SMA reveals giant star cluster in the making

Dec 16, 2013
This image from the Smithsonian's Submillimeter Array maps the projected density of molecular gas in the central 30 light years of W49A. Brighter colors mark denser regions. The brightest region at the image center is less than three light-years across, yet it contains about 50,000 suns' worth of molecular gas. Credit: Roberto Galván-Madrid (ESO), Hauyu Baobab Liu (ASIAA, Taiwan), Tzu-Cheng Peng (ESO)

W49A might be one of the best-kept secrets in our galaxy. This star-forming region shines 100 times brighter than the Orion nebula, but is so obscured by dust that very little visible or infrared light escapes.

The Smithsonian's Submillimeter Array (SMA) has peered through the dusty fog to provide the first clear view of this stellar nursery. The SMA revealed an active site of star formation being fed by streamers of 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).

W49A is located about 36,000 light-years from Earth, on the opposite side of the Milky Way. It represents a nearby example of the sort of vigorous seen in so-called "starburst" galaxies, where stars form 100 times faster than in our galaxy.

The heart of W49A holds a giant yet surprisingly compact star cluster. About 100,000 stars already exist within a space only 10 light-years on a side. In contrast, fewer than 10 stars lie within 10 light-years of our Sun. In a few million years, the giant star cluster in W49A will be almost as crowded as a globular cluster.

The SMA also revealed an intricate network of filaments feeding gas into the center, much like tributaries feed water into mighty rivers on Earth. The gaseous filaments in W49A form three big streamers, which funnel star-building material inward at speeds of about 4,500 miles per hour (2 km/sec).

"Move over, Mississippi!" quips co-author Qizhou Zhang of the CfA.

Being denser than average will help the W49A star cluster to survive. Most in the galactic disk dissolve rapidly, migrating away from each other under the influence of gravitational tides. This is why none of the Sun's sibling stars remain nearby. Since it is so compact, the cluster in W49A might remain intact for billions of years.

The Submillimeter Array mapped the molecular gas within W49A in exquisite detail. It showed that central 30 light-years of W49A is several hundred times denser than the average molecular cloud in the Milky Way. In total, the nebula contains about 1 million suns' worth of gas, mostly molecular hydrogen.

"We suspect that the organized architecture seen in W49A is rather common in massive stellar cluster-formation," adds co-author Hauyu Baobab Liu of the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA) in Taiwan.

The team expects to continue analyzing the SMA data for some time to come.

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

Explore further: Hidden details revealed in nearby starburst galaxy

Related Stories

Turbulence May Promote the Birth of Massive Stars

Feb 23, 2009

(PhysOrg.com) -- On long, dark winter nights, the constellation of Orion the Hunter dominates the sky. Within the Hunter's sword, the Orion Nebula swaddles a cluster of newborn stars called the Trapezium. These stars are ...

Hidden details revealed in nearby starburst galaxy

Dec 09, 2013

Using the new, high-frequency capabilities of the National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT), astronomers have captured never-before-seen details of the nearby starburst galaxy ...

Young stars paint spectacular stellar landscape

Nov 13, 2013

Astronomers at ESO have captured the best image so far of the clouds around the star cluster NGC 3572. This image shows how these clouds of gas and dust have been sculpted into bubbles, arcs and the odd features ...

Recommended for you

Satellite galaxies put astronomers in a spin

53 minutes ago

An international team of researchers, led by astronomers at the Observatoire Astronomique de Strasbourg (CNRS/Université de Strasbourg), has studied 380 galaxies and shown that their small satellite galaxies almost always ...

Video: The diversity of habitable zones and the planets

1 hour ago

The field of exoplanets has rapidly expanded from the exclusivity of exoplanet detection to include exoplanet characterization. A key step towards this characterization is the determination of which planets occupy the Habitable ...

Ultra-deep astrophoto of the Antenna Galaxies

1 hour ago

You might think the image above of the famous Antenna Galaxies was taken by a large ground-based or even a space telescope. Think again. Amateur astronomer Rolf Wahl Olsen from New Zealand compiled a total ...

The most precise measurement of an alien world's size

2 hours ago

Thanks to NASA's Kepler and Spitzer Space Telescopes, scientists have made the most precise measurement ever of the radius of a planet outside our solar system. The size of the exoplanet, dubbed Kepler-93b, ...

User comments : 4

Adjust slider to filter visible comments by rank

Display comments: newest first

cantdrive85
1 / 5 (5) Dec 16, 2013
The SMA revealed an active site of star formation being fed by streamers of infalling gas.

The "streamers of infalling gas" are actually the electric currents powering the stars.

"We were amazed by all the features we saw in the SMA images," says lead author Roberto Galván-Madrid, who conducted this research

Because they don't understand the basic properties of plasma...

The SMA also revealed an intricate network of filaments feeding gas into the center, much like tributaries feed water into mighty rivers on Earth. The gaseous filaments in W49A form three big streamers, which funnel star-building material inward at speeds of about 4,500 miles per hour (2 km/sec).

A narrow minded world-view prevents them from seeing the obvious.
Tuxford
1 / 5 (4) Dec 16, 2013
Have to agree about the assumption of infalling streamers, but I would argue is more likely outwardly ejected, in massive winds, from the high density core region they acknowledge exists. Regions of high matter density accelerate matter formation within the stellar cores, leading to instabilities, and ejection. This process is common in galactic cores as well.
davidivad
2.3 / 5 (3) Dec 16, 2013
it is hard to believe that they got such good resolution with all that stuff in between. I wish those toys were cheap enough for the average backyard astronomer.
GSwift7
4 / 5 (1) Dec 17, 2013
I wish those toys were cheap enough for the average backyard astronomer


That would be cool, since observing time is such a huge limitation on these big instruments.

On the other hand, the data is available for free (in some cases they do charge a handling fee, but it isn't much) to anyone with the means to make use of it. If you had an observatory like SMA in your back yard, all to yourself, it wouldn't do you much good. You would need some kind of big number-crunching computer system (not quite a super-computer, but close) in order to make sense of it. That is not a trivial part of the work.

But yeah, it would be really cool to be in charge of an observatory with that kind of power. (Christmas gift for next millenium: The IPod Radio and Infra-Red Telescopic Contact Lense Observatory and Interferometer, $19.99 at Target, lol)