Featured Research

from universities, journals, and other organizations

Case Astronomers Find Vast Stellar Web Spun By Colliding Galaxies

Date:
September 21, 2005
Source:
Case Western Reserve University
Summary:
Case Western Reserve University astronomers have captured the deepest wide-field image ever of the nearby Virgo cluster of galaxies, directly revealing for the first time a vast, complex web of "intracluster starlight" -- nearly 1,000 times fainter than the dark night sky -- filling the space between the galaxies within the cluster.

The deep, wide-field image of the Virgo Cluster, revealing its complex web of diffuse intracluster light. The dark circles are areas where bright foreground stars in our own galaxy have been masked out of the image.
Credit: Image courtesy of Case Western Reserve University

The Virgo imagewas captured through Case's newly refurbished 24-inch Burrell Schmidttelescope, built in the 1930s and located at the Kitt Peak NationalObservatory in Arizona. Over the course of 14 dark moonless nights, theresearchers took more than 70 images of the Virgo Cluster, then usedadvanced image processing techniques to combine the individual imagesinto a single image capable of showing the faint intracluster light.

"Whenwe saw all this very faint starlight in the image, my first reactionwas WOW!," project leader Chris Mihos said. "Then I began to worryabout all the things we could have done wrong." Many effects, such asstray light from nearby stars, from instruments in the observatory andeven from the changing brightness of the night sky could allcontaminate the image and lead to inaccurate results. "But as wecorrected for each of these contaminants, not only did the faintstarlight not disappear, it became even more apparent. That's when weknew we had something big."

The new image gives dramatic evidenceof the violent life and death of cluster galaxies. Drawn together intogiant clusters over the course of cosmic time by their mutual gravity,galaxies careen around in the cluster, smashing into other galaxies,being stripped apart by gravitational forces and even beingcannibalized by the massive galaxies which sit at the cluster's heart.The force of these encounters literally pulls many galaxies apart,leaving behind ghostly streams of stars adrift in the cluster, a fainttribute to the violence of cluster life.

"From computersimulations, we've long suspected this web of intracluster starlightshould be there," says Mihos, associate professor of astronomy at Case,"but it's been extremely hard to map it out because it’s so faint."Mihos and graduate students Craig Rudick (Case) and Cameron McBride(University of Pittsburgh, and former Case undergraduate) havedeveloped computer simulations that track how clusters of galaxiesevolve over time, to study exactly how this intracluster starlight iscreated.

"With the data from the telescope, we see how a clusterlooks today," Mihos explains. "But with computer simulations, we canwatch how a cluster evolves over 10 billion years of time. By comparingthe simulation to the real features we now see in Virgo, we can learnhow the cluster formed and what happened to its many galaxies." Forexample, the fact that the intracluster light in Virgo is so complexand irregular lends credence to the theory of "hierarchical assembly,"where clusters grow sporadically when groups of galaxies fall into thecluster, rather than through the smooth, slow addition of galaxies oneby one.

To detect the faint intracluster light, upgrades wereneeded to Case's Burrell Schmidt telescope, originally part of theoriginal Warner and Swasey Observatory in Cleveland until its move toKitt Peak in 1979. The improvements included the installation of a newcamera system and upgrades to the telescope to make it morestructurally stable and reduce unwanted scattered light.

"It'slike ‘The Little Engine that Could’," says Case astronomer PaulHarding, who directed the refurbishment of the telescope. "It's thesmallest telescope on the mountain, but with these upgrades it'scapable of some pretty incredible science." The telescope's wide fieldof view -- enough to fit three full moons across the image – provedcrucial to the project, allowing the team to map out the intraclusterlight over a much larger part of the Virgo Cluster than would bepossible using larger telescopes with their much smaller fields of view.

TheVirgo Cluster of galaxies -- so named because it appears in theconstellation of Virgo -- is the nearest galaxy cluster to the Earth,at a distance of approximately 50 million light years. The clustercontains more than 2,000 galaxies, the brightest of which can be seenwith the aide of a small telescope.

The Case findings arereported in the paper "Diffuse Light in the Virgo Cluster" to bepublished in the September 20th issue of The Astrophysical JournalLetters. Along with Mihos team researchers included Case astronomersHeather Morrison and Paul Harding, and John Feldmeier, a NationalScience Foundation Fellow at the National Optical Astronomy Observatoryin Tucson, Ariz. (and formerly of Case).

The wide-field image ofthe Virgo Cluster, along with movies of computer simulations ofgalaxies and galaxy clusters, can be found athttp://astroweb.case.edu/hos/Virgo.


Story Source:

The above story is based on materials provided by Case Western Reserve University. Note: Materials may be edited for content and length.


Cite This Page:

Case Western Reserve University. "Case Astronomers Find Vast Stellar Web Spun By Colliding Galaxies." ScienceDaily. ScienceDaily, 21 September 2005. <www.sciencedaily.com/releases/2005/09/050921081209.htm>.
Case Western Reserve University. (2005, September 21). Case Astronomers Find Vast Stellar Web Spun By Colliding Galaxies. ScienceDaily. Retrieved October 22, 2014 from www.sciencedaily.com/releases/2005/09/050921081209.htm
Case Western Reserve University. "Case Astronomers Find Vast Stellar Web Spun By Colliding Galaxies." ScienceDaily. www.sciencedaily.com/releases/2005/09/050921081209.htm (accessed October 22, 2014).

Share This



More Space & Time News

Wednesday, October 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Comet Siding Spring Grazes Mars' Atmosphere

Comet Siding Spring Grazes Mars' Atmosphere

Newsy (Oct. 19, 2014) A comet from the farthest reaches of the solar system passed extremely close to Mars this weekend, giving astronomers a rare opportunity to study it. Video provided by Newsy
Powered by NewsLook.com
Latin America Launches Communications Satellite

Latin America Launches Communications Satellite

AFP (Oct. 17, 2014) Argentina launches a home-built satellite, a first for Latin America. It will ride a French-made Ariane 5 rocket into orbit, and will provide cell phone, digital TV, Internet and data services to the lower half of South America. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
This Week @ NASA, October 17, 2014

This Week @ NASA, October 17, 2014

NASA (Oct. 17, 2014) Power spacewalk, MAVEN’s “First Light”, Hubble finds extremely distant galaxy and more... Video provided by NASA
Powered by NewsLook.com
Saturn's 'Death Star' Moon Might Have A Hidden Ocean

Saturn's 'Death Star' Moon Might Have A Hidden Ocean

Newsy (Oct. 17, 2014) The smallest of Saturn's main moons, Mimas, wobbles as it orbits. Research reveals it might be due to a global ocean underneath its icy surface. Video provided by Newsy
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:

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