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名稱Title
2021天文年會
國立嘉義大學蘭潭校區
5月21日至23日

論文摘要

A hunt for variability in YSOs using JCMT Scuba-2 and for young low-mass brown dwarfs using W-filter

[ Oral ]

Bhavana Lalchand (National Central University), Wen-Ping Chen (National Central University)

Observations of temporal brightness and variability of stars provide physical insights to diagnose the stellar structure, e.g. the convective/dynamo mechanism. During the earliest phase of stellar assembly, when a protostar is vigorously accreting from circumstellar material, sporadic brightening events led by outflows (flares) are expected. Owing to the enshrouding dusty circumstellar material, optical/infrared detection is ineffective in detecting such protostellar flares. Here we report a dedicated program to monitor, on a monthly cadence to measure the accretion variability of young stellar objects in star-forming regions with the James Clerk Maxwell Telescope (JCMT) using the SCUBA-2 bolometer array. This is the first time-domain submillimeter program, being carried out since 2015 for eight nearby star-forming regions such as IC348, NGC1333, Ophiuchus Core, among others. The program has successfully detected known 182 protostars (Class 0) and 800 disk sources (T-Tauri stars). A particularly important event in the stellar evolution is the emergence of flares during various magnetic reconnection led gyro-synchrotron radiation. We report the recent observation of such an extraordinary sub-mm flare by a T-Tauri binary JW566 and present the detection algorithm for such events. We will also present the detection of young low mass stars in the active star forming region of IC 348 by doing a deep photometric survey using a custom 1.45 μm filter (W-band) as well as standard J and H near-IR filters. We select our candidates based on reddening-insensitive index (Q) by combining J, H and W-band photometry. Further, we will show the cross-correlation between the JCMT SCUBA-2 850 μm emission and young-brown dwarfs to study the evolution of these low-mass objects.