And, critically, your complete orbit is throughout the orbit of the smaller companion star. The gravitational forces of a good binary ought to stop any planets from forming inside this area early within the system’s historical past. So, how did the planet find yourself in such an uncommon configuration?
A confused previous
The truth that one of many stars current in ν Octantis is a white dwarf suggests some potential explanations. White dwarfs are fashioned by Solar-like stars which have superior by means of a late helium-burning interval that causes them to swell significantly, leaving the outer floor of the star weakly certain to the remainder of its mass. On the distances inside ν Octantis, that will enable appreciable materials to be drawn off the outer companion and pulled onto the floor of what is now the central star. The online result’s a substantial mass switch.
This might have performed one in all two issues to put a planet within the inside of the system. One is that the transferred materials is not prone to make a right away dive onto the floor of the close by star. If the method is gradual sufficient, it may have produced a planet-forming disk for a short interval—lengthy sufficient to provide a planet on the inside of the system.
Alternatively, if there have been planets orbiting exterior to each stars, the change within the mass distribution of the system may have doubtlessly destabilized their orbits. That is perhaps sufficient to trigger interactions among the many planets to ship one in all them spiraling inward, the place it was finally captured within the steady retrograde orbit we now discover it.
Both case, the authors emphasize, needs to be fairly uncommon, which means we’re unlikely to have imaged many different methods like this at this stage of our examine of exoplanets. They do level to a different tight binary, HD 59686, that seems to have a planet in a retrograde orbit. However, as with ν Octantis, the info is not clear sufficient to rule out various configurations but. So, as soon as once more, extra information is required.
Nature, 2025. DOI: 10.1038/s41586-025-09006-x (About DOIs).
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