The Cat's Paw Nebula is home to many bright, young stars. But thousands of fainter stars concealed behind dust reveal themselves in a new infrared image.
The playfully named Cat’s Paw Nebula, otherwise known as NGC 6334, is the new hot spot for studying star formation. The well-known stellar nursery could be a mini-starburst, a concentrated area of extremely rapid star formation usually only seen in distant galaxies.
Astronomer Sarah Willis (Harvard-Smithsonian Center for Astrophysics and Iowa State University) peered through shrouds of dust to tally the stars in the Cat’s Paw Nebula, which is busy converting 200,000 Suns worth of material into stars (some as big as 40 times the mass of our Sun). Willis revealed her findings at the American Astronomical Society's meeting earlier this month, and she predicts that the mini-starburst will last for a few million years.
Most bona fide starbursts appear as smudges in a telescope because they reside in faraway galaxies. But NGC 6334 lies merely 5,500 light-years away within the Milky Way. The light from hot and massive O-type stars produces the optical glow we see as the Cat’s Paw Nebula, though much of it is blocked by thick clouds of gas and dust. Fortunately, ground-based and space-based telescopes can detect infrared light that pierces through the dark clouds.
Using the NASA Spitzer Space Telescope and the NOAO Extremely Wide-Field Infrared Imager (NEWFIRM) in Chile, Willis and her colleagues detected over 2,000 young stars down to those as faint as our Sun. Most of these stars hide in the nebula’s dark, dense ridges. To estimate the number of stars less massive than the Sun, the team extrapolated previous models of star formation while separating out background light sources, like galaxies and cooler giant stars. They found that the nebula transforms 3,600 solar masses worth of gas and dust into stars every 1 million years.
Star-forming regions in other galaxies also produce low-mass stars, but the light from high-mass stars often outshines them. That’s why the Cat’s Paw Nebula provides a unique opportunity to study the fainter side of star formation.
But the starbursting nebula provokes new questions, too. Most starbursts result from nearby supernova shockwaves or molecular cloud collisions. Those explanations don’t apply to the Cat’s Paw. A detailed view of the nebula could provide better answers to questions like these.