Remnant of Kepler's Supernova, SN 1604

Remnant of Tycho's Nova, SN 1572

Supernova remnant N49 in the Large Magellanic Cloud

A supernova remnant (SNR) is the structure resulting from the gigantic explosion of a star in a supernova. Supernova 1604, also known as Kepler's Supernova, Kepler's Nova or Kepler's Star, was a Supernova which occurred in the Milky Way, SN 1572 ( Tycho's Supernova, Tycho's Nova) "B Cassiopeiae" (B Cas or 3C 10 was a Supernova of Type Ia in the The Large Magellanic Cloud (LMC is a nearby Satellite galaxy of our own galaxy the Milky Way. A star is a massive luminous ball of plasma. The nearest star to Earth is the Sun, which is the source of most of the Energy on Earth A supernova (plural supernovae or supernovas) is a stellar Explosion. The supernova remnant is bounded by an expanding shock wave, and consists of ejected material expanding from the explosion, and the interstellar material it sweeps up and shocks along the way. For the music album by Converter see Shock Front For the 1977 horror film see Shock Waves A shock wave (also called

There are two possible routes to a supernova: either a massive star may run out of fuel, ceasing to generate fusion energy in its core, and collapsing inward under the force of its own gravity to form a neutron star or a black hole; or a white dwarf star may accumulate (accrete) material from a companion star until it reaches a critical mass and undergoes a thermonuclear explosion. A neutron star is a type of remnant that can result from the Gravitational collapse of a massive Star during a Type II, Type Ib or Type A black hole is a theoretical region of space in which the Gravitational field is so powerful that nothing not even Electromagnetic radiation (e A white dwarf, also called a degenerate dwarf, is a small Star composed mostly of Electron-degenerate matter. In Astrophysics, the term accretion is used for at least two distinct processes

In either case, the resulting supernova explosion expels much or all of the stellar material with velocities as much as 1% the speed of light, some 3,000 km s^-1. When this material collides with the surrounding circumstellar or interstellar gas, it forms a shock wave that can heat the gas up to temperatures as high as 10 million K, forming a plasma. In Physics and Chemistry, plasma is an Ionized Gas, in which a certain proportion of Electrons are free rather than being bound

Perhaps the most famous and best-observed young SNR was formed by SN 1987A, a supernova in the Large Magellanic Cloud that was discovered in 1987. SN 1987A was a Supernova in the outskirts of the Tarantula Nebula in the Large Magellanic Cloud, a nearby The Large Magellanic Cloud (LMC is a nearby Satellite galaxy of our own galaxy the Milky Way. Other well-known, older, supernova remnants include Tycho (SN 1572), a remnant named after Tycho Brahe, who recorded the brightness of its original explosion (AD 1572) and Kepler (SN 1604), named after Johannes Kepler. SN 1572 ( Tycho's Supernova, Tycho's Nova) "B Cassiopeiae" (B Cas or 3C 10 was a Supernova of Type Ia in the Tycho Brahe, born Tyge Ottesen Brahe ( December 14 1546 &ndash October 24 1601) was a Danish nobleman Supernova 1604, also known as Kepler's Supernova, Kepler's Nova or Kepler's Star, was a Supernova which occurred in the Milky Way, Johannes Kepler (ˈkɛplɚ ( December 27 1571 &ndash November 15 1630) was a German Mathematician, Astronomer The most recent remnant in our galaxy is G1.9+03, discovered in the galactic center and estimated to have gone supernova 140 years ago. Supernova remnant G19+03 is the youngest known Supernova remnant (SNR in the Milky Way Galaxy. ^[1]

Summary of stages

An SNR passes through the following stages as it expands:

1. Free expansion of the ejecta, until they sweep up their own weight in circumstellar or interstellar medium. This can last tens to a few hundred years depending on the density of the surrounding gas.
2. Sweeping up of a shell of shocked circumstellar and interstellar gas. This begins the Sedov-Taylor phase, which can be well modeled by a self-similar analytic solution. Strong X-ray emission traces the strong shock waves and hot shocked gas.
3. Cooling of the shell, to form a thin (< 1 pc), dense (1-100 million atoms per cubic metre) shell surrounding the hot (few million kelvin) interior. History The first direct measurements of an object at interstellar distances were undertaken by German Astronomer Friedrich Wilhelm Bessel in 1838 This is the pressure-driven snowplow phase. The shell can be clearly seen in optical emission from recombining ionized hydrogen and ionized oxygen atoms.
4. Cooling of the interior. The dense shell continues to expand from its own momentum, in a momentum-driven snowplow. This stage is best seen in the radio emission from neutral hydrogen atoms.
5. Merging with the surrounding interstellar medium. When the supernova remnant slows to the speed of the random velocities in the surrounding medium, after roughly a million years, it will merge into the general turbulent flow, contributing its remaining kinetic energy to the turbulence.

Types of supernova remnant

There are three types of supernova remnant:

• Shell-like, such as Cassiopeia A
• Composite, in which a shell contains a central pulsar wind nebula, such as G11. Cassiopeia A ( Cas A) is a Supernova remnant in the constellation Cassiopeia and the brightest extrasolar radio source in the sky with a flux A pulsar wind nebula (also known as " plerion " derived from Ancient Greek "pleres" meaning "full" - a term coined by Weiler & Panagia (1978 is 2-0. 3 or G21. 5-0. 9.
• Mixed-morphology (also called "thermal composite") remnants, in which central thermal X-ray emission is seen, enclosed by a radio shell. The thermal X-rays are primarily from swept-up interstellar material, rather than supernova ejecta. Examples of this class include the SNRs W28 and W44. (Confusingly, W44 additionally contains a pulsar and pulsar wind nebula; so it is simultaneously both a "classic" composite and a thermal composite. )

Origin of cosmic rays

Supernova remnants are the major source of Galactic cosmic rays. Galactic cosmic rays ( GCRs) consist of those Cosmic rays that enter the solar system from the outside ^[2][3][4] In 1949 Enrico Fermi proposed a model for the acceleration of cosmic rays through particle collisions with magnetic clouds in the interstellar medium. ^[5] This process, known as the "Second Order Fermi Mechanism", increases particle energy during head-on collisions, resulting in a steady gain in energy. A later model to produce Fermi Acceleration was generated by a powerful shock front moving through space. Particles that repeatedly cross the front of the shock can gain significant increases in energy. This became known as the "First Order Fermi Mechanism". ^[6]

Supernova remnants can provide the energetic shock fronts required to generate ultra-high energy cosmic rays. Observation of the SN 1006 remnant in the X-ray has shown synchrotron emission consistent with it being a source of cosmic rays^[2]. SN 1006 was a Supernova, widely seen on Earth beginning in the year 1006 CE Earth was about 7200 light-years away from the supernova This article concerns the physical phenomenon of synchrotron radiation However, for energies higher than about 10¹⁵ eV a different mechanism is required as supernova remnants cannot provide sufficient energy. ^[6]

See also

• List of supernova remnants
• Local Bubble
• Nova remnant
• Planetary nebula

References

External links

• Galactic SNR Catalogue (D. A. Green, University of Cambridge)
• Magellanic Cloud SNR Catalogues (R. Williams, University of Illinois at Urbana)
• NASA: Introduction to Supernova Remnants.
• NASA's Imagine: Supernova Remnants
• Supernova Remnant (UOttawa)
• Afterlife of a Supernova
• 2MASS images of Supernova Remnants
• An Article Discussing Ring Formation around certain Supernova