A statistical study towards high-mass BGPS clumps with the MALT90 survey


stars:formation;ISM:abundance;ISM:molecules;radio lines:ISM;ISM:kinematics and dynamics

stars:formation;ISM:abundance;ISM:molecules;radio lines:ISM;ISM:kinematics and dynamics
     In this work,we perform a statistical investigation towards 50 high-mass clumps using data from the Bolocam Galactic Plane Survey(BGPS)and Millimetre Astronomy Legacy Team 90-GHz survey(MALT90).Eleven dense molecular lines(N2H+(1–0),HNC(1–0),HCO+(1–0),HCN(1–0),HN13C(1–0),H13CO+(1–0),C2H(1–0),HC3N(10–9),SiO(2–1),13CS(2–1)and HNCO(44,0-30,3))are detected.N2H+ and HNC are shown to be good tracers for clumps in various evolutionary stages since they are detected in all the fields.The detection rates of N-bearing molecules decrease as the clumps evolve,but those of O-bearing species increase with evolution.Furthermore,the abundance ratios[N2H+]/[HCO+]and log([HC3N]/[HCO+])decline with log([HCO+])as two linear functions,respectively.This suggests that N+2H+ and HC3N transform to HCOas the clumps evolve.We also find that C2H is the most abundant molecule with an order of magnitude 10-8.In addition,three new infall candidates,G010.214–00.324,G011.121–00.128 and G012.215–00.118(a),are discovered to have large-scale infall motions and infall rates with an order of magnitude 10-3M⊙yr-1.


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