Wednesday, December 01, 2010

The Dwarf Star Tyche Might Be Out There

Imagine yourself flying away from the surface of the Sun.  The first four rocky planets pass by quickly enough.  However, the gaps between gas giants are bigger than the Sun to Mars and only progressively grow larger.  When one passes by Neptune one will eventually go through the monsterly thick Kuiper belt full of asteroids.  Once one is past that they will eventually encounter the Oort cloud, home of comets.  It is as "close" as 11 lights day from the Sun (Pluto is about 5.5 light hours away from the Sun) and ends about 1 light year away from the Sun.

The Oort cloud is much, much more larger than the solar system.  Image from Wikipedia.
Traditional understanding of nearby space has all but a rare few comets staying in the Oort cloud.  However, since the 1980s some astronomers noticed a casual cycle between comets entering the solar system and mass extinctions.  Some theorized that a dwarf star, a dying star that produces little light but has a powerful gravitational sway, in the Oort cloud was throwing life-destroying comets towards Earth.  The theoritical dwarf was named after the life killing goddess, Nemesis.

Scientific models were created to see if a dwarf star was throwing comets towards Earth.  It now seems unlikely that a dwarf planet would be responsible for mass extinctions due to the timing of comets entering the solar system.  However, further research and models suggest up to twenty percent visible from Earth were sent by a dwarf star.  The possible dwarf is now being called by Tyche, named after a sister of Nemesis and not a vengeful goddess, by some astronmers.

It could be out there.  Nemesis/Tyche in the midst of the Oort cloud.  The Sun is the small light in the middle of the image.  Image from Wikipedia

If there is a Tyche out there then it would be the closest star to the Earth (it would be one-fourth the distance between Earth and the current closest star: Proxima Centauri).

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