The star HIP 11915 in the constellation of Cetus
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Brazilian-led team leading the search for a Solar System 2.0
An international group of astronomers has
used the ESO 3.6-metre telescope to identify a planet just like Jupiter
orbiting at the same distance from a Sun-like star, HIP 11915.
According to current theories, the formation of Jupiter-mass planets
plays an important role in shaping the architecture of planetary
systems. The existence of a Jupiter-mass planet in a Jupiter-like orbit
around a Sun-like star opens the possibility that the system of planets
around this star may be similar to our own Solar System. HIP 11915 is
about the same age as the Sun and, furthermore, its Sun-like composition
suggests that there may also be rocky planets orbiting closer to the
star.
So far, exoplanet surveys have been most sensitive to planetary
systems that are populated in their inner regions by massive planets,
down to a few times the mass of the Earth [1].
This contrasts with our Solar System, where there are small rocky
planets in the inner regions and gas giants like Jupiter farther out.
According to the most recent theories, the arrangement of our Solar
System, so conducive to life, was made possible by the presence of
Jupiter and the gravitational influence this gas giant exerted on the
Solar System during its formative years. It would seem, therefore, that
finding a Jupiter twin is an important milestone on the road to finding a
planetary system that mirrors our own.
A Brazilian-led team has been targeting Sun-like stars in a bid to
find planetary systems similar to our Solar System. The team has now
uncovered a planet with a very similar mass to Jupiter [2], orbiting a Sun-like star, HIP 11915, at almost exactly the same distance as Jupiter. The new discovery was made using HARPS, one of the world’s most precise planet-hunting instruments, mounted on the ESO 3.6-metre telescope at the La Silla Observatory in Chile.
Although many planets similar to Jupiter have been found [3]
at a variety of distances from Sun-like stars, this newly discovered
planet, in terms of both mass and distance from its host star, and in
terms of the similarity between the host star and our Sun, is the most
accurate analogue yet found for the Sun and Jupiter.
The planet’s host, the solar twin HIP 11915, is not only similar in
mass to the Sun, but is also about the same age. To further strengthen
the similarities, the composition of the star is similar to the Sun’s.
The chemical signature of our Sun may be partly marked by the presence
of rocky planets in the Solar System, hinting at the possibility of
rocky planets also around HIP 11915.
According to Jorge Melendez, of the Universidade de São Paulo, Brazil, the leader of the team and co-author of the paper, “the
quest for an Earth 2.0, and for a complete Solar System 2.0, is one of
the most exciting endeavors in astronomy. We are thrilled to be part of
this cutting-edge research, made possible by the observational
facilities provided by ESO.” [4]
Megan Bedell, from the University of Chicago and lead author of the paper, concludes: “After
two decades of hunting for exoplanets, we are finally beginning to see
long-period gas giant planets similar to those in our own Solar System
thanks to the long-term stability of planet hunting instruments like
HARPS. This discovery is, in every respect, an exciting sign that other
solar systems may be out there waiting to be discovered.”
Follow-up observations are needed to confirm and constrain the
finding, but HIP 11915 is one of the most promising candidates so far to
host a planetary system similar to our own.
Notes
[1] The current detection techniques are more sensitive to large or
massive planets close to their host stars. Small and low-mass planets
are mostly beyond our current capabilities. Giant planets that orbit far
from their host star are also more difficult to detect. Consequently,
many of the exoplanets we currently know are large and/or massive, and
close to their stars.
[2] The planet was discovered by
measuring the slight wobble it imposes on its host star while orbiting
around it. As the inclination of the planet’s orbit is not known, only a
lower limit to its mass can be estimated. Note that the activity of the
star, which is linked to the variations of its magnetic field, could
possibly mimic the signal that is interpreted as the signature of the
planet. The astronomers have performed all the known tests to
investigate this possibility, but it is currently impossible to
completely rule it out.
[4] Since the signature of the Brazilian accession agreement in December 2010, Brazilian astronomer have had full access to the ESO observing facilities.
More Information
This research was presented in a paper entitled “The Solar Twin
Planet Search II. A Jupiter twin around a solar twin”, by M. Bedell et
al., to appear in the journal Astronomy and Astrophysics.
The team is composed of M. Bedell (Department of Astronomy and
Astrophysics, University of Chicago, Chicago, Illinois, USA; Visiting
Researcher at the Departamento de Astronomia do IAG/USP, Universidade de
São Paulo, São Paulo, Brazil), J. Meléndez (Universidade de São Paulo,
São Paulo, Brazil), J. L. Bean (Department of Astronomy and
Astrophysics, University of Chicago), I. Ramírez (McDonald Observatory
and Department of Astronomy, University of Texas, Austin, Texas, USA),
M. Asplund (Research School of Astronomy and Astrophysics, The
Australian National University, Weston, Australia), A. Alves-Brito
(Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Porto
Alegre, Rio Grande do Sul, Brazil), L. Casagrande (Research School of
Astronomy and Astrophysics, Australia), S. Dreizler (Institut für
Astrophysik, University of Göttingen, Germany), T. Monroe (Universidade
de São Paulo, Brazil), L. Spina (Universidade de São Paulo, Brazil) and
M. Tucci Maia (Universidade de São Paulo, Brazil).
ESO is the foremost intergovernmental astronomy organisation in
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which will become “the world’s biggest eye on the sky”.
Links
Contacts
University of Chicago
USA
Tel: +1 518 488 9348
Email: mbedell@oddjob.uchicago.edu
Jorge Meléndez
Universidade de São Paulo
Brazil
Tel: +55 11 3091 2840
Email: jorge.melendez@iag.usp.br
Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
Source: ESO
