Far and extreme-ultraviolet spectrophotometry of hot white dwarfs - Prospects for the determination of the He/H ratio in DA stars

1984 ◽  
Vol 96 ◽  
pp. 981 ◽  
Author(s):  
F. Wesemael ◽  
J. Liebert ◽  
R. F. Green
Keyword(s):  
White Dwarfs ◽  
Extreme Ultraviolet ◽  
Ultraviolet Spectrophotometry

Spectroscopic Determination of Mass for a Sample of DAO White Dwarfs

White Dwarfs ◽  
2003 ◽  
pp. 143-146
Author(s):  
S. A. Good ◽  
M. A. Barstow ◽  
M. R. Burleigh ◽  
J. B. Holberg ◽  
D. Sing ◽  
...  
Keyword(s):  
White Dwarfs ◽  
Spectroscopic Determination

Quantitative Determination of Benzaldehyde in Flavors and Cordials by Ultraviolet Spectrophotometry and 2,4-Dinitrophenylhydrazine Precipitation

1967 ◽  
Vol 50 (2) ◽  
pp. 319-322
Author(s):  
Richard L Brunelle
Keyword(s):  
Quantitative Determination ◽  
Spectrophotometric Method ◽  
Alternative Methods ◽  
Ultraviolet Spectrophotometry ◽  
Precipitation Procedure ◽  
Gravimetric Procedure

Abstract Three sets of samples were collaboratively analyzed by the official, first action ultraviolet spectrophotometric and 2,4-dinitrophenylhydrazine precipitation methods for determining benzaldehyde in flavors and cordials. The spectrophotometric method was unchanged, except for clarification, and collaborators reported recoveries averaging nearly 100%. The gravimetric procedure using 2,4-dinitrophenylhydrazine gave unsatisfactory recoveries on the first two sets of collaborative samples. However, collaborators reported approximately 96% recovery of benzaldehyde with a modified precipitation procedure on a third set of samples. The ultraviolet spectrophotometric method and the modified 2,4-dinitrophenylhydrazine precipitation procedure are recommended for adoption as official, final action as alternative methods.

scholarly journals A Spectroscopic Survey in the EUV of the “Coolest” Hot DA Stars

1996 ◽  
Vol 152 ◽  
pp. 217-222
Author(s):  
Jean Dupuis ◽  
Stéphane Vennes
Keyword(s):  
Effective Temperature ◽  
White Dwarfs ◽  
Heavy Element ◽  
Extreme Ultraviolet ◽  
Diffusion Theory ◽  
Hydrogen Atmosphere ◽  
Element Abundance ◽  
Pure Hydrogen ◽  
Element Abundances ◽  
The One

We present an analysis of the extreme ultraviolet (EUV) spectroscopy of a sample of 10 DA white dwarfs observed by the Extreme Ultraviolet Explorer (EUVE). We have selected white dwarfs cooler than about 50,000 K and with presumably low heavy element abundances. The goal of this study is to determine the fundamental atmospheric parameters, namely the effective temperature and chemical composition, of these stars by fitting their continua with synthetic spectra computed from pure hydrogen LTE/line-blanketed model atmospheres. The question of the presence (or absence) of trace elements is explored by comparing EUV-determined effective temperatures to the one obtained from a fit of hydrogen balmer lines. It is found that the majority of the DA in the sample are consistent with having a pure hydrogen atmosphere. One of the star, MCT0027-634, is another possible example of a HZ 43-type white dwarf, having an effective temperature above 50000 K and a low heavy element abundance, i.e., much lower than predicted by diffusion theory.

scholarly journals Expected Scientific Performance of the Three Spectrometers on the Extreme Ultraviolet Explorer

1990 ◽  
Vol 115 ◽  
pp. 335-338
Author(s):  
J. V. Vallerga ◽  
P. Jelinsky ◽  
P. W. Vedder ◽  
R. F. Malina
Keyword(s):  
Wavelength Range ◽  
Spectral Resolution ◽  
Line Source ◽  
White Dwarfs ◽  
Extreme Ultraviolet ◽  
Cataclysmic Variables ◽  
Effective Area ◽  
Light Sources ◽  
Scientific Performance ◽  
Astronomical Satellite

AbstractThe expected in-orbit performance of the three spectrometers included on the Extreme Ultraviolet Explorer (EUVE) astronomical satellite is presented. Recent calibrations of the gratings, mirrors and detectors using monochromatic and continuum EUV light sources allow the calculation of the spectral resolution and throughput of the instrument. An effective area range of 0.2 to 2.8 cm2 is achieved over the wavelength range 70-600Å with a peak spectral resolution λ/Δλ (FWHM) of ~ 360 assuming a spacecraft pointing knowledge of 10 arc seconds (FWHM). For a 40,000 sec observation, the average 3σ sensitivity to a monochromatic line source is 3 × 103 photons cm-2 sec-1. Simulated observations of known classes of EUV sources such as hot white dwarfs and cataclysmic variables are also presented.

UV Determination of Sulfoxide in Formulations

1965 ◽  
Vol 48 (3) ◽  
pp. 569-573
Author(s):  
J B Haus ◽  
L Manolev ◽  
R W Price
Keyword(s):  
Silicic Acid ◽  
Column Chromatography ◽  
The Other ◽  
Ultraviolet Spectrophotometry

Abstract A method for the assay of sulfoxide in insectieidal formulations involves separation of the sulfoxide from the other components by column chromatography on silicic acid with three successive eluting solutions: chloroform; 2% acetone in chloroform; and 10% acetone in chloroform. Sulfoxide is removed in the last eluate and is determined by ultraviolet spectrophotometry. Solvents, emulsifiers, pyrethrins, compounds related to sulfoxide, and other insecticides tested are separated by the column.

Determination of Nicotine in Feeds

1964 ◽  
Vol 47 (2) ◽  
pp. 226-228
Author(s):  
David E Root
Keyword(s):  
Aqueous Phase ◽  
Steam Distillation ◽  
Animal Feed ◽  
Collaborative Study ◽  
Basic Solution ◽  
Ultraviolet Spectrophotometry

Abstract Nicotine, used in medicated animal feed in combination with phenothiazine, dibutyl tin dilaurate, and 2,2'-dihydroxy-5,5’-dichlorophenyl methane, has been successfully isolated from these compounds and the feed interferences and cleaned up by extraction with 0.5% NaOH, steam distillation f r om this basic solution, and extraction from the aqueous phase with chloroform. The nicotine is then partitioned into 0.05iV HC1, and determined by ultraviolet spectrophotometry. A collaborative study yielded 9 0% over-all recoveries, and the method is recommended for adoption as official, first action.

Sign in / Sign up

Export Citation Format

Share Document