Hi Richard and List,
Thats a nice link you provided. Here is a video on you tube about
Nemesis-The Death Star. Check it out its a good source on the death
star hypothesis.
http://www.youtube.com/watch?v=Qa1jp4EiOcA
Shawn Alan
[meteorite-list] Nemesis-The Death Star
Richard Kowalski damoclid at yahoo.com
Sat Mar 13 23:33:23 EST 2010
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Hi Alan,
there has been several posts on the Minor Planet Mailing List
(http://tech.groups.yahoo.com/group/mpml/) today about this.
A 26 million year orbit essentially extends into interstellar space
and any object in such an orbit would rapidly be perturbed from it's
orbit around the Sun. I his post today, Bill Gray, author of some
excellent software including the freeware "Findorb", stated
"...It presumably has an
extremely high eccentricity, so the apohelion must be about 2.5
light-years out, roughly at the point where stars will pass by
on a reasonably regular basis. The orbit is about as stable as
a pencil balanced on its point in a hurricane."
IOW, it is highly unlikely any such object exists and if it did, it
wouldn't remain in orbit for very long, astronomically speaking...
That doesn't mean it doesn't, just don't hold your breath waiting for
WISE to find it...
--
Richard Kowalski
Full Moon Photography
IMCA #1081
--- On Sat, 3/13/10, Shawn Alan <photophlow at yahoo.com> wrote:
From: Shawn Alan <photophlow at yahoo.com>
Subject: [meteorite-list] Nemesis-The Death Star
To: meteorite-list at meteoritecentral.com
Date: Saturday, March 13, 2010, 9:04 PM
Hello List,
Last week a good topic was brought about the probability of
patterns with the places and amount of meteorites coming in
contact with Earth. I am not sure if this hypothesis was
suggested but I came across the Nemesis Hypothetical red
dwarf star hypotheses in Rocks from Space by O.Richard
Norton and Wikipedia. Here is what is on Wikipedia…..
Nemesis is a hypothetical red dwarf star or brown dwarf,
orbiting the Sun at a distance of about 50,000 to 100,000
AU, somewhat beyond the Oort cloud. This star was originally
postulated to exist as part of a hypothesis to explain a
perceived cycle of mass extinctions in the geological
record, which seem to occur once every 26 million years or
so.
Claimed periodicity of mass extinctions
In 1984, paleontologists David Raup and Jack Sepkoski
published a paper claiming that they had identified a
statistical periodicity in extinction rates over the last
250 million years using various forms of time series
analysis.[1] They focused on the extinction intensity of
fossil families of marine vertebrates, invertebrates, and
protozoans, identifying 12 extinction events over the time
period in question. The average time interval between
extinction events was determined as 26 million years. At the
time, two of the identified extinction events
(Cretaceous-Tertiary and Late Eocene) could be shown to
coincide with large impact events. Although Raup and
Sepkoski could not identify the cause of their supposed
periodicity, they suggested that there might be a
non-terrestrial connection. The challenge to propose a
mechanism was quickly addressed by several teams of
astronomers.
Development of the Nemesis hypotheses
Two teams of astronomers, Whitmire and Jackson, and Davis,
Hut, and Muller, independently published similar hypotheses
to explain Raup and Sepkoski's extinction periodicity in the
same issue of the journal Nature.[2][3] This hypothesis
proposes that the sun may have an as yet undetected
companion star in a highly elliptical orbit that
periodically disturbs comets in the Oort cloud, causing a
large increase in the number of comets visiting the inner
solar system with a consequential increase in impact events
on Earth. This became known as the Nemesis (or, more
colorfully, Death Star) hypothesis.
If it does exist, the exact nature of Nemesis is uncertain.
Richard A. Muller suggests that the most likely object is a
red dwarf with magnitude between 7 and 12,[4] while Daniel
P. Whitmire and Albert A. Jackson argue for a brown dwarf.
If a red dwarf, it would undoubtedly already exist in star
catalogs, but its true nature would only be detectable by
measuring its parallax; due to orbiting the Sun it would
have a very low proper motion and would escape detection by
proper motion surveys that have found stars like the 9th
magnitude Barnard's star.
The last major extinction event was about 5 million years
ago, so Muller posits that Nemesis is likely 1 to 1.5 light
years away at present, and even has ideas of what area of
the sky it might be in (supported by Yarris, 1987), near
Hydra, based on a hypothetical orbit derived from original
apogees of a number of atypical long-period comets that
describe an orbital arc meeting the specifications of
Muller's hypothesis.
Looking for Nemesis
If Nemesis exists, then it may be detected by the planned
Pan-STARRS or LSST astronomical surveys.
In particular, if Nemesis is a brown dwarf, then the WISE
mission should be able to find it. The hypothesis that the
Nemesis star is a brown dwarf was proposed by Dan Whitmire
and Albert A. Jackson, IV.[5]
Also, if you own a copy of Rocks from Space I would look
towards the back of the book and read up on Nemesis. It is a
very good hypothesis and makes since that this could be
taking place in our solar system.
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