This page hosts an interactive calculator that estimates the critical value for coevality of two binary stars.

If you use the calculator, please acknowledge the following paper:

Valle G., Dell'Omodarme M., Prada Moroni P.G., Degl'Innocenti S. (2015).
*A statistical test on the expected difference on grid-based binary
stars age estimates*. In preparation.

### Input

The following information are required:*M1*: the mass of the primary star in solar unit (range: 0.80 - 1.60 M_{sun}).*M2*: the mass of the secondary star in solar unit (range: 0.80 - 1.60 M_{sun}).*Metallicity*: the metallicity [Fe/H] of the primary star.*r*: the relative age of the primary star, defined as the ratio of the age af the star and the age at the TAMS.- Delta T
_{eff}: error on the effective temperature (in K). - Delta [Fe/H]: error on the metallicity (in dex).
- Delta M: relative error in the mass determination (range: [0.0; 1.0]).
- Delta R: relative error in the radius determination (range: [0.0; 1.0]).

### Output

The following information are computed:- W
_{0.95}: the critical value at level 0.05. - beta W
_{0.95}: the approximated critical values from the beta distribution.

### Details

For the computations, the following correlations ara assumed:

- rho = 0.95 between the two effective temperatures
- rho = 0.95 between the two [Fe/H]
- rho = 0.8 between the two masses
- rho = 0.0 between the two radii.

## Computation

Please provide the required input, press the button "Compute...", and wait a few seconds.