Probing Exoplanet Atmospheric Properties from Phase Variations and Polarization
Laura Mayorga, NMSU
The study of exoplanets is evolving past simple transit and Doppler method discovery and characterization. One of the many goals of the upcoming mission WFIRST-AFTA is to directly image giant exoplanets with a coronagraph. We undertake a study to determine the types of exoplanets that missions such as WFIRST will encounter and what instruments these missions require to best characterize giant planet atmospheres. We will first complete a benchmark study of how Jupiter reflects and scatters light as a function of phase angle. We will use Cassini flyby data from late 2000 to measure Jupiter’s phase curve, spherical albedo, and degree of polarization. Using Jupiter as a comparison, we will then study a sample of exoplanet atmosphere models generated to explore the atmospheric parameter space of giant planets and estimate what WFIRST might observe. Our study will provide valuable refinements to Jupiter-like models of planet evolution and atmospheric composition. We will also help inform future missions of what instruments are needed to characterize similar planets and what science goals will further our knowledge of giant worlds in our universe.
High Resolution Spectroscopy with Immersion Grating Infrared Spectrometer (IGRINS)
Hwihyun Kim, KASI/UT Austin
The Immersion Grating Infrared Spectrometer (IGRINS) is a revolutionary instrument that exploits broad spectral coverage at high-resolution (R=45,000) in the near-infrared. IGRINS employs a silicon immersion grating as the primary disperser of the white pupil, and volume-phase holographic gratings cross-disperse the H and K bands onto Teledyne Hawaii-2RG arrays. IGRINS provides simultaneous wavelength coverage from 1.45 – 2.45 microns in a compact cryostat. I will summarize the performance and various science programs of IGRINS since commissioning in Summer 2014. With IGRINS we have observed such as Solar System objects, nearby young stars, star-forming regions like Taurus and Ophiuchus, the Galactic Center, and planetary nebulae.
The second half of my talk will be focused on the study of ionized and neutral gas in an ultracompact HII region Monoceros R2. We obtained the IGRINS spectra of Mon R2 to study the kinematic patterns in the areas where ionized and molecular gases interact. The position-velocity maps from the IGRINS spectra demonstrate that the ionized gases (Brackett and Pfund series, He and Fe emission lines;Δv ≈ 40km/s) flow along the walls of the surrounding clouds. This is consistent with the model by Zhu et al. (2005, 2008). In the PV maps of the H2 emission lines there is no obvious motion (Δv < ~10km/s) of the molecular hydrogen right at the ionization boundary. This implies that the molecular gas is not taking part in the flow as the ionized gas is moving along the cavity walls.