*Noriaki Arima1, Shinsuke Abe1, Ko Arimatsu2, Miho Kawabata2
(1.Nihon University, 2.Kyoto University)
Keywords:Moon, ground-based telescope, lunar impact flash, meteoroid
When meteoroids, typically the size of centimeters and originating from asteroids or comets, collide with the lunar surface at velocities of several tens of kilometers per second, a portion of their kinetic energy is observed as a flash ranging from visible light to near-infrared. This phenomenon is known as a Lunar Impact Flash (LIF), and its duration is approximately 0.01 to 1 second (e.g., Ortiz et al., 2000, Nature, 405, 921). When meteoroids enter the Earth's atmosphere, the interaction with molecules results in the emission of light, producing meteors; larger meteoroids can be observed as bright fireballs, although they occur infrequently, leaving their size and mass distribution functions unclear. Lunar observations using ground-based telescopes can cover a much larger area compared to meteor observations monitoring the Earth's atmosphere, thus allowing for an efficient study of centimeter-sized meteoroids that would be observed as fireballs. Observations of LIFs allow for an efficient investigation of the frequency and size distribution of centimeter-sized meteoroids impacting the Earth-Moon system. This research not only elucidates the size range that connects meteors and asteroids but also contributes to the physical understanding of the accretion and destruction history of the solar system.
Single-band observations of LIFs have provided insights into the size and mass distributions of meteoroids impacting the Moon (e.g., Suggs et al., 2014, Icarus, 238, 23). Simultaneous dual-band observations have further constrained the peak blackbody radiation temperature of LIFs, ranging from approximately 2000 to 4500 K (e.g., Liakos et al., 2024, A&A, 687, 14). In this presentation, we will review the key scientific findings from ground-based observations of LIFs and introduce our ongoing research on high-speed, simultaneous three-band observations of the lunar surface in visible and near-infrared wavelengths.