Michael T. Roman's research while affiliated with Universidad Adolfo Ibáñez and other places

... The model consists of three layers (outlined in full in Section 2.3): a deep layer assumed to be composed of a mixture of H 2 S ice and photochemical haze, a layer of photochemical haze/ice at the methane condensation level, and an extended layer of photochemical haze extending from this level up through to the stratosphere. This holistic model was then improved upon by Irwin et al. (2023) by modifying the deep aerosol layer to be a compact layer based at ∼5 bar as opposed to the original diffuse layer. ...

... We first computed clear-atmosphere models with WASP-80b's planetary parameters using the Extrasolar Giant Planet (EGP)radiative-convective-thermochemical equilibrium code (McKay et al. 1989;Marley et al. 1996;Fortney et al. 2005;Morley et al. 2012) with atmospheric metallicities of solar, 3 × solar, and 10 × solar. The resulting temperature-pressure (TP) profiles were then fed into the Community Aerosol and Radiation Model for Atmospheres (CARMA; Turco et al. 1979;Toon et al. 1988;Ackerman et al. 1995;Gao et al. 2018) to act as the background atmosphere for simulations of photochemical hazes, following the setup in Gao et al. (2023). For each metallicity, we ran soot and tholin haze models for column haze production rates between η = 10 −14 and η = 10 −9 g cm −2 s −1 with logarithmically spaced intervals of 10 0.5 . ...

... These latitudinal changes are clearly visible in Figure 1, including the dark SPW at 60°S at short wavelengths (here at 551 nm), but also prominent banded features at longer continuum wavelengths (here at 831 nm), and a small bright collar (80°S) seen about the south pole at 860 nm, which at a wavelength of strong methane absorption must be caused by increased aerosol abundance high in the atmosphere. The banding seen at 831 nm is also just visible in recent 845-nm HST/WFC3 images (e.g., Chavez et al., 2023), which covers the same reflectance peak, but at much lower spectral resolution (Δλ ∼ 84 nm). However, the banding is particularly prominent at this 831 nm, which is at the center of a reflectance peak where we can see to deep pressures in the atmosphere. ...

... Rapidly orbiting (6.2 days) a low-mass K6V star with a size of 1.96 ± 0.08 R ⊕ , a mass of 3.4 ± 0.6 M ⊕ (Kosiarek et al. 2021), and a zero-albedo equilibrium temperature of 680 ± 25 K (Rodriguez et al. 2018), GJ 9827 d allows us to obtain a high signal-to-noise ratio (S/N) in transmission spectroscopy and add a precious new target to the sample of sub-Neptunes with transit spectra. While JWST now allows one to observe the eclipses and phase curves of small exoplanets deeper in the infrared (e.g., Kempton et al. 2023), transit spectroscopy remains the best method to obtain in-depth looks into the atmospheres of sub-Neptunes and potential water worlds with HST, as they are rarely hot enough to provide a high S/N in the near-infrared (hot Neptune desert; Owen & Lai 2018). ...

... If one adopts the Eddington approximation, the proposed methods to solve the spherical RTE usually add more equations to find a converged relationship among J, H, and K (e.g., Hummer & Rybicki 1971;Unno & Kondo 1976;Simonneau 1976). The accurate solution for the spherical, extended atmosphere requires a full 3D RTE solver such as a Monte Carlo RT solver (e.g., Lucy 1999;Lee et al. 2022). ...

... Using instruments like NIRSpec (Alderson et al. 2023;Moran et al. 2023), NIRISS (Feinstein et al. 2023;Fu et al. 2022), and NIRCam (Ahrer et al. 2023), we would be able to identify prominent H 2 O lines at wavelengths 1, 1.2, 1.5, 2, and 2.8 µm . Though we have observed CH 4 lines at 1.2, 1.5, 1.8, 2.4, and 3.5 µm, in our simulation, however there is no particular detection using the JWST yet. ...

... Such long integration times are beyond our current computational resources for parameter grid we computed. Christie et al. (2022) set the simulation time on basis of evolved features which different models create early on. Important feature such as the equatorial jet can be evolved in 7 ′ 800 days (Menou 2012) for GJ 1214b. ...

... MIRI continuum emission from the troposphere (e.g., Figures 7e and 7f) reveals subtle cool zones equatorward of eastward jets at 31.5° (an inflection in the broad equatorial jet), 47.8°, 61.5°, and 78.0°N, in addition to the broad cool Equatorial Zone at <9.2°N where continuum-band cloud tracking reveals a maximum eastward windspeed (García-Melendo et al., 2011). Stratospheric banding is more subtle, but a bright equatorial band is observed in methane emission at 7.67 μm and in the peak of the acetylene emission at 13.7 μm (corresponding to the equatorial stratospheric oscillation, Orton et al., 2008;Blake et al., 2022). • NPSV: The warm NPSV, defined by the strong gradient in stratospheric brightness temperature near 78°N, is visible throughout the MIRI/MRS data set, particularly near 7-8 μm sensing stratospheric CH 4 , and in regions of tropospheric continuum emission longward of 14 μm. ...

... Short-lived chemical tracers are known to display local variations (Zhang & Showman 2018a,b). The ubiquity of patchy clouds on planets (Zhang et al. 2013;Parmentier et al. 2013;Powell et al. 2019;Feinstein et al. 2022) alters planetary albedo and infrared opacity. Furthermore, atmospheric dynamics contribute to the redistribution of heat and chemical species (Ge et al. 2019;Drummond et al. 2020;Gilli et al. 2021;Shao et al. 2022;Lee et al. 2023). ...

... The JWST (Gardner et al. 2006 ) allows for detailed spectroscopy of exoplanets, including rocky, potentially Earth-lik e w orlds. Recent data from JWST were used to identify carbon dioxide, water, sulphur dioxide, and sulphur monoxide in the atmosphere of gas giant WASP-39 b (Ahrer et al. 2022(Ahrer et al. , 2023Alderson et al. 2023 ;Feinstein et al. 2023 ;Rustamkulov et al. 2023 ), water in gas giant WASP-96 b (Pontoppidan et al. 2022 ), and carbon dioxide and methane in K2-18 b (Madhusudhan et al. 2023 ), confirming JWST 's ability to resolve specific molecular signatures. Soon upcoming missions such as the Atmospheric Remotesensing Infrared Exoplanet Large surv e y (Tinetti et al. 2018 ), Earth-2.0 (Ge et al. 2022 ), and the ESO Extremely Large Telescope (Ramsay et al. 2020 ) promise to provide more spectroscopic data focused specifically on the search for life. ...