Knowra Circumstellar envelope Circumstellar envelope A region of gas and dust surrounding a star, often supplied by material expelled in stellar winds. Its structure and composition record how the star loses mass and interacts with its surroundings.
Stellar wind : A flow of charged particles and gas continuously or episodically escaping from a star. It carries much of the material that builds an envelope around an evolving star.
Circumstellar medium : Gas and dust in the space immediately surrounding a star, shaped by the star and its environment. The envelope is a form of circumstellar material, especially around stars losing mass.
Infrared astronomy : The study of celestial objects through infrared radiation. Cool circumstellar dust emits strongly in the infrared, making this wavelength range especially useful.
Mira variable : A pulsating red giant with large changes in visible brightness and a long period. Mira variables often lose mass through dense winds that form extended envelopes.
Mass loss : The reduction of a star’s mass as matter escapes into space. The rate and timing of mass loss set the envelope’s density and extent.
Interstellar medium : The gas, dust, and radiation occupying the space between stars in a galaxy. An expanding envelope eventually mixes into the surrounding interstellar medium.
Spectroscopy : The analysis of light by its wavelength to infer the properties of matter. Molecular and atomic spectral lines identify the envelope’s composition and motion.
OH/IR star : A heavily obscured, late-stage star detected through hydroxyl maser and infrared emission. Its strong dusty outflow makes the circumstellar envelope prominent at infrared and radio wavelengths.
Radiative transfer : The propagation of radiation through matter, including its absorption, emission, and scattering. It determines how envelope dust and gas shape the observed spectrum.
Asymptotic giant branch : A late evolutionary phase of low- to intermediate-mass stars marked by a cool, luminous atmosphere and strong mass loss. These stars commonly build extended, dusty envelopes through intense winds.
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