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Analysis and Interpretation of Astronomical Spectra 9

plained a minimum "dose" of electromagnetic radiation is generated, called “photon”, which
belongs to the Bosons within the "zoo" of elementary particles.

2.4 Properties of the Photons
– Without external influence photons have an infinitely long life
– Their production and “destruction” takes place in a variety of physical processes. Rele-

vant for the spectroscopy are electron transitions between different atomic orbital (de-
tails see later).
– A photon always moves with light speed. According to the Special Theory of Relativity
(STR) it can therefore possess no rest mass.

2.5 Photons – Carriers of Energy
Each photon has a specific frequency (or wavelength), which determines its energy – the
higher the frequency, the higher the energy of the photon (details see sect. 10.1).