Astrochemistry
Astrochemistry is the study of the chemical elements found in outer space, generally on larger scales than the Solar System, particularly in molecular gas clouds, and the study of their formation, interaction and destruction. As such, it represents an overlap of the disciplines of astronomy and chemistry. On the Solar System scale, the study of chemical elements is usually called cosmochemistry.
Detection of chemicals
Methods of detection
Astrochemistry involves the use of telescopes to measure various aspects of bodies in space, such as their temperature and composition. Findings from the use of spectroscopy in chemistry laboratories can be employed in determining the types of molecules in astronomical bodies (e.g. a star or an interstellar cloud). The various characteristics of molecules reveal themselves in their spectra, yielding a unique spectral representation corresponding to each type of molecule.
Limits of detection
However, there are limitations on measurements due to electromagnetic interference and, more problematic, the chemical properties of some molecules. For example, the most common molecule (H2, hydrogen gas), does not have a dipole moment, so it is not detected by radio telescopes. Much easier to detect with radio waves, due to its strong electric dipole moment, is CO (carbon monoxide).
Molecules detected
Over a hundred molecular species (including radicals and ions) have been reported so far, including a wide variety of organic compounds, such as alcohols, acids, aldehydes, and ketones. Some have claimed the detection of interstellar glycine,[1] the simplest amino acid, but this claim has stirred considerable controversy.[2] Research is progressing on the way interstellar and circumstellar molecules form and interact, and this research could have a profound impact on our understanding of the origin of life on Earth.
The sparseness of interstellar and interplanetary space results in some unusual chemistry, because symmetry-forbidden reactions cannot occur except on the longest of timescales. For this reason, molecules and molecular ions that are unstable on Earth can be highly abundant in space, for example the H3+ ion.
Nuclear reactions
Astrochemistry overlaps strongly with astrophysics and nuclear physics in characterizing the nuclear reactions that occur in stars, the consequences for stellar evolution, as well as stellar 'generations'. Indeed, the nuclear reactions in stars produce every naturally occurring chemical element. As the stellar 'generations' advance, the mass of the newly formed elements increases. A first-generation star uses elemental hydrogen (H) as a fuel source and produces helium (He). Hydrogen is the most abundant element, and it is the basic building block for all other elements as its nucleus has only one proton.
Gravitational pull toward the center of a star creates massive amounts of heat and pressure, which cause nuclear fusion. Through the process of merging nuclear mass, heavier elements are formed. Lithium, carbon, nitrogen, and oxygen are examples of elements that form in stellar fusion. After many stellar generations, very heavy elements are formed, such as iron and lead.
See also
- Astronomy
- List of molecules in interstellar space
- Molecular astrophysics
- Interstellar medium
ReferencesISBN links support NWE through referral fees
- International Astronomical Union, Dariusz C. Lis, Geoffrey A. Blake, and Eric Herbst. 2006. Astrochemistry: Recent Successes and Current Challenges : Proceedings of the 231st Symposium of the International Astronomical Union Held in Pacific Grove, California, USA, August 29 - September 2, 2005. IAU symposium and colloquium proceedings series. Cambridge, UK: Cambridge University Press. ISBN 978-0521852029.
- Shaw, Andrew M. 2006. Astrochemistry: From Astronomy to Astrobiology. Chichester, England: John Wiley & Sons. ISBN 978-0470091371.
- Singh, P.D., ed. 1997. Astrochemistry of Cosmic Phenomena. International Astronomical Union Symposia. Berlin: Springer. ISBN 0792318250.
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External links
- Astrochemistry - division of the International Astronomical Union. Retrieved September 30, 2007.
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- ↑ Kuan YJ, Charnley SB, Huang HC, et al. (2003). Interstellar glycine. ApJ 593 (2): 848-867.
- ↑ Snyder LE, Lovas FJ, Hollis JM, et al. (2005). A rigorous attempt to verify interstellar glycine. ApJ 619 (2): 914-930.
