Even though we may want to believe that we are very unique as a planet, which is true to some extent, there could be other planets like ours in the endless cosmos. As recently discovered, there was at least one other, with a crust quite similar to our home, but no longer exists. The discovery by University of Warwick astronomers showcase a few vaporised remnants of a planet long gone but were found in the atmospheres of four nearby white dwarf stars. These remnants can help shed light now on what the planet orbiting the stars might have been in its heyday.
The team believes the outer layer of these rocky planets might have been similar to Earth or Mars. The crusts could be studied to understand their chemistry. It is probably one of the oldest star systems discovered so far.The data was collected by the European Space Agency’s Gaia telescope. Over 1,000 white dwarfs were in the collection but one particular had an unusual signal. White dwarfs are stars who have nearly completed their life cycle and are reaching an end.
Using spectroscopy, they analysed the star at different wavelengths of light. By doing so, they were able to detect elements of various physical properties absorbing different colours. The unusual signal finally matched with lithium’s wavelength. One other nearby dwarf was observed to have potassium in its atmosphere. Comparing these two elements’ concentration and considering other elements observed like sodium and calcium, they concluded the ratios matched with Earth.
The estimate is that the planet collapsed, the crust then vaporising and missing with the gaseous outer layers of the star for 2 million years.According to lead author Dr Mark Hollands, these elements are significant as they are mostly found in the crust of a planet.
They assess some 300,000 gigatonnes of rocky debris lyingin the outer layer of the white dwarfs. The amount of crust material is similar in mass to most of our solar system's asteroids,which brings the conclusion thatthese are, in fact, broken off pieces of a planet.The initial stage of formation is similar to star but with time, the chemical composition changes. Hollandsbelieves the debris is suggestive of such transformation.