OGLE-2013-BLG-0102LA,B: Microlensing binary with components at star/brown-dwarf and brown-dwarf/planet boundaries

摘要

We present the analysis of the gravitational microlensing eventOGLE-2013-BLG-0102. The light curve of the event is characterized by a strongshort-term anomaly superposed on a smoothly varying lensing curve with amoderate magnification $A_{\rm max}\sim 1.5$. It is found that the event wasproduced by a binary lens with a mass ratio between the components of $q =0.13$ and the anomaly was caused by the passage of the source trajectory over acaustic located away from the barycenter of the binary. From the analysis ofthe effects on the light curve due to the finite size of the source and theparallactic motion of the Earth, the physical parameters of the lens system aredetermined. The measured masses of the lens components are $M_{1} = 0.096 \pm0.013~M_{\odot}$ and $M_{2} = 0.012 \pm 0.002~M_{\odot}$, which correspond tonear the hydrogen-burning and deuterium-burning mass limits, respectively. Thedistance to the lens is $3.04 \pm 0.31~{\rm kpc}$ and the projected separationbetween the lens components is $0.80 \pm 0.08~{\rm AU}$.