We identify an S-shaped main-jet axis in the Vela core-collapse supernova remnant(CCSNR)that we attribute to a pair of precessing jets,one of the tens of pairs of jets that exploded the progenitor of Vela according to...We identify an S-shaped main-jet axis in the Vela core-collapse supernova remnant(CCSNR)that we attribute to a pair of precessing jets,one of the tens of pairs of jets that exploded the progenitor of Vela according to the jittering jets explosion mechanism(JJEM).A main-jet axis is a symmetry axis across the CCSNR and through the center.We identify the S-shaped main-jet axis by the high abundance of ejecta elements,oxygen,neon,and magnesium.We bring the number of identified pairs of clumps and ears in Vela to seven,two pairs shaped by the pair of precessing jets that formed the main-jet axis.The pairs and the main-jet axis form the point-symmetric wind-rose structure of Vela.The other five pairs of clumps/ears do not have signatures near the center,only on two opposite sides of the CCSNR.We discuss different possible jet-less shaping mechanisms to form such a point-symmetric morphology and dismiss these processes because they cannot explain the point-symmetric morphology of Vela,the S-shaped high ejecta abundance pattern,and the enormous energy required to shape the S-shaped structure.Our findings strongly support the JJEM and further severely challenge the neutrino-driven explosion mechanism.展开更多
This paper yields a new exact solution for dense stellar objects by employing the Einstein-Maxwell system of differential equations.The established model comprises three interior layers with distinguishable equations ...This paper yields a new exact solution for dense stellar objects by employing the Einstein-Maxwell system of differential equations.The established model comprises three interior layers with distinguishable equations of state(EoSs):the polytropic EoS at the core layer,the quadratic EoS at the intermediate layer and the modified Van der Waals EoS at the envelope layer.The physical features indicate that the matter variables,metric functions and other physical conditions are viable with dense astrophysical objects.Excitingly,this model is an extension solution of the two-layered model generated by Sunzu and Lighuda.The layers are matched gently across the junctions with the care of the Reissner-Nordström exterior spacetime.Utilizing our model,star masses and radii compatible with observations and satisfactorily known objects are generated.The findings from this paper may be useful to describes purported strange stars such as SAX J1808.4-3658 and binary stars such as Vela X-1.展开更多
The subsurface convective zones (CZs) of massive stars significantly influence many of their key characteristics.Previous studies have paid little attention to the impact of rotation on the subsurface CZ,so we aim to ...The subsurface convective zones (CZs) of massive stars significantly influence many of their key characteristics.Previous studies have paid little attention to the impact of rotation on the subsurface CZ,so we aim to investigate the evolution of this zone in rapidly rotating massive stars.We use the Modules for Experiments in Stellar Astrophysics to simulate the subsurface CZs of massive stars during the main sequence phase.We establish stellar models with initial masses ranging from 5 M⊙to 120 M⊙,incorporating four metallicities (Z=0.02,0.006,0.002,and 0.0001) and three rotational velocities (ω/ωcrit=0,ω/ωcrit=0.50,andω/ωcrit=0.75).We find that rapid rotation leads to an expansion of the subsurface CZ,increases convective velocities,and promotes the development of this zone.Additionally,subsurface CZs can also emerge in stars with lower metallicities.Comparing our models with observations of massive stars in the Galaxy,the Large Magellanic Cloud,and the Small Magellanic Cloud,we find that rotating models better encompass the observed samples.Rotation significantly influences the evolution of the subsurface CZ in massive stars.By comparing with the observed microturbulence on the surfaces of OB stars,we propose that the subsurface CZs may be one of the sources of microturbulence.展开更多
We demonstrate by three-dimensional hydrodynamical simulations of energy deposition into the envelope of a red supergiant model the inflation of a Rayleigh–Taylor unstable envelope that forms a compact clumpy circums...We demonstrate by three-dimensional hydrodynamical simulations of energy deposition into the envelope of a red supergiant model the inflation of a Rayleigh–Taylor unstable envelope that forms a compact clumpy circumstellar material(CSM).Our simulations mimic vigorous core activity years to months before a core-collapse supernova(CCSN)explosion that deposits energy to the outer envelope.The fierce core nuclear activity in the pre-CCSN explosion phase might excite waves that propagate to the envelope.The wave energy is dissipated where envelope convection cannot carry the energy.We deposit this energy into a shell in the outer envelope with a power of L_(wave)=2.6×10^(6)L■or L_(wave)=5.2×10^(5)L■for 0.32 yr.The energy-deposition shell expands while its pressure is higher than its surroundings,but its density is lower.Therefore,this expansion is Rayleigh–Taylor unstable and develops instability fingers.Most of the inflated envelope does not reach the escape velocity in the year of simulation but forms a compact and clumpy CSM.The high density of the inflated envelope implies that if a companion is present in that zone,it will accrete mass at a very high rate and power a pre-explosion outburst.展开更多
SN 2014av is a type Ibn supernova(SN)characterized by the interaction between the SN ejecta and a helium-rich circumstellar medium(CSM).We use the^(56)Ni model,the ejecta-CSM interaction(CSI)model,and the CSI plus^(56...SN 2014av is a type Ibn supernova(SN)characterized by the interaction between the SN ejecta and a helium-rich circumstellar medium(CSM).We use the^(56)Ni model,the ejecta-CSM interaction(CSI)model,and the CSI plus^(56)Ni model to fit the multiband light curves(LCs)of SN 2014av.For the CSI and CSI plus^(56)Ni models,we assume that the CSM is a constant density shell(“shell”)or a steady-state stellar wind(“wind”)with density∝r-2.We find that both the^(56)Ni and CSI models fail to fit the multiband LCs of SN 2014av,while the CSI plus^(56)Ni model can account for the LCs.In the last scenario,the LCs around the peaks were mainly powered by the CSI,while the flattening of the LCs was mainly powered by the radioactive decay of^(56)Ni.For the wind case,the derived mass-loss rate of the progenitor is≈20.5-205.5 M_(⊙)yr^(-1),whose lower limit is significantly larger than the upper limit of normal stellar winds,and comparable the upper limit of hyper-winds.Hence,we suggest that the wind case is disfavored.For the shell case,the best-fitting values of the ejecta,^(56)Ni,and the CSM are2.29 M_(⊙),0.09 M_(⊙),and 5.00 M_(⊙),respectively.Provided the velocity of the CSM shell is 100-1000 km s^(-1),we infer that the shell might be expelled≈0.49-5.20 yr before the SN exploded.展开更多
I build a toy model in the frame of the jittering jets explosion mechanism(JJEM)of core collapse supernovae that incorporates both the stochastically varying angular momentum component of the material that the newly b...I build a toy model in the frame of the jittering jets explosion mechanism(JJEM)of core collapse supernovae that incorporates both the stochastically varying angular momentum component of the material that the newly born neutron star(NS)accretes and the constant angular momentum component,and show that the JJEM can account for the≃2.5–5M⊙mass gap between NSs and black holes(BHs).The random component of the angular momentum results from pre-collapse core convection fluctuations that are amplified by post-collapse instabilities.The fixed angular momentum component results from pre-collapse core rotation.For slowly rotating pre-collapse cores the stochastic angular momentum fluctuations form intermittent accretion disks(or belts)around the NS with varying angular momentum axes in all directions.The intermittent accretion disk/belt launches jets in all directions that expel the core material in all directions early on,hence leaving an NS remnant.Rapidly rotating pre-collapse cores form an accretion disk with angular momentum axis that is about the same as the pre-collapse core rotation.The NS launches jets along this axis and hence the jets avoid the equatorial plane region.Inflowing core material continues to feed the central object from the equatorial plane increasing the NS mass to form a BH.The narrow transition from slow to rapid pre-collapse core rotation,i.e.,from an efficient to inefficient jet feedback mechanism,accounts for the sparsely populated mass gap.展开更多
I present the effervescent zone model to account for the compact dense circumstellar material(CSM)around the progenitor of the core collapse supernova(CCSN)SN 2023ixf.The effervescent zone is composed of bound dense c...I present the effervescent zone model to account for the compact dense circumstellar material(CSM)around the progenitor of the core collapse supernova(CCSN)SN 2023ixf.The effervescent zone is composed of bound dense clumps that are lifted by stellar pulsation and envelope convection to distances of≈tens×au,and then fall back.The dense clumps provide most of the compact CSM mass and exist alongside the regular(escaping)wind.I crudely estimate that for a compact CSM within R_(CSM)≈30 au that contains M_(CSM)≈0.01 M_(⊙),the density of each clump is k_(b)≳3000 times the density of the regular wind at the same radius and that the total volume filling factor of the clumps is several percent.The clumps might cover only a small fraction of the CCSN photosphere in the first days post-explosion,accounting for the lack of strong narrow absorption lines.The long-lived effervescent zone is compatible with no evidence for outbursts in the years prior to the SN 2023ixf explosion and the large-amplitude pulsations of its progenitor,and it is an alternative to the CSM scenario of several-years-long high mass loss rate wind.展开更多
基金A grant from the Pazy Foundation supported this research
文摘We identify an S-shaped main-jet axis in the Vela core-collapse supernova remnant(CCSNR)that we attribute to a pair of precessing jets,one of the tens of pairs of jets that exploded the progenitor of Vela according to the jittering jets explosion mechanism(JJEM).A main-jet axis is a symmetry axis across the CCSNR and through the center.We identify the S-shaped main-jet axis by the high abundance of ejecta elements,oxygen,neon,and magnesium.We bring the number of identified pairs of clumps and ears in Vela to seven,two pairs shaped by the pair of precessing jets that formed the main-jet axis.The pairs and the main-jet axis form the point-symmetric wind-rose structure of Vela.The other five pairs of clumps/ears do not have signatures near the center,only on two opposite sides of the CCSNR.We discuss different possible jet-less shaping mechanisms to form such a point-symmetric morphology and dismiss these processes because they cannot explain the point-symmetric morphology of Vela,the S-shaped high ejecta abundance pattern,and the enormous energy required to shape the S-shaped structure.Our findings strongly support the JJEM and further severely challenge the neutrino-driven explosion mechanism.
文摘This paper yields a new exact solution for dense stellar objects by employing the Einstein-Maxwell system of differential equations.The established model comprises three interior layers with distinguishable equations of state(EoSs):the polytropic EoS at the core layer,the quadratic EoS at the intermediate layer and the modified Van der Waals EoS at the envelope layer.The physical features indicate that the matter variables,metric functions and other physical conditions are viable with dense astrophysical objects.Excitingly,this model is an extension solution of the two-layered model generated by Sunzu and Lighuda.The layers are matched gently across the junctions with the care of the Reissner-Nordström exterior spacetime.Utilizing our model,star masses and radii compatible with observations and satisfactorily known objects are generated.The findings from this paper may be useful to describes purported strange stars such as SAX J1808.4-3658 and binary stars such as Vela X-1.
基金the National Natural Science Foundation of China under grant Nos.U2031204,12163005,12373038,12288102,and 12263006the science research grant from the China Manned Space Project with No.CMSCSST-2021-A10+1 种基金the Natural Science Foundation of Xinjiang Nos.2022D01D85 and 2022TSYCLJ0006the Major Science and Technology Program of Xinjiang Uygur Autonomous Region under grant No.2022A03013-3.
文摘The subsurface convective zones (CZs) of massive stars significantly influence many of their key characteristics.Previous studies have paid little attention to the impact of rotation on the subsurface CZ,so we aim to investigate the evolution of this zone in rapidly rotating massive stars.We use the Modules for Experiments in Stellar Astrophysics to simulate the subsurface CZs of massive stars during the main sequence phase.We establish stellar models with initial masses ranging from 5 M⊙to 120 M⊙,incorporating four metallicities (Z=0.02,0.006,0.002,and 0.0001) and three rotational velocities (ω/ωcrit=0,ω/ωcrit=0.50,andω/ωcrit=0.75).We find that rapid rotation leads to an expansion of the subsurface CZ,increases convective velocities,and promotes the development of this zone.Additionally,subsurface CZs can also emerge in stars with lower metallicities.Comparing our models with observations of massive stars in the Galaxy,the Large Magellanic Cloud,and the Small Magellanic Cloud,we find that rotating models better encompass the observed samples.Rotation significantly influences the evolution of the subsurface CZ in massive stars.By comparing with the observed microturbulence on the surfaces of OB stars,we propose that the subsurface CZs may be one of the sources of microturbulence.
基金A grant from the Pazy Foundation supported this research。
文摘We demonstrate by three-dimensional hydrodynamical simulations of energy deposition into the envelope of a red supergiant model the inflation of a Rayleigh–Taylor unstable envelope that forms a compact clumpy circumstellar material(CSM).Our simulations mimic vigorous core activity years to months before a core-collapse supernova(CCSN)explosion that deposits energy to the outer envelope.The fierce core nuclear activity in the pre-CCSN explosion phase might excite waves that propagate to the envelope.The wave energy is dissipated where envelope convection cannot carry the energy.We deposit this energy into a shell in the outer envelope with a power of L_(wave)=2.6×10^(6)L■or L_(wave)=5.2×10^(5)L■for 0.32 yr.The energy-deposition shell expands while its pressure is higher than its surroundings,but its density is lower.Therefore,this expansion is Rayleigh–Taylor unstable and develops instability fingers.Most of the inflated envelope does not reach the escape velocity in the year of simulation but forms a compact and clumpy CSM.The high density of the inflated envelope implies that if a companion is present in that zone,it will accrete mass at a very high rate and power a pre-explosion outburst.
基金supported by the National Key R&D Program(2024YFA1611700)the National Natural Science Foundation of China(grant Nos.12133003,12494571 and 11963001)supported by the Guangxi Talent Program(“Highland of Innovation Talents”)and Program of Bagui Scholars(LHJ)。
文摘SN 2014av is a type Ibn supernova(SN)characterized by the interaction between the SN ejecta and a helium-rich circumstellar medium(CSM).We use the^(56)Ni model,the ejecta-CSM interaction(CSI)model,and the CSI plus^(56)Ni model to fit the multiband light curves(LCs)of SN 2014av.For the CSI and CSI plus^(56)Ni models,we assume that the CSM is a constant density shell(“shell”)or a steady-state stellar wind(“wind”)with density∝r-2.We find that both the^(56)Ni and CSI models fail to fit the multiband LCs of SN 2014av,while the CSI plus^(56)Ni model can account for the LCs.In the last scenario,the LCs around the peaks were mainly powered by the CSI,while the flattening of the LCs was mainly powered by the radioactive decay of^(56)Ni.For the wind case,the derived mass-loss rate of the progenitor is≈20.5-205.5 M_(⊙)yr^(-1),whose lower limit is significantly larger than the upper limit of normal stellar winds,and comparable the upper limit of hyper-winds.Hence,we suggest that the wind case is disfavored.For the shell case,the best-fitting values of the ejecta,^(56)Ni,and the CSM are2.29 M_(⊙),0.09 M_(⊙),and 5.00 M_(⊙),respectively.Provided the velocity of the CSM shell is 100-1000 km s^(-1),we infer that the shell might be expelled≈0.49-5.20 yr before the SN exploded.
基金a grant from the Israel Science Foundation(769/20).
文摘I build a toy model in the frame of the jittering jets explosion mechanism(JJEM)of core collapse supernovae that incorporates both the stochastically varying angular momentum component of the material that the newly born neutron star(NS)accretes and the constant angular momentum component,and show that the JJEM can account for the≃2.5–5M⊙mass gap between NSs and black holes(BHs).The random component of the angular momentum results from pre-collapse core convection fluctuations that are amplified by post-collapse instabilities.The fixed angular momentum component results from pre-collapse core rotation.For slowly rotating pre-collapse cores the stochastic angular momentum fluctuations form intermittent accretion disks(or belts)around the NS with varying angular momentum axes in all directions.The intermittent accretion disk/belt launches jets in all directions that expel the core material in all directions early on,hence leaving an NS remnant.Rapidly rotating pre-collapse cores form an accretion disk with angular momentum axis that is about the same as the pre-collapse core rotation.The NS launches jets along this axis and hence the jets avoid the equatorial plane region.Inflowing core material continues to feed the central object from the equatorial plane increasing the NS mass to form a BH.The narrow transition from slow to rapid pre-collapse core rotation,i.e.,from an efficient to inefficient jet feedback mechanism,accounts for the sparsely populated mass gap.
基金supported by a grant from the Israel Science Foundation(769/20)。
文摘I present the effervescent zone model to account for the compact dense circumstellar material(CSM)around the progenitor of the core collapse supernova(CCSN)SN 2023ixf.The effervescent zone is composed of bound dense clumps that are lifted by stellar pulsation and envelope convection to distances of≈tens×au,and then fall back.The dense clumps provide most of the compact CSM mass and exist alongside the regular(escaping)wind.I crudely estimate that for a compact CSM within R_(CSM)≈30 au that contains M_(CSM)≈0.01 M_(⊙),the density of each clump is k_(b)≳3000 times the density of the regular wind at the same radius and that the total volume filling factor of the clumps is several percent.The clumps might cover only a small fraction of the CCSN photosphere in the first days post-explosion,accounting for the lack of strong narrow absorption lines.The long-lived effervescent zone is compatible with no evidence for outbursts in the years prior to the SN 2023ixf explosion and the large-amplitude pulsations of its progenitor,and it is an alternative to the CSM scenario of several-years-long high mass loss rate wind.
