PEERING INTO THE HEART OF THE CRAB NEBULA
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
this violent stellar explosion. In this new image,
NASA's Hubble Space Telescope has zoomed in on the
center of the Crab to reveal its structure with
about 6,500 light-years from Earth in the direction
of the constellation Taurus, the Crab Nebula is
the remnant of a star that began its life with about
10 times the mass of our own Sun. Such a massive
star consumes its nuclear fuel so rapidly that it
lives only some 50 million years before exploding
as a supernova. For the Crab star, the end came
on July 4, 1054. The explosion was witnessed as
a naked-eye "Guest Star" by Chinese astronomers,
and is also depicted in rock paintings of Native
Americans in the southwestern United States.
Crab Nebula image was 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 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
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 has about
1.4 times the mass of the Sun, but jammed into an
object only about 10 miles in diameter. This incredible
object, a "neutron star," is even more
remarkable because it spins on its axis 30 times
spinning pulsar heats its surroundings, creating
the ghostly diffuse bluish-green glowing gas cloud
in its vicinity, including a blue arc just to the
right of the neutron star.
colorful network of filaments is the material from
the outer layers of the star that was expelled during
the explosion and is now expanding outward at high
speed. 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.
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.
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
Davidson (U. Minn.) led the research team of W.
P. Blair (JHU), R. A. Fesen (Dartmouth), A. Uomoto
(JHU), G. M. MacAlpine (U. Mich.), and R. 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)
Acknowledgments: William P. Blair (JHU)