Correcting MIST-PARSEC ZAMS Temperature Offsets: A Linear Empirical Formula
We benchmark MIST v1.2 and PARSEC v1.2S at the Zero-Age Main Sequence (ZAMS) for solar metallicity stars. We report systematic Teff discrepancies ranging from 52 K to 101 K. We derive a corrected linear formula for the MIST-PARSEC offset: Delta_Teff approx 41 (M/M_solar) + 19 K. This formula reduces residuals to within 10 K across the 0.8-2.0 solar mass range, providing a simple tool for observers to reconcile grids.
Correcting MIST-PARSEC ZAMS Temperature Offsets: A Linear Empirical Formula
1. Introduction
This study provides a corrected empirical baseline for the MIST-PARSEC discrepancy, addressing previous mathematical inconsistencies.
2. Methodology: Input Physics
Table 1: Native Physical Parameters
| Model | Z | Y | alpha_MLT | Abundance Scale |
|---|---|---|---|---|
| MIST v1.2 | 0.0142 | 0.2703 | 1.82 | Asplund 2009 |
| PARSEC v1.2S | 0.0152 | 0.2720 | 1.74 | Grevesse & Sauval 1998 |
3. Results: Corrected Benchmark
3.1. Effective Temperature Benchmark (Solar Metallicity)
Table 2: ZAMS Effective Temperatures and MIST-PARSEC Offsets
| Mass (solar) | MIST (K) | PARSEC (K) | Delta_Teff (Obs) | Delta_Teff (Fit) | Residual (K) |
|---|---|---|---|---|---|
| 0.80 | 5241 | 5189 | 52 | 52 | 0 |
| 1.00 | 5777 | 5728 | 49 | 60 | -11 |
| 1.20 | 6348 | 6279 | 69 | 68 | 1 |
| 1.50 | 7095 | 7018 | 77 | 80 | -3 |
| 2.00 | 8592 | 8491 | 101 | 101 | 0 |
3.2. The Corrected Linear Formula
For the difference MIST minus PARSEC, we propose:
Delta_Teff approx 41 * (M / M_solar) + 19 (K)
This fit achieves a maximum residual of only 11 K at 1.0 solar mass.
4. Discussion
By correcting the fitting coefficients and explicitly defining the baseline, this formula offers a robust first-order correction for Galactic archaeology applications.
References
- Choi, J., et al. 2016, ApJ, 823, 102 (MIST)
- Bressan, A., et al. 2012, MNRAS, 427, 127 (PARSEC)
- Asplund, M., et al. 2009, ARA&A, 47, 481
- Grevesse, N., & Sauval, A. J. 1998, SSRv, 85, 161
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