Although supernovae are well-known endpoints of accreting white dwarfs,alternative theoretical possibilities have been widely discussed,such as the accretion-induced collapse(AIC)event as the endpoint of oxygen-neon(O...Although supernovae are well-known endpoints of accreting white dwarfs,alternative theoretical possibilities have been widely discussed,such as the accretion-induced collapse(AIC)event as the endpoint of oxygen-neon(ONe)white dwarfs,either accreting up to or merging to exceed the Chandrasekhar limit(the maximum mass of a stable white dwarf).AIC is an important channel to form neutron stars,especially for those unusual systems that are unlikely produced by core-collapse supernovae.However,the observational evidence for this theoretically predicted event and its progenitor is very limited.In all of the known progenitor systems,white dwarfs increase in mass through accretion.Here,we report the discovery of an intriguing binary system Lan 11,composed of a stripped core-helium-burning hot subdwarf and an unseen compact object with a mass of 1.08M_(⊙)to 1.35M_(⊙).Our binary population synthesis calculations suggest that the latter is most likely to be an ONe white dwarf.Furthermore,the nondetection in deep radio observations by the Five-hundred-meter Aperture Spherical Radio Telescope(FAST)does not exclude this interpretation.The total mass of this binary ranges from 1.67M_(⊙)to 1.92M_(⊙),significantly exceeding the Chandrasekhar limit.The reproduction of its evolutionary history indicates that the unique system has undergone two phases of common envelope ejection,implying a born nature of this massive ONe white dwarf rather than an accretion growth from its companion.These results,together with short orbital period of this binary(3.65 h),suggest that this system will merge in 500-540 Myr,largely triggering an AIC event,although the possibility of type Ia supernova cannot be entirely ruled out.This finding greatly provides valuable constraints on our understanding of stellar endpoints,whatever leading to an AIC or a supernova.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11988101,11933004,12288102,12125303,12090040,12225304,12373037,and 12422303)the National Key R&D Program of China(Grant Nos.2021YFA1600400,and 2021YFA1600401)+17 种基金the Science Research Grants from the China Manned Space Project.Zhenwei Li acknowledges support from the National Natural Science Foundation of China(Grant No.12473034)the Yunnan Fundamental Research Projects(YFRP)(Grant No.202401AT070139)supported by the YFRP(Grant No.202401CF070035)the Young Talent Project of Yunnan Revitalization Talent Support Program.Dongdong Liu is supported by the National Natural Science Foundation of China(Grant No.12273105)the Youth Innovation Promotion Association CAS(Grant No.2021058)the Yunnan Revitalization Talent Support Program-Young Talent Project,and the Yunnan Fundamental Research Projects(Grant Nos.202401AV070006,and 202201AW070011)support from the National Natural Science Foundation of China(Grant No.12173028)suport from the National Natural Science Foundation of China(Grant No.12203068)support from the National Natural Science Foundation of China(Grant Nos.11988101,and 12041303)the CAS Youth Interdisciplinary Team,the Youth Innovation Promotion Association CAS(Grant No.2021055)the Cultivation Project for FAST Scientific Payoff and Research Achievement of CAMSCAS.P´eter N´emeth acknowledges support from the Grant Agency of the Czech Republic(Grant No.GACR 22-34467S)supported by the Project(Grant No.RVO:67985815)support from the National Natural Science Foundation of China(Grant Nos.12288102,12125303,and 12090043)the International Centre of Supernovae,Yunnan Key Laboratory(Grant No.202302AN360001)the Yunnan Fundamental Research Projects(Grant Nos.202201BC070003,and 202001AW070007)the Yunnan Revitalization Talent Support Program-Science&Technology Champion Project(Grant No.202305AB350003)support from the National Natural Science Foundation of China(Grant Nos.11988101,and 11933004)the New Cornerstone Science Foundation through the New Cornerstone Investigator Program and the XPLORER PRIZE。
文摘Although supernovae are well-known endpoints of accreting white dwarfs,alternative theoretical possibilities have been widely discussed,such as the accretion-induced collapse(AIC)event as the endpoint of oxygen-neon(ONe)white dwarfs,either accreting up to or merging to exceed the Chandrasekhar limit(the maximum mass of a stable white dwarf).AIC is an important channel to form neutron stars,especially for those unusual systems that are unlikely produced by core-collapse supernovae.However,the observational evidence for this theoretically predicted event and its progenitor is very limited.In all of the known progenitor systems,white dwarfs increase in mass through accretion.Here,we report the discovery of an intriguing binary system Lan 11,composed of a stripped core-helium-burning hot subdwarf and an unseen compact object with a mass of 1.08M_(⊙)to 1.35M_(⊙).Our binary population synthesis calculations suggest that the latter is most likely to be an ONe white dwarf.Furthermore,the nondetection in deep radio observations by the Five-hundred-meter Aperture Spherical Radio Telescope(FAST)does not exclude this interpretation.The total mass of this binary ranges from 1.67M_(⊙)to 1.92M_(⊙),significantly exceeding the Chandrasekhar limit.The reproduction of its evolutionary history indicates that the unique system has undergone two phases of common envelope ejection,implying a born nature of this massive ONe white dwarf rather than an accretion growth from its companion.These results,together with short orbital period of this binary(3.65 h),suggest that this system will merge in 500-540 Myr,largely triggering an AIC event,although the possibility of type Ia supernova cannot be entirely ruled out.This finding greatly provides valuable constraints on our understanding of stellar endpoints,whatever leading to an AIC or a supernova.
