The floodgates are open. Scientists have announced the first exoplanet discovered by NASA’s TESS telescope, launched in April 2018, with thousands more expected to be discovered in the coming years.
This planet is called Pi Mensae c, and it's described in a paper on the preprint server arXiv. It still needs to be confirmed that the planet definitely exists, with the paper currently under peer review, but the team say they are confident in their discovery.
“It was extremely exciting for the team!” Natalia Guerrero from the Massachusetts Institute of Technology, a member of the TESS team and a co-author on the paper, told IFLScience. “Pi Mensae c is exactly the type of planet TESS was designed to find – a small planet around a bright nearby star.”
The planet discovered by TESS, a successor to NASA's wildly successful Kepler space telescope, is not “small” compared to our own, but it is small compared to the abundance of gas giants TESS is expected to find. Pi Mensae c is about 2.1 times the size of Earth, and completes an orbit of its star in 6.27 days. The star it orbits, a yellow dwarf, is located about 60 light-years from Earth.
Pi Mensae c is thought to be a super-Earth, a large and potentially terrestrial planet with a rocky core. Being so close to its star, it’s unlikely to have water or be habitable due to its high temperature. The mass of the planet is estimated to be about 4.8 times that of Earth.
It’s actually the second planet we know of in this system, the other being Pi Mensae b discovered in 2001, a planet 10 times the mass of Jupiter that orbits in 5.7 years. That in itself raises questions about how these two very different planets came to evolve in this system.
And it’s not the only planet TESS has found – the telescope has already been used to rediscover 17 known exoplanets from previous searches. But it is the first entirely new planet found by the telescope, and that heralds a slew of even more exciting discoveries to come. Initial discoveries like these are always exciting though; one of Kepler's first planets was a Neptune-sized world dubbed Kepler-4b, for example.
“This is a meaningful discovery for the TESS team because it demonstrates TESS is carrying out its mission to find small exoplanets around nearby, bright stars,” Avi Shporer, also from the Massachusetts Institute of Technology, and a study co-author, told IFLScience. “In total, TESS is predicted to find thousands of new exoplanets. Hence, there are many more exciting planet detections to come in the next years!”
TESS is currently in a four-month testing phase. Over the course of its two-year primary mission, it is expected to find 20,000 planets between 30 and 300 light-years from Earth. Most of these will be gas giants considerably larger than our own planet, but a few hundred could be rocky worlds less than twice the size of Earth.
Pi Mensae c wasn’t the only TESS discovery announced by scientists. Yesterday it was also revealed TESS had found a “hot Earth” called LHS 3844 b around a dwarf star called LHS 3844 about 50 light-years from Earth.
So just months after it launched, we already have two exciting discoveries from TESS. With its predecessor Kepler running out of fuel, TESS is set to become our main planet-hunting telescope for the next few years. And based on these discoveries, we aren’t going to be left wanting for new worlds.