How planets can escape ultimate fiery oblivion with the power of explosions

The media is only interested in an exo-planet these days if it’s passingly similar to Earth, but some of the most fascinating worlds are interesting because they’re not Earth analogues.

Take the BD+48 740 system, the star  is a red giant that has already expanded sufficiently to have eaten most of the inner planets that may at one time have circled it. But it has one known world; the romantically named BD+48 740b which is a gas giant 1.6 times the size of Jupiter. There’s two strange things about this system:

1. A unusually high concentration of lithium in the star’s atmosphere.

2. The planet has an unusually high level of eccentricity to it’s orbit. In it’s super-heated Summer it gets closer to its sun than Venus is to ours, and in its winter it is much further out than Mars is in our system.

Our assumption is that at one stage, this system had an inner planet, but as BD+48 740 expanded it got pushed into the star, the crash caused an explosion that pushed BD+48 740b out of the way of the sun and into it’s current eccentric orbit. This kind of explosion would also have also generated the Lithium in the star’s atmosphere.

This is exciting, because it means that there is another way for a planet to end it’s life. We always thought that there were basically two things that can happen as a star like ours expands: either it expands quickly and pulls many of it’s worlds into it. Or it expands slowly and the extra energy it emits slowly pushes the planets away from it until they eventually freeze. BD+48 740b seems to have found a kind of a happy medium between the two.

Which leads me to wonder, could we do this? In five billion years time maybe we’ll decide we want to save the Earth from fiery oblivion. As the process of getting sucked into the sun takes thousands of years, we won’t necessarily have time to reverse that trend in the lifespan of a single civilisation. But it might be possible to push Venus in ahead of us to save our own world from destruction. 

It would, at least, make an interesting premise for a science fiction story.


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