Astronomers Pull Back the Curtain to Discover an Embryonic Star Cluster

For the first time, astronomers have peeled away the dust fog encapsulating a star-forming region known as W49A, and in doing so have uncovered a site of frantic star formation fed by infalling gas.

"We were amazed by all the features we saw in the SMA images," says lead author Roberto Galván-Madrid, who conducted this research at the Harvard-Smithsonian Center for Astrophysics (CfA) and the European Southern Observatory (ESO).

Located 36,000 light years from Earth on the opposite corner of the galaxy, W49A is the brightest star-formation region in galaxy, measuring about 100 times brighter than the famed Orion nebula. The cloud surrounding it is so thick, however, that little visible or infrared light is able to escape.

The new observations, made using the Smithsonian Submillimeter Array (SMA), reveal a complex arrangement of filaments pumping gas into the region's center at speeds of 4,500 miles per hour.

W49A's heart boasts a massive cluster of stars squeezed in next to each other like sardines; while less than 10 stars lie within 10 light years of our Sun, about 100,000 are packed into the same amount of space in the nebula. 

Such density will help it to survive long into the future, the researchers explained. While most star clusters in our galaxy fizzle away quickly, their stars pulled apart due to gravitational tides, the fact that W49A's could remain intact for billions of years.

The researchers used the SMA to map the molecular gas within the nebula as well. The results revealed enough enough gas - mostly molecular hydrogen - for 1 million suns.  

According to co-author Hauyu Baobab Liu of the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA) in Taiwan, the researchers believe W49A's "organized architecture" may be something of the norm when it comes to massive stellar cluster-formation.

Either way, the SMA data are likely to keep the researchers busy for a while yet.

"It's a mine of information," Galván-Madrid said.

The study was published in The Astrophysical Journal.