While discovering an exoplanet would be a thrill for anyone, astronomy student Michelle Kunimoto is turning it into something of a habit. The University of British Columbia Ph.D. candidate, who previously discovered four exoplanets as an undergrad, is making news again for uncovering an astounding 17 new alien worlds by combing through data collected by NASA's Kepler space telescope.
Included in this impressive total is an extremely rare Earth-sized world situated within the habitable or "Goldilocks zone" of its host star.
"This planet is about a thousand light-years away, so we're not getting there anytime soon!" Kunimoto said in a statement. "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."
Data mining the cosmos
Sizes of the 17 new planet candidates, compared to Mars, Earth and Neptune. The planet in green is KIC-7340288 b, a rare rocky planet in the habitable zone. (Photo: Used with permission by Michelle Kunimoto)
The new exoplanets discovered by Kunimoto were hidden within the copious data gathered by the Kepler space telescope over the course of its nearly 10-year survey of the cosmos. While more than 2,600 alien worlds were detected during the mission, which ended in October 2018, many more await detection among the 200,000 stars observed.
In a paper published in the latest issue of The Astronomical Journal, Kunimoto explained how she applied what's called the "transit method" to determine if planets were orbiting a star.
"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," she said. "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."
To confirm her results, Kunimoto then trained the Near InfraRed Imager and Spectrometer (NIRI) on the Gemini North 8-metre Telescope in Hawaii on the suspected planet-hosting stars.
"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."
A cousin of Earth?
The rare and potentially habitable exoplanet discovered by Kunimoto orbits its host star at a distance a little larger than that of Mercury and with a full orbit lasting 142.5 days. While it's roughly 1.5 times the size of Earth, it only receives about one-third of the light we get from our sun.
Kunimoto and her PhD supervisor, UBC professor Jaymie Matthews, will next turn their attention to analyzing known Kepler planets, with an eye toward discovering more about how a host star's temperature might impact the number of orbiting bodies.
"A particularly important result will be finding a terrestrial Habitable Zone planet occurrence rate," Matthews added. "How many Earth-like planets are there? Stay tuned."