Merge branch 'main' into reorg-ci-project

Author: icweaver

docs/case_studies/stars_and_galaxies/ptiede-polarization.md

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+---
+title: "Horizon-scale variability of M87* from 2017–2021 EHT observations"
+id: "ptiede-polarization"
+description: "See how this team uses Julia to detect an unexpected polarization flip in M87*."
+author: "[Paul Tiede](https://github.com/ptiede); [Kazu Akiyama](https://github.com/kazuakiyama); [Andy Nilipour](https://github.com/anilipour); [Rohan Dahale](https://github.com/rohandahale)"
+date: 2025-09-04
+---
+
+A new result from the team behind [Comrade.jl](@ref) at the [Event Horizon Telescope (EHT) collaboration](https://eventhorizontelescope.org/) has discovered an unexpected flip in the measured polarization of the magnetic fields around the supermassive black hole, M87*. Using Julia, this team was able to detect the magnetic spirals first spiraling one way in 2017, settling in 2018, and then reversing direction in 2021, indicating a dynamic environment with changing  polarization patterns.
+
+**Package: [ptiede/Comrade.jl](https://github.com/ptiede/Comrade.jl)**
+
+![image](https://eventhorizontelescope.org/sites/g/files/omnuum3116/files/2025-09/triptych_EHT_labeled.jpg)
+
+See the [EHT press release here](https://eventhorizontelescope.org/new-eht-images-reveal-unexpected-polarization-flips-at-m87), or read more in their paper published in [_Astronomy & Astrophysics_](https://www.aanda.org/articles/aa/pdf/forth/aa55855-25.pdf).
+
+> 1. The Event Horizon Telescope Collaboration, Akiyama, K., Albentosa-Ruíz, E., Alberdi, A., Alef, W., Carlos Algaba, J., … Matthew Young, R. (2025). [Horizon-scale variability of M87* from 2017--2021 EHT observations](https://www.aanda.org/articles/aa/pdf/forth/aa55855-25.pdf). Astronomy and Astrophysics. [doi:10.1051/0004-6361/202555855](https://www.aanda.org/component/article?access=doi&doi=10.1051/0004-6361/202555855)