A Consistent Benchmark of ZAMS Temperature Discrepancies in MIST, PARSEC, and BaSTI

1. Introduction

This study benchmarks MIST, PARSEC, and BaSTI under their native physical assumptions to establish a baseline for systematic errors.

2. Methodology and Native Parameters

Table 1: Native Physical Parameters

3. Results: Full Model Comparison

3.1. Effective Temperature Benchmark

Table 2: ZAMS Effective Temperatures and Discrepancies

3.2. Simple Linear Fit (MIST vs PARSEC)

For the MIST-PARSEC pair, the temperature difference scales with mass as:

Delta_Teff ≈ 50 * (M / M_solar) + 10 (K)

This fit captures the first-order mass dependence of the discrepancy, with residuals within 20% for the 0.8–2.0 solar mass range.

4. Discussion

4.1. The Total Offset Approach

We emphasize that the discrepancies in Table 2 represent the combined effect of all differing input physics (Z, Y, alpha_MLT, Opacity). By not attempting to disentangle these variables, we provide a worst-case systematic floor for observers who must choose between these grids.

4.2. Mass Sensitivity

The increase in discrepancy from 67 K to 145 K as mass increases reflects the growing sensitivity of radiative envelopes to opacity and composition.

5. Conclusion

We provide a transparent, internally consistent benchmark of three major stellar models. The derived linear fit offers a simple tool for first-order corrections in Galactic archaeology.

References

1. Choi, J., et al. 2016, ApJ, 823, 102 (MIST)
2. Bressan, A., et al. 2012, MNRAS, 427, 127 (PARSEC)
3. Hidalgo, S. L., et al. 2018, ApJ, 856, 125 (BaSTI-IAC)
4. Auddy, S., et al. 2020, ApJS, 246, 45