Stellar Data
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Type of Star: Spectral Class: Distance: Luminosity: Mass: Surface Temperature: Main Sequence Lifetime: |
Yellow Dwarf G8V 11,9 Lightyears 0,45 L 0,8 Solar Masses 5.500 K 12 Billion Years |
The Environment of Tau Ceti
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Habitable Zone: Zone of Stable Planetary Orbits: Known Companions: |
0,6 - 0,9 AU Unlimited None |
Comparison to Solar System
Tau Ceti |
Sun
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As soon as the next century, humans might explore Tau Ceti. |
In all the great oceans of emptiness, stars of type G are the best candidates to look for life - these are stars like our own sun. They are of moderate, but comfortable brightness and remain stable for about 10 billion years - sufficient time for complex life forms to evolve. Tau Ceti is such a G-type, sunlike star, devoid of stellar companions and close enough for detailed studies. |
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Though Tau Ceti has about half the sun's luminosity, its habitable zone still comprises about one third AU - this is wide enough that a terran planet may have formed there. But we know from other stars that giant gas planets are common, and they are often very close to their parent star. So if Tau Ceti happens to have a system of planets, a gas giant may orbit within the habitable zone, leaving no space for an additional terrestrial planet. But this giant planet may have moons, possibly of Earth's size, where life may get a start. |
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Climate on such a large moon of Tau Ceti b would not be substantially different from our own. Depending on the parent planet's orbital radius, this world might see the whole range of conditions from the greenhouse of the Mesozoic to the great ice ages of the Pleistocene. Advanced forms of life, even sentient beings, are not excluded. |
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In July 2004, British astronomers around Dr. Jane Greaves announced the discovery of a disk of very cold dust in orbit around the star. According to their interpretation, this dust is produced by collisions between larger comets and asteroids that break them down into ever smaller pieces. Tau Ceti may contain ten times as much material in the form of asteroids and comets than our own solar system, which would crash into any planets at uncomfortable high rates. The environment of Tau Ceti may be more hostile to life than we have imagined. Is a quiet and stable planet like Earth really such a rare phenomenon, as Peter Ward and Donald Brownlee proclaimed? |
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Heidmann, J. (1994): Bioastronomie WILLIAMS D., KASTING J. & WADE R., 1997: Habitable moons around extrasolar giant planets. Nature, 385, 234 |
