As scientists relentlessly pursue the discovery of extraterrestrial life beyond our solar system, traditional search efforts have focused on relatively younger stars. However, recent studies have taken a greater interest in older stars, as the chances of finding evidence of life within these systems appear to be significantly higher.
The first discovery of an exoplanet within the system of 51 Pegasi occurred in 1995 by Swiss astronomers Didier Queloz and Michel Mayor. Since then, more than 5,500 other planets have been discovered.
The secret behind the shift in scientists’ research from younger to older stars lies in the magnetic condition of the star, believed to play a crucial role in supporting various forms of complex life on its planets.
Stars rotate at high speeds in their infancy, creating strong magnetic fields that unleash harmful radiation and charged particles onto their planetary systems.
Over billions of years, older stars experience a gradual slowdown in rotation due to what is known as magnetic braking—a theory that explains the loss of a star’s angular momentum due to its magnetic field. Naturally, a slow-down in the star’s rotation coincides with a weakening of its magnetic field.
In a research paper titled “The weak magnetic braking of the 51 Pegasi star,” lead researcher Travis Metcalfe indicates that the study presents new insights into how the rotation speed and magnetic force of older stars that exceed their mid-life point change. The paper also suggests that with time, magnetic braking in older stars leads to the retention of stellar winds and a reduction in their harm to nearby planets, thus enhancing the opportunities for life to thrive.
In recent years, astronomers have used the “TESS” satellite to measure and study the magnetic fields of certain stars directly, including the 51 Pegasi star. The research has revealed a marked change in the behavior of magnetic braking occurring in stars younger than the sun. At a certain stage in their evolution, these stars suffer a tenfold decrease in the efficacy of their magnetic braking. This decline appears to persist as the stars age until a point before the magnetic brakes regain strength again.
The implications of the search for life beyond Earth tend to indicate that younger stars affect their planets with harmful radiations and charged particles, while older stars may provide a more stable environment.
Therefore, these conclusions suggest that stars in mid-life or older may be the best targets in the search for life outside our solar system in the future.
