Featured Research

from universities, journals, and other organizations

Multiple Galaxy Collisions Surprise Hubble Astronomers

Date:
November 22, 1999
Source:
Space Telescope Science Institute
Summary:
Hubble astronomers conducting research on a class of galaxies called ultra-luminous infrared galaxies (ULIRG) have discovered that over two dozen of these are found within "nests" of galaxies, apparently engaged in multiple collisions that lead to fiery pile-ups of three, four or even five galaxies smashing together.

EMBARGOED UNTIL: 1 a.m. (EST) November 22, 1999

CONTACT: Ray Villard
Space Telescope Science Institute, Baltimore, MD
(Phone: 410-338-4514)
(E-mail: villard@stsci.edu)

Kirk Borne
Goddard Space Flight Center, Greenbelt, MD
(Phone: 301-286-0696)
(E-mail: borne@xfiles.gsfc.nasa.gov)

Hubble astronomers conducting research on a class of galaxies calledultra-luminous infrared galaxies (ULIRG) have discovered that over twodozen of these are found within "nests" of galaxies, apparently engagedin multiple collisions that lead to fiery pile-ups of three, four oreven five galaxies smashing together.

Astronomers previously thought only pairs of galaxies were interactingin ULIRGs. But Hubble pictures show a surprising amount of complexityand structure that astronomer Kirk Borne of NASA's Goddard Space FlightCenter in Greenbelt, Md., and collaborators, photo-interpret asmultiple galaxy collisions.

Tangled-up looking images from complex computer simulations of multiplegalaxy collisions resemble what Borne sees through Hubble's eye. Forconclusive proof that more than two galaxies are interacting, he plansto do follow-up spectroscopic observations to measure the collisionspeeds of the wayward galaxies.

Using Hubble to conduct a three-year survey of 123 ULIRGs within 3billion light-years of Earth, Borne found that 30% of them show strongvisual evidence for multiple mergers, where astronomers previouslythought only two galaxies were interacting.

"We are seeing the final stage of the hierarchical evolution of theuniverse, where small fragments coalesce to build ever bigger objects,says Borne. "We see matter ripped out of galaxies in the form of longtails of stars, and matter contracting in the form of multiple nucleicrowded together. In some we see a 'nest' of galaxies where they allcoalesce."

These results offer a snapshot of what conditions were like in theearly universe, when galaxy collisions were commonplace.

First detected by the IRAS satellite in the early 1980s, ULIRGs glowfiercely in infrared light, one hundred times brighter than our MilkyWay galaxy. The brilliant infrared (IR) glow of these galaxies iscaused by a firestorm of star birth triggered by the collisions. The IRcomes from a large amount of dust absorbing and re-radiating the lightof the hot newborn stars that precipitated from the collisions.

It was realized early on that ULIRGs are oddly shaped enough to beconsidered pairs of colliding galaxies. It wasn't until 1998 that ateam of Japanese scientists, Y. Taniguchi and Y. Shioya, theorizedthat ULIRGs might be multiple-mergers. "The Hubble results supportthis hypothesis," says Borne.

In research that has been submitted for publication in theAstrophysical Journal Letters, Borne reports that the progenitors tothese bang-ups are probably similar to the so-called Hickson compactgroups -- clusters of at least four galaxies in a tight configurationthat is isolated from other galaxies. Under the relentless pull ofgravity, tidal forces exist which dissipate momentum from the galaxiesand make them fall together.

Borne's co-investigators are Howard Bushouse (Space Telescope ScienceInstitute), Luis Colina (Instituto de Fisica de Cantabria, Spain) andRay Lucas (Space Telescope Science Institute).

The Space Telescope Science Institute is operated by the Associationof Universities for Research in Astronomy, Inc. for NASA, undercontract with NASA's Goddard Space Flight Center, Greenbelt, MD. TheHubble Space Telescope is a project of international cooperationbetween NASA and the European Space Agency.

- end -

NOTE TO EDITORS: Images associated with this release are availableon the Internet at:http://oposite.stsci.edu/pubinfo/pr/1999/45 and via linkshttp://oposite.stsci.edu/pubinfo/latest.htmlhttp://oposite.stsci.edu/pubinfo/pictures.html

Higher resolution digital versions (300 dpi JPEG and TIFF) areavailable at:http://oposite.stsci.edu/pubinfo/pr/1999/45/pr-photos.html

STScI press releases and other information are availableautomatically by sending an Internet electronic mail messageto public-request@stsci.edu. In the body of the message(not the subject line) users should type the word "subscribe"(don't use quotes). The system will respond with a confirmationof the subscription, and users will receive new press releasesas they are issued. To unsubscribe, send mail topublic-request@stsci.edu. Leave the subject line blank,and type "unsubscribe" (don't use quotes) in the body ofthe message.

**************************

PHOTO CAPTION

EMBARGOED UNTIL: 1 a.m. (EST) November 22, 1999

PHOTO NO.: STScI-PRC99-45

MULTIPLE GALAXY COLLISIONS SURPRISE HUBBLE ASTRONOMERS

Astronomers have interpreted the oddly shaped objects in these NASAHubble Space Telescope snapshots as strong visual evidence formultiple galaxies crashing into each other. These smashups create atangled clump of matter and trigger a burst of new stars.

The photo at upper right, for example, appears to possess the nucleiof several galaxies. In another picture [bottom row, center], athree-galaxy collision has ripped several streamers of stars fromtheir homes. The galaxies are converging into one central spot.

The Wide Field and Planetary Camera 2 pictures reveal a surprisingamount of complexity and structure in these galaxies, calledultra-luminous infrared galaxies because they glow fiercely ininfrared light. The bright, infrared glow is caused by a firestorm ofstar birth triggered by the multiple-galaxy pileups.

These images are part of a three-year study of 123 galaxies within 3billion light-years of Earth. The study was conducted in 1996, 1997,and 1999. False colors were assigned to these photos to enhance finedetails within these merging galaxies.

Credits: NASA, Kirk Borne (Raytheon and NASA Goddard Space FlightCenter, Greenbelt, Md.), Luis Colina (Instituto de Fisica de Cantabria,Spain), and Howard Bushouse and Ray Lucas (Space Telescope ScienceInstitute, Baltimore, Md.)


Story Source:

The above story is based on materials provided by Space Telescope Science Institute. Note: Materials may be edited for content and length.


Cite This Page:

Space Telescope Science Institute. "Multiple Galaxy Collisions Surprise Hubble Astronomers." ScienceDaily. ScienceDaily, 22 November 1999. <www.sciencedaily.com/releases/1999/11/991122081943.htm>.
Space Telescope Science Institute. (1999, November 22). Multiple Galaxy Collisions Surprise Hubble Astronomers. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/1999/11/991122081943.htm
Space Telescope Science Institute. "Multiple Galaxy Collisions Surprise Hubble Astronomers." ScienceDaily. www.sciencedaily.com/releases/1999/11/991122081943.htm (accessed July 28, 2014).

Share This




More Space & Time News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Newsy (July 27, 2014) The satellite is back under ground control after a tense few days, but with a gecko sex experiment on board, the media just couldn't help themselves. Video provided by Newsy
Powered by NewsLook.com
NASA EDGE: OCO-2 Launch

NASA EDGE: OCO-2 Launch

NASA (July 25, 2014) NASA EDGE webcasts live from Vandenberg AFB for the launch of the Oribiting Carbon Observatory-2 (OCO) launch. Video provided by NASA
Powered by NewsLook.com
This Week @ NASA, July 25, 2014

This Week @ NASA, July 25, 2014

NASA (July 25, 2014) Apollo 11 celebration, Next Giant Leap anticipation, ISS astronauts appear in the House and more... Video provided by NASA
Powered by NewsLook.com
Space to Ground: Coming and Going

Space to Ground: Coming and Going

NASA (July 25, 2014) One station cargo ship leaves, another arrives, aquatic research and commercial spinoffs. Questions or comments? Use #spacetoground to talk to us. Video provided by NASA
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:
from the past week

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