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Direct Imaging of Extrasolar Planets from LBT and VLT to E-ELT

Final Report Summary - DICE (Direct Imaging of Extrasolar Planets from LBT and VLT to E-ELT)

The goal of the DICE project is to develop techniques that will improve the direct imaging capabilities of ground based telescopes in the search for and characterization of extrasolar giant planets (EGPs) and ultimately lead to the discovery of analogues to our solar system. By discovering exoplanet systems with current ground-based telescopes, we build a path for characterization with the next generation of large telescopes such as the European Extremely Large Telescope (E-ELT).

The main results of DICE are:

The Researcher's graduate students (T. Meshkat and G. Otten) have completed their surveys for gas giant planets around nearby stars. The two surveys completed are the A/F star survey and the ``Holey Disks'' survey.

Massive stars are relatively young compared to the Sun, and they are a prime location for the imaging of hot and young exoplanets. Their spectral types are known as A and F stars, and they formed the basis for the first survey. The survey used Kenworthy's APP coronagraph to increase the sensitivity of the survey close in to the stars. The recently published paper on the A and F star survey, Meshkat et al. (2015a), details the observations and analysis of the 13 stars observed. The survey discovered three new low mass companions to these stars and demonstrated that the coronagraph can detect 2 to 12 Jupiter mass planets within 30 AU of their parent star.

Based on the success of the A/F star survey, a second survey was undertaken that looked at stars with circumstellar disks similar to the star HR 8799, which has four planets orbiting it. These stars have unresolved disks of dust orbiting around them, and the spectral distribution of this dust at wavelengths of 20 to 200 microns implied that there is a gap cleared out in the disk, as seen in the HR 8799 system. Our hypothesis is that the gaps in these dust disks are being cleared out by the gravitational influence of a giant planet. The first paper in the survey is now published, again using the Researcher's coronagraph to increase sensitivity at small working angles, published in Meshkat et al. (2015b). The hypothesis was spectacularly validated with the discovery of HD 95086, a 5 Jupiter mass planet orbiting one of our target stars. We subsequently characterised the planet with additional observations and two papers, one of these led by Matthew Kenworthy's graduate student.

The APP coronagraph was further developed by Kenworthy's graduate student G. Otten, producing a new and improved design called the vector APP (vAPP). This was validated in the high contrast imaging laboratory in Leiden and published in Otten et al. (2014). An additional technological development has led to the grating vector APP (gvAPP) that results in a compact optical form of the vAPP suitable for use in current telescopes. The gvAPP was validated at the Large Binocular Telescope by Otten in November 2014, and a science grade gvAPP is being installed in the Magellan 6.5m telescope at Las Cumbres Observatory in May 2015.

Meshkat published her paper on the development of Optimised Principal Component Analysis, which demonstrates significant improvement over standard planet detection algorithms. The optimised PCA is used in the survey papers and is being cited in the literature.

Development of new ELT AO techniques led to a new insight in how wide field AO correction could be carried out at large telescopes. A networked distributed set of small telescopes scattered around the ELT can carry out tomography using multiple lines of sight looking towards bright natural guide stars. The Researcher successfully obtained funds from the national funding agency in the Netherlands to start a collaboration with researchers in South Africa. The first observing runs to test the wide field AO correction principle are in June 2015.

There is a tremendous popular interest in astronomy, and the idea of worlds other than our own in the Universe is one of the most inspiring concepts to society at large. Kenworthy's research leads the way in discovering new, directly imaged gas giant planets, which are the largest visible markers for extrasolar planetary systems. His reintegration into the European research community, enabled by this grant, reflects this. In the near future, further work with state of the art instruments on the Very Large Telescope informs future telescopes like the European Extremely Large Telescope, which may be the first telescope to directly image the surface of an alien rocky world. Kenworthy is in an excellent position to build on his research and build the algorithms and optics to attain these most challenging technical goals.