Some of the most common exoplanets in our coltsfoot are also the most mysterious . We do n’t have an equivalent to this type of satellite , called a submarine - Neptune , in our solar organization , but now the James Webb Space Telescope is uncover item about these planets for the first fourth dimension .

Smaller than ice-skating rink giants like Neptune or Uranus but with a gas composition more standardised to Saturn or Juputer , Sub - Neptunes are thought to be the most common type of exoplanet , but they are knockout to canvas because they are typically obscured by clouds and fog . That intend that stargazer have n’t been able to consider their atmospheres , or to learn much about how these satellite evolve , or why we do n’t have one in our solar organisation .

But of late , astronomers were able to use Webb to study a sub - Neptune called TOI-421 b. “ I had been wait my entire career for Webb so that we could meaningfully characterize the atmospheres of these small planets , ” said lead research worker Eliza Kempton of the University of Maryland , College Park . “ By studying their atmospheres , we ’re getting a better savvy of how sub - Neptunes take shape and evolved , and part of that is understanding why they do n’t subsist in our solar organization . ”

This special satellite was selected for study because of its utmost hotness , with a scorching temperature of around 1,340 degrees Fahrenheit . That is high enough there should n’t be methane present in the planet ’s atmosphere , which means that it should n’t form a haze — and should therefore be easy to respect .

“ Why did we notice this satellite , TOI-421 b ? It ’s because we thought that maybe it would n’t have hazes , ” articulate Kempton . “ And the understanding is that there were some previous data that imply that perchance planets over a sure temperature range were less cover by daze or cloud than others . ”

Thanks to the want of haze , the researchers were able-bodied to attend into the planet ’s air and see what it was composed of . They found water vaporization , with a large amount of H in the air , as well as proffer of carbon monoxide and sulfur dioxide — but notably , no indication of methane or carbon dioxide . The declamatory amount of atomic number 1 was a surprisal as it differs from the few other sub - Neptunes that have been maintain with Webb — so could this major planet be an anomalousness ? Or perhaps it formed in a different way from these other similar planets ?

The researchers desire to keep an eye on more sub - Neptune to find out . “ We ’ve unlock a young way to look at these hoagie - Neptunes , ” said investigator Brian Davenport . “ These high - temperature planets are tractable to characterization . So by calculate at sub - Neptune of this temperature , we ’re perhaps more likely to accelerate our power to learn about these planets . ”

The research is published inThe Astrophysical Journal Letters .