Could recently discovered exoplanet support alien life?

Rodiano Bonacci
Settembre 12, 2019

For the first time, scientists have found water vapor on a so-called "habitable zone exoplanent".

K2-18b may not be an exact replica of Earth, but in several ways, it comes much closer than previously known water-vapor-containing exoplanets, Nikole Lewis, an astronomer at Cornell University who was not involved in either study, told Lee Billings at Scientific American. "At first we weren't sure exactly what it meant, but we knew we had something exciting". So the only option is to wait for the next generation of space telescopes to be launched in the 2020s and look for gasses in K2-18b's atmosphere that could only be produced by living organisms, according to UCL's Dr Ingo Waldmann. But the new study about the planet's water vapor, published Wednesday in the journal Nature Astronomy, is a major step towards understanding what habitable planets look like outside our solar system. The "super-Earth" K2-18b sits within the habitable zone of its host star, meaning it is not too hot or too cold for liquid water to exist. None have been confirmed yet, however.

This bodes well for the water-bearing planet, as its 33-day orbit brings it about twice as close to its star as Mercury is to the Sun. It might have clouds, but if so, scientists' observations suggest they aren't very thick. They also propose a much more exotic version of the planet.

"It is not a true Earth analogue", the researchers report. Lead author Angelos Tsiaras says it could help determine, "Is the Earth unique?" Even detecting the planet in the first place requires highly sensitive instruments capable of detecting the faint dips in starlight; the spectral absorption lines are also incredibly faint.

The data also indicated the presence of hydrogen and helium in the atmosphere. The range is so large because of various unknown factors, including the temperature of the star and the distance between the star and the planet and the planet's atmosphere and pressure, which is why it's unclear if water exists on the surface.

"This is one of the biggest questions in science and we have always wondered if we are alone in the Universe".

But while the temperature range and presence of water are good signs, K2-18 b isn't necessarily habitable. Its star is relatively inactive, and hasn't put out any flares since scientists started observing the system.

This week, astronomers announced new hope for extraterrestrial habitability: an exoplanet some 110 light-years away from Earth that harbors water in its atmosphere.

This image taken aboard the International Space Station, shows the limb of the Earth at the bottom transitioning into the orange-colored stratosphere, the lowest and most dense portion of the Earth's atmosphere.

Now we have for the first time managed to detect water vapour in the atmosphere of an exoplanet that is potentially habitable. It likely isn't rocky like Earth and doesn't have similar bodies of water. Over time, the flow of charged particles and plasma from the sun stripped Mars' atmosphere away.

K2-18b resides in what is believed to be the habitable zone of its star, but aside from that, the world appears quite a bit different than Earth.

Although the planet sits in the habitable zone of its solar system, scientists say that there is now no way to determine whether there are signs of life. "It's definitely the smallest and coolest planet that we've had a glimpse into the atmosphere of so far".

Much remains unknown about the exoplanet K2-18 b, the researchers stressed. For now, there's no way to know what conditions on its surface are like. What they were looking for were chemical signatures of K2-18b's atmosphere-both whether the planet has an atmosphere at all, and whether that atmosphere contains water.

Whether or not life could exist on K2-18b is unknown, but the discovery of water vapor makes it a promising target for future observations-especially for the James Webb Telescope (JWST), which is now scheduled for launch in 2021 and will be able to detect "biosignatures"-and is possibly an indication that life is present".

"We're going to need more observations", she said.

Altre relazioniGrafFiotech

Discuti questo articolo

Segui i nostri GIORNALE