活動詳細資訊 Event Information
活動詳細資訊 Event Information
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活動訊息最後更新時間 : 2016-11-23 15:38:20
開始日期 Starting Date:2016-11-30  14:00
結束日期 Ending Date:2016-11-30  15:30
會議狀態 State:確定 Definitive
主/協辦單位 Organizer:天文及天文物理研究所 Institute of Astronomy and Astrophysics
活動地點 Venue:R1203 of the Astronomy-Mathematics Building, National Taiwan University
活動備忘 Event Memo:

Abstract
 

We present an outflow survey toward 20 Low Luminosity Objects (LLOs), namely protostars with an internal luminosity less than 0.2 Lsun. Although a number of studies have reported the properties of individual LLOs, the reasons for their low luminosity remain uncertain. To answer this question, we need to know the evolutionary status of LLOs. Protostellar outflows are found to widen as their parent cores evolve, and therefore, the outflow opening angle could be used as an evolutionary indicator. The infrared scattered light escapes out through the outflow cavity and highlights the cavity wall, giving us the opportunity to measure the outflow opening angle. Using the Canada-France-Hawaii Telescope, we detected outflows toward eight LLOs out of 20 at Ks band, and based on archival Spitzer IRAC1 images, we added four outflow-driving sources from the remaining 12 sources. By fitting these images with radiative transfer models, we derive the outflow opening angles and inclination angles. To study the widening of outflow cavities, we compare our sample with the young stellar objects from Arce & Sargent (2006) and Velusamy et al. (2014) in the plot of opening angle versus bolometric temperature taken as an evolutionary indicator. Our LLO targets match well the trend of increasing opening angle with bolometric temperature reported by Arce \& Sargent and are broadly consistent with that reported by Velusamy et al., suggesting that the opening angle could be a good evolutionary indicator for LLOs. Accordingly, we conclude that at least 40\% of the outflow-driving LLOs in our sample are young Class 0 objects.