So What Is the Weather Like on Aquila X-1?

During a Type-I burst, the turbulent deflagation front may excite waves in the neutron star atmosphere with frequencies of about one cycle per second. On the Earth the analogs to these waves are the Rossby waves which distort the path of the jet stream. On a neutron star, these waves are observed as highly coherent flux oscillations during a Type-I burst. The frequencies of these waves change as the upper layers of the neutron star cool which accounts for the small variation in the observed QPO frequencies. In principle several modes could be excited but the fundamental buoyant r-mode exhibits significantly larger variability for a given excitation than all of the other modes.