Webb telescope detects a possible signature of life on a distant world

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Cypress

Well-known member

Webb telescope detects a possible signature of life on a distant world​

A molecule detected on a planet 124 light-years away is produced on Earth by decaying phytoplankton and other microbes. There is no other known source.

A distant planet’s atmosphere shows signs of molecules that on Earth are associated only with biological activity, a possible signal of life on what is suspected to be a watery world, according to a report published Wednesday that analyzed observations by NASA’s James Webb Space Telescope.

The peer-reviewed report in the Astrophysical Journal Letters presents more questions than answers, acknowledges numerous uncertainties and does not declare the discovery of life beyond Earth, something never conclusively detected. But the authors do claim to have found the best evidence to date of a possible “biosignature” on a planet far from our solar system.

The planet, known as K2-18b, is 124 light-years away, orbiting a red dwarf star. Earlier observations suggested that its atmosphere is consistent with the presence of a global ocean. The molecule purportedly detected is dimethyl sulfide (DMS). On Earth it is produced by the decay of marine phytoplankton and other microbes, and it has no other known source. The astronomers want to observe the planet further to strengthen the evidence that the molecule is present.

 
Oh goody! Now Cypress will impress us all with quoting chemists for the day!

First Cypress demonstrated his MASSIVE knowledge of Quantum Mechanics in his discussion of imaginary numbers. Now we will be treated to a buffet of vague statements belying a profound ignorance of the subject backed up with quoting other people and whining when anyone questions him.

Cue the fun..... 3, 2, 1..... BLAAAAAAASTOFF!
 
DMS is a strong indicator of biological activity on earth but it may not be the same everywhere. Since there's no one on this thread who actually understands chemistry and run toward shiny objects without critical analysis, but DMS is not ipso facto always a sign of life.

To wit:

Abiotic production of DMS was achieved in lab settings using a photochemical reaction mechanism:

"Gas-phase products of H2S/CH4/N2 haze photochemistry, with or without CO2, were collected and analyzed using gas chromatography equipped with sulfur chemiluminescence detection. Depending on the starting conditions, we estimate that DMS, OCS, CH3SH, CH3CH2SH, CS2, and CH3CH2SCH3 are produced in mixing ratios >10−1 ppmv." (Reed et al, 2024)

The researchers indicate this constrains the reliance on things like DMS as a biosignature. For sure it is a biosignature on earth but that isn't necessarily true everywhere.

Reed et al were not the first or the only people to find evidence for abiotic production of DMS. Yang and Ru (2024) demonstrated abiotic formation of carbonyl sulfide (another potential biomarker we find on earth but also has a proposed mechanism for abiotic formation).

Hopefully this basic logic point will not upset posters like @Cypress. Yes it is a POSSIBLE sign of life, but not necessarily.

I know Cypress is at least smart enough to know that just because something happens ONE way it isn't necessarily the ONLY way. Of course Cy will come back on here (maybe) and tell me how many great minds agree with him. As if that is a logical riposte to the point.

Either way, here's an alternative explanation before we put on the party hats and celebrate life.

 
Cypress said:

Webb telescope detects a possible signature of life on a distant world​

A molecule detected on a planet 124 light-years away is produced on Earth by decaying phytoplankton and other microbes. There is no other known source.

A distant planet’s atmosphere shows signs of molecules that on Earth are associated only with biological activity, a possible signal of life on what is suspected to be a watery world, according to a report published Wednesday that analyzed observations by NASA’s James Webb Space Telescope.

The peer-reviewed report in the Astrophysical Journal Letters presents more questions than answers, acknowledges numerous uncertainties and does not declare the discovery of life beyond Earth, something never conclusively detected. But the authors do claim to have found the best evidence to date of a possible “biosignature” on a planet far from our solar system.

The planet, known as K2-18b, is 124 light-years away, orbiting a red dwarf star. Earlier observations suggested that its atmosphere is consistent with the presence of a global ocean. The molecule purportedly detected is dimethyl sulfide (DMS). On Earth it is produced by the decay of marine phytoplankton and other microbes, and it has no other known source. The astronomers want to observe the planet further to strengthen the evidence that the molecule is present.

Click to expand...
It's an interesting discovery and I hope continued observations bear it out.

A few months back you and I discussed the fact that Red Dwarf stars are the most common stars in our galaxy. They will also exist longer than our own star.

www.britannica.com

Red dwarf star | Definition, Facts, & Temperature | Britannica

Red dwarf star, the most numerous type of star in the universe and the smallest type of hydrogen-burning star.
www.britannica.com www.britannica.com
red dwarf star, the most numerous type of star in the universe and the smallest type of hydrogen-burning star.

Red dwarf stars have masses from about 0.08 to 0.6 times that of the Sun. (Objects smaller than red dwarf stars are called brown dwarfs and do not shine through the thermonuclear fusion of hydrogen.) Lighter stars are much more plentiful than heavier stars, and red dwarfs are thus the most numerous type of star. In the Milky Way Galaxy, about three-fourths of the stars are red dwarfs. The proportion is even higher in elliptical galaxies....

...Smaller stars have longer lifetimes than larger stars. While stars like the Sun have a lifetime of about 10 billion years, even the oldest red dwarf stars have not yet exhausted their internal supplies of hydrogen. The heaviest red dwarfs have lifetimes of tens of billions of years; the smallest have lifetimes of trillions of years. By comparison, the universe is only 13.8 billion years old. The dim red dwarfs will be the last stars shining in the universe.
 
K2-18b is huge; 8 to 9 times the size of Earth.

www.astronomy.com

K2-18 b could have dimethyl sulfide in its air. But is it a sign of life?

Fresh data from the James Webb Space Telescope provide more evidence for what some consider a biosignature — but debate is sure to follow.
www.astronomy.com www.astronomy.com

Biosignature or not?​

Lying 124 light-years away in the constellation Leo, K2-18 b orbits in the habitable zone of its red-dwarf host star — at a distance where the planet’s surface temperature can support liquid water. But at around 8 or 9 times as massive as Earth — equivalent to half the mass of the ice giant Neptune — it’s not clear what that surface is like.

The JWST observations that Madhusudhan’s team reported in 2023 showed clear signs of methane (CH4) and carbon dioxide (CO2) in its atmosphere. That, they argued, fits a scenario where a hydrogen-rich atmosphere surrounds a planet with a global water (H2O) ocean that could support life. They dubbed this scenario a “hycean” world, drawn from the words hydrogen and ocean. (Other studies, like one posted to the arXiv preprint server on the same day as the new work, say different scenarios are more likely for the planet. They include the possibility of a global magma ocean — “about as inhospitable as it gets,” says Seager — or a mostly gaseous makeup.)

At the time, the team also noted weak signs of DMS in the data, taken by JWST’s near-infrared spectrograph. DMS has been studied by astrobiologists for its potential to indicate life — what scientists call a biosignature — for over a decade. But the significance of the detection barely rose to a 2-sigma level, meaning there was a 5 percent probability of the signal appearing by chance — well short of the 5-sigma level considered to be the statistical gold standard in science.
 
Dutch Uncle said:
K2-18b is huge; 8 to 9 times the size of Earth.

www.astronomy.com

K2-18 b could have dimethyl sulfide in its air. But is it a sign of life?

Fresh data from the James Webb Space Telescope provide more evidence for what some consider a biosignature — but debate is sure to follow.
www.astronomy.com www.astronomy.com

Biosignature or not?​

Lying 124 light-years away in the constellation Leo, K2-18 b orbits in the habitable zone of its red-dwarf host star — at a distance where the planet’s surface temperature can support liquid water. But at around 8 or 9 times as massive as Earth — equivalent to half the mass of the ice giant Neptune — it’s not clear what that surface is like.

The JWST observations that Madhusudhan’s team reported in 2023 showed clear signs of methane (CH4) and carbon dioxide (CO2) in its atmosphere. That, they argued, fits a scenario where a hydrogen-rich atmosphere surrounds a planet with a global water (H2O) ocean that could support life. They dubbed this scenario a “hycean” world, drawn from the words hydrogen and ocean. (Other studies, like one posted to the arXiv preprint server on the same day as the new work, say different scenarios are more likely for the planet. They include the possibility of a global magma ocean — “about as inhospitable as it gets,” says Seager — or a mostly gaseous makeup.)

At the time, the team also noted weak signs of DMS in the data, taken by JWST’s near-infrared spectrograph. DMS has been studied by astrobiologists for its potential to indicate life — what scientists call a biosignature — for over a decade. But the significance of the detection barely rose to a 2-sigma level, meaning there was a 5 percent probability of the signal appearing by chance — well short of the 5-sigma level considered to be the statistical gold standard in science.
Click to expand...

The skepticism I have is that the planet orbits a red dwarf which are known to frequently spew out lethal amounts of gamma radiation.

Also, a few years ago dimethyl sulfide was supposedly detected in the atmosphere of Venus, but it dropped out of the news, so I assume the detection turned out to be a false positive, or had some other explanation
 
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