Letters of Intent received in 2019

LoI 2021-2112
Focus Meeting: Beyond the Goldilocks zone: the effect of stellar magnetic activty on exoplanet habitability

Date: 16 August 2021 to 27 August 2021
Location: Busan, Korea, Rep of
Contact: Heidi Korhonen (heidi.korhonen@nbi.ku.dk)
Coordinating division: Division E Sun and Heliosphere
Other divisions: Division F Planetary Systems and Astrobiology
Division G Stars and Stellar Physics
Co-Chairs of SOC: Heidi Korhonen (University of Copenhagen)
Sarah Gibson (HAO/NCAR)
Cristina Mandrini (IAFE, UBA-CONICET)
Chair of LOC: None (None)



We aim at a two day Focus Meeting during the 2021 General Assembly, with six sessions (three each day) that focus on different aspects:

1) Solar and stellar activity (observations, mechanism for creation, etc)
2) Solar System as a proxy (how does the Sun affect planets)
3) Planetary habitability (general considerations)
4) Flares (observations, modeling, impact on (exo)planets)
5) Coronal Mass Ejections (observations, modeling, impact on (exo)planets)
6) Winds (observations, modeling, impact on (exo)planets)



The activity of stars, such as the Sun, modulates the environment within their astrospheres. This variable forcing is mediated via stellar magnetic fields, radiative and energetic particulate flux, stellar winds and magnetic storms. In turn this influences planetary atmospheres, climate and habitability. Studies of this intimate relationship between the parent star, its astrosphere and planets that it hosts have reached a certain level of maturity within our own solar system – fueled both by advances in theoretical modeling and a host of satellites that observe the Sun-Earth system. This Focus Meeting takes advantage of these recent advances in studies of the Sun and the heliosphere to explore stellar activity and its impact on habitability of exoplanets.

Most studies on exoplanet habitability rely on finding conditions that allow having liquid water on the surface of the planet – an assumption that is mainly driven by the star-planet distance. Here, we will take the next step and add information on the magnetic activity. The magnetic activity of cool stars in the form of flares, winds and coronal mass ejections have a direct impact on planets. This activity varies with the mass, age and rotation rate of the star and can be damaging for life, even in the case of a fairly inactive star like the Sun. During periods of intense solar activity, the solar wind is enhanced and geomagnetic storms produce auroras, disrupt radio transmissions, affect power grids, damage orbiting satellites, and can be hazardous to astronauts. By analogy, the magnetic activity of young cool stars, which exhibit much higher activity levels than the Sun, may be hazardous for the creation and development of life. Therefore, knowledge of magnetic activity of the host star it is of crucial importance when determining the habitability of a planet. In close-in worlds, like in the habitable zone of an M dwarf, stellar magnetic activity could have a catastrophic impact on the actual habitability of the planet. Even the planets further away from the star are significantly affected, as is seen in the solar wind stripping of Mars’ atmosphere, and in the enhanced ion escape from the Martian atmosphere in connection to a CME events.

This Focus Meeting has a strong synergy with current and future missions and instruments (such as TESS, SPIRou, CARMENES, JWST, CHEOPS, Plato, and ARIEL), which are designed to characterize exoplanets and increase the number of terrestrial planets orbiting inside the ‘habitable zone’. In addition, one of the main science goals for extremely large telescopes is finding biomarkers in an exoplanet atmosphere. For the success of all these facilities it is crucial to understand the stellar magnetic activity and its effects on habitability.

Thanks to large collaborations we now have reconstructed surface magnetic fields of about one hundred cool stars, paving the way for studying activity along the main sequence. At the same time researchers studying our own Sun are benefiting from detailed space- and ground-based observations, elucidating the role of the solar activity and magnetism in the dynamics of Sun-Earth system. This timely Focus Meeting will foster interdisciplinary interactions between theorists, modelers, observers and data analysts whose research is directed towards understanding the origin of stellar magnetic, radiative and particulate variability, their impact on the electromagnetic and particulate environment of planets and the consequent forcing of planetary atmospheres.

The core of our SOC consists of exerts in solar and stellar magnetic activity and their effects on planets. For the full Focus Meeting proposal we will invite more people to our SOC, especially researchers with expertise in exoplanets and star-planet interaction. Possible people include for example: Katja Poppenhaeger (Germany, female), Ofer Cohen (USA, male), Cecilia Garraffo (USA, female), Stephen Marsden (Australia, male), Dibyendu Nandi (India, male), and Adriana Valio (Brazil, female).

The Presidents of Div. E, F, and G support the LoI for this GA Focus Meeting. The support from the different SCs should come after the analysis of the final proposal.