Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Astronomers find world with thick, inhospitable atmosphere and an icy heart

18.12.2009
In this week's issue of Nature, astronomers announce the discovery of a planet around the nearby, low-mass star GJ1214 [2].

It is the second time a transiting super-Earth has been detected, after the recent discovery of the planet Corot-7b [3]. A transit occurs when the planet's orbit is aligned so that we see it crossing the face of its parent star. The newly discovered planet has a mass about six times that of our terrestrial home and 2.7 times its radius, falling in size between the Earth and the ice giants of the Solar System, Uranus and Neptune.

Although the mass of GJ1214b is similar to that of Corot-7b, its radius is much larger, suggesting that the composition of the two planets must be quite different. While Corot-7b probably has a rocky core and may be covered with lava, astronomers believe that three quarters of GJ1214b is composed of water ice, the rest being made of silicon and iron.

GJ1214b orbits its star once every 38 hours at a distance of only two million kilometres — 70 times closer to its star than the Earth is to the Sun. "Being so close to its host star, the planet must have a surface temperature of about 200 degrees Celsius, too hot for water to be liquid," says David Charbonneau, lead author of the paper reporting the discovery.

When the astronomers compared the measured radius of GJ1214b with theoretical models of planets, they found that the observed radius exceeds the models' predictions: there is something more than the planet's solid surface blocking the star's light — a surrounding atmosphere, 200 km thick. "This atmosphere is much thicker than that of the Earth, so the high pressure and absence of light would rule out life as we know it," says Charbonneau, "but these conditions are still very interesting, as they could allow for some complex chemistry to take place."

"Because the planet is too hot to have kept an atmosphere for long, GJ1214b represents the first opportunity to study a newly formed atmosphere enshrouding a world orbiting another star," adds team member Xavier Bonfils. "Because the planet is so close to us, it will be possible to study its atmosphere even with current facilities."

The planet was first discovered as a transiting object within the MEarth project, which follows about 2000 low-mass stars to look for transits by exoplanets [4]. To confirm the planetary nature of GJ1214b and to obtain its mass (using the so-called Doppler method), the astronomers needed the full precision of the HARPS spectrograph, attached to ESO's 3.6-metre telescope at La Silla. An instrument with unrivalled stability and great precision, HARPS is the world's most successful hunter for small exoplanets.

"This is the second super-Earth exoplanet for which the mass and radius could be obtained, allowing us to determine the density and to infer the inner structure," adds co-author Stephane Udry. "In both cases, data from HARPS was essential to characterise the planet."

"The differences in composition between these two planets are relevant to the quest for habitable worlds," concludes Charbonneau. If super-Earth planets in general are surrounded by an atmosphere similar to that of GJ1214b, they may well be inhospitable to the development of life as we know it on our own planet.

Notes

[1] A super-Earth is defined as a planet between one and ten times the mass of the Earth. An exoplanet is a planet orbiting a star other than the Sun.

[2] The star GJ1214 is five times smaller than our Sun and intrinsically three hundred times less bright.

[3] Corot-7b is the smallest and fastest-orbiting exoplanet known and has a density quite similar to the Earth's, suggesting a solid, rocky world. Discovered by the CoRoT satellite as a transiting object, its true nature was revealed by HARPS (ESO 33/09).

[4] The MEarth project uses an armada of eight small telescopes each with a diameter of 40 cm, located on top of Mount Hopkins, Arizona, USA. MEarth looks for stars that change brightness. The goal is to find a planet that crosses in front of, or transits, its star. During such a mini-eclipse, the planet blocks a small portion of the star's light, making it dimmer. NASA's Kepler mission also uses transits to look for Earth-sized planets orbiting Sun-like stars. However, such systems dim by only one part in ten thousand. The higher precision required to detect the drop means that such worlds can only be found from space. In contrast, a super-Earth transiting a small, red dwarf star yields a greater proportional decrease in brightness and a stronger signal that is detectable from the ground.

More information

This research was presented in a paper appearing this week in Nature ("A Super-Earth Transiting a Nearby Low-Mass Star", by David Charbonneau et al.).

The team is composed of David Charbonneau, Zachory K. Berta, Jonathan Irwin, Christopher J. Burke, Philip Nutzman, Lars Buchhave, David W. Latham, Ruth A. Murray-Clay, Matthew J. Holman, and Emilio E. Falco (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), Christophe Lovis, Stephane Udry, Didier Queloz, Francesco Pepe, and Michel Mayor (Observatoire de l'Université de Genève, Switzerland), Xavier Bonfils, Xavier Delfosse, and Thierry Forveille (University Joseph Fourier — Grenoble 1/CNRS, LOAG, Grenoble, France), and Joshua N. Winn (Kavli Institute for Astrophysics and Space Research, MIT, Cambridge, USA).

ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world's most productive astronomical observatory. 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 Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world's most advanced visible-light astronomical observatory, and VISTA, the world's largest survey telescope. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become "the world's biggest eye on the sky".

Links

- More info: Exoplanet Media Kit: http://www.eso.org/outreach/products/publ/brochures/pdf/exoplanet_lowres.pdf

Contacts

Stéphane Udry
Geneva University, Switzerland
Geneva, Switzerland
Tel: +41 22 379 2467
Email: stephane.udry@unige.ch
Xavier Bonfils
Université Joseph Fourier - Grenoble 1 / CNRS, Laboratoire d'Astrophysique de Grenoble (LAOG), France France
Tel: +33 47 65 14 215
Email: xavier.bonfils@obs.ujf-grenoble.fr
David Charbonneau
Harvard-Smithsonian Center for Astrophysics
Cambridge, USA
Tel: +1 617 496 6515
Email: dcharbon@cfa.harvard.edu

Dr. Henri Boffin | EurekAlert!
Further information:
http://www.eso.org

More articles from Physics and Astronomy:

nachricht Studying fundamental particles in materials
17.01.2017 | Max-Planck-Institut für Struktur und Dynamik der Materie

nachricht Seeing the quantum future... literally
16.01.2017 | University of Sydney

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: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Water - as the underlying driver of the Earth’s carbon cycle

17.01.2017 | Earth Sciences

Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

17.01.2017 | Materials Sciences

Smart homes will “LISTEN” to your voice

17.01.2017 | Architecture and Construction

VideoLinks
B2B-VideoLinks
More VideoLinks >>>