A Synergic Strategy to Characterize the Habitability Conditions of Exoplanets Hosted by Solar-Type Stars

Reda, Raffaele; Mauro, M. P. Di; Giovannelli, Luca; Piersanti, Mirko; Berrilli, F.; Corsaro, E.

doi:10.3389/fspas.2022.909268

Cited by 3 publications

(1 citation statement)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For these reasons, the most widely used chromospheric lines are the Ca II K and H lines (393 and 397 nm, respectively), which form in the near UV part of the spectrum and are accessible from the ground. These lines are well known proxies of the photospheric magnetic field (e.g., Babcock and Babcock, 1955;Leighton, 1959;Cincunegui and Mauas, 2004;Ermolli et al, 2010;10.3389/fspas.2023.1328364 Fontenla et al, 2011;Bertello et al, 2016;Pevtsov et al, 2016;Petrie et al, 2021;Tähtinen et al, 2022), and they are employed for a variety of studies which include dynamo processes (Skumanich, 1972;Saar and Brandenburg, 1999;Chowdhury et al, 2022;Velloso et al, 2023), the characterization of stellar magnetic fields from the photosphere to the outer layers of stellar atmospheres and winds (e.g., Testa et al, 2015;Reda et al, 2022;Reda et al, 2023), estimates of UV and EUV stellar radiative emission (Lovric et al, 2017;Criscuoli et al, 2018;Sreejith et al, 2020) and long-term monitoring of stellar cycles (e.g., Baliunas et al, 1995;Hall et al, 1995;Egeland et al, 2017;Radick et al, 2018;Buccino et al, 2020). Given that synoptic measurements of the magnetic fields started only in the 1950s, while Ca II UV measurements date back to the beginning of 1900s, the latter are fundamental diagnostics of the long term evolution of the solar magnetic field (e.g., Chatzistergos et al, 2022b), and a fundamental input for solar irradiance reconstructions particularly at times when these were not available (e.g., Berrilli et al, 2020;Chatzistergos et al, 2021;Penza et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Sun-as-a-star variability of Hα and Ca II 854.2 nm lines

Zills,

Criscuoli,

Bertello

et al. 2024

Front. Astron. Space Sci.

View full text Add to dashboard Cite

Studies of stellar magnetic fields mostly rely on proxies derived from chromospheric lines, typically forming in the UV and shorter wavelengths and therefore accessible only from space based observatories. Even Ca II K or H observations, forming in regions accessible from the ground, are not always available. As a result, there is a crucial need to explore alternative activity proxies to overcome the limitations posed by observational constraints. Using sun-as-a-star observations acquired with the ISS at SOLIS we investigated the correlation between the Ca II K emission index and indices derived from the Hα 656.3 nm and Ca II 854.2 nm lines, which are well known chromospheric diagnostics. We found that both the core intensities and widths of the two lines are positively correlated with the Ca II K emission index (ρ ≳ 0.8), indicating their suitability as reliable indicators of magnetic activity, the width of the Hα line showing the highest correlation (ρ = 0.9). We also found that such correlations vary with the activity cycle. Specifically, during the analyzed cycle 24, the correlations with the Ca II K index varied 14% for the Hα width, 33% for the Hα core intensity, and doubled for the two Ca II 854.2 nm line indices. These results suggest that, among the investigated indices, the Hα width best traces magnetic activity. Results are discussed at the light of current knowledge of the formation heights of the two lines, and of spatially resolved solar observations.

show abstract

Section: Introductionmentioning

confidence: 99%

Sun-as-a-star variability of Hα and Ca II 854.2 nm lines

Zills,

Criscuoli,

Bertello

et al. 2024

Front. Astron. Space Sci.

View full text Add to dashboard Cite

show abstract

Future opportunities in solar system plasma science through ESA’s exploration programme

Holmstrom,

Lester,

Sanchez-Cano

2024

npj Microgravity

View full text Add to dashboard Cite

The solar wind interacts with all solar system bodies, inducing different types of dynamics depending on their atmospheric and magnetic environments. We here outline some key open scientific questions related to this interaction, with a focus on the Moon and Mars, that may be addressed by future Mars and Moon missions by the European Space Agency’s Human and Robotic Exploration programme. We describe possible studies of plasma interactions with bodies with and without an atmosphere, using multi-point and remote measurements, and energetic particle observations, as well as recommend some actions to take.

show abstract

The exoplanetary magnetosphere extension in Sun-like stars based on the solar wind–solar UV relation

Reda

Giovannelli

Piersanti

et al. 2023

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

The Earth’s magnetosphere extension is controlled by the solar activity level via solar wind properties. Understanding such a relation in the Solar System is important for predicting also the condition of exoplanetary magnetospheres near Sun-like stars. We use measurements of a chromospheric proxy, the Ca ii K index, and solar wind OMNI parameters to connect the solar activity variations, on the decennial time scales, to the solar wind properties. The data span over the time interval 1965-2021, which almost entirely covers the last 5 solar cycles. Using both cross-correlation and mutual information analysis, a 3.2-year lag of the solar wind speed with respect to the Ca ii K index is found. Analogously, a 3.6-year lag is found once considering the dynamic pressure. A correlation between the solar wind dynamic pressure and the solar UV emission is found and used to derive the Earth’s magnetopause standoff distance. Moreover, the advantage of using a chromospheric proxy, such as the Ca ii K index, opens the possibility to extend the relation found for the Sun to Sun-like stars, by linking stellar variability to stellar wind properties. The model is applied to a sample of Sun-like stars as a case study, where we assume the presence of an Earth-like exoplanet at 1 AU. Finally, we compare our results with previous estimates of the magnetosphere extension for the same set of Sun-like stars.

show abstract

A Synergic Strategy to Characterize the Habitability Conditions of Exoplanets Hosted by Solar-Type Stars

Cited by 3 publications

References 54 publications

Sun-as-a-star variability of Hα and Ca II 854.2 nm lines

Sun-as-a-star variability of Hα and Ca II 854.2 nm lines

Future opportunities in solar system plasma science through ESA’s exploration programme

The exoplanetary magnetosphere extension in Sun-like stars based on the solar wind–solar UV relation

Contact Info

Product

Resources

About