HILO — Mauna Kea’s ground-based telescopes are expected to play a major role in astronomy’s ongoing search for Earth-like planets.
An article published Monday by Astrophysical Journal uses data from the Kepler mission to describe 49 planets that are similar in size to Earth and located within the habitable zone of the stars they orbit. The analysis, led by Stephen Kane of San Francisco State University, took three years.
Twenty of those planets are “excellent candidates for habitable rocky planets,” according to a release from the University of Hawaii at Manoa. UH Institute for Astronomy astronomer Nader Haghighipour was a co-author of the article.
“This is our best set of planets that we can go after with future observation to see if there’s any sort of signs of water or biology,” said Roy Gal, IFA associate astronomer.
“The next step, which is the most crucial one, is to follow up on all these candidates (with) ground-based telescopes,” Haghighipour wrote in an e-mail.
The Subaru, Gemini and Keck telescopes on Mauna Kea will likely be part of that endeavor.
“They play different roles,” Gal said. “A lot of people think telescopes are identical, but they all have a little bit of specialization.”
Keck’s telescopes in particular may help, Haghighipour said, but because the host stars are so faint and far away, “the most promising telescope would be (the Thirty-Meter Telescope).”
Planet observation would focus on determining atmospheric makeup, via spectroscopy, and density.
“The latter is key to understanding the degree to which these planets are rocky, which is the most necessary condition for being an Earth-analog,” Haghighipour said.
The first Kepler mission launched a telescope into space with the sole aim of finding possible planets. It lasted from 2009 to 2013 and located more than 4,000 exoplanets that were in habitable zones relative to their stars — the “Goldilocks” zone, Gal said, meaning they are not too hot or too cold to sustain life. (The telescope is now in a “K2” stage after some of the machinery failed. It is still locating planets, just via different techniques.)
The 49 planets identified by Haghighipour and his colleagues as possible Earth-like ones represent just over 1 percent of the Kepler total.
The entire catalog described in the article comprises 216 planets and includes planets as large as the Solar System’s gas giants.
There is also a chance that the moons of larger gas giant planets could be habitable.
“This catalog of HZ planets is small,” Gal said. “We’re looking for needles in a haystack.”