The Yarkovsky-O'Keefe-Radzievskii-Paddack(YORP)effect is a net torque caused by solar radiation directly reflected and thermally re-emitted from the surface of small asteroids and is considered to be crucial in their dynamical evolution.By long-term photometric observations of selected near-Earth asteroids,it is hoped to enlarge asteroid samples with a detected YORP effect to facilitate the development of a theoretical framework.Archived light-curve data are collected and photometric observations are made for(1685)Toro and(85989)1999 JD6,which enables measurement of their YORP effect by inverting the light curve to fit observations from a convex shape model.For(1685)Toro,a YORP acceleration υ=(3.2±0.3)×10-9 rad·day-2(1o errror)is updated,which is consistent with previous YORP detection based on different light-curve data;for(85989)1999 JD6,it is determined that the sidereal period is 7.667 749±0.000009 hr,the rotation pole direction is located at A=232°±2°,β=-59°±1°,the acceleration is detected to be υ=(2.4±0.3)×10-8 rad·day-2(1σ error)and in addition to obtaining an excellent agreement between the observations and model.YORP should produce both spin-up and spin-down cases.However,including(85989)1999 JD6,the dω/dt values of 11 near-Earth asteroids are positive totally,which suggests that there is either a bias in the sample of YORP detections or a real feature needs to be explained.

Jun Tian;Hai-Bin Zhao;Bin Li

Key Laboratory of Planetary Sciences,Purple Mountain Observatory,Chinese Academy of Sciences,Nanjing 210023,China;School of Astronomy and Space Science,University of Science and Technology of China,Hefei 230026,China;Center for Excellence in Comparative Planetology,Chinese Academy of Sciences,Heifei 230026,China

天文和天体物理学研究

[1]Jun Tian;Hai-Bin Zhao;Bin Li-.Shape Model and Rotation Acceleration of(1685)Toro and(85989)1999 JD6 from Optical Observations)[J].天文和天体物理学研究,2022(12):166-182

JD6,Yarkovsky,Radzievskii,Paddack,YORP,Archived,errror,sidereal

Shape,Model,Rotation,Acceleration,Toro,from,Optical,Observations,Keefe,effect,net,torque,caused,by,solar,radiation,directly,reflected,thermally,emitted,surface,small,asteroids,considered,crucial,their,dynamical,evolution,By,long,photometric,observations,selected,near,Earth,hoped,enlarge,samples,detected,facilitate,development,theoretical,framework,light,curve,data,are,collected,made,which,enables,measurement,inverting,fit,convex,shape,model,For,acceleration,day,1o,updated,consistent,previous,different,determined,that,period,hr,rotation,pole,direction,located,error,addition,obtaining,excellent,agreement,between,should,produce,both,spin,down,cases,However,including,dt,values,positive,totally,suggests,there,either,bias,detections,feature,needs,explained

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