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Lecture 23- Interstellar Chemistry and Life After the Main Sequence

Lecture 23- Interstellar Chemistry and Life After the Main Sequence. Chemistry = (defined) as interaction of two (or more) molecules to form different molecules. Interstellar Chemistry. H 2 , CO, H 2 O, NH 3. How complicated does it get?.

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Lecture 23- Interstellar Chemistry and Life After the Main Sequence

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  1. Lecture 23- Interstellar Chemistry and Life After the Main Sequence Chemistry = (defined) as interaction of two (or more) molecules to form different molecules

  2. Interstellar Chemistry H2, CO, H2O, NH3 How complicated does it get?

  3. Our window on interstellar chemistry: microwave spectroscopy Each molecule has a unique “fingerprint” set of frequencies

  4. Example of an interstellar molecule Interstellar Acetic Acid, CH3COOH

  5. Notice other emission lines not identified

  6. Current State of Astrochemistry • Table of detected molecules • > 110 molecules found in interstellar space • The largest contain up to 13 atoms • Many, if not most, are organic • Nobody doubts there are more complicated species lurking out there (unidentified lines) • Connection to the origin of life?

  7. Next Topic: The Other Side of the Main Sequence. All stars in a cluster formed at the same time

  8. Look at the HR diagram of a cluster What can you say?

  9. Post-Main Sequence Stellar Evolution: Example Betelgeuse Lesson 1- Stars get bloated and red

  10. Post-Main Sequence Stellar Evolution • The course of evolution depends on mass • High Mass stellar evolution • Low Mass stellar evolution • The two kinds of evolution are quite similar for a while, then wildly diverge

  11. A star at the end of its Main Sequence Lifetime • No fuel source to keep up the central pressure. The core begins to contract under its own gravity

  12. Contraction continues until proton-proton cycle begins in shell around the core Calculations show that outer layers of star swell up to form a red giant

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