258 research outputs found
The Origin Of Radio Scintillation In The Local Interstellar Medium
No full textWe study three quasar radio sources (B1257-326, B1519-273, and J1819+385) that show large-amplitude intraday and annual scintillation variability produced by the Earth's motion relative to turbulent-scattering screens located within a few parsecs of the Sun. We find that the lines of sight to these sources pass through the edges of partially ionized warm interstellar clouds where two or more clouds may interact. From the gas flow vectors of these clouds, we find that the relative radial and transverse velocities of these clouds are large and could generate the turbulence that is responsible for the observed scintillation. For all three sight lines the flow velocities of nearby warm local interstellar clouds are consistent with the fits to the transverse flows of the radio scintillation signals.NSF AST 05-07713NASA HST-HF-01190.01, NAS 5-26555Astronom
Sodium Absorption from the Exoplanetary Atmosphere of HD 189733B Detected in the Optical Transmission Spectrum
No full textWe present the first ground-based detection of sodium absorption in the transmission spectrum of an extrasolar planet. Absorption due to the atmosphere of the extrasolar planet HD 189733b is detected in both lines of the Na I doublet. High spectral resolution observations were taken of 11 transits with the High Resolution Spectrograph ( HRS) on the 9.2 m Hobby-Eberly Telescope ( HET). The Na I absorption in the transmission spectrum due to HD 189733b is (-67.2 +/- 20.7) x 10(-5) deeper in the "narrow" spectral band that encompasses both lines relative to adjacent bands. The 1 sigma error includes both random and systematic errors, and the detection is > 3 sigma. This amount of relative absorption in Na I for HD 189733b is similar to 3 times larger than that detected for HD 209458b by Charbonneau et al. ( 2002) and indicates that these two hot Jupiters may have significantly different atmospheric properties.Hubble Fellowship grant HST-HF-01190.01NASA NAS 5-26555, NN05G107G, NNX07AL70GAstronom
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The Spin-Orbit Alignment of the HD 17156 Transiting Eccentric Planetary System
No full textWe present high- precision radial velocity observations of HD 17156 during a transit of its eccentric Jovian planet. In these data, we detect the Rossiter- McLaughlin effect, which is an apparent perturbation in the velocity of the star due to the progressive occultation of part of the rotating stellar photosphere by the transiting planet. This system had previously been reported by Narita et al. in 2008 to exhibit a lambda = 62 degrees +/- 25 degrees misalignment of the projected planetary orbital axis and the stellar rotation axis. We model our data, along with the Narita et al. data, and obtain for the combined data set. We thus conclude that the planetary orbital axis is lambda = 9.4 degrees +/- 9.3 degrees for the combined data set. We thus conclude that the planetary orbital axis is actually very well aligned with the stellar rotation axis.NASA HST-HF-01190.01, NNG05G107TPF Foundation Science Program and under Cooperative Agreement NNA06CA98AMcDonald Observator
Author's incription in The Prisoner
No full textThis edition includes an author's inscription, "Very true and faithful Alice Brown. June 25, 1916."Brown, Alice, 1857-1948.
Redfield, Martin, 1857-1948
Analysis and Evaluation of an Area Annexation Study for Redfield, South Dakota
No full textA major portion of both commercial and residential growth in the Redfield, South Dakota, area was occurring outside the existing city limits of that community in the late 1970\u27s. This pattern was becoming a concern to the Redfield City Council and prompted the city council to contact the Geography Department of South Dakota State University, Brookings, South Dakota, in 1978 to complete a study of annexation for Redfield. The author of this thesis was hired as a research assistant to complete the Redfield annexation study for the Geography Department. The city council needed to evaluate the annexation potential and problems before advancing into the actual annexation process. The study would serve as the basis of information required before annexation without petition could be allowed. The requirement for an annexation study was set forth in South Dakota Codified Law which reads in part, before a municipality may extend its boundaries to include contiguous territory, the governing body shall conduct a study to determine the need for the contiguous territory and to identify the resources necessary to extend the municipal boundaries. A letter written by Duane Sanger, Mayor of Redfield South Dakota, on behalf of the City Council requested information or advice on the following points: (1) The orderly development of the City within reasonable boundaries (2) The real estate tax impact on the City ( 3) The cost, if any, of extending City Services to the annexed areas (4) The feasibility of annexation of the State Institution located in Spink County, contiguous to the City (5) The impact of Federal and/or State with an increase in municipal population from 3,000 to 4,000 (6) The benefits, if any, the annexed areas will receive from the City (7) Other data which the City planners may use to continue the orderly development of the City\u27s growth. In the process of gathering information for the final annexation report, it became obvious to the researcher that conflicts were bound to occur. The researcher anticipated certain actions by the city council no matter what the annexation study reported. Therefore, the author attempted to present the information requested in an unbiased manner leaving the actual decision to the city council. The author felt this thesis would not be complete by presenting only the annexation study information as presented to the Redfield City Council on November 5, 1979. A look at the council\u27s decision on annexation and the resulting conflicts were an essential part of understanding the situation. The information presented in the annexation study, the actions of the city council, and the community controversy that resulted all needed to be evaluated to understand the annexation problem
A Multiwavelength Look at the GJ 9827 System: No Evidence of Extended Atmospheres in GJ 9827b and d from HST and CARMENES Data
No full textAbstract GJ 9827 is a bright star hosting a planetary system with three transiting planets. As a multiplanet system with planets that sprawl within the boundaries of the radius gap between terrestrial and gaseous planets, GJ 9827 is an optimal target to study the evolution of the atmospheres of close-in planets with a common evolutionary history and their dependence from stellar irradiation. Here we report on the Hubble Space Telescope (HST) and CARMENES transit observations of GJ 9827 planets b and d. We performed a stellar and ISM characterization from the ultraviolet HST spectra, obtaining fluxes for Ly α and Mg ii of F (Ly α ) = (5.42 ) × 10 −13 erg cm −2 s −1 and F (Mg ii ) = (5.64 ± 0.24) × 10 −14 erg cm −2 s −1 . We also investigated a possible absorption signature in Ly α in the atmosphere of GJ 9827b during a transit event from HST spectra, as well as H α and He i signature for the atmosphere of GJ 9827b and d from CARMENES spectra. We found no evidence of an extended atmosphere in either of the planets. This result is also supported by our analytical estimations of mass loss based on the measured radiation fields for all three planets of this system, which led to a mass-loss rate of 0.4, 0.3, and 0.1 planetary masses per Gyr for GJ 9827b, c, and d, respectively. These values indicate that the planets could have lost their volatiles quickly in their evolution and probably do not retain an atmosphere at the current stage
Carbon, nitrogen and phosphorus stoichiometry of rivers in the light of Redfield ratio
No full textAbstract. A. Redfield entered the history of hydroecology due to the discovery of a unique stoichiometric ratio of Carbon, Nitrogen and Phosphorus – 106: 16: 1 – in the marine plankton, which it was later named after the author – the Redfield Ratio. Furthermore, A. Redfield established, that the stoichiometric ratio of Carbon, Nitrogen and Phosphorus in seawater is supported on the average level and it is 1017 : 15 : 1. On the basis of established stoichiometric ratios A. Redfield came to the conclusion that exactly Nitrogen is a limiting factor in the marine environment, because the ratio of its average statistical stoichiometric availability in seawater turned out lower than the average stoichiometric utilization of plankton. Also the merit of A. Redfield is the was established by him the carbon and nitrogen forms, which make the greatest contribution to the pool of these elements are available for plankton. After Redfield the studies by the CNP-stoichiometry of water and plankton in marine and ocean ecosystems were carried out by a number of researchers. However, the CNP-stoichiometry of rivers water fell out of the field of view of hydroecologists. The authors of this publication tried to fill this gap. The purpose of the studies was to establish the peculiarities of CNP-stoichiometry of river ecosystems in comparison with marine ecosystems and it determine the contribution of different forms of carbon and nitrogen to the pool of these elements which available for plankton in river water. The research was conducted during the summer low water period (2014) at the at monitoring stations of watershed of the three rivers of the Carpathian region within the Chernivtsi region. It is Dniester, Prut and Siret. Water samples were taken by a bathometer at 16 sites (near 8 forest and 8 meadow floodplains) of each of the 15 monitoring stations. Under laboratory conditions, the nitrate content was determined by the nitrate meter (H-401). Carbonates and hydrogen carbonates was determined by titrimetrically method. Phosphates, ammonia and nitrites was determined by photocolorimetrically method. Like Redfield, the stoichiometric availability of Сarbon and Nitrogen in river water was estimated as the ratio of the molar concentrations of the corresponding elements to the molar Phosphorus concentration. For the first time the features of CNP stoichiometry of the rivers were installed in comparison with the marine stoichiometry. The stoichiometric ratio of total carbon, nitrogen and phosphorus in river water of the Carpathian region is 938C: 59N: 1P and the ratios of their stoichiometric availability to stoichiometric utilization by plankton is 8,9C : 3,7N : 1P. It was shown that stoichiometric availability of energetically favorable for the assimilation by plankton by forms of carbon and nitrogen – СО2 и NH4+ – in the rivers water is greatly reduced, and do not cover the necessary level of stoichiometric utilization of these elements by plankton. It is proved that the greatest contribution in the river water to the pool of stoichiometric available of carbon and nitrogen contributes HCO3-, а азота – NО3- in accordance. It was found that the main limiting factor of growth of and development of plankton in rivers of the Carpathian region appears phosphorus whose balanced share in CNP ratio is an order of magnitude lower than that it need for the utilization by plankton.</jats:p
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