Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Hot gas around cold dust cloud surprises astronomers

28.05.2003


New features may make southern sky’s ’Coalsack’ ideal for further study



Stargazers call a prominent dark black region in the Southern Hemisphere’s night sky the Coalsack. Even for naked-eye observers, the cloud of cold gas that makes up the Coalsack is hard to miss: It covers a part of the misty luminescence of the Milky Way, blocking out distant stars of our galaxy with the deep black shades that have earned the Coalsack its name.

A newly discovered aspect of the Coalsack may soon have astronomers thinking of it more like a treasure chest. At an American Astronomical Society Meeting in Nashville this week, astronomers will reveal evidence that the Coalsack has hot gases on its perimeter, a finding that means the Coalsack will likely provide many outstanding opportunities to learn more about interactions between regions of hot and cold gas, processes that are essential to star formation and distribution of the elements that make up life forms and the planets. Findings from the Coalsack may also help scientists refine their models of energy production in the galaxy.


“Every once in a while, nature gives us a break and sets things up so that we can study the key processes fairly easily,” says B-G Andersson, associate research scientist in physics and astronomy in the Krieger School of Arts and Sciences at Johns Hopkins and lead author of the AAS presentation. “For astronomers, this is a bit like finding a living dodo – instead of trying to make inferences about how the dodo walks, which is what we normally have to do, we can get direct, detailed observations of it walking.”

The Coalsack is relatively nearby in cosmological terms, about 650 light years away in the same spiral arm of the Milky Way as Earth. Because it is close by, structures in the Coalsack can be studied in great detail. It’s also nicely backlit from Earth’s point of view by bright stars in the next arm of the Milky Way, allowing scientists to use spectroscopy to acquire a fairly comprehensive sense of the chemical ingredients of the cloud.

The hot gas on the perimeter may indicate that the Coalsack is contained within a region of active massive star formation and supernovae known as the Upper Centaurus-Lupus super-bubble. This region has produced large hot stars that burn out quickly and die explosively, sometimes heating interstellar gas to high temperatures. Naked-eye observers can still see the darkness of the cold gas in the Coalsack because most of the surrounding hot gas is too warm to emit light in the visible portion of the electromagnetic spectrum.

Andersson and coauthors David Knauth and Robin Shelton of Johns Hopkins, S.L. Snowden of Goddard Space Flight Center and Peter Wannier of the Jet Propulsion Laboratory built the case for their finding with data taken by the orbiting Far Ultraviolet Spectroscopic Explorer (FUSE) and Roentgen Satellite (ROSAT) observatories. The authors had been using FUSE to study how cold gas clouds dissipate at their edges when their observations of the Coalsack came back with signs of oxygen VI , oxygen atoms with five of their eight surrounding electrons stripped away.

Astronomers know that considerable energy is required to knock that many electrons off an oxygen atom, and as a result have long interpreted the presence of oxygen VI as a sign that very hot gases are entering a cooling process. How this cooling process occurs – through turbulent mixing of the gas with colder gas clouds or through conduction of electrons – is a topic of debate among astronomers that further study of the Coalsack may help resolve.

Tipped off by the FUSE readings, Andersson and his colleagues analyzed X-ray data from ROSAT, which surveyed X-ray emissions from the entire sky, and found that the perimeter of the Coalsack, particularly its southeast edge, lights up in X-rays – another sign of the hot gas cloud. Through further analysis, they were able to show that the two readings appeared to be coming from the same region around the Coalsack.

“If our model of the Coalsack is right, then you can use it to test various theories of oxygen VI generation, and this may help us better understand what are the mechanisms behind previously detected oxygen VI production in many more distant parts of the galaxy,” Andersson comments. “This could tell us something about energy production in the galaxy, and that could in turn tell us more about star formation.”

Andersson noted that astronomers have been studying the Coalsack since the early 19th century, and plenty of good data on many features of the cloud are already available.

“This is starting to look like a really good laboratory for conducting these kinds of experiments,” he said. “There are certainly other cases where oxygen VI has likely been associated with a cloud, but never before have we had such a nearby cloud with a reliable distance determination or as many background stars behind the cloud to allow us to look at absorption readings.”


This research was supported by NASA.

Michael Purdy | EurekAlert!
Further information:
http://www.jhu.edu/

More articles from Physics and Astronomy:

nachricht Nanostructures taste the rainbow
29.06.2017 | California Institute of Technology

nachricht X-ray photoelectron spectroscopy under real ambient pressure conditions
28.06.2017 | National Institutes of Natural Sciences

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: Making Waves

Computer scientists use wave packet theory to develop realistic, detailed water wave simulations in real time. Their results will be presented at this year’s SIGGRAPH conference.

Think about the last time you were at a lake, river, or the ocean. Remember the ripples of the water, the waves crashing against the rocks, the wake following...

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Nanostructures taste the rainbow

29.06.2017 | Physics and Astronomy

New technique unveils 'matrix' inside tissues and tumors

29.06.2017 | Life Sciences

Cystic fibrosis alters the structure of mucus in airways

29.06.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>