Cross-aperture nulling interferometry
The VFN testbed in the ET Lab aims at demonstrating a new technique called the Vortex Fiber Nuller. Fiber nulling as a means to detect and characterize exoplanets and circumstellar disks at or within the diffraction limit was first introduced and demonstrated by Haguenauer and Serabyn (2006). This concept is largely based on the Bracewell nulling interferometer (Bracewell and MacPhie, 1979). The first fiber nuller was demonstrated on sky at Palomar observatory by Hanot et al. (2011). We recently introduced the concept of vortex fiber nulling, which circumvents the need of a rotating baseline and greatly simplifies the design and operation of the fiber nuller (Ruane et al., 2018). The VFN concept was demonstrated in the ET Lab by Caltech graduate student Daniel Echeverri, and will be the subject of an on-sky science demonstration at Keck observatory in 2021 (Echeverri et al., 2019). The combination of VFN starlight suppression at the 1E-3 raw contrast level (limited by AO residuals and finite stellar size) and high-resolution spectroscopy will enable the detection and high-resolution spectroscopic characterization of planets at or within the diffraction limit (down to ~10 mas on TMT). Using the latest giant planet occurrence rates from Nielsen et al. (2019), we predict the discovery and simultaneous characterization of dozens of new young giant planets in nearby young associations and star forming regions with Keck, and even more with TMT. Benefiting from the giant aperture and angular resolution of TMT, Ruane et al. (2018) predicts the detection of nearby Earth-size planet Ross 128 b in reflected light in 30 hours. Less challenging configurations, which include giant planet, mini-Neptunes and super-Earths will also be accessible. The challenging case of temperate Earth-size planets in less favorable configurations than Ross 128 b (e.g. more distant) will require the extreme adaptive optics system of the TMT-Planetary Systems Imager.