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<-   Atoms, molecules and spectra   ->
Star spectra
images/uvesdigitalisetypes.png
Copyright : Paris Observatory / ASM

A molecule is an assembly of atoms. A water molecule is made up of one oxygen and two hydrogen atoms.

Each atom and each molecule is associated with a group of lengths corresponding to energy transitions. The spectrum of a body is the ID of the chemical elements which make it up. The analysis of a complex spectrum gives the chemical composition and the abundance of each element.

Conclusion :The spectrum of a star/planet is therefore made up of a spectrum of a black body which depends on its temperature , and absorption rays which depend on the composition of its atmosphere. We see below the spectrum of several stars, from the warmest one (star 0) to the coolest one (star M).