Space

September 13, 2013

Hubble uncovers largest known group of star clusters, clues to dark matter

nasa-hubble
 

NASA’s Hubble Space Telescope has uncovered the largest known population of globular star clusters, an estimated 160,000, swarming like bees inside the crowded core of the giant grouping of galaxies known as Abell 1689.

An international team of astronomers used Hubble’s Advanced Camera for Surveys to discover this bounty of stellar fossils and confirm such compact groupings can be used as reliable tracers for dark matter, the invisible gravitational scaffolding on which galaxies are built.

“We show how the relationship between globular clusters and dark matter depends on the distance from the center of the galaxy grouping,” Karla Alamo-Martinez of the Center for Radio Astronomy and Astrophysics of the National Autonomous University of Mexico in Morelia. “In other words, if you know how many globular clusters are within a certain distance, we can give you an estimate of the amount of dark matter.”

Alamo-Martinez is lead author of a paper on the findings published online Sept. 10 and appearing in the Sept. 20 print edition of The Astrophysical Journal, and part of a team led by John Blakeslee of National Research Council Canada’s Herzberg Institute of Astrophysics at the Dominion Radio Astrophysical Observatory in Victoria, British Columbia.

Globular clusters, dense bunches of hundreds of thousands of stars, are the homesteaders of galaxies. They contain some of the oldest surviving stars in the universe. Almost 95 percent of globular cluster formation occurred within the first 1 billion to 2 billion years after our universe was born in the theorized Big Bang 13.8 billion years ago.

Studying globular clusters is critical to understanding the early, intense star-forming events that mark galaxy formation. Understanding dark matter can yield clues on how large structures such as galaxies and galaxy clusters were assembled billions of years ago.

The globular star cluster in Abell 1689 is roughly twice as large as any other population found in previous globular cluster surveys — in comparison, our Milky Way galaxy hosts about 150 — and constitutes the most distant such systems ever studied, at 2.25 billion light-years away. The Hubble study shows most of the globular clusters in Abell 1689 formed near the center of the galaxy grouping, which contains a deep well of dark matter. The farther away from the galaxy core Hubble looked, the fewer globular clusters it detected. This observation corresponded with a comparable drop in the amount of dark matter, based on previous research.

“The globular clusters are fossils of the earliest star formation in Abell 1689, and our work shows they were very efficient in forming in the denser regions of dark matter near the center of the galaxy cluster,” Blakeslee said. “Our findings are consistent with studies of globular clusters in other galaxy clusters, but extend our knowledge to regions of higher dark matter density.”

Peering deep inside the heart of Abell 1689, Hubble detected the visible-light glow of 10,000 globular clusters, some as dim as 29th magnitude, which is 1 one-billionth the faintness of the dimmest star that can be seen with the naked eye. Based on that number, Blakeslee’s team estimated that more than 160,000 globular clusters are huddled within a diameter of 2.4 million light-years.

“Even though we are looking deep into the cluster, we’re only seeing the brightest globular clusters, and only near the center of Abell 1689 where Hubble was pointed,” he said.




All of this week's top headlines to your email every Friday.


 
 

 
Image courtesy of NASA/JPL-Caltech/Univ. of Arizona

NASA’s Mars Curiosity rover arrives at Martian mountain

NASA’s Mars Curiosity rover has reached the Red Planet’s Mount Sharp, a Mount-Rainier-size mountain at the center of the vast Gale Crater and the rover mission’s long-term prime destination. “Curiosity n...
 
 

NASA announces 2014 aeronautics scholarship recipients

NASA has selected 20 students from across the nation to receive the agency’s Aeronautics Scholarship for the 2014-2015 school year. This scholarship program, which is in its seventh year, is designed to assist undergraduate and graduate students enrolled in fields of study related to aeronautics. Recipients were selected from hundreds of applications to the program....
 
 
NASA photograph by Dan Casper

NASA’s Orion spacecraft nears completion, ready for fueling

NASA photograph by Dan Casper The Orion crew module, stacked atop its service module, moved out of the Neil Armstrong Operations and Checkout Building at NASA’s Kennedy Space Center in Florida on Sept 11. Orion was transporte...
 

 

NASA awards cross-track infrared sounder instrument for the JPSS-2

NASA has awarded a sole source contract modification to Exelis, Inc., Geospatial Systems, of Fort Wayne, Ind., for the Cross-track Infrared Sounder Instrument for flight on the Joint Polar Satellite System-2 mission. This is a cost-plus-award-fee modification in the amount of $221 million. This action extends the period of performance of the contract from November...
 
 
NASA photograph

NASA unveils world’s largest spacecraft welding tool for Space Launch System

NASA photograph A 16mm fisheye lens was used to show a wide angle view of the Vertical Assembly Center at NASA’s Michoud Assembly Facility in New Orleans at a ribbon-cutting ceremony Sept 12. The VAC is the largest spacecraft...
 
 
boeing-satellite

Boeing receives first order for 502 Phoenix small satellite

EL SEGUNDO, Calif. – Boeing has received its first commercial order for the 502 Phoenix small satellite from HySpecIQ of Washington, D.C. The satellites will carry the commercial remote sensing industry’s first high...
 




0 Comments


Be the first to comment!


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>