Mapping Stellar Helium

Objetivo

In the epoch of Gaia, fundamental stellar properties will be made widely available for large numbers of stars. These properties are expected to unleash a new wave of discovery in the field of astrophysics. But while many properties of stars are measurable, meaningful Helium abundances (Y) remain elusive and as a result fundamental properties are not accurate.

Helium enrichment laws, which underpin most stellar properties, link initial Y to initial metallicity, but these relations are very uncertain with gradients (dY/dZ) spanning the range 1 to 3. This uncertainty is the initial Y problem and this is a bottleneck that must be overcome to unleash the true potential of Gaia.

Without measurements of initial Y for all stars we need to find alternative observables that trace out the evolution of initial Y. We will search for better tracers using the power of asteroseismology as a calibrator.

Asteroseismic measures of Helium will be used to construct a map from observable properties (fundamental, chemical or even dynamical) back to initial Helium. This is a challenge that can only be solved through the use of the latest asteroseismic techniques coupled to a rigorous yet flexible statistical scheme. I am uniquely qualified in the cutting edge methods of asteroseismology and the application of advanced multi-level statistical models. The intersection of these two skill sets will allow me to solve the initial Helium problem.

The motivation for a timely solution to this problem could not be stronger. We have just entered an age of large asteroseismic datasets, vast spectroscopic surveys, and the billion star program of Gaia. The next wave of scientific breakthroughs in stellar physics, exoplanetary science, and Galactic archeology will be held back unless accurate fundamental stellar properties are available. We can only produce these accurate properties with a reliable map of stellar Helium.