Using ground-based telescopes,the multi-color photometric observations of the contact binary EF Boo were obtained in 2020,2023,and 2024.Combining these with 7-sectors of light curves from TESS data,the variations of t...Using ground-based telescopes,the multi-color photometric observations of the contact binary EF Boo were obtained in 2020,2023,and 2024.Combining these with 7-sectors of light curves from TESS data,the variations of the O'Connell effect in continuous time and shapes of light curves over several years were identified.Three sets of typical light curves were analyzed to determine the photometric solutions via the Wilson-Devinney program.Considering the spectroscopic mass ratio of q=0.53,these photometric solutions suggest that EF Boo is a W-type W UMa contact binary with the averaged filling factor of f=22.26%,a small temperature difference,and a cool spot on the primary component.If the variations of the O'Connell effect are due to the magnetic activity of this cool spot,the longitudinal location varied from 50.4 to 302.7 over the time interval of 1434 days.Based on all CCD minimum times from ground-based telescope and TESS data,the O-C curve was also analyzed.A cyclic oscillation(A3=0.00575 days,T3=27.8 yr)superimposed on a secular increase(dP/dt=6.74×10^(-8)day yr^(-1))was discovered for the first time.The successive increase is possibly a result of mass transfer from the less massive star to the more massive one.The cyclic oscillations were possibly explained by the light-travel time effect via a third body or the magnetic activities.From the short cadence observations from TESS,we also calculated the value of the O'Connell effect and O-C value for each cycle and found no correlation between the O'Connell effect and O-C over nearly 30 days across different sectors.展开更多
文摘随着城市公共服务需求的不断提升及儿童友好城市建设的推进,深圳市儿童公园类服务设施正在向多元化、市场化和公益性目标转型,lii i政府和社会资本合作(Pubc-Prvate-Partnershp,PPP)将成为该类项目的主流运营模式。以某公园儿童游乐场改造项目为例,通过对项l目动力设施区财务收支构成、现金流模型与敏感性参数的系统测算,探讨了不同定价策略对项目经济效益、回本周期及内部收益率(Interna Rate of Return,IRR)的影响。采用问卷调查、市场数据对比与数学建模等多种方法,构建了项目收益与成本之间的量化模型,提出了建设-il拥有-经营(Bud-Own-Operate,BOO)模式下的定价优化建议,为儿童游乐场项目的决策提供了实证依据,也为类似公共设施PPP项目的财务评估与运营策略的选择提供了参考。
基金support of the staff of the 85 cm,60 cm telescopes at the Xinglong observational station of the National Astronomical Observatories,Chinese Academy of Sciences,and TESS team works funding by the NASA Science Mission directorate.This work is sponsored by the Natural Science Foundation of Xinjiang Uygur Autonomous Region(No.2022D01A164)the National Natural Science Foundation of China(Nos.U1831109 and 12103030)。
文摘Using ground-based telescopes,the multi-color photometric observations of the contact binary EF Boo were obtained in 2020,2023,and 2024.Combining these with 7-sectors of light curves from TESS data,the variations of the O'Connell effect in continuous time and shapes of light curves over several years were identified.Three sets of typical light curves were analyzed to determine the photometric solutions via the Wilson-Devinney program.Considering the spectroscopic mass ratio of q=0.53,these photometric solutions suggest that EF Boo is a W-type W UMa contact binary with the averaged filling factor of f=22.26%,a small temperature difference,and a cool spot on the primary component.If the variations of the O'Connell effect are due to the magnetic activity of this cool spot,the longitudinal location varied from 50.4 to 302.7 over the time interval of 1434 days.Based on all CCD minimum times from ground-based telescope and TESS data,the O-C curve was also analyzed.A cyclic oscillation(A3=0.00575 days,T3=27.8 yr)superimposed on a secular increase(dP/dt=6.74×10^(-8)day yr^(-1))was discovered for the first time.The successive increase is possibly a result of mass transfer from the less massive star to the more massive one.The cyclic oscillations were possibly explained by the light-travel time effect via a third body or the magnetic activities.From the short cadence observations from TESS,we also calculated the value of the O'Connell effect and O-C value for each cycle and found no correlation between the O'Connell effect and O-C over nearly 30 days across different sectors.
