I was fascinated by the night sky from my childhood. By observing stars, star clusters, galaxies, and black holes, I would like to answer the following questions; how are they formed, how are they evolved, and what are the laws that govern the formation and the evolution of them?
My observational target is the central region of the Milky Way galaxy, where a massive black hole, star clusters, and a huge number of stars exist. However, we cannot observe visible light from them because of strong extinction by interstellar dust grains. Most of my scientific work is thus based on data in an infrared wavelength regime, where the amount of the interstellar extinction is less than 10-6 of the visible light. Images and spectra of the astronomical objects allow us to understand the spatial distribution, kinematics and elemental abundances of them.
 In the last seven years, we have observed a star orbiting around the supermassive black hole (SMBH) at the center of Milky Way. The star’s orbit is almost an elliptical, like the orbits of the planets in the Solar system (Figure 1). However, due to the strong gravity from SMBH, the Newton’s law does not work there. We have shown that Einstein’s general relativity is well predict the motion of stars near SMBH (Do et al. 2019, Science).

Figure 1. The orbital motion of stars around the supermassive black hole at the center of our Galaxy, from 1995 to 2018 (Do et al. 2019).