Photometric Solutions for Detached Eclipsing Binaries: selection of ideal distance indicators in the SMC

Detached eclipsing binary stars provide a robust one-step distance determination to nearby galaxies. As a by-product of Galactic microlensing searches, catalogs of thousands of variable stars including eclipsing binaries have been produced by the OGLE, MACHO and EROS collaborations. We present photometric solutions for detached eclipsing binaries in the Small Magellanic Cloud (SMC) discovered by the OGLE collaboration. The solutions were obtained with an automated version of the Wilson-Devinney program. By fitting mock catalogs of eclipsing binaries we find that the normalized stellar radii (particularly their sum) and the surface brightness ratio are accurately described by the fitted parameters and estimated standard errors, despite various systematic uncertainties. In many cases these parameters are well constrained. In addition we find that systems exhibiting complete eclipses can be reliably identified where the fractional standard errors in the radii are small. We present two quantitatively selected sub-samples of eclipsing binaries that will be excellent distance indicators. These can be used both for computation of the distance to the SMC and to probe its structure. One particularly interesting binary has a very well determined solution, exhibits complete eclipses, and is comprised of well detached G-type, class $II$ giants.Comment: 29 pages, 12 figures. To be published in Ap

Measurements of Aerosol Size and Microphysical Properties: A Comparison Between Raman Lidar and Airborne Sensors

This manuscript compares measurements of aerosol size distributions and microphysical properties retrieved from the Raman lidar BASIL with those obtained from a series of aircraft sensors during HyMeX-SOP1. The attention is focused on a measurement session on 02 October 2012, with BASIL measurements revealing the presence of a lower aerosol layer extending up to 3.3 km and an elevated layer extending from 3.6 to 4.6 km. Aerosol size distribution and microphysical properties are determined from multi-wavelength particle backscattering and extinction profile measurements through a retrieval approach based on Tikhonov regularization. A good agreement is found between BASIL and the microphysical sensors' measurements for all considered aerosol size and microphysical properties. Specifically, BASIL and in-situ volume concentration values are in the range 2-5 mu m(3) cm(-3) in the lower layer and in the range 1-3.5 mu m(3) cm(-3) in the upper layer. Values of the effective radius values from BASIL and the in-situ sensors are in the range 0.2-0.6 mu m in both the lower and upper layer. Aerosol size distributions are determined at 2.2, 2.8, 4 and 4.3 km, with a good agreement between the Raman lidar and the microphysical sensors at all considered heights. We combined these size and microphysical results with Lagrangian back-trajectory analyses and chemical composition measurements. From this combination of datasets we conclude that aerosol particles below 3 km were probably originated by wildfires in North America and/or by anthropogenic activities in North-Eastern Europe, while aerosols above 3 km were also probably originated by wildfires in North America

Pot growing Media Amendment with Calcium Cyanamide and Weed Control Relationships

The aim of this research was to characterize the effect of a pre-transplant calcium cyanamide fertilization on weed control in the potted bedding ornamental plant Impatiens wallerana and to describe the physiological mechanisms involved. The positive effect of a calcium cyanamide amendment included both ammonium toxicity on weed seed germination and a decrease of weed rates growth such as relative leaf expansion rate (RLAE) and relative growth rate (RGR). Data showed RGR-NAR (net assimilation rate), RLAE-RGR, RLAE-NAR and RGR-root dry weight relationships, which would explain ammonium toxicity to roots and weed growth responses. These effects probably could be explained by a change in hormonal root synthesis. Our results showed that a pre-transplant calcium cyanamide amendment combining with a transplant routine optimize both I. wallerana growth and weed control.Fil: Leytur, M.. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Duarte Vera, Alejandra Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Sala, A.. Evonik Degussa Argentina S.A.; ArgentinaFil: Giardina, B.. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Evonik Degussa Argentina S.A.; ArgentinaFil: Di Benedetto, A.. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentin

Improving Interferometric Null Depth Measurements using Statistical Distributions: Theory and First Results with the Palomar Fiber Nuller

A new "self-calibrated" statistical analysis method has been developed for the reduction of nulling interferometry data. The idea is to use the statistical distributions of the fluctuating null depth and beam intensities to retrieve the astrophysical null depth (or equivalently the object's visibility) in the presence of fast atmospheric fluctuations. The approach yields an accuracy much better (about an order of magnitude) than is presently possible with standard data reduction methods, because the astrophysical null depth accuracy is no longer limited by the magnitude of the instrumental phase and intensity errors but by uncertainties on their probability distributions. This approach was tested on the sky with the two-aperture fiber nulling instrument mounted on the Palomar Hale telescope. Using our new data analysis approach alone-and no observations of calibrators-we find that error bars on the astrophysical null depth as low as a few 10-4 can be obtained in the near-infrared, which means that null depths lower than 10-3 can be reliably measured. This statistical analysis is not specific to our instrument and may be applicable to other interferometers

Synthetic Spectra and Color-Temperature Relations of M Giants

As part of a project to model the integrated spectra and colors of elliptical galaxies through evolutionary synthesis, we have refined our synthetic spectrum calculations of M giants. After critically assessing three effective temperature scales for M giants, we adopted the relation of Dyck et al. (1996) for our models. Using empirical spectra of field M giants as a guide, we then calculated MARCS stellar atmosphere models and SSG synthetic spectra of these cool stars, adjusting the band absorption oscillator strengths of the TiO bands to better reproduce the observational data. The resulting synthetic spectra are found to be in very good agreement with the K-band spectra of stars of the appropriate spectral type taken from Kleinmann & Hall (1986) as well. Spectral types estimated from the strengths of the TiO bands and the depth of the bandhead of CO near 2.3 microns quantitatively confirm that the synthetic spectra are good representations of those of field M giants. The broad-band colors of the models match the field relations of K and early-M giants very well; for late-M giants, differences between the field-star and synthetic colors are probably caused by the omission of spectral lines of VO and water in the spectrum synthesis calculations. Here, we present four grids of K-band bolometric corrections and colors -- Johnson U-V and B-V; Cousins V-R and V-I; Johnson-Glass V-K, J-K and H-K; and CIT/CTIO V-K, J-K, H-K and CO -- for models having 3000 K < Teff < 4000 K and -0.5 < log g < 1.5. These grids, which have [Fe/H] = +0.25, 0.0, -0.5 and -1.0, extend and supplement the color-temperature relations of hotter stars presented in a companion paper (astro-ph/9911367).Comment: To appear in the March 2000 issue of the Astronomical Journal. 60 pages including 15 embedded postscript figures (one page each) and 6 embedded postscript tables (10 pages total

How to write up case-study methodology sections

Business-to-business marketing academics study complex phenomena, aiming to describe these phenomena through theoretical frameworks, explaining the relationships among the framework's constructs, and provide guidance and insight to decision-makers. Not surprisingly, often business-to-business researchers undertake qualitative case studies. In this editorial, we discuss what we believe could be reported in the write-up of a case-study methodology section. In particular, we consider the issues of selecting cases; crafting instruments and protocols, entering the field; and analyzing the data. How to assess the validity and reliability of qualitative case studies is also discussed. We finish the editorial by examining three exemplar case studies that have been published in Industrial Marketing Management.http://www.elsevier.com/locate/indmarman2021-04-25hj2020Gordon Institute of Business Science (GIBS

The Clusters AgeS Experiment (CASE). II. The Eclipsing Blue Straggler OGLEGC-228 in the Globular Cluster 47 Tuc

We use photometric and spectroscopic observations of the eclipsing binary OGLEGC-228 (V228) to derive the masses, radii, and luminosities of the component stars. Based on measured systemic velocity, proper motion and distance, the system is a blue straggler member of the globular cluster 47 Tuc. Our analysis shows that V228 is a semi-detached Algol. We obtain M=1.512 +/- 0.022 Msun, R=1.357 +/- 0.019 Rsun, L=7.02 +/- 0.050 Lsun for the hotter and more luminous primary component and M=0.200 +/- 0.007 Msun, R=1.238 +/- 0.013 Rsun, L=1.57 +/- 0.09 Lsun for the Roche lobe filling secondary.Comment: 19 pages, 5 figures, AJ, in pres

Establishing Visible Interferometer System Responses: Resolved and Unresolved Calibrators

The propagation of errors through the uniform disk visibility function is examined. Implications of those errors upon measures of absolute visibility through optical and near-infrared interferometers are considered within the context of using calibration stars to establish system visibilities for these instruments. We suggest a simple ratio test to establish empirically whether or not the measured visibilities produced by such an instrument are relative (errors dominated by calibrator angular size prediction error) or absolute (errors dominated by measurement error).Comment: 20 pages, 7 figures, to be published in the PAS