One of the strongest Na I features was observed in WASP-96b. To confirm this novel detection, we provide a new 475-825 nm transmission spectrum obtained with Magellan/IMACS, which indeed confirms the presence of a broad sodium absorption feature. We find the same result when reanalyzing the 400-825 nm VLT/FORS2 data. We also utilize synthetic data to test the effectiveness of two common detrending techniques: (1) a Gaussian processes (GP) routine, and (2) common-mode correction followed by polynomial correction (CMC+Poly). We find that both methods poorly reproduce the absolute transit depths but maintain their true spectral shape. This emphasizes the importance of fitting for offsets when combining spectra from different sources or epochs. Additionally, we find that, for our data sets, both methods give consistent results, but CMC+Poly is more accurate and precise. We combine the Magellan/IMACS and VLT/FORS2 spectra with literature 800-1644 nm HST/ WFC3 spectra, yielding a global spectrum from 400 to 1644 nm. We used the PLATON and Exoretrievals retrieval codes to interpret this spectrum, and find that both yield relatively deeper pressures where the atmosphere is optically thick at log-pressures between 1.3(-1.1)(+1.0) and 0.29(-2.02)(+1.86) bars, respectively. Exoretrievals finds solar to supersolar Na I and H2O log-mixing ratios of -5.4(-1.9)(+2.0) and -4.5(-2.0)(+2.0), respectively, while PLATON finds an overall metallicity of log(10) (Z/Z(circle dot)) = -0.49(-0.37)(+1.0) dex. Therefore, our findings are in agreement with the literature and support the inference that the terminator of WASP-96b has few aerosols obscuring prominent features in the optical to near-infrared (near-IR) spectrum.

We present a precise ground-based optical transmission spectrum of the hot Saturn HATS-5b (T (eq) = 1025 K), obtained as part of the ACCESS survey with the IMACS multi-object spectrograph mounted on the Magellan Baade Telescope. Our spectra cover the 0.5-0.9 mu m region and are the product of five individual transits observed between 2014 and 2018. We introduce the usage of additional second-order light in our analyses, which allows us to extract an "extra" transit light curve, improving the overall precision of our combined transit spectrum. We find that the favored atmospheric model for this transmission spectrum is a solar-metallicity atmosphere with subsolar C/O, whose features are dominated by H2O and with a depleted abundance of Na and K. If confirmed, this would point to a "clear" atmosphere at the pressure levels probed by transmission spectroscopy for HATS-5b. Our best-fit atmospheric model predicts a rich near-IR spectrum, which makes this exoplanet an excellent target for future follow-up observations with the James Webb Space Telescope, both to confirm this H2O detection and to superbly constrain the atmosphere's parameters.

The characteristics of topological insulators are manifested in both their surface and bulk properties, but the latter remain to be explored. Here we report bulk signatures of pressure-induced band inversion and topological phase transitions in Pb1-xSnxSe (x = 0.00, 0.15, and 0.23). The results of infrared measurements as a function of pressure indicate the closing and the reopening of the band gap as well as a maximum in the free carrier spectral weight. The enhanced density of states near the band gap in the topological phase gives rise to a steep interband absorption edge. The change of density of states also yields a maximum in the pressure dependence of the Fermi level. Thus, our conclusive results provide a consistent picture of pressure-induced topological phase transitions and highlight the bulk origin of the novel properties in topological insulators.

The Sample Analysis at Mars instrument stepped combustion experiment on a Yellow-knife Bay mudstone at Gale crater, Mars revealed the presence of organic carbon of Martian and meteoritic origins. The combustion experiment was designed to access refractory organic carbon in Mars surface sediments by heating samples in the presence of oxygen to combust carbon to CO2. Four steps were performed, two at low temperatures (less than similar to 550 degrees C) and two at high temperatures (up to similar to 870 degrees C). More than 950 mu g C/g was released at low temperatures (with an isotopic composition of delta C-13 = +1.5 +/- 3.8) representing a minimum of 431 mu g C/g indigenous organic and inorganic Martian carbon components. Above 550 degrees C, 273 +/- 30 mu g C/g was evolved as CO2 and CO (with estimated delta C-13 = -32.9 to -10.1 for organic carbon). The source of high temperature organic carbon cannot be definitively confirmed by isotopic composition, which is consistent with macromolecular organic carbon of igneous origin, meteoritic infall, or diagenetically altered biomass, or a combination of these. If from allochthonous deposition, organic carbon could have supported both prebiotic organic chemistry and heterotrophic metabolism at Gale crater, Mars, at similar to 3.5 Ga.

We determine the quantitative morphology and star formation properties of galaxies in six nearby X-ray-detected, poor groups using multiobject spectroscopy and wide-field R imaging. The mean recessional velocities of the galaxy groups range from 2843 to 7558 km s(-1). Each group has 15-38 confirmed members ranging in luminosity from dwarfs to giants (-13.7 greater than or equal to M-R - 5 log h greater than or equal to -21.9). We measure structural parameters for each galaxy by fitting a PSF-convolved, two-component model to their surface brightness profiles. To compare the samples directly, we fade, smooth, and rebin each galaxy image so that we effectively observe each galaxy at the same redshift (9000 km s(-1)) and physical resolution (0.87 h(-1) kpc). The structural parameters are combined with [O II] measurements to test for correlations between morphological characteristics and current star formation in these galaxies. We compare results for the groups to a sample of field galaxies. We find that : (1) Galaxies spanning a wide range in morphological type and luminosity are fit well by a de Vaucouleurs bulge with exponential disk profile. (2) Morphologically classifying these nearby group galaxies by their bulge fraction (B/T) is fairly robust on average, even when their redshift has increased by up to a factor of 4 and the effective resolution of the images is degraded by up to a factor of 5. (3) The fraction of bulge-dominated systems in these groups is higher than in the field (similar to 50% versus similar to 20%). (4) The fraction of bulge-dominated systems in groups decreases with increasing radius, similar to the morphology-radius (similar to density) relation observed in galaxy clusters. (5) Current star formation in group galaxies is correlated with significant morphological asymmetry for disk-dominated systems (B/T <0.4). (6) The group galaxies that are most disk dominated (B/T <0.2) are less star forming and asymmetric on average than their counterparts in the field.

We determine the quantitative morphology and star formation properties of galaxies in six nearby X-ray-detected, poor groups using multiobject spectroscopy and wide-field R imaging. The mean recessional velocities of the galaxy groups range from 2843 to 7558 km s(-1). Each group has 15-38 confirmed members ranging in luminosity from dwarfs to giants (-13.7 greater than or equal to M-R - 5 log h greater than or equal to -21.9). We measure structural parameters for each galaxy by fitting a PSF-convolved, two-component model to their surface brightness profiles. To compare the samples directly, we fade, smooth, and rebin each galaxy image so that we effectively observe each galaxy at the same redshift (9000 km s(-1)) and physical resolution (0.87 h(-1) kpc). The structural parameters are combined with [O II] measurements to test for correlations between morphological characteristics and current star formation in these galaxies. We compare results for the groups to a sample of field galaxies. We find that : (1) Galaxies spanning a wide range in morphological type and luminosity are fit well by a de Vaucouleurs bulge with exponential disk profile. (2) Morphologically classifying these nearby group galaxies by their bulge fraction (B/T) is fairly robust on average, even when their redshift has increased by up to a factor of 4 and the effective resolution of the images is degraded by up to a factor of 5. (3) The fraction of bulge-dominated systems in these groups is higher than in the field (similar to 50% versus similar to 20%). (4) The fraction of bulge-dominated systems in groups decreases with increasing radius, similar to the morphology-radius (similar to density) relation observed in galaxy clusters. (5) Current star formation in group galaxies is correlated with significant morphological asymmetry for disk-dominated systems (B/T <0.4). (6) The group galaxies that are most disk dominated (B/T <0.2) are less star forming and asymmetric on average than their counterparts in the field.

We determine the quantitative morphology and star formation properties of galaxies in six nearby X-ray-detected, poor groups using multiobject spectroscopy and wide-field R imaging. The mean recessional velocities of the galaxy groups range from 2843 to 7558 km s(-1). Each group has 15-38 confirmed members ranging in luminosity from dwarfs to giants (-13.7 greater than or equal to M-R - 5 log h greater than or equal to -21.9). We measure structural parameters for each galaxy by fitting a PSF-convolved, two-component model to their surface brightness profiles. To compare the samples directly, we fade, smooth, and rebin each galaxy image so that we effectively observe each galaxy at the same redshift (9000 km s(-1)) and physical resolution (0.87 h(-1) kpc). The structural parameters are combined with [O II] measurements to test for correlations between morphological characteristics and current star formation in these galaxies. We compare results for the groups to a sample of field galaxies. We find that : (1) Galaxies spanning a wide range in morphological type and luminosity are fit well by a de Vaucouleurs bulge with exponential disk profile. (2) Morphologically classifying these nearby group galaxies by their bulge fraction (B/T) is fairly robust on average, even when their redshift has increased by up to a factor of 4 and the effective resolution of the images is degraded by up to a factor of 5. (3) The fraction of bulge-dominated systems in these groups is higher than in the field (similar to 50% versus similar to 20%). (4) The fraction of bulge-dominated systems in groups decreases with increasing radius, similar to the morphology-radius (similar to density) relation observed in galaxy clusters. (5) Current star formation in group galaxies is correlated with significant morphological asymmetry for disk-dominated systems (B/T <0.4). (6) The group galaxies that are most disk dominated (B/T <0.2) are less star forming and asymmetric on average than their counterparts in the field.

Based on observations of the Seyfert nucleus in NGC 1068 with ASCA, RXTE, and BeppoSAX, we report the discovery of a are (increase in flux by a factor of similar to1.6) in the 6.7 keV Fe K line component between observations obtained 4 months apart, with no significant change in the other (6.21, 6.4, and 6.97 keV) Fe Kalpha line components. During this time, the continuum flux decreased by similar to20%. The RXTE spectrum requires an Fe K absorption edge near 8.6 keV (Fe XXIII-XXV). The spectral data indicate that the 2-10 keV continuum emission is dominated (similar to2/3 of the luminosity) by reflection from a previously unidentified region of warm, ionized gas located less than or similar to0.2 pc from the AGN. The remaining similar to1/3 of the observed X-ray emission is reflected from optically thick, neutral gas. The coronal gas in the inner narrow-line region and/or the cold gas at the inner surface of the obscuring "torus" are possible cold reflectors. The inferred properties of the warm reflector are size (diameter) less than or similar to0.2 pc, gas density ngreater than or similar to10(5.5) cm(-3), ionization parameter xiapproximate to10(3.5) ergs cm s(-1), and covering fraction 0.003(L-0/10(43.5) ergs s(-1))(-1) <(&UOmega;/4π)<0.024(L-0/10(43.5) ergs s(-1))(-1), where L-0 is the intrinsic 2-10 keV X-ray luminosity of the AGN. We suggest that the warm reflector gas is the source of the ( variable) 6.7 keV Fe line emission and the 6.97 keV Fe line emission. The 6.7 keV line are is assumed to be due to an increase in the emissivity of the warm reflector gas from a decrease (by 20%-30%) in L-0. The properties of the warm reflector are most consistent with an intrinsically X-ray weak AGN with L(0)approximate to10(43.0) ergs s(-1). The optical and UV emission that scatters from the warm reflector into our line of sight is required to suffer strong extinction, which can be reconciled if the line of sight skims the outer surface of the torus. Thermal brems-strahlung radio emission from the warm reflector may be detectable in Very Long Baseline Array radio maps of the NGC 1068 nucleus.

Based on observations of the Seyfert nucleus in NGC 1068 with ASCA, RXTE, and BeppoSAX, we report the discovery of a are (increase in flux by a factor of similar to1.6) in the 6.7 keV Fe K line component between observations obtained 4 months apart, with no significant change in the other (6.21, 6.4, and 6.97 keV) Fe Kalpha line components. During this time, the continuum flux decreased by similar to20%. The RXTE spectrum requires an Fe K absorption edge near 8.6 keV (Fe XXIII-XXV). The spectral data indicate that the 2-10 keV continuum emission is dominated (similar to2/3 of the luminosity) by reflection from a previously unidentified region of warm, ionized gas located less than or similar to0.2 pc from the AGN. The remaining similar to1/3 of the observed X-ray emission is reflected from optically thick, neutral gas. The coronal gas in the inner narrow-line region and/or the cold gas at the inner surface of the obscuring "torus" are possible cold reflectors. The inferred properties of the warm reflector are size (diameter) less than or similar to0.2 pc, gas density ngreater than or similar to10(5.5) cm(-3), ionization parameter xiapproximate to10(3.5) ergs cm s(-1), and covering fraction 0.003(L-0/10(43.5) ergs s(-1))(-1) <(&UOmega;/4π)<0.024(L-0/10(43.5) ergs s(-1))(-1), where L-0 is the intrinsic 2-10 keV X-ray luminosity of the AGN. We suggest that the warm reflector gas is the source of the ( variable) 6.7 keV Fe line emission and the 6.97 keV Fe line emission. The 6.7 keV line are is assumed to be due to an increase in the emissivity of the warm reflector gas from a decrease (by 20%-30%) in L-0. The properties of the warm reflector are most consistent with an intrinsically X-ray weak AGN with L(0)approximate to10(43.0) ergs s(-1). The optical and UV emission that scatters from the warm reflector into our line of sight is required to suffer strong extinction, which can be reconciled if the line of sight skims the outer surface of the torus. Thermal brems-strahlung radio emission from the warm reflector may be detectable in Very Long Baseline Array radio maps of the NGC 1068 nucleus.

Based on observations of the Seyfert nucleus in NGC 1068 with ASCA, RXTE, and BeppoSAX, we report the discovery of a are (increase in flux by a factor of similar to1.6) in the 6.7 keV Fe K line component between observations obtained 4 months apart, with no significant change in the other (6.21, 6.4, and 6.97 keV) Fe Kalpha line components. During this time, the continuum flux decreased by similar to20%. The RXTE spectrum requires an Fe K absorption edge near 8.6 keV (Fe XXIII-XXV). The spectral data indicate that the 2-10 keV continuum emission is dominated (similar to2/3 of the luminosity) by reflection from a previously unidentified region of warm, ionized gas located less than or similar to0.2 pc from the AGN. The remaining similar to1/3 of the observed X-ray emission is reflected from optically thick, neutral gas. The coronal gas in the inner narrow-line region and/or the cold gas at the inner surface of the obscuring "torus" are possible cold reflectors. The inferred properties of the warm reflector are size (diameter) less than or similar to0.2 pc, gas density ngreater than or similar to10(5.5) cm(-3), ionization parameter xiapproximate to10(3.5) ergs cm s(-1), and covering fraction 0.003(L-0/10(43.5) ergs s(-1))(-1) <(&UOmega;/4π)<0.024(L-0/10(43.5) ergs s(-1))(-1), where L-0 is the intrinsic 2-10 keV X-ray luminosity of the AGN. We suggest that the warm reflector gas is the source of the ( variable) 6.7 keV Fe line emission and the 6.97 keV Fe line emission. The 6.7 keV line are is assumed to be due to an increase in the emissivity of the warm reflector gas from a decrease (by 20%-30%) in L-0. The properties of the warm reflector are most consistent with an intrinsically X-ray weak AGN with L(0)approximate to10(43.0) ergs s(-1). The optical and UV emission that scatters from the warm reflector into our line of sight is required to suffer strong extinction, which can be reconciled if the line of sight skims the outer surface of the torus. Thermal brems-strahlung radio emission from the warm reflector may be detectable in Very Long Baseline Array radio maps of the NGC 1068 nucleus.