[meteorite-list] Nemesis-The Death Star

From: Richard Kowalski <damoclid_at_meteoritecentral.com>
Date: Sun, 14 Mar 2010 22:10:35 -0700 (PDT)
Message-ID: <933048.11935.qm_at_web113612.mail.gq1.yahoo.com>

--- On Sun, 3/14/10, Sterling K. Webb <sterling_k_webb at sbcglobal.net> wrote:


> Hi, All.
>
> Despite the Nibiru Nuttery (and the clips of Muller in
> it),
> there is a continuing misunderstanding of the Nemesis
> hypothesis as regards the proposed orbit, its stability,
> and lifetime.


Agreed

An important point that hasn't been mentioned since this thread began is that the Nemesis hypothesis was created to explain an apparent periodicity in the observed extinctions over the past half a billion years. This periodicity is 26 million years. Unfortunately, this is the mean, and doesn't occur like "clockwork" which is a requisite for an orbiting star. Some extinction happen approximately on the 26my timetable, but most do not. Many are at least a million years off and one is as far off as 11 million years!

A star is such an orbit is going to pass through the Oort Cloud much more precisely than this. An 11 million year offset is completely unreasonable.

As I mentioned in my earlier post, a 26my period orbit extends into interstellar space and is unstable. Even if the object hasn't been orbiting the Sun for the last 4.5by, but only 500 million, as Sterling mentions, it would still have been ejected from its orbit long before now.

Alan Harris, who was at JPL for most of his career studying the minor bodies of our Solar System, posted on MPML this morning,

"This has actually been studied in great detail, and we have a real example
in nature: the Oort comet cloud. The typical dimension given for the Oort
Cloud is around 10,000 AU, with orbit periods in the one million year
range. Dynamical studies demonstrate that orbits in that range are the
ones close enough to instability to be perturbed out of the inner planetary
system 4.5 GY ago, and back in at random times since then, but not so far
out as to be stripped away by passing stars, the galactic tide, and so
forth. A 26 million year orbit period corresponds to an orbit about ten
times bigger, around 100,000 AU, as you calculate, and is just too
distant. Such a distant orbit is unstable and subject to being stripped
away in only an orbit or two of the sun. That's been well shown with Monte
Carlo integrations simulating the origin and evolution of the Oort Cloud."

If Nemesis exists, or existed, it would only orbit the Sun for 50 million years or so... Even if we double the reasonable lifetime to ~100 million years, or four orbits, the hypothesis fails to account for the supposed periodicity in the extinctions over the last 500 million years.

In my opinion, Nemesis is hypothesis who's time came and went over a decade ago.


Richard




      
Received on Mon 15 Mar 2010 01:10:35 AM PDT