Telescopes found a gas giant candidate 4 light-years away.

   Telescopes found a gas giant candidate 4 light-years away. 

"This artist's concept shows what the gas giant orbiting Alpha Centauri A could look like. Observations of the triple-star system Alpha Centauri using NASA's James Webb Space Telescope indicate the potential gas giant, about the mass of Saturn, orbits the star by about two times the distance between the sun and Earth. In this concept, Alpha Centauri A is depicted at the upper left of the planet, while the other sun-like star in the system, Alpha Centauri B, is at the upper right. Our sun is shown as a small dot of light between those two stars. Credit: : NASA, ESA, CSA, STScI, R. Hurt (Caltech/IPAC)" (Phys.org, Evidence found for planet around closest sun-like star)

"Now, Webb's observations from its Mid-Infrared Instrument (MIRI) are providing the strongest evidence to date of a gas giant planet orbiting in the habitable zone of Alpha Centauri A. (The MIRI instrument was developed in part by the Jet Propulsion Laboratory [JPL], which is managed by Caltech for NASA). The habitable zone is the region around a star where temperatures could be right for liquid water to pool on a planet's surface." (Phys.org, Evidence found for planet around closest sun-like star)

The new Jupiter- or Saturn-type gas giant orbits Alpha Centauri A. That gas giant is interesting because its location is in the triple-star system. And another interesting thing is that. The exoplanet orbits the Alpha Centauri primary system. We have known for a while that there are two confirmed exoplanets and one exoplanet candidate around Proxima Centauri. But that new gas giant is something else. It orbits Alpha Centauri A, which is likely to be our Sun. And that raises the possibility of finding extraterrestrial life forms from the Alpha Centauri system.  

The fact is that we might not find exocivilization around those stars. And if there are no intelligent lifeforms on some planet, that makes it hard to detect those alien organisms. If those organisms are primitive caryotes, it is very hard to separate their metabolic products from those of other chemical reactions. If the planet is a so-called water world, its entire surface is covered by oceans. And those very primitive algae and bacteria can live in those oceans. 

The first organisms lived in the Earth's oceans. If alien prokaryotes are like the first prokaryotes that lived in the oceans, the atmosphere of the planet can be very hostile. There are many things. That determines whether the water world can support life. If the atmosphere is dense and the gravity is high, that means water cannot boil. 

There are creatures on Earth that can live in very high-temperature water near so-called hydrothermal vents. Those so-called black smokers are a volcanic eruption hole. 

"In contrast to the approximately 2 °C (36 °F) ambient water temperature at these depths, water emerges from these vents at temperatures ranging from 60 °C (140 °F)[6] up to as high as 464 °C (867 °F). Due to the high hydrostatic pressure at these depths, water may exist in either its liquid form or as a supercritical fluid at such temperatures. The critical point of (pure) water is 375 °C (707 °F) at a pressure of 218 atmospheres."  (Wikipedia, hydrothermal vent) 

"The hydrothermal vents are recognized as a type of chemosynthetic based ecosystems (CBE) where primary productivity is fuelled by chemical compounds as energy sources instead of light (chemoautotrophy). Hydrothermal vent communities are able to sustain such vast amounts of life because vent organisms depend on chemosynthetic bacteria for food. " (Wikipedia, hydrothermal vent) 

"The water from the hydrothermal vent is rich in dissolved minerals and supports a large population of chemoautotrophic bacteria. These bacteria use sulfur compounds, particularly hydrogen sulfide, a chemical highly toxic to most known organisms, to produce organic material through the process of chemosynthesis." (Wikipedia, hydrothermal vent) 

The water can be at a very high temperature and support life, because it's in supercritical form. The high pressure and high gravity prevent the water from boiling. There are no bubbles in supercritical water. And that helps organisms survive near black smokers. 

We could see life's building blocks and things like carbon dioxide. But we would not see things like algae from the water planet. Another thing is that there may be no lifeforms in the gas giant's atmosphere. 

However, there is a possibility that those gas giants may have moons similar to Jupiter's Europa. Low gravity and low gas pressure can keep water liquid in low temperatures. So the habitable zone can be far different from what we used to think. Intelligent lifeforms probably don't form on those moons. But primitive algae and bacteria can live in those icy worlds. 

The water moon can host lifeforms like bacteria and algae. But those things are not easy to detect. The planetary models that astronomers use are made using our own solar system as a model. All gas giants in our solar system have moons. So maybe all other gas giants that orbit other than red dwarfs can have moons, or dwarf planets orbiting them. 

https://www.astronomy.com/science/alpha-centauri-planet/

https://www.jpl.nasa.gov/news/nasas-webb-finds-new-evidence-for-planet-around-closest-solar-twin/

https://phys.org/news/2025-08-evidence-planet-closest-sun-star.html

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

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

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

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

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