High Resolution Observations Of Acetone And P-containing Molecules In Star-forming Regions

We report high spatial resolution ALMA observations of CH₃COCH₃ lines toward I-RAS 16293-2422 in 145-147 GHz and 156-159 GHz bands.With the ALMA data,29 molecular transitions of CH₃COCH₃ are detected.Molecular line images clearly show that transitions originate mainly from two spatial components IRAS 16293A and IRAS 16293B,and radiation becomes more and more condensed with the gradual increase of energy levels.Under assumption of Local Thermodynamical Equilibrium?LTE?,we have calculated rotation temperature and column density based on multiple transitions of CH₃COCH₃.The rotation temperatures of 154 K and 192 K are derived for IRAS 16293A and IRAS 16293B,respectively.The estimated column densities are 5.9×10¹⁶ cm^-2 and 9.3×10¹⁶ cm^-2 for IRAS 16293A and IRAS 16293B,respectively.The H2 col-umn density are derived from the millimeter continuum observation,and the fractional abundance of CH₃COCH₃ relative to H2 are obtained to be?2.0-4.2?×10^-9.Compar-ing the spatial distribution and fractional abundance of CH₃COCH₃,we discuss possible chemical origination of CH₃COCH₃ in IRAS 16293-2422,in which CH₃COCH₃ may originate from grain-surface reaction,supports the grain-surface chemistry model.In addition,we have detected the CCP and PS in the typical massive star-forming re-gion Orion-KL.With the high resolution ALMA observations from 214 to 247 GHz,we have identified three CCP molecular transitions and one PS molecular transition.Under the LTE assumption in XCLASS,we obtained the rotational temperatures of the five e-mission source?Hot Core,Compact Ridge,IRc6,IRc7 and Swh?ranging from 60 to 87 K.The Compact Ridge has the lowest temperature and the Hot Core has the highest tem-perature.Finally,the column densities of CCP range from 3.6×10¹³ to 4.7×10¹⁴ cm^-2,the abundances relative to H2 are obtained ranging from 9.2×10^-11 to 1.5×10^-9.The column densities of PS range from 2.4×10¹³ to 1.5×10¹⁴ cm^-2,and the abundances relative to H2 are obtained ranging from 6.2×10^-11 to 4.8×10^-10.The two molecules have the largest abundance relative to H2 in Swh and the lowest abundance relative to H2 in Compact Ridge.The results suggest that the physical and chemical conditions of the emission source have a significant influence on the formation and depletion of interstellar molecules.