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Trifid Nebula's triple treat
DR EMILY BALDWIN
ASTRONOMY NOW

Posted: August 26, 2009


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A stunning new image of the Trifid Nebula from the European Southern Observatory (ESO) reveals the furious star-forming furnace set inside a rare combination of three nebula types.

The stellar factory, located 5,000 light years away in the constellation of Sagittarius, is so named for the dark dust bands that trisect its heart. The new ESO portrait paints a picture of the early stages of a star's life, from gestation to first light, and clearly shows the different regions of the nebula in visible light.

The Trifid Nebula, as captured by the Wide-Field Imager camera attached to the MPG/ESO 2.2-metre telescope at ESOÕs La Silla Observatory in northern Chile. So named for the dark dust bands that trisect its glowing heart, the Trifid Nebula is a rare combination of three nebulae types that reveal the fury of freshly formed stars and point to more star birth in the future. The field of view of the image is approximately 12 x 16 arcminutes. Image: ESO.

The light blue patch in the upper left of the image is called a reflection nebula, where gas scatters light from stars born inside the Trifid Nebula. The largest of these stars shines like a beacon in the hot blue portion of the visible spectrum. Since dust grains and molecules scatter blue light more efficiently than red light, this portion of the Trifid Nebula is permeated with an azure hue.

The pink regions are typical of an emission nebula, and signifies the presence of scorching new-born stars emitting the signature red light of hydrogen. As these newly ignited stars stir the nebula's gas, over time the tendrils of matter that weave through the nebula will eventually collapse into new stars too.

The third type of nebula crisscross the Trifid in dark bands, and are known as dark nebulae for their light-obscuring effects. Hidden inside these dark lanes are the coalescing remains of earlier birthing episodes. As the pressure, temperature and density inside these dark nebulae increases, more stars will spark into life.

Finally, in the lower part of the image, a finger of gas pokes out from the cloud, pointing directly at the central star powering the Trifid. This is an example of an evaporating gaseous globule, and at the tip of the finger, a knot of dense gas has resisted the onslaught of radiation from this massive star.