A stellar-wind bubble is a cavity
light-years across filled with hot gas blown into the
interstellar medium by the high-velocity (several thousand km/s)
stellar wind from a single massive
star of
type O or
B. Weaker stellar winds also blow bubble structures, which are also called astrospheres. The
heliosphere
The heliosphere is the magnetosphere, astrosphere and outermost atmospheric layer of the Sun. It takes the shape of a vast, bubble-like region of space. In plasma physics terms, it is the cavity formed by the Sun in the surrounding interstell ...
blown by the
solar wind
The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the sol ...
, within which all the major
planet
A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...
s of the
Solar System
The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...
are embedded, is a small example of a stellar-wind bubble.
Stellar-wind bubbles have a two-shock structure.
The freely-expanding stellar wind hits an inner termination shock, where its kinetic energy is thermalized, producing 10
6 K,
X-ray
An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...
-emitting
plasma. The hot, high-pressure, shocked wind expands, driving a shock into the surrounding interstellar gas. If the surrounding gas is dense enough (number densities
or so), the swept-up gas radiatively cools far faster than the hot interior, forming a thin, relatively dense shell around the hot, shocked wind.
See also
*
Wolf–Rayet nebula
A Wolf–Rayet nebula is a nebula which surrounds a Wolf–Rayet star.
WR nebulae have been classified in various ways. One of the earliest was by the nature and origin of the nebula:
* HII regions
* ejecta-type nebulae
* wind-blown bubbles
Th ...
References
Stellar astronomy
Galactic astronomy
Interstellar media
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