Planet/Binary Star Tyche

On Tue, Feb 22, 2011 at 11:47 PM, John Powell wrote:
>
> If this object does exist could it be used to gravity sling us to a nearby star? If Jupiter can gravity fling probes way out there this monster could really give a boost.
(...)

IIRC the maximum speed increase that you are able to get in a gravity
assist is limited not by the planet mass, but by its orbital speed.
The interaction between the spacecraft and the planet is akin to an
elastic collision between an object with negligible mass and a much
bigger one. The crude ASCII illustration below tries to depict that

Before assist (spacecraft is the dot, planet is the big O, speed is
denoted by the length of arrows):

.->
<-O

During assist (spacecraft goes around planet):

-\
O.

After assist:

<--. <-O

It is like when you hit moving truch headfront with a rubber ball:
after the collision the rubber ball would have its launch speed plus
the truck speed. Except of course that the spacecrat and the planet
have no physical contact during the "collision" and are bounded
temporarily only by gravity.

And, since Tyche will move *very* slowly, I don't think that it will
be of much help in that regard.