Infrared excess
In astrophysics, the term infrared excess describes an unexpected excess of infrared radiation . An example of an observed infrared excess is Beta Pictoris .
Basics
As a first approximation , the radiation from stars or other astronomical objects can be described as that of a black body . By specifying a temperature of the star's surface , the distribution of electromagnetic radiation in the optical and infrared spectral range can be calculated using Planck's law of radiation . An infrared excess describes a significant excess of measured radiation in the infrared compared to the expected value according to Planck's law of radiation.
causes
An infrared excess of a system arises from
- a circumstellar shell made of dust , which absorbs radiation in the optical, warms up to a few hundred Kelvin and radiates the radiation in the infrared again, e.g. B. in dust, transition, protoplanetary or debris disks
- in the case of a circumstellar shell made of ionized gas by thermal bremsstrahlung
- an unresolved red or brown dwarf in a binary star system .
In addition, an excess of infrared can result from external influences:
- a background galaxy
- a foreground object
- Interstellar matter towards the star.
literature
- Helmut Scheffler, Hans Elsässer : Physics of the stars and the sun . 2nd revised and expanded edition. BI Wissenschaftsverlag, Mannheim 1990, ISBN 3-411-14172-7 .
- Chao-Jian Wu et al .: Bright 22 $ μ $ m Excess Candidates from WISE All-Sky Catalog and Hipparcos Main Catalog . In: Astrophysics. Solar and Stellar Astrophysics . 2013, arxiv : 1308.3848v1 .
Individual evidence
- ↑ The star for the weekend: Beta Pictoris . Astrodicticum Simplex on ScienceBlogs.de, May 24, 2008.