James Webb’s discoveries reveal a new world for humans

posted on 01/13/2023 06:00

A year after reaching its destination, the James Webb Space Telescope has detected, for the first time, an exoplanet — a planet orbiting a star — one of its most anticipated missions by astronomers. The rocky celestial body, LHS 475b, is 41 light-years away from here, is almost the same size as Earth, but would hardly host any kind of life: the local temperature, the equipment reveals, exceeds hundreds of degrees Celsius.

Mapping data from the North American Space Agency’s (NASA) Transiting Exoplanet Survey Satellite (TESS) suggested the existence of the planet, located in the constellation Octans. But only a telescope with James Webb’s unprecedented accuracy could confirm the hunch. The discovery of LHS 475b was announced at the 241st meeting of the North American Astronomical Society in Seattle.

Led by Johns Hopkins University astronomers Kevin Stevenson and Jacob Lustig-Yager, the team used data collected by the supertelescope to observe the planet’s transit on three occasions. When this celestial body passes by its star, the light emitted by it becomes weaker, which was captured by James Webb, confirming the existence of LHS 475b. “There’s no question that the planet is there,” Lustig-Yager said in a statement.

James Webb is the only telescope capable of characterizing the atmospheres of Earth-sized exoplanets. Scientists used the equipment to scan the new planet in various wavelengths of light to see if it had an atmosphere. So far no firm conclusions have been drawn, but the instrument has captured a number of molecules, indicating that this is a possibility.

“This planet could very well be an airless body that once lost its existing atmosphere,” Kevin Stevenson explained in a press conference streamed online. “But it can also have a tense or very rarefied atmosphere, which we haven’t quite captured yet.”

New analysis

Astronomers will have another opportunity mid-year to observe a transit of LHS 475b and hope to be able to clarify open questions. The data, for the moment, suggest that, if there is an atmosphere, it bears no resemblance to the Earth’s atmosphere and is not even dense, which already rules out, for example, the presence of methane, as happens on Titan , the moon of Saturn. One bet is that the composition is more like that of Venus, with carbon dioxide.

LHS 475b completes a single orbit around its red dwarf star every two Earth days. Because the host is less than half the temperature of the Sun, it’s possible the planet still retains an atmosphere despite its proximity to the star, Stevenson explained. “We are at the forefront of studying small rocky exoplanets,” said Lustig-Yaeger. “We’re just starting to understand what their atmospheres might be like.”

In a statement, the director of NASA’s Astrophysics Division, Mark Clampin, underlined the importance of the discovery: “These first observational results of a rocky planet the size of Earth open the door to many future possibilities for, with James Webb, study the atmospheres of rocky planets. The telescope is bringing us ever closer to a new understanding of Earth-like worlds outside our solar system, and the mission has only just begun.”

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potential life

credit: NASA/JPL-Caltech/Robert Hurt

LHS 475b wasn’t the only exoplanet whose discovery was announced at the North American Astronomical Society meeting. Earlier this week, NASA reported, at the event, the existence of an Earth-sized world, TOI 700, orbiting its star in a habitable zone, i.e. at a distance that would allow the existence of liquid water on the surface., a prerequisite for the existence of life as we know it. With a size of 95% similar to that of the Earth, the celestial body is probably rocky.

TOI 700e was detected with data from Tess and joins four other planets in the same solar system. “It’s receiving an energy flux that’s 1.3 times the Earth’s insolation — so it’s in an area where liquid water can exist, under the right conditions,” Fellow Emily Gilbert explained in an online press conference. postdoctoral fellow at NASA’s Jet Propulsion Laboratory, who led the discovery.

The star of this solar system, 100 light-years from Earth in the constellation Dorado, is home to at least four other previously detected planets. One of these, TOI 700d, is also in the habitable zone and the size of the Earth. The TOI 700e takes 28 days to go around the host, Gilbert said.

Launched in 2018, the TESS mission monitors large areas of the sky, called sectors, over the course of 27 days each. In this way the satellite can follow the changes in stellar luminosity caused by the transit of a planet. “We look forward to more exciting discoveries hidden in the mission’s data trove,” Allison Youngblood, NASA astrophysicist, research scientist and deputy project scientist, said in a statement. (DUST)