Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


A Simple View Of Gravity Does Not Fully Explain The Distribution Of Stars In Crowded Clusters

Gravity remains the dominant force on large astronomical scales, but when it comes to stars in young star clusters the dynamics in these crowded environments cannot be simply explained by the pull of gravity.

After analyzing Hubble Space Telescope images of star cluster NGC 1818 in the Large Magellanic Cloud, a satellite galaxy of the Milky Way, researchers at the Kavli Institute for Astronomy and Astrophysics (KIAA) at Peking University in Beijing found more binary star systems toward the periphery of cluster than in the center – the opposite of what they expected. The surprising distribution of binaries is thought to result from complex interactions among stars within young clusters.

The team’s finding will be published in the March 1 print issue of The Astrophysical Journal and is now online.

In the dynamic environment of a star cluster, high-mass stars are thought to gravitate toward the center of a cluster when they give a ‘kick’ to lower-mass stars and lose energy, explained KIAA Prof. Richard de Grijs, who led the study. This leads them to sink to the cluster center, while the lower-mass stars gain energy and might move to orbits at greater distances from the cluster core. Astronomers call this process “mass segregation.”

However, when the Kavli researchers looked closely at binary star systems within NGC 1818, they found a much more complex picture.

Most stars in clusters actually form in pairs, called “binary stars,” which initially are located so close to one another that they interact, resulting in the destruction of some binary systems. Other binaries, meanwhile, swap partners. Astronomers had expected that the same process that leads a cluster’s most massive stars to gravitate toward the center would also apply to binaries. This is because together, the stars that make up binaries have more mass on average than a single star.

When the astronomers discovered that there were more binaries the farther from the core they observed, they were initially baffled by this unexpected result. They concluded that so-called “soft” binary systems, in which the two stars orbit each other at rather large distances, are destroyed due to close encounters with other stars near the cluster’s center. Meanwhile, “hard” binaries, in which the two stars orbit one another at much shorter distances, survive close encounters with other stars much better, all throughout a cluster. This is why more binaries were seen farther out than close in.

Mapping the radial distribution of binary systems in dense star clusters had never been done before for clusters as young as NGC 1818, which is thought to be 15-30 million years old. This is difficult to do in any case, because there are no young clusters nearby in our own Milky Way galaxy. The new result provides new insights into theoretically predicted processes that govern the evolution of star clusters.

“The extremely dynamic interactions among stars in clusters complicates our understanding of gravity,” team member Chengyuan Li said. “One needs to investigate the entire physical environment to fully understand what’s happening in that environment. Things are usually more complex than they appear.”

James Cohen | EurekAlert!
Further information:

More articles from Physics and Astronomy:

nachricht Move over, lasers: Scientists can now create holograms from neutrons, too
21.10.2016 | National Institute of Standards and Technology (NIST)

nachricht Finding the lightest superdeformed triaxial atomic nucleus
20.10.2016 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of 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: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

New method increases energy density in lithium batteries

24.10.2016 | Power and Electrical Engineering

International team discovers novel Alzheimer's disease risk gene among Icelanders

24.10.2016 | Life Sciences

New bacteria groups, and stunning diversity, discovered underground

24.10.2016 | Life Sciences

More VideoLinks >>>