Article:
The Indian Institute of Astrophysics (IIA) recently made an important discovery in the realm of space research. Their team of researchers has identified hundreds of Lithium-rich giant stars, which suggests that lithium is being produced within these stars. This revelation could account for the abundance of lithium found in the interstellar medium – the space between stars. The study was published in the Astrophysical Journal Letters and Monthly Notices of Royal Astronomical Society (MNRAS).
Discovering Super Li-rich Giants
The IIA scientists discovered numerous super Li-rich giants containing a quantity of lithium equal to or exceeding 10 times the current value. This phenomenon was measured in a logarithmic scale relative to hydrogen, known as A(Li) = 3.2 dex. To achieve this feat, the researchers followed a two-pronged strategy. Firstly, they systematically searched for high lithium content among low mass evolved stars within the Galaxy. Secondly, they determined the exact evolutionary phase of these high lithium abundance stars.
The Methodology of Discovery
The discovery of hundreds of lithium-rich giants utilized data garnered from large-scale ground and space missions. Despite this breakthrough, lithium-rich giants only account for 1% of all the stars in the Galaxy. The evolutionary phase of these giants was established by analyzing the relative positioning of thousands of stars based on their temperature and luminosity.
Lithium Enhancement and Red Clump Giants
For the first time, it was demonstrated that the enhancement of lithium in these giants is associated exclusively with central helium-burning stars, also known as Red Clump Giants. This finding could play a vital role in validating or eliminating theories including planet engulfment or Big Bang Nucleosynthesis (BBN) during the red giant evolution stage when the center’s helium is not burning.
The Role of Lithium in the Universe
Lithium is one of three primary elements, alongside Hydrogen and Helium, created during the BBN. This model predicts a primordial lithium abundance. Stars are proposed as a probable lithium source in the Galaxy and deemed lithium sinks. The original lithium present in stars at birth is gradually depleted over their lifetime since lithium burns at low temperatures easily found in stars.
Understanding the Process of Planetary Engulfment
In the universe, planets accompany host stars, such as how the sun is the host star for our solar system’s planets. As the host star evolves into a white dwarf, nearby planets can be engulfed during the giant phase. These planetary engulfment events result in the chemical assimilation of a planet into a star’s outer layer, altering the chemical pattern of the stellar atmosphere to reflect the composition of the swallowed celestial body.
The Concept of Big Bang Nucleosynthesis
Big Bang Nucleosynthesis (BBN) is a leading theory about the universe’s origin. It postulates that the universe commenced from a small singularity and expanded significantly over the next 13.8 billion years to form the current cosmos. This theory gets corroborated by the Universe’s light-element abundance. According to BBN, light elements like deuterium, helium, and lithium were created shortly after the Big Bang, while heavier elements originated later within the interiors of newly formed stars.
