Five-planet star

Kepler-444 hosts five earth-sized planets in very compact orbits. The planets were detected from the dimming that occurs when they transit the disc of their parent star, as shown in this artist’s conception.

On the basis of data gathered by NASA’s Kepler mission, scientists led by asteroseismologists from the University of Birmingham announced in The Astrophysical Journal their observation of a sun-like star (Kepler-444) hosting five planets with sizes between Mercury and Venus. Kepler-444 was formed 11.2 billion years ago, when the universe was less than 20 per cent its current age. This is the oldest known system of terrestrial-sized planets in the galaxy, two and a half times older than the earth.

The team carried out the research using asteroseismology: listening to the natural resonances of the host star that are caused by sound trapped within it. These oscillations lead to minuscule changes or pulses in its brightness which allowed the researchers to measure its diameter, mass and age.

The planets were then detected from the dimming that occured when the planets transited, or passed across, the stellar disc. This fractional fading in the intensity of the light received from the star enabled scientists to accurately measure the size of the planets relative to the size of the star.

“There are far-reaching implications for this discovery,” said Tiago Campante of the University of Birmingham’s School of Physics and Astronomy who led the research.