New Scientific Discoveries, Part Vier

[rjshae]

A Stellar Flyby Jumbled Up the Outer Solar System (Universe Today)

Quote

An ancient passerby may have visited the Sun and inadvertently helped shape the Solar System into what it is today. It happened billions of years ago when a stellar drifter came to within 110 astronomical units (AU) of our Sun. The effects were long-lasting and we can see evidence of the visitor’s fleeting encounter throughout the Solar System.

It does explain a lot. I wonder if it does better than the 9th planet hypothesis that was raised a few years ago to explain the orbits of TNOs?

Here's the original paper:

Trajectory of the stellar flyby that shaped the outer Solar System (Nature)

If they could find a captured object from the other star, that would be solid evidence.

[Zoraptor]

That explanation has been around a while as an alternative to PlanetX (as was, definitely not dead) or Nemesis (red/ brown dwarf solar companion; would also explain apparent mass extinction periodicity) hypotheses. Those both work theoretically, but neither has been found and for Nemesis at least that's getting to be a real problem. The attraction of something extra solar doing it is that you wouldn't expect to find anything, just its effects.

[rjshae]

20 minutes ago, Zoraptor said:

That explanation has been around a while as an alternative to PlanetX (as was, definitely not dead) or Nemesis (red/ brown dwarf solar companion; would also explain apparent mass extinction periodicity) hypotheses. Those both work theoretically, but neither has been found and for Nemesis at least that's getting to be a real problem. The attraction of something extra solar doing it is that you wouldn't expect to find anything, just its effects.

I suppose the difference this time is the application of numerous computer simulations that are used to reproduce essentially all of the observed properties of TNOs. A K-type star is a significant interloper that would have been even more severely disrupted by the more massive Sun, possibly losing members to the Solar System. I wonder if this happened while the Sun was still part of its origin stellar association?

[Zoraptor]

IIRC the expectation is that less massive stars have planets orbiting proportionately closer, eg a lot of red dwarfs have detected planets with years of only a few Earth days and are closer to their sun than Mercury is to ours, so the disruption for a smaller intruder is not as disproportionate as might be expected. Unless the difference is really large and the passage very close. I'd suspect it being part of the same stellar association is unlikely* solely on principle, but that's about as far from a solid conclusion as it's possible to get.

It'd certainly be tempting to think that the spate of big planetary scale collisions that happened ~4bn years ago were caused by an intruder. That's whatever knocked Uranus over onto its side, Theia's putative collision with Earth and some people are pretty confident Venus had a large collision as well to explain why its rotation is odd- and its greenhouse effect/ weird volcanism; with it at one point even having a roughly Lunar equivalent moon. They may well have all been 'natural', though the explanations are not incompatible with an intruder, ie something perturbed Theia but it doesn't have to be Venus/ Jupiter doing it and if it were them they may have themselves been perturbed first. It's all complicated too by planetary orbits changing 'naturally' over astronomical timescales...

*kind of by definition stars in stellar associations tend to drift apart rather than together over astronomical timespans.

[rjshae]

3 hours ago, Zoraptor said:

IIRC the expectation is that less massive stars have planets orbiting proportionately closer, eg a lot of red dwarfs have detected planets with years of only a few Earth days and are closer to their sun than Mercury is to ours, so the disruption for a smaller intruder is not as disproportionate as might be expected. Unless the difference is really large and the passage very close. I'd suspect it being part of the same stellar association is unlikely* solely on principle, but that's about as far from a solid conclusion as it's possible to get.

That is perhaps true for M-dwarfs (or a selection bias effect?), but this hypothesized star has 80% of a solar mass. A comparable star is Epsilon Eridani, which has a jovian planet and an rich asteroid system extending out to 75 AU. There may be other planets around Epsilon Eridani, but the star is active so radial velocity signals get drowned out. Planets in wider orbits may not show up because of the duration of the orbit and/or stellar activity. We need better technology.

Edited September 19 by rjshae

[Gfted1]

US scientists teleport energy, store it using quantum computers (interestingengineering.com)