Astronomers have discovered an exoplanet, WASP-69 b, with a unique feature – a gas tail that is shaped by the stellar wind coming from its host star. The discovery was made using the Keck/NIRSPEC telescope and published in January 2024.
WASP-69 b is a hot Jupiter exoplanet orbiting close to its host star. When radiation from the star heats up the planet’s outer atmosphere, it leads to photoevaporation, causing lightweight gases like hydrogen and helium to escape into space. However, the stellar wind from the star shapes this escaping gas into an exoplanetary tail.
The team observed that the gas tail extended more than 7.5 times the radius of the planet, measuring over 350,000 miles. The study suggests that changes in the stellar wind could affect the size and shape of the tail over time. This discovery provides valuable insights into the relationship between a star’s activity and its planetary atmosphere.
The study’s lead author, Dakotah Tyler, notes that if the stellar wind were to decrease, the planet would still be losing gas but not shaped into a tail. The team’s observations demonstrate how the stellar wind influences the formation of exoplanetary tails and offers potential applications for understanding stellar behavior in other star systems.
The discovery sheds light on the mysterious nature of exoplanet tails, which are subject to change due to various factors. Further research on this phenomenon could help scientists better understand how these tails form and evolve over time, providing valuable information about the relationship between a star’s activity and its planetary atmosphere.
Source: https://science.nasa.gov/universe/exoplanets/discovery-alert-a-planet-with-a-tail