How to Channel Photospheric Oscillations into the Corona

There are now many observations of waves in the solar corona with periods around 5 minutes. The source of these waves is uncertain, although global p-modes in the photosphere are an obvious candidate, given the similarity of the dominant periods. However, p-modes are traditionally considered evanescent in the upper photosphere, and it has been unclear how they could propagate through the chromosphere into the corona. Using a numerical model, we show that photospheric oscillations with periods around 5 minutes can actually propagate into the corona so long as they are guided along an inclined magnetic flux tube. The nonverticality of the flux tube increases the acoustic cutoff period to values closer to the dominant periods of the photospheric oscillations, thus allowing tunneling or even direct propagation into the outer atmosphere. The photospheric oscillations develop into shocks, which drive chromospheric spicules and reach the corona. We suggest that Transition Region and Coronal Explorer (TRACE) observations of propagating magnetoacoustic waves in the corona represent these shocked and tunneled photospheric oscillations. We also explore how seismology of these waves could be exploited to determine the connectivity between photosphere and corona.