Featured Research

from universities, journals, and other organizations

Stars Evolve Rapidly, Violently In Ultra-luminous Infrared Galaxies

Date:
February 20, 2006
Source:
Cornell University
Summary:
The Spitzer Space Telescope reveals new information about the composition of distant ultra-luminous infrared galaxies. A high proportion of crystalline silicates in the galaxies' general interstellar medium indicates a large population of massive young and rapidly evolving stars.

This image illustrates how two galaxies could be torn apart by their mutual attraction, causing whole strains of stars to be catapulted out to form something like antennae. The galaxies' nuclei would dance around each other and eventually merge to form a single nucleus.
Credit: Image courtesy of Cornell University News Service

The discovery makes the fiery environment within a typical spiral or starburst galaxy look almost pastoral. Cornell researchers using the Spitzer Space Telescope say distant galaxies contain an inferno of very young, massive and violently evolving stars, packed together in tiny but extremely powerful cosmic globs.

Related Articles


The key to the discovery, paradoxically, is in the presence of delicate, glittery crystalline silicates called Forsterite. These are glassy particles that exist in the debris disks of young stars and in the stellar wind of very old stars, but which have never before been observed in the mass of gas and dust known as the interstellar medium, or ISM, in the Milky Way or in any other galaxy.

The research, led by Cornell astronomer and Spitzer Fellow Henrik Spoon, will appear in the Feb. 20 issue of the Astrophysical Journal.

Using Spitzer's infrared spectrograph (IRS), an instrument developed by a team led by Cornell professor of astronomy James Houck and built at Cornell, Spoon and colleagues observed dozens of distant galaxies known as ultra-luminous infrared galaxies (ULIRGs). First discovered in large numbers in 1982, most ULIRGs are thought to form as two or more spiral galaxies collide (as our galaxy will, in a few billion years, with the nearby Andromeda galaxy), and their leftover hydrogen gas fuels the fierce, rapid formation of massive stars.

ULIRGs are relative runts in galactic terms (though some have sweeping tidal tails), with the source of their luminosity coming from an area as small as one-hundredth that of typical galaxies. Seen with an optical telescope, they look dusty, chaotic and unspectacular. But in the mid-infrared spectrum, said Spoon, "they are booming," appearing up to 100 times more luminous than a spiral or starburst galaxy.

Silicates are the most common types of minerals in the Milky Way, so their presence in ULIRGs is not surprising. But among the silicates, most (95 percent in the immediate vicinity of rapidly evolving stars and at least 99 percent in the general ISM) are amorphous in structure.

Spoon and his team saw the expected broad absorption features of amorphous silicates in the infrared spectra of the ULIRGs they observed. But they also saw signature narrow dips within the broad bumps indicating the presence of silicates in crystalline form in the general ISM. The concentration of crystalline silicates in at least 21 ULIRGs, Spoon found, is seven to 15 times greater than in any other known environment.

In our galaxy, crystalline silicates have only been observed close to active new stars, which inject them into their immediate environment as they evolve, and in the exhaled winds of dying stars. Subject to heavy pummeling by destructive cosmic and shock-accelerated ions, the silicates quickly lose their ordered, crystalline structure and take an amorphous shape.

"We were surprised to find such delicate little crystals in the centers of some of the most violent places in the universe," said Spoon. "Given the rapid transformation of crystalline silicates to an amorphous state, the injection rate of freshly produced crystalline silicates must be far higher than in our galaxy. We're probing exotic circumstances."

Spitzer's IRS, which can record infrared spectra from objects fainter and farther away than ever before, has allowed astronomers to study ULIRGs and other stellar nurseries in new detail.

"Now we can take a good look at what these characteristics are," said Spoon. "It's like, for the first time, you put on a pair of glasses, and -- wow."

The Spitzer Space Telescope is the last of NASA's Great Observatories. The Jet Propulsion Laboratory, a division of the California Institute of Technology, manages the Spitzer mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech.


Story Source:

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


Cite This Page:

Cornell University. "Stars Evolve Rapidly, Violently In Ultra-luminous Infrared Galaxies." ScienceDaily. ScienceDaily, 20 February 2006. <www.sciencedaily.com/releases/2006/02/060220102950.htm>.
Cornell University. (2006, February 20). Stars Evolve Rapidly, Violently In Ultra-luminous Infrared Galaxies. ScienceDaily. Retrieved November 28, 2014 from www.sciencedaily.com/releases/2006/02/060220102950.htm
Cornell University. "Stars Evolve Rapidly, Violently In Ultra-luminous Infrared Galaxies." ScienceDaily. www.sciencedaily.com/releases/2006/02/060220102950.htm (accessed November 28, 2014).

Share This


More From ScienceDaily



More Space & Time News

Friday, November 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Scientists Find Invisible Space Shield Protecting Earth

Scientists Find Invisible Space Shield Protecting Earth

Newsy (Nov. 27, 2014) An invisible barrier is keeping dangerous super fast electrons from interfering with our atmosphere, but scientists aren't entirely sure how. Video provided by Newsy
Powered by NewsLook.com
NASA's First 3-D Printer In Space Creates Its First Object

NASA's First 3-D Printer In Space Creates Its First Object

Newsy (Nov. 26, 2014) The International Space Station is now using a proof-of-concept 3D printer to test additive printing in a weightless, isolated environment. Video provided by Newsy
Powered by NewsLook.com
Feast Your Eyes: Lamb Chop Sent Into Space from UK

Feast Your Eyes: Lamb Chop Sent Into Space from UK

Reuters - Light News Video Online (Nov. 25, 2014) Take a stab at this -- stunt video shows a lamb chop's journey from an east London restaurant over 30 kilometers into space. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Soyuz Spacecraft Docks With International Space Station: NASA

Soyuz Spacecraft Docks With International Space Station: NASA

AFP (Nov. 24, 2014) A Russian Soyuz spacecraft carrying Italy's first female astronaut safely docks with the International Space Station, according to NASA. Duration: 00:40 Video provided by AFP
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