Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Astronomers identify thick disc of older stars in nearby Andromeda galaxy

16.02.2011
An international team of astronomers has identified for the first time a thick stellar disc in the Andromeda galaxy, the nearest large spiral galaxy to our own Milky Way.

The discovery of the thick disc, a major result from a five-year investigation, will help astronomers better understand the processes involved in the formation and evolution of large spiral galaxies like ours, according to the team, which includes UCLA research astronomer Michael Rich and colleagues from Europe and Australia.

Using the Keck Telescope in Hawaii, the astronomers analyzed the velocities of individual bright stars within the Andromeda galaxy and were able to observe a group of stars tracing a thick disc — distinct from those comprising the galaxy's already-known thin disc — and assessed how these stars differ from thin-disc stars in height, width and chemistry.

Approximately 70 percent of Andromeda's stars are contained in the galaxy's thin stellar disc. This disc structure contains the spiral arms traced by regions of active star formation, and it surrounds a central bulge of old stars at the core of the galaxy.

"From observations of our own Milky Way and other nearby spirals, we know that these galaxies typically possess two stellar discs, both a 'thin' and a 'thick' disc," said Michelle Collins, a doctoral student at the University of Cambridge's Institute of Astronomy, who led the study.

The thick disc consists of older stars whose orbits take them along a "thicker" path — one that extends both above and below the galaxy's thin disc.

"The classical thin stellar discs that we typically see in Hubble imaging result from the accretion of gas towards the end of a galaxy's formation, whereas thick discs are produced in a much earlier phase of the galaxy's life, making them ideal tracers of the processes involved in galactic evolution," Collins said.

The formation process of thick discs is not yet well understood. Previously, the best hope for understanding this structure was by studying the thick disc present in our own Milky Way. However, much of our galaxy's thick disc is obscured from view. The discovery of a similar thick disc in Andromeda presents a much clearer view of spiral structure.

Astronomers will be able to determine the properties of the disc across the galaxy and will search for signatures of the events related to its formation, the researchers said.

"Our initial study of this component already suggests that it is likely older than the thin disc, with a different chemical composition," said UCLA's Rich, who was the principal investigator at the Keck Observatory for the observations. "Future, more detailed observations should enable us to unravel the formation of the disc system in Andromeda, with the potential to apply this understanding to the formation of spiral galaxies throughout the universe."

"This result is one of the most exciting to emerge from the larger parent survey of the motions and chemistry of stars in the outskirts of Andromeda,'' said Scott Chapman of the Institute of Astronomy at Cambridge. "Finding this thick disc has afforded us a unique and spectacular view of the formation of the Andromeda system and will undoubtedly assist in our understanding of this complex process."

The study is currently available in the online version of Monthly Notices of the Royal Astronomical Society and will be published in a print edition of the journal later this year.

UCLA is California's largest university, with an enrollment of more than 38,000 undergraduate and graduate students. The UCLA College of Letters and Science and the university's 11 professional schools feature renowned faculty and offer 328 degree programs and majors. UCLA is a national and international leader in the breadth and quality of its academic, research, health care, cultural, continuing education and athletic programs. Six alumni and five faculty have been awarded the Nobel Prize.

For more news, visit the UCLA Newsroom and follow us on Twitter.

Stuart Wolpert | EurekAlert!
Further information:
http://www.ucla.edu

More articles from Physics and Astronomy:

nachricht Pulses of electrons manipulate nanomagnets and store information
21.07.2017 | American Institute of Physics

nachricht Vortex photons from electrons in circular motion
21.07.2017 | National Institutes of Natural Sciences

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: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA looks to solar eclipse to help understand Earth's energy system

21.07.2017 | Earth Sciences

Stanford researchers develop a new type of soft, growing robot

21.07.2017 | Power and Electrical Engineering

Vortex photons from electrons in circular motion

21.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>