Status of the Planet Formation Imager (PFI) concept

Abstract

The Planet Formation Imager (PFI) project aims to image the period of planet assembly directly, resolving structures as small as a giant planet's Hill sphere. These images will be required in order to determine the key mechanisms for planet formation at the time when processes of grain growth, protoplanet assembly, magnetic fields, disk/planet dynamical interactions and complex radiative transfer all interact -making some planetary systems habitable and others inhospitable. We will present the overall vision for the PFI concept, focusing on the key technologies and requirements that are needed to achieve the science goals. Based on these key requirements, we will define a cost envelope range for the design and highlight where the largest uncertainties lie at this conceptual stage.

The planet formation imager

“…After the 2014 SPIE meeting where the PFI project was introduced, a Science Working Group (SWG; headed by Stefan Kraus) and a Technical Working Group (TWG; headed first by David Buscher, and now Michael Ireland) were formed involving around one hundred astronomers around the world. Based on the early top-level science requirements first outlined in 2014, the 2016 SPIE meeting in Edinburgh saw even more contributions which explored technical solutions to achieve these science goals [17,14,12,16,19,3,21]. For instance, a mid-infrared wavelength range was chosen over mm-wave or near-infrared to access the most diverse aspects of planet formation in the "warm dust" zone.…”

“…The infrared surface brightness sensitivity is mostly determined by the size of the individual apertures and not the number of telescopes -this pushed the design towards large-area unit telescopes which drives the cost. A simple cost model was introduced by Ireland et al [12] which informed the baseline architecture described now where fewer large telescopes were preferred over many more small apertures (at fixed cost). Table 3 contains a summary of a baseline PFI architecture sufficient to achieve the top-level science requirements.…”

“…By using a Gregorian design, the pupil is apodized to be more gaussian, ideal for both propagation through long delay lines and injection into a single-mode fiber. See Monnier et al (2014) and Ireland et al (2016) for more information [18,12]. (right) Photograph shows the laboratory set-up to explore the generation of N-band laser frequency combs using direct difference frequency generation (DFG) of near infrared femtosecond pulses output by an optical parametric oscillator.…”

“…Work is ongoing in Chile (Valparaiso), USA (Flagstaff, Michigan), and Australia (Canberra) to seek funding and new partnerships. Figure 2 shows a ZEMAX design for a spherical primary with a highly-aspheric Gregorian secondary resulting in a gaussian-like apodization of the pupil with diffraction-limited performance over a small field-of-view [18,12]. The field-of-view limitations of some designs would limit off-axis AO tracking for visibly-faint targets and this trade-off requires more study.…”

Planet Formation Imager (PFI): science vision and key requirements

“…Therefore we focus in this article on giving a brief update on the organisational structure of the Science Working Group (SWG) that we have set up and on outlining some initial results and conclusions. The activities in the Technical Working Group (TWG) are outlined in several separate articles in these proceedings (Ireland et al, 14…”