press release
October 13, 2022
Using the European Southern Observatory’s (ESO) Very Large Telescope (VLT), astronomers have discovered the heaviest element ever found in the atmosphere of an exoplanet: barium. The discovery of barium at high altitudes in the atmospheres of the ultra-hot gas giants WASP-76 b and WASP-121 b – two exoplanets orbiting stars outside our Solar System – came as a surprise. This unexpected discovery raises questions about what these exotic atmospheres might be like.
“The really puzzling and paradoxical thing is this: why is there such a heavy element in the upper layers of the atmosphere of these planets?“, says Tomás Azevedo Silva, doctoral student at the University of Porto and the Instituto de Astrofísica e Ciências do Espaço (IA) in Portugal, who today Astronomy and astrophysics study published.
WASP-76 b And WASP-121 b are not ordinary exoplanets. Both are considered ultracalled Jupiter known because they are comparable in size to Jupiter and at the same time have extremely high surface temperatures, over 1000 °C. The reason for this is the proximity of their host stars, which also means that an orbit around the respective star takes only one or two days. This leads to quite exotic properties of these planets; for WASP-76 b, for example, astronomers suspect that it Iron is raining.
Yet scientists were surprised to find WASP-76 b and WASP-121 b in the upper atmosphere. barium to find that it is 2.5 times heavier than iron.”Given the strong gravity of planets, one might expect heavy elements like barium to fall rapidly into the lower layers of the atmosphere.“, explains co-author Olivier Demangeon, also a researcher at the University of Porto and IA.
“In a sense, it was an “accidental” discovery.said Azevedo Silva.We weren’t expecting or looking for barium. We had to make sure it was actually coming from the planet, because it had never been detected on an exoplanet before.“
The fact that barium was detected in the atmospheres of these two ultra-hot Jupiters suggests that this class of planets may be even stranger than previously thought. While we occasionally see barium in our skies as a bright green in fireworks, the question for researchers is what natural process could cause this heavy element to be present at such high altitudes on these exoplanets.At the moment we do not yet know clearly what the mechanisms are” explains Démangeon.
Ultra-hot Jupiters are extremely useful for studying the atmospheres of exoplanets. As Démangeon explains: “Because they are gaseous and hot, their atmospheres extend very widely and are therefore easier to observe and study than those of smaller or colder planets.“
Determining the composition of an exoplanet’s atmosphere requires highly specialized equipment. The team took advantage of this ESPRESSOinstrument at ESO’s VLT in Chile to analyse starlight filtered through the atmospheres of WASP-76 b and WASP-121 b.
These new results show that we have only scratched the surface of the mysteries of exoplanets. With future instruments such as the high-resolution ArmazoNes high-dispersion Echelle spectrograph (ANDES), astronomers will be able to study the atmospheres of large and small exoplanets, including those of rocky Earth-like planets, in much greater detail. ANDES will be involved in the upcoming Extremely Large Telescope (ELT) from ESO are used. They can thus gather further clues about the properties of these strange worlds.
More information
This study was presented in the publication “Detection of barium in the atmospheres of ultra-hot gas giants WASP-76b & WASP-121b”, published in Astronomy and astrophysics appears (doi: 10.1051/0004-6361/202244489).
The team is composed of T. Azevedo Silva (Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, Portugal (IA/UPorto, CAUP) and Departamento de Física e Astronomia Faculdade de Ciências, Universidade do Porto, Portugal (FCUP)) , ODS. Demangeon (IA/UPorto, CAUP and FCUP), NC Santos (IA/UPorto, CAUP and FCUP), R. Allart (Department of Physics and Institute for the Study of Exoplanets, University of Montreal, Canada and University Astronomical Observatory of Geneva, Switzerland (UNIGE)), F. Borsa (INAF – Osservatorio Astronomico di Brera, Italy), E. Cristo (IA/UPorto, CAUP and FCUP), E. Esparza-Borges (Instituto de Astrofísica de Canarias, Spain ( IAC) and Departamento de Astrofísica, Universidad de La Laguna, Tenerife, Spain (IAC-ULL)), JV Seidel (European Southern Observatory, Chile (ESO Chile)), E. Palle (IAC), SG Sousa (IA/UPorto) , H.M. Tabernero (Centro de Astrobiología, CSIC-INTA, Spain (CSIC-INTA)), MR Zapatero Osorio (CSIC-INTA), S. Cristiani (INAF – Osservatorio Astronomico di Trieste, Italy (INAF Trieste)), F. Pepe (UNIGE) , R. Rebolo (IAC and IAC-ULL), V. Adibekyan (IA/UPorto and FCUP), Y. Alibert (Institute of Physics, University of Bern, Switzerland), SCC Barros (IA/UPorto and FCUP), V. Bourrier (UNIGE), P. Di Marcantonio (INAF Trieste), V. D’Odorico (INAF Trieste, Scuola Normale Superiore, Italy and Institute for Fundamental Physics of the Universe, Trieste, Italy (IFPU)), D. Ehrenreich ( UNIGE and Center Life in the Universe, Faculty of Sciences of the University of Geneva, Switzerland), P. Figueira (UNIGE and IA/UPorto), JI González Hernández (IAC and Universidad de La Laguna, Departamento de Astrofísica, Spain), CJAP Martins (UA/UPorto and Centro de Astrofísica da Universidade do Porto, Portugal), A. Mehner (ESO Chile ), G. Micela (INAF – Osservatorio Astronomico di Palermo, Italy), P. Molaro (INAF Trieste and IFPU), D. Mounzer (UNIGE), NJ Nunes (Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências da Universidade de Lisboa and Department of Sciences, Faculdade de Ciências da Universidade de Lisboa, Portugal), A. Sozzetti (INAF – Osservatorio Astrofisico di Torino, Italy), A. Suárez Mascareño (IAC and IAC-ULL) and S. Udry (UNIGE).
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Contact details
Tomas Azevedo Silva
Instituto de Astrofisica e Ciências do Espaço, Faculdade de Ciências, University of Porto
Porto, Portugal
E-mail: Tomas.Silva@astro.up.pt
Olivier Démangeon
Instituto de Astrofisica e Ciências do Espaço, Faculdade de Ciências, University of Porto
Porto, Portugal
Tel: +351 226 089 855
E-mail: olivier.demangeon@astro.up.pt
Nuno Santos
Instituto de Astrofisica e Ciências do Espaço, Faculdade de Ciências, University of Porto
Porto, Portugal
E-mail: Nuno.Santos@astro.up.pt
Maria Rosa Zapatero Osorio
Astrobiology Center (CSIC-INTA)
Madrid, Spain
E-mail: mosorio@cab.inta-csic.es
Hugo Tabernero
Astrobiology Center (CSIC-INTA)
Madrid, Spain
E-mail: htabernero@cab.inta-csic.es
Jonay Gonzalez Henández
Institute of Astrophysics of the Canary Islands
Tenerife, Spain
E-mail: jonay@iac.es
Alejandro Suarez Mascareño
Institute of Astrophysics of the Canary Islands
Tenerife, Spain
E-mail: alejandro.suarez.mascareno@iac.es
Paolo Molaro
INAF Astronomical Observatory of Trieste
Trieste, Italy
E-mail: paolo.molaro@inaf.it
Baptiste Lavie
University of Geneva
Geneva, Switzerland
E-mail: Baptiste.Lavie@unige.ch
Juan Carlos Muñoz Mateos
ESO Media Manager
Garching near Munich, Germany
Tel: +49 89 3200 6176
E-mail: press@eso.org
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ESO Science Outreach Network and House of Astronomy
Heidelberg, Germany
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This is a translation of ESO press release eso2213.