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Diffraction-limited radial-velocity instruments offer a pathway towards improved precision and stability, and the exploration of new parameter spaces at high spatial and spectral resolution. However, achieving the necessary performance requires careful instrument design and considerable on-sky testing. We describe the design and construction of ‘Little iLocater’ (Lili), a compact spectrograph that has been used to validate the performance of the front-end fibre-injection system of the iLocater spectrograph. We present the design, assembly, and performance using on-sky data obtained at the Large Binocular Telescope (LBT), including extraction of spectra from standard stars, testing of the atmospheric dispersion corrector to elevations of 40°, and spatially resolved spectra from close companion systems. These results show the front-end fibre-injection system is performing as expected and is indicative of iLocater’s capabilities once installed at the LBT. 

Precision radial velocity spectrographs that use adaptive optics (AO) show promise to advance telescope observing capabilities beyond those of seeing-limited designs. We are building a spectrograph for the Large Binocular Telescope (LBT) named iLocater that uses AO to inject starlight directly into single mode fibers. iLocater's first acquisition camera system (the SX camera), which receives light from one of the 8.4 m diameter primary mirrors of the LBT, was initially installed in summer 2019 and has since been used for several commissioning runs. We present results from first-light observations that include on-sky measurements as part of commissioning activities. Imaging measurements of the bright B3IV star 2 Cygni (V= 4.98) resulted in the direct detection of a candidate companion star at an angular separation of onlyθ = 70 mas. Follow-up AO measurements using Keck/NIRC2 recover the candidate companion in multiple filters. AnR ≈ 1500 miniature spectrograph recently installed at the LBT named Lili provides spatially resolved spectra of each binary component, indicating similar spectral types and strengthening the case for companionship. Studying the multiplicity of young runaway star systems like 2 Cygni (36.6 ± 0.5 Myr) can help to understand formation mechanisms for stars that exhibit anomalous velocities through the Galaxy. This on-sky demonstration illustrates the spatial resolution of the iLocater SX acquisition camera working in tandem with the LBT AO system; it further derisks a number of technical hurdles involved in combining AO with Doppler spectroscopy. 

Abstract We use a high-precision radial velocity survey of FGKM stars to study the conditional occurrence of two classes of planets: close-in small planets (0.023–1 au, 2–30 M ⊕ ) and distant giant planets (0.23–10 au, 30–6000 M ⊕ ). We find that 41 − 13 + 15 % of systems with a close-in, small planet also host an outer giant, compared to 17.6 − 1.9 + 2.4 % for stars irrespective of small planet presence. This implies that small planet hosts may be enhanced in outer giant occurrences compared to all stars with 1.7 σ significance. Conversely, we estimate that 42 − 13 + 17 % of cold giant hosts also host an inner small planet, compared to 27.6 − 4.8 + 5.8 % of stars irrespective of cold giant presence. We also find that more massive and close-in giant planets are not associated with small inner planets. Specifically, our sample indicates that small planets are less likely to have outer giant companions more massive than approximately 120 M ⊕ and within 0.3–3 au, than to have less massive or more distant giant companions, with ∼2.2 σ confidence. This implies that massive gas giants within 0.3–3 au may suppress inner small planet formation. Additionally, we compare the host-star metallicity distributions for systems with only small planets and those with both small planets and cold giants. In agreement with previous studies, we find that stars in our survey that only host small planets have a metallicity distribution that is consistent with the broader solar-metallicity-median sample, while stars that host both small planets and gas giants are distinctly metal rich with ∼2.3 σ confidence.