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domingo, 8 de maio de 2011

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Astronomy Without A Telescope – Planet Spotting

by Steve Nerlich on May 8, 2011

The Extrasolar Planets Encyclopedia counted 548 confirmed extrasolar planets at 6 May 2011, while the NASA Star and Exoplanet Database (updated weekly) was today reporting 535. These are confirmed findings and the counts will significantly increase as more candidate exoplanets are assessed. For example, there were the 1,235 candidates announced by the Kepler mission in February, including 54 that may be in a habitable zone.

So what techniques are brought to bear to come up with these findings?

Pulsar timing – A pulsar is a neutron star with a polar jet roughly aligned with Earth. As the star spins and a jet comes into the line of sight of Earth, we detect an extremely regular pulse of light. Indeed, it is so regular that a slight wobble in the star’s motion, due to it possessing planets, is detectable.

The first extrasolar planets (i.e. exoplanets) were found in this way, actually three of them, around the pulsar PSR B1257+12 in 1992. Of course, this technique is only useful for finding planets around pulsars, none of which could be considered habitable – at least by current definitions – and, in all, only 4 such pulsar planets have been confirmed to date.

To look for planets around main sequence stars, we have…

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