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Appendix K: Report of the Panel on Optical and Infrared Observations from the Ground
Pages 415-439

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From page 415...
... Last, the panel emphasizes the importance of modest strategic investments in technology development and software, and in the further development of the systems-level approach to optimizing the performance of the OIR system in an era of time-domain/multi-messenger astrophysics. For this plan to succeed, there needs to be a fundamental change in the way in which the federal, state, and private funding sources for ground-based OIR facilities interact.
From page 416...
... The development and deployment of multi-object and integral-field spectrographs, and of advanced Adaptive Optics and High Contrast Imaging systems has made these technologies powerful PREPUBLICATION COPY – SUBJECT TO FURTHER EDITORIAL CORRECTION K-2
From page 417...
... The National Academies Exoplanet Science Strategy and the Panel on Exoplanets, Astrobiology, and the Solar System have identified two ground-based capabilities in optical and infrared astronomy that are essential to realize the great opportunity in exoplanets and astrobiology that is open before us: Firstly, the GMT and TMT will open an unprecedented discovery space in the study of planet formation, mature gas giants, and even terrestrial worlds. The unprecedented contrast and angular PREPUBLICATION COPY – SUBJECT TO FURTHER EDITORIAL CORRECTION K-3
From page 418...
... , and for interpreting studies of the planetary atmosphere, since the atmospheric scale height depends on a combination of surface gravity, temperature, and mean molecular weight. Radial velocity measurements are currently limited by variations in the stellar photosphere, instrumental stability and calibration, and spectral contamination from telluric lines.
From page 419...
... The combination of light-gathering power and high angular resolution will enable the new ELTs to test these models. By measuring precise radial velocities and proper motions, it will be possible to construct maps of the 3D stellar orbits at dwarf galaxy centers to map the radial distribution of dark matter, to thereby determine whether self-interacting dark matter is required.
From page 420...
... K.2.4 A Stellar Renaissance Over the past 15 years, the solar and stellar astrophysics community has ignited a scientific renaissance through a remarkable investment in facilities for global synoptic and high-resolution solar observations, extreme-precision stellar radial velocity, and milliarcsecond imaging of nearby stars, as well as ultra-widefield surveys focused on high-precision position measurements, high-cadence time-domain measurements, medium-resolution optical-infrared spectroscopy, and multi-band precision photometry. Ground-based OIR facilities have played, and will continue to play, the central role.
From page 421...
... Many of the brightest stars in those samples will be observable by ground-based optical interferometers and highspectral resolution spectrometers and spectropolarimeters to open a new window on the connection between stellar surface and interior phenomena. Looking further into the future, the spatial resolution of ELTs will isolate single stars below the main-sequence turnoff, map the orbits of tight binaries, and enable proper motion selection in distant clusters in currently inaccessible environments throughout the Local Volume.
From page 422...
... Laser Tomography Adaptive Optics utilizes six sodium laser beacons and edge-sensors. With this, diffraction-limited images of 10 mas at 1 μm can be achieved over a 20–30 arcsec FOV.
From page 423...
... Challenges with this system could lead to schedule delays and may limit desired scientific performance across select observing modes. The Laser Tomography Adaptive Optics mode depends on six sodium lasers and edge sensing to < 15 nm RMS.
From page 424...
... A further risk factor for GMT is the relative immaturity of estimates for cost-to-go. Only 16 percent of these are based on signed contracts or detailed bids, with the PREPUBLICATION COPY – SUBJECT TO FURTHER EDITORIAL CORRECTION K-10
From page 425...
... . The panel has therefore considered this proposal for investment in a two-ELT PREPUBLICATION COPY – SUBJECT TO FURTHER EDITORIAL CORRECTION K-11
From page 428...
... . This plan would be rigorously reviewed by NSF to determine whether the proposed budgets represent the best PREPUBLICATION COPY – SUBJECT TO FURTHER EDITORIAL CORRECTION K-14
From page 431...
... is one of the transformational technologies that have driven breakthroughs in many areas of astronomy and astrophysics in the past two decades, by enabling ground-based telescopes to image at their diffraction-limit. AO development has led, notably, to the discovery of the supermassive black hole at the Galactic Center, the first images and spectra of exoplanets, and direct evidence for the existence of dark subhalos as predicted by Cold Dark Matter models.
From page 432...
... Second, a planet's mass is a key input for interpreting spectroscopic features in its atmosphere, since the atmospheric scale height depends on the planetary surface gravity, in addition to the mean molecular weight and temperature. There is keen interest in studying terrestrial planets, including those orbiting at Earth-like insolations around Sun-like stars, motivating a push for mass measurements to the sensitivity required for such worlds.
From page 433...
... Following this recommendation, NASA and NSF jointly commissioned a community-based Extreme Precision Radial Velocity Working Group, which recently presented the blueprint for a strategic EPRV initiative.5 K.4.4 OIR Interferometers The renaissance in stellar astrophysics in the 2010s was driven by new data and capabilities that enabled enormous advances in precision measurements of fundamental physical properties of stars: masses, radii, and luminosities. The Panel on Stars, the Sun, and Stellar Populations's first science priority is measuring fundamental stellar properties across the H-R diagram, with an emphasis on precision stellar masses and radii.
From page 434...
... investments would promote continued growth of the interferometry user community and fund new technology development efforts. Mid-scale investments in CHARA and NPOI at the high end of MSRI-2 would enable implementation of larger telescopes, longer baselines, and advanced beam combination technologies needed to deliver the greater angular resolution and photometric sensitivity required to achieve the Stars panel's science goals.
From page 435...
... First light of the 4 m DKIST telescope in early 2020 promises significant progress in the coming decade for understanding detailed physical processes in the photosphere and the low corona related to the causes of flux emergence, the dynamo that drives stellar activity cycles, the mechanisms of coronal heating and solar wind acceleration, the fundamental process of magnetic reconnection, including the triggers for sudden release of stored magnetic energy in the star's atmosphere, and the effects of stellar activity on the habitability of exoplanets around stars more or less like the Sun. DKIST first-light instruments have break-through capabilities.
From page 436...
... Improving programmatic balance, including adequate/increased support for science analysis was a major theme of the 2013 Solar and Space Physics decadal survey. Coordination with in situ and remote-sensing space-based instrumentation including Parker Solar Probe, Solar Orbiter, and Solar Dynamics Observatory is essential to address survey goals.
From page 437...
... Opening up these new windows of discovery will place heavy demands on the ground-based OIR ecosystem, for localization, classification, and the characterization of transients. In many cases, a tiered approach to follow-up OIR observations of MMA and TDA discoveries will be required, engaging the full range of the OIR telescope ecosystem: from wide-field and/or rapid slewing 1–4 m aperture telescopes for candidate discovery and filtering, to 6.5–10 m aperture telescopes for spectroscopic classification, to an extension of VRO LSST operations for deep, wide-field target-ofopportunity gravitational-wave counterpart searches, and ultimately to ELTs for detailed characterization from spectroscopy and late-time light curve evolution.
From page 438...
... , and extreme precision radial velocity spectrometer (NEID)


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