You can't have an oort cloud comet hit the Earth at 160 km/s. The absolute fastest that anything falling from an orbit bound to our sun (oort cloud comets being very lightly bound) in the outer solar system can hit the Earth is about (((1+ square root of 2)* the Earth's orbital velocity)^2 + Earth's escape velocity^2)^0.5, or about 73 kilometers per second. This is if it falls from basically infinity (oort cloud distances) to the Earth's distance from the sun, reaching solar escape velocity at our altitude (square root of two times our orbital velocity) and then hits us head on in our orbit. The true velocity would vary between 73 km/s and 16 km/s with most values somewhere in the middle. Those measured faster velocities came from comets that were falling closer than one AU away from their parent stars.
Granted that's only a factor of 8 in maximum available energy per unit mass (difference between 73 squared and 160+earth's orbital velocity + dealing with earth's escape velocity as above). Still, this has almost certainly happened before over the Earth's history, many times, on ten to low tens of megayear timescales. Slightly less extreme events would be much more common - events with one tenth the calculated perturbation parameter would be ten times as frequent and come every 1-3 million years. EDIT stellar mass lessens this argument a little, this star is relatively large and thus its perturbation parameter is larger than the average stellar pass at this distance
yes, i have no idea how a 25 my old star and disk could have rocks in-falling at that speed, seems like even a gas giant wouldn't do that, as Jupiter only gives you 30kps,(outside Roche limit).
Still, if Planet 9 is real, and starts slinging stuff around out there, there may be some un-bound bodies in the system soon enough....
I was tracking these runaway stars for a SF story i had in mind, but this is the closest one i have heard of yet, and the ArXiv paper describes one that also passed thru 2.5 mya.
Gliese 710 will pass the Sun even closer
Close approach parameters recalculated based on the first Gaia data release
http://www.aanda.org/articles/aa/abs/2016/11/aa29835-16/aa29835-16.html
Close encounters of the stellar kind
https://arxiv.org/abs/1412.3648
tl:dr article
http://www.businessinsider.com/star-hurting-towards-solar-system-2016-12\
"Gliese 710 is about half the size of our sun, and it is set to reach Earth in 1.35 million years, according to a paper published in the journal Astronomy & Astrophysics in November.
And when it arrives, the star could end up a mere 77 light-days away from Earth — one light-day being the equivalent of how far light travels in one day, which is about 26 billion kilometers, the researchers worked out.
As far as we know, Gliese 710 isn't set to collide directly with Earth, but it wil be passing through the Oort Cloud, a shell of trillions of icy objects at the furthest reaches of our solar system. "
Seems like a great opportunity to send out some interstellar probes. The star will be trailing lots of ISM, free gas that would help bring a ramjet up to speed, and track till you could curve towards another destination. Likewise, a solar sail probe launched out in front of it by laser could "hitchhike" , and get some deep space ISM , and EM measurements.
Can we think of some other opportunities that this might present ? If we are past the filter by then, then we will already prob have samples of the Oort objects, but looks like they will be delivering then...