The Large-Scale Solar Magnetic Field During the Transition to Solar Cycle 25

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Long-term measurement of the large-scale magnetic field of the Sun is essential for understanding the solar activity, both at the Sun and throughout the heliosphere, as well as for gaining insight into the activity cycles of other stars that may affect habitability of exoplanets. Furthermore, because of society's increasing reliance on technology that is susceptible to changing conditions in space, knowledge of the space climate and predictive understanding of the next Solar Cycle are crucial. The main purpose of this five-year project is to enable continued accurate measurements of the large-scale magnetic field of the Sun during the transition from Solar Cycle 24 to Solar Cycle 25 using the Wilcox Solar Observatory (WSO) instrument. Observing this transition in the solar activity is particularly important, because solar physicists were unable to predict many of the unusual characteristics of Solar Cycle 24: its delayed start, historically weak level of activity, diminished solar wind strength, increased cosmic-ray intensity, and strong north-south asymmetry. Consequently, extending WSO's consistent 43-year time-series of measurements into the next Solar Cycle is critical for understanding the long-term magnetic activity cycle of the Sun and other Sun-like stars. During this five-year project, the team at Stanford University will: (i) collect, process, and evaluate the WSO observations of the Sun's photosphere; (ii) extend the reliable, consistent, nearly four-solar-cycle-long time-series of useful data products; and, (iii) make the data even more conveniently available to the broad scientific community. Furthermore, the WSO will continue to contribute to STEM education in the U.S., work force development, and public outreach. Observations at the WSO are collected by a resident observer, who is a graduate student in solar physics at Stanford University. Numerous summer students contribute to the data analysis and software development at the Observatory. Improved Solar Cycle predictions are crucial for advancing the national Space Weather efforts, and improved understanding of the Solar Cycle is relevant to advancing knowledge on the activity cycles on other Sun-like stars, which can affect our assessment of exoplanet habitability. The research and EPO agenda of this project supports the Strategic Goals of the AGS Division in discovery, learning, diversity, and interdisciplinary research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.