Subscribe free to our newsletters via your
. 24/7 Space News .




STELLAR CHEMISTRY
The Answer Is Blowing in the Intergalactic Wind
by Staff Writers
Tucson AZ (SPX) Nov 17, 2014


A composite image shows the galaxy NGC 4522 in the Virgo Cluster, the nearest large cluster of galaxies to our own local group of galaxies, and the "wake" of gas and dust being blown from the galaxy. The galaxy appears blue in the Hubble Space Telescope image in visible light. The superimposed red image is from Spitzer data and shows emissions from dust that traces molecular hydrogen. In the image, the galaxy is moving down and into the plane of the photo. Image courtesy Suresh Sivanandam and Dunlap Institute.

Using observation data from the Spitzer and Hubble space telescopes, UA astronomers help solve the mystery of why galaxies produce fewer stars when they occur in clusters.

Astronomers from the University of Toronto and the University of Arizona have provided the first direct evidence that an intergalactic "wind" is stripping galaxies of star-forming gas as they fall into clusters of galaxies. The observations help explain why galaxies found in clusters are known to have relatively little gas and less star formation when compared to non-cluster or "field" galaxies.

Astronomers have theorized that as a field galaxy falls into a cluster of galaxies, it encounters the cloud of hot gas at the center of the cluster. As the galaxy moves through this intracluster medium at thousands of kilometers per second, the cloud acts like a wind, blowing away the gas within the galaxy without disturbing its stars. The process is known as ram-pressure stripping.

Previously, astronomers had seen the very tenuous atomic hydrogen gas surrounding a galaxy get stripped. But it was believed that the denser molecular hydrogen clouds where stars form would be more resistant to the wind.

"However, we found that the molecular hydrogen gas is also blown from the in-falling galaxy," said Suresh Sivanandam of the Dunlap Institute at the University of Toronto, "much like smoke blown from a candle being carried into a room."

Previous observations showed indirect evidence of ram-pressure stripping of star-forming gas. Astronomers have observed young stars trailing from a galaxy; the stars would have formed from gas newly stripped from the galaxy. A few galaxies also have tails of very tenuous gas. But the latest observations show the stripped, molecular hydrogen itself, which can be seen as a wake trailing from the galaxy in the direction opposite to its motion.

"For more than 40 years, we have been trying to understand why galaxies in dense clusters have so few young stars compared with ones like our Milky Way galaxy, but now we see the quenching of star formation in action," said George Rieke, a Regents' Professor at the UA's Department of Astronomy and Steward Observatory.

"Cutting off the gas that forms stars is a key step in the evolution of galaxies from the early universe to the present."

The results, published in the Astrophysical Journal, are from observations of four galaxies. Sivanandam, Rieke and his wife and colleague, Marcia Rieke, also a Regents' Professor at the UA's Department of Astronomy and Steward Observatory, already had established that one of the four galaxies had been stripped of its star-forming gas by this wind. But by observing four galaxies, they have now shown that this effect is common.

The team made its analysis using optical, infrared and hydrogen-emission data from the Spitzer and Hubble space telescopes, as well as archival ground-based data. The team used an infrared spectrograph on the Spitzer telscope because direct observation of the molecular hydrogen required observations in the mid-infrared part of the spectrum-something that's almost impossible to do from the ground.

"Seeing this stripped molecular gas is like seeing a theory on display in the sky," Marcia Rieke said. "Astronomers have assumed that something stopped the star formation in these galaxies, but it is very satisfying to see the actual cause."

After Spitzer's expected end of operations later this decade, astronomers will observe the most distant objects in the universe with the James Webb Space Telescope, or JWST, currently under construction and planned for launch in late 2018. Like Spitzer, JWST will use technology developed at the UA: a mid-infrared-wavelength camera developed by George Rieke and a near-infrared-wavelength camera developed by his wife.

Marcia Rieke has been heralded for the international effort that she has led on the Spitzer space telescope to conduct very deep surveys at far-infrared wavelengths, which will allow astronomers to trace the history of star formation back in time 10 billion years. She is the principal investigator for the near-infrared camera, or NIRCam, on the JWST, the largest space telescope ever conceived. NIRCam will study infrared light.

Together with her husband, who led one of the instrument-developing teams on the Spitzer telescope project, Marcia Rieke co-authored a paper on the infrared interstellar extinction law - one of the most cited papers in all of astronomy. Many of her most-cited papers on radiation from galactic nuclei and starbursts in colliding galaxies are considered classics in the field.


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only


.


Related Links
University of Arizona
Stellar Chemistry, The Universe And All Within It






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle








STELLAR CHEMISTRY
The Answer is Blowing in the Intergalactic Wind
Toronto, Canada (SPX) Nov 14, 2014
Astronomers from the University of Toronto and the University of Arizona have provided the first direct evidence that an intergalactic "wind" is stripping galaxies of star-forming gas as they fall into clusters of galaxies. The observations help explain why galaxies found in clusters are known to have relatively little gas and less star formation when compared to non-cluster or "field" galaxies. ... read more


STELLAR CHEMISTRY
After Mars, India space chief aims for the moon

China examines the three stages of lunar test run

China gears up for lunar mission after round-trip success

NASA's LRO Spacecraft Captures Images of LADEE's Impact Crater

STELLAR CHEMISTRY
Warmth and flowing water on early Mars were episodic

Next NASA Mars Mission Reaches Milestone

Mars, too, has macroweather

Comet lander 'working well', but may be on slope

STELLAR CHEMISTRY
Tencent looks to the final travel frontier

ESA Commissions Airbus As contractor For Orion Service Module

Study Investigates How Men and Women Adapt Differently to Spaceflight

S3 concludes first phase of drop-tests

STELLAR CHEMISTRY
China publishes Earth, Moon photos taken by lunar orbiter

China plans to launch about 120 applied satellites

Mars probe to debut at upcoming air show

China to build global quantum communication network in 2030

STELLAR CHEMISTRY
Europe's 3D printer set for ISS

NASA Commercial Crew Partners Continue System Advancements

Astronaut turned Twitter star, Reid Wiseman, back on Earth

Three-man multinational space crew returns to Earth

STELLAR CHEMISTRY
Time-lapse video shows Orion's move to Cape Canaveral launch pad

Soyuz Installed at Baikonur, Expected to Launch Wednesday

SpaceX chief Musk confirms Internet satellite plan

Orbital recommits to NASA Commercial program and Antares

STELLAR CHEMISTRY
Follow the Dust to Find Planets

NASA's TESS mission cleared for next development phase

ADS primes ESA's CHEOPS to detect and classify exoplanets

NASA's TESS Mission Cleared for Next Development Phase

STELLAR CHEMISTRY
Shaking the topological cocktail of success

Drexel Engineers Improve Strength, Flexibility of Atom-Thick Films

Creating Bright X-Ray Pulses in the Laser Lab

New Process Isolates Promising Material




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.