Using the Tip of the Red Giant Branch as a Distance Indicator in the Near Infrared

Understand

The tip of the red giant branch (TRGB) is a well-established standard candle used to measure distances to nearby galaxies.

• The TRGB luminosity is typically measured in the I-band, where the luminosity has little dependency on stellar age or stellar metallicity.
• As the TRGB is brighter at wavelengths redder than the I-band, observational gains can be made if the TRGB luminosity can be robustly calibrated at longer wavelengths.
• This is of particular interest given the infrared capabilities that will be available with the James Webb Space Telescope and an important calibration consideration for using TRGB distances as part of an independent measurement of the Hubble constant.