.. _starspots: ****************** starspots ****************** .. tags:: star, magnetic-field, starspots, surface-boundary-condition, low-mass This test suite case evolves a 0.9 |Msun|, solar metallicity (Z=0.02) model to an age of 24.63 Gyr using MESA's implementation of the YREC (Yale Rotating Evolution Code) SPOTS formalism introduced by `Somers et al. (2020; ApJ) `__ Compare to Figure 15 in Section 7 of MESA Instrument Paper VI. The impedance of the surface flux due to magnetic pressure from starspots is parameterized in the style of an atmospheric boundary modification. As first described by `Somers et al. (2015; ApJ) `__, the degree of "spottiness" on the stellar surface is characterized using two parameters: * SPOTF (hereafter ``fspot``): a coverage fraction, or "spot filling factor" (in the notation of the YREC documentation); and * SPOTX (hereafter ``xspot``): the temperature contrast between the spotted and unspotted regions: xspot = T_spot/T_photosphere. The coverage fraction is set to ``fspot = 0.34`` (for consistency with observations of low-mass stars: `Cao et al., 2022 `__) and the temperature contrast is set to ``xspot = 0.85`` (also from fits to observations). Detailed discussion of this functionality can be found in `MESA Instrument Paper VI: Starspots `__. A plot of the HR diagram for the problem is included below: .. image:: ../../../star/test_suite/starspots/docs/hr_starspots_001496.svg :width: 100% Last-Updated: 09Aug2024 by Meridith Joyce Last-Run: 12Apr2026 (MESA c79eae5c5) by vincentva on procyon in 1028 seconds using 8 threads.