SCExAO/MEC and CHARIS Discovery of a Low Mass, 6 AU-Separation Companion to HIP 109427 using Stochastic Speckle Discrimination and High-Contrast Spectroscopy

We report the direct imaging discovery of a low-mass companion to the nearby accelerating A star, HIP 109427, with the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument coupled with the MKID Exoplanet Camera (MEC) and CHARIS integral field spectrograph. CHARIS data reduced with reference star PSF subtraction yield 1.1-2.4 $\mu$m spectra. MEC reveals the companion in $Y$ and $J$ band at a comparable signal-to-noise ratio using stochastic speckle discrimination, with no PSF subtraction techniques. Combined with complementary follow-up $L_{\rm p}$ photometry from Keck/NIRC2, the SCExAO data favors a spectral type, effective temperature, and luminosity of M4-M5.5, 3000-3200 $K$, and $\log_{10}(L/L_{\rm \odot}) = -2.28^{+0.04}_{-0.04}$, respectively. Relative astrometry of HIP 109427 B from SCExAO/CHARIS and Keck/NIRC2, and complementary Gaia-Hipparcos absolute astrometry of the primary favor a semimajor axis of $6.55^{+3.0}_{-0.48}$ au, an eccentricity of $0.54^{+0.28}_{-0.15}$, an inclination of $66.7^{+8.5}_{-14}$ degrees, and a dynamical mass of $0.280^{+0.18}_{-0.059}$ $M_{\odot}$. This work shows the potential for extreme AO systems to utilize speckle statistics in addition to widely-used post-processing methods to directly image faint companions to nearby stars near the telescope diffraction limit.Comment: 13 pages, 7 figures, 3 table

MKID digital readout tuning with deep learning

Microwave Kinetic Inductance Detector (MKID) devices offer inherent spectral resolution, simultaneous read out of thousands of pixels, and photon-limited sensitivity at optical wavelengths. Before taking observations the readout power and frequency of each pixel must be individually tuned, and if the equilibrium state of the pixels change, then the readout must be retuned. This process has previously been performed through manual inspection, and typically takes one hour per 500 resonators (20 h for a ten-kilo-pixel array). We present an algorithm based on a deep convolution neural network (CNN) architecture to determine the optimal bias power for each resonator. The bias point classifications from this CNN model, and those from alternative automated methods, are compared to those from human decisions, and the accuracy of each method is assessed. On a test feed-line dataset, the CNN achieves an accuracy of 90% within 1 dB of the designated optimal value, which is equivalent accuracy to a randomly selected human operator, and superior to the highest scoring alternative automated method by 10%. On a full ten-kilopixel array, the CNN performs the characterization in a matter of minutes — paving the way for future mega-pixel MKID arrays

The ARCONS Pipeline: Data Reduction for MKID Arrays

The Array Camera for Optical to Near-IR Spectrophotometry, or ARCONS, is a camera based on Microwave Kinetic Inductance Detectors (MKIDs), a new technology that has the potential for broad application in astronomy. Using an array of MKIDs, the instrument is able to produce time-resolved imaging and low-resolution spectroscopy constructed from detections of individual photons. The arrival time and energy of each photon are recorded in a manner similar to X-ray calorimetry, but at higher photon fluxes. The technique works over a very large wavelength range, is free from fundamental read noise and dark-current limitations, and provides microsecond-level timing resolution. Since the instrument reads out all pixels continuously while exposing, there is no loss of active exposure time to readout. The technology requires a different approach to data reduction compared to conventional CCDs. We outline here the prototype data reduction pipeline developed for ARCONS, though many of the principles are also more broadly applicable to energy-resolved photon counting arrays (e.g., transition edge sensors, superconducting tunnel junctions). We describe the pipeline's current status, and the algorithms and techniques employed in taking data from the arrival of photons at the MKID array to the production of images, spectra, and time-resolved light curves.Comment: 16 pages, 19 figures, pdflatex, accepted for ApJ

A Technology and Science Gap List for Habitable-Zone Exoplanet Imaging with Ground-Based Extremely Large Telescopes

The Pathways to Discovery in Astronomy and Astrophysics for the 2020s decadal survey highlighted the ability of the coming generation of 30-meter-class telescopes “to detect, image, and characterize temperate rocky planets around low-mass stars, measure their atmospheric compositions including searches for oxygen.” However, many of the technologies required to reach the challenging contrast ratios associated with this science case are not yet available, and targeted preparatory science must be carried out well in advance of these observations. In this paper, we draw from the example of NASA's Exoplanet Exploration Program and propose a preliminary version of a “Technology Gap List” and “Science Gap List” for the ground-based imaging of rocky planets around the nearest stars with extremely large ground-based telescopes. These lists can be used to prioritize precursor technical demonstrations and observations with current and near-term high contrast instrumentation, so that the community is ready to exploit the collecting area of extremely large telescopes. © 2022 SPIE.Immediate accessThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Direct detection of SDSS J0926+3624 orbital expansion with ARCONS

AM Canum Venaticorum (AM CVn) stars belong to a class of ultracompact, short-period binaries with spectra dominated largely by helium. SDSS J0926+3624 is of particular interest as it is the first observed eclipsing AM CVn system. We observed SDSS J0926+3624 with the Array Camera for Optical to Near-IR Spectrophotometry (ARCONS) at the Palomar 200″ telescope. ARCONS uses a relatively new type of energy-resolved photon counters called Microwave Kinetic Inductance Detectors. ARCONS, sensitive to radiation from 350 to 1100 nm, has a time resolution of several microseconds and can measure the energy of a photon to ∼10 per cent. We present the light curves for these observations and examine changes in orbital period from prior observations. Using a quadratic ephemeris model, we measure a period rate of change Ṗ = (3.07 ± 0.56) × 10−13. In addition, we use the high timing resolution of ARCONS to examine the system's high-frequency variations and search for possible quasi-periodic oscillations (QPOs). Finally, we use the instrument's spectral resolution to examine the light curves in various wavelength bands. We do not find any high-frequency QPOs or significant spectral variability throughout an eclipse

ARCONS: A 2024 Pixel Optical through Near-IR Cryogenic Imaging Spectrophotometer

We present the design, construction, and commissioning results of ARCONS, the Array Camera for Optical to Near-IR Spectrophotometry. ARCONS is the first ground-based instrument in the optical through near-IR wavelength range based on Microwave Kinetic Inductance Detectors (MKIDs). MKIDs are revolutionary cryogenic detectors, capable of detecting single photons and measuring their energy without filters or gratings, similar to an X-ray microcalorimeter. MKIDs are nearly ideal, noiseless photon detectors, as they do not suffer from read noise or dark current and have nearly perfect cosmic ray rejection. ARCONS is an Integral Field Spectrograph (IFS) containing a lens-coupled 2024 pixel MKID array yielding a 20"x20" field of view, and has been deployed on the Palomar 200" and Lick 120" telescopes for 24 nights of observing. We present initial results showing that ARCONS and its MKID arrays are now a fully operational and powerful tool for astronomical observations.Comment: 12 pages, 16 figures, submitted to PAS

An Updated Preliminary Optical Design and Performance analysis of the Planetary Systems Imager Adaptive Optics System

The Planetary Systems Imager (PSI), a proposed instrument suite for the Thirty Meter Telescope (TMT), enables a broad range of extreme-AO, high-contrast observations. PSI is specifically optimized for high contrast exoplanet science from 0.5 to 13 µm and to that end includes a core near-IR AO system that feeds multiple AO+science instrument subsystems. In this paper, we present a preliminary optical design for the full PSI-AO system, feeding the PSI-Red (2-5 µm), PSI-Blue (0.5-1.8 µm), and PSI-10 (8-13 µm) subsystems. We discuss an initial concept of testing and operations for the system that feeds into the conceptual design. We build on our preliminary end-to-end PSI-Red AO simulation to estimate the raw planet-to-star contrast ratios associated with PSI-Red and extrapolate these results to represent the effects of a PSI-Blue deformable mirror. © 2022 SPIE.Immediate accessThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

The Planetary Systems Imager for TMT: Overview and Status

We provide a summary review of the scientific and technical capabilities and the overall project status of the Planetary Systems Instrument (PSI), a second-generation instrumentation suite for the TMT. The instrument seeks to determine the composition and energy balance of exoplanets through the joint measurement of planet-reflected starlight and thermal emission, as well as constrain planet formation and evolution scenarios through high-spectral-resolution characterization of exoplanet atmospheres. The PSI instrument concept operates from optical to thermal infrared wavelengths, combining high-order AO correction with pupil- and focal-plane wavefront sensing, coronagraphs, imaging and low-resolution integral-field spectroscopy, as well as fiber-coupled high-resolution spectrometers. The modular design enables simultaneous characterization of exoplanets at multiple wavelengths, allows for phased deployment and commissioning, and provides upgrade paths to accommodate potential technological advances. We will provide an overview of the past two years of development, including description of the key scientific and technical requirement development and flowdown, AO and science output performance simulation, optical conceptual design of the front-end AO system, and the status of precursor instrumentation and techniques. © 2022 SPIE.Immediate accessThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]