Forum für Wissenschaft, Industrie und Wirtschaft

Hauptsponsoren:     3M 


Lightest exoplanet yet discovered

Well-known exoplanet researcher Michel Mayor today announced the discovery of the lightest exoplanet found so far.

The planet, “e”, in the famous system Gliese 581, is only about twice the mass of our Earth. The team also refined the orbit of the planet Gliese 581 d, first discovered in 2007, placing it well within the habitable zone, where liquid water oceans could exist.

These amazing discoveries are the outcome of more than four years of observations using the most successful low-mass-exoplanet hunter in the world, the HARPS spectrograph attached to the 3.6-metre ESO telescope at La Silla, Chile.

“The holy grail of current exoplanet research is the detection of a rocky, Earth-like planet in the ‘habitable zone’ — a region around the host star with the right conditions for water to be liquid on a planet’s surface”, says Michel Mayor from the Geneva Observatory, who led the European team to this stunning breakthrough.

Planet Gliese 581 e orbits its host star – located only 20.5 light-years away in the constellation Libra (“the Scales”) — in just 3.15 days. “With only 1.9 Earth-masses, it is the least massive exoplanet ever detected and is, very likely, a rocky planet”, says co-author Xavier Bonfils from Grenoble Observatory.

Being so close to its host star, the planet is not in the habitable zone. But another planet in this system appears to be. From previous observations — also obtained with the HARPS spectrograph at ESO’s La Silla Observatory and announced two years ago — this star was known to harbour a system with a Neptune-sized planet (ESO 30/05) and two super-Earths (ESO 22/07). With the discovery of Gliese 581 e, the planetary system now has four known planets, with masses of about 1.9 (planet e), 16 (planet b), 5 (planet c), and 7 Earth-masses (planet d). The planet furthest out, Gliese 581 d, orbits its host star in 66.8 days. “Gliese 581 d is probably too massive to be made only of rocky material, but we can speculate that it is an icy planet that has migrated closer to the star,” says team member Stephane Udry. The new observations have revealed that this planet is in the habitable zone, where liquid water could exist. “‘d’ could even be covered by a large and deep ocean — it is the first serious 'water world' candidate,” continued Udry.

The gentle pull of an exoplanet as it orbits the host star introduces a tiny wobble in the star’s motion — only about 7 km/hour, corresponding to brisk walking speed — that can just be detected on Earth with today’s most sophisticated technology. Low-mass red dwarf stars such as Gliese 581 are potentially fruitful hunting grounds for low-mass exoplanets in the habitable zone. Such cool stars are relatively faint and their habitable zones lie close in, where the gravitational tug of any orbiting planet found there would be stronger, making the telltale wobble more pronounced. Even so, detecting these tiny signals is still a challenge, and the discovery of Gliese 581 e and the refinement of Gliese 581 d’s orbit were only possible due to HARPS’s unique precision and stability.

“It is amazing to see how far we have come since we discovered the first exoplanet around a normal star in 1995 — the one around 51 Pegasi,” says Mayor. “The mass of Gliese 581 e is 80 times less than that of 51 Pegasi b. This is tremendous progress in just 14 years.”

The astronomers are confident that they can still do better. “With similar observing conditions an Earth-like planet located in the middle of the habitable zone of a red dwarf star could be detectable,” says Bonfils. “The hunt continues.”

This discovery was announced today at the JENAM conference during the European Week of Astronomy & Space Science, which is taking place at the University of Hertfordshire, UK. The results have also been submitted for publication in the research journal Astronomy & Astrophysics (“The HARPS search for southern extra-solar planets: XVIII. An Earth-mass planet in the GJ 581 planetary system”, by Mayor et al., 2009).
The team is composed of M. Mayor, S. Udry, C. Lovis, F. Pepe and D. Queloz (Geneva Observatory, Switzerland), X. Bonfils, T. Forveille , X. Delfosse, H. Beust and C. Perrier (LAOG, France), N. C. Santos (Centro de Astrofisica,Universidade de Porto), F. Bouchy (IAP, Paris, France) and J.-L. Bertaux (Service d’Aéronomie du CNRS, Verrières-le-Buisson, France).

ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in the Atacama Desert region of Chile: La Silla, Paranal and Chajnantor.

Michel Mayor
Geneva University, Switzerland
E-mail: michel.mayor (at)
Prof. Mayor will attend the JENAM conference from 20 to 21 April and can be reached by phone through the JENAM press centre.

Xavier Bonfils, Thierry Forveille
Grenoble Observatory, France
Phone: +33 476 63 55 27, +33 4 76 51 42 06
E-mail: xavier.bonfils (at), thierry.forveille(at)
Stephane Udry
Geneva University, Switzerland
Phone: +41 22 379 2467
E-mail: stephane.udry (at)

Dr. Henri Boffin | EurekAlert!
Further information:

More articles from Physics and Astronomy:

nachricht Appreciating the classical elegance of time crystals
20.09.2019 | ETH Zurich Department of Physics

nachricht 'Nanochains' could increase battery capacity, cut charging time
20.09.2019 | Purdue University

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: 'Nanochains' could increase battery capacity, cut charging time

How long the battery of your phone or computer lasts depends on how many lithium ions can be stored in the battery's negative electrode material. If the battery runs out of these ions, it can't generate an electrical current to run a device and ultimately fails.

Materials with a higher lithium ion storage capacity are either too heavy or the wrong shape to replace graphite, the electrode material currently used in...

Im Focus: Nervenzellen feuern Hirntumorzellen zum Wachstum an

Heidelberger Wissenschaftler und Ärzte beschreiben aktuell im Fachjournal „Nature“, wie Nervenzellen des Gehirns mit aggressiven Glioblastomen in Verbindung treten und so das Tumorwachstum fördern / Mechanismus der Tumor-Aktivierung liefert Ansatzpunkte für klinische Studien

Nervenzellen geben ihre Signale über Synapsen – feine Zellausläufer mit Kontaktknöpfchen, die der nächsten Nervenzelle aufliegen – untereinander weiter....

Im Focus: Stevens team closes in on 'holy grail' of room temperature quantum computing chips

Photons interact on chip-based system with unprecedented efficiency

To process information, photons must interact. However, these tiny packets of light want nothing to do with each other, each passing by without altering the...

Im Focus: Happy hour für die zeitaufgelöste Kristallographie

Ein Forschungsteam vom Max-Planck-Institut für Struktur und Dynamik der Materie (MPSD), der Universität Hamburg und dem European Molecular Biology Laboratory (EMBL) hat eine neue Methode entwickelt, um Biomoleküle bei der Arbeit zu beobachten. Sie macht es bedeutend einfacher, enzymatische Reaktionen auszulösen, da hierzu ein Cocktail aus kleinen Flüssigkeitsmengen und Proteinkristallen angewandt wird. Ab dem Zeitpunkt des Mischens werden die Proteinstrukturen in definierten Abständen bestimmt. Mit der dadurch entstehenden Zeitraffersequenz können nun die Bewegungen der biologischen Moleküle abgebildet werden.

Die Funktionen von Biomolekülen werden nicht nur durch ihre molekularen Strukturen, sondern auch durch deren Veränderungen bestimmt. Mittels der...

Im Focus: Happy hour for time-resolved crystallography

Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Hamburg and the European Molecular Biology Laboratory (EMBL) outstation in the city have developed a new method to watch biomolecules at work. This method dramatically simplifies starting enzymatic reactions by mixing a cocktail of small amounts of liquids with protein crystals. Determination of the protein structures at different times after mixing can be assembled into a time-lapse sequence that shows the molecular foundations of biology.

The functions of biomolecules are determined by their motions and structural changes. Yet it is a formidable challenge to understand these dynamic motions.

Alle Focus-News des Innovations-reports >>>



Industrie & Wirtschaft

92. Neurologie-Kongress: Mehr als 6500 Neurologen in Stuttgart erwartet

20.09.2019 | Veranstaltungen

Frische Ideen zur Mobilität von morgen

20.09.2019 | Veranstaltungen

Thermodynamik – Energien der Zukunft

19.09.2019 | Veranstaltungen

Wissenschaft & Forschung
Weitere VideoLinks im Überblick >>>
Aktuelle Beiträge

Ferroelektrizität verbessert Perowskit-Solarzellen

20.09.2019 | Energie und Elektrotechnik

HD-Mikroskopie in Millisekunden

20.09.2019 | Biowissenschaften Chemie

Kinobilder aus lebenden Zellen: Forscherteam aus Jena und Bielefeld 
verbessert superauflösende Mikroskopie

20.09.2019 | Medizintechnik

Weitere B2B-VideoLinks
im innovations-report
in Kooperation mit academics