Interactive Pages

Index of Live Figures

Live figures are Java applets that allow some interaction with the reader. The live figures are simpler than the simulator applets. Most live figures are plots with parameters that can be set by the reader. At this time there is only one live figure on the web site.

A live figure can be controlled with either the mouse or the keyboard. The figures conform to a common set of mouse and keyboard commands that are described on the Applet Control Guide page.

Black-Body Spectra

The figure on this page shows black-body spectra for four temperatures. The reader can change the temperature, the units of temperature, and the units of photon energy.

Hydrogen Fusion Rates

This figure shows the two-nucleus reaction rates that convert hydrogen into helium. The plot shows two different sets of reactions: reactions in the PP chain, and reactions in the CNO cycle. The rates are plotted as functions of temperature. The temperature can be expressed in either degrees or in keV.

Helium Fusion Rates

The helium nuclear fusion rates are presented and discussed. These rates are displayed by a live figure as two plots. The plots give the fusion rates as a function of temperature. The reader can set the temperature units to either degrees Kelvin or keV. The figure shows that the nuclear fusion of helium-4 is dominated by the triple-alpha process.

Polytropic Stellar Models

The figure on this page shows the polytropic model for stars. The reader can plot this curve as either a density or a function φ as a function of either a radius normalized to give a fixed stellar mass or a dimensionless radius ξ. The adiabatic index used to plot the models can be changed by the reader.

Travel to the Stars under Special Relativity.

A spaceship that is accelerating at a constant rate can travel to the stars in what its passengers regard as a startlingly short time. Accelerating with the average gravitational acceleration at Earth's surface, our travelers can reach nearby galaxies and return to Earth in a human lifetime. The Earth they find, however, will have aged by millions of years. The reader can use the live figure on this page to learn how the rate of acceleration changes these results.

Earth's Time During Interstellar Travel.

As an accelerating spacecraft travels to the stars, its passengers sees the passage of time on Earth slow to almost a stop as Earth falls through the spacecraft's event horizon. On the return trip, the passengers see Earth's days pass in seconds. The page includes a live figure that shows how time on Earth elapses with time on the spacecraft for user-selected distances and rates of acceleration.