This is a double image of the
star Eta Crucis taken through the vector-APP coronagraph installed at
MagAO. The two main images of the star exhibit D-shaped dark holes on
complementary sides.
Credit: Leiden University, University of Arizona
Astronomers have successfully
commissioned a new type of optic that can reveal the image of an
exoplanet next to its parent star. The 'vector Apodizing Phase Plate'
(vector-APP) coronagraph was installed at the 6.5-m Magellan Clay
telescope in Chile in May 2015, and the first observations demonstrated
an unprecedented contrast performance very close to the star, where
planets are more likely to reside. These results will be presented by
PhD student Gilles Otten this Monday afternoon to the scientific
community at the "In the Spirit of Lyot" conference organized by the
Centre for Research in Astrophysics of Québec and researchers at the
University of Montreal.
Almost 2000 exoplanets have been detected to date, but only a handful
of those have been imaged directly. Exoplanets are typically more than a
million times fainter than and are lost in the glare of their parent
star as seen from Earth. To directly image exoplanets and to
characterize their atmospheres, astronomical instruments at the world's
largest telescopes use coronagraphs to suppress the overwhelming halo of
light from the star.
The vector-APP coronagraph uses the wavelike nature of light to
cancel out the starlight whilst allowing the planet's light to shine
through.
This manipulation is implemented through a complex phase pattern that
can only be manufactured using advanced liquid crystal 3D patterning
techniques. This technique creates two images of the star, for which
dark D-shaped regions are located on opposite sides of each star image.
In this way, the whole region around the star can be scrutinized for
planets. By combining several layers of liquid crystals, the device can
be used over a wide range of wavelengths, including the infrared where
the contrast between planet and star is more favorable.
On May 6, 2015 a vector-APP coronagraphic device saw first light (at
3.9 m wavelength, in the infrared range of the spectrum) at the MagAO
instrument, attached to the 6.5-m diameter Magellan Clay telescope in
Chile. The telescope's integrated adaptive optics system provided the
instrument with sharp images of stars, which were consequently split up
and modified by the coronagraph to exhibit dark holes in which much
fainter planets could be imaged than without the vector-APP coronagraph.
Frans Snik, who invented the principle behind the new vector-APP
coronagraph, says: "It is fantastic to see that after all our design
work and lab testing, this new approach works perfectly at the telescope
on the very first night!"
Gilles Otten adds: "We knew that we were in business as soon as we
saw the first picture on the screen in the telescope control room."
Jared Males is excited about the opportunities of the vector-APP:
"With this new coronagraph we are now looking for planets around nearby
stars. We have the capacity to directly detect, or rule out, planets
smaller than Jupiter."
Matthew Kenworthy concludes: "This new coronagraph technology is also
excellent news for the extremely large telescopes currently under
construction. Thermal infrared instruments such as the Mid-infrared
E-ELT Imager and Spectrograph (METIS) can exploit this new technology
and discover new worlds. With a vector-APP coronagraph in the next
generation of telescopes, we can search for planets around nearby stars
with unprecedented sensitivity."
The advanced liquid crystal technology that the team adopted also
permitted the production of extreme vector-APP designs that are not
possible with more traditional manufacturing technologies. These new
designs produce dark holes that cover the full 360 degrees around the
target stars. The first data from an experimental device already shows
the viability of this novel approach.
Story Source:
The above post is reprinted from
materials provided by
University of Montreal.
Note: Materials may be edited for content and length.