Press Release

ESO: Media Telecon to Discuss Significant Exoplanet Finding

By SpaceRef Editor
October 15, 2009
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ESO: Media Telecon to Discuss Significant Exoplanet Finding

On Monday 19 October 2009, astronomers will report at the international ESO/CAUP exoplanet conference in Porto, Portugal, on a significant discovery in the field of exoplanets, obtained with the High Accuracy Radial Velocity Planet Searcher, better known as HARPS, the spectrograph for ESO’s 3.6-meter telescope.

ESO will host a media teleconference on Monday 19 October 2009, at 1:45 p.m. CEST (7:45 a.m. EDT in the United States), to be streamed online.

The teleconference participants are:

– Stephane Udry, Geneva Observatory, Switzerland
– Xavier Bonfils, LAOG, Grenoble, France
– Nuno Santos, University of Porto, Portugal

To participate in the teleconference, reporters must get accredited by contacting Henri Boffin by email ( Reporters will need to have access to a computer, with a recent version of Adobe’s Macromedia Flash Player installed and an Internet connection with a minimum bandwidth requirement of 56 kB/s. Further information will be provided to the accredited reporters.

Graphics and supporting information will be shown during the teleconference, and also be available at the start of the news conference at

The ESO/CAUP conference “Towards Other Earths: perspectives and limitations in the ELT era”, takes place in Porto on 19-23 October 2009. This conference discusses the new generation of instruments and telescopes that is now being conceived and built by different teams around the world to allow the discovery of other Earths, especially for the European Extremely Large Telescope (E-ELT). The discoveries are simultaneously presented by Michel Mayor at the international symposium “Heirs of Galileo: Frontiers of Astronomy” in Madrid, Spain.


The HARPS search for southern extra-solar planets XVIII. An Earth-mass planet in the GJ 581 planetary system

M. Mayor, X. Bonfils, T. Forveille, X. Delfosse, S. Udry, J.-L. Bertaux, H. Beust, F. Bouchy, C. Lovis, F. Pepe, C. Perrier, D. Queloz, N. C. Santos

(Submitted on 15 Jun 2009)

The GJ 581 planetary system was already known to harbour three planets, including two super-Earths planets which straddle its habitable zone. We report here the detection of an additional planet – GJ 581e – with a minimum mass of 1.9 M_earth With a period of 3.15 days, it is the innermost planet of the system and has a 5% transit probability. We also correct our previous confusion of the orbital period of GJ 581d (the outermost planet) with a one-year alias, thanks to an extended time span and many more measurements. The revised period is 66.8 days, and locates the semi-major axis inside the habitable zone of the low mass star. The dynamical stability of the 4-planet system imposes an upper bound on the orbital plane inclination. The planets cannot be more massive than approximately 1.6 times their minimum mass.

Comments: 9 pages, A&A Accepted
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:0906.2780v1 [astro-ph.EP]

Submission history
From: Xavier Bonfils [view email]
[v1] Mon, 15 Jun 2009 20:10:15 GMT (1057kb,D)

1. Introduction: HARPS is a vacuum spectrograph designed to measure precise radial velocities, with the specific goal of searching for exoplanets in the Southern hemisphere Mayor et al. (2003). This high-resolution Echelle spectrograph (R=115000) is fiber-fed by the ESO 3.6-meter telescope at La Silla Observatory. The consortium which built this instrument was granted 500 observing nights over five years to conduct a comprehensive search for exoplanets. This large programme addresses several key exoplanet questions, including the characterization of very low mass exoplanets. A significant fraction of the observing time was devoted to the study of planets orbiting stars at the bottom of the main sequence. The M-dwarf sub-programme includes over 100 stars, which form a volume-limited sample. Our HARPS search for southern exoplanets orbiting Mdwarfs is on-going, and has been recently expanded to a larger sample of some 300 low-mass stars.

SpaceRef staff editor.