Chemistry and dust in star-forming regions of space
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| Title | Chemistry and dust in star-forming regions of space |
| Authors | |
| Abstract | Stars form from clouds of gas and dust in the interstellar medium. How the tenuous interstellar gas becomes a relatively dense star, and how a new star interacts with its environment, are currently lively and active fields of astronomical research. Since the ubiquitous cosmic dust makes the gas in denser clouds opaque to visual radiation, the main way that we can probe regions of star formation is by detecting radio emissions from molecules that are formed in the gas during the collapse. About 130 different molecular species have been detected in interstellar clouds. Most of these molecular species are formed in a variety of gas phase reactions, but some species depend on surface reactions for their formation. Understanding these chemical routes helps us to describe in detail the physical conditions in the gas during the collapse that leads to star formation and in the interaction of the new star with the cloud in which it was formed. We give three examples of such interactions: We describe how the interaction of a newly-formed hot star interacts with the material close to the star but which was not incorporated in it. We show that the molecules that can be seen in such situations were until recently frozen-out as ices on the surfaces of dust grains. Many young stars have outflows in the form of well-collimated high-velocity jets that impact on nearby interstellar gas to create shocked regions. We show that these shocked regions illuminate and modify the chemistry of those regions. The characteristic chemistry arising enables us to describe the nature of the jet/cloud interaction in detail. Stellar jets widen into general outflows that encounter clumps of denser gas. The outflow from a massive star usually ionised. The interaction between such an outflow and a pre-existing clump creates a characteristic interface chemistry. We describe recent observations that appear to be the first detection of such an interface in a region in which massive stars are forming. |
| Publisher | Accademia Peloritana dei Pericolanti |
| Date | 2009-11-25 |
| Source | 0365-0359 |
| Rights | Articles and conference papers published in Atti della Accademia Peloritana dei Pericolanti – Classe di Scienze Fisiche, Matematiche e Naturali are distributed under the terms and conditions of a Creative Commons Attribution 3.0 Unported License (effective since 2009, Vol. 87). Correspondingly, authors who publish with this journal agree to the following terms:Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work´s authorship and initial publication in this journal.Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal´s published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access). |