In space, there are clouds containing gas and dust ejected from stars. Our Solar System 4.6 billion years ago, Molecular CloudsMost of these dust particles were destroyed during the formation of the solar system.
The dark areas in this image of the Carina Nebula are molecular clouds. NASA, ESA, N. Smith (University of California, Berkeley) et al., Hubble Heritage Team (STScI/AURA)
However, a very small number of grains survived and became primitive. meteoriteThey are Presolar grains Because they are older than our solar system. I am a scientist who studies the early solar system and beyond, focusing primarily on pre-solar grains.
These presolar grains existed in molecular clouds billions of years ago before reaching Earth in meteorites.
This photo shows a particle taken with a scanning electron microscope. Silicon Carbide(SiC). The scale bar is 1 micron, or 1 millionth of a meter (39.37 inches). The grains are Murchison meteorite A volcanic eruption that occurred in Australia in 1969.
Scientists have been studying the particles’ physical properties to pinpoint their origin. Carbon has two stable isotopes, ¹²C and ¹³C, which have slightly different weights. The ratio of these isotopes is barely altered by processes that occur in the solar system, such as evaporation and condensation. In contrast, Nucleosynthesis in stars The ¹²C/¹³C ratio varies from 1 to over 200,000.
If this particle originated within our solar system, its C/C ratio would be 89. The particle in this photo has a C/C ratio of about 55.1, proving its stellar origin. Combined with other information about the particle, this ratio tells us that the particle formed in a type of star called a neutron star. Asymptotic Giant Branch StarsThe star reached the end of its life over 4.6 billion years ago when it produced a huge amount of dust and ejected it into space.
A fragment of the Murchison meteorite from which particles have been extracted, at the National Museum of Natural History in Washington, DC. Art Brom/Flickr, CC BY-SA
Scientists have found other types of presolar particles in meteorites, including: diamond, graphite, Oxideand SilicatesPresolar grains like the one pictured here can help researchers understand nucleosynthesis in stars, the mixing of different regions within stars and stellar ejecta, and how the abundances of elements and their isotopes change over time in the Galaxy.
Sachiko Amari is a research professor of physics, literature, and science at Washington University in St. Louis. This article is reprinted from conversation Under Creative Commons License.Please read Original article.
