2019ApJ...872...79R

Several "hot Jupiter" host stars appear to exhibit enhanced chromospheric activity, coronal flaring, and starspot development synchronized to their planetary orbits. These effects have been attributed to tidal and/or magnetic interactions between the star and exoplanet. The best studied among such systems is HD 189733, which has previously been observed from radio to X-ray wavelengths. Here I present ∼4.75 GHz Arecibo radio telescope observations of HD 189733 during a fraction of the exoplanet orbital phase range previously associated with enhanced coronal X-ray flaring. No radio flares from the lower corona were detected. I also leverage Microvariability and Oscillations of Stars, Automated Photoelectric Telescope, and Wise photometry to measure the occurrences of minima associated with enhanced starspot activity. The phasing of these minima with the exoplanet orbit does not reveal any synchronized active region behavior. Moreover, for the first time, I combine X-ray, ultraviolet, photometric, Ca II H and K, Hα, and radio observations of HD 189733 to conduct an extensive, holistic reexamination of stellar activity in this system. Through the presentation of new data, and by merging physical and statistical analytic approaches, I demonstrate that the previously asserted enhancements in activity, allegedly synchronized to certain exoplanet orbital phases, are likely the result of inadequately sampled intrinsic stellar activity from an active star, rather than star-planet interactions.