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  Solar-cycle irradiance variations over the last four billion years

Shapiro, A. V., Shapiro, A., Gizon, L., Krivova, N. A., & Solanki, S. K. (2020). Solar-cycle irradiance variations over the last four billion years. Astronomy and Astrophysics, 636: A83. doi:10.1051/0004-6361/201937128.

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Shapiro, Anna V.1, Author
Shapiro, Alexander2, 3, Author           
Gizon, Laurent1, Author           
Krivova, Natalie A.2, Author           
Solanki, Sami K.2, Author           
1Department Solar and Stellar Interiors, Max Planck Institute for Solar System Research, Max Planck Society, ou_1832287              
2Department Sun and Heliosphere, Max Planck Institute for Solar System Research, Max Planck Society, ou_1832289              
3ERC Starting Grant: Connecting Solar and Stellar Variabilities (SOLVe), Max Planck Institute for Solar System Research, Max Planck Society, ou_3164811              


Free keywords: Sun: activity / Sun: evolution / solar-terrestrial relations / stars: variables: general
 Abstract: Context. The variability of the spectral solar irradiance (SSI) over the course of the 11-year solar cycle is one of the manifestations of solar magnetic activity. There is strong evidence that the SSI variability has an effect on the Earth’s atmosphere. The faster rotation of the Sun in the past lead to a more vigorous action of solar dynamo and thus potentially to larger amplitude of the SSI variability on the timescale of the solar activity cycle. This could lead to a stronger response of the Earth’s atmosphere as well as other solar system planets’ atmospheres to the solar activity cycle.

Aims. We calculate the amplitude of the SSI and total solar irradiance (TSI) variability over the course of the solar activity cycle as a function of solar age.

Methods. We employed the relationship between the stellar magnetic activity and the age based on observations of solar twins. Using this relation, we reconstructed solar magnetic activity and the corresponding solar disk area coverages by magnetic features (i.e., spots and faculae) over the last four billion years. These disk coverages were then used to calculate the amplitude of the solar-cycle SSI variability as a function of wavelength and solar age.

Results. Our calculations show that the young Sun was significantly more variable than the present Sun. The amplitude of the solar-cycle TSI variability of the 600 Myr old Sun was about ten times larger than that of the present Sun. Furthermore, the variability of the young Sun was spot-dominated (the Sun being brighter at the activity minimum than in the maximum), that is, the Sun was overall brighter at activity minima than at maxima. The amplitude of the TSI variability decreased with solar age until it reached a minimum value at 2.8 Gyr. After this point, the TSI variability is faculae-dominated (the Sun is brighter at the activity maximum) and its amplitude increases with age.


Language(s): eng - English
 Dates: 2020
 Publication Status: Published online
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1051/0004-6361/201937128
 Degree: -



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Title: Astronomy and Astrophysics
Source Genre: Journal
Publ. Info: Les Ulis Cedex A France : EDP Sciences
Pages: - Volume / Issue: 636 Sequence Number: A83 Start / End Page: - Identifier: -