New Discoveries in Stars and Stellar Evolution through Advances in Laboratory Astrophysics

As the Stars and Stellar Evolution (SSE) panel is fully aware, the next decade will see major advances in our understanding of these areas of research. To quote from their charge, these advances will occur in studies of the Sun as a star, stellar astrophysics, the structure and evolution of single and multiple stars, compact objects, SNe, gamma-ray bursts, solar neutrinos, and extreme physics on stellar scales. Central to the progress in these areas are the corresponding advances in laboratory astrophysics, required to fully realize the SSE scientific opportunities within the decade 2010-2020. Laboratory astrophysics comprises both theoretical and experimental studies of the underlying physics that produces the observed astrophysical processes. The 6 areas of laboratory astrophysics, which we have identified as relevant to the CFP panel, are atomic, molecular, solid matter, plasma, nuclear physics, and particle physics. In this white paper, we describe in Section 2 the scientific context and some of the new scientific opportunities and compelling scientific themes which will be enabled by advances in laboratory astrophysics. In Section 3, we discuss some of the experimental and theoretical advances in laboratory astrophysics required to realize the SSE scientific opportunities of the next decade. As requested in the Call for White Papers, Section 4 presents four central questions and one area with unusual discovery potential. Lastly, we give a short postlude in Section 5.

💡 Research Summary

The white paper titled “New Discoveries in Stars and Stellar Evolution through Advances in Laboratory Astrophysics” makes a compelling case that the next decade (2010‑2020) will see transformative progress in stellar astrophysics, provided that laboratory astrophysics advances in lockstep. It begins by outlining the broad scientific landscape: the Sun as a star, the structure and evolution of single and multiple stars, compact objects, supernovae (SNe), gamma‑ray bursts (GRBs), solar neutrinos, and extreme physics on stellar scales. The authors argue that each of these topics hinges on precise knowledge of the underlying atomic, molecular, solid‑state, plasma, nuclear, and particle physics – the six pillars of laboratory astrophysics identified for the Stars and Stellar Evolution (SSE) panel.

Section 2 surveys the emerging scientific opportunities that will be unlocked by improved laboratory data. High‑resolution atomic spectroscopy, with accurate transition probabilities and collisional cross‑sections, will sharpen abundance determinations for stellar atmospheres and the solar photosphere, thereby refining models of stellar interiors and evolution. Molecular physics experiments at low temperature and high density will elucidate the formation pathways of complex organics in protostellar clouds and protoplanetary disks, linking chemistry to planet formation. Solid‑matter studies of interstellar dust analogues (silicates, carbonaceous grains) will provide the optical constants needed to interpret infrared and far‑infrared observations of star‑forming regions and supernova remnants. Plasma experiments that recreate high‑energy‑density, magnetized, rotating flows will directly test magnetohydrodynamic (MHD) mixing, angular‑momentum transport, and shock physics relevant to stellar convection zones and core‑collapse supernova explosions. Nuclear physics measurements of key reaction rates – the p‑p chain, CNO cycle, and the neutron‑capture r‑ and s‑processes – will reduce uncertainties in stellar energy generation and nucleosynthesis yields. Finally, particle‑physics efforts to detect high‑energy neutrinos and to constrain dark‑matter interaction cross‑sections will open new windows on the interiors of compact objects and the physics of core‑collapse.

Section 3 translates these needs into concrete experimental and theoretical milestones. The authors call for expanded synchrotron and free‑electron‑laser facilities for atomic and molecular spectroscopy, ultra‑cold trap setups for astrochemical kinetics, high‑precision calorimetry for dust optical property measurements, laser‑driven implosion platforms and pulsed‑power machines for astrophysical plasma scaling, underground accelerator labs for low‑energy nuclear cross‑sections, and next‑generation neutrino observatories coupled with deep‑underground detectors for particle studies. They stress the importance of cross‑disciplinary collaborations, shared databases, and the integration of laboratory results into stellar evolution codes (e.g., MESA, GARSTEC).

Section 4 poses four central questions that will guide the community: (1) How do rotation, magnetic fields, and internal waves combine to drive mixing and angular‑momentum redistribution in stars of different masses? (2) What are the precise r‑process and s‑process pathways in core‑collapse supernovae and neutron‑star mergers, and how do they shape the Galactic chemical evolution? (3) What are the progenitor systems and jet‑launch mechanisms that produce gamma‑ray bursts, and how can laboratory plasma experiments constrain them? (4) What physical processes underlie the observed variability of the solar neutrino flux, and how can improved neutrino cross‑section data resolve them? The authors also highlight an “area with unusual discovery potential”: the study of matter under extreme pressure, temperature, and magnetic fields, where laboratory experiments may reveal new phases of matter or unexpected nuclear reaction channels not captured by current theory.

In the concluding Section 5, the paper reiterates that laboratory astrophysics is the essential bridge between observation and theory for the SSE panel. By delivering high‑fidelity atomic, molecular, solid‑state, plasma, nuclear, and particle data, the community will be able to interpret the wealth of data expected from upcoming observatories (e.g., JWST, LSST, Athena) and to answer the fundamental questions about how stars live, die, and enrich the cosmos. The authors advocate for sustained funding, coordinated international efforts, and the establishment of shared data repositories to ensure that the laboratory astrophysics enterprise remains a vibrant, integral component of 21st‑century stellar astrophysics.