Detection of stellar spots from the observations of caustic-crossing binary-lens gravitational microlensing events

Authors


★ E-mail: cheongho@astronomy.chungbuk.ac.kr (CH); parksh@ast.chungbuk.ac.kr (SP); hikim@hanul.issa.re.kr (HK); kchang@alpha94.chongju.ac.kr (KC)

Abstract

Recently, Heyrovský & Sasselov investigated the sensitivity of single-lens gravitational microlensing event light curves to spots and found that, during source transit, spots can cause deviations in amplification larger than 2 per cent, and thus be detectable. In this paper, we explore the feasibility of spot detection from the observations of binary-lens microlensing events instead of single-lens events. For this we investigate the sensitivity of binary-lens event light curves to spots and compare it with that of single-lens events. From this investigation, we find that during caustic crossings the fractional amplification deviations of light curves from those of spotless source events are equivalent to those of single-lens events, implying that spots can also be detected with a similar photometric precision to that required for spot detection by observing single-lens events. We discuss the relative advantages of observing binary-lens events over the observations of single-lens events in detecting stellar spots.

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