SPHERE images the dust ring around the star HR 4796A
SPHERE image of Saturn’s moon Titan
The SPHERE instrument attached to the VLT
SPHERE being prepared for first light
The SPHERE instrument on the final stage of its journey to the VLT
Saturn's moon Titan observed using the polarimetric mode of SPHERE
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Videos
Revolutionary new VLT Instrument installed
SPHERE — the Spectro-Polarimetric
High-contrast Exoplanet REsearch instrument — has been installed on
ESO’s Very Large Telescope (VLT) at the Paranal Observatory in Chile and
has achieved first light. This powerful new facility for finding and
studying exoplanets uses multiple advanced techniques in combination. It
offers dramatically better performance than existing instruments and
has produced impressive views of dust discs around nearby stars and
other targets during the very first days of observations. SPHERE was
developed and built by a consortium of many European institutes, led by
the Institut de Planétologie et d'Astrophysique de Grenoble, France,
working in partnership with ESO. It is expected to revolutionise the
detailed study of exoplanets and circumstellar discs.
SPHERE passed its acceptance tests in Europe in December 2013 and was then shipped to Paranal.
The delicate reassembly was completed in May 2014 and the instrument is
now mounted on VLT Unit Telescope 3. SPHERE is the latest of the second
generation of instruments for the VLT (the first three were X-shooter, KMOS and MUSE).
SPHERE combines several advanced techniques to give the highest
contrast ever reached for direct planetary imaging — far beyond what
could be achieved with NACO, which took the first ever direct image of an exoplanet.
To reach its impressive performance SPHERE required early development
of novel technologies, in particular in the area of adaptive optics,
special detectors and coronagraph components.
“SPHERE is a very complex instrument. Thanks to the hard work of
the many people who were involved in its design, construction and
installation it has already exceeded our expectations.
Wonderful!”
says Jean-Luc Beuzit, of the Institut de Planétologie et d'Astrophysique
de Grenoble, France and Principal Investigator of SPHERE.
SPHERE’s main goal is to find and characterise giant exoplanets orbiting nearby stars by direct imaging [1].
This is an extremely challenging task as such planets are both very
close to their parent stars in the sky and also very much fainter. In a
normal image, even in the best conditions, the light from the star
totally swamps the weak glow from the planet. The whole design of SPHERE
is therefore focused on reaching the highest contrast possible in a
tiny patch of sky around the dazzling star.
The first of three novel techniques exploited by SPHERE is extreme
adaptive optics to correct for the effects of the Earth’s atmosphere so
that images are sharper and the contrast of the exoplanet increased.
Secondly, a coronagraph is used to block out the light from the star and
increase the contrast still further. Finally, a technique called
differential imaging is applied that exploits differences between
planetary and stellar light in terms of its colour or polarisation — and
these subtle differences can also be exploited to reveal a currently
invisible exoplanet (ann13069, eso0503) [2].
SPHERE was designed and built by the following institutes: Institut
de Planétologie et d'Astrophysique de Grenoble; Max-Planck-Institut für
Astronomie in Heidelberg; Laboratoire d’Astrophysique de Marseille;
Laboratoire d’Etudes Spatiales et d’Instrumentation en Astrophysique de
l’Observatoire de Paris; Laboratoire Lagrange in Nice; ONERA;
Observatoire de Genève; Italian National Institute for Astrophysics
coordinated by the Osservatorio Astronomico di Padova; Institute for
Astronomy, ETH Zurich; Astronomical Institute of the University of
Amsterdam; Netherlands Research School for Astronomy (NOVA-ASTRON) and
ESO.
During the first light observations several test targets were
observed using the many different modes of SPHERE. These include one of
the best images so far of the ring of dust around the nearby star HR
4796A. It not only shows the ring with exceptional clarity but also
illustrates how well SPHERE can suppress the glare of the bright star at
the centre of the picture.
Following further extensive tests and science verification
observations SPHERE will be made available to the astronomical community
later in 2014.
“This is just the beginning. SPHERE is a uniquely powerful tool
and will doubtless reveal many exciting surprises in the years to come,” concludes Jean-Luc Beuzit.
Notes
[1] Most of the exoplanets currently
known were discovered using indirect techniques — such as radial
velocity variations of the host star, or the dip in brightness of the
star caused by a transiting exoplanet. Only a few exoplanets have so far
been directly imaged (eso0515, eso0842).
[2] A further, but simpler trick employed by SPHERE
is to take many pictures of an object, but with a significant rotation
of the image in between each. Features in the pictures that rotate are
artefacts of the imaging process, and features that stay in the same
place are real objects in the sky.
More information
ESO is the foremost intergovernmental
astronomy organisation in Europe and the world’s most productive
ground-based astronomical observatory by far. It is supported by 15
countries: Austria, Belgium, Brazil, 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 two survey telescopes. VISTA works in the infrared and
is the world’s largest survey telescope and the VLT Survey Telescope is
the largest telescope designed to exclusively survey the skies in
visible light. ESO is the European partner of a revolutionary
astronomical telescope ALMA, the largest astronomical project in
existence. ESO is currently planning the 39-metre European Extremely
Large optical/near-infrared Telescope, the E-ELT, which will become “the
world’s biggest eye on the sky”.
Links
- SPHERE science page at ESO
- SPHERE information at Observatoire des Sciences de l'Univers de Grenoble
- Photos of the VLT
Contacts
Jean-Luc BeuzitInstitut de Planétologie et d'Astrophysique de Grenoble
Grenoble, France
Tel: +33 4 76 63 55 20
Cell: +33 6 87 39 62 85
Email: Jean-Luc.Beuzit@obs.ujf-grenoble.fr
Markus Feldt
Max-Planck-Institut für Astronomie
Heidelberg, Germany
Tel: +49 6221 528 262
Email: mfeldt@mpia.de
Markus Kasper
ESO
Garching bei München, Germany
Tel: +49 89 3200 6359
Email: mkasper@eso.org
Norbert Hubin
ESO
Garching bei München, Germany
Tel: +49 89 3200 6517
Email: nhubin@eso.org
Richard Hook
ESO education and Public Outreach Department
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
