Astronomers Detect Water in the Atmosphere of Alien World

Studying exoplanets located hundreds of light years away from Earth is a complex task. Not only does it require state-of-the-art technology, but it also requires a lot of patience.

Gathering information about exoplanets from astronomical observations is also a complex task, because the light from the planets host stars is much stronger than the light from the exoplanet, making it extremely difficult for telescopes to see them.

The HR 8799 system contains the first exoplanet to be directly imaged. (NRC-HIA/C. MAROIS/W. M. KECK OBSERVATORY)
The HR 8799 system contains the first exoplanet to be directly imaged. (NRC-HIA/C. MAROIS/W. M. KECK OBSERVATORY)

However, astronomers at the Keck Observatory have taken a massive step forward in exoplanet observation. Using cutting-edge technology, scientists have  detected water in the atmosphere of a planet located 179 light years away from Earth.

The Solar system’s Star is called  HR 8799, and according to astronomical observations it has four planets:HR 8799 b, c, d, and e. The solar system is located in the constellation Pegasus.

HD 8799 is a very odd star for a number of reasons. The star itself is a 30 million-year-old main sequence star, and has strange stellar properties: the star is a member of the  Lambda Boötis (λ Boo) class, a group of peculiar stars with an unusual lack of metals—elements heavier than hydrogen and helium—in their upper atmosphere. It also has has a slight overabundance of carbon and oxygen compared to the Sun (by approximately 30% and 10% respectively).

Exoplanet HR 8799c is about 7 times the size of Jupiter. (W. M. KECK OBSERVATORY/ADAM MAKARENKO/C. ALVAREZ)
Exoplanet HR 8799c is about 7 times the size of Jupiter. (W. M. KECK OBSERVATORY/ADAM MAKARENKO/C. ALVAREZ)

But the star is also noteworthy for another reason: in 2008, astronomers announced that they had directly observed as much as three exoplanets orbiting the star using the Keck and Gemini telescopes.. In 2010, astronomers announced they discovered a fourth planet.

Now, thanks to new, direct, observation of the planet HR 8799 c, first observed in 2008, astronomers have confirmed the presence of water in the atmosphere. The new direct observations have also confirmed a lack of methane.

The direct observations were made possible thanks to a state-of-the-art combination of two telescope technologies at the Keck Observatory, the first one being adaptive optics.

As explained by Science direct, “Adaptive optics counteract the blurring effects of the Earth’s atmosphere. The second is a spectrometer on the Keck 2 telescope called the Near-Infrared Cryogenic Echelle Spectrograph (NIRSPEC), a high-resolution spectrometer that works in infrared light.”

“This type of technology is exactly what we want to use in the future to look for signs of life on an Earth-like planet. We aren’t there yet but we are marching ahead,” says Dimitri Mawet, an associate professor of astronomy at Caltech and a research scientist at JPL, which Caltech manages for NASA, and co-author of the study that presented these findings.

“Right now, with Keck, we can already learn about the physics and dynamics of these giant exotic planets, which are nothing like our own solar system planets,” explained the lead author of the study, Ji Wang.

“We are now more certain about the lack of methane in this planet.”

“This may be due to mixing in the planet’s atmosphere. The methane, which we would expect to be there on the surface, could be diluted if the process of convection is bringing up deeper layers of the planet that don’t have methane,” Wang added

 

The new findings were published in the Astronomical Journal.

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