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 Four elements make 2-D optical platform
26.09.2017 | Rice University

nachricht The material that obscures supermassive black holes
26.09.2017 | Instituto de Astrofísica de Canarias (IAC)

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: The fastest light-driven current source

Controlling electronic current is essential to modern electronics, as data and signals are transferred by streams of electrons which are controlled at high speed. Demands on transmission speeds are also increasing as technology develops. Scientists from the Chair of Laser Physics and the Chair of Applied Physics at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have succeeded in switching on a current with a desired direction in graphene using a single laser pulse within a femtosecond ¬¬ – a femtosecond corresponds to the millionth part of a billionth of a second. This is more than a thousand times faster compared to the most efficient transistors today.

Graphene is up to the job

Im Focus: LaserTAB: More efficient and precise contacts thanks to human-robot collaboration

At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.

Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Nerves control the body’s bacterial community

26.09.2017 | Life Sciences

Four elements make 2-D optical platform

26.09.2017 | Physics and Astronomy

Goodbye, login. Hello, heart scan

26.09.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>