Dr. Michael Eides University of Kentucky I will discuss physics of exotic muonium and positronium atoms, high precision quantum electrodynamic calculations of energy levels, and determination of the electron-muon mass ratio. I'll introduce the proton radius puzzle, discuss briefly the experimental data on muonic hydrogen, deuterium, and helium, and explain the status of the respective theory.
Dr. Fabienne Bastien Pennsylvania State University As a result of the high precision and cadence of surveys like MOST, CoRoT, and Kepler, we may now directly observe the very low-level light variations arising from stellar granulation in cool stars. Here, we discuss how this enables us to more accurately determine the physical properties of Sun-like stars, to understand the nature of surface convection and its connection to activity, and to better determine theproperties of planets around cool stars. Indeed, such sensitive photometric "flicker" variations are now within reach for thousands of stars, and we estimate that upcoming missions like TESS will enable such measurements for ~100 000 stars. We present recent results that tie “flicker” to granulation and enable a simple measurement of stellar surface gravity with a precision of 0.1 dex. We use this, together and solely with two other simple ways of characterizing the stellar photometric variations in a high quality light curve, to construct an evolutionary diagram for Sun-like stars from the Main Sequence on towards the red giant branch. We discuss further work that correlates “flicker” with stellar density, allowing the application of astrodensity profiling techniques used in exoplanet characterizationto many more stars. We also present results suggesting that the granulation of F stars must be magnetically suppressed in order to fit observations. Finally, we show that we may quantitatively predict a star's RV jitter using our evolutionary diagram, permitting the use of discovery light curves to help prioritize follow-up observations of transiting exoplanets.
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A small fraction of the universe's energy-density is comprised of normal matter. A still smaller fraction is bound into stars and gas that we can see and are responsible for life. This talk examines what we know about the baryon content of, and how stars assembled in, galaxies like the Milky Way (MW). Dynamical measurements from integral-field spectroscopy indicate the baryonic mass of spiral disks is small. Radiative-transfer modeling of dusty, edge-on galaxies reveals super-thin stellar disks previously missed. These findings yield a consistent picture of light disks with young luminosity-weighted stellar ages. A new census from the Sloan Digital Sky Survey-IV, now underway, will test how broadly these results apply to the galaxy population as a whole. This advance allows us to better place the MW in context of today's galaxy population, and to leverage the MW's unique archaeological record against observations of distant galaxies. A critical question that can be resolved is whether stellar age and abundance gradients in galaxy disks are the result of a settling process of decreasingly turbulent gas or dynamical heating.