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A New Zealand-based astronomy organisation has discovered a tiny star with its own planet slightly larger than Earth, 3000 light years away.
The discovery was made by the Japan-New Zealand Microlensing Observations in Astrophysics (MOA) collaboration, which said the star - the planet's equivalent of the sun - was the smallest on record to have an orbiting planet.
It has a mass about 6 per cent of our sun and is so small it may be incapable of producing energy by nuclear reactions. The planet is slightly larger than Earth, has a smaller orbital radius, similar to Venus, and, due to the small size of the star, is likely to be colder than Pluto, according to the MOA.
It said the location favoured the presence of a massive atmosphere underlain by a deep ocean on its surface.
Interior heating by radioactive decay was likely to be sufficient heat to keep that ocean at liquid temperature, yielding a possible habitat for life.
The discovery was made through a new Japanese-funded MOA telescope at Mt John Observatory in Canterbury, the world's largest dedicated to gravitational microlensing.
That process takes advantage of the fact that, as Einstein predicted, a star warps the space surrounding it, enabling the star to act like a giant magnifying glass.
The telescope is equipped with a state-of-the-art imaging camera capable of imaging an area of sky 13 times the size of the full moon in a single exposure.
A paper describing the discovery has been accepted for publication in the Astrophysical Journal and information about it is being presented today at the American Astronomical Society annual meeting in St Louis.
MOA collaboration member David Bennett, of Notre Dame University in the United States, said the discovery indicated that even the lowest mass stars could host planets.
"Planets have not previously been found orbiting stars with masses less than about 20 per cent of that of the sun, but this finding suggests that we can expect to find other very low-mass stars to have planets with a mass similar to that of the Earth, Dr Bennett said.
- NZPA
