A broadband theory of Langmuir-whistler events in the solar wind

Recent interplanetary observations presented evidence of simultaneous excit ation of high-frequency Langmuir waves and low-frequency electromagnetic wh istler waves in the magnetic holes of the solar wind. In this letter, we fo rmulate a broadband theory of the interplanetary Langmuir-whistler events. We show that whistler waves can grow exponentially as a result of nonlinear interactions of Langmuir waves and left-hand circularly polarized radio wa ves. In particular, the growth of whistler waves favors propagation paralle l to the Langmuir waves.