(Press-News.org) New observations by NASA's Hubble Space Telescope are expanding astronomers' understanding of the ways in which galaxies continuously recycle immense volumes of hydrogen gas and heavy elements. This process allows galaxies to build successive generations of stars stretching over billions of years.
This ongoing recycling keeps some galaxies from emptying their "fuel tanks" and stretches their star-forming epoch to over 10 billion years.
This conclusion is based on a series of Hubble Space Telescope observations that flexed the special capabilities of its Cosmic Origins Spectrograph (COS) to detect gas in the halo of our Milky Way and more than 40 other galaxies. Data from large ground-based telescopes in Hawaii, Arizona and Chile also contributed to the studies by measuring the properties of the galaxies.
Astronomers believe that the color and shape of a galaxy is largely controlled by gas flowing through an extended halo around it. The three studies investigated different aspects of the gas-recycling phenomenon.
The results are being published in three papers in the November 18 issue of Science magazine. The leaders of the three studies are Nicolas Lehner of the University of Notre Dame in South Bend, Ind.; Jason Tumlinson of the Space Telescope Science Institute in Baltimore, Md.; and Todd Tripp of the University of Massachusetts at Amherst.
The COS observations of distant stars demonstrate that a large mass of clouds is falling through the giant halo of our Milky Way, fueling its ongoing star formation. These clouds of hot hydrogen reside within 20,000 light-years of the Milky Way disk and contain enough material to make 100 million suns. Some of this gas is recycled material that is continually being replenished by star formation and the explosive energy of novae and supernovae, which kicks chemically enriched gas back into the halo.
The COS observations also show halos of hot gas surrounding vigorous star-forming galaxies. These halos, rich in heavy elements, extend as much as 450,000 light-years beyond the visible portions of their galactic disks. The amount of heavy-element mass discovered far outside a galaxy came as a surprise. COS measured 10 million solar masses of oxygen in a galaxy's halo, which corresponds to about one billion solar masses of gas -- as much as in the entire space between stars in a galaxy's disk.
Researchers also found that this gas is nearly absent from galaxies that have stopped forming stars. In these galaxies, the "recycling" process ignites a rapid firestorm of star birth which can blow away the remaining fuel, essentially turning off further star-birth activity.
This is evidence that gas pushed out of a galaxy, rather than pulled in from intergalactic space, determine a galaxy's fate."
The Hubble observations demonstrate that those galaxies forming stars at a very rapid rate, perhaps a hundred solar masses per year, can drive two-million-degree gas very far out into intergalactic space at speeds of up to two million miles per hour. That's fast enough for the gas to escape forever and never refuel the parent galaxy.
While hot gas "winds" from galaxies have been known for some time, the new COS observations reveal that hot outflows extend to much greater distances than previously thought and can carry a tremendous amount of mass out of a galaxy. Some of the hot gas is moving more slowly and could eventually be recycled. The observations show how gas-rich star-forming spiral galaxies can evolve to elliptical galaxies that no longer have star formation.
The light emitted by this hot plasma is invisible, so the researchers used COS to detect the presence of the gas by the way it absorbs certain colors of light from background quasars. Quasars are the brightest objects in the universe and are the brilliant cores of active galaxies that contain active central black holes. The quasars serve as distant lighthouse beacons that shine through the gas-rich "fog" of hot plasma encircling galaxies. At ultraviolet wavelengths, COS is sensitive to the presence of heavy elements, such as nitrogen, oxygen, and neon. COS's high sensitivity allows many galaxies to be studied that happen to lie in front of the much more distant quasars. The ionized heavy elements are markers for estimating how much mass is in a galaxy's halo.
INFORMATION:
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 (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.
NASA's Hubble confirms that galaxies are the ultimate recyclers
2011-11-21
[Attachments] See images for this press release:
ELSE PRESS RELEASES FROM THIS DATE:
Assembly stand completed for NASA's Webb Telescope flight optics
2011-11-21
GREENBELT, Md. -- The cleanroom at NASA's Goddard Space Flight Center in Greenbelt, Md. has received a giant structural steel frame that will be used to assemble the mirrors and instruments of the James Webb Space Telescope.
"This milestone is important as it marks the transition to the integration and testing phase for the Webb telescope's optical telescope element," said Lee Feinberg, Optical Telescope Element Manager for the Webb telescope at Goddard.
The Webb telescope is the world's next-generation space observatory and scientific successor to the Hubble Space ...
UGA researchers develop 'super' yeast that turns pine into ethanol
2011-11-21
Athens, Ga. – Researchers at the University of Georgia have developed a "super strain" of yeast that can efficiently ferment ethanol from pretreated pine -- one of the most common species of trees in Georgia and the U.S. Their research could help biofuels replace gasoline as a transportation fuel.
"Companies are interested in producing ethanol from woody biomass such as pine, but it is a notoriously difficult material for fermentations," said Joy Doran-Peterson, associate professor of microbiology in the Franklin College of Arts and Sciences.
"The big plus for softwoods, ...
Combo hormone therapy has increased breast cancer risk over estrogen alone
2011-11-21
The debate about using menopausal hormone therapies to relieve symptoms in post-menopausal women has been ongoing. Is the combination therapy of estrogen and progestin better or worse than just giving women estrogen alone? In women who still have a uterus (those who have not had a hysterectomy), progestin counteracts the increased risk of uterus cancer when estrogen is given alone, but at the expense of an increase in breast cancer risk compared to estrogen alone.
Now a study by researchers at UCLA's Jonsson Comprehensive Cancer Center has found that women taking the ...
Recent advance in detonation theory
2011-11-21
A detonation wave is a chemical reaction wave propagating at the velocity of a shock wave along the explosive charge. There is great demand for a detonation model that can accurately simulate the detonation process, which would provide a theoretical basis for highly efficient military destruction, the initiation of an atomic bomb, and calculations relating to the supernova SN Ia explosion. Detonation is complicated in that it involves mechanics, chemistry and thermodynamics simultaneously. The detonation product particles move multi-dimensionally, and there are transport ...
Corals can sense what's coming
2011-11-21
Australian scientists have thrown new light on the mechanism behind the mass death of corals worldwide as the Earth's climate warms.
Coral bleaching, one of the most devastating events affecting coral reefs around the planet, is triggered by rising water temperatures. It occurs when the corals and their symbiotic algae become heat-stressed, and the algae which feed the corals either die or are expelled by the coral.
There have been seven major bleaching events globally in the past 30 years, the most recent being in 2010 across the Indian Ocean and Coral Triangle. Australia's ...
Heart rate recovery predicts clinical worsening in pulmonary hypertension
2011-11-21
Heart rate recovery at one minute after a six-minute walking distance (6MWD) test is highly predictive of clinical worsening and time to clinical worsening in patients with idiopathic pulmonary arterial hypertension (IPAH), according to a new study.
"Ours is the first study to show that heart rate recovery at one minute of rest (HRR1) following a 6MW test is a strong predictor of clinical worsening in IPAH patients," said Omar A. Minai, MD, staff physician in the Department of Pulmonary, Allergy, and Critical Care Medicine at the Cleveland Clinic. "Predicting long-term ...
Metabolic syndrome biomarkers predict lung function impairment after exposure to WTC dust
2011-11-21
Metabolic syndrome biomarkers predict subsequent decline in lung function after particulate exposure, according to new research involving rescue personnel exposed to World Trade Center (WTC) dust.
In a nested case-control study of 327 non-smoking FDNY 9/11 rescue workers, metabolic syndrome biomarkers measured within six months of exposure to WTC dust predicted decline of forced expiratory volume in one second (FEV1) over the next six years.
"Study participants with dyslipidemia, elevated heart rate or elevated leptin levels had a significantly increased risk of developing ...
As probiotics use grows for gut health, VSL#3 has designations for specific GI issues
2011-11-21
GAITHERSBERG, MD, Nov. 18 – As clinical studies continue to validate the use of probiotics to help promote general gastrointestinal health, a growing U.S. market1 for probiotics indicates that the U.S. healthcare community and consumers alike are recognizing the value of these beneficial microorganisms. However, because most probiotics are classified as dietary supplements, directing patients to the best probiotic for their individual needs can be challenging. And, as the category matures, one probiotic preparation -- VSL#3 -- stands apart and ahead because it is not a ...
The protest vote prevails when a landslide victory is expected
2011-11-21
Researchers at the Juan March foundation and the Duke University (USA) have analysed the reason for casting a protest vote as a way of expressing unhappiness with a party during elections. Moderate voters are more likely to vote in this way than those at the extreme left or extreme right of the political spectrum.
Daniel Kselman, researcher at the Juan March Foundation and co-author of the study that analyses such behaviour states that "the protest vote is just a way of expressing discontent. In order for it to be effective, a lot more voters from your party need to vote ...
NRL Monterey develops more accurate tropical cyclone prediction model
2011-11-21
WASHINGTON -- Researchers at the Naval Research Laboratory (NRL) Marine Meteorology Division (MMD), Monterey, Calif., have developed the Coupled Ocean/Atmosphere Mesoscale Prediction System Tropical Cyclone (COAMPS-TC™) model, achieving a significant research milestone in predictions of tropical cyclone intensity and structure.
While the predictions of the paths or tracks of hurricanes, more generally referred to as tropical cyclones (TC), have steadily improved over the last few decades, improvements in the predictions of storm intensity have proven much more difficult.
"Over ...