From The University of Geneva [Université de Genève] (CH)
5.14.24
Émeline Bolmont
Emeline.Bolmont@unige.ch
Assistant professor and director
Astronomy Department
Life in the Universe research Center
Faculty of Sciences UNIGE
Artist’s concept of the exoplanet SPECULOOS-3 b orbiting its ultra-cool red dwarf star. The planet is as big as Earth, while its star is slightly larger than Jupiter, but much more massive. Credit: NASA/JPL-Caltech
An international team of astronomers – including members of the NCCR PlanetS, the University of Geneva (UNIGE) and the University of Bern (UNIBE) – has discovered, for only the second time, an Earth-sized exoplanet (SPECULOOS-3 b) around an ultra-cool Red Dwarf star. Red dwarfs account for 70% of the stars in our galaxy. The small size and lower luminosity of these stars make it easier to analyse any planets in orbit. These planetary systems are of particular interest to astronomers working on the question of life in the Universe, especially those at the UNIGE’s Life in the Universe research Center. The discovery of SPECULOOS-3 b is published today in the journal Nature Astronomy.
The SPECULOOS-3 b exoplanet is about 55 light years from Earth (which is relatively close) and is practically the same size as the blue planet. The comparison ends there, as the newcomer orbits its star in just 17 hours, and the days and nights may never end. In fact, the planet is probably locked in by tidal effects, so that the same side, called the day side, always faces the star, just like the Moon does for the Earth. The night side, on the other hand, is locked in endless darkness.
Despite these “few” differences from our Earth, this type of planet is of particular interest to astronomers, and in particular those at the Life in the Universe research Center (LUC). « SPECULOOS-3 b orbits a red dwarf star, confirms Émeline Bolmont, assistant professor in the astronomy department at the UNIGE, director of the LUC and co-author of the study. The small size of these stars makes it easier to detect small Earth-sized planets around them, and above all to observe any planetary atmospheres. Numerous studies show that life could develop on planets orbiting red dwarfs. They are therefore ideal candidates for us ».
Countless Red Dwarfs all around us.
More than 70% of the stars in the Milky Way are M dwarfs, also known as red dwarfs. These stars are cool and faint compared with our Sun, but they live for a very long time. Stars like our Sun burn for around 10 billion years before transforming into red giants that devour any planets that are too close. M dwarfs burn for 100 billion years or more, perhaps providing an anchor for life and an even longer window for its development.
With an average temperature of around 2600°C, the star SPECULOOS-3 is several thousand degrees cooler than our Sun (5500°C). Detecting such a star – not to mention a planet orbiting it – is a feat in itself, given that it is more than a thousand times less luminous than the Sun. SPECULOOS-3 belongs to the subclass of ultra-cool stars, the darkest and longest-lived. When the universe becomes icy and dark, these stars will be the last to burn.
The SPECULOOS project
As these ultra-cool stars are very faint, their planetary population is largely unexplored today. The SPECULOOS (Search for Planets EClipsing ULtra-cOOl Stars) project, led by Michael Gillon from the University of Liège in Belgium, is designed to change this. Ultra-cool dwarf stars are scattered across the sky, so they have to be observed one by one, over a period of weeks, to have a good chance of detecting transiting planets. To do this, you need a dedicated network of professional telescopes. This is the SPECULOOS concept.
Among the telescopes in this network, the SAINT-EX robotic telescope has been funded in part by the Universities of Geneva and Bern, the two host institutions of the PlanetS National Centre of Competence in Research (NCCR), which has also made a financial contribution to the project.
In addition to SAINT-EX, SPECULOOS has partnerships with the universities of Cambridge, Birmingham, the Massachusetts Institute of Technology and ETH Zürich
An exo-Earth ?
Because of its very short orbit, the SPECULOOS-3 b planet receives almost 16 times more energy per second from its star than the Earth does from the Sun. It is literally bombarded with high-energy radiation. The planet is therefore not in the star’s habitable zone (the place where liquid water can exist on the surface of a planet), unlike certain planets in another ultra-cool red dwarf, TRAPPIST-1, whose system was discovered in 2015 by the TRAPPIST telescope.
Although too close to its star to have liquid water, SPECULOOS-3 b is nonetheless of interest to astronomers. «This planet is an ideal target for the James Webb Space Telescope (JWST), and is even better than the TRAPPIST-1 planets, confirms Émeline Bolmont. The JWST should be able to determine whether the planet has been able to retain an atmosphere despite its proximity to its star. If we find one on this highly irradiated planet, it gives us good hope that one also exists on the planets in TRAPPIST-1’s habitable zone. »
See the full article here.
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The University of Geneva [Université de Genève] (CH) is a public research university located in Geneva, Switzerland.
It was founded in 1559 by John Calvin as a theological seminary and law school. It remained focused on theology until the 17th century, when it became a center for Enlightenment scholarship. In 1873, it dropped its religious affiliations and became officially secular. Today, the university is the third largest university in Switzerland by number of students. In 2009, the University of Geneva celebrated the 450th anniversary of its founding. Almost 40% of the students come from foreign countries.
The university has a diverse student body, with students from over 150 countries. It is also home to numerous research centers and institutes, including the Geneva Centre for Security Policy, the Global Studies Institute, and the Institute of Global Health.
The university holds and actively pursues teaching, research, and community service as its primary objectives. The university has been ranked very highly worldwide by the Shanghai Academic Ranking of World Universities, and by the QS World University Rankings, and the TIMES Higher Education World University Ranking.
During the French annexation of Geneva (1798–1813), the school was reorganized into a more universal format, with the introduction of degrees and its division in faculties. This process of modernization continued into the period of national Restoration.
UNIGE is a member of the League of European Research Universities (EU) (including academic institutions such as University of Amsterdam [Universiteit van Amsterdam] (NL), University of Cambridge (UK), Ruprecht Karl University of Heidelberg, [Ruprecht-Karls-Universität Heidelberg] (DE), University of Helsinki [ Helsingin yliopisto; Helsingfors universitet] (FI) and University of Milan [Università degli Studi di Milano Statale] (IT)). The university is a member of Coimbra Group (EU) and the European University Association (EU).
The University of Geneva is structured in various faculties and interfaculty centers which are representing teaching, research and service to society in the various disciplines.
Faculties
The university is composed of nine faculties:
Faculty of Sciences
Faculty of Medicine
Faculty of Humanities
Faculty Geneva School of Economics and Management (GSEM)
Faculty Geneva School of Social Sciences (G3S)
Faculty of Law (Geneva Law School)
Faculty of Theology
Faculty of Psychology and Education
Faculty of Translation and Interpreting
Interfaculty centers
The university is composed of fourteen interfaculty centers. Amongst others:
Institute for Reformation History (Reformation)
Interfaculty Center for Informatics (computer science)
Institute for Environmental Sciences (energy policy)
The Global Studies Institute
Interfaculty Center of Gerontology (gerontology)
Swiss Center for Affective Sciences (affective science)
Associated institutions
The university has also several partnerships with the nearby institutions, where students at the university may take courses.
Graduate Institute of International and Development Studies (IHEID)
Bossey Ecumenical Institute of the World Council of Churches
Wyss Center for Bio- and Neuro-engineering
Swiss National Supercomputing Centre
Art-Law Centre
Center for Biomedical Imaging (CIBM)
University Centre of Legal Medicine (CURML)
The Institute for Work and Health (IST)
The University of Geneva has had a budget of as much as 760 million. It mostly comes from the cantonal subventions, the other notable contributors being the federal state and the tuition fees.
International partnerships
Students at UNIGE have the possibility to study abroad for a semester or a year during their degree. Partner universities include Free University of Berlin, Harvard Law School, École Normale Supérieure, Trinity College Dublin, Erasmus University of Rotterdam, Université Libre de Bruxelles, King’s College London, McGill University, HEC Montreal, University of Ottawa, University of Oxford, Uppsala University, Johns Hopkins University, University of Michigan, UCLA, University of Southampton, University of Sydney, University of Tokyo.
The key sectors of research at the University of Geneva are sciences (molecular biology, bio-informatics, etc.), elementary physics, astrophysics, economics, social sciences, psychology, chemistry, biochemistry and biophysics.
UNIGE is home to six national research centers: in genetics (Frontiers in Genetics), in material sciences (MaNEP), in study of emotions (Affective Sciences), in chemical biology (with EPFL), in study of mental illness (Synaptic, with EPFL and Unil), in study of life path (with Unil). UNIGE also carries research in international studies since the creation in 2013 of the Global Studies Institute, in finance with the Geneva Finance Research Institute, and in environmental studies, with the creation in 2009 of the Institut des sciences de l’environnement.
Famous discoveries have been made by researcher working at UNIGE including the discoveries of extrasolar planets by Michel Mayor, and of quantum teleportation by Nicolas Gisin.
The university has hosted several Nobel laureates as students, researchers and/or professors. It has also hosted or graduated Fields Medal laureates.