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The direct-imaging exploration can obtain comprehensive physical information of exoplanets, which is a key technology to search for extraterrestrial life in the future. In this paper, based on our recent high-contrast imaging data of ground-based telescope, the newly discovered multi-star candidates are presented. In the early stage, combined with the ability of high-contrast imaging equipment for the exoplanets in the ground-based system, we select about 1000 targets from published works which are compiled using the catalogs released by Gaia. These targets are distributed in different young star clusters. Recently, we used Hale Telescope at Palomar Observatory to carry out high-contrast imaging observation on 42 of the above targets in the K-band. Most of the observed targets are 7.5–14 in the V-band. In 2019, after two rounds of observation, we discover six multi-star system candidates. It is however difficult to find out whether these targets are single-star or multi-star systems in Gaia DR2 (Data Release 2) catalog and Gaia EDR3 (early Data Release 3) catalog. [ABSTRACT FROM AUTHOR]

Due to its wide wavelength coverage, multi-resolution mode, and high transmission efficiency, the wide field multi-object spectrograph becomes the most common-used universal instrument in extremely large telescopes. It's still a great challenge to build the wide field multi-object spectrograph for a 30 m class telescope because of its sharply increased volume and budget. With the rapid development of astronomy and astrophysics, the innovation of astronomical technology is fundamentally required. In this paper, the research progress of different kinds of wide-field multi-object spectrographs is illustrated and reviewed, the recent status of conceptual designs and the instrument features of the wide field multi-object spectrographs of the three 30 m class telescopes in the world, especially the current effort made by the Chinese team for the wide field multi-object spectrograph of the Thirty Meter Telescope (TMT) are introduced. [ABSTRACT FROM AUTHOR]