Earth-like Planets Hosted by Young and Old Stars: 33 Stars Reveal the Ages of 'Suns'

Old stars may have Earth-like planets. A new study of 33 Kepler stars with solar-like oscillations have shown the ages of sun-like stars with Earth-like planets. 

"Our team has determined the ages for individual host stars before with similar levels of accuracy, but this constitutes the best characterized set of exoplanet host stars current available," said Victor Silva Aguirre, one of the researchers, in a news release.

In this latest study, the researchers characterized 33 stars that were carefully selected from the more than 1,200 stars with planets around them that were observed with the highly successful Kepler satellite. The stars had to be sufficiently bright to give a good statistical basis for the results, and they had to show some of the same characteristics similar to the sun to make them comparable.

Stars pulsate, vibrate and resonate just like sound waves in a musical instrument. In this case, the researchers used an advanced technique to measure these starry vibrations. The Kepler satellite has constantly measured tiny variations in the light from 145,000 stars over a period of little more than four years. Analyzing these variations over time gives the period of the many simultaneous pulsations in each star, and from that the scientists can derive the important basic properties of the individual stars.

The researchers found that the 33 stars are solar-like oscillators, which means that exhibit similar pulsations to that of the sun.

"One of the biggest questions in astrophysics is: does live exist beyond earth?" said Aguirre. "To even begin answering this, we need to know how many planets like ours exist out there, and when they formed. However, determining ages are only available for a handful of host stars thanks to asteroseismic observations made with the Kepler satellite."

This study provides the first sample of homogeneously determined ages for tens of exoplanet host stars with a high level precision. The exoplanets are comparable to the size of Earth and reveal that the host stars can be both young and older-about 2.5 times that of the sun. It's surprising to find planets that are orbiting stars that are so old.

The findings are published in the journal Monthly Notices of the Royal Astronomical Society.

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