TOI-257b (HD 19916b): A warm sub-saturn orbiting an evolved F-type star

We report the discovery of a warm sub-Saturn, TOI-257b (HD 19916b), based on data from NASA's Transiting Exoplanet Survey Satellite (TESS). The transit signal was detected by TESS and confirmed to be of planetary origin based on radial velocity observations. An analysis of the TESS photometry, the Minerva-Australis, FEROS, and HARPS radial velocities, and the asteroseismic data of the stellar oscillations reveals that TOI-257b has a mass of MP = 0.138 ± 0.023 M J (43.9 ± 7.3, M⊕), a radius of RP = 0.639 ± 0.013 R J (7.16 ± 0.15, R ⊕), bulk density of 0.65+0.12-0.11 (cgs), and period 18.38818 +0.00085 -0.00084 days. TOI-257b orbits a bright (V = 7.612 mag) somewhat evolved late F-type star with M∗ = 1.390 ± 0.046 rm M sun, R∗ = 1.888 ± 0.033 Rsun, Teff = 6075 ± 90 rm K, and vsin i = 11.3 ± 0.5 km s-1. Additionally, we find hints for a second non-transiting sub-Saturn mass planet on a ∼71 day orbit using the radial velocity data. This system joins the ranks of a small number of exoplanet host stars (∼100) that have been characterized with asteroseismology. Warm sub-Saturns are rare in the known sample of exoplanets, and thus the discovery of TOI-257b is important in the context of future work studying the formation and migration history of similar planetary systems

Understanding Chlorite and Chlorate Formation Associated with Hypochlorite Generation at Boron Doped Diamond Film Anodes

This research investigated reaction pathways for formation of chlorite and chlorate when using boron doped diamond (BDD) film anodes for generating hypochlorite. Batch electrolysis and voltammetry experiments were performed to investigate the rates and potential dependency of hypochlorite and chlorite oxidation. Density functional theory (DFT) modeling was used to investigate possible reaction pathways. The DFT simulations included reactions with hydrogen terminated surfaces, and with surface sites produced by anodic polarization, namely: ≡C•, =C•H, ≡C–O• and =C•HO. Oxychlorine radicals (ClO•, ClO2 •) were found to chemically adsorb to both secondary and tertiary carbon atoms on the BDD surface. These chemisorbed intermediates could react with hydroxyl radicals to regenerate the original chlorine oxyanion (ClO− or ClO2 −), and produce ≡C–O• and =C•HO sites on the BDD surface. The ≡C–O• and =C•HO sites also reacted with oxychlorine radicals to form chemisorbed intermediates, which could then be converted to higher oxidation states (ClO2 −, ClO3 −) via reaction with hydroxyl radicals. The predominant pathway for chlorite and chlorate production appears to involve oxidation of HOCl or HClO2 via direct electron transfer, followed by reaction of ClO• or ClO2 • with a hydroxyl radical

Properties of 42 solar-type Kepler targets from the asteroseismic modeling portal

Recently the number of main-sequence and subgiant stars exhibiting solar-like oscillations that are resolved into individual mode frequencies has increased dramatically. While only a few such data sets were available for detailed modeling just a decade ago, the Kepler mission has produced suitable observations for hundreds of new targets. This rapid expansion in observational capacity has been accompanied by a shift in analysis and modeling strategies to yield uniform sets of derived stellar properties more quickly and easily. We use previously published asteroseismic and spectroscopic data sets to provide a uniform analysis of 42 solar-type Kepler targets from the Asteroseismic Modeling Portal. We find that fitting the individual frequencies typically doubles the precision of the asteroseismic radius, mass, and age compared to grid-based modeling of the global oscillation properties, and improves the precision of the radius and mass by about a factor of three over empirical scaling relations. We demonstrate the utility of the derived properties with several applications. © 2014. The American Astronomical Society. All rights reserved.