Göttingen 2025 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 15: Astrophysical Plasmas

P 15.5: Vortrag

Mittwoch, 2. April 2025, 17:15–17:30, ZHG102

Measuring the Free-Free Opacity of Hydrogen at Stellar Interior Conditions Using the National Ignition Facility — •Samuel Schumacher¹, Julian Lütgert¹, Ronald Redmer¹, Mandy Bethkenhagen⁸, Laurent Masse⁷, Dirk Gericke², Siegfried Glenzer⁵, Tilo Döppner⁶, Tina Ebert⁶, Gareth Hall⁶, Otto Landen⁶, Markus Schölmerich⁶, Charles Starrett³, Nathaniel Shaffer⁴, Laurent Divol⁶, Benjamin Bachmann⁶, Steve MacLaren⁶, Clement Trosseille⁶, Shahab Khan⁶, and Dominik Kraus¹ — ¹Universität Rostock — ²Warwick University — ³Los Alamos National Laboratory — ⁴University of Rochester — ⁵SLAC — ⁶Lawrence Livermore National Laboratory — ⁷CEA — ⁸Université Lyon

The opacity of stellar matter is critical for modeling stellar interiors, primarily composed of hydrogen and helium. It determines where convection becomes the dominant energy transport mechanism.

Stellar interior modeling is challenging due to dense plasma conditions, with temperatures of hundreds of eV and densities 800 times that of solid matter. These conditions pose significant computational challenges and remain largely unexplored experimentally.

To address this, we conducted the first hydrogen absorption experiments at stellar interior conditions at the National Ignition Facility, the only facility capable of reproducing such extreme states. We present a modeling approach avoiding costly hydrodynamic simulations and enabling rigorous uncertainty estimates of our measurement through Bayesian analysis.

Keywords: Free-Free Opacity; Thomson Scattering; Red Dwarf Stars; X-Ray Radiography; Radiation Transport