Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Our Galaxy may be bigger than we thought

11.08.2005


Our Galaxy could be a lot bigger than we thought. That’s the conclusion of team of astronomers that’s found whole new ‘suburbs’ of stars in another galaxy.



Like archaeologists unearthing a lost city, the Australian and US astronomers used the 8-m Gemini South telescope in Chile to reveal the faint ancient outer parts of the galaxy NGC 300, showing that that galaxy is at least twice as big as previously thought.

The finding implies that our own Galaxy too is probably much bigger than textbooks say.


And ideas on how galaxies form will have to be rethought, to explain how NGC 300 could have stars so far out from its centre.

The research is published today [10 August 2005] in the Astrophysical Journal.

NGC300 is a spiral galaxy 6.1 million light-years away. It looks rather like our own Galaxy, with most of its stars lying in a thin disk like a pancake.

Using the Gemini Multi-Object Spectrograph instrument on the Gemini South telescope in Chile, the observers were able to see stars in the disk up to 47,000 light-years [14.4 kpc] from the galaxy’s centre—double the previously known radius of the disk.

These were extremely sensitive measurements, going more than ten times fainter than any previous images of this galaxy.

A few billion years ago the outskirts of NGC 300 were brightly lit suburbs that would have shown up as clearly as its inner metropolis. But the suburbs have dimmed with time, and are now inhabited only by faint, old stars—stars that need large telescopes such as Gemini South to detect them.

The finding has profound implications for our own Galaxy. Most current estimates put its size at 100,000 light-years across, about the same as the new estimate for NGC 300. “However, our galaxy is much more massive and brighter than NGC 300. So on this basis, our Galaxy is also probably much larger than we previously thought—perhaps as much as 200,000 light-years across,” said the paper’s lead author, Professor Joss Bland-Hawthorn of the Anglo-Australian Observatory.

The observers found no evidence that the outer part of NGC 300 was falling abruptly in brightness, or truncating, as happens in many galaxies.

“We now realize that there are distinctly different types of galaxy disks,” said team member Professor Ken Freeman of the Research School of Astronomy and Astrophysics at the Australian National University. “Probably most truncate—the density of stars in the disk drops off sharply. But NGC 300 just seems to go on forever. The density of stars in the disk falls off very smoothly and gradually.”

The observers traced NGC 300’s disk out to the point where the surface density of stars was equivalent to a one-thousandth of a Sun per square light-year.

“This is the most extended and diffuse population of stars ever seen,” said Bland-Hawthorn.

Helen Sim | alfa
Further information:
http://www.gemini.edu/index.php?option=content&task=view&id=144

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 >>>