Featured Research

from universities, journals, and other organizations

Evidence for densest nearby galaxy

Date:
September 24, 2013
Source:
Chandra X-ray Center
Summary:
Astronomers may have found the most crowded galaxy in our part of the universe.

Astronomers have discovered what may be the densest galaxy in the nearby universe.
Credit: X-ray: NASA/CXC/MSU/J.Strader et al, Optical: NASA/STScI

The densest galaxy in the nearby Universe may have been found. Packed with an extraordinary number of stars, this unusual galaxy is providing astronomers with clues to its intriguing past and how it fits into the galactic evolutionary chain.

Related Articles


The galaxy, known as M60-UCD1, is a type of "ultra-compact dwarf galaxy." It was discovered with NASA's Hubble Space Telescope and follow-up observations were done with NASA's Chandra X-ray Observatory and ground-based optical telescopes.

Observations from the W. M. Keck Observatory on the summit of Mauna Kea, Hawaii, characterized it as the most luminous known galaxy of its type and one of the most massive, weighing 200 million times more than our Sun.

What makes M60-UCD1 so remarkable is that about half of this mass is found within a radius of only about 80 light years. This would make the density of stars about 15,000 times greater than found in Earth's neighborhood in the Milky Way, meaning that the stars are about 25 times closer.

"Traveling from one star to another would be a lot easier in M60-UCD1 than it is in our galaxy," said Jay Strader of Michigan State University in Lansing, first author of a new paper describing these results. "But it would still take hundreds of years using present technology."

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, life to form," said co-author Anil Seth of the University of Utah.

Another intriguing aspect of M60-UCD1 is that the Chandra data reveal the presence of a bright X-ray source in its center. One explanation for this source is a giant black hole weighing in at some 10 million times the mass of the Sun.

Astronomers are trying to determine if M60-UCD1 and other ultra-compact dwarf galaxies are either born as jam-packed star clusters or if they are galaxies that get smaller because they have stars ripped away from them. 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 the galaxy and one or more nearby galaxies. The mass of the galaxy and the Sun-like abundances of elements also favor the idea that the galaxy 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 was originally 50 to 200 times more massive than it is now, which would make the mass of its black hole relative to the original mass of the galaxy more like the Milky Way and many other galaxies. It is possible that this stripping took place long ago and that M60-UCD1 has been stalled at its current size for several billion years. The researchers estimate that M60-UCD1 is more than about 10 billion years old.

The density of stars in the galaxy is so high astronomers do not expect to find a signature of dark matter in the motion of stars. However, these galaxies are considered likely to contain some dark matter. If they do, they are important for making comparisons with computer simulations of the formation of galaxies, which typically predict a larger number of clumps of dark matter than observed.

M60-UCD1 is located near a massive elliptical galaxy NGC 4649, also called M60, about 60 million light years from Earth. These results appear online and have been published in the September 20th issue of The Astrophysical Journal Letters.


Story Source:

The above story is based on materials provided by Chandra X-ray Center. Note: Materials may be edited for content and length.


Cite This Page:

Chandra X-ray Center. "Evidence for densest nearby galaxy." ScienceDaily. ScienceDaily, 24 September 2013. <www.sciencedaily.com/releases/2013/09/130924141659.htm>.
Chandra X-ray Center. (2013, September 24). Evidence for densest nearby galaxy. ScienceDaily. Retrieved December 22, 2014 from www.sciencedaily.com/releases/2013/09/130924141659.htm
Chandra X-ray Center. "Evidence for densest nearby galaxy." ScienceDaily. www.sciencedaily.com/releases/2013/09/130924141659.htm (accessed December 22, 2014).

Share This


More From ScienceDaily



More Space & Time News

Monday, December 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Spokesman: 'NORAD Ready to Track Santa'

Spokesman: 'NORAD Ready to Track Santa'

AP (Dec. 19, 2014) Pentagon spokesman Rear Adm. John Kirby said that NORAD is ready to track Santa Claus as he delivers gifts next week. Speaking tongue-in-cheek, he said if Santa drops anything off his sleigh, "we've got destroyers out there to pick them up." (Dec. 19) Video provided by AP
Powered by NewsLook.com
NASA's Planet-Finding Kepler Mission Isn't Over After All

NASA's Planet-Finding Kepler Mission Isn't Over After All

Newsy (Dec. 18, 2014) More than a year after NASA declared the Kepler spacecraft broken beyond repair, scientists have figured out how to continue getting useful data. Video provided by Newsy
Powered by NewsLook.com
Rover Finds More Clues About Possible Life On Mars

Rover Finds More Clues About Possible Life On Mars

Newsy (Dec. 17, 2014) NASA's Curiosity rover detected methane on Mars and organic compounds on the surface, but it doesn't quite prove there was life ... yet. Video provided by Newsy
Powered by NewsLook.com
Evidence of Life on Mars? NASA Rover Finds Methane, Organic Chemicals

Evidence of Life on Mars? NASA Rover Finds Methane, Organic Chemicals

Reuters - US Online Video (Dec. 16, 2014) NASA's Mars Curiosity rover finds methane in the Martian atmosphere and organic chemicals in the planet's soil, the latest hint that Mars was once suitable for microbial life. Linda So reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

More Coverage


Astronomers Discover Densest Galaxy Ever

Sep. 24, 2013 Imagine the distance between the sun and the star nearest to it -- a star called Alpha Centauri. That's a distance of about four light years. Now, imagine as many as 10,000 of our suns crammed ... read more

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins