Space

September 25, 2013

NASA’s Hubble, Chandra find evidence for densest nearby galaxy

nasa-chandra-hubble
Astronomers using NASA’s Hubble Space Telescope and Chandra X-ray Observatory and telescopes on the ground may have found the most crowded galaxy in our part of the universe.

The ultra-compact dwarf galaxy, known as M60-UCD1, is packed with an extraordinary number of stars and may be the densest galaxy near Earth. It is providing astronomers with clues to its intriguing past and its role in the galactic evolutionary chain.

M60-UCD1, estimated to be about 10 billion years old, is near the massive elliptical galaxy NGC 4649, also called M60, about 54 million light years from Earth. It is the most luminous known galaxy of its type and one of the most massive, weighing 200 million times more than our sun, based on observations with the W.M. Keck Observatory 10-meter telescope in Hawaii.

What makes M60-UCD1 so remarkable is that about half of this mass is found within a radius of only about 80 light years. The density of stars is about 15,000 times greater – meaning the stars are about 25 times closer to each other – than in Earth’s neighborhood in the Milky Way galaxy.

“Traveling from one star to another would be a lot easier in M60-UCD1 than it is in our galaxy, but it would still take hundreds of years using present technology,” said Jay Strader of Michigan State University in Lansing. Strader is the lead author of a paper about the research, which was published Sept. 20 in The Astrophysical Journal Letters.

The 6.5-meter Multiple Mirror Telescope in Arizona was used to study the amount of elements heavier than hydrogen and helium in stars in M60-UCD1. The values were found to be similar to our sun.

“The abundance of heavy elements in this galaxy makes it a fertile environment for planets and, potentially, for life to form,” said co-author Anil Seth of the University of Utah.

Another intriguing aspect of M60-UCD1 is the presence of a bright X-ray source in its center, revealed in Chandra data. One explanation for this source is a giant black hole weighing in at about 10 million times the mass of our sun.

Astronomers want to find out whether M60-UCD1 was born as a jam-packed star cluster or became more compact as stars were ripped away from it. Large black holes are not found in star clusters, so if the X-ray source is in fact due to a massive black hole, it was likely produced by collisions between M60-UCD1 and one or more nearby galaxies. M60-UCD1’s great mass and the abundances of elements heavier than hydrogen and helium are also arguments for the theory it is the remnant of a much larger galaxy.

“We think nearly all of the stars have been pulled away from the exterior of what once was a much bigger galaxy,” said co-author Duncan Forbes of Swinburne University in Australia. “This leaves behind just the very dense nucleus of the former galaxy, and an overly massive black hole.”

If this stripping did occur, then the galaxy originally was 50 to 200 times more massive than it is now, and the mass of its black hole relative to the original mass of the galaxy would be more like that of the Milky Way and many other galaxies. The stripping could have taken place long ago and M60-UCD1 may have been stalled at its current size for several billion years.

NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra Program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.




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


 
 

 

Headlines January 23, 2015

News: Two Marines identified in deadly California helo crash - Two Marine Corps officers killed when their helicopter crashed during a training exercise in the Southern California desert were remembered Jan. 25 as talented pilots. Greek F-16 crashes in Spain during NATO exercise - Ten people died Jan. 26 after a Greek air force F-16 jet crashed...
 
 

News Briefs January 26, 2015

Navy wants to increase use of sonar-emitting buoys The U.S. Navy is seeking permits to expand sonar and other training exercises off the Pacific Coast, a proposal raising concerns from animal advocates who say that more sonar-emitting buoys would harm whales. The Navy now wants to deploy up to 720 sonobuoys about 12 miles off...
 
 
Air National Guard photograph by SSgt. Annie Edwards

ANG conducts air refueling training with NATO allies in Germany

Air National Guard photograph by SSgt. Annie Edwards A NATO E-3A AWACS aircraft approaches a Utah Air National Guard KC-135R Stratotanker for air refueling during a training flight over Germany on Jan. 13, 2015. Nearly 30 airme...
 

 
Air Force photograph by SrA. Armando A. Schwier-Morales

Ramstein Airmen train with French air force

Air Force photograph by SrA. Armando A. Schwier-Morales Two U.S. Air Force pilots and a French air force navigator discuss the route to the drop zone during a simulated low-level drop Jan. 21, 2015, at Orleans – Bricy Air...
 
 

Marines receive first F-35C Lightning II carrier variant

The first F-35C Lightning II, carrier variant, for the U.S. Marine Corps touched-down on the flight line at Eglin Air Force Base, Fla., Jan. 13, from the Lockheed Martin plant in Fort Worth, Texas, to begin training in support of carrier-based operations. U.S. Marine Lt. Col. J.T. Ryan, Marine Fighter Attack Squadron 501 detachment commander...
 
 

VA announces single regional framework under MyVA initiative

The Department of Veterans Affairs announced Jan. 26 that it is taking the first steps under the MyVA initiative to realign its many organizational maps into one map with five regions to better serve Veterans. The new regions under the MyVA alignment will allow VA to begin the process of integrating disparate organizational boundaries into...
 




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>