The composition of interstellar molecular clouds.

Area of Science:

• Astrochemistry
• Cometary Science
• Star Formation

Background:

• Interstellar chemistry provides insights into the composition of early solar system materials, including comets.
• Understanding the chemical conditions during star and planet formation is crucial for deciphering solar system origins.
• Comets serve as valuable archives of pristine material from the early solar system.

Purpose of the Study:

• To compare interstellar gas-phase chemistry in different star-forming environments with the chemical composition of comets.
• To investigate molecular abundances, isomer ratios (HCN/HNC), ortho/para ratios, and deuterium fractionation in interstellar clouds.
• To assess the chemical link between interstellar molecular clouds and cometary composition.

Main Methods:

• Focus on gas-phase chemical analysis within isolated dark clouds and hot cores.
• Comparison of general molecular abundances, specific isomer ratios (HCN/HNC), ortho/para ratios, and hydrogen/deuterium isotopic fractionation.
• Utilizing existing data and theoretical models for interstellar chemistry.

Main Results:

• Analysis of molecular abundances in interstellar environments relevant to star formation.
• Evaluation of isomer ratios, ortho/para ratios, and isotopic fractionation in gas-phase interstellar chemistry.
• Identification of chemical similarities and differences between interstellar clouds and comets.

Conclusions:

• Interstellar chemistry in various star-forming regions offers a baseline for understanding cometary composition.
• Gas-phase chemical processes in dark clouds and hot cores significantly influence the molecular inventory available for comets.
• Further detailed comparisons can refine models of solar system formation and evolution.