NASA’s successor to the Kepler mission, the Transiting Exoplanet Survey Satellite (TESS), is already paying dividends. The satellite was only launched in April and spent time undergoing commissioning and calibration. But it has now started its science mission, and researchers have already discovered two new exoplanets.
The space telescope is on a two-year, $337 million mission to expand astronomers’ known catalog of so-called exoplanets, worlds circling distant stars. Like Kepler, TESS will be watching for transits, which occur when a planet passes in front of its star from the observer’s perspective, causing a periodic and regular dip in the star’s brightness.
While the two newly discovered planets are too hot to support life, TESS Deputy Science Director Sara Seager expects many more such discoveries.
On discovery of two candidate planets in @NASA_TESS‘s first data, @TESSatMIT Deputy Director of Science @ProfSaraSeager @MIT said “The team is excited about what TESS might discover next. We do know that planets are out there, littering the night sky, just waiting to be found.” pic.twitter.com/TbCoP2Ak84
— NASA_TESS (@NASA_TESS) 21 september 2018
Both exoplanets are still candidates, which means astronomers have yet to confirm their existance—but experts are already actively vetting the preliminary results.
The first exoplanet candidate was announced on September 19 and orbits a star called Pi Mensae, 60 light years away from Earth. It orbits its star every 6.3 days and seems to have a density similar to water.
Fun notes for @NASA_TESS 1st planet candidate: Pi Mensae star is visible in the night sky, the planet’s mass & radius show a water-like density (infers water / gases), and it’s the system’s 2nd known planet (the other has 10x Jupiter’s mass & orbits every 5.7 years). @TESSatMIT pic.twitter.com/tltNHbjDNb
— NASA_TESS (@NASA_TESS) 20 september 2018
The scientists have used TESS data to discover a new planet around the star Pi Mensae, also known as HD 39091, which is located about 59.5 light-years from Earth in the constellation Mensa, the table. Pi Mensae is a yellow dwarf star like the sun and the second-brightest among stars known to have transiting exoplanets.
Combining the newfound planet’s mass and radius shows it has a similar density to pure water, “though of course we should not imagine the planet to be a globe of water,” the TESS team writes. Instead, it probably has a core made of iron and rock, surrounded by an ocean or atmosphere of lighter materials like water, methane, hydrogen and helium.
TESS will scan a much larger region of the sky than Kepler did – and one that is closer to Earth. But TESS can really be thought of as the first half of a Kepler-like program. Since it will help find a lot of planets, including a few that may be close enough to be imaged by existing hardware. It will lay the groundwork for the giant telescopes that are currently under construction, as well as the James Webb Space Telescope, which continues to inch toward launch. These will greatly expand our reach out into the galaxy, vastly increasing the distance at which we can image planetary atmospheres.