Space Now!

Billions of Planets

18-05-12

Written by Josh

Recently it was reported in a new study of the sky that there could be billions of life supporting planets in our universe.

This news came after the release of an investigation done by a team of scientists in France. Their study was carried out using the High Accuracy Radial Velocity Planet Searcher (HARPS), this instrument studies stars and looks to see if they wobble.

The wobble can be caused by planets moving round their parent star. As both bodies interact gravitationally they both have an effect on each other and although the movement of the planet is much greater, small effects can be detected on the star.

The HARPS study focussed on a smaller, cooler type of star called a red dwarf. These were picked because it is thought they make up a large proportion of the stars in our galaxy and their smaller, fainter profile can make it easier to detect planets.

The French team analysed a sample containing 102 stars and achieved positive results from 8 systems, detecting a total of 14 planets, 2 of these being newly confirmed giant planets. This is an especially good result because a lot of information has been gathered about these planets, such as mass and orbital period, and these have a high level of accuracy due to the sophistication of HARPS.

From their data the team used statistical extrapolation to give them an idea of how common these planets may be. They concluded that 41% of red dwarf stars have at least one planet, but that result could be anywhere between 28% and 95%. This means that on the assumption that red dwarfs make up a large proportion of our galaxy (approximately 100 billion stars) we can see how it is easy to arrive at an estimate of billions of possible planets.

This sounds like good news but it has already been disputed. The estimate of 41% is much higher than the team's data actually shows, with the results they directly analysed showing that only about 10% of the stars sampled had planets around them.

The details of this study and the predications made have provoked discussion and will probably continue to do so. Questioning the validity of results is a vital part of the way science progresses, and in practice this ensures that science maintains the highest standards.

It is important to remember that this study has shown the HARPS instrument can still carry out its job to a high accuracy, therefore enabling more planets to be found and confirmed around a potentially abundant class of stars. This study and the discussion it has generated will help to bolster the interest in an already popular area of scientific research.

Image Credit: European Southern Observatory