Stellar Activity Distorts Exoplanet Data: Hubble Study Reveals Contamination Impacting Size, Temperature, and Atmospheric Readings

New research indicates that stellar activity significantly distorts the data collected on exoplanets. A study published in *The Astrophysical Journal Supplement Series* reveals that "patchy" stars, characterized by unevenly heated surfaces, can contaminate light signals, leading to inaccurate assessments of exoplanet size, temperature, and atmospheric properties. The lead author of the study is Arianna Saba from the Department of Physics and Astronomy at University College London. Researchers analyzed archival data from 20 exoplanet atmospheres observed by the Hubble Space Telescope. The study found that stellar activity contaminated approximately half of the exoplanet atmospheres in the sample to varying degrees. Six exoplanets showed pronounced contamination, while another six exhibited lesser contamination. The study highlights the importance of considering stellar variability in exoplanet transit studies, particularly when using data sets that do not cover the optical or UV spectral range. Observations in optical and UV wavelengths are more likely to reveal stellar contamination, while infrared observations may overlook it. Accounting for stellar activity can significantly alter planetary atmospheric parameters, such as molecular abundances and temperature. The researchers suggest that previous exoplanet atmosphere studies lacking broad optical or UV coverage should be revisited. Future studies should also employ multi-wavelength observations and develop better models to mitigate the impact of stellar activity. NASA's Institute of Advanced Concepts (NIAC) is funding the Legged Exploration Across the Plume (LEAP) program to explore the plumes of Enceladus using a jumping robot. Based on the Salto robot developed at UC Berkeley, LEAP could jump up to 100 meters horizontally on Enceladus. This method offers advantages over rovers due to the icy, uneven terrain and over powered flight due to the lack of atmosphere. The robot would jump through the plumes, collecting data closer to the source than other methods. Challenges include the need for additional reaction wheels for three-dimensional control and the limited payload capacity due to size constraints. The project is in its early stages, with the current phase focused on a case study to determine design parameters for future prototypes.