RSSAll Entries Tagged With: "molecular cloud"

Deep freeze telescope reveals galactic carbon trail

USING A TELESCOPE INSTALLED at the driest place on earth – Ridge A in Antarctica – a UNSW-led team of researchers has identified a giant gas cloud that appears to be in an early stage of formation. Giant clouds of molecular gas – the most massive bodies in our galaxy – are the birthplaces of stars.

“This newly discovered gas cloud is shaped like a very long filament, about 200 light years in extent and ten light years across, with a mass about 50,000 times that of our Sun,” says team leader, Professor Michael Burton, an astronomer at UNSW Australia. “The evidence suggests it is in the early stages of formation, before any stars have turned on.”

Stunning new way of doing science

The team is using the High Elevation Antarctic Terahertz telescope, or HEAT, at Ridge A, along with the Mopra telescope at Coonabarabran in NSW, to map the location of gas clouds in our galaxy from the carbon they contain.

At 4,000 metres elevation, Ridge A is one of the coldest places on the planet, and the driest. The lack of water vapour in the atmosphere there allows terahertz radiation from space to reach the ground and be detected.

PLATO-R in Antarctica

The PLATO-R observatory at Ridge A. The HEAT telescope is the black object on stilts at left, the instrument module is the yellow box and the solar panel array is on the right. Image Credit: Geoff Sims.

The PLATO-R robotic observatory with the HEAT telescope was installed in 2012 by a team led by UNSW physicist, Professor Michael Ashley, and Dr Craig Kulesa of the University of Arizona.

“We now have an autonomous telescope observing our galaxy from the middle of Antarctica and getting data, which is a stunning new way of doing science. Ridge A is more than 900 kilometres from the nearest people, who are at the South Pole, and is completely unattended for most of the year,” says Professor Burton.

Following the galactic carbon trail

The HEAT telescope detects atomic carbon and the Mopra telescope detects carbon monoxide. “I call it following the galactic carbon trail,” says Professor Burton.

Mopra telescope

The Mopra telescope, near Coonabarabran in NSW.

The discovery of the new galactic cloud, which is about 15,000 light years from earth, will help determine how these mysterious objects develop in the interstellar medium.

One idea is that they are formed from the gravitational collapse of an ensemble of small clouds into a larger one. Another involves the random collision of small clouds that then agglomerate. Or it may be that the molecular gas filament is condensing out of a very large, surrounding cloud of atomic gas.

About one star per year, on average, is formed in the Milky Way. Stars that explode and die then replenish the gas clouds as well as moving the gas about and mixing it up.

The team includes researchers from Australia, Germany and the US. The results have been published in The Astrophysical Journal.

Adapted from information issued by UNSW. Image Credit: Geoff Sims.

Get SpaceInfo.com.au daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

Australian dish charts where stars are born

The Large Magellanic Cloud

The Large Magellanic Cloud (LMC) is the nearest sizeable galaxy to our Milky Way, and is therefore a popular target for astronomers studying the evolution of stars.

ASTRONOMERS HAVE MAPPED in detail the star-forming regions of the nearest star-forming galaxy to our own, a step toward understanding the conditions surrounding star creation.

The researchers, led by University of Illinois astronomy professor Tony Wong—and including Associate Professor Sarah Maddison and PhD student Annie Hughes, both of the Swinburne University of Technology in Melbourne, Australia—have published their findings in the December issue of the Astrophysical Journal Supplement Series.

The Large Magellanic Cloud (LMC) is a popular galaxy among astronomers both for its nearness to our Milky Way and for the spectacular view it provides, a big-picture vista impossible to capture of our own galaxy.

“If you imagine a galaxy being a disc, the LMC is tilted almost face-on so we can look down on it, which gives us a very clear view of what’s going on inside,” Wong said.

Mopra dish

CSIRO's 22-metre-diameter Mopra radio telescope, located near Coonabarabran in NSW.

As the LMC is in the far southern sky, it is an ideal target for Australian telescopes. And indeed, the team used the CSIRO’s 22-metre-diameter radio telescope at Mopra, near Coonabarabran in north-central New South Wales.

Where are stars born?

Although astronomers have a working theory of how individual stars form, they know very little about what triggers the process or the conditions in space that are optimal for star birth.

Wong’s team focused on areas called molecular clouds, which are dense patches of gas—primarily molecular hydrogen—where stars are born. By studying these clouds and their relationship to new stars in the galaxy, the team hoped to learn more about how gas clouds turn into stars.

Using the Mopra dish, the astronomers mapped more than 100 molecular clouds in the LMC and estimated their sizes and masses, identifying regions with ample material for making stars. This seemingly simple task engendered a surprising find.

Conventional wisdom states that most of the molecular gas in a galaxy is apportioned to a few large clouds. However, Wong’s team found many more low-mass clouds than they expected—so many, in fact, that a majority of the dense gas may be sprinkled across the galaxy in these small molecular clouds, rather than clumped together in a few large blobs.

MAGMA image of the LMC

False-colour image of the Large Magellanic Cloud galaxy combining maps of neutral atomic hydrogen gas (red), hydrogen energised by nearby young stars (blue), and new data from Wong’s team which roughly show the locations of dense clouds of molecular hydrogen (green). It's thought that stars form within molecular hydrogen clouds.

Star formation widespread in the LMC galaxy

The large numbers of these relatively low-mass clouds means that star-forming conditions in the LMC may be relatively widespread and easy to achieve.

To better understand the connection between molecular clouds and star formation, the team compared their molecular cloud maps to maps of infrared radiation, which reveal where young stars are heating cosmic dust.

“It turns out that there’s actually very nice correspondence between these young massive stars and molecular clouds,” Wong said.

“We can say with great confidence that these clouds are where the stars form, but we are still trying to figure out why they have the properties they do,” he added.

Adapted from information issued by University of Illinois at Urbana-Champaign. Mopra photo courtesy CSIRO. MAGMA image of LMC courtesy Tony Wong, University of Illinois.

Get SpaceInfo.com.au daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…