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What is the context of this research?

Age is one of the most fundamental of all properties,whether for a person, the Grand Canyon, the Earth, or the Universe. Without age, all other properties, such as mass or size or color, are without context. Age can also demand physical explanation. For example, by the late 1800's, physicists knew the Sun was at least 300 million years old. This already ruled out all then-known mechanisms for powering the Sun. We now know the age of the Sun precisely (4.567 billion years) as well as the age of the Universe (13.798 ± 0.037 billion years). Yet our knowledge of the age of the Galaxy is much less precise, with age estimates of 11.5 to 13.5 billion years. In order to understand how long it took our Galaxy to form and what the most important physics controlling that formation was, we need to precisely and accurately know the age of the Galaxy.

What is the significance of this project?

Our project will develop and demonstrate a new technique for deriving the age of the Galaxy. For our ultimate goal of an accurate and precise age of the Galaxy, two other developments are required. First, because the ages of white dwarfs are more fully revealed by their total luminosity than by their surface temperature, astronomers need accurate distances to thousands of these stars. This is currently happening with ESA's Gaia satellite and these data will be available to us in approximately two years. Second, the theory that governs the details of how white dwarfs cool as they age needs testing and refinement. Our technique, once demonstrated and then applied to the Gaia data, may discover inconsistencies in white dwarf models and will provide the best age for the Galaxy. It will also spur on new developments in white dwarf theory.

What are the goals of the project?

Our goal is to derive the most accurate and most precise age for our galaxy, the Milky Way. We do this by studying white dwarf stars in Galactic halo, which is the oldest component of the Galaxy. White dwarfs are particularly suitable for this study because their age is largely revealed by their surface temperature. We have already measured the surface temperature for a handful of halo white dwarfs and this study will derive their ages with the help of a new statistical technique that we have developed. Our novel technique allows us to pool data from multiple white dwarf stars to derive an age for the formation of the Galaxy and test the duration of that formation period.