StarModelSequence

An evolutionary sequence of stellar models. This component is where the evolution takes place, creating growing sequences of models of increasing age or, under pseudo-evolution of some other changing parameter.

The data tables, control parameters and initial model are set with the starDataTables, starCtrl and initialModel menus respectively. The starView menu is an optional StarView component in which to display the structure of the latest model. If set, the HRDiagram displays the sequence as it develops.

Three types of evolutionary sequences are possible:

1. free evolution, where stars evolve through time.

2. artificial mass loss or gain where mass is added or removed to generate models of different total mass. Typically, the composition is held fixed and thermal terms are ignored for this. In this mode, the rate of mass change, dMdt can be specified, as well as the target mass at which to stop the sequence.

3. pseudo-evolution where physical constants are gradually modified to generate a sequence of models. These can be useful, for example, for testing hypotheses about how stellar properties depend on certain physical quantities, or for making stars under slightly different physics so as to distinguish putative explanations of evolution which are purely coincidental from those which may be fundamental. So, for example, to test the claim that process B occurs because state A holds, one can sometimes make a pseudo-star with minor changes in the physics in which state A no longer holds, but process B does occur all the same. It is suggested that most explanations of why stars become red giants are of this nature.

   Pseudo evolution is effected by setting a PseudoPhysFactors object as the target and gradually changing the current state towards it at rate dPdt (per year).

There are four buttons at the bottom to govern the evolution, with a display area to report the current state of the model. Typically, after setting the initial model, click "initialize", check there are no error messages (it should say "ready") and then click "single step" to take steps one by one or "run" to run continually. The evolution can be stopped with the "stop" button and restarted with "run". Clicking "initialize" will loose all record of any previous sequence made in this component. To make multiple sequences, make multiple sequence objects.

Note that the calculations are threaded, so you can carry on doing other things with the program while the evolutionary sequence is running. Indeed, on a multiprocessor machine, you can run several sequences at the same time to use all the processors.