The celestial world is an ever-evolving mystery that often sparks curiosity and prompts scientific exploration. One such intriguing marvel is the bright red star Betelgeuse, otherwise known as ‘Thiruvathirai’ or ‘Ardra’ in Indian astronomy. This fiery giant sits prominently in the constellation Orion, and recent studies have explained its unique pulsation patterns.
An Overview of Betelgeuse
Betelgeuse is a red supergiant star approaching the end of its lifespan. Ranking as the second-brightest star in the Orion constellation, next only to Rigel, this star has always intrigued scientists worldwide. In late 2019, after a disturbing outburst caused by the star shedding a large part of its visible surface, researchers noticed a strange dimming phenomenon about Betelgeuse which led to further investigation.
The brightness of Betelgeuse is variable due to two key factors: changes in its surface temperature and alterations in its size. As a red supergiant, it has an extremely unstable outer layer, making it prone to convection and pulsation.
The Pulsation Mechanism of Betelgeuse
The pulsation of Betelgeuse refers to a repeating cycle of contraction and expansion of the star. This phenomenon is not random but indicative of the star’s present state in its lifecycle. Extensive research suggests that Betelgeuse is presently in its late carbon-burning stage.
The pulsation periods offer a wealth of knowledge about the star’s radius, luminosity, and mass, affirming its core carbon-burning phase. Just as a lid lifts from a boiling pot releasing steam, red giant stars like Betelgeuse also expand and contract due to the heating and cooling of hydrogen in their outer layers.
When the star’s outer envelope, filled with cooler neutral hydrogen, absorbs heat from the interior, the star expands. Heating increases the temperature, causing the hydrogen to become ionized and absorb more heat, resulting in a powerful expansion and ejection of the outer shell. This cyclical process leads to the observed periodic dimming and brightening of Betelgeuse.
Stages of Evolution of Stars like Betelgeuse
Stars like Betelgeuse undergo a series of elemental fusions during their lifecycle. Initially, they fuse hydrogen into helium, a process that balances gravity and energy release. However, massive stars like Betelgeuse deplete their hydrogen fuel within few crore years and transition to using helium for creating carbon.
As each stage progresses, the burning rate increases, with carbon burning within a few hundred years and silicon burning within a day. The star eventually consumes the elements of the periodic table, ending with a core filled with iron. When the core becomes iron-rich, the star’s internal temperature and pressure drop, allowing gravity to compress the core and transform it into a neutron star or a black hole. Betelgeuse is currently at the late-carbon stage, indicating the final phase before its imminent collapse.
Understanding the Constellation Orion
Constellations are groups of visible stars that form perceived patterns on the celestial sphere, usually representing animals, mythological figures, or inanimate objects. Officially, there are 88 recognized constellations mapped out by the International Astronomical Union (IAU), headquartered in Paris, France, established in 1919.
The Orion constellation, home to Betelgeuse, is a notable constellation visible worldwide. Located on the celestial equator, this constellation is best viewed in the Northern Hemisphere from January to April and from November to February in the Southern Hemisphere.
Betelgeuse’s unique features and pulsating patterns make it an intriguing subject in the world of astronomy. As scientists continue to unravel the mysteries of this supergiant star, our understanding of the cosmos continues to deepen.
