The search for other Earths

AN ARTIST’S IMPRESSION OF AN EXOPLANET WITH MOONS, ORBITING THE STAR HD70642. CREDIT: DAVID A. HARDY, ASTROART.ORG © PPARC.
AN ARTIST’S IMPRESSION OF AN EXOPLANET WITH MOONS, ORBITING THE STAR HD70642. CREDIT: DAVID A. HARDY, ASTROART.ORG © PPARC.

Over the last decade, Australian astronomers have found dozens of new planets as part of the global effort to discover exoplanets—planets orbiting distant suns.

One of the pioneers of that hunt for exoplanets is Penny Sackett. From late 2008 until early 2011, Penny served as Australia’s Chief Scientist, advising the Prime Minister on matters relating to science, technology and innovation. But before that, she was director of the Research School of Astronomy and Astrophysics and Mount Stromlo and Siding Spring Observatories at the Australian National University (ANU).

Penny’s research established that about one in every 1,000 stars is orbited by a ‘Hot Jupiter’. These large planets sit extremely close to their sun, so that their orbits take just three or four days to complete. While most of the exoplanets spotted so far are Hot Jupiters, a handful of rocky, Earth-like planets have also been identified that might potentially support life.

Doubling up pays dividends in exoplanet hunt

“Twice the resolution and all the photons,” is Chris Tinney’s new catchphrase. It refers to new equipment being commissioned on the Anglo-Australian Telescope to hunt for planets beyond our Solar System (exoplanets). Chris, from the University of New South Wales, is a leader of the Anglo-Australian Planet Search (AAPS), which has found 32 exoplanets since 1998.

A so-called ‘Doppler shift’ in the spectrum of a star’s light often indicates the presence of planets. Unlike previous equipment, which frequently missed some of that light, the new system uses a cluster of optical fibres to gather all the starlight, boosting efficiency and doubling the Doppler precision.

Now, a new type of intensive observation campaign also is paying dividends. AAPS has recently had two 48-night blocks of observing time, which has helped them find two small exoplanets.“Our main aim is to find Solar System analogues,” says Chris, “ones that have a Jupiter-like planet in a middle-distance orbit, which could be indicative of having Earth-like planets in closer orbits.

“That requires getting very high precision measurements over orbital periods the same as Jupiter (12 years) or more. We have that precision now.”

PHOTO: AN ARTIST’S IMPRESSION OF AN EXOPLANET WITH MOONS, ORBITING THE STAR HD70642. CREDIT: DAVID A. HARDY, ASTROART.ORG © PPARC.

Department of Astrophysics and Optics, University of New South Wales, Sydney
Professor Chris Tinney, Tel: +61 (2) 9385 5168, cgt@phys.unsw.edu.au, phys.unsw.edu.au/~cgt/cgt/Homepage.html

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 Bringing undiscovered Earths into focus