NASA's Spitzer Space Telescope has sent earthlings a Valentine of sorts, a new image of a nebulous cloud of dust and hot stars that astronomers likened to a rosebud.

The image actually reveals a budding cluster of stellar birth.

"The picture is more than just pretty," said Thomas Megeath, an astronomer at the Harvard Smithsonian Center for Astrophysics who led the observations. "It helps us understand how stars form in the crowded environments of stellar nurseries."

The nebula, numbered NGC 7129, is 3,330 light-years away in the constellation Cepheus. The scene spans 10 light-years of space. In one portion of the nebula, some 130 young stars were found.

Our own Sun is believed to have grown up in a similar tightly-packed environment and been booted out to its now-lonely existence. The nearest star to the Sun is Proxima Centauri at 4.36 light-years away. In that same amount of space within NGC 7129, the 130 newborn stars are all huddled, Megeath said.

"By combining data from the Smithsonian's MMT Telescope in Arizona with Spitzer data, we find that roughly half of these stars are surrounded by disks of gas and dust," Megeath said. "Each of these disks is a forming solar system."

Astronomers do not know exactly how that process works, however, nor what percentage of stars with disks actually form planets.

Most stars are thought to develop in similar clusters, when a giant cloud of gas and dust, made mostly of hydrogen, condenses under its own weight. Knots form, and stars are born. Larger, faster-forming stars tend to rule such scenes, and smaller or slower-developing stars can be gravitationally kicked out of a cluster.

Spitzer detects infrared radiation, or heat, rather than visible light.

Infrared is not visible to humans, so the recorded colors are shifted, together, into the visible spectrum to form a "false color" image. The pink and red regions represent hot dust.

The green "stem" of the rosebud harbors newborn stars emitting fast-moving jets of superhot material that scorch the gas in which they are embedded.

Scientists analyzed the amount and specific type of infrared light escaping each star to determine which are ringed by the debris of their birth, the stuff of potential planets.

The scene is chaotic. Within just a million years, radiation from the newborn stars has blown a large bubble in the cloud that, astronomers say, once enveloped them all like a cocoon.

The observations will contribute to a better understanding of how stellar nurseries shape the development of planetary systems similar to our own. While the formation of rocky, Earthlike planets is fairly well understood, theory of giant planet formation is in disarray.

Scientists are eager to learn to what extent massive, hot, newborn stars prevent planet formation in these dense clusters by radiating the disks of nearby stars and blowing the material away. The balance between such violence and the ability of at least some stars to retain "protoplanetary disks," as they are called, is thought to have allowed our own Sun to develop the solar system as it is.

Spitzer was launched last August. It is managed by NASA's Jet Propulsion Laboratory and the California Institute of Technology.

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