Supernovae

Supernova1	The Crab Nebula was originally given this name due to its resemblance to a crab's claw in an early sketch made in 1855 by Lord Rosse's staff astronomer R.J. Mitchell. It is the remnant of a supernova explosion in the year 1054 A.D., which was recorded in five separate accounts in the Far East, although, oddly, no western observation has survived. The nebula was probably first noticed in 1731 by John Bevis, and it was significant enough to be the first entry in Charles Messier's list of nebulae (compiled to avoid mistaking them for comets). The nebula continues to expand and change the details of its appearance, and this is partly due to the violence of the original explosion. However, the star which exploded left behind a rotating neutron star, which continues to beam energy out into the nebula, as well as flashing with a period of only 33 milliseconds. The details of this energy input are important for our understanding both of neutron stars and of the physical conditions in the nebula, and are revealed in the patterns of filaments, their brightness and colors, and the way they change with time. Here's an animated view of the expanding gases.
Supernova1a	In this image, NASA's Hubble Space Telescope has zoomed in on the center of the Crab to reveal its structure with unprecedented detail. The Crab Nebula data were obtained by Hubble's Wide Field and Planetary Camera 2 in 1995. Images taken with five different color filters have been combined to construct this new false-color picture. The image shows ragged shreds of gas that are expanding away from the explosion site at over 3 million miles per hour. The core of the star has survived the explosion as a "pulsar," visible in the Hubble image as the lower of the two moderately bright stars to the upper left of center. The pulsar is a neutron star that spins on its axis 30 times a second. It heats its surroundings, creating the ghostly diffuse bluish-green glowing gas cloud in its vicinity, including a blue arc just to its right. The colorful network of filaments is the material from the outer layers of the star that was expelled during the explosion. The picture is somewhat deceptive in that the filaments appear to be close to the pulsar. In reality, the yellowish green filaments toward the bottom of the image are closer to us, and approaching at some 300 miles per second. The orange and pink filaments toward the top of the picture include material behind the pulsar, rushing away from us at similar speeds. The various colors in the picture arise from different chemical elements in the expanding gas, including hydrogen (orange), nitrogen (red), sulfur (pink), and oxygen (green). The shades of color represent variations in the temperature and density of the gas, as well as changes in the elemental composition. These chemical elements, some of them newly created during the evolution and explosion of the star and now blasted back into space, will eventually be incorporated into new stars and planets. Astronomers believe that the chemical elements in the Earth and even in our own bodies, such as carbon, oxygen, and iron, were made in other exploding stars billions of years ago.
Supernova2	NASA's Chandra X-ray Observatory has taken a stunning image of the Crab Nebula, the spectacular remains of a stellar explosion, and has revealed something never seen before: a brilliant ring around the nebula's heart. Combined with observations from the Hubble Space Telescope, the image provides important clues to the puzzle of how the cosmic "generator," a pulsing neutron star, energizes the nebula, which still glows brightly almost 1,000 years after the explosion. According to Dr. Martin Weisskopf, Chandra Project Scientist from NASA's Marshall Space Flight Center, Huntsville, AL "The Crab pulsar is accelerating particles up to the speed of light and flinging them out into interstellar space at an incredible rate." The image shows tilted rings or waves of high-energy particles that appear to have been flung outward over the distance of a light year from the central star, and high-energy jets of particles blasting away from the neutron star in a direction perpendicular to the spiral. Unraveling the mysteries of the Crab has proven to be the door to insight after insight into the workings of the universe. The Crab convincingly tied the origin of enigmatic "pulsars" to the stellar cataclysms known as supernovae. Observations of the expanding cloud of filaments in the Crab were instrumental in confirming the cosmic origin of the chemical elements from which planets (and people) are made. The Chandra X-ray Observatory has made a beautiful movie of the changes happening near the Crab Pulsar over a period of months. The Hubble Telescope viewed the same changes in visible light. The nebula is located 6,000 light years from Earth in the constellation Taurus. The Crab pulsar, which was discovered by radio astronomers in 1968, is a neutron star rotating 30 times per second. Neutron stars are formed in the seconds before a supernova explosion when gravity crushes the central core of the star to densities 50 trillion times that of lead and a diameter of only 12 miles.
Supernova3	On February 24, 1987 a supernova (called SN1987A) was observed in the Large Magellanic Cloud, a satellite galaxy to our own Milky Way. The image on the right shows the scene before the explosion with the soon-to-be-exploded star arrowed. The image on the left shows the scene after the explosion.
Supernova4	Here is supernova 1987A as it appears in a wide field view about 10 years after the original explosion. This three-color image is composed of several pictures of the supernova and its neighboring region taken with the Wide Field and Planetary Camera 2 in Sept. 1994, Feb. 1996 and July 1997. The many bright blue stars nearby the supernova are massive stars, each more than six times heftier than our Sun. With ages of about 12 million years old, they are members of the same generation of stars as the star that went supernova. The presence of bright gas clouds is another sign of the youth of this region, which still appears to be a fertile breeding ground for new stars. In a few years the supernova's fast moving material will sweep the inner ring with full force, heating and exciting its gas, and will produce a new series of cosmic fireworks that will offer a striking view for more than a decade.
Supernova5	This striking NASA Hubble Space Telescope picture shows three rings of glowing gas encircling the site of supernova 1987A. Though all of the rings appear inclined to our view (so that they appear to intersect) they are probably in three different planes. The small bright ring lies in a plane containing the supernova, the two larger rings lie in front and behind it. The rings are a surprise because astronomers expected to see, instead, an hourglass shaped bubble of gas being blown into space by the supernova's progenitor star (based on previous HST observations, and images at lower resolution taken at ground-based observatories). One possibility is that the two rings might be "painted" on the invisible hourglass by a high-energy beam of radiation that is sweeping across the gas, like a searchlight sweeping across clouds. The source of the radiation might be a previously unknown stellar remnant that is a binary companion to the star that exploded in 1987. The supernova is 169,000 light years away, and lies in the dwarf galaxy called the Large Magellanic Cloud, which can be seen from the southern hemisphere. The image was taken in visible light (hyrdrogen-alpha emission), with the Wide Field Planetary Camera 2, in February 1994.
Supernova6	This Hubble Space Telescope series of four panels shows the evolution of the SN 1987A debris from February 1994 to February 1996. Material from the stellar interior was ejected into space during the supernova explosion in February 1987. The explosion debris is expanding at nearly 6 million miles per hour. Ten years now after the explosion, this cosmic fireball is large enough --- about one-sixth of a light-year in diameter --- to be resolved from the Earth's orbit with the Hubble Space Telescope. The debris is resolved into two opposing blobs and is dim in the center. The apparent direction of ejection is the same as the short axis of the bright inner ring that surrounds the supernova. This suggests that the explosion is directed out of the plane of the ring. The ring is probably composed of materials lost by the pre-supernova star in the last stages of its evolution. The telescope captured the images with the Wide Field and Planetary Camera 2. The central image of the supernova and the ring system was taken in light emitted by nitrogen gas (658 nanometers) on Sept. 24, 1994. The series of debris images were taken using a visible light filter of wavelength around 550 nanometers taken (from left to right) on Feb. 4, 1994, Sept. 24, 1994, March 5, 1995, and Feb. 6, 1996.
Supernova6a	Picture of supernova 1987a from November, 2003 - 16 years after the explosion. A blast wave continues to hit a one light year wide ring of material which existed before the supernova explosion.
Supernova7	A supernova in the outskirts of a spiral galaxy in 1994.
Supernova8	This ten-degree wide radio image of the constellation Cygnus shows shells of ancient supernovas, cocoons surrounding newborn stars, and specks from distant quasars. Two supernova shells are the brown globule at lower left and the white bumpy sphere at upper right. Bright white knots are stellar cocoons.
Supernova9	The Cassiopeia A supernova remnant imaged in x-rays by the Chandra X-ray Observatory. This supernova exploded about 300 years ago.
Supernova10	Some images of the Veil Nebula, the remnant of a supernova that exploded 5,000 to 10,000 years ago. The Veil nebula is huge, spanning 3.5 by 2.3 degrees. It is located about 1,400 light years away in the constellation Cygnus.
Supernova11	Hubble telescope pictures of supernovae in very distant galaxies.
Supernova12	Right of center is supernova remnant IC443 about 5,000 LY away in the constellation Gemini. This remnant contains a neutron star remaining after the explosion about 30,000 years ago. To the upper left of center is the emission nebula IC444.