Radio signals coming from the nightside of exoplanets could reveal planetary details

So far, in the search for exoplanets, scientists have been unable to detect radio signals coming from those planets. However, they believe that radio signals from distant solar systems could give astronomers valuable information about the characteristics of the planet they emanate from. A research paper published by Rice University scientists has outlined a better way to determine which exoplanets are most likely to produce detectable radio signals based on activity within the magnetosphere on the nightside of the planet.The study shows that radio signals emanating from the dayside of an exoplanet appear to be at their max during phases of high solar activity. The study also found that those coming from the planet's nightside could add significantly to the signal. Information on the planet's magnetosphere is of particular interest to scientists because the strength of the magnetosphere around an exoplanet indicates how well it will be protected from the solar wind coming from its host star.

Earth's magnetosphere is one of the key reasons the planet is teeming with life because it protects us from radiation and solar wind. Magnetic field strength data could shed light on planetary interiors and allow researchers to understand how planets form. Here on earth, an analytical tool known as Bode's Law helps establish a linear relationship between the solar wind and radio emissions from the planets in its path. Researchers have tried to apply the law to exoplanet systems with little success.

Researchers on the new study say that current analytical models rely primarily on emissions expected to emerge from the polar region of an exoplanet, which can be seen on Earth as an aurora. The new study appends a numerical model to those used for estimating polar region emissions to provide a complete picture of emissions around an entire exoplanet. Nighttime emissions don't necessarily come from a single large spot, like auroras around the North Pole, but from various parts of the magnetosphere. During strong solar activity, the nightside spots could raise the total emissions by at least an order of magnitude.