CHARIS science: performance simulations for the Subaru Telescope's third-generation of exoplanet imaging instrumentation

Abstract

We describe the expected scientific capabilities of CHARIS, a high-contrast integral-field spectrograph (IFS) currently under construction for the Subaru telescope. CHARIS is part of a new generation of instruments, enabled by extreme adaptive optics (AO) systems (including SCExAO at Subaru), that promise greatly improved contrasts at small angular separation thanks to their ability to use spectral information to distinguish planets from quasistatic speckles in the stellar point-spread function (PSF). CHARIS is similar in concept to GPI and SPHERE, on Gemini South and the Very Large Telescope, respectively, but will be unique in its ability to simultaneously cover the entire near-infrared J, H, and K bands with a low-resolution mode. This extraordinarily broad wavelength coverage will enable spectral differential imaging down to angular separations of a few λ/D, corresponding to ∼0. 1. SCExAO will also offer contrast approaching 10 −5 at similar separations, ∼0. 1-0. 2. The discovery yield of a CHARIS survey will depend on the exoplanet distribution function at around 10 AU. If the distribution of planets discovered by radial velocity surveys extends unchanged to ∼20 AU, observations of ∼200 mostly young, nearby stars targeted by existing high-contrast instruments might find ∼1-3 planets. Carefully optimizing the target sample could improve this yield by a factor of a few, while an upturn in frequency at a few AU could also increase the number of detections. CHARIS, with a higher spectral resolution mode of R ∼ 75, will also be among the best instruments to characterize planets and brown dwarfs like HR 8799 cde and κ And b. We then use the thousands of mini spectra to reconstruct the data cube, the spectrum of each spatial element of the field-of-view.

Patterned liquid-crystal optics for broadband coronagraphy and wavefront sensing

“…For an IFU like CHARIS at the Subaru telescope, this is inefficient use of the instrument. CHARIS 25,26 can observe from 0.9-2.4 µm (y-K) simultaneously, so only a coronagraph with 100% bandwidth can use the full potential of such an instrument. Here we present a new grating vAPP coronagraph that will be placed in the SCExAO instrument [27][28][29] at the beginning of August 2017 to feed the CHARIS instrument.…”

Pioneering high contrast science instruments for planet characterization on giant segmented mirror telescopes

“…Post-coronagraph the light is fed to the recently commissioned facility imager, CHARIS. 19,20 The following section summarizes the core science modules of SCExAO, their status and recent results.…”

Developing linear dark-field control for exoplanet direct imaging in the laboratory and on ground-based telescopes

“…Instrument system contrasts draw from multiple sources (e.g. [8][9][10][11][12] ): those listed for JWST/NIRCam refer to the 'effective' 1.6 µm contrast achieved for intermediate-aged stars with NIRCam at 4.4 µm. 13 While high-contrast imaging testbeds simulating space-based high-contrast imaging have demonstrated significant progress towards the goal of imaging an Earth twin, maintaining a dark hole (DH) to see solar system-like planets requires extremely precise stellar halo measurements.…”