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Spitzer and ALMA combine forces to reveal stellar birth

Jenny Winder, News Writer
Nov 13, 2013, 8:00 UTC

Sen—Combined observations from NASA's Spitzer Space Telescope and the newly completed Atacama Large Millimeter/submillimeter Array (ALMA) in Chile have combined forces to reveal the throes of stellar birth as never before.

HH 46/47 is a well-studied Herbig-Haro (HH) object, which form when jets shot out by newborn stars collide with surrounding material, producing small, bright, nebulous regions.

The dynamics within many HH objects are obscured by enveloping gas and dust. But the infrared and submillimeter wavelengths of light seen by Spitzer and ALMA, respectively, are able to pierce the dark cosmic cloud around HH 46/47. Infrared light has longer wavelengths than what we see with our eyes, and submillimeter light has even longer wavelengths.

In the image above shorter-wavelength light appears blue and longer-wavelength light, red. Blue shows gas energized by the outflowing jets. The green colours trace a combination of hydrogen gas molecules and dust that follows the boundary of the gas cloud cocooning the young star.

The Spitzer observations show twin supersonic jets emanating from the central star that blast away surrounding gas and set it alight into two bubbly lobes.

HH 46/47 sits on the edge of its enveloping cloud in such a way that the jets pass through two different cosmic environments. The rightward jet, heading into the cloud, is plowing through a "wall" of material, while the leftward jet is relatively unobstructed, passing through less material.

This orientation offers scientists a handy compare-and-contrast setup for how the outflows from a developing star interact with their surroundings.

"Young stars like our sun need to remove some of the gas collapsing in on them to become stable, and HH 46/47 is an excellent laboratory for studying this outflow process," said Alberto Noriega-Crespo, a scientist at the Infrared Processing and Analysis Center at the California Institute of Technology. "Thanks to Spitzer, the HH 46/47 outflow is considered one of the best examples of a jet being present with an expanding bubble-like structure."

The team began studying HH 46/47 with Spitzer nearly 10 years ago when the telescope first began observing the heavens. Now, using a new image processing technique developed in the past few years, they have been able to render HH 46/47 in higher resolution.

The fresh views of HH 46/47 by ALMA have revealed that the gas in the lobes is expanding faster than previously thought. This faster expansion has an influence on the overall amount of turbulence in the gaseous cloud that originally spawned the star. In turn, the extra turbulence could have an impact on whether and how other stars might form in this gaseous, dusty, and thus fertile, ground for star-making.