Automated Identification of the Tip of the Red Giant Branch in Globular Clusters with Gaia Data

Abstract

This study introduces an automated approach for identifying the tip of the red giant branch (TRGB) in globular clusters, combining astronomical data with algorithmic methods. Using a dataset of 160 globular clusters and Python scripts, we matched stellar sources with Gaia data. Our script generates color-magnitude diagrams (CMDs), and uses the local outlier factor (LOF) algorithm to remove outliers. Applying a second-degree polynomial to fit red giant branch (RGB), we identify the TRGB as the star closest to the fitted curve's endpoint. By this method, we expanded TRGB samples in global clusters to 91 with newer observational data. Our results show a decreasing trend in I-band luminosity for metallicities greater than $-$1, consistent with previous studies. The results show a robust trend fitting and the ${\mathrm{M}}_{\mathrm{I}}$ of TRGB is about $-$4.02 with extremely low metallicity. Our approach enhances TRGB identification efficiency while providing valuable insights for developing automatic tools in astronomical data analysis.

References in corpus (17)

• The Gaia mission
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• Gaia Data Release 3: Summary of the content and survey properties
• astroquery: An Astronomical Web-Querying Package in Python
• Measurements of the Hubble Constant: Tensions in Perspective
• Gaia EDR3 view on Galactic globular clusters
• The Optical to Mid-Infrared Extinction Law Based on the APOGEE, Gaia DR2, Pan-STARRS1, SDSS, APASS, 2MASS and WISE Surveys
• Distances to PHANGS Galaxies: New Tip of the Red Giant Branch Measurements and Adopted Distances
• Homogeneous photometry VII. Globular clusters in the Gaia era
• The Parallax of Omega Centauri Measured from Gaia EDR3 and a Direct, Geometric Calibration of the Tip of the Red Giant Branch and the Hubble Constant
• The brightness of the Red Giant Branch tip: Theoretical framework, a set of reference models, and predicted observables
• The Tip of the Red Giant Branch Distances to Type Ia Supernova Host Galaxies. IV. Color Dependence and Zero-Point Calibration
• DUSTiNGS III: Distribution of Intermediate-Age and Old Stellar Populations in Disks and Outer Extremities of Dwarf Galaxies
• A Wide-Field View on Multiple Stellar Populations in 28 Milky Way Globular Clusters
• The Carnegie Chicago Hubble Program X: Tip of the Red Giant Branch Distances to NGC 5643 and NGC 1404
• Stellar variability in Gaia DR3. I. Three-band photometric dispersions for 145 million sources
• A Gaia Data Release 3 View on the Tip of the Red Giant Branch Luminosity

Cited by in corpus (1)

• Calibrating the Tip of the Red Giant Branch and measuring Magellanic Cloud distances to 2% exclusively with Gaia