Variation in the pre-transit Balmer line signal around the hot Jupiter HD 189733 b

摘要: As followup to our recent detection of a pre-transit signal around HD 189733 b, we obtained full phase coverage single planetary transit. The is again detected in the Balmer lines but with variable strength and timing, suggesting that bow shock geometry reported previous work does not describe from latest We also demonstrate use Ca II H K residual core flux as proxy for stellar activity level throughout A moderate trend found between absorption 2013 data flux. This suggests some hydrogen can be attributed varying levels. very weak correlation line 2015 transit, hinting at smaller contribution compared simulate how levels produce changes transmission spectra. These simulations show signals reproduced by variability. If signature circumplanetary material, its evolution time described accretion clumps spiraling towards star, although this interpretation has serious limitations. Further high-cadence monitoring H-alpha necessary distinguish true transiting material short-term variations level.