Nearby exoplanet is a 1st-of-its-kind 'steam world,’ James Webb Space Telescope finds

[Admin]

Using the James Webb Space Telescope, astronomers have found a "first of its kind" world, an exoplanet that is twice the size of Earth and has an atmosphere packed with steam.

Nearby exoplanet is a 1st-of-its-kind 'steam world,’ James Webb Space Telescope finds : Read more

 

[wsdzasddswef]

Even if they do find a habitable big earth planet with tall blue people with tails theres no way they would expose it to the general public for decades

 

[COLGeek]

Even if they do find a habitable big earth planet with tall blue people with tails theres no way they would expose it to the general public for decades

Why and who is they?

Assuming such a discovery was made. Discounting that JWST could see that level of detail.

 

[hamsterbytes54]

Am i wrong to think that Venus is like the steam pkanet?

 

[offib]

How do we know that this isn't the earth after one or two hundred years of runaway climate change? Water vapour in the atmosphere has already increased by %7 for every 1C rise in average warming.

 

[offib]

Am i wrong to think that Venus is like the steam pkanet?

I mean, water has far more absorption and warming potential than CO2...

 

[Unclear Engineer]

Getting back to our best guess at reality: What would the surface pressure be for that "steam planet"? Would the conditions be past the critical point, so that there is no free water surface between "liquid" and "gas"?

 

[Torbjorn Larsson]

Future observations probing potential absorptionfrom carbon- and sulfur-bearing species could shed more lighton which volatile enrichment mechanism(s) shaped theatmosphere of GJ 9827 d.

GJ 9827 d is a sub-Neptune (1.98 Earth radius) just above the radius valley, but it is interesting even so.

With a mass of 3.02 M⊕ and a radius of 1.98 R⊕, GJ 9827 d hugs the upper size end of the radius valley, in line with its high predicted hydrogenescape rates.

Getting back to our best guess at reality: What would the surface pressure be for that "steam planet"? Would the conditions be past the critical point, so that there is no free water surface between "liquid" and "gas"?

It is a complicated issue:

Furthermore, recent theoretical (C. Dorn & T. Lichtenberg 2021; N. Madhusudhan et al. 2021; H. Innes et al. 2023)and observational findings (R. Luque & E. Palle 2022;N. Madhusudhan et al. 2023; B. Benneke et al. 2024a;M. Holmberg & N. Madhusudhan 2024) support greater compositional diversity within the sub-Neptune population. While the coolest planets may be “Hycean worlds” with water in condensed liquid/ice phases under a H/He atmosphere, the warmer temperature of the vast majority of planets would instead imply a supercritical state for the water/volatile layer. Contrary to liquid water, supercritical water is highly miscible with hydrogen. Such warm, volatile-rich planets may therefore host exposed “mixed” envelopes where both H2 and potentially large amounts of HMMW volatiles coexist (B. Benneke et al.2024a; R. Burn et al. 2024; N. F. Wogan et al. 2024). In addition, water is expected to partition between the planetary envelope, the molten or solid mantle, and the metal core, leading to more uncertainties in planetary structure models(C. Dorn & T. Lichtenberg 2021; H. E. Schlichting &E. D. Young 2022; H. Luo et al. 2024).

We estimate, for a pure H2O envelope on top of a solid rock/iron core, that the hydrosphere makes up between 20% and 40% of the total planet mass.