2008/07/24 by Adriana Silva-Valio · 2 citations
Engineering · Physics and Astronomy · #Astronomy and Astrophysical Research #Space Technology and Applications #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/591846
13 pages, 5 figures
openalex publication_date 2008/07/24 · arxiv created 2008/08/15 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
A new method for determining the stellar rotation period is proposed here, based on the detection of starspots during transits of an extrasolar planet orbiting its host star. As the planet eclipses the star, it may pass in front of a starspot which will then make itself known through small flux variations in the transit light curve. If we are lucky enough to catch the same spot on two consecutive transits, it is possible to estimate the stellar rotational period. This method is successfully tested on transit simulations on the Sun yielding the correct value for the solar period. By detecting two starspots on more than one transit of HD 209458 observed by the Hubble Space Telescope , it was possible to estimate a period of either 9.9 or 11.4 days for the star, depending on which spot is responsible for the signature in the light curve a few transits later. Comparison with period estimates of HD 209458 reported in the literature indicates that 11.4 days is the most likely stellar rotation period.