The newly discovered planet TOI-674 b, slightly larger than Neptune and orbiting a red dwarf star about 150 light-years away, is a member of an exclusive club: the exoplanets, or planets around other stars, known because they have water vapor inside. their atmospheres. Many questions remain, such as how much water vapor does its atmosphere contain. But TOI-674 b’s atmosphere is much easier to observe than many exoplanets, making it a prime target for deeper investigations.

The planet’s distance, size and relationship to its star make it especially accessible to space telescopes. At 150 light years, it is considered “close” in astronomical terms. The star itself, relatively cool and less than half the size of our Sun, cannot be seen from Earth with the naked eye, but that also translates to an advantage for astronomers. As the comparatively large planet – in a size class known as “super Neptune” – crosses the face of its tiny star, the starlight shining through its atmosphere can be more easily analyzed by our telescopes. Those equipped with special instruments called spectrographs – including the recently launched James Webb Space Telescope – can spread that light into a spectrum, revealing which gases are present in the planet’s atmosphere.

The discovery came from a partnership between the tried and true Hubble Space Telescope and TESS, NASA’s Transiting Exoplanet Survey Satellite, which launched in 2018. The planet was first found by TESS, then its light spectrum was measured by Hubble. Data from the now-retired Spitzer Space Telescope also helped astronomers discover some of the planet’s atmospheric components. If the Webb telescope, once up and running, is hooked up to TOI-674b, it should be able to examine the planet’s atmosphere in much more detail.

Only three other Neptune-sized exoplanets have had aspects of their atmospheres revealed so far, though the advent of telescopes like Webb promises a golden age in the study of exoplanet atmospheres.

The new planet can claim membership in another exclusive group: the inhabitants of the so-called “Neptune Desert”. TOI-674 b orbits its tiny star so tightly that a “year” on this planet, once around the star, takes less than two days. But among the thousands of confirmed exoplanets in our galaxy so far, a strange pattern has emerged: Planets in the size class between Neptune and Jupiter are extremely rare in orbits of three days or less. The rarity of such planets and the analysis of those that do appear can provide important clues to the formation of planetary systems in general – including our own.

An international team of scientists, led by Jonathan Brande of the University of Kansas, contributed to the new study of water vapor in TOI-674 b, which has been submitted to an academic journal. They included researchers from NASA’s Ames Research Center and IPAC and other Caltech research centers.

A recent discovery places this exoplanet (a planet orbiting a star beyond our own) in an exclusive club – planets with water vapor in their atmospheres!

Hubble and TESS (NASA’s Transiting Exoplanet Survey Satellite) worked together to make this discovery. The exoplanet orbits a red-dwarf star about 150 light-years away from Earth, and is a little bigger than Neptune.

While many questions still remain, TOI-674 b’s atmosphere is easier to observe than those of many exoplanets, making it a prime target for more investigation.