We are a tax-exempt 501(c)(3) non-profit organization dedicated to scientific research and public education. We support and conduct scientific research on topics relevant to the observational and theoretical properties of white dwarf stars, and we create and distribute public education resources through our website. If you would like to support one of the projects below by donating equipment, time, or funding, please find out how you can help or consider making a secure online donation. If you have any questions, or other ideas for how you might be able to get involved with one of these projects, please do not hesitate to contact us.

Support one of our Projects:

• Whole Earth Telescope - an international collaboration of astronomers at telescopes around the globe.

• Time-series CCD photometer - a portable instrument specifically designed for our observations.

• Open Source White Dwarf Code - a computer code to model the evolution and pulsations of white dwarfs.

• Asteroseismology Metacomputer - a commodity-hardware parallel computer designed to run our models.

• Evolutionary Computing - an analysis method based on a genetic algorithm for objective global fitting.

Overview: Our basic research goal is to observe and study the internal structure and composition of white dwarf stars, the remnants of a nuclear fusion furnace that once turned hydrogen into helium and energy, a process which still powers stars like the Sun. An unexpected circumstance allows us to probe their structure: some of these stars vibrate in a periodic manner that sends seismic waves deep through their interior and brings information to the surface. We see this manifested as complex periodic variations in their brightness, which we can study and analyze, much as seismologists study the inner structure of the earth using earthquakes. White dwarfs once supported steady nuclear fusion, and would again if hydrogen were injected into them. We essentially have a working fusion laboratory to study, one that we must understand in detail if we are ever to master this clean sustainable energy source and duplicate the process on this planet.

Whole Earth Telescope

We can determine the internal structure of pulsating white dwarfs using the techniques of high speed photometry to observe their variations in brightness over time, and then matching these observations with a computer model which behaves the same way. The parameters of the model are chosen to correspond one-to-one with the physical processes that give rise to the variations, so a good fit to the data gives us confidence that our model reflects the actual physics of the stars themselves. In the past decade, the observational requirements of white dwarf seismology have been satisfied by the development of the Whole Earth Telescope (WET) -- an informal collaboration of astronomers at observatories around the globe who cooperate to produce nearly continuous time-series photometry of white dwarfs for up to 14 days at a time. This instrument has provided a wealth of seismological data on the different varieties of pulsating white dwarf stars.

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We are working to establish a permanent WET endowment, which would support the general operating expenses of this instrument through secure investments. Ideally, this fund would allow for two runs of the WET each year, and provide for travel expenses to send astronomers to remote observatories and to bring international collaborators to headquarters for logistical support.

Evolutionary Computing

In an effort to bring the analysis of WET data to the level of sophistication demanded by the observations, we are developing a model-fitting method based on a genetic algorithm. The underlying ideas for genetic algorithms were inspired by Charles Darwin's notion of biological evolution through natural selection. The basic idea is to solve a problem by evolving the best solution from an initial set of random guesses. The computer model provides the framework within which the evolution takes place, and the individual parameters controlling it serve as the genetic building blocks. Observations provide the selection pressure. In practice, this method is much more efficient than other comparably global techniques.

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We have had unprecedented success from the application of this method to helium-atmosphere pulsating (DBV) white dwarfs, and we are currently working to extend the method to the other types of pulsators. The hot DOV white dwarfs promise to serve as interesting probes of neutrino physics, while we hope to test the theory of stellar crystallization with the cool massive DAV white dwarf BPM 37093 (known informally as the "Diamond in the sky").

Asteroseismology Metacomputer

Although extremely effective and objective in their application, genetic algorithms still require a very large amount of computer time because they involve running thousands of complex models for each set of observations. To make this approach practical, we designed and built a specialized computer -- a collection of 64 minimal PCs connected by a network, which can run our models in parallel about 60 times faster than any one of them by itself. Our initial application of this new method to a well-observed pulsating white dwarf demonstrated that our models are very sensitive to the central composition, and allowed us to measure the astrophysically-important (C + He → O) nuclear fusion reaction rate with much greater precision than is possible in terrestrial laboratories. The potential of this approach to probe interesting physics is clear. What we can accomplish by applying it to other classes of objects is limited only by the computational resources that we can devote to each problem.

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Fortunately, the modular design of our computer is conducive to expansion, and the off-the-shelf hardware has become both faster and less expensive in the three years since we built the original. We are currently raising funds to build a new parallel computer based on our proven design, and to duplicate it at two collaborating institutions, so we have the computational power necessary to probe the other classes of white dwarf stars using this new method.

Open Source White Dwarf Code

In an environment of dwindling resources, scientific investigations are facing competitive stresses that are beginning to separate scientists into two camps: those who guard their techniques jealously for fear of being rendered obsolete, and those who embrace the true spirit of scientific inquiry and share their results and resources freely with both colleagues and competitors without prejudice. In some areas of astronomy, this cultural split is beginning to hinder scientific progress.

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OpenWD is an attempt to initiate an open, world-wide collaboration among experts who study white dwarf stars to develop a complete, cutting-edge computer code to model the evolutionary and pulsational characteristics of white dwarf stars. The project is beginning with a complete FORTRAN code from the public domain to serve as the basis for updates and additions from collaborators who want to contribute modules that include their own prescriptions for various physical ingredients. This distributes the workload among scientists who have a stake in seeing their own work included, and facilitates comparison between competing ideas by providing a common base for all of the modules. It also helps to ensure a future where it will be easier for all astronomers to embrace the collaborative spirit.

Time-series CCD photometer

The study of pulsating white dwarfs requires a special kind of instrument capable of high speed imaging. When studying phenomena that change rapidly, we do not have the luxury of increasing our exposure time to improve the signal. Our instrument must be highly efficient even with short exposures. We also need high timing precision to determine the beginning and duration of each exposure accurately. Most CCD cameras cannot obtain data continuously -- there is a dead time between exposures when the detector is busy reading out the previous image. The time required varies from a few seconds to a few minutes. We need an instrument with essentially zero dead time, so we can record the rapidly variable phenomena without interruption.

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Most observatories do not provide high-speed imaging systems which satisfy these special requirements. We are raising funds to build a high speed CCD imaging instrument, based on a commercial CCD camera, optimized to observe pulsating white dwarfs and other dynamic phenomena. The design is based on an existing system, known as Argos, at McDonald Observatory. The portable nature of this instrument will allow us to send it wherever it is needed for Whole Earth Telescope observations (particularly at Asian longitudes), and eventually duplicate it where funds are available.