Three Neptune-mass planets

I've mentioned before that spectrographs can provide some amazing results despite the lack of pretty pictures. Now, a team of astronomers from France, Switzerland and Portugal have used the HARPS spectrograph on the European Southern Observatory's 3.6-m telescope at La Silla to find a solar system containing three Neptune mass planets. The planets orbit the star HD 69830. This star is slightly less massive than the Sun and is only (only!) about 41 light years away in the direction of the constellation Puppis.

The measurements don't directly observe the planets but actually infer their presence by watching how HD 69830 is slightly tugged around by them as they orbit. From the measurements, it was possible to say that the orbital periods - the time taken to orbit the star once - are 8.7, 31.6 and 197 days. Although we know about lots of planets outside the Solar System these days, this new system is notable because the planet with the longest orbital period is actually quite close to the region known as the habitable zone. This is the region where the temperature is between the melting point and boiling point of water and is the most condusive to life as we know it. Although that doesn't mean that this new planet has life on it, it is a step closer to finding Earth-like planets that might.

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Posted in astro blog by Stuart on Thursday 18th May 2006 (06:55 UTC) | Permalink
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