此研究聚焦在恆星形成初期的兩個主題，首先是如何透過吸積周圍氣體與塵埃增長其質量，另外則是在太陽鄰近分子雲當中，尋找剛誕生的恆星與棕矮星。論文的第一部份利用涵蓋5.5年的JCMT瞬變巡天 (Transient survey) 850-micron 波段的觀測資料，監測8個古德帶 (Gould Belt) 當中的恆星形成區，尋找快速變亮的原始恆星。我們辨識出兩個暴亮源，一顆是位於獵戶座OMC~2/3分子雲當中的JW 566，它屬於第二型金牛座T型的雙星，於2016年偵測到閃焰，在450-micron 波段達 500±107 mJy/beam，而在 850-micron 波段達 466±47 mJy/beam，為有史以來在年輕恆星當中偵測到最明亮的次毫米波爆發。另一個暴亮源Source 2864，則是個類星體。這兩個事件雖然都不是原恆星吸積事件，但證實我們的分析方法有效而可靠。論文的第二部份利用客製的窄頻濾鏡，以廣角紅外觀測搜尋棕矮星。此W濾鏡中心波長大約在1.45-micron，是棕矮星及更冷的行星質量天體大氣當中，水分子吸收線之所在。我們使用此濾鏡觀測了年輕星團IC 348，及其旁邊的暗雲Barnard 5，兩者皆位於英仙座分子雲的東緣。我們以紅外光譜驗證了3顆在IC 348中未知的棕矮星，也在Barnard 5首次發現棕矮星。另外我們利用2MASS及WISE巡天篩選出年輕恆星，配合 Gaia 的視差與自行運動數據，探討分子雲當中恆星形成的過程，以及這些活動如何受到鄰近OB星協當中的大質量恆星影響。;My research focuses on the earliest stage of star formation, including how stars gain their masses by accretion from surrounding gas and dust, and comparison of the stellar and substellar samples in nearby molecular clouds. To this cause, data obtained by the JCMT Transient survey and the W-band Imaging survey was used. Analysis of five and a half years of the JCMT Transient Surveys 850-micron images monitoring observations toward eight Gould Belt star-forming regions to search for evidence of transient events or long-duration variability from faint sources. Two robust sources that show evidence for submillimeter variability were detected; the first being JW 566, a Class II T Tauri binary object in OMC 2/3 as an extraordinary submillimeter flare, which is unique, and the only clear single-epoch transient detection in this sample. In contrast, the second submillimeter variable identified in our analysis, Source 2864, is highly variable at all observed timescales. The source is most likely a background blazar but was previously classified as a highly extinct Class II object based on the Spitzer mid-IR photometry. New substellar objects were discovered using a custom-designed narrowband photometric filter, W-band at the CFHT, centered at the 1.45-micron absorption feature present in brown dwarf atmospheres. The region for observation and analysis was taken to be the young star cluster IC 348, and the neighbouring Barnard 5 dark cloud, both of which are at the eastern end of the Perseus star-forming complex. Spectroscopic observations using the SpeX instrument on the IRTF′s telescope confirm the existence of three previously unknown brown dwarfs in IC 348, further discovering the first brown dwarf in Barnard 5. Together with the young stellar population selected via near- and mid-infrared colors using the Two Micron All Sky Survey and the Wide-field Infrared Survey Explorer, the relation between stellar and substellar objects with the associated molecular clouds were diagnosed. Gaia EDR3 parallaxes and kinematics of the cloud members across the Perseus region were also used to propose the star formation scenario of the complex under influence of the nearby OB association.
