Related Experiment Video
Updated: Jul 12, 2026

Applying X-ray Imaging Crystal Spectroscopy for Use as a High Temperature Plasma Diagnostic
Published on: August 25, 2016
X-ray Variability in the Hot Supergiant zgr Orionis
Abstract:
Hot massive stars represent only a small fraction of the stellar population of the galaxy, but their enormous luminosities make them visible over large distances. Therefore, they are ideal standard candles, used to determine distances of near galaxies. Their mass loss due to supersonic winds driven by radiation pressure contributes significantly to the interstellar medium and thus to the chemical evolution of galaxies. All hot stars are soft x-ray sources; in contrast to the sun with its highly variable x-ray flux, long time scale x-ray variability is not common among hot stars. An analysis is presented here of an unusual increase in x-ray flux observed with the roentgen observatory satellite during a period of 2 days for the hot supergiant zeta Orionis, the only episode of x-ray variability that has been found in a hot star. These observations provide the most direct evidence so far for the scenario of shock-heated gas in the winds of hot stars.
Related Concept Videos
X-ray Imaging
Atomic Spectroscopy: Effects of Temperature
At thermal equilibrium, the relative populations of excited and ground state atoms can be estimated using the Maxwell–Boltzmann distribution. For example, an increase in temperature from...
Atomic Emission Spectroscopy: Overview
Atomic Emission Spectroscopy: Interference
Flame Photometry: Overview
IR Spectrometers
