An
international team comprising researchers at The University of Bern and
the University of Geneva as well as the National Centre of Competence
in Research (NCCR) PlanetS analyzed the atmosphere of one of the most
extreme planets with great depth. The
results from this hot, Jupiter-like planet that was first characterized
with the help of the CHEOPS space telescope, may help astronomers
understand the complexities of many other exoplanets--including
Earth-like planets.
The air of Earth isn't a uniform envelope but rather consists of distinct layers that possess distinct characteristics. The
lowest layer that spans from sea level beyond the highest mountain
peaks, for example--the troposphere--contains most of the water vapor
and is thus the layer in which most weather phenomena occur. The
stratosphere, the layer that is above it, is the one with an ozone
layer, which protects us from sun's dangerous ultraviolet radiation.
In
a recent study that was published in Nature Astronomy, an international
group of researchers headed by researchers from the University of Lund
show for the first time that the atmosphere of one of the most extreme
planets could have similar layers, but with different features.
A sultry and exotic ambience
WASP-189b is a star that is beyond our solar system. It is situated 322 light years away Earth. The
extensive observations conducted by the CHEOPS space telescope in the
year 2020 discovered, among other things, this planet lies 20x closer
the star it hosts as Earth can be to Sun and has a daily temp of about
3200 Celsius. Recent
studies using the HARPS instrument located at la Silla Observatory
situated in Chile this time in the very first instance have allowed the
scientists to look more in-depth inspection of the atmosphere of the
Jupiter-like planet.
"We
measured the light coming from the planet's host star and passing
through the planet's atmosphere. The gasses in its atmosphere absorb
some of the starlight, similar to Ozone absorbing some of the sunlight
in Earth's atmosphere, and thereby leave their characteristic
'fingerprint." Through
the aid of HARPS and HARPS, we could identify the chemical compounds
that were responsible," lead author of the study and doctoral student at
Lund University, Bibiana Prinoth says. Based on the findings of the
research the gases that left their footprints on the WASP-189b's
atmosphere comprised of vanadium, iron, chromium manganese, magnesium,
and iron.
A "Ozone layer" on a scorchingly hot planet?
One of the most interesting substances they discovered is a gas that contains titanium called titanium oxide. Although
titanium oxide is rare in the world of Earth however, it may play a
significant role in the WASP-189b atmosphere, similar to the role of
ozone in the atmosphere of Earth. "Titanium
oxide absorbs short wave radiation, such as ultraviolet radiation. Its
detection could therefore indicate a layer in the atmosphere of
WASP-189b that interacts with the stellar irradiation similarly to how
the Ozone layer does on Earth," study co-author Kevin Heng, a professor
of Astrophysics of the University of Bern and a member of the NCCR
PlanetS, explains.
In
fact, the researchers discovered indications of such a layer as well as
other layers that are located on the extremely hot Jupiter-like planet. "In
our analysis, we saw that the 'fingerprints' of the different gasses
were slightly altered compared to our expectation. We believe that
strong winds and other processes could generate these alterations. And
because the fingerprints of different gasses were altered in different
ways, we think that this indicates that they exist in different
layers--similarly to how the fingerprints of water vapor and ozone on
Earth would appear differently altered from a distance, because they
mostly occur in different atmospheric layers," Prinoth clarifies. These findings could change the way scientists study exoplanets.
A different approach to look at exoplanets
"In
the past, astronomers often assumed that the atmospheres of exoplanets
exist as a uniform layer and try to understand it as such. But our
results demonstrate that even the atmospheres of intensely irradiated
giant gas planets have complex three-dimensional structures," study
co-author and associate senior lecturer at Lund University Jens
Hoeijmakers points out.
"We
are convinced that to be able to fully understand these and other types
of planets--including ones more similar to Earth, we need to appreciate
the three-dimensional nature of their atmospheres. This requires
innovations in data analysis techniques, computer modeling and
fundamental atmospheric theory," Kevin Heng concludes.
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