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Millions of new Comets Coming - Part 2 of 2

Hello Bernd,

You are a welcome sight in restoring order in our little corner of the
universe.

As we are just beginning to study stars in a binary system, and as there is
evidence, weak though it may currently appear, that our own sun may itself
be a companion star, there are several factors I'd like to understand.

Bernd kindly wrote the following two sentences:

"The rather weak evidence for
periodicities of some 20 to 30 million years in the fossil record of
mass extinctions has even been used to suggest the existence of a
companion star orbiting the Sun at a distance of a few tens of thousands
of AU. "

and.....

"The Oort cloud which contains some 10^12 to 10^13 comets
extends out to about 1.5 ly (0.5pc, 100,000 AU), so a star would need to
approach the Solar System to within that distance before many cometary
orbits would be disturbed."

According to my calculations, 1 light year would equal about 70,000AU,
rounded up.  It seems to me that, while a star approaching from outside the
Oort cloud, could have the counter-intuitive effect of 'repelling', that is
pushing comets inward (as in the shepherding moon effect), that it would be
equally, if not more,  logical that a companion star revolving inside the
Oort cloud at a distance of  70,000AU or less, would pull comets inward
toward Earth and account for the periodicity of extinctions.

What is the exact range of position in AU's that Nemesis has been theorized
to occupy?   And why have we not seen it??   In applying range of distance
to proximity of binary stars to their companions, am I correct in assuming
the size of the stars would be the key factor in determining this?

Best regards,
Julia



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