Composite
 |  |  |  | |
| Chandra X-Ray Data (blue) | Chandra X-Ray Data (green) | Hubble Telescope (visible-light) | Spitzer Telescope (infrared) |
NASA's three Great Observatories -- the Hubble Space Telescope, the Spitzer
Space Telescope, and the Chandra X-ray Observatory -- joined forces to probe the
expanding remains of a supernova, called Kepler's supernova remnant, first seen
400 years ago by sky watchers, including astronomer Johannes Kepler.
The combined image unveils a bubble-shaped shroud of gas and dust that is 14
light-years wide and is expanding at 4 million miles per hour (2,000 kilometers
per second). Observations from each telescope highlight distinct features of the
supernova remnant, a fast-moving shell of iron-rich material from the exploded
star, surrounded by an expanding shock wave that is sweeping up interstellar gas
and dust.
Each color in this image represents a different region of the electromagnetic
spectrum, from X-rays to infrared light. These diverse colors are shown in the
panel of photographs below the composite image. The X-ray and infrared data
cannot be seen with the human eye. By color-coding those data and combining them
with Hubble's visible-light view, astronomers are presenting a more complete
picture of the supernova remnant.
Visible-light images from the Hubble telescope (colored yellow) reveal where the
supernova shock wave is slamming into the densest regions of surrounding gas.
The bright glowing knots are dense clumps from instabilities that form behind
the shock wave. The Hubble data also show thin filaments of gas that look like
rippled sheets seen edge-on. These filaments reveal where the shock wave is
encountering lower-density, more uniform interstellar material.
The Spitzer telescope shows microscopic dust particles (colored red) that have
been heated by the supernova shock wave. The dust re-radiates the shock wave's
energy as infrared light. The Spitzer data are brightest in the regions
surrounding those seen in detail by the Hubble telescope.
The Chandra X-ray data show regions of very hot gas, and extremely high-energy
particles. The hottest gas (higher-energy X-rays, colored blue) is located
primarily in the regions directly behind the shock front. These regions also
show up in the Hubble observations, and also align with the faint rim of glowing
material seen in the Spitzer data. The X-rays from the region on the lower left
(colored blue) may be dominated by extremely high-energy electrons that were
produced by the shock wave and are radiating at radio through X-ray wavelengths
as they spiral in the intensified magnetic field behind the shock front. Cooler
X-ray gas (lower-energy X-rays, colored green) resides in a thick interior shell
and marks the location of heated material expelled from the exploded star.
Kepler's supernova, the last such object seen to explode in our Milky Way
galaxy, resides about 13,000 light-years away in the constellation Ophiuchus.
The Chandra observations were taken in June 2000, the Hubble in August 2003;
and the Spitzer in August 2004.
