Annual Report 2019

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An extreme gas giant
Kevin Heng

"Ultimately, we want to use our research to fathom the origin and development of the solar system as well as the origin of life."

Matter and the universe

Rare-Earth metals in the atmosphere of an exoplanet

KELT-9b is the hottest exoplanet known to date. In the summer of 2018, a team of astronomers from the universities of Bern and Geneva found signatures of gaseous iron and titanium in its atmosphere. In the spring of 2019, the same researchers were also able to detect traces of vaporized sodium, magnesium, chromium, and the rare-Earth metals scandium and yttrium.

 

KELT-9 is a star in the constellation Cygnus (Swan) and is almost twice as hot as the Sun. Its exoplanet KELT-9b orbits very closely around its star and is thus what is referred to as a hot Jupiter, in fact exemplifying the most extreme of its kind. Its atmosphere reaches temperatures of around 4,000 °C. In such heat, all elements are almost completely vaporized and molecules are broken apart into their constituent atoms. This means that the atmosphere of KELT-9b contains no clouds or aerosols and the sky is clear, mostly transparent to light from its star.

The atoms in the atmosphere of the exoplanet absorb part of the light of the star. Each atom thus has a unique "fingerprint" of colors that it absorbs. These fingerprints can be measured with a sensitive spectrograph mounted on a large telescope, allowing astronomers to discern the chemical composition of the atmospheres of planets that are many light years away.

Back in August 2018, a team of researchers from the National Centre of Competence in Research PlanetS of the universities of Bern and Geneva made an interesting discovery with this technology: “Using the HARPS-North spectrograph on the Italian National Galileo Telescope on the island of La Palma, we found iron and titanium atoms in the hot atmosphere of KELT-9b," explains Kevin Heng, Director and Professor at the Center for Space and Habitability (CSH) at the University of Bern and a member of the National Centre of Competence in Research PlanetS. 

Did you know?

"Exoplanets are planets outside our solar system that orbit other stars. Since the discovery of the first exoplanets in the mid-90s, well over 3,000 exoplanets have been discovered."

The exoplanet as a treasure trove

The team observed the KELT-9 system for a second time, with the goal of confirming their previous detections, but also to search for additional elements. Their survey included 73 atoms, among which some so-called rare-Earth metals. These metals are less common on Earth, but are applied in advanced materials and devices. Jens Hoeijmakers, PlanetS postdoc jointly appointed between Bern and Geneva Observatory, says: “We predicted that the spectrum of this planet could well be a treasure trove where we would find elements which have not been observed in the atmosphere of an exoplanet before.”

The researchers indeed found strong signals of vaporized sodium, magnesium, chromium and the rare-Earth metals scandium and yttrium in the spectrum of the planet - although the latter three had never been detected in the atmosphere of an exoplanet before. “Based on our analyses, we are now able to estimate at what altitude in the planet’s atmosphere these atoms are absorbing light", says Jens Hoeijmakers. In addition, more is now known about wind patterns high up in the atmosphere that blow atoms from one hemisphere to the other.

"Using this technology, we want to find out more about the atmosphere of these exoplanets as well as other planets that have temperatures almost as high as that of KELT-9b,” explains Jens Hoeijmakers. Kevin Heng adds: "The chances are good that one day we will find so-called biosignatures, i.e. signs of life, on an exoplanet using the same techniques that we are applying today. Ultimately, we want to use our research to fathom the origin and development of the solar system as well as the origin of life."

How to explore exoplanets

Kevin Heng, Director and Professor at the Center for Space and Habitabilty (CSH) at the University of Bern, and Jens Hoeijmakers, PlanetS postdoc jointly appointed between Bern and Geneva Observatory, talk about exoplanet research. © University of Bern

Artist’s impression of KELT-9b und its host star KELT-9. © NASA/JPL-Caltech
Artist’s impression of a sunset over KELT-9b. Under this blazing star, the atmosphere of the planet is warm enough to glow in reddish-orange tones and to vaporise heavy metals such as iron and titanium. © Denis Bajram
A high-resolution image of the spectrum of our Sun. © N.A.Sharp, NOAO/NSO/Kitt Peak FTS/AURA/NSF
The Galileo National Telescope (TNG) of the Italian National Institute of Astrophysics (INAF) on the Canary Island La Palma. © INAF-TNG

Center for Space and Habitability CSH

The mission of the Center for Space and Habitability (CSH) is to foster dialogue and interaction between the various scientific disciplines interested in the formation, detection and characterization of other worlds, the definition of life and our search for it elsewhere in the universe, and its implications for disciplines outside of the sciences. The members and affiliates include astronomers and astrophysicists, atmospheric, climate and planetary scientists, geologists and geophysicists, biologists, chemists and philosophers. The CSH is home to the CSH and Bernoulli Fellowships, which host young, dynamic and talented researchers from all over the world to conduct independent research.

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Bernese space exploration: part of the world's elite since the first moon landing

When Buzz Aldrin became the second man to step out of the lunar module on July 21, 1969, the first thing he did was to unfurl the University of Bern’s solar wind sail and plant it into the ground on the moon, even before doing the same with the American flag. This Solarwind Composition Experiment (SWC), which was planned and evaluated by Prof. Dr. Johannes Geiss and his team at the Physics Institute of the University of Bern, was a first major highlight in the history of Bernese space exploration.

Bernese space exploration has been part of the world’s elite ever since. When viewed in terms of figures, it reveals an impressive balance sheet: Instruments have flown into the upper atmosphere and ionosphere with rockets 25 times (1967-1993), into the stratosphere on balloon flights 9 times (1991-2008), more than 30 instruments have accompanied space probes on their missions, and with CHEOPS, the University of Bern is sharing responsibility with ESA for an entire mission.

The successful work of the Department of Space Research and Planetary Sciences from the Physics Institute of the University of Bern was consolidated by the founding of a university competence center, the Center for Space and Habitability (CSH). The Swiss Nation Fund also awarded the University of Bern the the National Centre for Competence in Research (NCCR) PlanetS, which it manages together with the University of Geneva.

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