Astrophysical Distance Scale. VII. A Self-consistent, Multiwavelength Calibration of the Slopes and Relative Zero Points for the Run of Luminosity with the Color of Stars Defining the Tip of the Red Giant Branch

• Published in: The Astronomical journal Vol. 166; no. 6; pp. 224 - 231
• Main Authors: Madore, Barry F., Freedman, Wendy L., Owens, Kayla
• Format: Journal Article
• Language: English
• Published: Madison The American Astronomical Society 01-12-2023; IOP Publishing
• Subjects: Calibration; Distance indicators; Infrared photometry; James Webb Space Telescope; Luminosity; Magellanic clouds; Near infrared radiation; Red giant branch; Red giant stars; Slopes; Stars
• ISSN: 0004-6256; 1538-3881
• DOI: 10.3847/1538-3881/ad022c

Abstract
Given the recent successful launch of the James Webb Space Telescope, determining robust calibrations of the slopes and absolute magnitudes of the near- to mid-infrared tip of the red-giant branch (TRGB) will be essential to measuring precise extragalactic distances via this method. Using ground-based data of the Large Magellanic Cloud from the Magellanic Clouds Photometric Survey along with near-infrared (NIR) data from 2MASS and mid-infrared (MIR) data collected as a part of the SAGE survey using the Spitzer Space Telescope, we present slopes and zero-points for the TRGB in the optical (VI), NIR (JHK), and MIR ([3.6] and [4.5]) bandpasses. These calibrations utilize stars +0.3 ± 0.1 mag below the tip, providing a substantial statistical improvement over previous calibrations which only used the sample of stars narrowly encompassing the tip.