我們擬在年輕星團與恆星形成區當中搜尋並研究次恆星，也就是棕矮星與質量與行星相當的天體。 我們將利用CFHT 配備新設計的W 濾鏡，以指認含有水汽的低溫大氣層。這樣的光度觀測提供高 效率而可靠的候選天體名單，以便後續使用大型望遠鏡的紅外光譜認證。大部分目前已知的次恆 星都限於太陽附近。而這裡提出的計畫將發現最完整、質量最低、年齡不到兩百萬年的氣體天體， 以探究它們的形成過程。我們也將清點鄰近星團拋射出的低質量成員，藉以研究星團瓦解的動力 過程。另一方面我們也將利用 Subaru/HSC 找出極微弱，也就是極度年老的棕矮場星，以探討缺 乏複雜元素的低溫大氣性質與年輕棕矮星的差別。 ;We propose to search for and to characterize substellar objects, i.e., brown dwarfs and planet-mass objects in young star clusters and star-forming regions. A customized W filter sensitive to the water absorption in infrared wavelengths will be used on the CFHT to identify candidates with molecule-bearing cool atmospheres. The imaging survey will provide an efficient and reliable list of brown dwarfs for spectroscopic conformation by large telescopes. Most substellar objects known so far are in the field in immediate solar neighborhood. The project proposed here will uncover the most comprehensive sample of the least massive gaseous cosmic bodies when they are less than a couple million years old, i.e., at the epoch of their infancy to shed light of their formation history in relevance to stellar counterparts. We will also conduct a census of low-mass members which have been dynamically ejected from nearby star clusters, thereby diagnosing the cluster disintegration process. We will also make use of the Subaru/HSC data to identify very faint, i.e., extremely old field, brown dwarfs, in order to contrast the metal-deficient cool atmospheres with those of the young population.