Stellar Flares Of The Hot Jupiter Host Star Hd 189733 A: Testing For A Possible Planetary Influence
Stellar flares are energetic eruptions that occur due to spontaneous rearrangements of stellar magnetic field lines. The question of whether close-in planets can influence or trigger stellar flares has been investigated for several years. Here we study the binary star system HD 189733 which consists of a K dwarf and an M dwarf. There is a Hot Jupiter orbiting the K dwarf with an orbital period of approximately 2.2 days. In 2009 and 2011, X-ray observations were used to discover stellar flares
... er stellar flares on the K dwarf HD 189733 A occurring at the same point in the orbital period of this Hot Jupiter in both years (Pilletteri et al., 2011). We sought to take more data on this system and discover whether or not there was a firm correlation between the orbit of this planet and the stellar flares on HD 189733 A. We did this by using echelle spectra and observing the change in depth of the H-alpha lines over time, which would indicate whether or not stellar flares were occurring. By studying the change in the depth of the H-alpha line versus the phase of the orbital period of the planet, we created an H-alpha curve that shows the are activity on HD 189733 A for the nights when our data was taken. Our analysis shows a complete lack of flares of the magnitude Pilletteri et al. (2011) observed, not only in the predicted portion of the orbital period, but also in the entire data set. This suggests that such flares are an extraordinary occurrence for this star and likely do not occur regularly during every orbital period of the Hot Jupiter.