A new image from NASA’s Chandra X-ray Observatory reveals hot gas
flowing away from massive young stars in the center of the Horseshoe
Nebula, a.k.a. M17 or the Omega Nebula. A group of massive young stars
responsible for the activity in the nebula is located in the bright pink
region near the center of the image.

Chandra’s resolving power enabled astronomers to separate the
contribution of these and other stars in the nebula from X-rays produced
by the hot gas flow, which is shown in red. Temperatures in the hot gas
flow range from 1.5 million degrees Celsius (2.7 million degrees
Fahrenheit) to about 7 million degrees Celsius (13 million degrees F).
The blue color indicates areas where stars are embedded in clouds of
dust and gas that absorb low energy X-rays.

An infrared image of the Horseshoe Nebula reveals a cloud of much cooler
gas and dust shaped like a horseshoe that gives the nebula its name. The
hot gas shown by the Chandra image fits inside the cool gas cloud, and
appears to have formed the horseshoe shape by carving a cavity in the
cool gas. This activity could lead to the formation of new stars in the

The stars in the Horseshoe Nebula are only about a million years old, so
the nebula is too young for one of its stars to have exploded as a
supernova and heated the gas. Collisions between high-speed winds of
particles flowing away from the massive stars could heat the gas, or the
hot gas could be produced as these winds collide with cool clouds to
form bubbles of hot gas. This hot gas appears to be flowing out of the
Horseshoe like champagne flows out of a bottle when the cork is removed,
so it has been termed an “X-ray champagne flow.”

A comparison with other young star clusters confirms that massive young
stars are responsible for hot gas clouds like the one seen in the
Horseshoe Nebula. The Arches cluster, which contains many massive young
stars shows this type of cloud, whereas the central regions of the Orion
Nebula, which has few massive young stars, does not.

NASA’s Marshall Space Flight Center, Huntsville, Ala., manages the
Chandra program for the Office of Space Science, NASA Headquarters,
Washington. Northrop Grumman of Redondo Beach, Calif., formerly TRW,
Inc., was the prime development contractor for the observatory. The
Smithsonian Astrophysical Observatory controls science and flight
operations from the Chandra X-ray Center in Cambridge, Mass.

The image and additional information are available at: