Astronomers discovered 40 examples of unusually small red giants. Stars in this phase are running out of hydrogen in their cores and inflate their outer layers. Astronomers led by Yaguang Li propose that the small red giants come from binary systems, and their matter is being stolen by a smaller star.
Binary stars are common. And they steal each other's mass from time to time. In this case it is a pair consisting of white dwarf and a red giant. The white dwarf is a later phase of stellar evolution, these objects are collapsed cores of the progenitor star. Astronomers now propose that the white dwarfs in these systems steal away the upper layers of the red giants. Making them smaller, lighter and sometimes even less luminous. If the transfer is significant and the mass of the white dwarfs rises above 1.44 solar masses, it will explode as a supernova. Maybe the dwarfs in these 40 systems are getting closer to that limit, there is no way to know. But we will see them through our telescopes, as magnificent explosions of light.
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