Optical Line Spectrum Research Articles

Hubble Space Telescope and ground-based optical imaging of the Proto-Planetary Nebula M1-92

We present HST and ground-based images of the bipolar proto-planetary nebula M1-92. Trammell et al. (1993) studied Ml-92 using spectropolarimetry and concluded that the continuum emission is reflected from the inner regions of the object, the forbidden lines are formed locally in the bipolar lobes, and the permitted lines are partially reflected and partially formed in the bipolar lobes. The emission produced in the lobes of Ml-92 is indicative of shock heating, Vs = 60–100 km s–1. Shock emission dominates the optical line spectra of the lobes of M1-92 and is a powerful probe into the properties of the mass loss occurring between the AGB and PN phases of evolution.

A Catalog of Ultraviolet, Optical, and Near-Infrared Emission Lines Identified in Supernova Remnants

view Abstract Citations (43) References (201) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Catalog of Ultraviolet, Optical, and Near-Infrared Emission Lines Identified in Supernova Remnants Fesen, Robert A. ; Hurford, Alan P. Abstract Optical spectra of two filaments in the Cygnus Loop are used to investigate the faint optical line spectra of supernova remnants (SNRs). Data on a bright, previously studied filament in the remnant's northeast rim (NGC 6992) provide accurate relative line strengths for many faint emission lines present in shocked, low-density interstellar gas. Spectra of a particularly strong [O III] λλ4959, 5007 filament {I([O m])/I(Hβ≃45} reveal both a high [O III] electron temperature (60000 ± 3000 K) and many high-ionization lines, including [Ar IV], [Ar V], [Ne IV], [Ca V, [Cl III], [Fe VI], [Fe VII], and [Fe X]. Taken together, these data reveal 16 new emission lines not previously seen in any SNR, plus an additional 11 emission lines seen only once before in various remnants. These new spectral results are incorporated into a comprehensive catalog of over 250 emission lines identified in Galactic and Magellanic Cloud SNRs within the wavelength range 900-12000 Å, and are complete through 1995. Along with accurate laboratory wavelengths and commonly observed relative line intensity information, this tabulation lists individual remnants and references for less commonly observed lines. UV, optical and lines identified in SNRs organized by ionization stage, and a reference list of observational papers sorted by remnant and wavelength regime are also given. Publication: The Astrophysical Journal Supplement Series Pub Date: October 1996 DOI: 10.1086/192348 Bibcode: 1996ApJS..106..563F Keywords: CATALOGS; INFRARED: ISM: LINES AND BANDS; LINE: IDENTIFICATION; ISM: SUPERNOVA REMNANTS full text sources ADS | data products SIMBAD (21)

Spectropolarimetry of the post-main-sequence bipolar nebulae GL 618, M2-56, and M1-92

New high-quality spectropolarimetry of the post-main-sequence bipolar nebulae GL 618, M2-56, and M1-92 is presented which permits accurate separation of the scattered and unscattered components. Shock emission dominates the optical line spectrum of the three nebulae and probably plays a significant role in their dynamical evolution. The central H II region spectrum for GL 6189 is isolated and T(stellar) of 36,000-40,000 and log (N/O) = 0.0 +/- 0.2 are derived. GL 618 and M2-56 have shock velocities of 40-60 km/s; that of M1-92 is 60-100 km/s. Log (N/O) is derived for different regions of the three nebulae. There is an apparent correlation of outflow velocity with chemical abundance.

Optical line spectra in metallic (Nd,Ce)2CuO4-x.

Optical absorption lines characteristic of ${\mathrm{Nd}}^{3+}$ have been observed in semiconducting and metallic phases of (Nd,Ce${)}_{2}$${\mathrm{CuO}}_{4\mathrm{\ensuremath{-}}\mathit{x}}$ using a sensitive optical spectroscopic technique. Samples with controlled levels of impurities and controlled cerium content have been studied to verify that the lines observed are intrinsic to (Nd,Ce${)}_{2}$${\mathrm{CuO}}_{4\mathrm{\ensuremath{-}}\mathit{x}}$. Sharp absorption lines in the visible spectrum of these metallic materials are observed. The materials exhibit dichroism characteristic of a two-dimensional conductor. Both this dichroism and the oscillator strengths of certain transitions show variations that are correlated with the doping level, conductivity, and degree of orientation of the samples. It is believed that these variations are the result of changes, induced by the doping, in the charge distribution near the Nd ions and the indices of refraction of the material.

Low-Activity Nuclei in Spiral Galaxies

Two types of active nuclei have been observed in normal spiral galaxies in X-rays with the Einstein Observatory: low-activity AGN, and starburst regions. The prototype of the first kind is the nucleus of M81 (Elvis and Van Speybroeck 1982; Fabbiano 1988a), but similar nuclei might also be those of M33 and NGC 1313. Soft X-ray spectra of these nuclei suggest relatively steep soft X-ray components (Trinchieri, Fabbiano and Peres 1988; Fabbiano and Trinchieri 1987; Fabbiano 1988a), reminiscent of those observed in QSOs by Bechtold et al (1987) and Wilkes and Elvis (1987). In M81, in particular, this soft component might supply enough photons to explain the optical line spectrum. If this soft X-ray component originates from an accretion disk surrounding a central black hole, the mass of the latter is likely to be smaller than 104–5 solar masses.

Ultraviolet Variability of the Symbiotic Star AG PEG

Symbiotic star AG Peg consists of a hot subdwarf with a WN6 spectrum and a cool M3 giant, which is not filling its Roche lobe (Boyarchuk 1967, 1985). A detailed study of profiles, equivalent widths and radial velocities of emission lines in optical spectra allowed Hutchings et al. (1975) to conclude that a hot subluminous star approximately 1 M⊙ rotates rapidly and ejects material which streams towards the cool M giant with the mass 3-4 M⊙. UV observations seems to support this model.UV observations provided from the databank of the IUE satellite were obtained in 1978–81 by different observers. The observational material consists of 12 high dispersion SWP spectra and covers the region 1200 – 2100 A. The spectra were reduced at Trieste observatory using standard IUESIPS package. The radial velocities of emission lines were measured on tracings and corrected for the motion of Earth and satellite.

The influence of the Jahn-Teller effect upon zero-phonon lines in optical spectra

A mechanism involving the Jahn-Teller effect is used to account for both strong and absent zero-phonon lines in optical spectra. The method is applied to explain why the 1.03 eV zero-phonon line of the GaP:Cr3+ system is very strong, whilst no zero-phonon line is observed from the GaAs:Cr3+ system.

250 keV and 100 keV argon ion induced X-ray and optical emissions from a Cr/Ni sandwich on Si and Al samples

During 250 keV Ar + ion bombardment of an Cr/Ni sandwich on Si samples [1] X-ray and optical emissions have been recorded. The optical spectrum showed pronounced Cr I lines from the first Cr layer of the bombarded sample. The X-ray spectra showed Ar K. lines. The Al foils bombarded by 100 keV Ar + ions showed the optical line spectra with pronounced Al I optical lines as well as Al II and Al III optical lines, while the X-ray spectra obtained by 250 keV Ar + ion bombardment showed pronounced K X-ray Al lines and less pronounced K X-ray argon lines. The correlation diagram for the Ar +→ Cr collisions shows that the Ar 1s electron can be promoted to the 2p levels of the united atom with a probability of vacancy creation in the Ar K shell. The Al K α lines appeared as a consequence of the Al Is electron promotion to the 2p level of the united atom. The promoted Al Is electron left a vacancy in the Al K shell. Deexcitation in both the Ar and Al excited atom occurs when the K vacancy is filled by an electron from the upper shells.

Emission-line gas associated with the radio lobes of the high-luminosity radio source 3C 171

Sets of spectroscopic and imaging CCD emission line data were obtained of the gas in the radio lobe regions of the celestial object SC 171. The optical scans were made at Kitt Peak in 1982-83 and radio data were gathered with the VLA at 2, 6 and 20 cm wavelengths in 1983. The brightest gas emission lines resided alongside knots of the bright radio regions, which were composed of plasma. The gas spectra were akin to those emitted by active nuclei. The gas may be cooling and entrained in boundary layers around the radio sources, which are highly distorted and Faraday depolarized where optical line spectra and radio emissions overlap. Finally, the gas velocities showed a velocity range of up to 1000 km/sec, a dispersion supportive of a model of entrained turbulent flow.

Electric quadrupole refocusing of CaBr: Differential transmission of hyperfine levels and assignment of low-J lines in optical spectra

Abstract The refocusing of a molecular beam of CaBr X 2 Σ + by an electric quadrupole is investigated. The enhancement by electric deflection of the intensities of lines originating from levels of low J in the fluorescence excitation spectrum of CaBr B 2 Σ + −X 2 Σ + is shown to be a useful technique of line assignment in a dense electronic band system. It is also found that the hyperfine levels are not transmitted equally through the quadrupole; for f levels, the hyperfine populations are actually reversed. A qualitative explanation, based on the correlation of zero-field hyperfine levels with high-field states, is given.

Determination of Autoionization Rates by Means of Optical Emission Spectroscopy

Extraction of accurate values of autoionization rates from broadened emission lines in optical spectra is discussed. Results for autoionizing states in He I and Li I are given and compared with theory. Spin-induced autoionization is proposed to cause the discrepancy between theoretical and experimental lifetimes for some Li I quartet levels.

Origin of new lines in optical spectra in CDW state

Under the formation of the commensurate charge density wave (CCDW) in the layered compound materials, the new lines become observable both in the infrared absorption and the Raman scattering spectra. We present theoretically the microscopic mechanisms of these new lines. The following mechanisms are considered. (1) The originally infrared or Raman active mode is hybridized with the modes folded onto the Γ-point through the electron-phonon couplings. As a result, some of these modes are given the infrared or Raman activities. (2) Contributions from the collective modes of CDW. We develop these ideas and apply them to the case of 1T-TiSe 2, which shows rather simple CCDW. It is found that in the case of 1T-TiSe 2, the new lines are explained by these mechanisms.

Cosmological limits on photon splitting

General conservation laws and symmetries permit one photon to split into three all traveling in the original direction. But QED predicts that this process has vanishing probability. Observations of the 3-K microwave background and optical line spectra of quasars can be used to test this over cosmic length scales. We discuss photon splitting within the framework of a Lorentz-covariant, phenomenological theory. This theory predicts (a) spectral broadening, (b) frequency-dependent red-shift, and (c) multiple red-shifts for each source. Because these effects do not show up, we can set observational limits on the parameters that govern the splitting. In particular, the 3-K background implies that a photon of arbitrary wavelength $\ensuremath{\lambda}$ propagating in flat space (i.e., without cosmological reddening) must have a decay lifetime larger than $(6 \frac{\mathrm{cm}}{\ensuremath{\lambda}})t$, where $t$ is the present age of the universe.

Extra lines in optical spectra of Tb(OH)3

The fluorescence spectrum of Tb(OH)3 at liquid helium temperatures exhibits a complex structure. Beside the well known electronic transitions many intense extra lines were found. The behavior of the extra lines under an external magnetic field and at various temperatures has been investigated and compared to that of the parent electronic lines. It is shown that the extra lines can be explained by internal mechanical stress.

Thermal Broadening and Shift of the Zero‐Phonon Lines in Optical Spectra of Impurity Organic Crystals

AbstractA theoretical interpretation is made of all the data on the temperature broadening and shift of the zero‐phonon lines in spectra of impurity normal paraffin crystals. It is shown that the broadening of most lines investigated may be well described in the Debye approximation using the theoretical dependence, obtained on the basis of the Krivoglaz‐McCumber model in which adiabatic, Condon and harmonic approximations were utilized, and a small change of the elastic constants of the lattice vibrations and a displacement of the equilibrium positions of nuclei induced by the electron transition in the impurity centre were taken into account. The line shifts could not be described by the theoretical formula obtained in the same approximation. The possible reasons of this discrepancy are discussed.

Thermal resolution of desorption energy spectra

The rate equations for desorption of sorbed gases from solids are considered where the solid surface is exposed to a time varying temperature schedule. Three cases are considered. Firstly the case of constant energy of binding sites; secondly discrete energy heterogeneous sites; and thirdly a continuum of heterogeneous sites. New techniques for the evaluation of the desorption energy, the initial site population and the order of the reaction are considered, and the analogy, in the second case above, between the optical line spectrum and desorption from discrete energy sites, is shown to be useful in determining the ability of the temperature displacement technique to resolve multiple energy peaks.

A Possible Nuclear Effect in Magnetic Cooling Experiments on Copper Salts

ATTENTION has recently been directed by Gorter1 to the existence of a splitting of the energy-levels of paramagnetic salts due to the coupling between the electronic and nuclear magnetic moments. The level separation, which is of the order of 0·1 cm.â1, is seen in the hyperfine structure of the optical line spectrum. Now such a splitting, ought also to lead to a Schottky specific heat anomaly at temperatures of the order of 0·1° K., that is, some 104 times higher than in salts the paramagnetism of which is due only to the nuclei.