They detect water vapor in the atmosphere of a “super Neptune”
This recently discovered planet, a bit bigger than neptune and orbiting a red dwarf star about 150 light-years away, places it at an exclusive club: exoplanets, or planets around other stars, known to have water vapor in their atmospheres. Many questions remain, such as how much water vapor its atmosphere contains. But TOI-674 b’s atmosphere is much easier to observe than that of many exoplanets, making it a prime target for further investigation.
The planet’s distance, size, and relationship to its star make it especially accessible to space telescopes. At 150 light-years away, 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 this 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 smallest star, our telescopes can more easily analyze the light from stars shining through its atmosphere. Those equipped with special instruments called spectrographs, including the recently launched James Webb Space Telescope, can spread this light out into a spectrum, revealing which gases are present in the planet’s atmosphere.
The discovery arose from a partnership between the Hubble Space Telescope and the TESS satellite, launched in 2018. The planet was first found by TESS, Hubble then measured its light spectrum. Data from the now-retired Spitzer Space Telescope also helped astronomers discover some of the planet’s atmospheric components. If the Webb telescope, once it’s up and running, points toward TOI-674 b, it should be able to examine the planet’s atmosphere in much more detail..
So far, only aspects of the atmospheres of three other Neptune-sized exoplanets have been revealed, though the advent of telescopes like Webb promises a golden age in the study of exoplanet atmospheres.
The new planet TOI-674 b orbits its small star so strongly that a “year” on this planet, one orbit 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 of the class size between Neptune and Jupiter are extremely rare in orbits of three days or less. The rarity of these planets and the analysis of those that appear could provide important clues about the formation of planetary systems in general, including our own.
January 14, 2022
NASA in Spanish