Description:

Abstract:

The brightness of the tip of the red-giant branch allows one to constrain novel energy losses that would lead to a larger core mass at helium ignition and thus to a brighter TRGB than expected by standard stellar models. The required absolute TRGB calibrations strongly improve with reliable geometric distances that have become available for the galaxy NGC 4258 that hosts a water megamaser and to the Large Magellanic Cloud based on 20 detached eclipsing binaries. Moreover, we revise a previous TRGB calibration in the globular cluster ω Centauri with a recent kinematical distance determination based on Gaia DR2 data. All of these calibrations have similar uncertainties and they agree with each other and with recent dedicated stellar models. The reduced observational errors imply that stellar evolution theory and bolometric corrections begin to dominate the overall uncertainties.

Seminar Speaker: Francesco Capozzi, Virginia Tech

Host: André de Gouvea

Meeting Details:
Monday, April 12, 2021 at 4:00pm (Central Time)

Zoom info:
Please email laura.nevins@northwestern.edu to get the Zoom meeting link. 

Keywords: Physics, Astronomy, HEP