New Zealand astronomers discover new star and planet

A team of astronomers at New Zealand’s Mt John observatory in Canterbury has discovered a small star with its own planet some two to three times larger than Earth, 3,000 light years away.

The international team included New Zealand astronomer Dr Ian Bond from Massey University in Auckland. Software that Dr Bond developed is used for the analysis of data in the microlensing technique used to discover the star and planet.

Dr Bond says the discovery is significant because it means that even the lowest mass stars can host planets. Dr Bond says in the near future it may be possible to see signs of life on planets like this when NASA launches a more powerful successor to the Hubble space telescope.

The discovery was made through a new Japanese-funded MOA telescope, the world's largest dedicated to gravitational microlensing and the biggest telescope in New Zealand. MOA stands for microlensing observations in astrophysics. The telescope has a 1.8 metre aperture, and a field of view in excess of two square degrees. It has a large electronic camera mounted at the prime focus. The camera can take photos with 80 million pixels. Many millions of stars can be recorded in a single exposure of dense stellar fields such as in Sagittarius at the centre of the Milky Way.

The newly discovered star has a mass only about six percent of our Sun and is so small it may not be able to produce energy by nuclear fusion as our own Sun does. The planet is larger than Earth but has a smaller orbital radius, similar to Venus, and, because its sun is so small, it is likely to be colder than Pluto. The MOA team thinks that the planet could have a thick atmosphere underlain by a deep ocean warmed by internal heating from radioactivity.

The heating of the planet from radioactive decay was likely keeping its ocean liquid, yielding a possible habitat for life.

A paper about the discovery of the star and planet has been accepted for publication in The Astrophysical Journal, and is expected to be published in September 2008.

The MOA group is made up of astronomers from Nagoya University, Konan University, Nagano National College of Technology, and Tokyo Metropolitan College of Aeronautics in Japan, as well as Massey University, The University of Auckland, Mt John Observatory, the University of Canterbury, Victoria University in New Zealand, as well as Dr David Bennett of Notre Dame University. Additional astronomers include staff from the Warsaw University Observatory in Poland, the Universidad de Concepción in Chile, the University of Cambridge, the Institut d'Astrophysique de Paris, the Observatoire Midi-Pyr´en´ees, the Observatoire de Paris, the European Southern Observatory in Chile, and Heidelberg University.

To learn more about the Mount John Observatory and the MOA telescope see http://www.phys.canterbury.ac.nz/moa/