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Telescope network turns to EMCCD camera in hunt for Earth-like exoplanets

The Stellar Observation Network Group (SONG), following a study led by Kennet Harpsoe from the Centre for Star and Planet Formation in Copenhagen, is using an EMCCD camera from Andor to search for Earth-like exoplanets.

SONG is an initiative of astronomers from the Niels Bohr Institute and Aarhus University and is building a global network of robotic one-metre telescopes to observe any star around the clock, since the telescopes succeed each other as the star passes overhead.

Although EMCCD's have different sources of noise compared to conventional CCDs, Harpsoe has demonstrated that new methods for photometric reduction can be developed to ensure that the iXon 897 EMCCD from Andor is the ideal detector for high frame rate applications where resolution is vital.

‘Rare gravitational microlensing events, where a star's gravitational field deviates the light from a background source, enable us to detect objects as small as an Earth-like exoplanet,’ said Kennet Harpsoe of SONG. ‘However, the likelihood that two random stars become sufficiently aligned is vanishingly small and almost all microlensing events occur towards the centre of the Galaxy in the densest fields in the night sky. Consequently, the stars appear as a continuum, where only the brightest stars can be distinguished as individual stars.

‘The significant improvement in resolution, fast readout times and negligible readout noise brought about by the Andor EMCCD camera is a prerequisite for successfully observing gravitational microlensing events. Our work demonstrates that SONG's quest to find small, Earth-like exoplanets capable of supporting life through our global network of robotic telescopes can go forward with confidence.’

In the 17 years since the discovery of the first planet in orbit around another star, more than 600 exoplanets have been detected. However, almost all are so-called Hot Jupiters or Roaster Planets, giant planets orbiting close to their parent stars with very high surface temperatures, simply because they are the easiest to visualise. To date, telescopic detection of small Earth-like objects capable of supporting life has remained virtually impossible.


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