Star Blasts Strip Alien Worlds Bare

New X-ray data sheds light on exoplanet atmospheres.

New research shows that distant alien planets are losing their atmospheres due to harsh stellar radiation. Scientists looked at how fierce X-rays from distant stars affect planets orbiting them. They wanted to understand how much an exoplanet’s (a planet outside our solar system) atmosphere might be blasted away. This radiation, like a cosmic hairdryer, can cause an exoplanet to shrink over eons.

Research Methodology

The team used data from the eROSITA telescope, along with older observations from other X-ray missions. They focused on 287 known exoplanets. The eROSITA telescope, orbiting Earth, is designed to spot high-energy X-rays, providing a fresh look at these distant star systems.

Key Findings

Their findings revealed widespread atmospheric stripping. The study found:

96 exoplanets were measured by eROSITA for the first time.
This included 14 transiting exoplanets (planets that pass in front of their star from our view) showing significant radiation exposure.
Fifty exoplanets in the sample endure more radiation than even a well-studied evaporating planet named GJ 436 b.

"We have presented a catalogue of X-ray luminosities of exoplanet host stars, high-energy irradiation levels of exoplanets and their estimated atmospheric mass loss rates," the authors stated.

This means some exoplanets are getting hammered by their star's energy, which can dramatically change their size and composition over billions of years.

Future Research and Implications

The exact rate of a planet’s atmospheric loss is still uncertain, as are factors like how high X-rays are absorbed in the atmosphere. The eROSITA telescope also has limits to its depth and can be dazzled by very bright sources. Future research will explore these details using improved models.

The authors noted: "Particularly interesting targets for follow-up observations of ongoing mass loss have been found, among them two multi-planet systems which can lead to unique insights on the evolution of exoplanetary atmospheres over time."

This work opens doors to finding planets actively losing their air. This research helps scientists grasp how planets change and evolve over cosmic time.

Source:

Foster, G., Poppenhaeger, K., Ilic, N., & Schwope, A. (2021). Exoplanet X-ray irradiation and evaporation rates with eROSITA. Astronomy & Astrophysics. doi: 10.1051/0004-6361/202140511