A planet that may also be blue - 100 light-years away: Astronomers have discovered an exoplanet in a binary star system that may be completely covered by deep ocean. TOI-1452 b is slightly larger than Earth and orbits one of the two stars at a distance that could allow for liquid surface water. Its density suggests a high proportion of light substance - presumably water. Sharp looks with the James Webb Space Telescope should now elicit further secrets from TOI-1452 b, the scientists say.
Space is teeming with planets: astronomers have already discovered thousands of celestial bodies around distant stars. In the meantime, interest is therefore focused on the special specimens. Research is particularly focused on exoplanets that have similar characteristics to our cosmic homeland. A central aspect is the blue treasure of the earth. As is well known, liquid water has become the elixir of life for us: It is the prerequisite for the existence of all terrestrial organisms and it is assumed that their development history began in the oceans. Now the team of astronomers led by Charles Cadieux, a doctoral student at the Université de Montréal, is adding a particularly promising candidate to the small collection of potential water worlds.
On the trail of the exoplanet, the researchers brought data from NASA's TESS space telescope, which scans the sky for planetary systems in our cosmic neighborhood. In a system about 100 light-years from Earth in the constellation Draco, TESS detected interesting signals: every eleven days there was a slight decrease in brightness, which is apparently due to the passage of a planet. The researchers then followed this lead in more detail. As more and more interesting aspects emerged, the team used various astronomical facilities and instruments to collect information that was as detailed as possible.
Exciting features
First, it became clear that the star system consists not of one, but of two stars smaller than our sun. They orbit each other at a distance about two and a half times the distance between the Sun and Pluto. That's why she initially only perceived the TESS telescope as a single point of light. But a camera installed at Canada's Observatoire du Mont-Mégantic (OMM) was eventually able to resolve the signal to distinguish the two objects. It also revealed that the exoplanet orbits the duo's star TOI-1452. According to the calculations, it receives amounts of energy in the process that could lead to temperate conditions that allow liquid water on the surface.
The transit data revealed that the planet is about 70 percent larger than Earth. The radial velocity method was then used to determine the planet's mass, which allows conclusions to be drawn about a planet's characteristics based on its gravitational influence on its host star. The instrument "SPIRou" at the OMM was used, which is particularly suitable for studying low-mass stars such as TOI-1452, as it works in the infrared spectrum, where these stars shine most brightly. As the team reports, the data analysis revealed a mass of TOI-1452 that is about five times that of Earth.
An ocean planet?
"Its radius and mass suggest it is much less dense than you would expect for a planet that's mostly metal and rock, like Earth," says Cadieux. The features can be explained by the fact that a large part of the mass consists of lighter materials. A plausible explanation would be water. "TOI-1452 b is one of the best ocean planet candidates we've found so far," says Cadieux. Model simulations by the scientists showed that TOI-1452 b could consist of up to 30 percent water. He would be a pronounced water world. Because although Earth is sometimes referred to as the blue planet because about 70 percent of its surface is covered by oceans, it is actually a rather dry planet: water actually makes up only about 1 percent of Earth's mass.
TOI-1452 b is now a perfect candidate for further observations with the James Webb Space Telescope, the scientists say. It's also close enough to Earth that researchers hope to study its atmosphere for more clues as to whether it is, in fact, an oceanic planet. It's also fortunate that it's in a region of the sky that the Webb telescope can see year-round. "Our planned investigations with the Webb telescope will make a decisive contribution to a better understanding of TOI-1452 b," says René Doyon from the Université de Montréal. "As soon as possible, we will book time on Webb to observe this mysterious world."
Source: University of Montreal, professional article: The Astronomical Journal, doi: 10.3847/1538-3881/ac7cea