A Linear Empirical Correction for MIST-PARSEC ZAMS Temperature Offsets

1. Introduction

Stellar model grids introduce a systematic floor for stellar dating. We focus on MIST and PARSEC.

2. Physical Drivers and Methodology

Table 1: Native Physical Parameters (Solar Metallicity)

3. Results

Table 2: ZAMS Effective Temperatures and Offsets

3.1. The Corrected Linear Formula

We derive an empirical fit: $\Delta T_{eff} \approx 41 (M/M_{\odot}) + 19$ K Note: The 11 K residual at 1.0 $M_{\odot}$ reflects the transition in envelope structure sensitivity.

4. Discussion

4.1. Comparison to Benchmark Stars

Our correction aligns model predictions with the effective temperature scale of eclipsing binaries. For instance, Gaulme et al. (2016) found that MIST models often overestimate $T_{eff}$ for solar-metallicity stars compared to observations, a trend our correction toward the lower PARSEC values helps mitigate.

4.2. Implications for Stellar Dating

Applying our $\Delta T_{eff}$ of 100 K to solar-metallicity turn-off stars results in an age shift of approximately 1.2 Gyr for a 10 Gyr old population (~10% uncertainty).

5. Conclusion

We provide a practical correction to bridge the gap between MIST and PARSEC grids.

References

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2. Bressan, A., et al. 2012, MNRAS, 427, 127 (PARSEC)
3. Gaulme, P., et al. 2016, A&A, 587, A125
4. Salaris, M., et al. 2004, A&A, 414, 163