VUV spectroscopic study of the ? state of H2

NASA Astrophysics Data System (ADS)

Dickenson, G. D.; Ubachs, W.

2014-04-01

Spectral lines, probing rotational quantum states J‧ = 0, 1, 2 of the inner well vibrations (υ‧ ≤ 8) in the ? state of molecular hydrogen, were recorded in high resolution using a vacuum ultraviolet Fourier transform absorption spectrometer in the wavelength range 73-86 nm. Accurate line positions and predissociation widths are determined from a fit to the absorption spectra. Improved values for the line positions are obtained, while the predissociation widths agree well with previous investigations.

Resolution modeling of dispersive imaging spectrometers

NASA Astrophysics Data System (ADS)

Silny, John F.

2017-08-01

This paper presents best practices for modeling the resolution of dispersive imaging spectrometers. The differences between sampling, width, and resolution are discussed. It is proposed that the spectral imaging community adopt a standard definition for resolution as the full-width at half maximum of the total line spread function. Resolution should be computed for each of the spectral, cross-scan spatial, and along-scan spatial/temporal dimensions separately. A physical optics resolution model is presented that incorporates the effects of slit diffraction and partial coherence, the result of which is a narrower slit image width and reduced radiometric throughput.

The broad-band X-ray spectral variability of Mrk 841

NASA Technical Reports Server (NTRS)

George, I. M.; Nandra, K.; Fabian, A. C.; Turner, T. J.; Done, C.; Day, C. S. R.

1993-01-01

A detailed spectral analysis of five X-ray observations of Mrk 841 with the EXOSAT, Ginga, and ROSAT satellites is reported. Variability is apparent in both the soft (0.1-1.0 keV) and medium (1-20 keV) energy bands. Above, 1 keV, the spectra are adequately modeled by a power law with a strong emission line of equivalent width 450 eV. The large equivalent width of the emission line indicates a strongly enhanced reflection component of the source compared with other Seyferts observed with Ginga. The implications of the results of the analysis for physical models of the emission regions in this and other X-ray bright Seyferts are briefly examined.

THE FORMATION OF IRIS DIAGNOSTICS. VIII. IRIS OBSERVATIONS IN THE C ii 133.5 nm MULTIPLET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rathore, Bhavna; Pereira, Tiago M. D.; Carlsson, Mats

The C ii 133.5 nm multiplet has been observed by NASA’s Interface Region Imaging Spectrograph (IRIS) in unprecedented spatial resolution. The aims of this work are to characterize these new observations of the C ii lines, place them in context with previous work, and to identify any additional value the C ii lines bring when compared with other spectral lines. We make use of wide, long exposure IRIS rasters covering the quiet Sun and an active region. Line properties such as velocity shift and width are extracted from individual spectra and analyzed. The lines have a variety of shapes (mostlymore » single-peak or double-peak), are strongest in active regions and weaker in the quiet Sun. The ratio between the 133.4 and 133.5 nm components is always less than 1.8, indicating that their radiation is optically thick in all locations. Maps of the C ii line widths are a powerful new diagnostic of chromospheric structures, and their line shifts are a robust velocity diagnostic. Compared with earlier quiet Sun observations, we find similar absolute intensities and mean line widths, but smaller redshifts; this difference can perhaps be attributed to differences in spectral resolution and spatial coverage. The C ii intensity maps are somewhat similar to those of transition region lines, but also share some features with chromospheric maps such as those from the Mg ii k line, indicating that they are formed between the upper chromosphere and transition region. C ii intensity, width, and velocity maps can therefore be used to gather additional information about the upper chromosphere.« less

Thermal Boundary Layer Effects on Line-of-Sight Tunable Diode Laser Absorption Spectroscopy (TDLAS) Gas Concentration Measurements.

PubMed

Qu, Zhechao; Werhahn, Olav; Ebert, Volker

2018-06-01

The effects of thermal boundary layers on tunable diode laser absorption spectroscopy (TDLAS) measurement results must be quantified when using the line-of-sight (LOS) TDLAS under conditions with spatial temperature gradient. In this paper, a new methodology based on spectral simulation is presented quantifying the LOS TDLAS measurement deviation under conditions with thermal boundary layers. The effects of different temperature gradients and thermal boundary layer thickness on spectral collisional widths and gas concentration measurements are quantified. A CO 2 TDLAS spectrometer, which has two gas cells to generate the spatial temperature gradients, was employed to validate the simulation results. The measured deviations and LOS averaged collisional widths are in very good agreement with the simulated results for conditions with different temperature gradients. We demonstrate quantification of thermal boundary layers' thickness with proposed method by exploitation of the LOS averaged the collisional width of the path-integrated spectrum.

Very narrow band model calculations of atmospheric fluxes and cooling rates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernstein, L.S.; Berk, A.; Acharya, P.K.

1996-10-15

A new very narrow band model (VNBM) approach has been developed and incorporated into the MODTRAN atmospheric transmittance-radiance code. The VNBM includes a computational spectral resolution of 1 cm{sup {minus}1}, a single-line Voigt equivalent width formalism that is based on the Rodgers-Williams approximation and accounts for the finite spectral width of the interval, explicit consideration of line tails, a statistical line overlap correction, a new sublayer integration approach that treats the effect of the sublayer temperature gradient on the path radiance, and the Curtis-Godson (CG) approximation for inhomogeneous paths. A modified procedure for determining the line density parameter 1/d ismore » introduced, which reduces its magnitude. This results in a partial correction of the VNBM tendency to overestimate the interval equivalent widths. The standard two parameter CG approximation is used for H{sub 2}O and CO{sub 2}, while the Goody three parameter CG approximation is used for O{sub 3}. Atmospheric flux and cooling rate predictions using a research version of MODTRAN, MODR, are presented for H{sub 2}O (with and without the continuum), CO{sub 2}, and O{sub 3} for several model atmospheres. The effect of doubling the CO{sub 2} concentration is also considered. These calculations are compared to line-by-line (LBL) model calculations using the AER, GLA, GFDL, and GISS codes. The MODR predictions fall within the spread of the LBL results. The effects of decreasing the band model spectral resolution are illustrated using CO{sub 2} cooling rate and flux calculations. 36 refs., 18 figs., 1 tab.« less

Electron Stark Broadening Database for Atomic N, O, and C Lines

NASA Technical Reports Server (NTRS)

Liu, Yen; Yao, Winifred M.; Wray, Alan A.; Carbon, Duane F.

2012-01-01

A database for efficiently computing the electron Stark broadening line widths for atomic N, O, and C lines is constructed. The line width is expressed in terms of the electron number density and electronatom scattering cross sections based on the Baranger impact theory. The state-to-state cross sections are computed using the semiclassical approximation, in which the atom is treated quantum mechanically whereas the motion of the free electron follows a classical trajectory. These state-to-state cross sections are calculated based on newly compiled line lists. Each atomic line list consists of a careful merger of NIST, Vanderbilt, and TOPbase line datasets from wavelength 50 nm to 50 micrometers covering the VUV to IR spectral regions. There are over 10,000 lines in each atomic line list. The widths for each line are computed at 13 electron temperatures between 1,000 K 50,000 K. A linear least squares method using a four-term fractional power series is then employed to obtain an analytical fit for each line-width variation as a function of the electron temperature. The maximum L2 error of the analytic fits for all lines in our line lists is about 5%.

[The application of Doppler broadening and Doppler shift to spectral analysis].

PubMed

Xu, Wei; Fang, Zi-shen

2002-08-01

The distinction between Doppler broadening and Doppler shift has analyzed, Doppler broadening locally results from the distribution of velocities of the emitting particles, the line width gives the information on temperature of emitting particles. Doppler shift results when the emitting particles have a bulk non random flow velocity in a particular direction, the drift of central wavelength gives the information on flow velocity of emitting particles, and the Doppler shift only drifts the profile of line without changing the width. The difference between Gaussian fitting and the distribution of chord-integral line shape have also been discussed. The distribution of H alpha spectral line shape has been derived from the surface of limiter in HT-6M Tokamak with optical spectroscope multichannel analysis (OSMA), the result by double Gaussian fitting shows that the line shape make up of two port, the emitting of reflect particles with higher energy and the release particle from the limiter surface. Ion temperature and recycling particle flow velocity have been obtained from Doppler broadening and Doppler shift.

Measurements of argon-, helium-, hydrogen-, and nitrogen-broadened widths of methane lines near 9000 per cm

NASA Technical Reports Server (NTRS)

Fox, Kenneth; Jennings, Donald E.; Stern, Elizabeth A.; Hubbard, Rob

1988-01-01

Pressure-broadened widths of rotational-vibrational lines in CH4 have been measured at very high spectral resolution in the R-branch of the 3nu3 overtone. The broadening gases were Ar, He, H2, and N2. Results are presented as averages for J-multiplets at ambient temperature. The overall values (per cm per atm) for these R-branch lines are 0.0651 (CH4-Ar), 0.0508 (CH4-He), 0.0728 (CH4-H2), and 0.0715 (CH4-N2).

In-Flight Spectral Calibration of the APEX Imaging Spectrometer Using Fraunhofer Lines

NASA Astrophysics Data System (ADS)

Kuhlmann, Gerrit; Hueni, Andreas; Damm, Aalexander; Brunner, Dominik

2015-11-01

The Airborne Prism EXperiment (APEX) is an imaging spectrometer which allows to observe atmospheric trace gases such as nitrogen dioxide (NO2). Using a high resolution spectrum of solar Fraunhofer lines, APEX measurements collected during flight have been spectrally calibrated for centre wavelength positions (CW) and instrument slit function (ISF) and compared to the laboratory calibration. We find that CWs depend strongly on both across- and along-track position due to spectral smile and CWs dependency on ambient pressure. The width of the ISF is larger than estimated from the laboratory calibration but can be described by a linear scaling of the laboratory values. The ISF width depends on across- but not on along-track direction. The results demonstrate the importance of characterizing and monitoring the instrument performance during flight and will be used to improve the Empa APEX NO2 retrieval algorithm.

Effects of distributions of energy of transfer rates on spectral hole burning in photosynthetic pigment-protein complexes

NASA Astrophysics Data System (ADS)

Ahmouda, Somaya

To perform photosynthesis, plants, algae and bacteria possess well organized and closely coupled photosynthetic pigment-protein complexes. Information on energy transfer in photosynthetic complexes is important to understand their functioning and possibly to design new and improved photovoltaic devices. The information on energy transfer processes contained in the narrow zero-phonon lines at low temperatures is hidden under the inhomogeneous broadening. Thus, it has been proven difficult to analyze the spectroscopic properties of these complexes in sufficient detail by conventional spectroscopy methods. In this context the high resolution spectroscopy techniques such as Spectral Hole Burning are powerful tools designed to get around the inhomogeneous broadening. Spectral Hole Burning involves selective excitation by a laser which removes molecules with the zero-phonon transitions resonant with this laser. This thesis focuses on the effects of the distributions of the energy transfer rates (homogeneous line widths) on the evolution of spectral holes. These distributions are a consequence of the static disorder in the photosynthetic pigment-protein complexes. The qualitative effects of different types of the line width distributions on the evolution of spectral holes have been and explored by numerical simulations, an example of analysis of the original experimental data has been presented as well.

Highly Sensitive Refractive Index Sensors with Plasmonic Nanoantennas-Utilization of Optimal Spectral Detuning of Fano Resonances.

PubMed

Mesch, Martin; Weiss, Thomas; Schäferling, Martin; Hentschel, Mario; Hegde, Ravi S; Giessen, Harald

2018-05-25

We analyze and optimize the performance of coupled plasmonic nanoantennas for refractive index sensing. The investigated structure supports a sub- and super-radiant mode that originates from the weak coupling of a dipolar and quadrupolar mode, resulting in a Fano-type spectral line shape. In our study, we vary the near-field coupling of the two modes and particularly examine the influence of the spectral detuning between them on the sensing performance. Surprisingly, the case of matched resonance frequencies does not provide the best sensor. Instead, we find that the right amount of coupling strength and spectral detuning allows for achieving the ideal combination of narrow line width and sufficient excitation strength of the subradiant mode, and therefore results in optimized sensor performance. Our findings are confirmed by experimental results and first-order perturbation theory. The latter is based on the resonant state expansion and provides direct access to resonance frequency shifts and line width changes as well as the excitation strength of the modes. Based on these parameters, we define a figure of merit that can be easily calculated for different sensing geometries and agrees well with the numerical and experimental results.

A frequency doubled pressure-tunable oscillator-amplifier dye laser system

NASA Technical Reports Server (NTRS)

Moriarty, A.; Heaps, W.; Davis, D. D.

1976-01-01

A tunable high-repetition-rate oscillator-amplifier dye-laser system is reported. The dye laser described was longitudinally pumped with the second harmonic of a Nd-YAG laser operating at 10 Hz. Using three Faraday-Perot etalons and pressure tuning, a maximum fundamental output power of the order of 6 MW with a corresponding spectral width of less than 0.003 nm at 564 nm was obtained. The fundamental at 564 nm was frequency doubled to give a maximum power level of 0.6 MW of second-harmonic output power with a spectral width less than 0.0015 nm at 282 nm. Frequency stability could be maintained to within approximately 15% of the line-width.

Contamination of the 5394 Å spectral region by telluric lines

NASA Astrophysics Data System (ADS)

Vince, I.; Vince, O.

2010-11-01

The spectral region in the vicinity of 5394 Å contains three prominent photospheric spectral lines, which can be used as a solar plasma diagnostic tool. The occurrence of telluric lines in this region is a potential source of systematic and random errors in these solar spectral lines. The goal of our investigation was to determine the telluric line contamination of this interesting spectral region. Several series of high-resolution solar spectra within an interval of about 4 Å around the 5394 Å wavelength were observed at different zenith distances of the Sun. Comparison of these spectra has permitted identification of telluric lines in this spectral interval. The observations were carried out with the horizontal solar spectrograph of the Heliophysical Observatory in Debrecen. Telluric feature blending was identified in the blue and red wings of the Fe I 5393.2 Å line, and in the local continuum of the Mn I 5394.7 Å line. The blue wing of the Fe I 5395.2 Å line is contaminated by a weak telluric feature too. The red continuum of this line has a more prominent telluric contamination. A dozen of water vapor telluric lines that determined the observed telluric features were identified in this spectral interval. The profiles of three telluric lines that have a significant influence on both the profiles of solar spectral lines and the level of local continuum were derived, and the variation of their parameters (equivalent width and central depth) with air mass were analyzed.

High spectral resolution observations of fluorescent molecular hydrogen in molecular clouds

NASA Technical Reports Server (NTRS)

Burton, Michael G.; Geballe, T. R.; Brand, P. W. J. L.; Moorhouse, A.

1990-01-01

The 1-0 S(1) line of molecular hydrogen has been observed at high spectral resolution in several sources where the emission was suspected of being fluorescent. In NGC 2023, the Orion Bar, and Parsamyan 18, the S(1) line is unresolved, and the line center close to the rest velocity of the ambient molecular cloud. Such behavior is expected for UV-excited line emission. The H2 line widths in molecular clouds thus can serve as diagnostic for shocked and UV-excitation mechanisms. If the lines are broader than several km/s or velocity shifts are observed across a source it is likely that shocks are responsible for the excitation of the gas.

Spectroscopic survey of southern hemisphere white dwarfs. II. Spectroscopic data for forty-one southern white dwarfs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wegner, G.

New spectroscopic data on 41 southern white dwarfs are presented. Most of these stars have not teen previously observed spectroscopically. Spectral types, as well as equivalent widths and line profiles for a few selected lines, are given. (auth)

Synthetic spectral analysis of a kinetic model for slow-magnetosonic waves in solar corona

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruan, Wenzhi; He, Jiansen; Tu, Chuanyi

We propose a kinetic model of slow-magnetosonic waves to explain various observational features associated with the propagating intensity disturbances (PIDs) occurring in the solar corona. The characteristics of slow mode waves, e.g, inphase oscillations of density, velocity, and thermal speed, are reproduced in this kinetic model. Moreover, the red-blue (R-B) asymmetry of the velocity distribution as self-consistently generated in the model is found to be contributed from the beam component, as a result of the competition between Landau resonance and Coulomb collisions. Furthermore, we synthesize the spectral lines and make the spectral analysis, based on the kinetic simulation data ofmore » the flux tube plasmas and the hypothesis of the surrounding background plasmas. It is found that the fluctuations of parameters of the synthetic spectral lines are basically consistent with the observations: (1) the line intensity, Doppler shift, and line width are fluctuating in phase; (2) the R-B asymmetry usually oscillate out of phase with the former three parameters; (3) the blueward asymmetry is more evident than the redward asymmetry in the R-B fluctuations. The oscillations of line parameters become weakened for the case with denser surrounding background plasmas. Similar to the observations, there is no doubled-frequency oscillation of the line width for the case with flux-tube plasmas flowing bulkly upward among the static background plasmas. Therefore, we suggest that the “wave + beam flow” kinetic model may be a viable interpretation for the PIDs observed in the solar corona.« less

SYNTHETIC HYDROGEN SPECTRA OF OSCILLATING PROMINENCE SLABS IMMERSED IN THE SOLAR CORONA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zapiór, M.; Heinzel, P.; Oliver, R.

We study the behavior of H α and H β spectral lines and their spectral indicators in an oscillating solar prominence slab surrounded by the solar corona, using an MHD model combined with a 1D radiative transfer code taken in the line of sight perpendicular to the slab. We calculate the time variation of the Doppler shift, half-width, and maximum intensity of the H α and H β spectral lines for different modes of oscillation. We find a non-sinusoidal time dependence of some spectral parameters with time. Because H α and H β spectral indicators have different behavior for differentmore » modes, caused by differing optical depths of formation and different plasma parameter variations in time and along the slab, they may be used for prominence seismology, especially to derive the internal velocity field in prominences.« less

Studies on 405nm blue-violet diode laser with external grating cavity

NASA Astrophysics Data System (ADS)

Li, Bin; Gao, Jun; Zhao, Jun; Yu, Anlan; Luo, Shiwen; Xiong, Dongsheng; Wang, Xinbing; Zuo, Duluo

2016-03-01

Spectroscopy applications of free-running laser diodes (LD) are greatly restricted as its broad band spectral emission. And the power of a single blue-violet LD is around several hundred milliwatts by far, it is of great importance to obtain stable and narrow line-width laser diodes with high efficiency. In this paper, a high efficiency external cavity diode laser (ECDL) with high output power and narrow band emission at 405 nm is presented. The ECDL is based on a commercially available LD with nominal output power of 110 mW at an injection current of 100 mA. The spectral width of the free-running LD is about 1 nm (FWHM). A reflective holographic grating which is installed on a home-made compact adjustable stage is utilized for optical feedback in Littrow configuration. In this configuration, narrow line-width operation is realized and the effects of grating groove density as well as the groove direction related to the beam polarization on the performances of the ECDL are experimentally investigated. In the case of grating with groove density of 3600 g/mm, the threshold is reduced from 21 mA to 18.3 mA or 15.6 mA and the tuning range is 3.95 nm or 6.01 nm respectively when the grating is orientated in TE or TM polarization. In addition, an output beam with a line-width of 30 pm and output power of 92.7 mW is achieved in TE polarization. With these narrow line-width and high efficiency, the ECDL is capable to serve as a light source for spectroscopy application such as Raman scattering and laser induced fluorescence.

Spectrum radial velocity analyser (SERVAL). High-precision radial velocities and two alternative spectral indicators

NASA Astrophysics Data System (ADS)

Zechmeister, M.; Reiners, A.; Amado, P. J.; Azzaro, M.; Bauer, F. F.; Béjar, V. J. S.; Caballero, J. A.; Guenther, E. W.; Hagen, H.-J.; Jeffers, S. V.; Kaminski, A.; Kürster, M.; Launhardt, R.; Montes, D.; Morales, J. C.; Quirrenbach, A.; Reffert, S.; Ribas, I.; Seifert, W.; Tal-Or, L.; Wolthoff, V.

2018-01-01

Context. The CARMENES survey is a high-precision radial velocity (RV) programme that aims to detect Earth-like planets orbiting low-mass stars. Aims: We develop least-squares fitting algorithms to derive the RVs and additional spectral diagnostics implemented in the SpEctrum Radial Velocity AnaLyser (SERVAL), a publicly available python code. Methods: We measured the RVs using high signal-to-noise templates created by coadding all available spectra of each star. We define the chromatic index as the RV gradient as a function of wavelength with the RVs measured in the echelle orders. Additionally, we computed the differential line width by correlating the fit residuals with the second derivative of the template to track variations in the stellar line width. Results: Using HARPS data, our SERVAL code achieves a RV precision at the level of 1 m/s. Applying the chromatic index to CARMENES data of the active star YZ CMi, we identify apparent RV variations induced by stellar activity. The differential line width is found to be an alternative indicator to the commonly used full width half maximum. Conclusions: We find that at the red optical wavelengths (700-900 nm) obtained by the visual channel of CARMENES, the chromatic index is an excellent tool to investigate stellar active regions and to identify and perhaps even correct for activity-induced RV variations.

Amide I SFG Spectral Line Width Probes the Lipid-Peptide and Peptide-Peptide Interactions at Cell Membrane In Situ and in Real Time.

PubMed

Zhang, Baixiong; Tan, Junjun; Li, Chuanzhao; Zhang, Jiahui; Ye, Shuji

2018-06-13

The balance of lipid-peptide and peptide-peptide interactions at cell membrane is essential to a large variety of cellular processes. In this study, we have experimentally demonstrated for the first time that sum frequency generation vibrational spectroscopy can be used to probe the peptide-peptide and lipid-peptide interactions in cell membrane in situ and in real time by determination of the line width of amide I band of protein backbone. Using a "benchmark" model of α-helical WALP23, it is found that the dominated lipid-peptide interaction causes a narrow line width of the amide I band, whereas the peptide-peptide interaction can markedly broaden the line width. When WALP23 molecules insert into the lipid bilayer, a quite narrow line width of the amide I band is observed because of the lipid-peptide interaction. In contrast, when the peptide lies down on the bilayer surface, the line width of amide I band becomes very broad owing to the peptide-peptide interaction. In terms of the real-time change in the line width, the transition from peptide-peptide interaction to lipid-peptide interaction is monitored during the insertion of WALP23 into 1,2-dipalmitoyl- sn-glycero-3-phospho-(1'- rac-glycerol) (DPPG) lipid bilayer. The dephasing time of a pure α-helical WALP23 in 1-palmitoyl-2-oleoyl- sn-glycero-3-phospho-(1'- rac-glycerol) and DPPG bilayer is determined to be 2.2 and 0.64 ps, respectively. The peptide-peptide interaction can largely accelerate the dephasing time.

Single steady frequency and narrow-linewidth external-cavity semiconductor laser

NASA Astrophysics Data System (ADS)

Zhao, Weirui; Jiang, Pengfei; Xie, Fuzeng

2003-11-01

A single longitudinal mode and narrow line width external cavity semiconductor laser is proposed. It is constructed with a semiconductor laser, collimator, a flame grating, and current and temperature control systems. The one facet of semiconductor laser is covered by high transmission film, and another is covered by high reflection film. The flame grating is used as light feedback element to select the mode of the semiconductor laser. The temperature of the constructed external cavity semiconductor laser is stabilized in order of 10-3°C by temperature control system. The experiments have been carried out and the results obtained - the spectral line width of this laser is compressed to be less than 1.4MHz from its original line-width of more than 1200GHz and the output stability (including power and mode) is remarkably enhanced.

VizieR Online Data Catalog: Chemical abundances of 8 metal-poor stars (Ishigaki+, 2014)

NASA Astrophysics Data System (ADS)

Ishigaki, M. N.; Aoki, W.; Arimoto, N.; Okamoto, S.

2014-01-01

Equivalent widths and chemical abundances of the six giant stars in Bootes I dwarf spheroidal galaxy (Boo-009, Boo-094, Boo-117, Boo-121, Boo-127, Boo-911) and the two Milky Way halo stars (HD216143, HD85773) are presented. For each spectral line, excitation potential, loggf values, measured equivalent widths and abundances are given. (2 data files).

Magnetic fluorescent lamp

DOEpatents

Berman, S.M.; Richardson R.W.

1983-12-29

The radiant emission of a mercury-argon discharge in a fluorescent lamp assembly is enhanced by providing means for establishing a magnetic field with lines of force along the path of electron flow through the bulb of the lamp assembly, to provide Zeeman splitting of the ultraviolet spectral line. Optimum results are obtained when the magnetic field strength causes a Zeeman splitting of approximately 1.7 times the thermal line width.

Temperature dependence of Lorentz air-broadening and pressure-shift coefficients of (12)CH4 lines in the 2.3-micron spectral region

NASA Technical Reports Server (NTRS)

Devi, V. Malathy; Benner, D. Chris; Smith, M. A. H.; Rinsland, C. P.

1994-01-01

High-resolution (0.01/cm) absorption spectra of lean mixtures of CH4 in dry air were recorded with the McMath-Pierce Fourier transform spectrometer (FTS) of the National Solar Observatory on Kitt Peak at various temperatures between 24 and -61 C. The spectra have been analyzed to determine the values at room temperature of pressure-broadened widths and pressure-induced shifts of more than 740 transitions. The temperature dependence of air-broadened widths and pressure-induced shifts was deduced for approx. 370 transitions in the nu(sub 1) + nu(sub 4), nu(sub 3) + nu(sub 4), and nu(sub 2) + nu(sub 3) bands of (12)CH4 located between 4118 and 4615/cm. These results were obtained by analyzing a total of 29 spectra simultaneously using a multi-spectral non-linear least-squares fitting technique. This new technique allowed the determination of correlated spectral line parameters (e.g. intensity and broadening coefficient) better than the procedure of averaging values obtained by fitting the spectra individually. This method also provided a direct determination of the uncertainties in the retrieved parameters due to random errors. For each band analysed in this study the dependence of the various spectral line parameters upon the tetrahedral symmetry species and the rotational quantum numbers of the transitions is also presented.

Measurement of Spectral Broadening in PTS-Polydiacetylene

NASA Astrophysics Data System (ADS)

Bhowmik, Achintya; Thakur, Mrinal

1998-03-01

PTS-polydiacetylene has significant potential for future applications in ultrafast all-optical switches and logic gates.(R. Quintero-Torres and M. Thakur, Appl. Phys. Lett., 66, 1310 (1995).) In this work, we have made detailed measurements of the instantaneous spectral line broadening in a 500 μm thick PTS single-crystal as a function of intensity and wavelength. A mode-locked Ti-Sapphire laser with 2 ps pulse-width at 82 MHz repetition rate, and a Nd:YAG laser with 60 ps pulse-width at 10 Hz repetition rate were used for measurements at 720-840 nm and 1064 nm wavelength respectively. The spectral bandwidth of the beam was recorded before and after passing through the PTS single-crystal by a high-resolution spectrometer. The nonlinear refractive index (n_2) of PTS as a function of wavelength has been determined from the spectral broadening data.

Type II Supernova Spectral Diversity. I. Observations, Sample Characterization, and Spectral Line Evolution

NASA Astrophysics Data System (ADS)

Gutiérrez, Claudia P.; Anderson, Joseph P.; Hamuy, Mario; Morrell, Nidia; González-Gaitan, Santiago; Stritzinger, Maximilian D.; Phillips, Mark M.; Galbany, Lluis; Folatelli, Gastón; Dessart, Luc; Contreras, Carlos; Della Valle, Massimo; Freedman, Wendy L.; Hsiao, Eric Y.; Krisciunas, Kevin; Madore, Barry F.; Maza, José; Suntzeff, Nicholas B.; Prieto, Jose Luis; González, Luis; Cappellaro, Enrico; Navarrete, Mauricio; Pizzella, Alessandro; Ruiz, Maria T.; Smith, R. Chris; Turatto, Massimo

2017-11-01

We present 888 visual-wavelength spectra of 122 nearby type II supernovae (SNe II) obtained between 1986 and 2009, and ranging between 3 and 363 days post-explosion. In this first paper, we outline our observations and data reduction techniques, together with a characterization based on the spectral diversity of SNe II. A statistical analysis of the spectral matching technique is discussed as an alternative to nondetection constraints for estimating SN explosion epochs. The time evolution of spectral lines is presented and analyzed in terms of how this differs for SNe of different photometric, spectral, and environmental properties: velocities, pseudo-equivalent widths, decline rates, magnitudes, time durations, and environment metallicity. Our sample displays a large range in ejecta expansion velocities, from ˜9600 to ˜1500 km s-1 at 50 days post-explosion with a median {{{H}}}α value of 7300 km s-1. This is most likely explained through differing explosion energies. Significant diversity is also observed in the absolute strength of spectral lines, characterized through their pseudo-equivalent widths. This implies significant diversity in both temperature evolution (linked to progenitor radius) and progenitor metallicity between different SNe II. Around 60% of our sample shows an extra absorption component on the blue side of the {{{H}}}α P-Cygni profile (“Cachito” feature) between 7 and 120 days since explosion. Studying the nature of Cachito, we conclude that these features at early times (before ˜35 days) are associated with Si II λ 6355, while past the middle of the plateau phase they are related to high velocity (HV) features of hydrogen lines. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile; and the Gemini Observatory, Cerro Pachon, Chile (Gemini Program GS-2008B-Q-56). Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (ESO Programs 076.A-0156, 078.D-0048, 080.A-0516, and 082.A-0526).

Further studies with data collected by NASA's airborne Doppler lidar in Oklahoma in 1981

NASA Technical Reports Server (NTRS)

Bluestein, H. B.; Mccaul, E. W., Jr.

1986-01-01

Continued study of the lidar data collected in 1981 has resulted in significant new improvements in the analysis techniques reported by Bluestein et al. (1985) and McCaul (1985). Through comparison of fore- and aft-derived scalar fields of intensity and spectral width, the self-consistency of the lidar moment estimates was assessed. Reflectivity estimates were found to be quite stable and reliable, while spectral widths were prone to become noisy if signal to noise ratio (SNR) fell below 12 dB. In addition, spectral widths contained a significant component due to radial velocity gradients in areas along gust fronts, and these components were different along the fore and aft lines of sight. Significant improvement in agreement between the fore and aft fields of spectral width was obtained by estimating the radial velocity gradient component and then removing it from the raw measured widths to yield only the turbulent portion of the contribution to width. Additional analyses showed that lidar-derived vorticity estimates were consistent with several approximate models of vorticity growth along gust front zones, and with the hypothesis that Helmholtz instability could have been responsible for vortices seen along part of the gust front of 30 June 1981. Computations of divergence transverse to axes through an isolated cumulus congestus indicated that the strongest convergence tended to lie along an axis parallel to the congestus. This and the results of other additional analyses seem to suggest that the lidar winds do indeed accurately reflected the basic features of the real wind field.

Spectroscopy peculiarities of thermal plasma of electric arc discharge between electrodes with Zn admixtures

NASA Astrophysics Data System (ADS)

Semenyshyn, R. V.; Veklich, A. N.; Babich, I. L.; Boretskij, V. F.

2014-10-01

Plasma of the free burning electric arc between Ag-SnO2-ZnO composite electrodes as well as brass electrodes were investigated. The plasma temperature distributions were obtained by Boltzmann plot method involving Cu I, Ag I or Zn I spectral line emissions. The electron density distributions were obtained from the width and from absolute intensity of spectral lines. The laser absorption spectroscopy was used for measurement of copper atom concentration in plasma. Plasma equilibrium composition was calculated using two independent groups of experimental values (temperature and copper atom concentration, temperature and electron density). It was found that plasma of the free burning electric arc between brass electrodes is in local thermodynamical equilibrium. The experimental verification of the spectroscopic data of Zn I spectral lines was carried out.

Dual-broadband rotational CARS modelling of nitrogen at pressures up to 9 MPa. II. Rotational Raman line widths

NASA Astrophysics Data System (ADS)

Afzelius, M.; Bengtsson, P.-E.; Bood, J.; Bonamy, J.; Chaussard, F.; Berger, H.; Dreier, T.

Rotational coherent anti-Stokes Raman spectroscopy (CARS) is a well-established spectroscopic technique for thermometry at pre-combustion temperatures and atmospheric pressure. However, at pressures of several MPa, a previous investigation revealed large discrepancies between experimental data and the theoretical model. A re-evaluation has been made of these data (at room temperature and in the range 1.5-9 MPa) with two improvements to the spectral code. The first is the inclusion of an inter-branch interference effect, which is described in detail in Paper I. The second is the use of experimental S1-branch Raman line widths measured at 295 K, with a temperature dependence extracted from semi-classical calculations following the Robert-Bonamy formalism. It is shown that these two modifications significantly improve the theoretical model, since both the spectral fits and the accuracy of the evaluated temperatures are considerably improved.

Stark broadening of several Bi IV spectral lines of astrophysical interest

NASA Astrophysics Data System (ADS)

Colón, C.; Moreno-Díaz, C.; de Andrés-García, I.; Alonso-Medina, A.

2017-09-01

The presence of spectral lines of bismuth in stellar atmospheres has been reported in different stars. The anomalous values of the spectral intensities of Bi II and Bi III, compared to the theoretical Local Termodinamic Equilibrium (LTE) standards of Bi I/Bi II/Bi III, have been reported in the spectra obtained with the High Resolution Spectrograph of the Hubble/Goddard Space Telescope in the chemically peculiar stars HgMn stars χ Lupi and HR 7775. Spectral lines of 1436.8, 1902.3, 2630.9 and 2936.7 Å of Bi II and 1423.4 Å of Bi III were reported and their relative intensities were measured in these studies Litzén & Wahlgren 2002. These lines are overlapped with spectral lines of 1437.65, 2630.1 and 2937.1 Å of Bi IV. A study of the Stark broadening parameters of Bi IV spectral lines can help to study these overlaps. In this paper, using the Griem semi-empirical approach, we report calculated values of the Stark parameters for 64 spectral lines of Bi IV. The matrix elements used in these calculations have been determined from 17 configurations of Bi IV. They were calculated using the cowan code including core polarization effects. Data are displayed for an electron density of 1017 cm-3 and temperatures T = 10 000-160 000 K. Also calculated radiative lifetimes for 12 levels with experimental lifetime are presented, in order to test the goodness of our calculations. Theoretical trends of the Stark width and shift parameters versus the temperature for spectral lines of astrophysical interest are displayed.

A light-induced microwave oscillator

NASA Technical Reports Server (NTRS)

Yao, X. S.; Maleki, L.

1995-01-01

We describe a novel oscillator that converts continuous light energy into sta ble and spectrally pure microwave signals. This light-induced microwave oscillator (LIMO) consists of a pump laser and a feedback circuit, including an intensity modulator, an optical fiber delay line, a photodetector, an amplifier, and a filter. We develop a quasilinear theory and obtain expressions for the threshold condition, the amplitude, the frequency, the line width, and the spectral power density of the oscillation. We also present experimental data to compare with the theoretical results. Our findings indicate that the LIMO can generate ultrastable, spectrally pure microwave reference signals up to 75 GHz with a phase noise lower than -140 dBc/Hz at 10 kHz.

Structure of sunspot light bridges in the chromosphere and transition region

NASA Astrophysics Data System (ADS)

Rezaei, R.

2018-01-01

Context. Light bridges (LBs) are elongated structures with enhanced intensity embedded in sunspot umbra and pores. Aims: We studied the properties of a sample of 60 LBs observed with the Interface Region Imaging Spectrograph (IRIS). Methods: Using IRIS near- and far-ultraviolet spectra, we measured the line intensity, width, and Doppler shift; followed traces of LBs in the chromosphere and transition region (TR); and compared LB parameters with umbra and quiet Sun. Results: There is a systematic emission enhancement in LBs compared to nearby umbra from the photosphere up to the TR. Light bridges are systematically displaced toward the solar limb at higher layers: the amount of the displacement at one solar radius compares well with the typical height of the chromosphere and TR. The intensity of the LB sample compared to the umbra sample peaks at the middle/upper chromosphere where they are almost permanently bright. Spectral lines emerging from the LBs are broader than the nearby umbra. The systematic redshift of the Si IV line in the LB sample is reduced compared to the quiet Sun sample. We found a significant correlation between the line width of ions arising at temperatures from 3 × 104 to 1.5 × 105 K as there is also a strong spatial correlation among the line and continuum intensities. In addition, the intensity-line width relation holds for all spectral lines in this study. The correlations indicate that the cool and hot plasma in LBs are coupled. Conclusions: Light bridges comprise multi-temperature and multi-disciplinary structures extending up to the TR. Diverse heating sources supply the energy and momentum to different layers, resulting in distinct dynamics in the photosphere, chromosphere, and TR.

Spectra of High-Ionization Seyfert 1 Galaxies: Implications for the Narrow-Line Region

NASA Technical Reports Server (NTRS)

Moore, David; Cohen, Ross D.; Marcy, Geoffrey W.

1996-01-01

We present line profiles and profile parameters for the Narrow-Line Regions (NLRs) of six Seyfert 1 galaxies with high-ionization lines: MCG 8-11-11, Mrk 79, Mrk 704, Mrk 841, NGC 4151, and NGC 5548. The sample was chosen primarily with the goal of obtaining high-quality [Fe VII] lambda6087 and, when possible, [Fe X] lambda6374 profiles to determine if these lines are more likely formed in a physically distinct 'coronal line region' or are formed throughout the NLR along with lines of lower critical density (n(sub cr)) and/or Ionization Potential (IP). We discuss correlations of velocity shift and width with n(sub cr) and IP. In some objects, lines of high IP and/or n(sub cr) are systematically broader than those of low IP/n(sub cr). Of particular interest, however, are objects that show no correlations of line width with either IP or n(sub cr). In these objects, lines of high and low IP/n(sub cr), are remarkably similar, which is difficult to reconcile with the classical picture of the NLR, in which lines of high and low IP/n(sub cr) are formed in physically distinct regions. We argue for similar spatial extents for the flux in lines with similar profiles. Here, as well as in a modeling-oriented companion paper, we develop further an idea suggested by Moore & Cohen that objects that do and do not show line width correlations with IP/n(sub cr) can both be explained in terms of a single NLR model with only a small difference in the cloud column density distinguishing the two types of object. Overall, our objects do not show correlations between the Full Width at Half-Maximum (FWHM) and IP and/or n(sub cr). The width must be defined by a parameter that is sensitive to extended profile wings in order for the correlations to result. We present models in which FWHM correlations with IP and/or n(sub cr) result only after simulating the lower spectral resolution used in previous observational studies. The models that simulate the higher spectral resolution of our observational study produce line width correlations only if the width is defined by a parameter that is more sensitive to extended profile wings than is the FWHM. Our sample of six objects is in effect augmented by incorporating the larger sample (16 objects) of Veilleux into some of our discussion. This paper focuses on new interpretations of NLR emission-line spectra and line profiles that stem directly from the observations. Paper 2 focuses on modeling and complements this paper by illustrating explicitly the effects that spatial variations in electron density, ionization parameter, and column density have on model profiles. By comparing model profiles with the observed profiles presented here, as well as with those presented by Veilleux, Paper 2 yields insight into how the electron density, ionization parameter, and column density likely vary throughout the NLR.

Spectral analysis comparisons of Fourier-theory-based methods and minimum variance (Capon) methods

NASA Astrophysics Data System (ADS)

Garbanzo-Salas, Marcial; Hocking, Wayne. K.

2015-09-01

In recent years, adaptive (data dependent) methods have been introduced into many areas where Fourier spectral analysis has traditionally been used. Although the data-dependent methods are often advanced as being superior to Fourier methods, they do require some finesse in choosing the order of the relevant filters. In performing comparisons, we have found some concerns about the mappings, particularly when related to cases involving many spectral lines or even continuous spectral signals. Using numerical simulations, several comparisons between Fourier transform procedures and minimum variance method (MVM) have been performed. For multiple frequency signals, the MVM resolves most of the frequency content only for filters that have more degrees of freedom than the number of distinct spectral lines in the signal. In the case of Gaussian spectral approximation, MVM will always underestimate the width, and can misappropriate the location of spectral line in some circumstances. Large filters can be used to improve results with multiple frequency signals, but are computationally inefficient. Significant biases can occur when using MVM to study spectral information or echo power from the atmosphere. Artifacts and artificial narrowing of turbulent layers is one such impact.

No evidence for Lyman α emission in spectroscopy of z > 7 candidate galaxies

NASA Astrophysics Data System (ADS)

Caruana, Joseph; Bunker, Andrew J.; Wilkins, Stephen M.; Stanway, Elizabeth R.; Lacy, Mark; Jarvis, Matt J.; Lorenzoni, Silvio; Hickey, Samantha

2012-12-01

We present Gemini/Gemini Near Infrared Spectrograph (GNIRS) spectroscopic observations of four z-band (z ≈ 7) dropout galaxies and Very Large Telescope (VLT)/XSHOOTER observations of one z-band dropout and three Y-band (z ≈ 8-9) dropout galaxies in the Hubble Ultra Deep Field, which were selected with Wide Field Camera 3 imaging on the Hubble Space Telescope. We find no evidence of Lyman α emission with a typical 5σ sensitivity of 5 × 10-18 erg cm-2 s-1, and use the upper limits on Lyman α flux and the broad-band magnitudes to constrain the rest-frame equivalent widths for this line emission. Accounting for incomplete spectral coverage, we survey 3.0 z-band dropouts and 2.9 Y-band dropouts to a Lyman α rest-frame equivalent width limit >120 Å (for an unresolved emission line); for an equivalent width limit of 50 Å the effective numbers of drop-outs surveyed fall to 1.2 z-band drop-outs and 1.5 Y-band drop-outs. A simple model where the fraction of high rest-frame equivalent width emitters follows the trend seen at z = 3-6.5 is inconsistent with our non-detections at z = 7-9 at the ≈1σ level for spectrally unresolved lines, which may indicate that a significant neutral H I fraction in the intergalactic medium suppresses the Lyman α line in z-drop and Y-drop galaxies at z > 7. Based on observations collected at the European Organization for Astronomical Research in the Southern Hemisphere, Chile, as part of programme 086.A-0968(B).

Line shape parameters of PH3 transitions in the Pentad near 4-5 μm: Self-broadened widths, shifts, line mixing and speed dependence

NASA Astrophysics Data System (ADS)

Malathy Devi, V.; Benner, D. Chris; Kleiner, Isabelle; Sams, Robert L.; Fletcher, Leigh N.

2014-08-01

Accurate knowledge of spectroscopic line parameters of PH3 is important for remote sensing of the outer planets, especially Jupiter and Saturn. In a recent study, line positions and intensities for the Pentad bands of PH3 have been reported from analysis of high-resolution, high signal-to noise room-temperature spectra recorded with two Fourier transform spectrometers (2014) [1]. The results presented in this study were obtained during the analysis of positions and intensities, but here we focus on the measurements of spectral line shapes (e.g. widths, shifts, line mixing) for the 2ν4, ν2 + ν4, ν1 and ν3 bands. A multispectrum nonlinear least squares curve fitting technique employing a non-Voigt line shape to include line mixing and speed dependence of the Lorentz width was employed to fit the spectra simultaneously. The least squares fittings were performed on five room-temperature spectra recorded at various PH3 pressures (∼2-50 Torr) with the Bruker IFS-125HR Fourier transform spectrometer (FTS) located at the Pacific Northwest National Laboratory (PNNL), in Richland, Washington. Over 840 Lorentz self-broadened half-width coefficients, 620 self-shift coefficients and 185 speed dependence parameters were measured. Line mixing was detected for transitions in the 2ν4, ν1 and ν3 bands, and their values were quantified for 10 A+A- pairs of transitions via off-diagonal relaxation matrix element formalism. The dependences of the measured half-width coefficients on the J and K rotational quanta of the transitions are discussed. The self-width coefficients for the ν1 and ν3 bands from this study are compared to the self-width coefficients for transitions with the same rotational quanta (J, K) reported for the Dyad (ν2 and ν4) bands. The measurements from present study should be useful for the development of a reliable theoretical modeling of pressure-broadened widths, shifts and line mixing in symmetric top molecules with C3v symmetry in general, and of PH3 in particular.

Line shape parameters of PH 3 transitions in the Pentad near 4–5 μm: Self-broadened widths, shifts, line mixing and speed dependence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malathy Devi, V.; Benner, D. C.; Kleiner, Isabelle

2014-08-01

Accurate knowledge of spectroscopic line parameters of PH 3 is important for remote sensing of the outer planets, especially Jupiter and Saturn. In a recent study, line positions and intensities for the Pentad bands of PH 3 have been reported from analysis of high-resolution, high signal-to noise room-temperature spectra recorded with two Fourier transform spectrometers (2014) [1]. The results presented in this study were obtained during the analysis of positions and intensities, but here we focus on the measurements of spectral line shapes (e.g. widths, shifts, line mixing) for the 2ν 4, ν 2 + ν 4, ν 1 andmore » ν 3 bands. A multispectrum nonlinear least squares curve fitting technique employing a non-Voigt line shape to include line mixing and speed dependence of the Lorentz width was employed to fit the spectra simultaneously. The least squares fittings were performed on five room-temperature spectra recorded at various PH 3 pressures (~2–50 Torr) with the Bruker IFS-125HR Fourier transform spectrometer (FTS) located at the Pacific Northwest National Laboratory (PNNL), in Richland, Washington. Over 840 Lorentz self-broadened half-width coefficients, 620 self-shift coefficients and 185 speed dependence parameters were measured. Line mixing was detected for transitions in the 2ν 4, ν 1 and ν 3 bands, and their values were quantified for 10 A+A- pairs of transitions via off-diagonal relaxation matrix element formalism. The dependences of the measured half-width coefficients on the J and K rotational quanta of the transitions are discussed. The self-width coefficients for the ν 1 and ν 3 bands from this study are compared to the self-width coefficients for transitions with the same rotational quanta (J, K) reported for the Dyad (ν 2 and ν 4) bands. The measurements from present study should be useful for the development of a reliable theoretical modeling of pressure-broadened widths, shifts and line mixing in symmetric top molecules with C 3v symmetry in general, and of PH 3 in particular.« less

Spectacle and SpecViz: New Spectral Analysis and Visualization Tools

NASA Astrophysics Data System (ADS)

Earl, Nicholas; Peeples, Molly; JDADF Developers

2018-01-01

A new era of spectroscopic exploration of our universe is being ushered in with advances in instrumentation and next-generation space telescopes. The advent of new spectroscopic instruments has highlighted a pressing need for tools scientists can use to analyze and explore these new data. We have developed Spectacle, a software package for analyzing both synthetic spectra from hydrodynamic simulations as well as real COS data with an aim of characterizing the behavior of the circumgalactic medium. It allows easy reduction of spectral data and analytic line generation capabilities. Currently, the package is focused on automatic determination of absorption regions and line identification with custom line list support, simultaneous line fitting using Voigt profiles via least-squares or MCMC methods, and multi-component modeling of blended features. Non-parametric measurements, such as equivalent widths, delta v90, and full-width half-max are available. Spectacle also provides the ability to compose compound models used to generate synthetic spectra allowing the user to define various LSF kernels, uncertainties, and to specify sampling.We also present updates to the visualization tool SpecViz, developed in conjunction with the JWST data analysis tools development team, to aid in the exploration of spectral data. SpecViz is an open source, Python-based spectral 1-D interactive visualization and analysis application built around high-performance interactive plotting. It supports handling general and instrument-specific data and includes advanced tool-sets for filtering and detrending one-dimensional data, along with the ability to isolate absorption regions using slicing and manipulate spectral features via spectral arithmetic. Multi-component modeling is also possible using a flexible model fitting tool-set that supports custom models to be used with various fitting routines. It also features robust user extensions such as custom data loaders and support for user-created plugins that add new functionality.This work was supported in part by HST AR #13919, HST GO #14268, and HST AR #14560.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phillion, D.

This code enables one to display, take line-outs on, and perform various transformations on an image created by an array of integer*2 data. Uncompressed eight-bit TIFF files created on either the Macintosh or the IBM PC may also be read in and converted to a 16 bit signed integer image. This code is designed to handle all the formats used for PDS (photo-densitometer) files at the Lawrence Livermore National Laboratory. These formats are all explained by the application code. The image may be zoomed infinitely and the gray scale mapping can be easily changed. Line-outs may be horizontal or verticalmore » with arbitrary width, angled with arbitrary end points, or taken along any path. This code is usually used to examine spectrograph data. Spectral lines may be identified and a polynomial fit from position to wavelength may be found. The image array can be remapped so that the pixels all have the same change of lambda width. It is not necessary to do this, however. Lineouts may be printed, saved as Cricket tab-delimited files, or saved as PICT2 files. The plots may be linear, semilog, or logarithmic with nice values and proper scientific notation. Typically, spectral lines are curved.« less

Evidence for high-altitude haze thickening on the dark side of Venus from 10-micron heterodyne spectroscopy of CO2

NASA Technical Reports Server (NTRS)

Deming, D.; Espenak, F.; Jennings, D.; Kostiuk, T.; Mumma, M.

1982-01-01

Infrared heterodyne spectroscopy provides data for isolated spectral lines with a spectral resolution which is small compared to the Doppler width. Heterodyne spectroscopy of CO2 lines near 10 micrometers was first reported for the atmosphere of Venus by Betz et al. (1976). The present investigation is concerned with observations of two absorption lines of (C-12)(O-16)2 conducted with an infrared heterodyne spectrometer interfaced with a solar telescope. The 10.8598-micrometer P(44) line was observed on the day side of Venus and the 10.3337-micrometer R(8) line was observed on the night side. It is shown that continuous opacity due to haze, and possible departures from vibrational LTE in CO2, are crucial considerations in fitting the observed lines.

Development and applications of tunable, narrow band lasers and stimulated Raman scattering devices for atmospheric lidar

NASA Technical Reports Server (NTRS)

Wilkerson, Thomas D.

1993-01-01

The main thrust of the program was the study of stimulated Raman processes for application to atmospheric lidar measurements. This has involved the development of tunable lasers, the detailed study of stimulated Raman scattering, and the use of the Raman-shifted light for new measurements of molecular line strengths and line widths. The principal spectral region explored in this work was the visible and near-IR wavelengths between 500 nm and 1.5 microns. Recent alexandrite ring laser experiments are reported. The experiments involved diode injection-locking, Raman shifting, and frequency-doubling. The experiments succeeded in producing tunable light at 577 and 937 nm with line widths in the range 80-160 MHz.

Magnetic fluorescent lamp having reduced ultraviolet self-absorption

DOEpatents

Berman, Samuel M.; Richardson, Robert W.

1985-01-01

The radiant emission of a mercury-argon discharge in a fluorescent lamp assembly (10) is enhanced by providing means (30) for establishing a magnetic field with lines of force along the path of electron flow through the bulb (12) of the lamp assembly, to provide Zeeman splitting of the ultraviolet spectral line. Optimum results are obtained when the magnetic field strength causes a Zeeman splitting of approximately 1.7 times the thermal line width.

A line parameter list for the nu2 and nu4 bands of /C-12/H4 and /C-13/H4, extended to J-prime = 25 and its application to planetary atmospheres

NASA Technical Reports Server (NTRS)

Orton, G. S.; Robiette, A. G.

1980-01-01

Line parameters (transition frequencies, line strengths, line widths, ground state energies and quantum identifications) for the nu2 and nu4 bands of (C-12)H4 and (C-13)H4 have been calculated for J-prime equal to or less than 25 using the simultaneous coupled fitting procedure of Gray and Robiette. Molecular constants for the nu2 band of (C-13)H4 were estimated from isotopic shifts from (C-12)H4 values. Agreement with laboratory spectra, where available, is always well within 1 kayser over the entire spectral range covered by the list. The most serious problem in comparison with laboratory data is the omission of lines belonging to 'hot' bands in this spectral region. This list is valuable in remote sensing problems for sorting out lines of trace species from weak methane lines and for determining the atmospheric opacity in relatively transparent spectral regions. Applications of the parameter list are demonstrated for remote sounding of the Jovian atmosphere.

Stark parameter dependence of the rest core charge of the emitters for multiply charged ions spectral lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Šćepanović, M., E-mail: mara.scepanovic@gmail.com; Purić, J.

2016-03-25

Stark width and shift simultaneous dependence on the upper level ionization potential and rest core charge of the emitter has been evaluated and discussed. It has been verified that the found relations, connecting Stark broadening parameters with upper level ionization potential and rest core charge of the emitters for particular electron temperature and density, can be used for prediction of Stark line width and shift data in case of ions for which observed data, or more detailed calculations, are not yet available. Stark widths and shifts published data are used to demonstrate the existence of other kinds of regularities withinmore » similar spectra of different elements and their ionization stages. The emphasis is on the Stark parameter dependence on the upper level ionization potential and on the rest core charge for the lines from similar spectra of multiply charged ions. The found relations connecting Stark widths and shift parameters with upper level ionization potential, rest core charge and electron temperature were used for a prediction of new Stark broadening data, thus avoiding much more complicated procedures.« less

Laser plasma x-ray line spectra fitted using the Pearson VII function

NASA Astrophysics Data System (ADS)

Michette, A. G.; Pfauntsch, S. J.

2000-05-01

The Pearson VII function, which is more general than the Gaussian, Lorentzian and other profiles, is used to fit the x-ray spectral lines produced in a laser-generated plasma, instead of the more usual, but computationally expensive, Voigt function. The mean full-width half-maximum of the fitted lines is 0.102+/-0.014 nm, entirely consistent with the value expected from geometrical considerations, and the fitted line profiles are generally inconsistent with being either Lorentzian or Gaussian.

A Solar-flux Line-broadening Analysis

NASA Astrophysics Data System (ADS)

Gray, David F.

2018-04-01

The Fourier technique of extracting rotation rates and macroturbulence-velocity dispersions from the shapes and broadening of stellar spectral lines is applied to the solar-flux spectrum. Lines with equivalent widths less than ∼0.055 Å are shown to have the advantage over stronger lines by allowing the residual transform to be followed to higher frequencies. The standard radial-tangential macroturbulence formulation fits the observations well and yields an equatorial velocity that is within a few percent of the correct rate.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phillion, D.

This code enables one to display, take line-outs on, and perform various transformations on an image created by an array of integer*2 data. Uncompressed eight-bit TIFF files created on either the Macintosh or the IBM PC may also be read in and converted to a 16 bit signed integer image. This code is designed to handle all the formates used for PDS (photo-densitometer) files at the Lawrence Livermore National Laboratory. These formats are all explained by the application code. The image may be zoomed infinitely and the gray scale mapping can be easily changed. Line-outs may be horizontal or verticalmore » with arbitrary width, angled with arbitrary end points, or taken along any path. This code is usually used to examine spectrograph data. Spectral lines may be identified and a polynomial fit from position to wavelength may be found. The image array can be remapped so that the pixels all have the same change of lambda width. It is not necessary to do this, however. Lineouts may be printed, saved as Cricket tab-delimited files, or saved as PICT2 files. The plots may be linear, semilog, or logarithmic with nice values and proper scientific notation. Typically, spectral lines are curved. By identifying points on these lines and fitting their shapes by polyn.« less

Results of Detailed Modeling of the Narrow-Line Region of Seyfert Galaxies

NASA Technical Reports Server (NTRS)

Moore, David; Cohen, Ross D.

1996-01-01

We present model line profiles of [O II] lambda3727, [Ne III] lambda3869, [O I] lambda5007, [Fe VII] lambda6087, [Fe X] lambda6374, [O I] lambda6300, H(alpha) lambda6563, and [S 2] lambda6731. The profiles presented here illustrate explicitly the pronounced effects that collisional de-excitation, and that spatial variations in both the ionization parameter and cloud column density, have on Narrow-Line Region (NLR) model profiles. The above effects were included only qualitatively in a previous analytical treatment by Moore and Cohen. By making a direct correspondence between these model profiles and the analytical model profiles of Moore and Cohen, and by comparing with the observed profiles presented in a companion paper and also with those presented elsewhere in the literature, we strengthen some of the conclusions of Moore and Cohen. Most notably, we argue for constant ionization parameter, uniformly accelerated outflow of clouds that are individually stratified in ionization, and the interpretation of emission-line width correlations with ionization potential as a column density effect. For comparison with previous observational studies, such as our own in a companion paper, we also calculate profile parameters for some of the models, and we present and discuss the resulting line width correlations with critical density (n(sub cr)) and Ionization Potential (IP). Because the models we favor are those that produce extended profile wings as observed in high spectral resolution studies, the line width correlations of our favoured models are of particular interest. Line width correlations with n(sub cr) and/or IP result only if the width parameter is more sensitive to extended profile wings than is the Full Width at Half-Maximum (FWHM). Correlations between FWHM and n(sub cr) and/or IP result only after convolving the model profiles with a broad instrumental profile that simulates the lower spectral resolution used in early observational studies. The model in agreement with the greatest number of observational considerations has electron density decreasing outward from n(sub e) approx. equals 10(exp 6)/cu cm to n(sub e) approx. equals 10(exp 2)/cu cm and, due to collisional de-excitation effects in the lowest velocity clouds, it generates broad flat-topped profile peaks in the lines of lowest critical density (e.g., [O II] lambda3727 and [S II] lambda(lambda)6716, 6731). Because the observed profile peaks of both low and high critical density lines are often very similar, our favored model requires a contribution to NLR emission-line spectra from low-velocity, low-density, and low-ionization gas not included in the model NLR.

Ultraviolet photometry from the orbiting astronomical observatory. XVI - The stellar Lyman-alpha absorption line

NASA Technical Reports Server (NTRS)

Savage, B. D.; Panek, R. J.

1974-01-01

The stellar Lyman-alpha line at 1216 A was observed in 29 lightly reddened stars of spectral type B2.5 to B9 by a far-UV spectrophotometer on OAO-2. The equivalent widths obtained range from 15 A at type B2.5 to 65 A at type B8; in the late-B stars, the L-alpha line removes 2 to 3% of the total stellar flux. In this sampling, the strength of the L-alpha line correlates well with measures of the Balmer discontinuity and Balmer line strengths; luminosity classification does not seem to affect the line strength. The observed line widths also agree with the predictions of Mihala's grid of non-LTE model atmospheres. In some cases, the L-alpha line influences the interstellar column densities reported in the interstellar OAO-2 L-alpha survey. Hence, these data toward lightly reddened B2 and B1.5 stars should be regarded as upper limits only.

Rocket-Plume Spectroscopy Simulation for Hydrocarbon-Fueled Rocket Engines

NASA Technical Reports Server (NTRS)

Tejwani, Gopal D.

2010-01-01

The UV-Vis spectroscopic system for plume diagnostics monitors rocket engine health by using several analytical tools developed at Stennis Space Center (SSC), including the rocket plume spectroscopy simulation code (RPSSC), to identify and quantify the alloys from the metallic elements observed in engine plumes. Because the hydrocarbon-fueled rocket engine is likely to contain C2, CO, CH, CN, and NO in addition to OH and H2O, the relevant electronic bands of these molecules in the spectral range of 300 to 850 nm in the RPSSC have been included. SSC incorporated several enhancements and modifications to the original line-by-line spectral simulation computer program implemented for plume spectral data analysis and quantification in 1994. These changes made the program applicable to the Space Shuttle Main Engine (SSME) and the Diagnostic Testbed Facility Thruster (DTFT) exhaust plume spectral data. Modifications included updating the molecular and spectral parameters for OH, adding spectral parameter input files optimized for the 10 elements of interest in the spectral range from 320 to 430 nm and linking the output to graphing and analysis packages. Additionally, the ability to handle the non-uniform wavelength interval at which the spectral computations are made was added. This allowed a precise superposition of wavelengths at which the spectral measurements have been made with the wavelengths at which the spectral computations are done by using the line-by-line (LBL) code. To account for hydrocarbon combustion products in the plume, which might interfere with detection and quantification of metallic elements in the spectral region of 300 to 850 nm, the spectroscopic code has been enhanced to include the carbon-based combustion species of C2, CO, and CH. In addition, CN and NO have spectral bands in 300 to 850 nm and, while these molecules are not direct products of hydrocarbon-oxygen combustion systems, they can show up if nitrogen or a nitrogen compound is present as an impurity in the propellants and/or these can form in the boundary layer as a result of interaction of the hot plume with the atmosphere during the ground testing of engines. Ten additional electronic band systems of these five molecules have been included into the code. A comprehensive literature search was conducted to obtain the most accurate values for the molecular and the spectral parameters, including Franck-Cordon factors and electronic transition moments for all ten band systems. For each elemental transition in the RPSSC, six spectral parameters - Doppler broadened line width at half-height, pressure-broadened line width at half-height, electronic multiplicity of the upper state, electronic term energy of the upper state, Einstein transition probability coefficient, and the atomic line center - are required. Input files have been created for ten elements of Ni, Fe, Cr, Co, Cu, Ca, Mn, Al, Ag, and Pd, which retain only relatively moderate to strong transitions in 300 to 430 nm spectral range for each element. The number of transitions in the input files is 68 for Ni; 148 for Fe; 6 for Cr; 87 for Co; 1 for Ca; 3 for Mn; 2 each for Cu, Al, and Ag; and 11 for Pd.

Time scale variation of NV resonance line profiles of HD203064

NASA Astrophysics Data System (ADS)

Strantzalis, A.

2012-01-01

Hot emission star, such as Be and Oe, present many spectral lines with very complex and peculiar profiles. Therefore, we cannot find a classical distribution to fit theoretically those physical line profiles. So, many physical parameters of the regions, where spectral lines are created, are difficult to estimate. Here, in this poster paper we study the UV NV (λλ 1238.821, 1242.804 A) resonance lines of the Be star HD203064 at three different dates. We using the Gauss-Rotation model, that proposed the idea that these complex profiles consist of a number of independent Discrete or Satellite Absorption Components (DACs, SACs). Our purpose is to calculate the values of a group of physical parameters as the apparent rotational, radial, and random velocities of the thermal motions of the ions. Also the Full Width at Half Maximum (FWHM) and the column density, as well as the absorbed energy of the independent regions of matter, which produce the main and the satellite components of the studied spectral lines. In addition, we determine the time scale variations of the above physical parameters.

Controlling pulse delay by light and low magnetic fields: slow light in emerald induced by transient spectral hole-burning.

PubMed

Rajan, Rajitha Papukutty; Riesen, Hans; Rebane, Aleksander

2013-11-15

Slow light based on transient spectral hole-burning is reported for emerald, Be(3)Al(2)Si(6)O(18):Cr(3+). Experiments were conducted in π polarization on the R(1)(± 3/2) line (E2 ← A(2)4) at 2.2 K in zero field and low magnetic fields B||c. The hole width was strongly dependent on B||c, and this allowed us to smoothly tune the pulse delay from 40 to 154 ns between zero field and B||c = 15.2 mT. The latter corresponds to a group velocity of 16 km/s. Slow light in conjunction with a linear filter theory can be used as a powerful and accurate technique in time-resolved spectroscopy, e.g., to determine spectral hole-widths as a function of time.

MONTE CARLO SIMULATION OF METASTABLE OXYGEN PHOTOCHEMISTRY IN COMETARY ATMOSPHERES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bisikalo, D. V.; Shematovich, V. I.; Gérard, J.-C.

2015-01-01

Cometary atmospheres are produced by the outgassing of material, mainly H{sub 2}O, CO, and CO{sub 2} from the nucleus of the comet under the energy input from the Sun. Subsequent photochemical processes lead to the production of other species generally absent from the nucleus, such as OH. Although all comets are different, they all have a highly rarefied atmosphere, which is an ideal environment for nonthermal photochemical processes to take place and influence the detailed state of the atmosphere. We develop a Monte Carlo model of the coma photochemistry. We compute the energy distribution functions (EDF) of the metastable O({supmore » 1}D) and O({sup 1}S) species and obtain the red (630 nm) and green (557.7 nm) spectral line shapes of the full coma, consistent with the computed EDFs and the expansion velocity. We show that both species have a severely non-Maxwellian EDF, that results in broad spectral lines and the suprathermal broadening dominates due to the expansion motion. We apply our model to the atmosphere of comet C/1996 B2 (Hyakutake) and 103P/Hartley 2. The computed width of the green line, expressed in terms of speed, is lower than that of the red line. This result is comparable to previous theoretical analyses, but in disagreement with observations. We explain that the spectral line shape does not only depend on the exothermicity of the photochemical production mechanisms, but also on thermalization, due to elastic collisions, reducing the width of the emission line coming from the O({sup 1}D) level, which has a longer lifetime.« less

SPECTRAL SMILE CORRECTION IN CRISM HYPERSPECTRAL IMAGES

NASA Astrophysics Data System (ADS)

Ceamanos, X.; Doute, S.

2009-12-01

The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is affected by a common artifact in "push-broom" sensors, the so-called "spectral smile". As a consequence, both central wavelength and spectral width of the spectral response vary along the across-track dimension, thus giving rise to a shifting and smoothing of spectra (see Fig. 1 (left)). In fact, both effects are greater for spectra on the edges, while they are minimum for data acquired by central detectors, the so-called "sweet spot". The prior artifacts become particularly critical for Martian observations which contain steep spectra such as CO2 ice-rich polar images. Fig. 1 (right) shows the horizontal brightness gradient which appears in every band corresponding to a steep portion of spectra. The correction of CRISM spectral smile is addressed using a two-step method which aims at modifying data sensibly in order to mimic the optimal CRISM response. First, all spectra, which are previously interpolated by cubic splines, are resampled to the "sweet spot" wavelengths in order to overcome the spectra shift. Secondly, the non-uniform spectral width is overcome by mimicking an increase of spectral resolution thanks to a spectral sharpening. In order to minimize noise, only bands particularly suffering from smile are selected. First, bands corresponding to the outliers of the Minimum Noise Transformation (MNF) eigenvector, which corresponds to the MNF band related to smile (MNF-smile), are selected. Then, a spectral neighborhood Θi, which takes into account the local spectral convexity or concavity, is defined for every selected band in order to maximize spectral shape preservation. The proposed sharpening technique takes into account both the instrument parameters and the observed spectra. First, every reflectance value belonging to a Θi is reevaluated by a sharpening which depends on a ratio of the spectral width of the current detector and the "sweet spot" one. Then, the optimal degree of sharpening for every Θi is determined thanks to a loop of sharpening procedures, which is assessed by the examination of an estimation of the smile energy (the MNF-smile eigenvalue). As a matter of fact, a higher sharpening is performed on Θi as long as the smile energy decreases. Experiments on CRISM data show remarkable results regarding the decrease of smile energy (up to 80%) and the spectral shape preservation. In fact, initial smile-affected spectra do no longer show shifting nor smoothing (see Fig. 2). Line-averaged spectra and band 155 of FRT5AE3_07 showing spectral smile effects Line-averaged spectra and band 155 of smile-corrected FRT5AE3_07

Wavelength stabilized multi-kW diode laser systems

NASA Astrophysics Data System (ADS)

Köhler, Bernd; Unger, Andreas; Kindervater, Tobias; Drovs, Simon; Wolf, Paul; Hubrich, Ralf; Beczkowiak, Anna; Auch, Stefan; Müntz, Holger; Biesenbach, Jens

2015-03-01

We report on wavelength stabilized high-power diode laser systems with enhanced spectral brightness by means of Volume Holographic Gratings. High-power diode laser modules typically have a relatively broad spectral width of about 3 to 6 nm. In addition the center wavelength shifts by changing the temperature and the driving current, which is obstructive for pumping applications with small absorption bandwidths. Wavelength stabilization of high-power diode laser systems is an important method to increase the efficiency of diode pumped solid-state lasers. It also enables power scaling by dense wavelength multiplexing. To ensure a wide locking range and efficient wavelength stabilization the parameters of the Volume Holographic Grating and the parameters of the diode laser bar have to be adapted carefully. Important parameters are the reflectivity of the Volume Holographic Grating, the reflectivity of the diode laser bar as well as its angular and spectral emission characteristics. In this paper we present detailed data on wavelength stabilized diode laser systems with and without fiber coupling in the spectral range from 634 nm up to 1533 nm. The maximum output power of 2.7 kW was measured for a fiber coupled system (1000 μm, NA 0.22), which was stabilized at a wavelength of 969 nm with a spectral width of only 0.6 nm (90% value). Another example is a narrow line-width diode laser stack, which was stabilized at a wavelength of 1533 nm with a spectral bandwidth below 1 nm and an output power of 835 W.

1H line width dependence on MAS speed in solid state NMR - Comparison of experiment and simulation

NASA Astrophysics Data System (ADS)

Sternberg, Ulrich; Witter, Raiker; Kuprov, Ilya; Lamley, Jonathan M.; Oss, Andres; Lewandowski, Józef R.; Samoson, Ago

2018-06-01

Recent developments in magic angle spinning (MAS) technology permit spinning frequencies of ≥100 kHz. We examine the effect of such fast MAS rates upon nuclear magnetic resonance proton line widths in the multi-spin system of β-Asp-Ala crystal. We perform powder pattern simulations employing Fokker-Plank approach with periodic boundary conditions and 1H-chemical shift tensors calculated using the bond polarization theory. The theoretical predictions mirror well the experimental results. Both approaches demonstrate that homogeneous broadening has a linear-quadratic dependency on the inverse of the MAS spinning frequency and that, at the faster end of the spinning frequencies, the residual spectral line broadening becomes dominated by chemical shift distributions and susceptibility effects even for crystalline systems.

The relaxation matrix for symmetric tops with inversion symmetry. I. Effects of line coupling on self-broadened ν1 and pure rotational bands of NH3.

PubMed

Ma, Q; Boulet, C

2016-06-14

The Robert-Bonamy formalism has been commonly used to calculate half-widths and shifts of spectral lines for decades. This formalism is based on several approximations. Among them, two have not been fully addressed: the isolated line approximation and the neglect of coupling between the translational and internal motions. Recently, we have shown that the isolated line approximation is not necessary in developing semi-classical line shape theories. Based on this progress, we have been able to develop a new formalism that enables not only to reduce uncertainties on calculated half-widths and shifts, but also to model line mixing effects on spectra starting from the knowledge of the intermolecular potential. In our previous studies, the new formalism had been applied to linear and asymmetric-top molecules. In the present study, the method has been extended to symmetric-top molecules with inversion symmetry. As expected, the inversion splitting induces a complete failure of the isolated line approximation. We have calculated the complex relaxation matrices of self-broadened NH3. The half-widths and shifts in the ν1 and the pure rotational bands are reported in the present paper. When compared with measurements, the calculated half-widths match the experimental data very well, since the inapplicable isolated line approximation has been removed. With respect to the shifts, only qualitative results are obtained and discussed. Calculated off-diagonal elements of the relaxation matrix and a comparison with the observed line mixing effects are reported in the companion paper (Paper II).

The Relaxation Matrix for Symmetric Tops with Inversion Symmetry. I. Effects of Line Coupling on Self-Broadened v (sub 1) and Pure Rotational Bands of NH3

NASA Technical Reports Server (NTRS)

Ma, Q.; Boulet, C.

2016-01-01

The Robert-Bonamy formalism has been commonly used to calculate half-widths and shifts of spectral lines for decades. This formalism is based on several approximations. Among them, two have not been fully addressed: the isolated line approximation and the neglect of coupling between the translational and internal motions. Recently, we have shown that the isolated line approximation is not necessary in developing semi-classical line shape theories. Based on this progress, we have been able to develop a new formalism that enables not only to reduce uncertainties on calculated half-widths and shifts, but also to model line mixing effects on spectra starting from the knowledge of the intermolecular potential. In our previous studies, the new formalism had been applied to linear and asymmetric-top molecules. In the present study, the method has been extended to symmetric-top molecules with inversion symmetry. As expected, the inversion splitting induces a complete failure of the isolated line approximation. We have calculated the complex relaxation matrices of selfbroadened NH3. The half-widths and shifts in the ?1 and the pure rotational bands are reported in the present paper. When compared with measurements, the calculated half-widths match the experimental data very well, since the inapplicable isolated line approximation has been removed. With respect to the shifts, only qualitative results are obtained and discussed. Calculated off-diagonal elements of the relaxation matrix and a comparison with the observed line mixing effects are reported in the companion paper (Paper II).

Voigt deconvolution method and its applications to pure oxygen absorption spectrum at 1270 nm band.

PubMed

Al-Jalali, Muhammad A; Aljghami, Issam F; Mahzia, Yahia M

2016-03-15

Experimental spectral lines of pure oxygen at 1270 nm band were analyzed by Voigt deconvolution method. The method gave a total Voigt profile, which arises from two overlapping bands. Deconvolution of total Voigt profile leads to two Voigt profiles, the first as a result of O2 dimol at 1264 nm band envelope, and the second from O2 monomer at 1268 nm band envelope. In addition, Voigt profile itself is the convolution of Lorentzian and Gaussian distributions. Competition between thermal and collisional effects was clearly observed through competition between Gaussian and Lorentzian width for each band envelope. Voigt full width at half-maximum height (Voigt FWHM) for each line, and the width ratio between Lorentzian and Gaussian width (ΓLΓG(-1)) have been investigated. The following applied pressures were at 1, 2, 3, 4, 5, and 8 bar, while the temperatures were at 298 K, 323 K, 348 K, and 373 K range. Copyright © 2015 Elsevier B.V. All rights reserved.

Stark width and shift for electron number density diagnostics of low temperature plasma: Application to silicon Laser Induced Breakdown Spectroscopy

NASA Astrophysics Data System (ADS)

Ivković, M.; Konjević, N.

2017-05-01

In this work we summarize, analyze and critically evaluate experimental procedures and results of LIBS electron number density plasma characterization using as examples Stark broadened Si I and Si II line profiles. Selected publications are covering the time period from very beginning of silicon LIBS studies until the end of the year 2015. To perform the analysis of experimental LIBS data, the testing of available semiclassical theoretical Stark broadening parameters for Si I and Si II lines was accomplished first. This is followed by the description of experimental setups, results and details of experimental procedure relevant for the line shape analysis of spectral lines used for plasma characterization. Although most of results and conclusions of this analysis are related to the application of silicon lines for LIBS characterization they are of general importance and may be applied to other elements and different low-temperature plasma sources. The analysis of experimental procedures used for LIBS diagnostics from emission profiles of non-hydrogenic spectral lines is carried out in the following order: the influence of laser ablation and crater formation, spatial and temporal plasma observation, line self-absorption and experimental profile deconvolution, the contribution of ion broadening in comparison with electron impacts contributions to the line width in case of neutral atom line and some other aspects of line shape analysis are considered. The application of Stark shift for LIBS diagnostics is demonstrated and discussed. Finally, the recommendations for an improvement of experimental procedures for LIBS electron number density plasma characterization are offered.

Relativistic quantum mechanical calculations of electron-impact broadening for spectral lines in Be-like ions

NASA Astrophysics Data System (ADS)

Duan, B.; Bari, M. A.; Wu, Z. Q.; Jun, Y.; Li, Y. M.; Wang, J. G.

2012-11-01

Aims: We present relativistic quantum mechanical calculations of electron-impact broadening of the singlet and triplet transition 2s3s ← 2s3p in four Be-like ions from N IV to Ne VII. Methods: In our theoretical calculations, the K-matrix and related symmetry information determined by the colliding systems are generated by the DARC codes. Results: A careful comparison between our calculations and experimental results shows good agreement. Our calculated widths of spectral lines also agree with earlier theoretical results. Our investigations provide new methods of calculating electron-impact broadening parameters for plasma diagnostics.

Application of CRAFT in two-dimensional NMR data processing.

PubMed

Krishnamurthy, Krish; Sefler, Andrea M; Russell, David J

2017-03-01

Two-dimensional (2D) data are typically truncated in both dimensions, but invariably and severely so in the indirect dimension. These truncated FIDs and/or interferograms are extensively zero filled, and Fourier transformation of such zero-filled data is always preceded by a rapidly decaying apodization function. Hence, the frequency line width in the spectrum (at least parallel to the evolution dimension) is almost always dominated by the apodization function. Such apodization-driven line broadening in the indirect (t 1 ) dimension leads to the lack of clear resolution of cross peaks in the 2D spectrum. Time-domain analysis (i.e. extraction of frequency, amplitudes, line width, and phase parameters directly from the FID, in this case via Bayesian modeling into a tabular format) of NMR data is another approach for spectral resonance characterization and quantification. The recently published complete reduction to amplitude frequency table (CRAFT) technique converts the raw FID data (i.e. time-domain data) into a table of frequencies, amplitudes, decay rate constants, and phases. CRAFT analyses of time-domain data require minimal or no apodization prior to extraction of the four parameters. We used the CRAFT processing approach for the decimation of the interferograms and compared the results from a variety of 2D spectra against conventional processing with and without linear prediction. The results show that use of the CRAFT technique to decimate the t 1 interferograms yields much narrower spectral line width of the resonances, circumventing the loss of resolution due to apodization. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

PCF based high power narrow line width pulsed fiber laser

NASA Astrophysics Data System (ADS)

Chen, H.; Yan, P.; Xiao, Q.; Wang, Y.; Gong, M.

2012-09-01

Based on semiconductor diode seeded multi-stage cascaded fiber amplifiers, we have obtained 88-W average power of a 1063-nm laser with high repetition rate of up to 1.5 MHz and a constant 2-ns pulse duration. No stimulated Brillouin scattering pulse or optical damage occurred although the maximum pulse peak power has exceeded 112 kW. The output laser exhibits excellent beam quality (M2x = 1.24 and M2y = 1.18), associated with a spectral line width as narrow as 0.065 nm (FWHM). Additionally, we demonstrate high polarization extinction ratio of 18.4 dB and good pulse stabilities superior to 1.6 % (RMS).

Ultraviolet to optical spectral distributions of northern star-forming galaxies

NASA Technical Reports Server (NTRS)

Mcquade, Kerry; Calzetti, Daniela; Kinney, Anne L.

1995-01-01

We report spectral energy distribution from the UV to the optical for a sample of 31 northern star-forming galaxies. We also present measurements for emission-line fluxes, continuum levels, and equivalent widths of absorption features for each individual spectrum as well as averages for the eight galactic activity classes, including normal, starburst, Seyfert 2, blue compact dwarf, blue compact, Low-Inonization Nuclear Emission Regions (LINER), H II, and combination LINER-H II galaxies.

Statistical Investigation of Supersonic Downflows in the Transition Region above Sunspots

NASA Astrophysics Data System (ADS)

Samanta, Tanmoy; Tian, Hui; Prasad Choudhary, Debi

2018-06-01

Downflows at supersonic speeds have been observed in the transition region (TR) above sunspots for more than three decades. These downflows are often seen in different TR spectral lines above sunspots. We have performed a statistical investigation of these downflows using a large sample that was missing previously. The Interface Region Imaging Spectrograph (IRIS) has provided a wealth of observational data of sunspots at high spatial and spectral resolutions in the past few years. We have identified 60 data sets obtained with IRIS raster scans. Using an automated code, we identified the locations of strong downflows within these sunspots. We found that around 80% of our sample shows supersonic downflows in the Si IV 1403 Å line. These downflows mostly appear in the penumbral regions, though some of them are found in the umbrae. We also found that almost half of these downflows show signatures in chromospheric lines. Furthermore, a detailed spectral analysis was performed by selecting a small spectral window containing the O IV 1400/1401 Å and Si IV 1403 Å lines. Six Gaussian functions were simultaneously fitted to these three spectral lines and their satellite lines associated with the supersonic downflows. We calculated the intensity, Doppler velocity, and line width for these lines. Using the O IV 1400/1401 Å line ratio, we find that the downflow components are around one order of magnitude less dense than the regular components. Results from our statistical analysis suggest that these downflows may originate from the corona and that they are independent of the background TR plasma.

Measurements of resonant scattering in the Perseus cluster core with Hitomi SXS

NASA Astrophysics Data System (ADS)

Sato, K.; Zhuravleva, I.

2017-10-01

Hitomi (ASTRO-H) SXS allows us to investigate fine structures of emission lines in extended X-ray sources for the first time. Thanks to its high energy resolution of 5 eV at 6 keV in orbit, Hitomi SXS finds a quiescent atmosphere in the Intra cluster medium of the Perseus cluster core where the gas has a line-of-sight velocity dispersion below 200 km/sec from the line width in the spectral analysis (Hitomi collaboration, Nature, 2016). The resonant scattering is also important to measure the gas velocity as a complementary probe of the direct measurement from the line width. Particularly in the cluster core, resonant scattering should be taken into account when inferring physical properties from line intensities because the optical depth of the He-alpha resonant line is expected to be larger than 1. The observed line flux ratio of Fe XXV He-α resonant to forbidden lines is found to be lower in the cluster core when compared to the outer region, consistent with resonant scattering of the resonant line and also in support of the low turbulent velocity.

VizieR Online Data Catalog: Spectroscopic survey of youngest field stars II. (Frasca+, 2018)

NASA Astrophysics Data System (ADS)

Frasca, A.; Guillout, P.; Klutsch, A.; Freire Ferrero, R.; Marilli, E.; Biazzo, K.; Gandolfi, D.; Montes, D.

2018-01-01

Radial velocity (RV) and projected rotational velocity (vsini) of the single stars and SB1 systems are quoted in Table A1 along with the V magnitude and B-V color index. The vsini values measured from the full width at half maximum of the of the cross-correlation function (CCF) and by means of the code ROTFIT are both listed in Table A1. Table A2 and A3 report RV and vsini from the CCF for the components of SB2 and triple (SB3) systems, respectively. Table A4 reports, for the single stars and SB1 systems, the spectral type, atmospheric parameters (Teff, logg, and [Fe/H]), the equivalent width of the lithium 6708-A line (corrected for the FeI blends) and the net equivalent width of Hα line, measured after the subtraction of the inactive photospheric template. (4 data files).

THE CONNECTIONS BETWEEN THE UV AND OPTICAL Fe ii EMISSION LINES IN TYPE 1 AGNs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kovacević-Dojcinović, Jelena; Popović, Luka Č., E-mail: jkovacevic@aob.bg.ac.rs, E-mail: lpopovic@aob.bg.ac.rs

We investigate the spectral properties of the UV (λλ2650–3050 Å) and optical (λλ4000–5500 Å) Fe ii emission features in a sample of 293 Type 1 active galactic nuclei (AGNs) from the Sloan Digital Sky Survey database. We explore different correlations between their emission line properties, as well as the correlations with other emission lines from the spectral range. We find several interesting correlations and outline the most interesting results as follows. (i) There is a kinematical connection between the UV and optical Fe ii lines, indicating that the UV and optical Fe ii lines originate from the outer part ofmore » the broad line region, the so-called intermediate line region. (ii) The unexplained anticorrelations of the optical Fe ii equivalent width (EW Fe ii{sub opt}) versus EW [O iii] 5007 Å and EW Fe ii{sub opt} versus FWHM Hβ have not been detected for the UV Fe ii lines. (iii) The significant averaged redshift in the UV Fe ii lines, which is not present in optical Fe ii, indicates an inflow in the UV Fe ii emitting clouds, and probably their asymmetric distribution. (iv) Also, we confirm the anticorrelation between the intensity ratio of the optical and UV Fe ii lines and the FWHM of Hβ, and we find the anticorrelations of this ratio with the widths of Mg ii 2800 Å, optical Fe ii, and UV Fe ii. This indicates a very important role for the column density and microturbulence in the emitting gas. We discuss the starburst activity in high-density regions of young AGNs as a possible explanation of the detected optical Fe ii correlations and intensity line ratios of the UV and optical Fe ii lines.« less

Eta Carinae across the 2003.5 Minimum: Analysis in the Visible and Near Infrared Spectral Region

NASA Technical Reports Server (NTRS)

Nielsen, K. E.; Kober, G. Vieira; Weis, K.; Gull, T.; Stahl, O.; Bomans, D. J.

2008-01-01

We present analysis of the visible through near infrared spectrum of eta Car and its ejecta obtained during the 'eta Car Campaign with the Ultraviolet Visual Echelle Spectrograph (UVES) at the ESO Very Large Telescope (VLT)'. This is a part of larger effort to present a complete eta Car spectrum, and extends the previously presented analyses with the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) in the UV (1240-3159 A) to 10,430 A. The spectrum in the mid and near UV is characterized by the ejecta absorption. At longer wavelengths, stellar wind features from the central source and narrow emission lines from the Weigelt condensations dominate the spectrum. However, narrow absorption lines from the circumstellar shells are present. This paper provides a description of the spectrum between 3060 and 10,430 A, including line identifications of the ejecta absorption spectrum, the emission spectrum from the Weigelt condensations and the P-Cygni stellar wind features. The high spectral resolving power of VLT/UVES enables equivalent width measurements of atomic and molecular absorption lines for elements with no transitions at the shorter wavelengths. However, the ground based seeing and contributions of nebular scattered radiation prevent direct comparison of measured equivalent widths in the VLT/UVES and HST/STIS spectra. Fortunately, HST/STIS and VLT/UVES have a small overlap in wavelength coverage which allows us to compare and adjust for the difference in scattered radiation entering the instruments apertures. This paper provide a complete online VLT/UVES spectrum with line identifications and a spectral comparison between HST/STIS and VLT/UVES between 3060 and 3160 A.

Eta Carinae across the 2003.5 Minimum: Analysis in the Visible and Near Infrared Spectral Region

NASA Technical Reports Server (NTRS)

Nielsen, K. E.; Kober, G. Vieira; Weis, K.; Gull, T. R.; Stahl, O.; Bomans, D. J.

2009-01-01

We present an analysis of the visible through near infrared spectrum of Eta Car and its ejecta obtained during the "Eta Car Campaign with the Ultraviolet and Visual Echelle Spectrograph (UVES) at the ESO Very Large Telescope (VLT)". This is a part of the larger effort to present a complete Eta Car spectrum, and extends the previously presented analyses with the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) in the UV (1240-3159 Angstrom) to 10,430 Angstrom. The spectrum in the mid and near UV is characterized by the ejecta absorption. At longer wavelengths, stellar wind features from the central source and narrow emission lines from the Weigelt condensations dominate the spectrum. However, narrow absorption lines from the circumstellar shells are present. This paper provides a description of the spectrum between 3060 and 10,430 Angstroms, including line identifications of the ejecta absorption spectrum, the emission spectrum from the Weigelt condensations and the P-Cygni stellar wind features. The high spectral resolving power of VLT/UVES enables equivalent width measurements of atomic and molecular absorption lines for elements with no transitions at the shorter wavelengths. However, the ground based seeing and contributions of nebular scattered radiation prevent direct comparison of measured equivalent widths in the VLT/UVES and HST/STIS spectra. Fortunately, HST/STIS and VLT/UVES have a small overlap in wavelength coverage which allows us to compare and adjust for the difference in scattered radiation entering the instruments' apertures. This paper provides a complete online VLT/UVES spectrum with line identifications and a spectral comparison between HST/STIS and VLT/UVES between 3060 and 3160 Angstroms.

Non-LTE, line-blanketed model atmospheres for late O- and early B-type stars

NASA Technical Reports Server (NTRS)

Grigsby, James A.; Morrison, Nancy D.; Anderson, Lawrence S.

1992-01-01

The use of non-LTE line-blanketed model atmospheres to analyze the spectra of hot stars is reported. The stars analyzed are members of clusters and associations, have spectral types in the range O9-B2 and luminosity classes in the range III-IV, have slow to moderate rotation, and are photometrically constant. Sampled line opacities of iron-group elements were incorporated in the radiative transfer solution; solar abundances were assumed. Good to excellent agreement is obtained between the computed profiles and essentially all the line profiles used to fix the model, and reliable stellar parameters are derived. The synthetic M II 5581 equivalent widths agree well with the observed ones at the low end of the temperature range studied, but, above 25,000 K, the synthetic line is generally stronger than the observed line. The behavior of the observed equivalent widths of N II, N III, C II and C III lines as a function of Teff is studied. Most of the lines show much scatter, with no consistent trend that could indicate abundance differences from star to star.

The Distance to the Coma Cluster from the Tully--Fisher Relation

NASA Astrophysics Data System (ADS)

Herter, T.; Vogt, N. P.; Haynes, M. P.; Giovanelli, R.

1993-12-01

As part of a survey to determine the distances to nearby (z < .04) Abell clusters via application of the Tully--Fisher (TF) relation, we have obtained 21 cm HI line widths, optical rotation curves and photometric I--band CCD images of galaxies within and near the Coma cluster. Because spiral galaxies within the cluster itself are HI deficient and thus are detected marginally or not at all in HI, distance determinations using only the radio TF relation exclude true cluster members. Our sample includes eight HI deficient galaxies within 1.5 degrees of the cluster center, for which optical velocity widths are derived from their Hα and [NII] rotation curves. The 21 cm line widths have been extracted using a new algorithm designed to optimize the measurement for TF applications, taking into account the effects of spectral resolution and smoothing. The optical width is constructed from the velocity histogram, and is therefore a global value akin to the HI width. A correction for turbulent broadening of the HI is derived from comparison of the optical and HI widths. Using a combined sample of 260 galaxies in 11 clusters and an additional 30 field objects at comparable distances, we have performed a calibration of the radio and optical analogs of the TF relation. Preliminary results show a clear linear relationship with a small offset between optical and radio widths, and good agreement in deriving Tully--Fisher distances to clusters. Our Coma sample consists of 28 galaxies with optical widths and 42 with HI line widths, with an overlapping set of 20 galaxies. We will present the data on the Coma cluster, and discuss the results of our analysis.

Extending the Calibration of C IV-based Single-epoch Black Hole Mass Estimators for Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Park, Daeseong; Barth, Aaron J.; Woo, Jong-Hak; Malkan, Matthew A.; Treu, Tommaso; Bennert, Vardha N.; Assef, Roberto J.; Pancoast, Anna

2017-04-01

We provide an updated calibration of C IV λ 1549 broad emission line–based single-epoch (SE) black hole (BH) mass estimators for active galactic nuclei (AGNs) using new data for six reverberation-mapped AGNs at redshift z=0.005{--}0.028 with BH masses (bolometric luminosities) in the range {10}6.5{--}{10}7.5 {M}ȯ ({10}41.7{--}{10}43.8 erg s‑1). New rest-frame UV-to-optical spectra covering 1150–5700 Å for the six AGNs were obtained with the Hubble Space Telescope (HST). Multicomponent spectral decompositions of the HST spectra were used to measure SE emission-line widths for the C IV, Mg II, and Hβ lines, as well as continuum luminosities in the spectral region around each line. We combine the new data with similar measurements for a previous archival sample of 25 AGNs to derive the most consistent and accurate calibrations of the C IV-based SE BH mass estimators against the Hβ reverberation-based masses, using three different measures of broad-line width: full width at half maximum (FWHM), line dispersion ({σ }line}), and mean absolute deviation (MAD). The newly expanded sample at redshift z=0.005{--}0.234 covers a dynamic range in BH mass (bolometric luminosity) of {log}{M}BH}/{M}ȯ =6.5{--}9.1 ({log}{L}bol}/ erg s‑1 = 41.7{--}46.9), and we derive the new C IV-based mass estimators using a Bayesian linear regression analysis over this range. We generally recommend the use of {σ }line} or MAD rather than FWHM to obtain a less biased velocity measurement of the C IV emission line, because its narrow-line component contribution is difficult to decompose from the broad-line profile. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO-12922.

Analysis of carbon dioxide bands near 2.2 micrometers

NASA Technical Reports Server (NTRS)

Abubaker, M. S.; Shaw, J. H.

1984-01-01

Carbon dioxide is one of the more important atmospheric infrared-absorbing gases due to its relatively high, and increasing, concentration. The spectral parameters of its bands are required for understanding radiative heat transfer in the atmosphere. The line intensities, positions, line half-widths, rotational constants, and band centers of three overlapping bands of CO2 near 2.2 microns are presented. Non-linear least squares (NLLS) regression procedures were employed to determine these parameters.

Slitless Solar Spectroscopy

NASA Technical Reports Server (NTRS)

Davila, Joseph M.; Jones, Sahela

2011-01-01

Spectrographs have traditionally suffered from the inability to obtain line intensities, widths, and Doppler shifts over large spatial regions of the Sun quickly because of the narrow instantaneous field of view. This has limited the spectroscopic analysis of rapidly varying solar features like, flares, CME eruptions, coronal jets, and reconnection regions. Imagers have provided high time resolution images of the full Sun with limited spectral resolution. In this paper we present recent advances in deconvolving spectrally dispersed images obtained through broad slits. We use this new theoretical formulation to examine the effectiveness of various potential observing scenarios, spatial and spectral resolutions, signal to noise ratio, and other instrument characteristics. This information will lay the foundation for a new generation of spectral imagers optimized for slitless spectral operation, while retaining the ability to obtain spectral information in transient solar events.

Redshifts of high-temperature emission lines in the far-ultraviolet spectra of late-type stars. II - New, precise measurements of dwarfs and giants

NASA Technical Reports Server (NTRS)

Ayres, Thomas R.; Jensen, Eberhard; Engvold, Oddbjorn

1988-01-01

Results are presented from an IUE SWP camera investigation of the occurrence of gasdynamic flows, analogous to the downdrafts of 10 to the 5th K material observed over magnetic active regions of the sun, among stars of late spectral type. The SWP calibration spectra study conducted documents the existence of local, small, persistent distortions of the echelle wavelength scales that are of unknown origin. Attention is given to the enormous widths of the stellar high-excitation emission lines in both the dwarfs and the giants, with respect to the comparatively small, subsonic Doppler shifts; the widths are typically an order of magnitude greater than the redshifts.

H2-broadening, shifting and mixing coefficients of the doublets in the ν2 and ν4 bands of PH3 at room temperature

NASA Astrophysics Data System (ADS)

Salem, Jamel; Blanquet, Ghislain; Lepère, Muriel; Younes, Rached ben

2018-05-01

The broadening, shifting and mixing coefficients of the doublet spectral lines in the ν2 and ν4 bands of PH3 perturbed by H2 have been determined at room temperature. Indeed, the collisional spectroscopic parameters: intensities, line widths, line shifts and line mixing parameters, are all grouped together in the collisional relaxation matrix. To analyse the collisional process and physical effects on spectra of phosphine (PH3), we have used the measurements carried out using a tunable diode-laser spectrometer in the ν2 and ν4 bands of PH3 perturbed by hydrogen (H2) at room temperature. The recorded spectra are fitted by the Voigt profile and the speed-dependent uncorrelated hard collision model of Rautian and Sobelman. These profiles are developed in the studies of isolated lines and are modified to account for the line mixing effects in the overlapping lines. The line widths, line shifts and line mixing parameters are given for six A1 and A2 doublet lines with quantum numbers K = 3n, (n = 1, 2, …) and overlapped by collisional broadening at pressures of less than 50 mbar.

Temperature Dependence of Wavelength Selectable Zero-Phonon Emission from Single Defects in Hexagonal Boron Nitride.

PubMed

Jungwirth, Nicholas R; Calderon, Brian; Ji, Yanxin; Spencer, Michael G; Flatté, Michael E; Fuchs, Gregory D

2016-10-12

We investigate the distribution and temperature-dependent optical properties of sharp, zero-phonon emission from defect-based single photon sources in multilayer hexagonal boron nitride (h-BN) flakes. We observe sharp emission lines from optically active defects distributed across an energy range that exceeds 500 meV. Spectrally resolved photon-correlation measurements verify single photon emission, even when multiple emission lines are simultaneously excited within the same h-BN flake. We also present a detailed study of the temperature-dependent line width, spectral energy shift, and intensity for two different zero-phonon lines centered at 575 and 682 nm, which reveals a nearly identical temperature dependence despite a large difference in transition energy. Our temperature-dependent results are well described by a lattice vibration model that considers piezoelectric coupling to in-plane phonons. Finally, polarization spectroscopy measurements suggest that whereas the 575 nm emission line is directly excited by 532 nm excitation, the 682 nm line is excited indirectly.

Spectroscopic Measurements of Collision-less Coupling Between Laser-Produced, Super-Alfvénic Debris Plasmas and Magnetized, Ambient Plasmas

NASA Astrophysics Data System (ADS)

Bondarenko, Anton; Everson, E.; Schaeffer, D.; Constantin, C.; Vincena, S.; Van Compernolle, B.; Clark, S.; Niemann, C.

2013-06-01

Emission spectroscopy is currently being utilized in order to assess collision-less momentum and energy coupling between super-Alfvénic debris plasmas and magnetized, ambient plasmas of astrophysical relevance. In a recent campaign on the Large Plasma Device (LAPD) utilizing the Phoenix laboratory Raptor laser (130 J, 25 ns FWHM), laser-ablated carbon debris plasmas were generated within magnetized, ambient helium plasmas (nelec ≈ 3×1012 cm-3, Telec ≈ 5.5 eV, B0 = 200 G), and prominent spectral lines of carbon and helium ions were studied in high resolution (˜ 0.01 nm). Time-resolved Doppler shift and width measurements of a C V ion spectral line reveal significant deceleration as the ions stream through the background plasma, which may indirectly indicate momentum coupling. Spectral lines of He II ions are observed to intensify by orders of magnitude and broaden, indicating energy transfer from the debris plasma to the background plasma.

Analysis of He I 1083 nm Imaging Spectroscopy Using a Spectral Standard

NASA Technical Reports Server (NTRS)

Malanushenko, Elena V.; Jones, Harrison P.

2004-01-01

We develop a technique. for the analysis of He I 1083 nanometer spectra which addresses several difficulties through determination of a continuum background by comparison with a well calibrated standard and through removal of nearby solar and telluric blends by differential comparison to an average spectrum. The method is compared with earlier analysis of imaging spectroscopy obtained at the National Solar Observatory/Kitt Peak Vacuum Telescope (NSO/KPVT) with the NASA/NSO Spectromagnetograph (SPM). We examine distributions of Doppler velocity and line width as a function of central intensity for an active region, filament, quiet Sun, and coronal hole. For our example, we find that line widths and central intensity are oppositely correlated in a coronal hole and quiet Sun. Line widths are comparable to the quiet sun in the active region, are systematically lower in the filament, and extend to higher values in the coronal hole. Outward velocities of approximately equal to 2 to 4 kilometers per second are typically observed in the coronal hole. The sensitivity of these results to analysis technique is discussed.

The chemical composition of the Lambda Bootis stars

NASA Technical Reports Server (NTRS)

Baschek, B.; Slettebak, A.

1988-01-01

Measurements of the equivalent widths of 24 ultraviolet lines from IUE spectra of 10 Lambda Bootis or suspected Lambda Bootis stars and 19 normal standard stars of spectral types B8-A7 have been compared with line strengths determined using model atmospheres. Abundance differences are estimated via a differential analysis technique. It is found that the ratio of C, N, and O to the heavier elements Mg to Ni is significantly larger than that for solar composition stars.

Spectral Analysis of the Accretion Flow in NGC 1052 with Suzaku

NASA Technical Reports Server (NTRS)

Brenneman, L. W.; Weaver, K. A.; Kadler, M.; Tueller, J.; Marscher, A.; Ros, E.; Zensus,A.; Kovalev, Y. Y.; Aller, M.; Aller, H.;

Effect of nearest-neighbor ions on excited ionic states, emission spectra, and line profiles in hot and dense plasmas

NASA Technical Reports Server (NTRS)

Salzmann, D.; Stein, J.; Goldberg, I. B.; Pratt, R. H.

1991-01-01

The effect of the cylindrical symmetry imposed by the nearest-neighbor ions on the ionic levels and the emission spectra of a Li-like Kr ion immersed in hot and dense plasmas is investigated using the Stein et al. (1989) two-centered model extended to include computations of the line profiles, shifts, and widths, as well as the energy-level mixing and the forbidden transition probabilities. It is shown that the cylindrical symmetry mixes states with different orbital quantum numbers l, particularly for highly excited states, and, thereby, gives rise to forbidden transitions in the emission spectrum. Results are obtained for the variation of the ionic level shifts and mixing coefficients with the distance to the nearest neighbor. Also obtained are representative computed spectra that show the density effects on the spectral line profiles, shifts, and widths, and the forbidden components in the spectrum.

Stimulated Electronic X-Ray Raman Scattering

NASA Astrophysics Data System (ADS)

Weninger, Clemens; Purvis, Michael; Ryan, Duncan; London, Richard A.; Bozek, John D.; Bostedt, Christoph; Graf, Alexander; Brown, Gregory; Rocca, Jorge J.; Rohringer, Nina

2013-12-01

We demonstrate strong stimulated inelastic x-ray scattering by resonantly exciting a dense gas target of neon with femtosecond, high-intensity x-ray pulses from an x-ray free-electron laser (XFEL). A small number of lower energy XFEL seed photons drive an avalanche of stimulated resonant inelastic x-ray scattering processes that amplify the Raman scattering signal by several orders of magnitude until it reaches saturation. Despite the large overall spectral width, the internal spiky structure of the XFEL spectrum determines the energy resolution of the scattering process in a statistical sense. This is demonstrated by observing a stochastic line shift of the inelastically scattered x-ray radiation. In conjunction with statistical methods, XFELs can be used for stimulated resonant inelastic x-ray scattering, with spectral resolution smaller than the natural width of the core-excited, intermediate state.

Stark widths and shifts for spectral lines of Sn IV

NASA Astrophysics Data System (ADS)

de Andrés-García, I.; Alonso-Medina, A.; Colón, C.

2016-01-01

In this paper, we present theoretical Stark widths and shifts calculated corresponding to 66 spectral lines of Sn IV. We use the Griem semi-empirical approach and the COWAN computer code. For the intermediate coupling calculations, the standard method of least-squares fitting from experimental energy levels was used. Data are presented for an electron density of 1017 cm-3 and temperatures T = 1.1-5.0 (104 K). The matrix elements used in these calculations have been determined from 34 configurations of Sn IV: 4d10ns(n = 5-10), 4d10nd(n = 5-8), 4d95s2, 4d95p2, 4d95s5d, 4d85s5p2 and 4d105g for even parity and 4d10np(n = 5-8), 4d10nf (n = 4-6), 4d95snp(n = 5-8), 4d85s25p and 4d95snf (n = 4-10) for odd parity. Also, in order to test the matrix elements used in our calculations, we present calculated values of radiative lifetimes of 14 levels of Sn IV. There is good agreement between our calculations and the experimental radiative lifetimes obtained from the bibliography. The spectral lines of Sn IV are observed in UV spectra of HD 149499 B obtained with the Far Ultraviolet Spectroscopic Explorer, the Goddard High Resolution Spectrograph and the International Ultraviolet Explorer. Theoretical trends of the Stark broadening parameter versus the temperature for relevant lines are presented. Also our values of Stark broadening parameters have been compared with the data available in the bibliography.

Lunar Sodium and Potassium Exosphere in May 2014

NASA Astrophysics Data System (ADS)

Oliversen, R. J.; Kuruppuaratchi, D. C. P.; Mierkiewicz, E. J.; Derr, N. J.; Rosborough, S.; Gallant, M. A.; Roesler, F. L.

2015-12-01

We apply high resolution spectroscopy to investigate the lunar exosphere by measuring sodium and potassium spectral line profiles to determine the variations in exospheric effective temperatures and velocities. Observations were made at the National Solar Observatory McMath-Pierce Telescope during May 2014. Data were collected over several nights, centered on full moon (May 14) and covering a waxing phase angle of 67° to a waning phase angle of 75°. We used a dual-etalon Fabry-Perot spectrometer with a resolving power of 184,000 (1.63 km s-1) to measure the line widths and radial velocity shifts of the sodium D2 (5889.951 Å) and potassium D1 (7698.965 Å) emission lines. The field of view was 3 arcmin (~330 km) and positioned at several locations, each centered at 1.5 arcmin (~165 km) off the East and West sunlit limbs. The deconvolved line widths indicate significant differences between the sodium and potassium temperatures. The sodium line widths were mostly symmetric as a function of phase for both the waxing and waning phases. At phase angles > 40º (outside of the magnetotail) the full width half maximum (FWHM) line widths are 1.5 - 2.0 km s-1 or ~1500 K for FWHM = 1.75 km s-1. Inside the magnetotail (phase angle < 40º) and near full moon (phase angle ~6°), the FWHM increased to ~4 km s-1. The implied line width temperature is 8000 K, although some of the observed line width may be due to a dispersion in velocities from many contribution along the extended sodium tail. Unlike sodium, the potassium line widths are wider by 50% during the waxing phase compared to the waning phase at phases > 40º. The potassium temperatures pre-magnetotail passage are ~1000 K while the temperatures post-magnetotail passage are ~2000K. At phase angles < 40º, the potassium intensities decreased dramatically; on consecutive days, when the phase angle changed from 44º to 31º to 20º, the relative intensities dropped by 1.0:0.6:0.15. The potassium intensity in the East and West equatorial regions (latitude < 10º) were similar; however, the potassium intensity was brightest off the limb near Aristarchus (latitude ~24º), which was the crater we observed nearest the KREEP region. This work was partially supported by the NASA Planetary Astronomy programs, NNX11AE38G and NNX13AL30G.

NOSD-1000, the high-temperature nitrous oxide spectroscopic databank

NASA Astrophysics Data System (ADS)

Tashkun, S. A.; Perevalov, V. I.; Lavrentieva, N. N.

2016-07-01

We present a high-temperature version, NOSD-1000, of the nitrous oxide spectroscopic databank. The databank contains the line parameters (positions, intensities, air- and self-broadened half-widths and coefficients of temperature dependence of air- and self-broadened half-widths) of the most abundant isotopologue 14N216O of the nitrous oxide molecule. The reference temperature is Tref=1000 K and the intensity cutoff is Icut=10-25 cm-1/(molecule cm-2). More than 1.4 million lines covering the 260-8310 cm-1 spectral range are included in NOSD-1000. The databank has been generated within the framework of the method of effective operators and based on the global fittings of spectroscopic parameters (parameters of the effective Hamiltonian and effective dipole moment operators) to observed data collected from the literature. Line-by-line simulation of a medium-resolution high-temperature (T=873 K) spectrum has been performed in order to validate the databank. NOSD-1000 is freely accessible via the Internet.

Stellar model chromospheres. IX - Chromospheric activity in dwarf stars

NASA Technical Reports Server (NTRS)

Kelch, W. L.; Worden, S. P.; Linsky, J. L.

1979-01-01

High-resolution Ca II K line profiles are used to model the upper photospheres and lower chromospheres of eight main-sequence stars ranging in spectral type from F0 to M0 and exhibiting different degrees of chromospheric activity. The model chromospheres are studied as a function of spectral type and activity for stars of similar spectral type in order to obtain evidence of enhanced nonradiative heating in the upper-photospheric models and in the ratio of minimum temperature at the base of the chromosphere to effective temperature, a correlation between activity and temperature in the lower chromospheres, and a correlation of the width at the base of the K-line emission core and at the K2 features with activity. Chromospheric radiative losses are estimated for the modelled stars and other previously analyzed main-sequence stars. The results obtained strengthen the argument that dMe flare stars exhibit fundamentally solar-type activity but on an increased scale.

Spectral Line Parameters Including Temperature Dependences of Self- and Air-Broadening in the 2 (left arrow) 0 Band of CO at 2.3 micrometers

NASA Technical Reports Server (NTRS)

Devi, V. Malathy; Benner, D. Chris; Smith, M. A. H.; Mantz, A. W.; Sung, K.; Brown, L. R.; Predoi-Cross, A.

2012-01-01

Temperature dependences of pressure-broadened half-width and pressure-induced shift coefficients along with accurate positions and intensities have been determined for transitions in the 2<--0 band of C-12 O-16 from analyzing high-resolution and high signal-to-noise spectra recorded with two different Fourier transform spectrometers. A total of 28 spectra, 16 self-broadened and 12 air-broadened, recorded using high- purity (greater than or equal to 99.5% C-12-enriched) CO samples and CO diluted with dry air(research grade) at different temperatures and pressures, were analyzed simultaneously to maximize the accuracy of the retrieved parameters. The sample temperatures ranged from 150 to 298K and the total pressures varied between 5 and 700 Torr. A multispectrum nonlinear least squares spectrum fitting technique was used to adjust the rovibrational constants (G, B, D, etc.) and intensity parameters (including Herman-Wallis coefficients), rather than determining individual line positions and intensities. Self-and air-broadened Lorentz half-width coefficients, their temperature dependence exponents, self- and air-pressure-induced shift coefficients, their temperature dependences, self- and air-line mixing coefficients, their temperature dependences and speed dependence have been retrieved from the analysis. Speed-dependent line shapes with line mixing employing off-diagonal relaxation matrix element formalism were needed to minimize the fit residuals. This study presents a precise and complete set of spectral line parameters that consistently reproduce the spectrum of carbon monoxide over terrestrial atmospheric conditions.

Characterizing Quasar Outflows I: Sample, Spectral Measurements

NASA Astrophysics Data System (ADS)

Ganguly, Rajib; Christenson, D. H.; Richmond, J. M.; Derseweh, J. A.; Robbins, J. M.; Townsend, S. L.; Stark, M. A.

2012-05-01

Galaxy evolution models have shown that quasars are a crucial ingredient in the evolution of massive galaxies. Outflows play a key role in the story of quasars and their host galaxies, by helping regulate the accretion process, the star-formation rate and mass of the host galaxy (i.e., feedback). The prescription for modeling outflows as a contributor to feedback requires knowledge of the outflow velocity, geometry, and column density. In particular, we need to understand how these depend on physical parameters and how much is determined stochastically (and with what distribution). For this purpose, we are examining a sample of 11000 z=1.7-2.0 quasars from the Sloan Digital Sky Survey. This redshift range permits the following from the SDSS spectra: (1) separation of objects that do and do not exhibit outflows; (2) classification/measurement of outflow properties (ionization, velocity, velocity width); and (3) measurements of UV emission line and continuum parameters. In this poster, we subjectively divide these quasars into four categories: broad absorption-line quasars (2700 objects), associated absorption-line quasars (1700 objects), reddened quasars (160 objects), and unabsorbed/unreddened quasars (6300 objects). We present measurements of the absorption (velocities, velocity widths, equivalent widths), composite spectral profiles of outflows as a function of velocity, as well as measurements of the continuum and CIV, MgII, and FeII emission-line properties. In accompanying posters, we add photometry from the rest-frame X-ray (ROSAT and Chandra), EUV (GALEX), optical (2MASS), and infrared (WISE) bands to complete the SED. The continuum and emission-line measurements from the SDSS spectra and accompanying photometry provides estimates on the black hole masses, bolometric luminsosities, and SED. We consider empirically how these affect the outflow properties. This material is based upon work supported by the National Aeronautics and Space Administration under Grant No. 09-ADP09-0016 issued through the Astrophysics Data Analysis Program.

Raman Scattering by Crystals of Rare-Earth Hexaborides with Different Isotopes of Boron

NASA Astrophysics Data System (ADS)

Markov, Yu. F.; Gurin, V. N.; Ponkratov, K. V.

2018-04-01

Monocrystals of lanthanum hexaboride LaB6 containing both natural boron and its isotopes 10B and 11B have been produced using the solution-melt method. Polyelement hexaboride rare-earths have been grown and the corresponding ceramics have been synthesized for the first time. All these crystals have been studied by means of various techniques, generally using Raman scattering. The Raman spectra attributed to various spectral lines corresponding to nonanalyzable representations have been obtained and interpreted. Frequencies and half-widths of spectral lines have been obtained, the removal of degeneracy and the development of respective splitting of degenerate oscillations induced by defects, mainly by boron isotope inclusions, have been identified. The influence of defects on the Raman spectra has been determined.

Vector magnetic fields in sunspots. I - Stokes profile analysis using the Marshall Space Flight Center magnetograph

NASA Technical Reports Server (NTRS)

Balasubramaniam, K. S.; West, E. A.

1991-01-01

The Marshall Space Flight Center (MSFC) vector magnetograph is a tunable filter magnetograph with a bandpass of 125 mA. Results are presented of the inversion of Stokes polarization profiles observed with the MSFC vector magnetograph centered on a sunspot to recover the vector magnetic field parameters and thermodynamic parameters of the spectral line forming region using the Fe I 5250.2 A spectral line using a nonlinear least-squares fitting technique. As a preliminary investigation, it is also shown that the recovered thermodynamic parameters could be better understood if the fitted parameters like Doppler width, opacity ratio, and damping constant were broken down into more basic quantities like temperature, microturbulent velocity, or density parameter.

Low resolution spectroscopy of selected Algol systems

NASA Astrophysics Data System (ADS)

Devarapalli, Shanti Priya; Jagirdar, Rukmini; Parthasarathy, M.; Sahu, D. K.; Mohan, Vijay; Bhatt, B. C.; Thomas, Vineet S.

2018-04-01

The analysis of spectroscopic data for 30 Algol-type binaries is presented. All these systems are short period Algols having primaries with spectral types B and A. Dominant spectral lines were identified for the spectra collected and their equivalent widths were calculated. All the spectra were examined to understand presence of mass transfer, a disk or circumstellar matter and chromospheric emission. We also present first spectroscopic and period study for few Algols and conclude that high resolution spectra within and outside the primary minimum are needed for better understanding of these Algol type close binaries.

Potassium in the atmosphere of Mercury

NASA Technical Reports Server (NTRS)

Potter, A. E.; Morgan, T. H.

1986-01-01

Spectral data are reported from a search for potassium in the Mercury atmosphere. The data were collected with instrumentation at Kitt Peak (7699 A) and at McDonald Observatory (7698.98 and 7664.86 A). The equivalent mean widths of the potassium emission lines observed are tabulated, along with the estimated abundances, which are compared with sodium abundances as determined by resonance lines. The average column abundance of potassium is projected to be 1 billion atoms/sq cm, about 1 percent the column abundance of sodium.

THE SPECTRALLY RESOLVED Lyα EMISSION OF THREE Lyα-SELECTED FIELD GALAXIES AT z ∼ 2.4 FROM THE HETDEX PILOT SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chonis, Taylor S.; Finkelstein, Steven L.; Gebhardt, Karl

2013-10-01

We present new results on the spectrally resolved Lyα emission of three Lyα-emitting field galaxies at z ∼ 2.4 with high Lyα equivalent width (>100 Å) and Lyα luminosity (∼10{sup 43} erg s{sup –1}). At 120 km s{sup –1} (FWHM) spectral resolution, the prominent double-peaked Lyα profile straddles the systemic velocity, where the velocity zero point is determined from spectroscopy of the galaxies' rest-frame optical nebular emission lines. The average velocity offset from systemic of the stronger redshifted emission component for our sample is 176 km s{sup –1} while the average total separation between the redshifted and main blueshifted emissionmore » components is 380 km s{sup –1}. These measurements are a factor of ∼2 smaller than for UV-continuum-selected galaxies that show Lyα in emission with lower Lyα equivalent widths. We compare our Lyα spectra to the predicted line profiles of a spherical 'expanding shell' Lyα radiative transfer grid that models large-scale galaxy outflows. Specifically, blueward of the systemic velocity where two galaxies show a weak, highly blueshifted (by ∼1000 km s{sup –1}) tertiary emission peak, the model line profiles are a relatively poor representation of the observed spectra. Since the neutral gas column density has a dominant influence over the shape of the Lyα line profile, we caution against equating the observed Lyα velocity offset with a physical outflow velocity, especially at lower spectral resolution where the unresolved Lyα velocity offset is a convoluted function of several degenerate parameters. Referring to rest-frame ultraviolet and optical Hubble Space Telescope imaging, we find that galaxy-galaxy interactions may play an important role in inducing a starburst that results in copious Lyα emission as well as perturbing the gas distribution and velocity field, both of which have strong influence over the Lyα emission line profile.« less

Narrow Quasar Absorption Lines and the History of the Universe

NASA Astrophysics Data System (ADS)

Liebscher, Dierck-Ekkehard

In order to get an estimation of the parameters of the cosmological model the statistics of narrow absorption lines in quasar spectra is evaluated. To this end a phenomenological model of the evolution of the corresponding absorbers in density, size, number and dimension is presented and compared with the observed evolution in the spectral density of the lines and their column density seen in the equivalent width. In spite of the wide range of possible models, the Einstein-deSitter model is shown to be unlikely because of the implied fast evolution in mass.

Exoplanetary System HD 189733 - Chromosphere, Transit, Activity

NASA Astrophysics Data System (ADS)

Krejcova, T.; Czesla, S.; Wolter, U.; Schmitt, J. H. M. M.

2015-01-01

We present a study of the temporal evolution of the chromospherically sensitive lines in the transiting exoplanetary system HD 189733 using high-resolution UVES spectra. With its fast temporal cadence of only 45 s and its wide spectral coverage, our time series is ideal to study the influence of the transiting planetary disk on chromospheric lines . We measured the equivalent width and central line depression of the Ca II H and K lines, Hα, and the Ca II infrared triplet. While all these lines show temporal evolution on a scale potentially induced by the occulting planetary disk, strong intrinsic stellar variability prevents us from uniquely ascribing the observed variation to the planetary transit.

Homogeneous and inhomogeneous broadenings and the Voigt line shapes in the phase-resolved and intensity sum-frequency generation vibrational spectroscopy.

PubMed

Chen, Shun-Li; Fu, Li; Gan, Wei; Wang, Hong-Fei

2016-01-21

In this report, we show that the ability to measure the sub-1 cm(-1) resolution phase-resolved and intensity high-resolution broadband sum frequency generation vibrational spectra of the -CN stretch vibration of the Langmuir-Blodgett (LB) monolayer of the 4-n-octyl-4'-cyanobiphenyl (8CB) on the z-cut α-quartz surface allows the direct comparison and understanding of the homogeneous and inhomogeneous broadenings in the imaginary and intensity SFG vibrational spectral line shapes in detail. The difference of the full width at half maximum (FWHM) of the imaginary and intensity sum-frequency generation vibrational spectroscopy spectra of the same vibrational mode is the signature of the Voigt line shape and it measures the relative contribution to the overall line shape from the homogeneous and inhomogeneous broadenings in SFG vibrational spectra. From the phase-resolved and intensity spectra, we found that the FWHM of the 2238.00 ± 0.02 cm(-1) peak in the phase-resolved imaginary and intensity spectra is 19.2 ± 0.2 cm(-1) and 21.6 ± 0.4 cm(-1), respectively, for the -CN group of the 8CB LB monolayer on the z-cut α-quartz crystal surface. The FWHM width difference of 2.4 cm(-1) agrees quantitatively with a Voigt line shape with a homogeneous broadening half width of Γ = 5.29 ± 0.08 cm(-1) and an inhomogeneous standard derivation width Δω = 5.42 ± 0.07 cm(-1). These results shed new lights on the understanding and interpretation of the line shapes of both the phase-resolved and the intensity SFG vibrational spectra, as well as other incoherent and coherent spectroscopic techniques in general.

Wide band continuous all-fiber comb generator at 1.5 micron

NASA Astrophysics Data System (ADS)

Lemaître, François; Mondin, Linda; Orlik, X.

2017-11-01

We present an all-fiber continuous optical frequency comb-generator (OFCG) able to generate over 6 nm (750 GHz) at 1560 nm using a combination of electro-optic and acousto-optic modulations. As opposed to numerous experimental setups that use the longitudinal modes of an optical cavity to generate continuous optical frequency combs, our setup doesn't need any active stabilization of the cavity length since we use the intrinsically high stability of radiofrequency sources to generate the multiple lines of the comb laser. Moreover, compared to the work of ref [1], the hybrid optical modulation we use allows to suppress the problem of instability due interferences between the generated lines. We notice that these lines benefit from the spectral quality of the seed laser because the spectral width of the synthesized hyperfrequency and radiofrequency signals are generally narrower than laser sources.

MODTRAN2: Evolution and applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, G.P.; Chetwynd, J.H.; Kneizys, F.X.

1994-12-31

MODTRAN2 is the most recent version of the Moderate Resolution Atmospheric Radiance and Transmittance Model. It encompasses all the capabilities of LOWTRAN 7, the historic 20 cm{sup {minus}1} resolution (full width at half maximum, FWHM) radiance code, but incorporates a much more sensitive molecular band model with 2 cm{sup {minus}1} resolution. The band model is based directly upon the HITRAN spectral parameters, including both temperature and pressure (line shape) dependencies. Because the band model parameters and their applications to transmittance calculations have been independently developed using equivalent width binning procedures, validation against full Voigt line-by-line calculations is important. Extensive spectralmore » comparisons have shown excellent agreement. In addition, simple timing runs of MODTRAN vs. FASCOD3P show an improvement of more than a factor of 100 for a typical 500 cm{sup {minus}1} spectral interval and comparable vertical layering. It has been previously established that not only is MODTRAN an excellent band model for full path calculations, but it replicates layer-specific quantities to a very high degree of accuracy. Such layer quantities, derived from ratios and differences of longer path MODTRAN calculations from point A to adjacent layer boundaries, can be used to provide inversion algorithm weighting functions or similarly formulated quantities. One of the most exciting new applications is the rapid calculation of reliable IR cooling rates, including species, altitude, and spectral distinctions, as well as the standard integrated quantities. Comparisons with prior line-by-line cooling rate calculations are excellent, and the techniques can be extended to incorporate global climatologies. Enhancements expected to appear in MODTRAN3 relate directly to climate change studies. The addition of ultraviolet SO{sub 2} and NO{sub 2} in the UV, along with upgraded ozone Chappuis bands in the visible will also be part of MODTRAN3.« less

THE TWO REGIMES OF PHOTOSPHERIC MOTIONS IN {alpha} HYDRA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gray, David F., E-mail: dfgray@uwo.ca

2013-02-10

High-resolution spectroscopic observations of {alpha} Hya were acquired between 2003 and 2010. Analysis of line shifts, differential shifts, line widths, and line bisectors points to two regimes of velocity fields in the photosphere of {alpha} Hya: (1) normal granulation embedded in (2) large convection cells. Variations occur on a wide range of timescales, from several years on down. Radial velocity variations, which are irregular and span 786 m s{sup -1}, have a distribution consistent with a true mean rise velocity of the large cells of {approx}725 m s{sup -1} and a dispersion of {approx}220 m s{sup -1}. The distribution ofmore » granulation velocities, as measured from the widths of spectral lines, shows only small variations, consistent with the two regime concepts. On the multi-year timescale, radial velocity changes, small temperature variations ({approx}10 K), and small line-width variations ({approx}<0.8%) track each other, possibly with phase shifts. The granulation velocity gradient for {alpha} Hya is about half as large as the Sun's and no variation with time was seen, implying that any variation in velocity gradient from one large cell to the next must be less than a few percent. The asymmetry in the granulation velocity distribution, as specified in the flux deficit, is smaller than expected for {alpha} Hya's position in the HR diagram and appears to be variable.« less

Time scale variation of MgII resonance lines of HD 41335 in UV region

NASA Astrophysics Data System (ADS)

Nikolaou, I.

2012-01-01

It is known that hot emission stars (Be and Oe) present peculiar and very complex spectral line profiles. Due to these perplexed lines that appear, it is difficult to actually fit a classical distribution to those physical profiles. Therefore many physical parameters of the regions, where these lines are created, can not be determined. In this paper, we study the Ultraviolet (UV) MgII (?? 2795.523, 2802.698 A) resonance lines of the HD 41335 star, at three different periods. Considering that these profiles consist of a number of independent Discrete or Satellite Absorption Components (DACs, SACs), we use the Gauss-Rotation model (GR-model). From this analysis we can estimate the values of a group of physical parameters, such as the apparent rotational and radial velocities, the random velocities of the thermal motions of the ions, as well as the Full Width at Half Maximum (FWHM), the column density and the absorbed energy of the independent regions of matter, which produce the main and the satellite components of the studied spectral lines. Eventually, we calculate the time scale variations of the above physical parameters.

Characterization of the frequency stability of an optical frequency standard at 1.39 µm based upon noise-immune cavity-enhanced optical heterodyne molecular spectroscopy.

PubMed

Dinesan, H; Fasci, E; D'Addio, A; Castrillo, A; Gianfrani, L

2015-01-26

Frequency fluctuations of an optical frequency standard at 1.39 µm have been measured by means of a highly-sensitive optical frequency discriminator based on the fringe-side transmission of a high finesse optical resonator. Built on a Zerodur spacer, the optical resonator exhibits a finesse of 5500 and a cavity-mode width of about 120 kHz. The optical frequency standard consists of an extended-cavity diode laser that is tightly stabilized against the center of a sub-Doppler H(2) (18)O line, this latter being detected by means of noise-immune cavity-enhanced optical heterodyne molecular spectroscopy. The emission linewidth has been carefully determined from the frequency-noise power spectral density by using a rather simple approximation, known as β-line approach, as well as the exact method based on the autocorrelation function of the laser light field. It turns out that the linewidth of the optical frequency standard amounts to about 7 kHz (full width at half maximum) for an observation time of 1 ms. Compared to the free-running laser, the measured width corresponds to a line narrowing by a factor of ~220.

UV and VUV spectroscopy and photochemistry of small molecules in a supersonic jet

NASA Technical Reports Server (NTRS)

Ruehl, E.; Vaida, V.

1990-01-01

UV and VUV absorption and emission spectroscopy is used to probe jet cooled molecules, free radicals, and clusters in the gas phase. Due to efficient cooling inhomogeneous effects on spectral line widths are eliminated. Therefore from these spectra, both structural and dynamical information is obtained. The photoproducts of these reactions are probed by resonance enhanced multiphoton ionization.

Dependence of astigmatism, far-field pattern, and spectral envelope width on active layer thickness of gain guided lasers with narrow stripe geometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mamine, T.

1984-06-15

The effects of active layer thickness on the astigmatism, the angle of far-field pattern width parallel to the junction, and the spectral envelope width of a gain guided laser with a narrow stripe geometry have been investigated analytically and experimentally. It is concluded that a large level of astigmatism, a narrow far-field pattern width, and a rapid convergence of the spectral envelope width are inherent to the gain guided lasers with thin active layers.

Carbon Dioxide Line Shapes for Atmospheric Remote Sensing

NASA Astrophysics Data System (ADS)

Predoi-Cross, Adriana; Ibrahim, Amr; Wismath, Alice; Teillet, Philippe M.; Devi, V. Malathy; Benner, D. Chris; Billinghurst, Brant

2010-02-01

We present a detailed spectroscopic study of carbon dioxide in support of atmospheric remote sensing. We have studied two weak absorption bands near the strong ν2 band that is used to derive atmospheric temperature profiles. We have analyzed our laboratory spectra recorded with the synchrotron and globar sources with spectral line profiles that reproduce the absorption features with high accuracy. The Q-branch transitions exhibited asymmetric line shape due to weak line-mixing. For these weak transitions, we have retrieved accurate experimental line strengths, self- and air-broadening, self- and air-induced shift coefficients and weak line mixing parameters. The experimental precision is sufficient to reveal inherent variations of the width and shift coefficients according to transition quantum numbers.

VizieR Online Data Catalog: BAL QSOs from SDSS DR3 (Trump+, 2006)

NASA Astrophysics Data System (ADS)

Trump, J. R.; Hall, P. B.; Reichard, T. A.; Richards, G. T.; Schneider, D. P.; vanden Berk, D. E.; Knapp, G. R.; Anderson, S. F.; Fan, X.; Brinkman, J.; Kleinman, S. J.; Nitta, A.

2007-11-01

We present a total of 4784 unique broad absorption line quasars from the Sloan Digital Sky Survey Third Data Release (Cat. ). An automated algorithm was used to match a continuum to each quasar and to identify regions of flux at least 10% below the continuum over a velocity range of at least 1000km/s in the CIV and MgII absorption regions. The model continuum was selected as the best-fit match from a set of template quasar spectra binned in luminosity, emission line width, and redshift, with the power-law spectral index and amount of dust reddening as additional free parameters. We characterize our sample through the traditional balnicity index and a revised absorption index, as well as through parameters such as the width, outflow velocity, fractional depth, and number of troughs. (1 data file).

Alignment and absolute wavelength calibration of imaging Bragg spectrometers.

PubMed

Bertschinger, G; Marchuk, O; Barnsley, R

2016-11-01

In the present and the next generation of fusion devices, imaging Bragg spectrometers are key diagnostics to measure plasma parameters in the hot core, especially ion temperature and plasma rotation. The latter quantities are routinely obtained using the Doppler-width and -shift of the emitted spectral lines, respectively. Line shift measurements require absolute accuracies Δλ/λ of about 10 ppm, where λ-is the observed wavelength. For ITER and the present fusion devices, spectral lines of He-and H-like argon, iron, and krypton as well as Ne-like tungsten are foreseen for the measurements. For these lines, Kα lines can be found, some in higher order, which fit into the narrow energy window of the spectrometers. For arbitrary wavelength settings, Kα lines are also used to measure the miscut of the spherical crystals; afterwards the spectrometers can be set according to the geometrical imaging properties using coordinate measurement machines. For the spectrometers measuring Lyα lines of H-like ions, fluorescence targets can provide in situ localized calibration lines on the spectra. The fluorescence targets are used best in transmission and are excited by the thermal x-ray radiation of the plasma. An analytic theory of fluorescence is worked out.

A Catalog of Quasar Properties from the Baryon Oscillation Spectroscopic Survey

NASA Astrophysics Data System (ADS)

Chen, Zhi-Fu; Pan, Da-Sheng; Pang, Ting-Ting; Huang, Yong

2018-01-01

Using the quasars with z em < 0.9 from the Baryon Oscillation Spectroscopic Survey, we measure the spectral characteristics, including continuum and emission lines, around the Hβ and Hα spectral regions, which are lacking in Quasar Data Release 12 (DR12Q). We estimate the virial black hole mass from broad Hα and/or Hβ, and infer quasar redshifts from [O III] λ5007 emission lines. All the measurements and derived quantities are publicly available. A comparison between [O III] λ5007 redshifts and the visual inspection redshifts included in DR12Q indicates that the visual inspection redshifts are robust. We find that the full widths at half maximum of the broad Hα are consistent with those of the broad Hβ, while both the equivalent widths and line luminosities of the broad Hα are obviously larger than the corresponding quantities of the broad Hβ. We also find that there is an obviously systematic offset between the Hβ and Hα based mass if they are inferred from the empirical relationships in the literature. Using our large quasar sample, we have improved the Hβ and Hα based mass estimators by minimizing the difference between the Hβ- and Hα-based masses. For the black hole mass estimator (Equation (1)), we find that the coefficients (a, b) = (7.00, 0.50) for Hα and (a, b) = (6.96, 0.50) for Hβ are the best choices.

Geometrical effects in data collection and processing for calibration-free laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Shabanov, S. V.; Gornushkin, I. B.

2018-01-01

Data processing in the calibration-free laser-induced breakdown spectroscopy (LIBS) is usually based on the solution of the radiative transfer equation along a particular line of sight through a plasma plume. The LIBS data processing is generalized to the case when the spectral data are collected from large portions of the plume. It is shown that by adjusting the optical depth and width of the lines the spectra obtained by collecting light from an entire spherical homogeneous plasma plume can be least-square fitted to a spectrum obtained by collecting the radiation just along a plume diameter with a relative error of 10-11 or smaller (for the optical depth not exceeding 0.3) so that a mismatch of geometries of data processing and data collection cannot be detected by fitting. Despite the existence of such a perfect least-square fit, the errors in the line optical depth and width found by a data processing with an inappropriate geometry can be large. It is shown with analytic and numerical examples that the corresponding relative errors in the found elemental number densities and concentrations may be as high as 50% and 20%, respectively. Safe for a few found exceptions, these errors are impossible to eliminate from LIBS data processing unless a proper solution of the radiative transfer equation corresponding to the ray tracing in the spectral data collection is used.

Study of Structure and Small-Scale Fragmentation in TMC-1

NASA Technical Reports Server (NTRS)

Langer, W. D.; Velusamy, T.; Kuiper, T. B.; Levin, S.; Olsen, E.; Migenes, V.

1995-01-01

Large-scale C(sup 18)O maps show that the Taurus molecular cloud 1 (TMC-1) has numerous cores located along a ridge which extends about 12 minutes by at least 35 minutes. The cores traced by C(sup 18)O are about a few arcminutes (0.1-0.2 pc) in extent, typically contain about 0.5-3 solar mass, and are probably gravitationally bound. We present a detailed study of the small-scale fragmentary structure of one of these cores, called core D, within TMC-1 using very high spectral and spatial resolution maps of CCS and CS. The CCS lines are excellent tracers for investigating the density, temperature, and velocity structure in dense cores. The high spectral resolution, 0.008 km /s, data consist mainly of single-dish, Nyquist-sampled maps of CCS at 22 GHz with 45 sec spatial resolution taken with NASA's 70 m DSN antenna at Goldstone. The high spatial resolution spectral line maps were made with the Very Large Array (9 sec resolution) at 22 GHz and with the OVRO millimeter array in CCS and CS at 93 GHz and 98 GHz, respectively, with 6 sec resolution. These maps are supplemented with single-dish observations of CCS and CC(sup 34)S spectra at 33 GHz using a NASA 34 m DSN antenna, CCS 93 GHz, C(sup 34)S (2-1), and C(sup 18)O (1-0) single-dish observations made with the AT&T Bell Laboratories 7 m antenna. Our high spectral and spatial CCS and CS maps show that core D is highly fragmented. The single-dish CCS observations map out several clumps which range in size from approx. 45 sec to 90 sec (0.03-0.06 pc). These clumps have very narrow intrinsic line widths, 0.11-0.25 km/s, slightly larger than the thermal line width for CCS at 10 K, and masses about 0.03-0.2 solar mass. Interferometer observations of some of these clumps show that they have considerable additional internal structure, consisting of several condensations ranging in size from approx. 10 sec- 30 sec (0.007-0.021 pc), also with narrow line widths. The mass of these smallest fragments is of order 0.01 solar mass. These small-scale structures traced by CCS appear to be gravitationally unbound by a large factor. Most of these objects have masses that fall below those of the putative proto-brown dwarfs (approx. less than 0.1 solar mass). The presence of many small gravitationally unbound clumps suggests that fragmentation mechanisms other than a purely Jeans gravitational instability may be important for the dynamics of these cold dense cores.

The Iron Abundance of IOTA Herculis From Ultraviolet Iron Lines

NASA Astrophysics Data System (ADS)

Grigsby, J.; Mulliss, C.; Baer, G.

1995-03-01

We have obtained (Adelman 1992, 1993, private comunication) coadded, high-resolution IUE spectra of Iota Herculis (B3 IV) in both short wavelength (SWP) and long wavelength (LWP) regions. The spectra span the ultraviolet spectrum from 110 - 300 nm and have a SNR of roughly 30 -50; they are described in Adelman et. al. (1993, ApJ 419, 276). Abundance indicators were 54 lines of Fe II and 26 lines of Fe III whose atomic parameters have been measured in the laboratory. LTE synthetic spectra for comparison with observations were produced with the Kurucz model atmosphere and spectral synthesis codes ATLAS9/SYNTHE (Kurucz 1979, ApJS 40,1; Kurucz and Avrett 1981, SAO Special Report 391). Model parameters were chosen from the literature: effective temperature = 17500 K, log g =3.75, v sin i= 11 km/s, and turbulent velocity = 0 km/s. (Peters and Polidan 1985, in IAU Symposium 111, ed. D. S. Hayes et al. (Dordrecht: Reidel), 417). We determined the equivalent widths of the chosen lines by fitting gaussian profiles to the lines and by measuring the equivalent widths of the gaussians. We derived abundances by fitting a straight line to a plot of observed equivalent widths vs. synthetic equivalent widths; we adjusted the iron abundance of the models until a slope of unity was achieved. The abundances derived from the different ionization stages are in agreement: Fe II lines indicate an iron abundance that is 34 +15/-10% the solar value([Fe/H]=-0.47 +0.16-0.15dex), while from Fe III lines we obtain 34 +/- 10% ([Fe/H]=-0.47 +0.11/-0.15 dex). A search of the literature suggests that no previous investigations of this star's iron abundance have found agreement between the different ionization stages. We thank Saul Adelman for his generous assistance, and the Faculty Research Fund Board of Wittenberg University for support of this research.

Mercury exosphere. III: Energetic characterization of its sodium component

NASA Astrophysics Data System (ADS)

Leblanc, Francois; Chaufray, Jean-Yves; Doressoundiram, Alain; Berthelier, Jean-Jacques; Mangano, Valeria; López-Ariste, Arturo; Borin, Patrizia

2013-04-01

Mercury's sodium exosphere has been observed only few times with high spectral resolution from ground based observatories enabling the analysis of the emission spectra. These observations highlighted the energetic state of the sodium exospheric atoms relative to the surface temperature. More recently, the Doppler shift of the exospheric Na atoms was measured and interpreted as consistent with an exosphere moving outwards from the subsolar point (Potter, A.E., Morgan, T.H., Killen, R.E. [2009]. Icarus 204, 355-367). Using THEMIS solar telescope, we observed Mercury's sodium exosphere with very high spectral resolution at two opposite positions of its orbit. Using this very high spectral resolution and the scanning capabilities of THEMIS, we were able to reconstruct the 2D spatial distributions of the Doppler shifts and widths of the sodium atomic Na D2 and D1 lines. These observations revealed surprisingly large Doppler shift as well as spectral width consistent with previous observations. Starting from our 3D model of Mercury Na exosphere (Mercury Exosphere Global Circulation Model, Leblanc, F., Johnson, R.E. [2010]. Icarus 209, 280-300), we coupled this model with a 3D radiative transfer model described in a companion paper (Chaufray, J.Y., Leblanc, F. [2013]. Icarus, submitted for publication) which allows us to properly treat the non-maxwellian state of the simulated sodium exospheric population. Comparisons between THEMIS observations and simulations suggest that the previously observed energetic state of the Na exosphere might be essentially explained by a state of the Na exospheric atoms far from thermal equilibrium along with the Doppler shift dispersion of the Na atoms induced by the solar radiation pressure. However, the Doppler shift of the spectral lines cannot be explained by our modelling, suggesting either an exosphere spatially structured very differently than in our model or the inaccuracy of the spectral calibration when deriving the Doppler shift.

Advances in atmospheric temperature profile measurements using high spectral resolution lidar

NASA Astrophysics Data System (ADS)

Razenkov, Ilya I.; Eloranta, Edwin W.

2018-04-01

This paper reports the atmospheric temperature profile measurements using a University of Wisconsin-Madison High Spectral Resolution Lidar (HSRL) and describes improvements in the instrument performance. HSRL discriminates between Mie and Rayleigh backscattering [1]. Thermal motion of molecules broadens the spectrum of the transmitted laser light due to Doppler effect. The HSRL exploits this property to allow the absolute calibration of the lidar and measurements of the aerosol volume backscatter coefficient. Two iodine absorption filters with different line widths are used to resolve temperature sensitive changes in Rayleigh backscattering for atmospheric temperature profile measurements.

Proton clouds to measure long-range contacts between nonexchangeable side chain protons in solid-state NMR.

PubMed

Sinnige, Tessa; Daniëls, Mark; Baldus, Marc; Weingarth, Markus

2014-03-26

We show that selective labeling of proteins with protonated amino acids embedded in a perdeuterated matrix, dubbed 'proton clouds', provides general access to long-range contacts between nonexchangeable side chain protons in proton-detected solid-state NMR, which is important to study protein tertiary structure. Proton-cloud labeling significantly improves spectral resolution by simultaneously reducing proton line width and spectral crowding despite a high local proton density in clouds. The approach is amenable to almost all canonical amino acids. Our method is demonstrated on ubiquitin and the β-barrel membrane protein BamA.

Faraday effect on the Rb D{sub 1} line in a cell with a thickness of half the wavelength of light

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sargsyan, A., E-mail: sarmeno@mail.ru, E-mail: sargsyanarmen85@gmail.com; Pashayan-Leroy, Y.; Leroy, C.

2016-09-15

The rotation of the radiation polarization plane in a longitudinal magnetic field (Faraday effect) on the D{sub 1} line in atomic Rb vapor has been studied with the use of a nanocell with the thickness L varying in the range of 100–900 nm. It has been shown that an important parameter is the ratio L/λ, where λ = 795 nm is the wavelength of laser radiation resonant with the D{sub 1} line. The best parameters of the signal of rotation of the radiation polarization plane have been obtained at the thickness L = λ/2 = 397.5 nm. The fabricated nanocellmore » had a large region with such a thickness. The spectral width of the signal reached at the thickness L = 397.5 nm is approximately 30 MHz, which is much smaller than the spectral width (≈ 500 MHz) reached with ordinary cells with a thickness in the range of 1–100 mm. The parameters of the Faraday rotation signal have been studied as functions of the temperature of the nanocell, the laser power, and the magnetic field strength. The signal has been reliably detected at the laser power P{sub L} ≥ 1 μW, magnetic field strength B ≥ 0.5 G, and the temperature of the nanocell T ≥ 100°C. It has been shown that the maximum rotation angle of the polarization plane in the longitudinal magnetic field is reached on the F{sub g} = 3 → F{sub e} = 2 transition of the {sup 85}Rb atom. The spectral profile of the Faraday rotation signal has a specific shape with a sharp peak, which promotes its applications. In particular, Rb atomic transitions in high magnetic fields about 1000 G are split into a large number of components, which are completely spectrally resolved and allow the study of the behavior of an individual transition.« less

Physics of the infrared spectrum

NASA Technical Reports Server (NTRS)

Deming, Drake; Jennings, Donald E.; Jefferies, John; Lindsey, Charles

1991-01-01

The IR bandpass is attractive for solar magnetic field studies in virtue of the proportionality to wavelength of the ratio of Zeeman splitting to line width. The large Zeeman splitting and optical thinness of the 12-micron observations render them especially useful for vector magnetic field derivations. The IR continuum, and many IR spectral lines, are formed in LTE and are useful in studies of the temperature structure of the solar atmosphere from the deepest observable photospheric layers to chromospheric altitudes. The far-IR continuum is an excellent thermometer for the upper photosphere and chromosphere.

IR spectroscopy of water vapor confined in nanoporous silica aerogel.

PubMed

Ponomarev, Yu N; Petrova, T M; Solodov, A M; Solodov, A A

2010-12-06

The absorption spectrum of the water vapor, confined in the nanoporous silica aerogel, was measured within 5000-5600 cm(-1) with the IFS 125 HR Fourier spectrometer. It has been shown, that tight confinement of the molecules by the nanoporous size leads to the strong lines broadening and shift. For water vapor lines, the HWHM of confined molecules are on the average 23 times larger than those for free molecules. The shift values are in the range from -0.03 cm(-1) to 0.09 cm(-1). Some spectral lines have negative shift. The data on the half-widths and center shifts for some strongest H(2)O lines have been presented.

Methane spectral line widths and shifts, and dependences on physical parameters

NASA Technical Reports Server (NTRS)

Fox, K.; Quillen, D. T.; Jennings, D. E.; Wagner, J.; Plymate, C.

1991-01-01

A detailed report of the recent high-resolution spectroscopic research on widths and shifts measured for a strong infrared-active fundamental of methane is presented. They were measured in collision with several rare gases and diatomic molecules, in the vibrational-rotational fundamental near 3000/cm. These measurements were made at an ambient temperature of 294 K over a range of pressures from 100 to 700 torr. The measurements are discussed in a preliminary but detailed and quantitative manner with reference to masses, polarizabilities, and quadrupole moments. Some functional dependences on these physical parameters are considered. The present data are useful for studies of corresponding planetary spectra.

Alfvén Wave Turbulence as a Coronal Heating Mechanism: Simultaneously Predicting the Heating Rate and the Wave-induced Emission Line Broadening

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oran, R.; Landi, E.; Holst, B. van der

We test the predictions of the Alfvén Wave Solar Model (AWSoM), a global wave-driven magnetohydrodynamic (MHD) model of the solar atmosphere, against high-resolution spectra emitted by the quiescent off-disk solar corona. AWSoM incorporates Alfvén wave propagation and dissipation in both closed and open magnetic field lines; turbulent dissipation is the only heating mechanism. We examine whether this mechanism is consistent with observations of coronal EUV emission by combining model results with the CHIANTI atomic database to create synthetic line-of-sight spectra, where spectral line widths depend on thermal and wave-related ion motions. This is the first time wave-induced line broadening ismore » calculated from a global model with a realistic magnetic field. We used high-resolution SUMER observations above the solar west limb between 1.04 and 1.34 R {sub ⊙} at the equator, taken in 1996 November. We obtained an AWSoM steady-state solution for the corresponding period using a synoptic magnetogram. The 3D solution revealed a pseudo-streamer structure transversing the SUMER line of sight, which contributes significantly to the emission; the modeled electron temperature and density in the pseudo-streamer are consistent with those observed. The synthetic line widths and the total line fluxes are consistent with the observations for five different ions. Further, line widths that include the contribution from the wave-induced ion motions improve the correspondence with observed spectra for all ions. We conclude that the turbulent dissipation assumed in the AWSoM model is a viable candidate for explaining coronal heating, as it is consistent with several independent measured quantities.« less

SPECTRAL CLASSIFICATION AND PROPERTIES OF THE O Vz STARS IN THE GALACTIC O-STAR SPECTROSCOPIC SURVEY (GOSSS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arias, Julia I.; Barbá, Rodolfo H.; Sabín-Sanjulián, Carolina

On the basis of the Galactic O Star Spectroscopic Survey (GOSSS), we present a detailed systematic investigation of the O Vz stars. The currently used spectral classification criteria are rediscussed, and the Vz phenomenon is recalibrated through the addition of a quantitative criterion based on the equivalent widths of the He i λ 4471, He ii λ 4542, and He ii λ 4686 spectral lines. The GOSSS O Vz and O V populations resulting from the newly adopted spectral classification criteria are comparatively analyzed. The locations of the O Vz stars are probed, showing a concentration of the most extrememore » cases toward the youngest star-forming regions. The occurrence of the Vz spectral peculiarity in a solar-metallicity environment, as predicted by the fastwind code, is also investigated, confirming the importance of taking into account several processes for the correct interpretation of the phenomenon.« less

Spectroscopy as a tool for geochemical modeling

NASA Astrophysics Data System (ADS)

Kopacková, Veronika; Chevrel, Stephane; Bourguignon, Anna

2011-11-01

This study focused on testing the feasibility of up-scaling ground-spectra-derived parameters to HyMap spectral and spatial resolution and whether they could be further used for a quantitative determination of the following geochemical parameters: As, pH and Clignite content. The study was carried on the Sokolov lignite mine as it represents a site with extreme material heterogeneity and high heavy-metal gradients. A new segmentation method based on the unique spectral properties of acid materials was developed and applied to the multi-line HyMap image data corrected for BRDF and atmospheric effects. The quantitative parameters were calculated for multiple absorption features identified within the VIS/VNIR/SWIR regions (simple band ratios, absorption band depth and quantitative spectral feature parameters calculated dynamically for each spectral measurement (centre of the absorption band (λ), depth of the absorption band (D), width of the absorption band (Width), and asymmetry of the absorption band (S)). The degree of spectral similarity between the ground and image spectra was assessed. The linear models for pH, As and the Clignite content of the whole and segmented images were cross-validated on the selected homogenous areas defined in the HS images using ground truth. For the segmented images, reliable results were achieved as follows: As: R2=0.84, Clignite: R2=0.88 and R2 pH: R2= 0.57.

Study of archaeological coins of different dynasties using libs coupled with multivariate analysis

NASA Astrophysics Data System (ADS)

Awasthi, Shikha; Kumar, Rohit; Rai, G. K.; Rai, A. K.

2016-04-01

Laser Induced Breakdown Spectroscopy (LIBS) is an atomic emission spectroscopic technique having unique capability of an in-situ monitoring tool for detection and quantification of elements present in different artifacts. Archaeological coins collected form G.R. Sharma Memorial Museum; University of Allahabad, India has been analyzed using LIBS technique. These coins were obtained from excavation of Kausambi, Uttar Pradesh, India. LIBS system assembled in the laboratory (laser Nd:YAG 532 nm, 4 ns pulse width FWHM with Ocean Optics LIBS 2000+ spectrometer) is employed for spectral acquisition. The spectral lines of Ag, Cu, Ca, Sn, Si, Fe and Mg are identified in the LIBS spectra of different coins. LIBS along with Multivariate Analysis play an effective role for classification and contribution of spectral lines in different coins. The discrimination between five coins with Archaeological interest has been carried out using Principal Component Analysis (PCA). The results show the potential relevancy of the methodology used in the elemental identification and classification of artifacts with high accuracy and robustness.

Photofragmentation, state interaction, and energetics of Rydberg and ion-pair states: Resonance enhanced multiphoton ionization of HI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hróðmarsson, Helgi Rafn; Wang, Huasheng; Kvaran, Ágúst, E-mail: agust@hi.is

2014-06-28

Mass resolved resonance enhanced multiphoton ionization data for hydrogen iodide (HI), for two-photon resonance excitation to Rydberg and ion-pair states in the 69 600–72 400 cm{sup −1} region were recorded and analyzed. Spectral perturbations due to homogeneous and heterogeneous interactions between Rydberg and ion-pair states, showing as deformations in line-positions, line-intensities, and line-widths, were focused on. Parameters relevant to photodissociation processes, state interaction strengths and spectroscopic parameters for deperturbed states were derived. Overall interaction and dynamical schemes to describe the observations are proposed.

Slitless Spectroscopy

NASA Astrophysics Data System (ADS)

Davila, J. M.; O'Neill, J. F.

2013-12-01

Spectrographs provide a unique window into plasma parameters in the solar atmosphere. In fact spectrographs provide the most accurate measurements of plasma parameters such as density, temperature, and flow speed. However, traditionally spectrographic instruments have suffered from the inability to cover large spatial regions of the Sun quickly. To cover an active region sized spatial region, the slit must be rastered over the area of interest with an exposure taken at each pointing location. Because of this long cycle time, the spectra of dynamic events like flares, CME initiations, or transient brightening are obtained only rarely. And even if spectra are obtained they are either taken over an extremely small spatial region, or the spectra are not co-temporal across the raster. Either of these complicates the interpretation of the spectral raster results. Imagers are able to provide high time and spatial resolution images of the full Sun but with limited spectral resolution. The telescopes onboard the Solar Dynamics Observatory (SDO) normally take a full disk solar image every 10 seconds with roughly 1 arcsec spatial resolution. However the spectral resolution of the multilayer imagers on SDO is of order 100 times less than a typical spectrograph. Because of this it is difficult to interpret multilayer imaging data to accurately obtain plasma parameters like temperature and density from these data, and there is no direct measure of plasma flow velocity. SERTS and EIS partially addressed this problem by using a wide slit to produce monochromatic images with limited FOV to limit overlapping. However dispersion within the wide slit image remained a problem which prevented the determination of intensity, Doppler shift, and line width in the wide slit. Kankelborg and Thomas introduced the idea of using multiple images -1, 0, and +1 spectral orders of a single emission line. This scheme provided three independent images to measure the three spectral line parameters in each pixel with the Multi-Order Solar EUV Spectrograph (MOSES) instrument. We suggest a reconstruction approach based on tomographic methods with regularization. Preliminary results show that the typical Doppler shift and line width error introduced by the reconstruction method is of order a few km/s at 300 A. This is on the order of the error obtained in narrow slit spectrographs but with data obtained over a two-dimensional field of view.

Comparison of 5-year progression of retinitis pigmentosa involving the posterior pole among siblings by means of SD-OCT: a retrospective study.

PubMed

Colombo, Leonardo; Montesano, Giovanni; Sala, Barbara; Patelli, Fabio; Maltese, Paolo; Abeshi, Andi; Bertelli, Matteo; Rossetti, Luca

2018-06-26

The aim of this study is to analyze and compare the progression of photoreceptor atrophy among siblings affected by retinitis pigmentosa by means of spectral SD-OCT. Fifty three eyes of 27 patients belonging to 12 family clusters were analyzed. To assess the annual progression rate of photoreceptor atrophy, the ellipsoid zone (EZ) line was measured in OCT sections through the fovea. We used multivariate generalized mixed effects to model the rate of progression and its relation to the initial ellipsoid zone line width. During our 4.84 years (± 1.44) mean follow up time (range 3-7) 53 eyes were examined. The ellipsoid zone line width declined with a yearly average rate of 76.4 μm (4.16% / year) (p-value < 0.0001). Progression rates were poorly correlated within family clusters (p-value = 0.23) and showed statistical difference between affected siblings (p-value = 0.007). There was no correlation between inter-familiar progression rate and mode of inheritance (p-value = 0.98) as well as between age and ellipsoid zone line width among siblings (p-value = 0.91). RP could be extremely heterogeneous even among siblings: an accurate and sensitive method to follow the progression of the disease is fundamental for future development of clinical trials and therapy strategies.

[Microsecond Pulsed Hollow Cathode Lamp as Enhanced Excitation Source of Hydride Generation Atomic Fluorescence Spectrometry].

PubMed

Zhang, Shuo

2015-09-01

The spectral, electrical and atomic fluorescence characteristics of As, Se, Sb and Pb hollow cathode lamps (HCLs) powered by a laboratory-built high current microsecond pulse (HCMP) power supply were studied, and the feasibility of using HCMP-HCLs as the excitation source of hydride generation atomic fluorescence spectrometry (HG-AFS) was evaluated. Under the HCMP power supply mode, the As, Se, Sb, Pb HCLs can maintain stable glow discharge at frequency of 100~1000 Hz, pulse width of 4.0~20 μs and pulse current up to 4.0 A. Relationship between the intensity of characteristic emission lines and HCMP power supply parameters, such as pulse current, power supply voltage, pulse width and frequency, was studied in detail. Compared with the conventional pulsed (CP) HCLs used in commercial AFS instruments, HCMP-HCLs have a narrower pulse width and much stronger pulse current. Under the optimized HCMP power supply parameters, the intensity of atomic emission lines of As, Se, Sb HCLs had sharp enhancement and that indicated their capacity of being a novel HG-AFS excitation source. However, the attenuation of atomic lines and enhancement of ionic lines negated such feasibility of HCMP-Pb HCL. Then the HG-AFS analytical capability of using the HCMP-As/Se/Sb HCLs excitation source was established and results showed that the HCMP-HCL is a promising excitation source for HG-AFS.

Theoretical Stark broadening parameters for spectral lines arising from the 2p5ns, 2p5np and 2p5nd electronic configurations of Mg III

NASA Astrophysics Data System (ADS)

Colón, C.; Moreno-Díaz, C.; Alonso-Medina, A.

2013-10-01

In the present work we report theoretical Stark widths and shifts calculated using the Griem semi-empirical approach, corresponding to 237 spectral lines of Mg III. Data are presented for an electron density of 1017 cm-3 and temperatures T = 0.5-10.0 (104K). The matrix elements used in these calculations have been determined from 23 configurations of Mg III: 2s22p6, 2s22p53p, 2s22p54p, 2s22p54f and 2s22p55f for even parity and 2s22p5ns (n = 3-6), 2s22p5nd (n = 3-9), 2s22p55g and 2s2p6np (n = 3-8) for odd parity. For the intermediate coupling (IC) calculations, we use the standard method of least-squares fitting from experimental energy levels by means of the Cowan computer code. Also, in order to test the matrix elements used in our calculations, we present calculated values of 70 transition probabilities of Mg III spectral lines and 14 calculated values of radiative lifetimes of Mg III levels. There is good agreement between our calculations and experimental radiative lifetimes. Spectral lines of Mg III are relevant in astrophysics and also play an important role in the spectral analysis of laboratory plasma. Theoretical trends of the Stark broadening parameter versus the temperature for relevant lines are presented. No values of Stark parameters can be found in the bibliography.

The broad-band x ray spectral variability of Mkn 841

NASA Technical Reports Server (NTRS)

George, I. M.; Nandra, K.; Fabian, A. C.; Turner, T. J.; Done, C.; Day, C. S. R.

1992-01-01

The results of a detailed spectral analysis of four X-ray observations of the luminous Seyfert 1.5 galaxy Mkn 841 performed using the EXOSAT and Ginga satellites over the period June 1984 to July 1990 are reported. Preliminary results from a short ROSAT PSPC observation of Mkn 841 in July 1990 are also presented. Variability is apparent in both the soft (0.1-1.0 keV) and medium (1-20 keV) energy bands. Above 1 keV, the spectra are adequately modelled by a power-law with a strong emission line of equivalent width approximately 450 eV. The energy of the line (approximately 6.4 keV) is indicative of K-shell fluorescence from neutral iron, leading to the interpretation that the line arises via X-ray illumination of cold material surrounding the source. In addition to the flux variability, the continuum shape also changes in a dramatic fashion, with variations in the apparent photon index Delta(Gamma) approximately 0.6. The large equivalent width of the emission line clearly indicates a strongly enhanced reflection component in the source, compared to other Seyferts observed with Ginga. The spectral changes are interpreted in terms of a variable power-law continuum superimposed on a flatter reflection component. For one Ginga observation, the reflected flux appears to dominate the medium energy X-ray emission, resulting in an unusually flat slope (Gamma approximately 1.0). The soft X-ray excess is found to be highly variable by a factor approximately 10. These variations are not correlated with the hard flux, but it seems likely that the soft component arises via reprocessing of the hard X-rays. We find no evidence for intrinsic absorption, with the equivalent hydrogen column density constrained to be less than or equal to few x 10(exp 20) cm(exp -2). The implications of these results for physical models for the emission regions in this and other X-ray bright Seyferts are briefly discussed.

STRONGER REFLECTION FROM BLACK HOLE ACCRETION DISKS IN SOFT X-RAY STATES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steiner, James F.; Remillard, Ronald A.; García, Javier A.

We analyze 15,000 spectra of 29 stellar-mass black hole (BH) candidates collected over the 16 year mission lifetime of Rossi X-ray Timing Explorer using a simple phenomenological model. As these BHs vary widely in luminosity and progress through a sequence of spectral states, which we broadly refer to as hard and soft, we focus on two spectral components: the Compton power law and the reflection spectrum it generates by illuminating the accretion disk. Our proxy for the strength of reflection is the equivalent width of the Fe–K line as measured with respect to the power law. A key distinction ofmore » our work is that for all states we estimate the continuum under the line by excluding the thermal disk component and using only the component that is responsible for fluorescing the Fe–K line, namely, the Compton power law. We find that reflection is several times more pronounced (∼3) in soft compared to hard spectral states. This is most readily caused by the dilution of the Fe line amplitude from Compton scattering in the corona, which has a higher optical depth in hard states. Alternatively, this could be explained by a more compact corona in soft (compared to hard) states, which would result in a higher reflection fraction.« less

NGC 1058: Gas motions in an extended, quiescent spiral disk

NASA Technical Reports Server (NTRS)

Hanson, Margaret Murray; Dickey, John M.; Helou, George

1990-01-01

Researchers investigate in detail the motion of gas in the galaxy NGC 1058 using the very large array (VLA) to map the emission in the 21-cm line. This galaxy is so nearly face-on that the contribution to the line width due to the variation of the rotational velocity across the D-array beam is small compared with the random z-motion of the gas. Researchers confirm results of earlier studies (Lewis 1987, A. and A. Suppl., 63, 515; van der Kruit and Shostak 1984, A. and A., 134, 258) of the galaxy's total neutral hydrogen (HI) and kinematics, including the fact that the rotation curve drops faster than Keplerian at the outer edge of the disk, which is interpreted as a fortuitous twist of the plane of rotation in the outer disk. However, their very high velocity resolution (2.58 km s(exp -1) after Hanning smoothing) coupled with good spatial resolution, allows researchers to measure more accurately the line width, and even to some extent its shape, throughout the disk. One of the most interesting results of this study is the remarkable constancy of the line width in the outer disk. From radius 90 to 210 seconds the Gaussian velocity dispersion (sigma sub nu) of the 21-cm line has a mean value of 5.7 km s(exp -1) (after correcting for the spectral resolution) with a dispersion of less than 0.9 km s(exp -1) (after correcting for the spectral resolution) with a dispersion of less than 0.9 km s(exp -1). Translating this directly into a kinetic temperature (Doppler temperature): T sub Dopp equals 121K (sigma sub mu exp 2/(km s(exp -1) (exp 2) gives 4000 K, with a dispersion of less than 1500 K over the outer disk. This constancy is observed even when comparing the spiral arms versus inter-arm regions, which in the radius range from 100 to 150 seconds the surface density modulates (defined as the ratio N sub peak -N sub trough/N sub peak + N sub trough) from 0.5 to 0.25 in the range 150 to 200 seconds.

[Activities of Harvard College Observatory

NASA Technical Reports Server (NTRS)

Dalgarno, A.; Smith, Peter L.; Stark, G.; Yoshino, K.

2002-01-01

With support from this grant, we have: 1) Developed techniques for improving wavelengths and f-values for singly and doubly charged ions of the iron group and have improved the accuracy of Fe III wavelengths by an order of magnitude. New Fe II f-values have also resulted from this work. 2) Measured line oscillator strengths and photoabsorption cross sections for UV molecular spectral feature that have been, or could be, used for searches for and detection of molecules in diffuse and translucent interstellar clouds and for determination of molecular column densities there. In addition, we have determined other molecular parameters -- line assignments, wavelengths, and line widths -- that are essential for theoretical descriptions of the abundance, fractionation, and excitation of interstellar molecules and for comparison of predictions with observations. 3) Measured A-values for spin-changing and other weak lines in low-Z ions. When A-values are available, these spectral features are useful for astrophysical plasma density and temperature diagnostics. Such lines are also used in interstellar abundance determinations in cases where the stronger allowed lines are saturated in astronomical spectra. 4) Taken an activist approach to ensuring that, (i), astronomers have ready access to our data, and, (ii), avenues of communication between data users and producers are strengthened.

SHIELD: EVLA HI Spectral Line Observations of Low-mass Dwarfs

NASA Astrophysics Data System (ADS)

Miazzo, Masao; Ruvolo, Elizabeth; Cannon, John M.; McNichols, Andrew; Teich, Yaron; Adams, Elizabeth A.; Giovanelli, Riccardo; Haynes, Martha P.; McQuinn, Kristen B.; Salzer, John Joseph; Skillman, Evan D.; Dolphin, Andrew E.; Elson, Edward C.; Haurberg, Nathalie C.; Huang, Shan; Janowiecki, Steven; Jozsa, Gyula; Leisman, Luke; Ott, Juergen; Papastergis, Emmanouil; Rhode, Katherine L.; Saintonge, Amelie; Van Sistine, Angela; Warren, Steven R.

2017-01-01

The “Survey of HI in Extremely Low-mass Dwarfs” (SHIELD) is a multiwavelength study of local volume low-mass galaxies. Using the now-complete Arecibo Legacy Fast ALFA (ALFALFA) source catalog, 82 systems are identified that meet distance, line width, and HI flux criteria for being gas-rich, low-mass galaxies. These systems harbor neutral gas reservoirs smaller than 3x10^7 M_sun, thus populating the faint end of the HI mass function with statistical confidence for the first time. Here we present new Karl G. Jansky Very Large Array D-configuration HI spectral line observations of 32 previously unobserved galaxies. These low angular resolution (~40" beam) images localize the HI gas; with a few exceptions, the HI gas is co-spatial with the optical centers of the galaxies. These images provide the first glimpse of the neutral interstellar medium in these systems.Support for this work was provided by NSF grant 1211683 to JMC at Macalester College.

Intensity measurements for the /2, O/ gamma-band of O2, b 1Sigma-g/+/ - X 3Sigma-g/-/

NASA Technical Reports Server (NTRS)

Miller, J. H.; Giver, L. P.; Boese, R. W.

1976-01-01

Line intensities for the P sub P and P sub Q branches of the (2-O) vibrational band of the magnetic dipole electronic transition for the oxygen red system at 6280 A were measured, and the sum of the R sub R and R sub Q branch intensities was taken. A large number of repetitive spectral scans were required for accuracy, because of low absorption values even at optical path lengths from 300 to 600 m. A total of 557 individual measurements of P-branch lines yielded an intensity value for the P-branches, and equivalent widths for 24 spectral scans yielded an intensity value for the R-branch. R-branch to P-branch intensity ratios were taken for the A-band, B-band, and gamma-band (respectively, O-O at 7620 A, 1-O at 6880 A, and 2-O at 6280 A). Intensities for some rotational lines are found, and effects of combined rotation-vibration interaction are probed.

High-resolution grazing-incidence grating spectrometer for temperature measurements of low-Z ions emitting in the 100-300 Å spectral banda)

NASA Astrophysics Data System (ADS)

Widmann, K.; Beiersdorfer, P.; Magee, E. W.; Boyle, D. P.; Kaita, R.; Majeski, R.

2014-11-01

We have constructed a high-resolution grazing-incidence spectrometer designed for measuring the ion temperature of low-Z elements, such as Li+ or Li2 +, which radiate near 199 Å and 135 Å, respectively. Based on measurements at the Livermore Electron Beam Ion Trap we have shown that the instrumental resolution is better than 48 mÅ at the 200 Å setting and better than 40 mÅ for the 135-Å range. Such a high spectral resolution corresponds to an instrumental limit for line-width based temperature measurements of about 45 eV for the 199 Å Li+ and 65 eV for the 135 Å Li2 + lines. Recently obtained survey spectra from the Lithium Tokamak Experiment at the Princeton Plasma Physics Laboratory show the presence of these lithium emission lines and the expected core ion temperature of approximately 70 eV is sufficiently high to demonstrate the feasibility of utilizing our high-resolution spectrometer as an ion-temperature diagnostic.

Discrimination and quantification of autofluorescence spectra of human lung cells

NASA Astrophysics Data System (ADS)

Rahmani, Mahya; Khani, Mohammad Mehdi; Khazaei Koohpar, Zeinab; Molik, Paria

2016-10-01

To study laser-induced autofluorescence spectroscopy of the human lung cell line, we evaluated the native fluorescence properties of cancer QU-DB and normal MRC-5 human lung cells during continuous exposure to 405 nm laser light. Two emission bands centered at ~470 nm and ~560 nm were observed. These peaks are most likely attributable to mitochondrial fluorescent reduced nicotinamide adenine dinucleotide and riboflavin fluorophores, respectively. This article highlights lung cell autofluorescence characterization and signal discrimination by collective investigation of different spectral features. The absolute intensity, the spectral shape factor or redox ratio, the full width of half-maximum and the full width of quarter maximum was evaluated. Moreover, the intensity ratio, the area under the peak and the area ratio as a contrast factor for normal and cancerous cells were also calculated. Among all these features it seems that the contrast factor precisely and significantly discriminates the spectral differences of normal and cancerous lung cells. On the other hand, the relative quantum yield for both cell types were found by comparing the quantum yield of an unknown compound with known fluorescein sodium as a reference solution.

A high resolution spectroscopic study of the oxygen molecule. Ph.D. Thesis Final Report

NASA Technical Reports Server (NTRS)

Ritter, K. J.

1984-01-01

A high resolution spectrometer which incorporates a narrow line width tunable dye laser was used to make absorption profiles of 57 spectral lines in the Oxygen A-Band at pressures up to one atmosphere in pure O2. The observed line profiles are compared to the Voigt, and a collisionally narrowed, profile using a least squares fitting procedure. The collisionally narrowed profile compares more favorable to the observed profiles. Values of the line strengths and self broadening coeffiencients, determined from the least square fitting process, are presented in tabular form. It is found that the experssion by Watson are in closest agreement with the experimentally determined strengths. The self broadening coefficients are compared with the measurements of several other investigators.

UV chromospheric and circumstellar diagnostic features among F supergiant stars

NASA Technical Reports Server (NTRS)

Stencel, R. E.; Worden, S. P.; Giampapa, M. S.

1981-01-01

A survey of F supergiant stars to evaluate the extension of chromospheric and circumstellar characteristics commonly observed in the slightly cooler G, K, and M supergiant is discussed. An ultraviolet survey was elected since UV features of Mg II and Fe II might persist in revealing outer atmosphere phenomena even among F supergiants. The encompassed spectral types F0 to G0, and luminosity classes Ib, Ia, and Ia-0. In addition, the usefulness of the emission line width-to-luminosity correlation for the G-M stars in both the Ca II and Mg II lines is examined.

Theory of Thomson scattering in inhomogeneous plasmas

NASA Astrophysics Data System (ADS)

Belyi, V. V.

2018-05-01

A self-consistent kinetic theory of Thomson scattering of an electromagnetic field by a nonuniform plasma is derived. We show that not only the imaginary part, but also the time and space derivatives of the real part of the dielectric susceptibility determine the amplitude and the width of the Thomson scattering spectral lines. As a result of inhomogeneity, these properties become asymmetric with respect to inversion of the sign of the frequency. Our theory provides a method of a remote probing and measurement of electron density gradients in plasma; this is based on the demonstrated asymmetry of the Thomson scattering lines.

UV photoabsorption cross sections of CO, N2, and SO2 for studies of the ISM and planetary atmospheres

NASA Technical Reports Server (NTRS)

Smith, Peter L.; Rufus, J.; Yoshino, K.; Parkinson, W. H.; Stark, Glenn; Pickering, Juliet C.; Thorne, A. P.

2002-01-01

We report high-resolution laboratory measurements of photoabsorption cross sections of CO, N2, and SO2 in the wavelength range 80 to 320 nm. The motivation is to provide the quantitative data that are needed to analyze observations of absorption by, and to model photochemical processes in, the interstellar medium and a number of planetary atmospheres. Because of the high resolution of the spectrometers used, we can minimize distortion of the spectrum that occurs when instrument widths are greater than the widths of spectral features being measured. In many cases, we can determine oscillator strengths of individual rotational lines - a unique feature of our work.

Solar off-limb line widths: Alfvén waves, ion-cyclotron waves, and preferential heating

NASA Astrophysics Data System (ADS)

Dolla, L.; Solomon, J.

2008-05-01

Context: Alfvén waves and ion-cyclotron absorption of high-frequency waves are frequently brought into models devoted to coronal heating and fast solar-wind acceleration. Signatures of ion-cyclotron resonance have already been observed in situ in the solar wind (HELIOS spacecrafts) and, recently, in the upper corona (UVCS/SOHO remote-sensing results). Aims: We propose a method to constrain both the Alfvén wave amplitude and the preferential heating induced by ion-cyclotron resonance, above a partially developed polar coronal hole observed with the SUMER/SOHO spectrometer. Methods: The instrumental stray light contribution is first substracted from the spectra. By supposing that the non-thermal velocity is related to the Alfvén wave amplitude, it is constrained through a density diagnostic and the gradient of the width of the Mg X 625 Å line. The temperatures of several coronal ions, as functions of the distance above the limb, are then determined by substracting the non-thermal component to the observed line widths. Results: The effect of stray light explains the apparent decrease with height in the width of several spectral lines, this decrease usually starting about 0.1-0.2 R_⊙ above the limb. This result rules out any direct evidence of damping of the Alfvén waves, often suggested by other authors. We also find that the ions with the smallest charge-to-mass ratios are the hottest ones at a fixed altitude and that they are subject to a stronger heating, as compared to the others, between 57´´ and 102´´ above the limb. This constitutes a serious clue to ion-cyclotron preferential heating.

Detection of chlorine with concentration of 0.18 kg/m{sup 3} in concrete by laser-induced breakdown spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sugiyama, K.; Fujii, T.; Matsumura, T.

2010-05-01

The chlorine concentration in concrete samples was measured by laser-induced breakdown spectroscopy (LIBS). One or two pulsed second harmonic Nd:YAG lasers ({lambda}=532 nm) were used for the generation of laser-induced breakdown, and an intensified CCD camera, spectrometer, and optical bundle fiber were used for spectral measurement. To maximize the spectral intensity of the chlorine fluorescence line at a wavelength of 837.59 nm, the time delay between laser irradiation and spectral measurement, the time delay between the two laser pulses in double-pulse measurement, and the gate width of the spectral measurement were optimized. The linear relationship between the spectral intensity ofmore » the chlorine fluorescence line and the chlorine concentration was verified for pressed samples with chlorine concentrations from 0.18 to 5.4 kg/m{sup 3}. The signal-to-noise ratio was higher than 2 for the sample with a chlorine concentration of 0.18 kg/m{sup 3} (0.008 wt. %). Thus, a chlorine concentration of 0.6 kg/m{sup 3}, at which the reinforcing bars in concrete structures start to corrode, can be detected. These results show that LIBS is effective for the quantitative measurement of chlorine concentration in concrete with high sensitivity.« less

Wavelength-Filter Based Spectral Calibrated Wave number - Linearization in 1.3 mm Spectral Domain Optical Coherence.

PubMed

Wijeisnghe, Ruchire Eranga Henry; Cho, Nam Hyun; Park, Kibeom; Shin, Yongseung; Kim, Jeehyun

2013-12-01

In this study, we demonstrate the enhanced spectral calibration method for 1.3 μm spectral-domain optical coherence tomography (SD-OCT). The calibration method using wavelength-filter simplifies the SD-OCT system, and also the axial resolution and the entire speed of the OCT system can be dramatically improved as well. An externally connected wavelength-filter is utilized to obtain the information of the wavenumber and the pixel position. During the calibration process the wavelength-filter is placed after a broadband source by connecting through an optical circulator. The filtered spectrum with a narrow line width of 0.5 nm is detected by using a line-scan camera. The method does not require a filter or a software recalibration algorithm for imaging as it simply resamples the OCT signal from the detector array without employing rescaling or interpolation methods. One of the main drawbacks of SD-OCT is the broadened point spread functions (PSFs) with increasing imaging depth can be compensated by increasing the wavenumber-linearization order. The sensitivity of our system was measured at 99.8 dB at an imaging depth of 2.1 mm compared with the uncompensated case.

Distributed seeding for narrow-line width hard x-ray free-electron lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Dinh Cong; Anisimov, Petr Mikhaylovich; Buechler, Cynthia Eileen

2015-09-09

We describe a new FEL line-narrowing technique called distributed seeding (DS), using Si(111) Bragg crystal monochromators to enhance the spectral brightness of the MaRIE hard X-ray freeelectron laser. DS differs from self-seeding in three important aspects. First, DS relies on spectral filtering of the radiation at multiple locations along the undulator, with a monochromator located every few power gain lengths. Second, DS performs filtering early in the exponential gain region before SASE spikes start to appear in the radiation longitudinal profile. Third, DS provides the option to select a wavelength longer than the peak of the SASE gain curve, whichmore » leads to improved spectral contrast of the seeded FEL over the SASE background. Timedependent Genesis simulations show the power-vs-z growth curves for DS exhibit behaviors of a seeded FEL amplifier, such as exponential growth region immediately after the filters. Of the seeding approaches considered, the two-stage DS spectra produce the highest contrast of seeded FEL over the SASE background and that the three-stage DS provides the narrowest linewidth with a relative spectral FWHM of 8 X 10 -5 .« less

Comprehensive Analysis of RXTE Data from Cyg X-1. Spectral Index-Quasi-Periodic Oscillation Frequency-Luminosity Correlations

NASA Technical Reports Server (NTRS)

Shaposhnikov, Nickolai; Titarchuk, Lev

2006-01-01

We present timing and spectral analysis of approx. 2.2 Ms of Rossi X-ray Time Explorer (RXTE) archival data from Cyg X-1. Using the generic Comptonization model we reveal that the spectrum of Cyg X-1 consists of three components: a thermal seed photon spectrum, a Comptonized part of the seed photon spectrum and the iron line. We find a strong correlation between 0.1-20 Hz frequencies of quasiperiodic oscillations (QPOs) and the spectral power-law index. Presence of two spectral phases (states) are clearly seen in the data when the spectral indices saturate at low and high values of QPO frequencies. This saturation effect was discovered earlier in a number of black hole candidate (BHC) sources and now we strongly confirm this phenomenon in Cyg X-1. In the soft state this index- QPO frequency correlation shows a saturation of the photon index Gamma approx. 2.1 at high values of the low frequency upsilon(sub L). The saturation level of Gamma approx. 2.1 is the lowest value found yet in BHCs. The bolometric luminosity does not show clear correlation with the index. We also show that Fe K(sub alpha) emission line strength (equivalent width, EW) correlates with the QPO frequency. EW increases from 200 eV in the low/hard state to 1.5 keV in the high/soft state. The revealed observational correlations allow us to propose a scenario for the spectral transition and iron line formation which occur in BHC sources. We also present the spectral state (the power-law index) evolution for eight years of Cyg X-1 observations by RXTE.

Spectral Variability of the Herbig Ae/Be Star HD 37806

NASA Astrophysics Data System (ADS)

Pogodin, M. A.; Pavlovskiy, S. E.; Kozlova, O. V.; Beskrovnaya, N. G.; Alekseev, I. Yu.; Valyavin, G. G.

2018-03-01

Results are reported from a spectroscopic study of the Herbig Ae/Be star HD 37806 from 2009 through 2017 using high resolution spectrographs at the Crimean Astrophysical Observatory and the OAN SPM Observatory in Mexico. 72 spectra of this object near the Hα, Hβ, HeI 5876 and D NaI lines are analyzed. The following results were obtained: 1. The type of spectral profile of the Hα line can change from P Cyg III to double emission and vice versa over a time scale on the order of a month. 2. Narrow absorption components are observed in the profiles of the Hα and D NaI lines with radial velocities that vary over a characteristic time on the order of a day. 3. On some days, the profiles of the Hβ, HeI 5876, and D NaI lines show signs of accretion of matter to the star with a characteristic lifetime of a few days. A possible interpretation of these phenomena was considered. The transformation of the Hα profile may be related to a change in the outer latitudinal width of the boundary of the wind zone. The narrow variable absorption lines may be caused by the rotation of local azimuthal inhomogeneities in the wind zone owing to the interaction of the disk with the star's magnetosphere in a propeller regime. Several current theoretical papers that predict the formation of similar inhomogeneous wind structures were examined. It is suggested that the episodes with signs of accretion in the spectral line profiles cannot be a consequence of the modulation of these profiles by the star's rotation but are more likely caused by sudden, brief changes in the accretion rate. These spectral observations of HD 37806 should be continued in a search for cyclical variability in the spectral parameters in order to identify direct signs of magnetospheric accretion and detect possible binary behavior in this object.

Lineshape measurements of He- β spectra on the ORION laser facility

DOE PAGES

Beiersdorfer, P.; Brown, G. V.; Shepherd, R.; ...

2016-10-25

Here, we have utilized a newly developed high-resolution X-ray spectrometer to measure the shapes of spectral lines produced from laser-irradiated targets on the Orion laser facility in the United Kingdom. We present measurements of the He-β spectra of chlorine and chromium from targets irradiated by either a long-pulse or a short-pulse laser beam. The experimental conditions provide a spread in plasma density ranging from about 10 19 to about 10 24 cm –3. We present spectral calculations that show that the relative intensities of the Li-like satellite lines can be used to infer the density in the lower range, especiallymore » if the lithiumlike satellite lines are well resolved. In addition, we use the Stark-broadened width of the He-β line to infer densities above about 10 22 cm –3. In the case of a short-pulse irradiated chromium foil, we find that the He-like chromium is produced at a density of almost 8 g/cm 3, i.e., solid density. In addition, we can infer the electron temperature from the observation of dielectronic recombination satellite lines.« less

On searching for observational manifestations of Alfvén waves in solar faculae

NASA Astrophysics Data System (ADS)

Kobanov, N. I.; Chupin, S. A.; Chelpanov, A. A.

2017-12-01

In an effort to detect torsional oscillations, we have studied the periodic half-width variations for several spectral lines in solar faculae. The duration of the series being analyzed was from 40 to 150 min. We have determined the dominant frequencies and amplitudes of the half-width oscillations and considered their phase relations to the intensity and line-of-sight velocity oscillations. Five-minute profile halfwidth oscillations with a peak-to-peak amplitude of ˜10 m ˚A are recorded with confidence in the upperphotospheric Si I 10 827 ˚A line in faculae. The chromospheric He I 10 830 A˚ and Hα line profiles shows ˜40-60 m ˚A variations in two frequency bands, 2.5-4 and 1-1.9 mHz. No center-to-limb dependence that, according to the theory, must accompany the torsional oscillations has been revealed in the behavior of the oscillation amplitudes. According to present views, these variations cannot be caused by periodic temperature and magnetic field changes. Our observations do not allow us to explain these variations by the sausage mode action either, which should manifest itself at the double frequency.

In-line flat-top comb filter based on a cascaded all-solid photonic bandgap fiber intermodal interferometer.

PubMed

Geng, Youfu; Li, Xuejin; Tan, Xiaoling; Deng, Yuanlong; Yu, Yongqin

2013-07-15

In this paper, an in-line comb filter with flat-top spectral response is proposed and constructed based on a cascaded all-solid photonic bandgap fiber modal interferometer. It consists of two short pieces of all-solid photonic bandgap fiber and two standard single-mode fibers as lead fibers with core-offset splices between them. The theoretical and experimental results demonstrated that by employing a cut and resplice process on the central position of all-solid photonic bandgap fiber, the interference spectra are well tailored and flat-top spectral profiles could be realized by the controllable offset amount of the resplice. The channel position also could be tuned by applying longitudinal torsion with up to 4 nm tuning range. Such a flat-top fiber comb filter is easy-to-fabricate and with a designable passband width and flat-top profile.

Hybrid interferometric/dispersive atomic spectroscopy of laser-induced uranium plasma

DOE PAGES

Morgan, Phyllis K.; Scott, Jill R.; Jovanovic, Igor

2015-12-19

An established optical emission spectroscopy technique, laser-induced breakdown spectroscopy (LIBS), holds promise for detection and rapid analysis of elements relevant for nuclear safeguards, nonproliferation, and nuclear power, including the measurement of isotope ratios. One such important application of LIBS is the measurement of uranium enrichment ( 235U/ 238U), which requires high spectral resolution (e.g., 25 pm for the 424.4 nm U II line). High-resolution dispersive spectrometers necessary for such measurements are typically bulky and expensive. We demonstrate the use of an alternative measurement approach, which is based on an inexpensive and compact Fabry–Perot etalon integrated with a low to moderatemore » resolution Czerny–Turner spectrometer, to achieve the resolution needed for isotope selectivity of LIBS of uranium in ambient air. Furthermore, spectral line widths of ~ 10 pm have been measured at a center wavelength 424.437 nm, clearly discriminating the natural from the highly enriched uranium.« less

Hα line shape in front of the limiter in the HT-6M tokamak

NASA Astrophysics Data System (ADS)

Wan, Baonian; Li, Jiangang; Luo, Jiarong; Xie, Jikang; Wu, Zhenwei; Zhang, Xianmei; HT-6M Group

1999-11-01

The Hα line shape in front of the limiter in the HT-6M tokamak is analysed by multi-Gaussian fitting. The energy distribution of neutral hydrogen atoms reveals that Hα radiation is contributed by Franck-Condon atoms, atoms reflected at the limiter surface and charge exchange. Multi-Gaussian fitting of the Hα spectral profile indicates contributions of 60% from reflection particles and 40% from molecule dissociation to recycling. Ion temperatures in central regions are obtained from the spectral width of charge exchange components. Dissociation of hydrogen molecules and reflection of particles at the limiter surface are dominant in edge recycling. Reduction of particle reflection at the limiter surface is important for controlling edge recycling. The measured profiles of neutral hydrogen atom density are reproduced by a particle continuity equation and a simplified one dimensional Monte Carlo simulation code.

Characterization and on-sky demonstration of an integrated photonic spectrograph for astronomy.

PubMed

Cvetojevic, N; Lawrence, J S; Ellis, S C; Bland-Hawthorn, J; Haynes, R; Horton, A

2009-10-12

We present results from the first on-sky demonstration of a prototype astronomical integrated photonic spectrograph (IPS) using the Anglo-Australian Telescope near-infrared imaging spectrometer (IRIS2) at Siding Spring Observatory to observe atmospheric molecular OH emission lines. We have succeeded in detecting upwards of 27 lines, and demonstrated the practicality of the IPS device for astronomy. Furthermore, we present a laboratory characterization of the device, which is a modified version of a commercial arrayed-waveguide grating multiplexer. We measure the spectral resolution full-width-half-maximum to be 0.75 +/- 0.05 nm (giving R = lambda/deltalambda = 2100 +/- 150 at 1500 nm). We find the free spectral range to be 57.4 +/- 0.6 nm and the peak total efficiency to be approximately 65%. Finally, we briefly discuss the future steps required to realize an astronomical instrument based on this technology concept.

Origin and Correction of Magnetic Field Inhomogeneity at the Interface in Biphasic NMR Samples

PubMed Central

Martin, Bryan T.; Chingas, G. C.

2012-01-01

The use of susceptibility matching to minimize spectral distortion of biphasic samples layered in a standard 5 mm NMR tube is described. The approach uses magic angle spinning (MAS) to first extract chemical shift differences by suppressing bulk magnetization. Then, using biphasic coaxial samples, magnetic susceptibilities are matched by titration with a paramagnetic salt. The matched phases are then layered in a standard NMR tube where they can be shimmed and examined. Line widths of two distinct spectral lines, selected to characterize homogeneity in each phase, are simultaneously optimized. Two-dimensional distortion-free, slice-resolved spectra of an octanol/water system illustrate the method. These data are obtained using a 2D stepped-gradient pulse sequence devised for this application. Advantages of this sequence over slice-selective methods are that acquisition efficiency is increased and processing requires only conventional software. PMID:22459062

Soft X-ray spectral features in the Seyfert 1 Galaxy NGC4051

NASA Technical Reports Server (NTRS)

Mihara, Tatehiro; Matsuoka, Masaru; Mushotzky, Richard F.; Kunieda, Hideyo; Otani, Chiko; Miyamoto, Sigenori; Yamauchi, Makoto

1994-01-01

We report ASCA observations of NGC 4051 during the PV phase. The time averaged X-ray spectrum is not well fit by a simple power law with an iron K-emission line and shows significant absorption-edge features most probably due to O VII and O VIII and a strong soft excess. This is the first direct measurement of edges in the spectrum of this object and confirms that the X-ray spectrum of NGC 4051 is modified by a 'warm' absorbing gas. The best fit underlying power law index in the 0.4-10 keV band is 1.88. A power law modified by a warm absorber model can partly explain the apparent soft excess and qualitatively fit the SIS spectrum. However, the addition of a black body of kT approx. = 0.1 keV improves the fit considerably. The 90% upper limit on the width of the iron line is 460 eV full width at half maximum (FWHM). Applying the fluorescent iron line model from an accretion disk gives an upper limit of 20 deg for the inclination of the disk.

Circumnuclear star formation in Mrk 42 mapped with Gemini Near-infrared Integral Field Spectrograph

NASA Astrophysics Data System (ADS)

Hennig, Moiré G.; Riffel, Rogemar A.; Dors, O. L.; Riffel, Rogerio; Storchi-Bergmann, Thaisa; Colina, Luis

2018-06-01

We present Gemini Near-infrared Integral Field Spectrograph (NIFS) observations of the inner 1.5 × 1.5 kpc2 of the narrow-line Seyfert 1 galaxy Mrk 42 at a spatial resolution of 60 pc and spectral resolution of 40 km s^{-1}. The emission-line flux and equivalent width maps clearly show a ring of circumnuclear star formation regions surrounding the nucleus with radius of ˜500 pc. The spectra of some of these regions show molecular absorption features which are probably of CN, TiO, or VO, indicating the presence of massive evolved stars in the thermally pulsing asymptotic giant branch phase. The gas kinematics of the ring is dominated by rotation in the plane of the galaxy, following the large-scale disc geometry, while at the nucleus an additional outflowing component is detected blueshifted by 300-500 km s^{-1}, relative to the systemic velocity of the galaxy. Based on the equivalent width of Br γ we find pieces of evidence of gradients in the age of H II regions along the ring of Mrk 42, favouring the pearls on a string scenario of star formation. The broad component of Pa β emission line presents a Full Width at Half Maximum of ˜1480 km s^{-1}, implying in a mass of ˜2.5 × 106 M⊙ for the central supermassive black hole. Based on emission-line ratios we conclude that besides the active galactic nucleus, Mrk 42 presents nuclear Starburst activity.

A Coordinated X-Ray and Optical Campaign of the Nearby Massive Binary Sigma Orionis Aa. II; X-Ray Variability

NASA Technical Reports Server (NTRS)

Nichols, J.; Huenemoerder, D. P.; Corcoran, M. F.; Waldron, W.; Naze, Y; Pollock, A. M. T.; Moffat, A. F. J.; Lauer, J.; Shenar, T.; Russell, C. M. P.;

Isotopic determination of uranium in soil by laser induced breakdown spectroscopy

DOE PAGES

Chan, George C. -Y.; Choi, Inhee; Mao, Xianglei; ...

2016-03-26

Laser-induced breakdown spectroscopy (LIBS) operated under ambient pressure has been evaluated for isotopic analysis of uranium in real-world samples such as soil, with U concentrations in the single digit percentage levels. The study addresses the requirements for spectral decomposition of 235U and 238U atomic emission peaks that are only partially resolved. Although non-linear least-square fitting algorithms are typically able to locate the optimal combination of fitting parameters that best describes the experimental spectrum even when all fitting parameters are treated as free independent variables, the analytical results of such an unconstrained free-parameter approach are ambiguous. In this work, five spectralmore » decomposition algorithms were examined, with different known physical properties (e.g., isotopic splitting, hyperfine structure) of the spectral lines sequentially incorporated into the candidate algorithms as constraints. It was found that incorporation of such spectral-line constraints into the decomposition algorithm is essential for the best isotopic analysis. The isotopic abundance of 235U was determined from a simple two-component Lorentzian fit on the U II 424.437 nm spectral profile. For six replicate measurements, each with only fifteen laser shots, on a soil sample with U concentration at 1.1% w/w, the determined 235U isotopic abundance was (64.6 ± 4.8)%, and agreed well with the certified value of 64.4%. Another studied U line - U I 682.691 nm possesses hyperfine structure that is comparatively broad and at a significant fraction as the isotopic shift. Thus, 235U isotopic analysis with this U I line was performed with spectral decomposition involving individual hyperfine components. For the soil sample with 1.1% w/w U, the determined 235U isotopic abundance was (60.9 ± 2.0)%, which exhibited a relative bias about 6% from the certified value. The bias was attributed to the spectral resolution of our measurement system - the measured line width for this U I line was larger than its isotopic splitting. In conclusion, although not the best emission line for isotopic analysis, this U I emission line is sensitive for element analysis with a detection limit of 500 ppm U in the soil matrix; the detection limit for the U II 424.437 nm line was 2000 ppm.« less

VizieR Online Data Catalog: FTS reference UV wavelengths of CrIII (Smillie+, 2008)

NASA Astrophysics Data System (ADS)

Smillie, D. G.; Pickering, J. C.; Smith, P. L.

2009-03-01

The Cr III spectrum was acquired in the wavenumber range 31596 to 63192cm-1, using the Imperial College (IC) VUV FTS, and a PDL as light source. The spectral resolution used, 0.12cm-1, was sufficient to fully resolve the Doppler broadened transition line profiles, for which the average unblended full-width at half maximum (FWHM) was just under 0.3cm-1. (1 data file).

Experimental and theoretical studies of the npσ1Σu+ and npπ1 Πu+ (n ⩾ 4,N‧ = 1 -6) states of D2: Energies, natural widths, absorption line intensities, and dynamics

NASA Astrophysics Data System (ADS)

Glass-Maujean, M.; Jungen, Ch.; Vasserot, A. M.; Schmoranzer, H.; Knie, A.; Kübler, S.; Ehresmann, A.; Ubachs, W.

2017-08-01

Over a thousand spectral lines in the photoexcitation spectrum of molecular deuterium (D2) to np1 Σu+ and 1Πu+ Rydberg levels (n ⩾ 4) were measured for rotational levels N‧ = 1 -6 in the 117 000-137 000 cm-1 spectral range by two different types of experiments at two synchrotron radiation sources: a vacuum ultraviolet (VUV) Fourier-transform (FT) spectrometer at SOLEIL, Paris and a 10 m-normal-incidence monochromator (NIM) at BESSY II, Berlin. The experimental energies, the absorption cross sections, Einstein A-coefficients, and line widths are compared with ab initio multi-channel quantum defect (MQDT) calculations for these levels. More than 350 R(0) or P(2) lines were assigned, some 280 R(1) or P(3) lines, some 270 R(2) or P(4) lines, over 100 R(3) or P(5) lines, over 90 R(4) lines, and 24 R(5) lines to extract information on the N‧ = 1 -6 excited levels. Transition energies were determined up to excitation energies of 137 000 cm-1 above the ground state, thereby extending earlier work by various authors and considerably improving the spectral accuracy (< 0.1 cm-1), leading to several reassignments. The absorption and the dissociation, ionization and fluorescence excitation cross sections from the NIM experiment are measured on absolute scale and are used to calibrate intensities in the VUV-FT spectra. The overall agreement between experiment and first principles calculations, without adjustable parameters, is excellent in view of the multi-state interferences treated within the MQDT-framework: For the low N‧ values the averaged deviations between those observed in the FT-SOLEIL spectra and those calculated with MQDT are ∼ 0.1 cm-1 with a spread of ∼ 0.5 cm-1. The line intensities in terms of Einstein coefficients are well represented in the MQDT-framework, as are the level widths representing the lifetimes associated with the sum of the three decay channels. These line intensities follow, in general, the 1 /n3 scaling behavior as characteristic in Rydberg series, but deviations occur and those are explained by MQDT. The decay dynamics of the excited N Rydberg levels is analyzed on the basis of the measured quantum yields for ionization, dissociation and fluorescence observed in the NIM experiment in terms of absolute cross sections for the distinctive channels. In particular in the n = 4 manifolds dissociation is found to play a major role, where in the n = 5 manifolds the behavior is most erratic due to strong competition between decay channels. At n = 6 , ionization takes over as the dominant channel. Despite the excellent agreement between observations and the outcome of the MQDT calculations for both level energies and dynamics, some pronounced deviations are found as in the splitting of the 5 pπ, v = 4 -6, N‧ = 1 levels. The shortcomings of the MQDT calculations are ascribed to the treatment of the excited states in terms of a 1 snp single electron configuration, therewith neglecting possible interferences with 1 snf or 2 s core excited states. Some 27 lines remained unassigned; in view of their observation in fluorescence it is stipulated that these lines probe levels in the nf manifold.

Spectroscopy of an unusual emission line M star

NASA Technical Reports Server (NTRS)

Schneider, Donald P.; Greenstein, Jesse L.; Schmidt, Maarten; Gunn, James E.

1991-01-01

Moderate-resolution spectroscopy of an unusual late-type faint emission-line star, PC 0025 + 0047, is reported. A very strong (greater than 250 A equivalent width) an H-alpha emission line was detected by the present automated line search algorithm. The spectrum was found to have two unresolved emission lines (H-alpha and H-beta) near zero velocity, superposed on the absorption spectrum of a very red M dwarf which has strong K I, and relatively weak bands of TiO. From the weakness of the subordinate lines of Na I (8192 A) and other spectral features, it is inferred that it is definitely a cooler, and probably fainter, analog of LHS 2924. The strength of the emission lines indicates that PC 0025 + 0447 is very young and may be a fading predecessor brown drawf at an estimated M(bol) approaching 14m at a distance of about 60 pc.

Three-dimensional stereoscopic analysis of a coronal mass ejection and comparison with UV spectroscopic data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Susino, Roberto; Bemporad, Alessandro; Dolei, Sergio, E-mail: susino@oato.inaf.it, E-mail: sdo@oact.inaf.it

2014-07-20

A three-dimensional (3D) reconstruction of the 2007 May 20 partial-halo coronal mass ejection (CME) has been made using STEREO/EUVI and STEREO/COR1 coronagraphic images. The trajectory and kinematics of the erupting filament have been derived from Extreme Ultraviolet Imager (EUVI) image pairs with the 'tie-pointing' triangulation technique, while the polarization ratio technique has been applied to COR1 data to determine the average position and depth of the CME front along the line of sight. This 3D geometrical information has been combined for the first time with spectroscopic measurements of the O VI λλ1031.91, 1037.61 line profiles made with the Ultraviolet Coronagraphmore » Spectrometer (UVCS) on board the Solar and Heliospheric Observatory. Comparison between the prominence trajectory extrapolated at the altitude of UVCS observations and the core transit time measured from UVCS data made possible a firm identification of the CME core observed in white light and UV with the prominence plasma expelled during the CME. Results on the 3D structure of the CME front have been used to calculate synthetic spectral profiles of the O VI λ1031.91 line expected along the UVCS slit, in an attempt to reproduce the measured line widths. Observed line widths can be reproduced within the uncertainties only in the peripheral part of the CME front; at the front center, where the distance of the emitting plasma from the plane of the sky is greater, synthetic widths turn out to be ∼25% lower than the measured ones. This provides strong evidence of line broadening due to plasma heating mechanisms in addition to bulk expansion of the emitting volume.« less

Hyperfine structure measurements of neutral iodine atom (127I) using Fourier Transform Spectrometry

NASA Astrophysics Data System (ADS)

Ashok, Chilukoti; Vishwakarma, S. R.; Bhatt, Himal; Ankush, B. K.; Deo, M. N.

2018-01-01

We report the hyperfine Structure (hfs) splitting observations of neutral iodine atom (II) in the 6000 - 10,000 cm-1 near infrared spectral region. The measurements were carried out using a high-resolution Fourier Transform Spectrometer (FTS), where an electrodeless discharge lamp (EDL), excited using microwaves, was employed as the light source and InGaAs as the light detector. A specially designed setup was used to lower the plasma temperature of the medium so as to reduce the Doppler width and consequently to increase the spectral resolution of hfs components. A total of 183 lines with hfs splitting have been observed, out of which hfs in 53 spectral lines are reported for the first time. On the basis of hfs analysis, we derived the magnetic dipole and electric quadrupole coupling constants, A and B respectively for 30 even and 30 odd energy levels and are compared with the values available in the literature. New hfs values for 5 even and 4 odd levels are also reported here for the first time.

Automated road network extraction from high spatial resolution multi-spectral imagery

NASA Astrophysics Data System (ADS)

Zhang, Qiaoping

For the last three decades, the Geomatics Engineering and Computer Science communities have considered automated road network extraction from remotely-sensed imagery to be a challenging and important research topic. The main objective of this research is to investigate the theory and methodology of automated feature extraction for image-based road database creation, refinement or updating, and to develop a series of algorithms for road network extraction from high resolution multi-spectral imagery. The proposed framework for road network extraction from multi-spectral imagery begins with an image segmentation using the k-means algorithm. This step mainly concerns the exploitation of the spectral information for feature extraction. The road cluster is automatically identified using a fuzzy classifier based on a set of predefined road surface membership functions. These membership functions are established based on the general spectral signature of road pavement materials and the corresponding normalized digital numbers on each multi-spectral band. Shape descriptors of the Angular Texture Signature are defined and used to reduce the misclassifications between roads and other spectrally similar objects (e.g., crop fields, parking lots, and buildings). An iterative and localized Radon transform is developed for the extraction of road centerlines from the classified images. The purpose of the transform is to accurately and completely detect the road centerlines. It is able to find short, long, and even curvilinear lines. The input image is partitioned into a set of subset images called road component images. An iterative Radon transform is locally applied to each road component image. At each iteration, road centerline segments are detected based on an accurate estimation of the line parameters and line widths. Three localization approaches are implemented and compared using qualitative and quantitative methods. Finally, the road centerline segments are grouped into a road network. The extracted road network is evaluated against a reference dataset using a line segment matching algorithm. The entire process is unsupervised and fully automated. Based on extensive experimentation on a variety of remotely-sensed multi-spectral images, the proposed methodology achieves a moderate success in automating road network extraction from high spatial resolution multi-spectral imagery.

Thermal and Nonthermal Contributions to the Solar Flare X-Ray Flux

NASA Technical Reports Server (NTRS)

Dennis, Brian R.; Phillips, K. J. H.; Sylwester, Janusz; Sylwester, Barbara; Schwartz, Richard A.; Tolbert, A. Kimberley

2004-01-01

The relative thermal and nonthermal contributions to the total energy budget of a solar flare are being determined through analysis of RHESSI X-ray imaging and spectral observations in the energy range from approx. 5 to approx. 50 keV. The classic ways of differentiating between the thermal and nonthermal components - exponential vs. sources - can now be combined for individual flares. In addition, RHESSI's sensitivity down to approx. 4 keV and energy resolution of approx. 1 keV FWHM allow the intensities and equivalent widths of the complex of highly ionized iron lines at approx. 6.7 keV and the complex of highly ionized iron and nickel lines at approx. 8 keV to be measured as a function of time. Using the spectral line and continuum intensities from the Chianti (version 4.2) atomic code, the thermal component of the total flare emission can be more reliably separated from the nonthermal component in the measured X-ray spectrum. The abundance of iron can also be determined from RHESSI line-to-continuum measurements as a function of time during larger flares. Results will be shown of the intensity and equivalent widths of these line complexes for several flares and the temperatures, emission measures, and iron abundances derived from them. Comparisons will be made with 6.7-keV Fe-line fluxes measured with the RESIK bent crystal spectrometer on the Coronas-F spacecraft operating in third order during the peak times of three flares (2002 May 31 at 00:12 UT, 2002 December 2 at 19:26 UT, and 2003 April 26 at 03:OO UT). During the rise and decay of these flares, RESIK was operating in first order allowing the continuum flux to be measured between 2.9 and 3.7 keV for comparison with RHESSI fluxes at its low-energy end.

Pilot Search for 54-MHz Maser Emission from Interstellar Hydroxyl Using LOFAR

NASA Astrophysics Data System (ADS)

Hoffman, Ian M.; Heald, G.; Oonk, R.; McKean, J.; Mol, J.; Hessels, J.; Toribio, C.; LOFAR Collaboration

2014-01-01

We present the results of the most sensitive search to date for the two 54-MHz spectral lines of the hydroxyl (OH) molecule. These are the preliminary results of a larger, planned observational campaign. The splitting of the rotational ground state of the hydroxyl molecule gives rise to the four familiar 1.7-GHz transitions by which OH is known in the interstellar medium. There are also two magnetic-dipole transitions among these states at frequencies of 53.2 MHz and 55.1 MHz. These 54-MHz transitions have never been detected astronomically. Because of the relative weakness of the magnetic-dipole emission process, it is expected that only maser emission will generate a detectable 54-MHz signal. Two previous searches have been conducted by other authors with other instruments toward Galactic sources of known 1720-MHz OH maser emission: three sources were searched at 55.1 MHz and two other sources were searched at 53.2 MHz, resulting in upper limits of approximately 30 Jy for spectral channels of 2 km/s in width. In preparation for our future observational campaign that will apply the unprecedented sensitivity of LOFAR to the search for 54-MHz OH emission, we conducted a pilot project using six hours of Commissioning Time. These observations employed 21 48-element stations and produced a spectral resolution of approximately 0.5 km/s for both the 53.2- and 55.1-MHz lines. This spectral resolution is a considerable improvement over previous searches since it is suitable both for resolving the characteristically narrow width of maser lines and for identifying radiofrequency interference. In our pilot observations, no emission was detected at either frequency with an upper limit of approximately 3 Jy. We observed the Galactic sources W75N and W3(OH), neither of which have been searched previously at either frequency. We discuss the astrophysical implications of these sensitive non-detections. LOFAR, the Low Frequency Array designed and constructed by ASTRON, has facilities in several countries, that are owned by various parties (each with their own funding sources), and that are collectively operated by the International LOFAR Telescope (ILT) foundation under a joint scientific policy.

Properties of laser-produced GaAs plasmas measured from highly resolved X-ray line shapes and ratios

NASA Astrophysics Data System (ADS)

Seely, J. F.; Fein, J.; Manuel, M.; Keiter, P.; Drake, P.; Kuranz, C.; Belancourt, Patrick; Ralchenko, Yu.; Hudson, L.; Feldman, U.

2018-03-01

The properties of hot, dense plasmas generated by the irradiation of GaAs targets by the Titan laser at Lawrence Livermore National Laboratory were determined by the analysis of high resolution K shell spectra in the 9 keV to 11 keV range. The laser parameters, such as relatively long pulse duration and large focal spot, were chosen to produce a steady-state plasma with minimal edge gradients, and the time-integrated spectra were compared to non-LTE steady state spectrum simulations using the FLYCHK and NOMAD codes. The bulk plasma streaming velocity was measured from the energy shifts of the Ga He-like transitions and Li-like dielectronic satellites. The electron density and the electron energy distribution, both the thermal and the hot non-thermal components, were determined from the spectral line ratios. After accounting for the spectral line broadening contributions, the plasma turbulent motion was measured from the residual line widths. The ionization balance was determined from the ratios of the He-like through F-like spectral features. The detailed comparison of the experimental Ga spectrum and the spectrum simulated by the FLYCHK code indicates two significant discrepancies, the transition energy of a Li-like dielectronic satellite (designated t) and the calculated intensity of a He-like line (x), that should lead to improvements in the kinetics codes used to simulate the X-ray spectra from highly-charged ions.

[The backgroud sky subtraction around [OIII] line in LAMOST QSO spectra].

PubMed

Shi, Zhi-Xin; Comte, Georges; Luo, A-Li; Tu, Liang-Ping; Zhao, Yong-Heng; Wu, Fu-Chao

2014-11-01

At present, most sky-subtraction methods focus on the full spectrum, not the particular location, especially for the backgroud sky around [OIII] line which is very important to low redshift quasars. A new method to precisely subtract sky lines in local region is proposed in the present paper, which sloves the problem that the width of Hβ-[OIII] line is effected by the backgroud sky subtraction. The exprimental results show that, for different redshift quasars, the spectral quality has been significantly improved using our method relative to the original batch program by LAMOST. It provides a complementary solution for the small part of LAMOST spectra which are not well handled by LAMOST 2D pipeline. Meanwhile, This method has been used in searching for candidates of double-peaked Active Galactic Nuclei.

MODTRAN3: Suitability as a flux-divergence code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, G.P.; Chetwynd, J.H.; Wang, J.

1995-04-01

The Moderate Resolution Atmospheric Radiance and Transmittance Model (MODTRAN3) is the developmental version of MODTRAN and MODTRAN2. The Geophysics Directorate, Phillips Laboratory, released a beta version of this model in October 1994. It encompasses all the capabilities of LOWTRAN7, the historic 20 cm{sup -1} resolution (full width at half maximum, FWHM) radiance code, but incorporates a much more sensitive molecular band model with 2 cm{sup -1} resolution. The band model is based directly upon the HITRAN spectral parameters, including both temperature and pressure (line shape) dependencies. Validation against full Voigt line-by-line calculations (e.g., FASCODE) has shown excellent agreement. In addition,more » simple timing runs demonstrate potential improvement of more than a factor of 100 for a typical 500 cm{sup -1} spectral interval and comparable vertical layering. Not only is MODTRAN an excellent band model for {open_quotes}full path{close_quotes} calculations (that is, radiance and/or transmittance from point A to point B), but it replicates layer-specific quantities to a very high degree of accuracy. Such layer quantities, derived from ratios and differences of longer path MODTRAN calculations from point A to adjacent layer boundaries, can be used to provide inversion algorithm weighting functions or similarly formulated quantities. One of the most exciting new applications is the rapid calculation of reliable IR cooling rates, including species, altitude, and spectral distinctions, as well as the standard spectrally integrated quantities. Comparisons with prior line-by-line cooling rate calculations are excellent, and the techniques can be extended to incorporate global climatologies of both standard and trace atmospheric species.« less

Line transport in turbulent atmosphere

NASA Astrophysics Data System (ADS)

Nikoghossian, Artur

We consider the spectral line transfer in turbulent atmospheres with a spatially correlated velocity field. Both the finite and semi-infinite media are treated. In finding the observed intensities we first deal with the problem for determining the mean intensity of radiation emerging from the medium for a fixed value of turbulent velocity at its boundary. New approach proposed in solving this problem is based on invariant imbedding technique which yields the solution of the proper problems for a family of media of different optical thicknesses and allows tackling different kinds of inhomogeneous problems. The dependence of the line profile, integral intensity and the line width on the mean correlation length and average value of the hydrodynamic velocity is studied. It is shown that the transition from a micro-turbulent regime to a macro-turbulent one occurs within a comparatively narrow range of variation in the correlation length. The diffuse reflection of the line radiation from a one-dimensional semi-infinite turbulent atmosphere is examined. In addition to the observed spectral line profile, statistical averages describing the diffusion process in the atmosphere (mean number of scattering events, average time spent by a diffusing photon in the medium) are determined. The dependence of these quantities on the average hydrodynamic velocity and correlation coefficient is studied.

Line Transport in Turbulent Atmospheres

NASA Astrophysics Data System (ADS)

Nikoghossian, A. G.

2017-07-01

The spectral line transfer in turbulent atmospheres with a spatially correlated velocity field is examined. Both the finite and semi-infinite media are treated. In finding the observed intensities we first deal with the problem for determining the mean intensity of radiation emerging from the medium for a fixed value of turbulent velocity at its boundary. A new approach proposed for solving this problem is based on the invariant imbedding technique which yields the solution of the proper problems for a family of media of different optical thicknesses and allows tackling different kinds of inhomogeneous problems. The dependence of the line profile, integral intensity, and the line width on the mean correlation length and the average value of the hydrodynamic velocity is studied. It is shown that the transition from a micro-turbulent regime to a macro-turbulence occurs within a comparatively narrow range of variation in the correlation length . Ambartsumian's principle of invariance is used to solve the problem of diffuse reflection of the line radiation from a one-dimensional semi-infinite turbulent atmosphere. In addition to the observed spectral line profile, statistical averages describing the diffusion process in the atmosphere (mean number of scattering events, average time spent by a diffusing photon in the medium) are determined. The dependence of these quantities on the average hydrodynamic velocity and correlation coefficient is studied.

Hyperspectral light sheet microscopy

NASA Astrophysics Data System (ADS)

Jahr, Wiebke; Schmid, Benjamin; Schmied, Christopher; Fahrbach, Florian O.; Huisken, Jan

2015-09-01

To study the development and interactions of cells and tissues, multiple fluorescent markers need to be imaged efficiently in a single living organism. Instead of acquiring individual colours sequentially with filters, we created a platform based on line-scanning light sheet microscopy to record the entire spectrum for each pixel in a three-dimensional volume. We evaluated data sets with varying spectral sampling and determined the optimal channel width to be around 5 nm. With the help of these data sets, we show that our setup outperforms filter-based approaches with regard to image quality and discrimination of fluorophores. By spectral unmixing we resolved overlapping fluorophores with up to nanometre resolution and removed autofluorescence in zebrafish and fruit fly embryos.

Hyperspectral light sheet microscopy.

PubMed

Jahr, Wiebke; Schmid, Benjamin; Schmied, Christopher; Fahrbach, Florian O; Huisken, Jan

2015-09-02

To study the development and interactions of cells and tissues, multiple fluorescent markers need to be imaged efficiently in a single living organism. Instead of acquiring individual colours sequentially with filters, we created a platform based on line-scanning light sheet microscopy to record the entire spectrum for each pixel in a three-dimensional volume. We evaluated data sets with varying spectral sampling and determined the optimal channel width to be around 5 nm. With the help of these data sets, we show that our setup outperforms filter-based approaches with regard to image quality and discrimination of fluorophores. By spectral unmixing we resolved overlapping fluorophores with up to nanometre resolution and removed autofluorescence in zebrafish and fruit fly embryos.

Full-range k-domain linearization in spectral-domain optical coherence tomography.

PubMed

Jeon, Mansik; Kim, Jeehyun; Jung, Unsang; Lee, Changho; Jung, Woonggyu; Boppart, Stephen A

2011-03-10

A full-bandwidth k-domain linearization method for spectral-domain optical coherence tomography (SD-OCT) is demonstrated. The method uses information of the wavenumber-pixel-position provided by a translating-slit-based wavelength filter. For calibration purposes, the filter is placed either after a broadband source or at the end of the sample path, and the filtered spectrum with a narrowed line width (∼0.5 nm) is incident on a line-scan camera in the detection path. The wavelength-swept spectra are co-registered with the pixel positions according to their central wavelengths, which can be automatically measured with an optical spectrum analyzer. For imaging, the method does not require a filter or a software recalibration algorithm; it simply resamples the OCT signal from the detector array without employing rescaling or interpolation methods. The accuracy of k-linearization is maximized by increasing the k-linearization order, which is known to be a crucial parameter for maintaining a narrow point-spread function (PSF) width at increasing depths. The broadening effect is studied by changing the k-linearization order by undersampling to search for the optimal value. The system provides more position information, surpassing the optimum without compromising the imaging speed. The proposed full-range k-domain linearization method can be applied to SD-OCT systems to simplify their hardware/software, increase their speed, and improve the axial image resolution. The experimentally measured width of PSF in air has an FWHM of 8 μm at the edge of the axial measurement range. At an imaging depth of 2.5 mm, the sensitivity of the full-range calibration case drops less than 10 dB compared with the uncompensated case.

2.5 MHz Line-Width High-energy, 2 Micrometer Coherent Wind Lidar Transmitter

NASA Technical Reports Server (NTRS)

Petros, Mulugeta; Yu, Jirong; Trieu, Bo; Bai, Yingxin; Petzar, Paul; Singh, Upendra N.; Reithmaier, Karl

2007-01-01

2 micron solid-state lasers are the primary choice for coherent Doppler wind detection. As wind lidars, they are used for wake vortex and clear air turbulence detection providing air transport safety. In addition, 2 micron lasers are one of the candidates for CO2 detection lidars. The rich CO2 absorption line around 2 micron, combined with the long upper state life of time, has made Ho based 2 micron lasers a viable candidate for CO2 sensing DIAL instrument. The design and fabrication of a compact coherent laser radar transmitter for Troposphere wind sensing is under way. This system is hardened for ground as well as airborne applications. As a transmitter for a coherent wind lidar, this laser has stringent spectral line width and beam quality requirements. Although the absolute wavelength does not have to be fixed for wind detection, to maximize return signal, the output wavelength should avoid atmospheric CO2 and H2O absorption lines. The base line laser material is Ho:Tm:LuLF which is an isomorph of Ho:Tm:YLF. LuLF produces 20% more output power than Ho:Tm:YLF. In these materials the Tm absorption cross-section, the Ho emission cross-section, the Tm to Ho energy transfer parameters and the Ho (sup 5) I (sub 7) radiative life time are all identical. However, the improved performance of the LuLF is attributed to the lower thermal population in the (sup 5) I (sub 8) manifold. It also provides higher normal mode to Q-switch conversion than YLF at high pump energy indicating a lower up-conversion. The laser architecture is composed of a seed laser, a ring oscillator, and a double pass amplifier. The seed laser is a single longitudinal mode with a line width of 13 KHz. The 100mJ class oscillator is stretched to 3 meters to accommodate the line-width requirement without compromising the range resolution of the instrument. The amplifier is double passed to produce greater than 300mJ energy.

The excited J = 01 Σu+ levels of D2: Measurements and ab initio quantum defect study

NASA Astrophysics Data System (ADS)

Glass-Maujean, M.; Jungen, Ch.; Dickenson, G. D.; de Oliveira, N.; Ubachs, W.

2016-02-01

The DESIRS beamline of the SOLEIL synchrotron facility, equipped with a vacuum ultraviolet Fourier-transform spectrometer has been used to measure P (N″ = 1) (N -N″ = - 1) absorption transitions of the D2 molecule. Some 44 P-lines were assigned and their transition frequencies determined up to excitation energies of 134,000 cm-1 above the ground state, thereby extending the earlier work by various authors, and considerably improving the spectral accuracy (<0.1 cm-1). The assignments have been aided by first principles multichannel quantum defect theory (MQDT) calculations. These calculations also provide predictions of the autoionization widths of the upper levels which agree well with the observed resonance widths.

Dynamic spectral shifts of molecular anions in organic glasses. [Pulse radiolysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huddleston, R.K.; Miller, J.R.

1982-06-24

Time-dependent spectra of the radical anions of pyromellitic dianhydride and p-dinitrobenzene have been observed after formation by pulse radiolysis in frozen 2-methyltetrahydrofuran and triacetin glasses. At temperatures near the glass transition, the spectra shift toward the blue over the entire observed time range 100 ns to 100 s), while at temperatures well below the glass transition, the spectral shifts can be stopped or greatly slowed. The magnitudes of the shifts are not large (typically approx. = to 10 nm), but because they are larger than the vibrational line widths, dramatic kinetics may be observed: the absorbance grows or decays bymore » more than a factor of five at some wavelengths. The observations are consistent with a solvent molecule reorientation mechanism for spectral shifts of molecular ions in low-temperature organic glasses. 6 figures.« less

Creation of Rydberg Polarons in a Bose Gas

NASA Astrophysics Data System (ADS)

Camargo, F.; Schmidt, R.; Whalen, J. D.; Ding, R.; Woehl, G.; Yoshida, S.; Burgdörfer, J.; Dunning, F. B.; Sadeghpour, H. R.; Demler, E.; Killian, T. C.

2018-02-01

We report spectroscopic observation of Rydberg polarons in an atomic Bose gas. Polarons are created by excitation of Rydberg atoms as impurities in a strontium Bose-Einstein condensate. They are distinguished from previously studied polarons by macroscopic occupation of bound molecular states that arise from scattering of the weakly bound Rydberg electron from ground-state atoms. The absence of a p -wave resonance in the low-energy electron-atom scattering in Sr introduces a universal behavior in the Rydberg spectral line shape and in scaling of the spectral width (narrowing) with the Rydberg principal quantum number, n . Spectral features are described with a functional determinant approach (FDA) that solves an extended Fröhlich Hamiltonian for a mobile impurity in a Bose gas. Excited states of polyatomic Rydberg molecules (trimers, tetrameters, and pentamers) are experimentally resolved and accurately reproduced with a FDA.

X-ray stars observed in LAMOST spectral survey

NASA Astrophysics Data System (ADS)

Lu, Hong-peng; Zhang, Li-yun; Han, Xianming L.; Shi, Jianrong

2018-05-01

X-ray stars have been studied since the beginning of X-ray astronomy. Investigating and studying the chromospheric activity from X-ray stellar optical spectra is highly significant in providing insights into stellar magnetic activity. The big data of LAMOST survey provides an opportunity for researching stellar optical spectroscopic properties of X-ray stars. We inferred the physical properties of X-ray stellar sources from the analysis of LAMOST spectra. First, we cross-matched the X-ray stellar catalogue (12254 X-ray stars) from ARXA with LAMOST data release 3 (DR3), and obtained 984 good spectra from 713 X-ray sources. We then visually inspected and assigned spectral type to each spectrum and calculated the equivalent width (EW) of Hα line using the Hammer spectral typing facility. Based on the EW of Hα line, we found 203 spectra of 145 X-ray sources with Hα emission above the continuum. For these spectra we also measured the EWs of Hβ, Hγ, Hδ and Ca ii IRT lines of these spectra. After removing novae, planetary nebulae and OB-type stars, we found there are 127 X-ray late-type stars with Hα line emission. By using our spectra and results from the literature, we found 53 X-ray stars showing Hα variability; these objects are Classical T Tauri stars (CTTs), cataclysmic variables (CVs) or chromospheric activity stars. We also found 18 X-ray stars showing obvious emissions in the Ca ii IRT lines. Of the 18 X-ray stars, 16 are CTTs and 2 are CVs. Finally, we discussed the relationships between the EW of Hα line and X-ray flux.

Spectral features of tidal disruption candidates and alternative origins for such transient flares

NASA Astrophysics Data System (ADS)

Saxton, Curtis J.; Perets, Hagai B.; Baskin, Alexei

2018-03-01

UV and optically selected candidates for stellar tidal disruption events (TDEs) often exhibit broad spectral features (He II emission, H α emission, or absorption lines) on a blackbody-like continuum (104 K≲ T≲ 105 K). The lines presumably emit from TDE debris or circumnuclear clouds photoionized by the flare. Line velocities however are much lower than expected from a stellar disruption by supermassive black hole (SMBH), and are somewhat faster than expected for the broad line region (BLR) clouds of a persistently active galactic nucleus (AGN). The distinctive spectral states are not strongly related to observed luminosity and velocity, nor to SMBH mass estimates. We use exhaustive photoionization modelling to map the domain of fluxes and cloud properties that yield (e.g.) an He-overbright state where a large He II(4686 Å)/H α line ratio creates an illusion of helium enrichment. Although observed line ratios occur in a plausible minority of cases, AGN-like illumination cannot reproduce the observed equivalent widths. We therefore propose to explain these properties by a light-echo photoionization model: the initial flash of a hot blackbody (detonation) excites BLR clouds, which are then seen superimposed on continuum from a later, expanded, cooled stage of the luminous source. The implied cloud mass is substellar, which may be inconsistent with a TDE. Given these and other inconsistencies with TDE models (e.g. host-galaxies distribution) we suggest to also consider alternative origins for these nuclear flares, which we briefly discuss (e.g. nuclear supernovae and starved/subluminous AGNs).

Nanocell with a pressure-controlled Rb atomic vapor column thickness: Critical influence of the thickness on optical processes

NASA Astrophysics Data System (ADS)

Sargsyan, A.; Amiryan, A.; Cartaleva, S.; Sarkisyan, D.

2017-07-01

A new device is designed: it consists of a nanocell (NC) filled with Rb atom vapors and placed in a vacuum chamber. When the pressure in the chamber changes in the range 0-1 atm, the NC thickness is smoothly varied in the range L = 140-1700 nm, which is caused by the pressure-induced deformation of thin garnet windows in the chamber. The pressure dependence has excellent reproducibility even after many hundreds of cycles of letting in of air and its complete pumping out from the chamber. The accuracy of setting required thickness L is much better than in the wedge-gap NCs to be moved mechanically that were used earlier. The processes of Faraday rotation (FR) of a polarization plane, resonance absorption, and fluorescence are studied using the D 1-line narrow-band continuous laser radiation when the thickness changes from L = λ/2 (398 nm) to L = 2λ (1590 nm) at a step λ/2. The FR signal is shown to be maximal at L = λ/2 and 3λ/2 and to have the minimum spectral width (≈60 MHz). At L = λ and 2λ, the FR signal is minimal and has the maximum spectral width (≈200 MHz). The resonance absorption demonstrates the same oscillating behavior; however, the effect in the case of FR is much more pronounced. The oscillating effect is absent for resonance fluorescence: its spectral width and amplitude increase monotonically with L. The detected effects are explained and possible applications are noted.

FIBER AND INTEGRATED OPTICS. FIBER WAVEGUIDE DEVICES: Fiber Michelson interferometer with a 50-km difference between its arms

NASA Astrophysics Data System (ADS)

Dianov, Evgenii M.; Kuznetsov, A. V.; Makarenko, A. Yu; Okhotnikov, O. G.; Prokhorov, A. M.; Shcherbakov, E. A.

1990-12-01

Single-mode fiber waveguides were used in constructing a Michelson interferometer with a 50-km difference between its arm lengths. An analysis was made of its resolving power as a function of the parameters of the optical part and of the characteristics of the electronic apparatus used in the system. The width of a spectral emission line of a semiconductor laser with a distributed Rayleigh fiber resonator was determined.

Suzaku Observations of the Ultracompact Binary System 4U1626-67

NASA Technical Reports Server (NTRS)

Camero-Arranz, A.; Pottschmidt, K.; Finger, M. H.; Wilson-Hodge, C. A.; Marcu, D. M.

2011-01-01

The accretion-powered pulsar 4U1626-67 experienced a new torque reversal at the beginning of 2008, after about 18 years of steadily spinning down. We present a spectral analysis of this source using two pointed observations performed by Suzaku in 2006 March and in 2010 September. We confirm with Suzaku the presence of a strong emission-line complex centered on 1 keV, with the strongest line being the hydrogen-like Ne Ly- alpha at 1.025(1.5) keV. We were able to resolve this complex with up to eight emission lines. A dramatic increase of the equivalent width of the Ne Ly-alpha 1.021 keV after the 2008 torque reversal occurred, reaching almost the same value measured by ASCA in 1993. In addition, we confirm the general decrease trend of the equivalent widths during the spin-down period. We also report on the detection of a cyclotron line feature centered at approx 37 keV. In spite of the fact that a dramatic increase of the X-ray luminosity (0.5-100 keV) of a factor of approx 3.5 occurred between these two observations, no significant change in the energy of the cyclotron line feature was observed. However, the intensity of the approx 1 keV line complex increased by an overall factor of approx 10.

A new method to determine the interstellar reddening towards WN stars

NASA Technical Reports Server (NTRS)

Conti, Peter S.; Morris, Patrick W.

1990-01-01

An empirical approach to determine the redding in WN stars is presented, in which the measured strengths of the emission lines of He II at 1640 and 4686 A are used to estimate the extinction. The He II emission lines at these wavelengths are compared for a number of WN stars in the Galaxy and the LMC. It is shown that the equivalent width ratios are single valued and are independent of the spectral subtypes. The reddening for stars in the Galaxy is derived using a Galactic extinction law and observed line flux ratios, showing good agreement with previous determinations of reddening. The possible application of the method to study the absorption properties of the interstellar medium in more distant galaxies is discussed.

AUTONOMOUS GAUSSIAN DECOMPOSITION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lindner, Robert R.; Vera-Ciro, Carlos; Murray, Claire E.

2015-04-15

We present a new algorithm, named Autonomous Gaussian Decomposition (AGD), for automatically decomposing spectra into Gaussian components. AGD uses derivative spectroscopy and machine learning to provide optimized guesses for the number of Gaussian components in the data, and also their locations, widths, and amplitudes. We test AGD and find that it produces results comparable to human-derived solutions on 21 cm absorption spectra from the 21 cm SPectral line Observations of Neutral Gas with the EVLA (21-SPONGE) survey. We use AGD with Monte Carlo methods to derive the H i line completeness as a function of peak optical depth and velocitymore » width for the 21-SPONGE data, and also show that the results of AGD are stable against varying observational noise intensity. The autonomy and computational efficiency of the method over traditional manual Gaussian fits allow for truly unbiased comparisons between observations and simulations, and for the ability to scale up and interpret the very large data volumes from the upcoming Square Kilometer Array and pathfinder telescopes.« less

The effect of temperature and dot size on the spectral properties of colloidal InP/ZnS core-shell quantum dots.

PubMed

Narayanaswamy, Arun; Feiner, L F; Meijerink, A; van der Zaag, P J

2009-09-22

Visual color changes between 300 and 510 K were observed in the photoluminescence (PL) of colloidal InP/ZnS core-shell nanocrystals. A subsequent study of PL spectra in the range 2-510 K and fitting the temperature dependent line shift and line width to theoretical models show that the dominant (dephasing) interaction is due to scattering by acoustic phonons of about 23 meV. Low temperature photoluminescence excitation measurements show that the excitonic band gap depends approximately inversely linearly on the quantum dot size d, which is distinctly weaker than the dependence predicted by current theories.

Observing stellar coronae with the Goddard High Resolution Spectrograph. 1: The dMe star AU microscopoii

NASA Astrophysics Data System (ADS)

Maran, S. P.; Robinson, R. D.; Shore, S. N.; Brosius, J. W.; Carpenter, K. G.; Woodgate, B. E.; Linsky, J. L.; Brown, A.; Byrne, P. B.; Kundu, M. R.; White, S.; Brandt, J. C.; Shine, R. A.; Walter, F. M.

1994-02-01

We report on an observation of AU Mic taken with the Goddard High Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope. The data consist of a rapid sequence of spectra covering the wavelength range 1345-1375 A with a spectral resolution of 10,000. The observations were originally intended to search for spectral variations during flares. No flares were detected during the 3.5 hr of monitoring. A method of reducing the noise while combining the individual spectra in the time series is described which resulted in the elimination of half of the noise while rejecting only a small fraction of the stellar signal. The resultant spectrum was of sufficient quality to allow the detection of emission lines with an integrated flux of 10-15 ergs/sq cm(sec) or greater. Lines of C I, O I, O V, Cl I, and Fe XXI were detected. This is the first indisputable detection of the 1354 A Fe XXI line, formed at T approximately = 107 K, on a star other than the Sun. The line was well resolved and displayed no significant bulk motions or profile asymmetry. From the upper limit on the observed line width, we derive an upper limit of 38 km/s for the turbulent velocity in the 107 K plasma. An upper limit is derived for the flux of the 1349 A Fe XII line, formed at T approximately = 1.3 x 106 K. These data are combined with contemporaneous GHRS and International Ultraviolet Explorer (IUE) data to derive the volume emission measure distribution of AU Mic over the temperature range 104-107 K. Models of coronal loops in hydrostatic equilibrium are consistent with the observed volume emission measures of the coronal lines. The fraction of the stellar surface covered by the footprints of the loops depends upon the loop length and is less than 14% for lengths smaller than the stellar radius. From the upper limit to the estimated width of the Fe XXI line profile we find that the we cannot rule out Alfven wave dissipation as a possible contributor to the required quiescent loop heating rate.

Dynamics of short-pulse generation via spectral filtering from intensely excited gain-switched 1.55-μm distributed-feedback laser diodes.

PubMed

Chen, Shaoqiang; Yoshita, Masahiro; Sato, Aya; Ito, Takashi; Akiyama, Hidefumi; Yokoyama, Hiroyuki

2013-05-06

Picosecond-pulse-generation dynamics and pulse-width limiting factors via spectral filtering from intensely pulse-excited gain-switched 1.55-μm distributed-feedback laser diodes were studied. The spectral and temporal characteristics of the spectrally filtered pulses indicated that the short-wavelength component stems from the initial part of the gain-switched main pulse and has a nearly linear down-chirp of 5.2 ps/nm, whereas long-wavelength components include chirped pulse-lasing components and steady-state-lasing components. Rate-equation calculations with a model of linear change in refractive index with carrier density explained the major features of the experimental results. The analysis of the expected pulse widths with optimum spectral widths was also consistent with the experimental data.

High-resolution X-ray spectroscopy of the supernova remnant N132D

NASA Technical Reports Server (NTRS)

Hwang, Una; Hughes, John P.; Canizares, Claude R.; Markert, Thomas H.

1993-01-01

A joint nonequilibrium ionization analysis of spectral data from the Einstein Observatory of the SNR N132D in the LMC is presented on the basis of data from the Focal Plane Crystal Spectrometer (FPCS) and the Solid State Spectrometer (SSS), and lower spectral resolution data from the IPC and the Monitor Proportional Counter (MPC). The FPCS detected individual emission lines of O VII, O VIII, Ne IX, Ne X, Fe XVII, and possibly Fe XX. Measured line widths for the oxygen lines suggest Doppler broadening that is roughly consistent with optically measured expansion velocities of 2250 km/s. At the SSS/IPC temperature, FPCS flux ratios constrain the O/Fe abundance to be at least 1.9 times its solar value and the O/Ne abundance to be 0.2-1.0 times its solar value. Models for remnants with progenitor masses of 20 and 25 solar masses are completely consistent with the data, while remnants with progenitor masses of 13 and 15 solar masses can be made consistent if the progenitors are required to eject a large fraction of their iron cores.

High-resolution grazing-incidence grating spectrometer for temperature measurements of low-Z ions emitting in the 100–300 Å spectral band

DOE PAGES

Widmann, K.; Beiersdorfer, P.; Magee, E. W.; ...

2014-09-19

In this paper, we have constructed a high-resolution grazing-incidence spectrometer designed for measuring the ion temperature of low-Z elements, such as Li + or Li 2 +, which radiate near 199 Å and 135 Å, respectively. Based on measurements at the Livermore Electron Beam Ion Trap we have shown that the instrumental resolution is better than 48 mÅ at the 200 Å setting and better than 40 mÅ for the 135-Å range. Such a high spectral resolution corresponds to an instrumental limit for line-width based temperature measurements of about 45 eV for the 199 Å Li+ and 65 eV formore » the 135 Å Li 2 + lines. Finally, recently obtained survey spectra from the Lithium Tokamak Experiment at the Princeton Plasma Physics Laboratory show the presence of these lithium emission lines and the expected core ion temperature of approximately 70 eV is sufficiently high to demonstrate the feasibility of utilizing our high-resolution spectrometer as an ion-temperature diagnostic.« less

CO{sub 2} isolated line shapes by classical molecular dynamics simulations: Influence of the intermolecular potential and comparison with new measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Larcher, G.; Tran, H., E-mail: ha.tran@lisa.u-pec.fr; Schwell, M.

2014-02-28

Room temperature absorption spectra of various transitions of pure CO{sub 2} have been measured in a broad pressure range using a tunable diode-laser and a cavity ring-down spectrometer, respectively, in the 1.6 μm and 0.8 μm regions. Their spectral shapes have been calculated by requantized classical molecular dynamics simulations. From the time-dependent auto-correlation function of the molecular dipole, including Doppler and collisional effects, spectral shapes are directly computed without the use of any adjusted parameter. Analysis of the spectra calculated using three different anisotropic intermolecular potentials shows that the shapes of pure CO{sub 2} lines, in terms of both themore » Lorentz widths and non-Voigt effects, slightly depend on the used potential. Comparisons between these ab initio calculations and the measured spectra show satisfactory agreement for all considered transitions (from J = 6 to J = 46). They also show that non-Voigt effects on the shape of CO{sub 2} transitions are almost independent of the rotational quantum number of the considered lines.« less

Low-Temperature Single Carbon Nanotube Spectroscopy of sp 3 Quantum Defects

DOE PAGES

He, Xiaowei; Gifford, Brendan J.; Hartmann, Nicolai F.; ...

2017-09-28

Aiming to unravel the relationship between chemical configuration and electronic structure of sp3 defects of aryl-functionalized (6,5) single-walled carbon nanotubes (SWCNTs), we perform low-temperature single nanotube photoluminescence (PL) spectroscopy studies and correlate our observations with quantum chemistry simulations. Here, we observe sharp emission peaks from individual defect sites that are spread over an extremely broad, 1000-1350 nm, spectral range. Our simulations allow us to attribute this spectral diversity to the occurrence of six chemically and energetically distinct defect states resulting from topological variation in the chemical binding configuration of the monovalent aryl groups. Both PL emission efficiency and spectral linemore » width of the defect states are strongly influenced by the local dielectric environment. Wrapping the SWCNT with a polyfluorene polymer provides the best isolation from the environment and yields the brightest emission with near-resolution limited spectral line width of 270 ueV, as well as spectrally resolved emission wings associated with localized acoustic phonons. Pump-dependent studies further revealed that the defect states are capable of emitting single, sharp, isolated PL peaks over 3 orders of magnitude increase in pump power, a key characteristic of two-level systems and an important prerequisite for single-photon emission with high purity. Our findings point to the tremendous potential of sp3 defects in development of room temperature quantum light sources capable of operating at telecommunication wavelengths as the emission of the defect states can readily be extended to this range via use of larger diameter SWCNTs.« less

Low-Temperature Single Carbon Nanotube Spectroscopy of sp 3 Quantum Defects

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, Xiaowei; Gifford, Brendan J.; Hartmann, Nicolai F.

Aiming to unravel the relationship between chemical configuration and electronic structure of sp3 defects of aryl-functionalized (6,5) single-walled carbon nanotubes (SWCNTs), we perform low-temperature single nanotube photoluminescence (PL) spectroscopy studies and correlate our observations with quantum chemistry simulations. Here, we observe sharp emission peaks from individual defect sites that are spread over an extremely broad, 1000-1350 nm, spectral range. Our simulations allow us to attribute this spectral diversity to the occurrence of six chemically and energetically distinct defect states resulting from topological variation in the chemical binding configuration of the monovalent aryl groups. Both PL emission efficiency and spectral linemore » width of the defect states are strongly influenced by the local dielectric environment. Wrapping the SWCNT with a polyfluorene polymer provides the best isolation from the environment and yields the brightest emission with near-resolution limited spectral line width of 270 ueV, as well as spectrally resolved emission wings associated with localized acoustic phonons. Pump-dependent studies further revealed that the defect states are capable of emitting single, sharp, isolated PL peaks over 3 orders of magnitude increase in pump power, a key characteristic of two-level systems and an important prerequisite for single-photon emission with high purity. Our findings point to the tremendous potential of sp3 defects in development of room temperature quantum light sources capable of operating at telecommunication wavelengths as the emission of the defect states can readily be extended to this range via use of larger diameter SWCNTs.« less

Erratum: The 2.27 day period of WR-134 (HD 191765)

NASA Astrophysics Data System (ADS)

McCandliss, Stephan R.; Bohannan, Bruce; Robert, Carmelle; Moffat, Anthony F. J.

1994-11-01

The original temporal analysis of a 12 night spectral timeseries of Wolf-Rayet (WR)-134 has been found to be flawed and a re-analysis shows that the line profile variations are indeed periodic. When combined with a 4 night timeseries taken 45 days earlier, a period near 2.27 d is found in periodograms of the He II lambda 5412 line centroid, rms line width, and line skew variations. When the emission line residuals are ordered as a function of phase, a sinuous feature appears to 'snake' about the line center with an amplitude of +/-500 km/s. This is approximately equal to 20 larger than the line centroid amplitude; the calculation of which is heavily weighted by static portions of the line profile. In addition to the 'snake,' emission residuals appear that move away from line center on unbound trajectories and are thought to result from the interaction of a periodic driver with the unstable flow of the radiation driven wind.

Erratum: The 2.27 day period of WR-134 (HD 191765)

NASA Technical Reports Server (NTRS)

Mccandliss, Stephan R.; Bohannan, Bruce; Robert, Carmelle; Moffat, Anthony F. J.

1994-01-01

The original temporal analysis of a 12 night spectral timeseries of Wolf-Rayet (WR)-134 has been found to be flawed and a re-analysis shows that the line profile variations are indeed periodic. When combined with a 4 night timeseries taken 45 days earlier, a period near 2.27 d is found in periodograms of the He II lambda 5412 line centroid, rms line width, and line skew variations. When the emission line residuals are ordered as a function of phase, a sinuous feature appears to 'snake' about the line center with an amplitude of +/-500 km/s. This is approximately equal to 20 larger than the line centroid amplitude; the calculation of which is heavily weighted by static portions of the line profile. In addition to the 'snake,' emission residuals appear that move away from line center on unbound trajectories and are thought to result from the interaction of a periodic driver with the unstable flow of the radiation driven wind.

Study of the spectral width of intermode beats and optical spectrum of an actively mode-locked three-mirror semiconductor laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zakharyash, Valerii F; Kashirsky, Aleksandr V; Klementyev, Vasilii M

2005-09-30

Various oscillation regimes of an actively mode-locked semiconductor laser are studied experimentally. Two types of regimes are found in which the minimal spectral width ({approx}3.5 kHz) of intermode beats is achieved. The width of the optical spectrum of modes is studied as a function of their locking and the feedback coefficients. The maximum width of the spectrum is {approx}3.7 THz. (control of laser radiation parameters)

Performance of the Fourier transform spectrometer (FTS) for FIS onboard ASTRO-F

NASA Astrophysics Data System (ADS)

Murakami, Noriko; Kawada, Mitsunobu; Takahashi, Hidenori; Ozawa, Keita; Imamura, Tetsuo; Shibai, Hiroshi; Nakagawa, Takao

2004-10-01

We have developed the imaging Fourier Transform Spectrometer (FTS) for the FIS (Far-Infrared Surveyor) onboard the ASTRO-F satellite. A Martin-Puplett interferometer is adopted to achieve high optical efficiency in a wide wavelength range. The total optical efficiency of this spectrometer is achieved 40-80% of the ideal value which is 25% of the incident flux. The wavelength range of 50-200μm is covered with two kinds of detector; the monolithic Ge:Ga photoconductor array for short wavelength (50-110μm) and the stressed Ge:Ga photoconductor array for long wavelength (110-200μm). The spectral resolution expected from the maximum optical path difference is 0.18cm-1. In order to evaluate the spectral resolution of the FTS, we measured absorption lines of H2O in atmosphere using the optics of the FTS with a bolometer at the room temperature. The measured line widths are consistent with the expected instrumental resolution of 0.18 cm-1. Some spectral measurements at the cryogenic temperature were carried out by using cold blackbody sources whose temperatures are controlled in a range from 20 to 50 K. The derived spectra considering with the spectral response of the system are consistent with expected ones. Spectroscopic observations with the FTS will provide a lot of astronomical information; SED of galaxies detected in the all sky survey and the physical diagnostics of the interstellar matter by using the excited atomic or molecular lines.

Signatures of Alfvén waves in the polar coronal holes as seen by EIS/Hinode

NASA Astrophysics Data System (ADS)

Banerjee, D.; Pérez-Suárez, D.; Doyle, J. G.

2009-07-01

Context: We diagnose the properties of the plume and interplume regions in a polar coronal hole and the role of waves in the acceleration of the solar wind. Aims: We attempt to detect whether Alfvén waves are present in the polar coronal holes through variations in EUV line widths. Methods: Using spectral observations performed over a polar coronal hole region with the EIS spectrometer on Hinode, we study the variation in the line width and electron density as a function of height. We use the density sensitive line pairs of Fe xii 186.88 Å and 195.119 Å and Fe xiii 203.82 Å and 202.04 Å. Results: For the polar region, the line width data show that the nonthermal line-of-sight velocity increases from 26~km s-1 at 10´´ above the limb to 42~km s-1 some 150´´ (i.e. ~110 000 km) above the limb. The electron density shows a decrease from 3.3 × 10^9~cm-3 to 1.9 × 10^8~cm-3 over the same distance. Conclusions: These results imply that the nonthermal velocity is inversely proportional to the quadratic root of the electron density, in excellent agreement with what is predicted for undamped radially propagating linear Alfvén waves. Our data provide signatures of Alfvén waves in the polar coronal hole regions, which could be important for the acceleration of the solar wind. Table [see full textsee full textsee full text] and Fig. [see full textsee full textsee full text] are only available in electronic form at http://www.aanda.org

A resonant absorption line in the ASCA spectrum of NGC 985?

NASA Astrophysics Data System (ADS)

Nicastro, F.; Fiore, F.; Brandt, N.; Reynolds, C. S.

1999-01-01

We present timing and spectral analyses of the ASCA observation of the Seyfert 1 galaxy NGC 985. The 0.6-10keV spectrum of this source is complex: large residuals are evident below 1keV when fitting the spectrum with a power-law model. Fitting a warm absorber model to the 0.6-2.5keV spectrum gives α=1.12+/-0.04, LogNWAH=21.97+/-0.08 and LogU=0.06+/-0.09, but the residuals continue to show a deficit of counts between 0.9 and 1keV. Adding an absorption line improves the fit, and the energy of the line is consistent with that of Kα NeIX-X resonant absorption lines. Hence, we confirm the presence of an ionized absorber along the line of sight to this source and interpret the further 1keV spectral feature as the first detection of a strong resonant absorption line associated with this system. The extrapolation of this model above 2.5keV produces large positive residuals above 3-4keV. Fitting the data with a broken power law plus warm absorber model gives an acceptable χ2 and Δα~0.5. A narrow iron line at 6.4keV (quasar frame) of equivalent width 138+64-110eV is also present in the ASCA data.

[NEII] Line Velocity Structure of Ultracompact HII Regions

NASA Astrophysics Data System (ADS)

Okamoto, Yoshiko K.; Kataza, Hirokazu; Yamashita, Takuya; Miyata, Takashi; Sako, Shigeyuki; Honda, Mitsuhiko; Onaka, Takashi; Fujiyoshi, Takuya

Newly formed massive stars are embedded in their natal molecular clouds and are observed as ultracompact HII regions. They emit strong ionic lines such as [NeII] 12.8 micron. Since Ne is ionized by UV photons of E>21.6eV which is higher than the ionization energy of hydrogen atoms the line probes the ionized gas near the ionizing stars. This enables to probe gas motion in the vicinity of recently-formed massive stars. High angular and spectral resolution observations of the [NeII] line will thus provide siginificant information on structures (e.g. disks and outflows) generated through massive star formation. We made [NeII] spectroscopy of ultracompact HII regions using the Cooled Mid-Infrared Camera and Spectrometer (COMICS) on the 8.2m Subaru Telescope in July 2002. Spatial and spectral resolutions were 0.5"" and 10000 respectively. Among the targets G45.12+0.13 shows the largest spatial variation in velocity. The brightest area of G45.12+0.13 has the largest line width in the object. The total velocity deviation amounts to 50km/s (peak to peak value) in the observed area. We report the velocity structure of [NeII] emission of G45.12+0.13 and discuss the gas motion near the ionizing star.

Temperature-dependence laws of absorption line shape parameters of the CO2 ν3 band

NASA Astrophysics Data System (ADS)

Wilzewski, J. S.; Birk, M.; Loos, J.; Wagner, G.

2018-02-01

To improve the understanding of temperature-dependence laws of spectral line shape parameters, spectra of the ν3 rovibrational band of CO2 perturbed by 10, 30, 100, 300 and 1000 mbar of N2 were recorded at nine temperatures between 190 K and 330 K using a 22 cm long single-pass absorption cell in a Bruker IFS125 HR Fourier Transform spectrometer. The spectra were fitted employing a quadratic speed-dependent hard collision model in the Hartmann-Tran implementation extended to account for line mixing in the Rosenkranz approximation by means of a multispectrum fitting approach developed at DLR. This enables high accuracy parameter retrievals to reproduce the spectra down to noise level and we present the behavior of line widths, shifts, speed-dependence-, collisional narrowing- and line mixing-parameters over this 140 K temperature range.

Air- and Self-Broadened Half Widths, Pressure-Induced Shifts, and Line Mixing in the Nu(sub 2) Band of (12)CH4

NASA Technical Reports Server (NTRS)

Smith, M. A. H.; Benner, D. Chris; Pedroi-Cross, A.; Devi, V. Malathy

2013-01-01

Lorentz self- and air-broadened half width and pressure-induced shift coefficients and their dependences on temperature have been measured from laboratory absorption spectra for nearly 130 transitions in the nu(sub 2) band of (12)CH4. In addition line mixing coefficients (using the relaxation matrix element formalism) for both self- and airbroadening were experimentally determined for the first time for a small number of transitions in this band. Accurate line positions and absolute line intensities were also determined. These parameters were obtained by analyzing high-resolution (approx. 0.003 to 0.01 per cm) laboratory spectra of high-purity natural CH4 and air-broadened CH4 recorded at temperatures between 226 and 297 K using the McMath-Pierce Fourier transform spectrometer (FTS) located at the National Solar Observatory on Kitt Peak, Arizona. A multispectrum nonlinear least squares technique was used to fit short (5-15 per cm) spectral intervals in 24-29 spectra simultaneously. Parameters were determined for nu(sub 2) transitions up to J" = 16. The variations of the measured broadening and shift parameters with the rotational quantum number index and tetrahedral symmetry species are examined. The present results are also compared with previous measurements available in the literature.

Control of Emission Color of High Quantum Yield CH3NH3PbBr3 Perovskite Quantum Dots by Precipitation Temperature.

PubMed

Huang, He; Susha, Andrei S; Kershaw, Stephen V; Hung, Tak Fu; Rogach, Andrey L

2015-09-01

Emission color controlled, high quantum yield CH 3 NH 3 PbBr 3 perovskite quantum dots are obtained by changing the temperature of a bad solvent during synthesis. The products for temperatures between 0 and 60 °C have good spectral purity with narrow emission line widths of 28-36 nm, high absolute emission quantum yields of 74% to 93%, and short radiative lifetimes of 13-27 ns.

High-resolution single-shot spectral monitoring of hard x-ray free-electron laser radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Makita, M.; Karvinen, P.; Zhu, D.

We have developed an on-line spectrometer for hard x-ray free-electron laser (XFEL) radiation based on a nanostructured diamond diffraction grating and a bent crystal analyzer. Our method provides high spectral resolution, interferes negligibly with the XFEL beam, and can withstand the intense hard x-ray pulses at high repetition rates of >100 Hz. The spectrometer is capable of providing shot-to-shot spectral information for the normalization of data obtained in scientific experiments and optimization of the accelerator operation parameters. We have demonstrated these capabilities of the setup at the Linac Coherent Light Source, in self-amplified spontaneous emission mode at full energy ofmore » >1 mJ with a 120 Hz repetition rate, obtaining a resolving power of Ε/δΕ > 3 × 10 4. In conclusion, the device was also used to monitor the effects of pulse duration down to 8 fs by analysis of the spectral spike width.« less

High-resolution single-shot spectral monitoring of hard x-ray free-electron laser radiation

DOE PAGES

Makita, M.; Karvinen, P.; Zhu, D.; ...

2015-10-16

We have developed an on-line spectrometer for hard x-ray free-electron laser (XFEL) radiation based on a nanostructured diamond diffraction grating and a bent crystal analyzer. Our method provides high spectral resolution, interferes negligibly with the XFEL beam, and can withstand the intense hard x-ray pulses at high repetition rates of >100 Hz. The spectrometer is capable of providing shot-to-shot spectral information for the normalization of data obtained in scientific experiments and optimization of the accelerator operation parameters. We have demonstrated these capabilities of the setup at the Linac Coherent Light Source, in self-amplified spontaneous emission mode at full energy ofmore » >1 mJ with a 120 Hz repetition rate, obtaining a resolving power of Ε/δΕ > 3 × 10 4. In conclusion, the device was also used to monitor the effects of pulse duration down to 8 fs by analysis of the spectral spike width.« less

Multispectrum Analysis of 12CH4 in the v4 Band: I. Air-Broadened Half Widths, Pressure-Induced Shifts, Temperature Dependences and Line Mixing

NASA Technical Reports Server (NTRS)

Smith, MaryAnn H.; Benner, D. Chris; Predoi-Cross, Adriana; Venkataraman, Malathy Devi

2009-01-01

Lorentz air-broadened half widths, pressure-induced shifts and their temperature dependences have been measured for over 430 transitions (allowed and forbidden) in the v4 band of (CH4)-12 over the temperature range 210 to 314 K. A multispectrum non linear least squares fitting technique was used to simultaneously fit a large number of high-resolution (0.006 to 0.01/cm) absorption spectra of pure methane and mixtures of methane diluted with dry air. Line mixing was detected for pairs of A-, E-, and F-species transitions in the P- and R-branch manifolds and quantified using the off-diagonal relaxation matrix elements formalism. The measured parameters are compared to air- and N2-broadened values reported in the literature for the v4 and other bands. The dependence of the various spectral line parameters upon the tetrahedral symmetry species and rotational quantum numbers of the transitions is discussed. All data used in the present work were recorded using the McMath-Pierce Fourier transform spectrometer located at the National Solar Observatory on Kitt Peak.

Advances in Low-Temperature Tungsten Spectroscopy Capability to Quantify DIII-D Divertor Erosion

DOE PAGES

Abrams, Tyler; Thomas, Daniel M.; Unterberg, Ezekial A.; ...

2018-01-05

Recent emphasis of tungsten (W) plasma-materialsinteractions (PMI) experiments on DIII-D has made it essential to enhance the W I and W II measurement capabilities of its spectroscopy diagnostic suite to acquire W sourcing measurements with high temporal, spatial, and wavelength resolution. To this end, four new viewing chords for the Multichordal Divertor Spectrometer (MDS) and diverter filterscope systems were installed, leading to a 7x increase in blue light sensitivity. W I and low-Z impurity line identifications were performed in the 3995-4030 Å region, placing wavelengths within 0.1 Å of the NIST values. A novel method was also developed for themore » DIII-D high temporal resolution filterscopes to distinguish between W I light and background contamination, important due to the relatively weak intensity of this line, using two different bandpass filters width different widths but the same center wavelength. Lastly, fast imaging of the W I 4008.75 Å spectral line with a PCO Pixelfly VGA 200/205 camera allowed for discrimination between ELMy and intra-ELM W I emission profiles with very high (~1 mm) spatial resolution.« less

H-alpha observations of Sh2-190, Sh2-222, Sh2-229, Sh2-236 HII regions

NASA Astrophysics Data System (ADS)

Sahan, Muhittin

2018-02-01

Hα spectral line (6563Å) profiles of four northern HII regions in the our galaxy (Sh2-190, Sh2-222, Sh2-229, Sh2-236) have been obtained using DEFPOS spectrometer, located at coude focus of 150 cm RTT150 telescope at TUBITAK National Observatory (TUG, Antalya, Turkey). Observations were carried out at nights of 2015 December 24-27 with long exposure times ranging from 900s to 3600s. The LSR velocities and the linewidths (Full Width Half Maximum: FWHM) of the Hα emission lines were found to be in the range of -45.46 kms-1 to +3.57 kms-1 and 38.50 kms-1 to 44.10 kms-1, respectively. The Sh2-229 HII region is the faintest one (211.16 R), while the Sh2-236 HII region (IC410) is brightest source (535.75 R). The LSR velocity and the line width (FWHM) results of the DEFPOS/RTT150 system were compared with the data by several authors given in literature and results of DEFPOS data were found to be in good agreement with data given in literature.

Advances in Low-Temperature Tungsten Spectroscopy Capability to Quantify DIII-D Divertor Erosion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abrams, Tyler; Thomas, Daniel M.; Unterberg, Ezekial A.

Recent emphasis of tungsten (W) plasma-materialsinteractions (PMI) experiments on DIII-D has made it essential to enhance the W I and W II measurement capabilities of its spectroscopy diagnostic suite to acquire W sourcing measurements with high temporal, spatial, and wavelength resolution. To this end, four new viewing chords for the Multichordal Divertor Spectrometer (MDS) and diverter filterscope systems were installed, leading to a 7x increase in blue light sensitivity. W I and low-Z impurity line identifications were performed in the 3995-4030 Å region, placing wavelengths within 0.1 Å of the NIST values. A novel method was also developed for themore » DIII-D high temporal resolution filterscopes to distinguish between W I light and background contamination, important due to the relatively weak intensity of this line, using two different bandpass filters width different widths but the same center wavelength. Lastly, fast imaging of the W I 4008.75 Å spectral line with a PCO Pixelfly VGA 200/205 camera allowed for discrimination between ELMy and intra-ELM W I emission profiles with very high (~1 mm) spatial resolution.« less

Suppressing spectral diffusion of emitted photons with optical pulses

DOE PAGES

Fotso, H. F.; Feiguin, A. E.; Awschalom, D. D.; ...

2016-01-22

In many quantum architectures the solid-state qubits, such as quantum dots or color centers, are interfaced via emitted photons. However, the frequency of photons emitted by solid-state systems exhibits slow uncontrollable fluctuations over time (spectral diffusion), creating a serious problem for implementation of the photon-mediated protocols. Here we show that a sequence of optical pulses applied to the solid-state emitter can stabilize the emission line at the desired frequency. We demonstrate efficiency, robustness, and feasibility of the method analytically and numerically. Taking nitrogen-vacancy center in diamond as an example, we show that only several pulses, with the width of 1more » ns, separated by few ns (which is not difficult to achieve) can suppress spectral diffusion. As a result, our method provides a simple and robust way to greatly improve the efficiency of photon-mediated entanglement and/or coupling to photonic cavities for solid-state qubits.« less

Optical microresonator for application to an opto-electronic oscillator

NASA Astrophysics Data System (ADS)

Wu, Yu-Mei; Vivien, Laurent; Cassan, Eric; Luong, Vu Hai Nam; Nguyen, Lam Duy; Journet, Bernard

2010-02-01

Optoelectronic oscillators are classically based on a feedback fiber loop acting as a delay line for high spectral purity. One of the problems due to long fiber loops is the size and the requirement of temperature control. Going toward integrated solutions requires the introduction of optical resonators with a very high quality factor. A structure based on silicon on insulator material has been designed for application to an oscillator working at 8 GHz. The micro-resonator has a stadium shape with a ridge of 30 nm height, 1 μm width, a millimetric radius and a gap of some microns in agreement with the required free spectral range. A quality factor of 500000 can be achieved leading to an equivalent fiber loop of 2 km.

A MODEL FOR INTERFACE DYNAMOS IN LATE K AND EARLY M DWARFS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mullan, D. J.; MacDonald, J.; Houdebine, E. R., E-mail: mullan@udel.edu

2015-09-10

Measurements of the equivalent width EW(CaK) of emission in the Ca ii K line have been obtained by Houdebine et al. for stars with spectral types from dK5 to dM4. In order to explain the observed variations of EW(CaK) with spectral sub-type, we propose a quantitative model of interface dynamos in low-mass stars. Our model leads to surface field strengths B{sub s} which turn out to be essentially linearly proportional to EW(CaK). This result is reminiscent of the Sun, where Skumanich et al. found that the intensity of CaK emission in solar active regions is linearly proportional to the localmore » field strength.« less

M.S.L.A.P. Modular Spectral Line Analysis Program documentation

NASA Technical Reports Server (NTRS)

Joseph, Charles L.; Jenkins, Edward B.

1991-01-01

MSLAP is a software for analyzing spectra, providing the basic structure to identify spectral features, to make quantitative measurements of this features, and to store the measurements for convenient access. MSLAP can be used to measure not only the zeroth moment (equivalent width) of a profile, but also the first and second moments. Optical depths and the corresponding column densities across the profile can be measured as well for sufficiently high resolution data. The software was developed for an interactive, graphical analysis where the computer carries most of the computational and data organizational burden and the investigator is responsible only for all judgement decisions. It employs sophisticated statistical techniques for determining the best polynomial fit to the continuum and for calculating the uncertainties.

Line shape parameters of air-broadened water vapor transitions in the ν 1 and ν 3 spectral region

DOE PAGES

Malathy Devi, V.; Gamache, Robert R.; Vispoel, Bastien; ...

2017-11-26

A Bruker IFS-120HR Fourier transform spectrometer located at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington was used to record a series of spectra of pure H 2O and air-broadened H 2O in the regions of the ν 1 and ν 3 bands (3450–4000 cm -1) at different pressures, temperatures and volume mixing ratios of H 2O in air. Eighteen high-resolution, high signal-to-noise (S/N) ratio absorption spectra were recorded at T = 268, 296 and 353 K using two temperature-controlled absorption cells with path lengths of 9.906(1) and 19.95(1) cm. Furthermore, the resolution of the spectra recorded with themore » 9.906 cm and 19.95 cm absorption cells was 0.006 and 0.008 cm -1, respectively. A multispectrum nonlinear least squares fitting technique was employed to fit all the eighteen spectra simultaneously to retrieve 313 accurate line positions, 315 intensities, 229 Lorentz air-broadened half-width and 213 air-shift coefficients and their temperature dependences (136 for air-broadened width and 128 for air-shift coefficients, respectively). Room temperature self-broadened half-width coefficients for 209 transitions and self-shift coefficients for 106 transitions were also measured. Line mixing coefficients were experimentally determined for isolated sets of 10 transition pairs for H 2O-air and 8 transition pairs for H 2O-H 2O using the off-diagonal relaxation matrix element formalism, and 85 quadratic speed dependence parameters were measured. Modified Complex Robert-Bonamy (MCRB) calculations of self-, and air-broadened (from N 2- and O 2-broadening) half-width and air-shift coefficients, and temperature dependence exponents of air-broadened half-width coefficients are made. Finally, the measurements and calculations are compared with each other and with similar parameters reported in the literature.« less

Line shape parameters of air-broadened water vapor transitions in the ν1 and ν3 spectral region

NASA Astrophysics Data System (ADS)

Malathy Devi, V.; Gamache, Robert R.; Vispoel, Bastien; Renaud, Candice L.; Chris Benner, D.; Smith, Mary Ann H.; Blake, Thomas A.; Sams, Robert L.

2018-06-01

A Bruker IFS-120HR Fourier transform spectrometer located at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington was used to record a series of spectra of pure H2O and air-broadened H2O in the regions of the ν1 and ν3 bands (3450-4000 cm-1) at different pressures, temperatures and volume mixing ratios of H2O in air. Eighteen high-resolution, high signal-to-noise (S/N) ratio absorption spectra were recorded at T = 268, 296 and 353 K using two temperature-controlled absorption cells with path lengths of 9.906(1) and 19.95(1) cm. The resolution of the spectra recorded with the 9.906 cm and 19.95 cm absorption cells was 0.006 and 0.008 cm-1, respectively. A multispectrum nonlinear least squares fitting technique was employed to fit all the eighteen spectra simultaneously to retrieve 313 accurate line positions, 315 intensities, 229 Lorentz air-broadened half-width and 213 air-shift coefficients and their temperature dependences (136 for air-broadened width and 128 for air-shift coefficients, respectively). Room temperature self-broadened half-width coefficients for 209 transitions and self-shift coefficients for 106 transitions were also measured. Line mixing coefficients were experimentally determined for isolated sets of 10 transition pairs for H2O-air and 8 transition pairs for H2O-H2O using the off-diagonal relaxation matrix element formalism, and 85 quadratic speed dependence parameters were measured. Modified Complex Robert-Bonamy (MCRB) calculations of self-, and air-broadened (from N2- and O2-broadening) half-width and air-shift coefficients, and temperature dependence exponents of air-broadened half-width coefficients are made. The measurements and calculations are compared with each other and with similar parameters reported in the literature.

Line shape parameters of air-broadened water vapor transitions in the ν 1 and ν 3 spectral region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malathy Devi, V.; Gamache, Robert R.; Vispoel, Bastien

A Bruker IFS-120HR Fourier transform spectrometer located at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington was used to record a series of spectra of pure H 2O and air-broadened H 2O in the regions of the ν 1 and ν 3 bands (3450–4000 cm -1) at different pressures, temperatures and volume mixing ratios of H 2O in air. Eighteen high-resolution, high signal-to-noise (S/N) ratio absorption spectra were recorded at T = 268, 296 and 353 K using two temperature-controlled absorption cells with path lengths of 9.906(1) and 19.95(1) cm. Furthermore, the resolution of the spectra recorded with themore » 9.906 cm and 19.95 cm absorption cells was 0.006 and 0.008 cm -1, respectively. A multispectrum nonlinear least squares fitting technique was employed to fit all the eighteen spectra simultaneously to retrieve 313 accurate line positions, 315 intensities, 229 Lorentz air-broadened half-width and 213 air-shift coefficients and their temperature dependences (136 for air-broadened width and 128 for air-shift coefficients, respectively). Room temperature self-broadened half-width coefficients for 209 transitions and self-shift coefficients for 106 transitions were also measured. Line mixing coefficients were experimentally determined for isolated sets of 10 transition pairs for H 2O-air and 8 transition pairs for H 2O-H 2O using the off-diagonal relaxation matrix element formalism, and 85 quadratic speed dependence parameters were measured. Modified Complex Robert-Bonamy (MCRB) calculations of self-, and air-broadened (from N 2- and O 2-broadening) half-width and air-shift coefficients, and temperature dependence exponents of air-broadened half-width coefficients are made. Finally, the measurements and calculations are compared with each other and with similar parameters reported in the literature.« less

Precision Spectrophotometric Calibration System for Dark Energy Instruments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schubnell, Michael S.

2015-06-30

For this research we build a precision calibration system and carried out measurements to demonstrate the precision that can be achieved with a high precision spectrometric calibration system. It was shown that the system is capable of providing a complete spectrophotometric calibration at the sub-pixel level. The calibration system uses a fast, high precision monochromator that can quickly and efficiently scan over an instrument’s entire spectral range with a spectral line width of less than 0.01 nm corresponding to a fraction of a pixel on the CCD. The system was extensively evaluated in the laboratory. Our research showed that amore » complete spectrophotometric calibration standard for spectroscopic survey instruments such as DESI is possible. The monochromator precision and repeatability to a small fraction of the DESI spectrograph LSF was demonstrated with re-initialization on every scan and thermal drift compensation by locking to multiple external line sources. A projector system that mimics telescope aperture for point source at infinity was demonstrated.« less

Observations of comet Levy 1990c in the (OI) 6300-A line with an imaging Fabry-Perot

NASA Technical Reports Server (NTRS)

Prasad, C. Debi; Jockers, Klaus; Rauer, H.; Geyer, E. H.

1992-01-01

We have observed the comet Levy 1990c during 16-25 August 1990 using the MPAE focal reducer system based Fabry-Perot etalon coupled with the 1 meter telescope of the Observatory of Hoher List. The free spectral range and resolution limit of the interferometer was approximately 2.18 A and approximately 0.171 A respectively. Classical Fabry-Perot fringes were recorded on a CCD in the cometary (OI) 6300 A line. They are well resolved from telluric air glow and cometary NH2 emission. Our observations indicate that the (OI) is distributed asymmetrically with respect to the center of the comet. In this paper we report the spatial distribution of (OI) emission and its line width in the coma of comet Levy.

METALLICITY AND TEMPERATURE INDICATORS IN M DWARF K-BAND SPECTRA: TESTING NEW AND UPDATED CALIBRATIONS WITH OBSERVATIONS OF 133 SOLAR NEIGHBORHOOD M DWARFS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rojas-Ayala, Barbara; Covey, Kevin R.; Lloyd, James P.

2012-04-01

We present K-band spectra for 133 nearby (d < 33 ps) M dwarfs, including 18 M dwarfs with reliable metallicity estimates (as inferred from an FGK type companion), 11 M dwarf planet hosts, more than 2/3 of the M dwarfs in the northern 8 pc sample, and several M dwarfs from the LSPM catalog. From these spectra, we measure equivalent widths of the Ca and Na lines, and a spectral index quantifying the absorption due to H{sub 2}O opacity (the H{sub 2}O-K2 index). Using empirical spectral type standards and synthetic models, we calibrate the H{sub 2}O-K2 index as an indicatormore » of an M dwarf's spectral type and effective temperature. We also present a revised relationship that estimates the [Fe/H] and [M/H] metallicities of M dwarfs from their Na I, Ca I, and H{sub 2}O-K2 measurements. Comparisons to model atmosphere provide a qualitative validation of our approach, but also reveal an overall offset between the atomic line strengths predicted by models as compared to actual observations. Our metallicity estimates also reproduce expected correlations with Galactic space motions and H{alpha} emission line strengths, and return statistically identical metallicities for M dwarfs within a common multiple system. Finally, we find systematic residuals between our H{sub 2}O-based spectral types and those derived from optical spectral features with previously known sensitivity to stellar metallicity, such as TiO, and identify the CaH1 index as a promising optical index for diagnosing the metallicities of near-solar M dwarfs.« less

A widely tunable 10-μm quantum cascade laser phase-locked to a state-of-the-art mid-infrared reference for precision molecular spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sow, P. L. T.; Mejri, S.; Tokunaga, S. K.

2014-06-30

We report the coherent phase-locking of a quantum cascade laser (QCL) at 10-μm to the secondary frequency standard of this spectral region, a CO{sub 2} laser stabilized on a saturated absorption line of OsO{sub 4}. The stability and accuracy of the standard are transferred to the QCL resulting in a line width of the order of 10 Hz, and leading to the narrowest QCL to date. The locked QCL is then used to perform absorption spectroscopy spanning 6 GHz of NH{sub 3} and methyltrioxorhenium, two species of interest for applications in precision measurements.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Modjaz, Maryam; Liu, Yuqian Q.; Bianco, Federica B.

We present the first systematic investigation of spectral properties of 17 Type Ic Supernovae (SNe Ic), 10 broad-lined SNe Ic (SNe Ic-bl) without observed gamma-ray bursts (GRBs), and 11 SNe Ic-bl with GRBs (SN-GRBs) as a function of time in order to probe their explosion conditions and progenitors. Using a number of novel methods, we analyze a total of 407 spectra, which were drawn from published spectra of individual SNe as well as from the densely time-sampled spectra of Modjaz et al (2014). In order to quantify the diversity of the SN spectra as a function of SN subtype, wemore » construct average spectra of SNe Ic, SNe Ic-bl without GRBs, and SNe Ic-bl with GRBs. We find that SN 1994I is not a typical SN Ic, contrasting the general view, while the spectra of SN 1998bw/GRB 980425 are representative of mean spectra of SNe Ic-bl. We measure the ejecta absorption and width velocities using a new method described here and find that SNe Ic-bl with GRBs, on average, have quantifiably higher absorption velocities, as well as broader line widths than SNe without observed GRBs. In addition, we search for correlations between SN-GRB spectral properties and the energies of their accompanying GRBs. Finally, we show that the absence of clear He lines in optical spectra of SNe Ic-bl, and in particular of SN-GRBs, is not due to them being too smeared-out due to the high velocities present in the ejecta. This implies that the progenitor stars of SN-GRBs are probably free of the He-layer, in addition to being H-free, which puts strong constraints on the stellar evolutionary paths needed to produce such SN-GRB progenitors at the observed low metallicities.« less

Spectral Variability of the UXOR Star RR Tau Over 2.5 Magnitudes in V

NASA Astrophysics Data System (ADS)

Rodgers, B.; Wooden, D. H.; Grinin, V. P.; Shakhovskoy, D.

2000-12-01

We present moderate resolution optical spectra of the highly variable Herbig Ae star RR Tau over 12 epochs spanning 2.5 magnitudes in V. The data cover most of the optical spectrum from the CaII K line in the blue to the CaII infrared triplet in the far red. Using contemporaneous photometric measurements from two sources, we have reliable estimates of the visual magnitude of the system at each spectral epoch. We find some spectral activity to be closely correlated with photometric variability, while other features are remarkably stable. Significant variability is common in the cores of Hα and Hβ , but is not well correlated with photometric variability. On the other hand, the wings (Δ v>400km/s) of the Balmer lines are quite stable, showing no change in spectral type when compared to Kurucz line profiles. This, along with the constant equivalent width seen in several weak metal lines, suggest that the physical conditions of the underlying continuum source are not changing significantly, despite a factor of ten change in brightness. In contrast, strong low-ionization permitted lines, such as FeII, CaII and NaI, are seen in deep absorption when the star is bright (V <= 12), but disappear during photometric minima to reveal weak emission lines. These absorption lines are not being filled in by the emission but rather are physically disappearing from the system. This could occur, for example, if an obscuring screen moved between the continuum source and the absorbing gas. The [OI]6300 line, a common wind diagnostic, is seen in emission at all epochs, with flux which is roughly constant except increasing slightly when the system is faint. We discuss these data in the context of different scenarios for the photometric variability and find them to be more consistent with the obscuration hypothesis, than changing accretion luminosity. This work is part of the dissertation research of B. Rodgers, which has been funded in large part by a NASA Graduate Student Research Program (GSRP) grant, for which D.H. Wooden is Rodgers' advisor. We gratefully acknowledge the use of the database of the Amateur Astronomers Variable Star Organization (AAVSO).

Identification of Interesting Objects in Large Spectral Surveys Using Highly Parallelized Machine Learning

NASA Astrophysics Data System (ADS)

Škoda, Petr; Palička, Andrej; Koza, Jakub; Shakurova, Ksenia

2017-06-01

The current archives of LAMOST multi-object spectrograph contain millions of fully reduced spectra, from which the automatic pipelines have produced catalogues of many parameters of individual objects, including their approximate spectral classification. This is, however, mostly based on the global shape of the whole spectrum and on integral properties of spectra in given bandpasses, namely presence and equivalent width of prominent spectral lines, while for identification of some interesting object types (e.g. Be stars or quasars) the detailed shape of only a few lines is crucial. Here the machine learning is bringing a new methodology capable of improving the reliability of classification of such objects even in boundary cases. We present results of Spark-based semi-supervised machine learning of LAMOST spectra attempting to automatically identify the single and double-peak emission of Hα line typical for Be and B[e] stars. The labelled sample was obtained from archive of 2m Perek telescope at Ondřejov observatory. A simple physical model of spectrograph resolution was used in domain adaptation to LAMOST training domain. The resulting list of candidates contains dozens of Be stars (some are likely yet unknown), but also a bunch of interesting objects resembling spectra of quasars and even blazars, as well as many instrumental artefacts. The verification of a nature of interesting candidates benefited considerably from cross-matching and visualisation in the Virtual Observatory environment.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rasca, Anthony P.; Chen, James; Pevtsov, Alexei A., E-mail: anthony.rasca.ctr@nrl.navy.mil

Recent observations of the photosphere using high spatial and temporal resolution show small dynamic features at or below the current resolving limits. A new pixel dynamics method has been developed to analyze spectral profiles and quantify changes in line displacement, width, asymmetry, and peakedness of photospheric absorption lines. The algorithm evaluates variations of line profile properties in each pixel and determines the statistics of such fluctuations averaged over all pixels in a given region. The method has been used to derive statistical characteristics of pixel fluctuations in observed quiet-Sun regions, an active region with no eruption, and an active regionmore » with an ongoing eruption. Using Stokes I images from the Vector Spectromagnetograph (VSM) of the Synoptic Optical Long-term Investigations of the Sun (SOLIS) telescope on 2012 March 13, variations in line width and peakedness of Fe i 6301.5 Å are shown to have a distinct spatial and temporal relationship with an M7.9 X-ray flare in NOAA 11429. This relationship is observed as stationary and contiguous patches of pixels adjacent to a sunspot exhibiting intense flattening in the line profile and line-center displacement as the X-ray flare approaches peak intensity, which is not present in area scans of the non-eruptive active region. The analysis of pixel dynamics allows one to extract quantitative information on differences in plasma dynamics on sub-pixel scales in these photospheric regions. The analysis can be extended to include the Stokes parameters and study signatures of vector components of magnetic fields and coupled plasma properties.« less

Note: Broadly tunable all-fiber ytterbium laser with 0.05 nm spectral width based on multimode interference filter.

PubMed

Mukhopadhyay, Pranab K; Gupta, Pradeep K; Singh, Amarjeet; Sharma, Sunil K; Bindra, Kushvinder S; Oak, Shrikant M

2014-05-01

A multimode interference filter with narrow transmission bandwidth and large self-imaging wavelength interval is constructed and implemented in an ytterbium doped fiber laser in all-fiber format for broad wavelength tunability as well as narrow spectral width of the output beam. The peak transmission wavelength of the multimode interference filter was tuned with the help of a standard in-fiber polarization controller. With this simple mechanism more than 30 nm (1038 nm-1070 nm) tuning range is demonstrated. The spectral width of the output beam from the laser was measured to be 0.05 nm.

Note: Broadly tunable all-fiber ytterbium laser with 0.05 nm spectral width based on multimode interference filter

NASA Astrophysics Data System (ADS)

Mukhopadhyay, Pranab K.; Gupta, Pradeep K.; Singh, Amarjeet; Sharma, Sunil K.; Bindra, Kushvinder S.; Oak, Shrikant M.

2014-05-01

A multimode interference filter with narrow transmission bandwidth and large self-imaging wavelength interval is constructed and implemented in an ytterbium doped fiber laser in all-fiber format for broad wavelength tunability as well as narrow spectral width of the output beam. The peak transmission wavelength of the multimode interference filter was tuned with the help of a standard in-fiber polarization controller. With this simple mechanism more than 30 nm (1038 nm-1070 nm) tuning range is demonstrated. The spectral width of the output beam from the laser was measured to be 0.05 nm.

Note: Broadly tunable all-fiber ytterbium laser with 0.05 nm spectral width based on multimode interference filter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mukhopadhyay, Pranab K., E-mail: pkm@rrcat.gov.in; Gupta, Pradeep K.; Singh, Amarjeet

2014-05-15

A multimode interference filter with narrow transmission bandwidth and large self-imaging wavelength interval is constructed and implemented in an ytterbium doped fiber laser in all-fiber format for broad wavelength tunability as well as narrow spectral width of the output beam. The peak transmission wavelength of the multimode interference filter was tuned with the help of a standard in-fiber polarization controller. With this simple mechanism more than 30 nm (1038 nm–1070 nm) tuning range is demonstrated. The spectral width of the output beam from the laser was measured to be 0.05 nm.

Wavelength dependence of the Brillouin spectral width of boron doped germanosilicate optical fibers.

PubMed

Law, Pi-Cheng; Dragic, Peter D

2010-08-30

Boron co-doped germanosilicate fibers are investigated via the Brillouin light scattering technique using two wavelengths, 1534 nm and 1064 nm. Several fibers are investigated, including four drawn from the same preform but at different draw temperatures. The Stokes' shifts and the Brillouin spectral widths are found to increase with increasing fiber draw temperature. A frequency-squared law has adequately described the wavelength dependence of the Brillouin spectral width of conventional Ge-doped fibers. However, it is found that unlike conventional Ge-doped fibers these fibers do not follow the frequency-squared law. This is explained through a frequency-dependent dynamic viscosity that modifies this law.

Improving spectral resolution in spatial encoding dimension of single-scan nuclear magnetic resonance 2D spin echo correlated spectroscopy

NASA Astrophysics Data System (ADS)

Lin, Liangjie; Wei, Zhiliang; Yang, Jian; Lin, Yanqin; Chen, Zhong

2014-11-01

The spatial encoding technique can be used to accelerate the acquisition of multi-dimensional nuclear magnetic resonance spectra. However, with this technique, we have to make trade-offs between the spectral width and the resolution in the spatial encoding dimension (F1 dimension), resulting in the difficulty of covering large spectral widths while preserving acceptable resolutions for spatial encoding spectra. In this study, a selective shifting method is proposed to overcome the aforementioned drawback. This method is capable of narrowing spectral widths and improving spectral resolutions in spatial encoding dimensions by selectively shifting certain peaks in spectra of the ultrafast version of spin echo correlated spectroscopy (UFSECSY). This method can also serve as a powerful tool to obtain high-resolution correlated spectra in inhomogeneous magnetic fields for its resistance to any inhomogeneity in the F1 dimension inherited from UFSECSY. Theoretical derivations and experiments have been carried out to demonstrate performances of the proposed method. Results show that the spectral width in spatial encoding dimension can be reduced by shortening distances between cross peaks and axial peaks with the proposed method and the expected resolution improvement can be achieved. Finally, the shifting-absent spectrum can be recovered readily by post-processing.

The rebirth of Supernova 1987A : a study of the ejecta-ring collision

NASA Astrophysics Data System (ADS)

Gröningsson, Per

Supernovae are some of the most energetic phenomena in the Universe and they have throughout history fascinated people as they appeared as new stars in the sky. Supernova (SN) 1987A exploded in the nearby satellite galaxy, the Large Magellanic Cloud (LMC), at a distance of only 168,000 light years. The proximity of SN 1987A offers a unique opportunity to study the medium surrounding the supernova in great detail. Powered by the dynamical interaction of the ejecta with the inner circumstellar ring, SN 1987A is dramatically evolving at all wavelengths on time scales less than a year. This makes SN 1987A a great ``laboratory'' for studies of shock physics. Repeated observations of the ejecta-ring collision have been carried out using the UVES echelle spectrograph at VLT. This thesis covers seven epochs of high resolution spectra taken between October 1999 and November 2007. Three different emission line components are identified from the spectra. A narrow (~10 km/s) velocity component emerges from the unshocked ring. An intermediate (~250 km/s) component arises in the shocked ring, and a broad component extending to ~15,000 km/s comes from the reverse shock. Thanks to the high spectral resolution of UVES, it has been possible to separate the shocked from the unshocked ring emission. For the unshocked gas, ionization stages from neutral up to Ne V and Fe VII were found. The line fluxes of the low-ionization lines decline during the period of the observations. However, the fluxes of the [O III] and [Ne III] lines appear to increase and this is found to be consistent with the heating of the pre-shock gas by X-rays from the shock interactions. The line emission from the ejecta-ring collision increases rapidly as more gas is swept up by the shocks. This emission comes from ions with a range of ionization stages (e.g., Fe II-XIV). The low-ionization lines show an increase in their line widths which is consistent with that these lines originate from radiative shocks. The high-ionization line profiles (Fe X-XIV) initially show larger spectral widths, which indicates that at least a fraction of the emission comes from non-radiative shocks.

Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter

NASA Astrophysics Data System (ADS)

Martínez-Arnáiz, R.; Maldonado, J.; Montes, D.; Eiroa, C.; Montesinos, B.

2010-09-01

Context. Chromospheric activity produces both photometric and spectroscopic variations that can be mistaken as planets. Large spots crossing the stellar disc can produce planet-like periodic variations in the light curve of a star. These spots clearly affect the spectral line profiles, and their perturbations alter the line centroids creating a radial velocity jitter that might “contaminate” the variations induced by a planet. Precise chromospheric activity measurements are needed to estimate the activity-induced noise that should be expected for a given star. Aims: We obtain precise chromospheric activity measurements and projected rotational velocities for nearby (d ≤ 25 pc) cool (spectral types F to K) stars, to estimate their expected activity-related jitter. As a complementary objective, we attempt to obtain relationships between fluxes in different activity indicator lines, that permit a transformation of traditional activity indicators, i.e., Ca ii H & K lines, to others that hold noteworthy advantages. Methods: We used high resolution (~50 000) echelle optical spectra. Standard data reduction was performed using the IRAF echelle package. To determine the chromospheric emission of the stars in the sample, we used the spectral subtraction technique. We measured the equivalent widths of the chromospheric emission lines in the subtracted spectrum and transformed them into fluxes by applying empirical equivalent width and flux relationships. Rotational velocities were determined using the cross-correlation technique. To infer activity-related radial velocity (RV) jitter, we used empirical relationships between this jitter and the R'_HK index. Results: We measured chromospheric activity, as given by different indicators throughout the optical spectra, and projected rotational velocities for 371 nearby cool stars. We have built empirical relationships among the most important chromospheric emission lines. Finally, we used the measured chromospheric activity to estimate the expected RV jitter for the active stars in the sample. Based on observations made with the 2.2 m telescope at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto (Spain) and the Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Istituto Nazionale de Astrofisica Italiano (INAF), in the Spanish Observatorio del Roque de los Muchachos. This research has been supported by the Programa de Acceso a Infraestructuras Científicas y Tecnológicas Singulares (ICTS).Tables A1 to A4 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/520/A79

Changes in the Far UV Spectrum of Eta Carinae Near the 2003 Minimum

NASA Technical Reports Server (NTRS)

Iping, R. C.; Gull, T. R.; Sonneborn, G.; Massa, D.; Vieira, G. L.; Nielsen, K. E.

2004-01-01

High resolution 905-1180 spectra of \\eta Carinae have been obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite at nine epochs between February 2000 and June 2003 . This period of time extends from the broad maximum up to the very beginning of the minimum of the 5.52-year period initially discovered by A. Damineli. The flux levels were unchanged between February 2000 through February 2003 with minor spectral differences. The X-Ray minimum started on June 29, 2003 . Three observations were accomplished on June 10, June 17 and June 27 leading up to the minimum. Substantial changes were present in the June 10 and June 17 spectra, but a very significant change occurred by June 27, 2003. Longward of 1100A, the overall flux dropped 10 to 30 %. Shortward of 1100A, there are spectral intervals with NO decrease in flux even down to the shortest wavelengths (920--950 ). This indicates that dust absorption has a negligible role in the observed spectral changes and that line absorptions play a major role. Throughout the spectrum there are intervals ranging in width of 3-10A with strong increased absorption. Significant absorptions may be associated with the red portion of the following stellar wind lines: C III 977, O VI 1031,1037, P V 1117, while other absorption features are much broader, more extended and not clearly associated with well-known spectral transitions. Given the complexity of the STIS echelle spectra taken in this period of time, many of these absorption features are likely due to multiple absorption lines

Broad-band properties of the CfA Seyfert galaxies. III - Ultraviolet variability

NASA Technical Reports Server (NTRS)

Edelson, R. A.; Pike, G. F.; Krolik, J. H.

1990-01-01

A total of 657 archived IUE spectra are used to study the UV variability properties of six members of the CfA Seyfert I galaxy sample. All show strong evidence for continuum and line variations and a tendency for less luminous objects to be more strongly variable. Most objects show a clear correlation at zero lag between UV spectral index and luminosity, evidence that the variable component is an accretion disk around a black hole which is systematically smaller in less luminous sources. No correlation is seen between the continuum luminosity and equivalent width of the C IV, Mg II, and semiforbidden C III emission lines when the entire sample is examined, but a clear anticorrelation is present when only repeated observations of individual objects are considered. This is due to a combination of light-travel time effects in the broad-line region and the nonlinear responses of lines to continuum fluctuations.

A Coordinated X-Ray and Optical Campaign of the Nearest Massive Eclipsing Binary, Delta Orionis Aa. II. X-Ray Variability

NASA Technical Reports Server (NTRS)

Nichols, J.; Huenemoerder, D. P.; Corcoran, M. F.; Waldron, W.; Naze, Y.; Pollock, A. M. T.; Moffat, A. F. J.; Lauer, J.; Shenar, T.; Russell, C. M. P.;

THE CORES OF THE Fe K{alpha} LINES IN ACTIVE GALACTIC NUCLEI: AN EXTENDED CHANDRA HIGH ENERGY GRATING SAMPLE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shu, X. W.; Wang, J. X.; Yaqoob, T.

We extend the study of the core of the Fe K{alpha} emission line at {approx}6.4 keV in Seyfert galaxies reported by Yaqoob and Padmanabhan using a larger sample observed by the Chandra high-energy grating (HEG). The sample consists of 82 observations of 36 unique sources with z < 0.3. Whilst heavily obscured active galactic nuclei are excluded from the sample, these data offer some of the highest precision measurements of the peak energy of the Fe K{alpha} line, and the highest spectral resolution measurements of the width of the core of the line in unobscured and moderately obscured (N {submore » H} < 10{sup 23} cm{sup -2}) Seyfert galaxies to date. From an empirical and uniform analysis, we present measurements of the Fe K{alpha} line centroid energy, flux, equivalent width (EW), and intrinsic width (FWHM). The Fe K{alpha} line is detected in 33 sources, and its centroid energy is constrained in 32 sources. In 27 sources, the statistical quality of the data is good enough to yield measurements of the FWHM. We find that the distribution in the line centroid energy is strongly peaked around the value for neutral Fe, with over 80% of the observations giving values in the range 6.38-6.43 keV. Including statistical errors, 30 out of 32 sources ({approx}94%) have a line centroid energy in the range 6.35-6.47 keV. The mean EW, among the observations in which a non-zero lower limit could be measured, was 53 {+-} 3 eV. The mean FWHM from the subsample of 27 sources was 2060 {+-} 230 km s{sup -1}. The mean EW and FWHM are somewhat higher when multiple observations for a given source are averaged. From a comparison with the H{beta} optical emission-line widths (or, for one source, Br{alpha}), we find that there is no universal location of the Fe K{alpha} line-emitting region relative to the optical broad-line region (BLR). In general, a given source may have contributions to the Fe K{alpha} line flux from parsec-scale distances from the putative black hole, down to matter a factor {approx}2 closer to the black hole than the BLR. We confirm the presence of the X-ray Baldwin effect, an anti-correlation between the Fe K{alpha} line EW and X-ray continuum luminosity. The HEG data have enabled isolation of this effect to the narrow core of the Fe K{alpha} line.« less

Spectroscopic Peculiarity of the Herbig Be Star HD 259431

NASA Astrophysics Data System (ADS)

Pogodin, M. A.; Pavlovskij, S. E.; Drake, N. A.; Beskrovnaya, N. G.; Kozlova, O. V.; Alekseev, I. Yu.; Borges Fernandes, M.; Pereira, C. B.; Valyavin, G.

2017-06-01

High-resolution spectra of the Herbig Be star HD 259431 obtained in 2010-2016 at three observatories (Crimean AO, ESO in Chile, and OAN SPN in Mexico) are analysed. The object demonstrates a very rich emission line profile spectrum. The bulk of the lines exhibit double-peaked emission profiles and originate in the gaseous disk. The atmospheric lines are unusually shallow, and majority of them are distorted by the circumstellar (CS) contribution. Moreover, we have revealed that they are overlapped with an additional continuum emission. Using the observed ratio of the equivalent widths of two He I λ 4009 and 4026 lines, we estimated the spectral type of the object as B5 V. We also constructed the spectral energy distribution of the additional continuum using wide wings of the atmospheric Hβ-Hɛ lines free of the CS contribution. The continuum corresponds to the blue part of the black body spectrum. The Hβ - Hɛ Balmer emission lines show very variable profiles looking as either of P Cyg-type or a double-peaked emission line with a depression of the red wing. We found the period of this variability P = 2.630d and interpreted it as a sign of a rotating magnetosphere of the star with the magnetic axis inclined to the rotation axis. At different phases of rotation, the observer can see either an accretion flow at high magnetic latitudes or a wind zone at lower latitudes. We also estimated the inclination of the rotation axis i = 52°±1°.

Using the Properties of Broad Absorption Line Quasars to Illuminate Quasar Structure

NASA Astrophysics Data System (ADS)

Yong, Suk Yee; King, Anthea L.; Webster, Rachel L.; Bate, Nicholas F.; O'Dowd, Matthew J.; Labrie, Kathleen

2018-06-01

A key to understanding quasar unification paradigms is the emission properties of broad absorption line quasars (BALQs). The fact that only a small fraction of quasar spectra exhibit deep absorption troughs blueward of the broad permitted emission lines provides a crucial clue to the structure of quasar emitting regions. To learn whether it is possible to discriminate between the BALQ and non-BALQ populations given the observed spectral properties of a quasar, we employ two approaches: one based on statistical methods and the other supervised machine learning classification, applied to quasar samples from the Sloan Digital Sky Survey. The features explored include continuum and emission line properties, in particular the absolute magnitude, redshift, spectral index, line width, asymmetry, strength, and relative velocity offsets of high-ionisation C IV λ1549 and low-ionisation Mg II λ2798 lines. We consider a complete population of quasars, and assume that the statistical distributions of properties represent all angles where the quasar is viewed without obscuration. The distributions of the BALQ and non-BALQ sample properties show few significant differences. None of the observed continuum and emission line features are capable of differentiating between the two samples. Most published narrow disk-wind models are inconsistent with these observations, and an alternative disk-wind model is proposed. The key feature of the proposed model is a disk-wind filling a wide opening angle with multiple radial streams of dense clumps.

Geocoronal Balmer α line profile observations and forward-model analysis

NASA Astrophysics Data System (ADS)

Mierkiewicz, E. J.; Bishop, J.; Roesler, F. L.; Nossal, S. M.

2006-05-01

High spectral resolution geocoronal Balmer α line profile observations from Pine Bluff Observatory (PBO) are presented in the context of forward-model analysis. Because Balmer series column emissions depend significantly on multiple scattering, retrieval of hydrogen parameters of general aeronomic interest from these observations (e.g., the hydrogen column abundance) currently requires a forward modeling approach. This capability is provided by the resonance radiative transfer code LYAO_RT. We have recently developed a parametric data-model comparison search procedure employing an extensive grid of radiative transport model input parameters (defining a 6-dimensional parameter space) to map-out bounds for feasible forward model retrieved atomic hydrogen density distributions. We applied this technique to same-night (March, 2000) ground-based Balmer α data from PBO and geocoronal Lyman β measurements from the Espectrógrafo Ultravioleta extremo para la Radiación Difusa (EURD) instrument on the Spanish satellite MINISAT-1 (provided by J.F. Gómez and C. Morales of the Laboratorio de Astrofisica Espacial y Física Fundamental, INTA, Madrid, Spain) in order to investigate the modeling constraints imposed by two sets of independent geocoronal intensity measurements, both of which rely on astronomical calibration methods. In this poster we explore extending this analysis to the line profile information also contained in the March 2000 PBO Balmer α data set. In general, a decrease in the Doppler width of the Balmer α emission with shadow altitude is a persistent feature in every night of PBO observations in which a wide range of shadow altitudes are observed. Preliminary applications of the LYAO_RT code, which includes the ability to output Doppler line profiles for both the singly and multiply scattered contributions to the Balmer α emission line, displays good qualitative agreement with regard to geocoronal Doppler width trends observed from PBO. Model-data Balmer α Doppler width comparisons, using the best-fit model parameters obtained during the March 2000 PBO/EURD forward-model study, will be presented and discussed, including the feasibility of using Balmer α observed Doppler widths as an additional model constraint in our forward-model search procedure.

A new X-ray spectral observation of NGC 1068

NASA Technical Reports Server (NTRS)

Marshall, F. E.; Netzer, H.; Arnaud, K. A.; Boldt, E. A.; Holt, S. S.; Jahoda, K. M.; Kelley, R.; Mushotzky, R. F.; Petre, R.; Serlemitsos, P. J.

1993-01-01

A new X-ray observation of NGC 1068, in which improved spectral resolution (R is approximately equal to 40) and broad energy range provide important new constraints on models for this galaxy, is reported. The observed X-ray continuum of NGC 1068 from 0.3 to 10 keV is well fitted as the sum of two power-law spectra with no evidence for absorption intrinsic to the source. Strong Fe K emission lines with a total equivalent width of 2700 eV were detected due to iron less ionized than Fe XX and to iron more ionized than Fe XXIII. No evidence was seen for lines due to the recombination of highly ionized oxygen with an upper limit for the O Ly-alpha emission line of 40 eV. The discovery of multiple Fe K and Fe L emission lines indicates a broad range of ionization states for this gas. The X-ray emission from the two components is modeled for various geometries using a photoionization code that calculates the temperature and ionization state of the gas. Typical model parameters are a total Compton depth of a few percent, an inner boundary of the hot component of about 1 pc, and an inner boundary of the warm component of about 20 pc.

The SAMI Galaxy Survey: Data Release One with emission-line physics value-added products

NASA Astrophysics Data System (ADS)

Green, Andrew W.; Croom, Scott M.; Scott, Nicholas; Cortese, Luca; Medling, Anne M.; D'Eugenio, Francesco; Bryant, Julia J.; Bland-Hawthorn, Joss; Allen, J. T.; Sharp, Rob; Ho, I.-Ting; Groves, Brent; Drinkwater, Michael J.; Mannering, Elizabeth; Harischandra, Lloyd; van de Sande, Jesse; Thomas, Adam D.; O'Toole, Simon; McDermid, Richard M.; Vuong, Minh; Sealey, Katrina; Bauer, Amanda E.; Brough, S.; Catinella, Barbara; Cecil, Gerald; Colless, Matthew; Couch, Warrick J.; Driver, Simon P.; Federrath, Christoph; Foster, Caroline; Goodwin, Michael; Hampton, Elise J.; Hopkins, A. M.; Jones, D. Heath; Konstantopoulos, Iraklis S.; Lawrence, J. S.; Leon-Saval, Sergio G.; Liske, Jochen; López-Sánchez, Ángel R.; Lorente, Nuria P. F.; Mould, Jeremy; Obreschkow, Danail; Owers, Matt S.; Richards, Samuel N.; Robotham, Aaron S. G.; Schaefer, Adam L.; Sweet, Sarah M.; Taranu, Dan S.; Tescari, Edoardo; Tonini, Chiara; Zafar, T.

2018-03-01

We present the first major release of data from the SAMI Galaxy Survey. This data release focuses on the emission-line physics of galaxies. Data Release One includes data for 772 galaxies, about 20 per cent of the full survey. Galaxies included have the redshift range 0.004 < z < 0.092, a large mass range (7.6 < log M*/ M⊙ < 11.6), and star formation rates of ˜10-4 to ˜101M⊙ yr-1. For each galaxy, we include two spectral cubes and a set of spatially resolved 2D maps: single- and multi-component emission-line fits (with dust-extinction corrections for strong lines), local dust extinction, and star formation rate. Calibration of the fibre throughputs, fluxes, and differential atmospheric refraction has been improved over the Early Data Release. The data have average spatial resolution of 2.16 arcsec (full width at half-maximum) over the 15 arcsec diameter field of view and spectral (kinematic) resolution of R = 4263 (σ = 30 km s-1) around H α. The relative flux calibration is better than 5 per cent, and absolute flux calibration has an rms of 10 per cent. The data are presented online through the Australian Astronomical Observatory's Data Central.

Outburst Cycle of the Dwarf Nova SS Cygni

NASA Astrophysics Data System (ADS)

Voikhanskaya, N. F.

2018-01-01

Extensive observational data obtained to date is analyzed with special attention given to space observations. The spectral type of the white dwarf is estimated and it is concluded that accretion of matter on it is the only source of the x-ray flux in the system. The rotation of the secondary is shown to be synchronous and therefore its illumination by hard x-rays results in the formation of stellar wind. This is the main mechanism of mass transfer onto the white dwarf. The geometry of the system prevents the formation of the disk by stellar wind. Instead, stellar wind forms a quasispherical envelope whose variability influences the outburst process. Based on these conclusions, the properties of the system are interpreted, which so far have remained unexplained: short-term appearance of peculiar spectrum during the rising phase of the outburst, rather constant width of absorption lines during the outburst, decrease of the width of emission lines during the outburst, variation of the x-ray and ultraviolet fluxes during ordinary and low-amplitude anomalous outbursts, and, finally, the quasiperiodicity of the outbursts.

The effect of line damping, magneto-optics and parasitic light on the derivation of sunspot vector magnetic fields

NASA Technical Reports Server (NTRS)

Skumanich, A.; Lites, B. W.

1985-01-01

The least square fitting of Stokes observations of sunspots using a Milne-Eddington-Unno model appears to lead, in many circumstances, to various inconsistencies such as anomalously large doppler widths and, hence, small magnetic fields which are significantly below those inferred solely from the Zeeman splitting in the intensity profile. It is found that the introduction of additional physics into the model such as the inclusion of damping wings and magneto-optic birefrigence significantly improves the fit to Stokes parameters. Model fits excluding the intensity profile, i.e., of both magnitude as well as spectral shape of the polarization parameters alone, suggest that parasitic light in the intensity profile may also be a source of inconsistencies. The consequences of the physical changes on the vector properties of the field derived from the Fe I lambda 6173 line for the 17 November 1975 spot as well as on the thermodynamic state are discussed. A Doppler width delta lambda (D) - 25mA is bound to be consistent with a low spot temperature and microturbulence, and a damping constant of a = 0.2.

Discovery of a GeV blazar shining through the galactic plane

DOE PAGES

Vandenbroucke, J.; Buehler, R.; Ajello, M.; ...

2010-07-14

The Fermi Large Area Telescope (LAT) discovered a new gamma-ray source near the Galactic plane, Fermi J0109+6134, when it flared brightly in 2010 February. The low Galactic latitude (b = –1more » $$ο\\atop{.}$$2) indicated that the source could be located within the Galaxy, which motivated rapid multi-wavelength follow-up including radio, optical, and X-ray observations. Here, we report the results of analyzing all 19 months of LAT data for the source, and of X-ray observations with both Swift and the Chandra X-ray Observatory. We determined the source redshift, z = 0.783, using a Keck Low-Resolution Imaging Spectrometer observation. Finally, we compiled a broadband spectral energy distribution (SED) from both historical and new observations contemporaneous with the 2010 February flare. The redshift, SED, optical line width, X-ray absorption, and multi-band variability indicate that this new GeV source is a blazar seen through the Galactic plane. Because several of the optical emission lines have equivalent width >5 Å, this blazar belongs in the flat-spectrum radio quasar category.« less

Relaxation Matrix for Symmetric Tops with Inversion Symmetry: Line Coupling and Line Mixing Effects on NH3 Lines in the V4 Band

NASA Technical Reports Server (NTRS)

Ma, Q.; Boulet, C.; Tipping, R. H.

2017-01-01

Line shape parameters including the half-widths and the off-diagonal elements of the relaxation matrix have been calculated for self-broadened NH3 lines in the perpendicular v4 band. As in the pure rotational and the parallel v1 bands, the small inversion splitting in this band causes a complete failure of the isolated line approximation. As a result, one has to use formalisms not relying on this approximation. However, due to differences between parallel and perpendicular bands of NH3, the applicability of the formalism used in our previous studies of the v1 band and other parallel bands must be carefully verified. We have found that, as long as potential models only contain components with K1 equals K2 equals 0, whose matrix elements require the selection rule delta k equals 0, the formalism is applicable for the v4 band with some minor adjustments. Based on both theoretical considerations and results from numerical calculations, the non-diagonality of the relaxation matrices in all the PP, RP, PQ, RQ, PR, and RR branches is discussed. Theoretically calculated self-broadened half-widths are compared with measurements and the values listed in HITRAN 2012. With respect to line coupling effects, we have compared our calculated intra-doublet off-diagonal elements of the relaxation matrix with reliable measurements carried out in the PP branch where the spectral environment is favorable. The agreement is rather good since our results do well reproduce the observed k and j dependences of these elements, thus validating our formalism.

Observation and modelling of main-sequence star chromospheres - X. Radiative budgets on Gl 867A and AU Mic (dM1e), and a two-component model chromosphere for Gl 205 (dM1)

NASA Astrophysics Data System (ADS)

Houdebine, E. R.

2010-04-01

We report on high-resolution observations of two dM1 stars: Gl 867A, an active dM1e star, and Gl 205, a less active dM1 star. The wavelength coverage is from 3890 to 6820Å with a resolving power of about 45000. The difference spectrum of these two stars allows us to make a survey of spectral lines sensitive to magnetic activity. We chose these two stars because, to within measurement errors, they have very close properties: Gl 867A has R = 0.726Rsolar, [M/H] = 0.080 dex and Teff = 3416 K, and Gl 205 has R = 0.758Rsolar, [M/H] = 0.101 dex and Teff = 3493 K. We find that besides traditional chromospheric lines, many photospheric lines are `filled-in' in the active star spectrum. These differences are, most of the time, weak in absolute fluxes but can be large in terms of differences in the spectral-line equivalent widths. We calculate the differences in surface fluxes between these two stars for many spectral lines. We derive the radiative budgets for two dM1e stars: Gl 867A and AU Mic. We show that the sum of the numerous spectral lines represents a significant fraction of the radiative cooling of the outer atmosphere. We also re-investigate the cooling from the continuum from the visible to the extreme ultraviolet; we find that earlier predictions of the calculations of Houdebine et al. (Paper V) are in good agreement with observations. We emphasize that if this radiative cooling is chromospheric in character, then in chromospheric model calculations, we should include the radiative losses in CaI, CrI, VI, TiI and FeI. From simple constraints, we derive model chromospheres for quiescent and active regions on Gl 205. We show that the quiescent regions have a strong absorption Hα profile. The plage regions show a filled-in intermediate activity Hα profile. We also present possible spectral line profiles of quiescent and active regions on Gl 867A. Based on observations collected at Observatoire de Haute Provence, France. E-mail: eric_houdebine@yahoo.fr

Evidence for a massive stellar black hole in x ray Nova Muscae

NASA Technical Reports Server (NTRS)

Chen, Wan; Gehrels, Neil; Cheng, F. H.

1992-01-01

We present evidence that the X-ray Nova Muscae system contains a massive, greater than 10 M solarmass, black hole. A recently measured photometric binary mass function gives the black hole mass for this system as a function of orbital inclination angle. From the spectral redshift and width of the positron annihilation gamma-ray line observed by GRANAT/SIGMA, we find the accretion disk inclination angle to be 22 deg plus or minus 18 deg. Assuming the accretion disk lies in the orbital plane of the system, the black hole mass is found to have a lower limit of 14 M solar mass although statistics are poor. This is supported by spectral modeling of combined optical/UV/x-ray/gamma-ray data and by a new Nova Muscae distance limit we derive of greater than 3 kpc. The large mass for this black hole and the high binary mass ratio it implies (greater than 20) raise a serious challenge to theoretical models of the formation and evolution of massive binaries. The gamma-ray line technique introduced here can give tight constraints on orbital parameters when high-sensitivity line measurements are made by such missions as GRO.

Atmospheric Temperature Profile Measurements Using Mobile High Spectral Resolution Lidar

NASA Astrophysics Data System (ADS)

Razenkov, Ilya I.; Eloranta, Edwin W.

2016-06-01

The High Spectral Resolution Lidar (HSRL) designed at the University of Wisconsin-Madison discriminates between Mie and Rayleigh backscattering [1]. It exploits the Doppler effect caused by thermal motion of molecules, which broadens the spectrum of the transmitted laser light. That allows for absolute calibration of the lidar and measurements of the aerosol volume backscatter coefficient. Two iodine absorption filters with different absorption line widths (a regular iodine vapor filter and Argon buffered iodine filter) allow for atmospheric temperature profile measurements. The sensitivity of the measured signal-to-air temperature ratio is around 0.14%/K. The instrument uses a shared telescope transmitter-receiver design and operates in eyesafe mode (the product of laser average power and telescope aperture equals 0.1 Wm2 at 532 nm).

Emission line shapes produced by dissociative excitation of atmospheric gases

NASA Technical Reports Server (NTRS)

Zipf, E. C.; Wells, W. C.

1980-01-01

The spectral line shapes of the radiation emitted from O atoms produced by the dissociative excitation of O2, CO, CO2 and NO are investigated. Doppler line shapes are derived from time-of-flight spectra of O (5S0) atoms decaying by the emission of 1356-A radiation after being produced in electron impact experiments at incident electron energies from 25 to 300 eV. It is shown that the effective line width of the radiation is large compared with the Doppler absorption widths of ambient O atoms in both photoelectron and auroral excitation, and thus the dissociatively excited component of the O I 1304-A airglow will behave as though it were optically thin, exhibiting pronounced limb brightening effects and a scale height characteristic of the initial, local source function. It is found that the average kinetic energy of the dissociation fragments inferred from O I (5S) time-of-flight spectra is in good agreement with that of O I (3S) atoms in the electron impact dissociation of CO2, although not for O2. Finally, it is suggested that although electron impact dissociation of CO and CO2 contributes to the 1304-A emission in the upper atmosphere of Venus, it cannot be the dominant source of this radiation since the absolute cross sections for the reaction are too small.

A near infrared classification of pre-main sequence stars

NASA Astrophysics Data System (ADS)

Alonso-Martínez, M.; Meeus, G.; Eiroa, C.

2017-03-01

T Tauri stars are young solar analogues (M ≤ 1.5M_{⊙}), harbouring a disc and with ongoing accretion. The T Tauri phase has been estimated to last around 10 Myr. We have obtained J and K band spectra with WHT/LIRIS and NOT/NOTCam of 112 T Tauri stars in the Taurus star forming region. By measuring the equivalent widths of common and strong spectral features, known to follow a tight relation with temperature, we aim at providing a direct and fast method to derive stellar effective temperatures. Line ratios of strong absorption features relatively close in wavelength are used to overcome the effects of veiling. Besides, the Al I (1.313μm) line is strongly gravity-dependent and used to discern between surface gravities. Finally, we estimate accretion rates using the H-lines Pa-β and Br-γ.

High-Resolution Spectroscopy of [Ne II] Emission from AA Tau and GM Aur

NASA Astrophysics Data System (ADS)

Najita, Joan R.; Doppmann, Greg W.; Bitner, Martin A.; Richter, Matthew J.; Lacy, John H.; Jaffe, Daniel T.; Carr, John S.; Meijerink, Rowin; Blake, Geoffrey A.; Herczeg, Gregory J.; Glassgold, Alfred E.

2009-05-01

We present high-resolution (R = 80,000) spectroscopy of [Ne II] emission from two young stars, GM Aur and AA Tau, which have moderate to high inclinations. The emission from both sources appears centered near the stellar velocity and is broader than the [Ne II] emission measured previously for the face-on disk system TW Hya. These properties are consistent with a disk origin for the [Ne II] emission we detect, with disk rotation (rather than photoevaporation or turbulence in a hot disk atmosphere) playing the dominant role in the origin of the line width. In the non-face-on systems, the [Ne II] emission is narrower than the CO fundamental emission from the same sources. If the widths of both diagnostics are dominated by Keplerian rotation, this suggests that the [Ne II] emission arises from larger disk radii on average than does the CO emission. The equivalent width of the [Ne II] emission we detect is less than that of the spectrally unresolved [Ne II] feature in the Spitzer spectra of the same sources. Variability in the [Ne II] emission or the mid-infrared continuum, a spatially extended [Ne II] component, or a very (spectrally) broad [Ne II] component might account for the difference in the equivalent widths. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministrio da Cincia e Tecnologia (Brazil), and SECYT (Argentina).

Collision Induced Velocity Changes from Molecular Dynamic Simulations. Application to the Spectral Shape of the Q(1) Raman Lines of H{_2}/H{_2}

NASA Astrophysics Data System (ADS)

Tran, H.; Hartmann, J. M.

2011-06-01

Collision induced velocity changes for pure H{_2} have been computed from classical dynamic simulations. The results have been compared with the Keilson-Storer model from four different points of view. The first involves various autocorrelation functions associated with the velocity. The second and third give more detailed information, and are time evolutions of some conditional probabilities for changes of the velocity modulus and orientation and the collision kernels themselves. The fourth considers the evolutions, with density, of the half widths of the Q(1) lines of the isotropic Raman (1-0) fundamental band and of the (2-0) overtone quadrupole band. These spectroscopic data enable an indirect test of the models since velocity changes translate into line-shape modifications through the speed dependence of collisional parameters and the Dicke narrowing of the Doppler contribution to the profile. The results indicate that, while the KS approach gives a poor description of detailed velocity-to-velocty changes, it leads to accurate results for the correlation functions and spectral shapes, quantities related to large averages over the velocity. It is also shown that the use of collision kernels directly derived from MDS lead to an almost perfect prediction of all considered quantities (correlation functions, conditional probabilities, and spectral shapes). Finally, the results stress the need for very accurate calculations of line-broadening and -shifting coefficients from the intermolecular potential to obviate the need for experimental data and permit fully meaningful tests of the models. H. Tran, J.M. Hartmann J. Chem. Phys. 130, 094301, 2009.

Super-narrow, extremely high quality collective plasmon resonances at telecom wavelengths and their application in a hybrid graphene-plasmonic modulator.

PubMed

Thackray, Benjamin D; Thomas, Philip A; Auton, Gregory H; Rodriguez, Francisco J; Marshall, Owen P; Kravets, Vasyl G; Grigorenko, Alexander N

2015-05-13

We present extremely narrow collective plasmon resonances observed in gold nanostripe arrays fabricated on a thin gold film, with the spectral line full width at half-maximum (fwhm) as low as 5 nm and quality factors Q reaching 300, at important fiber-optic telecommunication wavelengths around 1.5 μm. Using these resonances, we demonstrate a hybrid graphene-plasmonic modulator with the modulation depth of 20% in reflection operated by gating of a single layer graphene, the largest measured so far.

Computational chemistry and aeroassisted orbital transfer vehicles

NASA Technical Reports Server (NTRS)

Cooper, D. M.; Jaffe, R. L.; Arnold, J. O.

1985-01-01

An analysis of the radiative heating phenomena encountered during a typical aeroassisted orbital transfer vehicle (AOTV) trajectory was made to determine the potential impact of computational chemistry on AOTV design technology. Both equilibrium and nonequilibrium radiation mechanisms were considered. This analysis showed that computational chemistry can be used to predict (1) radiative intensity factors and spectroscopic data; (2) the excitation rates of both atoms and molecules; (3) high-temperature reaction rate constants for metathesis and charge exchange reactions; (4) particle ionization and neutralization rates and cross sections; and (5) spectral line widths.

A Catalog of Broad Absorption Line Quasars from the Sloan Digital Sky Survey Third Data Release

NASA Astrophysics Data System (ADS)

Trump, Jonathan R.; Hall, Patrick B.; Reichard, Timothy A.; Richards, Gordon T.; Schneider, Donald P.; Vanden Berk, Daniel E.; Knapp, Gillian R.; Anderson, Scott F.; Fan, Xiaohui; Brinkman, J.; Kleinman, S. J.; Nitta, Atsuko

2006-07-01

We present a total of 4784 unique broad absorption line quasars from the Sloan Digital Sky Survey Third Data Release. An automated algorithm was used to match a continuum to each quasar and to identify regions of flux at least 10% below the continuum over a velocity range of at least 1000 km s-1 in the C IV and Mg II absorption regions. The model continuum was selected as the best-fit match from a set of template quasar spectra binned in luminosity, emission line width, and redshift, with the power-law spectral index and amount of dust reddening as additional free parameters. We characterize our sample through the traditional ``balnicity'' index and a revised absorption index, as well as through parameters such as the width, outflow velocity, fractional depth, and number of troughs. From a sample of 16,883 quasars at 1.7<=z<=4.38, we identify 4386 (26.0%) quasars with broad C IV absorption, of which 1756 (10.4%) satisfy traditional selection criteria. From a sample of 34,973 quasars at 0.5<=z<=2.15, we identify 457 (1.31%) quasars with broad Mg II absorption, 191 (0.55%) of which satisfy traditional selection criteria. We also provide a supplementary list of 39 visually identified z>4.38 quasars with broad C IV absorption. We find that broad absorption line quasars may have broader emission lines on average than other quasars.

Line width resonance of the longitudinal optical phonon in GaAs:N

NASA Astrophysics Data System (ADS)

Mialitsin, Aleksej; Mascarenhas, Angelo

2013-03-01

We extend resonant Raman scattering studies of Mascarenhas et al. [PRB68, 233201 (2003)] of GaAs1-xNx to the ultra-dilute nitrogen doping concentrations, whereby we unambiguously resolve the line width resonances of the LO phonon. A discontinuity is observed in the LO phonon line width resonance energy as a function of concentration. With decreasing nitrogen concentration the EW line width resonance energy reduces by ca. 40 meV at x = 0 . 4 % . This value corresponds to the concentration, at which the localized to delocalized transition manifests itself in the electro-reflectance signature line widths.

Hα observations with DEFPOS

NASA Astrophysics Data System (ADS)

Sahan, M.

2011-02-01

A 7.5 cm, dual étalon Fabry-Pérot spectrometer called DEFPOS has been set up at Coudé focus of 150 cm RTT150 telescope at TUBITAK National Observatory (TUG, Antalya, Turkey) to investigate the physical properties of Diffuse Ionized Gas (DIG) in our Galaxy. The spectrometer, having a 4 arcmin circular field of view over a 200 km s-1 (4.4 Å) spectral window near Hα, has been used to observe H II regions and Planetary Nebulae (PNe) since May 2007 (Sahan et al. 2009). Early observations have been analyzed and physical and kinematic properties such as the intensity, the line width, and the LSR velocity are presented here. These values are compared with earlier results from different studies. In this study, I discuss some results obtained by DEFPOS, including two H II regions (Sh2-156, Sh2-157), and two PNe (NGC 1360, and NGC 6826). The Intensities, the radial velocities and the line widths of the Hα emission line vary from 101.4R to 149.97R (1 Rayleigh =106/4π photons cm-2 sr-1 s-1 = 2.41×10-7 erg cm-2 s-1 sr-1 at Hα), -41.19 km s-1 to +8.34 km s-1, and 39.55 km s-1 to 58.23 km s-1, respectively.

Detection of significant differences between absorption spectra of neutral helium and low temperature photoionized helium plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bartnik, A.; Wachulak, P.; Fiedorowicz, H.

2013-11-15

In this work, spectral investigations of photoionized He plasmas were performed. The photoionized plasmas were created by irradiation of helium stream, with intense pulses from laser-plasma extreme ultraviolet (EUV) source. The EUV source was based on a double-stream Xe/Ne gas-puff target irradiated with 10 ns/10 J Nd:YAG laser pulses. The most intense emission from the source spanned a relatively narrow spectral region below 20 nm, however, spectrally integrated intensity at longer wavelengths was also significant. The EUV radiation was focused onto a gas stream, injected into a vacuum chamber synchronously with the EUV pulse. The long-wavelength part of the EUVmore » radiation was used for backlighting of the photoionized plasmas to obtain absorption spectra. Both emission and absorption spectra in the EUV range were investigated. Significant differences between absorption spectra acquired for neutral helium and low temperature photoionized plasmas were demonstrated for the first time. Strong increase of intensities and spectral widths of absorption lines, together with a red shift of the K-edge, was shown.« less

Intergalactic Helium Absorption toward High-Redshift Quasars

NASA Technical Reports Server (NTRS)

Giroux, Mark L.; Fardal, Mark A.; Shull, J. Michael

1995-01-01

The recent Hubble Space Telescope (HST) observations of the z(q) = 3.286 quasar Q0302-003 (Jakobsen et at. 1994) and the z(q) = 3.185 quasar Q1935-67 by Tytler (1995) show absorption edges at the redshifted wavelength of He II 304 A. A key goal is to distinguish between contributions from discrete Ly-alpha forest clouds and a smoothly distributed intergalactic medium (IGM). We model the contributions from each of these sources of He II absorption, including the distribution of line Doppler widths and column densities, the 'He II proximity effect' from the quasar, and a self-consistent derivation of the He II opacity of the universe as a function of the spectrum of ionizing sources, with the assumption that both the clouds and the IGM are photoionized. The He II edge can be fully accounted for by He II line blanketing for reasonable distributions of line widths and column densities in the Ly-alpha forest, provided that the ionizing sources have spectral index alpha(s) greater than 1.5, and any He II proximity effect is neglected. Even with some contribution from a diffuse IGM, it is difficult to account for the edge observed by Jakobsen et al. (1994) with a 'hard' source spectrum (alpha(s) less than 1.3). The proximity effect modifies the relative contributions of the clouds and IGM to tau(He II) near the quasar (z approx. less than z(q)) and markedly increases the amount of He II absorption required. This implies, for example, that to account for the He II edge with line blanketing alone, the minimum spectral index alpha(s) must be increased from 1.5 to 1.9. We demonstrate the need for higher resolution observations that characterize the change in transmission as z approaches z(q) and resolve line-free gaps in the continuum. We set limits on the density of the diffuse IGM and suggest that the IGM and Ly-alpha clouds are likely to be a significant repository for dark baryons.

Chromospheric activity on late-type star DM UMa using high-resolution spectroscopic observations

NASA Astrophysics Data System (ADS)

Zhang, LiYun; Pi, QingFeng; Han, Xianming L.; Chang, Liang; Wang, Daimei

2016-06-01

We present new 14 high-resolution echelle spectra to discuss the level of chromospheric activity of DM UMa in {He I} D3, {Na I} D1, D2, Hα, and {Ca II} infrared triplet lines (IRT). It is the first time to discover the emissions above the continuum in the {He I} D3 lines on 2015 February 9 and 10. The emission on February 9 is the strongest one ever detected for DM UMa. We analysed these chromospheric active indicators by employing the spectral subtraction technique. The subtracted spectra reveal weak emissions in the {Na I} D1, D2 lines, strong emission in the Hα line, and clear excess emissions in the {Ca II} IRT lines. Our values for the EW8542/EW8498 ratio are on the low side, in the range of 1.0-1.7. There are also clear phase variations of the level of chromospheric activity in equivalent width (EW) light curves in these chromospheric active lines (especially the Hα line). These phenomena might be explained by flare events or rotational modulations of the level of chromospheric activity.

Evaluation of width and width uniformity of near-field electrospinning printed micro and sub-micrometer lines based on optical image processing

NASA Astrophysics Data System (ADS)

Zhao, Libo; Xia, Yong; Hebibul, Rahman; Wang, Jiuhong; Zhou, Xiangyang; Hu, Yingjie; Li, Zhikang; Luo, Guoxi; Zhao, Yulong; Jiang, Zhuangde

2018-03-01

This paper presents an experimental study using image processing to investigate width and width uniformity of sub-micrometer polyethylene oxide (PEO) lines fabricated by near-filed electrospinning (NFES) technique. An adaptive thresholding method was developed to determine the optimal gray values to accurately extract profiles of printed lines from original optical images. And it was proved with good feasibility. The mechanism of the proposed thresholding method was believed to take advantage of statistic property and get rid of halo induced errors. Triangular method and relative standard deviation (RSD) were introduced to calculate line width and width uniformity, respectively. Based on these image processing methods, the effects of process parameters including substrate speed (v), applied voltage (U), nozzle-to-collector distance (H), and syringe pump flow rate (Q) on width and width uniformity of printed lines were discussed. The research results are helpful to promote the NFES technique for fabricating high resolution micro and sub-micro lines and also helpful to optical image processing at sub-micro level.

A Library of Selenourea Precursors to PbSe Nanocrystals with Size Distributions near the Homogeneous Limit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campos, Michael P.; Hendricks, Mark P.; Beecher, Alexander N.

Here, we report a tunable library of N,N,N'-trisubstituted selenourea precursors and their reaction with lead oleate at 60–150 °C to form carboxylate-terminated PbSe nanocrystals in quantitative yields. Single exponential conversion kinetics can be tailored over 4 orders of magnitude by adjusting the selenourea structure. The wide range of conversion reactivity allows the extent of nucleation ([nanocrystal] = 4.6–56.7 μM) and the size following complete precursor conversion (d = 1.7–6.6 nm) to be controlled. Narrow size distributions (σ = 0.5–2%) are obtained whose spectral line widths are dominated (73–83%) by the intrinsic single particle spectral broadening, as observed using spectral holemore » burning measurements. Here, the intrinsic broadening decreases with increasing size (fwhm = 320–65 meV, d = 1.6–4.4 nm) that derives from exciton fine structure and exciton–phonon coupling rather than broadening caused by the size distribution.« less

A Library of Selenourea Precursors to PbSe Nanocrystals with Size Distributions near the Homogeneous Limit

DOE PAGES

Campos, Michael P.; Hendricks, Mark P.; Beecher, Alexander N.; ...

2017-01-19

Here, we report a tunable library of N,N,N'-trisubstituted selenourea precursors and their reaction with lead oleate at 60–150 °C to form carboxylate-terminated PbSe nanocrystals in quantitative yields. Single exponential conversion kinetics can be tailored over 4 orders of magnitude by adjusting the selenourea structure. The wide range of conversion reactivity allows the extent of nucleation ([nanocrystal] = 4.6–56.7 μM) and the size following complete precursor conversion (d = 1.7–6.6 nm) to be controlled. Narrow size distributions (σ = 0.5–2%) are obtained whose spectral line widths are dominated (73–83%) by the intrinsic single particle spectral broadening, as observed using spectral holemore » burning measurements. Here, the intrinsic broadening decreases with increasing size (fwhm = 320–65 meV, d = 1.6–4.4 nm) that derives from exciton fine structure and exciton–phonon coupling rather than broadening caused by the size distribution.« less

Fine Structure in Quasar Flows Revealed by Lens-Aided Multi-Angle Spectroscopy (LAMAS)

NASA Astrophysics Data System (ADS)

Green, Paul J.

2006-09-01

Spectral differences between lensed quasar image components are common. Since lensing is intrinsically achromatic, these differences are typically explained as the effect of either microlensing, or as light path time delays sampling intrinsic quasar spectral variability. In some cases, neither explanation seems sufficient. Here we advance a novel third hypothesis: some spectral differences are due to small line-of- sight differences through quasar disk wind outflows, taking the widest separation lens SDSSJ1004+4112 as a key example. We show that small changes in sightline may traverse streams with significantly differing columns. The implications are many. Fine structure in these outflows may change the observed spectra on arcsec scales. Though difficult to detect observationally, high ionization, high velocity-width streams may sculpt the optical and X-ray spectra of most quasars. We discuss existing multi-epoch optical/UV spectroscopy and results from X-ray observations both by Chandra and XMM in this context, and sketch further possible tests. The author gratefully acknowledges support through NASA contract NAS8-03060 (CXC).

An analytical X-ray CdTe detector response matrix for incomplete charge collection correction for photon energies up to 300 keV

NASA Astrophysics Data System (ADS)

Kurková, Dana; Judas, Libor

2018-05-01

Gamma and X-ray energy spectra measured with semiconductor detectors suffer from various distortions, one of them being so-called "tailing" caused by an incomplete charge collection. Using the Hecht equation, a response matrix of size 321 × 321 was constructed which was used to correct the effect of incomplete charge collection. The correction matrix was constructed analytically for an arbitrary energy bin and the size of the energy bin thus defines the width of the spectral window. The correction matrix can be applied separately from other possible spectral corrections or it can be incorporated into an already existing response matrix of the detector. The correction was tested and its adjustable parameters were optimized on the line spectra of 57Co measured with a cadmium telluride (CdTe) detector in a spectral range from 0 up to 160 keV. The best results were obtained when the values of the free path of holes were spread over a range from 0.4 to 1.0 cm and weighted by a Gauss function. The model with the optimized parameter values was then used to correct the line spectra of 152Eu in a spectral range from 0 up to 530 keV. An improvement in the energy resolution at full width at half maximum from 2.40 % ± 0.28 % to 0.96 % ± 0.28 % was achieved at 344.27 keV. Spectra of "narrow spectrum series" beams, N120, N150, N200, N250 and N300, generated with tube voltages of 120 kV, 150 kV, 200 kV, 250 kV and 300 kV respectively, and measured with the CdTe detector, were corrected in the spectral range from 0 to 160 keV (N120 and N150) and from 0 to 530 keV (N200, N250, N300). All the measured spectra correspond both qualitatively and quantitatively to the available reference data after the correction. To obtain better correspondence between N150, N200, N250 and N300 spectra and the reference data, lower values of the free paths of holes (range from 0.16 to 0.65 cm) were used for X-ray spectra correction, which suggests energy dependence of the phenomenon.

Spectral and Imaging Observations of a Current Sheet Region in a Small-scale Magnetic Reconnection Event

NASA Astrophysics Data System (ADS)

Xue, Zhike; Yan, Xiaoli; Yang, Liheng; Wang, Jincheng; Feng, Song; Li, Qiaoling; Ji, Kaifan; Zhao, Li

2018-05-01

We report a possible current sheet region associated with a small-scale magnetic reconnection event by using the spectral and imaging observations of the Interface Region Imaging Spectrograph (IRIS) and the magnetograms obtained by the Solar Dynamics Observatory on 2016 August 08. The length and width of the current sheet region are estimated to be from 1.4 ± 0.1 Mm to 3.0 ± 0.3 Mm and from 0.34 ± 0.01 Mm to 0.64 ± 0.09 Mm, respectively. The evolutions of the length of the current sheet region are positively correlated with that of the width. These measurements are among the smallest reported. When the IRIS slit scans the current sheet region, the spectroscopic observations show that the Si IV line is broadened in the current sheet region and the plasma has a blueshifted feature at the middle and a redshifted feature at the ends of the current sheet region. The maximum measured blueshifted and redshifted Doppler velocities are ‑20.8 ± 0.9 and 34.1 ± 0.4 km s‑1, respectively. Additionally, the electron number densities of the plasma in the current sheet region are computed to be around 1011 cm‑3 based on the spectrums of the two O IV lines. The emergence, movement, and cancellation of a small sunspot with negative polarity are observed during the formation and shift of the current sheet region. We suggest that the occurrence and evolution of the magnetic reconnection are driven by the movement of the small sunspot in the photosphere.

BeppoSAX Observations of MKN 110

NASA Technical Reports Server (NTRS)

Nicastro, Fabrizio; Oliversen, Ronald J. (Technical Monitor)

2002-01-01

Mkn 110 is a bright, nearby Seyfert 1 galaxy, which underwent a long optical monitoring campaign, during the past 12 years. Optical observations show that Mkn 110 vary, both in flux and spectral shape. The intensity and width of its Broad Emission Lines (BELs) also vary, from typical Seyfert 1, to typical Narrow Line Seyfert 1 (NLSyl) values, so suggesting that this could be the first supermassive black holes where accretion state related transitions, as frequently observed in stellar-size black holes, have finally been observed. To verify these suggestions we asked to monitor Mkn 110 with BeppoSAX with three 50 ksec observations six months apart. The goal of the proposal was to observe spectral variations in X-ray, already suggested by previous, existing ROSAT (Roentgen Satellite) and ASCA (Advanced Satellite for Cosmology and Astrophysics) observations of the same source. The first of these three SAX (Satellite per Astronomia X) observations was taken on May 2000, and lacks the Low-Energy instrument (0.1-2 keV is the band in which NLSy1 and Sy1 X-ray spectra differ most).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Yu-Qian; Modjaz, Maryam; Bianco, Federica B., E-mail: YL1260@nyu.edu, E-mail: mmodjaz@nyu.edu

Super-luminous supernovae (SLSNe) are tremendously luminous explosions whose power sources and progenitors are highly debated. Broad-lined SNe Ic (SNe Ic-bl) are the only type of SNe that are connected with long-duration gamma-ray bursts (GRBs). Studying the spectral similarity and difference between the populations of hydrogen-poor SLSNe (SLSNe Ic) and of hydrogen-poor stripped-envelope core-collapse SNe, in particular SNe Ic and SNe Ic-bl, can provide crucial observations to test predictions of theories based on various power source models and progenitor models. In this paper, we collected all of the published optical spectra of 32 SLSNe Ic, 21 SNe Ic-bl, as well asmore » 17 SNe Ic, quantified their spectral features, constructed average spectra, and compared them in a systematic way using new tools we have developed. We find that SLSNe Ic and SNe Ic-bl, including those connected with GRBs, have comparable widths for their spectral features and average absorption velocities at all phases. Thus, our findings strengthen the connection between SLSNe Ic and GRBs. In particular, SLSNe Ic have average Fe ii λ 5169 absorption velocities of −15,000 ± 2600 km s{sup −1} at 10 days after peak, which are higher than those of SNe Ic by ∼7000 km s{sup −1} on average. SLSNe Ic also have significantly broader Fe ii λ 5169 lines than SNe Ic. Moreover, we find that such high absorption and width velocities of SLSNe Ic may be hard to explain with the interaction model, and none of the 13 SLSNe Ic with measured absorption velocities spanning over 10 days has a convincing flat velocity evolution, which is inconsistent with the magnetar model in one dimension. Lastly, we compare SN 2011kl, the first SN connected with an ultra-long GRB, with the mean spectrum of SLSNe Ic and of SNe Ic-bl.« less

Toward Spectroscopically Detecting the Global Latitudinal Temperature Variation on the Solar Surface

NASA Astrophysics Data System (ADS)

Takeda, Y.; UeNo, S.

2017-09-01

A very slight rotation-induced latitudinal temperature variation (presumably on the order of several kelvin) on the solar surface is theoretically expected. While recent high-precision solar brightness observations reported its detection, confirmation by an alternative approach using the strengths of spectral lines is desirable, for which reducing the noise due to random fluctuation caused by atmospheric inhomogeneity is critical. Toward this difficult task, we carried out a pilot study of spectroscopically investigating the relative variation of temperature (T) at a number of points in the solar circumference region near to the limb (where latitude dependence should be detectable, if any exists) based on the equivalent widths (W) of 28 selected lines in the 5367 - 5393 Å and 6075 - 6100 Å regions. We paid special attention to i) clarifying which types of lines should be employed and ii) how much precision is attainable in practice. We found that lines with strong T-sensitivity (|log W/log T|) should be used and that very weak lines should be avoided because they inevitably suffer strong relative fluctuations (Δ W/W). Our analysis revealed that a precision of Δ T/T ≈ 0.003 (corresponding to ≈ 15 K) can be achieved at best by a spectral line with comparatively large |log W/log T|, although this can possibly be further improved When a number of lines are used all together. Accordingly, if many such favorable lines could be measured with subpercent precision of Δ W/W and by averaging the resulting Δ T/T from each line, the random noise would eventually be reduced to ≲ 1 K and detection of a very subtle amount of global T-gradient might be possible.

Effects of 946-nm thermal shift and broadening on Nd3+:YAG laser performance

NASA Astrophysics Data System (ADS)

Seyed Ebrahim, Pourmand; Ghasem, Rezaei

2015-12-01

Spectroscopic properties of flashlamp pumped Nd3+:YAG laser are studied as a function of temperature in a range from -30 °C to 60 °C. The spectral width and shift of quasi three-level 946.0-nm inter-Stark emission within the respective intermanifold transitions of 4F3/2 → 4I9/2 are investigated. The 946.0-nm line shifts toward the shorter wavelength and broadens. In addition, the threshold power and slope efficiency of the 946.0-nm laser line are quantified with temperature. The lower the temperature, the lower the threshold power is and the higher the slope efficiency of the 946.0-nm laser line is, thus the higher the laser output is. This phenomenon is attributed to the ion-phonon interaction and the thermal population in the ground state. Project supported by Estahban Branch, Islamic Azad University.

Long-slit optical spectroscopy of powerful far-infrared galaxies - The nature of the nuclear energy source

NASA Technical Reports Server (NTRS)

Armus, Lee; Heckman, Timothy M.; Miley, George K.

1989-01-01

Optical spectroscopic data are presented for a sample of 47 powerful far-IR galaxies chosen for IR spectral shape, and for six other IR-bright galaxies. The stellar absorption lines expected from a population of old stars are generally very weak in the nuclei of the galaxies. Very weak Mg I absorption is found in regions well off the nucleus, implying that the visible spectrum is dominated by young stars and not by an AGN. At least one, and probably five, of the galaxies have detectable WR emission features, providing additional evidence for a young stellar population. About 20 percent of the galaxies have strong Balmer absorption lines, indicating the presence of a substantial intermediate-age stellar population. The equivalent width of the H-alpha emission line can be modeled as arising from a mixture of a large young population and an intermediate-age population of stars.

Photophysics of GaN single-photon emitters in the visible spectral range

NASA Astrophysics Data System (ADS)

Berhane, Amanuel M.; Jeong, Kwang-Yong; Bradac, Carlo; Walsh, Michael; Englund, Dirk; Toth, Milos; Aharonovich, Igor

2018-04-01

In this work, we present a detailed photophysical analysis of recently discovered, optically stable single-photon emitters (SPEs) in gallium nitride (GaN). Temperature-resolved photoluminescence measurements reveal that the emission lines at 4 K are three orders of magnitude broader than the transform-limited width expected from excited-state lifetime measurements. The broadening is ascribed to ultrafast spectral diffusion. The photophysical study on several emitters at room temperature (RT) reveals an average brightness of (427 ±215 )kCounts /s . Finally, polarization measurements from 14 emitters are used to determine visibility as well as dipole orientation of defect systems within the GaN crystal. Our results underpin some of the fundamental properties of SPEs in GaN both at cryogenic and RT, and define the benchmark for future work in GaN-based single-photon technologies.

Study of the amplified spontaneous emission spectral width and gain coefficient for a KrF laser in unsaturated and saturated conditions

NASA Astrophysics Data System (ADS)

Hariri, A.; Sarikhani, S.

2014-01-01

On the basis of a model of a geometrically dependent gain coefficient, the amplified spontaneous emission (ASE) spectral width was calculated analytically for the nearly resonant transition of ν ˜ ν0, and also numerically for a wide range of transition frequencies. For this purpose, the intensity rate equation was used under unsaturated and saturated conditions. For verifying the proposed model, reported measurements of the ASE energy versus the excitation length for a KrF laser were used. For the excitation length of l = 84 cm corresponding to single-path propagation, the ASE spectral width for the homogeneously broadened transition was calculated to be 6.28 Å, to be compared with the measured 4.1 Å spectral width reported for a KrF oscillator utilizing a two-mirror resonator. With the gain parameters obtained from the ASE energy measurements, the unsaturated and saturated gain coefficients for l = 84 cm were calculated to be 0.042 cm-1 and 0.014 cm-1, respectively. These values of the gain coefficient are comparable to but slightly lower than the measured gain coefficient for laser systems of 80-100 cm excitation lengths reported from different laboratories.

Radio stars observed in the LAMOST spectral survey

NASA Astrophysics Data System (ADS)

Zhang, Li-Yun; Yue, Qiang; Lu, Hong-Peng; Han, Xian-Ming L.; Zhang, Yong; Shi, Jian-Rong; Wang, Yue-Fei; Hou, Yong-Hui; Zi-Huang, Cao

2017-09-01

Radio stars have attracted astronomers’ attention for several decades. To better understand the physics behind stellar radio emissions, it is important to study their optical behaviors. The LAMOST survey provides a large database for researching stellar spectroscopic properties of radio stars. In this work, we concentrate on their spectroscopic properties and infer physical properties from their spectra, such as stellar activity and variability. We mined big data from the LAMOST spectral survey Data Release 2 (DR2), published on 2016 June 30, by cross-matching them with radio stars from FIRST and other surveys. We obtained 783 good stellar spectra with high signal to noise ratio for 659 stars. The criteria for selection were positional coincidence within 1.5‧‧ and LAMOST objects classified as stars. We calculated the equivalent widths (EWs) of the Ca ii H&K, Hδ, Hγ, Hβ, Hα and Ca ii IRT lines by integrating the line profiles. Using the EWs of the Hα line, we detected 147 active stellar spectra of 89 objects having emissions above the Hα continuum. There were also 36 objects with repeated spectra, 28 of which showed chromospheric activity variability. Furthermore, we found 14 radio stars emitting noticeably in the Ca ii IRT lines. The low value of the EW8542/EW8498 ratio for these 14 radio stars possibly alludes to chromospheric plage regions.

Self- and Air-Broadened Line Shape Parameters of (12)CH(4) : 4500-4620 cm(-1)

NASA Astrophysics Data System (ADS)

Devi, V. Malathy; Benner, D. Chris; Sung, K.; Brown, L. R.; Crawford, T. J.; Smith, M. A. H.; Mantz, A. W.; Predoi-Cross, A.

2014-06-01

Accurate knowledge of spectral line shape parameters is important for infrared transmission and radiance calculations in the terrestrial atmosphere. We report the self and air-broadened Lorentz widths, shifts and line mixing coefficients along with their temperature dependencies for methane absorption lines in the 2.2 µm spectral region. For this, we obtained a series of high-resolution, high S/N spectra of 99.99% 12C-enriched samples of pure methane and its dilute mixtures in dry air at cold temperatures down to 150 K using the Bruker IFS 125HR Fourier transform spectrometer at JPL. The coolable absorption cell had an optical path of 20.38 cm and was specially built to reside inside the sample compartment of the Bruker FTS1. The 13 spectra used in the analysis consisted of seven pure 12CH4 spectra at pressures from 4.5 to 169 Torr and six air-broadened spectra with total sample pressures of 113-300 Torr and methane volume mixing ratios between 4 and 9.7%. These 13 spectra were fit simultaneously using the multispectrum least-squares fitting technique2. The results will be compared to existing values reported in the literature3. as part of the GNU EPrints system , and is freely redistributable under the GPL .

On-line, continuous monitoring in solar cell and fuel cell manufacturing using spectral reflectance imaging

DOEpatents

Sopori, Bhushan; Rupnowski, Przemyslaw; Ulsh, Michael

2016-01-12

A monitoring system 100 comprising a material transport system 104 providing for the transportation of a substantially planar material 102, 107 through the monitoring zone 103 of the monitoring system 100. The system 100 also includes a line camera 106 positioned to obtain multiple line images across a width of the material 102, 107 as it is transported through the monitoring zone 103. The system 100 further includes an illumination source 108 providing for the illumination of the material 102, 107 transported through the monitoring zone 103 such that light reflected in a direction normal to the substantially planar surface of the material 102, 107 is detected by the line camera 106. A data processing system 110 is also provided in digital communication with the line camera 106. The data processing system 110 is configured to receive data output from the line camera 106 and further configured to calculate and provide substantially contemporaneous information relating to a quality parameter of the material 102, 107. Also disclosed are methods of monitoring a quality parameter of a material.

Observation and modelling of the Fe XXI line profile observed by IRIS during the impulsive phase of flares

NASA Astrophysics Data System (ADS)

Polito, V.; Testa, P.; De Pontieu, B.; Allred, J. C.

2017-12-01

The observation of the high temperature (above 10 MK) Fe XXI 1354.1 A line with the Interface Region Imaging Spectrograph (IRIS) has provided significant insights into the chromospheric evaporation process in flares. In particular, the line is often observed to be completely blueshifted, in contrast to previous observations at lower spatial and spectral resolution, and in agreement with predictions from theoretical models. Interestingly, the line is also observed to be mostly symmetric and with a large excess above the thermal width. One popular interpretation for the excess broadening is given by assuming a superposition of flows from different loop strands. In this work, we perform a statistical analysis of Fe XXI line profiles observed by IRIS during the impulsive phase of flares and compare our results with hydrodynamic simulations of multi-thread flare loops performed with the 1D RADYN code. Our results indicate that the multi-thread models cannot easily reproduce the symmetry of the line and that some other physical process might need to be invoked in order to explain the observed profiles.

The Ionized Gas and Nuclear Environment in NGC 3783. IV; Variability and Modeling of the 900 ks CHANDRA Spectrum

NASA Technical Reports Server (NTRS)

Netzer, Hagai; Kaspi, Shai; Behar, Ehud; Brandt, W. N.; Chelouche, Doron; George, Ian M.; Crenshaw, D. Michael; Gabel, Jack R.; Hamann, Frederick W.; George, Steven B.

2003-01-01

We present a detailed analysis of the 900 ks spectrum of NGC3783 obtained by Chandra in 2000-2001 (Kaspi et al. 2002). We split the data in various ways to look for time dependent and luminosity dependent spectral variations. This analysis, the measured equivalent widths of a large number of X-ray lines, and our photoionization calculations, lead us to the following conclusions: 1) NGC 3783 fluctuated in luminosity, by a factor N 1.5, during individual 170 ks observations. The fluctuations were not associated with significant spectral variations. 2) On a longer time scale, of 20-120 days, we discovered two very different spectral shapes that are noted the high state and the low state spectra. The observed changes between the two can be described as the appearance and disappearance of a soft continuum component. The spectral variations are not related, in a simple way, to the brightening or the fading of the short wavelength continuum, as observed in other objects. NGC3783 seems to be the first AGN to show this unusual behavior. 3) The appearance of the soft continuum component is consistent with beeing the only spectral variation and there is no need to invoke changes in the absorber s opacity. In particular, all absorption lines with reliable measurements show the same equivalent width, within the observational uncertainties, during high and low states. 4) Photoionization model calculations show that a combination of three ionization components, each split into two kinematic components, explain very well the intensity of almost all absorption lines and the bound-free absorption. The components span a large range of ionization and a total column of about 3 x 10(exp 22) per square centimeter Moreover, all components are thermally stable and are situated on the vertical branch of the stability curve.. This means that they are in pressure equilibrium and perhaps occupy the same volume of space. This is the first detection of such a multi-component equilibrium gas in AGN. 5) The only real discrepancy between the model and the observations is the wavelength of the iron M-shell UTA feature. This is most likely due to an underestimation of the dielectronic recombination O VI and discuss its possible origin. 6) The lower limit on the distance of the absorbing gas in NGC3783 is between 0.2 and 3.2 pc, depending of the specific ionization component. The constant pressure assumption imposes an upper limit of about 25 pc on the distance of the least ionized gas from the central sourec.

Measuring the ISM Content of Optically Luminous Type 2 Quasars

NASA Astrophysics Data System (ADS)

Marshall, Jameeka; Petric, Andreea; Flagey, Nicolas; Lacy, Mark; Omont, Alain

2018-01-01

There is a connection between black holes (BH) and the surrounding bulge stars. Measuring the cold interstellar medium (ISM) content of host galaxies is essential to understand the coevolution of galaxies and BHs. The ISM measurement is important because gas constitutes the raw material from which BHs grow and stars form. Quasars are extremely luminous active galaxies fueled by accreting supermassive black holes. Type 2 quasars have narrow spectral lines whereas type 1 quasars have broad spectral lines. Not only can the ISM measurements provide empirical data to help further clarify quasar models but it is also crucial in distinguishing the physical differences between type 1 and type 2 quasars. Observations of twenty type 2 quasars were made using IRAM, a single dish 30 meter radio telescope, to measure 12CO (1-0) and 12CO (2-1) emission. We used line widths to constrain the dynamical mass and gravitational potential of the host galaxy. Star formation rate (SFR) measured in the infrared (IR) and SFR derived from optical spectra were used to estimate star formation efficiency and gas depletion time scale (M H2/star formation rate). Preliminary analysis suggests that star formation efficiency in type 2 quasars is slightly higher than in type 1 quasars.

A young solar twin in the Rosette cluster NGC 2244 line of sight

NASA Astrophysics Data System (ADS)

Huber, Jeremy M.; Kielkopf, John F.; Mengel, Matthew; Carter, Bradley D.; Ferland, Gary J.; Clark, Frank O.

2018-05-01

Based on prior precision photometry and cluster age analysis, the bright star GSC 00154-01819 is a possible young pre-main sequence member of the Rosette cluster, NGC 2244. As part of a comprehensive study of the large-scale structure of the Rosette and its excitation by the cluster stars, we noted this star as a potential backlight for a probe of the interstellar medium and extinction along the sight line towards a distinctive nebular feature projected on to the cluster centre. New high-resolution spectra of the star were taken with the University College London Echelle Spectrograph of the AAT. They reveal that rather than being a reddened spectral type B or A star within the Mon OB2 association, it is a nearby, largely unreddened, solar twin of spectral type G2V less than 180 Myr old. It is about 219 pc from the Sun with a barycentric radial velocity of +14.35 ± 1.99 km s-1. The spectrum of the Rosette behind it and along this line of sight shows a barycentric radial velocity of +26.0 ± 2.4 km s-1 in H α, and a full width at half-maximum velocity dispersion of 61.94 ± 1.38 km s-1.

Cataclysmic variables based on the stellar spectral survey LAMOST DR3

NASA Astrophysics Data System (ADS)

Han, Xianming L.; Zhang, Li-Yun; Shi, Jian-Rong; Pi, Qing-Feng; Lu, Hong-Peng; Zhao, Li-Bo; Terheide, Rachel K.; Jiang, Lin-Yang

2018-06-01

Big data in the form of stellar spectra from the spectroscopic survey associated with the Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST) are important for studying properties of cataclysmic variables (CVs). By cross matching the catalogs of CVs compiled with LAMOST DR3, acquired from October 2011 to July 2015, we obtained the first spectroscopic catalog for CVs observed by LAMOST with high signal to noise ratio, above 8. By integrating line profiles, their equivalent widths (EWs) of the Hα, Hβ, Hγ and Hδ, as well as He I 5876 and 6678 Å lines, were calculated. There were 74 stellar spectra from 48 known CVs and three spectra from three new CV candidates. At the same time, we also collected their previously published EWs. Thirty-three objects had repeated spectra and 30 stars showed spectral variability in the Hα line. Moreover, we carried out photometric follow-up studies for five CVs (UU Aqr, TT Tri, PX And, BP Lyn and RW Tri). We obtained nine new light curves and revised their linear ephemerides. For RW Tri, there is a possible oscillation with an amplitude of 0.0031(2) days and a period of 47.6 ± 0.4 years, which might be caused by a third body (brown dwarf) or magnetic activity cycle.

An investigation of the rapid spectral variability of the AP stars 53 Cam, 41 Tau, and Beta CrB on the basis of the K CA II and H-delta lines

NASA Astrophysics Data System (ADS)

Kuvshinov, V. M.; Plachinda, S. I.

The flux is shown to vary with the phase of the period of axial rotation. For 53 Cam and Beta CrB, this variability is smooth and is well correlated with the intensity of the mean surface magnetic field. It is pointed out that in the case of 53 Cam, an analogous dependence between the equivalent width of the K Ca II line and the phase of the period of rotation was obtained by Faraggiana (1973). It is considered significant that the correlations between the flux in the K line and the intensity of the mean surface magnetic field for 53 Cam and Beta CrB have the same sign. With 41 Tau, as with the effective magnetic field, no smooth relationship is found between the fluxes in the K Ca II and H-delta lines and the phase of the period of rotation.

Spectrum syntheses of high-resolution integrated light spectra of Galactic globular clusters

NASA Astrophysics Data System (ADS)

Sakari, Charli M.; Shetrone, Matthew; Venn, Kim; McWilliam, Andrew; Dotter, Aaron

2013-09-01

Spectrum syntheses for three elements (Mg, Na and Eu) in high-resolution integrated light spectra of the Galactic globular clusters 47 Tuc, M3, M13, NGC 7006 and M15 are presented, along with calibration syntheses of the solar and Arcturus spectra. Iron abundances in the target clusters are also derived from integrated light equivalent width analyses. Line profiles in the spectra of these five globular clusters are well fitted after careful consideration of the atomic and molecular spectral features, providing levels of precision that are better than equivalent width analyses of the same integrated light spectra, and that are comparable to the precision in individual stellar analyses. The integrated light abundances from the 5528 and 5711 Å Mg I lines, the 6154 and 6160 Å Na I lines, and the 6645 Å Eu II line fall within the observed ranges from individual stars; however, these integrated light abundances do not always agree with the average literature abundances. Tests with the second parameter clusters M3, M13 and NGC 7006 show that assuming an incorrect horizontal branch morphology is likely to have only a small ( ≲ 0.06 dex) effect on these Mg, Na and Eu abundances. These tests therefore show that integrated light spectrum syntheses can be applied to unresolved globular clusters over a wide range of metallicities and horizontal branch morphologies. Such high precision in integrated light spectrum syntheses is valuable for interpreting the chemical abundances of globular cluster systems around other galaxies.

Measuring the x-ray resolving power of bent potassium acid phthalate diffraction crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haugh, M. J., E-mail: haughmj@nv.doe.gov; Jacoby, K. D.; Wu, M.

2014-11-15

This report presents the results from measuring the X-ray resolving power of a curved potassium acid phthalate (KAP(001)) spectrometer crystal using two independent methods. It is part of a continuing effort to measure the fundamental diffraction properties of bent crystals that are used to study various characteristics of high temperature plasmas. Bent crystals like KAP(001) do not usually have the same diffraction properties as corresponding flat crystals. Models that do exist to calculate the effect of bending the crystal on the diffraction properties have simplifying assumptions and their accuracy limits have not been adequately determined. The type of crystals thatmore » we measured is being used in a spectrometer on the Z machine at Sandia National Laboratories in Albuquerque, New Mexico. The first technique for measuring the crystal resolving power measures the X-ray spectral line width of the characteristic lines from several metal anodes. The second method uses a diode X-ray source and a double crystal diffractometer arrangement to measure the reflectivity curve of the KAP(001) crystal. The width of that curve is inversely proportional to the crystal resolving power. The measurement results are analyzed and discussed.« less

Measuring the X-ray Resolving Power of Bent Potassium Acid Phthalate Diffraction Crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haugh, M. J.; Wu, M.; Jacoby, K. D.

2014-11-01

This report presents the results from measuring the X-ray resolving power of a curved potassium acid phthalate (KAP(001)) spectrometer crystal using two independent methods. It is part of a continuing effort to measure the fundamental diffraction properties of bent crystals that are used to study various characteristics of high temperature plasmas. Bent crystals like KAP(001) do not usually have the same diffraction properties as corresponding flat crystals. Models that do exist to calculate the effect of bending the crystal on the diffraction properties have simplifying assumptions and their accuracy limits have not been adequately determined. The type of crystals thatmore » we measured is being used in a spectrometer on the Z machine at Sandia National Laboratories (SNL) in Albuquerque, NM. The first technique for measuring the crystal resolving power measures the X-ray spectral line width of the characteristic lines from several metal anodes. The second method uses a diode X-ray source and a dual goniometer arrangement to measure the reflectivity curve of the KAP(001) crystal. The width of that curve is inversely proportional to the crystal resolving power. The measurement results are analyzed and discussed.« less

Measuring the x-ray resolving power of bent potassium acid phthalate diffraction crystalsa)

NASA Astrophysics Data System (ADS)

Haugh, M. J.; Wu, M.; Jacoby, K. D.; Loisel, G. P.

2014-11-01

This report presents the results from measuring the X-ray resolving power of a curved potassium acid phthalate (KAP(001)) spectrometer crystal using two independent methods. It is part of a continuing effort to measure the fundamental diffraction properties of bent crystals that are used to study various characteristics of high temperature plasmas. Bent crystals like KAP(001) do not usually have the same diffraction properties as corresponding flat crystals. Models that do exist to calculate the effect of bending the crystal on the diffraction properties have simplifying assumptions and their accuracy limits have not been adequately determined. The type of crystals that we measured is being used in a spectrometer on the Z machine at Sandia National Laboratories in Albuquerque, New Mexico. The first technique for measuring the crystal resolving power measures the X-ray spectral line width of the characteristic lines from several metal anodes. The second method uses a diode X-ray source and a double crystal diffractometer arrangement to measure the reflectivity curve of the KAP(001) crystal. The width of that curve is inversely proportional to the crystal resolving power. The measurement results are analyzed and discussed.

VizieR Online Data Catalog: Halpha measurements in Abell 2465 (Wegner+, 2015)

NASA Astrophysics Data System (ADS)

Wegner, G. A.; Chu, D. S.; Hwang, H. S.

2015-07-01

The wavelength of the Hα line at the redshift of Abell 2465 is near 817nm in a clear spectral region between the many telluric emission lines. A custom narrow-band filter for observing Hα was obtained from the Andover Corp. It has a peak transmission at 817.7nm (m817) and a full width at half-maximum (FWHM) of 8.77nm. The wide filter was a Gunn i (ig) filter with nearly the same central wavelength of 820nm and a FWHM of 185nm, and was manufactured by Custom Scientific. Hα observations of Abell 2465 were obtained 2012 September 19-23 using the 2.4m Hiltner telescope at the MDM Observatory on Kitt Peak. The 'Nellie' CCD was used. (1 data file).

Kinetics in Gas Mixtures for Problem of Plasma Assisted Combustion

DTIC Science & Technology

2010-05-01

to Brewster angle , the width of the generation line is approximately equal to 3 GHz (0.1 cm−1, or 0.7·10−3 nm) in the visible range. The frequency... lenses and optical windows of the lamps. Streak–images, spectral profiles obtained from the images and reference spectra are given in Fig. 6.3—6.4...797.18− 0.4675N, (6.3) where N is a pixels number. In the experiments, the system of two lenses L1 and L2 focused emission from the discharge cell on

VizieR Online Data Catalog: Stark broadening of XeVIII spectral lines (Dimitrijevic+, 2015)

NASA Astrophysics Data System (ADS)

Dimitrijevic, M. S.; Simic, Z.; Kovacevic, A.; Valjarevic, A.; Sahal-Brechot, S.

2018-01-01

By means of the code based on semiclassical perturbation theory we have calculated widths and shifts for 60 transitions of Xe VIII. The needed energy levels have been taken from Saloman (2004JPCRD..33..765S). Oscillator strengths have been calculated by using the method of Bates & Damgaard (1949RSPTA.242..101B) and the tables of Oertel & Shomo (1968ApJS...16..175O). For higher levels, oscillator strengths have been calculated according to Van Regemorter, Hoang Binh & Prud'homme (1979, J. Phys. B, 12, 1073). (1 data file).

Electrical flicker-noise generated by filling and emptying of impurity states in injectors of quantum-cascade lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamanishi, Masamichi, E-mail: masamiya@crl.hpk.co.jp; Hirohata, Tooru; Hayashi, Syohei

2014-11-14

Free running line-widths (>100 kHz), much broader than intrinsic line-widths ∼100 Hz, of existing quantum-cascade lasers are governed by strong flicker frequency-noise originating from electrical flicker noise. Understanding of microscopic origins of the electrical flicker noises in quantum-cascade lasers is crucially important for the reduction of strength of flicker frequency-noise without assistances of any type of feedback schemes. In this article, an ad hoc model that is based on fluctuating charge-dipoles induced by electron trappings and de-trappings at indispensable impurity states in injector super-lattices of a quantum-cascade laser is proposed, developing theoretical framework based on the model. The validity of the presentmore » model is evaluated by comparing theoretical voltage-noise power spectral densities based on the model with experimental ones obtained by using mid-infrared quantum-cascade lasers with designed impurity-positioning. The obtained experimental results on flicker noises, in comparison with the theoretical ones, shed light on physical mechanisms, such as the inherent one due to impurity states in their injectors and extrinsic ones due to surface states on the ridge-walls and due to residual deep traps, for electrical flicker-noise generation in existing mid-infrared quantum-cascade lasers. It is shown theoretically that quasi-delta doping of impurities in their injectors leads to strong suppression of electrical flicker noise by minimization of the dipole length at a certain temperature, for instance ∼300 K and, in turn, is expected to result in substantial narrowing of the free running line-width down below 10 kHz.« less

WINGS-SPE. III. Equivalent width measurements, spectral properties, and evolution of local cluster galaxies

NASA Astrophysics Data System (ADS)

Fritz, J.; Poggianti, B. M.; Cava, A.; Moretti, A.; Varela, J.; Bettoni, D.; Couch, W. J.; D'Onofrio D'Onofrio, M.; Dressler, A.; Fasano, G.; Kjærgaard, P.; Marziani, P.; Moles, M.; Omizzolo, A.

2014-06-01

Context. Cluster galaxies are the ideal sites to look at when studying the influence of the environment on the various aspects of the evolution of galaxies, such as the changes in their stellar content and morphological transformations. In the framework of wings, the WIde-field Nearby Galaxy-cluster Survey, we have obtained optical spectra for ~6000 galaxies selected in fields centred on 48 local (0.04 < z < 0.07) X-ray selected clusters to tackle these issues. Aims: By classifying the spectra based on given spectral lines, we investigate the frequency of the various spectral types as a function of both the clusters' properties and the galaxies' characteristics. In this way, using the same classification criteria adopted for studies at higher redshift, we can consistently compare the properties of the local cluster population to those of their more distant counterparts. Methods: We describe a method that we have developed to automatically measure the equivalent width of spectral lines in a robust way, even in spectra with a non optimal signal-to-noise ratio. This way, we can derive a spectral classification reflecting the stellar content, based on the presence and strength of the [Oii] and Hδ lines. Results: After a quality check, we are able to measure 4381 of the ~6000 originally observed spectra in the fields of 48 clusters, of which 2744 are spectroscopically confirmed cluster members. The spectral classification is then analysed as a function of galaxies' luminosity, stellar mass, morphology, local density, and host cluster's global properties and compared to higher redshift samples (MORPHS and EDisCS). The vast majority of galaxies in the local clusters population are passive objects, being also the most luminous and massive. At a magnitude limit of MV < -18, galaxies in a post-starburst phase represent only ~11% of the cluster population, and this fraction is reduced to ~5% at MV < -19.5, which compares to the 18% at the same magnitude limit for high-z clusters. "Normal" star-forming galaxies (e(c)) are proportionally more common in local clusters. Conclusions: The relative occurrence of post-starbursts suggests a very similar quenching efficiency in clusters at redshifts in the 0 to ~1 range. Furthermore, more important than the global environment, the local density seems to be the main driver of galaxy evolution in local clusters at least with respect to their stellar populations content. Based on observations taken at the Anglo Australian Telescope (3.9 m- AAT) and at the William Herschel Telescope (4.2 m-WHT).Full Table A.1 is available in electronic form at both the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/566/A32 and by querying the wings database at http://web.oapd.inaf.it/wings/new/index.htmlAppendices are available in electronic form at http://www.aanda.org

XMM-Newton observations of the supernova remnant IC 443. II. Evidence of stellar ejecta in the inner regions

NASA Astrophysics Data System (ADS)

Troja, E.; Bocchino, F.; Miceli, M.; Reale, F.

2008-07-01

Aims: We investigate the spatial distribution of the physical and chemical properties of the hot X-ray emitting plasma of the supernova remnant IC 443, to derive important constraints on its ionization stage, on the progenitor supernova explosion, on the age of the remnant, and its physical association with a close pulsar wind nebula. Methods: We present XMM-Newton images of IC 443, a median photon energy map, silicon and sulfur equivalent width maps, and a spatially resolved spectral analysis of a set of homogeneous regions. Results: The hard X-ray thermal emission (1.4-5.0 keV) of IC 443 displays a centrally-peaked morphology, its brightness peaks being associated with hot (kT > 1 keV) X-ray emitting plasma. A ring-shaped structure, characterized by high values of equivalent widths and median photon energy, encloses the PWN. Its hard X-ray emission is spectrally characterized by a collisional ionization equilibrium model, and strong emission lines of Mg, Si, and S, requiring oversolar metal abundances. Dynamically, the location of the ejecta ring suggests an SNR age of ~4000 yr. The presence of overionized plasma in the inner regions of IC 443, addressed in previous works, is much less evident in our observations.

Numerical investigation of frequency spectrum in the Hasegawa-Wakatani model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Juhyung; Terry, P. W.

2013-10-15

The wavenumber-frequency spectrum of the two-dimensional Hasegawa-Wakatani model is investigated in the hydrodynamic, intermediate, and adiabatic regimes. A nonlinear frequency and a line width related to energy transfer properties provide a measure of the average frequency and spectral broadening, respectively. In the adiabatic regime, narrow spectra, typical of wave turbulence, are observed with a nonlinear frequency shift in the electron drift direction. In the hydrodynamic regime, broad spectra with almost zero nonlinear frequencies are observed. Nonlinear frequency shifts are shown to be related to nonlinear energy transfer by vorticity advection through the high frequency region of the spectrum. In themore » intermediate regime, the nonlinear frequency shift for density fluctuations is observed to be weaker than that of electrostatic potential fluctuations. The weaker frequency shift of the density fluctuations is due to nonlinear density advection, which favors energy transfer in the low frequency range. Both the nonlinear frequency and the spectral width increase with poloidal wavenumber k{sub y}. In addition, in the adiabatic regime where the nonlinear interactions manifest themselves in the nonlinear frequency shift, the cross-phase between the density and potential fluctuations is observed to match a linear relation, but only if the linear response of the linearly stable eigenmode branch is included. Implications of these numerical observations are discussed.« less

A solar tornado observed by EIS. Plasma diagnostics

NASA Astrophysics Data System (ADS)

Levens, P. J.; Labrosse, N.; Fletcher, L.; Schmieder, B.

2015-10-01

Context. The term "solar tornadoes" has been used to describe apparently rotating magnetic structures above the solar limb, as seen in high resolution images and movies from the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory (SDO). These often form part of the larger magnetic structure of a prominence, however the links between them remain unclear. Here we present plasma diagnostics on a tornado-like structure and its surroundings, seen above the limb by the Extreme-ultraviolet Imaging Spectrometer (EIS) aboard the Hinode satellite. Aims: We aim to extend our view of the velocity patterns seen in tornado-like structures with EIS to a wider range of temperatures and to use density diagnostics, non-thermal line widths, and differential emission measures to provide insight into the physical characteristics of the plasma. Methods: Using Gaussian fitting to fit and de-blend the spectral lines seen by EIS, we calculated line-of-sight velocities and non-thermal line widths. Along with information from the CHIANTI database, we used line intensity ratios to calculate electron densities at each pixel. Using a regularised inversion code we also calculated the differential emission measure (DEM) at different locations in the prominence. Results: The split Doppler-shift pattern is found to be visible down to a temperature of around log T = 6.0. At temperatures lower than this, the pattern is unclear in this data set. We obtain an electron density of log ne = 8.5 when looking towards the centre of the tornado structure at a plasma temperature of log T = 6.2, as compared to the surroundings of the tornado structure where we find log ne to be nearer 9. Non-thermal line widths show broader profiles at the tornado location when compared to the surrounding corona. We discuss the differential emission measure in both the tornado and the prominence body, which suggests that there is more contribution in the tornado at temperatures below log T = 6.0 than in the prominence. A movie is available in electronic form at http://www.aanda.org

Multimodal imaging of central retinal disease progression in a 2 year mean follow up of Retinitis Pigmentosa

PubMed Central

Sujirakul, Tharikarn; Lin, Michael K.; Duong, Jimmy; Wei, Ying; Lopez-Pintado, Sara; Tsang, Stephen H.

2015-01-01

Purpose To determine the rate of progression and optimal follow up time in patients with advanced stage retinitis pigmentosa (RP) comparing the use of fundus autofluorescence imaging and spectral domain optical coherence tomography. Design Retrospective analysis of progression rate. Methods Longitudinal imaging follow up in 71 patients with retinitis pigmentosa was studied using the main outcome measurements of hyperautofluoresent ring horizontal diameter and vertical diameter along with ellipsoid zone line width from spectral domain optical coherence tomography. Test-retest reliability and the rate of progression were calculated. The interaction between the progression rates was tested for sex, age, mode of inheritance, and baseline measurement size. Symmetry of left and right eye progression rate was also tested. Results Significant progression was observed in >75% of patients during the 2 year mean follow up. The mean annual progression rates of ellipsoid zone line, and hyperautofluorescent ring horizontal diameter and vertical diameter were 0.45° (4.9%), 0.51° (4.1%), and 0.42° (4.0%), respectively. The e llipsoid zone line width, and hyperautofluorescent ring horizontal diameter and vertical diameter had low test-retest variabilities of 8.9%, 9.5% and 9.6%, respectively. This study is the first to demonstrate asymmetrical structural progression rate between right and left eye, which was found in 19% of patients. The rate of progression was significantly slower as the disease approached the fovea, supporting the theory that RP progresses in an exponential fashion. No significant interaction between progression rate and patient age, sex, or mode of inheritance was observed. Conclusions Fundus autofluorescence and optical coherence tomography detect progression in patients with RP reliably and with strong correlation. These parameters may be useful alongside functional assessments as the outcome measurements for future therapeutic trials. Follow-up at 1 year intervals should be adequate to efficiently detect progression. PMID:26164827

Uncertainties Associated with Theoretically Calculated N2-Broadened Half-Widths of H2O Lines

NASA Technical Reports Server (NTRS)

Ma, Q.; Tipping, R. H.; Gamache, R. R.

2010-01-01

With different choices of the cut-offs used in theoretical calculations, we have carried out extensive numerical calculations of the N2-broadend Lorentzian half-widths of the H2O lines using the modified Robert-Bonamy formalism. Based on these results, we are able to thoroughly check for convergence. We find that, with the low-order cut-offs commonly used in the literature, one is able to obtain converged values only for lines with large half-widths. Conversely, for lines with small half-widths, much higher cut-offs are necessary to guarantee convergence. We also analyse the uncertainties associated with calculated half-widths, and these are correlated as above. In general, the smaller the half-widths, the poorer the convergence and the larger the uncertainty associated with them. For convenience, one can divide all H2O lines into three categories, large, intermediate, and small, according to their half-width values. One can use this division to judge whether the calculated half-widths are converged or not, based on the cut-offs used, and also to estimate how large their uncertainties are. We conclude that with the current Robert- Bonamy formalism, for lines in category lone can achieve the accuracy requirement set by HITRAN, whereas for lines in category 3, it 'is impossible to meet this goal.

Análisis de la región de alta temperatura en las estrellas Be y estudio de sus propiedades y geometría

NASA Astrophysics Data System (ADS)

Torres, A. F.; Ringuelet, A. E.

The aim of this study is to analyse the Hot Temperature Region (HTR) that surrounds the photospheres of Be stars. Consequently, we have chosen 54 Be stars of spectral types B0, B1, B2, B3, B8 and B9; the sample is representative of a considerable range of temperature. We have analysed different lines that originate in the HTR from archival IUE spectra reprocessed by the INES: He II λ1640, Si IV λλ1394, 1403 and Al III λλ1855, 1863. From the measured values, we derive several relations that provide information on the geometry and thermodynamical properties of the HTR. Our major findings can be summarised as follows: 1) The equivalent widths of the selected lines in the spectrum of the program stars persist with similar values through all v sin(i) inclinations. 2) The equivalent widths of the Si IV lines are well correlated with the kinetic energy expansion of the wind. This suggests that the dissipation of mechanical energy in the HTR is an important source of heating. 3) The He II lines formation region, which is located at the dense base of the wind, shows full spherical symmetry. 4) The formation region of Si IV lines is located in a low-density well-developed wind and it extends over very high latitudes (˜75o). 5) The Al III lines are formed in an elongated region which is the beginning of the cool envelope. The analysis followed in this work has been completely independent from any theoretical model. Consequently, these results will be useful for deciding whether the circunstellar envelope of Be stars has an ellipsoidal geometry or a disklike shape.

A mean-based filter to remove power line harmonic noise from seismic reflection data

NASA Astrophysics Data System (ADS)

Karslı, Hakan; Dondurur, Derman

2018-06-01

Power line harmonic noise generated by power lines during the seismic data acquisition in land and marine seismic surveys generally appears as a single frequency with 50/60 Hz (or multiples of these frequencies) and contaminates seismic data leading to complicate the identification of fine details in the data. Commonly applied method during seismic data processing to remove the harmonic noise is classical notch filter (or very narrow band-stop filter), however, it also attenuates all recorded data around the notch frequencies and results in a complete loss of available information which corresponds to fine details in the seismic data. In this study, we introduce an application of the algorithm of iterative trimmed and truncated mean filter method (ITTM) to remove the harmonic noise from seismic data, and here, we name the method as local ITTM (LITTM) since we applied it to the seismic data locally in spectral domain. In this method, an optimal value is iteratively searched depending on a threshold value by trimming and truncating process for the spectral amplitude samples within the specified spectral window. Therefore, the LITTM filter converges to the median, but, there is no need to sort the data as in the case of conventional median filters. On the other hand, the LITTM filtering process doesn't require any reference signal or a precise estimate of the fundamental frequency of the harmonic noise, and only approximate frequency band of the noise within the amplitude spectra is considered. The only required parameter of the method is the width of this frequency band in the spectral domain. The LITTM filter is first applied to synthetic data and then we analyze a real marine dataset to compare the quality of the output after removing the power line noise by classical notch, median and proposed LITTM filters. We observe that the power line harmonic noise is completely filtered out by LITTM filter, and unlike the conventional notch filter, without any damage on the available frequencies around the notch frequency band. It also provides a more balanced amplitude spectrum since it does not produce amplitude notches in the spectrum.

VizieR Online Data Catalog: What is the Milky Way outer halo made of? (Battaglia+, 2017)

NASA Astrophysics Data System (ADS)

Battaglia, G.; North, P. L.; Jablonka, P.; Shetrone, M.; Minniti, D.; Diaz, M.; Starkenburg, E.; Savoy, M.

2017-10-01

High resolution spectra have been taken of 28 red giant stars members of the Galactic outer halo. Three spectrographs were used: HRS@HET (stars #1 to #7), MIKE@Magellan (stars #8 to #18), and UVES@VLT (stars #19 to #28). Stars #21, #26, and #28 were also observed with HRS@HET. Element abundances were determined using the equivalent width method. The tables 5 to 11 presented here contain the spectral line parameters, observed equivalent widths and corresponding abundances for all lines adopted for the abundance determination in the 28 stars of the sample. Table 5 contains this data for stars #1, #2, #3, #4, and #21 all observed with HRS@HET. Table 6 contains the same for stars #26, #5, #6, #7, and #28 observed with HRS@HET (note that stars #21, #26, and #28 were also observed with UVES@VLT, and we display in Tables 5 and 6 their equivalent widths and abundances based on their HRS spectra for comparison purpose). Table 7 contains the same data, but for stars #8, #9, #10, #11, and #12 observed with MIKE@Magellan; Tables 8 and 9 contain the same for stars #13, #14, #15, #16, #17 and for star #18 respectively, all observed with MIKE@Magellan. Tables 10 and 11 contain the same data for stars #19, #20, #21, #22, #23 and for stars #24, #25, #26, #27, #28 respectively, all observed with UVES@VLT. (8 data files).

Hybrid Interferometric/Dispersive Atomic Spectroscopy For Nuclear Materials Analysis

NASA Astrophysics Data System (ADS)

Morgan, Phyllis K.

Laser-induced breakdown spectroscopy (LIBS) is an optical emission spectroscopy technique that holds promise for detection and rapid analysis of elements relevant for nuclear safeguards and nonproliferation, including the measurement of isotope ratios. One important application of LIBS is the measurement of uranium enrichment (235U/238U), which requires high spectral resolution (e.g., 25 pm for the 424.437 nm U II line). Measuring uranium enrichment is important in nuclear nonproliferation and safeguards because the uranium highly enriched in the 235U isotope can be used to construct nuclear weapons. High-resolution dispersive spectrometers necessary for such measurements are typically bulky and expensive. A hybrid interferometric/dispersive spectrometer prototype, which consists of an inexpensive, compact Fabry-Perot etalon integrated with a low to moderate resolution Czerny-Turner spectrometer, was assembled for making high-resolution measurements of nuclear materials in a laboratory setting. To more fully take advantage of this low-cost, compact hybrid spectrometer, a mathematical reconstruction technique was developed to accurately reconstruct relative line strengths from complex spectral patterns with high resolution. Measurement of the mercury 313.1555/313.1844 nm doublet from a mercury-argon lamp yielded a spectral line intensity ratio of 0.682, which agrees well with an independent measurement by an echelle spectrometer and previously reported values. The hybrid instrument was used in LIBS measurements and achieved the resolution needed for isotopic selectivity of LIBS of uranium in ambient air. The samples used were a natural uranium foil (0.7% of 235U) and a uranium foil highly enriched in 235U to 93%. Both samples were provided by the Penn State University's Breazeale Nuclear Reactor. The enrichment of the uranium foils was verified using a high-purity germanium detector and dedicated software for multi-group spectral analysis. Uranium spectral line widths of ˜10 pm were measured at a center wavelength 424.437 nm, clearly discriminating the natural from the highly enriched uranium at that wavelength. The 424.167 nm isotope shift (˜6 pm), limited by spectral broadening, was only partially resolved but still discernible. This instrument and reconstruction method could enable the design of significantly smaller, portable high-resolution instruments with isotopic specificity, benefiting nuclear safeguards, treaty verification, nuclear forensics, and a variety of other spectroscopic applications.

Line-width roughness of advanced semiconductor features by using FIB and planar-TEM as reference metrology

NASA Astrophysics Data System (ADS)

Takamasu, Kiyoshi; Takahashi, Satoru; Kawada, Hiroki; Ikota, Masami

2018-03-01

LER (Line Edge Roughness) and LWR (Line Width Roughness) of the semiconductor device are an important evaluation scale of the performance of the device. Conventionally, LER and LWR is evaluated from CD-SEM (Critical Dimension Scanning Electron Microscope) images. However, CD-SEM measurement has a problem that high frequency random noise is large, and resolution is not sufficiently high. For random noise of CD-SEM measurement, some techniques are proposed. In these methods, it is necessary to set parameters for model and processing, and it is necessary to verify the correctness of these parameters using reference metrology. We have already proposed a novel reference metrology using FIB (Focused Ion Beam) process and planar-TEM (Transmission Electron Microscope) method. In this study, we applied the proposed method to three new samples such as SAQP (Self-Aligned Quadruple Patterning) FinFET device, EUV (Extreme Ultraviolet Lithography) conventional resist, and EUV new material resist. LWR and PSD (Power Spectral Density) of LWR are calculated from the edge positions on planar-TEM images. We confirmed that LWR and PSD of LWR can be measured with high accuracy and evaluated the difference by the proposed method. Furthermore, from comparisons with PSD of the same sample by CD-SEM, the validity of measurement of PSD and LWR by CD-SEM can be verified.

A Coordinated X-Ray and Optical Campaign of the Nearest Massive Eclipsing Binary, δ Orionis Aa. II. X-Ray Variability

NASA Astrophysics Data System (ADS)

Nichols, J.; Huenemoerder, D. P.; Corcoran, M. F.; Waldron, W.; Nazé, Y.; Pollock, A. M. T.; Moffat, A. F. J.; Lauer, J.; Shenar, T.; Russell, C. M. P.; Richardson, N. D.; Pablo, H.; Evans, N. R.; Hamaguchi, K.; Gull, T.; Hamann, W.-R.; Oskinova, L.; Ignace, R.; Hoffman, Jennifer L.; Hole, K. T.; Lomax, J. R.

2015-08-01

We present time-resolved and phase-resolved variability studies of an extensive X-ray high-resolution spectral data set of the δ Ori Aa binary system. The four observations, obtained with Chandra ACIS HETGS, have a total exposure time of ≈ 479 ks and provide nearly complete binary phase coverage. Variability of the total X-ray flux in the range of 5-25 Å is confirmed, with a maximum amplitude of about ±15% within a single ≈ 125 ks observation. Periods of 4.76 and 2.04 days are found in the total X-ray flux, as well as an apparent overall increase in the flux level throughout the nine-day observational campaign. Using 40 ks contiguous spectra derived from the original observations, we investigate the variability of emission line parameters and ratios. Several emission lines are shown to be variable, including S xv, Si xiii, and Ne ix. For the first time, variations of the X-ray emission line widths as a function of the binary phase are found in a binary system, with the smallest widths at ϕ = 0.0 when the secondary δ Ori Aa2 is at the inferior conjunction. Using 3D hydrodynamic modeling of the interacting winds, we relate the emission line width variability to the presence of a wind cavity created by a wind-wind collision, which is effectively void of embedded wind shocks and is carved out of the X-ray-producing primary wind, thus producing phase-locked X-ray variability. Based on data from the Chandra X-ray Observatory and the MOST satellite, a Canadian Space Agency mission, jointly operated by Dynacon Inc., the University of Toronto Institute of Aerospace Studies, and the University of British Columbia, with the assistance of the University of Vienna.

Observational Signatures of Transverse Magnetohydrodynamic Waves and Associated Dynamic Instabilities in Coronal Flux Tubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antolin, P.; Moortel, I. De; Doorsselaere, T. Van

Magnetohydrodynamic (MHD) waves permeate the solar atmosphere and constitute potential coronal heating agents. Yet, the waves detected so far may be but a small subset of the true existing wave power. Detection is limited by instrumental constraints but also by wave processes that localize the wave power in undetectable spatial scales. In this study, we conduct 3D MHD simulations and forward modeling of standing transverse MHD waves in coronal loops with uniform and non-uniform temperature variation in the perpendicular cross-section. The observed signatures are largely dominated by the combination of the Kelvin–Helmholtz instability (KHI), resonant absorption, and phase mixing. Inmore » the presence of a cross-loop temperature gradient, we find that emission lines sensitive to the loop core catch different signatures compared to those that are more sensitive to the loop boundary and the surrounding corona, leading to an out-of-phase intensity and Doppler velocity modulation produced by KHI mixing. In all of the considered models, common signatures include an intensity and loop width modulation at half the kink period, a fine strand-like structure, a characteristic arrow-shaped structure in the Doppler maps, and overall line broadening in time but particularly at the loop edges. For our model, most of these features can be captured with a spatial resolution of 0.″33 and a spectral resolution of 25 km s{sup −1}, although we do obtain severe over-estimation of the line width. Resonant absorption leads to a significant decrease of the observed kinetic energy from Doppler motions over time, which is not recovered by a corresponding increase in the line width from phase mixing and KHI motions. We estimate this hidden wave energy to be a factor of 5–10 of the observed value.« less

Ultraviolet emission lines in young low-mass galaxies at z ≃ 2: physical properties and implications for studies at z > 7

NASA Astrophysics Data System (ADS)

Stark, Daniel P.; Richard, Johan; Siana, Brian; Charlot, Stéphane; Freeman, William R.; Gutkin, Julia; Wofford, Aida; Robertson, Brant; Amanullah, Rahman; Watson, Darach; Milvang-Jensen, Bo

2014-12-01

We present deep spectroscopy of 17 very low mass (M⋆ ≃ 2.0 × 106-1.4 × 109 M⊙) and low luminosity (MUV ≃ -13.7 to -19.9) gravitationally lensed galaxies in the redshift range z ≃ 1.5-3.0. Deep rest-frame ultraviolet spectra reveal large equivalent width emission from numerous emission lines (N IV], O III], C IV, Si III], C III]) which are rarely seen in individual spectra of more massive star-forming galaxies. C III] is detected in 16 of 17 low-mass star-forming systems with rest-frame equivalent widths as large as 13.5 Å. Nebular C IV emission is present in the most extreme C III] emitters, requiring an ionizing source capable of producing a substantial component of photons with energies in excess of 47.9 eV. Photoionization models support a picture whereby the large equivalent widths are driven by the increased electron temperature and enhanced ionizing output arising from metal-poor gas and stars (0.04-0.13 Z⊙), young stellar populations (6-50 Myr), and large ionization parameters (log U = -2.16 to -1.84). The young ages implied by the emission lines and continuum spectral energy distributions (SEDs) indicate that the extreme line emitters in our sample are in the midst of a significant upturn in their star formation activity. The low stellar masses, blue UV colours, and large specific star formation rates of our sample are similar to those of typical z ≳ 6 galaxies. Given the strong attenuation of Lyα in z ≳ 6 galaxies, we suggest that C III] is likely to provide our best probe of early star-forming galaxies with ground-based spectrographs and one off the most efficient means of confirming z ≳ 10 galaxies with the James Webb Space Telescope.

Calibration of the OHREX high-resolution imaging crystal spectrometer at the Livermore electron beam ion traps

NASA Astrophysics Data System (ADS)

Hell, N.; Beiersdorfer, P.; Magee, E. W.; Brown, G. V.

2016-11-01

We report the calibration of the Orion High-Resolution X-ray (OHREX) imaging crystal spectrometer at the EBIT-I electron beam ion trap at Livermore. Two such instruments, dubbed OHREX-1 and OHREX-2, are fielded for plasma diagnostics at the Orion laser facility in the United Kingdom. The OHREX spectrometer can simultaneously house two spherically bent crystals with a radius of curvature of r = 67.2 cm. The focusing properties of the spectrometer allow both for larger distance to the source due to the increase in collected light and for observation of extended sources. OHREX is designed to cover a 2.5°-3° spectral range at Bragg angles around 51.3°. The typically high resolving powers at these large Bragg angles are ideally suited for line shape diagnostics. For instance, the nominal resolving power of the instrument (>10 000) is much higher than the effective resolving power associated with the Doppler broadening due to the temperature of the trapped ions in EBIT-I. The effective resolving power is only around 3000 at typical EBIT-I conditions, which nevertheless is sufficient to set up and test the instrument's spectral characteristics. We have calibrated the spectral range for a number of crystals using well known reference lines in the first and second order and derived the ion temperatures from these lines. We have also made use of the 50 μm size of the EBIT-I source width to characterize the spatial focusing of the spectrometer.

High-resolution Observations of Hα Spectra with a Subtractive Double Pass

NASA Astrophysics Data System (ADS)

Beck, C.; Rezaei, R.; Choudhary, D. P.; Gosain, S.; Tritschler, A.; Louis, R. E.

2018-02-01

High-resolution imaging spectroscopy in solar physics has relied on Fabry-Pérot interferometers (FPIs) in recent years. FPI systems, however, become technically challenging and expensive for telescopes larger than the 1 m class. A conventional slit spectrograph with a diffraction-limited performance over a large field of view (FOV) can be built at much lower cost and effort. It can be converted into an imaging spectro(polari)meter using the concept of a subtractive double pass (SDP). We demonstrate that an SDP system can reach a similar performance as FPI-based systems with a high spatial and moderate spectral resolution across a FOV of 100^'' ×100^' ' with a spectral coverage of 1 nm. We use Hα spectra taken with an SDP system at the Dunn Solar Telescope and complementary full-disc data to infer the properties of small-scale superpenumbral filaments. We find that the majority of all filaments end in patches of opposite-polarity fields. The internal fine-structure in the line-core intensity of Hα at spatial scales of about 0.5'' exceeds that in other parameters such as the line width, indicating small-scale opacity effects in a larger-scale structure with common properties. We conclude that SDP systems in combination with (multi-conjugate) adaptive optics are a valid alternative to FPI systems when high spatial resolution and a large FOV are required. They can also reach a cadence that is comparable to that of FPI systems, while providing a much larger spectral range and a simultaneous multi-line capability.

Calibration of the OHREX high-resolution imaging crystal spectrometer at the Livermore electron beam ion traps

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hell, N.; Dr. Remeis-Sternwarte and ECAP, Universität Erlangen-Nürnberg, Bamberg 96049; Beiersdorfer, P.

2016-11-15

We report the calibration of the Orion High-Resolution X-ray (OHREX) imaging crystal spectrometer at the EBIT-I electron beam ion trap at Livermore. Two such instruments, dubbed OHREX-1 and OHREX-2, are fielded for plasma diagnostics at the Orion laser facility in the United Kingdom. The OHREX spectrometer can simultaneously house two spherically bent crystals with a radius of curvature of r = 67.2 cm. The focusing properties of the spectrometer allow both for larger distance to the source due to the increase in collected light and for observation of extended sources. OHREX is designed to cover a 2.5°–3° spectral range atmore » Bragg angles around 51.3°. The typically high resolving powers at these large Bragg angles are ideally suited for line shape diagnostics. For instance, the nominal resolving power of the instrument (>10 000) is much higher than the effective resolving power associated with the Doppler broadening due to the temperature of the trapped ions in EBIT-I. The effective resolving power is only around 3000 at typical EBIT-I conditions, which nevertheless is sufficient to set up and test the instrument’s spectral characteristics. We have calibrated the spectral range for a number of crystals using well known reference lines in the first and second order and derived the ion temperatures from these lines. We have also made use of the 50 μm size of the EBIT-I source width to characterize the spatial focusing of the spectrometer.« less

Experimental Study of Temperature-Dependence Laws of Non-Voigt Absorption Line Shape Parameters

NASA Astrophysics Data System (ADS)

Wilzewski, Jonas; Birk, Manfred; Loos, Joep; Wagner, Georg

2017-06-01

To improve the understanding of temperature-dependence laws of spectral line shape parameters, spectra of the ν_3 rovibrational band of CO_2 perturbed by 10, 30, 100, 300 and 1000 mbar of N_2 were measured at nine temperatures between 190 K and 330 K using a 22 cm long single-pass absorption cell in a Bruker IFS125 HR Fourier Transform spectrometer. The spectra were fitted employing a quadratic speed-dependent hard collision model in the Hartmann-Tran implementation extended to account for line mixing in the Rosenkranz approximation by means of a multispectrum fitting approach developed at DLR This enables high accuracy parameter retrievals to reproduce the spectra down to noise level and we will present the behavior of line widths, shifts, speed-dependence-, collisional narrowing- and line mixing-parameters over this 140 K temperature range. Tran et al. JQSRT 129, 199-203 (2013); JQSRT 134, 104 (2014). Loos et al., 2014; http://doi.org/10.5281/zenodo.11156. Ngo et al. JQSRT 29, 89-100 (2013); JQSRT 134, 105 (2014).

Chromospheric explosions

NASA Technical Reports Server (NTRS)

Doschek, G. A.; theory. (3) Resolved: Most chromospheric h; theory. (3) Resolved: Most chromospheric h

1986-01-01

Three issues relative to chromospheric explosions were debated. (1) Resolved: The blue-shifted components of x-ray spectral lines are signatures of chromospheric evaporation. It was concluded that the plasma rising with the corona is indeed the primary source of thermal plasma observed in the corona during flares. (2) Resolved: The excess line broading of UV and X-ray lines is accounted for by a convective velocity distribution in evaporation. It is concluded that the hypothesis that convective evaporation produces the observed X-ray line widths in flares is no more than a hypothesis. It is not supported by any self-consistent physical theory. (3) Resolved: Most chromospheric heating is driven by electron beams. Although it is possible to cast doubt on many lines of evidence for electron beams in the chromosphere, a balanced view that debaters on both sides of the question might agree to is that electron beams probably heat the low corona and upper chromosphere, but their direct impact on evaporating the chromosphere is energetically unimportant when compared to conduction. This represents a major departure from the thick-target flare models that were popular before the Workshop.

THE DUST SUBLIMATION RADIUS AS AN OUTER ENVELOPE TO THE BULK OF THE NARROW Fe Kα LINE EMISSION IN TYPE 1 AGNs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gandhi, Poshak; Hönig, Sebastian F.; Kishimoto, Makoto

2015-10-20

The Fe Kα emission line is the most ubiquitous feature in the X-ray spectra of active galactic nuclei (AGNs), but the origin of its narrow core remains uncertain. Here, we investigate the connection between the sizes of the Fe Kα core emission regions and the measured sizes of the dusty tori in 13 local Type 1 AGNs. The observed Fe Kα emission radii (R{sub Fe}) are determined from spectrally resolved line widths in X-ray grating spectra, and the dust sublimation radii (R{sub dust}) are measured either from optical/near-infrared (NIR) reverberation time lags or from resolved NIR interferometric data. This directmore » comparison shows, on an object-by-object basis, that the dust sublimation radius forms an outer envelope to the bulk of the Fe Kα emission. R{sub Fe} matches R{sub dust} well in the AGNs, with the best constrained line widths currently. In a significant fraction of objects without a clear narrow line core, R{sub Fe} is similar to, or smaller than, the radius of the optical broad line region. These facts place important constraints on the torus geometries for our sample. Extended tori in which the solid angle of fluorescing gas peaks at well beyond the dust sublimation radius can be ruled out. We also test for luminosity scalings of R{sub Fe}, finding that the Eddington ratio is not a prime driver in determining the line location in our sample. We also discuss in detail potential caveats of data analysis and instrumental limitations, simplistic line modeling, uncertain black hole masses, and sample selection, showing that none of these is likely to bias our core result. The calorimeter on board Astro-H will soon vastly increase the parameter space over which line measurements can be made, overcoming many of these limitations.« less

Line-dependent veiling in very active classical T Tauri stars

NASA Astrophysics Data System (ADS)

Rei, A. C. S.; Petrov, P. P.; Gameiro, J. F.

2018-02-01

Context. The T Tauri stars with active accretion disks show veiled photospheric spectra. This is supposedly due to non-photospheric continuum radiated by hot spots beneath the accretion shocks at stellar surface and/or chromospheric emission lines radiated by the post-shocked gas. The amount of veiling is often considered as a measure of the mass-accretion rate. Aim. We analysed high-resolution photospheric spectra of accreting T Tauri stars LkHα 321, V1331 Cyg, and AS 353A with the aim of clarifying the nature of the line-dependent veiling. Each of these objects shows a strong emission line spectrum and powerful wind features indicating high rates of accretion and mass loss. Methods: Equivalent widths of hundreds of weak photospheric lines were measured in the observed spectra of high quality and compared with those in synthetic spectra of appropriate models of stellar atmospheres. Results: The photospheric spectra of the three T Tauri stars are highly veiled. We found that the veiling is strongly line-dependent: larger in stronger photospheric lines and weak or absent in the weakest ones. No dependence of veiling on excitation potential within 0 to 5 eV was found. Different physical processes responsible for these unusual veiling effects are discussed in the framework of the magnetospheric accretion model. Conclusions: The observed veiling has two origins: (1) an abnormal structure of stellar atmosphere heated up by the accreting matter, and (2) a non-photospheric continuum radiated by a hot spot with temperature lower than 10 000 K. The true level of the veiling continuum can be derived by measuring the weakest photospheric lines with equivalent widths down to ≈10 mÅ. A limited spectral resolution and/or low signal-to-noise ratio results in overestimation of the veiling continuum. In the three very active stars, the veiling continuum is a minor contributor to the observed veiling, while the major contribution comes from the line-dependent veiling.

VizieR Online Data Catalog: Excess CaII H&K emission in active binaries (Montes+, 1996)

NASA Astrophysics Data System (ADS)

Montes, D.; Fernandez-Figueroa, M. J.; Cornide, M.; de Castro, E.

1996-05-01

In this work we analyze the behaviour of the excess CaII H & K and H_epsilon emissions in a sample of 73 chromospherically active binary systems (RS CVn and BY Dra classes), of different activity levels and luminosity classes. This sample includes the 53 stars analyzed by Fernandez-Figueroa et al. (1994) and the observations of 28 systems described by Montes et al. (1995). By using the spectral subtraction technique (subtraction of a synthesized stellar spectrum constructed from reference stars of spectral type and luminosity class similar to those of the binary star components) we obtain the active-chromosphere contribution to the CaII H & K lines in these 73 systems. We have determined the excess CaII H & K emission equivalent widths and converted them into surface fluxes. The emissions arising from each component were obtained when it was possible to deblend both contributions. (4 data files).

AKARI/IRC NEAR-INFRARED SPECTRAL ATLAS OF GALACTIC PLANETARY NEBULAE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ohsawa, Ryou; Onaka, Takashi; Sakon, Itsuki

2016-04-15

Near-infrared (2.5–5.0 μm) low-resolution (λ/Δλ ∼ 100) spectra of 72 Galactic planetary nebulae (PNe) were obtained with the Infrared Camera (IRC) in the post-helium phase. The IRC, equipped with a 1′ × 1′ window for spectroscopy of a point source, was capable of obtaining near-infrared spectra in a slit-less mode without any flux loss due to a slit. The spectra show emission features including hydrogen recombination lines and the 3.3–3.5 μm hydrocarbon features. The intensity and equivalent width of the emission features were measured by spectral fitting. We made a catalog providing unique information on the investigation of the near-infrared emission ofmore » PNe. In this paper, details of the observations and characteristics of the catalog are described.« less

Stellar and Circumstellar Properties of Low-Mass, Young, Subarcsecond Binaries

NASA Astrophysics Data System (ADS)

Bruhns, Sara; Prato, L. A.

2014-01-01

We present a study of the stellar and circumstellar characteristics of close (< 1''), young (< 2 to 3 Myr), low-mass (<1 solar mass) binary stars in the Taurus star forming region. Low-resolution (R ~ 2000) spectra were taken in the K-band using adaptive optics to separate the observations for each component and identify the individual spectral types, extinction, and K-band excess. Combining these data with stellar luminosities allows us to estimate the stellar masses and ages. We also measured equivalent widths of the hydrogen Brackett gamma line in order to estimate the strength of gas accretion. We obtained spectra for six binary systems with separations from 1'' down to 0.3''. In the CZ Tau binary we found that the fainter secondary star spectrum appears to be of earlier spectral type than the primary; we speculate on the origin of this inversion.

High-power ultra-broadband frequency comb from ultraviolet to infrared by high-power fiber amplifiers.

PubMed

Yang, Kangwen; Li, Wenxue; Yan, Ming; Shen, Xuling; Zhao, Jian; Zeng, Heping

2012-06-04

A high-power ultra-broadband frequency comb covering the spectral range from ultraviolet to infrared was generated directly by nonlinear frequency conversion of a multi-stage high-power fiber comb amplifier. The 1030-nm infrared spectral fraction of a broadband Ti:sapphire femtosecond frequency comb was power-scaled up to 100 W average power by using a large-mode-area fiber chirped-pulse amplifier. We obtained a frequency-doubled green comb at 515 nm and frequency-quadrupled ultraviolet pulses at 258 nm with the average power of 12.8 and 1.62 W under the input infrared power of 42.2 W, respectively. The carrier envelope phase stabilization was accomplished with an ultra-narrow line-width of 1.86 mHz and a quite low accumulated phase jitter of 0.41 rad, corresponding to a timing jitter of 143 as.

Be Stars in the Open Cluster NGC 6830

NASA Astrophysics Data System (ADS)

Yu, Po-Chieh; Lin, Chien-Cheng; Lin, Hsing-Wen; Lee, Chien-De; Konidaris, Nick; Ngeow, Chow-Choong; Ip, Wing-Huen; Chen, Wen-Ping; Chen, Hui-Chen; Malkan, Matthew A.; Chang, Chan-Kao; Laher, Russ; Huang, Li-Ching; Cheng, Yu-Chi; Edelson, Rick; Ritter, Andreas; Quimby, Robert; Ben-Ami, Sagi; Ofek, Eran. O.; Surace, Jason; Kulkarni, Shrinivas R.

2016-05-01

We report the discovery of two new Be stars, and re-identify one known Be star in the open cluster NGC 6830. Eleven Hα emitters were discovered using the Hα imaging photometry of the Palomar Transient Factory Survey. Stellar membership of the candidates was verified with photometric and kinematic information using 2MASS data and proper motions. The spectroscopic confirmation was carried out by using the Shane 3 m telescope at the Lick observatory. Based on their spectral types, three Hα emitters were confirmed as Be stars with Hα equivalent widths greater than -10 Å. Two objects were also observed by the new spectrograph spectral energy distribution-machine (SED-machine) on the Palomar 60-inch Telescope. The SED-machine results show strong Hα emission lines, which are consistent with the results of the Lick observations. The high efficiency of the SED-machine can provide rapid observations for Be stars in a comprehensive survey in the future.

VizieR Online Data Catalog: Spectral atlas of HD 50138 (Borges Fernandes+, 2009)

NASA Astrophysics Data System (ADS)

Borges Fernandes, M.; Kraus, M.; Chesneau, O.; Domiciano de Souza, A.; de Araujo, F. X.; Stee, P.; Meilland, A.

2009-09-01

In this table, it is described the lines identified, with their radial velocities and equivalent widths in the high-resolution FEROS spectra obtained in 1999 and 2007. FEROS is a bench-mounted Echelle spectrograph with fibers, which covers a sky area of 2" of diameter, with a wavelength coverage from 360nm to 920nm and a spectral resolution of R=55000 (in the region around 600nm). The spectrum of 1999 was obtained with an exposure time of 180 seconds and has a S/N ratio of approximately 80 in the 550nm region. In 2007, we were able to take two consecutive spectra of the star, both with 180 seconds of exposure time. Since these spectra do not show significant differences, we added them up for a better S/N ratio, which is around 250. (1 data file).

High Spectral Resolution Lidar for atmospheric temperature profiling.

NASA Astrophysics Data System (ADS)

Razenkov, I.; Eloranta, E. W.

2017-12-01

The High Spectral Resolution Lidar (HSRL) designed at the University of Wisconsin-Madison is equipped with two iodine absorption filters with different line widths (1.8 GHz and 2.85 GHz). The filters are implemented to discriminate between Mie and Rayleigh backscattering and to resolve temperature sensitive changes in Rayleigh spectrum for atmospheric temperature profile measurements. This measurement capability makes the instrument intrinsically and absolutely calibrated. HSRL has a shared transmitter-receiver telescope and operates in the eye-safe mode with the product of laser average power and telescope aperture less than 0.025 𝑊𝑚2 at 532 nm. With this low-power prototype instrument we have achieved temperature profile measurements extending above tropopause with a time resolution of several hours. Further instrument optimizations will reduce systematic measurement errors and will improve a signal-to-noise ratio providing temperature data comparable to a standard radiosonde with higher time resolution.

Pulsed Thermal Emission from the Accreting Pulsar XMMU J054134.7-682550

NASA Astrophysics Data System (ADS)

Manousakis, Antonis; Walter, Roland; Audard, Marc; Lanz, Thierry

2009-05-01

XMMU J054134.7-682550, located in the LMC, featured a type II outburst in August 2007. We analyzed XMM-Newton (EPIC-MOS) and RXTE (PCA) data in order to derive the spectral and temporal characteristics of the system throughout the outburst. Spectral variability, spin period evolution, energy dependent pulse shape are discussed. The outburst (LX~3×1038 erg/s~LEDD) spectrum can be modeled using, cutoff power law, soft X-ray blackbody, disk emission, and cyclotron absorption line. The blackbody component shows a sinusoidal behavior, expected from hard X-ray reprocessing on the inner edge of the accretion disk. The thickness of the inner accretion disk (width of ~75 km) can be constrained. The spin-up of the pulsar during the outburst is the signature of a (huge) accretion rate. Simbol-X will provide similar capabilities as XMM-Newton and RXTE together, for such bright events.

Spectral shape deformation in inverse spin Hall voltage in Y{sub 3}Fe{sub 5}O{sub 12}|Pt bilayers at high microwave power levels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lustikova, J., E-mail: lustikova@imr.tohoku.ac.jp; Shiomi, Y.; Handa, Y.

2015-02-21

We report on the deformation of microwave absorption spectra and of the inverse spin Hall voltage signals in thin film bilayers of yttrium iron garnet (YIG) and platinum at high microwave power levels in a 9.45-GHz TE{sub 011} cavity. As the microwave power increases from 0.15 to 200 mW, the resonance field shifts to higher values, and the initially Lorentzian spectra of the microwave absorption intensity as well as the inverse spin Hall voltage signals become asymmetric. The contributions from opening of the magnetization precession cone and heating of YIG cannot well reproduce the data. Control measurements of inverse spinmore » Hall voltages on thin-film YIG|Pt systems with a range of line widths underscore the role of spin-wave excitations in spectral deformation.« less

Low Luminosity States of the Black Hole Candidate GX 339-4. 1; ASCA and Simultaneous Radio/RXTE Observations

NASA Technical Reports Server (NTRS)

Wilms, Joern; Nowak, Michael A.; Dove, James B.; Fender, Robert P.; DiMatteo, Tiziana

1998-01-01

We discuss a series of observations of the black hole candidate GX 339-4 in low luminosity, spectrally hard states. We present spectral analysis of three separate archival Advanced Satellite for Cosmology and Astrophysics (ASCA) data sets and eight separate Rossi X-ray Timing Explorer (RXTE) data sets. Three of the RXTE observations were strictly simultaneous with 843 Mega Hertz and 8.3-9.1 Giga Hertz radio observations. All of these observations have (3-9 keV) flux approximately less than 10(exp-9) ergs s(exp-1) CM(exp -2). The ASCA data show evidence for an approximately 6.4 keV Fe line with equivalent width approximately 40 eV, as well as evidence for a soft excess that is well-modeled by a power law plus a multicolor blackbody spectrum with peak temperature approximately equals 150-200 eV. The RXTE data sets also show evidence of an Fe line with equivalent widths approximately equal to 20-1OO eV. Reflection models show a hardening of the RXTE spectra with decreasing X-ray flux; however, these models do not exhibit evidence of a correlation between the photon index of the incident power law flux and the solid angle subtended by the reflector. 'Sphere+disk' Comptonization models and Advection Dominated Accretion Flow (ADAF) models also provide reasonable descriptions of the RXTE data. The former models yield coronal temperatures in the range 20-50 keV and optical depths of r approximately equal to 3. The model fits to the X-ray data, however, do not simultaneously explain the observed radio properties. The most likely source of the radio flux is synchrotron emission from an extended outflow of extent greater than O(10 (exp7) GM/c2).

Doppler-Zeeman Mapping of the Rapidly Rotating Magnetic CP Star HD37776

NASA Astrophysics Data System (ADS)

Khokhlova, V. L.; Vasilchenko, D. V.; Stepanov, V. V.; Romanyuk, I. I.

2000-03-01

We present the results of our analysis of magnetic-field configuration and abundance anomalies on the surface of the rapidly rotating, chemically peculiar helium-strong variable B2 V star HD37776 with unresolved Zeeman components of spectral lines. Simultaneous inversion of the observed Stokes I and V profiles, which realizes the method of Doppler-Zeeman mapping (Vasilchenko et al. 1996), has been applied for the first time. Spectroscopic observations were carried out with the Main stellar spectrograph of the 6-m Special Astrophysical Observatory telescope equipped with a Zeeman analyzer and a CCD array, which allowed spectra in right- and left-hand circularly polarized light to be taken simultaneously at a signal-to-noise ratio S/N > 200 (Romanyuk et al. 1999). The profile width of winged spectral lines (reaching 5 A) is determined by Zeeman line splitting; however, the observed Zeeman components are blurred and unresolved because of the rapid stellar rotation. When solving the inverse problem, we sought for the magnetic-field configuration in the form of a combination of arbitrarily oriented dipole, quadrupole, and octupole placed at the stellar center. The observed Stokes I and V profiles for eight spectral lines of He, OII, AlIII, SiIII, and FeIII averaged over the visible stellar surface were used as input data. We constructed a model of the magnetic field from the condition of coincidence of magnetic maps obtained from different lines of different chemical elements and from the condition of a minimum profile residual. This model is a combination of centered coaxial dipole and quadrupole with the dominant quadrupole component at 30 deg < i < 50 deg, beta = 40 deg, and a maximum surface field strength H_s = 60 kG. A comparison of our abundance maps with the field configuration shows that the He concentration is at a maximum in the regions of maximum radial field, while the maximum concentrations of O, Al, Si, and Fe coincide with the regions of maximum tangential field.

Continuous modulations of femtosecond laser-induced periodic surface structures and scanned line-widths on silicon by polarization changes.

PubMed

Han, Weina; Jiang, Lan; Li, Xiaowei; Liu, Pengjun; Xu, Le; Lu, YongFeng

2013-07-01

Large-area, uniform laser-induced periodic surface structures (LIPSS) are of wide potential industry applications. The continuity and processing precision of LIPSS are mainly determined by the scanning intervals of adjacent scanning lines. Therefore, continuous modulations of LIPSS and scanned line-widths within one laser scanning pass are of great significance. This study proposes that by varying the laser (800 nm, 50 fs, 1 kHz) polarization direction, LIPSS and the scanned line-widths on a silicon (111) surface can be continuously modulated with high precision. It shows that the scanned line-width reaches the maximum when the polarization direction is perpendicular to the scanning direction. As an application example, the experiments show large-area, uniform LIPSS can be fabricated by controlling the scanning intervals based on the one-pass scanned line-widths. The simulation shows that the initially formed LIPSS structures induce directional surface plasmon polaritons (SPP) scattering along the laser polarization direction, which strengthens the subsequently anisotropic LIPSS fabrication. The simulation results are in good agreement with the experiments, which both support the conclusions of continuous modulations of the LIPSS and scanned line-widths.

Minimum line width of ion beam-modified polystyrene by negative carbon ions for nerve-cell attachment and neurite extension

NASA Astrophysics Data System (ADS)

Sommani, P.; Tsuji, H.; Sato, H.; Kitamura, T.; Hattori, M.; Gotoh, Y.; Ishikawa, J.

2007-04-01

The minimum line width of the negative-ion-modified polystyrene (PS) for guidance and immobilizations of nerve-cell body and neurite extension have been investigated. Carbon negative ions were implanted into PS at fluence of 3 × 1015 ions/cm2 and energy of 5-20 keV through the various triangle apertures of the micro-pattern mask. After in vitro culture of the nerve-like cells of rat adrenal pheochromocytoma (PC12h), results showed that the minimum line widths for a single cell attachment and for neurite extension were 5-7 and 3-5 μm, respectively. While the minimum line width for attachment of cell group with long neurite was about 20 μm. The suitable widths for a large number of cells and for neurite extension were 20 and 5 μm, respectively. Therefore, the guidance for a clear separation of the attachment size of cell body and neurite extension could be achieved by the different modified line widths.

Long-term Spectral Evolution of Tidal Disruption Candidates Selected by Strong Coronal Lines

NASA Astrophysics Data System (ADS)

Yang, Chen-Wei; Wang, Ting-Gui; Ferland, Gary; Yuan, Weimin; Zhou, Hong-Yan; Jiang, Peng

2013-09-01

We present results of follow-up optical spectroscopic Multi-Mirror Telescope (MMT) observations of seven rare, extreme coronal line-emitting galaxies reported by Wang et al. Large variations in coronal lines are found in four objects, making them strong candidates for tidal disruption events (TDEs). For the four TDE candidates, all the coronal lines with ionization states higher than [Fe VII] disappear within 5-9 yr. The [Fe VII] line faded by a factor of about five in one object (J0952+2143) within 4 yr, whereas the line emerged in another two objects that previously did not show the line. A strong increment in the [O III] flux is observed, shifting the line ratios toward the loci of active galactic nuclei on the BPT diagram. Surprisingly, we detect a non-canonical [O III] λ5007/[O III] λ4959 ratio of ~= 2 in two objects, indicating a large column density of O2 + and thus probably optically thick gas. This result also requires a very large ionization parameter and a relatively soft ionizing spectral energy distribution (e.g., a blackbody with T < 5 × 104 K). Our observations can be explained as the echoing of a strong ultraviolet to soft X-ray flare caused by TDEs on molecular clouds in the inner parsecs of the galactic nuclei. Reanalyzing the Sloan Digital Sky Survey spectra reveals double-peaked or strongly blue-shouldered broad lines in three of the objects, which disappeared in the MMT spectra of two objects and faded by a factor of 10 in 8 yr in the remaining object with a decrease in both the line width and centroid offset. We interpret these broad lines as arising from decelerating biconical outflows. Our results demonstrate that the signatures of echoing can persist for as long as 10 yr and can be used to probe the gas environment in quiescent galactic nuclei.

Effective Temperatures for Young Stars in Binaries

NASA Astrophysics Data System (ADS)

Muzzio, Ryan; Avilez, Ian; Prato, Lisa A.; Biddle, Lauren I.; Allen, Thomas; Wright-Garba, Nuria Meilani Laure; Wittal, Matthew

2017-01-01

We have observed about 100 multi-star systems, within the star forming regions Taurus and Ophiuchus, to investigate the individual stellar and circumstellar properties of both components in young T Tauri binaries. Near-infrared spectra were collected using the Keck II telescope’s NIRSPEC spectrograph and imaging data were taken with Keck II’s NIRC2 camera, both behind adaptive optics. Some properties are straightforward to measure; however, determining effective temperature is challenging as the standard method of estimating spectral type and relating spectral type to effective temperature can be subjective and unreliable. We explicitly looked for a relationship between effective temperatures empirically determined in Mann et al. (2015) and equivalent width ratios of H-band Fe and OH lines for main sequence spectral type templates common to both our infrared observations and to the sample of Mann et al. We find a fit for a wide range of temperatures and are currently testing the validity of using this method as a way to determine effective temperature robustly. Support for this research was provided by an REU supplement to NSF award AST-1313399.

A study of rotational velocity distribution of Be stars

NASA Astrophysics Data System (ADS)

Sitko, C.; Janot-Pacheco, E.; Emilio, M.

2014-10-01

Classical Be stars are rapid rotators of spectral type late O to early A and luminosity class V-III, which exhibit Balmer emission lines and often a near infrared excess originating in an equatorially concentrated circumstellar envelope, both produced by sporadic mass ejection episodes. The causes of the abnormal mass loss (the so-called Be phenomenon) are as yet unknown. In spite of their high vsin i, rapid rotation alone cannot explain the ejection episodes as most Be stars do not rotate at their critical rotation rates. In this work we present the distribution of vsin i of 261 Be's stars from BeSS (Be Star Spectra) database. We used two techniques, the Fourier method and the FWHM (Full Width at Half Maximum) method. For the analysis we made use of three absorption lines of Helium (4026r A, 4388 Å and 4471 Å). Stars with projected rotational velocities up to 300 km s^{-1} agree with the ones already published in the literature. 84 of our stars do not have the values of rotational velocity published. The majority of our sample are B1/B2 spectral type, whose have the greatest velocities.

Imaging Spectrophotometry of the Jet/ISM Interaction in IC5063

NASA Technical Reports Server (NTRS)

Cecil, G.; Schuft, B.; Morse, J.; Bland-Hawthorn, J.

2004-01-01

IC5063 is a somewhat dusty z=0.0110 S0 galaxy with a Seyfert 2 nucleus. It has a triple radio source that spans 3 arcsec, mostly blueshifted H I absorption that spans 700 km/s, and ionization cones that extend for more than 2 arcmins. We obtained fully sampled [O III]\\lambda5007 grids at 0."9 and 70 km/s FWHM resolution using the Rutgers Fabry-Perot system on the Blanco 4m telescope. Complementary long-slit spectra using the RC spectrograph on the Blanco, and Taurus Tunable Filter spectral images in H\\alpha and [N II]\\lambda6583, were also obtained to assess gaseous ionization conditions. We present the results of our analysis, and correlate spectral structures to those visible in archival WFPC2 images. We find that, in the region near the radio triple, gaseous ionization and line velocity width is tightly correlated, in excellent quantitative agreement with the high-velocity shock regime in the diagnostic emission-line ratio diagrams of Dopita & Sutherland. We separate kinematically gas in normal disk rotation that is illuminated by the AGN in the ionization cones from that agitated mechanically by the jet, and assess the energy input from both processes.

A Multiwavelength Study of POX 52, a Dwarf Seyfert Galaxy with an Intermediate Mass Black Hole

NASA Astrophysics Data System (ADS)

Barth, Aaron

2004-09-01

POX 52 is a Seyfert 1 galaxy with unprecedented properties: its host galaxy is a dwarf elliptical, and its stellar velocity dispersion is only 36 km/s. The stellar velocity dispersion and the broad emission-line widths both suggest a black hole mass of order 10^5 solar masses. We request HST ACS/HRC imaging to perform a definitive measurement of the host galaxy structure; STIS UV and optical spectroscopy to study the nonstellar continuum and the structure of the broad-line region; and Chandra ACIS imaging to investigate the spectral and variability properties of the X-ray emission. The results of this program will give a detailed understanding of the host galaxy and accretion properties of one of the very few known black holes in the mass range around 10^5 solar masses.

Long-term magnetic field monitoring of the Sun-like star ξ Bootis A

NASA Astrophysics Data System (ADS)

Morgenthaler, A.; Petit, P.; Saar, S.; Solanki, S. K.; Morin, J.; Marsden, S. C.; Aurière, M.; Dintrans, B.; Fares, R.; Gastine, T.; Lanoux, J.; Lignières, F.; Paletou, F.; Ramírez Vélez, J. C.; Théado, S.; Van Grootel, V.

2012-04-01

Aims: We aim to investigate the long-term temporal evolution of the magnetic field of the solar-type star ξ Bootis A, both from direct magnetic field measurements and from the simultaneous estimate of indirect activity indicators. Methods: We obtained seven epochs of high-resolution, circularly-polarized spectra from the NARVAL spectropolarimeter between 2007 and 2011, for a total of 76 spectra. Using approximately 6100 photospheric spectral lines covering the visible domain, we employed a cross-correlation procedure to compute a mean polarized line profile from each spectrum. The large-scale photospheric magnetic field of the star was then modelled by means of Zeeman-Doppler Imaging, allowing us to follow the year-to-year evolution of the reconstructed magnetic topology. Simultaneously, we monitored the width of several magnetically sensitive spectral lines, the radial velocity, the line asymmetry of intensity line profiles, and the chromospheric emission in the cores of the Ca II H and Hα lines. Results: During the highest observed activity states, in 2007 and 2011, the large-scale field of ξ Bootis A is almost completely axisymmetric and is dominated by its toroidal component. The toroidal component persists with a constant polarity, containing a significant fraction of the magnetic energy of the large-scale surface field through all observing epochs. The magnetic topologies reconstructed for these activity maxima are very similar, suggesting a form of short cyclicity in the large-scale field distribution. The mean unsigned large-scale magnetic flux derived from the magnetic maps varies by a factor of about 2 between the lowest and highest observed magnetic states. The chromospheric flux is less affected and varies by a factor of 1.2. Correlated temporal evolution, due to both rotational modulation and seasonal variability, is observed between the Ca II emission, the Hα emission and the width of magnetically sensitive lines. The rotational dependence of polarimetric magnetic measurements displays a weak correlation with other activity proxies, presumably due to the different spatial scales and centre-to-limb darkening associated with polarimetric signatures, as compared to non-polarized activity indicators. Better agreement is observed on the longer term. When measurable, the differential rotation reveals a strong latitudinal shear in excess of 0.2 rad d-1. Based on observations obtained at the Bernard Lyot Telescope (TBL, Pic du Midi, France) of the Midi-Pyrénées Observatory, which is operated by the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France.Tables 3-6 are available in electronic form at http://www.aanda.org

High-Resolution, Ground-Based Observations of the Lunar Exosphere during the month of May from 2013 to 2016.

NASA Astrophysics Data System (ADS)

Kuruppuaratchi, D. C. P.; Oliversen, R. J.; Mierkiewicz, E. J.; Robertson, S. D.; Gallant, M.; Rosborough, S.; Sarantos, M.; Derr, N. J.

2017-12-01

We apply high resolution spectroscopy to investigate the lunar exosphere by measuring sodium and potassium spectral line profiles to determine the variations in exospheric effective temperatures and velocities. Observations were made at the National Solar Observatory McMath-Pierce Telescope. We used a dual-etalon Fabry-Perot spectrometer with a resolving power of 180,000 (1.7 km/s) to measure the line widths and radial velocities of Doppler shifted sodium D2 (5889.9509 Å) and potassium D1 (7698.9646 Å) emission lines. The instrument's, 2 arcmin ( 224 km) and 3 arcmin ( 336km), Field of View (FOV) is positioned off the limb in equatorial and high latitude regions. Therefore, observations taken at 1st and 3rd quarter are taken at local noon while observations taken at full moon are at 6 am (dawn) and 6 pm (dusk) locally. We discuss data taken during the month of May/June from 2013 to 2016 for sodium and 2014 to 2016 for potassium. The deconvolved line widths indicate sodium temperatures at large phase angles (phase > 40o) are on the order of 1600 K while temperatures near full Moon are on the order of 4500 K. Line widths and temperatures are largest during full Moon; a trend that is not due to geometrical effects of looking `down' the tail. A slight asymmetry between waxing phase data and waning phase data is seen in all years. At limb relative intensity data for sodium, corrected for the Sun-Moon motion, show intensities that are higher after full Moon; a result that is consistent with enhanced PSD efficiency after the Moon resides in the plasma sheet. The potassium relative intensity decreases significantly as the waxing moon approaches full moon but like sodium its intensity increases after exiting the magnetotail. November results for each year will be compared with May results to establish any orbital trends. This work was partially supported by the NASA Planetary Astronomy programs, NNX11AE38G and NNX13AL30G.

Line width determination using a biomimetic fly eye vision system.

PubMed

Benson, John B; Wright, Cameron H G; Barrett, Steven F

2007-01-01

Developing a new vision system based on the vision of the common house fly, Musca domestica, has created many interesting design challenges. One of those problems is line width determination, which is the topic of this paper. It has been discovered that line width can be determined with a single sensor as long as either the sensor, or the object in question, has a constant, known velocity. This is an important first step for determining the width of any arbitrary object, with unknown velocity.

Real-time line-width measurements: a new feature for reticle inspection systems

NASA Astrophysics Data System (ADS)

Eran, Yair; Greenberg, Gad; Joseph, Amnon; Lustig, Cornel; Mizrahi, Eyal

1997-07-01

The significance of line width control in mask production has become greater with the lessening of defect size. There are two conventional methods used for controlling line widths dimensions which employed in the manufacturing of masks for sub micron devices. These two methods are the critical dimensions (CD) measurement and the detection of edge defects. Achieving reliable and accurate control of line width errors is one of the most challenging tasks in mask production. Neither of the two methods cited above (namely CD measurement and the detection of edge defects) guarantees the detection of line width errors with good sensitivity over the whole mask area. This stems from the fact that CD measurement provides only statistical data on the mask features whereas applying edge defect detection method checks defects on each edge by itself, and does not supply information on the combined result of error detection on two adjacent edges. For example, a combination of a small edge defect together with a CD non- uniformity which are both within the allowed tolerance, may yield a significant line width error, which will not be detected using the conventional methods (see figure 1). A new approach for the detection of line width errors which overcomes this difficulty is presented. Based on this approach, a new sensitive line width error detector was developed and added to Orbot's RT-8000 die-to-database reticle inspection system. This innovative detector operates continuously during the mask inspection process and scans (inspects) the entire area of the reticle for line width errors. The detection is based on a comparison of measured line width that are taken on both the design database and the scanned image of the reticle. In section 2, the motivation for developing this new detector is presented. The section covers an analysis of various defect types, which are difficult to detect using conventional edge detection methods or, alternatively, CD measurements. In section 3, the basic concept of the new approach is introduced together with a description of the new detector and its characteristics. In section 4, the calibration process that took place in order to achieve reliable and repeatable line width measurements is presented. The description of an experiments conducted in order to evaluate the sensitivity of the new detector is given in section 5, followed by a report of the results of this evaluation. The conclusions are presented in section 6.

The Mean Metal-line Absorption Spectrum of Damped Ly α Systems in BOSS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mas-Ribas, Lluís; Miralda-Escudé, Jordi; Pérez-Ràfols, Ignasi

We study the mean absorption spectrum of the Damped Ly α (DLA) population at z ∼ 2.6 by stacking normalized, rest-frame-shifted spectra of ∼27,000 DLA systems from the DR12 of the Baryon Oscillation Spectroscopic Survey (BOSS)/SDSS-III. We measure the equivalent widths of 50 individual metal absorption lines in five intervals of DLA hydrogen column density, five intervals of DLA redshift, and overall mean equivalent widths for an additional 13 absorption features from groups of strongly blended lines. The mean equivalent width of low-ionization lines increases with N {sub H} {sub i}, whereas for high-ionization lines the increase is much weaker.more » The mean metal line equivalent widths decrease by a factor ∼1.1–1.5 from z ∼ 2.1 to z ∼ 3.5, with small or no differences between low- and high-ionization species. We develop a theoretical model, inspired by the presence of multiple absorption components observed in high-resolution spectra, to infer mean metal column densities from the equivalent widths of partially saturated metal lines. We apply this model to 14 low-ionization species and to Al iii, S iii, Si iii, C iv, Si iv, N v, and O vi. We use an approximate derivation for separating the equivalent width contributions of several lines to blended absorption features, and infer mean equivalent widths and column densities from lines of the additional species N i, Zn ii, C ii*, Fe iii, and S iv. Several of these mean column densities of metal lines in DLAs are obtained for the first time; their values generally agree with measurements of individual DLAs from high-resolution, high signal-to-noise ratio spectra when they are available.« less

X-RAY SPECTROSCOPY OF THE HIGH-MASS X-RAY BINARY PULSAR CENTAURUS X-3 OVER ITS BINARY ORBIT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Naik, Sachindra; Ali, Zulfikar; Paul, Biswajit, E-mail: snaik@prl.res.in

2011-08-20

We present a comprehensive spectral analysis of the high-mass X-ray binary (HMXB) pulsar Centaurus X-3 with the Suzaku observatory covering nearly one orbital period. The light curve shows the presence of extended dips which are rarely seen in HMXBs. These dips are seen up to as high as {approx}40 keV. The pulsar spectra during the eclipse, out-of-eclipse, and dips are found to be well described by a partial covering power-law model with high-energy cutoff and three Gaussian functions for 6.4 keV, 6.7 keV, and 6.97 keV iron emission lines. The dips in the light curve can be explained by themore » presence of an additional absorption component with high column density and covering fraction, the values of which are not significant during the rest of the orbital phases. The iron line parameters during the dips and eclipse are significantly different compared to those during the rest of the observation. During the dips, the iron line intensities are found to be lesser by a factor of 2-3 with a significant increase in the line equivalent widths. However, the continuum flux at the corresponding orbital phase is estimated to be lesser by more than an order of magnitude. Similarities in the changes in the iron line flux and equivalent widths during the dips and eclipse segments suggest that the dipping activity in Cen X-3 is caused by an obscuration of the neutron star by dense matter, probably structures in the outer region of the accretion disk, as in the case of dipping low-mass X-ray binaries.« less

Applying aerial digital photography as a spectral remote sensing technique for macrophytic cover assessment in small rural streams

NASA Astrophysics Data System (ADS)

Anker, Y.; Hershkovitz, Y.; Gasith, A.; Ben-Dor, E.

2011-12-01

Although remote sensing of fluvial ecosystems is well developed, the tradeoff between spectral and spatial resolutions prevents its application in small streams (<3m width). In the current study, a remote sensing approach for monitoring and research of small ecosystem was developed. The method is based on differentiation between two indicative vegetation species out of the ecosystem flora. Since when studied, the channel was covered mostly by a filamentous green alga (Cladophora glomerata) and watercress (Nasturtium officinale), these species were chosen as indicative; nonetheless, common reed (Phragmites australis) was also classified in order to exclude it from the stream ROI. The procedure included: A. For both section and habitat scales classifications, acquisition of aerial digital RGB datasets. B. For section scale classification, hyperspectral (HSR) dataset acquisition. C. For calibration, HSR reflectance measurements of specific ground targets, in close proximity to each dataset acquisition swath. D. For habitat scale classification, manual, in-stream flora grid transects classification. The digital RGB datasets were converted to reflectance units by spectral calibration against colored reference plates. These red, green, blue, white, and black EVA foam reference plates were measured by an ASD field spectrometer and each was given a spectral value. Each spectral value was later applied to the spectral calibration and radiometric correction of spectral RGB (SRGB) cube. Spectral calibration of the HSR dataset was done using the empirical line method, based on reference values of progressive grey scale targets. Differentiation between the vegetation species was done by supervised classification both for the HSR and for the SRGB datasets. This procedure was done using the Spectral Angle Mapper function with the spectral pattern of each vegetation species as a spectral end member. Comparison between the two remote sensing techniques and between the SRGB classification and the in-situ transects indicates that: A. Stream vegetation classification resolution is about 4 cm by the SRGB method compared to about 1 m by HSR. Moreover, this resolution is also higher than of the manual grid transect classification. B. The SRGB method is by far the most cost-efficient. The combination of spectral information (rather than the cognitive color) and high spatial resolution of aerial photography provides noise filtration and better sub-water detection capabilities than the HSR technique. C. Only the SRGB method applies for habitat and section scales; hence, its application together with in-situ grid transects for validation, may be optimal for use in similar scenarios.
The HSR dataset was first degraded to 17 bands with the same spectral range as the RGB dataset and also to a dataset with 3 equivalent bands

Method of controlling the mercury vapor pressure in a photo-chemical lamp or vapor filter used for Hg.sup.196 enrichment

DOEpatents

Grossman, Mark W.

1993-01-01

The present invention is directed to a method of eliminating the cold spot zones presently used on Hg.sup.196 isotope separation lamps and filters by the use of a mercury amalgams, preferably mercury - indium amalgams. The use of an amalgam affords optimization of the mercury density in the lamp and filter of a mercury enrichment reactor, particularly multilamp enrichment reactors. Moreover, the use of an amalgam in such lamps and/or filters affords the ability to control the spectral line width of radiation emitted from lamps, a requirement for mercury enrichment.

Method of controlling the mercury vapor pressure in a photo-chemical lamp or vapor filter used for Hg[sup 196] enrichment

DOEpatents

Grossman, M.W.

1993-02-16

The present invention is directed to a method of eliminating the cold spot zones presently used on Hg[sup 196] isotope separation lamps and filters by the use of a mercury amalgams, preferably mercury - indium amalgams. The use of an amalgam affords optimization of the mercury density in the lamp and filter of a mercury enrichment reactor, particularly multilamp enrichment reactors. Moreover, the use of an amalgam in such lamps and/or filters affords the ability to control the spectral line width of radiation emitted from lamps, a requirement for mercury enrichment.

Observable consequences of zero-point energy

NASA Astrophysics Data System (ADS)

Sen, Siddhartha; Gupta, Kumar S.

2017-12-01

Spectral line widths, the Lamb shift and the Casimir effect are generally accepted to be observable consequences of the zero-point electromagnetic (ZPEM) fields. A new class of observable consequences of ZPEM field at the mesoscopic scale were recently proposed and observed. Here, we extend this class of observable effects and predict that mesoscopic water layers should have a high value for its solid-liquid phase transition temperature, as illustrated by water inside a single-walled carbon nanotube (CNT). For this case, our analysis predicts that the phase transition temperature scales inversely with the square of the effective radius available for the water flow within the CNT.

Femtosecond soliton source with fast and broad spectral tunability.

PubMed

Masip, Martin E; Rieznik, A A; König, Pablo G; Grosz, Diego F; Bragas, Andrea V; Martinez, Oscar E

2009-03-15

We present a complete set of measurements and numerical simulations of a femtosecond soliton source with fast and broad spectral tunability and nearly constant pulse width and average power. Solitons generated in a photonic crystal fiber, at the low-power coupling regime, can be tuned in a broad range of wavelengths, from 850 to 1200 nm using the input power as the control parameter. These solitons keep almost constant time duration (approximately 40 fs) and spectral widths (approximately 20 nm) over the entire measured spectra regardless of input power. Our numerical simulations agree well with measurements and predict a wide working wavelength range and robustness to input parameters.

Chandra ACIS-I particle background: an analytical model

NASA Astrophysics Data System (ADS)

Bartalucci, I.; Mazzotta, P.; Bourdin, H.; Vikhlinin, A.

2014-06-01

Aims: Imaging and spectroscopy of X-ray extended sources require a proper characterisation of a spatially unresolved background signal. This background includes sky and instrumental components, each of which are characterised by its proper spatial and spectral behaviour. While the X-ray sky background has been extensively studied in previous work, here we analyse and model the instrumental background of the ACIS-I detector on board the Chandra X-ray observatory in very faint mode. Methods: Caused by interaction of highly energetic particles with the detector, the ACIS-I instrumental background is spectrally characterised by the superimposition of several fluorescence emission lines onto a continuum. To isolate its flux from any sky component, we fitted an analytical model of the continuum to observations performed in very faint mode with the detector in the stowed position shielded from the sky, and gathered over the eight-year period starting in 2001. The remaining emission lines were fitted to blank-sky observations of the same period. We found 11 emission lines. Analysing the spatial variation of the amplitude, energy and width of these lines has further allowed us to infer that three lines of these are presumably due to an energy correction artefact produced in the frame store. Results: We provide an analytical model that predicts the instrumental background with a precision of 2% in the continuum and 5% in the lines. We use this model to measure the flux of the unresolved cosmic X-ray background in the Chandra deep field south. We obtain a flux of 10.2+0.5-0.4 × 10-13 erg cm-2 deg-2 s-1 for the [1-2] keV band and (3.8 ± 0.2) × 10-12 erg cm-2 deg-2 s-1 for the [2-8] keV band.

Ultraviolet Properties of Halo Coronal Mass Ejections: Doppler Shifts, Angles, Shocks, and Bulk Morphology

NASA Astrophysics Data System (ADS)

Ciaravella, A.; Raymond, J. C.; Kahler, S. W.

2006-11-01

We present UV spectral information for 22 halo or partial halo CMEs observed by UVCS. The CME fronts show broad line profiles, while the line intensities are comparable to the background corona. The Doppler shifts of the front material are generally small, showing that the motion of gas in the fronts is mostly transverse to the line of sight. This indicates that, at least in halo CMEs, the fronts generally correspond to coronal plasma swept up by a shock or compression wave, rather than plasma carried outward by magnetic loops. This favors an ice cream cone (or a spherical shell) model, as opposed to an expanding arcade of loops. We use the line widths to discriminate between shock heating and bulk expansion. Of 14 cases where we detected the CME front, the line broadening in 7 cases can be attributed to shock heating, while in 3 cases it is the line-of-sight component of the CME expansion. For the CME cores we determine the angles between the motion and the plane of the sky, along with the actual heliocentric distances, in order to provide quantitative estimates of projection effects.

Potential Line Structure Variability in DIB Features Observed in Pathfinder tres Survey

NASA Astrophysics Data System (ADS)

Law, Charles; Milisavljevic, Dan; Crabtree, Kyle N.; Johansen, Sommer Lynn

2017-06-01

The Diffuse Interstellar Bands (DIBs) are hundreds of spectral lines observed in sightlines towards many stars in the optical and near-infrared. Although most of these transitions remain unassigned, four of them have recently been assigned to C_{60}^{+} and C_{70}^{+}. In earlier observations of the visible spectrum of the extragalactic supernova SN 2012ap, we observed changes in the equivalent widths of DIBs on the timescale of its light curve, which indicated that some DIB carriers might exist closer to massive stars then previously believed. Motivated by these findings, we undertook a pathfinder survey of 17 massive stars with the Tillinghast Reflector Echelle Spectrograph at Fred L. Whipple Observatory in search of temporal variability in DIBs. In 3 of the 17 stars, we found possible evidence for variation in line substructure of DIBs λ5797 and λ6614. In this talk, we will discuss our efforts to model λ5797 toward MT-59 using contour simulations based on previously published spectral models from higher resolution observations. Although the SNR of this spectrum was only 5-15, our preliminary results suggest that the variations in molecular spectra over time might arise from changes in carrier temperature. These early results demonstrate the need for higher SNR spectra taken at multiple epochs to further explore potential temporal variability. If successful, time-variation could provide additional evidence to assist in identifying DIB carriers.

FULL SPECTRAL SURVEY OF ACTIVE GALACTIC NUCLEI IN THE ROSSI X-RAY TIMING EXPLORER ARCHIVE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rivers, Elizabeth; Markowitz, Alex; Rothschild, Richard, E-mail: erivers@ucsd.edu

2013-08-01

We have analyzed spectra for all active galactic nuclei (AGNs) in the Rossi X-ray Timing Explorer archive. We present long-term average values of absorption, Fe line equivalent width (EW), Compton reflection, and photon index, and calculate fluxes and luminosities in the 2-10 keV band for 100 AGN with sufficient brightness and overall observation time to yield high-quality spectral results. We compare these parameters across the different classifications of Seyferts and blazars. Our distributions of photon indices for Seyfert 1s and 2s are consistent with the idea that Seyferts share a common central engine; however, our distributions of Compton reflection humpmore » strengths do not support the classical picture of absorption by a torus and reflection off a Compton-thick disk with type depending only on inclination angle. We conclude that a more complex reflecting geometry such as a combined disk and torus or clumpy torus is likely a more accurate picture of the Compton-thick material. We find that Compton reflection is present in {approx}85% of Seyferts and by comparing Fe line EW's to Compton reflection hump strengths we have found that on average 40% of the Fe line arises in Compton thick material; however, this ratio was not consistent from object to object and did not seem to be dependent on optical classification.« less

Possible 6-qubit NMR quantum computer device material; simulator of the NMR line width

NASA Astrophysics Data System (ADS)

Hashi, K.; Kitazawa, H.; Shimizu, T.; Goto, A.; Eguchi, S.; Ohki, S.

2002-12-01

For an NMR quantum computer, splitting of an NMR spectrum must be larger than a line width. In order to find a best device material for a solid-state NMR quantum computer, we have made a simulation program to calculate the NMR line width due to the nuclear dipole field by the 2nd moment method. The program utilizes the lattice information prepared by commercial software to draw a crystal structure. By applying this program, we can estimate the NMR line width due to the nuclear dipole field without measurements and find a candidate material for a 6-qubit solid-state NMR quantum computer device.

The effect of lane line width and contrast upon lanekeeping.

PubMed

McKnight, A S; McKnight, A J; Tippetts, A S

1998-09-01

The combined effect of lane line width and line-pavement contrast upon lanekeeping was studied through simulation. Some 124 subjects, ages 17-79 (x = 56.30), 52% male, each performed 42 trials over road segments representing three levels of width crossed with 14 line-pavement contrast ratios. Lanekeeping performance was recorded in terms of heading error, position error, lane excursions and road excursions. Subjects were stratified into two levels of ability on a combined measure of visual, attentional and psychomotor variables known to decline with age. Contrast and width had a negligible effect upon performance except at very low contrast ratios, ca 1.02 at high pavement luminance levels (e.g. concrete) and 1.04 for very low luminance levels (e.g. asphalt). These ratios are similar to those encountered at night on wet roads. Mean overall performance error at the low contrast ratios increased by a factor of 1.6, 1.8 and 2.2 for 8, 6 and 4" widths, respectively. Lower ability subjects exhibited greater error at almost all contrast ratios, with no consistent relationship between degree of decrement and either width or contrast. The results suggest that lane line width and contrast have a negligible effect upon lanekeeping performance except at extremely low levels of contrast, where both have large effects. Further research in the roadway environment is needed to determine the relationships of line width and contrast ratio to lanekeeping on normal and degraded surface conditions.

B-MINE: The Balloon-Borne Microcalorimeter Nuclear Line Explorer

NASA Technical Reports Server (NTRS)

Silver, E.; Schnopper, H.; Jones, C.; Forman, W.; Bandler, S.; Murray, S.; Romaine, S.; Slane, P.; Grindlay, J.; Madden, N.

2001-01-01

B-MINE is a concept for a balloon mission designed to probe the deepest regions of a supernova explosion by detecting 44Ti emission at 68 keV with spatial and spectral resolutions that are sufficient to determine the extent and velocity distribution of the 44Ti emitting region. The payload introduces the concept of focusing optics and microcalorimeter spectroscopy to nuclear line emission astrophysics. B-MINE has a thin, plastic foil telescope multilayered to maximize the reflectivity in a 20 keV band centered at 68 keV and a microcalorimeter array optimized for the same energy band. This combination provides a reduced background, an energy resolution of 50 eV and a 3 sigma sensitivity in 10 (exp 6) s of 3.3 x 10(exp -7) ph cm(exp -2) s(exp -1) at 68 keV. During the course of a long duration balloon flight, B-MINE could carry out a detailed study of the 44Ti emission line centroid and width in CAS A.

Electron spin resonance characterization of radical components in irradiated black pepper skin and core

NASA Astrophysics Data System (ADS)

Yamaoki, Rumi; Kimura, Shojiro; Ohta, Masatoshi

2011-11-01

Characteristics of free radical components of irradiated black pepper fruit (skin) and the pepper seed (core) were analyzed using electron spin resonance. A weak signal near g=2.005 was observed in black pepper before irradiation. Complex spectra near g=2.005 with three lines (the skin) or seven lines (the core) were observed in irradiated black pepper (both end line width; ca. 6.8 mT). The spectral intensities decreased considerably at 30 days after irradiation, and continued to decrease steadily thereafter. The spectra simulated on the basis of the content and the stability of radical components derived from plant constituents, including fiber, starch, polyphenol, mono- and disaccharide, were in good agreement with the observed spectra. Analysis showed that the signal intensities derived from fiber in the skin for an absorbed dose were higher, and the rates of decrease were lower, than that in the core. In particular, the cellulose radical component in the skin was highly stable.

ARES v2: new features and improved performance

NASA Astrophysics Data System (ADS)

Sousa, S. G.; Santos, N. C.; Adibekyan, V.; Delgado-Mena, E.; Israelian, G.

2015-05-01

Aims: We present a new upgraded version of ARES. The new version includes a series of interesting new features such as automatic radial velocity correction, a fully automatic continuum determination, and an estimation of the errors for the equivalent widths. Methods: The automatic correction of the radial velocity is achieved with a simple cross-correlation function, and the automatic continuum determination, as well as the estimation of the errors, relies on a new approach to evaluating the spectral noise at the continuum level. Results: ARES v2 is totally compatible with its predecessor. We show that the fully automatic continuum determination is consistent with the previous methods applied for this task. It also presents a significant improvement on its performance thanks to the implementation of a parallel computation using the OpenMP library. Automatic Routine for line Equivalent widths in stellar Spectra - ARES webpage: http://www.astro.up.pt/~sousasag/ares/Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 075.D-0800(A).

Near-infrared metallicities, radial velocities, and spectral types for 447 nearby M dwarfs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Newton, Elisabeth R.; Charbonneau, David; Irwin, Jonathan

We present metallicities, radial velocities, and near-infrared (NIR) spectral types for 447 M dwarfs determined from moderate resolution (R ≈ 2000) NIR spectra obtained with the NASA Infrared Telescope Facility (IRTF)/SpeX. These M dwarfs are primarily targets of the MEarth Survey, a transiting planet survey searching for super Earths around mid-to-late M dwarfs within 33 pc. We present NIR spectral types for each star and new spectral templates for the IRTF in the Y, J, H, and K-bands, created using M dwarfs with near-solar metallicities. We developed two spectroscopic distance calibrations that use NIR spectral type or an index basedmore » on the curvature of the K-band continuum. Our distance calibration has a scatter of 14%. We searched 27 NIR spectral lines and 10 spectral indices for metallicity sensitive features, taking into account correlated noise in our estimates of the errors on these parameters. We calibrated our relation using 36 M dwarfs in common proper pairs with an F-, G-, or K-type star of known metallicity. We validated the physical association of these pairs using proper motions, radial velocities, and spectroscopic distance estimates. Our resulting metallicity calibration uses the sodium doublet at 2.2 μm as the sole indicator for metallicity. It has an accuracy of 0.12 dex inferred from the scatter between the metallicities of the primaries and the estimated metallicities of the secondaries. Our relation is valid for NIR spectral types from M1V to M5V and for –1.0 dex < [Fe/H] < +0.35 dex. We present a new color-color metallicity relation using J – H and J – K colors that directly relates two observables: the distance from the M dwarf main sequence and equivalent width of the sodium line at 2.2 μm. We used radial velocities of M dwarf binaries, observations at different epochs, and comparison between our measurements and precisely measured radial velocities to demonstrate a 4 km s{sup –1} accuracy.« less

Investigation on chlorosomal antenna geometries: tube, lamella and spiral-type self-aggregates.

PubMed

Linnanto, Juha M; Korppi-Tommola, Jouko E I

2008-06-01

Molecular mechanics calculations and exciton theory have been used to study pigment organization in chlorosomes of green bacteria. Single and double rod, multiple concentric rod, lamella, and Archimedean spiral macrostructures of bacteriochlorophyll c molecules were created and their spectral properties evaluated. The effects of length, width, diameter, and curvature of the macrostructures as well as orientations of monomeric transition dipole moment vectors on the spectral properties of the aggregates were studied. Calculated absorption, linear dichroism, and polarization dependent fluorescence-excitation spectra of the studied long macrostructures were practically identical, but circular dichroism spectra turned out to be very sensitive to geometry and monomeric transition dipole moment orientations of the aggregates. The simulations for long multiple rod and spiral-type macrostructures, observed in recent high-resolution electron microscopy images (Oostergetel et al., FEBS Lett 581:5435-5439, 2007) gave shapes of circular dichroism spectra observed experimentally for chlorosomes. It was shown that the ratio of total circular dichroism intensity to integrated absorption of the Q(y) transition is a good measure of degree of tubular structures in the chlorosomes. Calculations suggest that the broad Q(y) line width of chlorosomes of sulfur bacteria could be due to (1) different orientations of the transition moment vectors in multi-walled rod structures or (2) a variety of Bchl-aggregate structures in the chlorosomes.

A complex guided spectral transform Lanczos method for studying quantum resonance states

DOE PAGES

Yu, Hua-Gen

2014-12-28

A complex guided spectral transform Lanczos (cGSTL) algorithm is proposed to compute both bound and resonance states including energies, widths and wavefunctions. The algorithm comprises of two layers of complex-symmetric Lanczos iterations. A short inner layer iteration produces a set of complex formally orthogonal Lanczos (cFOL) polynomials. They are used to span the guided spectral transform function determined by a retarded Green operator. An outer layer iteration is then carried out with the transform function to compute the eigen-pairs of the system. The guided spectral transform function is designed to have the same wavefunctions as the eigenstates of the originalmore » Hamiltonian in the spectral range of interest. Therefore the energies and/or widths of bound or resonance states can be easily computed with their wavefunctions or by using a root-searching method from the guided spectral transform surface. The new cGSTL algorithm is applied to bound and resonance states of HO₂, and compared to previous calculations.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Richer, Michael G.; Suárez, Genaro; López, José Alberto

We present spectroscopic observations of the C ii λ 6578 permitted line for 83 lines of sight in 76 planetary nebulae at high spectral resolution, most of them obtained with the Manchester Echelle Spectrograph on the 2.1 m telescope at the Observatorio Astronómico Nacional on the Sierra San Pedro Mártir. We study the kinematics of the C ii λ 6578 permitted line with respect to other permitted and collisionally excited lines. Statistically, we find that the kinematics of the C ii λ 6578 line are not those expected if this line arises from the recombination of C{sup 2+} ions ormore » the fluorescence of C{sup +} ions in ionization equilibrium in a chemically homogeneous nebular plasma, but instead its kinematics are those appropriate for a volume more internal than expected. The planetary nebulae in this sample have well-defined morphology and are restricted to a limited range in H α line widths (no large values) compared to their counterparts in the Milky Way bulge; both these features could be interpreted as the result of young nebular shells, an inference that is also supported by nebular modeling. Concerning the long-standing discrepancy between chemical abundances inferred from permitted and collisionally excited emission lines in photoionized nebulae, our results imply that multiple plasma components occur commonly in planetary nebulae.« less

Detection of High-Frequency Oscillations and Damping from Multi-slit Spectroscopic Observations of the Corona

NASA Astrophysics Data System (ADS)

Samanta, T.; Singh, J.; Sindhuja, G.; Banerjee, D.

2016-01-01

During the total solar eclipse of 11 July 2010, multi-slit spectroscopic observations of the solar corona were performed from Easter Island, Chile. To search for high-frequency waves, observations were taken at a high cadence in the green line at 5303 Å that is due to [Fe xiv] and the red line at 6374 Å that is due to [Fe x]. The data were analyzed to study the periodic variations in intensity, Doppler velocity, and line width using wavelet analysis. The data with high spectral and temporal resolution enabled us to study the rapid dynamical changes within coronal structures. We find that at certain locations, each parameter shows significant oscillation with periods ranging from 6 - 25 s. For the first time, we were able to detect damping of high-frequency oscillations with periods of about 10 s. If the observed damped oscillations are due to magnetohydrodynamic waves, then they can contribute significantly to the heating of the corona. From a statistical study we try to characterize the nature of the observed oscillations while considering the distribution of power in different line parameters.

OBSERVATIONAL DETECTION OF DRIFT VELOCITY BETWEEN IONIZED AND NEUTRAL SPECIES IN SOLAR PROMINENCES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khomenko, Elena; Collados, Manuel; Díaz, Antonio J., E-mail: khomenko@iac.es, E-mail: mcv@iac.es, E-mail: aj.diaz@uib.es

2016-06-01

We report the detection of differences in the ion and neutral velocities in prominences using high-resolution spectral data obtained in 2012 September at the German Vacuum Tower Telescope (Observatorio del Teide, Tenerife). A time series of scans of a small portion of a solar prominence was obtained simultaneously with high cadence using the lines of two elements with different ionization states, namely, Ca ii 8542 Å and He i 10830 Å. The displacements, widths, and amplitudes of both lines were carefully compared to extract dynamical information about the plasma. Many dynamical features are detected, such as counterstreaming flows, jets, andmore » propagating waves. In all of the cases, we find a very strong correlation between the parameters extracted from the lines of both elements, confirming that both lines trace the same plasma. Nevertheless, we also find short-lived transients where this correlation is lost. These transients are associated with ion-neutral drift velocities of the order of several hundred m s{sup −1}. The patches of non-zero drift velocity show coherence in time–distance diagrams.« less

Calibration of the OHREX high-resolution imaging crystal spectrometer at the Livermore electron beam ion traps [Calibration of the OHREX high-resolution imaging crystal spectrometer at the Livermore EBIT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hell, N.; Beiersdorfer, P.; Magee, E. W.

2016-08-04

Here, we report the calibration of the Orion High-Resolution X-ray (OHREX) imaging crystal spectrometer at the EBIT-I electron beam ion trap at Livermore. Two such instruments, dubbed OHREX-1 and OHREX-2, are fielded for plasma diagnostics at the Orion laser facility in the United Kingdom. The OHREX spectrometer can simultaneously house two spherically bent crystals with a radius of curvature of r=67.2 cm. The focusing properties of the spectrometer allow both for larger distance to the source due to the increase in collected light and for observation of extended sources. OHREX is designed to cover a 2.5–3 degree spectral range atmore » Bragg angles around 51.3 degree. The typically high resolving powers at these large Bragg angles are ideally suited for line shape diagnostics. For instance, the nominal resolving power of the instrument (> 10000) is much higher than the effective resolving power associated with the Doppler broadening due to the temperature of the trapped ions in EBIT-I. The effective resolving power is only around 3000 at typical EBIT-I conditions, which nevertheless is sufficient to set up and test the instrument’s spectral characteristics. We have calibrated the spectral range for a number of crystals using well known reference lines in first and second order, and derived the ion temperatures from these lines. We have also made use of the 50µm size of the EBIT-I source width to characterize the spatial focusing of the spectrometer.« less

Small-scale swirl events in the quiet Sun chromosphere

NASA Astrophysics Data System (ADS)

Wedemeyer-Böhm, S.; Rouppe van der Voort, L.

2009-11-01

Context: Recent progress in instrumentation enables solar observations with high resolution simultaneously in the spatial, temporal, and spectral domains. Aims: We use such high-resolution observations to study small-scale structures and dynamics in the chromosphere of the quiet Sun. Methods: We analyse time series of spectral scans through the Ca ii 854.2 nm spectral line obtained with the CRISP instrument at the Swedish 1-m Solar Telescope. The targets are quiet Sun regions inside coronal holes close to disc-centre. Results: The line core maps exhibit relatively few fibrils compared to what is normally observed in quiet Sun regions outside coronal holes. The time series show a chaotic and dynamic scene that includes spatially confined “swirl” events. These events feature dark and bright rotating patches, which can consist of arcs, spiral arms, rings or ring fragments. The width of the fragments typically appears to be of the order of only 0.2 arcsec, which is close to the effective spatial resolution. They exhibit Doppler shifts of -2 to -4 km s-1 but sometimes up to -7 km s-1, indicating fast upflows. The diameter of a swirl is usually of the order of 2´´. At the location of these swirls, the line wing and wide-band maps show close groups of photospheric bright points that move with respect to each other. Conclusions: A likely explanation is that the relative motion of the bright points twists the associated magnetic field in the chromosphere above. Plasma or propagating waves may then spiral upwards guided by the magnetic flux structure, thereby producing the observed intensity signature of Doppler-shifted ring fragments. The movie is only available in electronic form at http://www.aanda.org Marie Curie Intra-European Fellow of the European Commission.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bai, X. Y.; Liu, S. Q.; Su, J. T.

We report a subarcsecond penumbral transient brightening event with the high-spatial resolution observations from the 1.6 m New Solar Telescope (NST), Interface Region Imaging Spectrograph ( IRIS ), and the Solar Dynamics Observatory . The transient brightening, whose thermal energy is in the range of nanoflares, has signatures in the chromosphere, the transient region, and the corona. NST's H α channel reveals the fine structure of the event with a width as narrow as 101 km (0.″14), which is much smaller than the width from the previous observation. The transient brightening lasts for about 3 minutes. It is associated withmore » a redshift of about 17 km s{sup −1}, found in the Si iv 1402.77 Å line and exhibits an inward motion to the umbra with a speed of 87 km s{sup −1}. The small-scale energy released from the event has a multi-temperature component. Spectral analysis of the brightening region from IRIS shows that not only the transition region lines such as Si iv 1402.77 Å and C ii 1334.53 Å, but also the chromospheric Mg ii k 2796.35 Å line are significantly enhanced and broadened. In addition, the event can be found in all the extreme-ultraviolet passbands of the Atmospheric Imaging Assembly and the derived differential emission measure profile increases between 4 and 15 MK (or 6.6 ≤ log T ≤ 7.2) in the transient brightening phase. It is possible that the penumbral transient brightening event is caused by magnetic reconnection.« less

Evaluating and improving the redshifts of z > 2.2 quasars

NASA Astrophysics Data System (ADS)

Mason, Michelle; Brotherton, Michael S.; Myers, Adam

2017-08-01

Quasar redshifts require the best possible precision and accuracy for a number of applications, such as setting the velocity scale for outflows as well as measuring small-scale quasar-quasar clustering. The most reliable redshift standard in luminous quasars is arguably the narrow [O III] λλ4959, 5007 emission line doublet in the rest-frame optical. We use previously published [O III] redshifts obtained using near-infrared spectra in a sample of 45 high-redshift (z > 2.2) quasars to evaluate redshift measurement techniques based on rest-frame ultraviolet spectra. At redshifts above z = 2.2, the Mg II λ2798 emission line is not available in observed-frame optical spectra and the most prominent unblended and unabsorbed spectral feature available is usually C IV λ1549. Peak and centroid measurements of the C IV profile are often blueshifted relative to the rest-frame of the quasar, which can significantly bias redshift determinations. We show that redshift determinations for these high-redshift quasars are significantly correlated with the emission-line properties of C IV (I.e. the equivalent width, or EW, and the full width at half-maximum, or FWHM) as well as the luminosity, which we take from the Sloan Digital Sky Survey Data Release 7. We demonstrate that empirical corrections based on multiple regression analyses yield significant improvements in both the precision and accuracy of the redshifts of the most distant quasars and are required to establish consistency with redshifts determined in more local quasars.

Uncertainty Analysis of Air Radiation for Lunar Return Shock Layers

NASA Technical Reports Server (NTRS)

Kleb, Bil; Johnston, Christopher O.

2008-01-01

By leveraging a new uncertainty markup technique, two risk analysis methods are used to compute the uncertainty of lunar-return shock layer radiation predicted by the High temperature Aerothermodynamic Radiation Algorithm (HARA). The effects of epistemic uncertainty, or uncertainty due to a lack of knowledge, is considered for the following modeling parameters: atomic line oscillator strengths, atomic line Stark broadening widths, atomic photoionization cross sections, negative ion photodetachment cross sections, molecular bands oscillator strengths, and electron impact excitation rates. First, a simplified shock layer problem consisting of two constant-property equilibrium layers is considered. The results of this simplified problem show that the atomic nitrogen oscillator strengths and Stark broadening widths in both the vacuum ultraviolet and infrared spectral regions, along with the negative ion continuum, are the dominant uncertainty contributors. Next, three variable property stagnation-line shock layer cases are analyzed: a typical lunar return case and two Fire II cases. For the near-equilibrium lunar return and Fire 1643-second cases, the resulting uncertainties are very similar to the simplified case. Conversely, the relatively nonequilibrium 1636-second case shows significantly larger influence from electron impact excitation rates of both atoms and molecules. For all cases, the total uncertainty in radiative heat flux to the wall due to epistemic uncertainty in modeling parameters is 30% as opposed to the erroneously-small uncertainty levels (plus or minus 6%) found when treating model parameter uncertainties as aleatory (due to chance) instead of epistemic (due to lack of knowledge).

Subsonic islands within a high-mass star-forming infrared dark cloud

NASA Astrophysics Data System (ADS)

Sokolov, Vlas; Wang, Ke; Pineda, Jaime E.; Caselli, Paola; Henshaw, Jonathan D.; Barnes, Ashley T.; Tan, Jonathan C.; Fontani, Francesco; Jiménez-Serra, Izaskun; Zhang, Qizhou

2018-03-01

High-mass star forming regions are typically thought to be dominated by supersonic motions. We present combined Very Large Array and Green Bank Telescope (VLA+GBT) observations of NH3 (1,1) and (2,2) in the infrared dark cloud (IRDC) G035.39-00.33, tracing cold and dense gas down to scales of 0.07 pc. We find that, in contrast to previous, similar studies of IRDCs, more than a third of the fitted ammonia spectra show subsonic non-thermal motions (mean line width of 0.71 km s-1), and sonic Mach number distribution peaks around ℳ = 1. As possible observational and instrumental biases would only broaden the line profiles, our results provide strong upper limits to the actual value of ℳ, further strengthening our findings of narrow line widths. This finding calls for a re-evaluation of the role of turbulent dissipation and subsonic regions in massive-star and cluster formation. Based on our findings in G035.39, we further speculate that the coarser spectral resolution used in the previous VLA NH3 studies may have inhibited the detection of subsonic turbulence in IRDCs. The reduced turbulent support suggests that dynamically important magnetic fields of the 1 mG order would be required to support against possible gravitational collapse. Our results offer valuable input into the theories and simulations that aim to recreate the initial conditions of high-mass star and cluster formation.

Role of the He I and He II metastables in the resonance 2p 2P°1/2, 3/2 B III level population

NASA Astrophysics Data System (ADS)

Djeniže, S.; Srećković, A.; Bukvić, S.

2007-01-01

Aims:The aim of this work is to present atomic processes which lead to an extra population of the 2p ~^2P°1/2, 3/2 B III resonance levels in helium plasma generating intense radiation in the B III 206.578 nm and 206.723 nm lines. Methods: The line profiles were recorded using a step-by-step (7.3 pm) technique which provides monitoring of the line shapes continually during the plasma decay and gives the possibility to compare line shapes at various times in the same plasma. Results: On the basis of the line intensity decays of the doubly ionized boron resonance spectral lines in laboratory nitrogen and helium plasmas, we have found the existence of a permanent energy transfer from He I and He II metastables to the 2p ^2P°1/2, 3/2 B III resonance levels. The shapes of the mentioned lines are also observed. At electron temperatures of about 18 000 K and electron densities about 1.1× 1023 m-3, the Stark broadening was found as a main B III line broadening mechanism. The measured Stark widths (W) are compared with the Doppler width (W_D) and with the splitting in the hyperfine structure (Δ_hfs). Our measured W data are found to be much higher than results obtained by means of various theoretical approaches. Conclusions: . The He I and He II metastables over populate the B III resonance levels leading to populations higher than predicted by LTE model. Consequently, the emitted B III resonance lines are more intense than expected from LTE model. This fact can be of importance if B III resonance line intensities are used for abundance determination purposes in astrophysics. Similar behavior can be expected for some lines emitted by astrophysical interesting emitters: Al III, Si III, Sc III, Cr III, V III, Ti III, Fe III, Co III, Ni III, Ga III, Zr III, Y III, Nb III, In III, Sn III, Sb III, Au III, Pb III and Bi III in hot and dense helium plasmas.

Neonatal line width in deciduous incisors from Neolithic, mediaeval and modern skeletal samples from north-central Poland.

PubMed

Kurek, Marta; Żądzińska, Elżbieta; Sitek, Aneta; Borowska-Strugińska, Beata; Rosset, Iwona; Lorkiewicz, Wiesław

2016-01-01

The neonatal line is usually the first accentuated incremental line visible on the enamel. The prenatal environment significantly contributes to the width of the neonatal line, influencing the pace of reaching post-delivery homeostasis by the newborn's organism. Studies of the enamel of the earliest developing deciduous teeth can provide an insight into the prenatal development and the perinatal conditions of children of past human populations, thus being an additional source contributing to consideration of the influence of prenatal and perinatal factors modifying growth processes. The aim of this study was to examine whether the neonatal line, reflecting the conditions of the prenatal and perinatal environment, differed between the Neolithic, the mediaeval and the modern populations from the Kujawy region in north-central Poland. The material consisted of longitudinally ground sections of 57 human deciduous incisors obtained from children aged 1.0-7.5 years representing three archaeological series from Brześć Kujawski site. All teeth were sectioned in the labio-linqual plane using a diamond blade (Buechler IsoMet 1000). Final specimens were observed with the microscope Delta Optical Evolution 300 at 10× and 40× magnifications. For each tooth, linear measurements of the neonatal line width were performed on its labial surface at the three levels from the cemento-enamel junction. No significant difference was found in the mean neonatal line width depending on the tooth type and archaeological site, although the thickest neonatal line characterised children from the Neolithic series. In all analysed series, the neonatal line width was diversified depending on the child's age at death. The value of Spearman's rank correlation coefficient calculated for the correlation between the child's age at death and the neonatal line width was statistically significant. A clear increase in the width of the neonatal line was thus observed along with a decrease in the child's age at death. Copyright © 2015 Elsevier GmbH. All rights reserved.

Shell stability and conditions analyzed using a new method of extracting shell areal density maps from spectrally resolved images of direct-drive inertial confinement fusion implosions

DOE PAGES

Johns, H. M.; Mancini, R. C.; Nagayama, T.; ...

2016-01-25

In warm target direct-drive inertial confinement fusion implosion experiments performed at the OMEGA laser facility, plastic micro-balloons doped with a titanium tracer layer in the shell and filled with deuterium gas were imploded using a low-adiabat shaped laser pulse. Continuum radiation emitted in the core is transmitted through the tracer layer and the resulting spectrum recorded with a gated multi-monochromatic x-ray imager (MMI). Titanium K-shell line absorption spectra observed in the data are due to transitions in L-shell titanium ions driven by the backlighting continuum. The MMI data consist of an array of spectrally resolved images of the implosion. Thesemore » 2-D space-resolved titanium spectral features constrain the plasma conditions and areal density of the titanium doped region of the shell. The MMI data were processed to obtain narrow-band images and space resolved spectra of titanium spectral features. Shell areal density maps, ρL(x,y), extracted using a new method using both narrow-band images and space resolved spectra are confirmed to be consistent within uncertainties. We report plasma conditions in the titanium-doped region of electron temperature (Te) = 400 ± 28 eV, electron number density (N e) = 8.5 × 10 24 ± 2.5 × 10 24 cm –3, and average areal density = 86 ± 7 mg/cm 2. Fourier analysis of areal density maps reveals shell modulations caused by hydrodynamic instability growth near the fuel-shell interface in the deceleration phase. We observe significant structure in modes l = 2–9, dominated by l = 2. We extract a target breakup fraction of 7.1 ± 1.5% from our Fourier analysis. Furthermore, a new method for estimating mix width is evaluated against existing literature and our target breakup fraction. We estimate a mix width of 10.5 ±1 μm.« less

High Resolution Optical Spectroscopy of the Classical Nova V5668 Sgr Showing the Presence of Lithium

NASA Astrophysics Data System (ADS)

Wagner, R. Mark; Woodward, Charles E.; Starrfield, Sumner; Ilyin, Ilya; Strassmeier, Klaus

2018-01-01

The classical nova (CN) V5668 Sgr was discovered on 2015 March 15.634 and initial optical spectra implied it was an Fe II-class CN. We obtained high resolution optical spectroscopy on 30 nights between 2015 April 3 and 2016 June 5 with the 2 x 8.4 m Large Binocular Telescope (LBT) and the 1.8 m Vatican Advanced Technology Telescope (VATT) using the Potsdam Echelle Polarimetric Spectroscopic Instrument (PEPSI). The spectra cover all or part of the 3830-9065 Å spectral region at a spectral resolution of up to 270,000 (1 km/s); the highest resolution currently available on any 8-10 m class telescope. The early spectra are dominated by emission lines of the Balmer and Paschen series of hydrogen, Fe II, Ca II, and Na I with P Cyg-type line profiles as well as emission lines of [O I]. Numerous interstellar lines and bands are readily apparent at high spectral resolution. The permitted line profiles show complex and dramatic variations in the multi-component P Cyg-type line profiles with time. We detect a weak blue-shifted absorption line at a velocity consistent with Li I 6708 Å when compared with the line profiles of Hβ, Fe II 5169 Å, and Na I D. This line is present in spectra obtained on 7 of 8 consecutive nights up to day 21 of the outburst; but absent on day 42 when it is evident that the ionization of the ejecta has significantly increased. The equivalent width of the line converted to a column density, and the resulting mass fraction, imply a significant enrichment of 7Li in the ejecta. 7Li is produced by the decay of unstable 7Be created during the thermonuclear runaway. The discovery of the resonance lines of 7Be II in the optical spectra of the recent CNe V339 Del, V2944 Oph, and V5668 Sgr by Tajitsu et al. (2016) and its subsequent decay to 7Li (half life of 53 days) suggests a significant enrichment of 7Li in the Galaxy from CNe is possible. Our observations of the Li I 6708 Å line in the early optical spectra of V5668 Sgr mark the second direct detection of Li in a CN following the detection of Li I in the early optical spectra of V1369 Cen by Izzo et al. (2015). SS acknowledges partial support from NSF and NASA grants to ASU. CEW acknowledges support from NASA.

Determination of natural line widths of Kα X-ray lines for some elements in the atomic range 50≤Z≤65 at 59.5 keV

NASA Astrophysics Data System (ADS)

Kündeyi, Kadriye; Aylıkcı, Nuray Küp; Tıraşoǧlu, Engin; Kahoul, Abdelhalim; Aylıkcı, Volkan

2017-02-01

The semi-empirical determination of natural widths of Kα X-ray lines (Kα1 and Kα2) were performed for Sn, Sb, Te, I, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd and Tb. For the semi-empirical determination of the line widths, K shell fluorescence yields of elements were measured. The samples were excited by 59.5 keV γ rays from a 241Am annular radioactive source in order to measure the K shell fluorescence yields. The emitted K X-rays from the samples were counted by an Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV. The measured K shell fluorescence yields were used for the calculation of K shell level widths. Finally, the natural widths of K X-ray lines were determined as the sums of levels which involved in the transition. The obtained values were compared with earlier studies.

Improvement of contact grating device for efficient terahertz wave generation using bi-angular filter

NASA Astrophysics Data System (ADS)

Nagashima, Keisuke; Tsubouchi, Masaaki; Ochi, Yoshihiro; Maruyama, Momoko

2018-03-01

We have proposed an improved contact grating device for generating terahertz waves efficiently and have succeeded in developing the device with a very high diffraction efficiency and a wide spectral width. This device has a bi-angular filter and a Fabry-Perot-type structure, which are composed of dielectric multilayers. The bi-angular filter is designed to reflect the 0th-order wave and transmit the-1st-order diffraction wave. Numerical calculations indicate that the new device has a maximum diffraction efficiency over 99% and a spectral width of approximately 20 nm. We measured a high efficiency of 90% over a broad spectral range using a fabricated device.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen Weicheng; Chen Guojie; Han Dingan

A fibre laser with a SESAM as a passive mode-locker is constructed for obtaining a vector soliton with the Kelly sidebands. The analysis of the peculiarities of the sidebands shows that the polarisation states are nonuniform across the entire pulse spectral profile from the leading edge to the trailing edge. Polarisation filtering effect is proposed to obtain a vector soliton with a uniform polarisation state. It is shown that during the polarisation filtering by a polariser incorporated into the laser cavity, the spectral width of the vector solitons gradually broadens and the pulse power decreases. It is found that atmore » a maximum spectral width and a minimum pulse power, vector solitons with a uniform polarisation state are generated. (nonlinear optical phenomena)« less

Velocity-resolved observations of water in Comet Halley

NASA Technical Reports Server (NTRS)

Larson, Harold P.; Davis, D. Scott; Mumma, Michael J.; Weaver, Harold A.

1986-01-01

High resolution (lambda/delta lambda approx. = 3 x 10 to the 5th power) near-infrared observations of H2O emission from Comet Halley were acquired at the time of maximum post-perihelion geocentric Doppler shift. The observed widths and absolute positions of the H2O line profiles reveal characteristics of the molecular velocity field in the coma. These results support H2O outflow from a Sun-lit hemisphere or the entire nucleus, but not from a single, narrow jet emanating from the nucleus. The measured pre- and post-perihelion outflow velocities were 0.9 + or - 0.2 and 1.4 + or - 0.2 km/s, respectively. Temporal variations in the kinematic properties of the outflow were inferred from changes in the spectral line shapes. These results are consistent with the release of H2O into the coma from multiple jets.

Nova V2362 Cygni (Nova Cygni 2006): Spitzer, Swift, and Ground-Based Spectral Evolution

NASA Technical Reports Server (NTRS)

Lynch, David K.; Venturini, Catherine C.; Mazuk, S.; Woodward, Charles; Gehrz, Robert; Rayner, John; Helton, L.A.; Ness, Jan-Uwe; Starrfield, Sumner; Rudy, Richard J.;

High Spectral Resolution SOFIA/EXES Observations of C2H2 toward Orion IRc2

NASA Astrophysics Data System (ADS)

Rangwala, Naseem; Colgan, Sean W. J.; Le Gal, Romane; Acharyya, Kinsuk; Huang, Xinchuan; Lee, Timothy J.; Herbst, Eric; deWitt, Curtis; Richter, Matt; Boogert, Adwin; McKelvey, Mark

2018-03-01

We present high spectral resolution observations from 12.96 to 13.33 microns toward Orion IRc2 using the mid-infrared spectrograph, Echelon-Cross-Echelle Spectrograph (EXES), at Stratospheric Observatory for Infrared Astronomy (SOFIA). These observations probe the physical and chemical conditions of the Orion hot core, which is sampled by a bright, compact, mid-infrared background continuum source in the region, IRc2. All 10 of the rovibrational C2H2 transitions expected in our spectral coverage are detected with high signal-to-noise ratios (S/Ns), yielding continuous coverage of the R-branch lines from J = 9–8 to J = 18–17, including both ortho and para species. Eight of these rovibrational transitions are newly reported detections. The isotopologue, 13CCH2, is clearly detected with a high S/N. This enabled a direct measurement of the 12C/13C isotopic ratio for the Orion hot core of 14 ± 1 and an estimated maximum value of 21. We also detected several HCN rovibrational lines. The ortho and para C2H2 ladders are clearly separate, and tracing two different temperatures, 226 K and 164 K, respectively, with a non-equilibrium ortho to para ratio (OPR) of 1.7 ± 0.1. Additionally, the ortho and para V LSR values differ by about 1.8 ± 0.2 km s‑1, while the mean line widths differ by 0.7 ± 0.2 km s‑1, suggesting that these species are not uniformly mixed along the line of sight to IRc2. We propose that the abnormally low C2H2 OPR could be a remnant from an earlier, colder phase, before the density enhancement (now the hot core) was impacted by shocks generated from an explosive event 500 years ago.

Characterization of KCNE1 inside Lipodisq Nanoparticles for EPR Spectroscopic Studies of Membrane Proteins.

PubMed

Sahu, Indra D; Zhang, Rongfu; Dunagan, Megan M; Craig, Andrew F; Lorigan, Gary A

2017-06-01

EPR spectroscopic studies of membrane proteins in a physiologically relevant native membrane-bound state are extremely challenging due to the complexity observed in inhomogeneity sample preparation and dynamic motion of the spin-label. Traditionally, detergent micelles are the most widely used membrane mimetics for membrane proteins due to their smaller size and homogeneity, providing high-resolution structure analysis by solution NMR spectroscopy. However, it is often difficult to examine whether the protein structure in a micelle environment is the same as that of the respective membrane-bound state. Recently, lipodisq nanoparticles have been introduced as a potentially good membrane mimetic system for structural studies of membrane proteins. However, a detailed characterization of a spin-labeled membrane protein incorporated into lipodisq nanoparticles is still lacking. In this work, lipodisq nanoparticles were used as a membrane mimic system for probing the structural and dynamic properties of the integral membrane protein KCNE1 using site-directed spin labeling EPR spectroscopy. The characterization of spin-labeled KCNE1 incorporated into lipodisq nanoparticles was carried out using CW-EPR titration experiments for the EPR spectral line shape analysis and pulsed EPR titration experiment for the phase memory time (T m ) measurements. The CW-EPR titration experiment indicated an increase in spectral line broadening with the addition of the SMA polymer which approaches close to the rigid limit at a lipid to polymer weight ratio of 1:1, providing a clear solubilization of the protein-lipid complex. Similarly, the T m titration experiment indicated an increase in T m values with the addition of SMA polymer and approaches ∼2 μs at a lipid to polymer weight ratio of 1:2. Additionally, CW-EPR spectral line shape analysis was performed on six inside and six outside the membrane spin-label probes of KCNE1 in lipodisq nanoparticles. The results indicated significant differences in EPR spectral line broadening and a corresponding inverse central line width between spin-labeled KCNE1 residues located inside and outside of the membrane for lipodisq nanoparticle samples when compared to lipid vesicle samples. These results are consistent with the solution NMR structure of KCNE1. This study will be beneficial for researchers working on studying the structural and dynamic properties of membrane proteins.

Time scale variations of the CIV resonance lines in HD 24534

NASA Astrophysics Data System (ADS)

Tsatsi, A.

2012-01-01

Many lines in the spectra of hot emission stars (Be and Oe) present peculiar and very complex profiles. As a result we can not find a classical theoretical distribution to fit these physical profiles; hence many physical parameters of the regions where these lines are created are difficult to be determined. In this paper, we adopt the Gauss-Rotation model (GR-model), that proposed the idea that these complex profiles consist of a number of independent Discrete or Satellite Absorption Components (DACs, SACs). The model is applied for CIV (λλ 1548.187, 1550.772 A) resonance lines in the spectra of HD 24534 (X Persei), taken by I.U.E. at three different periods. From this analysis we can calculate the values of a group of physical parameters, such as the apparent rotational and radial velocities, the random velocities of the thermal motions of the ions, as well as the Full Width at Half Maximum (FWHM) and the absorbed energy of the independent regions of matter which produce the main and the satellite components of the studied spectral lines. Finally, we calculate the time scale variation of the above physical parameters.

Stark broadening of Ca IV spectral lines of astrophysical interest

NASA Astrophysics Data System (ADS)

Alonso-Medina, A.; Colón, C.

2014-12-01

Ca IV emission lines are under the preview of Solar Ultraviolet Measurements of Emitted Radiation device aboard the Solar and Heliospheric Observatory. Also, lines of the Ca IV in planetary nebulae NGC 7027 were detected with the Short Wavelength Spectrometer on board the Infrared Space Observatory. These facts justify an attempt to provide new spectroscopic parameters of Ca IV. There are no theoretical or experimental Stark broadening data for Ca IV. Using the Griem semi-empirical approach and the COWAN code, we report in this paper calculated values of the Stark broadening parameters for 467 lines of Ca IV. They were calculated using a set of wavefunctions obtained by using Hartree-Fock relativistic calculations. These lines arising from 3s23p4ns (n = 4, 5), 3s23p44p, 3s23p4nd (n = 3, 4) configurations. Stark widths and shifts are presented for an electron density of 1017 cm-3 and temperatures T = 10 000, 20 000 and 50 200 K. As these data cannot be compared to others in the literature, we present an analysis of the different regularities of the values presented in this work.

VizieR Online Data Catalog: ALMA survey of Lupus protoplanetary disks. I. (Ansdell+, 2016)

NASA Astrophysics Data System (ADS)

Ansdell, M.; Williams, J. P.; van der Marel, N.; Carpenter, J. M.; Guidi, G.; Hogerheijde, M.; Mathews, G. S.; Manara, C. F.; Miotello, A.; Natta, A.; Oliveira, I.; Tazzari, M.; Testi, L.; van Dishoeck, E. F.; van Terwisga, S. E.

2016-11-01

Our ALMA Cycle 2 observations (Project ID: 2013.1.00220.S) were obtained on 2015 June 14 (AGK-type sources and unknown spectral types) and 2015 June 15 (M-type sources). The continuum spectral windows were centered on 328.3, 340.0, and 341.8GHz with bandwidths of 1.875, 0.938, and 1.875 GHz and channel widths of 15.625, 0.244, and 0.977MHz, respectively. The bandwidth-weighted mean continuum frequency was 335.8GHz (890um). The spectral setup included two windows covering the 13CO and C18O 3-2 transitions; these spectral windows were centered on 330.6 and 329.3GHz, respectively, with bandwidths of 58.594MHz, channel widths of 0.122MHz, and velocity resolutions of 0.11km/s. (3 data files).

Line Parameters of Carbon Dioxide in the 4850 CM-1 Region

NASA Astrophysics Data System (ADS)

Benner, D. Chris; Devi, V. Malathy; Nugent, Emily; Sung, Keeyoon; Brown, Linda R.; Miller, Charles E.; Toth, Robert A.

2011-06-01

The spectral region near 4850 Cm-1 is used to monitor atmospheric carbon dioxide, but current accuracies of the line intensities and line shape coefficients do not permit carbon dioxide mixing ratios to be obtained to 1 ppm (about one part in 400). To improve the line parameters, we are remeasuring the prominent CO2 bands in this region specifically to characterize the non-Voigt effects of line mixing and speed dependence at room temperature. The laboratory spectra of air- and self-broadened CO2 have been recorded at a variety of pressures, path lengths, mixing ratios and resolutions (0.005 to 0.01 Cm-1) with two different Fourier transform spectrometers (the McMath-Pierce FTS at Kitt Peak and a Bruker 125 HR FTS at JPL). The line parameters of some 2000 transitions are being derived by simultaneous multispectrum fitting using a few dozen spectra encompassing a 230 Cm-1 wide spectral interval. The rovibrational constants for line positions and the band intensities and Herman-Wallis coefficients are being retrieved directly from the spectra, rather than floating positions and intensities individually. Self and foreign Lorentz widths and pressure shifts are being determined for the stronger bands while non-Voigt coefficients describing line mixing and speed dependence are being obtained for at least one of the strongest bands. D. Chris Benner, C. P. Rinsland, V. M. Devi, M. A. H. Smith, and D. A. Atkins, JQSRT 1995;53:705-21. V. M. Devi, D. Chris Benner, L. R. Brown, C. E. Miller, and R. A. Toth, J. Mol. Spectrosc. 2007;245:52-80. Part of the research described in this paper was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contracts and cooperative agreements with the National Aeronautics and Space Administration. Support for the work at William and Mary was provided by contracts with JPL.

Excess Hα emission in chromospherically active binaries.

NASA Astrophysics Data System (ADS)

Montes, D.; Fernandez-Figueroa, M. J.; de Castro, E.; Cornide, M.

1995-02-01

We study the behaviour of the excess Hα emission in a sample of 51 chromospherically active binary systems (RS CVn and BY Dra classes), of different activity levels. This sample include the 27 stars analysed by Fernandez-Figueroa et al. (1994) and the new observations of 24 systems described by Montes et al. (1994b). By using the spectral subtraction technique (subtraction of a synthesized stellar spectrum constructed from reference stars of similar spectral type and luminosity class) we obtain the active-chromosphere contribution to the Hα line in these 51 systems. We have determined the excess Hα emission equivalent widths and converted it to surface fluxes. The Hα emissions arising from each component star were obtained when it was possible to deblend both contributions. The comparison of the excess Hα emission, obtained with the spectral subtraction technique, with other Hα activity indices allows us to conclude that this is the preferable activity indicator for binaries. The behaviour of the excess Hα emission as a function of the rotation has been analyzed. A slight decline toward longer rotational periods, P_rot_, and larger Rossby numbers, R_0_, is present in agreement with previous results using others activity indicators. We have compared the derived excess Hα emission fluxes with those obtained in the Ca II K and Hɛ lines finding that a good correlation exits between these three chromospheric activity indicators. The Hα losses seem to be more important than Ca II K losses for cooler stars, in fact all the system with Hα emission above the continuum are cooler than 5000K. Correlations with other activity indicators, (C IV in the transition region, and X-rays in the corona) indicate that the exponents of the power-law relations increase with the formation temperature of the spectral features.

Water absorption lines, 931-961 nm - Selected intensities, N2-collision-broadening coefficients, self-broadening coefficients, and pressure shifts in air

NASA Technical Reports Server (NTRS)

Giver, L. P.; Gentry, B.; Schwemmer, G.; Wilkerson, T. D.

1982-01-01

Intensities were measured for 97 lines of H2O vapor between 932 and 961 nm. The lines were selected for their potential usefulness for remote laser measurements of H2O vapor in the earth's atmosphere. The spectra were obtained with several different H2O vapor abundances and N2 broadening gas pressures; the spectral resolution was 0.046/cm FWHM. Measured H2O line intensities range from 7 x 10 to the -25th to 7 x 10 to the -22nd/cm per (molecules/sq cm). H2O self-broadening coefficients were measured for 13 of these strongest lines; the mean value was 0.5/cm per atm. N2-collision-broadening coefficients were measured for 73 lines, and the average was 0.11 cm per atm HWHM. Pressure shifts in air were determined for a sample of six lines between 948 and 950 nm; these lines shift to lower frequency by an amount comparable to 0.1 of the collision-broadened widths measured in air or N2. The measured intensities of many lines of 300-000 band are much larger than expected from prior computations, in some cases by over an order of magnitude. Coriolis interactions with the stronger 201-000 band appear to be the primary cause of the enhancement of these line intensities.

Long-term spectroscopic monitoring of the Luminous Blue Variable AG Carinae

NASA Astrophysics Data System (ADS)

Stahl, O.; Jankovics, I.; Kovács, J.; Wolf, B.; Schmutz, W.; Kaufer, A.; Rivinius, Th.; Szeifert, Th.

2001-08-01

We have extensively monitored the Luminous Blue Variable AG Car (HD 94910) spectroscopically. Our data cover the years 1989 to 1999. In this period, the star underwent almost a full S Dor cycle from visual minimum to maximum and back. Over several seasons, up to four months of almost daily spectra are available. Our data cover most of the visual spectral range with a high spectral resolution (lambda /Delta lambda ~ 20 000). This allows us to investigate the variability in many lines on time scales from days to years. The strongest variability occurs on a time scale of years. Qualitatively, the variations can be understood as changes of the effective temperature and radius, which are in phase with the optical light curve. Quantitatively, there are several interesting deviations from this behaviour, however. The Balmer lines show P Cygni profiles and have their maximum strength (both in equivalent width and line flux) after the peak of the optical light curve, at the descending branch of the light curve. The line-width during maximum phase is smaller than during minimum, but it has a local maximum close to the peak of the visual light curve. We derive mass-loss rates over the cycle from the Hα line and find the highest mass loss rates (log dot {M}/({M}_sun yr-1) ~ -3.8, about a factor of five higher than in the minimum, where we find log dot {M}/({M}_sun yr-1) ~ -4.5) after the visual maximum. Line-splitting is very commonly observed, especially on the rise to maximum and on the descending branch from maximum. The components are very long-lived (years) and are probably unrelated to similar-looking line-splitting events in normal supergiants. Small apparent accelerations of the components are observed. The change in radial velocity could be due to successive narrowing of the components, with the absorption disappearing at small expansion velocities first. In general, the line-splitting is more likely the result of missing absorption at intermediate velocities than of excess absorption at the velocities of the components. The HeI lines and other lines which form deep in the atmosphere show the most peculiar variations. The HeI lines show a central absorption with variable blue- and red-shifted emission components. Due to the variations of the emission components, the HeI lines can change their line profile from a normal P Cyg profile to an inverse P Cyg-profile or double-peak emission. In addition, very broad (+/-1500 km s-1) emission wings are seen at the strongest HeI lines of AG Car. At some phases, a blue-shifted absorption is also present. The central absorption of the HeI lines is blue-shifted before and red-shifted after maximum. Possibly, we directly see the expansion and contraction of the photosphere. If this explanation is correct, the velocity of the continuum-forming layer is not dominated by expansion but is only slightly oscillating around the systemic velocity. Based on observations collected at the European Southern Observatory at La Silla, Chile.

The variability of the Seyfert galaxy NGC 2992: the case for a revived AGN

NASA Astrophysics Data System (ADS)

Gilli, R.; Maiolino, R.; Marconi, A.; Risaliti, G.; Dadina, M.; Weaver, K. A.; Colbert, E. J. M.

2000-03-01

We report the transition to an active state of the nucleus in the Seyfert 1.9 galaxy NGC 2992, discovered by means of new hard X-ray data. While the 2-10 keV flux declined by a factor of ~ 20 from 1978 to 1994, two recent BeppoSAX observations in 1997 and in 1998 caught the nuclear emission raising back to the same level of activity observed in 1978. In both BeppoSAX observations the X-ray spectrum of the source is well represented by a power law with spectral index Gamma =~ 1.7, absorbed by a column density of N_H =~ 1022 cm-2 and characterized by a prominent iron Kalpha line. While in the second BeppoSAX data set the line properties appear to be consistent with those expected from accretion disc models, in the first BeppoSAX data set the iron feature is rather peculiar. The broadening is not significant and the line energy is E_Kalpha =6.62+/-0.07 keV, indicating emission from highly ionized iron. The line has too high equivalent width ( ~ 700 eV) to be produced by a hot scattering medium. By comparing these data with data previously in the literature, we interpret the spectral and flux changes in terms of different phases of rebuilding an accretion disc. The timescale for the disc rebuilding is estimated to range between 1 and 5 years. The X-ray data are complemented with optical and near-infrared followup spectra taken 1.5 months after the discovery of the X-ray burst. The spectra are characterized by prominent broad emission lines. There is also evidence for hot dust emission in the H and K bands that, however, is probably still in the process of increasing.

Laboratory measurements of VUV N2 photoabsorption cross sections and line widths: applications to planetary atmospheric transmission models

NASA Astrophysics Data System (ADS)

Smith, P. L.; Stark, G.; Yoshino, K.

2003-05-01

The analyses of VUV occultation measurements of the N2-rich atmospheres of Titan and Triton are hampered by the lack of fundamental spectroscopic data for N2. There is a need for reliable photoabsorption cross sections and line widths for the 100 electronic bands of N2 in the 80 to 100 nm wavelength region. We present analyses of new measurements of individual line strengths and widths in N2 bands in the region 94 to 100 nm. Within individual bands, we find significant departures from the predicted line strength distributions based on isolated band models. Line width analyses within each band indicate that predissociation-broadening is often highly dependent on the rotational quantum number. We illustrate the importance of N2 line widths in the analysis of occultation measurements via N2 transmission models over selected wavelength regions. We have continued to compile on-line molecular spectroscopic atlas based on our N2 laboratory data: http://cfa-www.harvard.edu/amdata/ampdata/N2ARCHIVE/n2home.html. The archive includes published and unpublished 14N2, 14N15N, and 15N2 line lists and spectroscopic identifications, excited state energy levels, band and line f-values, a summary of published band f-value and line width measurements, and a cross-referenced summary of the relevant N2 literature. The listings are searchable by wavelength interval or band identification and are suitable for down-loading in a convenient format. We gratefully acknowledge funding support from NASA grant NAG5-9059 and the Smithsonian Institution Atherton-Seidell Grant Program.

Ultra-Wideband Optical Modulation Spectrometer (OMS) Development

NASA Technical Reports Server (NTRS)

Gardner, Jonathan (Technical Monitor); Tolls, Volker

2004-01-01

The optical modulation spectrometer (OMS) is a novel, highly efficient, low mass backend for heterodyne receiver systems. Current and future heterodyne receiver systems operating at frequencies up to a few THz require broadband spectrometer backends to achieve spectral resolutions of R approximately 10(exp 5) to 10(exp 6) to carry out many important astronomical investigations. Among these are observations of broad emission and absorption lines from extra-galactic objects at high redshifts, spectral line surveys, and observations of planetary atmospheres. Many of these lines are pressure or velocity broadened with either large half-widths or line wings extending over several GHz. Current backend systems can cover the needed bandwidth only by combining the output of several spectrometers, each with typically up to 1 GHz bandwidth, or by combining several frequency-shifted spectra taken with a single spectrometer. An ultra-wideband optical modulation spectrometer with 10 - 40 GHz bandwidth will enable broadband ob- servations without the limitations and disadvantages of hybrid spectrometers. Spectrometers like the OMS will be important for both ground-based observatories and future space missions like the Single Aperture Far-Infrared Telescope (SAFIR) which might carry IR/submm array heterodyne receiver systems requiring a spectrometer for each array pixel. Small size, low mass and small power consumption are extremely important for space missions. This report summarizes the specifications developed for the OMS and lists already identified commercial parts. The report starts with a review of the principle of operation, then describes the most important components and their specifications which were derived from theory, and finishes with a conclusion and outlook.

Folded inflatable protective device and method for making same

DOEpatents

Behr, V.L.; Nelsen, J.M.; Gwinn, K.W.

1998-10-20

An apparatus and method are disclosed for making an inflatable protective device made of lightweight material that can withstand the initial stress from inflation and enhance radial inflation. The device includes a cushion and an inflator port. The invention further includes several stacks of folded cushion material including a combination of full-width stacks and half-width stacks: a first full-width stack defined by one or more fan folds in a first lateral half of the cushion wherein the folds are substantially centered above a first center line and are substantially over the inflator port; a second full-width stack defined by one or more fan folds in a second lateral half of the cushion wherein the folds are substantially centered above the first center line and substantially over the inflator port in the first full-width stack; a first half-width stack defined by a plurality of fan folds in the bottom of the cushion where neither edge of each fold extends substantially over the second center line; and a second half-width stack defined by a plurality of fan folds in the top of the cushion wherein neither edge of each fold extends substantially over the second center line. 22 figs.

Folded inflatable protective device and method for making same

DOEpatents

Behr, Vance L.; Nelsen, James M.; Gwinn, Kenneth W.

1998-01-01

An apparatus and method for making an inflatable protective device made of lightweight material that can withstand the initial stress from inflation and enhance radial inflation. The device includes a cushion and an inflator port. The invention further includes several stacks of folded cushion material including a combination of full-width stacks and half-width stacks: a first full-width stack defined by one or more fan folds in a first lateral half of the cushion wherein the folds are substantially centered above a first center line and are substantially over the inflator port; a second full-width stack defined by one or more fan folds in a second lateral half of the cushion wherein the folds are substantially centered above the first center line and substantially over the inflator port in the first full-width stack; a first half-width stack defined by a plurality of fan folds in the bottom of the cushion where neither edge of each fold extends substantially over the second center line; and a second half-width stack defined by a plurality of fan folds in the top of the cushion wherein neither edge of each fold extends substantially over the second center line.

Evaluation of spectroscopic databases through radiative transfer simulations compared to observations. Application to the validation of GEISA 2015 with IASI and TCCON

NASA Astrophysics Data System (ADS)

Armante, Raymond; Scott, Noelle; Crevoisier, Cyril; Capelle, Virginie; Crepeau, Laurent; Jacquinet, Nicole; Chédin, Alain

2016-09-01

The quality of spectroscopic parameters that serve as input to forward radiative transfer models are essential to fully exploit remote sensing of Earth atmosphere. However, the process of updating spectroscopic databases in order to provide the users with a database that insures an optimal characterization of spectral properties of molecular absorption for radiative transfer modeling is challenging. The evaluation of the databases content and the underlying choices made by the managing team is thus a crucial step. Here, we introduce an original and powerful approach for evaluating spectroscopic parameters: the Spectroscopic Parameters And Radiative Transfer Evaluation (SPARTE) chain. The SPARTE chain relies on the comparison between forward radiative transfer simulations made by the 4A radiative transfer model and observations of spectra made from various observations collocated over several thousands of well-characterized atmospheric situations. Averaging the resulting 'calculated-observed spectral' residuals minimizes the random errors coming from both the radiometric noise of the instruments and the imperfect description of the atmospheric state. The SPARTE chain can be used to evaluate any spectroscopic databases, from the visible to the microwave, using any type of remote sensing observations (ground-based, airborne or space-borne). We show that the comparison of the shape of the residuals enables: (i) identifying incorrect line parameters (line position, intensity, width, pressure shift, etc.), even for molecules for which interferences between the lines have to be taken into account; (ii) proposing revised values, in cooperation with contributing teams; and (iii) validating the final updated parameters. In particular, we show that the simultaneous availability of two databases such as GEISA and HITRAN helps identifying remaining issues in each database. The SPARTE chain has been here applied to the validation of the update of GEISA-2015 in 2 spectral regions of particular interest for several currently exploited or planned Earth space missions: the thermal infrared domain and the short-wave infrared domain, for which observations from the space-borne IASI instrument and from the ground-based FTS instruments at the Parkfalls TCCON site are used respectively. Main results include: (i) the validation of the positions and intensities of line parameters, with overall significantly lower residuals for GEISA-2015 than for GEISA-2011 and (iii) the validation of the choice made on the parameters (such as pressure shift and air-broadened width) which has not been given by the provider but completed by ourselves. For example, comparisons between residuals obtained with GEISA-2015 and HITRAN-2012 have highlighted a specific issue with some HWHM values in the latter that can be clearly identified on the 'calculated-observed' residuals.

Imaging spectrophotometry of the nuclear outflow of NGC 1068

NASA Technical Reports Server (NTRS)

Cecil, Gerald

1990-01-01

This observational program (in conjunction with R. B. Tully (IfA, Honolulu), and J. Bland (Rice U., Houston)) aims to constrain the kinematic organization and dominant excitation mechanisms of ionized gas in active galaxies. More generally, researchers are interested in the dynamics of radiative, supersonic flows in the Interstellar Medium (ISM). Imaging Fabry-Perot interferometers and low-noise Charge Coupled Devices (CCDs) are used for complete spatial coverage of the complex gas distribution in circumnuclear narrow-line regions (NLRs). Extranuclear emission line widths in NLRs can exceed 3000 km s(-1), so to avoid inter-order confusion researchers use an etalon of 4000 km s(-1) free spectral range to map (N II) lambda lambda 6548, 6583 and H alpha. To maximize spatial resolution, researchers select nearby active systems independent of luminosity but known to possess interesting morphologies and/or high-velocity extranuclear ionized gas. Monochromatic images Full Width Half Maximum (FWHM) approx. 65 km s(-1) have thus far been obtained in 1 second or better seeing at the U. Hawaii 2.2m, CFH 3.6m, and CTIO 4.0m telescopes. These are stacked into grids of line profiles, of spectrophotometric quality, at sub-arcsecond increments across a 3 second field. To handle the approx. 20,000 to 300,000 useful spectra that arise from a typical night's work, researchers have developed a complete analysis and reduction package for VAX and Sun image workstations. Reduction involves parametrization of approx. 10 to the 8th raw data points to a few maps (e.g., velocities of each kinematic subsystem, continuum-free line fluxes) containing approx. 10 to the 5th pixels. Researchers identify kinematic and structural symmetries by examining these maps and the point to point variations of the synthesized line profiles. The combination of monochromatic images and full spatial sampling of line profiles has allowed them to isolate such symmetries and has led to reliable kinematic deprojections.

Very high rotational excitation of CO in a cooled electric discharge through carbon monoxide

NASA Astrophysics Data System (ADS)

Cossart-Magos, Claudina; Cossart, Daniel

2000-02-01

Infrared emission from 12CO and 13CO, excited in the cathode region of a discharge tube immersed in liquid nitrogen, was recorded by Fourier-transform spectrometry at a resolution of 0.005 cm-1. The Δv=1 sequence bands recorded in the 2500-1800 cm-1 spectral interval, indicate the existence of three different rotational populations; (i) molecules in the zero-ground level with Trot≈100 K (responsible for reabsorption of part of the 1-0 emission band); (ii) molecules with Trot≈275 K (maximum intensity for Jmax'≈6 in each band, Tvib≈3000 K for v'=2-4, Tvib≈8600 K for v'=5-13); (iii) molecules with v' limited to 6, for which R-rotational lines are observed for J' values between 50 and 120 (Jmax'≈90, non-Boltzmannian population distribution). The full-width at half-maximum (FWHM) of all the observed lines is less than 0.007 cm-1. A Doppler width of 0.005 cm-1 and translational temperature Ttr≈280 K can be deduced. Such high-J levels of the CO molecule had never been observed in the laboratory. In the absorption spectrum of the Sun photosphere, the same lines present FWHM values 5-8 times larger. The best available Dunham coefficients are checked to reproduce the high-J lines wave numbers to at least 0.001 cm-1. Dissociative recombination of the dimer (CO)2+ cation, which is likely to be formed in our experimental conditions, is discussed as a possible mechanism to produce CO fragments with very high rotational excitation, while keeping vibrational excitation limited to v'=6.

Catoptric electrodes: transparent metal electrodes using shaped surfaces.

PubMed

Kik, Pieter G

2014-09-01

An optical electrode design is presented that theoretically allows 100% optical transmission through an interdigitated metallic electrode at 50% metal areal coverage. This is achieved by redirection of light incident on embedded metal electrode lines to an angle beyond that required for total internal reflection. Full-field electromagnetic simulations using realistic material parameters demonstrate 84% frequency-averaged transmission for unpolarized illumination across the entire visible spectral range using a silver interdigitated electrode at 50% areal coverage. The redirection is achieved through specular reflection, making it nonresonant and arbitrarily broadband, provided the electrode width exceeds the optical wavelength. These findings could significantly improve the performance of photovoltaic devices and optical detectors that require high-conductivity top contacts.

FIBER AND INTEGRATED OPTICS. OTHER TOPICS IN QUANTUM ELECTRONICS: Fiber-optic interferometers: control of spectral composition of the radiation and formation of high-intensity optical pulses

NASA Astrophysics Data System (ADS)

Bulushev, A. G.; Dianov, Evgenii M.; Kuznetsov, A. V.; Okhotnikov, O. G.; Paramonov, Vladimir M.; Tsarev, Vladimir A.

1990-05-01

A study was made of the use of single-mode fiber ring interferometers in narrowing the emission lines of semiconductor lasers and increasing the optical radiation power. Efficient coupling of radiation, emitted by a multifrequency injection laser with an external resonator, into a fiber ring interferometer was achieved both under cw and mode-locking conditions. Matching of the optical lengths of the external resonator and the fiber interferometer made it possible to determine the mode width for this laser. A method for generation of optical pulses in a fiber ring interferometer from cw frequency modulated radiation was developed.

VUV Fourier-Transform absorption study of the npπ1 Πu-, v, N ←X1 Σg+, v″ = 0,N″ transitions in D2

NASA Astrophysics Data System (ADS)

Glass-Maujean, M.; Jungen, Ch.; Dickenson, G. D.; Ubachs, W.; de Oliveira, N.; Joyeux, D.; Nahon, L.

2015-09-01

The DESIRS beamline of the SOLEIL synchrotron facility, equipped with a vacuum ultraviolet Fourier-Transform spectrometer has been used to measure Q (N″) (N -N″ = 0) absorption transitions of the D2 molecule. Some 212 Q-lines were assigned and their transition frequencies determined up to excitation energies of 137 000 cm-1 above the ground state, thereby extending the earlier work by various authors, and considerably improving the spectral accuracy (<0.1 cm-1). The assignments have been aided by first principles multichannel quantum defect theory (MQDT) calculations which also provide predictions of the autoionization widths of the upper levels.

Optimal detection pinhole for lowering speckle noise while maintaining adequate optical sectioning in confocal reflectance microscopes

PubMed Central

Rajadhyaksha, Milind

2012-01-01

Abstract. Coherent speckle influences the resulting image when narrow spectral line-width and single spatial mode illumination are used, though these are the same light-source properties that provide the best radiance-to-cost ratio. However, a suitable size of the detection pinhole can be chosen to maintain adequate optical sectioning while making the probability density of the speckle noise more normal and reducing its effect. The result is a qualitatively better image with improved contrast, which is easier to read. With theoretical statistics and experimental results, we show that the detection pinhole size is a fundamental parameter for designing imaging systems for use in turbid media. PMID:23224184

High-resolution emission spectra of pulsed terahertz quantum-cascade lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ikonnikov, A. V., E-mail: antikon@ipm.sci-nnov.ru; Antonov, A. V.; Lastovkin, A. A.

The spectra of pulsed terahertz quantum-cascade lasers were measured with high spectral resolution. The characteristic line width at half maximum was 0.01 cm{sup -1}; it is controlled by laser temperature variations during the supply voltage pulse. It was shown that an increase in the laser temperature leads to a decrease in the emission frequency, which is caused by an increase in the effective refractive index of the active region. It was also found that a decrease in the supply voltage results in a decrease in the emission frequency, which is caused by a change in the energy of diagonal transitionsmore » between lasing levels.« less

3D-HST Grism Spectroscopy of a Gravitationally Lensed, Low-metallicity Starburst Galaxy at z = 1.847

NASA Astrophysics Data System (ADS)

Brammer, Gabriel B.; Sánchez-Janssen, Rubén; Labbé, Ivo; da Cunha, Elisabete; Erb, Dawn K.; Franx, Marijn; Fumagalli, Mattia; Lundgren, Britt; Marchesini, Danilo; Momcheva, Ivelina; Nelson, Erica; Patel, Shannon; Quadri, Ryan; Rix, Hans-Walter; Skelton, Rosalind E.; Schmidt, Kasper B.; van der Wel, Arjen; van Dokkum, Pieter G.; Wake, David A.; Whitaker, Katherine E.

2012-10-01

We present Hubble Space Telescope (HST) imaging and spectroscopy of the gravitational lens SL2SJ02176-0513, a cusp arc at z = 1.847. The UV continuum of the lensed galaxy is very blue, which is seemingly at odds with its redder optical colors. The 3D-HST WFC3/G141 near-infrared spectrum of the lens reveals the source of this discrepancy to be extremely strong [O III] λ5007 and Hβ emission lines with rest-frame equivalent widths of 2000 ± 100 and 520 ± 40 Å, respectively. The source has a stellar mass ~108 M ⊙, sSFR ~ 100 Gyr-1, and detection of [O III] λ4363 yields a metallicity of 12 + log (O/H) = 7.5 ± 0.2. We identify local blue compact dwarf analogs to SL2SJ02176-0513, which are among the most metal-poor galaxies in the Sloan Digital Sky Survey. The local analogs resemble the lensed galaxy in many ways, including UV/optical spectral energy distribution, spatial morphology, and emission line equivalent widths and ratios. Common to SL2SJ02176-0513 and its local counterparts is an upturn at mid-IR wavelengths likely arising from hot dust heated by starbursts. The emission lines of SL2SJ02176-0513 are spatially resolved owing to the combination of the lens and the high spatial resolution of HST. The lensed galaxy is composed of two clumps with combined size re ~300 pc, and we resolve significant differences in UV color and emission line equivalent width between them. Though it has characteristics occasionally attributed to active galactic nuclei, we conclude that SL2SJ02176-0513 is a low-metallicity star-bursting dwarf galaxy. Such galaxies will be found in significant numbers in the full 3D-HST grism survey. Based on observations made with the NASA/ESA Hubble Space Telescope, program 12328, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

The Kinematics of the Permitted C II λ6578 Line in a Large Sample of Planetary Nebulae

NASA Astrophysics Data System (ADS)

Richer, Michael G.; Suárez, Genaro; López, José Alberto; García Díaz, María Teresa

2017-03-01

We present spectroscopic observations of the C II λ6578 permitted line for 83 lines of sight in 76 planetary nebulae at high spectral resolution, most of them obtained with the Manchester Echelle Spectrograph on the 2.1 m telescope at the Observatorio Astronómico Nacional on the Sierra San Pedro Mártir. We study the kinematics of the C II λ6578 permitted line with respect to other permitted and collisionally excited lines. Statistically, we find that the kinematics of the C II λ6578 line are not those expected if this line arises from the recombination of C2+ ions or the fluorescence of C+ ions in ionization equilibrium in a chemically homogeneous nebular plasma, but instead its kinematics are those appropriate for a volume more internal than expected. The planetary nebulae in this sample have well-defined morphology and are restricted to a limited range in Hα line widths (no large values) compared to their counterparts in the Milky Way bulge; both these features could be interpreted as the result of young nebular shells, an inference that is also supported by nebular modeling. Concerning the long-standing discrepancy between chemical abundances inferred from permitted and collisionally excited emission lines in photoionized nebulae, our results imply that multiple plasma components occur commonly in planetary nebulae.

The Defect Induced Mix Experiment (DIME) for NIF

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmitt, Mark J; Bradley, Paul A; Cobble, James A

2012-06-18

LANL will perform two Defect Induced Mix Experiment (DIME) implosion campaigns on NIF in July and September, 2012. This presentation describes the goals for these shots and the experimental configuration and diagnostic set up to collect the appropriate data. The first two-shot campaign will focus on executing polar direct drive (PDD) implosions of plastic CH capsules filled with deuterium gas. Gas filling will be performed through a fill tube at target chamber center. A vanadium backligher foil will provide x-rays to radiograph the last half of the implosion to compare the implosion trajectory with modeling predictions. An equatorial groove inmore » one of the capsules will be present to determine its effect on implosion dynamics. The second DIME campaign will commission and use a spectral imager (MMI) to examine the evolution of thin capsule layers doped with either Ge or Ga at 1.85%. Spectral line emission from these layers will quantify the mix width at the inner shell radius and near an equatorial groove feature.« less

Up-scalable low-cost fabrication of plasmonic and photonic nanostructures for sensing

NASA Astrophysics Data System (ADS)

Gallinet, Benjamin; Davoine, Laurent; Basset, Guillaume; Schnieper, Marc

2013-09-01

The fabrication by nanoimprint lithography of large-area plasmonic and photonic sensing platforms is reported. The plasmonic nanostructures have the shape of split-ring resonators and support both electric dipole and quadrupole modes. They carry the spectral signature of Fano resonances. Their near-field and far-field optical properties are investigated with an analytical model together with numerical calculations. Fano-resonant systems combine strong nanoscale light confinement with a narrow spectral line width, which makes them very promising for biochemical sensing and immunoassays. On the other hand, chemical sensors based on resonant gratings are obtained by patterning a sol-gel material, evaporating a high refractive index semiconductor and coating with a chemically sensitive dye layer. By exposition to a liquid or an invisible gas such as ammonium, the change in absorption is detected optically. An analytical model is introduced to explain the enhancement of the signal by the resonant grating, which can be detected with the naked eye from a color change of the reflected light.

Single-particle spectroscopy of I-III-VI semiconductor nanocrystals: spectral diffusion and suppression of blinking by two-color excitation.

PubMed

Sharma, Dharmendar Kumar; Hirata, Shuzo; Bujak, Lukasz; Biju, Vasudevanpillai; Kameyama, Tatsuya; Kishi, Marino; Torimoto, Tsukasa; Vacha, Martin

2016-07-14

Ternary I-III-VI semiconductor nanocrystals have been explored as non-toxic alternatives to II-VI semiconductors for optoelectronic and sensing applications, but large photoluminescence spectral width and moderate brightness restrict their practical use. Here, using single-particle photoluminescence spectroscopy on nanocrystals of (AgIn)xZn2(1-x)S2 we show that the photoluminescence band is inhomogeneously broadened and that size distribution is the dominant factor in the broadening. The residual homogeneous linewidth of individual nanocrystals reaches up to 75% of the ensemble spectral width. Single nanocrystals undergo spectral diffusion which also contributes to the inhomogeneous band. Excitation with two lasers with energies above and below the bandgap reveals coexistence of two emitting donor states within one particle. Spectral diffusion in such particles is due to temporal activation and deactivation of one such state. Filling of a trap state with a lower-energy laser enables optical modulation of photoluminescence intermittency (blinking) and leads to an almost two-fold increase in brightness.

Spectral representation of the three-body Coulomb problem. II. Autoionizing doubly excited states of unnatural parity in helium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eiglsperger, Johannes; Piraux, Bernard; Madronero, Javier

2010-04-15

A spectral approach of configuration interaction type is used to evaluate energies and widths for a wide range of singlet and triplet P{sup e} resonance states of helium up to the eighth single ionization threshold. While the present data are in excellent agreement with existing theoretical results (below the N=3-5 ionization threshold) obtained within an explicitly correlated approach, there are substantial differences with the energies, the widths, and the number of resonances obtained with the stabilization method.

Multi-species sensing using multi-mode absorption spectroscopy with mid-infrared interband cascade lasers

NASA Astrophysics Data System (ADS)

O'Hagan, S.; Northern, J. H.; Gras, B.; Ewart, P.; Kim, C. S.; Kim, M.; Merritt, C. D.; Bewley, W. W.; Canedy, C. L.; Vurgaftman, I.; Meyer, J. R.

2016-06-01

The application of an interband cascade laser, ICL, to multi-mode absorption spectroscopy, MUMAS, in the mid-infrared region is reported. Measurements of individual mode linewidths of the ICL, derived from the pressure dependence of lineshapes in MUMAS signatures of single, isolated, lines in the spectrum of HCl, were found to be in the range 10-80 MHz. Multi-line spectra of methane were recorded using spectrally limited bandwidths, of approximate width 27 cm-1, defined by an interference filter, and consist of approximately 80 modes at spectral locations spanning the 100 cm-1 bandwidth of the ICL output. Calibration of the methane pressures derived from MUMAS data using a capacitance manometer provided measurements with an uncertainty of 1.1 %. Multi-species sensing is demonstrated by the simultaneous detection of methane, acetylene and formaldehyde in a gas mixture. Individual partial pressures of the three gases are derived from best fits of model MUMAS signatures to the data with an experimental error of 10 %. Using an ICL, with an inter-mode interval of ~10 GHz, MUMAS spectra were recorded at pressures in the range 1-10 mbar, and, based on the data, a potential minimum detection limit of the order of 100 ppmv is estimated for MUMAS at atmospheric pressure using an inter-mode interval of 80 GHz.

Automatic alignment of individual peaks in large high-resolution spectral data sets

NASA Astrophysics Data System (ADS)

Stoyanova, Radka; Nicholls, Andrew W.; Nicholson, Jeremy K.; Lindon, John C.; Brown, Truman R.

2004-10-01

Pattern recognition techniques are effective tools for reducing the information contained in large spectral data sets to a much smaller number of significant features which can then be used to make interpretations about the chemical or biochemical system under study. Often the effectiveness of such approaches is impeded by experimental and instrument induced variations in the position, phase, and line width of the spectral peaks. Although characterizing the cause and magnitude of these fluctuations could be important in its own right (pH-induced NMR chemical shift changes, for example) in general they obscure the process of pattern discovery. One major area of application is the use of large databases of 1H NMR spectra of biofluids such as urine for investigating perturbations in metabolic profiles caused by drugs or disease, a process now termed metabonomics. Frequency shifts of individual peaks are the dominant source of such unwanted variations in this type of data. In this paper, an automatic procedure for aligning the individual peaks in the data set is described and evaluated. The proposed method will be vital for the efficient and automatic analysis of large metabonomic data sets and should also be applicable to other types of data.

Ultrasensitive detection of atmospheric trace gases using frequency modulation spectroscopy

NASA Technical Reports Server (NTRS)

Cooper, David E.

1986-01-01

Frequency modulation (FM) spectroscopy is a new technique that promises to significantly extend the state-of-the-art in point detection of atmospheric trace gases. FM spectroscopy is essentially a balanced bridge optical heterodyne approach in which a small optical absorption or dispersion from an atomic or molecular species of interest generates an easily detected radio frequency (RF) signal. This signal can be monitored using standard RF signal processing techniques and is, in principle, limited only by the shot noise generated in the photodetector by the laser source employed. The use of very high modulation frequencies which exceed the spectral width of the probed absorption line distinguishes this technique from the well-known derivative spectroscopy which makes use of low (kHz) modulation frequencies. FM spectroscopy was recently extended to the 10 micron infrared (IR) spectral region where numerous polyatomic molecules exhibit characteristic vibrational-rotational bands. In conjunction with tunable semiconductor diode lasers, the quantum-noise-limited sensitivity of the technique should allow for the detection of absorptions as small as .00000001 in the IR spectral region. This sensitivity would allow for the detection of H2O2 at concentrations as low as 1 pptv with an integration time of 10 seconds.

No Compton Reflection In a Chandra/RXTE Observation of Mkn 509: Implications for the Fe-K Line Emission From Accreting X-Ray Sources

NASA Technical Reports Server (NTRS)

Yaqoob, Tahir; Padmanabhan, Urmila; Kraemer, Steven B.; Crenshaw, D. Michael; Mckernan, Barry; George, Ian M.; Turner, T. Jane; White, Nicholas E. (Technical Monitor)

2002-01-01

We report the results of simultaneous Chandra and RXTE observations of the Seyfert 1 galaxy Mkn 509. We deconvolve the broad and narrow Fe-K emission-line components for which we measure rest-frame equivalent widths of 119+/-18 eV and 57+/-13 eV respectively. The broad line has a FWHM of 57,600((sup 14,400)(sub -21,000)) km/s and the narrow line is unresolved, with an upper limit on the FWHM of 4,940 km/s. Both components must originate in cool matter since we measure rest-frame center energies of 6.36((sup +0.13)(sub -0.12)) keV and 6.42+/-0.01 keV for the broad and narrow line respectively. This rules out He-like and H-like Fe for the origin of both the broad and narrow lines. If, as is widely accepted, the broad Fe-K line originates in Thomson-thick matter (such as an accretion disk), then one expects to observe spectral curvature above approximately 10 keV, (commensurate with the observed broad line), characteristic of the Compton-reflection continuum. However our data sets very stringent limits on deviations of the observed continuum from a power law. Light travel-time delays cannot be invoked to explain anomalies in the relative strengths of the broad Ferry line and Compton-reflection continuum since they are supposed to originate in the same physical location. We are forced to conclude that both the broad and narrow Fe-K lines had to originate in Thomson-thin matter during our observation. This result, for a single observation of just one source, means that our understanding of Fe K line emission and Compton reflection from accreting X-ray sources in general needs to be re-examined. For example, if an irradiated accretion disk existed in Mkn 509 at the time of the observations, the lack of spectral curvature above approximately 10 keV suggests two possibilities. Either the disk was Thomson-thick and highly ionized, having negligible Fe-K line emission and photoelectric absorption or the disk was Thomson-thin producing some or all of the broad Fe-K line emission. In the former case, the broad Fe-K line had to have produced in a Thomson-thin region elsewhere. In both cases the predicted spectral curvature above approximately 10 keV is negligible. An additional implication of our results is that any putative obscuring torus in the system, required by unification models of active galaxies, must also be Thomson-thin. The same applies to the optical broad line region (BLR) if it has a substantial covering factor.

Long-lived, long-period radial velocity variations in Aldebaran: A planetary companion and stellar activity

NASA Astrophysics Data System (ADS)

Hatzes, A. P.; Cochran, W. D.; Endl, M.; Guenther, E. W.; MacQueen, P.; Hartmann, M.; Zechmeister, M.; Han, I.; Lee, B.-C.; Walker, G. A. H.; Yang, S.; Larson, A. M.; Kim, K.-M.; Mkrtichian, , D. E.; Döllinger, M.; Simon, , A. E.; Girardi, L.

2015-08-01

Aims: We investigate the nature of the long-period radial velocity variations in α Tau first reported over 20 yr ago. Methods: We analyzed precise stellar radial velocity measurements for α Tau spanning over 30 yr. An examination of the Hα and Ca II λ8662 spectral lines, and Hipparcos photometry was also done to help discern the nature of the long-period radial velocity variations. Results: Our radial velocity data show that the long-period, low amplitude radial velocity variations are long-lived and coherent. Furthermore, Hα equivalent width measurements and Hipparcos photometry show no significant variations with this period. Another investigation of this star established that there was no variability in the spectral line shapes with the radial velocity period. An orbital solution results in a period of P = 628.96 ± 0.90 d, eccentricity, e = 0.10 ± 0.05, and a radial velocity amplitude, K = 142.1 ± 7.2 m s-1. Evolutionary tracks yield a stellar mass of 1.13 ± 0.11 M⊙, which corresponds to a minimum companion mass of 6.47 ± 0.53 MJup with an orbital semi-major axis of a = 1.46 ± 0.27 AU. After removing the orbital motion of the companion, an additional period of ≈520 d is found in the radial velocity data, but only in some time spans. A similar period is found in the variations in the equivalent width of Hα and Ca II. Variations at one-third of this period are also found in the spectral line bisector measurements. The ~520 d period is interpreted as the rotation modulation by stellar surface structure. Its presence, however, may not be long-lived, and it only appears in epochs of the radial velocity data separated by ~10 yr. This might be due to an activity cycle. Conclusions: The data presented here provide further evidence of a planetary companion to α Tau, as well as activity-related radial velocity variations. Based in part on observations obtained at the 2-m-Alfred Jensch Telescope at the Thüringer Landessternwarte Tautenburg and the telescope facilities of McDonald Observatory.Tables 3-9 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/580/A31

Spectral Analysis, Synthesis, & Energy Distributions of Nearby E+A Galaxies Using SDSS-IV MaNGA

NASA Astrophysics Data System (ADS)

Weaver, Olivia A.; Anderson, Miguel Ricardo; Wally, Muhammad; James, Olivia; Falcone, Julia; Liu, Allen; Wallack, Nicole; Liu, Charles; SDSS Collaboration

2017-01-01

Utilizing data from the Mapping Nearby Galaxies at APO (MaNGA) Survey (MaNGA Product Launch-4, or MPL-4), of the latest generation of the Sloan Digital Sky Survey (SDSS-IV), we identified nine post-starburst (E+A) systems that lie within the Green Valley transition zone. We identify the E+A galaxies by their SDSS single fiber spectrum and u-r color, then confirmed their classification as post-starburst by coding/plotting methods and spectral synthesis codes (FIREFLY and PIPE3D), as well as with their Spectral Energy Distributions (SEDs) from 0.15 µm to 22 µm, using GALEX, SDSS, 2MASS, and WISE data. We produced maps of gaussian-fitted fluxes, equivalent widths, stellar velocities, metallicities and age. We also produced spectral line ratio diagrams to classify regions of stellar populations of the galaxies. We found that our sample of E+As retain their post-starburst properties across the entire galaxy, not just at their center. We detected matching a trend line in the ultraviolet and optical bands, consistent with the expected SEDs for an E+A galaxy, and also through the J, H and Ks bands, except for one object. We classified one of the nine galaxies as a luminous infrared galaxy, unusual for a post-starburst object. Our group seeks to further study stellar population properties, spectral energy distributions and quenching properties in E+A galaxies, and investigate their role in galaxy evolution as a whole. This work was supported by the Alfred P. Sloan Foundation via the SDSS-IV Faculty and Student Team (FAST) initiative, ARC Agreement #SSP483 to the CUNY College of Staten Island. This work was also supported by grants to The American Museum of Natural History, and the CUNY College of Staten Island through from National Science Foundation.

Hanle effect in nonmonochromatic laser light

NASA Astrophysics Data System (ADS)

Ryan, R. E.; Bergeman, T. H.

1991-06-01

We report results of calculations on the Hanle effect in a J=0⇆J=1 atomic transition with three types of model fluctuating light fields: (a) the Brownian-motion phase-diffusion field, as produced in recent experiments by Arnett et al. [Phys. Rev. A 41, 2580 (1990)]; (b) Gaussian amplitude fluctuations; and (c) the chaotic field model, in which real and imaginary parts of the electric-field amplitude fluctuate. For the stochastic density-matrix equations, we use methods developed by Zoller and co-workers [e.g., Dixit, Zoller, and Lambropoulos, Phys. Rev. A 21, 1289 (1980)] employing the Fokker-Planck operator and leading to matrix continued-fraction expansions. The Hanle effect is of interest as a prototype for multisublevel atomic transitions. The width of the Hanle dip at zero magnetic field reflects the tendency of the light field to preserve the coherence between excited-state sublevels. For monochromatic light, the Hanle dip width increases as the square root of light intensity. When the laser bandwidth increases, power broadening of the coherence dip normally decreases. However, with the Brownian-motion phase-diffusion model, if the laser spectral profile is nearly Gaussian, broadening the laser up to several times the natural width of the atomic line does not diminish the Hanle dip width. With amplitude fluctuations, even in the limit of monochromatic light, power broadening of the Hanle dip with intensity is reduced by one-third to one-half depending on the particular model.

Fabry-Perot interferometer measurement of static temperature and velocity for ASTOVL model tests

NASA Technical Reports Server (NTRS)

Kourous, Helen E.; Seacholtz, Richard G.

1995-01-01

A spectrally resolved Rayleigh/Mie scattering diagnostic was developed to measure temperature and wing-spanwise velocity in the vicinity of an ASTOVL aircraft model in the Lewis 9 x 15 Low Speed Wind Tunnel. The spectrum of argon-ion laser light scattered by the air molecules and particles in the flow was resolved with a Fabry-Perot interferometer. Temperature was extracted from the spectral width of the Rayleigh scattering component, and spanwise gas velocity from the gross spectral shift. Nozzle temperature approached 800 K, and the velocity component approached 30 m/s. The measurement uncertainty was about 5 percent for the gas temperature, and about 10 m/s for the velocity. The large difference in the spectral width of the Mie scattering from particles and the Rayleigh scattering from gas molecules allowed the gas temperature to be measured in flow containing both naturally occurring dust and LDV seed (both were present).

The Survey of HI in Extremely Low-mass Dwarfs: A Multi-Wavelength Perspective on Low-Mass Galaxy Evolution

NASA Astrophysics Data System (ADS)

Cannon, John M.; McNichols, Andrew; Teich, Yaron; Adams, Elizabeth A.; Giovanelli, Riccardo; Haynes, Martha P.; McQuinn, Kristen B.; Salzer, John Joseph; Skillman, Evan D.; Dolphin, Andrew E.; Elson, Edward C.; Haurberg, Nathalie C.; Huang, Shan; Janowiecki, Steven; Jozsa, Gyula; Leisman, Luke; Ott, Juergen; Papastergis, Emmanouil; Rhode, Katherine L.; Saintonge, Amelie; Van Sistine, Angela; Warren, Steven R.

2017-01-01

The “Survey of HI in Extremely Low-mass Dwarfs” (SHIELD) is a multiwavelength study of local volume low-mass galaxies drawn from the Arecibo Legacy Fast ALFA (ALFALFA) catalog. HST/Spitzer joint program GO-12658 revealed the stellar populations of the first 12 SHIELD galaxies (Cannon et al. 2011), allowing accurate distance measurements (McQuinn et al. 2014) and detailed studies of the patterns of recent star formation in each galaxy (McQuinn et al. 2015). These HST and Spitzer images are a critical interpretive benchmark for ground-based optical imaging and spectroscopy (Haurberg et al. 2015), as well as for sensitive VLA HI spectral line imaging of the SHIELD galaxies (McNichols et al. 2016; Teich et al. 2016). These results have furthered our understanding of the evolution of galaxies in a mass regime that was previously only sparsely populated. With the low-redshift ALFALFA catalog now complete, the scope of the SHIELD program has been expanded to include all 82 galaxies that meet distance, line width, and HI flux criteria for being gas-rich, low-mass galaxies. In HST program 13750, images of 18 more SHIELD galaxies have again set the physical scales for supporting HI spectral line imaging with both the VLA and the WSRT (Gordon et al. 2016). Taken as a whole, the ongoing SHIELD program is one of the most comprehensive multiwavelength studies of the physical properties of low-mass galaxies outside of the Local Group.

Using Hyperfine Structure Limits to Characterize the Formaldehyde Maser in G32.74-0.07

NASA Astrophysics Data System (ADS)

Araya, Esteban; Nazmus Sakib, Md; Olmi, Luca; Hofner, Peter; Kurtz, Stan; Hoffman, Ian M.; Linz, Hendrik

2018-06-01

Formaldehyde (H2CO) masers are a rare variety of astrophysical masers, but they have the virtue of exclusively tracing the interiors of high-mass star forming regions. We report observations conducted with the 305m Arecibo Telescope and the Karl G. Jansky Very Large Array (VLA) of the 6 cm H2CO maser in the region of high-mass star formation G32.74-0.07. This maser is among the narrowest H2CO masers known, and thus it is an excellent candidate to study the excitation of the hyperfine components of the transition. The Arecibo and VLA results are consistent, the maser flux density observed with Arecibo is recovered in the VLA image within the rms noise of the spectra, and the fitted line widths of the two observations agree to within formal errors. Our high signal-to-noise (~7 mJy rms) and high spectral resolution (0.05 km/s) observations allow us to set strong limits on the hyperfine structure of the line. The line profile is consistent with unsaturated emission, with a maser gain of approximately 3, and an amplified background radio continuum of ~1 mJy. VLA observations confirm the presence of a continuum source at the location of the maser. The continuum source is characterized by a spectral index of +0.9 at 5 GHz, which is indicative of thermal Bremsstrahlung in the optically thick/thin transition.

Interferometric investigation of emission lines from the solar corona

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marshall, P.M.; Henderson, G.

1973-11-01

The profiles of the Fe XN, lambda 5303, and Fe X, lambda 6374, emission lines of the solar corona were observed at different posttions using a photoelectric scanning Fabry -- Perot interferometer. These profiles were obtained during the eclipse of 7th March 1970, in Mexico and at the Pic-du-Midi coronagraph in October, 1970. The half-widths of these profiles were determined for both the coronal lines and temperatures were derived from these widths. No systematic temperature variation was discovered, however there was some suggestion of the existence of a fluctuation with time in the width of the emission lines. (auth)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goto, Motoshi; Morita, Shigeru

Emission lines in the visible/UV wavelength ranges are observed with 80 lines of sight which cover an entire poloidal cross section of the plasma in the Large Helical Device. The emitted light is received with optical fibers having 100 {mu}m diameter and is guided into a 1.33 m Czerny-Turner-type spectrometer based on spherical mirrors for collimating and focusing. A charge-coupled device having 13.3x13.3 mm{sup 2} area size is used as the detector and the spectra from all the lines of sight are recorded perpendicularly to the wavelength dispersion. The spectrometer is equipped with optics located in front of the entrancemore » slit to correct the difference between the meridional and sagittal focal points, and thus the astigmatism, which otherwise causes severe cross talk between adjacent optical fiber images on the detector, is corrected. Consequently, simultaneous spectral measurement with 80 lines of sight is realized. The Zeeman splitting of a neutral helium line, {lambda}667.8 nm (2 {sup 1}P-3 {sup 1}D), which is caused by the magnetic field for plasma confinement, is measured with the spectrometer. Though the obtained line profile is in general a superposition of several components on the same line of sight, they can be separated according to their different splitting widths. The two-dimensional poloidal distribution of the helium line intensity is obtained with the help of a tomographic technique.« less

970-nm ridge waveguide diode laser bars for high power DWBC systems

NASA Astrophysics Data System (ADS)

Wilkens, Martin; Erbert, Götz; Wenzel, Hans; Knigge, Andrea; Crump, Paul; Maaßdorf, Andre; Fricke, Jörg; Ressel, Peter; Strohmaier, Stephan; Schmidt, Berthold; Tränkle, Günther

2018-02-01

de lasers are key components in material processing laser systems. While mostly used as pump sources for solid state or fiber lasers, direct diode laser systems using dense wavelength multiplexing have come on the market in recent years. These systems are realized with broad area lasers typically, resulting in beam quality inferior to disk or fiber lasers. We will present recent results of highly efficient ridge waveguide (RW) lasers, developed for dense-wavelength-beamcombining (DWBC) laser systems expecting beam qualities comparable to solid state laser systems and higher power conversion efficiencies (PCE). The newly developed RW lasers are based on vertical structures with an extreme double asymmetric large optical cavity. Besides a low vertical divergence these structures are suitable for RW-lasers with (10 μm) broad ridges, emitting in a single mode with a good beam quality. The large stripe width enables a lateral divergence below 10° (95 % power content) and a high PCE by a comparably low series resistance. We present results of single emitters and small test arrays under different external feedback conditions. Single emitters can be tuned from 950 nm to 975 nm and reach 1 W optical power with more than 55 % PCE and a beam quality of M2 < 2 over the full wavelength range. The spectral width is below 30 pm FWHM. 5 emitter arrays were stabilized using the same setup. Up to now we reached 3 W optical power, limited by power supply, with 5 narrow spectral lines.

X-ray spectra of Hercules X-1. 1: Iron line fluorescence from a subrelativistic shell

NASA Technical Reports Server (NTRS)

Pravdo, S. H.; Becker, R. H.; Boldt, E. A.; Holt, S. S.; Serlemitsos, P. J.; Swank, J. H.

1977-01-01

The X-ray spectrum of Hercules X-1 was observed in the energy range 2-24 keV from August 29 to September 3, 1975. A broad iron line feature is observed in the normal high state spectrum. The line equivalent width is given along with its full-width-half-maximum energy. Iron line fluorescence from an opaque, cool shell of material at the Alfven surface provides the necessary luminosity in this feature. The line energy width can be due to Doppler broadening if the shell is forced to corotate with the pulsar at a radius 800 million cm. Implications of this model regarding physical conditions near Her X-1 are discussed.

Plexcitons: The Role of Oscillator Strengths and Spectral Widths in Determining Strong Coupling.

PubMed

Thomas, Reshmi; Thomas, Anoop; Pullanchery, Saranya; Joseph, Linta; Somasundaran, Sanoop Mambully; Swathi, Rotti Srinivasamurthy; Gray, Stephen K; Thomas, K George

2018-01-23

Strong coupling interactions between plasmon and exciton-based excitations have been proposed to be useful in the design of optoelectronic systems. However, the role of various optical parameters dictating the plasmon-exciton (plexciton) interactions is less understood. Herein, we propose an inequality for achieving strong coupling between plasmons and excitons through appropriate variation of their oscillator strengths and spectral widths. These aspects are found to be consistent with experiments on two sets of free-standing plexcitonic systems obtained by (i) linking fluorescein isothiocyanate on Ag nanoparticles of varying sizes through silane coupling and (ii) electrostatic binding of cyanine dyes on polystyrenesulfonate-coated Au nanorods of varying aspect ratios. Being covalently linked on Ag nanoparticles, fluorescein isothiocyanate remains in monomeric state, and its high oscillator strength and narrow spectral width enable us to approach the strong coupling limit. In contrast, in the presence of polystyrenesulfonate, monomeric forms of cyanine dyes exist in equilibrium with their aggregates: Coupling is not observed for monomers and H-aggregates whose optical parameters are unfavorable. The large aggregation number, narrow spectral width, and extremely high oscillator strength of J-aggregates of cyanines permit effective delocalization of excitons along the linear assembly of chromophores, which in turn leads to efficient coupling with the plasmons. Further, the results obtained from experiments and theoretical models are jointly employed to describe the plexcitonic states, estimate the coupling strengths, and rationalize the dispersion curves. The experimental results and the theoretical analysis presented here portray a way forward to the rational design of plexcitonic systems attaining the strong coupling limits.

Power spectrum weighted edge analysis for straight edge detection in images

NASA Astrophysics Data System (ADS)

Karvir, Hrishikesh V.; Skipper, Julie A.

2007-04-01

Most man-made objects provide characteristic straight line edges and, therefore, edge extraction is a commonly used target detection tool. However, noisy images often yield broken edges that lead to missed detections, and extraneous edges that may contribute to false target detections. We present a sliding-block approach for target detection using weighted power spectral analysis. In general, straight line edges appearing at a given frequency are represented as a peak in the Fourier domain at a radius corresponding to that frequency, and a direction corresponding to the orientation of the edges in the spatial domain. Knowing the edge width and spacing between the edges, a band-pass filter is designed to extract the Fourier peaks corresponding to the target edges and suppress image noise. These peaks are then detected by amplitude thresholding. The frequency band width and the subsequent spatial filter mask size are variable parameters to facilitate detection of target objects of different sizes under known imaging geometries. Many military objects, such as trucks, tanks and missile launchers, produce definite signatures with parallel lines and the algorithm proves to be ideal for detecting such objects. Moreover, shadow-casting objects generally provide sharp edges and are readily detected. The block operation procedure offers advantages of significant reduction in noise influence, improved edge detection, faster processing speed and versatility to detect diverse objects of different sizes in the image. With Scud missile launcher replicas as target objects, the method has been successfully tested on terrain board test images under different backgrounds, illumination and imaging geometries with cameras of differing spatial resolution and bit-depth.

Stark widths regularities within spectral series of sodium isoelectronic sequence

NASA Astrophysics Data System (ADS)

Trklja, Nora; Tapalaga, Irinel; Dojčinović, Ivan P.; Purić, Jagoš

2018-02-01

Stark widths within spectral series of sodium isoelectronic sequence have been studied. This is a unique approach that includes both neutrals and ions. Two levels of problem are considered: if the required atomic parameters are known, Stark widths can be calculated by some of the known methods (in present paper modified semiempirical formula has been used), but if there is a lack of parameters, regularities enable determination of Stark broadening data. In the framework of regularity research, Stark broadening dependence on environmental conditions and certain atomic parameters has been investigated. The aim of this work is to give a simple model, with minimum of required parameters, which can be used for calculation of Stark broadening data for any chosen transitions within sodium like emitters. Obtained relations were used for predictions of Stark widths for transitions that have not been measured or calculated yet. This system enables fast data processing by using of proposed theoretical model and it provides quality control and verification of obtained results.

Identifying Bright Stars in Crowded Environments Using Velocity Dispersion Measurements, and an Application to the Center of M32

NASA Astrophysics Data System (ADS)

Davidge, T. J.; Beck, Tracy L.; McGregor, Peter J.

2010-02-01

The identification of individual stars in crowded environments using photometric information alone is confounded by source confusion. However, with the addition of spectroscopic information it is possible to distinguish between blends and areas where the light is dominated by a single star, using the widths of absorption features. We describe a procedure for identifying locations in kinematically hot environments where the light is dominated by a single star, and apply this method to spectra with 0.1″ angular resolution covering the 2.1-2.3 μm interval in the central regions of M32. Targets for detailed investigation are selected as areas of localized brightness enhancement. Three locations where at least 60% of the K-band light comes from a single bright star, and another with light that is dominated by two stars with very different velocities, are identified. The dominant stars are evolving near the tip of the asymptotic giant branch (AGB), and have M5 III spectral type. The lack of a dispersion in spectral type suggests that the upper AGB within the central arcsecond of M32 has a dispersion in J - K of only a few hundredths of a magnitude, in agreement with what is seen at larger radii. One star has weaker atomic absorption lines than the others, such that [M/H] is 0.2 dex lower. Such a difference in metallicity is consistent with the metallicity dispersion inferred from the photometric width of the AGB in M32. The use of line width to distinguish between blends involving many relatively faint stars, none of which dominate the light output, and areas that are dominated by a single intrinsically bright star could be extended to crowded environments in other nearby galaxies. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (US), the Science and Technology Facilities Council (UK), the National Research Council of Canada (Canada), CONICYT (Chile), the Australian Research Council (Australia), the Ministerio da Ciencia e Technologia (Brazil), and the Ministerio de Ciencia, Tecnologia e Innovacion Productiva (Argentina).

A New Measurement of the Spectral Lag of Gamma-Ray Bursts and its Implications for Spectral Evolution Behaviors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shao, Lang; Wang, Fu-Ri; Cheng, Ye-Hao

We carry out a systematical study of the spectral lag properties of 50 single-pulsed gamma-ray bursts (GRBs) detected by the Fermi Gamma-Ray Burst Monitor. By dividing the light curves into multiple consecutive energy channels, we provide a new measurement of the spectral lag that is independent of energy channel selections. We perform a detailed statistical study of our new measurements. We find two similar power-law energy dependencies of both the pulse arrival time and pulse width. Our new results on the power-law indices would favor the relativistic geometric effects for the origin of spectral lag. However, a complete theoretical frameworkmore » that can fully account for the diverse energy dependencies of both arrival time and pulse width revealed in this work is still lacking. We also study the spectral evolution behaviors of the GRB pulses. We find that a GRB pulse with negligible spectral lag would usually have a shorter pulse duration and would appear to have a “hardness-intensity tracking” behavior, and a GRB pulse with a significant spectral lag would usually have a longer pulse duration and would appear to have a “hard-to-soft” behavior.« less

The lick-index calibration of the Gemini multi-object spectrographs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Puzia, Thomas H.; Miller, Bryan W.; Trancho, Gelys

2013-06-01

We present the calibration of the spectroscopic Lick/IDS standard line-index system for measurements obtained with the Gemini Multi-Object Spectrographs known as GMOS-North and GMOS-South. We provide linear correction functions for each of the 25 standard Lick line indices for the B600 grism and two instrumental setups, one with 0.''5 slit width and 1 × 1 CCD pixel binning (corresponding to ∼2.5 Å spectral resolution) and the other with 0.''75 slit width and 2 × 2 binning (∼4 Å). We find small and well-defined correction terms for the set of Balmer indices Hβ, Hγ {sub A}, and Hδ {sub A} alongmore » with the metallicity sensitive indices Fe5015, Fe5270, Fe5335, Fe5406, Mg{sub 2}, and Mgb that are widely used for stellar population diagnostics of distant stellar systems. We find other indices that sample molecular absorption bands, such as TiO{sub 1} and TiO{sub 2}, with very wide wavelength coverage or indices that sample very weak molecular and atomic absorption features, such as Mg{sub 1}, as well as indices with particularly narrow passband definitions, such as Fe4384, Ca4455, Fe4531, Ca4227, and Fe5782, which are less robustly calibrated. These indices should be used with caution.« less

HIGH PRECISION K-SHELL PHOTOABSORPTION CROSS SECTIONS FOR ATOMIC OXYGEN: EXPERIMENT AND THEORY

DOE Office of Scientific and Technical Information (OSTI.GOV)

McLaughlin, B. M.; Ballance, C. P.; Bowen, K. P.

2013-07-01

Photoabsorption of atomic oxygen in the energy region below the 1s {sup -1} threshold in X-ray spectroscopy from Chandra and XMM-Newton is observed in a variety of X-ray binary spectra. Photoabsorption cross sections determined from an R-matrix method with pseudo-states and new, high precision measurements from the Advanced Light Source (ALS) are presented. High-resolution spectroscopy with E/{Delta}E Almost-Equal-To 4250 {+-} 400 was obtained for photon energies from 520 eV to 555 eV at an energy resolution of 124 {+-} 12 meV FWHM. K-shell photoabsorption cross section measurements were made with a re-analysis of previous experimental data on atomic oxygen atmore » the ALS. Natural line widths {Gamma} are extracted for the 1s {sup -1}2s {sup 2}2p {sup 4}({sup 4} P)np {sup 3} P Degree-Sign and 1s {sup -1}2s {sup 2}2p {sup 4}({sup 2} P)np {sup 3} P Degree-Sign Rydberg resonances series and compared with theoretical predictions. Accurate cross sections and line widths are obtained for applications in X-ray astronomy. Excellent agreement between theory and the ALS measurements is shown which will have profound implications for the modeling of X-ray spectra and spectral diagnostics.« less

PECULIAR NEAR-NUCLEUS OUTGASSING OF COMET 17P/HOLMES DURING ITS 2007 OUTBURST

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qi, Chunhua; Gurwell, Mark A.; Wilner, David J.

2015-01-20

We present high angular resolution Submillimeter Array observations of the outbursting Jupiter family comet 17P/Holmes on 2007 October 26-29, achieving a spatial resolution of 2.''5, or ∼3000 km at the comet distance. The observations resulted in detections of the rotational lines CO 3-2, HCN 4-3, H{sup 13}CN 4-3, CS 7-6, H{sub 2}CO 3{sub 1,} {sub 2}-2{sub 1,} {sub 1}, H{sub 2}S 2{sub 2,} {sub 0}-2{sub 1,} {sub 1}, and multiple CH{sub 3}OH lines, along with the associated dust continuum at 221 and 349 GHz. The continuum has a spectral index of 2.7 ± 0.3, slightly steeper than blackbody emission from large dust particles.more » From the imaging data, we identify two components in the molecular emission. One component is characterized by a relatively broad line width (∼1 km s{sup –1} FWHM) exhibiting a symmetric outgassing pattern with respect to the nucleus position. The second component has a narrower line width (<0.5 km s{sup –1} FWHM) with the line center redshifted by 0.1-0.2 km s{sup –1} (cometocentric frame), and shows a velocity shift across the nucleus position with the position angle gradually changing from 66° to 30° within the four days of observations. We determine distinctly different CO/HCN ratios for each of the components. For the broad-line component we find CO/HCN < 7, while in the narrow-line component, CO/HCN = 40 ± 5. We hypothesize that the narrow-line component originates from the ice grain halo found in near-nucleus photometry, believed to be created by sublimating recently released ice grains around the nucleus during the outburst. In this interpretation, the high CO/HCN ratio of this component reflects the more pristine volatile composition of nucleus material released in the outburst.« less

Surface Gravities for 228 M, L, and T Dwarfs in the NIRSPEC Brown Dwarf Spectroscopic Survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, Emily C.; Mace, Gregory N.; McLean, Ian S.

2017-03-20

We combine 131 new medium-resolution ( R ∼ 2000) J -band spectra of M, L, and T dwarfs from the Keck NIRSPEC Brown Dwarf Spectroscopic Survey (BDSS) with 97 previously published BDSS spectra to study surface-gravity-sensitive indices for 228 low-mass stars and brown dwarfs spanning spectral types M5–T9. Specifically, we use an established set of spectral indices to determine surface gravity classifications for all of the M6–L7 objects in our sample by measuring the equivalent widths (EW) of the K i lines at 1.1692, 1.1778, and 1.2529 μ m, and the 1.2 μ m FeH{sub J} absorption index. Our resultsmore » are consistent with previous surface gravity measurements, showing a distinct double peak—at ∼L5 and T5—in K i EW as a function of spectral type. We analyze the K i EWs of 73 objects of known ages and find a linear trend between log(Age) and EW. From this relationship, we assign age ranges to the very low gravity, intermediate gravity, and field gravity designations for spectral types M6–L0. Interestingly, the ages probed by these designations remain broad, change with spectral type, and depend on the gravity-sensitive index used. Gravity designations are useful indicators of the possibility of youth, but current data sets cannot be used to provide a precise age estimate.« less

Flat-field VLS spectrometers for laboratory applications

NASA Astrophysics Data System (ADS)

Ragozin, Evgeny N.; Belokopytov, Aleksei A.; Kolesnikov, Aleksei O.; Muslimov, Eduard R.; Shatokhin, Aleksei N.; Vishnyakov, Eugene A.

2017-05-01

Our intention is to develop high-resolution stigmatic spectral imaging in the XUV (2 - 40 nm). We have designed, aligned and tested a broadband stigmatic spectrometer for a range of 12-30 nm, which makes combined use of a normalincidence multilayer mirror (MM) (in particular, a broadband aperiodic MM) and a grazing-incidence plane varied linespace (VLS) reflection grating. The concave MM produces a slightly astigmatic image of the radiation source (for instance, the entrance slit), and the VLS grating produces a set of its dispersed stigmatic spectral images. The multilayer structure determines the spectral width of the operating range, which may amount to more than an octave in wavelength (e.g. 12.5-30 nm for an aperiodic Mo/Si MM), while the VLS grating controls the spectral focal curve. The stigmatism condition is satisfied simultaneously for two wavelengths, 14 and 27 nm. In this case, the condition of non-rigorous stigmatism is fulfilled for the entire wavelength range. A LiF laser plasma spectrum was recorded in one 0.5 J laser shot. A spatial resolution of 26 μm and a spectral resolution of 900 were demonstrated in the 12.5 - 25 nm range. We also report the design of a set of flat-field spectrometers of Harada type with VLS gratings. VLS gratings were made by ebeam and interference lithography. A technique (analytical + numerical) was developed for calculating optical schemes for writing plane and concave VLS gratings with predefined line density variation.

Experimental Line List of Water Vapor Absorption Lines in the Spectral Ranges 1850 - 2280 CM-1 and 2390-4000 CM-1

NASA Astrophysics Data System (ADS)

Loos, Joep; Birk, Manfred; Wagner, Georg

2017-06-01

A new experimental line parameter list of water vapor absorption lines in the spectral ranges 1850 - 2280 cm-1 and 2390 - 4000 cm-1 is presented. The line list is based on the analysis of several transmittance spectra measured using a Bruker IFS 125 HR high resolution Fourier transform spectrometer. A total of 54 measurements of pure water and water/air-mixtures at 296 K as well as water/air-mixtures at high and low temperatures were performed. A multispectrum fitting approach was used applying a quadratic speed-dependent hard collision line shape model in the Hartmann-Tran implementation extended to account for line mixing in the Rosenkranz approximation in order to retrieve line positions, intensities, self- and air-broadening parameters, their speed-dependence, self- and air-shifts as well as line mixing and in some cases collisional narrowing parameters. Additionally, temperature dependence parameters for widths, shifts and in a few cases line mixing were retrieved. For every parameter an extensive error estimation calculation was performed identifying and specifying systematic error sources. The resulting parameters are compared to the databases HITRAN12 as well as experimental values. For intensities, a detailed comparison to results of recent ab initio calculations performed at University College London was done showing an agreement within 2 % for a majority of the data. However, for some bands there are systematic deviations attributed to ab initio calculation errors. .H. Ngo et al. JQSRT 129, 89-100 (2013) doi:10.1016/j.jqsrt.2013.05.034; JQSRT 134, 105 (2014) doi:10.1016/j.jqsrt.2013.10.016. H. Tran et al. JQSRT 129, 199-203 (2013) doi:10.1016/j.jqsrt.2013.06.015; JQSRT 134, 104 (2014) doi:10.1016/j.jqsrt.2013.10.015. L.S. Rothman et al. JQSRT 130, 4-50 (2013) doi:10.1016/j.jqsrt.2013.07.002. N. Jacquinet-Husson et al. JMS 112, 2395-2445 (2016) doi:10.1016/j.jms.2016.06.007.

Photometric and spectral evolution of the symbiotic eclipsing variable V1329 Cygni at a late stage of its nova-like outburst

NASA Astrophysics Data System (ADS)

Arkhipova, V. P.; Esipov, V. F.; Ikonnikova, N. P.; Komissarova, G. V.

2015-03-01

The photoelectric UBV observations of the peculiar symbiotic star V1329 Cyg performed at the Crimean Station of the SAI-MSU during 245 nights over the period 2003-2014 are presented. The star's light curves since 1973 from the Crimean observations are shown. The brightness decline after its outburst over the last 40 years was . The phase color curves at phases 0.2 and 0.8 have maxima. Their qualitative interpretation in terms of the model of interacting winds in symbiotic binary star systems is proposed. The orbital period of the binary system has been redetermined. The spectroscopic observations at the 125-cm telescope of the Crimean Station from 1994 to 2014 have confirmed the change in the system's emission spectrum with orbital phase. The HI, He I, and Fe II line fluxes clearly trace the orbital motion. The Balmer hydrogen lines as well as the continuum at λ6000 and the V-band flux change by a factor of ˜3.5 from minimum to maximum light. The neutral helium lines change by a factor of 5. The high-excitation He II, [FeVII], [Ca VII] lines and the Raman O VI λ6825 line have shown changes in the fluxes by a factor of ˜2-3 weakly correlating with the orbital phase. The equivalent widths of the HI and He I lines are maximal at the star's maximum light and have distinct minima at phases 0.2 and 0.8, while the equivalent widths of the He II, [FeVII], and [CaVII] lines are minimal in the range of phases 0.2-0.8. The question about the location of the permitted and forbidden line emission zones in the binary system V1329 Cyg is discussed. The evolution of the emission spectrum for V1329 Cyg from 1980 to 2014 has been studied on the basis of new and archival data. A gradual decrease in the absolute fluxes of the nebular emission lines has been detected. The [O III] and [Fe VII] lines have weakened significantly. However, the [Fe X] λ6375 Å line has appeared and gradually strengthened, suggesting an increase in the degree of gas ionization in the line formation zone.

Spectral broadening of optical transitions in InAs/GaAs coupled quantum dot pairs

NASA Astrophysics Data System (ADS)

Kumar, P.; Czarnocki, C.; Jennings, C.; Casara, J.; Monteros, A. L.; Zahbihi, N.; Scheibner, M.; Economou, S. E.; Bracker, A. S.; Pursley, B. C.; Gammon, D.; Carter, S. G.

The optical transitions in InAs/GaAs coupled quantum dot (CQD) pairs are investigated experimentally. These coupled dot systems provide new means to study the interaction of quantum states with the mechanical modes of the crystal environment. Here, the line width and line shape of CQD optical transitions are analyzed in detail as a function of temperature, excitation power, excitation energy, and tunnel coupling strength. A significant line broadening, up to 25 times the typical lifetime-limited linewidth of single-dot excitons, is being observed at level anti-crossings where the coherent tunnel coupling between spatially direct and indirect exciton states is considerable. The experimental observations are compared with theoretical predictions where linewidth broadening at anti-crossings is attributed to the phonon assisted transitions, and found to be strongly dependent on the energy splitting of the two exciton branches. This work focuses on understanding the linewidth broadening due to the pure dephasing, and fundamental aspects of the interaction of these systems with the local environment. This work was supported by the Defense Threat Reduction Agency, Basic Research Award HDTRA1-15-1-0011.

PG 0308 + 096 and PG 1026 + 002 - Two new short period binary stars resulting from common-envelope evolution

NASA Technical Reports Server (NTRS)

Saffer, Rex A.; Wade, Richard A.; Liebert, James; Green, Richard F.; Sion, Edward M.; Bechtold, J.; Foss, Diana; Kidder, K.

1993-01-01

Ultraviolet spectroscopy, optical spectroscopy, and spectrophotometry have been used to study the excess UV stars PG 0308 + 096 and PG 1026 + 002. Both objects are short-period binary systems, each containing a DA white dwarf star and a dM star. Orbital periods of approximately 0.284 day for PG 0308 + 096, and aproximately 0.597 day for PG 1026, have been found by spectroscopic analysis of the H-alpha emission line. Ly-alpha and Balmer line profile fitting were used to estimate the mass of white dwarf stars; mass estimates for the dM stars are based on their spectral types. The orbital inclinations are derived from these masses, the periods, and amplitudes of the H-alpha radial velocity curves. The equivalent width of the H-alpha emission line, in each binary system, varies with the orbital phase in such a manner as to imply that it arises, in large part at least, from the hemisphere of the M star that faces the white dwarf star.

Ein statistisches Modell zum Einfluß der thermischen Bewegung auf NMR-Festkörperspektren

NASA Astrophysics Data System (ADS)

Ploss, W.; Freude, D.; Pfeifer, H.; Schmiedel, H.

Es wird ein statistisches Modell zum Einfluß der thermischen Bewegung auf die NMR-Linienform vorgestellt, das die Verschmälerung von Festkörper-Spektren bei wachsender Temperatur beschreibt. Das Modell geht von der Annahme aus, daß nach einer Ortsveränderung eines Kerns infolge thermischer Bewegung jede beliebige Kernresonanzfrequenz mit der durch das Festkörperspektrum vorgegebenen Wahrscheinlichkeit angenommen werden kann. Am Beispiel der Festkörper-Gaußlinie wird der Unterschied zu dem bekannten Modell von ANDERSON und WEISS verdeutlicht.Translated AbstractA Statistical Model for the Influence of Thermal Motion on N. M. R. Spectra in SolidsA theory is proposed which allows to describe the narrowing of n. m. r.-line width in the presence of thermal motions of the spins. The model is based on the assumption, that the local resonance frequency of a given spin immediately after the jump is distributed according to the n. m. r.-line shape of the rigid lattice. The difference to the well-known ANDERSON-WEISS-model of spectral narrowing is demonstrated for a gaussian line shape.

The Mysterious 6565 Å Absorption Feature of the Galactic Halo

NASA Astrophysics Data System (ADS)

Sethi, Shiv K.; Shchekinov, Yuri; Nath, Biman B.

2017-12-01

We consider various possible scenarios to explain the recent observation of what has been called a broad Hα absorption in our Galactic halo, with peak optical depth τ ≃ 0.01 and equivalent width W≃ 0.17 \\mathringA . We show that the absorbed feature cannot arise from the circumgalactic and ISM Hα absorption. As the observed absorption feature is quite broad ({{Δ }}λ ≃ 30 \\mathringA ), we also consider CNO lines that lie close to Hα as possible alternatives to explain the feature. We show that such lines could also not account for the observed feature. Instead, we suggest that it could arise from diffuse interstellar bands (DIBs) carriers or polyaromatic hydrocarbons (PAHs) absorption. While we identify several such lines close to the Hα transition, we are unable to determine the molecule responsible for the observed feature, partly because of selection effects that prevent us from identifying DIBs/PAHs features close to Hα using local observations. Deep integration of a few extragalactic sources with high spectral resolution might allow us to distinguish between different possible explanations.

Relativistic redshifts in quasar broad lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tremaine, Scott; Shen, Yue; Liu, Xin

2014-10-10

The broad emission lines commonly seen in quasar spectra have velocity widths of a few percent of the speed of light, so special- and general-relativistic effects have a significant influence on the line profile. We have determined the redshift of the broad Hβ line in the quasar rest frame (determined from the core component of the [O III] line) for over 20,000 quasars from the Sloan Digital Sky Survey Data Release 7 quasar catalog. The mean redshift as a function of line width is approximately consistent with the relativistic redshift that is expected if the line originates in a randomlymore » oriented Keplerian disk that is obscured when the inclination of the disk to the line of sight exceeds ∼30°-45°, consistent with simple active galactic nucleus unification schemes. This result also implies that the net line-of-sight inflow/outflow velocities in the broad-line region are much less than the Keplerian velocity when averaged over a large sample of quasars with a given line width.« less

Spectroscopic line parameters of 12CH4 for atmospheric composition retrievals in the 4300-4500 cm-1 region

NASA Astrophysics Data System (ADS)

Hashemi, R.; Predoi-Cross, A.; Nikitin, A. V.; Tyuterev, Vl. G.; Sung, K.; Smith, M. A. H.; Malathy Devi, V.

2017-01-01

Due to the importance of methane as a trace atmospheric gas and a greenhouse gas, we have carried out a precise line-shape study to obtain the CH4-CH4 and CH4-air half-width coefficients, CH4-CH4 and CH4-air shift coefficients and off-diagonal relaxation matrix element coefficients for methane transitions in the spectral range known as the "methane Octad". In addition, the associated temperature dependences of these coefficients have been measured in the 4300-4500 cm-1 region of the Octad. The high signal to noise ratio spectra of pure methane and of dilute mixtures of methane in dry air with high resolution have been recorded at temperatures from 148 K to room temperature using the Bruker IFS 125 HR Fourier transform spectrometer (FTS) at the Jet Propulsion Laboratory, Pasadena, California. The analysis of spectra was done using a multispectrum non-linear least-squares curve fitting technique. Theoretical calculations have been performed and the results are compared with the previously published line positions, intensities and with the line parameters available in the GEISA and HITRAN2012 databases.

Laser-induced breakdown spectroscopy measurement of a small fraction of rhenium in bulk tungsten

NASA Astrophysics Data System (ADS)

Nishijima, D.; Ueda, Y.; Doerner, R. P.; Baldwin, M. J.; Ibano, K.

2018-03-01

Laser-induced breakdown spectroscopy (LIBS) of bulk rhenium (Re) and tungsten (W)-Re alloy has been performed using a Q-switched Nd:YAG laser (wavelength = 1064 nm, pulse width ∼4-6 ns, laser energy = 115 mJ). It is found that the electron temperature, Te, of laser-induced Re plasma is lower than that of W plasma, and that Te of W-Re plasma is in between Re and W plasmas. This indicates that material properties affect Te in a laser-induced plasma. For analysis of W-3.3%Re alloy, only the strongest visible Re I 488.9 nm line is found to be used because of the strong enough intensity without contamination with W lines. Using the calibration-free LIBS method, the atomic fraction of Re, cRe, is evaluated as a function of the ambient Ar gas pressure, PAr. At PAr < 10 Torr, LIBS-measured cRe agrees well with that from EDX (energy-dispersive X-ray micro-analysis), while cRe increases with an increase in PAr at >10 Torr due to spectral overlapping of the Re I 488.9 nm line by an Ar II 488.9 nm line.

Characterization of lunar ferromagnetic phases by the effective linewidth method

NASA Technical Reports Server (NTRS)

Patton, C. E.; Schmidt, H.

1978-01-01

The effective line-width technique, first developed to study the physics of microwave relaxation in ferrites, has been successfully applied to lunar matter. Effective line-width measurements have been made on two selected samples containing disperse spherical metallic iron particles below 40 microns in diam. The data were obtained for fields from 7 to 12 kOe and a temperature range 125 - 300 K. The effective line width was field-independent and temperature-independent at 650 - 750 Oe. The high-field tails of the ferromagnetic resonance absorption were highly Lorentzian. From the relatively large and temperature-independent high-field effective line widths, it appears that (1) the metallic iron phases in lunar soil are rather impure; (2) the impurities are passive, in that there is no evidence for a temperature peak process; and (3) these samples contain no appreciable magnetite.

Comparison of Trajectory Models in Calculations of N2-broadened Half-widths and N2-induced Line Shifts for the Rotational Band of H2O-16 and Comparison with Measurements

NASA Technical Reports Server (NTRS)

Lamouroux, J.; Gamache, R. R.; Laraia, A. L.; Ma, Q.; Tipping, R. H.

2012-01-01

In this work, Complex Robert-Bonamy calculations of half-widths and line shifts were done for N2-broadening of water for 1639 transitions in the rotational band using two models for the trajectories. The first is a model correct to second order in time, the Robert-Bonamy parabolic approximation. The second is the solution of Hamilton's equations. Both models use the isotropic part of the atom-atom potential to determine the trajectories. The present calculations used an intermolecular potential expanded to 20th order to assure the convergence of the half-widths and line shifts. The aim of the study is to assess if the difference in the half-widths and line shifts determined from the two trajectory models is greater than the accuracy requirements of the spectroscopic and remote sensing communities. The results of the calculations are compared with measurements of the half-widths and line shifts. It is shown that the effects of the trajectory model greatly exceed the needs of current remote sensing measurements and that line shape parameters calculated using trajectories determined by solving Hamilton's equations agree better with measurement.

UVSTAR: An imaging spectrograph with telescope for the Shuttle Hitchhiker-M platform

NASA Technical Reports Server (NTRS)

Stalio, Roberto; Sandel, Bill R.; Broadfoot, A. Lyle

1993-01-01

UVSTAR is an EUV spectral imager intended as a facility instrument devoted to solar system and astronomy studies. It covers the wavelength range of 500 to 1250 A, with sufficient spectral resolution to separate emission lines and to form spectrally resolved images of extended plasma sources. Targets include the Io plasma torus at Jupiter, hot stars, planetary nebulae and bright galaxies. UVSTAR consists of a pair of telescopes and concave grating spectrographs that cover the overlapping spectral ranges of 500-900 and 850-1250 A. The telescopes use two 30 cm diameter off-axis paraboloids having focal length of 1.5 m. An image of the target is formed at the entrance slits of the two concave grating spectrographs. The gratings provide dispersion and re-image the slits at the detectors, intensified CCD's. The readout format of the detectors can be chosen by computer, and three slit widths are selectable to adapt the instrument to specific tasks. UVSTAR has internal gimbals which allow rotation of plus or minus 3 deg about each of two axes. Dedicated finding and tracking telescopes will acquire and track the target after rough pointing is achieved by orienting the Orbiter. Responsibilities for implementation and utilization of UVSTAR are shared by groups in Italy and the U.S. UVSTAR is scheduled for flight in early 1995, timed for an opportunity to observe the Jovian system.

Non-Markovianity of the damped Jaynes-Cummings model with detuning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li Jungang; Zou Jian; Shao Bin

2010-06-15

The degree of non-Markovian behavior of a damped Jaynes-Cummings model with detuning is investigated. Our attention is focused on the effects of the detuning and the width of the Lorentzian spectral density on the degree of non-Markovian behavior. It is found that an increase of the detuning can make the information exchange between the qubit and the reservoir more rapid, and this leads to an increase in the degree of non-Markovianity for some cases, while an increase of the spectral width always leads to a decrease in the degree of non-Markovianity.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Siyao; Lazarian, A.; Yan, Huirong, E-mail: hryan@pku.edu.cn

We address the problem of the different line widths of coexistent neutrals and ions observed in molecular clouds and explore whether this difference can arise from the effects of magnetohydrodynamic (MHD) turbulence acting on partially ionized gas. Among the three fundamental modes of MHD turbulence, we find that fast and slow modes do not contribute to line width differences. We focus on the Alfvénic component, and consider the damping of Alfvén modes by taking into account both neutral-ion collisions and neutral viscosity. We confirm that the line width difference can be explained by the differential damping of the Alfvénic turbulencemore » in ions and the hydrodynamic turbulence in neutrals, and find it strongly depends on the properties of MHD turbulence. We consider various regimes of turbulence corresponding to different media magnetizations and turbulent drivings. In the case of super-Alfvénic turbulence, when the damping scale of Alfvénic turbulence is below the Alfvénic scale l{sub A}, the line width difference does not depend on magnetic field strength. In other turbulence regimes, however, the dependence is present and evaluation of magnetic field from the observed line width difference is possible.« less

Relativistic Iron Emission and Disk Reflection in Galactic Microquasar XTE J1748-288

NASA Technical Reports Server (NTRS)

Miller, J. M.; Fox, D. W.; Matteo, T. DI; Wijnands, R.; Belloni, T.; Pooley, D.; Kouveliotou, C.; Lewin, W. H. G.

2001-01-01

We report evidence for an Fe K(alpha) fluorescence line feature and disk reflection in the very high, high-, and low-state X-ray spectra of the Galactic microquasar XTE J1748-288 during its 1998 June outburst. Spectral analyses are made on data gathered throughout the outburst by the Rossi X-Ray Timing Explorer Proportional Counter Array. Gaussian line, relativistic disk emission line, and ionized disk reflection models are fitted to the data. In the very high state the line profile appears strongly redshifted, consistent with disk emission from the innermost stable orbits around a maximally rotating Kerr black hole. In the high state the line profile is less redshifted and increasingly prominent. The low-state line profile is very strong (approx. 0.5 keV equivalent width) and centered at 6.7 +/- 0.10 keV; disk line emission model fits indicate that the inner edge of the disk fluctuates between approx. 20Rg and approx. 100Rg in this state. The disk reflection fraction is traced through the outburst; reflection from an ionized disk is preferred in the very high and high states, and reflection from a relatively neutral disk is preferred in the low state. We discuss the implications of our findings for the binary system dynamics and accretion flow geometry in XTE J1748-288.

Relativistic Iron Emission and Disk Reflection in Galactic Microquasar XTE J1748-288

NASA Technical Reports Server (NTRS)

Miller, J. M.; Fox, D. W.; DiMatteo, T.; Wijnands, R.; Belloni, T.; Pooley, D.; Kouveliotou, C.; Lewin, W. H. G.

2001-01-01

We report evidence for an Fe K-alpha fluorescence line feature and disk reflection in the very high, high-, and low-state X-ray spectra of the Galactic microquasar XTE J1748 - 288 during its 1998 June outburst. Spectral analyses are made on data gathered throughout the outburst by the Rossi X-Ray Timing Explorer Proportional Counter Array. Gaussian line, relativistic disk emission line, and ionized disk reflection models are fitted to the data. In the very high state the line profile appears strongly redshifted, consistent with disk emission from the innermost stable orbits around a maximally rotating Kerr black hole. In the high state the line profile is less redshifted and increasingly prominent. The low-state line profile is very strong (approx. 0.5 keV equivalent width) and centered at 6.7 +/- 0.10 keV; disk line emission model fits indicate that the inner edge of the disk fluctuates between approx. 20R(sub g) and - approx. 100R(sub g) in this state. The disk reflection fraction is traced through the outburst; reflection from an ionized disk is preferred in the very high and high states, and reflection from a relatively neutral disk is preferred in the low state. We discuss the implications of our findings for the binary system dynamics and accretion flow geometry in XTE J1748 - 288.

Measurement of acrolein and 1,3-butadiene in a single puff of cigarette smoke using lead-salt tunable diode laser infrared spectroscopy.

PubMed

Thweatt, W Dave; Harward, Charles N; Parrish, Milton E

2007-05-01

Acrolein and 1,3-butadiene in cigarette smoke generally are measured using two separate analytical methods, a carbonyl derivative HPLC method for acrolein and a volatile organic compound (VOC) GC/MS method for 1,3-butadiene. However, a single analytical method having improved sensitivity and real-time per puff measurement will offer more specific information for evaluating experimental carbon filtered cigarettes designed to reduce the smoke deliveries of these constituents. This paper describes an infrared technique using two lead-salt tunable diode lasers (TDLs) operating with liquid nitrogen cooling with emissions at 958.8 cm(-1) and 891.0 cm(-1) respectively for the simultaneous measurement of acrolein and 1,3-butadiene, respectively, in each puff of mainstream cigarette smoke in real time. The dual TDL system uses a 3.1l volume, 100 m astigmatic multiple pass absorption gas cell. Quantitation is based on a spectral fit that uses previously determined infrared molecular line parameters generated in our laboratory, including line positions, line strengths and nitrogen-broadened half-widths for these species. Since acrolein and ethylene absorption lines overlap and 1,3-butadiene, ethylene and propylene absorption lines overlap, the per puff deliveries of ethylene and propylene were determined since their overlapping absorption lines must be taken into account by the spectral fit. The acrolein and 1,3-butadiene total cigarette deliveries for the 1R5F Kentucky Reference cigarette were in agreement with the HPLC and GC/MS methods, respectively. The limit of detection (LOD) for 1,3-butadiene and acrolein was 4 ng/puff and 24 ng/puff, respectively, which is more than adequate to determine at which puff they break through the carbon filter. The retention and breakthrough behavior for the two primary smoke constituents depend on the cigarette design and characteristics of the carbon filter being evaluated.

Measurement of acrolein and 1,3-butadiene in a single puff of cigarette smoke using lead-salt tunable diode laser infrared spectroscopy

NASA Astrophysics Data System (ADS)

Thweatt, W. Dave; Harward, Charles N., Sr.; Parrish, Milton E.

2007-05-01

Acrolein and 1,3-butadiene in cigarette smoke generally are measured using two separate analytical methods, a carbonyl derivative HPLC method for acrolein and a volatile organic compound (VOC) GC/MS method for 1,3-butadiene. However, a single analytical method having improved sensitivity and real-time per puff measurement will offer more specific information for evaluating experimental carbon filtered cigarettes designed to reduce the smoke deliveries of these constituents. This paper describes an infrared technique using two lead-salt tunable diode lasers (TDLs) operating with liquid nitrogen cooling with emissions at 958.8 cm -1 and 891.0 cm -1 respectively for the simultaneous measurement of acrolein and 1,3-butadiene, respectively, in each puff of mainstream cigarette smoke in real time. The dual TDL system uses a 3.1 l volume, 100 m astigmatic multiple pass absorption gas cell. Quantitation is based on a spectral fit that uses previously determined infrared molecular line parameters generated in our laboratory, including line positions, line strengths and nitrogen-broadened half-widths for these species. Since acrolein and ethylene absorption lines overlap and 1,3-butadiene, ethylene and propylene absorption lines overlap, the per puff deliveries of ethylene and propylene were determined since their overlapping absorption lines must be taken into account by the spectral fit. The acrolein and 1,3-butadiene total cigarette deliveries for the 1R5F Kentucky Reference cigarette were in agreement with the HPLC and GC/MS methods, respectively. The limit of detection (LOD) for 1,3-butadiene and acrolein was 4 ng/puff and 24 ng/puff, respectively, which is more than adequate to determine at which puff they break through the carbon filter. The retention and breakthrough behavior for the two primary smoke constituents depend on the cigarette design and characteristics of the carbon filter being evaluated.

Improving atmospheric CO2 retrievals using line mixing and speed-dependence when fitting high-resolution ground-based solar spectra

NASA Astrophysics Data System (ADS)

Mendonca, J.; Strong, K.; Toon, G. C.; Wunch, D.; Sung, K.; Deutscher, N. M.; Griffith, D. W. T.; Franklin, J. E.

2016-05-01

A quadratic speed-dependent Voigt spectral line shape with line mixing (qSDV + LM) has been included in atmospheric trace-gas retrievals to improve the accuracy of the calculated CO2 absorption coefficients. CO2 laboratory spectra were used to validate absorption coefficient calculations for three bands: the strong 20013 ← 00001 band centered at 4850 cm-1, and the weak 30013 ← 00001 and 30012 ← 00001 bands centered at 6220 cm-1 and 6340 cm-1 respectively, and referred to below as bands 1 and 2. Several different line lists were tested. Laboratory spectra were best reproduced for the strong CO2 band when using HITRAN 2008 spectroscopic data with air-broadened widths divided by 0.985, self-broadened widths divided by 0.978, line mixing coefficients calculated using the exponential power gap (EPG) law, and a speed-dependent parameter of 0.11 used for all lines. For the weak CO2 bands, laboratory spectra were best reproduced using spectroscopic parameters from the studies by Devi et al. in 2007 coupled with line mixing coefficients calculated using the EPG law. A total of 132,598 high-resolution ground-based solar absorption spectra were fitted using qSDV + LM to calculate CO2 absorption coefficients and compared to fits that used the Voigt line shape. For the strong CO2 band, the average root mean square (RMS) residual is 0.49 ± 0.22% when using qSDV + LM to calculate the absorption coefficients. This is an improvement over the results with the Voigt line shape, which had an average RMS residual of 0.60 ± 0.21%. When using the qSDV + LM to fit the two weak CO2 bands, the average RMS residual is 0.47 ± 0.19% and 0.51 ± 0.20% for bands 1 and 2, respectively. These values are identical to those obtained with the Voigt line shape. Finally, we find that using the qSDV + LM decreases the airmass dependence of the column averaged dry air mole fraction of CO2 retrieved from the strong and both weak CO2 bands when compared to the retrievals obtained using the Voigt line shape.

CA II K-line metallicity indicator for field RR Lyrae stars

NASA Astrophysics Data System (ADS)

Clementini, Gisella; Tosi, Monica; Merighi, Roberto

In order to check and, possibly, improve the Preston's Delta S calibration scale, CCD spectra have been obtained for 25 field RR Lyrae variables. Eleven of the program stars have values of (Fe/H) derived by Butler and Deming (1979) from the Fe II lines' strength. For them we find that the equivalent width of the Ca II K line is extremely well correlated to the (Fe/H) values, the best fit relation being: (Fe/H) = 0.43W(K) - 2.75 where W(K) is the equivalent width of the K line. We conclude that the use of the K line equivalent width is at present the best method to derive the (Fe/H) abundance of the RR Lyrae stars.

- and Air-Broadened Line Shape Parameters of 12CH_4 : 4500-4620 CM-1

NASA Astrophysics Data System (ADS)

Devi, V. Malathy; Benner, D. Chris; Sung, Keeyoon; Brown, Linda; Crawford, Timothy J.; Smith, Mary Ann H.; Mantz, Arlan; Predoi-Cross, Adriana

2014-06-01

Accurate knowledge of spectral line shape parameters is important for infrared transmission and radiance calculations in the terrestrial atmosphere. We report the self- and air-broadened Lorentz widths, shifts and line mixing coefficients along with their temperature dependences for methane absorption lines in the 2.2 μm spectral region. For this, we obtained a series of high-resolution, high S/N spectra of 99.99% 12C-enriched samples of pure methane and its dilute mixtures in dry air at cold temperatures down to 150 K using the Bruker IFS 125HR Fourier transform spectrometer at JPL. The coolable absorption cell had an optical path of 20.38 cm and was specially built to reside inside the sample compartment of the Bruker FTS. The 13 spectra used in the analysis consisted of seven pure 12CH_4 spectra at pressures from 4.5 to 169 Torr and six air-broadened spectra with total sample pressures of 113-300 Torr and methane volume mixing ratios between 4 and 9.7%. These 13 spectra were fit simultaneously using the multispectrum least-squares fitting technique. The results will be compared to existing values reported in the literature. K. Sung, A. W. Mantz, L. R. Brown, et al., J. Mol. Spectrosc., 162 (2010) 124-134. D. C. Benner, C. P. Rinsland, V. Malathy Devi, M. A. H. Smith and D. Atkins, JQSRT, 53 (1995) 705-721. Research described in this paper was performed at Connecticut College, the College of William and Mary, NASA Langley Research Center and the Jet Propulsion Laboratory, California Institute of Technology, under contracts and cooperative agreements with the National Aeronautics and Space Administration.

Pressure broadening of the electric dipole and Raman lines of CO2 by argon: Stringent test of the classical impact theory at different temperatures on a benchmark system

NASA Astrophysics Data System (ADS)

Ivanov, Sergey V.; Buzykin, Oleg G.

2016-12-01

A classical approach is applied to calculate pressure broadening coefficients of CO2 vibration-rotational spectral lines perturbed by Ar. Three types of spectra are examined: electric dipole (infrared) absorption; isotropic and anisotropic Raman Q branches. Simple and explicit formulae of the classical impact theory are used along with exact 3D Hamilton equations for CO2-Ar molecular motion. The calculations utilize vibrationally independent most accurate ab initio potential energy surface (PES) of Hutson et al. expanded in Legendre polynomial series up to lmax = 24. New improved algorithm of classical rotational frequency selection is applied. The dependences of CO2 half-widths on rotational quantum number J up to J=100 are computed for the temperatures between 77 and 765 K and compared with available experimental data as well as with the results of fully quantum dynamical calculations performed on the same PES. To make the picture complete, the predictions of two independent variants of the semi-classical Robert-Bonamy formalism for dipole absorption lines are included. This method. however, has demonstrated poor accuracy almost for all temperatures. On the contrary, classical broadening coefficients are in excellent agreement both with measurements and with quantum results at all temperatures. The classical impact theory in its present variant is capable to produce quickly and accurately the pressure broadening coefficients of spectral lines of linear molecules for any J value (including high Js) using full-dimensional ab initio - based PES in the cases where other computational methods are either extremely time consuming (like the quantum close coupling method) or give erroneous results (like semi-classical methods).

Hot molecular hydrogen in the central parsec of the Galaxy through near-infrared 3D fitting

NASA Astrophysics Data System (ADS)

Ciurlo, A.; Paumard, T.; Rouan, D.; Clénet, Y.

2016-10-01

Aims: We have investigated neutral gas in the central cavity of the circumnuclear disk (CND) at the Galactic center, where the ionized minispiral lies, to describe the H2 distribution and properties in this ionized environment. Methods: This study was carried out through a spectro-imaging data cube of the central cavity obtained with SPIFFI on the VLT. The observed field of view is 36″ × 29″, with a spectral resolution R = 1300 in the near-infrared. These observations cover several H2 lines. To preserve the spatial resolution and avoid edge effects, we applied a new line-fitting method that consists of a regularized 3D fitting. We also applied a more classical 1D fitting to compare the relative strength of the H2 lines. Results: We present high spatial and spectral resolution maps of the intensity, velocity, and width of five H2 lines and an extinction map derived from H2. Molecular gas is detected everywhere in the field. In particular, in addition to the known CND features, we detected an emission from the northern arm cloud and from the minicavity. The excitation diagrams allow us to estimate the temperature, mass, and density of these features. Conclusions: We interpret the CND emission as coming from a hot, thermalized, thin layer at the surface of the clouds. The observed H2 corresponds only to a small fraction of the total H2 mass. The emission remains fairly strong in the whole central cavity, but it is not thermalized. A strong deviation from thermal equilibrium is detected near the minicavity. We suggest that this emission is caused by constantly forming H2 that is destroyed again before it reaches ortho/para equilibrium.

High-cadence observations of spicular-type events and their wave-signatures

NASA Astrophysics Data System (ADS)

Shetye, Juie

2016-05-01

We present, a statistical study of spectral images, taken from the CRISP instrument at the Swedish 1-m Solar Telescope in H-alpha 656.28 nm of fast spicules with Doppler velocities in the range of -41km/s to +41 km/s. Remarkably, many of these spicules display apparent velocities above 500 km/s, very short lifetimes of up to 20 s combined with width or thickness of 100 km and apparent lengths of around 3500 km. Here we present, the other spectral properties of these events in the H-alpha line scan. Most features showed signature in multiple line position as we scan along the line scan. In around 89 % of the cases, there is temporal offset by 3.7 s to 5 s between the red-wing and blue-wing signatures. Another result is that 25% of cases are repetitive i.e. appear at the same location but they are not co-temporal or necessarily periodic in nature. Putting all the evidence together, we interpret the observations as mass motions (of flux tubes) that appear in the field-of-view of CRISP’s 0.0060 nm filters in the line of sight, along their projection as we scan. Further we observed transverse motion associated with these structures, which in some cases could be related to high-frequency kink-waves. We describe some cases showing this motion and the energies associated with them. The current work presented already tests the limits of current telescopes in terms of the temporal and spatial resolution. DKIST VTF instrument, having 3 times more spatial resolution than CRISP and much higher temporal resolution, we can being to understand the nature of such fine-scale transient phenomena in greater details.

Supplement Analysis for the Transmission System Vegetation Management Program FEIS (DOE/EIS-0285/SA-192- Ashe-Hanford/Scooteney-Tap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hutchinson, Ken

2004-01-26

Vegetation Management for the Ashe-Hanford (tower 13/1 to 15/2) and Scooteney Tap (tower 2/1+1200 to 4/1+50) line corridor. The Ashe-Hanford line is a 500 kV single circuit transmission line having an easement width of 350 feet. The Scooteney Tap line is a 230 kV single circuit line having an easement width of 262.5 feet on the Department of Energy’s Hanford Nuclear Reservation (Reservation) and an easement width of 100 feet on private lands. The proposed work will be accomplished in the indicated sections of the transmission lines as referenced on the attached checklist. The work will include the performance ofmore » tower pad maintenance and access road maintenance in the referenced areas. Maintenance will include the control of all brush species within 30 feet of transmission structures and controlling all vegetation, except grass along the access roads to provide a 14-foot width for travel. Noxious weed management will also occur on the rights-of- way where needed.« less

Maxillary Arch Dimensions and Spectral Characteristics of Children with Cleft Lip and Palate Who Produce Middorsum Palatal Stops

ERIC Educational Resources Information Center

Zajac, David J.; Cevidanes, Lucia; Shah, Sonam; Haley, Katarina L.

2012-01-01

Purpose: The purpose of this study was twofold: (a) to determine maxillary arch dimensions of children with repaired cleft lip and palate (CLP) who produced middorsum palatal stops and (b) to describe some spectral characteristics of middorsum palatal stops. Method: Maxillary arch width, length, and height dimensions and first spectral moments of…

Time scale variations of the physical parameters of the Si IV resonance lines in the case of the Be star HD 50138

NASA Astrophysics Data System (ADS)

Stathopoulos, D.

2012-01-01

As it is well known many lines in the spectra of hot emission stars (Be and Oe) present peculiar and very complex profiles. As a result, we cannot find a classical theoretical distribution in order to fit these profiles. Because of this, we are not able to calculate the physical parameters of the regions were these lines are created. In this paper, using the Gauss-Rotation model (GR-model Danezis et al), that proposed the idea that these complex profiles consist of a number of independent Discrete or Satellite Absorption Components (DACs, SACs), we study the UV Si IV (λλ 1393.755, 1402.77 A) resonance lines of the Be star HD 50138 in three different periods. From this analysis we can calculate the values of a group of physical parameters. The parameters are the apparent rotational and radial velocities, the random velocities of the thermal motions of the ions, as well as the Full Width at Half Maximum (FWHM) an the absorbed energy of the independent regions of matter which produce the main and the satellite components of the studied spectral line. Finally we calculate the time scale variations of the above physical parameters.

Quadrupole splittings in the near-infrared spectrum of 14NH 3

DOE PAGES

Twagirayezu, Sylvestre; Hall, Gregory E.; Sears, Trevor J.

2016-10-13

Sub-Doppler, saturation dip, spectra of lines in the v 1 + v 3, v 1 + 2v 4 and v 3 + 2v 4 bands of 14NH 3 have been measured by frequency comb-referenced diode laser absorption spectroscopy. The observed spectral line widths are dominated by transit time broadening, and show resolved or partially-resolved hyperfine splittings that are primarily determined by the 14N quadrupole coupling. Modeling of the observed line shapes based on the known hyperfine level structure of the ground state of the molecule shows that, in nearly all cases, the excited state level has hyperfine splittings similar tomore » the same rotational level in the ground state. The data provide accurate frequencies for the line positions and easily separate lines overlapped in Doppler-limited spectra. The observed hyperfine splittings can be used to make and confirm rotational assignments and ground state combination differences obtained from the measured frequencies are comparable in accuracy to those obtained from conventional microwave spectroscopy. Furthermore, several of the measured transitions do not show the quadrupole hyperfine splittings expected based on their existing rotational assignments. Either the assignments are incorrect or the upper levels involved are perturbed in a way that affects the nuclear hyperfine structure.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kitiashvili, I. N.; Couvidat, S.; Lagg, A.

The solar atmosphere is extremely dynamic, and many important phenomena develop on small scales that are unresolved in observations with the Helioseismic and Magnetic Imager (HMI) instrument on the Solar Dynamics Observatory. For correct calibration and interpretation of the observations, it is very important to investigate the effects of small-scale structures and dynamics on the HMI observables, such as Doppler shift, continuum intensity, spectral line depth, and width. We use 3D radiative hydrodynamics simulations of the upper turbulent convective layer and the atmosphere of the Sun, and a spectro-polarimetric radiative transfer code to study observational characteristics of the Fe imore » 6173 Å line observed by HMI in quiet-Sun regions. We use the modeling results to investigate the sensitivity of the line Doppler shift to plasma velocity, and also sensitivities of the line parameters to plasma temperature and density, and determine effective line formation heights for observations of solar regions located at different distances from the disk center. These estimates are important for the interpretation of helioseismology measurements. In addition, we consider various center-to-limb effects, such as convective blueshift, variations of helioseismic travel-times, and the “concave” Sun effect, and show that the simulations can qualitatively reproduce the observed phenomena, indicating that these effects are related to a complex interaction of the solar dynamics and radiative transfer.« less

Hyperspectral Analysis of Soil Nitrogen, Carbon, Carbonate, and Organic Matter Using Regression Trees

PubMed Central

Gmur, Stephan; Vogt, Daniel; Zabowski, Darlene; Moskal, L. Monika

2012-01-01

The characterization of soil attributes using hyperspectral sensors has revealed patterns in soil spectra that are known to respond to mineral composition, organic matter, soil moisture and particle size distribution. Soil samples from different soil horizons of replicated soil series from sites located within Washington and Oregon were analyzed with the FieldSpec Spectroradiometer to measure their spectral signatures across the electromagnetic range of 400 to 1,000 nm. Similarity rankings of individual soil samples reveal differences between replicate series as well as samples within the same replicate series. Using classification and regression tree statistical methods, regression trees were fitted to each spectral response using concentrations of nitrogen, carbon, carbonate and organic matter as the response variables. Statistics resulting from fitted trees were: nitrogen R2 0.91 (p < 0.01) at 403, 470, 687, and 846 nm spectral band widths, carbonate R2 0.95 (p < 0.01) at 531 and 898 nm band widths, total carbon R2 0.93 (p < 0.01) at 400, 409, 441 and 907 nm band widths, and organic matter R2 0.98 (p < 0.01) at 300, 400, 441, 832 and 907 nm band widths. Use of the 400 to 1,000 nm electromagnetic range utilizing regression trees provided a powerful, rapid and inexpensive method for assessing nitrogen, carbon, carbonate and organic matter for upper soil horizons in a nondestructive method. PMID:23112620

Wall-resolved spectral cascade-transport turbulence model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, C. S.; Shaver, D. R.; Lahey, R. T.

A spectral cascade-transport model has been developed and applied to turbulent channel flows (Reτ= 550, 950, and 2000 based on friction velocity, uτ ; or ReδΜ= 8,500; 14,800 and 31,000, based on the mean velocity and channel half-width). This model is an extension of a spectral model previously developed for homogeneous single and two-phase decay of isotropic turbulence and uniform shear flows; and a spectral turbulence model for wall-bounded flows without resolving the boundary layer. Data from direct numerical simulation (DNS) of turbulent channel flow was used to help develop this model and to assess its performance in the 1Dmore » direction across the channel width. The resultant spectral model is capable of predicting the mean velocity, turbulent kinetic energy and energy spectrum distributions for single-phase wall-bounded flows all the way to the wall, where the model source terms have been developed to account for the wall influence. We implemented the model into the 3D multiphase CFD code NPHASE-CMFD and the latest results are within reasonable error of the 1D predictions.« less

Wall-resolved spectral cascade-transport turbulence model

DOE PAGES

Brown, C. S.; Shaver, D. R.; Lahey, R. T.; ...

2017-07-08

A spectral cascade-transport model has been developed and applied to turbulent channel flows (Reτ= 550, 950, and 2000 based on friction velocity, uτ ; or ReδΜ= 8,500; 14,800 and 31,000, based on the mean velocity and channel half-width). This model is an extension of a spectral model previously developed for homogeneous single and two-phase decay of isotropic turbulence and uniform shear flows; and a spectral turbulence model for wall-bounded flows without resolving the boundary layer. Data from direct numerical simulation (DNS) of turbulent channel flow was used to help develop this model and to assess its performance in the 1Dmore » direction across the channel width. The resultant spectral model is capable of predicting the mean velocity, turbulent kinetic energy and energy spectrum distributions for single-phase wall-bounded flows all the way to the wall, where the model source terms have been developed to account for the wall influence. We implemented the model into the 3D multiphase CFD code NPHASE-CMFD and the latest results are within reasonable error of the 1D predictions.« less

Theoretical Models of Low-Resolution Microwave Rotational Spectra of Ethane- and Propanethiol

NASA Astrophysics Data System (ADS)

Kadjar, Ch. O.; Kazimova, S. B.; Hasanova, A. S.; Ismailzadeh, G. I.; Menzeleyev, M. R.

2018-05-01

Additive modeling of low-resolution microwave spectra of heteroisomeric substituted hydrocarbons produced theoretical spectra of ethanethiol and propanethiol in the range 0-2 THz with maxima at 465 ± 20 and 240 ± 20 GHz. More precise calculations in a narrow frequency band of these ranges used spectral line half-widths of 1.5, 0.8, and 0.5 MHz that modeled conditions in different layers of Earth's troposphere. The strongest extrema of the low-resolution spectra of the studied molecules were found at 486 ± 5, 446 ± 5, and 436 ± 5 (ethanethiol) and at 257 ± 5, 239 ± 5, and 234 ± 5 GHz (propanethiol). Various aspects of the application of the results were discussed.

Resonant electrodynamic heating of stellar coronal loops: An LRC circuit analogue

NASA Technical Reports Server (NTRS)

Ionson, J. A.

1980-01-01

The electrodynamic coupling of stellar coronal loops to underlying beta velocity fields. A rigorous analysis revealed that the physics can be represented by a simple yet equivalent LRC circuit analogue. This analogue points to the existence of global structure oscillations which resonantly excite internal field line oscillations at a spatial resonance within the coronal loop. Although the width of this spatial resonance, as well as the induced currents and coronal velocity field, explicitly depend upon viscosity and resistivity, the resonant form of the generalized electrodynamic heating function is virtually independent of irreversibilities. This is a classic feature of high quality resonators that are externally driven by a broad band source of spectral power. Applications to solar coronal loops result in remarkable agreement with observations.

\\Space: A new code to estimate \\temp, \\logg, and elemental abundances

NASA Astrophysics Data System (ADS)

Boeche, C.

2016-09-01

\\Space is a FORTRAN95 code that derives stellar parameters and elemental abundances from stellar spectra. To derive these parameters, \\Space does not measure equivalent widths of lines nor it uses templates of synthetic spectra, but it employs a new method based on a library of General Curve-Of-Growths. To date \\Space works on the wavelength range 5212-6860 Å and 8400-8921 Å, and at the spectral resolution R=2000-20000. Extensions of these limits are possible. \\Space is a highly automated code suitable for application to large spectroscopic surveys. A web front end to this service is publicly available at http://dc.g-vo.org/SP_ACE together with the library and the binary code.

Apodizing functions for Fourier transform spectroscopy.

PubMed

Naylor, David A; Tahic, Margaret K

2007-11-01

Apodizing functions are used in Fourier transform spectroscopy (FTS) to reduce the magnitude of the sidelobes in the instrumental line shape (ILS), which are a direct result of the finite maximum optical path difference in the measured interferogram. Three apodizing functions, which are considered optimal in the sense of producing the smallest loss in spectral resolution for a given reduction in the magnitude of the largest sidelobe, find frequent use in FTS [J. Opt. Soc. Am.66, 259 (1976)]. We extend this series to include optimal apodizing functions corresponding to increases in the width of the ILS ranging from factors of 1.1 to 2.0 compared with its unapodized value, and we compare the results with other commonly used apodizing functions.

Anomalous broadening and shift of emission lines in a femtosecond laser plasma filament in air

NASA Astrophysics Data System (ADS)

Ilyin, A. A.; Golik, S. S.; Shmirko, K. A.; Mayor, A. Yu.; Proschenko, D. Yu.

2017-12-01

The temporal evolution of the width and shift of N I 746.8 and O I 777.4 nm lines is investigated in a filament plasma produced by a tightly focused femtosecond laser pulse (0.9 mJ, 48 fs). The nitrogen line shift and width are determined by the joint action of electron impact shift and the far-off resonance AC Stark effect. The intensive (I = 1.2·1010 W/cm2) electric field of ASE (amplified spontaneous emission) and post-pulses result in a possible LS coupling break for the O I 3p 5P level and the generation of Rabi sidebands. The blueshifted main femtosecond pulse and Rabi sideband cause the stimulated emission of the N2 1+ system. The maximal widths of emission lines are approximately 6.7 times larger than the calculated Stark widths.

A High Resolution Spectroscopic Study of the Nu2 Band of Hydrogen Sulfide and the 1-0 Band of Hydrogen Iodide. Ph.D. Thesis - Maryland Univ.

NASA Technical Reports Server (NTRS)

Strow, L. L.

1981-01-01

A tunable diode laser spectrometer was constructed and used to study: (1) the effects of centrifugal distortion on the transition frequencies and strengths of the nu sub 2 band of H2S, and (2) nuclear quadrupole hyperfine structure in the 1-0 band of HI. A total of 126 line frequencies and 94 line strengths in the nu sub 2 band of H2S were measured. The average accuracy of the line frequency measurements was + or - 0.0016 cm. The line strengths were measured to an average accuracy of about 3 percent. The effect of the finite spectral width of the diode laser on the measurement of line strengths is discussed. The observed H2S line frequencies were fit to Watson's AS and NS reduced Hamiltonian in both the Ir and IIIr coordinate representations in order to determine the best set of rotation distortion constants for the upper state of the nu sub 2 band. Comparisons of the observed line strengths in this band to rigid rotor line strengths are also presented. Nuclear quadrupole hyperfine structure in the low J lines of the 1-0 band of HI was observed. The upper vibrational state nuclear quadrupole coupling constant, determined from the observed splittings, was -1850 MHz + or - 12 MHz or 1.2 percent + or - 0.7 percent larger than the ground state coupling constant.

First identification of pure rotation lines of NH in the infrared solar spectrum

NASA Technical Reports Server (NTRS)

Geller, M.; Farmer, C. B.; Norton, R. H.; Sauval, A. J.; Grevesse, N.

1991-01-01

Pure rotation lines of NH of the v = 0 level and v = 1 level are detected in high-resolution solar spectra obtained from the Atmospheric Trace Molecule Spectroscopy (ATMOS) experimental observations. It is pointed out that the identification of the lines is favored by the typical appearance of the triplet lines of nearly equal intensities. The observed equivalent widths of these triplet lines are compared with predicted intensities, and it is observed that these widths are systematically larger than the predicted values. It is noted that because these very faint lines are observed in a region where the signal is very low, a systematic error in the measurements of the equivalent widths cannot be ruled out; therefore, the disagreement between the observed and predicted intensities is not considered to be real.

Split-cross-bridge resistor for testing for proper fabrication of integrated circuits

NASA Technical Reports Server (NTRS)

Buehler, M. G. (Inventor)

1985-01-01

An electrical testing structure and method is described whereby a test structure is fabricated on a large scale integrated circuit wafer along with the circuit components and has a van der Pauw cross resistor in conjunction with a bridge resistor and a split bridge resistor, the latter having two channels each a line width wide, corresponding to the line width of the wafer circuit components, and with the two channels separated by a space equal to the line spacing of the wafer circuit components. The testing structure has associated voltage and current contact pads arranged in a two by four array for conveniently passing currents through the test structure and measuring voltages at appropriate points to calculate the sheet resistance, line width, line spacing, and line pitch of the circuit components on the wafer electrically.

A survey of ultraviolet interstellar absorption lines

NASA Technical Reports Server (NTRS)

Bohlin, R. C.; Jenkins, E. B.; Spitzer, L., Jr.; York, D. G.; Hill, J. K.; Savage, B. D.; Snow, T. P., Jr.

1983-01-01

A telescope-spectrometer on the Copernicus spacecraft made possible the measurement of many ultraviolet absorption lines produced by the interstellar gas. The present survey provides data on ultraviolet absorption lines in the spectra of 88 early-type stars. The stars observed are divided into four classes, including reddened stars, unreddened bright stars, moderately reddened bright stars, and unreddened and moderately reddened faint stars. Data are presented for equivalent width, W, radial velocity V, and rms line width, D, taking into account some 10 to 20 lines of N I, O I, Si II, P II, S II, Cl I, Cl II, Mn II, Fe II, Ni II, Cu II, and H2. The data are based on multiple scans for each line. Attention is given to details of observations, the data reduction procedure, and the computation of equivalent width, mean velocity, and velocity dispersion.

Stark broadening of He I lines

NASA Astrophysics Data System (ADS)

Dimitrijevic, M. S.; Sahal-Brechot, S.

1990-03-01

Results are presented from calculations of the electron-, proton-, and ionized helium-impact line widths and shifts for 77 neutral helium multiplets in the UV, visible, and IR regions of the spectrum. The calculations are performed using a semiclassical perturbation formalism (Sahal-Brechot, 1969). Tables are given for the line widths and shift for He I resonance lines at a perturber density of 10 to the 13th/cu cm.

Optical spectral singularities as threshold resonances

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mostafazadeh, Ali

2011-04-15

Spectral singularities are among generic mathematical features of complex scattering potentials. Physically they correspond to scattering states that behave like zero-width resonances. For a simple optical system, we show that a spectral singularity appears whenever the gain coefficient coincides with its threshold value and other parameters of the system are selected properly. We explore a concrete realization of spectral singularities for a typical semiconductor gain medium and propose a method of constructing a tunable laser that operates at threshold gain.

Signal and noise level estimation for narrow spectral width returns observed by the Indian MST radar

NASA Astrophysics Data System (ADS)

Hooper, D. A.

1999-07-01

Use is made of five sets of multibeam observations of the lower atmosphere made by the Indian mesosphere-stratosphere-troposphere (MST) radar. Two aspects of signal processing which can lead to serious underestimates of the signal-to-noise ratio are considered. First, a comparison is made of the effects of different data weighting windows applied to the inphase and quadrature components of the radar return samples prior to Fourier transformation. The relatively high degree of spectral leakage associated with the rectangular and Hamming windows can give rise to overestimates of the noise levels by up to 28 dB for the strongest signals. Use of the Hanning window is found to be the most appropriate for these particular data. Second, a technique for removing systematic dc biases from the data in the time domain is compared with the more well-known practice of correction in the frequency domain. The latter technique, which is often used to remove the effects of ground clutter, is shown to be particularly inappropriate for the characteristically narrow spectral width signals observed by the Indian MST radar. For cases of near-zero Doppler shift it can remove up to 30 dB of signal information. The consequences of noise and signal level discrepancies for studies of refractivity structures are discussed. It is shown that neither problem has a significant effect on Doppler shift or spectral width estimates.

Through BAL Quasars Brightly

NASA Technical Reports Server (NTRS)

Chartas, George

2003-01-01

We report on an observation of the broad absorption line (BAL) quasar PG 1115+080 performed with the XMM-Newton observatory. Spectral analysis reveals the second case of a relativistic X-ray-absorbing outflow in a BAL quasar. The first case was revealed in a recent observation of APM 08279+5255 with the Chandra X-Ray Observatory. As in the case of APM 08279+5255, the observed flux of PG 1115+080 is greatly magnified by gravitational lensing. The relatively high redshift (z=1.72) of the quasar places the redshifted energies of resonant absorption features in a sensitive portion of the XMM- Newton spectral response. The spectrum indicates the presence of complex low-energy absorption in the 0.2-0.6 keV observed energy band and high-energy absorption in the 2-5 keV observed energy band. The high-energy absorption is best modeled by two Gaussian absorption lines with rest-frame energies of 7.4 and 9.5 keV. Assuming that these two lines axe produced by resonant absorption due to Fe XXV, we infer that the X-ray absorbers are outflowing with velocities of approx. 0.10c and approx. 0.34c respectively. We have detected significant variability of the energies and widths of the X-ray BALs in PG 1115+080 and APM 08279+5255 over timescales of 19 and 1.8 weeks (proper time), respectively. The BAL variability observed from APM 08279+5255 supports our earlier conclusion that these absorbers are most likely launched at relatively small radii of less than 10(exp 16)(Mbh/M8)(sup 1/2) cm. A comparison of the ionization properties and column densities of the low-energy and high-energy absorbers indicates that these absorbers are likely distinct; however, higher spectral resolution is needed to confirm this result. Finally, we comment on prospects for constraining the kinematic and ionization properties of these X-ray BALs with the next generation of X-ray observatories.

Ultrahigh-resolution high-speed retinal imaging using spectral-domain optical coherence tomography

NASA Astrophysics Data System (ADS)

Cense, Barry; Nassif, Nader A.; Chen, Teresa C.; Pierce, Mark C.; Yun, Seok-Hyun; Hyle Park, B.; Bouma, Brett E.; Tearney, Guillermo J.; de Boer, Johannes F.

2004-05-01

We present the first ultrahigh-resolution optical coherence tomography (OCT) structural intensity images and movies of the human retina in vivo at 29.3 frames per second with 500 A-lines per frame. Data was acquired at a continuous rate of 29,300 spectra per second with a 98% duty cycle. Two consecutive spectra were coherently summed to improve sensitivity, resulting in an effective rate of 14,600 A-lines per second at an effective integration time of 68 μs. The turn-key source was a combination of two super luminescent diodes with a combined spectral width of more than 150 nm providing 4.5 mW of power. The spectrometer of the spectraldomain OCT (SD-OCT) setup was centered around 885 nm with a bandwidth of 145 nm. The effective bandwidth in the eye was limited to approximately 100 nm due to increased absorption of wavelengths above 920 nm in the vitreous. Comparing the performance of our ultrahighresolution SD-OCT system with a conventional high-resolution time domain OCT system, the A-line rate of the spectral-domain OCT system was 59 times higher at a 5.4 dB lower sensitivity. With use of a software based dispersion compensation scheme, coherence length broadening due to dispersion mismatch between sample and reference arms was minimized. The coherence length measured from a mirror in air was equal to 4.0 μm (n= 1). The coherence length determined from the specular reflection of the foveal umbo in vivo in a healthy human eye was equal to 3.5 μm (n = 1.38). With this new system, two layers at the location of the retinal pigmented epithelium seem to be present, as well as small features in the inner and outer plexiform layers, which are believed to be small blood vessels.

X-ray spectrometer having 12 000 resolving power at 8 keV energy

NASA Astrophysics Data System (ADS)

Seely, John F.; Hudson, Lawrence T.; Henins, Albert; Feldman, Uri

2017-10-01

An x-ray spectrometer employing a thin (50 μm) silicon transmission crystal was used to record high-resolution Cu Kα spectra from a laboratory x-ray source. The diffraction was from the (331) planes that were at an angle of 13.26° to the crystal surface. The components of the spectral lines resulting from single-vacancy (1s) and double-vacancy (1s and 3d) transitions were observed. After accounting for the natural lifetime widths from reference double-crystal spectra and the spatial resolution of the image plate detector, the intrinsic broadening of the transmission crystal was measured to be as small as 0.67 eV and the resolving power 12 000, the highest resolving power achieved by a compact (0.5 m long) spectrometer employing a single transmission crystal operating in the hard x-ray region. By recording spectra with variable source-to-crystal distances and comparing to the calculated widths from various geometrical broadening mechanisms, the primary contributions to the intrinsic crystal broadening were found to be the source height at small distances and the crystal apertured height at large distances. By reducing these two effects, using a smaller source size and vignetting the crystal height, the intrinsic crystal broadening is then limited by the crystal thickness and the rocking curve width and would be 0.4 eV at 8 keV energy (20 000 resolving power).

Multiwavelength self-pulsating fibre laser based on cascaded SPM spectral broadening and filtering

NASA Astrophysics Data System (ADS)

Rochette, Martin; Sun, Kai; Hernández-Cordero, Juan; Chen, Lawrence R.

2008-06-01

We experimentally demonstrate the operation of a laser based on self-phase modulation followed by offset spectral filtering. This laser has three operation modes: a continuous-wave mode, a self-pulsating mode where the laser self ignites and produces pulses, and a pulse-buffering mode where no new pulse is formed from spontaneous emission noise but only pulses already propagating or pulses injected in the laser cavity can be sustained. In the self-pulsating and pulse-buffering modes, the laser is multi-wavelength and continuously tunable over the entire gain band of the amplifiers. The output pulse width is quasi transform-limited with respect to the spectral-width of the filters used in the cavity. Overall, this device provides a simple alternative to pulsed laser source and also represents a promising approach for signal buffering.

Temporal characterization of the wave-breaking flash in a laser plasma accelerator

NASA Astrophysics Data System (ADS)

Miao, Bo; Feder, Linus; Goers, Andrew; Hine, George; Salehi, Fatholah; Wahlstrand, Jared; Woodbury, Daniel; Milchberg, Howard

2017-10-01

Wave-breaking injection of electrons into a relativistic plasma wake generated in near-critical density plasma by sub-terawatt laser pulses generates an intense ( 1 μJ) and ultra-broadband (Δλ 300 nm) radiation flash. In this work we demonstrate the spectral coherence of this radiation and measure its temporal width using single-shot supercontinuum spectral interferometry (SSSI). The measured temporal width is limited by measurement resolution to 50 fs. Spectral coherence is corroborated by PIC simulations which show that the spatial extent of the acceleration trajectory at the trapping region is small compared to the radiation center wavelength. To our knowledge, this is the first temporal and coherence characterization of wave-breaking radiation. This work is supported by the US Department of Energy, the National Science Foundation, and the Air Force Office of Scientific Research.

(14)N overtone transition in double rotation solid-state NMR.

PubMed

Haies, Ibraheem M; Jarvis, James A; Brown, Lynda J; Kuprov, Ilya; Williamson, Philip T F; Carravetta, Marina

2015-10-07

Solid-state NMR transitions involving outer energy levels of the spin-1 (14)N nucleus are immune, to first order in perturbation theory, to the broadening caused by the nuclear quadrupole interaction. The corresponding overtone spectra, when acquired in conjunction with magic-angle sample spinning, result in lines, which are just a few kHz wide, permitting the direct detection of nitrogen compounds without the need for labeling. Despite the success of this technique, "overtone" resonances are still broadened due to indirect, second order effects arising from the large quadrupolar interaction. Here we demonstrate that another order of magnitude in spectral resolution may be gained by using double rotation. This brings the width of the (14)N solid-state NMR lines much closer to the region commonly associated with high-resolution solid-state NMR spectroscopy of (15)N and demonstrates the improvements in resolution that may be possible through the development of pulsed methodologies to suppress these second order effects.

Virtual rough samples to test 3D nanometer-scale scanning electron microscopy stereo photogrammetry.

PubMed

Villarrubia, J S; Tondare, V N; Vladár, A E

2016-01-01

The combination of scanning electron microscopy for high spatial resolution, images from multiple angles to provide 3D information, and commercially available stereo photogrammetry software for 3D reconstruction offers promise for nanometer-scale dimensional metrology in 3D. A method is described to test 3D photogrammetry software by the use of virtual samples-mathematical samples from which simulated images are made for use as inputs to the software under test. The virtual sample is constructed by wrapping a rough skin with any desired power spectral density around a smooth near-trapezoidal line with rounded top corners. Reconstruction is performed with images simulated from different angular viewpoints. The software's reconstructed 3D model is then compared to the known geometry of the virtual sample. Three commercial photogrammetry software packages were tested. Two of them produced results for line height and width that were within close to 1 nm of the correct values. All of the packages exhibited some difficulty in reconstructing details of the surface roughness.

Conversion from mutual helicity to self-helicity observed with IRIS

NASA Astrophysics Data System (ADS)

Li, L. P.; Peter, H.; Chen, F.; Zhang, J.

2014-10-01

Context. In the upper atmosphere of the Sun observations show convincing evidence for crossing and twisted structures, which are interpreted as mutual helicity and self-helicity. Aims: We use observations with the new Interface Region Imaging Spectrograph (IRIS) to show the conversion of mutual helicity into self-helicity in coronal structures on the Sun. Methods: Using far UV spectra and slit-jaw images from IRIS and coronal images and magnetograms from SDO, we investigated the evolution of two crossing loops in an active region, in particular, the properties of the Si IV line profile in cool loops. Results: In the early stage two cool loops cross each other and accordingly have mutual helicity. The Doppler shifts in the loops indicate that they wind around each other. As a consequence, near the crossing point of the loops (interchange) reconnection sets in, which heats the plasma. This is consistent with the observed increase of the line width and of the appearance of the loops at higher temperatures. After this interaction, the two new loops run in parallel, and in one of them shows a clear spectral tilt of the Si IV line profile. This is indicative of a helical (twisting) motion, which is the same as to say that the loop has self-helicity. Conclusions: The high spatial and spectral resolution of IRIS allowed us to see the conversion of mutual helicity to self-helicity in the (interchange) reconnection of two loops. This is observational evidence for earlier theoretical speculations. Movie associated with Fig. 1 and Appendix A are available in electronic form at http://www.aanda.org

The MUSCLES Treasury Survey. IV. Scaling Relations for Ultraviolet, Ca II K, and Energetic Particle Fluxes from M Dwarfs

NASA Astrophysics Data System (ADS)

Youngblood, Allison; France, Kevin; Loyd, R. O. Parke; Brown, Alexander; Mason, James P.; Schneider, P. Christian; Tilley, Matt A.; Berta-Thompson, Zachory K.; Buccino, Andrea; Froning, Cynthia S.; Hawley, Suzanne L.; Linsky, Jeffrey; Mauas, Pablo J. D.; Redfield, Seth; Kowalski, Adam; Miguel, Yamila; Newton, Elisabeth R.; Rugheimer, Sarah; Segura, Antígona; Roberge, Aki; Vieytes, Mariela

2017-07-01

Characterizing the UV spectral energy distribution (SED) of an exoplanet host star is critically important for assessing its planet’s potential habitability, particularly for M dwarfs, as they are prime targets for current and near-term exoplanet characterization efforts and atmospheric models predict that their UV radiation can produce photochemistry on habitable zone planets different from that on Earth. To derive ground-based proxies for UV emission for use when Hubble Space Telescope (HST) observations are unavailable, we have assembled a sample of 15 early to mid-M dwarfs observed by HST and compared their nonsimultaneous UV and optical spectra. We find that the equivalent width of the chromospheric Ca II K line at 3933 Å, when corrected for spectral type, can be used to estimate the stellar surface flux in ultraviolet emission lines, including H I Lyα. In addition, we address another potential driver of habitability: energetic particle fluxes associated with flares. We present a new technique for estimating soft X-ray and >10 MeV proton flux during far-UV emission line flares (Si IV and He II) by assuming solar-like energy partitions. We analyze several flares from the M4 dwarf GJ 876 observed with HST and Chandra as part of the MUSCLES Treasury Survey and find that habitable zone planets orbiting GJ 876 are impacted by large Carrington-like flares with peak soft X-ray fluxes ≥10-3 W m-2 and possible proton fluxes ˜102-103 pfu, approximately four orders of magnitude more frequently than modern-day Earth.

Suzaku observation of the eclipsing high mass X-ray binary pulsar XTE J1855-026

NASA Astrophysics Data System (ADS)

Devasia, Jincy; Paul, Biswajit

2018-02-01

We report results from analysis performed on an eclipsing supergiant high mass X-ray binary pulsar XTE J1855-026 observed with the X-ray Imaging Spectrometer (XIS) on-board Suzaku Observatory in April 2015. Suzaku observed this source for a total effective exposure of ˜ 87 ks just before an eclipse. Pulsations are clearly observed and the pulse profiles of XTE J1855-026 did not show significant energy dependence during this observation consistent with previous reports. The time averaged energy spectrum of XTE J1855-026 in the 1.0-10.5 keV energy range can be well fitted with a partial covering power law model modified with interstellar absorption along with a black-body component for soft excess and a gaussian for iron fluorescence line emision. The hardness ratio evolution during this observation indicated significant absorption of soft X-rays in some segments of the observation. For better understanding of the reason behind this, we performed time-resolved spectroscopy in the 2.5-10.5 keV energy band which revealed significant variations in the spectral parameters, especially the hydrogen column density and iron line equivalent width with flux. The correlated variations in the spectral parameters indicate towards the presence of clumps in the stellar wind of the companion star accounting for the absorption of low energy X-rays in some time segments.

The temporal evolution of explosive events and its implication on reconnection dynamics

NASA Astrophysics Data System (ADS)

Guo, L.; Liu, W.; De Pontieu, B.; Huang, Y. M.; Peter, H.; Bhattacharjee, A.

2017-12-01

Transition-region explosive events and other bursts seen in extreme UV light are characterized by broad spectral line profiles, and the more violent ones show a strong enhancement of emission. They are thought to be driven by magnetic reconnection, because of their characteristic spectral profiles often indicating strong Alfvénic flows, and because of the fact that they typically occur where magnetic flux concentrations of opposite polarity intersect. In this presentation, we will focus on the temporal evolution of transition-region explosive events. In particular, we will investigate fast onsets of these events and the rapid oscillations of intensity during these event. The fast onset refers to the beginning of an explosive event, where the intensities and the widths of its line profiles increase dramatically (often within less than 10 seconds) and the rapid oscillations of intensity refer to blinks of emission that usually last less than 10 seconds during the event. In order to interpret and understand underlying mechanisms of these observations, we conduct numerical simulation of an explosive event and calculate its spectra. We observe a similar temporal evolution in the synthetic Si IV spectra when the explosive event is driven by time-dependent reconnection—plasmoid instability. The qualitative agreement between observations and simulations suggests that the temporal evolution of Si IV spectra of explosive events are closely related to reconnection dynamics.

Analysis of fusion neutron spectral widths in high-foot implosions at the National Ignition Facility

NASA Astrophysics Data System (ADS)

Grim, Gary; Caggiano, Joseph; Callahan, Debra; Casey, Daniel; Cerjan, Charles; Clark, Daniel; Tilo, Doeppner; Eckart, Mark; Field, John; Frenje, Lars; Gatu-Johnson, Maria; Hartouni, Edward; Hatarik, Robert; Hurricane, Omar; Kilkenny, Joseph; Knauer, James; Ma, Tammy; Mannion, Owen; Munro, David; Park, Hye-Sook; Sayre, Daniel; Spears, Brian; Yeamans, Charles

2015-11-01

We present the latest results of thermal temperature analyses of cryogenically layered deuterium-tritium implosions at the NIF using data from the ``High Foot'' campaign. Data from new analysis methods and interpreted in the context of new theoretical developments will be reported. These data will include DD and DT apparent ion temperatures, their uniformity with direction, inferred plasma thermal temperature, as well as the magnitude of non-thermal contributions to the spectral widths. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

Cramer-Rao Bound for Gaussian Random Processes and Applications to Radar Processing of Atmospheric Signals

NASA Technical Reports Server (NTRS)

Frehlich, Rod

1993-01-01

Calculations of the exact Cramer-Rao Bound (CRB) for unbiased estimates of the mean frequency, signal power, and spectral width of Doppler radar/lidar signals (a Gaussian random process) are presented. Approximate CRB's are derived using the Discrete Fourier Transform (DFT). These approximate results are equal to the exact CRB when the DFT coefficients are mutually uncorrelated. Previous high SNR limits for CRB's are shown to be inaccurate because the discrete summations cannot be approximated with integration. The performance of an approximate maximum likelihood estimator for mean frequency approaches the exact CRB for moderate signal to noise ratio and moderate spectral width.

Estimation of photonic band gap in the hollow core cylindrical multilayer structure

NASA Astrophysics Data System (ADS)

Chourasia, Ritesh Kumar; Singh, Vivek

2018-04-01

The propagation characteristic of two hollow core cylindrical multilayer structures having high and low refractive index contrast of cladding regions have been studied and compared at two design wavelengths i.e. 1550 nm and 632.8 nm. With the help of transfer matrix method a relation between the incoming light wave and outgoing light wave has been developed using the boundary matching technique. In high refractive index contrast, small numbers of layers are sufficient to provide perfect band gap in both design wavelengths. The spectral position and width of band gap is highly depending on the optical path of incident light in all considered cases. For sensing application, the sensitivity of waveguide can be obtained either by monitoring the width of photonic band gap or by monitoring the spectral shift of photonic band gap. Change in the width of photonic band gap with the core refractive index is larger in high refractive index contrast of cladding materials. However, in the case of monitoring the spectral shift of band gap, the obtained sensitivity is large for low refractive index contrast of cladding materials and further it increases with increase of design wavelength.

Monte-Carlo modelling to determine optimum filter choices for sub-microsecond optical pyrometry.

PubMed

Ota, Thomas A; Chapman, David J; Eakins, Daniel E

2017-04-01

When designing a spectral-band pyrometer for use at high time resolutions (sub-μs), there is ambiguity regarding the optimum characteristics for a spectral filter(s). In particular, while prior work has discussed uncertainties in spectral-band pyrometry, there has been little discussion of the effects of noise which is an important consideration in time-resolved, high speed experiments. Using a Monte-Carlo process to simulate the effects of noise, a model of collection from a black body has been developed to give insights into the optimum choices for centre wavelength and passband width. The model was validated and then used to explore the effects of centre wavelength and passband width on measurement uncertainty. This reveals a transition centre wavelength below which uncertainties in calculated temperature are high. To further investigate system performance, simultaneous variation of the centre wavelength and bandpass width of a filter is investigated. Using data reduction, the effects of temperature and noise levels are illustrated and an empirical approximation is determined. The results presented show that filter choice can significantly affect instrument performance and, while best practice requires detailed modelling to achieve optimal performance, the expression presented can be used to aid filter selection.