It would be interesting to view this in terms of the galactic plane. If A/2017 U1 came from Lyra, I think that maybe we "caught up" to it in our rotation around the galactic plane.
That would seem to be the case:
https://en.wikipedia.org/wiki/Milky_Way ... ighborhood wrote:
<<The orbital speed of the Solar System about the center of the Milky Way is approximately 220 km/s. The general direction of the Sun's Galactic motion is towards the star Vega near the constellation of Hercules, at an angle of roughly 60 sky degrees to the direction of the Galactic Center. The Sun's orbit about the Milky Way is expected to be roughly elliptical with the addition of perturbations due to the Galactic spiral arms and non-uniform mass distributions. In addition, the Sun passes through the Galactic plane approximately 2.7 times per orbit. This is very similar to how a simple harmonic oscillator works with no drag force (damping) term.>>
And its resulting trajectory may mean that the Sun has ejected it from the galactic plane.
But perhaps it does not have the velocity to get very far from the plane.
Does someone have a rendering of the encounter in these terms?
The asteroid will be sent out from the Sun at a relative velocity of 26 km/s and at an angle of 36°
below the Galactic plane for a relative vertical velocity = -15 km/s
[= 26 sin(-36°)].
However the Sun is currently moving at a velocity of 220 km/s and at an angle of 18°
above the Galactic plane for an absolute vertical velocity = 67 km/s
[= 220 sin(18°)].
Hence the absolute vertical velocity of the asteroid is just 45 km/s
[= 67 - 15]
: thus less than the Sun and like the Sun confined to the disk.