"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.
Pulses of electrons manipulate nanomagnets and store information
21.07.2017 | American Institute of Physics
Vortex photons from electrons in circular motion
21.07.2017 | National Institutes of Natural Sciences
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.
To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...
The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....
A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...
Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision
Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...
21.07.2017 | Event News
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21.07.2017 | Physics and Astronomy