Spectrographic observations of peculiar stars.

in Astrophysical Journal (1940), 91

1. The spectra of several absorption O-type stars showing vestiges of Wolf-Rayet emission have been investigated from λ 3300 to λ 6700. The absorption spectrum consists mainly of H, He II, He I,O III,O IV ... [more ▼]

1. The spectra of several absorption O-type stars showing vestiges of Wolf-Rayet emission have been investigated from λ 3300 to λ 6700. The absorption spectrum consists mainly of H, He II, He I,O III,O IV, N III, N IV, and Si IV. The emission lines show a P Cygni character and are confined to H, He I, and a few transitions of He II, N III, N IV, N V, C III, and Si IV. The location of the expanding shell giving rise to the emission and absorption lines is estimated. 2. The visual spectrum of P Cygni reveals strong Fe III lines originating from metastable levels (dilution effect). Lines of other elements show a peculiar selectivity of the emission lines. The spectra of three other P Cygni type stars (Z Canis Majoris, BD+47°3487, and BD+11°4073) are described, especially in connection with the phenomena arising in expanding shells. RY Scuti shows a strong system of forbidden [Fe III] lines, and the variations in the spectrum of this star are discussed. 3. The ultraviolet region of the spectrum of ξ Tauri shows several sets of absorption lines (H, He, and ionized metals) arising from the reversing layer and from various layers in the surrounding shell. The a5D - 4p5P0 multiplet of Fe III was the most conspicuous feature in the visual region of γ Cassiopeiae in March, 1940. New data are given for the spectra of several other stars with extended shells (MtW 143, HD 218393, HD 160529, and HD 190073). A group of stars showing forbidden [Fe II] lines is discussed (WY Geminorum, W Cephei, B 1985, B 5481, and HD 45677) ; and new [Fe II] multiplets are found in the ultraviolet region of these objects. 4. The spectra of four binary systems showing simultaneously an M-type spectrum and forbidden lines of high excitation are described in detail. The spectroscopic phenomena accompanying the recent outburst of Z Andromedae are discussed; the continuous absorption in the shell plays an important role in the relative intensities of the emission and absorption components of the P Cygni type lines. The two stars AX Persei and CI Cygni have very similar bright-line spectra, of which the nebular part shows a very high excitation; besides H, He I, and He II, the strongest lines are due to [Fe VII] and [Ne V], and there is good evidence in favor of [Fe X]. The temperature of the nucleus exciting these nebular lines must be of the order of 150,000°, or more. Another multiple object of lower excitation is R Aquarii, and new spectroscopic data show the occultation effect of the nebula by the TiO atmosphere of the late-type component. There is good reason to beUeve that the binary nature of a star stimulates the process of shell formation. [less ▲]

Spectrographic observations of peculiar stars. III.

in Astrophysical Journal (1942), 95

This paper describes recent changes in the spectra of AX Per, Z And, AG Peg, and R Aqr. There is also a description of recent spectrograms of the unusually red bright-line star MWC 349.

Spectrographic Observations of Peculiar Stars.IV.

in Astrophysical Journal (1942), 96

I. New observational results.-AX Persei in January and February, 1942, showed the lines of [Fe V] and [Fe VI] with considerable intensity. Other interesting changes in the spectrum have been recorded. RW ... [more ▼]

I. New observational results.-AX Persei in January and February, 1942, showed the lines of [Fe V] and [Fe VI] with considerable intensity. Other interesting changes in the spectrum have been recorded. RW Hydrae is interesting because of the absence of fluorescence excitation in O III and because the He I singlets (2p1P0 - nd1D) are relatively strong. Z Andromedae has returned to a stage similar to that observed in August, 1940. T Coronae Borealis has bright Fe II, but the absence of [Ne V] shows that the excitation is lower than in Z Andromedae. Z Canis Majoris has been observed near maximum light. Several Of and W stars have also been observed. II. Excitation mechanisms in shells.-The importance of fluorescence excitation is discussed and is applied to the problem of selectivities among emission lines of peculiar stars. Of particular interest are the ratios of singlet to triplet intensities of He I. The great relative strength of the singlets in objects of low excitation, like RW Hydrae, is attributed (a) to the predominance of fluorescence over recombination and (b) to the presence of high radiation density in the nebulous shells of the singlet series (1s1S - np1P0) of He I. Similar considerations are applied to unusual intensities of emission lines in Of shells and in P Cygni or Be shells. The influence of departures of the exciting radiation from that of a black body is discussed for novae and for certain long-period variables. When fluorescence is produced by strong ultraviolet emission lines, as in the case of Bowen's mechanism for O III, the gradient in the velocity of expansion of a shell produces important modifications. This may account for absence of the Bowen mechanism in Wolf-Rayet stars and in other rapidly expanding shells. [less ▲]

Spectrographie Bidimensionnelle de 2 Mirages Gravitationnels avec SILFID

in Bulletin d'Information du Télescope Canada-France-Hawaii (1990), 22

Not Available

Spectrométrie dans l’infrarouge proche. Application à l’analyse rapide des protéines et des acides aminés de Vicia faba L.

Master's dissertation (1981)

Le travail comprend tout d'abord la mise au point d'une technique de dosage rapide et précise de la matière protéique totale des graines de féverole (Vicia faba L.) par spectroscopie dans l'infrarouge à ... [more ▼]

Le travail comprend tout d'abord la mise au point d'une technique de dosage rapide et précise de la matière protéique totale des graines de féverole (Vicia faba L.) par spectroscopie dans l'infrarouge à partir de résultats obtenus par kjeldahl sur 108 cultivars. La seconde partie est consacrée à l'analyse de 10 acides aminés essentiels de 68 variétés de féveroles par colonne de résine échangeuse de cations et réalisation de équations de calibration par NIR. [less ▲]

Spectrométrie de masse MALDI-TOF en bactériologie clinique ou comment identifier une bactérie en une minute

in Revue Médicale de Liège (2010), 65(Suppl. Synthèse 2010), 29-34

The major application of MALDI-TOTOF mass spectrometry in clinical microbiology is the bacterial identification based on the analysis of all their proteins (ribosomal and membrane-associated proteins ... [more ▼]

The major application of MALDI-TOTOF mass spectrometry in clinical microbiology is the bacterial identification based on the analysis of all their proteins (ribosomal and membrane-associated proteins). This technology allows the identification of most of bacteria within a few minutes. The method is fast, accurate, reliable and cost-effective by comparison to conventional phenotypic techniques. Other applications of MALDI-TOF mass spectrometry are still under development, as the detection of bacterial toxins or resistance mechanisms to antimicrobial agents. [less ▲]

Spectrophotometric Monitoring of Comet C/1995 O1 (Hale-Bopp): Pre- and Post-Perihelion

in Bulletin of the American Astronomical Society (1998, September 01)

Spectrophotometric observations of comet C/1995 O1 (Hale-Bopp) were performed at the European Southern Observatory (ESO), Chile. From April to September 1996 its gaseous activity was monitored over a ... [more ▼]

Spectrophotometric observations of comet C/1995 O1 (Hale-Bopp) were performed at the European Southern Observatory (ESO), Chile. From April to September 1996 its gaseous activity was monitored over a heliocentric distance range from 4.6 AU to 2.9 AU. The monitoring is continued on Hale-Bopp's outbound path since September 1997 and covers up to now 3 AU to 5 AU heliocentric distance. Medium resolution spectra in the optical wavelength range from about 350 nm to 700 nm were taken at the 1.54m Danish and the 1.52m ESO telescope. Emission bands of the CN, C_3, C_2 and NH_2 radicals can be followed over the comet's orbit. We will present a first analysis of the post-perihelion activity evolution and compare to the pre-perihelion path. Currently, at 4.7 AU on the outbound path, we still see emission of CN, C_3, C_2 and NH_2. The production rate of CN showed a sudden increase around this heliocentric distance pre-perihelion (Rauer et al., Science 275, 1909). The post-perihelion activity evolution of CN and the other observed radicals in this distance range will be evaluated. [less ▲]

Spectrophotométrie dans le proche infrarouge : Une méthode d'analyse adaptée au secteur agro-alimentaire.

in Agoratech (1997), (8),

Spectropolarimetry of WR66

in Wolf-Rayet stars in the framework of stellar evolution ; 33rd Liege International Astrophysical Coll (1996)

We have carried out spectropolarimetric observations of the Wolf-Rayet star WR66 (WN8) with EFOSC1 mounted on the ESO 3.6m telescope of La Silla. The results indicate a polarization level of about 5 to 6 ... [more ▼]

We have carried out spectropolarimetric observations of the Wolf-Rayet star WR66 (WN8) with EFOSC1 mounted on the ESO 3.6m telescope of La Silla. The results indicate a polarization level of about 5 to 6 % in the continuum which is most probably due to interstellar polarization. [less ▲]

Spectroscopic analysis of extreme metal-poor 'dwarfs'. II - Improved model atmospheres and detailed abundances

in Astronomy and Astrophysics (1985), 146

High resolution spectrophotometric data were obtained for the stellar objects HD 19445 and HD 140283. The spectra gathered were well-matched by model stellar atmospheres for the continuous flux and Fe I ... [more ▼]

High resolution spectrophotometric data were obtained for the stellar objects HD 19445 and HD 140283. The spectra gathered were well-matched by model stellar atmospheres for the continuous flux and Fe I excitation equilibrium. HD 19445 was identified as a dwarf star and HD 140283 as a subgiant. Abundance analyses indicated an Fe abundance lower than previously estimated, oxygen overabundant relative to C and Fe, Mg, Si and Ca overabundant relative to Fe, and deficiencies of Al and Mn. Sr was overabundant relative to Ba. The abundance discrepancies are in disagreement with the standard nucleosynthesis model. Further such spectroscopic data are needed to develop accurate galactic chemical evolution models. [less ▲]