Defining Serious Impairment of Body Function: The Aftermath of Kreiner and the Need for Change

Article published in the Michigan State University School of Law Student Scholarship Collection

Defining Serious Impairment of Body Function: The Aftermath of Kreiner and the Need for Change

Article published in the Michigan State University School of Law Student Scholarship Collection

Large adaptive optics survey for substellar objects around Young, Nearby, Low-mass Stars with Robo-AO

We present results from the Large Adaptive optics Survey for Substellar Objects, where the goal is to directly image new substellar companions (<70 MJup) at wide orbital separations (≳50 au) around young (≲300 Myr), nearby (<100 pc), low-mass (≈0.1–0.8 M☉) stars. We report on 427 young stars imaged in the visible (i′) and near-infrared (J or H) simultaneously with Robo-AO on the Kitt Peak 2.1 m telescope and later the Maunakea University of Hawaii 2.2 m telescope. To undertake the observations, we commissioned a new infrared camera for Robo-AO that uses a low-noise high-speed SAPHIRA avalanche photodiode detector. We detected 121 companion candidates around 111 stars, of which 62 companions are physically associated based on Gaia DR2 parallaxes and proper motions, another 45 require follow-up observations to confirm physical association, and 14 are background objects. The companion separations range from 2 to 1101 au and reach contrast ratios of 7.7 mag in the near-infrared compared to the primary. The majority of confirmed and pending candidates are stellar companions, with ∼5 being potentially substellar and requiring follow-up observations for confirmation. We also detected a 43 ± 9 MJup and an 81 ± 5 MJup companion that were previously reported. We found 34 of our targets have acceleration measurements detected using Hipparcos–Gaia proper motions. Of those, 58-+1412% of the 12 stars with imaged companion candidates have significant accelerations (c2 > 11.8), while only 23-+611% of the remaining 22 stars with no detected companion have significant accelerations. The significance of the acceleration decreases with increasing companion separation. These young accelerating low-mass stars with companions will eventually yield dynamical masses with future orbit monitoring

High contrast imaging upgrades for the Keck adaptive optics imager

The Keck II adaptive optics (AO) system is being upgraded with a near-infrared Pyramid Wavefront Sensor (PWS) as part of the Keck Planet Imager and Characterizer (KPIC) upgrade. The overview of the KPIC project and the PWS development are presented elsewhere in this conference. This paper focuses on improvements made to the NIRC2 science instrument, referred to as the NIRC2 upgrade, aimed at enhancing its high contrast imaging capabilities. The NIRC2 upgrade incorporates new coronagraphic elements that reach their maximum performance when operated in combination with the new near-infrared PWS and polarimetric elements that would add polarimetric capability when fully implemented. The key elements to the NIRC2 upgrade are the installation of two next-generation Vector Vortex Coronographic (VVC) masks, one optimized for the L and M band, and the other one optimized for the K band. Also key to the upgrade is the incorporation of a new Lyot stop optimized to minimize diffraction and residual nutation of the Keck-II telescope pupil. These new elements provide improved coronographic performance when operated with the new PWS and the existing Shack Hartmann wavefront sensor (SH WFS). The upgrade implementation and preliminary on-sky results are discussed. © 2019 AO4ELT 2019 - Proceedings 6th Adaptive Optics for Extremely Large Telescopes. All rights reserved