They found a deposit of cosmic lithium that is never destroyed, in an amount 13,000 times greater than what exists on Earth, in a brown dwarf.

Lithium, white gold, is scarce on Earth. Without lithium, there are no options for electric car batteries, treatments for bipolar disorder, and many other advancements that require lithium. We are going through a supply crisis on the planet. However, they have just found an intact lithium deposit in the heart of a brown dwarf.

Brown dwarfs, also known as brown dwarfs or failed stars, are the natural link between stars and planets; they are more massive than Jupiter, but not enough to burn hydrogen, which is the fuel used by stars to shine. This is why these substellar objects remained invisible until observers detected them in the mid-1990s. They are particularly interesting because it was predicted that some of these objects could preserve intact the lithium content, the so-called “white oil” because of its rarity and relevance for multiple applications.

A team of researchers from Astrophy InstituteCanary Islands (IAC) and dThe National Institute of AstrologyPhysics, Optics and Electronics (INAOE), discovered lithium in the coldest, oldest brown dwarf where so far the presence of this valuable element has been confirmed.

This substellar object, called Reid 1B, it preserves intact the oldest known deposit of lithium in our cosmic neighborhood, the origins of which date back to an age before the formation of the binary system to which it belongs. The discovery was made using the OSIRIS instrument, installed at the Gran Telescopio Canarias, at the Roque de lo Muchachos Observatory (Garafía, La Palma). The study was published about Royal Astronomical Society Monthly Notices (MNRAS).

Over the past twenty years, astronomers have detected and tracked the orbital motions of some binary stars composed of brown dwarfs in the so-called solar neighborhood. So they determined the dynamic masses of the two components using Kepler’s laws, mathematical formulas. affirmed in the 17th century by Johannes Kepler to describe the movement of astronomical bodies that are in mutual gravitational influence, such as the system formed by the Earth and the shello In some of these binary systems, the primary component has enough mass to burn lithium, while the secondary component may not. However, the theoretical models have not been tested so far.

Using the OSIRIS instrument, installed on the Great Canary Telescope (GTC or GRantecan), Currently the world’s largest optical and infrared telescope, located at the Roque de los Muchachos Observatory (ORM), a team of researchers from the Astrofi InstituteCanary Islands (IAC) and dThe National Institute of AstrologyBetween February and August of this year, Physics, Optics and Electronics (INAOE) carried out high-sensitivity spectroscopic observations of two binaries whose components are brown dwarfs.

They didn’t detect lithium in three of these failed stars, but in Reid 1B, the weakest and coldest of the four. This team of astrophysicists then presented a unique discovery, a cosmic lithium deposit that is never destroyed, the origins of which date back to a time before the formation of the system to which Reid 1B belongs. It is, in fact, the coldest and weakest extrasolar object where lithium has been found, in an amount 13,000 times that of Earth. With an age of 1.1 billion years and a dynamic mass 41 greater than that of Jupiter, the largest planet in the solar system, this object it’s 16,9 light years from us.

a hidden treasure chest

Lithium observations on brown dwarfs allow their masses to be estimated with some precision based on nuclear reactions. The resulting theoretical thermonuclear masses should be consistent with the dynamic masses determined, with less uncertainty, from the orbital analysis. However, the researchers found that lithium is preserved to a dynamic mass that is 10% less than predicted by more recent theoretical models. This discrepancy seems significant and suggests that something still eludes us in our theoretical understanding of brown dwarfs.

We’ve been tracking lithium in brown dwarfs for three decades – he explains. Eduardo Lorenzo Martín Guerrero de Escalante, research professor at the IAC’s Higher Council for Scientific Research (CSIC) and first author of the article – and we were finally able to determine with accuracy the mass boundary between its conservation and its destruction and compare with theoretical predictions”. And he adds: “There is billion of brown dwarfs in the Milky Way. The lithium that brown dwarfs harbor they constitute the largest known deposit of this valuable element in our cosmic neighborhood”.

Carlos del Burgo Diaz, co-author of the article and a researcher at INAOE, CONACYT’s public research center, points out that “although primordial lithium was created 13.8 billion years ago together with hydrogen and helium, as a result of nuclear reactions after the Big Bang , today it finds up to four times more lithium in the Universe”. According to the researcher, “although this small element can be destroyed, more is also created, for example, in explosive events like nova and supernova, then brown dwarfs like Reid 1B can pack and protect you, just like a hidden treasure chest. “

This work was financed with funds from the Spanish Ministry of Economy and Digital Transformation (MINECO) and the European Regional Development Fund (ERDF) through the PID2019-109522GB-C53 project.

The Gran Telescopio Canarias and the Observatories of the Instituto de Astrophysics de Canarias (IAC) are part of the Singular Scientific and Technical Infrastructures (ICTS) network in Spain.

Article: New restrictions on minimum mass for burning thermonuclear lithium in brown dwarfs”, Monthly Notices from the Royal Astronomical Society; Martín, Eduardo L.; Lodieu, Nicolas; del Burgo, Carlos; October 2021.

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