Featured Research

from universities, journals, and other organizations

Scientists 'Weigh' Tiny Galaxy Halfway Across Universe

Date:
October 8, 2007
Source:
University of California, Santa Barbara
Summary:
A tiny galaxy, nearly halfway across the universe, the smallest in size and mass known to exist at that distance, has been identified. The galaxy is about half the size, and approximately one-tenth the "weight" of the smallest distant galaxies typically observed, and it is 100 times lighter than our own Milky Way.

Color composite image of the gravitational lens system, made from Hubble (blue and green) and Keck (red) data. The blue ring is the tiny background galaxy, stretched by the gravitational pull of the foreground lens galaxy at the center of the image.
Credit: Marshall & Treu (UCSB)

A tiny galaxy, nearly halfway across the universe, the smallest in size and mass known to exist at that distance, has been identified by an international team of scientists led by two from the University of California, Santa Barbara.

The scientists used data collected by NASA's Hubble Space Telescope and the W. M. Keck Observatory in Hawaii. This galaxy is about half the size, and approximately one-tenth the "weight" of the smallest distant galaxies typically observed, and it is 100 times lighter than our own Milky Way.

"Even though this galaxy is more than six billion light years away, the reconstructed image is as sharp as the ordinary ground-based images of the nearest structure of galaxies, the Virgo cluster, which is 100 times closer to us," said lead author Phil Marshall, a postdoctoral fellow at UC Santa Barbara.

Second author Tommaso Treu, assistant professor of physics at UCSB, explained that the imaging is made possible by the fact that the newly discovered galaxy is positioned behind a massive galaxy, creating an "Einstein ring." The matter distribution in the foreground bends the light rays in much the same way a magnifying glass does. By focusing the light rays, this gravitational lensing effect increases the apparent brightness and size of the background galaxy by more than a factor of 10.

Treu and his colleagues in the Sloan Lens ACS Survey (SLACS) collaboration are at the forefront of the study of Einstein ring gravitational lenses. With gravitational lensing, light from distant galaxies is deflected on its way to Earth by the gravitational field of any massive object that lies in the way. Because the light bends, the galaxy is distorted into an arc or multiple separate images. When both galaxies are exactly lined up, the light forms a bull's-eye pattern, called an Einstein ring, around the foreground galaxy.

The mass estimate for the galaxy, and the inference that many of its stars have only recently formed, is made possible by the combination of optical and near infrared images from the Hubble Space Telescope with longer wavelength images obtained with the Keck Telescope. "If the galaxy is representative of a larger population, it could be one of the building blocks of today's spiral galaxies, or perhaps a progenitor of modern dwarf galaxies," said Treu. "It does look remarkably similar to the smallest galaxies in the Virgo cluster, but is almost half the way across the universe."

Another key aspect of the research is the use of "laser guide star adaptive optics." Adaptive optics systems use bright stars in the field of view to measure the Earth's atmospheric blurring and correct for it in real time. This technique relies on having a bright star in the image as well, so it is limited to a small fraction of the night sky.

The laser guide star adaptive optics system in place at the Keck Telescope uses a powerful laser to illuminate the layer of sodium atoms that exist in the Earth's atmosphere, explained Jason Melbourne, a team member from the Center for Adaptive Optics at the University of California, Santa Cruz. The laser image acts as an artificial star, bright enough to perform adaptive optics correction at an arbitrary position in the sky, thus enabling much sharper imaging over most of the sky.

Marshall's postdoctoral fellowship research is funded by the TABASGO Foundation through UCSB. Treu's research is supported by the National Aeronautical and Space Administration (NASA), the National Science Foundation, and the Sloan Foundation.

Other researchers involved in the project are: Raphael Gavazzi of UC Santa Barbara; Kevin Bundy of the University of Toronto; S. Mark Ammons of Lick Observatory and the Center for Adaptive Optics (CfAO) at the University of California, Santa Cruz; Adam S. Bolton of the Institute for Astronomy at the University of Hawaii; Scott Burles of the Massachusetts Institute of Technology; James Larkin of the University of California, Los Angeles; David Le Mignant of the W. M. Keck Observatory and CfAO at UC Santa Cruz; David C. Koo of the Lick Observatory at UC Santa Cruz; Leon V.E. Koopmans of the Kapteyn Astronomical Institute, the Netherlands; Claire E. Max of the Lick Observatory and CfAO at UC Santa Cruz; Leonidas A. Moustakas of the Jet Propulsion Laboratory and the California Institute of Technology; Eric Steinbring of the Herzberg Institute of Astrophysics, National Research Council of Canada; and Shelly A. Wright of UCLA.

The findings will be published in the December 20, 2007 issue of the Astrophysical Journal.


Story Source:

The above story is based on materials provided by University of California, Santa Barbara. Note: Materials may be edited for content and length.


Cite This Page:

University of California, Santa Barbara. "Scientists 'Weigh' Tiny Galaxy Halfway Across Universe." ScienceDaily. ScienceDaily, 8 October 2007. <www.sciencedaily.com/releases/2007/10/071004085224.htm>.
University of California, Santa Barbara. (2007, October 8). Scientists 'Weigh' Tiny Galaxy Halfway Across Universe. ScienceDaily. Retrieved April 21, 2014 from www.sciencedaily.com/releases/2007/10/071004085224.htm
University of California, Santa Barbara. "Scientists 'Weigh' Tiny Galaxy Halfway Across Universe." ScienceDaily. www.sciencedaily.com/releases/2007/10/071004085224.htm (accessed April 21, 2014).

Share This



More Space & Time News

Monday, April 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

SpaceX's Dragon Spacecraft Captured by International Space Station

SpaceX's Dragon Spacecraft Captured by International Space Station

Reuters - US Online Video (Apr. 20, 2014) SpaceX's unmanned Dragon spacecraft makes a scheduled Easter Sunday rendezvous with the International Space Station. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Raw: Easter Morning Delivery for Space Station

Raw: Easter Morning Delivery for Space Station

AP (Apr. 20, 2014) Space station astronauts got a special Easter treat: a cargo ship full of supplies. The SpaceX company's cargo ship, Dragon, spent two days chasing the International Space Station following its launch from Cape Canaveral. (April 20) Video provided by AP
Powered by NewsLook.com
Extremely Large Telescope Could Spot Alien Life

Extremely Large Telescope Could Spot Alien Life

Newsy (Apr. 20, 2014) Scientists are preparing to blow up a Chilean mountain to construct the Extremely Large Telescope, which will take detailed pictures of exoplanets. Video provided by Newsy
Powered by NewsLook.com
A Hoax? Cosmetics Company Wants To Brighten The Moon

A Hoax? Cosmetics Company Wants To Brighten The Moon

Newsy (Apr. 19, 2014) FOREO, a Swedish cosmetics company, says it wants to brighten the moon to lower electricity costs. 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:
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