(Press-News.org) Astrophysicists have found that contrary to decades of orthodoxy, stars with a high sodium content die before reaching the final, spectacular stages of life.
In a study published today in Nature, an international group of researchers led by Dr Simon Campbell of the Monash Centre for Astrophysics (MoCA), used the European Southern Observatory's 'Very Large Telescope' (VLT) to observe NGC 6752, a globular cluster of stars in our galaxy, 13,000 light years from Earth.
They found that 70 per cent of stars in the tightly bound group fail to reach the final red giant phase. This phase is the last stage of nuclear burning before stars form a planetary nebula, where the gas and dust emitted through copius stellar winds are colourfully illuminated by radiation from the star's naked core.
Dr Campbell said the results were startling because prior to this, it was thought that all low-mass stars, including our Sun, would progress to this final red giant phase.
"We, and other groups in the world, have modeled the entire life-time of these stars and all the models indicate that they pass through this phase. It turns out that the models are not accurately predicting what we have observed here," Dr Campbell said.
"If it were just a small number of stars not making it to this stage, we could put it down to uncertainties in the observations or in the models, but it is a huge proportion of stars - 70 per cent, all those with high sodium content - that are following this newly observed pattern. It can not be ignored."
Globular clusters, which contain about a million stars, are some of the oldest structures in the Universe, having formed shortly after the Big Bang around 14 billion years ago. These very old stars are highly homogenous in mass and age, and so are widely used as natural laboratories for constraining the computer modelling of stars.
Co-author on the paper and Director of MoCA, Professor John Lattanzio, said that the sodium was a marker and unlikely to be the cause of the early death of the stars.
"Although, at this stage, we don't know the causes, this finding affects our understanding of some of the oldest stars in the Universe - stars that we routinely use to compare with our computer models to test how accurate they are," Professor Lattanzio said.
The MoCA group will now observe some of the other 157 globular clusters in the Milky Way to confirm that the pattern holds. They are also working on new theoretical models to try and understand what is causing so many stars to fail to reach a stellar old age.
### END
Low-sodium 'diet' key to a stellar old age
2013-05-30
ELSE PRESS RELEASES FROM THIS DATE:
New possibilities for prostate cancer treatment revealed
2013-05-30
Researchers have identified a sub-group of cells that could contribute to prostate cancer recurrence, opening up new ways to treat the disease, which claims more than 3000 lives a year in Australia.
Published today in Science Translational Medicine, a study led by Monash University researchers has found prostate cancer cells that survive androgen withdrawal treatment. Previously unidentified, these cells are potential targets for future treatments. As they are present early in disease development, there is the possibility of therapy before the cancer reaches the aggressive, ...
Cholesterol sets off chaotic blood vessel growth
2013-05-30
A study at the University of California, San Diego School of Medicine identified a protein that is responsible for regulating blood vessel growth by mediating the efficient removal of cholesterol from the cells. Unregulated development of blood vessels can feed the growth of tumors.
The work, led by Yury Miller, MD, PhD, associate professor of medicine at UC San Diego, will be published in the advance online edition of the journal Nature on May 29.
Cholesterol is a structural component of the cell and is indispensable for normal cellular function, although its excess ...
Super-dense star is first ever found suddenly slowing its spin
2013-05-30
University Park, PA -- One of the densest objects in the universe, a neutron star about 10,000 light years from Earth, has been discovered suddenly putting the brakes on its spinning speed. The event is a mystery that holds important clues for understanding how matter reacts when it is squeezed more tightly than the density of an atomic nucleus -- a state that no laboratory on Earth has achieved. The discovery, by an international team of scientists that includes a Penn State University astronomer, will be published in the journal Nature on 30 May 2013.
The scientists ...
A little less protein may be the answer in neurodegenerative disorders
2013-05-30
HOUSTON -- (May 30, 2013) – In some neurodegenerative diseases, and specifically in a devastating inherited condition called spinocerebellar ataxia 1 (SCA1), the answer may not be an "all-or-nothing," said a collaboration of researchers from Baylor College of Medicine, the Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital and the University of Minnesota in a report that appears online in the journal Nature. The problem might be solved with just a little less.
"If you can only decrease the levels of ataxin-1 (the protein involved in SCA1) ...
Are children who take Ritalin for ADHD at greater risk of future drug abuse?
2013-05-30
UCLA research has shown that that children with attention-deficit hyperactivity disorder are far more likely than other kids to develop serious substance abuse problems as adolescents and adults. But do stimulant medications used to treat ADHD contribute to the risk?
UCLA psychologists have conducted the most comprehensive assessment ever on this question and have found that children with ADHD who take medications such as Ritalin and Adderall are at no greater risk of using alcohol, marijuana, nicotine or cocaine later in life than kids with ADHD who don't take these ...
Arctic current flowed under deep freeze of last ice age, study says
2013-05-30
During the last ice age, when thick ice covered the Arctic, many scientists assumed that the deep currents below that feed the North Atlantic Ocean and help drive global ocean currents slowed or even stopped. But in a new study in Nature, researchers show that the deep Arctic Ocean has been churning briskly for the last 35,000 years, through the chill of the last ice age and warmth of modern times, suggesting that at least one arm of the system of global ocean currents that move heat around the planet has behaved similarly under vastly different climates.
"The Arctic ...
Professor collaborates on most comprehensive analyses of NSAIDs and coxibs
2013-05-30
Charles H. Hennekens, MD, DrPH, the first Sir Richard Doll professor and senior academic advisor to the dean in the Charles E. Schmidt College of Medicine at Florida Atlantic University has published in the current issue of the Lancet the most comprehensive analyses of the benefits and risks of non-steroidal anti-inflammatory drugs (NSAIDs), which include cyclo-oxygenase-2 inhibitors (coxibs).
Hennekens and colleagues from around the world, under the direction of the Clinical Trial Service and Epidemiology Studies Unit at the University of Oxford, conducted a world-wide ...
More precision from less predictability: A new quantum trade-off
2013-05-30
Researchers at Griffith University's Centre for Quantum Dynamics have demonstrated that, contrary to what the Heisenberg uncertainty relation may suggest, particle properties such as position and momentum can be measured simultaneously with high precision.
But it comes at a cost.
The findings have been published in Experimental Test of Universal Complementarity Relations in the prestigious journal Physical Review Letters.
Co-author Dr Michael Hall said the work represents an important advance in the quantitative understanding and experimental verification of complementarity; ...
Even short bouts of high intensity training improve fitness in inactive men
2013-05-30
It is a commonly held perception that getting in shape and staying there requires hard work and hours upon hours of training. New research shows the opposite – it seems that only four minutes of vigorous activity three times per week is enough to be fit and healthy.
Regular training improves maximal oxygen uptake (VO2max), which is a well-established measure of physical fitness. However, just how much exercise, and how intense that exercise should be to deliver the biggest benefit remains to be defined. Now, researchers from the KG Jebsen – Centre of Exercise in Medicine ...
Travelers play valuable role assisting crew in common medical emergencies on flights
2013-05-30
PITTSBURGH, May 30, 2013– Medical emergencies during commercial airline travel can be a frightening experience, but most situations are well-treated by other passengers and flight attendants, in collaboration with consulting physicians on the ground. A University of Pittsburgh study published today in the New England Journal of Medicine found that doctors, nurses and other medical professionals on the aircraft helped to treat sick fellow passengers in three-fourths of the emergencies studied.
Led by Christian Martin-Gill, M.D., M.P.H., assistant professor of emergency ...