Cat’s Paw Nebula: Nearby Mini-Starburst?

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.

Cat's Paw Nebula
This false-color image combines infrared data from the Herschel and Spitzer spacecraft with the ground-based NEWFIRM imager. The green signifies dense regions of gas and dust, where new stars will likely form. The newly-forming massive stars are marked by red and orange. The light reflected back to us by these hot, young stars is shown by the hazy blue and purple. Click the image to view a larger version.
S. Willis (CfA, ISU) / ESA / Herschel / NASA / JPL / Caltech / Spitzer / CTIO / NOAO / AURA / NSF
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.

Cat's Paw Nebula
The end of the Cat’s Paw nebula imaged from the Blanco 4-meter Telescope in Chile. The picture highlights the ionized hydrogen from the emission nebula in red. Click on the image to see an enlarged version.
T.A. Rector (U Alaska) / T. Abbott / NOAO / AURA / NSF
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.

One thought on “Cat’s Paw Nebula: Nearby Mini-Starburst?

  1. Peter WilsonPeter

    "Most starbursts result from nearby supernova shockwaves…" But what causes the supernova? Massive new stars. But what causes massive new stars? Not sure about the chicken or egg, but believe most starbursts result from molecular cloud collisions, and the supernova come after, not before.