A team of scientists from the Massachusetts Institute of Technology (MIT), together with researchers from other institutions, made a discovery capable of marveling mathematicians and astronomers at once: with analysis of the Kepler space telescope K2 mission data, they found a “Terra pi”, that is, a planet that is similar in size to the Earth and orbits its star every 3.14 days.
The researchers analyzed the planet’s system earlier this year with The Search for habitable Planets EClipsing ULtra-cOOl Stars (SPECULOOS), a network of telescopes on the desert floor of the Atacama desert. Astronomers generally look at individual stars for signs that indicate that a planet is passing in front of that star – that is, signs of planetary transit. Thus, Prajwal Niraula, a graduate student in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS) department, found a white dwarf in the data collected by the K2 mission, the Kepler telescope’s second observation mission.
Niraula analyzed the data and found “flaws” in the light of the star EPIC 249631677, which seemed to repeat itself every 3.14 days. After studying the signs and testing different scenarios for their origin, the team agreed that it was a planetary transit, and that they needed to look at the star more closely. For that, they had to identify a window of time to see the traffic. With a weather forecasting algorithm, the team discovered some February 2020 nights that could allow the planet to be visualized. They pointed SPECULOOS ‘telescopes towards the star and saw two transits in the southern hemisphere and one in the north.
Niraula explains that “the planet moves as precisely as a clockwork”. The new planet was called K2-315b, and it is the 315th planetary system discovered within K2 data – which is simply a timid system in a very promising location. The researchers estimate that the K2-315b has a radius equivalent to 0.95 of that of Earth, so that it is very similar in size to that of our planet. It orbits a cold star that is the size of a fifth of our Sun at a speed of 81 kilometers per second.
Scientists have not yet determined the mass of K2-315b, but they suspect it is similar to that of our planet. However, the “planet pi” is probably not habitable, because it is so close to its star that temperatures there must reach 350 ° C. Even so, this world is a good candidate for studies on its atmosphere. “Now we know that we can search for and extract planets from data files, and we hope there are none left, especially the important ones like this that have a big impact,” says de Wit, assistant professor at EAPS.
For the team, the K2-315b is a promising candidate to be accompanied by the James Webb space telescope for analysis of its atmosphere. Until these studies start, they are checking other databases and looking at the sky for signs of other Earth-like planets. “With better algorithms, we hope that someday we will be able to search for smaller planets, perhaps as small as Mars,” concludes Niraula.
The study article, entitled “π Earth: a 3.14-day Earth-sized Planet from K2’s Kitchen Served Warm by the SPECULOOS Team”, was published in the magazine Astronomical Journal.