Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Why do starburst galaxies 'burst'?

16.02.2015

ALMA sees super stellar nurseries at heart of sculptor galaxy

Starburst galaxies transmute gas into new stars at a dizzying pace - up to 1,000 times faster than typical spiral galaxies like the Milky Way. To help understand why some galaxies "burst" while others do not, an international team of astronomers used the Atacama Large Millimeter/submillimeter Array (ALMA) to dissect a cluster of star-forming clouds at the heart of NGC 253, one of the nearest starburst galaxies to the Milky Way.


What is the recipe for starburst? Astronomers studied NGC 253 with ALMA to find out. These new ALMA data reveal a diffuse envelope of carbon monoxide gas (shown in red), which surrounds stellar nurseries -- regions of active star formation (in yellow). By dissecting these regions with ALMA, astronomers are uncovering clues to the processes and conditions that drive furious star formation. The ALMA data are superimposed on a Hubble image that covers part of the same region.

Credit: B. Saxton (NRAO/AUI/NSF); ALMA (NRAO/ESO/NAOJ); A. Leroy; STScI/NASA, ST-ECF/ESA, CADC/NRC/CSA

"All stars form in dense clouds of dust and gas," said Adam Leroy, an astronomer formerly with the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia, and now with The Ohio State University in Columbus. "Until now, however, scientists struggled to see exactly what was going on inside starburst galaxies that distinguished them from other star-forming regions."

ALMA changes that by offering the power to resolve individual star-forming structures, even in distant systems. As an early demonstration of this capability, Leroy and his colleagues mapped the distributions and motions of multiple molecules in clouds at the core of NGC 253, also known as the Sculptor Galaxy.

Sculptor, a disk-shape galaxy currently undergoing intense starburst, is located approximately 11.5 million light-years from Earth, which is remarkably nearby for such an energetic star factory. This proximity makes Sculptor an excellent target for detailed study.

"There is a class of galaxies and parts of galaxies, we call them starbursts, where we know that gas is just plain better at forming stars," noted Leroy. "To understand why, we took one of the nearest such regions and pulled it apart - layer by layer - to see what makes the gas in these places so much more efficient at star formation."

ALMA's exceptional resolution and sensitivity allowed the researchers to first identify ten distinct stellar nurseries inside the heart of Sculptor, something that was remarkably hard to accomplish with earlier telescopes, which blurred the different regions together.

The team then mapped the distribution of about 40 millimeter-wavelength "signatures" from different molecules inside the center of the galaxy. This was critically important since different molecules correspond to different conditions in and around star-forming clouds. For example, carbon monoxide (CO) corresponds to massive envelopes of less dense gas that surround stellar nurseries. Other molecules, like hydrogen cyanide (HCN), reveal dense areas of active star formation. Still rarer molecules, like H13CN and H13CO+, indicate even denser regions.

By comparing the concentration, distribution, and motion of these molecules, the researchers were able to peel apart the star-forming clouds in Sculptor, revealing that they are much more massive, ten times denser, and far more turbulent than similar clouds in normal spiral galaxies.

These stark differences suggest that it's not just the number of stellar nurseries that sets the throttle for a galaxy to create new stars, but also what kind of stellar nurseries are present. Because the star-forming clouds in Sculptor pack so much material into such a small space, they are simply better at forming stars than the clouds in a galaxy like the Milky Way. Starburst galaxies, therefore, show real physical changes in the star-formation process, not just a one-to-one scaling of star formation with the available reservoir of material.

"These differences have wide-ranging implications for how galaxies grow and evolve," concluded Leroy. "What we would ultimately like to know is whether a starburst like Sculptor produces not just more stars, but different types of stars than a galaxy like the Milky Way. ALMA is bringing us much closer to that goal."

These results are accepted for publication in the Astrophysical Journal and are being presented February 15, 2015, at a news conference at the American Association for the Advancement of Science (AAAS) meeting in San Jose, California.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

Media Contact

Charles Blue
cblue@nrao.edu
434-296-0314

 @TheNRAO

http://www.nrao.edu 

Charles Blue | EurekAlert!

More articles from Physics and Astronomy:

nachricht Measured for the first time: Direction of light waves changed by quantum effect
24.05.2017 | Vienna University of Technology

nachricht Physicists discover mechanism behind granular capillary effect
24.05.2017 | University of Cologne

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

Physicists discover mechanism behind granular capillary effect

24.05.2017 | Physics and Astronomy

Measured for the first time: Direction of light waves changed by quantum effect

24.05.2017 | Physics and Astronomy

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>