Exoplanet K2-18b

[Cypress]

Webb Discovers Methane, Carbon Dioxide in Atmosphere of K2-18 b

A new investigation with NASA’s James Webb Space Telescope into K2-18 b, an exoplanet 8.6 times as massive as Earth, has revealed the presence of carbon-bearing molecules including methane and carbon dioxide. Webb’s discovery adds to recent studies suggesting that K2-18 b could be a Hycean exoplanet, one which has the potential to possess a hydrogen-rich atmosphere and a water ocean-covered surface.

The abundance of methane and carbon dioxide, and shortage of ammonia, support the hypothesis that there may be a water ocean underneath a hydrogen-rich atmosphere in K2-18 b. These initial Webb observations also provided a possible detection of a molecule called dimethyl sulfide (DMS). On Earth, this is only produced by life. The bulk of the DMS in Earth’s atmosphere is emitted from phytoplankton in marine environments.

K2-18 b orbits the cool dwarf star K2-18 in the habitable zone and lies 120 light-years from Earth in the constellation Leo. Exoplanets such as K2-18 b, which have sizes between those of Earth and Neptune, are unlike anything in our solar system.

https://www.nasa.gov/goddard/2023/webb-discovers-methane-carbon-dioxide-in-atmosphere-of-k2-18b

 

[PostmodernProphet]

I wonder if the inhabitants will welcome new neighbors......

 

[Dutch Uncle]

Webb Discovers Methane, Carbon Dioxide in Atmosphere of K2-18 b

A new investigation with NASA’s James Webb Space Telescope into K2-18 b, an exoplanet 8.6 times as massive as Earth, has revealed the presence of carbon-bearing molecules including methane and carbon dioxide. Webb’s discovery adds to recent studies suggesting that K2-18 b could be a Hycean exoplanet, one which has the potential to possess a hydrogen-rich atmosphere and a water ocean-covered surface.

The abundance of methane and carbon dioxide, and shortage of ammonia, support the hypothesis that there may be a water ocean underneath a hydrogen-rich atmosphere in K2-18 b. These initial Webb observations also provided a possible detection of a molecule called dimethyl sulfide (DMS). On Earth, this is only produced by life. The bulk of the DMS in Earth’s atmosphere is emitted from phytoplankton in marine environments.

K2-18 b orbits the cool dwarf star K2-18 in the habitable zone and lies 120 light-years from Earth in the constellation Leo. Exoplanets such as K2-18 b, which have sizes between those of Earth and Neptune, are unlike anything in our solar system.

https://www.nasa.gov/goddard/2023/webb-discovers-methane-carbon-dioxide-in-atmosphere-of-k2-18b

8.6 Gs would be a tough existence.

 

[Cypress]

8.6 Gs would be a tough existence.

The article describes is volume or size being 8.6 times that of Earth. But gravity is related to mass, not volume. The density of K2-18b isn't necessarily the same as Earth's density. Earth has a substantial iron-nickel core and a dense mantle.

 

[Cypress]

Assuming we could get a solar light sail to accelerate up to 0.2 c, it would take 600 years from Earth's perspective to get a probe to that planet.

 

[Dutch Uncle]

The article describes is volume or size being 8.6 times that of Earth. But gravity is related to mass, not volume. The density of K2-18b isn't necessarily the same as Earth's density. Earth has a substantial iron-nickel core and a dense mantle.

If the standard of rocky planets in the habitable zone is followed, then it would be close. Agreed not necessarily, but it would like be much higher gravity than Earth.

Earth, by the way, would be a sixth larger if a Mars-sized planet hadn't collided with the Earth and knocked off the Moon.

 

[Saint Guinefort]

If the standard of rocky planets in the habitable zone is followed, then it would be close. Agreed not necessarily, but it would like be much higher gravity than Earth.

Earth, by the way, would be a sixth larger if a Mars-sized planet hadn't collided with the Earth and knocked off the Moon.

According to the article from Nasa it is about 8 times as massive so you are likely correct. About 8 times the gravity of earth per F=Gmm/r^2

 

[NiftyNiblick]

Webb Discovers Methane, Carbon Dioxide in Atmosphere of K2-18 b

A new investigation with NASA’s James Webb Space Telescope into K2-18 b, an exoplanet 8.6 times as massive as Earth, has revealed the presence of carbon-bearing molecules including methane and carbon dioxide. Webb’s discovery adds to recent studies suggesting that K2-18 b could be a Hycean exoplanet, one which has the potential to possess a hydrogen-rich atmosphere and a water ocean-covered surface.

The abundance of methane and carbon dioxide, and shortage of ammonia, support the hypothesis that there may be a water ocean underneath a hydrogen-rich atmosphere in K2-18 b. These initial Webb observations also provided a possible detection of a molecule called dimethyl sulfide (DMS). On Earth, this is only produced by life. The bulk of the DMS in Earth’s atmosphere is emitted from phytoplankton in marine environments.

K2-18 b orbits the cool dwarf star K2-18 in the habitable zone and lies 120 light-years from Earth in the constellation Leo. Exoplanets such as K2-18 b, which have sizes between those of Earth and Neptune, are unlike anything in our solar system.

https://www.nasa.gov/goddard/2023/webb-discovers-methane-carbon-dioxide-in-atmosphere-of-k2-18b

If a planet configured to support carbon-based life forms were 8.6 times larger than earth,
their species most closely resembling humans
would have awfully thick legs.

 

[Cypress]

If the standard of rocky planets in the habitable zone is followed, then it would be close. Agreed not necessarily, but it would like be much higher gravity than Earth.

Earth, by the way, would be a sixth larger if a Mars-sized planet hadn't collided with the Earth and knocked off the Moon.

Good then, I didn't see an estimate of it's density.

Definitely higher gravity than Earth either way. I don't know if 5g or 8g neccessarily excluded the possibility of life.

 

[Dutch Uncle]

According to the article from Nasa it is about 8 times as massive so you are likely correct. About 8 times the gravity of earth per F=Gmm/r^2

That's how I read it, Perry; 8.6 times as massive, but only 2.6 times the radius of Earth, equaling 5.2 times the diameter. 5.2 times the size but 8.6 times the mass.

The postulation of an icy mantle is interesting especially since they think the ocean may be too hot for life.

Spectra of K2-18 b, obtained with Webb’s NIRISS (Near-Infrared Imager and Slitless Spectrograph) and NIRSpec (Near-Infrared Spectrograph), display an abundance of methane and carbon dioxide in the exoplanet’s atmosphere, as well as a possible detection of a molecule called dimethyl sulfide (DMS). The detection of methane and carbon dioxide, and shortage of ammonia, support the hypothesis that there may be a water ocean underneath a hydrogen-rich atmosphere in K2-18 b. K2-18 b, 8.6 times as massive as Earth, orbits the cool dwarf star K2-18 in the habitable zone and lies 120 light-years from Earth....

....While K2-18 b lies in the habitable zone, and is now known to harbor carbon-bearing molecules, this does not necessarily mean that the planet can support life. The planet's large size — with a radius 2.6 times the radius of Earth — means that the planet’s interior likely contains a large mantle of high-pressure ice, like Neptune, but with a thinner hydrogen-rich atmosphere and an ocean surface. Hycean worlds are predicted to have oceans of water. However, it is also possible that the ocean is too hot to be habitable or be liquid.

 

[Cypress]

If a planet configured to support carbon-based life forms were 8.6 times larger than earth,
their species most closely resembling humans
would have awfully thick legs.

I'm thinking microbial life.

I seriously doubt the possibility of humanoids or tetrapods.

 

[Dutch Uncle]

Good then, I didn't see an estimate of it's density.

Definitely higher gravity than Earth either way. I don't know if 5g or 8g neccessarily excluded the possibility of life.

Agreed gravity at those level wouldn't exclude life, especially oceanic life. On land, maybe a lot of turtle-like creatures.

 

[Cypress]

Agreed gravity at those level wouldn't exclude life, especially oceanic life. On land, maybe a lot of turtle-like creatures.

For sure.

I also think we have to be careful using planets in our solar system as physical or chemical analogies to planets in other systems. If 20 years of exoplanet research has shown us anything, it is to not expect other planetary systems to look similar to ours

 

[NiftyNiblick]

Agreed gravity at those level wouldn't exclude life, especially oceanic life. On land, maybe a lot of turtle-like creatures.

Excuse me for changing the subject, Oom,
but you seem to know the mods and administrators much better than I do.

Have CFM [Banjo Fuck],
Frank Apisa,
and Asshat Zombie [or whatever Fredo last called himself]
all passed away?

I miss at least one of those three,
but it appears that they've all died.

 

[Dutch Uncle]

I'm thinking microbial life.

I seriously doubt the possibility of humanoids or tetrapods.

That might be all it takes for the DSM presence.

K2-18 is red dwarf. If I'm reading the Wiki link correctly, it's only about 2.4B years old, +600M years, about half the age of the Earth. I'm reminded of the Alan Watts comment about rocks: "Watch out, because the rocks are going to eventually come alive and they are going to have people crawling over them. " LOL

https://en.wikipedia.org/wiki/K2-18
K2-18, also known as EPIC 201912552, is a red dwarf star located 124 light-years (38 parsecs)[4] from Earth, in the constellation of Leo.

The red dot near Virgo bottom Left.

 

[Cypress]

That might be all it takes for the DSM presence.

K2-18 is red dwarf. If I'm reading the Wiki link correctly, it's only about 2.4B years old, +600M years, about half the age of the Earth. I'm reminded of the Alan Watts comment about rocks: "Watch out, because the rocks are going to eventually come alive and they are going to have people crawling over them. " LOL

https://en.wikipedia.org/wiki/K2-18
K2-18, also known as EPIC 201912552, is a red dwarf star located 124 light-years (38 parsecs)[4] from Earth, in the constellation of Leo.

The red dot near Virgo bottom Left.

Interesting. It took about three billion years on Earth just for multicellular life to appear m

I read about some research recently that suggested photosynthesis might be difficult in M class star systems because those red dwarfs just don't put out enough solar radiation.

 

[Dutch Uncle]

For sure.

I also think we have to be careful using planets in our solar system as physical or chemical analogies to planets in other systems. If 20 years of exoplanet research has shown us anything, it is to not expect other planetary systems to look similar to ours

Agreed, but NASA wouldn't use the term "massive" if it wasn't talking mass. IIRC, planets are detected by the effect their mass has upon their primary star. This was noticed in the wobble of Bernard's Star: https://en.wikipedia.org/wiki/Barnard's_Star_b

The planet was proposed through the radial velocity method, the most common planet-hunting technique. A "wobble" observed in Barnard's Star's motion was confirmed to have a period of about 233 days, corresponding to a semi-major axis of 0.4 AU for a proposed companion. The mass of the likely planetary body was then deduced to be about 3.2 Earth mass. Lead astronomer Ignasi Ribas notes: "We used observations from seven different instruments, spanning 20 years of measurements, making this one of the largest and most extensive datasets ever used for precise radial-velocity studies."

https://en.wikipedia.org/wiki/Planetary_mass

In astronomy, planetary mass is a measure of the mass of a planet-like astronomical object. Within the Solar System, planets are usually measured in the astronomical system of units, where the unit of mass is the solar mass (M☉), the mass of the Sun. In the study of extrasolar planets, the unit of measure is typically the mass of Jupiter (MJ) for large gas giant planets, and the mass of Earth (M🜨) for smaller rocky terrestrial planets.

The mass of a planet within the Solar System is an adjusted parameter in the preparation of ephemerides. There are three variations of how planetary mass can be calculated:

 

[Dutch Uncle]

Interesting. It took about three billion years on Earth just for multicellular life to appear m

I read about some research recently that suggested photosynthesis might be difficult in M class star systems because those red dwarfs just don't put out enough solar radiation.

The article suggested the oceans may be too hot for life or not liquid, meaning gaseous to me. IDK. The Earth used to be super hot and then cooled.

Since the article mentions "habitable zone", I'm presuming that astronomers are taking into account solar heating; smaller, cooler stars would have a closer habitable zone than larger, hotter stars.

 

[Cypress]

Agreed, but NASA wouldn't use the term "massive" if it wasn't talking mass. IIRC, planets are detected by the effect their mass has upon their primary star. This was noticed in the wobble of Bernard's Star: https://en.wikipedia.org/wiki/Barnard's_Star_b


https://en.wikipedia.org/wiki/Planetary_mass

Exoplanet research is some of the coolest out there!

I love how NASA practically buried that nugget about detections of DSM molecules. A good conservative scientific approach to not get to excited until further validation and corroboration.

The British tabloids were making DSM the lead in their articles, and playing it up as evidence of life

 

[Dutch Uncle]

Excuse me for changing the subject, Oom,
but you seem to know the mods and administrators much better than I do.

Have CFM [Banjo Fuck],
Frank Apisa,
and Asshat Zombie [or whatever Fredo last called himself]
all passed away?

I miss at least one of those three,
but it appears that they've all died.

CFM was banned a few times. AHZ is on a long vacay tempban. Not sure about Frank, but, IIRC, he was in his late 70s or 80s.

AHZ after name-change: 07-03-2023

JesusAI 3rd 12b
JesusAI banned 3 months for 12b violation

01-20-2021

CFM
4th violation of rule 12b

Permanent ban