Line Profiles In Spectra Research Articles

Evidence for late-time dust formation in the ejecta of supernova SN 1995N from emission-line asymmetries

ABSTRACT We present a study of the dust associated with the core-collapse supernova SN 1995N. Infrared emission detected 14–15 yr after the explosion was previously attributed to thermally echoing circumstellar material (CSM) associated with the supernova (SN) progenitor. We argue that this late-time emission is unlikely to be an echo, and is more plausibly explained by newly formed dust in the SN ejecta, indirectly heated by the interaction between the ejecta and the CSM. Further evidence in support of this scenario comes from emission-line profiles in spectra obtained 22 yr after the explosion; these are asymmetric, showing greater attenuation on the red wing, consistent with absorption by dust within the expanding ejecta. The spectral energy distribution and emission-line profiles at epochs later than ∼5000 d are both consistent with the presence of about 0.4 M⊙ of amorphous carbon dust. The onset of dust formation is apparent in archival optical spectra, taken between 700 and 1700 d after the assumed explosion date. As this is considerably later than most other instances where the onset of dust formation has been detected, we argue that the explosion date must be later than previously assumed.

Ultrafast Variability of Line Profiles in Spectra of γ Ori

Ultrafast Variability of Line Profiles in Spectra of γ Ori

Measurement System for Study of Absorption Spectra of Gaseous Media at High Pressures

A system for measuring the absorption spectra of gaseous media at pressures of 0.01–150 atm in the 0.3–25 μm range is considered. Its suitability for studying pressure-induced absorption owing to intermolecular collisions and for measuring spectral absorption coefficients, integrated band intensities, and spectrum line profiles is discussed.

Searching double-peaked emission-line profiles in the spectra of galaxies through the symmetry of the cross-correlation function

The presence of double-peaked/multicomponent emission line profiles in spectra of galaxies is commonly done by visual inspection. However, the identification of complex emission line profiles by eye is unapproachable for large databases such as the Sloan Digital Sky Survey (SDSS) or the integral field spectroscopy surveys of galaxies (e.g. CALIFA or MaNGA). We describe a quick method involving the cross-correlation technique for detecting the presence of complex (double-peaked or multiple components) profiles in the spectra of galaxies, deriving simultaneously a first estimation of the velocity dispersions and radial velocities of the dominant gaseous component. We illustrate the proposed procedure with the well-known complex [OIII]4959,5007 profiles of the central region of NGC1068.

Efficient dealing with spectrum line profiles using complex rational functions

We comment on the use of complex rational functions in dealing with spectrum line profiles. This involves efficient ways of computation of the profiles, as well as applications in describing the real and imaginary counterparts of response functions, obeying Kramers–Kronig relations.

A detailed comparison of spectral line intensities with plane and hollow cathodes in a Grimm type glow discharge source

The hollow cathode discharge was investigated and compared with the plane cathode discharge in a Grimm-type source studying a large number of lines with iron and titanium as cathode materials in argon plasma. The high resolution Fourier Transform Spectrometer (FTS) at Imperial College (IC) was used for recording spectra. The intensity changes for atomic and ionic lines of iron, titanium and argon are discussed, whereby clear trends in intensity increase and reduction according to the excitation energies of the emission lines are identified. Differences in line profiles in spectra using the hollow and plane cathodes were detected. The comparison between the hollow (10–15 mm deep) and shallow (2 mm deep) cathodes gives additional information about the depth influence on the hollow cathode effect. The extended study presented in this paper is a further step towards a better understanding of the discharge processes in the glow discharge.

Line profile variability of OB stars: Pulsation, rotation, clumps and magnetic fields

AbstractThe variability of line profiles in spectra of bright OB stars has been studied.We obtain more than 1000 high quality spectra of δ Ori A, λ Ori A, α Cam, 19 Cep, ι Her, ρ Leo and other target stars. We revealed the line profile microvariability of small amplitude (0.5–3% in the adjacent continuum units) for all observed stars. For most stars only cyclic components of the line profile variability (LPV) at the time scales from hours to days were detected. These components seem to be connected with both the non‐radial pulsations (NRP) and rotation line profile modulation. In the spectra of δ Ori A and λ Ori A we found the evidences of the stochastic LPV in spectra, probably connected with the small clumps in the stellar wind. On the basis of recent observations we discuss the origin of the magnetic field of early‐type stars. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The Scanner for Precise Spectrophotometry of the Sun as a Star

The primary shortcomings of existing methods for spectrophotometry of the Sun as a star are discussed. A new observational method is proposed. This method is based on a repeated scanning of the Sun's image while summing the signal of each step across the solar disk. A device for precise spectrophotometry of the Sun as a star has been developed around a double-pass spectrograph. This device and its operation algorithm are described. Errors caused by scanning irregularities and seeing are estimated. Several Sun-as-a-star spectrum line profiles and their bisectors are presented and compared with the same ones from the Kitt Peak FTS solar flux atlas.

Decomposition of electron energy loss spectrum-line profiles by target factor analysis

Interfaces play a ubiquitous role in governing the behavior of materials, but the fundamental means by which they exert their influence are surprisingly little understood. EELS offers a path towards elucidating the nature of both the coordination and local chemistry at interfaces; however, successful application requires the development of quantitative techniques for the deconvolution of various contributions to the spectra. The present work describes a first application of Factor Analysis (FA) to this problem. FA is a multiparameter statistical method used to extract subtle information from complicated data sets, the mathematical basis of which has been well documented in the literature. In brief, FA seeks to reproduce a given data set within experimental error using the minimum number of statistically non-zero “factors” or “components”. In this study, FA has been successfully applied to the decomposition of an Al L2,3 spectrum-line profile across a magnesium aluminate spinel/sapphire interface. One of us (JB) recently examined this heterophase structure in detail using multiple least squares decomposition of the two endpoint components (spinel and sapphire).

On the recursive properties of Dawson's integral

The generalized Dawson integral F(p,x) is considered. Closed formulae are given for the nth derivatives with respect to the arguments x and p in terms of the function itself. A recursion relation is developed which may be regarded as the (n+1)st-order differential equation satisfied by F(p,x). It is shown that known results concerning Dawson's function are merely specific cases of the generalized Dawson equation. The application of the successive derivatives of F(2,x) in the context of the Voigt spectrum line profiles is demonstrated.

Diurnal variation of the linear polarization across the H? and H? Fraunhofer lines of the terrestrial atmosphere, and a detection of a ?daylight flash?, II

In Paper I, the ability of using the polarimetric technique to observe the filling-in of the Fraunhofer spectrum line profiles—the Ring effect—has been presented (using the Hβ Fraunhofer line only). It has also been found that the added light, which caused the filling-in, is polarized. Here, a description is given of some observations, which, hopefully, will lead to a better understanding of the Ring effect using the Hα and Hβ Fraunhofer spectral lines. The observations of the filling-in effect at the zenith have covered many conditions which might be considered as controlling its behaviour at these two spectral regions. The data reveal variations of polarization at the centres of those Fraunhofer lines as a function of solar zenith angle. The results show no uniformity for the added light intensity, its value was depending on the kind of day (clear and turbid) and/or on the solar zenith angle. Also the photometric observational studies reported here suggest that a new phenomenon behaving like airglow has been discovered. It is referred to here as a ‘daylight flash’ and was recorded (for short periods) on three days at both the Hα and Hβ Fraunhofer lines with different strengths. The cores of these lines were filled in while the near continua were unaffected.

Quasi-Periodic Variations of Balmer Line Profiles in Spectra of the T Tau-Type Star RW Aurigae

RW Aur is one of the most active T Tau-type stars with essentially variable emission line spectrum. In order to study the nature of this variability,patrol spectroscopic observations of the star were carried outfrom November 1979 to March 1982 at the 2.6-meter telescope of the Crimean Astrophysical Observatory. The spectral region λλ38OO-67OO A has been observed with a dispersion of about 40 A/mm. All nights were supplied with simultaneous spectrophotometry of the star.

Optimized computation of the voigt and complex probability functions

Methods for computing the complex probability function w( z) = e − z 2 erfc (− iz), which is related to the Voigt spectrum line profiles, are developed. The basic method is a rational approximation, minimizing the relative error of the imaginary part on the real axis. It is complemented by other methods in order to increase efficiency and to overcome the inevitable failure of any rational approximation near the real axis. The procedures enable one to evaluate both real and imaginary parts of w(z) with high relative accuracy. The methods are simple, as demonstrated by a sample FORTRAN program.

Spectrum line profiles: A generalized Voigt function including collisional narrowing

Reduction of collision-narrowed line profile functions to dimensionless form analogous to the standard form of the Voigt profile simplifies mathematical treatment. New quadratures are given which allow the efficient calculation of collision-narrowed profiles over the full physically realizable range of both collisional broadening and narrowing.

Spectroscopic Line-Profile Studies of Long Magnetically Confined High-Current, Steady-State Vacuum Arcs

Spectroscopic studies of the line profiles of radiating ions in a magnetically confined, high-current, steady-state vacuum carbon arc have revealed ion temperatures up to 5,000,000°K in a 4.9-m long arc. The ion temperature is a quadratic function of the distance from the anode in a given arc, but for arcs of different lengths the highest arc temperature is roughly proportional to the arc length. The spectrum line profiles are essentially Gaussian (Doppler shape) for observations transverse to the arc column but in very long arcs are non-Gaussian, and sharper, for axial views. Helium, nitrogen, or argon fed to the arc through the cathode result in pronounced heating of the trapped ions, their transverse temperature being dependent on the charge state of the ion, thus suggesting strong radial electric field heating of the ions.

Theoretical Aspects of the W Virginis Phenomena.

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Theoretical Aspects of the W Virginis Phenomena. Whitney, Charles A. Abstract The physical basis of an earlier shock-wave model for the atmospheric motions of NV Virginis is discussed. Implications of this model for spectrum line profiles and curve-of-growth turbulence are shown to be either (a) consistent with observations or (b) undetectable from present data. The expected duration of the doubling of absorption lines is computed and found to agree with observed values. Results of recent calculations on the structure of the shock front are presented and are used for a preliminary interpretation of the observed hydrogen-emission lines. Publication: The Astronomical Journal Pub Date: March 1962 DOI: 10.1086/108831 Bibcode: 1962AJ.....67Q.286W full text sources ADS |

Wechselwirkungen im Plasma kondensierter Niederspannungsentladungen

The line profiles of spectra of condensed low-voltage discharges of Pfeilsticker-type are affected by interaction independent of electrode composition. From line profiles it is possible to derive the kind of interaction, which enables one to say something about the physical processes in the discharge. Observed line profiles in discharges of high current density lead to selection rules for analytical and reference lines for use in quantitative spectrochemical analysis. By means of these rules it seems to be possible to select lines which are of satisfactory slope, free of self-absorption or reversal and suitable for test on concentration sensitivity. These selection rules are based on the term designation of the line. The integrating characteristic of the photographic plate or photoelectric receiver used has to be mentioned. Comparison of spectral and dynamic characteristics shows that characteristics give a complete control of the discharge, including the importance of a well-defined ignition for high-accuracy analysis.