CMD Frequently Asked Questions

Is there a bug in the Z=0.008 isochrone of log(age)=9.15? Not exactly. For this particular Z and age, there is a pronounced peak in the production rate of AGB stars, that causes a transient red phase in the integrated SSP colours. The reason is explained in section 3.2.1 of Girardi & Bertelli (1998), and another paper is in preparation in order to further clarify the question and give detailed advice. The effect is well dealt by the algorithms used in CMD, but it has caused problems to many users, especially when the isochrones are fed to population synthesis codes that do not deal properly with the (occasional) gaps in the mass distribution of AGB stars. In order to alleviate the problem, on 20jun08 the option "Use improved interpolation scheme" has been inserted on the web page: It suppresses the Z=0.008, 1.85 M_sun evolutionary track from the isochrone interpolation, then spreading the "overproduction" of AGB stars at log(age)=9.15 over a wider range of ages, and avoiding gaps in the mass distribution of AGB stars. It also activates some minor cosmetic changes in other isochrones, related to a better choice of equivalent evolutionary points.
NOTE: From 21nov08 on, the "Use improved interpolation scheme" option was set as the default. It includes, in addition, the correction of a small bug affecting the MS and SGB of isochrones with Z<0.001, at ages between 1.1e9 and 1.2e9 yr.
How do I refer to these isochrones? Use the references provided in the output header. These references however may not be complete and we strongly encourage you to look at the papers for the details!

In case you want to add a reference to this URL, use "". References to official papers are however to be preferred.

Why do I get Object not found? Some users keep finding a "Object not found" error message instead of the output files. It may happen in browsers that don't support HTML 4. Update your browser in this case. Anything later than 2001 should work fine.

This service is mantained by Léo Girardi at the Osservatorio Astronomico di Padova.
Questions, comments and special requests should be directed to leo.girardi@oapd·inaf·it .
Last modified: June 6, 2007