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Nemesis: Does the Sun Have a 'Companion'?

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  • Citti, Sharon
    http://www.space.com/scienceastronomy/solarsystem/nemesis_010320.html Nemesis: Does the Sun Have a Companion ? By Robert Roy Britt
    Message 1 of 1 , Apr 3, 2001
      Nemesis: Does the Sun Have a 'Companion'?

      By Robert Roy Britt <mailto:rbritt@...>
      Senior Science Writer
      posted: 07:00 am ET
      03 April 2001

      "The trouble with most folks isn't so much their ignorance. It's know'n so
      many things that ain't so." -- A favorite quote of Richard A. Muller, by
      19th century humorist Josh Billings.
      When you think big, as Richard A. Muller does, you're bound to create ideas
      now and then that are so compelling you just can't let go of them -- ideas
      so outlandish that mainstream scientists are equally eager to dismiss them.
      Muller, a physicist at University of California at Berkeley, has had his
      share of big ideas

      If you don't count the restaurant he owned between 1976 and 1982 ("If anyone
      near and dear to you wants to open a restaurant, I can now be hired to talk
      them out of it."), Muller's ideas are generally rooted in solid science and
      genius extrapolation. He's got a gaggle of prestigious awards to prove it,
      with titles that say things like "outstanding" and "highly original."
      But Muller's biggest idea is a real Nemesis. Or so he claims.
      Like a thorn in the side of mainstream researchers, Muller's Nemesis theory
      -- that our Sun
      has a companion star responsible for recurring episodes of wholesale death
      and destruction here on Earth -- seems to reemerge periodically like
      microbes after a mass extinction.
      It's a theory that has many detractors. And it's a theory that has been
      beaten down and left for dead in the minds of most scientists.
      Yet it is a theory that just won't die.
      Nemesis is cautiously supported by a handful of scientists, who often sound
      like ringside rooters eager for a victory but thankful they don't have to
      put the gloves on. Muller meanwhile acknowledges the possibility that the
      whole idea could turn out to be wrong, but he is nonetheless confident that
      Nemesis will be found within 10 years.
      "Give me a million dollars and I'll find it," Muller said in a recent
      telephone interview.
      Brave words for a bold theory that if proven true would shake up everything
      we know about the formation and evolution of our solar system.
      Genesis of Nemesis
      Muller's idea for Nemesis came to him 1983. Luis Alvarez, then an emeritus
      professor of physics at the University of California at Berkeley, and his
      son Walter had recently put forth the theory that a giant impact
      > had wiped out the dinosaurs. (This idea, like so many others that are now
      widely accepted, met with staunch criticism when it was introduced because
      it, too, was not mainstream).
      Around the same time, two other researchers had suggested yet another
      controversial idea, that mass extinctions occurred at regular intervals --
      every 26 million years or so. Scientists immediately folded the ideas into a
      new and breathtaking possibility: Impacts by space rocks were causing
      massive global species destruction every 26 million years.
      Luis Alvarez was Richard Muller's mentor, and he suggested that Muller try
      to debunk the periodicity argument. Pondering this, Muller dreamed up the
      fanciful companion to the Sun as a possible cause, and with Berkeley's Piet
      Hut and Marc Davis of Princeton, worked out the details.
      Muller gave the object the name of the Greek goddess of retribution --
      fitting for a killer star that roamed stealthily beyond the solar system
      flicking comets at dinosaurs.
      In the end, the idea looked surprisingly plausible to Muller and his
      colleagues, and the results of their work were ultimately published in the
      journal Nature in 1984. Muller then wrote a book about Nemesis, and he has
      pursued the companion star, while also doing other research, ever since.
      Tossing comets at us
      Nemesis, as Muller sees it, is a common red dwarf star
      <http://www.space.com/reference/brit/stars/structure_2.html> that would be
      visible through binoculars or a small telescope, if only we knew which of
      some 3,000 stars to look at. These are stars that have been cataloged, but
      their distances are not known.
      Any one of them could be the Death Star, as Nemesis has come to be called by
      Red dwarfs are the most common stars in the galaxy. They are small and
      relatively cool, dimmer than our Sun. The notion of companion stars is also
      exceedingly common -- more than half of all stars are part of such a binary
      system, in which two stars are thought to form out of a single cloud of gas
      and dust.
      Binary stars settle into a gravitational dance around a common point in
      space. The smaller of the two stars does most of the orbiting, whereas the
      larger one is much closer to the center of the dance routine. It's like two
      kids on a seesaw. For the thing to work properly, the heavier child must sit
      closer to the center of the apparatus.
      Muller figures Nemesis' orbit ranges from 1 to 3 light-years away from the
      On its closest approach, the lethal companion would pass through a vast, but
      sparsely populated halo of primitive comets called the Oort Cloud
      tml>, which surrounds our solar system from beyond Neptune's orbit out to
      nearly a light-year away. (The Sun's nearest known star, Proxima Centauri,
      is about 4.25 light-years away).
      During this passage through or near the Oort Cloud, the gravity of Nemesis
      would scatter a furious storm of primordial comets that had been relatively
      undisturbed for 4.5 billion years, since the solar system came into being.
      Dislodged from their once-stable orbits, millions or billions of these
      comets would travel to the inner solar system over millions of years, pulled
      toward the Sun by its gravity. A handful would run into Earth along the way,
      and the flurry of would result in mass extinctions.
      Simple enough. But Nemesis has for years been dogged by a misunderstanding,
      Muller says. Most researchers think the theory was long ago dismissed by
      competing data that claimed its orbit was not possible.
      Far-out idea
      The orbit assumed for Nemesis is an unusual one, Muller admits. No star has
      ever been found to orbit so far from a companion. "And that really bothers
      people," he said. "It makes them think that this is a really far-out idea,
      But computer models developed by Muller and his colleagues predict that such
      an orbit must occur at some point in the evolution of most binary star
      systems. "We just haven't found such systems yet," he said.
      And while Muller appreciates the natural and healthy skepticism of other
      scientists, he figures they are not interested in funding a search because
      they erroneously assume that Nemesis cannot be found.
      Jonathan Tate is the director of Spaceguard U.K
      <http://www.space.com/news/asteroid_british_000915.html>., which lobbies for
      a government response to the threat of asteroids. Tate is among those who
      see no rush to find Nemesis. He would rather see money spent on more
      immediate searches for asteroids closer to Earth that might prove to be
      humanity's undoing in coming decades or centuries.
      As Tate points out, proving that mass extinctions occur every 26 million
      years, regardless of the cause, is only of academic interest: Humans may not
      likely to be around to care, as many researchers don't expect our species to
      last that long. If we do survive, there will likely be plenty of time to
      Questioning periodicity
      Meanwhile, many scientists see little or no credibility to the studies
      alleging periodicity in mass extinctions
      .html>, and hence no need for a Nemesis theory.
      Numerous studies have reported cycles in either impacts or mass extinctions.
      The period between peaks in these studies mostly range from 26 million to 35
      million years. Andrew Glikson of the Australian National University says
      that trying to pin down things that happened so long ago is no simple
      challenge. For one thing, space rocks that land in the ocean leave few
      clues, Glikson points out, and Earth is roughly two-thirds water.
      And Earth
      l> has always had a crust that is on the move. Evidence gets buried,
      destroyed, and folded into oblivion by the same process that creates
      mountains and moves continents.
      "Some of the suggested periodicities are more likely to represent
      statistical artifacts than robust observations," Glikson said.
      David Raup, a University of Chicago paleontologist, made the original
      mass-extinction periodicity argument two decades ago along with colleague J.
      John Sepkoski. The pair studied marine fossil records over a 250
      million-year period that they say showed significant spikes every 26 million
      "To me, the periodicity idea is as well supported as many ideas that have
      been adopted into the conventional wisdom, but the scientific community is
      heartily skeptical," Raup told SPACE.com. "Of the 15 or so re-analyses of
      our data published since the original paper, about half support periodicity
      and half reject it. It's is still very much in the eye of the beholder."
      Muller supports the statistics more emphatically.
      "There is a peculiar pattern in mass extinctions, something that cannot be
      dismissed as a statistical fluctuation," Muller said. "It requires some
      Raup, now retired from active research, would not venture a guess as to when
      or whether Nemesis might be found, but he expressed hope in the idea: "I am
      glad Rich [Muller] is still working on it because it may take a lot of
      effort, and
      The galactic plane, Planet X and black holes
      Other ideas have been put forth to explain the alleged periodicity in mass
      The most widely accepted is the suggestion that the solar system, as it
      revolves around the center of the Milky Way, bobs up and down through the
      plane of the galaxy. This plane is full of gas and dust that never became
      stars, which collectively has a certain amount of gravity that some expect
      might dislodge comets from the Oort Cloud.
      There are doubts, however, about the amount of mass in the galactic plane
      and whether or not the timing coincides with the periodicity of mass
      Others have suggested a dim failed star known as a brown dwarf might be
      lurking in the distant fringes of the solar system. Muller called the
      increasing rate of discovery of brown dwarfs, including one that is just 13
      light-years away
      "extremely discouraging." For if Nemesis were a brown dwarf, it would be
      harder to find.
      Yet another enduring idea is that another large planet lurks beyond Pluto.
      This so-called Planet X would be a gas ball up to five times the size of
      Earth, according to some predictions. Even the possibility of a black hole
      has been raised. Few researchers support these two ideas.
      Evidence from the Moon
      The best evidence for periodic impacts on Earth may ultimately come from the
      Moon. While the Earth's crust has been stretched, squashed and folded
      violently its whole life, the Moon is relatively static, preserving a far
      more accessible geologic record.
      A year ago Muller, Berkeley geologist Paul Renne and then-graduate student
      Timothy Culler found the Moon underwent a flurry of impacts
      between 400 million and 600 million years ago. The active period (which may
      still be going on) presumably affected Earth as well since both bodies are
      in roughly the same spot in the solar system.
      Muller says the sudden increase offers indirect evidence for a sudden change
      in the orbit of Nemesis, which might have been caused by a passing star.
      But the study did not turn up evidence for the 26 million-year periodicity,
      as hoped. Muller says there was not enough data. The study involved 155
      microscopic glass beads formed in the intense heat of lunar impacts and
      later brought to Earth, in a single gram of soil, by the Apollo 14 crew.
      But given that there are "several hundred pounds (kilograms) of [lunar] dust
      and rocks that have not been analyzed," Muller plans another more detailed
      Whether or not he finds evidence for Nemesis in Moon dust, it's clear that
      Muller won't stop looking. He is a man of enduring confidence. But he is
      also a remarkably conservative scientist, quick as anyone to point out that
      there is no proof until there is proof.
      "I'm realistic," he said. "I may be wrong."
      And he recognizes that if the Death Star is not found, the whole idea could
      become a real Nemesis for the big thinker who dreamed it up.
      Click here <http://www.space.com/scienceastronomy/headlines.html> for more
      news and information about asteroids, comets and astrobiology (including
      mass extinctions).

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