Weathering the storm or rising from the ashes? The circumbinary planets of NN Serpentis
NN Serpentis has everything: a white dwarf + main sequence binary system that is believed to contain two planets and, now, a disc of debris.
One Star, Two Star, Brown Star, Blue Star
Enter the observed oddball: a subdwarf B (sdB) star. These unexpected stars are fusing helium into carbon and oxygen in their core and only have a thin hydrogen envelope. So, where did the hydrogen go?
Are We Seeing Common Envelopes After All?
Scientists propose way in which we could observe the envelope being ejected from binaries going through a common envelope phase. And their predictions match a class of objects which have already been observed.
How common is Common Envelope evolution?
It’s a fact of the universe that most stars are members of a binary system. However, our knowledge of stellar evolution has most thoroughly treated the case of a single, isolated star evolving according to its own schedule, dictated by the well-understood equations of stellar structure. What happens when the binary stars have tight enough orbits to influence each other?