Scientists have recently discovered the smallest white dwarf star ever observed, which is about the size of the moon. This remarkable finding challenges previous notions about the smallest possible size for such objects.

White dwarf stars are remnants of ancient, dying stars, with masses similar to that of the sun but squeezed into a fraction of the size. Despite their small size, white dwarfs are incredibly dense, with a teaspoon of material from one weighing approximately as much as a car. Until now, it was believed that these stars could not be smaller than about 0.034 times the mass of the sun, known as the Chandrasekhar limit.

However, astronomers from the University of Warwick in the United Kingdom have discovered a white dwarf star named WDJ0551+4135 that is just about the same size as the moon, with a radius of about 2,500 kilometers. This star is located about 150 light-years away from Earth and is part of a binary star system, meaning it orbits closely with another star.

The researchers were able to observe WDJ0551+4135 by using a technique called gravitational microlensing. This method involves measuring the bending of light from a background star when a foreground object, such as a white dwarf, passes in front of it.

By carefully analyzing the data gathered from this phenomenon, the scientists were able to determine the size of the white dwarf.

The discovery of this moon-sized white dwarf challenges current theories about the minimum size constraint for such stars. It suggests that they can be smaller than previously believed, possibly even as small as the mass of Jupiter. This finding has important implications for our understanding of the evolution and fate of white dwarf stars.

The study of white dwarfs is essential for gaining insight into the future of our own star, the sun. As stars age and exhaust their nuclear fuel, they expand into red giants before shedding their outer layers and leaving behind a white dwarf core.

Understanding the size range in which white dwarfs can exist will help scientists predict the future of the sun, as well as other stars in the universe.

In conclusion, researchers have discovered a white dwarf star, WDJ0551+4135, that is the smallest ever observed, with a similar size to the moon. This challenges the previous belief that white dwarfs could not be smaller than a certain limit. By studying white dwarfs, scientists gain valuable knowledge about the evolution of stars, including our own sun.