Science.-New model to detect magnetospheres in distant solar systems

MADRID, 23 (EUROPA PRESS)

We cannot detect them yet, but radio signals from distant solar systems could provide valuable information about the characteristics of their planets.

A paper by scientists at Rice University describes a way to better determine which exoplanets are most likely to produce detectable signals based on the activity of the magnetosphere on the previously discounted night sides of the exoplanets.

Rice alumnus Anthony Sciola’s study, advised by co-author and space plasma physicist Frank Toffoletto, shows that while radio emissions from the daytime sides of exoplanets appear to peak during high solar activity, it is likely that those emerging from the night side add significantly to the signal.

This is of interest to the exoplanet community because the strength of a given planet’s magnetosphere indicates how well it would be shielded from the solar wind radiating from its star, in the same way that Earth’s magnetic field protects us.

Planets orbiting within a star’s Goldilocks zone, where conditions could give rise to life, could be considered uninhabitable without evidence of a strong enough magnetosphere. Magnetic field strength data would also help model planetary interiors and understand how planets form, Sciola said in a statement.

The study appears in The Astrophysical Journal.

Sciola says that the current analytical model is based primarily on emissions that are expected to emerge from the polar region of an exoplanet, what we see on Earth as an aurora. The new study adds a numerical model to those estimating emissions from the polar region to provide a more complete picture of emissions around an entire exoplanet.

“We are adding features that only appear in lower regions during really high solar activity,” he said.

It turns out, he said, that the emissions on the nightside do not necessarily come from one large place, such as the auroras around the north pole, but from various parts of the magnetosphere. In the presence of strong solar activity, the sum of these night spots could increase the planet’s total emissions by at least an order of magnitude.

“They are very small in scale and occur sporadically, but when you add them all together, they can have a big effect,” said Sciola, who continues the work at the Johns Hopkins University Applied Physics Laboratory. “A numerical model is needed to solve those events. For this study, Sciola used the multiscale atmospheric geospatial environment (MAGE) developed by the Center for Geospatial Storms (CGS) based at the Applied Physics Laboratory in collaboration with the physics group. of Rice’s space plasma.

“Basically, we are confirming the analytical model for more extreme exoplanet simulations, but adding additional details,” he said. “The bottom line is that we are paying more attention to the limiting factors of the current model, but we say that, in certain situations, you can get more emissions than that limiting factor suggests.”

He noted that the new model works best in exoplanetary systems. “You have to be very far away to see the effect,” he said. It is difficult to know what is happening on a global scale on Earth; it’s like trying to watch a movie by sitting next to the screen. You only get a little patch. “

Also, radio signals from an Earth-like exoplanet may never be detectable from Earth’s surface, Sciola said. “The Earth’s ionosphere blocks them,” he said. “That means we can’t even see Earth’s own radio emission from the ground, even though it’s so close.”

Detecting signals from exoplanets will require a satellite complex or a facility on the opposite side of the moon. “That would be a nice, quiet place to make a matrix that will not be limited by the ionosphere and Earth’s atmosphere,” Sciola said.