Announcing the “first official picture” of the six Kepler-452b planets that await follow-up analysis for possible life, a telescope astronomer said they are even more unlikely to be habitable than the six Earth-sized planets indicated.
Based on a new approach to analysing the total planetary statistics of a sample Kepler identified with its first mission in 2009, which followed and extended on previous missions of the Hubble space telescope, Chaz Riggs of the University of Texas at Austin and some colleagues have proposed a more conservative estimate for the planets in Kepler’s Kepler Family to explain why the six Earth-size planets found so far have been so sparsely sampled.
Based on a new approach to analysing the total planetary statistics of a sample Kepler identified with its first mission in 2009, Chaz Riggs of the University of Texas at Austin and some colleagues have proposed a more conservative estimate for the planets in Kepler’s Kepler Family to explain why the six Earth-size planets found so far have been so sparsely sampled.
Riggs and some colleagues propose that the total number of planets in the Kepler Family is about 300 – about 25% fewer than the original Kepler dataset.
Riggs and others propose that it might be a trick of the light spectrum that has allowed them to identify the six Earth-size planets but left other planets that might be most similar to planets like our home world unseed.
They decided to use the Hubble Space Telescope, or Hubble, to identify planets by a method called microdissection, which uses data from only the most distant stars.
The method lets researchers detect hundreds or thousands of “pulsing lights” within a relatively narrow band around the distant star. The stars are moving on their own time scales in both the so-called dimmed and brightened states that would give us the opportunity to see significant differences in their light.
The microdissection method provides the possibility that three faint stars are broken up into tens of thousands of tiny pulsating objects – molecules containing chemicals of light – as they pass through our retina. The pattern of the flickering objects appears as a single night spot when seen at a small scale of our eyes, but becomes separated by billions of kilometres once we measure them to be Earth-like. This sensitivity to Earth-like planets that exist outside our solar system allows for an interesting analysis of transiting planets.
Using the Hubble Space Telescope, Riggs and colleagues examined only the stars near which Kepler detected two transiting transits (the periods when planets cross in front of their star from our point of view).
The six Earth-sized planets have been spotted around six Earth-sized stars, with dimming by a small amount of the starlight, very similar to what is seen with our sun. The researchers use an observational model to model how this special spectral pattern might be explained.
The processing of the microdissection data shows that between the six Kepler-452b planets detected so far, another group of planets with 30 times the mass of Jupiter are much closer to our Sun than those with six Earth-sized planets. An interesting finding is that these new planets would only be about 1 to 1.2 times the size of Earth.
“The theory for confirming that these planets are terrestrial would be that they would be less massive, requiring less magium to reach the same orbit,” said Riggs.
Planets would also need to be 4.5 to 6.2 times the mass of Jupiter, “out of bounds” for the six planets detected so far. That would mean that there would be 500 to 1,200 targets for further follow-up study – far beyond what the Kepler team would find in the ensuing search for exoplanets.
British astronomy: the Hubble Telescope | Astronomy magazine