"These tiny relics, a millionth of a meter small, could point us to the first steps of dust formation in both old and young stars," stated Dr. Larry Nittler of the Carnegie Institutions Department of Terrestrial Magnetism. Nittler is co-author of a study published in the September 3, 2004, issue of Science,* about the origin of two presolar grains from the Tieschitz meteorite and the implications they have for resolving observational and theoretical challenges of dusty outflows surrounding asymptotic giant branch (AGB) stars--one of the last evolutionary stages of low-mass stars like the Sun.
Both theoreticians and observational astronomers have long grappled with the issue of whether aluminum oxide--which in its crystalline form is the second hardest natural material--is the first solid to condense as hot, gaseous winds from oxygen-rich AGB stars expand and cool. "Because AGB stars are the most significant source of dust in the Milky Way galaxy, determining how and in what form this dust condenses is important to understanding how the chemical elements get cycled between stars and interstellar space. Also, the first solids in cooling disks around new stars form by analogous processes to those occurring around AGB stars, so these grains give us a glimpse into the earliest stages of our own solar system formation," said Nittler.
Observational astronomers have obtained telltale infrared spectra from dusty AGB stars that have indicated the possible presence of two forms of aluminum oxide--the crystalline form and an amorphous, or non crystalline form. However, the data have not been precise enough to tell if both forms are really present. "This study is really the first definitive analysis that indicates that both forms are indeed produced in AGB stars," said Professor Tom Bernatowicz of Washington University in St. Louis.
UNH scientists help provide first-ever views of elusive energy explosion
16.11.2018 | University of New Hampshire
NASA keeps watch over space explosions
16.11.2018 | NASA/Goddard Space Flight Center
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure
Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...
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16.11.2018 | Life Sciences
16.11.2018 | Life Sciences