Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists ’RAVE-ing’ about most ambitious star survey ever

12.01.2006


An international team of astronomers today announced the first results from the Radial Velocity Experiment, an ambitious all-sky spectroscopic survey aimed at measuring the speed, temperature, surface gravity and composition of up to a million stars passing near the sun.



Those first results from the project, known for short as RAVE, confirm that dark matter dominates the total mass of our home galaxy, the Milky Way, team members at The Johns Hopkins University and elsewhere said. The full survey promises to yield a new, detailed understanding of the origins of the galaxy, they said.

The results were released at the American Astronomical Society’s 207th meeting in Washington, D.C.


The team is using the "six-degree field" multi-object spectrograph on the 1.2-meter UK Schmidt Telescope at the Anglo-Australian Observatory, located at Siding Spring Observatory in New South Wales, Australia. The instrument is capable of obtaining spectroscopic information for as many as 150 stars at once, said Rosemary Wyse, a professor in the Henry A. Rowland Department of Physics and Astronomy in Johns Hopkins’ Krieger School of Arts and Sciences and a member of the RAVE team. RAVE includes members from the United States, Germany, Australia, Canada, the Netherlands, the United Kingdom, Slovenia, Italy, Switzerland and France.

"One important early application of RAVE aims to measure just how much stuff there is in our Milky Way galaxy -- the collection of stars, gas and dark matter that is the home of our sun," Wyse said. "Newton’s Law of Gravity allows us to figure out from the orbital motions of stars how much mass is holding them together. Faster motions need more mass. We know from analyzing the motions in other galaxies that there is a lot more mass than we can see and this dark matter appears to dominate. But we are not sure exactly how much dark matter is needed in our own galaxy, and we don’t know what the dark matter is made up of. That information is important, and the RAVE survey is going to help us answer some of those questions."

Greg Ruchti, a graduate student in physics and astronomy at Johns Hopkins who also is a member of the RAVE team, notes that the project "needs large samples of very fast stars, and the unprecedented scope of the survey is ideal to find these rare objects. I’m really excited about being part of the RAVE team."

With more data and more modeling, the RAVE team plans to ascertain the Milky Way’s overall mass, which, at present, is poorly understood, Wyse said. The team has what it considers a "better approach" to the problem: a model that makes very definite predictions about the way mass varies as a function of distance from the center of the Milky Way. If the team adopts this model, it can then estimate the overall mass from just the local "escape velocity," Wyse said.

Escape velocity is the speed at which a star would have to be moving to leave the galaxy. The value of this special speed depends on the mass of the galaxy: The higher the mass, the higher the speed necessary to escape. Thus, researchers can estimate the weight of the Milky Way galaxy by measuring how fast objects must move to leave it, Wyse said.

Current RAVE limits show that stars would need to move faster than around 500 kilometers per second to escape, more than twice as fast as the sun is moving around the galactic center. At that escape speed, it would take less than eight seconds to travel from Baltimore to Los Angeles.

"Some groups believe that our neighbor, the Andromeda Galaxy -- also known as M31 -- is the most massive galaxy in our local group. But we suspect from our early results that our Milky Way is actually the local heavyweight," said Martin Smith of the University of Groningen in the Netherlands. "We are, with RAVE, on the verge of an answer."

Funding for RAVE is provided by the National Science Foundation, for Johns Hopkins, and by the national research councils of other team members’ countries as well as by private sources.

"RAVE will run for several more years, and the full RAVE survey will provide a vast resource of stellar motions and chemical abundances, allowing us to answer fundamental questions about the formation and evolution of our galaxy," said Matthias Steinmetz, director of the Astrophysical Institute Potsdam, and leader of the RAVE collaboration.

Lisa De Nike | EurekAlert!
Further information:
http://www.jhu.edu/news/home06/jan06/wyse.html
http://www.jhu.edu

More articles from Physics and Astronomy:

nachricht First Juno science results supported by University of Leicester's Jupiter 'forecast'
26.05.2017 | University of Leicester

nachricht Measured for the first time: Direction of light waves changed by quantum effect
24.05.2017 | Vienna University of Technology

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: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

How herpesviruses win the footrace against the immune system

26.05.2017 | Life Sciences

Water forms 'spine of hydration' around DNA, group finds

26.05.2017 | Life Sciences

First Juno science results supported by University of Leicester's Jupiter 'forecast'

26.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>