June 1, 2000
Photo No: H2000-15
Peering into the Heart of the Crab Nebula
In the year 1054 A.D., Chinese astronomers were startled by the
appearance of a new star, so bright that it was visible in broad
daylight for several weeks. Today, the Crab Nebula is visible at
the site of the "Guest Star". Located about 6,500 light-years
from Earth, the Crab Nebula is the remnant of a star that began
its life with about 10 times the mass of our own Sun. Its life
ended on July 4, 1054 when it exploded as a supernova. 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. Resembling an abstract painting by Jackson
Pollack, 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
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.
Kris Davidson (U. Minn.) led the research team of William P. Blair
(JHU), Robert A. Fesen (Dartmouth), Alan Uomoto (JHU), Gordon M.
MacAlpine (U. Mich.), and Richard B.C. Henry (U. Okla.) in the
collection of the HST data. The Hubble Heritage Team created the
color image from black and white data processed by Dr. Blair.
Credit: NASA and The Hubble Heritage Team (STScI/AURA)