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 Astronomers find unexpected, dust-obscured star formation in distant galaxy
24.03.2017 | University of Massachusetts at Amherst

nachricht Gravitational wave kicks monster black hole out of galactic core
24.03.2017 | NASA/Goddard Space Flight Center

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: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>