Astronomy Student Michelle Kunimoto of the University of British Columbia (UBC) has discovered 17 new exoplanets, including a potentially habitable, Earth-sized world, by combing through the data gathered by NASA's Kepler mission. The Kepler satellite looked for planets, especially those that lie in the "habitable zones" of their stars, where liquid water could exist on a rocky planet's surface over its original four-year mission.
Exoplanets refer to planets that orbit stars outside of our Solar System.
The new finding is published in The Astronomical Journal that includes one such particularly rare planet. Officially named KIC-7340288 b, the planet discovered by Michelle Kunimoto is just one and a half times the size of Earth, which is small enough to be considered rocky, instead of gaseous like the giant planets of the Solar System and in the habitable zone of its star.
"This planet is about a thousand light-years away, so we're not getting there anytime soon!" said Michelle Kunimoto, a PhD candidate in the Department of Physics and Astronomy. "But this is a really exciting find since there have only been 15 small, confirmed planets in the habitable zone found in Kepler data so far," Michelle Kunimoto added.
The planet has a year that is 142.5 days long, orbiting its star at 0.444 Astronomical Units (AU, the distance between Earth and our Sun) just bigger than Mercury's orbit in our Solar System, and gets about a third of the light Earth gets from the Sun. Of the other 16 new planets discovered, the smallest is only two-thirds the size of Earth one of the smallest planets to be found with Kepler so far. The rest range in size up to eight times the size of Earth.
Michelle Kunimoto working on her Ph.D. at UBC used the "transit method" to look for the planets among the roughly 200,000 stars observed by the Kepler mission.
"Every time a planet passes in front of a star, it blocks a portion of that star's light and causes a temporary decrease in the star's brightness," Michelle Kunimoto said. She further stated, "By finding these dips, known as transits, you can start to piece together information about the planet, such as its size and how long it takes to orbit".
Michelle Kunimoto also collaborated with UBC alumnus Henry Ngo to obtain razor-sharp follow-up images of some of her planet-hosting stars with the Near InfraRed Imager and Spectrometer (NIRI) on the Gemini North 8-metre telescope in Hawaii.
"I took images of the stars as if from space, using adaptive optics," she said. "I was able to tell if there was a star nearby that could have affected Kepler's measurements, such as being the cause of the dip itself."
In addition to the new planets, Michelle Kunimoto was able to observe thousands of known Kepler planets using the transit method and will be re-analysing the exoplanet census as a whole.
"We'll be estimating how many planets are expected for stars with different temperatures," said Michelle Kunimoto's PhD supervisor and UBC Professor Jaymie Matthews.
"A particularly important result will be finding a terrestrial habitable zone planet occurrence rate. How many Earth-like planets are there? Stay tuned," Jaymie Matthews added.
(With inputs from ANI)