Chicxulub's outer origin

10-15 years ago I recall breathless comments about an asteroid breakup 160 million years before that, that its fragments did the Chicxulub in between. Those comments dropped by the wayside, maybe because that asteroid-cluster got ruled out. Here we go again: Simone Marchi, William Bottke, David Nesvorný... some others, as 'splained to us by one Ailsa Harvey. This argument looks more plausible, though.

What we know about the impactor itself is that it had iridium... but not as much iridium as (say) a Psyche 16, nor a Vesta. The impactor was assumed of a near Earth origin because, well, it did hit Earth, after all. Marchi's simulations involve "thermal forces"- so I gather from the Harvey summary. Whatever that means, it allows outer (semimajor axis 3.4 AU) asteroids to cross into inner orbits, like Earth's 1 AU. The further out (originally), the less metallic. REALLY further out you get those iceball comets but I'm pretty sure comets have been ruled out for this one.

I must question that Harvey knows what she's talking about, herself. Asteroids don't get pulled from orbit. To me that means something like Oumuamua (or Voyager), heading into interstellar space. Asteroids might however get their orbit altered - usually keeping about the same semimajor, but getting a different eccentricity. Such orbits may, if eccentric enough, intersect with some other body's orbit.

I'd point out that when a further asteroid gets too close to Jupiter (5.2 AU), Jupiter elongates that orbit. A more-elliptic trajectory, you should know from Kepler, has a lower perihelion. When that perihelion dips below 1 AU... well, that's an Earth-crossing orbit, ain't it.

Pity I have to wait until November to read the actual article.