Help on basic Isochrone Plots

The Isochrone plot facility allows to produce Isochrone plots for Johnson UBVRI diagrams of the follwing kinds:

1. Colour-magnitude and colour-colour diagrams for one photometric system, using data from one data source,
2. Colour-magnitude and colour-colour diagrams for two photometric systems, using data from two data sources, one for each system,
3. Select Distance Modulus, E(B-V), Age, Metallicity, Probability Criteria, Binary Sequence and Source of Isochrones
The plots are active, so that stars can be identified by clicking on the points.

Because the plot are made on the basis on the original data file, one needs to select the data sources.
To help on such decision, the number of stars in each data source is indicated within brackets and a link is provided to get the full text of the reference. Only the data sources with more than 10 stars are listed.

1) Diagrams for one photometric system

These diagrams are the colour-magnitude and colour-colour diagrams. To obtain such plots:
1. Select one photometric system,
2. Select two parameters,
3. Select a data source,
4. Click on the button "Plot CMD".

2) Diagrams for two photometric systems

These diagrams are the colour-magnitude and colour-colour diagrams. To obtain such plots:
1. Select two photometric systems,
2. Select one parameter for each system,
3. Select the corresponding data sources,
4. Click on the button "Plot CMD".

3) Plot Isochrones

As last step, the Distance, E(B-V) and Age can be chosen. The default values, if available, are shown. The membership probabilities are chosen from the file 'prob.mu' and given with three different symbols:

• Filled circles: Probability > 0.50,
• Open circles: Probability < 0.50,
• Crosses: Probability not known.
The Binary Sequence is just shifted by 0.754 mag in V.

The isochrones for the given metallicities [Z] are tabulated in steps of 0.05 dex in log t. For ages outside the limites, the closest Isochrone will be plotted. Currently there are two different sets available:

• Padova Group: Tabulated for 6.6 < log t < 10.25,
• Geneva Group: Tabulated for 6.0 < log t < 10.20, available for masses higher than 0.8 Solar masses.
Only the standard Isochrones have been implemented.

For the reddening the following relations were used: A(V) = 3.1E(B-V) = 4.3E(U-B) = 5.12E(V-R) = 2.48E(V-I) = 4.43E(R-I)