Featured Research

from universities, journals, and other organizations

Astronomers explain why disk galaxies eventually look alike

Date:
September 11, 2013
Source:
Iowa State University
Summary:
Astronomers have discovered the fundamental process responsible for the smooth, steady fade of older disk galaxies. They say the key is the clumps of interstellar gases and new stars within young galaxy disks.

Iowa State's Curtis Struck and IBM's Bruce Elmegreen are studying how galaxies evolve from the clumpy example on the left to the smooth example on the right.
Credit: Images by the Sloan Digital Sky Survey

It happens to all kinds of flat, disk galaxies -- whether they're big, little, isolated or crowded in a cluster. They all grow out of their irregular, clumped appearance and their older stars take on the same smooth look, predictably fading from a bright center to a dim edge.

Or, as Curtis Struck, an Iowa State University astronomer, wrote in a research summary: "In galaxy disks, the scars of a rough childhood, and adolescent blemishes, all smooth away with time."

But how does that happen?

Struck, a professor of physics and astronomy who studies galaxy evolution and wrote the 2011 book "Galaxy Collisions," said a few explanations have been proposed, but most of those only covered certain types of galaxies. There hasn't been an explanation for the nearly universal and exponential fade in the brightness of the lookalike disk galaxies.

To try to find an explanation, Struck and Bruce Elmegreen, a research scientist at IBM's Thomas J. Watson Research Center in Yorktown Heights, N.Y., built computer models simulating galaxy evolution. And they think they've found a fundamental answer in the gravitational pull of the irregular, clumped structure of younger galaxies.

Struck and Elmegreen based their paper on the simplest possible galaxy model that still includes all the essential ingredients: a razor-thin disk and orbiting stars subject to the gravity of the massive clumps.

"We focused on the clumps," Struck said. "We thought the clumpy structure of young galaxy disks may be responsible for both its own erasure and the smooth universal brightness profile."

Struck said the models showed that's the case. The gravity of those clumps of interstellar gases and new stars alter the orbits of nearby stars. In some cases, the changes are significant, scattering stars well away from their original and nearly circular orbits.

Over time, that scattering from circular to slightly elliptical orbits produces the smooth fade in brightness from the center of a galaxy to its edge.

We're talking a lot of time: "This process takes a few hundred million years to a few billion years," Struck said.

Do those findings match the data coming from the Hubble Space Telescope and large ground-based telescopes, tools that allow astronomers to see distant galaxies in their young and clumpy structure?

"Yes, they do fit the observed data coming back," Struck said.

Struck also said there's more work to be done to explain the mystery of the smooth, steady fade of older disk galaxies. Struck and Elmegreen will gradually add more physical processes to their models to see how additional complexities affect what they've discovered about the fundamental process of star scattering.

Even so, Struck said the current models have provided a good explanation for the universal appearance of older disk galaxies.

"If there is some disturbance, some clumpiness in the galaxy," he said, "you eventually get this smooth profile."


Story Source:

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


Journal Reference:

  1. Bruce G. Elmegreen, Curtis Struck. EXPONENTIAL GALAXY DISKS FROM STELLAR SCATTERING. The Astrophysical Journal, 2013; 775 (2): L35 DOI: 10.1088/2041-8205/775/2/L35

Cite This Page:

Iowa State University. "Astronomers explain why disk galaxies eventually look alike." ScienceDaily. ScienceDaily, 11 September 2013. <www.sciencedaily.com/releases/2013/09/130911131744.htm>.
Iowa State University. (2013, September 11). Astronomers explain why disk galaxies eventually look alike. ScienceDaily. Retrieved September 30, 2014 from www.sciencedaily.com/releases/2013/09/130911131744.htm
Iowa State University. "Astronomers explain why disk galaxies eventually look alike." ScienceDaily. www.sciencedaily.com/releases/2013/09/130911131744.htm (accessed September 30, 2014).

Share This



More Space & Time News

Tuesday, September 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

The Water You Drink Might Be Older Than The Sun

The Water You Drink Might Be Older Than The Sun

Newsy (Sep. 27, 2014) — Researchers at the University of Michigan simulated the birth of planets and our sun to determine whether water in the solar system predates the sun. Video provided by Newsy
Powered by NewsLook.com
First Woman Cosmonaut in 17 Years Blasts Off for ISS

First Woman Cosmonaut in 17 Years Blasts Off for ISS

AFP (Sep. 26, 2014) — A Russian Soyuz spacecraft carrying an American astronaut and two Russian cosmonauts, including the first woman cosmonaut in 17 years, blasted off on schedule Friday. Duration: 00:35 Video provided by AFP
Powered by NewsLook.com
Water Discovery On Small Planet Could Be Key To Earth 2.0

Water Discovery On Small Planet Could Be Key To Earth 2.0

Newsy (Sep. 25, 2014) — Scientists have discovered traces of water in the atmosphere of a distant, Neptune-sized planet. Video provided by Newsy
Powered by NewsLook.com
Raw: US-Russian Crew Lifts Off for Space Station

Raw: US-Russian Crew Lifts Off for Space Station

AP (Sep. 25, 2014) — A U.S.-Russian space crew has blasted off successfully for the International Space Station. The Russian Soyuz-TMA14M spacecraft lifted off from the Russian-leased Baikonur launch facility in Kazakhstan. (Sept. 25) Video provided by AP
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