⩾100 formed in the outflow of low-mass (1.5, 2 and 3M⊙) low-metallicity (Z=3×10−3 for 1.5, 2 and 3M⊙, Z=6×10−3 for 3M⊙ only) AGB stars and that KFC1 grains with 12C/13C⩾60 formed in those stars as well as in 5M⊙ stars of solar and/or half-solar metallicities. Grains with 12C/13C<20 in all the fractions seem to have multiple origins. Some of them formed in the ejecta of core-collapse supernovae. J stars and born-again AGB stars are also possible stellar sources.We calculated the abundances of graphite grains from supernovae and AGB stars in the Murchison meteorite to be 0.24ppm and 0.44ppm, respectively, whereas those of SiC grains from supernovae and AGB stars are 0.063ppm and 5.6ppm, respectively. In contrast to graphite, AGB stars are a dominant source of SiC grains.Since different mineral types have different residence times in the interstellar medium, their abundances in meteorites may not reflect original yields in stellar sources. Even if graphite grains are more easily destroyed than SiC grains, graphite grains from supernovae are more abundant than SiC grains from supernovae (0.24ppm vs. 0.063ppm), indicating that supernovae are a prolific producer of graphite grains. Graphite grains from AGB stars are less abundant than SiC grains from AGB stars (0.44ppm vs. 5.6ppm). This difference may reflect the difference in their parent stars: graphite grains formed in low-metallicity stars, while SiC grains formed in close-to-solar metallicity stars.