infrared excess

{{Short description|Measurement of an astronomical source}}

An infrared excess is a measurement of an astronomical source, typically a star, that in their spectral energy distribution has a greater measured infrared flux than expected by assuming the star is a blackbody radiator. Infrared excesses are often the result of circumstellar dust heated by starlight and reemitted at longer wavelengths. They are common in young stellar objects and evolved stars on the asymptotic giant branch or older.{{Cite journal|last1=Cotten|first1=Tara H.|last2=Song|first2=Inseok|journal=The Astrophysical Journal Supplement Series|language=en|volume=225|issue=1|pages=15|doi=10.3847/0067-0049/225/1/15|issn=0067-0049|title=A Comprehensive Census of Nearby Infrared Excess Stars|year=2016|arxiv=1606.01134|bibcode=2016ApJS..225...15C|s2cid=118438871 |doi-access=free }}

In addition, monitoring for infrared excess emission from stellar systems is one possible method that could enable a search for large-scale stellar engineering projects of a hypothetical extraterrestrial civilization; for example a Dyson sphere or Dyson swarm.{{Cite web | url=http://m.space.com/24269-how-to-search-for-alien-civilizations.html | title=Incredible Technology: How to Search for Advanced Alien Civilizations | website=Space.com | access-date=2014-08-22 | archive-date=2015-09-29 | archive-url=https://web.archive.org/web/20150929213551/http://m.space.com/24269-how-to-search-for-alien-civilizations.html | url-status=dead }} This infrared excess would be the outcome of the waste heat emitted by the aforementioned structures if they are considered blackbodies at temperatures close to 300 K. {{Cite journal|last=Dyson|first=Freeman J.|date=1960-06-03|title=Search for Artificial Stellar Sources of Infrared Radiation|journal=Science|language=en|volume=131|issue=3414|pages=1667–1668|doi=10.1126/science.131.3414.1667|issn=0036-8075|pmid=17780673|bibcode=1960Sci...131.1667D|s2cid=3195432}}{{Cite journal|last1=Wright|first1=J. T.|last2=Mullan|first2=B.|last3=Sigurdsson|first3=S.|last4=Povich|first4=M. S.|journal=The Astrophysical Journal|language=en|volume=792|issue=1|pages=26|doi=10.1088/0004-637X/792/1/26|issn=0004-637X|title=The Ĝ Infrared Search for Extraterrestrial Civilizations with Large Energy Supplies. I. Background and Justification|year=2014|arxiv=1408.1133|bibcode=2014ApJ...792...26W|doi-access=free}}