Scientists have recently discovered a rare type of star dust whose structure specifies that it formed during a rare form of nucleosynthesis, a process through which new atomic nuclei are developed, and could shed new light on water's history on Earth.

A team led by cosmochemists from Caltech and Victoria University of Wellington in New Zealand, a Caltech report said, examined ancient materials aggregates within the Allende meteorite which, in 1969, fell to this planet, and discovered that a lot of them had extraordinarily high amount of strontium-84, comparatively rare light isotope of the element strontium that is so-named for the "84 neutrons in its nucleus".

Francois LH Tissot, a geochemistry assistant professor at Caltech said strontium-84 is part of an isotope family produced by a nucleosynthetic process, called the p-process, which stays a mystery.

Their findings, he added, points to the survival of trains potentially containing pure strontium-84. This, he continued, is exciting, as such grains' physical identification would offer an extraordinary chance of learning more about the p-process.

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Science Times - Rare Type of Stellar Grain Found in Ancient Materials: Scientists Explain More About Water’s Origin on Earth
(Photo : Wikimedia Commons)
Pure strontium in protective argon gas atmosphere.

Strontium Found To Be Helpful

Tissot and collaborator Bruce LA Charlier of Victoria Univerisity of Wellington are co-lead authors on research, "Survival of presolar p-nuclide carriers in the nebula revealed by stepwise leaching of Allende refractory inclusions", published in Science Advances.

This is quite interesting, explained Charlier adding, they want to know what this material's nature is and how it is fitting into a mix of ingredients that went to form the planet's recipe.

Strontium, a chemically reactive metal, WebMD explained, comprises four stable isotopes: strontium-84, including its heavier cousins with 86, 87, or 88 neurons in their nuclei.

Scientists have discovered that strontium is helpful when trying to date objects from the early solar system as strontium-87, one of its heavy isotopes, is generated by the radioactive isotope rubidium-87's decay.


 The rubidium-87 has a very long half-life, 49 billion years, which is more than thrice the age of the universe. 

Half-life is representing the amount of time needed for the isotope's radioactivity to drop to one-half its original value, enabling the isotopes to serve as chronometers for dating samples on varying time scales.

The most popular radioactive isotope used for dating is carbon-14, the radioactive isotope of carbon; with its half-life of approximately 5,700 years, carbon-14 can be used to identify the ages of organic materials on timescales up to roughly 60,000 years.

On the contrary, Rubidium-87 can be used to date the universe's oldest objects, and, closer to home, the solar system's objects.

Rubidium-Strontium Pair

As indicated in the study, what is specifically interesting about using the rubidium-strontium pair for dating is that the former is a volatile element.

Meaning, it tends to evaporate to form a gas phase at even comparatively low temperatures. Strontium, on the other hand, is not volatile.

As such, rubidium exists at a higher proportion in an object in the solar system that is richer in other volatiles like water for one, as they formed at lower temperatures.

Counterintuitively, Earth has an RB/SR ratio, that is 10 times lower compared to that of water-rich meteorites, inferring that this planet either accreted from water-poor materials or it accreted from water-rich ones although lost most of its water over time, as well as its rubidium. Understanding which of these circumstances occurred is essential for deciphering the origin of water on Earth.

Theoretically, the Rb-Sr chronometer, as explained in the SOA/NASA Astrophysics Data System, needs to be able to tease apart with the said two scenarios as the amount of strontium-87 that the radioactive decay produced in a given amount of time will not be the same if this planet began with a lot of rubidium against less of the material.

Related information about rubidium is shown on Nanotechnology World Association's YouTube video below:

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