Even though more than 4000 extra-solar planets are known today, only a small fraction of these has been captured in an image. To better understand the planet formation mechanisms in solar-like... Show moreEven though more than 4000 extra-solar planets are known today, only a small fraction of these has been captured in an image. To better understand the planet formation mechanisms in solar-like environments we started the Young Suns Exoplanet Survey (YSES). YSES targets a homogeneous sample of seventy young (~15Myr), Sun-like stars of the Scorpius-Centaurus association to search for sub-stellar companions. High-contrast imaging observations that were collected with the SPHERE instrument at the Very Large Telescope revealed (i) a shadowed transition disk around Wray 15-788 that shows significant signs of ongoing planet formation and (ii) one of the lowest-mass companions imaged to date: YSES 2b has a mass of 6.5 Jupiter masses and is orbiting its solar-mass primary at a separation of 110 au. Most intriguing, though, was (iii) the discovery of the first directly imaged multi-planet system around a Sun-like star. The detection of two gas-giant companions of 14±3 and 6±1 Jupiter masses that are orbiting YSES 1 at separations of 160 au and 320 au, respectively, provides important implications for the outer architecture of planetary systems and the underlying formation mechanisms. Show less
This thesis aims to demonstrate how the achromatic nature and design flexibility of liquid-crystal optics can be used to improve high-contrast imaging instruments to facilitate detailed exoplanet... Show moreThis thesis aims to demonstrate how the achromatic nature and design flexibility of liquid-crystal optics can be used to improve high-contrast imaging instruments to facilitate detailed exoplanet characterization.Chapter 2 discusses the design, performance, and future development of the liquid-crystal vector-apodizing phase plate (vAPP) coronagraph, five of which have been installed in different instruments on current generation telescopes since 2016. In chapter 3 we use the achromatic nature of the vAPP in combination with the LBT/ALES integral field spectrograph to obtain the first ever thermal infrared spectrum of the inner three HR 8799 planets. In Chapter 4 and 8 we show that by combining multiple grating patterns to reduce the influence of polarization leakage, we can improve the performance of liquid-crystal coronagraphs. In Chapter 5 and 6 we enhance sparse aperture masking, capable of detecting companions beyond the diffraction limit, by using liquid-crystal phase masks to enable low-resolution spectroscopy and improve throughput. In Chapter 7 we demonstrate that a liquid-crystal Zernike wavefront sensor can accurately and efficiently measure phase and amplitude aberrations simultaneously, facilitating extreme contrasts. Together, the concepts presented in this thesis can be used to improve high-contrast imaging instruments of both ground-based and space-based observatories. Show less
