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名稱Title
2018天文年會
國立金門大學
5月18日至20日

論文摘要

Study of Embedded X-ray Brown Dwarfs and Young Stellar Objects in IC 348

[ Oral ]

Bhavana LALCHAND, Po-Shih CHIANG, Wen-Ping CHEN National Central University, Taiwan(R.O.C)

Brown dwarfs have masses (15-80 MJup) below that required to maintain core hydrogen fusion. Such a sub stellar population in star-forming regions is the critical first step to understand their formation mechanism (do they form like stars, or like planets?). The sample also serves to bridge the knowledge of free-floating planets versus exoplanets. We have identified brown dwarf candidates via imaging detection of possible water absorption, one of the characteristics of cool atmospheres. Some of these are matched with X-ray sources and also with JCMT 850-micron emissions. We thus have a premium sample to study magnetic activity in substellar infancy. These embedded X-ray brown dwarfs have Lx/Lbol〖 ≥10〗^(-5)-〖10〗^(-4), to be compared with those for other young stellar populations, such as 〖10〗^(-4.5)-〖10〗^(-3) for T Tauri stars, 〖10〗^(-4)-〖10〗^(-6) for Herbig Ae/Be stars, or with 〖10〗^(-7) for OB stars. In late-M dwarfs, flaring is frequent and strong, suggesting that magnetic field persists, whereas in even cooler L and T type brown dwarfs, the dynamo process is expected to weaken due to neutral photospheres. Our brown dwarf sample is the most comprehensive in a young star cluster, and we present their spectral typing, X-ray and submillimeter properties. Keywords: brown dwarfs, young stellar objects, open clusters and associations: individual (IC 348), X-rays