Spectral energy distribution
{{Other uses|Sed (disambiguation)}}
{{More citations needed|date=December 2009}}
File:Example data processed by theSkyNet POGS distributed computing project.png (upper right) obtained by combining data at many different wavelengths, e.g. UV, visible, and infrared (left)]]
A spectral energy distribution (SED) is a plot of energy versus frequency or wavelength of light (not to be confused with a 'spectrum' of flux density vs frequency or wavelength).{{cite web|title=SED plots - CoolWiki|url=http://coolwiki.ipac.caltech.edu/index.php/SED_plots|website=coolwiki.ipac.caltech.edu|language=en|accessdate=27 February 2018}} It is used in many branches of astronomy to characterize astronomical sources. For example, in radio astronomy they are used to show the emission from synchrotron radiation, free-free emission and other emission mechanisms. In infrared astronomy, SEDs can be used to classify young stellar objects.
Detector for spectral energy distribution
The count rates observed from a given astronomical radiation source have no simple relationship to the flux from that source, such as might be incident at the top of the Earth's atmosphere.{{ cite journal |author=Dolan JF |title=The Direct Reduction of Astronomical X-Ray Spectra |journal= Astrophys. Space Sci. |date=Aug 1972 |volume=17 |issue=2 |pages=472–81 |doi=10.1007/BF00642917 |bibcode=1972Ap&SS..17..472D |s2cid=123125127 }} This lack of a simple relationship is due in no small part to the complex properties of radiation detectors.
These detector properties can be divided into
- those that merely attenuate the beam, including
- #residual atmosphere between source and detector,
- #absorption in the detector window when present,
- #quantum efficiency of the detecting medium,
- those that redistribute the beam in detected energy, such as
- #fluorescent photon escape phenomena,
- #inherent energy resolution of the detector.
See also
References
{{Reflist}}
Further reading
- {{ cite book |author=Eberhard Haug|author2=Werner Nakel|name-list-style=amp|title=The elementary process of Bremsstrahlung |date= 2004 |page =Scientific lecture notes in physics, vol. 73 |publisher=World Scientific |location=River Edge NJ |isbn=978-981-238-578-9 |url=https://books.google.com/books?id=v4FMtIwTri8C&q=bremsstrahlung+haug }}
- {{cite web|title=Fitting the spectral energy distributions of galaxies|url=http://www.sedfitting.org/SED08/Paper_vs1.0_online/walcher_ms.html|author=Jakob Walcher|author2=Brent Groves|author3=Tamás Budavári|author4=Daniel Dale|url-status=dead|archiveurl=https://web.archive.org/web/20140814041031/http://www.sedfitting.org/SED08/Paper_vs1.0_online/walcher_ms.html|archivedate=2014-08-14}}
External links
- [https://web.archive.org/web/20031108030727/http://heasarc.nasa.gov/ The High Energy Astrophysics Science Archive Research Center (HEASARC) at NASA]
- [http://www.scienceofspectroscopy.info The Science of Spectroscopy] {{Webarchive|url=https://web.archive.org/web/20190323134512/http://www.scienceofspectroscopy.info/ |date=2019-03-23 }}
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Category:Applied and interdisciplinary physics
Category:Observational astronomy
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