Prebiotic Astrochemistry and the Formation of Molecules of Astrobiological Interest in Interstellar Clouds and Protostellar Disks

摘要

Despite the generally hostile nature of the environments involved, chemistry does occur in space. Molecules are seen in environments that span a wide range of physical and chemical conditions and that clearly were created by a multitude of chemical processes, many of which differ substantially from those associated with traditional equilibrium chemistry. The wide range of environmental conditions and processes involved with chemistry in space yields complex populations of materials, and because the elements H, C, O, and N are among the most abundant in the universe, many of these are organic in nature, including some of direct astrobiological interest. Much of this chemistry occurs in "dense" interstellar clouds and protostellar disks surrounding forming stars because these environments have higher relative densities and more benign radiation fields than in stellar ejectae or the diffuse interstellar medium. Because these are the environments in which new planetary systems form, some of the chemical species made in these environments are expected to be delivered to the surfaces of planets where they can potentially play key roles in the origin of life. Because these chemical processes are universal and should occur in these environments wherever they are found, this implies that some of the starting materials for life are likely to be widely distributed throughout the universe.