It is well known that the search for exoplanets with conditions favorable to habitability is, nowadays, an active field of research. The interest is clearly represented by a double aspect: discovering more and more how and in which way other planetary systems similar to ours behave and how actually our home, the Earth, is an exceptional case. The main focus in recent years has focused on the dynamic relationship between the main star of a given planetary system and its orbiting planets in the so-called habitability belt (where exoplanets are located). This is because, as in the case of the solar system, the interaction mechanisms between the Earth and the Sun ensure that our life (for the moment) continues undisturbed. Going into a little more detail, for example, the extent of the Earth's magnetosphere is controlled by the level of solar activity through the properties of the solar wind. Therefore, understanding this relationship in the solar system is important for predicting the condition of exoplanetary magnetospheres near Sun-like stars.
The magnetosphere protects the planet from the violent interaction that would arise between the particles that make up the stellar wind and the atmosphere of the planet itself. For example, the barrier produced by the Earth's magnetic field protects the habitability of our planet by preventing the solar wind from blowing away the Earth's atmosphere. Therefore, the estimate of the extension of the "magnetic barrier" is a fundamental point for defining the parameters of habitability. With the instruments currently available it is not possible to directly measure the dynamic pressure of the wind in stars other than the Sun. There is therefore no direct measurement capable of estimating the compression of the magnetosphere of exoplanets, but it is possible to measure the ultraviolet emission of stelle.
The Solar and Space Physics Group of the Physics Department of the University of Rome "Tor Vergata" is clearly very active on the issues mentioned above (and not only). In fact, a scientific article was recently published in the Monthly Notices of the Royal Astronomical Society whose authors include Prof. Francesco Berrilli, Prof. Dario Del Moro, Dr. Luca Giovannelli, Dr. Valentina Penza and Dr. Raffaele Reda (PhD student in Astronomy Astrophysics and Space Science). The analysis conducted in the article uses the Sun-Earth interaction as a Rosetta stone for the study of other planetary systems. To study the relationship between the ultraviolet emission of the Sun and the properties of the solar wind measured near the Earth, data from the last five solar cycles (covering more than 50 years) were used.
The study on the topics covered in the article are the result of a collaboration between the Solar and Space Physics Group of the Physics Department of the University of Rome Tor Vergata, INAF IAPS and the National Solar Observatory (USA).
