A Temperature and Abundance Retrieval Method for Exoplanet Atmospheres

We present a new method to retrieve molecular abundances and temperature profiles from exoplanet atmosphere photometry and spectroscopy. We run millions of 1D atmosphere models in order to cover the large range of allowed parameter space, and present error contours in the atmospheric properties, given the data. In order to run such a large number of models, we have developed a parametric pressure-temperature (P-T) profile coupled with line-by-line radiative transfer, hydrostatic equilibrium, and energy balance, along with prescriptions for non-equilibrium molecular composition and energy redistribution. We apply our temperature and abundance retrieval method to the atmospheres of two transiting exoplanets, HD 189733b and HD 209458b, which have the best available Spitzer and HST observations. For HD 189733b, we find efficient day-night redistribution of energy in the atmosphere, and molecular abundance constraints confirming the presence of H2O, CO, CH4, and CO2. For HD 209458b, we confirm and constrain the day-side thermal inversion in an average 1D temperature profile. We also report independent detections of H$_2$O, CO, CH$_4$ and CO$_2$ on the dayside of HD 209458b, based on six-channel Spitzer photometry. We report constraints for HD 189733b due to individual data sets separately; a few key observations are variable in different data sets at similar wavelengths. Moreover, a noticeably strong carbon dioxide absorption in one data set is significantly weaker in another. We must, therefore, acknowledge the strong possibility that the atmosphere is variable, both in its energy redistribution state and in the chemical abundances.Comment: 20 pages in emulateapj format, 11 figures. Final version, after proof correction

JexoSim 2.0: End-to-end JWST simulator for exoplanet spectroscopy – implementation and case studies

The recently developed JWST Exoplanet Observation Simulator (JexoSim) simulates transit spectroscopic observations of exoplanets by JWST with each of its four instruments using a time-domain approach. Previously we reported the validation of JexoSim against Pandexo and instrument team simulators. In the present study, we report a substantially enhanced version, JexoSim 2.0, which improves on the original version through incorporation of new noise sources, enhanced treatment of stellar and planetary signals and instrumental effects, as well as improved user-operability and optimisations for increased speed and efficiency. A near complete set of instrument modes for exoplanet time-series observations is now included. In this paper we report the implementation of JexoSim 2.0 and assess performance metrics for JWST in end-member scenarios using the hot Jupiter HD 209458 b and the mini-Neptune K2-18 b. We show how JexoSim can be used to compare performance across the different JWST instruments, selecting an optimal combination of instrument and subarray modes, producing synthetic transmission spectra for each planet. These studies indicate that the 1.4 {\mu}m water feature detected in the atmosphere of K2-18 b using the Hubble WFC3 might be observable in just one transit observation with JWST with either NIRISS or NIRSpec. JexoSim 2.0 can be used to investigate the impact of complex noise and systematic effects on the final spectrum, plan observations and test the feasibility of novel science cases for JWST. It can also be customised for other astrophysical applications beyond exoplanet spectroscopy. JexoSim 2.0 is now available for use by the scientific community

Adjunctive use of systematic retinal thickness map analysis to monitor disease activity in punctate inner choroidopathy

A challenge in the management of 'white dot syndromes' is the lack of sensitive objective measures of disease activity. Retinal thickness maps from spectral domain optical coherence tomography (SD-OCT) inform treatment decisions in other retinal conditions such as age-related macular degeneration and diabetic maculopathy. In this report, we demonstrate their value in providing quantitative monitoring of a patient with punctate inner choroidopathy (PIC). Retinal thickness maps referenced against a baseline scan reliably detected focal areas of increased macular volume in active PIC lesions during symptomatic episodes, highlighting these as 'hot spots' that could be quantified, providing an objective basis for treatment decisions

Molecular identification of insecticide degradation by gut bacteria isolated from Helicoverpa armigera of Cotton plants

The cotton bollworm Helicoverpa armigera occurs as a major pest in many economically important crops, including cotton, pigeon pea, chickpea, pea, cowpea, sunflower, tomato, sorghum, pearl millet and other crops. Intestinal microorganisms play important role in the degradation of diet components of insects. In order to know the role of gut bacteria in insecticide resistance five   insecticides Chlorpyriphos (20% EC), Cypermethrin (25% EC), Malathion (50% EC), Quinalphos (25% EC), Triazophos (40% EC), were selected for the insecticide degradation studies. All the bacterial isolates from the gut of lab and field populations of H. armigera were identified using 16S rRNA gene-based identification and tested for their growth on minimal salt medium (MSM) along with the selected insecticides. A total of 11 bacterial isolates were tested and among them, isolate CL4 (Rhodococcus sp.) was found to grow on minimal salt medium (MSM) and with chlorpyriphos and isolate CL2 (Enterococcus casseliflavus) was able to grow in MSM with chloropyriphos (C22H19Cl2NO3) and malathion (C10H19O6PS2) and no growth was seen in MSM without insecticide (control).  Gas Chromatography analysis of the positive bacterial isolate cultures in MSM showed that the isolate CL4 (Rhodococcus sp.) was able to utilize 43.9% of chlorpyriphos and isolate CL2 (E.casseliflavus) was able to utilize 26% of chlorpyriphos and 57.1% of malathion in MSM broth cultures with comparison with the respective control cultures. Findings of the current work suggested that gut bacteria in the field populations of H. armigera plays a role in insecticide resistanc

Habitability and Biosignatures of Hycean Worlds

We investigate a new class of habitable planets composed of water-rich interiors with massive oceans underlying H2-rich atmospheres, referred to here as Hycean worlds. With densities between those of rocky super-Earths and more extended mini-Neptunes, Hycean planets can be optimal candidates in the search for exoplanetary habitability and may be abundant in the exoplanet population. We investigate the bulk properties (masses, radii, and temperatures), potential for habitability, and observable biosignatures of Hycean planets. We show that Hycean planets can be significantly larger compared to previous considerations for habitable planets, with radii as large as 2.6 Earth radii (2.3 Earth radii) for a mass of 10 Earth masses (5 Earth masses). We construct the Hycean habitable zone (HZ), considering stellar hosts from late M to sun-like stars, and find it to be significantly wider than the terrestrial-like HZ. While the inner boundary of the Hycean HZ corresponds to equilibrium temperatures as high as ~500 K for late M dwarfs, the outer boundary is unrestricted to arbitrarily large orbital separations. Our investigations include tidally locked `Dark Hycean' worlds that permit habitable conditions only on their permanent nightsides and `Cold Hycean' worlds that see negligible irradiation. Finally, we investigate the observability of possible biosignatures in Hycean atmospheres. We find that a number of trace terrestrial biomarkers which may be expected to be present in Hycean atmospheres would be readily detectable using modest observing time with the James Webb Space Telescope (JWST). We identify a sizable sample of nearby potential Hycean planets that can be ideal targets for such observations in search of exoplanetary biosignatures

A Study on the Seismic Response of Ground and Reinforced Concrete Buildings in Belgaum Region, India

In the recent years, each unpredictable earthquake (for example Kobe, 1995; Taiwan, 1999; Kocaeli, 1999 and Bhuj, 2001) has revealed its own saga of destruction and failure of engineered structures. Therefore, regional variation in potential earthquake damage should be carefully assessed for better planning towards disaster mitigation. This requires assessment of the seismic ground motion parameters. The present study focus on the seismic response of ground and reinforced concrete buildings in Belgaum region (located in zone III, as per IS 1893–Part1: 2002) in Karnataka state. At present no strong motion records are available in this region and therefore, wavelet-based spectrum compatibility approach is used to generate synthetic earthquake motions for the region. The effect of soil deposits in the region on propagation of seismic motion parameters to the ground surface is investigated based on equivalent linear approach. The Frequency response analysis of buildings of various configurations is carried out with three dimensional numerical modeling. The results indicate the maximum spectral accelerations at the ground surface in the range of 0.68g to 1.29g and peak ground acceleration (PGA) amplifications in the range of 2.16 to 3.13. The predicted fundamental period of soil deposits in the region varies from 0.2 s to 0.4 s. The configuration of buildings susceptible to resonance due to the close matching of resulting wave frequencies of the ground is identified

Infrared Eclipses of the Strongly Irradiated Planet WASP-33b, and Oscillations of its Host Star

We observe two secondary eclipses of the strongly irradiated transiting planet WASP-33b in the Ks band, and one secondary eclipse each at 3.6- and 4.5 microns using Warm Spitzer. This planet orbits an A5V delta-Scuti star that is known to exhibit low amplitude non-radial p-mode oscillations at about 0.1-percent semi-amplitude. We detect stellar oscillations in all of our infrared eclipse data, and also in one night of observations at J-band out of eclipse. The oscillation amplitude, in all infrared bands except Ks, is about the same as in the optical. However, the stellar oscillations in Ks band have about twice the amplitude as seen in the optical, possibly because the Brackett-gamma line falls in this bandpass. We use our best-fit values for the eclipse depth, as well as the 0.9 micron eclipse observed by Smith et al., to explore possible states of the exoplanetary atmosphere, based on the method of Madhusudhan and Seager. On this basis we find two possible states for the atmospheric structure of WASP-33b. One possibility is a non-inverted temperature structure in spite of the strong irradiance, but this model requires an enhanced carbon abundance (C/O>1). The alternative model has solar composition, but an inverted temperature structure. Spectroscopy of the planet at secondary eclipse, using a spectral resolution that can resolve the water vapor band structure, should be able to break the degeneracy between these very different possible states of the exoplanetary atmosphere. However, both of those model atmospheres absorb nearly all of the stellar irradiance with minimal longitudinal re-distribution of energy, strengthening the hypothesis of Cowan et al. that the most strongly irradiated planets circulate energy poorly. Our measurement of the central phase of the eclipse yields e*cos(omega)=0.0003 +/-0.00013, which we regard as being consistent with a circular orbit.Comment: 23 pages, 9 figures, 3 tables, accepted for the Astrophysical Journa

Influence of the C/O ratio on titanium and vanadium oxides in protoplanetary disks

Context. The observation of carbon-rich disks have motivated several studies questioning the influence of the C/O ratio on their gas phase composition in order to establish the connection between the metallicity of hot-Jupiters and that of their parent stars. Aims. We to propose a method that allows the characterization of the adopted C/O ratio in protoplanetary disks independently from the determination of the host star composition. Titanium and vanadium chemistries are investigated because they are strong optical absorbers and also because their oxides are known to be sensitive to the C/O ratio in some exoplanet atmospheres. Methods. We use a commercial package based on the Gibbs energy minimization technique to compute the titanium and vanadium equilibrium chemistries in protoplanetary disks for C/O ratios ranging from 0.05 to 10. Our calculations are performed for pressures ranging from 1e-6 to 1e-2 bar, and for temperatures ranging from 50 to 2000 K. Results. We find that the vanadium nitride/vanadium oxide and titanium hydride/titanium oxide gas phase ratios strongly depend on the C/O ratio in the hot parts of disks (T > 1000 K). Our calculations suggest that, in these regions, these ratios can be used as tracers of the C/O value in protoplanetary disks.Comment: Accepted for publication in A&