Their study explains the origin of these clouds for the first time.
Swinburne University PhD student Alyson Ford (now at the University of Michigan) and her supervisors; Dr Naomi McClure-Griffiths (CSIRO Astronomy and Space Science) and Felix Lockman (US National Radio Astronomy Observatory), have made the first detailed observations of ‘halo’ gas clouds in our Galaxy.
Just as Earth has an atmosphere, the main starry disk of our Galaxy is surrounded by a thinner halo of stars, gas and ‘dark matter’.
The halo clouds skim the surface of our Galaxy, sitting 400 to 10 000 light-years outside the Galactic disk. They are big: an average-sized cloud contains hydrogen gas 700 times the mass of the Sun and is about 200 light-years across.
“We’re studying the clouds to understand what role they play in recycling material between the disk and halo,” Dr McClure-Griffiths said.
“The clouds can fall back down into the main body of the Galaxy, returning gas to it.”
The researchers studied about 650 clouds and found striking differences between them in different areas of the Galaxy. One part of the Galaxy had three times as many clouds as another next to it, and the clouds were twice as thick.
The region with lots of thick clouds is where lots of stars form, while the region with fewer clouds also forms fewer stars."We’re studying the clouds to understand what role they play in recycling material between the disk and halo,"
Dr McClure-Griffiths said.But the halo clouds aren’t found exactly where stars are forming right now. Instead, they seem to be linked to earlier star formation.
Massive stars grow old quickly. After a few million years they shed material into space as a ’wind‘ and then explode.
This violence creates bubbles in the gas in space, like the holes in a Swiss cheese.
“Stellar winds and explosions sweep up gas from the Galactic disk into the lower halo.
“We’ve found this churned-up gas is ‘spritzing’ the surface of the Galactic disk in the form of halo clouds.”
A star-forming region is active for less than a million years, but a super-bubble in the Galaxy takes 20 or 30 million years to form.
“Just as yeast takes a while to make wine bubbly, stars take a while to make the Galaxy bubbly,” Dr McClure-Griffiths said.
The halo clouds are distinct from a larger population of ‘high-velocity clouds’ that also sail outside the galaxy. The halo clouds move in tandem with the rotating Galaxy, while the high-velocity clouds scud along much faster.
This study is the first to accurately locate the halo clouds in relation to the main body of the Galaxy. Its findings were presented overnight at a news conference at a meeting of the American Astronomical Society in Miami, Florida.
Media please note:
Dr McClure-Griffiths will be available to respond directly to media enquiries from 7 am to 8:20 am. To organise interviews with Dr McClure-Griffiths after 8:20 am, contact Ms Helen Sim.
Helen Sim | EurekAlert!
Enhancing the quantum sensing capabilities of diamond
23.11.2017 | The Hebrew University of Jerusalem
Quantum optics allows us to abandon expensive lasers in spectroscopy
22.11.2017 | Lomonosov Moscow State University
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...
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....
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...
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...
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....
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
23.11.2017 | Information Technology
23.11.2017 | Physics and Astronomy
23.11.2017 | Life Sciences