Population II Distance Indicators: RR Lyrae Variables, Tip of the Red Giant Branch (TRGB) Stars and J-Branch Asymptotic Giant Branch (JAGB/Carbon) Stars

Understand

We review the theoretical underpinnings, evolutionary status, calibrations and current applications of three bright Population II extragalactic distance indicators: Tip of the Red Giant Branch (TRGB) stars, RR Lyrae variables and J-Branch Asymptotic Giant Branch (JAGB/Carbon) stars.

• For M_I (TRGB) = -4.05 mag the Hubble constant is determined to be Ho = 69.8 +/- 0.6 (stat) +/-1.6 (sys) km/s/Mpc.