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viernes, 11 de febrero de 2011

Thousands of New Stars Emerge in Glowing Nebula

Thousands of young stars come to the fore in in this beautiful new image from the Spitzer Space Telescope.

The previously unseen stars were born around 1,800 light-years from Earth in a region called the North American Nebula. In images that capture the same range of light that human eyes can see, the nebula looks like the eastern seaboard of the United States, down to the Gulf of Mexico. But most of that light is reflected off clouds of dust that hide infant stars. Only about 200 young stars were known before.

This image breaks through the clouds to find more than 2,000 new objects that may be young stars. (More data processing will determine their nature.) Because Spitzer is sensitive to infrared wavelengths that can sense heat, it can see the glow of the dusty, buried stars.

“One of the things that makes me so excited about this image is how different it is from the visible image, and how much more we can see in the infrared than in the visible,” said Spitzer astronomer Luisa Rebull in a press release. “The Spitzer image reveals a wealth of detail about the dust and the young stars here.” A paper detailing the observations has been accepted in the Astrophysical Journal Supplement Series.

Stars are born inside collapsing balls of gas and dust, which flattens into a disk that spins together with the star like a record album. As the star ages, the disk is thought to congeal into planets. Most of the dust is expected to dissipate by the time the star is at the center of a mature solar system.

The new Spitzer image shows stars in all stages of development, from dust-blanketed infancy to early adulthood, when stars are new parents to a growing family of planets.

Despite the new views of its growing stellar family, the North American nebula is still shrouded in mystery. The group of massive stars that is thought to dominate the nebula is still unseen. The Spitzer image and images from other telescopes hint that the missing stars lurk behind the Gulf of Mexico portion of the nebula.

In this image, infrared light with a wavelength of 3.6 microns is colored blue; 8.0-micron light is green; and 24-micron light is red. Since taking this image, Spitzer ran out of the coolant needed to keep the two longest wavelength detectors working. Spitzer is still snapping photos in the two shorter wavelength bands.

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