9,922 research outputs found
To Peek or Not to Peek: Inadvertant or Unsolicited Disclosure of Documents to Opposing Counsel
A history of the city of Somerville for the first four grades
Thesis (Ed.M.)--Boston Universit
Using the chromatic Rossiter-McLaughlin effect to probe the broadband signature in the optical transmission spectrum of HD 189733b
Transmission spectroscopy is a powerful technique for probing exoplanetary
atmospheres. A successful ground-based observational method uses a differential
technique based on high-dispersion spectroscopy, but that only preserves narrow
features in transmission spectra. Here we use the chromatic Rossiter-McLaughlin
(RM) effect to measure the Rayleigh-scattering slope in the transmission
spectrum of HD 189733b with the aim to show that it can be effectively used to
measure broadband transmission features. The amplitude of the RM effects
depends on the effective size of the planet, and in the case of an atmospheric
contribution therefore depends on the observed wavelength. We analysed archival
HARPS data of three transits of HD 189733b, covering a wavelength range of 400
to 700 nm. We measured the slope in the transmission spectrum of HD 189733b at
a significance. Assuming it is due to Rayleigh scattering and not
caused by stellar activity, it would correspond to an atmospheric temperature,
as set by the scale height, of , well in line with
previously obtained results. This shows that ground-based high-dispersion
spectral observations can be used to probe broad-band features in the
transmission spectra of extrasolar planets, by using the chromatic RM effect.
This method will be particularly interesting in conjunction with the new
echelle spectrograph ESPRESSO, which currently is under construction for ESOs
Very Large Telescope and will provide a gain in signal-to-noise ratio of about
a factor 4 compared to HARPS. This will be of great value because of the
limited and uncertain future of the Hubble Space Telescope and because the
future James Webb Space Telescope will not cover this wavelength regime.Comment: 8 pages, 7 figures, accepted for publication on Astronomy and
Astrophysic
Exploratory Study on Selected Philippine Agricultural Commodity Import Statistics vis-Ã -vis Export Statistics of the Exporting Countries
Using the import data compiled by the Philippines and comparing these with data as reported by the exporting countries, this study aims to determine the disparity of the statistics from the two sources on the quantity and value of selected agricultural commodities for the years 2000 to 2005. The products covered by this study consist of wholly or semi-milled rice, maize (corn), live poultry, domestic fowls, ducks, geese, frozen meat of bovine animals, apples, oranges, onions and shallots, and garlic. The differences in statistics on the bilateral transactions─in terms of FOB values, quantities, and derived unit prices─are examined by using percentage differences, the implicit minimal measurement error (IMME), and the Wilcoxon Matched-Pair Signed-Ranks (Wilcoxon-MPSR) test. Results show that considerable discrepancies between import and export statistics do exist. The discrepancy may reflect both legitimate conceptual differences between Philippine imports and exports statistics of the exporting countries, as well as errors in reporting. The discrepancy is further substantiated by the results of the Wilcoxon-MPSR test, which show that these differences are significant.
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