Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Hubble Catches End of Star-Making Party in Nearby Dwarf Galaxy

15.01.2010
Galaxies throughout the universe are ablaze with star birth. But for a nearby, small spiral galaxy, the star-making party is almost over.

Astronomers were surprised to find that star-formation activities in the outer regions of NGC 2976 have been virtually asleep because they shut down millions of years ago. The celebration is confined to a few die-hard partygoers huddled in the galaxy's inner region.

The explanation, astronomers say, is that a raucous interaction with a neighboring group of hefty galaxies ignited star birth in NGC 2976. Now the star-making fun is beginning to end. Images from NASA's Hubble Space Telescope show that star formation in the galaxy began fizzling out in its outskirts as some of the gas was stripped away and the rest collapsed toward the center. With no gas left to fuel the party, more and more regions of the galaxy are taking a much-needed nap.

"Astronomers thought that grazing encounters between galaxies can cause the funneling of gas into a galaxy's core, but these Hubble observations provide the clearest view of this phenomenon," explains astronomer Benjamin Williams of the University of Washington in Seattle, who directed the Hubble study, which is part of the ACS Nearby Galaxy Survey Treasury (ANGST) program. "We are catching this galaxy at a very interesting time. Another 500 million years and the party will

be over."

NGC 2976 does not look like a typical spiral galaxy. It has a star-forming disk, but no obvious spiral pattern. Its gas is centrally concentrated, but it does not have a central bulge of stars. The galaxy resides on the fringe of the M81 group of galaxies, located about 12 million light-years away in the constellation Ursa Major.

"The galaxy looks weird because an interaction with the M81 group about a billion years ago stripped some gas from the outer parts of the galaxy, forcing the rest of the gas to rush toward the galaxy's center, where it is has little organized spiral structure," Williams says.

The tsunami of gas racing toward the center has fueled rapid star birth for at least the past 500 million years in the relatively armless disk. At the same time, star birth ended in the galaxy's outer regions because the gas ran out. Now, the inner disk is running out of gas as new stars burst to life, shrinking the star-birth zone to a 5,000-light-year-wide area around the core.

"At one point during this process, the density of gas in the inner regions of this galaxy was very high, about five times higher than it is today," explains Julianne Dalcanton of the University of Washington, and leader of the ANGST team. "The gas vanished incredibly fast, and the galaxy now appears to be settling down."

Astronomers pieced together this star-formation story with the help of Hubble's sharp vision. The galaxy's relatively close distance to Earth allowed Hubble's Advanced Camera for Surveys (ACS) to resolve hundreds of thousands of individual stars. By studying those stars, the astronomers determined their color and brightness, which provided information about when the stars formed. The astronomers combined the Hubble results with a map, made from radio observations, showing the current distribution of hydrogen across the galaxy. The map is part of The HI Nearby Galaxy Survey by the National Radio Astronomy Observatory's Very Large Array in New Mexico. By analyzing the combined data, Williams and the team then reconstructed the star-making history for large areas of the galaxy.

"This type of observation is unique to Hubble," Williams says. "If we had not been able to pick out individual stars, we would have known that the galaxy is weird, but we would not have dug up evidence for a significant gas rearrangement in the galaxy, which caused the stellar birth zone to shrink toward the galaxy's center."

Simulations predict that the same "gas-funneling" mechanism may trigger starbursts in the central regions of other dwarf galaxies that interact with larger neighbors. The trick to studying the effects of this process in detail, Williams says, is being able to resolve many individual stars in galaxies to create an accurate picture of their evolution.

Williams' results appear in The Astrophysical Journal (Volume 709, Number 1, 2010).

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute conducts Hubble science operations. The institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc. in Washington.

Donna Weaver | Newswise Science News
Further information:
http://www.stsci.edu
http://hubblesite.org/news/2010/05
http://www.nasa.gov/hubble

Further reports about: ACS Astronomy Galaxy Hubble Hubble Space Telescope NASA NGC 7331 Nearby Space Telescope Star-Making Telescope dwarf star birth

More articles from Physics and Astronomy:

nachricht SF State astronomer searches for signs of life on Wolf 1061 exoplanet
20.01.2017 | San Francisco State University

nachricht Molecule flash mob
19.01.2017 | Technische Universität Wien

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>