Hot New Stars Take Center Stage in Cosmic Photo

For hot, young stars, the Orion nebula seems like the place to be, according to a stunning new image taken by a NASA telescope.

The cluster of young stars in the sword of the famed constellation of Orion (The Hunter) stand out in a new infrared image from NASA's Spitzer Space Telescope, which captured the bustling group of cosmic orbs amid interstellar gas and dust.

By closely monitoring the young stars, scientists hope to learn more about why the stars change, and to what degree planet formation might play a role.

"This is an exploratory project," said John Stauffer, the principal investigator of the research at NASA's Spitzer Science Center, located at the California Institute of Technology in Pasadena, Calif. "Nobody has done this before at a wavelength sensitive to the heat from dust circling around so many stars. We are seeing a lot of variation, which may be a result of clumps of warped structures in the planet-forming disks."

The image of the young stars was taken after Spitzer ran out of coolant in May 2009, which marked the beginning of its extended "warm" mission.

The super-cold liquid helium coolant was used to keep the telescope?s instrument temperatures low enough for detailed infrared observations. But Spitzer?s two shortest-wavelength infrared channels can still function normally at the new, warmer temperature of minus 406 degrees Fahrenheit (minus 243 degrees Celsius).

Spitzer telescope?s infrared stare

In this next phase of Spitzer's mission, the telescope is able to devote more time to projects that cover a greater expanse and require longer observation times.

That includes the "Young Stellar Object Variability" program, in which Spitzer is staring at the same patch of the Orion nebula for extended periods to observe the same cluster of about 1,500 variable stars over time.

So far, Spitzer has already taken approximately 80 photos of this set of stars over the course of 40 days. A second set of observations is planned for the fall.

The stars in this region of the Orion nebula are approximately one million years old, which, in the cosmos, is still relatively young. In comparison, the sun is 4.6 billion years old.

As scientists note, these young stars do exhibit behavior that differs from more adult sun-like stars. For one, the brightness levels of younger stars fluctuate more, and the stars themselves spin faster.

Cold stars, hot stars

One reason for the variations in stellar brightness is due to the existence of cold spots on the surface of the stars. Cold spots are more prevalent on young stars and come and go as the star spins, which changes the amount of light that can be monitored by telescopes.

Stellar brightness can also change as a result of hot spots, which are caused by gas that accretes onto a young star from the material out of which it formed.

"In the 1950s and ?60s, astronomers knew that younger stars varied, and they postulated this had something to do with the birthing process," Stauffer said. "Later, with improved technology, we could see a lot more and learned a great deal about the stars' spots."

Spitzer's infrared sight also has the ability to see the warm, dusty disks orbiting around the stars. These disks are where planets may eventually clump together and form. By gathering more data on these varying disks, Stauffer and his team hope to learn more about how planets develop.

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