# Astrophysical properties of 600 bonafide single stars in the Hyades open cluster

**Authors:** Wolfgang Brandner, Per Calissendorff, Taisiya Kopytova  
**arXiv:** [2301.04159](https://arxiv.org/abs/2301.04159)  
**Date:** 2023-01-10  
**Summary page:** https://www.summarizepaper.com/en/paper/2301.04159v1/

## Key points

- Determination of astrophysical properties of stars is a challenging task that often relies on the application of stellar models
- Stellar sequences in nearby open clusters provide an excellent means to test and calibrate these models, assign astrophysical properties consistently to a large sample of stars, and serve as benchmarks for atmospheric and evolutionary models
- The study aims to update the single star sequence of members of the Hyades cluster, identify the best-fitting isochrones, and determine the astrophysical properties of 600 bonafide single main-sequence stars
- Data from the Gaia Catalogue of Nearby Stars is used to identify high-probability members of the Hyades cluster
- A multi-step method is applied to flag photometric outliers and identify bona fide single stars and likely binary and multiple systems
- The single stars define a tight sequence that is well-fitted by PARSEC isochrones for a supersolar metallicity of [M/H] = +0.18 ± 0.03 and an age of 775 ± 25 Myr in the mass range 0.12 to 2.2 Msun
- The derived stellar properties include mass, effective temperature, luminosity, and surface gravity for each candidate member star
- These properties can serve as benchmarks for atmospheric and evolutionary models as well as all-sky catalogs containing stellar parameters such as mass, effective temperature, luminosity, surface gravity etc., which are also applicable for exoplanet studies among Hyades exoplanet hosts

## Summary

The determination of astrophysical properties of stars is a challenging task that often relies on the application of stellar models. Stellar sequences in nearby open clusters provide an excellent means to test and calibrate these models, assign astrophysical properties consistently to a large sample of stars, and serve as benchmarks for atmospheric and evolutionary models. In this study, we aim to update the single star sequence of members of the Hyades cluster, identify the best-fitting isochrones, and determine the astrophysical properties of 600 bonafide single main-sequence stars. We use data from the Gaia Catalogue of Nearby Stars to identify high-probability members of the Hyades cluster. We apply a multi-step method to flag photometric outliers and identify bona fide single stars and likely binary and multiple systems. The single stars define a tight sequence that is well-fitted by PARSEC isochrones for a supersolar metallicity of [M/H] = +0.18 ± 0.03 and an age of 775 ± 25 Myr in the mass range 0.12 to 2.2 Msun. The derived stellar properties include mass, effective temperature, luminosity, and surface gravity for each candidate member star. These properties can serve as benchmarks for atmospheric and evolutionary models as well as all-sky catalogs of stellar astrophysical properties. Additionally, they are relevant for studies on exoplanet properties among Hyades exoplanet hosts. To ensure accuracy in our results, we clean up problematic data from Gaia DR3 using a multi-step process that classifies GCNS candidate members into four groups: bona fide single stars, probable binary and multiple systems, white dwarfs, and sources with problematic photometry in at least one Gaia photometric band. Our findings validate PARSEC isochrones while also highlighting potential modifications needed in temperature-Rosseland mean optical depth (T-τ) relations in stellar models. This study provides valuable insights into the astrophysical properties of stars and their evolution, contributing to our understanding of the universe by providing accurate measurements for benchmarking atmospheric and evolutionary models as well as all-sky catalogs containing stellar parameters such as mass, effective temperature, luminosity, surface gravity etc., which are also applicable for exoplanet studies among Hyades exoplanet hosts.