The terms galactic corona and gaseous corona have been used in the first decade of the 21st century to describe a hot,
ion
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...
ised, gaseous component in the
galactic halo
A galactic halo is an extended, roughly spherical component of a galaxy which extends beyond the main, visible component. Several distinct components of galaxies comprise the halo:
* the stellar halo
* the galactic corona (hot gas, i.e. a plas ...
of the
Milky Way
The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked ey ...
. A similar body of very hot and tenuous gas in the halo of any
spiral galaxy
Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work ''The Realm of the Nebulae''[galactic disc
A galactic disc (or galactic disk) is a component of disc galaxies, such as spiral galaxies and lenticular galaxies. Galactic discs consist of a stellar component (composed of most of the galaxy's stars) and a gaseous component (mostly compose ...]
ejecting hot gas.
The hypothesis is that a single
supernova and then its
supernova remnant
A supernova remnant (SNR) is the structure resulting from the explosion of a star in a supernova. The supernova remnant is bounded by an expanding shock wave, and consists of ejected material expanding from the explosion, and the interstellar ma ...
both produce hot ionized gas that supplies an individual “galactic fountain”. The expelled material forms a
giant bubble of high-pressure, low density, hot gas in the denser, cooler gas and dust of the
galactic disc
A galactic disc (or galactic disk) is a component of disc galaxies, such as spiral galaxies and lenticular galaxies. Galactic discs consist of a stellar component (composed of most of the galaxy's stars) and a gaseous component (mostly compose ...
. At least some of those bubbles extend high or low enough, vertically, to pierce through the denser disk, and form “chimneys” which exhaust the hot gas into the halo, analogous to a terrestrial
geyser
A geyser (, ) is a spring characterized by an intermittent discharge of water ejected turbulently and accompanied by steam. As a fairly rare phenomenon, the formation of geysers is due to particular hydrogeological conditions that exist only ...
spewing out water and steam that is much hotter and much less dense than the surrounding earth, heated by a source hidden deep below.
As the expelled gas in the galactic corona cools, it falls back into the
galactic disc
A galactic disc (or galactic disk) is a component of disc galaxies, such as spiral galaxies and lenticular galaxies. Galactic discs consist of a stellar component (composed of most of the galaxy's stars) and a gaseous component (mostly compose ...
, guided by the disc's own gravitational attraction, enriching the
gas and dust in the disc with the heavy elements (loosely termed
“metals” by astronomers) which were produced in supernova precursors, and during
supernova explosions.
Current research
Galactic coronas have been and are currently being studied extensively, in the hope of gaining a further understanding of galaxy formation.
[
However, considering how galaxies differ in shape and size, no particular theory has been able to adequately explain how all galactic coronas are formed and maintained.][
]
See also
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References
External links
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{{DEFAULTSORT:Galactic Corona
Corona
Corona