2014/11/20 by K. G. Kislyakova, Mats Holmström, M. Holmström +4 · 3 citations
Physics and Astronomy · #Astrophysics and Star Formation Studies #Solar and Space Plasma Dynamics #Stellar, planetary, and galactic studies #astro-ph.EP #physics.space-ph
paper · pdf · doi:10.1126/science.1257829
published as Science, vol. 346, p. 981, 2014 · This is the author's version of the work. It is posted here by permission of the AAAS for non-commercial research use only. The definitive version was published in Science, vol. 346, p. 981, 21 November 2014, DOI: 10.1126/science.1257829. 3 pages, 3 figures
openalex publication_date 2014/11/20 · arxiv created 2014/11/25 · arxiv updated 2014/11/26 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Transit observations of HD 209458b in the stellar Lyman-α(Lyα) line revealed strong absorption in both blue and red wings of the line interpreted as hydrogen atoms escaping from the planet's exosphere at high velocities. The following sources for the absorption were suggested: acceleration by the stellar radiation pressure, natural spectral line broadening, or charge exchange with the stellar wind. We reproduced the observation by means of modeling that includes all aforementioned processes. Our results support a stellar wind with a velocity of ≈400 kilometers per second at the time of the observation and a planetary magnetic moment of ≈1.6 × 10(26) amperes per square meter.