Hunting for planets
This new array will focus in the search for planets the size of Neptune and smaller, with a diameter of two to eight times that of the Earth. Reach a level of accuracy in the measurement of the brightness of stars – one part in a thousand – than ever before.
Credit: ESO/G. Lambert
The NGTS (Next-Generation Transit Survey or tool to survey the transit of new generation) has achieved the first light at ESO at Paranal in northern Chile. It is a wide-field and observing system, consisting of an array of twelve telescopes – each with an aperture of 20 cm – which aims to detect transits of extrasolar planets – that is, planets that pass in front of its parent star (outside the solar system) and consequently produce a small attenuation of the light of the star which can be observed by very sensitive instruments. The telescopes will focus in the search for planets the size of Neptune and smaller, with a diameter of between two and eight times that of the Earth.
Credit: ESO/R. West
This new structure, built by a consortium of British, Swiss and German, exploits the superb observing conditions and the excellent support structures available in the site in Chile. “We needed a site where the clear nights were so many and the clear air and dry , so we can make very accurate measurements and as often as possible – the Paranal was by far the best choice”, said Don Pollacco University of Warwick in the UK, one of the leaders of the project NGTS.
NGTS is designed to work in robotic mode and will monitor continuously the brightness of hundreds of thousands of relatively bright stars in the southern sky. Looking exoplanets in transit will reach a level of accuracy in the measurement of the brightness of stars – one part in a thousand – never before achieved by a tool to survey a large field that operates from the ground.
Credit: ESO/G. Lambert
NASA’s Kepler orbital mission, for example, has higher accuracy on measurement of the brightness of stars, but explores a smaller region of the sky than NGTS. The search NGTS over a larger area will find cases brightest of exoplanets smaller, more suitable for subsequent detailed studies. This high accuracy in the measurement of the brightness of a very large field is technically very challenging, but all the key technologies required for the NGTS had already been proven to be feasible on a smaller prototype, according to La Palma, in the Canary Islands between 2009 and 2010. The NGTS also builds on the success of the experiment SuperWASP, which so far leads the detection of large gas planets. The findings will be further explored with other than NGTS larger telescopes, including the VLT (Very Large Telescope) of ESO.
One of the aims is to find small planets that are sufficiently bright to measure the planetary mass. As a result we will be able to estimate the density of the planets and then derive clues about their composition. It will also be possible to probe the atmosphere of exoplanets in transit. In fact, in this period a part of the light from the star passes through the atmosphere of exoplanets, if present, and leaves a trace small, but identifiable. So far they have been completed only a few of these so delicate observations, but the NGTS provide many potential targets.
Credit: ESO/R. Wesson
This is the first project of telescope housed, but not managed by ESO at Paranal. Other projects that operate with similar agreements can be found at the La Silla Observatory. The data will feed the NGTS still in storage system of ESO and will be available to astronomers around the way for the coming decades.
Peter Wheatley, one of the project leaders of NGTS, University of Warwick, said: “We are excited to begin our search for small planets around nearby stars. The findings and observations of NGTS depth of telescopes on the ground and from space will be important steps for our research on the atmosphere and the composition of the planets as small as Earth.”