Extreme exoplanet has a complex and exotic atmosphere

Date:
January 28, 2022
Source:
University of Bern
Summary:
An international team analyzed the atmosphere of one of the most
extreme known planets in great detail. 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.



FULL STORY ==========================================================================
An international team including researchers from 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 known planets in great detail. 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 atmosphere of Earth is not a uniform envelope but consists of distinct layers that each have characteristic properties. The lowest layer that
spans from sea level beyond the highest mountain peaks, for example --
the troposphere -, contains most of the water vapour and is thus the
layer in which most weather phenomena occur. The layer above it -- the stratosphere -- is the one that contains the famous ozone layer that
shields us from the Sun's harmful ultraviolet radiation.

In a new study that appeared in the journal Nature Astronomy, an
international team of researchers led by the University of Lund show
for the first time that the atmosphere of one of the most extreme known
planets may have similarly distinct layers as well -- albeit with very different characteristics.

An exotic cocktail for an atmosphere WASP-189b is a planet outside our own solar system, located 322 light years from Earth. Extensive observations
with the CHEOPS space telescope in 2020 revealed among other things that
the planet is 20 times closer to its host star than Earth is to the Sun
and has a daytime temperature of 3200 degrees Celsius.

More recent investigations with the HARPS spectrograph at the La Silla Observatory in Chile now for the first time allowed the researchers to
take a closer look at the atmosphere of this Jupiter-like planet.

"We measured the light coming from the planet's host star and
passing through the planet's atmosphere. The gases 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'. With the help of HARPS, we were able to identify
the corresponding substances," lead author of the study and doctoral
student at Lund University, Bibiana Prinoth, explains. According to the researchers, the gases that left their fingerprints in the atmosphere
of WASP-189b included iron, chromium, vanadium, magnesium and manganese.

An "Ozone layer" on a blisteringly hot planet? One particularly
interesting substance the team found is a gas containing titanium:
titanium oxide. While titanium oxide is very scarce on Earth, it could
play an important role in the atmosphere of WASP-189b -- similar to
that of ozone in Earth's atmosphere. "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 at the University
of Bern and a member of the NCCR PlanetS, explains.

Indeed, the researchers found hints of such a layer and other layers
on the ultra-hot Jupiter-like planet. "In our analysis, we saw that the 'fingerprints' of the different gases 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 gases were altered in different
ways, we think that this indicates that they exist in different layers
-- similarly to how the fingerprints of water vapour and ozone on Earth
would appear differently altered from a distance, because they mostly
occur in different atmospheric layers," Prinoth explains. These results
may change how astronomers investigate exoplanets.

A different way 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 modelling
and fundamental atmospheric theory," Kevin Heng concludes.

========================================================================== Story Source: Materials provided by University_of_Bern. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Bibiana Prinoth, H. Jens Hoeijmakers, Daniel Kitzmann, Elin Sandvik,
Julia V. Seidel, Monika Lendl, Nicholas W. Borsato, Brian Thorsbro,
David R. Anderson, David Barrado, Kateryna Kravchenko, Romain
Allart, Vincent Bourrier, Heather M. Cegla, David Ehrenreich,
Chloe Fisher, Christophe Lovis, Andrea Guzma'n-Mesa, Simon Grimm,
Matthew Hooton, Brett M. Morris, Maria Oreshenko, Lorenzo Pino,
Kevin Heng. Titanium oxide and chemical inhomogeneity in the
atmosphere of the exoplanet WASP-189 b. Nature Astronomy, 2022;
DOI: 10.1038/s41550-021-01581-z ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220128141342.htm

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