The TOP-SCOPE Survey of Planck Galactic Cold Clumps: Survey Overview and Results of an Exemplar Source, PGCC G26.53+0.17
Authors: Liu Tie , Kim Kee-Tae , Juvela Mika , Wang Ke , Tatematsu Ken’ichi , Francesco James Di , Liu Sheng-Yuan , Wu Yuefang , Thompson Mark , Fuller Gary , Eden David , Li Di , Ristorcelli I. , Kang Sung-ju , Lin Yuxin , Johnstone D. , He J. H. , Koch P. M. , Sanhueza Patricio , Qin Sheng-Li , Zhang Q. , Hirano N. , Goldsmith Paul F. , Evans II Neal J. , White Glenn J. , Choi Minho , Lee Chang Won , Toth L. V. , Mairs Steve , Yi H.-W. , Tang Mengyao , Soam Archana , Peretto N. , Samal Manash R. , Fich Michel , Parsons Harriet , Yuan Jinghua , Zhang Chuan-Peng , Malinen Johanna , Bendo George J. , Rivera-Ingraham A. , Liu Hong-Li , Wouterloot Jan , Li Pak Shing , Qian Lei , Rawlings Jonathan , Rawlings Mark G. , Feng Siyi , Aikawa Yuri , Akhter S. , Alina Dana , Bell Graham , Bernard J.-P. , Blain Andrew , Bőgner Rebeka , Bronfman L. , Byun D.-Y. , Chapman Scott , Chen Huei-Ru , Chen M. , Chen Wen-Ping , Chen X. , Chen Xuepeng , Chrysostomou A. , Cosentino Giuliana , Cunningham M. R. , Demyk K. , Drabek-Maunder Emily , Doi Yasuo , Eswaraiah C. , Falgarone Edith , Fehér O. , Fraser Helen , Friberg Per , Garay G. , Ge J. X. , Gear W. K. , Greaves Jane , Guan X. , Harvey-Smith Lisa , HASEGAWA Tetsuo , Hatchell J. , He Yuxin , Henkel C. , Hirota T. , Holland W. , Hughes A. , Jarken E. , Ji Tae-Geun , Jimenez-Serra Izaskun , Kang Miju , Kawabata Koji S. , Kim Gwanjeong , Kim Jungha , Kim Jongsoo , Kim Shinyoung , Koo B.-C. , Kwon Woojin , Kuan Yi-Jehng , Lacaille K. M. , Lai Shih-Ping , Lee C. F. , Lee J.-E. , Lee Y.-U. , Li Dalei , Li Hua-bai , Lo N. , Lopez John A. P. , Lu Xing , Lyo A-Ran , Mardones D. , Marston A. , McGehee P. , Meng F. , Montier L. , Montillaud Julien , Moore T. , Morata O. , Moriarty-Schieven Gerald H. , Ohashi S. , Pak Soojong , Park Geumsook , Paladini R. , Pattle Kate M , Pech Gerardo , Pelkonen V.-M. , Qiu K. , Ren Zhi-Yuan , Richer John , Saito M. , Sakai Takeshi , Shang H. , Shinnaga Hiroko , Stamatellos Dimitris , Tang Y.-W. , Traficante Alessio , Vastel Charlotte , Viti S. , Walsh Andrew , Wang Bingru , Wang Hongchi , Wang Junzhi , Ward-Thompson D. , Whitworth Anthony , Xu Ye , Yang J. , Yang Yao-Lun , Yuan Lixia , Zavagno A. , Zhang Guoyin , Zhang H.-W. , Zhou Chenlin , Zhou Jianjun , Zhu Lei , Zuo Pei , Zhang Chao 
Published: February 2018

Abstract
The low dust temperatures (<14 K) of Planck Galactic cold clumps (PGCCs) make them ideal targets to probe the initial conditions and very early phase of star formation. “TOP-SCOPE” is a joint survey program targeting ∼2000 PGCCs in J = 1–0 transitions of CO isotopologues and ∼1000 PGCCs in 850 μm continuum emission. The objective of the “TOP-SCOPE” survey and the joint surveys (SMT 10 m, KVN 21 m, and NRO 45 m) is to statistically study the initial conditions occurring during star formation and the evolution of molecular clouds, across a wide range of environments. The observations, data analysis, and example science cases for these surveys are introduced with an exemplar source, PGCC G26.53+0.17 (G26), which is a filamentary infrared dark cloud (IRDC). The total mass, length, and mean line mass (M/L) of the G26 filament are ∼6200 M
☉, ∼12 pc, and ∼500 M
☉ pc−1, respectively. Ten massive clumps, including eight starless ones, are found along the filament. The most massive clump as a whole may still be in global collapse, while its denser part seems to be undergoing expansion owing to outflow feedback. The fragmentation in the G26 filament from cloud scale to clump scale is in agreement with gravitational fragmentation of an isothermal, nonmagnetized, and turbulent supported cylinder. A bimodal behavior in dust emissivity spectral index (β) distribution is found in G26, suggesting grain growth along the filament. The G26 filament may be formed owing to large-scale compression flows evidenced by the temperature and velocity gradients across its natal cloud.