Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Unlocking the dark secrets of dwarf galaxies

23.07.2003


New research on dwarf spheroidal galaxies by a team of astronomers at the University of Cambridge promises a real astronomical first: detection, for the first time, of the true outer limits of a galaxy.



The team is presenting today (23 July 2003) at the 25th General Assembly of the International Astronomical Union (IAUXXV) in Sydney, Australia. The research could provide the key to understanding how larger galaxies were formed, including our own Milky Way galaxy.

The rare dwarf spheroidal galaxies display few stars but contain massive amounts of "dark matter" or matter that does not emit radiation that can be observed by astronomers. The team studied these galaxies in detail using some of the largest optical telescopes on earth in order to probe their dark secrets. Dwarf spheroidal galaxies are widely believed to be the building blocks from which galaxies were formed.


By studying the motion of many stars the scientists have created a picture of how the mass of the galaxy is arranged. Surprisingly, when the Cambridge team looked at the stars at the edge of one such galaxy, Draco, they found that the outer stars were moving so quickly that the galaxy could only stay together if it contained 100 times more dark matter than the mass of the stars alone.

Using detailed models of the motions of stars in a galaxy containing large quantities of dark matter, the group was able to demonstrate their observations could only be understood if the galaxy was surrounded by a large halo of dark matter.

Observations of the Ursa Minor dwarf spheroidal galaxy presented a new complication in the study. The team found an unexpected clump of slow-moving stars interpreted as the dead remains of one of the pure star systems, a globular cluster. The cluster should have been scattered across the galaxy, but it was still held together. The team realised this was only possible if the dark matter were arranged in a manner very differently from standard galaxies.

In May 2003, further research into Ursa Minor showed the stars in the very outermost parts are not moving quickly like the stars at the edge of Draco. Several theories are being investigated including dark matter from edge of Ursa Minor has been snatched away from the galaxy by its massive parent, the Milky Way, allowing some stars to wander gently away from their parent. Or they could be stars which wandered too close to other stars in the centre of the galaxy and were slung out to the edge of the galaxy as a result.

Whatever the explanation, the findings promise a real astronomical first: detection, for the first time, of the true outer limits of a galaxy.

Gerry Gilmore, Professor of Experimental Philosophy at the Institute of Astronomy at the University of Cambridge, said:

"This research, utilising some of the largest optical telescopes on earth, has provided us with insight to the makeup of these rare dwarf galaxies. This research helps astronomers better understand how galaxies were formed, and help take into account dark matter in all galaxies."

Laura Morgan | alfa
Further information:
http://www.cam.ac.uk

More articles from Physics and Astronomy:

nachricht Two dimensional circuit with magnetic quasi-particles
22.01.2018 | Technische Universität Kaiserslautern

nachricht Meteoritic stardust unlocks timing of supernova dust formation
19.01.2018 | Carnegie Institution for Science

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: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Thanks for the memory: NIST takes a deep look at memristors

22.01.2018 | Materials Sciences

Radioactivity from oil and gas wastewater persists in Pennsylvania stream sediments

22.01.2018 | Earth Sciences

Saarland University bioinformaticians compute gene sequences inherited from each parent

22.01.2018 | Life Sciences

VideoLinks Wissenschaft & Forschung
Overview of more VideoLinks >>>