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TRAO Multi-beam Legacy Survey of Nearby Filamentary Molecular Clouds : Progress Report
ShinYoung Kim,Eun Jung Chung,Chang Won Lee,Philip C. Myers,Paola Caselli,Mario Tafalla,Gwanjeong Kim,Miryang Kim,Archana Soam,Maheswar Gophinathan,Tie Liu,Kyounghee Kim,Woojin Kwon,Jongsoo Kim 한국천문학회 2017 天文學會報 Vol.42 No.1
DENSE MOLECULAR CORES BEING EXTERNALLY HEATED
Kim, Gwanjeong,Lee, Chang Won,Gopinathan, Maheswar,Jeong, Woong-Seob,Kim, Mi-Ryang American Astronomical Society 2016 The Astrophysical journal Vol.824 No.2
<P>We present results of our study of eight dense cores, previously classified as starless, using infrared (3-160 mu m) imaging observations with the AKARI telescope and molecular line (HCN and N2H+) mapping observations with the KVN telescope. Combining our results with the archival IR to millimeter continuum data, we examined the starless nature of these eight cores. Two of the eight cores are found to harbor faint protostars having luminosities of similar to 0.3-4.4 L-circle dot The other six cores are found to remain starless and probably are in a dynamically transitional state. The temperature maps produced using multi-wavelength images show an enhancement of about 3-6K toward the outer boundary of these cores, suggesting that they are most likely being heated externally by nearby stars and/or interstellar radiation fields. Large virial parameters and an overdominance of red asymmetric line profiles over the cores may indicate that the cores are set into either an expansion or an oscillatory motion, probably due to the external heating. Most of the starless cores show a coreshine effect due to the scattering of light by the micron-sized dust grains. This may imply that the age of the cores is of the order of similar to 10(5) years, which is consistent with the timescale required for the cores to evolve into an oscillatory stage due to external perturbation. Our observational results support the idea that the external feedback from nearby stars and/or interstellar radiation fields may play an important role in the dynamical evolution of the cores.</P>
A SEARCH FOR VERY LOW-LUMINOSITY OBJECTS IN GOULD BELT CLOUDS
Kim, Mi-Ryang,Lee, Chang Won,Dunham, Michael M.,Evans II, Neal J.,Kim, Gwanjeong,Allen, Lori E. American Astronomical Society 2016 The Astrophysical journal Supplement series Vol.225 No.2
<P>We present the results of a search for Very Low-Luminosity Objects (VeLLOs) in the Gould Belt (GB) clouds using infrared and sub-millimeter (sub-mm) data from 1.25 to 850 mu m and our N2H+ (J = 1-0) observations. We modified the criteria by Dunham et al.. to select the VeLLOs in the GB clouds, finding 95 VeLLO candidates, 79 of which are newly identified in this study. Out of 95 sources, 44 were detected in both sub-mm continuum and N2H+ emission and were classified as Group A (the VeLLOs), and 51 sources detected in either sub-mm emission or N2H+ emission were classified with Group B as candidate VeLLOs. We find that these VeLLOs and the candidates are forming in environments different from those of the likely VeLLOs. Seventy-eight sources are embedded within their molecular clouds, and thus are likely VeLLOs forming in a dense environment. The remaining 17 sources are located in low-level extinction regions (A(V) < 1) connected to the clouds, and can be either background sources or candidate substellar objects forming in an isolated mode. The VeLLOs and the candidates are likely more luminous and their envelopes tend to be more massive in denser environments. The VeLLOs and the candidates are more populous in the clouds where more YSOs form, indicating that they form in a manner similar to that of normal YSOs. The bolometric luminosities and temperatures of the VeLLOs are compared to predictions of episodic accretion models, showing that the low luminosities for most VeLLOs can be well explained by their status in the quiescent phases of a cycle of episodic mass accretion.</P>