German astronomers have discovered a strange new type of star covered in the by-product of helium burning. The stars might have been formed by a rare stellar merger event. The study has been published in Monthly Notices of the Royal Astronomical Society.
Normal stars have surfaces composed of hydrogen and helium. The stars their surfaces covered with carbon and oxygen. The ashes of helium burning are an exotic composition for a star. The situation becomes more puzzling as the new stars have temperatures. It indicated that they are still burning helium in their cores. This is a property seen in more evolved stars than those observed by scientists.
Scientists explained a possible explanation for their formation. Dwarfs are the remnants of larger stars. It has exhausted their nuclear fuel. These are typically very small and dense.
Stellar mergers happen between white dwarfs in close binary systems because of the shrinking of the orbit. It has been caused by the emission of gravitational waves. No current stellar evolutionary models can fully explain the newly discovered stars. Scientists need refined models to assess whether these mergers can actually happen.
These models could not only help the team to better understand these stars. But these can provide deeper insight into the late evolution of binary systems. It can provide insights about how their stars exchange mass as they evolve. Astronomers will develop more refined models for the evolution of binary stars. Till then the origin of the helium covered stars will be up for debate.