The development of large-scale time-domain surveys provides an opportunity to study the physical properties as well as the evolutionary scenario of B-type subdwarfs(sdBs)and M-type dwarfs(dMs).Here,we obtained 33 sdB+...The development of large-scale time-domain surveys provides an opportunity to study the physical properties as well as the evolutionary scenario of B-type subdwarfs(sdBs)and M-type dwarfs(dMs).Here,we obtained 33 sdB+dM eclipsing binaries based on the Zwicky Transient Facility(ZTF)light curves and Gaia Early Data Release3(EDR3)parallaxes.By using the PHOEBE code for light curve analysis,we obtain probability distributions for parameters of 29 sdB+dMs.R1,R2 and i are well determined,and the average uncertainty of mass ratio q is 0.08.Our parameters are in good agreement with previous works if a typical mass of sdB is assumed.Based on parameters of 29 sdB+dMs,we find that both the mass ratio q and the companion’s radius R2 decrease with the shortening of the orbital period.For the three sdB+dMs with orbital periods less than 0.075 days,their companions are all brown dwarfs.The masses and radii of the companions satisfy the mass–radius relation for low-mass stars and brown dwarfs.Companions with radii between 0.12 R_(⊙)and 0.15 R_(⊙)seem to be missing in the observations.As more short-period sdB+dM eclipsing binaries are discovered and classified in the future with ZTF and Gaia,we will have more information to constrain the evolutionary ending of sdB+dMs.展开更多
基金supported by Sichuan Science and Technology Program(grant No.2020YFSY0034)National Natural Science Foundation of China(NSFC)through the projects 12003022,12173047,11903045,12003046,and U1731111+2 种基金supported by the Major Science and Technology Project of Qinghai Province 2019-ZJ-A10funded in part by the National Science Foundation(NSF#1517474,#1909109)the National Aeronautics and Space Administration(NASA 17ADAP17-68)。
文摘The development of large-scale time-domain surveys provides an opportunity to study the physical properties as well as the evolutionary scenario of B-type subdwarfs(sdBs)and M-type dwarfs(dMs).Here,we obtained 33 sdB+dM eclipsing binaries based on the Zwicky Transient Facility(ZTF)light curves and Gaia Early Data Release3(EDR3)parallaxes.By using the PHOEBE code for light curve analysis,we obtain probability distributions for parameters of 29 sdB+dMs.R1,R2 and i are well determined,and the average uncertainty of mass ratio q is 0.08.Our parameters are in good agreement with previous works if a typical mass of sdB is assumed.Based on parameters of 29 sdB+dMs,we find that both the mass ratio q and the companion’s radius R2 decrease with the shortening of the orbital period.For the three sdB+dMs with orbital periods less than 0.075 days,their companions are all brown dwarfs.The masses and radii of the companions satisfy the mass–radius relation for low-mass stars and brown dwarfs.Companions with radii between 0.12 R_(⊙)and 0.15 R_(⊙)seem to be missing in the observations.As more short-period sdB+dM eclipsing binaries are discovered and classified in the future with ZTF and Gaia,we will have more information to constrain the evolutionary ending of sdB+dMs.
