Subscribe free to our newsletters via your
. 24/7 Space News .

Subscribe free to our newsletters via your

A New Way to Explore Dark Matter
by Staff Writers
Hilo HI (SPX) Jan 12, 2016

Computer simulation of gas distribution (left) and stars (right) after the Milky Way is perturbed by the dwarf satellite. Download the entire animation here.

Ripples in gas at the outer disk of our galaxy have puzzled astronomers since they were first revealed by radio observations a decade ago. Now, astronomers believe they have found the culprit - a dwarf galaxy, containing dark, unseen material, which skimmed the outskirts of our galaxy a few hundred million years ago.

The research, led by Sukanya Chakrabarti of the Rochester Institute of Technology, presents the first plausible explanation for the galactic ripples. "It's a bit like throwing a stone into a pond and making ripples," said Chakrabarti at a conference at the 227th meeting of the American Astronomical Society in Kissimmee, Florida.

"Of course we aren't talking about a pond, but our galaxy, which is tens of thousands of light-years across, and made of stars and gas, but the result is the same - ripples!"

Chakrabarti adds that this work is part of a new discipline called galactoseismology: "This is really the first non-theoretical application of this field, where we can infer things about the unseen composition of galaxies from analyzing galaxy-quakes."

To reach their conclusion the research team studied a trio of stars, called Cepheid variables, which are part of the likely dwarf galaxy now estimated to lie about 300,000 light-years away from our galaxy in the direction of the constellation Norma.

"We have a pretty good idea of the distance to these stars because the intrinsic brightness of Cepheid variable stars depends on their period of pulsation, which we can measure," says Chakrabarti.

"But the stars' distances were already estimated before this work - what I wanted to know was how fast this speeding bullet was going when it passed by our galaxy - with that information we can begin to understand the dynamics, and ultimately how much unseen dark matter is there."

To do that, Chakrabarti and her team focused on three Cepheids in the tiny galaxy. Using spectroscopic observations obtained at the Gemini Observatory (as well as the Magellan Telescope, and the WiFeS spectrograph) the researchers found that the stars are all speeding away at similar velocities - about 450,000 mph (~200 kilometers/second).

"This really implicates these stars as being part of an organized, fast-moving system which we believe is a dwarf galaxy. It's also very likely that this dwarf satellite brushed our galaxy millions of years ago and left ripples in its wake," said Chakrabarti.

"This new, potentially powerful way to study how stars, gas and dust are distributed in galaxies is really quite exciting," said Chris Davis, program director at the U.S. National Science Foundation that funds roughly 65% of Gemini as part of its international partnership, as well as this research program.

"Known as galactoseismology, it can trace both visible and invisible materials, including the elusive dark matter. It's a great way to better understand how galaxies and neighboring satellite dwarf galaxies interact as well."

Gemini Observatory astronomer Rodolfo Angeloni oversaw the observations at the Gemini South telescope in Chile. He adds that Gemini South is uniquely well-equipped to make these types of observations.

"The combination of Gemini's silver-coated mirror and the versatility of the infrared spectrograph Flamingos-2 really made this work possible." However, he continues, "These were especially faint and remote targets - we really had to push the limits."

The team plans to continue this work by looking for more Cepheid variable stars in our galaxy's halo. "There could be a population of yet undiscovered Cepheid variables that formed from a gas-rich dwarf galaxy falling into our galaxy's halo," said Chakrabarti.

"With the capabilities of today's telescopes and instruments we should be able to sample enough of the Milky Way's halo to make reasonable estimates on dark matter content - one of the greatest mysteries in astronomy today!"

The international research team includes Rodolfo Angeloni, Ken Freeman, Leo Blitz, among others, and RIT research scientist Benjamin Sargent and Andrew Lipnicky, a graduate student in the astrophysical sciences and technology program.


Related Links
Gemini Observatory
Stellar Chemistry, The Universe And All Within It

Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks DiggDigg RedditReddit GoogleGoogle

Previous Report
Russian scientists to develop dark matter detection model
Novosibirsk (Sputnik) Jan 04, 2016
Russian scientists plan to develop a dark matter detection prototype within one to two years, the Siberian Branch of Russian Academy of Science's senior nuclear physics research official said Sunday. "We know that [dark matter] leaves almost no traces and our main task is to dramatically lower the detection threshold to a minimum, which is physically possible in principle. There is quite s ... read more

Chang'e-3 landing site named "Guang Han Gong"

Momentum builds for creation of 'moon villages'

South Korea to launch lunar exploration in 2016, land by 2020

Death rumors of Russian lunar program 'greatly exaggerated' - Deputy PM

Rover Rounds Martian Dune to Get to the Other Side

Boulders on a Martian Landslide

NASA suspends March launch of InSight mission to Mars

University researchers test prototype spacesuits at Kennedy

Strengthening Our Space Technology Future: Snapshots of Success

Six Orion Milestones to Track in 2016

Gadgets get smarter, friendlier at CES show

Congress to NASA: Hurry up on that 'habitation augmentation module'

China plans 20 launches in 2016

China's Belt and Road Initiative catches world's imagination: Inmarsat CEO

Robotic telescope built by China and Thailand put into operation

China launches HD earth observation satellite

British astronaut's first spacewalk set for Jan 15

NASA Delivers New Video Experience On ISS

British astronaut dials wrong number on Xmas call from space

Space Station Receives New Space Tool to Help Locate Ammonia Leaks

SpaceX will try to land its reusable rocket on an ocean dock

Maintaining Arianespace's launch services leadership in 2016

Arianespace starts year with record order backlog

Russian Space Forces launched 21 spacecraft in 2015

Lab discovery gives glimpse of conditions found on other planets

Nearby star hosts closest alien planet in the 'habitable zone'

ALMA reveals planetary construction sites

Monster planet is 'dancing with the stars'

Researchers squeeze hydrogen into 'metallic state'

Vietnam army probes mysterious 'space balls'

Setting the Standard for 3-D Printed Rocket Engines

3D-Printed Ceramics Could be Used in Future Space Flights

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement