Supernova Remnants - Chandra X-ray Observatory

crab nebula 

W49b 

Supernovas that signal the end of massive 

stars are some of the most dramatic events 

in the cosmos. With its unique mirrors and 

instrumentation, Chandra has captured these 

celestial explosions in spectacular X-ray 

images. These titanic events send shock waves 

rumbling through space and create giant 

bubbles of multimillion-degree Celsius gas. 

hTTp://Chandra.harvard.edu 

Cassiopeia a 

DEM L71 

G21.5-0.9 

N132D 

Kepler 

Tycho 

Chandra’s X-ray images enable astronomers 

to determine the energy, composition, and 

dynamics of these explosions. In the centers of 

many of these bubbles, Chandra has revealed 

the presence of pulsars—rapidly rotating, highly 

magnetized neutron stars—that are pumping 

wave after wave of extremely energetic matter 

and antimatter particles into space.

A Look at Supernova Remnants with the Chandra X-ray Observatory 

every 50 years or so, a massive star in our Galaxy 

blows itself apart in a supernova explosion. Superno - 

vas are one of the most violent events in the universe, 

and the force of the explosion generates a blinding 

flash of radiation, as well as shock waves analogous 

to sonic booms. 

There are two types of supernovas: Type II, where a 

massive star explodes; and Type Ia, where a white 

dwarf collapses because it has pulled too much mate - 

rial from a nearby companion star onto itself. 

The general picture for a Type II supernova goes some - 

thing like this. When the nuclear power source at the 

center or core of a star is exhausted, the core col - 

lapses. In less than a second, a neutron star (or black 

hole, if the star is extremely massive) is formed. as infalling 

matter crashes down on the neutron star, tem - 

peratures rise to billions of degrees Celsius. Within 

hours, a catastrophic explosion occurs, and all but the 

central neutron star is blown away at speeds in excess 

of 50 million kilometers per hour. a thermonuclear 

shock wave races through the now expanding stellar 

debris, fusing lighter elements into heavier ones and 

producing a brilliant visual outburst that can be as 

intense as the light of several billion Suns! 

The matter thrown off by the explosion plows through 

the surrounding gas producing shock waves that create 

a shell of multimillion - degree gas and high -energy 

particles called a supernova remnant. The supernova 

remnant will produce intense radio and X - radiation for 

thousands of years. 

In several young supernova remnants the rapidly rotat - 

ing neutron star at the center of the explosion gives off 

pulsed radiation at X-ray and other wavelengths, and 

creates a magnetized bubble of high-energy particles 

whose radiation can dominate the appearance of the 

remnant for a thousand years or more. 

eventually, after rumbling across several thousand light 

years, the supernova remnant will disperse. Supernovas 

heat the interstellar gas, seed it with heavy elements, 

Crab Nebula: The Crab nebula was first observed by Chinese astronomers in 1054 a.d., and this 

stellar debris left behind from a supernova explosion has since become one of the most studied 

objects in the sky. This image from Chandra provides a dramatic look at the activity generated 

by the pulsar (white dot near the center of the image) in the Crab nebula. The inner X-ray ring is 

thought to be a shock wave that marks the boundary between the surrounding nebula and the flow 

of matter and antimatter particles from the pulsar. energetic shocked particles move outward to 

brighten the outer ring and produce an extended X-ray glow. The jets perpendicular to the ring are 

due to matter and antimatter particles spewing out from the poles of the pulsar. 

G21.5-0.9: This image, made by combining 150 hours of archived Chandra data, shows the remnant 

of a supernova explosion. The central bright cloud of high-energy electrons is surrounded by a 

distinctive shell of hot gas. The shell is due to a shock wave generated as the material ejected by 

the supernova plows into interstellar matter. although many supernovas leave behind bright shells, 

others do not. This supernova remnant was long considered to be one without a shell until it was 

revealed by Chandra. 

and trigger the collapse of giant clouds of cool dust and 

gas to form a new generation of stars. It is probable that 

a supernova led to the formation of our solar system 

some five billion years ago and provided the chemical 

elements necessary for life on earth. 

The cloud that collapsed to form the Sun and its plan - 

ets was composed mostly of hydrogen and helium, but 

it was enriched with heavier elements, among them 

carbon, nitrogen, oxygen, silicon, sulfur, and iron. 

These elements are manufactured deep in the interior 

of massive stars and would, for the most part, remain 

there if not for the cataclysmic supernova explosions. 

astronomers are using Chandra data to compile detailed 

maps of supernova remnants that show the variations 

in temperature of the hot gas, the total energy of the 

shock wave, and the quantity and location of vari - 

ous elements. Chandra has also been used to observe 

recent supernova events. These observations will 

allow astronomers to refine and test theories of the 

explosion and the events leading up to it. 

CIrCuMSTeLLar 

GaS 

ShoCKed 

eJeCTa 

CooL 

eJeCTa 

ForWard 

ShoCK Wave 

IllustratIon of shock Waves In supernova remnants: 

The expansion of the ejecta into the circumstellar gas from 

a supernova explosion generates a forward shock wave that 

speeds ahead of the ejecta. Like an extreme version of sonic 

booms produced by the supersonic motion of airplanes, the 

forward shock wave produces sudden, large changes in pressure 

and temperature behind the shock wave (purple). The hot, high 

pressure gas (purple) behind the forward shock expands and 

pushes back on the ejecta, causing a reverse shock that heats 

the ejecta (orange). eventually, the reverse shock wave will 

traverse the cool ejecta (blue) and heat it. 

Kepler’s superNova remNaNt: In 1604, Johannes Kepler was among those who witnessed a 

“new star” in the western sky. Four hundred years later, Chandra is helping unravel the mysteries 

of the expanding remains of what is now called Kepler’s supernova. Modern astronomers know that 

Kepler’s supernova is a fast moving shell of iron-rich material from the exploded star, about 14 light 

years across, surrounded by an expanding shock wave that is sweeping up interstellar gas and dust. 

Chandra’s X-ray vision allows astronomers to analyze regions where high-energy particles glow due 

to their multimillion-degree temperatures. 

N132D: Chandra’s image of n132d shows a beautiful, complex remnant of the explosion of a massive 

star. The horseshoe shape of the remnant is thought to be due to shock waves from the collision of the 

supernova ejecta with cool giant gas clouds. as the shock waves move through the gas, they heat it to 

millions of degrees Celsius, producing the glowing X-ray shell. n132d is about 180,000 light years from 

earth in the Large Magellanic Cloud, a small companion galaxy to the Milky Way.

More about 

Chandra’s Supernova Remnants... 

Cassiopeia a: This extraordinarily deep Chandra image shows Cassiopeia a (Cas a, for short), the 

youngest supernova remnant in the Milky Way. analysis of Cassiopeia a shows that this supernova 

remnant accelerates electrons to enormous energies. The blue, wispy arcs reveal the acceleration 

is taking place in an expanding shock wave generated by the explosion that destroyed the progenitor 

star. This acceleration is close to the theoretical limit and provides strong evidence that 

supernova remnants are key sites for generating cosmic rays, mysterious high-energy particles that 

bombard the earth. 

Credits — Crab Nebula: NASA/CXC/SAO/F.Seward et al.; G21.5-0.9: NASA/CXC/U.Manitoba/H.Matheson & S.Safi-Harb; Kepler’s SNR: NASA/CXC/ 

NCSU/S.Reynolds et al.; N132D: NASA/CXC/NCSU/K.J.Borkowski et al.; Cassiopeia A: NASA/CXC/MIT/UMass Amherst/M.D.Stage et al.; DEM 

L71: NASA/CXC/Rutgers/J.Hughes et al.; W49B: X-ray: NASA/CXC/SSC/J.Keohane et al.; Infrared: Caltech/SSC/J.Rho & T.Jarrett; Tycho’s SNR: 

NASA/CXC/Rutgers/J.Warren & J.Hughes et al.; Illustration: CXC/M.Weiss 

ChAndrA 

X-ray Center 

Dem l71: astronomers consider deM L71 to be a textbook example of what happens when a star 

explodes and ejects matter at high speeds into the surrounding interstellar gas. Chandra’s X-ray 

image of deM L71 reveals a 10-million-degree inner cloud (aqua) of glowing iron and silicon, which 

is surrounded by an outer ring of 5-million-degree gas. an analysis of the Chandra data identified 

the inner cloud as the remains of a white dwarf star that exploded. The white dwarf pulled matter 

from a nearby companion star onto itself until it became unstable and blew apart in a thermonuclear 

explosion. Like n132d, deM L71 is located in the Large Magellanic Cloud. 

W49b: This is a composite Chandra X-ray (blue) and palomar infrared (red and green) image of 

the supernova remnant known as W49b, which lies some 35,000 light years from earth. The data 

reveal a barrel-shaped supernova remnant consisting of bright infrared rings around a glowing 

bar of intense X-radiation. These X-rays are produced by jets of 15-million-degree gas that is rich 

in iron and nickel. These features indicate that W49b could have been produced when the core 

of a rapidly rotating massive star collapsed to form a black hole, triggering the ejection of highenergy 

jets of material. 

tyCho’s superNova remNaNt: Chandra’s image shows a bubble of hot gaseous supernova debris 

(green and red) inside a more rapidly moving shell of extremely high-energy electrons (blue). 

These features were created as the supersonic expansion of the debris into interstellar gas produced 

two shock waves—one that moves outward and accelerates particles to high energies, and 

another that moves backward and heats the stellar debris. The relative expansion speeds of the hot 

debris and the high-energy shell indicate that a large fraction of the energy of the outward-moving 

shock wave is going into the acceleration of atomic nuclei to extremely high energies. This finding 

strengthens the case that supernova shock waves are an important source of cosmic rays, high-energy 

nuclei which constantly bombard earth. 

Smithsonian 

Astrophysical Observatory 

Harvard-Smithsonian Center for Astrophysics 

60 Garden Street, Cambridge, MA 02138 

For more information, visit 

http://chandra.harvard.edu

Supernova Remnants - Chandra X-ray Observatory

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