Andrew Yee
May 18th 06, 12:30 AM
ESO Education and Public Relations Dept.
--------------------------------------------------------------
Text with all links and the photos are available on the ESO
Website at URL:
http://www.eso.org/outreach/press-rel/pr-2006/pr-18-06.html
--------------------------------------------------------------
Contact:
Christophe Lovis and Michel Mayor
Observatoire de l'Universitde Gene, Switzerland
Phone: +41 22 379 24 07, +41 22 379 24 60
Yann Alibert and Willy Benz
Physikalisches Institut der Universit Bern, Switzerland
Phone: +41 31 631 44 27, +41 31 631 44 03
Under embargo till 17 May 19:00 CET
ESO Science release 18/06
Trio of Neptunes and their Belt
HARPS Instrument Finds Unusual Planetary System
Using the ultra-precise HARPS spectrograph on ESO's 3.6-m telescope
at La Silla (Chile), a team of European astronomers have discovered
that a nearby star is host to three Neptune-mass planets. The
innermost planet is most probably rocky, while the outermost is
the first known Neptune-mass planet to reside in the habitable zone.
This unique system is likely further enriched by an asteroid belt.
"For the first time, we have discovered a planetary system composed
of several Neptune-mass planets", said Christophe Lovis, from the
Geneva Observatory and lead-author of the paper presenting the
results [1].
During more than two years, the astronomers carefully studied
HD 69830, a rather inconspicuous nearby star slightly less massive
than the Sun. Located 41 light-years away towards the constellation
of Puppis (the Stern), it is, with a visual magnitude of 5.95, just
visible with the unaided eye. The astronomers' precise radial-
velocity measurements [2] allowed them to discover the presence of
three tiny companions orbiting their parent star in 8.67, 31.6 and
197 days.
"Only ESO's HARPS instrument installed at the La Silla Observatory,
Chile, made it possible to uncover these planets", said Michel
Mayor, also from Geneva Observatory, and HARPS Principal
Investigator. "Without any doubt, it is presently the world's
most precise planet-hunting machine" [3].
The detected velocity variations are between 2 and 3 metres per
second, corresponding to about 9 km/h! That's the speed of a person
walking briskly. Such tiny signals could not have been distinguished
from 'simple noise' by most of today's available spectrographs.
The newly found planets have minimum masses between 10 and 18 times
the mass of the Earth. Extensive theoretical simulations favour an
essentially rocky composition for the inner planet, and a rocky/gas
structure for the middle one. The outer planet has probably accreted
some ice during its formation, and is likely to be made of a
rocky/icy core surrounded by a quite massive envelope. Further
calculations have also shown that the system is in a dynamically
stable configuration.
The outer planet also appears to be located near the inner edge of
the habitable zone, where liquid water can exist at the surface of
rocky/icy bodies. Although this planet is probably not Earth-like
due to its heavy mass, its discovery opens the way to exciting
perspectives.
"This alone makes this system already exceptional", said Willy Benz,
from Bern University, and co-author. "But the recent discovery by
the Spitzer Space Telescope that the star most likely hosts an
asteroid belt is adding the cherry to the cake."
With three roughly equal-mass planets, one being in the habitable
zone, and an asteroid belt, this planetary system shares many
properties with our own solar system.
"The planetary system around HD 69830 clearly represents a Rosetta
stone in our understanding of how planets form", said Michel Mayor.
"No doubt it will help us better understand the huge diversity we
have observed since the first extra-solar planet was found 11
years ago."
High resolution images and their captions are available at
http://www.eso.org/outreach/press-rel/pr-2006/phot-18-06.html
Video footage and animations are also available at
http://www.eso.org/outreach/press-rel/pr-2006/vid-18-06.html
Notes
[1]: These results appear in the 18 May issue of the research
journal Nature ("Discovery of an extrasolar planetary system with
three Neptune-Mass Planets", by C. Lovis et al.). The team is
composed of Christophe Lovis, Michel Mayor, Francesco Pepe, Didier
Queloz, and Sthane Udry (Observatoire de l'Universitde Gene,
Switzerland), Nuno C. Santos (Observatoire de l'Universitde
Gene, Switzerland, Centro de Astronomia e Astrofisica da
Universidade de Lisboa and Centro de Geofisica de Evora, Portugal),
Yann Alibert, Willy Benz, Christoph Mordasini (Physikalisches
Institut der Universit Bern, Switzerland), Franis Bouchy
(Observatoire de Haute-Provence and IAP, France), Alexandre C. M.
Correia (Universidade de Aveiro, Portugal), Jacques Laskar (IMCCE-
CNRS, Paris, France), Jean-Loup Bertaux (Service d'Aonomie du
CNRS, France), and Jean-Pierre Sivan (Laboratoire d'Astrophysique
de Marseille, France).
[2]: A planet in orbit around a star will manifest its presence
by pulling the star in different directions, thereby changing by
rather small amounts its measured velocity. Astronomers therefore
measure with very high precision the velocity of a star to detect
the signature of one or more planets.
[3]: The High Accuracy Radial velocity Planet Searcher (HARPS) at
the ESO La Silla 3.6-m telescope is dedicated to the discovery of
extrasolar planets. It is a fibre-fed high-resolution echelle
spectrograph that has demonstrated a long-term precision of about
1 m/s.
National contacts for the media:
Belgium: Dr. Rodrigo Alvarez, +32-2-474 70 50
Finland: Ms. Riitta Tirronen, +358 9 7748 8369
Denmark: Dr. Michael Linden-Vnle, +45-33-18 19 97
France: Dr. Daniel Kunth, +33-1-44 32 80 85
Germany: Dr. Jakob Staude, +49-6221-528229
Italy: Dr. Leopoldo Benacchio, benacchio @ inaf.it
The Netherlands: Ms. Marieke Baan, +31-20-525 74 80
Portugal: Prof. Teresa Lago, +351-22-089 833
Sweden: Dr. Jesper Sollerman, +46-8-55 37 85 54
Switzerland: Dr. Martin Steinacher, +41-31-324 23 82
United Kingdom: Mr. Peter Barratt, +44-1793-44 20 25
--------------------------------------------------------------
ESO Press Information is available on the WWW at
http://www.eso.org/outreach/press-rel/
--------------------------------------------------------------
(c) ESO Education & Public Relations Department
Karl-Schwarzschild-Strasse 2, D-85748 Garching, Germany
--------------------------------------------------------------
--------------------------------------------------------------
Text with all links and the photos are available on the ESO
Website at URL:
http://www.eso.org/outreach/press-rel/pr-2006/pr-18-06.html
--------------------------------------------------------------
Contact:
Christophe Lovis and Michel Mayor
Observatoire de l'Universitde Gene, Switzerland
Phone: +41 22 379 24 07, +41 22 379 24 60
Yann Alibert and Willy Benz
Physikalisches Institut der Universit Bern, Switzerland
Phone: +41 31 631 44 27, +41 31 631 44 03
Under embargo till 17 May 19:00 CET
ESO Science release 18/06
Trio of Neptunes and their Belt
HARPS Instrument Finds Unusual Planetary System
Using the ultra-precise HARPS spectrograph on ESO's 3.6-m telescope
at La Silla (Chile), a team of European astronomers have discovered
that a nearby star is host to three Neptune-mass planets. The
innermost planet is most probably rocky, while the outermost is
the first known Neptune-mass planet to reside in the habitable zone.
This unique system is likely further enriched by an asteroid belt.
"For the first time, we have discovered a planetary system composed
of several Neptune-mass planets", said Christophe Lovis, from the
Geneva Observatory and lead-author of the paper presenting the
results [1].
During more than two years, the astronomers carefully studied
HD 69830, a rather inconspicuous nearby star slightly less massive
than the Sun. Located 41 light-years away towards the constellation
of Puppis (the Stern), it is, with a visual magnitude of 5.95, just
visible with the unaided eye. The astronomers' precise radial-
velocity measurements [2] allowed them to discover the presence of
three tiny companions orbiting their parent star in 8.67, 31.6 and
197 days.
"Only ESO's HARPS instrument installed at the La Silla Observatory,
Chile, made it possible to uncover these planets", said Michel
Mayor, also from Geneva Observatory, and HARPS Principal
Investigator. "Without any doubt, it is presently the world's
most precise planet-hunting machine" [3].
The detected velocity variations are between 2 and 3 metres per
second, corresponding to about 9 km/h! That's the speed of a person
walking briskly. Such tiny signals could not have been distinguished
from 'simple noise' by most of today's available spectrographs.
The newly found planets have minimum masses between 10 and 18 times
the mass of the Earth. Extensive theoretical simulations favour an
essentially rocky composition for the inner planet, and a rocky/gas
structure for the middle one. The outer planet has probably accreted
some ice during its formation, and is likely to be made of a
rocky/icy core surrounded by a quite massive envelope. Further
calculations have also shown that the system is in a dynamically
stable configuration.
The outer planet also appears to be located near the inner edge of
the habitable zone, where liquid water can exist at the surface of
rocky/icy bodies. Although this planet is probably not Earth-like
due to its heavy mass, its discovery opens the way to exciting
perspectives.
"This alone makes this system already exceptional", said Willy Benz,
from Bern University, and co-author. "But the recent discovery by
the Spitzer Space Telescope that the star most likely hosts an
asteroid belt is adding the cherry to the cake."
With three roughly equal-mass planets, one being in the habitable
zone, and an asteroid belt, this planetary system shares many
properties with our own solar system.
"The planetary system around HD 69830 clearly represents a Rosetta
stone in our understanding of how planets form", said Michel Mayor.
"No doubt it will help us better understand the huge diversity we
have observed since the first extra-solar planet was found 11
years ago."
High resolution images and their captions are available at
http://www.eso.org/outreach/press-rel/pr-2006/phot-18-06.html
Video footage and animations are also available at
http://www.eso.org/outreach/press-rel/pr-2006/vid-18-06.html
Notes
[1]: These results appear in the 18 May issue of the research
journal Nature ("Discovery of an extrasolar planetary system with
three Neptune-Mass Planets", by C. Lovis et al.). The team is
composed of Christophe Lovis, Michel Mayor, Francesco Pepe, Didier
Queloz, and Sthane Udry (Observatoire de l'Universitde Gene,
Switzerland), Nuno C. Santos (Observatoire de l'Universitde
Gene, Switzerland, Centro de Astronomia e Astrofisica da
Universidade de Lisboa and Centro de Geofisica de Evora, Portugal),
Yann Alibert, Willy Benz, Christoph Mordasini (Physikalisches
Institut der Universit Bern, Switzerland), Franis Bouchy
(Observatoire de Haute-Provence and IAP, France), Alexandre C. M.
Correia (Universidade de Aveiro, Portugal), Jacques Laskar (IMCCE-
CNRS, Paris, France), Jean-Loup Bertaux (Service d'Aonomie du
CNRS, France), and Jean-Pierre Sivan (Laboratoire d'Astrophysique
de Marseille, France).
[2]: A planet in orbit around a star will manifest its presence
by pulling the star in different directions, thereby changing by
rather small amounts its measured velocity. Astronomers therefore
measure with very high precision the velocity of a star to detect
the signature of one or more planets.
[3]: The High Accuracy Radial velocity Planet Searcher (HARPS) at
the ESO La Silla 3.6-m telescope is dedicated to the discovery of
extrasolar planets. It is a fibre-fed high-resolution echelle
spectrograph that has demonstrated a long-term precision of about
1 m/s.
National contacts for the media:
Belgium: Dr. Rodrigo Alvarez, +32-2-474 70 50
Finland: Ms. Riitta Tirronen, +358 9 7748 8369
Denmark: Dr. Michael Linden-Vnle, +45-33-18 19 97
France: Dr. Daniel Kunth, +33-1-44 32 80 85
Germany: Dr. Jakob Staude, +49-6221-528229
Italy: Dr. Leopoldo Benacchio, benacchio @ inaf.it
The Netherlands: Ms. Marieke Baan, +31-20-525 74 80
Portugal: Prof. Teresa Lago, +351-22-089 833
Sweden: Dr. Jesper Sollerman, +46-8-55 37 85 54
Switzerland: Dr. Martin Steinacher, +41-31-324 23 82
United Kingdom: Mr. Peter Barratt, +44-1793-44 20 25
--------------------------------------------------------------
ESO Press Information is available on the WWW at
http://www.eso.org/outreach/press-rel/
--------------------------------------------------------------
(c) ESO Education & Public Relations Department
Karl-Schwarzschild-Strasse 2, D-85748 Garching, Germany
--------------------------------------------------------------