Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Detecting dusty clouds and stars in our galaxy in a new way

08.01.2013
Radio wave technique uncovers shadows of clouds and stars in Milky Way's center

The center of our Milky Way galaxy is a wondrous place full of huge star clusters, dust clouds, magnetic filaments and a supermassive black hole. But it can be a confusing place, too, posing challenges to astronomers trying to image these exotic features and learn more about where they are located in the galaxy.

Northwestern University's Farhad Zadeh has discovered a new tool for detecting dusty clouds and stars: simply take a picture using radio waves. He is the first to identify what he calls radio dark clouds and stars. Stars in the early and late phases of their evolution are shrouded by huge dusty envelopes in the form of dust and gas outflows.

"When you see these dark stars or clouds in radio wavelength images, it tells you something very interesting," Zadeh said. "We immediately know there is a cold gas cloud or dusty star mixing with a hot radiative medium and that an interaction is taking place. Knowing details of these clouds is important because the clouds can produce stars and also provide material for the growth of black holes."

Zadeh is a professor of physics and astronomy in the Weinberg College of Arts and Sciences and a member of Northwestern's Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA).

Unlike in the optical, X-ray and infrared wavelengths, it is unusual to see a dark feature with radio waves. Radio is a long wavelength and therefore doesn't get absorbed easily and typically passes through whatever is in its way.

Initially Zadeh thought maybe the dark features he saw on the radio images he was studying were nothing, but then he connected the features to five known dense molecular and dusty clouds located in the center of our galaxy, some near Sagittarius A* (Sgr A*), the black hole.

"This technique provides very good sensitivity of faint dusty features, and it can produce images with even higher resolution than many other telescopes," Zadeh said. "It is an initial observation that tells you something is there that needs to be studied more closely."

In addition, astronomers can measure the size of dusty stars using this new technique.

Zadeh will present his results at 11:30 a.m. PST (Pacific Standard Time) Tuesday, Jan. 8, at the 221st meeting of the American Astronomical Society in Long Beach, Calif. He also will participate in a press conference on the galactic center at 12:45 p.m. PST the same day.

The interaction of a cold dust cloud with a hot radiation field results in a loss in the continuum emission and appears as a dark feature in the radio wavelength image, Zadeh said. The dark features that trace the embedded molecular clouds provide astronomers with the size of the cloud in three dimensions.

Although not part of the work he is presenting, Zadeh said a good example of a dusty cloud that could be imaged with his technique is G2, the tiny cloud that is fast approaching Sgr A*, our galaxy's black hole.

The cloud now is too close to the black hole for Zadeh to take an image, but he is looking at earlier data to see if he can locate G2 as a radio dark cloud.

"If the cloud was farther away from the black hole than it is now, we could detect it," Zadeh said.

For his study, Zadeh used Green Bank Telescope maps and Very Large Array images from the National Radio Astronomy Observatory. The National Science Foundation (grant AST-0807400) supported the research.

The title of Zadeh's paper, which was published Nov. 1 by the Astrophysical Journal Letters, is "Imprints of Molecular Clouds in Radio Continuum Images."

Megan Fellman | EurekAlert!
Further information:
http://www.northwestern.edu

More articles from Physics and Astronomy:

nachricht Enhancing the quantum sensing capabilities of diamond
23.11.2017 | The Hebrew University of Jerusalem

nachricht Quantum optics allows us to abandon expensive lasers in spectroscopy
22.11.2017 | Lomonosov Moscow State University

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: Frictional Heat Powers Hydrothermal Activity on Enceladus

Computer simulation shows how the icy moon heats water in a porous rock core

Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Underwater acoustic localization of marine mammals and vehicles

23.11.2017 | Information Technology

Enhancing the quantum sensing capabilities of diamond

23.11.2017 | Physics and Astronomy

Meadows beat out shrubs when it comes to storing carbon

23.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>