Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Galaxy Merger Leaves Behind Telltale Blue Arc


Astronomers have identified the vivid scar of a cosmic catastrophe: a blue arc thousands of light years long produced when a galaxy pulled in a smaller satellite galaxy and tore it apart.

Visible in the upper right corner of this image of the Centaurus A Galaxy is an arc of blue stars left behind when Centaurus A pulled in a smaller galaxy and tore it apart. Astronomers say the scar from this cosmic collision is fairly new and thousands of light years long.
Note: Image is available without arrows. Follow this link.
Photo by Eric Peng/JHU/NOAO

The streak is composed of clusters of young blue stars that formed as the larger galaxy, Centaurus A, absorbed the smaller galaxy about 200 million to 400 million years ago. Researchers will report in the December Astronomical Journal that their discovery suggests absorption of smaller galaxies may be a significant contributor to the formation of galactic halos, outer perimeters of galaxies where star populations are sparse.

"This adds a nice example in the local universe to the growing evidence that galaxy halos are built up from the accretion of dwarf satellite galaxies," said Eric Peng, a graduate student in astronomy in the Krieger School of Arts and Sciences at The Johns Hopkins University and lead author of the new paper. "These halos are interesting partly because they’re hard to study, but also because time scales for things to happen in halos are very long, which means they may preserve conditions that reveal how a galaxy formed and evolved."

Peng and his colleagues found the streak in specially processed digital images of Centaurus A taken at the National Science Foundation’s Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory near La Serena, Chile. The team made its observations in 2000.

At 10 million light years from our galaxy, Centaurus A (which is visible with binoculars in the southern hemisphere’s night sky, but not visible at all in the northern hemisphere) is quite close in galactic terms. The galaxy’s most prominent features include a central lane of dust and debris, and signs of violent activity on its perimeter that are suggestive of a prior galactic merger.

Astronomers had previously noticed the arc that Peng and colleagues have now identified as a galactic merger remnant, but without recognizing its origin. That took evidence Peng and colleagues gathered with Mosaic II, a new wide-field digital camera at the Blanco Telescope funded by the National Optical Astronomy Observatory.

Peng and fellow researchers Holland Ford, a professor of astronomy at Johns Hopkins; Ken Freeman, a professor at the Australian National University; and Rick White, astronomer at the Space Telescope Science Institute, used Mosaic II to create images of Centaurus A through several different color filters. Comparing these images highlighted regions of the galaxy that have different colors, and revealed the predominance of young blue stars in the arc. This allowed Peng and his colleagues to identify the arc as a remnant of a galactic merger and estimate the time when Centaurus A absorbed it.

Astronomers have identified similar remnants of galactic mergers in various stages of ingestion into the Milky Way, including the Sagittarius Galaxy. Peng said the newly identified remnant in Centaurus A is unusual in terms of both how recently the merger took place and how gas-rich the satellite galaxy appears to have been.

Ford noted that the group hadn’t originally set out to find remnants of dwarf galaxies.

"One of the joys of science is unexpected discoveries," Ford said. "Although our pictures were taken for another project, we decided to search the data for evidence of ’shredded’ dwarf galaxies. We were very excited when the blue arc popped out of one of the images."

Peng noted that the remnant cannot account for all the signs of prior galactic merger activity seen in Centaurus A. As an elliptical (or roughly football- shaped) galaxy, Centaurus A was likely produced by the merger of two large galaxies.

"It’s possible that the small galaxy that was recently accreted by Centaurus A was originally a satellite orbiting one of the large galaxies involved in that larger merger," says Peng. "Just like when our galaxy merges with the Andromeda Galaxy in the distant future -- the Milky Way’s satellite galaxies, such as the Magellanic Clouds, will likely be involved in that merger."

Peng and other researchers are currently looking for other signs of remnants elsewhere in Centaurus A, and planning for follow-up observations on the arc they identified as a galactic remnant.

"If we can get the velocities of star clusters in the arc and map out the orbit, that will allow us to place better constraints on how long ago the merger occurred and on what the motions of the incoming galaxy were," Peng says.

Michael Purdy | EurekAlert!

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

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>