Planet formation imager (PFI): introduction and technical considerations

Abstract

Complex non-linear and dynamic processes lie at the heart of the planet formation process. Through numerical simulation and basic observational constraints, the basics of planet formation are now coming into focus. High resolution imaging at a range of wavelengths will give us a glimpse into the past of our own solar system and enable a robust theoretical framework for predicting planetary system architectures around a range of stars surrounded by disks with a diversity of initial conditions. Only long-baseline interferometry can provide the needed angular resolution and wavelength coverage to reach these goals and from here we launch our planning efforts. The aim of the "Planet Formation Imager" (PFI) project is to develop the roadmap for the construction of a new near-/mid-infrared interferometric facility that will be optimized to unmask all the major stages of planet formation, from initial dust coagulation, gap formation, evolution of transition disks, mass accretion onto planetary embryos, and eventual disk dispersal. PFI will be able to detect the emission of the cooling, newlyformed planets themselves over the first 100 Myrs, opening up both spectral investigations and also providing a vibrant look into the early dynamical histories of planetary architectures.Here we introduce the Planet Formation Imager (PFI) Project (www.planetformationimager.org) and give initial thoughts on possible facility architectures and technical advances that will be needed to meet the challenging top-level science requirements.

The planet formation imager

“…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.…”

“…An effort was started in 2013 at a workshop in Haute-Provence to explore the potential for a new facility that could image all the fundamental stages of planet formation in situ in nearby star forming regions. The Planet Formation Imager (PFI, www.planetformationimager.org) project was first proposed at the 2014 SPIE meeting on Astronomical Telescopes and Instrumentation (Montreal) in a series of presentations [18,13,11].…”

“…Radiative transfer model for an example planet-forming disk[18,8] with the relevant size scales marked. The primary science driver of the Planet Formation Imager (PFI) is to image scales as large as the whole circumstellar accretion disk down to the circumplanetary accretion disks of individual giant planets.…”

Planet formation imager: project update

“…The PFI SWG and TWG have published a large number of articles in SPIE, outlining both the science case 2, 5 and possible technical implementations of PFI. 1,3,4,[6][7][8][9][10] This year there are about 13 contributions directly related to PFI: In addition to this work, the PFI TWG will write at least one paper in the planned Science White Book to define a baseline PFI architecture to reference in the science chapters.…”