WorldWideScience
 
 
1

Role of nonthermal velocity fields in determining the H-alpha widths in supergiant chromospheres  

International Nuclear Information System (INIS)

Radiative transfer calculations of the H-alpha line in spherically symmetric, expanding chromospheres explain the large widths of the line observed in late G and K supergiants. The role of various dynamical processes as well as that of opacity in determining the H-alpha width is illustrated. The H-alpha line profile is basically characterized by large optical depths and large Doppler broadening velocity. The calculations show that the existence of large microturbulence has to be invoked in the chromosphere to understand the observed widths. 22 refs

2

ROBOSPECT: Automated Equivalent Width Measurement  

CERN Document Server

We present ROBOSPECT, a new code to automatically measure and deblend line equivalent widths for both absorption and emission spectra. We test the accuracy of these measurements against simulated spectra as well as manual equivalent width measurements of five stellar spectra over a range of signal-to-noise values and a set of long slit emission spectra. We find that ROBOSPECT accurately matches both the synthetic and manual measurements, with scatter consistent with the expectations based on the data quality and the results of Cayrel (1988).

Waters, Christopher Z

2013-01-01

3

The Variability of Halpha Equivalent Widths in Be Stars  

CERN Document Server

Focusing on B-emission stars, we investigated a set of H$\\alpha$ equivalent widths calculated from observed spectra acquired over a period of about 4 years from 2003 to 2007. During this time, changes in equivalent width for our program stars were monitored. We have found a simple statistical method to quantify these changes in our observations. This statistical test, commonly called the F ratio, involves calculating the ratio of the external and internal error. We show that the application of this technique can be used to place bounds on the degree of variability of Be stars. This observational tool provides a quantitative way to find Be stars at particular stages of variability requiring relatively little observational data.

Jones, C E; Smith, A D

2011-01-01

4

H I Lyman-alpha Equivalent Widths of Stellar Populations  

Science.gov (United States)

We have compiled a library of stellar Lyman-alpha (Ly?) equivalent widths in O and B stars using the model atmosphere codes CMFGEN and TLUSTY, respectively. The equivalent widths range from about 0 to 30 Å in absorption for early-O to mid-B stars. The purpose of this library is for the prediction of the underlying stellar Ly? absorption in stellar populations of star-forming galaxies with nebular Ly? emission. We implemented the grid of individual equivalent widths into the Starburst99 population synthesis code to generate synthetic Ly? equivalent widths for representative star formation histories. A starburst observed after 10 Myr will produce a stellar Ly? line with an equivalent width of ~ - 10 ± 4 Å in absorption for a Salpeter initial mass function. The lower value (deeper absorption) results from an instantaneous burst, and the higher value (shallower line) from continuous star formation. Depending on the escape fraction of nebular Ly? photons, the effect of stellar Ly? on the total profile ranges from negligible to dominant. If the nebular escape fraction is 10%, the stellar absorption and nebular emission equivalent widths become comparable for continuous star formation at ages of 10-20 Myr.

Peña-Guerrero, María A.; Leitherer, Claus

2013-12-01

5

HI Lyman-alpha equivalent widths of stellar populations  

CERN Document Server

We have compiled a library of stellar Lyman-alpha equivalent widths in O and B stars using the model atmosphere codes CMFGEN and TLUSTY, respectively. The equivalent widths range from about 0 to 30 \\AA in absorption for early-O to mid-B stars. The purpose of this library is the prediction of the underlying stellar Lyman-alpha absorption in stellar populations of star-forming galaxies with nebular Lyman-alpha emission. We implemented the grid of individual equivalent widths into the Starburst99 population synthesis code to generate synthetic Lyman-alpha equivalent widths for representative star-formation histories. A starburst observed after 10 Myr will produce a stellar Lyman-alpha line with an equivalent width of $\\sim$ -10$\\pm$4 \\AA in absorption for a Salpeter initial mass function. The lower value (deeper absorption) results for an instantaneous burst, and the higher value (shallower line) for continuous star formation. Depending on the escape fraction of nebular Lyman-alpha photons, the effect of stellar...

Pena-Guerrero, Maria A

2013-01-01

6

FUNDPAR: A Program for deriving Fundamental Parameters from Equivalent Widths  

CERN Document Server

We implemented a fortran code that determine fundamental parameters of solar type stars from a list of Fe line equivalent widths. The solution should verify 3 conditions in the standard method: ionization equilibrium, excitation equilibrium and independence between metallicity and equivalent widths. We added the condition that the input metallicity of the model atmosphere should be similar to the output metallicity derived with equivalent widths. Solar-scaled Kurucz model atmospheres with NEWODF opacities are calculated with an independent program. Parameter files control different details, such as the mixing-length parameter, the overshooting, the damping of the lines and the weight factors in the definition of the chi2 function. FUNDPAR derive the uncertainties following 2 methods: the criteria of Gonzalez & Vanture (1998) and the dispersion using the chi2 function. The code use the 2009 version of the MOOG program. The results derived with FUNDPAR are in agreement with previous determinations in the li...

Saffe, Carlos

2010-01-01

7

FUNDPAR: A program for Deriving Fundamental Parameters from Equivalent Widths  

Science.gov (United States)

We implemented a Fortran code that determines fundamental parameters of solar type stars from a list of Fe line equivalent widths. The solution should verify three conditions in the standard method: ionization equilibrium, excitation equilibrium and independence between metallicity and equivalent widths. Solar-scaled Kurucz model atmospheres with NEWODF opacities are calculated with an independent program. Parameter files control different details, such as the mixing-length parameter and the overshooting. FUNDPAR derives the uncertainties following two methods: the criterion of Gonzalez & Vanture (1998) and the dispersion using the ?2 function. The code uses the 2009 version of the MOOG program. The results derived with FUNDPAR are in agreement with previous determinations in the literature. The program is freely available from the web.

Saffe, C.

2011-04-01

8

Equivalent Widths in the Spectrum of Sirius (Zhao+, 2000)  

Science.gov (United States)

The equivalent widths of total 546 lines (26 elements are included) in the spectrum of the bright Am star Sirius from 380 to 930 nm are tabulated. The high-resolution, high signal-to-noise ratio spectrum was obtained with the Coude Echelle Spectrograph attached to the 2.16 m telescope at Beijing Astronomical Observatory (Xinglong, China). Here we also give the results of the equivalent widths comparison between our measurements and those of Strom et al. (=1966ApJ...146..880S) and Sadakane & Ueta (=1989PASJ...41..279S). Table 1. Observation Journal of Sirius: ------------------------------------------------------------------------- --- Spectral Range Exposure Time Geocentric Radial Velocity (nm) Obs. Date (s) (km s-1) ------------------------------------------------------------------------- --- 386.5-572.1 1997 Feb 18/19 180 12.75 (0.45) 383.3-661.9 1997 Feb 18/19 40+40+30 12.37 (0.96) 378.9-551.6 1997 Feb 18/19 40+40 12.31 (0.82) 380.7-649.3 1997 Feb 18/19 40+40 12.42 (0.93) 623.8-922.7 1999 Apr 01/02 300+300 15.49 (0.52) 624.8-930.4 1999 Apr 01/02 300+300 15.58 (0.69) ------------------------------------------------------------------------- --- (1 data file).

Zhao, G.; Qiu, H. M.; Chen, Y. Q.; Li, Z. W.

2000-09-01

9

The distribution of equivalent widths in long GRB afterglow spectra  

CERN Document Server

The extreme brightness of gamma-ray burst (GRB) afterglows and their simple spectral shape make them ideal beacons to study the interstellar medium of their host galaxies through absorption line spectroscopy. Using 69 low-resolution GRB afterglow spectra, we conduct a study of the rest-frame equivalent width (EW) distribution of features with an average rest-frame EW larger than 0.5 A. To compare an individual GRB with the sample, we develop EW diagrams as a graphical tool, and we give a catalogue with diagrams for the 69 spectra. We introduce a line strength parameter (LSP) that allows us to quantify the strength of the absorption features as compared to the sample by a single number. Using the distributions of EWs of single-species features, we derive the distribution of column densities by a curve of growth (CoG) fit. We find correlations between the LSP and the extinction of the GRB, the UV brightness of the host galaxies and the neutral hydrogen column density. However, we see no significant evolution of...

Postigo, A de Ugarte; Thoene, C C; Christensen, L; Gorosabel, J; Milvang-Jensen, B; Schulze, S; Jakobsson, P; Wiersema, K; Sanchez-Ramirez, R; Leloudas, G; Zafar, T; Malesani, D; Hjorth, J

2012-01-01

10

HI Lyman-alpha Equivalent Widths of Stellar Populations  

Science.gov (United States)

Lyman-alpha (Ly alpha) emission is a widely used indicator of star formation in starburst clusters as close as a few tens of Mpc, and also in high-redshift galaxies. The observed Ly alpha is the total contribution of the nebular and stellar components. However, this stellar contribution has not been observationally constrained mainly due to the interstellar HI column densities masking the intrinsic Ly alpha of even the closest O stars. We assembled a library of Ly alpha profiles using CMFGEN and TLUSTY model atmospheres to predict Ly? Equivalent Widths (EW’s) in O and B stars. We implemented this new library into the population synthesis code Starburst99, in order to calculate the underlying stellar absorption for young populations. For a standard equilibrium population, our models predict a stellar contribution of about 10 A absorption, depending on the type of Initial Mass Function (IMF) assumed and on the age of the population. We argue that our models provide a realistic description of the stellar Ly? and that they should be used to correct the observed nebular emission in star-forming galaxies.

Peña-Guerrero, M. A.; Leitherer, C.

2014-09-01

11

H{\\alpha} photometry of low mass stars in 47 Tucanae: chromospheric activity and exotica  

CERN Document Server

We have used archival Hubble Space Telescope observations obtained with the Advanced Camera for Surveys to study the H{\\alpha} emission properties of main sequence stars in the globular cluster 47 Tucanae. Using a combination of multi-band observations in the F606W, F814W and F658N bands, we search for stars showing H{\\alpha} excess emission. An accurate photometric measurement of their H{\\alpha} equivalent width allows us to identify objects with large H{\\alpha} emission, which we attribute to mass accretion rather than enhanced chromospheric activity. The spatial position of some of these stars is coincident with that of known X-ray sources and their location in the colour-magnitude diagram allows us to classify them as active binaries or cataclysmic variables (CVs). We show that this method, commonly adopted to study accreting discs in young stellar objects, can be successfully used to identify and characterise candidate CVs.

Beccari, G; Panagia, N; Pasquini, L

2013-01-01

12

The reddening law of Type Ia Supernovae: separating intrinsic variability from dust using equivalent widths  

CERN Document Server

We employ 76 type Ia supernovae with optical spectrophotometry within 2.5 days of B-band maximum light obtained by the Nearby Supernova Factory to derive the impact of Si and Ca features on supernovae intrinsic luminosity and determine a dust reddening law. We use the equivalent width of Si II {\\lambda}4131 in place of light curve stretch to account for first-order intrinsic luminosity variability. The resultant empirical spectral reddening law exhibits strong features associated with Ca II and Si II {\\lambda}6355. After applying a correction based on the Ca II H&K equivalent width we find a reddening law consistent with a Cardelli extinction law. Using the same input data, we compare this result to synthetic rest-frame UBVRI-like photometry in order to mimic literature observations. After corrections for signatures correlated with Si II {\\lambda}4131 and Ca II H&K equivalent widths, and introducing an empirical correlation between colors, we determine the dust component in each band. We find a value ...

Chotard, N; Aldering, G; Antilogus, P; Aragon, C; Bailey, S; Baltay, C; Bongard, S; Buton, C; Canto, A; Childress, M; Copin, Y; Fakhouri, H K; Hsiao, E Y; Kerschhaggl, M; Kowalski, M; Loken, S; Nugent, P; Paech, K; Pain, R; Pecontal, E; Pereira, R; Perlmutter, S; Rabinowitz, D; Runge, K; Scalzo, R; Smadja, G; Tao, C; Thomas, R C; Weaver, B A; Wu, C

2011-01-01

13

On the H$\\alpha$ Behaviour of Blue Supergiants: Rise and Fall over the Bi-stability Jump  

CERN Document Server

The evolutionary state of blue supergiants is still unknown. Stellar wind mass loss is one of the dominant processes determining the evolution of massive stars, and it may provide clues on the evolutionary properties of blue supergiants. As the H$\\alpha$ line is the most oft-used mass-loss tracer in the OB-star regime, we provide a detailed analysis of the H$\\alpha$ line for OB supergiant models over an $T_{\\rm eff}$ range between 30000 and 12500K. We find a maximum in the H$\\alpha$ equivalent width at 22500 K - at the location of the bi-stability jump. The H$\\alpha$ line-profile behaviour is characterised by two branches of $T_{\\rm eff}$: (i) a "hot" branch between 30000 and 22500 K, where H$\\alpha$ emission becomes stronger with decreasing $T_{\\rm eff}$, and (ii) a "cool" branch between 22500 and 12500 K, where the line becomes weaker. Our models show that this non-monotonic H$\\alpha$ behaviour is related to the optical depth of Ly$\\alpha$, finding that at the "cool" branch the population of the 2nd level o...

Petrov, Blagovest; Gräfener, Götz

2014-01-01

14

H-alpha observations of the gamma-ray-emitting Be/X-ray binary LSI+61303: orbital modulation, disk truncation, and long-term variability  

CERN Document Server

We report 138 spectral observations of the H-alpha emission line of the radio- and gamma-ray-emitting Be/X-ray binary LSI+61303 obtained during the period of September 1998 -- January 2013. From measuring various H-alpha parameters, we found that the orbital modulation of the H-alpha is best visible in the equivalent width ratio EW(B)/EW(R), the equivalent width of the blue hump, and in the radial velocity of the central dip. The periodogram analysis confirmed that the H-alpha emission is modulated with the orbital and superorbital periods. For the past 20 years the radius of the circumstellar disk is similar to the Roche lobe size at the periastron. It is probably truncated by a 6:1 resonance. The orbital maximum of the equivalent width of H-alpha emission peaks after the periastron and coincides on average with the X-ray and gamma-ray maxima. All the spectra are available upon request from the authors and through the CDS.

Zamanov, R; Marti, J; Tomov, N A; Belcheva, G; Luque-Escamilla, P L; Latev, G

2013-01-01

15

VizieR Online Data Catalog: Equivalent widths of WINGS galaxies (Fritz+, 2014)  

Science.gov (United States)

Equivalent Widths for up to 14 optical lines, measurement uncertainties, the D4000 and Dn4000 index, spectral classification, and magnitude and geometrical completeness are presented for 4861 galaxies in 29 nearby clusters' fields. Galaxies in the following clusters have been included in the catalog: A1069, A119, A151, A1631a, A1644, A2382, A2399, A2415, A3128, A3158, A3266, A3376, A3395, A3490, A3497, A3556, A3560, A3809, A500, A754, A957x, A970, A1795, A1983, A2457, A2626, A376, Z8338 and Z8852. (1 data file).

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

2014-02-01

16

Rapid changes in H alpha-flares correlated with microwaves  

Science.gov (United States)

The time evolution of several flares was studied in H alpha with a time resolution of 1.4 seconds. The time profiles of the linecenter intensity show fast fluctuations and spikes. During the impulsive phase, prominent spikes occur in different kernels and they are correlated with microwave and Hard X-ray spikes. Spectral resolved observations show major changes of the ratio between H alpha line width and H alpha linecenter intensity at time scales in the order of 1 minute. No significant fluctuations occurred at shorter time scales.

Wuelser, J-P.; Kaempfer, N.

1986-01-01

17

DAOSPEC: An Automatic Code for Measuring Equivalent Widths in High-resolution Stellar Spectra  

Science.gov (United States)

DAOSPEC is a Fortran code for measuring equivalent widths of absorption lines in stellar spectra with minimal human involvement. It works with standard FITS format files and it is designed for use with high resolution (R>15000) and high signal-to-noise-ratio (S/N>30) spectra that have been binned on a linear wavelength scale. First, we review the analysis procedures that are usually employed in the literature. Next, we discuss the principles underlying DAOSPEC and point out similarities and differences with respect to conventional measurement techniques. Then experiments with artificial and real spectra are discussed to illustrate the capabilities and limitations of DAOSPEC, with special attention given to the issues of continuum placement; radial velocities; and the effects of strong lines and line crowding. Finally, quantitative comparisons with other codes and with results from the literature are also presented.

Stetson, P. B.; Pancino, E.

2010-11-01

18

DAOSPEC: an automatic code for measuring equivalent widths in high-resolution stellar spectra  

CERN Document Server

DAOSPEC is a Fortran code for measuring equivalent widths of absorption lines in stellar spectra with minimal human involvement. It works with standard FITS format files and it is designed for use with high resolution (R>15000) and high signal-to-noise-ratio (S/N>30) spectra that have been binned on a linear wavelength scale. First, we review the analysis procedures that are usually employed in the literature. Next, we discuss the principles underlying DAOSPEC and point out similarities and differences with respect to conventional measurement techniques. Then experiments with artificial and real spectra are discussed to illustrate the capabilities and limitations of DAOSPEC, with special attention given to the issues of continuum placement; radial velocities; and the effects of strong lines and line crowding. Finally, quantitative comparisons with other codes and with results from the literature are also presented.

Stetson, P B

2008-01-01

19

Multi-slit spectrograph and H alpha Doppler system  

Science.gov (United States)

Description of the design and operation of a multiple-entrance-slit spectrograph, built for time-lapse photography of the spectra of flares and other transient solar phenomena. This spectrograph employs narrow-band filters to limit the wavelength range of the spectrograph to a few angstroms centered at H-alpha or other spectral lines. A polarizing beamsplitter, prior to the slits, provides a prefiltered second solar image to a narrow band H-alpha Doppler filter for simultaneous photography in the wings of the H-alpha line. The spectrograph and the H-alpha Doppler system constitute a flexible instrument in which components may be substituted to achieve different passband widths, image scales, dispersions, and corresponding numbers and spacings of adjacent spectra at a selected wavelength.

Martin, S. F.; Ramsey, H. E.; Carroll, G. A.; Martin, D. C.

1974-01-01

20

On the (Non-)Enhancement of the Ly? Equivalent Width by a Multiphase Interstellar Medium  

DEFF Research Database (Denmark)

It has been suggested that radiative transfer effects may explain the unusually high equivalent widths (EWs) of the Lya line, observed occasionally from starburst galaxies, especially at high redshifts. If the dust is locked up inside high-density clouds dispersed in an empty intercloud medium, the Lya photons could scatter off of the surfaces of the clouds, effectively having their journey confined to the dustless medium. The continuum radiation, on the other hand, does not scatter, and would thus be subject to absorption inside the clouds. This scenario is routinely invoked when Lya EWs higher than what is expected theoretically are observed, although the ideal conditions under which the results are derived usually are not considered. Here we systematically examine the relevant physical parameters in this idealized framework, testing whether any astrophysically realistic scenarios may lead to such an effect. It is found that although clumpiness indeed facilitates the escape of Lya, it is highly unlikely that any real interstellar media should result in a preferential escape of Lya over continuum radiation. Other possible causes are discussed, and it is concluded that the observed high EWs are more likely to be caused by cooling radiation from cold accretion and/or anisotropic escape of the Lya radiation. © 2013. The American Astronomical Society. All rights reserved.

Laursen, Peter; Duval, F.

2013-01-01

 
 
 
 
21

Ly{\\alpha} Equivalent Width Distribution at Redshift z $\\sim$ 4.5  

CERN Document Server

Ly{\\alpha} line equivalent widths (EWs) provide important clues to the physical nature of high redshift Lyman alpha emitters (LAEs). However, measuring the Ly{\\alpha} EW distribution of high-z narrowband selected LAEs can be hard because many sources do not have broadband photometry. We investigate the possible biases in measuring the intrinsic Ly{\\alpha} EW distribution for a LAE sample at z $\\sim$ 4.5 in the Extended Chandra Deep Field South (ECDFS). Only weak Malmquist-type bias in both the intrinsic Ly{\\alpha} luminosity function and the Ly{\\alpha} EW distribution were found. However, the observed EW distribution is severely biased if one only considers LAEs with detections in the continuum. Taking the broadband non-detections into account requires fitting the distribution of the broadband-to-narrowband ratio, which then gives a larger EW distribution scale length. Assuming an exponential form of the intrinsic Ly{\\alpha} EW distribution dN/dEW = N exp(-EW/W$_0$), we obtain W$_0$ = 167+/-44{\\AA} (uncorrect...

Zheng, Zhen-Ya; Malhotra, Sangeeta; Rhoads, James E; Finkelstein, Steven L; Finkelstein, Keely

2013-01-01

22

Lyman Alpha Emitters in Hierarchical Galaxy Formation II. UV Continuum Luminosity Function and Equivalent Width Distribution  

CERN Document Server

We present theoretical predictions of UV continuum luminosity function (UV LF) and Lya equivalent width (EW) distribution of Lyman alpha emitters (LAEs) in the framework of the hierarchical clustering model of galaxy formation. The model parameters about LAEs were determined by fitting to the observed Lya LF at z=5.7 in our previous study, and the fit indicates that extinction of Lya photons by dust is significantly less effective than that of UV continuum photons, implying clumpy dust distribution in interstellar medium. We then compare the predictions about UV LFs and EW distributions with a variety of observations at z~3-6, allowing no more free parameters and paying careful attention to the selection conditions of LAEs in each survey. We find that the predicted UV LFs and EW distributions are in nice agreement with observed data, and especially, our model naturally reproduces the existence of large EW LAEs(> 240 A) without introducing Pop III stars or top-heavy initial mass function. We show that both the...

Kobayashi, Masakazu A R; Nagashima, Masahiro

2009-01-01

23

Ly? equivalent width distribution of Ly? emitting galaxies at redshift z ˜ 4.5  

Science.gov (United States)

Ly? line equivalent widths (EWs) provide important clues to the physical nature of high-redshift Lyman alpha emitters (LAEs). However, measuring the Ly? EW distribution of high-z narrow-band-selected LAEs can be hard because many sources do not have well-measured broad-band photometry. We investigate the possible biases in measuring the intrinsic Ly? EW distribution for a LAE sample at z ˜ 4.5 in the Extended Chandra Deep Field South (ECDFS). We show that our source selection procedures produce only weak Eddington type bias in both the intrinsic Ly? luminosity function and the Ly? EW distribution. However, the observed EW distribution is severely biased if one only considers LAEs with detections in the continuum. Taking the broad-band non-detections into account requires fitting the distribution of the broad-band-to-narrow-band ratio, which then gives a larger EW distribution scale length. Assuming an exponential form of the intrinsic Ly? EW distribution {d}N/{dEW} = N exp ^{-EW/W_0}, we obtain W0 = 167^{+44}_{-19} Å (uncorrected for IGM absorption of Ly?, and ?g = 160^{+43}_{-12} Å for a Gaussian EW distribution). We discuss the likely range of IGM absorption effects in light of recent measurements of Ly? line profiles and velocity offsets. Our data are consistent with Ly? EW being independent of UV luminosity (i.e. we do not see evidence for the `Ando' effect). Our simulations also imply that broad-band images should be 0.5-1 mag deeper than narrow-band images for an effective and reasonably complete LAE survey. Comparing with consistent measurements at other redshifts, we see a strong evolution in Ly? EW distribution with redshift which goes as a power-law form of W0 ? (1 + z)?, with ? = 1.1 ± 0.1 (0.6 ± 0.1) if no IGM corrections are applied to the Ly? line; or ? = 1.7 ± 0.1 (1.2 ± 0.1) after applying a maximal IGM-absorption correction to Ly? line for an exponential (a Gaussian) EW distribution from z = 0.3 to 6.5.

Zheng, Zhen-Ya; Wang, Jun-Xian; Malhotra, Sangeeta; Rhoads, James E.; Finkelstein, Steven L.; Finkelstein, Keely

2014-03-01

24

Photometry and H$alpha$ studies of a Low Mass Ratio Overcontact binary ASAS J082243+1927.0  

CERN Document Server

Both high precision CCD photometric and H$alpha$ line studies are presented for an overcontact binary ASAS J082243+1927.0. The light curve exhibits a total eclipse at secondary minima along with an O'Connell effect. The light curve was modeled using the Wilson Devinney code and the best solution provides the mass ratio q = 0.106 and fill-out factor f = 72%. These parameters indicate that the system is a low mass ratio overcontact binary with a high degree of geometrical contact. The H alpha line equivalent width varied at different phases and it is found that the line is possibly filled-in at secondary minima. From a small sample of overcontact binaries, we found a correlation between the orbital period and H alpha line equivalent width of the primary component. Based on a sample of high filling factor and low mass ratio contact binaries, a mass ratio cut-off is observed at q = 0.085 in mass ratio - period plane. It was observed that below q $\\le$ 0.085, period decreases with an increase in q and above it, pe...

Sriram, K; Rao, P Vivekananda

2014-01-01

25

Simultaneous H$\\alpha$, NaI D$_{1}$, D$_{2}$, and HeI D$_{3}$ observations of a flare on the RS CVn system UX Ari  

CERN Document Server

We present simultaneous H\\alpha, Na~{\\sc i} D_{1}, D_{2}, and He~{\\sc i} D_{3} spectroscopic observations on the RS CVn system UX Ari. We have found a dramatic increase in the excess H\\alpha emission equivalent width by a factor of 2 in an interval of 1 day that indicates the beginning of a strong flare in this system. The presence of the He~{\\sc i} D_{3} in emission in coincidence with the enhancement of the H\\alpha emission confirms the detection of a flare. The application of the spectral subtraction technique reveals that the core of the Na~{\\sc i} D_{1} and D_{2} lines are also filled-in by chromospheric emission.

Montes, D; Fernández-Figueroa, M J; Lorente, R

1996-01-01

26

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

Science.gov (United States)

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 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 H? 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

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

27

Late-type dwarf irregular galaxies in the Virgo cluster; 1, $H-\\alpha$ and red continuum data  

CERN Document Server

We present H-alpha and red continuum observations for a sample of late-type low surface brightness (LSB) dwarf irregular galaxies(DIGs), consisting of all the m_B<17.2 ImIV and V galaxies in the Virgo cluster (VC), and compare them with a representative sample of VC high surface brightness (HSB) DIGs. Line fluxes and equivalent widths are listed for individual HII regions and total H-alpha emission is measured for the entire DIG. The HII regions we identified do not produce all the line emission. For LSBs with line emission we find star formation rates (SFR) of 6.9-43.0 10^{-3} M_sol/yr, ~10x weaker than for HSB objects. About 2 HII regions are detected per LSB galaxy; they are smaller and fainter than in HSB galaxies in the VC, have line equivalent widths ~50% of those in HSBs, and cover similar fractions of the galaxies. The line-emitting regions of LSB galaxies are preferentially located at the periphery of a galaxy, while in HSBs they tend to be central. The line strength of an HII region is correlated...

Heller, A; Brosch, N; Heller, Ana; Almoznino, Elchanan; Brosch, Noah

1998-01-01

28

DEFPOS H${\\alpha}$ Observations of W80 Complex  

CERN Document Server

We present H${\\alpha}$ emission line measurements of the W80 nebular complex. A total of 26 regions have been observed inside the nebula with the Dual Etalon Fabry-Perot Optical Spectrometer (DEFPOS) system at the f/48 Coude focus of 150 cm RTT150 telescope located at TUBITAK National Observatory (TUG) in Antalya/Turkey. The intensities, the local standard of rest (LSR) velocities ($V_{LSR}$), heliocentric radial velocities ($V_{HEL}$) and the linewidths at Full Width at Half Maximum (FWHM) of the H${\\alpha}$ emission lines have been determined from these observations. They lie in the range of 259 to 1159 Rayleigh {1R = 10$^{6}/4\\pi$ photons cm$^{-2}$ sr$^{-1}$ s$^{-1}$ = 2.4110$^{-7}$ erg cm$^{-2}$ sr$^{-1}$ s$^{-1}$ at H${\\alpha}$.} (R), 4 to 12 km s$^{-1}$ and 44 to 55 km s$^{-1}$, respectively. The radial velocity measurements show that there are several maxima and minima inside the W80. The new results confirm the literature that complex seems to be rather a uniform in radial velocity and no seen turbule...

Aksaker, Naz\\im

2012-01-01

29

The stars with H-alpha missing  

Science.gov (United States)

During the course of a survey for ultraviolet-excess objects, a group of objects were found that spectroscopically resemble the subdwarf B stars, except for variable strength H-alpha absorption. The H-alpha line can have the nominal strength predicted from the other Balmer lines, or it can be completely absent. Observations reveal significant changes in the H-alpha profile on both a night-to-night and month-to-month basis. IUE observations of three stars reveal few features in the ultraviolet region and, when combined with optical data, allow a rough determination of photospheric temperatures. A binary model is proposed for these systems, and the ramifications of the objects found here and in the Palomar-Green survey are discussed.

Downes, Ronald A.

1987-01-01

30

High-redshift Ly alpha emitters with a large equivalent width: Properties of i-dropout galaxies with an NB921-band depression in the Subaru Deep Field  

CERN Document Server

We report new follow-up spectroscopy of i-dropout galaxies with an NB921-band depression found in the Subaru Deep Field. The NB921-depressed i-dropout selection method is expected to select galaxies with large equivalent width Ly alpha emission over a wide redshift range, 6.0equivalent widths are 153A and 114A, which are lower limits on the intrinsic equivalent widths. Through our spectroscopic observations (including previous ones) of NB921-depressed i-dropout galaxies, we identified 5 galaxies in total with a rest-frame equivalent width larger than 100A at 6.0equivalent width, in a wider redshift range than usual narrow-band excess techniques. B...

Nagao, T; Maiolino, R; Marconi, A; Kashikawa, N; Ajiki, M; Hattori, T; Ly, C; Malkan, M A; Motohara, K; Ohta, K; Sasaki, S S; Shioya, Y; Taniguchi, Y; Nagao, Tohru; Murayama, Takashi; Maiolino, Roberto; Marconi, Alessandro; Kashikawa, Nobunari; Ajiki, Masaru; Hattori, Takashi; Ly, Chun; Malkan, Matthew A.; Motohara, Kentaro; Ohta, Kouji; Sasaki, Shunji S.; Shioya, Yasuhiro; Taniguchi, Yoshiaki

2007-01-01

31

ON THE (NON-)ENHANCEMENT OF THE Ly{alpha} EQUIVALENT WIDTH BY A MULTIPHASE INTERSTELLAR MEDIUM  

Energy Technology Data Exchange (ETDEWEB)

It has been suggested that radiative transfer effects may explain the unusually high equivalent widths (EWs) of the Ly{alpha} line, observed occasionally from starburst galaxies, especially at high redshifts. If the dust is locked up inside high-density clouds dispersed in an empty intercloud medium, the Ly{alpha} photons could scatter off of the surfaces of the clouds, effectively having their journey confined to the dustless medium. The continuum radiation, on the other hand, does not scatter, and would thus be subject to absorption inside the clouds. This scenario is routinely invoked when Ly{alpha} EWs higher than what is expected theoretically are observed, although the ideal conditions under which the results are derived usually are not considered. Here we systematically examine the relevant physical parameters in this idealized framework, testing whether any astrophysically realistic scenarios may lead to such an effect. It is found that although clumpiness indeed facilitates the escape of Ly{alpha}, it is highly unlikely that any real interstellar media should result in a preferential escape of Ly{alpha} over continuum radiation. Other possible causes are discussed, and it is concluded that the observed high EWs are more likely to be caused by cooling radiation from cold accretion and/or anisotropic escape of the Ly{alpha} radiation.

Laursen, Peter; Duval, Florent; Oestlin, Goeran, E-mail: pela@dark-cosmology.dk [The Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, SE-10691 Stockholm (Sweden)

2013-04-01

32

DISSECTION OF H{alpha} EMITTERS : LOW-z ANALOGS OF z > 4 STAR-FORMING GALAXIES  

Energy Technology Data Exchange (ETDEWEB)

Strong H{alpha} emitters (HAEs) dominate the z {approx} 4 Lyman-break galaxy (LBG) population. We have identified local analogs of these HAEs using the Sloan Digital Sky Survey. At z < 0.4, only 0.04% of the galaxies are classified as HAEs with H{alpha} equivalent widths ({approx}> 500 A) comparable to that of z {approx} 4 HAEs. Local HAEs have lower stellar mass and lower ultraviolet (UV) luminosity than z {approx} 4 HAEs, yet the H{alpha}-to-UV luminosity ratio, as well as their specific star formation rate, is consistent with that of z {approx} 4 HAEs, indicating that they are scaled-down versions of high-z star-forming galaxies. Compared to the previously studied local analogs of LBGs selected using rest-frame UV properties, local HAEs show similar UV luminosity surface density, weaker D{sub n} (4000) break, lower metallicity, and lower stellar mass. This implies that the local HAEs are less evolved galaxies than the traditional Lyman break analogs. In the stacked spectrum, local HAEs show a significant He II {lambda}4686 emission line suggesting a population of hot, massive stars similar to that seen in some Wolf-Rayet galaxies. Low [N II]/[O III] line flux ratios imply that local HAEs are inconsistent with being systems that host bright active galactic nuclei. Instead, it is highly likely that local HAEs are galaxies with an elevated ionization parameter, either due to a high electron density or large escape fraction of hydrogen ionizing photons as in the case of Wolf-Rayet galaxies.

Shim, Hyunjin [Department of Earth Science Education, Kyungpook National University (Korea, Republic of); Chary, Ranga-Ram, E-mail: hjshim@knu.ac.kr [U.S. Planck Data Center, California Institute of Technology, MS 220-6, Pasadena, CA 91125 (United States)

2013-03-01

33

H$\\alpha$ Star Formation Rates of $z$ > 1 Galaxy Clusters in the IRAC Shallow Cluster Survey  

CERN Document Server

We present Hubble Space Telescope near-IR spectroscopy for 18 galaxy clusters at 1.0 < $z$ < 1.5 in the IRAC Shallow Cluster Survey. We use Wide Field Camera 3 grism data to spectroscopically identify H$\\alpha$ emitters in both the cores of galaxy clusters as well as in field galaxies. We find a large cluster-to-cluster scatter in the star formation rates within a projected radius of 500 kpc, and many of our clusters (~60%) have significant levels of star formation within a projected radius of 200 kpc. A stacking analysis reveals that dust reddening in these star-forming galaxies is positively correlated with stellar mass and may be higher in the field than the cluster at a fixed stellar mass. This may indicate a lower amount of gas in star-forming cluster galaxies than in the field population. Also, H$\\alpha$ equivalent widths of star-forming galaxies in the cluster environment are still suppressed below the level of the field. This suppression is most significant for lower mass galaxies (log M$_{*}$ &...

Zeimann, Gregory; Brodwin, Mark; Gonzalez, Anthony H; Mancone, Conor; Snyder, Gregory F; Stern, Daniel; Eisenhardt, Peter; Dey, Arjun; Moustakas, John

2013-01-01

34

Comparison of the Halpha equivalent width of HII regions in a flocculent and a grand design galaxy: possible evidences for IMF variations  

CERN Document Server

We present here a study of the Halpha equivalent widths of the flocculent galaxy NGC 4395 and the grand design galaxy NGC 5457. A difference between the mean values of the Halpha equivalent widths for the two galaxies has been found. Several hypotheses are presented in order to explain this difference: differences in age, metallicity, star formation rate, photon leakage and initial mass function. Various tests and Monte Carlo models are used to find out the most probable cause of this difference. The resultsshow that the possible cause for the difference could be a variation in the initial mass function. This difference is such that it seems to favor a fraction of more massive stars in the grand design galaxy when compared with the flocculent galaxy. This could be due to a change of the environmental conditions due to a density wave.

Cedres, B; Tomita, A; Cedres, Bernabe; Cepa, Jordi; Tomita, Akihiko

2005-01-01

35

ON THE ORIGINS OF THE DIFFUSE H{alpha} EMISSION: IONIZED GAS OR DUST-SCATTERED H{alpha} HALOS?  

Energy Technology Data Exchange (ETDEWEB)

It is known that the diffuse H{alpha} emission outside of bright H II regions not only are very extended, but also can occur in distinct patches or filaments far from H II regions, and the line ratios of [S II] {lambda}6716/H{alpha} and [N II] {lambda}6583/H{alpha} observed far from bright H II regions are generally higher than those in the H II regions. These observations have been regarded as evidence against the dust-scattering origin of the diffuse H{alpha} emission (including other optical lines), and the effect of dust scattering has been neglected in studies on the diffuse H{alpha} emission. In this paper, we reexamine the arguments against dust scattering and find that the dust-scattering origin of the diffuse H{alpha} emission cannot be ruled out. As opposed to the previous contention, the expected dust-scattered H{alpha} halos surrounding H II regions are, in fact, in good agreement with the observed H{alpha} morphology. We calculate an extensive set of photoionization models by varying elemental abundances, ionizing stellar types, and clumpiness of the interstellar medium (ISM) and find that the observed line ratios of [S II]/H{alpha}, [N II]/H{alpha}, and He I {lambda}5876/H{alpha} in the diffuse ISM accord well with the dust-scattered halos around H II regions, which are photoionized by late O- and/or early B-type stars. We also demonstrate that the H{alpha} absorption feature in the underlying continuum from the dust-scattered starlight ({sup d}iffuse galactic light{sup )} and unresolved stars is able to substantially increase the [S II]/H{alpha} and [N II]/H{alpha} line ratios in the diffuse ISM.

Seon, Kwang-Il [Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of); Witt, Adolf N., E-mail: kiseon@kasi.re.kr [Ritter Astrophysical Research Center, University of Toledo, Toledo, OH 43606 (United States)

2012-10-20

36

Study of a Complete Sample of H-alpha Emission-Line Galaxies  

Science.gov (United States)

The Universidad Complutense de Madrid survey is a long project with the aim of finding and analyzing star formation galaxies using the H-alpha line as the tracer for the massive star formation processes. In order to obtain a representative complete sample of such a technique, several objective prism plates were taken with the Schmidt telescope at Calar Alto Almeria (Spain). The combination of IIIaF Kodak emulsion and a RG630 filter was used for covering the red spectral region, from 6400A to a redshift of 0.045 for the H-alpha line. A compilation of descriptions and positions is presented for 272 emission-line candidates from 545 square degrees of the sky. Also apparent magnitude and equivalent width estimators are given. Spectroscopical observations were carried out for the full sample of H-alpha emission--line galaxy (ELGs) candidates. All the spectroscopic information is presented in the form of an appendix. Each ELG was classified into one of eight natural groups of star forming galaxies. The ELG types most commonly found (47%) are intermediate to low-luminosity objects with a very intense star-formation region which dominates the optical output of the galaxy. This kind of ELGs is similar to the galaxy population detected in the blue objective prism surveys, but what is more important, it was found a second population (43%) of star-forming galaxies with low ionization or high extinction properties. This ELGs group are not detected nor in the blue (University of Michigan survey) neither in other surveys (Kiso, IRAS, Markarian) using other selection techniques. Emission-line ratio diagnostic diagrams reveal that the ELGs in the different natural groups tend to have distinctly different line ratios. This suggests that the various ELGs types differ from one another in terms of metal abundance of their ionized gas, the ionization parameter and the relative importance of the starburst process in the galaxy, confirming a previous similar result found for the UM survey. There is present a trend for lower metallicities at lower luminosities. It has not been found any galaxy with metallicity lower than I Zw 18. >From the original IRAS data it was obtained for the whole sample the far-infrared fluxes. In the one hand it is necessary to apply a two-component model for reproducing the general behaviour of the UCM sample at that spectral range. In the other hand the FIR properties of a H-alpha selected sample are well differentiated against FIR-selected samples. The line+continuum flux is the main selection parameter for the UCM survey, but other secondary effects are discussed. An study of the luminosity and spatial distribution of the UCM galaxies is presented. The ELGs follow at great scale the distribution of the catalog galaxies. Using the UCM ELGs as SFR tracers a luminosity function for the SFR at the local Universe is computed. These result has important implications for our understanding of the origin of the star formation phenomena as well as the evolution of the galaxies. In the future, we propose to extend the survey to new sky regions and deeper redshifts and to quantify the SFR at the Local Universe by means of the UCM sample. The original is written in spanish. (SECTION: Dissertation Summary)

Gallego Maestro, Jesus

1995-07-01

37

Quantitative Fourier transform infrared diagnostics of the gas-phase composition using the HITRAN database and the equivalent width of the spectral features.  

Science.gov (United States)

This paper presents a strategy for quantification of medium resolution Fourier transform infrared (FT-IR) spectra. The approach is based on a comparison of the values of the equivalent width of spectral features determined from the measured FT-IR spectra with those calculated from corresponding molecular spectra simulated using spectroscopic parameters tabulated in the HITRAN database. Although the equivalent-width method is routinely applied in many high-resolution experiments, its potential is often ignored when the spectral resolution of the measurements is bigger than the width of the studied molecular transitions. Here with an eye on application of the method to the study of the biomass thermal decomposition products, we demonstrate the capability of the method for analysis of FT-IR spectra with moderate resolution. The method is validated for a number of molecules (NH3, CO, CH4, C2H2, C2H4, and NO) that are important products of biomass thermal decomposition. Namely, known amounts of gases were placed in a sample cell and their concentrations were determined using the method for different FT-IR settings. The agreement between the concentration values determined using the present method and those found in the sample cell was generally better than 10%. The paper also shows examples of application of the developed methodology for the analysis of FT-IR spectra from biomass pyrolysis. PMID:19891829

Sepman, A V; den Blanken, R; Schepers, R; de Goey, L P H

2009-11-01

38

On the origins of the diffuse H-alpha emission: Ionized gas or dust-scattered H-alpha halos?  

CERN Document Server

It is known that the diffuse H-alpha emission outside of bright H II regions not only are very extended, but also can occur in distinct patches or filaments far from H II regions, and the line ratios of [S II] 6716/H-alpha and [N II] 6583/H-alpha observed far from bright H II regions are generally higher than those in the H II regions. These observations have been regarded as evidence against the dust-scattering origin of the diffuse H-alpha emission (including other optical lines), and the effect of dust scattering has been neglected in studies on the diffuse H-alpha emission. In this paper, we reexamine the arguments against dust scattering and find that the dust-scattering origin of the diffuse H-alpha emission cannot be ruled out. As opposed to the previous contention, the expected dust- scattered H-alpha halos surrounding H II regions are, in fact, in good agreement with the observed H-alpha morphology. We calculate an extensive set of photoionization models by varying elemental abundances, ionizing stel...

Seon, Kwang-Il

2012-01-01

39

A Ly? Emitter with an Extremely Large Rest-frame Equivalent Width of ~900 Å at z = 6.5: A Candidate Population III-dominated Galaxy?  

Science.gov (United States)

We have identified a very interesting Ly? emitter (LAE), whose Ly? emission line has an extremely large observed equivalent width of EW0 = 436+422 - 149 Å, which corresponds to an extraordinarily large intrinsic rest-frame equivalent width of EWint 0 = 872+844 - 298 Å after the average intergalactic absorption correction. The object was spectroscopically confirmed to be a real LAE by its apparent asymmetric Ly? line profile detected at z = 6.538. The continuum emission of the object was definitely detected in our deep z'-band image; thus, its EW0 was reliably determined. Follow-up deep near-infrared spectroscopy revealed emission lines of neither He II ?1640 as an apparent signature of Population III (Pop III) nor C IV ?1549 as proof of an active nucleus. No detection of the short-lived He II ?1640 line is not necessarily inconsistent with the interpretation that the underlying stellar population of the object is dominated by Pop III. We found that the observed extremely large EW0 of the Ly? emission and the upper limit on the EW0 of the He II ?1640 emission can be explained by population synthesis models favoring a very young age less than 2-4 Myr and massive metal-poor (Z = 10-3. However, we cannot conclusively rule out the possibility that this object is composed of a normal stellar population with a clumpy dust distribution, which could enhance the Ly? EW0, though its significance is still unclear. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan, and the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Kashikawa, Nobunari; Nagao, Tohru; Toshikawa, Jun; Ishizaki, Yoshifumi; Egami, Eiichi; Hayashi, Masao; Ly, Chun; Malkan, Matthew A.; Matsuda, Yuichi; Shimasaku, Kazuhiro; Iye, Masanori; Ota, Kazuaki; Shibuya, Takatoshi; Jiang, Linhua; Taniguchi, Yoshiaki; Shioya, Yasuhiro

2012-12-01

40

Raman-Scattering Wings of H alpha in Symbiotic Stars  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Nussbaumer et al. (1989) proposed that broad H$\\alpha$ wings can be formed through Raman scattering of Ly$\\beta$ photons, and in this Letter we argue that the H$\\alpha$ wings prevalently seen in symbiotic stars may be indeed formed in this way. Assuming a flat incident UV radiation around Ly$\\beta$, we generate template wing profiles around H$\\alpha$ that are formed through Raman scattering in a plane-parallel H~I region. We perform profile fitting analyses to show that the ...

Lee, Hee-won

2000-01-01

 
 
 
 
41

Starbursts and Extra-planar H-alpha from SINGG  

CERN Document Server

The NOAO Survey for Ionization in Neutral Gas Galaxies (SINGG) is the largest star formation survey of an HI selected sample. Since the selection is made without regard to optical morphology, it is not biased toward or against "interesting" types of galaxies; thus SINGG is an ideal sample for studying galaxy demographics. Of a sample of 90 extra-galactic sources observed in photometric conditions, all are detected in H-alpha. This indicates that dormant galaxies, those containing an appreciable ISM but no star formation, are at best rare. We have made first pass morphological surveys for starbursts, as judged by H-alpha surface brightness, and outflows as judged by extra-planar H-alpha. We find that about 15% of the sources contain starbursts, with little dependence on the neutral hydrogen mass MHI. Nearly one half of a sample ~35 edge-on galaxies show evidence for extra-planar H-alpha having a scale size of 0.5 Kpc or larger, while nearly one quarter have extra-planar H-alpha features 1.0 Kpc in size or larg...

Meurer, G R

2003-01-01

42

Sensitivity of H alpha profiles to rapid electron beam fluctuations  

International Nuclear Information System (INIS)

In order to understand the temporal relationship between H alpha and hard x ray emission predicted by the nonthermal electron thick target model of impulsive-phase energy transport the time-dependent theoretical H alpha profiles were computed for the dynamic model atmospheres of Fisher, Canfield, and McClymont, which simulate the effects of an impulsively initiated power-law beam of electrons. On the basis of the physical analysis it was expected that a very rapid H alpha response to an instantaneous increase in the flux of a nonthermal deka-keV electron beam, as compared to the timescale associated with the propagation of these electrons over characteristic flare coronal loop spatial scales. It was concluded that observational efforts to test the thick target nonthermal electron model through detection of impulsive H alpha brightenings associated with impulsive hard x ray or microwave bursts should initially focus attention on the H alpha line center. Additional simultaneous blue-wing measurements will have substantial diagnostic potential

43

H\\alpha\\ Absorption in Transiting Exoplanet Atmospheres  

CERN Document Server

Absorption of stellar H\\alpha\\ by the upper atmosphere of the planet HD189733b has recently been detected by Jensen et al. Motivated by this observation, we have developed a model for atomic hydrogen in the n=2 state and compared the resulting H\\alpha\\ line profile to the observations. The model atmosphere is in hydrostatic balance, as well as thermal and photoionization equilibrium. Collisional and radiative transitions are included in the determination of the n=2 state level population. We find that H\\alpha\\ absorption is dominated by an optical depth \\tau\\ ~ 1 shell, composed of hydrogen in the metastable 2s state that is located below the hydrogen ionization layer. The number density of the 2s state within the shell is found to vary slowly with radius, while that of the 1s state falls rapidly. Thus while the Ly\\alpha absorption, for a certain wavelength, occurs inside a relatively well defined impact parameter, the contribution to H\\alpha\\ absorption is roughly uniform over the entire atomic hydrogen laye...

Christie, Duncan; Li, Zhi-Yun

2013-01-01

44

H\\alpha\\ Emission Variability in Active M Dwarfs  

CERN Document Server

We use ~12,000 spectra of ~3,500 magnetically active M0-M9 dwarfs from the Sloan Digital Sky Survey taken at 10-15 minute intervals, together with ~300 spectra of ~60 M0-M8 stars obtained hourly with the Hydra multi-object spectrometer, to probe H\\alpha\\ variability on timescales of minutes to weeks. With multiple observations for every star examined, we are able to characterize fluctuations in H\\alpha emission as a function of activity strength and spectral type. Stars with greater magnetic activity (as quantified by L_H\\alpha/L_bol) are found to be less variable at all spectral types. We attribute this result to the stronger level of persistent emission in the high activity stars, requiring a larger heating event in order to produce measurable variability. We also construct H\\alpha\\ structure functions to constrain the timescale of variability. The more active objects with lower variability exhibit a characteristic timescale longer than an hour, likely due to larger, longer lasting heating events, while the...

Bell, Keaton J; Davenport, James R A; Hawley, Suzanne L; West, Andrew A; Rogel, Allen B

2011-01-01

45

The Wisconsin H-Alpha Mapper Northern Sky Survey  

CERN Document Server

The Wisconsin H-Alpha Mapper (WHAM) has surveyed the distribution and kinematics of ionized gas in the Galaxy above declination -30 degrees. The WHAM Northern Sky Survey (WHAM-NSS) has an angular resolution of one degree and provides the first absolutely-calibrated, kinematically-resolved map of the H-Alpha emission from the Warm Ionized Medium (WIM) within ~ +/-100 km/s of the Local Standard of Rest. Leveraging WHAM's 12 km/s spectral resolution, we have modeled and removed atmospheric emission and zodiacal absorption features from each of the 37,565 spectra. The resulting H-Alpha profiles reveal ionized gas detected in nearly every direction on the sky with a sensitivity of 0.15 R (3 sigma). Complex distributions of ionized gas are revealed in the nearby spiral arms up to 1-2 kpc away from the Galactic plane. Toward the inner Galaxy, the WHAM-NSS provides information about the WIM out to the tangent point down to a few degrees from the plane. Ionized gas is also detected toward many intermediate velocity cl...

Haffner, L M; Tufte, S L; Madsen, G J; Jaehnig, K P; Percival, J W

2003-01-01

46

H-alpha Spectral diversity of type II supernovae  

CERN Document Server

We present a spectroscopic analysis of the H-alpha profiles of hydrogen-rich type II supernovae. A total of 52 type II supernovae having well sampled optical light curves and spectral sequences were analyzed. Concentrating on the H-alpha P-Cygni profile we measure its velocity from the FWHM of emission and the ratio of absorption to emission (a/e) at a common epoch at the start of the recombination phase, and search for correlations between these spectral parameters and photometric properties of the V-band light curves. Testing the strength of various correlations we find that a/e appears to be the dominant spectral parameter in terms of describing the diversity in our measured supernova properties. It is found that supernovae with smaller a/e have higher H-alpha velocities, more rapidly declining light curves from maximum, during the plateau and radioactive tail phase, are brighter at maximum light and have shorter optically thick phase durations. We discuss possible explanations of these results in terms of...

Gutiérrez, Claudia P; Hamuy, Mario; González-Gaitán, Santiago; Folatelli, Gastón; Morrell, Nidia I; Stritzinger, Maximilian D; Phillips, Mark M; McCarthy, Patrick; Suntzeff, Nicholas B; Thomas-Osip, Joanna

2014-01-01

47

A Survey for H$\\alpha$ Pulsar Bow Shocks  

CERN Document Server

We report on a survey for H$\\alpha$ bow shock emission around nearby $\\gamma$-detected energetic pulsars. This survey adds three Balmer-dominated neutron star bow shocks to the six previously confirmed examples. In addition to the shock around {\\it Fermi} pulsar PSR J1741$-$2054, we now report H$\\alpha$ structures around two additional $\\gamma$-ray pulsars, PSR J2030+4415 and PSR J1509$-$5850. These are the first known examples of H$\\alpha$ nebulae with pre-ionization halos. With new measurements, we show that a simple analytic model can account for the angular size and flux of the bow shocks' apices. The latter, in particular, provides a new pulsar probe and indicates large moments of inertia and smaller distances than previously assumed, in several cases. In particular we show that the re-measured PSR J0437$-$4715 shock flux implies $I = (1.7\\pm 0.2) \\times 10^{45}/(f_{HI} {\\rm sin}i) {\\rm g\\,cm^2}$. We also derive a distance $d\\approx 0.72$kpc for the $\\gamma$-ray only pulsar PSR J2030+4415 and revised dis...

Brownsberger, Sasha

2014-01-01

48

Impact of non-LTE effects on the IR Ca II triplet and the Mg I 8736 Å equivalent widths in late-type giant and super-giant stars  

Science.gov (United States)

Calcium and magnesium are key ?-elements to study stellar populations in galaxies. Classical stellar abundances analyses rely on the local thermodynamic equilibrium (LTE) assumption which is not always appropriate, in particular for metal-poor and/or evolved stars. To better understand these stars and apprehend their impacts on the chemical enrichment of the Galaxy, it is necessary to use a Non-LTE (NLTE) description which is more realistic but also more complex to build up. For the calcium (Ca) and magnesium (Mg) lines in the RVS@Gaia, we computed theoretical NLTE corrections to apply to the measured equivalent widths of these lines using very complete model atoms of Mg and Ca. These corrections can be used by the automated abundance analysis methods based on equivalent widths for current and forthcoming large surveys.

Merle, T.; Thévenin, F.; Pichon, B.; Bigot, L.

2012-12-01

49

3.5 mm depression features associated with H-alpha 'disparitions brusques'. [solar prominence brightness temperature depressions associated with H alpha filament disappearance  

Science.gov (United States)

The characteristics of 3.5-mm depression features associated with two 'disparation brusques' observed in H-alpha are discussed. The millimeter depressions still exist, although reduced in strength, after the disappearance of the H-alpha filament. The two depressions correspond to temperatures of 600 and 450 K before and to 200 and 250 K after the disappearance of the H-alpha filament.

Kundu, M. R.; Lantos, P.

1977-01-01

50

A DETECTION OF H{alpha} IN AN EXOPLANETARY EXOSPHERE  

Energy Technology Data Exchange (ETDEWEB)

We report on a search for H{alpha} absorption in four exoplanets. Strong features at H{alpha} are observed in the transmission spectra of both HD 189733b and HD 209458b. We attempt to characterize and remove the effects of stellar variability in HD 189733b, and along with an empirical Monte Carlo test the results imply a statistically significant transit-dependent feature of (- 8.72 {+-} 1.48) Multiplication-Sign 10{sup -4} integrated over a 16 A band relative to the adjacent continuum. We interpret this as the first detection of this line in an exoplanetary atmosphere. A previous detection of Ly{alpha} in HD 189733b's atmosphere allows us to calculate an excitation temperature for hydrogen, T{sub exc} = 2.6 Multiplication-Sign 10{sup 4} K. This calculation depends significantly on certain simplifying assumptions. We explore these assumptions and argue that T{sub exc} is very likely much greater than the radiative equilibrium temperature (the temperature the planet is assumed to be at based on stellar radiation and the planetary distance) of HD 189733b. A large T{sub exc} implies a very low density that is not in thermodynamic equilibrium with the planet's lower atmosphere. We argue that the n = 2 hydrogen required to cause H{alpha} absorption in the atmosphere is created as a result of the greater UV flux at HD 189733b, which has the smallest orbit and most chromospherically active central star in our sample. Though the overall integration of HD 209458b's transmission spectrum over a wide band is consistent with zero, it contains a dramatic, statistically significant feature in the transmission spectrum with reflectional symmetry. We discuss possible physical processes that could cause this feature. Our remaining two targets (HD 147506b and HD 149026b) do not show any clear features, so we place upper limits on their H{alpha} absorption levels.

Jensen, Adam G.; Redfield, Seth [Van Vleck Observatory, Astronomy Department, Wesleyan University, 96 Foss Hill Drive, Middletown, CT 06459 (United States); Endl, Michael; Cochran, William D.; Koesterke, Lars [Department of Astronomy, University of Texas, Austin, TX 78712 (United States); Barman, Travis, E-mail: Adam.Jensen@gmail.com, E-mail: sredfield@wesleyan.edu, E-mail: mike@astro.as.utexas.edu, E-mail: wdc@astro.as.utexas.edu, E-mail: lars@tacc.utexas.edu, E-mail: barman@lowell.edu [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States)

2012-06-01

51

A Detection Of H-alpha In An Exoplanetary Exosphere  

CERN Document Server

We report on a search for H-alpha absorption in four exoplanets. Strong features at H-alpha are observed in the transmission spectra of both HD 189733b and HD 209458b. We attempt to characterize and remove the effects of stellar variability in HD 189733b, and along with an empirical Monte Carlo test the results imply a statistically significant transit-dependent feature of (-8.72+/-1.48)x10^-4 integrated over a 16 Angstrom band relative to the adjacent continuum. We interpret this as the first detection of this line in an exoplanetary atmosphere. A previous detection of Ly-alpha in HD 189733b's atmosphere allows us to calculate an excitation temperature for hydrogen, T_exc=2.6x10^4 K. This calculation depends significantly on certain simplifying assumptions. We explore these assumptions and argue that T_exc is very likely much greater than the radiative equilibrium temperature (the temperature the planet is assumed to be at based on stellar radiation and the planetary distance) of HD 189733b. A large T_exc im...

Jensen, Adam G; Endl, Michael; Cochran, William D; Koesterke, Lars; Barman, Travis S

2012-01-01

52

Spectral Properties From Lyman-alpha to H-alpha For An Essentially Complete Sample of Quasars I: Data  

CERN Document Server

We have obtained quasi-simultaneous ultraviolet-optical spectra for 22 out of 23 quasars in the complete PG-X-ray sample with redshift, z<0.4, and M_B<-23. The spectra cover rest-frame wavelengths from at least Lyman-alpha to H-alpha. Here we provide a detailed description of the data, including careful spectrophotometry and redshift determination. We also present direct measurements of the continua, strong emission lines and features, including Lyman-alpha, SiIV+OIV], CIV, CIII], SiIII], MgII, H-beta, [OIII], He5876+NaI5890,5896, H-alpha, and blended iron emission in the UV and optical. The widths, asymmetries and velocity shifts of profiles of strong emission lines show that CIV and Lyman-alpha are very different from H-beta and H-alpha. This suggests that the motion of the broad line region is related to the ionization structure, but the data appears not agree with the radially stratified ionization structure supported by reverberation mapping studies, and therefore suggest that outflows contribute a...

Shang, Z; Wills, D; Brotherton, M S; Shang, Zhaohui; Wills, Beverley J.; Brotherton, Michael S.

2007-01-01

53

Solar H-alpha Oscillations from Intensity and Doppler Observations  

CERN Document Server

Chromospheric wave activity around flares and filaments has been a research focus for years, and could provide indirect measurements of local conditions that are not otherwise accessible. One interesting observed phenomenon is oscillations in filaments, activated by distant flares and the large-scale waves they produce. Characteristics of these oscillations, such as periods, amplitudes, and lifetimes, can provide unique information about the filament. We measure oscillation properties in flares and filaments from H-alpha chromospheric data using a new method that provides important spatial and frequency content of the dynamics. We apply the method to two flare events where filaments are observed to oscillate and determine their properties. We find strong oscillatory signal in flaring active regions in the chromosphere over a range of frequencies. Two filaments are found to oscillate without any detectable chromospheric wave acting as an activation mechanism. We find that filaments oscillate with periods of te...

Jackiewicz, J

2013-01-01

54

Umbral oscillations and penumbral waves in H alpha. [in sunspots  

Science.gov (United States)

Examples are presented of umbral oscillations observed on Big Bear H-alpha filtergram movies, and the relation between umbral oscillations and running penumbral waves occurring in the same sunspot is investigated. Umbral oscillations near the center of the umbra are probably physically independent of the penumbral waves because the period of these umbral oscillations (150 sec) is shorter than the penumbral wave period (270 sec), but not a harmonic. Dark puffs emerge from the edge of the umbra and move outward across the penumbra, and have the same period as the running penumbral waves. These dark puffs are interpreted to be the extension of chromospheric umbral oscillations at the edge of the umbra. It is suggested that the dark puffs and the running penumbral waves have a common source: photospheric oscillations just inside the umbra.

Moore, R. L.; Tang, F.

1975-01-01

55

Observational Tests to Detect Photometric Reverberation in H-alpha  

Science.gov (United States)

We present photometric observations of several AGN that were secured with the 0.9-m telescope located at the West Mountain Observatory that is operated by Brigham Young University. The new observations use standard BVR filters along with several custom filters that are part of a red shifted H-alpha set. Light curves are presented for several of the targets along with a summary of the analysis made to detect lag times between the continuum and broad emission line flux as evidence for photometric reverberation. Plans are presented for future research that will continue along these lines.We thank the Department of Physics and Astronomy along with the College of Physical and Mathematical Sciences at Brigham Young University for continued support of the research work being done at the West Mountain Observatory.

Joner, Michael D.; Carroll, Carla

2014-06-01

56

Pulsar H(alpha) Bowshocks probe Neutron Star Physics  

Science.gov (United States)

We propose a KOALA/AAOmega study of southern pulsar bow shocks. These rare, Balmer-dominated, non-radiative shocks provide an ideal laboratory to study the interaction of the relativistic pulsar wind with the ISM. We will cover H(alpha) at high spectral resolution to measure the kinematics of the upstream ISM and the post-shock flow, while the blue channel measures the Balmer decrement and probes for a faint cooling component. These data, with MHD models, allow us to extract the 3D flow geometry and the orientation and asymmetry of the pulsar wind. These data can also measure the pulsar spindown power, thus estimating the neutron star moment of inertia and effecting a fundamental test of dense matter physics.

Romani, Roger W.

2014-08-01

57

A Ly-alpha Emitter with an Extremely Large Rest-frame Equivalent Width of ~900A at z=6.5: A Candidate of Population III-dominated Galaxy?  

CERN Document Server

We have identified a very interesting Ly-alpha emitter, whose Ly-alpha emission line has an extremely large observed equivalent width of EW_0=436^{+422}_{-149}A, which corresponds to an extraordinarily large intrinsic rest-frame equivalent width of EW_0^{int}=872^{+844}_{-298}A after the average intergalactic absorption correction. The object was spectroscopically confirmed to be a real Ly-alpha emitter by its apparent asymmetric Ly-alpha line profile detected at z=6.538. The continuum emission of the object was definitely detected in our deep z'-band image; thus, its EW_0 was reliably determined. Follow-up deep near-infrared spectroscopy revealed emission lines of neither He II lambda1640 as an apparent signature of Population III, nor C IV lambda1549 as a proof of active nucleus. No detection of short-lived He II lambda1640 line is not necessarily inconsistent with the interpretation that the underlying stellar population of the object is dominated by Population III. We found that the observed extremely lar...

Kashikawa, Nobunari; Toshikawa, Jun; Ishizaki, Yoshifumi; Egami, Eiichi; Hayashi, Masao; Ly, Chun; Malkan, Matthew A; Matsuda, Yuichi; Shimasaku, Kazuhiro; Iye, Masanori; Ota, Kazuaki; Shibuya, Takatoshi; Jiang, Linhua; Taniguchi, Yoshiaki; Shioya, Yasuhiro

2012-01-01

58

On the Origins of the High-Latitude H-alpha Background  

CERN Document Server

The diffuse high-latitude H-alpha background is widely believed to be predominantly the result of in-situ recombination of ionized hydrogen in the warm interstellar medium of the Galaxy. Instead, we show that both a substantial fraction of the diffuse high-latitude H-alpha intensity in regions dominated by Galactic cirrus dust and much of the variance in the high-latitude H-alpha background are the result of scattering by interstellar dust of H-alpha photons originating elsewhere in the Galaxy. We provide an empirical relation, which relates the expected scattered H-alpha intensity to the IRAS 100um diffuse background intensity, applicable to about 81% of the entire sky. The assumption commonly made in reductions of CMB observations, namely that the observed all-sky map of diffuse H-alpha light is a suitable template for Galactic free-free foreground emission, is found to be in need of reexamination.

Witt, A N; Barnes, F S; DeRoo, C T; Vijh, U P; Madsen, G J

2010-01-01

59

An H-alpha survey of the rich cluster A1689  

Digital Repository Infrastructure Vision for European Research (DRIVER)

(Abridged) We present results of an H-alpha survey in the rich cluster A1689 at z=0.18, using the LDSS++ spectrograph on the AAT. We obtained spectra covering redshifted H-alpha for 522 galaxies brighter than I=22.5, covering a field of 8.7'X8.7'. We detect H-alpha emission in 46 of these galaxies; accounting for selection effects due to sampling and cluster membership, we determine that 24% of cluster members brighter than M_R=-16.5+5log(h) are detected with H-alpha flux gr...

Balogh, Michael; Couch, Warrick J.; Smail, Ian; Bower, Richard G.; Glazebrook, Karl

2002-01-01

60

The Lyman-alpha/H-alpha ratio in solar flares and quasars  

Science.gov (United States)

Constant temperature and density solar flare models are constructed with temperature and hydrogen density values that reflect reasonable nonlinear averages of those parameters in the depth dependent solar flare chromosphere models of Lites and Cook (1979). Acceptable values of the intensity ratios L-alpha/H-alpha and H-beta/H-alpha correspond to temperatures from about 9000 to 13,000 K, and hydrogen densities from 10 to the 11th to 10 to the 15th cu cm. The H-alpha and Ly-alpha source functions are thermalized at depths consistent with those inferred from independent studies, although the observed Ly-alpha/H-alpha ratio does not necessarily imply an electron temperature appropriate to the Planck function ratio. It is also shown that the value of Ly-alpha/H-alpha depends on the temperature, hydrogen density, and the optical depth of the emitting chromospheric layer.

Canfield, R. C.; Puetter, R. C.; Ricchiazzi, P. J.

1981-01-01

 
 
 
 
61

Dust Attenuation and H(alpha) Star Formation Rates of Z Approx. 0.5 Galaxies  

Science.gov (United States)

Using deep narrow-band and broad-band imaging, we identify 401 z approximately 0.40 and 249 z approximately 0.49 H-alpha line-emitting galaxies in the Subaru Deep Field. Compared to other H-alpha surveys at similar redshifts, our samples are unique since they probe lower H-alpha luminosities, are augmented with multi-wavelength (rest-frame 1000AA--1.5 microns) coverage, and a large fraction (20%) of our samples has already been spectroscopically confirmed. Our spectra allow us to measure the Balmer decrement for nearly 60 galaxies with H-beta detected above 5-sigma. The Balmer decrements indicate an average extinction of A(H-alpha)=0.7(uparrow){+1.4}_{-0.7} mag. We find that the Balmer decrement systematically increases with higher H-alpha luminosities and with larger stellar masses, in agreement with previous studies with sparser samples. We find that the SFRs estimated from modeling the spectral energy distribution (SED) is reliable---we derived an "intrinsic" H-alpha luminosity which is then reddened assuming the color excess from SED modeling. The SED-predicted H-alpha luminosity agrees with H-alpha narrow-band measurements over 3 dex (rms of 0.25 dex). We then use the SED SFRs to test different statistically-based dust corrections for H-alpha and find that adopting one magnitude of extinction is inappropriate: galaxies with lower luminosities are less reddened. We find that the luminosity-dependent dust correction of Hopkins et al. yields consistent results over 3 dex (rms of 0.3 dex). Our comparisons are only possible by assuming that stellar reddening is roughly half of nebular reddening. The strong correspondence argue that with SED modeling, we can derive reliable intrinsic SFRs even in the absence of H-alpha measurements at z approximately 0.5.

Ly, Chun; Malkan, Matthew A.; Kashikawa, Nobunari; Ota, Kazuaki; Shimasaku, Kazuhiro; Iye, Masanori; Currie, Thayne

2012-01-01

62

H-alpha Filaments and Feedback in NGC4696 at the centre of the Centaurus cluster  

Science.gov (United States)

One third of Brightest Cluster Galaxies (BCG) have strong opticalemission lines originating in an extensive filamentary nebula. Theprototype is the spectacular nebula around NGC1275 in the Perseuscluster which we are have imaged in H-alpha and [NII] with HST,spatially resolving the filamentary structure. Here we propose deepobservations of the nebula in NGC4696, the BCG in the Centaurus cluster.NGC4696, at approximately half the distance of NGC1275 is the nearestBCG nebula with molecular filaments, thus affording the highest linearspatial resolution in this type of source.These observations will test the magnetic support model for thefilaments by resolving and measuring the width of the filaments, andtest the particle heating model for the excitation of the filamentsthrough measurement of their surface brightness distribution andmorphology.The relation of the filaments to the dust lanes, and the complex FaradayRotation maps of this source will provide further diagnostics notavailable in NGC1275. The results will have a wide relevance to similarnebulae found around distant radio galaxies and young galaxies.

Fabian, Andrew

2014-10-01

63

Width issues  

International Nuclear Information System (INIS)

Current practices at British Columbia Hydro establish right-of-way widths on the basis of Canadian Standards Association (CSA) standards and BC Hydro standards and practices. The CSA sets certain minimum requirements which are increased by BC Hydro engineers to suit local conditions and design or maintenance requirements. As part of a general review of the utility's rights-of-way policies, a task team was established to consider the following issues related to right-of-way width: CSA and BC Hydro standards and practices; future use of rights-of-way by BC Hydro; electromagnetic interference; audible noise; public safety; right-of-way width for underground circuits; incorporation of setbacks in municipal bylaws; legislative approaches; and land use and development. Recommendations for continuation or modification of current practices are made in each of the issue areas. Justifications are provided for the recommendations, along with costs of implementation and alternative options

64

The H-alpha Luminosity Function and Star-Formation Rate Volume Density at z=0.8 from the NEWFIRM H-alpha Survey  

CERN Document Server

[Abridged] We present new measurements of the H-alpha luminosity function (LF) and SFR volume density for galaxies at z~0.8. Our analysis is based on 1.18$\\mu$m narrowband data from the NEWFIRM H-alpha Survey, a comprehensive program designed to capture deep samples of intermediate redshift emission-line galaxies using narrowband imaging in the near-infrared. The combination of depth ($\\approx1.9\\times10^{-17}$ erg s$^{-1}$ cm$^{-2}$ in H-alpha at 3$\\sigma$) and areal coverage (0.82 deg$^2$) complements other recent H-alpha studies at similar redshifts, and enables us to minimize the impact of cosmic variance and place robust constraints on the shape of the LF. The present sample contains 818 NB118 excess objects, 394 of which are selected as H-alpha emitters. Optical spectroscopy has been obtained for 62% of the NB118 excess objects. Empirical optical broadband color classification is used to sort the remainder of the sample. A comparison of the LFs constructed for the four individual fields reveals signific...

Ly, Chun; Dale, Daniel A; Momcheva, Ivelina; Salim, Samir; Staudaher, Shawn; Moore, Carolynn A; Finn, Rose

2010-01-01

65

Observatons of NGC 3077 Galaxy in Narrow Band [SII] and H_alpha Filters  

CERN Document Server

We present observations of the HI tidal arm near dwarf galaxy NGC 3077 (member of the M81 galaxy group) in narrow band [SII] and H_alpha filters. Observations were carried out in March 2011 with the 2m RCC telescope at NAO Rozhen, Bulgaria. Our search for possible supernova remnant candidates (identified as sources with enhanced [SII] emission relative to their H_alpha emission) in this region yielded no sources of this kind. Nevertheless, we found a number of objects with significant H_alpha emission that probably represent uncatalogued, low brightness HII regions.

Andjelic, M; Arbutina, B; Ilic, D; Urosevic, D

2011-01-01

66

The H-alpha Variations of eta Carinae During the 2009.0 Spectroscopic Event  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report on H-alpha spectroscopy of the 2009.0 spectroscopic event of eta Carinae collected via SMARTS observations using the CTIO 1.5 m telescope and echelle spectrograph. Our observations were made almost every night over a two month interval around the predicted minimum of eta Car. We observed a significant fading of the line emission that reached a minimum seven days after the X-ray minimum. About 17 d prior to the H-alpha flux minimum, the H-alpha profile exhibited the...

Richardson, N. D.; Gies, D. R.; Henry, T. J.; Fernandez-lajus, E.; Okazaki, A. T.

2010-01-01

67

The Discovery of a Giant H-alpha Filament in NGC 7213  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The nearby Seyfert galaxy NGC 7213 has been imaged in H-alpha and HI with the CTIO 1.5 m telescope and with the Australia Telescope Compact Array (ATCA), respectively. Optically NGC 7213 looks undisturbed and relatively featureless but the continuum-subtracted H-alpha image shows a 19 kpc long filament located approximately 18.6 kpc from the nucleus. The H-alpha filament could be neutral gas photo-ionized by the active nucleus, as has been suggested for the Seyfert galaxy NG...

Hameed, Salman; Blank, David; Young, Lisa; Devereux, Nick

2000-01-01

68

Spatially Resolved H(alpha)-Emitting Wind Structure of P Cygni.  

Science.gov (United States)

High spatial resolution observations of the H(alpha)-emitting wind structure associated with the luminous blue variable star P Cygni were obtained with the Navy Prototype Optical Interferometer. These observations represent the most comprehensive interfer...

A. Balan, C. Tycner, D. J. Hutter, J. A. Benson, R. T. Zavala

2010-01-01

69

Correlations between MIR, FIR, H$\\alpha$, and FUV Luminosities for SWIRE galaxies  

CERN Document Server

e present and analyze the correlations between mid-infrared (MIR), far-infrared (FIR), total-infrared (TIR), H$\\alpha$, and FUV luminosities for star-forming galaxies, composite galaxies and AGNs, based on a large sample of galaxies selected from the $Spitzer$ SWIRE fields. The MIR luminosities of star-forming galaxies are well correlated with their H$\\alpha$, TIR and FUV luminosities, and we re-scaled the MIR-derived SFR formulae according to the above correlations with differences less than 15%. We confirm the recent result by calzetti et al. (2007) that the combined observed H$\\alpha$ + 24$\\mu$m luminosities L(H$\\alpha IR and TIR luminosities are completely following those of star-forming galaxies.

Zhu, Yi-Nan; Cao, Chen; Li, Hai-Ning

2008-01-01

70

Detection of H alpha emission in a methane (T type) brown dwarf  

Science.gov (United States)

We report the detection of H alpha emission in the T dwarf (methane brown dwarf) 2MASSW J1237392 + 652615 over three days using the Keek Low esolution Imaging Spectrograph. The measured line flux, log (L-H alpha/L-bol) = -4.3, is roughly consistent with early M dwarf activity levels and inconsistent with decreasing activity trends in late M and L dwarfs. Similar emission is not seen in two other T dwarfs.

Burgasser, A.; Kirkpatrick, J.; Reid, I.; Liebert, J.; Gizis, J.; Brown, M.

2000-01-01

71

The Spatially Resolved H\\alpha-Emitting Wind Structure of P Cygni  

CERN Document Server

High spatial resolution observations of the H\\alpha-emitting wind structure associated with the Luminous Blue Variable star P Cygni were obtained with the Navy Prototype Optical Interferometer (NPOI). These observations represent the most comprehensive interferometric data set on P Cyg to date. We demonstrate how the apparent size of the H\\alpha-emitting region of the wind structure of P Cyg compares between the 2005, 2007 and 2008 observing seasons and how this relates to the H\\alpha line spectroscopy. Using the data sets from 2005, 2007 and 2008 observing seasons, we fit a circularly symmetric Gaussian model to the interferometric signature from the H\\alpha-emitting wind structure of P Cyg. Based on our results we conclude that the radial extent of the H\\alpha-emitting wind structure around P Cyg is stable at the 10% level. We also show how the radial distribution of the H\\alpha flux from the wind structure deviates from a Gaussian shape, whereas a two-component Gaussian model is sufficient to fully describ...

Balan, Aurelian; Zavala, R T; Benson, J A; Hutter, D J; Templeton, M

2010-01-01

72

Dust Attenuation and H-alpha Star Formation Rates of z~0.5 Galaxies  

CERN Document Server

Using deep narrow-band and broad-band imaging, we identify 401 z~0.40 and 249 z~0.49 H-alpha line-emitting galaxies in the Subaru Deep Field. Compared to other H-alpha surveys at similar redshifts, our samples are unique since they probe lower H-alpha luminosities, are augmented with multi-wavelength (rest-frame 1000AA--1.5 microns) coverage, and a large fraction (20%) of our samples has already been spectroscopically confirmed. Our spectra allow us to measure the Balmer decrement for nearly 60 galaxies with H-beta detected above 5-sigma. The Balmer decrements indicate an average extinction of A(H-alpha)=0.7^{+1.4}_{-0.7} mag. We find that the Balmer decrement systematically increases with higher H-alpha luminosities and with larger stellar masses, in agreement with previous studies with sparser samples. We find that the SFRs estimated from modeling the spectral energy distribution (SED) is reliable---we derived an "intrinsic" H-alpha luminosity which is then reddened assuming the color excess from SED modeli...

Ly, Chun; Kashikawa, Nobunari; Ota, Kazuaki; Shimasaku, Kazuhiro; Iye, Masanori; Currie, Thayne

2012-01-01

73

A Comparison of UIT Far-Ultraviolet and H alpha Star Formation Rates  

CERN Document Server

We have used archival ultraviolet (UV) imaging of 50 nearby star-forming galaxies obtained with the Ultraviolet Imaging Telescope (UIT) to derive integrated near-UV and far-UV magnitudes, and have combined these data with H alpha, far-infrared, and thermal radio continuum measurements to explore the consistency of UV and H alpha star formation rates (SFRs). In agreement with previous studies, we find that the UV and H alpha SFRs are qualitatively consistent, even before corrections for extinction are applied. The uncorrected UV SFRs are systematically lower by a factor of 1.5 (with a factor of two scatter) among luminous galaxies with SFRs over 1 solar mass per year, indicating a higher effective attenuation of the far-UV radiation. Among less luminous galaxies there is no significant offset between the H alpha and far-UV SFR scales. Far-infrared and thermal radio continuum data available for a subset of our sample allow us to estimate the attenuation in the UV and at H alpha independently. The UV and H alpha...

Bell, E F

2000-01-01

74

An H-alpha survey of the rich cluster A1689  

CERN Document Server

(Abridged) We present results of an H-alpha survey in the rich cluster A1689 at z=0.18, using the LDSS++ spectrograph on the AAT. We obtained spectra covering redshifted H-alpha for 522 galaxies brighter than I=22.5, covering a field of 8.7'X8.7'. We detect H-alpha emission in 46 of these galaxies; accounting for selection effects due to sampling and cluster membership, we determine that 24% of cluster members brighter than M_R=-16.5+5log(h) are detected with H-alpha flux greater than 4h^{-2}X 10^{38} ergs/s. This corresponds to a limiting star formation rate of 0.008 h^{-2} Msun/yr, assuming 1 magnitude of dust extinction. From a Hubble Space Telescope mosaic covering 7.5' X 10.0', we determine morphologies for 199 galaxies brighter than I=21, and find that 20% of the cluster members are of type Sa or later. More than 90% of cluster spirals show H-alpha emission, compared with less than 10% of E and S0 galaxies. The cluster H-alpha luminosity function has a low normalisation relative to the z~0.2 field, by ~...

Balogh, M; Smail, I; Bower, R G; Glazebrook, K; Balogh, Michael; Couch, Warrick J.; Smail, Ian; Bower, Richard G.; Glazebrook, Karl

2002-01-01

75

NEBULAR ATTENUATION IN H{alpha}-SELECTED STAR-FORMING GALAXIES AT z = 0.8 FROM THE NewH{alpha} SURVEY  

Energy Technology Data Exchange (ETDEWEB)

We present measurements of the dust attenuation of H{alpha}-selected emission-line galaxies at z = 0.8 from the NewH{alpha} narrowband survey. The analysis is based on deep follow-up spectroscopy with Magellan/IMACS, which captures the strong rest-frame optical emission lines from [O II] {lambda}3727 to [O III] {lambda}5007. The spectroscopic sample used in this analysis consists of 341 confirmed H{alpha} emitters. We place constraints on the active galactic nucleus (AGN) fraction using diagnostics that can be applied at intermediate redshift. We find that at least 5% of the objects in our spectroscopic sample can be classified as AGNs and 2% are composite, i.e., powered by a combination of star formation and AGN activity. We measure the dust attenuation for individual objects from the ratios of the higher order Balmer lines. The H{beta} and H{gamma} pair of lines is detected with S/N > 5 in 55 individual objects and the H{beta} and H{delta} pair is detected in 50 individual objects. We also create stacked spectra to probe the attenuation in objects without individual detections. The median attenuation at H{alpha} based on the objects with individually detected lines is A(H{alpha}) = 0.9 {+-} 1.0 mag, in good agreement with the attenuation found in local samples of star-forming galaxies. We find that the z = 0.8 galaxies occupy a similar locus of attenuation as a function of magnitude, mass, and star formation rate (SFR) as a comparison sample drawn from the SDSS DR4. Both the results from the individual z = 0.8 galaxies and from the stacked spectra show consistency with the mass-attenuation and SFR-attenuation relations found in the local universe, indicating that these relations are also applicable at intermediate redshift.

Momcheva, Ivelina G. [Astronomy Department, Yale University, New Haven, CT 06511 (United States); Lee, Janice C.; Ouchi, Masami [Carnegie Observatories, Pasadena, CA 91101 (United States); Ly, Chun [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Salim, Samir [Astronomy Department, Indiana University, Bloomington, IN 47405 (United States); Dale, Daniel A. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Finn, Rose [Physics Department, Siena College, Loudonville, NY 12211 (United States); Ono, Yoshiaki, E-mail: ivelina.momcheva@yale.edu [Department of Astronomy, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan)

2013-02-01

76

Localization of HXR and H-alpha impulsive brightenings during the solar flares  

Science.gov (United States)

We investigated localization of hard X-ray radiation (HXR) and H-alpha impulsive brightenings recorded during solar flares. Using high cadence observations we analysed temporal relation-ships and mutually changes of localizations as well as intensity variations of the non-thermal HXR and thermal H-alpha sources. The visual data (so-called spectra-images) were collected with the Multi-Channel Subtractive Double Pass (MSDP) spectrograph and Solar Eclipse Coro-nal Imaging System (SECIS) in Bialkow Observatory (University of Wroclaw, Poland) in H-alpha line with high time resolution (up to 50 ms). The HXR images were reconstructed from Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) observations, using the PIXON method. Ultraviolet observations from Transition Region and Coronal Explorer (TRACE) satellite were used for localizations of anchors of hot coronal loops within the solar flare regions. We found good conformity of HXR non-thermal sources with H-alpha emission, confirming our earlier results showing very fast radiative response of chromosphere in H-alpha range during impulsive phase of solar flares.

Radziszewski, Krzysztof; Rudawy, Pawel

77

H-$\\alpha$ Imaging of Early-type(Sa-Sab) Spiral Galaxies, 1  

CERN Document Server

H-alpha and continuum images are presented for 27 nearby early-type(Sa-Sab) spiral galaxies. Contrary to popular perception, the images reveal copious massive star formation in some of these galaxies. A determination of the H-alpha morphology and a measure of the H-alpha luminosity suggests that early-type spirals can be classified into two broad categories based on the luminosity of largest HII region in the disk. The first category includes galaxies for which the individual HII regions have L(H-alpha) 10^(39) erg/s. All category 2 galaxies show either prominent dust lanes or other morphological peculiarities such as tidal tails which suggests that the anomalously luminous HII regions in category 2 galaxies may have formed as a result of a recent interaction. The observations, which are part of an on-going H-alpha survey, reveal early-type spirals to be a heterogeneous class of galaxies that are evolving in the current epoch. We have also identified some systematic differences between the classifications of...

Hameed, S A; Hameed, Salman; Devereux, Nick

1999-01-01

78

Galaxy And Mass Assembly (GAMA): Bivariate functions of H$\\alpha$ star forming galaxies  

CERN Document Server

We present bivariate luminosity and stellar mass functions of H$\\alpha$ star forming galaxies drawn from the Galaxy And Mass Assembly (GAMA) survey. While optically deep spectroscopic observations of GAMA over a wide sky area enable the detection of a large number of $0.001<{SFR}_{H\\alpha}$ (M$_{\\odot}$ yr$^{-1}$)$<100$ galaxies, the requirement for an H$\\alpha$ detection in targets selected from an $r$-band magnitude limited survey leads to an incompleteness due to missing optically faint star forming galaxies. Using $z<0.1$ bivariate distributions as a reference we model the higher-$z$ distributions, thereby approximating a correction for the missing optically faint star forming galaxies to the local SFR and stellar mass densities. Furthermore, we obtain the $r$-band LFs and stellar mass functions of H$\\alpha$ star forming galaxies from the bivariate LFs. As our sample is selected on the basis of detected H$\\alpha$ emission, a direct tracer of on-going star formation, this sample represents a true ...

Gunawardhana, M L P; Taylor, E N; Bland-Hawthorn, J; Norberg, P; Baldry, I K; Loveday, J; Owers, M S; Wilkins, S M; Colless, M; Brown, M J I; Driver, S P; Alpaslan, M; Brough, S; Cluver, M; Croom, S; Kelvin, L; Lara-López, M A; Liske, J; López-Sánchez, A R; Robotham, A S G

2014-01-01

79

The sensitivity of H alpha profiles to rapid electron beam fluctuations  

Science.gov (United States)

In order to understand the temporal relationship between H alpha and hard X-ray emission predicted by the nonthermal electron thick target model of impulsive-phase energy transport the time-dependent theoretical H alpha profiles were computed for the dynamic model atmospheres of Fisher, Canfield, and McClymont, which simulate the effects of an impulsively initiated power-law beam of electrons. On the basis of the physical analysis it was expected that a very rapid H alpha response to an instantaneous increase in the flux of a nonthermal deka-keV electron beam, as compared to the timescale associated with the propagation of these electrons over characteristic flare coronal loop spatial scales. It was concluded that observational efforts to test the thick target nonthermal electron model through detection of impulsive H alpha brightenings associated with impulsive hard X-ray or microwave bursts should initially focus attention on the H alpha line center. Additional simultaneous blue-wing measurements will have substantial diagnostic potential.

Canfield, Richard C.; Gayley, Kenneth G.

1986-01-01

80

Nebular Attenuation in H\\alpha-selected Star-forming Galaxies at z=0.8 from the NewH\\alpha\\ Survey  

CERN Document Server

We present measurements of the dust attenuation of H\\alpha-selected emission-line galaxies at z=0.8 from the NewH\\alpha\\ narrowband survey. The analysis is based on deep follow-up spectroscopy with Magellan/IMACS, which captures the strong rest-frame optical emission lines from [OII] \\lambda 3727 to [OIII] \\lambda 5007. The spectroscopic sample used in this analysis consists of 341 confirmed H\\alpha\\ emitters. We place constraints on the AGN fraction using diagnostics which can be applied at intermediate redshift. We find that at least 5% of the objects in our spectroscopic sample can be classified as AGN and 2% are composite, i.e. powered by a combination of star-formation and AGN activity. We measure the dust attenuation for individual objects from the ratios of the higher order Balmer lines. The H\\beta\\ and H\\gamma\\ pair of lines is detected with S/N>5 in 55 individual objects and the H\\beta\\ and H\\delta\\ pair is detected in 50 individual objects. We also create stacked spectra to probe the attenuation in ...

Momcheva, Ivelina; Ly, Chun; Salim, Samir; Dale, Daniel A; Ouchi, Masami; Finn, Rose; Ono, Yoshiaki

2012-01-01

 
 
 
 
81

Comparison Of UV And H-alpha SFR Indicators At Intermediate Redshift: Extraction Of H-alpha Fluxes From Near-IR Narrowband Imaging  

Science.gov (United States)

We present preliminary results of an on-going study of the systematics between two commonly used star formation rate (SFR) indicators, UV and H-alpha emission at z 0.8. This poster reports on the measurement of emission-line fluxes from new H-alpha near-IR narrowband imaging in the Extended Groth Strip (EGS), while a companion poster describes the extraction of UV fluxes from ultra-deep GALEX data taken in the same area. Two narrowband filters centered on 1113 and 1184 nm were used to image the EGS in 32 different pointings. The data were taken with the PISCES near-IR imager at the Steward Observatory Bok 2.3m Telescope. Catalogs were produced using Source Extractor and cross-correlated with the DEEP2 redshift dataset to identify true H-alpha emitters in the redshift windows of our filters. The SFR of these galaxies were computed and compared to the SFR computed by GALEX UV photometry. Esselman's research was supported by the NOAO/KPNO Research Experiences for Undergraduates (REU) Program which is funded by the National Science Foundation through Scientific Program Order No. 3 (AST-0243875) of the Cooperative Agreement No. AST-0132798 between the Association of Universities for Research in Astronomy (AURA) and the NSF.

Esselman, Andrew R.; Lee, J.; Salim, S.; Finn, R.; Dale, D.

2007-12-01

82

A Dual Narrowband Survey for H\\alpha\\ Emitters at z=2.2: Demonstration of the Technique and Constraints on the H\\alpha\\ Luminosity Function  

CERN Document Server

We present first results from a narrowband imaging program for intermediate redshift emission-line galaxies using the newly commissioned FourStar infrared camera at the 6.5m Magellan telescope. To enable prompt identification of H\\alpha\\ emitters, a pair of custom 1% filters, which sample low-airglow atmospheric windows at 1.19 \\mu m and 2.10 \\mu m, is used to detect both H\\alpha\\ and [OII]\\lambda 3727 emission from the same redshift volume at z=2.2. Initial observations are taken over a 130 arcmin^2 area in the CANDELS-COSMOS field. The exquisite image quality resulting from the combination of the instrument, telescope, and standard site conditions (~0.55" FWHM) allows the 1.19 \\mu m and 2.10 \\mu m data to probe 3\\sigma\\ emission-line depths down to 1.0e-17 erg/s/cm^2 and 1.2e-17 erg/s/cm^2 respectively, in less than 10 hours of integration time in each narrowband. For H\\alpha\\ at z=0.8 and z=2.2, these fluxes correspond to observed star formation rates of ~0.3 and ~4 Msun/yr respectively. We find 122 source...

Lee, Janice C; Spitler, L; Labbe, I; Salim, S; Persson, S E; Ouchi, M; Dale, D; Monson, A; Murphy, D

2012-01-01

83

A Model for the Scattered Light Contribution and Polarization of the Diffuse $H\\alpha$ Galactic Background  

CERN Document Server

We present Monte Carlo simulations of the Diffuse H$\\alpha$ Galactic Background. Our models comprise direct and multiply scattered H$\\alpha$ radiation from the kpc scaleheight Warm Ionized Medium and midplane H II regions. The scattering is off dust that is assumed to be well mixed with the gas, with an axisymmetric density distribution taken from the literature. The results of our simulations are all-sky H$\\alpha$ images that enable us to separate out the contributions of direct and scattered radiation. We also determine how far the model H$\\alpha$ photons have traveled, i.e., how far we see into the Galaxy at H$\\alpha$. Our models reproduce the overall characteristics of the observed H$\\alpha$ background and predict the scattered H$\\alpha$ intensity at high latitudes is in the range 5% to 20% of the total intensity, in agreement with estimations based on [S II]/H$\\alpha$ and [O III]/H$\\alpha$ line ratio measurements. The polarization arising from dust scattering of H$\\alpha$ from midplane H II regions is pr...

Wood, K; Wood, Kenneth; Reynolds, Ron

1999-01-01

84

An $H_{\\alpha}$ Catalogue of Galaxies in Hickson Compact Groups; 1, The Sample  

CERN Document Server

We present H$_\\alpha$ photometry for a sample of 95 galaxies in Hickson Compact Groups obtained from observations of 31 groups. The Catalogue lists isophotal and adaptive aperture (Kron aperture) flux measurements for about 75% of the accordant galaxies inside the observed HCGs, 22 out of which are upper limits. Non standard data reduction procedures have been used to obtain the continuum subtracted H$_\\alpha$ images for each HCG of the target sample. Flux calibration has also been performed in order to obtain H$_\\alpha$ luminosities for the whole sample. Both the data reduction and calibration procedures are carefully described in this paper. The new data listed in this Catalogue are of great importance in understanding the star formation rate inside HCG galaxies and in giving new insights on its dependence on galaxy interactions.

Severgnini, P; Saracco, P; Chincarini, G L

1999-01-01

85

The Discovery of a Giant H-alpha Filament in NGC 7213  

CERN Document Server

The nearby Seyfert galaxy NGC 7213 has been imaged in H-alpha and HI with the CTIO 1.5 m telescope and with the Australia Telescope Compact Array (ATCA), respectively. Optically NGC 7213 looks undisturbed and relatively featureless but the continuum-subtracted H-alpha image shows a 19 kpc long filament located approximately 18.6 kpc from the nucleus. The H-alpha filament could be neutral gas photo-ionized by the active nucleus, as has been suggested for the Seyfert galaxy NGC 5252, or shock-ionized by a jet interacting with the surrounding HI, as has been suggested for the radio galaxy PKS 2240-41. The HI map reveals NGC 7213 to be a highly disturbed system suggesting a past merging event.

Hameed, S A; Young, L; Devereux, N; Hameed, Salman; Blank, David; Young, Lisa; Devereux, Nick

2000-01-01

86

Far-infrared characteristics of K dwarfs with H-alpha emission  

International Nuclear Information System (INIS)

A sample of K dwarfs with H-alpha emission have counterparts in the IRAS Point Source Catalog. They show two types of infrared spectral behavior, either net decline of emergent flux density from 0.55 micron to at least 12 microns, approximately like normal K dwarfs without H-alpha emission, or net rise in this spectral range, as though with radiation from cool circumstellar matter. Behavior type is not well associated with H-alpha emission strength. Declining spectra are detectable with IRAS to about 30 pc, but rising spectra are not found in this volume so they must be less abundant. Stars with rising spectra may be associated with nebulosity, but one of them, TW Hya, is an exception to the later dependence. 25 references

87

Sizes of flaring kernels in various parts of the H-alpha line profile  

CERN Document Server

In this paper we present new results of spectraphotometrical investigations of the flaring kernels sizes and their intensities measured simultaneously in various parts of the H-alpha line profile. Our investigations were based on the very high temporal resolution spectral-imaging observations of the solar flares collected with Large Coronagraph (LC), Multi-channel Subtractive Double Pass Spectrograph and Solar Eclipse Coronal Imaging System (MSDP-SECIS) at Bialkow Observatory (University of Wroclaw, Poland). We have found that the areas of the investigated individual flaring kernels vary in time and in wavelengths as well as the intensities and areas of the H-alpha flaring kernels decreased systematically when observed in consecutive wavelengths toward the wings of the H-alpha line. Our result could be explained as an effect of the cone-shaped lower parts of the magnetic loops channeling high energy particle beams exciting chromospheric plasma.

Radziszewski, K

2008-01-01

88

A qualitative interpretation of 7 August 1972 impulsive phase flare H alpha line profiles  

Science.gov (United States)

The considered investigation shows that existing models of the formation of the H-alpha line during flares appear to provide clear qualitative evidence that heating of the H-alpha forming regions of the flare chromosphere in the bright H-alpha kernels observed during the impulsive phase of solar flares is not due primarily to heating by Coulomb collisions of a power-law distribution of 10-100 keV electrons with chromospheric material. It appears rather that some shorter-range process, involving possibly conduction or optically thick radiative transfer, is favored. Such a conclusion is clearly relevant to collisionless confinement modelling. However, much work remains to be done before there will be a basis for quantitatively testing the consistency of the considered picture with chromospheric diagnostics.

Canfield, R. C.

1982-01-01

89

A study of the H-alpha line in X1735 - 444  

Science.gov (United States)

Forty six optical spectra containing the H-alpha line of X1735 - 444, which were obtained over three nights in May 1987, were analyzed. Using a convolution method, a radial velocity curve was derived for the whole H-alpha line. Combining the spectroscopic results with an updated photometric ephemeris, the probable sites for H-alpha emission in X1735 - 444 were determined. Results of the analyses suggest that two distinct regions contribute to the observed profile in X-1735 - 444: (1) the peak emission, which is associated with the accretion stream of material passing between the companion and the compact object; and (2) the base emission, which is produced symmetrically in the outer accretion disk.

Smale, Alan P.; Corbet, Robin H. D.

1991-01-01

90

H-alpha Survey of the Local Volume: Isolated Southern Galaxies  

CERN Document Server

We present our H-alpha observations of 11 isolated southern galaxies: SDIG, PGC 51659, E 222-010, E 272-025, E 137-018, IC 4662, Sag DIG, IC 5052, IC 5152, UGCA 438, and E149-003, with distances from 1 to 7 Mpc. We have determined the total H-alpha fluxes from these galaxies. The star formation rates in these galaxies range from 10^{-1} (IC 4662) to 10^{-4}_{\\odot}/yr (SDIG) and the gas depletion time at the observed star formation rates lies within the range from 1/6 to 24 Hubble times H_0^{-1} .

Kaisin, S S; Knyazev, A Yu; Karachentsev, I D

2007-01-01

91

H$\\alpha$ long term monitoring of the Be star $\\beta$ Cep Aa  

CERN Document Server

Recent papers published in the last years contributed to resolve the enigma on the hypothetical Be nature of the hot pulsating star $\\beta$ Cep. This star shows variable emission in the H$\\alpha$ line, typical for Be stars, but its projected rotational velocity is very much lower than the critical limit, contrary to what is expected for a typical Be star. The emission has been attributed to the secondary component of the $\\beta$ Cep spectroscopic binary system. In this paper, using both ours and archived spectra, we attempted to recover the H$\\alpha$ profile of the secondary component and to analyze its behavior with time for a long period. To accomplish this task, we first derived the atmospheric parameters of the primary: T$_{\\rm eff}$ = 24000 $\\pm$ 250 K and $\\log g$ = 3.91 $\\pm$ 0.10, then we used these values to compute its synthetic H$\\alpha$ profile and finally we reconstructed the secondary's profile disentangling the observed one. The secondary's H$\\alpha$ profile shows the typical two peaks emission...

Catanzaro, G

2008-01-01

92

Scattered H-alpha emission from a large translucent cloud G294-24  

CERN Document Server

We study an undocumented large translucent cloud, detected by means of its enhanced radiation on the SHASSA (Southern H-Alpha Sky Survey Atlas) survey. We consider whether its excess surface brightness can be explained by light scattered off the dust grains in the cloud, or whether emission from in situ ionized gas is required. In addition, we aim to determine the temperature of dust, the mass of the cloud, and its possible star formation activity. We compare the observed H-alpha surface brightness of the cloud with predictions of a radiative transfer model. We use the WHAM (Wisconsin H-Alpha Mapper) survey as a source for the Galactic H-alpha interstellar radiation field illuminating the cloud. Visual extinction through the cloud is derived using 2MASS J, H, and K band photometry. We use far-IR ISOSS (ISO Serendipitous Survey), IRAS, and DIRBE data to study the thermal emission of dust. The LAB (The Leiden/Argentine/Bonn Galactic HI Survey) is used to study 21cm HI emission associated with the cloud. Radiati...

Lehtinen, K; Mattila, K

2010-01-01

93

H$\\alpha$ and Free-Free Emission from the WIM  

CERN Document Server

Recent observations have found the ratio of H$\\alpha$ to free-free radio continuum to be surprisingly high in the diffuse ionized ISM (the so-called WIM), corresponding to an electron temperature of only $\\sim$3000~K. Such low temperatures were unexpected in gas that was presumed to be photoionized. We consider a 3-component model for the observed diffuse emission, consisting of a mix of (1) photoionized gas, (2) gas that is recombining and cooling, and (3) cool H~I gas. This model can successfully reproduce the observed intensities of free-free continuum, H$\\alpha$, and collisionally-excited lines such as [\\ion{N}{2}]6583. To reproduce the low observed value of free-free to H$\\alpha$, the PAH abundance in the photoionized regions must be lowered by a factor $\\sim$3, and $\\sim$15\\% of the diffuse H$\\alpha$ must be reflected from dust grains, as suggested by \\citet{Wood+Reynolds_1999}.

Dong, Ruobing

2010-01-01

94

The Properties of H{\\alpha} Emission-Line Galaxies at $z$ = 2.24  

CERN Document Server

Using deep narrow-band $H_2S1$ and $K_{s}$-band imaging data obtained with CFHT/WIRCam, we identify a sample of 56 H$\\alpha$ emission-line galaxies (ELGs) at $z=2.24$ with the 5$\\sigma$ depths of $H_2S1=22.8$ and $K_{s}=24.8$ (AB) over 383 arcmin$^{2}$ area in the ECDFS. A detailed analysis is carried out with existing multi-wavelength data in this field. Three of the 56 H$\\alpha$ ELGs are detected in Chandra 4 Ms X-ray observation and two of them are classified as AGNs. The rest-frame UV and optical morphologies revealed by HST/ACS and WFC3 deep images show that nearly half of the H$\\alpha$ ELGs are either merging systems or with a close companion, indicating that the merging/interacting processes play a key role in regulating star formation at cosmic epoch z=2-3; About 14% are too faint to be resolved in the rest-frame UV morphology due to high dust extinction. We estimate dust extinction form SEDs. We find that dust extinction is generally correlated with H$\\alpha$ luminosity and stellar mass (SM). Our res...

An, F X; Wang, W -H; Huang, J -S; Kong, X; Wang, J -X; Fang, G W; Zhu, F; Gu, Q -S; Wu, H; Hao, L; Xia, X -Y

2014-01-01

95

A long-term study of H(alpha) line variations in FK Comae Berenices  

Science.gov (United States)

We present observations of H(alpha) V/R ratio variations in FK Comae Berencies obtained during several observing seasons from 1981 to 1992. The raw H(alpha) emission profile is always observed to be double peaked due to the stellar-absorption component. During the most years the V/R ratio varies regularly with the period of the photometric light curve. The V/R periodicity is most obvious when time spans no longer than several stellar rotations are considered. We propose that the bulk of the emission component of the H(alpha) line arises in corotating circumstellar material that may be similar to that of a quiescent solar prominence. The lifetime of these structures appears to be on the order of weeks. A weak contribution from a circumstellar disk is evident and chromospheric emission may also be present. The appearance or disappearance of circumstellar structures over periods longer than a few weeks, or the total absence of such structures, blurs the more regular variations in H(alpha) seen over short time scales. Other more stochastic activity, such as flares, also clearly occurs. Phase shifts of the V/R ratio from year to year rule out the hypothesis that mass tranfer in a close binary system is responsible for the V/R variations.

Welty, Alan D.; Ramsey, Lawrence W.; Iyengar, Mrinal; Nations, Harold L.; Buzasi, Derek L.

1993-01-01

96

Using H-alpha as a Tracer of the Emission Region of LS I +61 303  

CERN Document Server

The gamma-ray binary LS I +61 303 is one of the brightest Fermi sources, with orbitally modulated emission across the electromagnetic spectrum. Here we present H-alpha spectra of LS I +61 303 that exhibit a dramatic emission burst shortly before apastron, observed as a redshifted shoulder in the line profile. A correlated burst in radio, X-ray, and GeV emission is observed at the same orbital phase. We interpret the source of the emission as a compact pulsar wind nebula that forms when a tidal mass stream from the Be circumstellar disk interacts with the relativistic pulsar wind. The H-alpha emission offers an important probe of the high energy emission morphology in this system.

McSwain, M Virginia

2011-01-01

97

H-alpha Emission Variability in the gamma-ray Binary LS I +61 303  

CERN Document Server

LS I +61 303 is an exceptionally rare example of a high mass X-ray binary (HMXB) that also exhibits MeV-TeV emission, making it one of only a handful of "gamma-ray binaries". Here we present H-alpha spectra that show strong variability during the 26.5 day orbital period and over decadal time scales. We detect evidence of a spiral density wave in the Be circumstellar disk over part of the orbit. The H-alpha line profile also exhibits a dramatic emission burst shortly before apastron, observed as a redshifted shoulder in the line profile, as the compact source moves almost directly away from the observer. We investigate several possible origins for this red shoulder, including an accretion disk, mass transfer stream, and a compact pulsar wind nebula that forms via a shock between the Be star's wind and the relativistic pulsar wind.

McSwain, M Virginia; Gies, Douglas R; Ray, Paul S

2010-01-01

98

Automated Detection of Filaments and their Disappearance using Full Disc H-alpha Images  

CERN Document Server

A new algorithm is developed that automatically detects filaments on the solar disc in H-alpha images. Preprocessing of H-alpha images include corrections for limb darkening and foreshortening. Further, by applying suitable intensity and size thresholds, filaments are extracted, while other solar features e.g. sunspots and plages are removed. Filaments attributes such as their position on the solar disc, total area, length, and number of fragments are determined. In addition, every filament is also labelled with a unique number. The algorithm is capable of following a particular filament through successive images which allows us to detect the changes and disappearance of the same, and thus provides a real-time warning of eruptive filaments. This aspect would prove to be of particular importance in studies pertaining to space weather. The algorithm will eventually be integrated with an upcoming telescope at Udaipur Solar Observatory for real time monitoring of activated/eruptive filaments.

Joshi, Anand D; Mathew, Shibu K

2009-01-01

99

H-alpha observations of the HH objects in the NGC 7129 field  

Science.gov (United States)

We have studied the HH objects around NGC7129 using H-alpha emission profiles, obtained with the CIGALE scanning Perot-Fabry interferometer. From these, we have derived the position dependence of line profiles, centroid velocities and velocity dispersion. HH 103 and GGD 35 have broad and double-peaked profiles. One extended arc-shaped HH object was also confirmed. The shock velocities and orientation angles are calculated from profiles and compared with observations.

Magakian, T. Yu.; Boulesteix, J.; Marcelin, M.; Le Coarer, E.

1994-11-01

100

Spectropolarimetry of Broad H_alpha Lines and Geometry of the BLR  

CERN Document Server

In a small fraction of Broad Line Radio Galaxies (BLRG) and Seyfert 1 galaxies, the polarization position angle rotates across the broad emission lines, especially at H_alpha. An understanding of this behavior can potentially yield important information on the scattering geometry in the nucleus. We show two examples of this phenomenon, 3C 445, a BLRG, and Mrk 231, a Seyfert 1, and present an equatorial scattering model that explains some of its features in a straightforward way.

Cohen, M H; Cohen, Marshall H.; Martel, Andre' R.

2001-01-01

 
 
 
 
101

On the H$\\alpha$ emission from the $\\beta$ Cephei system  

CERN Document Server

Be stars, which are characterised by intermittent emission in their hydrogen lines, are known to be fast rotators. This fast rotation is a requirement for the formation of a Keplerian disk, which in turn gives rise to the emission. However, the pulsating, magnetic B1IV star $\\beta$ Cephei is a very slow rotator that still shows H$\\alpha$ emission episodes like in other Be stars, contradicting current theories. We investigate the hypothesis that the H$\\alpha$ emission stems from the spectroscopically unresolved companion of $\\beta$ Cep. Spectra of the two unresolved components have been separated in the 6350-6850\\AA range with spectro-astrometric techniques, using 11 longslit spectra obtained with ALFOSC at the Nordic Optical Telescope, La Palma. We find that the H$\\alpha$ emission is not related to the primary in $\\beta$ Cep, but is due to its 3.4 magnitudes fainter companion. This companion has been resolved by speckle techniques, but it remains unresolved by traditional spectroscopy. The emission extends fr...

Schnerr, R S; Oudmaijer, R D; Telting, J H

2006-01-01

102

An H-alpha nuclear spiral structure in the E0 active galaxy Arp102B  

CERN Document Server

We report the discovery of a two-armed mini-spiral structure within the inner kiloparsec of the E0 LINER/Seyfert 1 galaxy Arp102B. The arms are observed in H-alpha emission and located East and West of the nucleus, extending up to about 1 kpc from it. We use narrow-band imaging from the Hubble Space Telescope Advanced Camera for Surveys, in combination with archival VLA radio images at 3.6 and 6 cm to investigate the origin of the nuclear spiral. From the H-alpha luminosity of the spiral, we obtain an ionized gas mass of the order of one million solar masses. One possibility is that the nuclear spiral represents a gas inflow triggered by a recent accretion event which has replenished the accretion disk, giving rise to the double-peaked emission-line profiles characteristic of Arp102B. However, the radio images show a one-sided curved jet which correlates with the eastern spiral arm observed in the H-alpha image. A published milliarcsecond radio image also shows one-sided structure at position angle about 40 d...

Fathi, Kambiz; Storchi-Bergmann, Thaisa; Kharb, Preeti; Robinson, Andrew; Marconi, Alessandro; Maciejewski, Witold; Capetti, Alessandro

2011-01-01

103

H$\\alpha$ Emission From Active Equal-mass, Wide M Dwarf Binaries  

CERN Document Server

We identify a sample of near-equal mass wide binary M dwarf systems from the SLoWPoKES catalog of common proper-motion binaries and obtain follow-up observations of their chromospheric activity as measured by the H$\\alpha$ emission line. We present optical spectra for both components of 48 candidate M dwarf binaries, confirming their mid-M spectral types. Of those 48 coeval pairs, we find eight with H$\\alpha$ emission from both components, three with weak emission in one component and no emission in the other, and 37 with two inactive components. We find that of the eleven pairs with at least one active component, only three follow the net trend of decreasing activity strength $L_{\\rm H\\alpha}/L_{\\rm bol}$ with later spectral type. The difference in quiescent activity strength between the A and B components is larger than what would be expected based on the small differences in color (mass). For five binaries with two active components, we present 47 hours of time-resolved spectroscopy, observed on the ARC 3....

Gunning, Heather C; Davenport, James R A; Dhital, Saurav; Hawley, Suzanne L; West, Andrew A

2014-01-01

104

The SINS Survey: Broad H-alpha Emission in High-Redshift Star-Forming Galaxies  

CERN Document Server

High signal-to-noise, representative spectra of star-forming galaxies at z~2, obtained via stacking of the galaxies observed in the context of the SINS survey, reveal broad (FWHM > 1500 km/s) H-alpha emission. This feature is preferentially found in the more massive and more rapidly star-forming systems, which also tend to be older and larger galaxies. We interpret this feature as evidence of either powerful starburst-driven galactic winds or active supermassive black holes. If galactic winds are responsible for the broad H-alpha emission, the high velocities of this ionized gas indicate that much of it will be expelled from the host galaxy and its dark matter halo. On the other hand, if the broad line regions of active black holes account for the broad H-alpha feature, the corresponding black holes masses are estimated to be an order of magnitude lower than those predicted by local scaling relations, suggesting a delayed assembly of supermassive black holes with respect to their host bulges.

Shapiro, Kristen L; Quataert, Eliot; Schreiber, Natascha M Förster; Davies, Richard; Tacconi, Linda; Armus, Lee; Bouché, Nicolas; Buschkamp, Peter; Cimatti, Andrea; Cresci, Giovanni; Daddi, Emanuele; Eisenhauer, Frank; Erb, Dawn K; Genel, Shy; Hicks, Erin K S; Lilly, Simon J; Lutz, Dieter; Renzini, Alvio; Shapley, Alice; Steidel, Charles C; Sternberg, Amiel

2009-01-01

105

Observational and theoretical constraints for an H$\\alpha$-halo around the Crab Nebula  

CERN Document Server

We searched for a fast moving H$\\alpha$ shell around the Crab nebula. Such a shell could account for this supernova remnant's missing mass, and carry enough kinetic energy to make SN 1054 a normal Type II event. Deep H$\\alpha$ images were obtained with WFI at the 2.2m MPG/ESO telescope and with MOSCA at the 2.56m NOT. The data are compared with theoretical expectations derived from shell models with ballistic gas motion, constant temperature, constant degree of ionisation and a power law for the density profile. We reach a surface brightness limit of $5\\times10^{-8} ergs s^{-1} cm^{-2} sr^{-1}$. A halo is detected, but at a much higher surface brightness than our models of recombination emission and dust scattering predict. Only collisional excitation of Ly$\\beta$ with partial de-excitation to H$\\alpha$ could explain such amplitudes. We show that the halo seen is due to PSF scattering and thus not related to a real shell. We also investigated the feasibility of a spectroscopic detection of high-velocity H$\\al...

Tziamtzis, A; Lundqvist, P; Sollerman, J

2009-01-01

106

The H-alpha Variations of eta Carinae During the 2009.0 Spectroscopic Event  

CERN Document Server

We report on H-alpha spectroscopy of the 2009.0 spectroscopic event of eta Carinae collected via SMARTS observations using the CTIO 1.5 m telescope and echelle spectrograph. Our observations were made almost every night over a two month interval around the predicted minimum of eta Car. We observed a significant fading of the line emission that reached a minimum seven days after the X-ray minimum. About 17 d prior to the H-alpha flux minimum, the H-alpha profile exhibited the emergence of a broad, P Cygni type, absorption component (near a Doppler shift of -500 km/s) and a narrow absorption component (near -144 km/s and probably associated with intervening gas from the Little Homunculus Nebula). All these features were observed during the last event in 2003.5 and are probably related to the close periastron passage of the companion. We argue that these variations are consistent with qualitative expectations about changes in the primary star's stellar wind that result from the wind-wind collision with a massive...

Richardson, N D; Henry, T J; Fernandez-Lajus, E; Okazaki, A T

2010-01-01

107

Impulsive H-alpha diagnostics of electron-beam-heated solar flare model chromospheres  

Science.gov (United States)

Time-dependent H-alpha profiles were computed for the dynamic model atmospheres of Fisher, Canfield, and McClymont (1985) simulating the effects of an intense impulsively initiated power-law beam of electrons incident on the chromosphere. The temporal response of H-alpha arises from three separate physical mechanisms, whose relative importance varies over the line profile. The fastest variations (typically less than 0.1 s for the explosive heating discussed here) arise from energy imbalance; these are apparent on chromospheric heating and cooling time scales and have their greatest amplitude at line center. Slower variations arise from ionization imbalance and are most apparent in the blue wing. The slowest variations arise from hydrodynamic effects and are related to the formation of a chromospheric condensation; these are most apparent in the red wing. These results provide a basis for the design and analysis of observations of H-alpha, in coordination with hard X-rays or microwaves, to test mechanisms of energy transport in solar flares.

Canfield, Richard C.; Gayley, Kenneth G.

1987-01-01

108

Solar Flare Kernel Observations with Integral Field Spectroscopy in H-alpha Line and SDO  

Science.gov (United States)

We developed a field integral spectroscopic instrument using a micro-lens array at the Domeless Solar Telescope, Hida Obervatory. and obtained data of H-alpha flares in X-ray C- and M-class flares taking place on 3 Nov 2011. The field of view was about 10 arc seconds square and time cadence was 12 seconds. The data demonstrate that simultaneous spectroscopic observations over extended solar structures, at a high spatial resolution and temporal cadence, are important to track and understand the physics of transient phenomena happening in impulsive flare kernels. With two-dimensional field spectral data, we made monochromatic images at given wavelengths in the H-alpha line and nearby continuum to co-align with X-ray and UV images from SDO. We also carried out line profile analysis to derive 2-D distribution of atmospheric parameters. Obtained H-alpha spectra clearly show the rapid development of red asymmetry at the flare kernels, giving a large downward Doppler shift of up to 50 km/sec. The accompanied formation of coronal flaring loop structures are consistent with a scenario of downward motion of compressed chromospheric flare kernels due do impulsive heat flow from the corona to the chromosphere and simultaneous evaporation of the chromospheric material into the corona.

Suematsu, Y.

2013-12-01

109

Impulsive H-alpha diagnostics of electron-beam-heated solar flare model chromospheres  

International Nuclear Information System (INIS)

Time-dependent H-alpha profiles were computed for the dynamic model atmospheres of Fisher, Canfield, and McClymont (1985) simulating the effects of an intense impulsively initiated power-law beam of electrons incident on the chromosphere. The temporal response of H-alpha arises from three separate physical mechanisms, whose relative importance varies over the line profile. The fastest variations (typically less than 0.1 s for the explosive heating discussed here) arise from energy imbalance; these are apparent on chromospheric heating and cooling time scales and have their greatest amplitude at line center. Slower variations arise from ionization imbalance and are most apparent in the blue wing. The slowest variations arise from hydrodynamic effects and are related to the formation of a chromospheric condensation; these are most apparent in the red wing. These results provide a basis for the design and analysis of observations of H-alpha, in coordination with hard X-rays or microwaves, to test mechanisms of energy transport in solar flares. 18 references

110

A Spectroscopic Study of the H-alpha Surface Brightness Profiles in the Outer Disks of Galaxies  

CERN Document Server

The surface brightness profile of H-alpha emission in galaxies is generally thought to be confined by a sharp truncation, sometimes speculated to coincide with a star formation threshold. Over the past years, observational evidence for both old and young stellar populations, as well as individual H II regions, has demonstrated that the outer disk is an actively evolving part of a galaxy. To provide constraints on the origin of the aforementioned H-alpha truncation and the relation of H-alpha emission in the outer disk to the underlying stellar population, we measure the shape of the outer H-alpha surface brightness profile of 15 isolated, edge-on late-type disk galaxies using deep, long-slit spectroscopy. Tracing H-alpha emission up to 50% beyond the optical radius, R_25, we find a composite H-alpha surface brightness profile, well described by a broken-exponential law, that drops more steeply in the outer disk, but which is not truncated. The stellar continuum and H-alpha surface brightness both exhibit a br...

Christlein, Daniel; Bland-Hawthorn, Joss

2010-01-01

111

Herschel reveals the obscured star formation in HiZELS H\\alpha\\ emitters at z=1.47  

CERN Document Server

We describe the far-infrared (FIR; rest-frame 8--1000\\mu m) properties of a sample of 443 H\\alpha-selected star-forming galaxies in the COSMOS and UDS fields detected by the HiZELS imaging survey. Sources are identified using narrow-band filters in combination with broad-band photometry to uniformly select H\\alpha\\ (and [OII] if available) emitters in a narrow redshift slice at z = 1.47+/-0.02. We use a stacking approach in Spitzer, Herschel (from PEP and HerMES surveys) and AzTEC images to describe their typical FIR properties. We find that HiZELS galaxies with observed H\\alpha\\ luminosities of ~ 10^{8.1-9.1} Lo have bolometric FIR luminosities of typical LIRGs, L_FIR ~ 10^{11.48+/-0.05} Lo. Combining the H\\alpha\\ and FIR luminosities, we derive median SFR = 32+/-5 Mo/yr and H\\alpha\\ extinctions of A(H\\alpha) = 1.0+/-0.2 mag. Perhaps surprisingly, little difference is seen in typical HiZELS extinction levels compared to local star-forming galaxies. We confirm previous empirical stellar mass (M*) to A(H\\alpha...

Ibar, E; Best, P N; Ivison, R J; Smail, I; Arumugam, V; Berta, S; Béthermin, M; Bock, J; Cava, A; Conley, A; Farrah, D; Floc'h, E Le; Lutz, D; Magdis, G; Magnelli, B; Ikarashi, S; Kohno, K; Marsden, G; Oliver, S J; Page, M J; Pozzi, F; Riguccini, L; Schulz, B; Seymour, N; Smith, A J; Symeonidis, M; Wang, L; Wardlow, J; Zemcov, M

2013-01-01

112

Integral field spectroscopy of H-alpha emission in cooling flow cluster cores: disturbing the molecular gas reservoir  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present optical integral field spectroscopy of the H-alpha-luminous (>1E42 erg/s) central cluster galaxies in the cores of the cooling flows A1664, A1835, A2204 and Zw8193. From the [NII]+H-alpha complex we derive 2-D views of the distribution and kinematics of the emission line gas, and further diagnostics from the [SII] and [OI] lines. The H-alpha emission shows a variety of disturbed morphologies with velocity gradients and splittings of several hundred km/s on scales ...

Wilman, Rj; Edge, Ac; Swinbank, Am

2006-01-01

113

Broad H-alpha wings from the optically thin stellar wind of the hot components in symbiotic binaries  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Aims: To model broad H-alpha wings observed in symbiotic binaries by an optically thin, bipolar stellar wind from their hot components as an alternative to that considering the Raman scattering of Ly-beta photons on atomic hydrogen. Methods: Profile-fitting analysis. Comparison of the observed broad H-alpha wings and their luminosity with those predicted by the model. Results: Synthetic H-alpha profiles fit excellently the observed wings for |RV| > 200 km/s in our sample of ...

Skopal, A.

2006-01-01

114

Hubble Space Telescope H-alpha imaging of star-forming galaxies at z = 1-1.5: evolution in the size and luminosity of giant HII regions  

CERN Document Server

We present HST/WFC3 narrowband imaging of the H-alpha emission in a sample of eight gravitationally-lensed galaxies at z = 1 - 1.5. The magnification caused by the foreground clusters enables us to obtain a median source plane spatial resolution of 360pc, as well as providing magnifications in flux ranging from ~10x to ~50x. This enables us to identify resolved star-forming HII regions at this epoch and therefore study their H-alpha luminosity distributions for comparisons with equivalent samples at z ~ 2 and in the local Universe. We find evolution in the both luminosity and surface brightness of HII regions with redshift. The distribution of clump properties can be quantified with an HII region luminosity function, which can be fit by a power law with an exponential break at some cut-off, and we find that the cut-off evolves with redshift. We therefore conclude that `clumpy' galaxies are seen at high redshift because of the evolution of the cut-off mass; the galaxies themselves follow similar scaling relati...

Livermore, R C; Richard, J; Bower, R G; Ellis, R S; Swinbank, A M; Rigby, J R; Smail, Ian; Ebeling, H; Crain, R A

2012-01-01

115

A synoptic of H-alpha line profile in the T Tauri star SU Aurigae  

Science.gov (United States)

We present a catalog of 106 high spectral resolution observations of the H-alpha line profile in the T Tauri star SU Aurigae, obtained during the period from 1986 October through 1990 November. The spectra were acquired during joint synoptic programs to observe selected T Tauri stars using the Hamilton Echelle Spectrometer of the Lick Observatory and the solar-stellar spectrograph at the McMath telescope of the National Solar Observatory on Kitt Peak. A restricted set of Mg II h and k line profiles was also obtained in a coordinated program involving the International Ultraviolet Explorer (IUE) satellite observatory and the McMath solar-stellar facility. Striking variability is evident on a nightly basis. A key result is that the relative intensity in the blue wing of H-alpha spanning a range of velocities bear -150 km/s is modulated at a period of 2.98 +/- 0.4 days. We identify the 2.98 day period with the rotation period of the star. We also find that the occurrence of the periodic modulation of the mass outflow is episodic and most evident during a 2 week sequence of nightly observations. We find two other intervals where the periodic spectroscopic variability is likely present, although at a lower level of significance at a lower level of significance. The variability is otherwise stochastic in nature. The Mg II resonance lines exhibit clear variability that is most pronounced in the blue wing of the k line. A comparison of the Mg II k line profile with H-alpha profiles obtained nearly simultaneous yields no apparent correlation between the variable features in each line. The profile shapes of the Mg II h and k lines are generally indicative of formation in a wind. An analysis of the principal features that appear in the H-alpha profile set suggests that the line is composed of contributions from an enhanced chromosphere; a relatively slow moving, dense, optically thick component of a stellar wind formed relatively close to the star; and an optically thin, high-velocity, expanding stellar wind located further away from the star. An investigation of possible correlations among the principal features in the series of H-alpha profiles suggests that as the density in the wind increases, the wind may become more unstable to large turbulence. This may lead to a reduction in the wind bulk velocity, thus regulating the mass-loss rate. We also find that the position of the main absorption feature which is always present in the H-alpha profiles is not correlated with its depth, indicating that optical depth and wind velocity are not correlated in the denser portions of the wind.

Giampapa, Mark S.; Basri, Gibor S.; Johns, Christopher M.; Imhoff, Catherine

1993-01-01

116

Models of Diffuse H{\\alpha} in the Interstellar Medium: The Relative Contributions from In Situ Ionisation and Dust Scattering  

CERN Document Server

Using three dimensional Monte Carlo radiation transfer models of photoionisation and dust scattering, we explore different components of the widespread diffuse H$\\alpha$ emission observed in the interstellar medium of the Milky Way and other galaxies. We investigate the relative contributions of H$\\alpha$ from recombination emission in ionised gas and H$\\alpha$ that originates in H{\\sc ii} regions near the Galactic midplane and scatters off high altitude dust in the diffuse interstellar medium. For the radiation transfer simulations we consider two geometries for the interstellar medium: a three dimensional fractal geometry that reproduces the average density structure inferred for hydrogen in the Milky Way, and a density structure from a magneto hydrodynamic simulation of a supernovae driven turbulent interstellar medium. Although some sight lines that are close to H{\\sc ii} regions can be dominated by scattered light, overall we find that less than $\\sim 20\\%$ of the total H$\\alpha$ intensity in our simulat...

Barnes, Joanna E; Hill, Alex S; Haffner, L Matthew

2014-01-01

117

High Resolution H alpha Images of the Binary Low-mass Proplyd LV 1 with the Magellan AO System  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We utilize the new Magellan adaptive optics system (MagAO) to image the binary proplyd LV 1 in the Orion Trapezium at H alpha. This is among the first AO results in visible wavelengths. The H alpha image clearly shows the ionization fronts, the interproplyd shell, and the cometary tails. Our astrometric measurements find no significant relative motion between components over ~18 yr, implying that LV 1 is a low-mass system. We also analyze Large Binocular Telescope AO observa...

Wu, Y. -l; Close, L. M.; Males, J. R.; Follette, K.; Morzinski, K.; Kopon, D.; Rodigas, T. J.; Hinz, P.; Puglisi, A.; Esposito, S.; Pinna, E.; Riccardi, A.; Xompero, M.; Briguglio, R.

2013-01-01

118

H alpha Fabry-Perot Study in the Orion Nebula (M 42): Protoplanetary Disks  

Science.gov (United States)

We summarize the kinematical results obtained from an H alpha Fabry-Perot study of some proplyds in the Orion nebula. These results are presented in detail in de la Fuente et al. (2003 a,b). We obtained heliocentric systemic velocities, mass loss rates, disks life-times and radial velocity profiles, finding that Fabry-Perot interferometry constitutes an effective technique for the detection of proplyds. We also present a brief summary of some astrobiological aspects presented by Throop et al. (2001, 2002). We illustrate our results using the proplyds 168-326, 167-317, 163-317, 158-323, 158-327 and 161-314.

de La Fuente, E.; Rosado, M.; Arias, L.; Ambrocio-Cruz, P.

2003-09-01

119

H$\\alpha$ emission line profiles of selected post-AGB stars  

CERN Document Server

We present H alpha emission line spectra of 7 post-AGB stars. Typically, they have a P-Cygni type profile with a very strong emission component and a relatively narrow absorption component. These lines are formed in the fast post-AGB wind which in most cases has a velocity of around 100 km/s. Hence the emission originates close to the central star and the absorption occurs in the fast wind itself or in the region where the fast wind sweeps up the slow wind. The emission profile has very broad wings. It is still unclear what causes these wings.

De van Steene, G C; Van Hoof, P A M; Steene, Griet C. Van de; Wood, Peter R.

1999-01-01

120

Measurement of Star-Formation Rate from H-alpha in field galaxies at z=1  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report the results of J-band infrared spectroscopy of a sample of 13 z=1 field galaxies drawn from the Canada-France Redshift Survey, targeting galaxies whose redshifts place the rest frame H-alpha line emission from HII regions in between the bright night sky OH lines. As a result we detect emission down to a flux limit of ~10^{-16} ergs cm^{-2} s^{-1} corresponding to a luminosity limit of ~10^{41} ergs at this redshift for a H_0=50 km s^{-1} Mpc,^{-1} q_0=0.5 cosmology...

Glazebrook, Karl; Blake, Chris; Economou, Frossie; Lilly, Simon; Colless, Matthew

1998-01-01

 
 
 
 
121

Pattern Speeds of Bars and Spiral Arms From H-alpha Velocity Fields  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have applied the Tremaine-Weinberg method to 10 late-type barred spiral galaxies using data cubes, in H-alpha emission, from the GHAFAS and FANTOMM Fabry-Perot spectrometers. We have combined the derived bar (and/or spiral) pattern speeds with angular frequency plots to measure the corotation radii for the bars in these galaxies. We base our results on a combination of this method with a morphological analysis designed to estimate the corotation radius to bar-length ratio...

Fathi, Kambiz; Beckman, John; Pin?ol-ferrer, Nuria; Hernandez, Olivier; Martinez-valpuesta, Inma; Carignan, Claude

2009-01-01

122

H-alpha imaging of the Local Volume galaxies I. The NGC 6946 galaxy group  

CERN Document Server

We present new H-alpha imaging of all known dwarf irregular companions to NGC 6946: UGC 11583, KK 251, KK 252, KKR 55, KKR 56, Cepheus 1, KKR 59, and KKR 60. The galaxies span a range of blue absolute magnitudes of [-13.6, -17.6], relative gas content of [0.1, 2.5] M_sun/L_sun, current star formation activity of [0.2, 5.2]10^-2 M_sun yr^-1, and timescale to exhaust the current gas supply of [6, 86] Gyr.

Karachentsev, I D; Tsvetanov, Z I; Ford, H

2005-01-01

123

Near- And Mid-Infrared Imaging Study of Young Stellar Objects around LkH$\\alpha$ 234  

CERN Document Server

We present high-resolution ($0\\farcs2$) near-infrared images of the area surrounding the Herbig Be star LkH$\\alpha$ 234 taken with the Coronagraphic Imager with Adaptive Optics (CIAO) and the adaptive optics on the Subaru Telescope. The near-infrared ($J$, $H$, $K$, $L'$ and $M'$ bands) images reveal circumstellar structures around LkH$\\alpha$ 234 in detail. Eight young stellar object (YSO) candidates (Object B, C, D, E, F, G, NW1, and NW2) were detected at 2$\\arcsec$--11$\\arcsec$ from LkH$\\alpha$ 234. Objects B and C are likely variable stars, which is consistent with a young evolutionary status. Three objects (LkH$\\alpha$ 234, NW1, and NW2) were identified in the 11.8 $\\micron$ (SiC) and 17.65 $\\micron$ images obtained with the Long Wavelength Spectrometer (LWS) on the Keck Telescope. NW1 and NW2 are thought to be embedded young stars. We suggest that NW1 and not LkH$\\alpha$ 234 is the source illuminating the reflection nebula west of LkH$\\alpha$ 234, although Object G may be another candidate. In our image...

Kato, Eri; Perrin, Marshall D; Shibai, Hiroshi; Itoh, Yusuke; Ootsubo, Takafumi

2011-01-01

124

Real-time flare detection in ground-based H$\\alpha$ imaging at Kanzelh\\"ohe Observatory  

CERN Document Server

Kanzelh\\"ohe Observatory (KSO) regularly performs high-cadence full-disk imaging of the solar chromosphere in the H$\\alpha$ and CaIIK spectrallines as well as the solar photosphere in white-light. In the frame of ESA's Space Situational Awareness (SSA) programme, a new system for real-time H$\\alpha$ data provision and automatic flare detection was developed at KSO. The data and events detected are published in near real-time at ESA's SSA Space Weather portal (http://swe.ssa.esa.int/web/guest/kso-federated). In this paper, we describe the H$\\alpha$ instrument, the image recognition algorithms developed, the implementation into the KSO H$\\alpha$ observing system and present the evaluation results of the real-time data provision and flare detection for a period of five months. The H$\\alpha$ data provision worked in $99.96$% of the images, with a mean time lag between image recording and online provision of 4s. Within the given criteria for the automatic image recognition system (at least three H$\\alpha$ images a...

Pötzi, Werner; Riegler, Gernot; Amerstorfer, Ulrike; Pock, Thomas; Temmer, Manuela; Polanec, Wolfgang; Baumgartner, Dietmar J

2014-01-01

125

Shocks and Star Formation in Stephan's Quintet. I. Gemini Spectroscopy of H{\\alpha}-bright knots  

CERN Document Server

We present a Gemini-GMOS spectroscopic study of HST-selected H{\\alpha}-emitting regions in Stephan's Quintet (HCG 92), a nearby compact galaxy group, with the aim of disentangling the processes of shock-induced heating and star formation in its intra-group medium. The $\\approx$40 sources are distributed across the system, but most densely concentrated in the $\\sim$kpc-long shock region. Their spectra neatly divide them into narrow- and and broad-line emitters, and we decompose the latter into three or more emission peaks corresponding to spatial elements discernible in HST imaging. The emission line ratios of the two populations of H{\\alpha}-emitters confirm their nature as H II regions (90% of the sample) or molecular gas heated by a shock-front propagating at $\\lesssim$300 km/s. Their redshift distribution reveals interesting three-dimensional structure with respect to gas-phase baryons, with no H II regions associated with shocked gas, no shocked regions in the intruder galaxy NGC 7318B, and a sharp bounda...

Konstantopoulos, I S; Guillard, P; Trancho, G; Cluver, M E; Bastian, N; Charlton, J C; Fedotov, K; Gallagher, S C; Smith, L J; Struck, C J

2013-01-01

126

H{\\alpha} to FUV ratios in resolved star forming region populations of nearby spiral galaxies  

CERN Document Server

We present a new study of H{\\alpha}/FUV flux ratios of star forming regions within a sample of nearby spiral galaxies. We search for evidence of the existence of a cluster mass dependent truncation in the underlying stellar initial mass function (IMF). We use an automated approach to identification of extended objects based on the SExtractor algorithm to catalogue resolved Hii regions within a set of nearby spiral galaxies. Corrections due to dust attenuation effects are applied to avoid artificially boosted H{\\alpha}/FUV values. We use the BPASS stellar population synthesis code of Eldridge & Stanway (2009) to create a benchmark population of star forming regions to act as a reference for our observations. Based on those models, we identify a zone of parameter space populated by regions that cannot be obtained with a cluster mass dependent truncation in the stellar IMF imposed. We find that the investigated galaxies display small subpopulations of star forming regions falling within our zone of interest,...

Hermanowicz, Maciej T; Eldridge, John J

2013-01-01

127

The star formation rate at redshift one: H-alpha spectroscopy with CIRPASS  

CERN Document Server

We have conducted an H-alpha survey of 38 0.77

Doherty, M; Dalton, G; Lewis, I; Parry, I; Sharp, R; Bunker, Andrew; Dalton, Gavin; Doherty, Michelle; Lewis, Ian; Parry, Ian; Sharp, Robert

2006-01-01

128

Search for H alpha emitters in Galaxy Clusters with Tunable Filters  

CERN Document Server

The studies of the evolution of galaxies in Galaxy Clusters have as a traditional complication the difficulty in establishing cluster membership of those sources detected in the field of view. The determination of spectroscopic redshifts involves long exposure times when it is needed to reach the cluster peripherical regions of/or clusters at moderately large redshifts, while photometric redshifts often present uncertainties too large to offer significant conclusions. The mapping of the cluster of galaxies with narrow band tunable filters makes it possible to reach large redshifts intervals with an accuracy high enough to establish the source membership of those presenting emission/absorption lines easily identifiable, as H alpha. Moreover, the wavelength scan can include other lines as [NII], [OIII] or $H_{\\beta}$ allowing to distinguish those sources with strong stellar formation activity and those with an active galactic nuclei. All this makes it possible to estimate the stellar formation rate of the galax...

Perez-Martinez, Ricardo; Cepa, Jordi; Bongiovanni, Angel; Garcia, Ana Perez; 10.1007/978-3-642-11250-8

2010-01-01

129

Monitoring H-alpha Emission in Be Stars of NGC 659 and NGC 663  

Science.gov (United States)

Over the past nine years we have developed a calibrated H-alpha index based on spectrophotometric data from the Dominion Astrophysical Observatory 1.2-m telescope. We have also manufactured a set of filters to photometrically match our spectrophotometric band-passes. This filter set is employed at the BYU West Mountain Observatory 0.9-m telescope. As one of our first applications of these new filters we examined stars in the young open clusters NGC 659 and NGC 663. We were primarily interested in the Be stars and High Mass X-ray binaries in the field. From July 2013 to January 2104 we observed both fields on 17 nights. We will present our preliminary results from this data set.

Hintz, Eric G.; Joner, Michael D.

2014-06-01

130

He II 4686-A and H-alpha emission lines of Cygnus X-1  

International Nuclear Information System (INIS)

The results of a long-term monitoring program of the He II 4686-A and H-alpha emission lines of the massive X-ray binary Cygnus X-1 are presented. The radial velocities of the residual He II 4686-A emission profiles can be fitted to a smooth sinusoid with little scatter with no significant eccentricity. There is no significant variation in the K amplitude estimated at different epochs which implies a stable origin for the emission. There is a phase lag of 134 deg between the absorption and emission velocity curves. The results support the model of Friend and Castor (1982) in which the primary star almost fills its Roche lobe and has an enhanced mass flow toward the secondary. The He II 4686-A emission strength is strongly modulated with the 5.6-day orbital period. 43 references

131

H-alpha LEGUS: Unveiling the Interplay Between Stars, Star Clusters, and Ionized Gas  

Science.gov (United States)

We propose to obtain narrow-band, H-alpha observations for a significant subset of the star-forming, nearby galaxies recently targeted by the LEGUS treasury program (GO-13364). LEGUS is observing these galaxies in five broad-band filters: NUV, U, B, V, and I. The new H-alpha observations will reveal thousands of previously undetected HII regions, including those ionized by stellar clusters and single massive stars, allow us to measure their luminosities and sizes, and to separate discrete sources from diffuse ionized gas. We will use our narrow-band imaging survey to: (1) establish the connection between star and cluster formation, and determine the prevelance with which isolated massive stars form in different galaxies; (2) determine whether the initial cluster mass function is universal; (3) investigate the size evolution of ionized gas bubbles, and how this depends on cluster age and mass, as well as on local galactic conditions; and (4) place stringent limits on the leakage of ionizing photons from HII regions, and better understand how the interplay between properties of the ionizing source and the morphology of the HII region impacts leakage. The broad goal of this study is to better understand how feedback from massive stars affects the surrounding medium. Ultimately, the interplay between feedback and the ISM on these scales will enable a better understanding of galaxy-scale outflows in the early universe, a process critical to galaxy evolution. This program naturally lends itself to an improvement of the scientific output by involving the general public via an already established Citizen Science program.

Chandar, Rupali

2014-10-01

132

High time resolution observations of H alpha line profiles during the impulsive phase of a solar flare  

International Nuclear Information System (INIS)

H-alpha observations of the impulsive phase of a 1B/M1 solar flare on May 24, 1987, were carried out with high temporal resolution. A line center imaging system and an imaging spectrograph for line profile acquisition have been operated simultaneously with 0.3 s and 2.3 s temporal resolution, respectively. The temporal evolution at line center and in the blue and red wing have been correlated with hard X-ray data from HXRBS. The observed line profiles have been analyzed in terms of dynamic H-alpha line profile calculations by Canfield and Gayley. The combined H-alpha and hard X-ray signatures of two flare kernels are compatible with the theoretical predictions for strong nonthermal electron heating and the formation of a downward moving chromospheric condensation. A third kernel also shows the predicted downward moving chromospheric material, but its temporal evolution is not compatible with electron beam heating. 15 refs

133

Collisionally excited filaments in HST H$\\alpha$ and H$\\beta$ images of HH~1/2  

CERN Document Server

We present new H$\\alpha$ and H$\\beta$ images of the HH~1/2 system, and we find that the H$\\alpha$/H$\\beta$ ratio has high values in ridges along the leading edges of the HH~1 bow shock and of the brighter condensations of HH~2. These ridges have H$\\alpha$/H$\\beta=4\\to 6$, which is consistent with collisional excitation from the $n=1$ to the $n=3$ and 4 levels of hydrogen in a gas of temperatures $T=1.5\\to 10\\times 10^4$~K. This is therefore the first direct proof that the collisional excitation/ionization region of hydrogen right behind Herbig-Haro shock fronts is detected.

Raga, A C; Castellanos-Ramírez, A; Chiang, Hsin-Fang; Bally, J

2014-01-01

134

H-alpha survey of low-mass satellites of the neighbouring galaxies M31 and M81  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Images have been obtained at the 6-m telescope at the Special Astrophysical Observatory (SAO) of the Russian Academy of Sciences in the H-alpha line and in the continuum for 20 dwarf spheroidal satellites of M31: And XI-And XXX, plus the distant Globular cluster Bol 520. Their star formation rates (FR) are estimated using the H-alpha flux and the ultraviolet FUV flux measured with the GALEX space telescope. Most of the dSph satellites of M31 have extremely low star formation...

Kaisin, S. S.; Karachentsev, I. D.

2013-01-01

135

Equivalent Fractions  

Science.gov (United States)

In this NCTM Android app a user identifies equivalent fractions for a given random fraction or one of the player's own. The user creates their representations by dividing and shading either a square or circular region. The fractions are shown as locations on the number line and their equivalency is demonstrated when they are at the same point. The user has the ability to construct a table of equivalent fractions. This app is related to an Illuminations activity and an iOS app that are cataloged separately.

2012-07-31

136

An Atlas of H-alpha and R Images and Radial Profiles of 29 Bright Isolated Spiral Galaxies  

CERN Document Server

Narrow-band H-alpha+[NII] and broadband R images and surface photometry are presented for a sample of 29 bright (M_B < -18) isolated S0-Scd galaxies within a distance of 48 Mpc. These galaxies are among the most isolated nearby spiral galaxies of their Hubble classifications as determined from the Nearby Galaxies Catalog (Tully 1987a).

Koopmann, R A

2005-01-01

137

H-alpha survey of low-mass satellites of the neighbouring galaxies M31 and M81  

CERN Document Server

Images have been obtained at the 6-m telescope at the Special Astrophysical Observatory (SAO) of the Russian Academy of Sciences in the H-alpha line and in the continuum for 20 dwarf spheroidal satellites of M31: And XI-And XXX, plus the distant Globular cluster Bol 520. Their star formation rates (FR) are estimated using the H-alpha flux and the ultraviolet FUV flux measured with the GALEX space telescope. Most of the dSph satellites of M31 have extremely low star formation rates with a characteristic upper limit of SFR~5x10^{-7}. We have made similar estimates of SFR from the H-alpha and FUV fluxes for 13 galaxies with low surface brightness recently discovered in the neighborhood of M81. Eleven of them are physical satellites of M81 with typical SFR< 5x10^{-5}. The median stellar masses of these satellites of M31 and M81 are 0.9 and 1.9 million solar masses, respectively. Our H-alpha observations place a 2-3 times stricter limit on the value of SFR than the data from the GALEX satellite, with a substant...

Kaisin, S S

2013-01-01

138

A Flaring L5 Dwarf The Nature of H\\alpha Emission in Very Low Mass (Sub)Stellar Objects  

CERN Document Server

Time series spectrophotometry of the L5 dwarf 2MASS 01443536-0716142 showed strong H\\alpha emission which declined by nearly 75% in four consecutive exposures. The line was not detected in emission on a spectrum obtained eleven months later. This behavior constrasts with that of 2MASSI J1315309-264951, an L5 dwarf which has shown even stronger H\\alpha emission on four separate occasions. The observational database suggests that L dwarfs can be found in such strong flares only occasionally, with a duty cycle of order 1%. In contrast, the few, continuously-strong H\\alpha emitters, including PC 0025+0447 and 2MASSI J1237392+652615, must either be (1) objects no older than 10-100 Myrs with continuously-active accretion and/or chromospheres, but which apparently formed in isolation from known young stellar clusters and associations, or (2) objects empowered by a different and unknown mechanism for the H\\alpha energy.

Liebert, J; Cruz, K L; Reid, I N; Burgasser, A J; Tinney, C G; Gizis, J E; Liebert, James; Burgasser, Adam; Gizis, John E.

2003-01-01

139

Discovery of H-alpha Emission from the Close Companion Inside the Gap of Transitional Disk HD142527  

CERN Document Server

We utilized the new high-order 585 actuator Magellan Adaptive Optics system (MagAO) to obtain very high-resolution visible light images of HD142527 with MagAO's VisAO science camera. In the median seeing conditions of the 6.5m Magellan telescope (0.5-0.7"), we find MagAO delivers 24-19% Strehl at H-alpha (0.656 microns). We detect a faint companion (HD142527B) embedded in this young transitional disk system at just 86.3+/-1.9 mas (~12 AU) from the star. The companion is detected in both H-alpha and a continuum filter (Delta_mag=6.33+/-0.20 mag at H-alpha and 7.50+/-0.25 mag in the continuum filter). This provides confirmation of the tentative companion discovered by Biller and co-workers with sparse aperture masking at the 8m VLT. The H-alpha emission from the ~0.25 solar mass companion (EW=180 Angstroms) implies a mass accretion rate of ~5.9x10^-10 Msun/yr, and a total accretion luminosity of 1.2% Lsun. Assuming a similar accretion rate, we estimate that a 1 Jupiter mass gas giant could have considerably bet...

Close, L M; Males, J R; Puglisi, A; Xompero, M; Apai, D; Najita, J; Weinberger, A J; Morzinski, K; Rodigas, T J; Hinz, P; Bailey, V; Briguglio, R

2014-01-01

140

Detection of H-alpha emission from z>3.5 submillimetre luminous galaxies with AKARI-FUHYU spectroscopy  

CERN Document Server

We present tentative H-alpha emission line detections of four submillimetre-detected galaxies at z>3.5: the radio galaxies 8C1909+722 and 4C60.07 at signal-to-noise ratios (SNRs) of 3.1 and 2.5, and two submillimetre-selected galaxies (SMGs) near the first of these at SNRs of 10.0 and 2.4, made with the AKARI Space Telescope as part of the FUHYU mission program. These are the highest-redshift H-alpha detections in such galaxies, made possible by AKARI's unique near-infrared spectroscopic capability. The two radio galaxies had known redshifts and surrounding structure, and we have detected broad H-alpha components indicating the presence of dust-shrouded quasars. We conclude that powerful AGNs at z>3.5 occur in peaks of the star-formation density fields, supporting a close connection between stellar mass build-up and black hole mass assembly at this redshift. We also show that 4C60.07 is a binary AGN. The H-alpha detections of the two SMGs are the first redshift determinations for these sources, confirming the...

Sedgwick, Chris; Pearson, Chris; Smail, Ian; Im, Myungshin; Oyabu, Shinki; Takagi, Toshinobu; Matsuhara, Hideo; Wada, Takehiko; Lee, Hyung Mok; Jeong, Woong-Seob; White, Glenn J

2013-01-01

 
 
 
 
141

Dust-Corrected Star Formation Rates of Galaxies. I. Combinations of H-alpha and Infrared Tracers  

CERN Document Server

We combine H-alpha emission-line and infrared continuum measurements of two samples of nearby galaxies to derive dust attenuation-corrected star formation rates (SFRs). We use a simple energy balance based method that has been applied previously to HII regions in the Spitzer Infrared Nearby Galaxies Survey (SINGS), and extend the methodology to integrated measurements of galaxies. We find that our composite H-alpha+IR based SFRs are in excellent agreement with attenuation-corrected SFRs derived from integrated spectrophotometry, over the full range of SFRs (0.01 -- 80 solar mass per year) and attenuations (0 -- 2.5 mag) studied. We find that the combination of H-alpha and total infrared luminosities provides the most robust SFR measurements, but combinations of H-alpha measurements with monochromatic luminosities at 24 micron and 8 micron perform nearly as well. The calibrations differ significantly from those obtained for HII regions (Calzetti et al. 2007), with the difference attributable to a more evolved ...

Kennicutt, Robert C Jr; Calzetti, Daniela; Moustakas, John; Dale, Daniel A; Bendo, George; Engelbracht, Charles W; Johnson, Benjamin D; Lee, Janice C

2009-01-01

142

Development of a high-speed H-alpha camera system for the observation of rapid fluctuations in solar flares  

International Nuclear Information System (INIS)

A solid-state digital camera was developed for obtaining H alpha images of solar flares with 0.1 s time resolution. Beginning in the summer of 1988, this system will be operated in conjunction with SMM's hard X-ray burst spectrometer (HXRBS). Important electron time-of-flight effects that are crucial for determining the flare energy release processes should be detectable with these combined H alpha and hard X-ray observations. Charge-injection device (CID) cameras provide 128 x 128 pixel images simultaneously in the H alpha blue wing, line center, and red wing, or other wavelength of interest. The data recording system employs a microprocessor-controlled, electronic interface between each camera and a digital processor board that encodes the data into a serial bitstream for continuous recording by a standard video cassette recorder. Only a small fraction of the data will be permanently archived through utilization of a direct memory access interface onto a VAX-750 computer. In addition to correlations with hard X-ray data, observations from the high speed H alpha camera will also be correlated and optical and microwave data and data from future MAX 1991 campaigns. Whether the recorded optical flashes are simultaneous with X-ray peaks to within 0.1 s, are delayed by tenths of seconds or are even undetectable, the results will have implications on the validity of both thermal and nonthermal models of hard X-ray production

143

Evidence of Planetesimal infall on to the very young Herbig Be star LkH$_\\alpha$234  

CERN Document Server

We report here the first evidence for planetesimal infall onto the very young Herbig Be star LkH$_\\alpha$234. These results are based on observations acquired over 31 days using spectroscopy of the sodium D lines, the He I 5876\\AA, and hydrogen H$_\\alpha$ lines. We find Redshifted Absorption Components (RAC) with velocities up to 200 km/s and very mild Blueshifted Absorption Components (BEC) up to 100 km/s in the Na I lines. No correlation is observed between the appearance of the Na I RAC & BEC and the H$_\\alpha$ and He I line variability, which suggests that these (Na I RAC & BEC) are formed in a process unrelated to the circumstellar gas accretion. We interpret the Na I RAC as evidence for an infalling evaporating body, greater than 100 km in diameter, which is able to survive at distances between 2.0 to 0.1 AU from the star. The dramatic appearance of the sodium RAC and mild BEC is readily explained by the dynamics of this infalling body making LkH$_\\alpha$234 the youngest (age $\\sim$ 0.1 Myr) sys...

Chakraborty, A; Mahadevan, S

2004-01-01

144

Photometry of HD 50064 - A Be supergiant star with a P Cygni profile at H-alpha  

International Nuclear Information System (INIS)

Photometric and spectroscopic observations of the B1 Ia star HD 50064 (NGC 2301 No. 3) are presented. It is found to be irregularly variable and to possess a P Cygni profile at H-alpha. It is found that the star is probably not an actual cluster member. 19 refs

145

H$\\alpha$ spectroscopy and multi-wavelength imaging of a solar flare caused by filament eruption  

CERN Document Server

We study a sequence of eruptive events including filament eruption, a GOES C4.3 flare and a coronal mass ejection. We aim to identify the possible trigger(s) and precursor(s) of the filament destabilisation; investigate flare kernel characteristics; flare ribbons/kernels formation and evolution; study the interrelation of the filament-eruption/flare/coronal-mass-ejection phenomena as part of the integral active-region magnetic field configuration; determine H alpha line profile evolution during the eruptive phenomena. Multi-instrument observations are analysed including H$\\alpha$ line profiles, speckle images at H$\\alpha$-0.8 \\AA\\ and H$\\alpha$+0.8 \\AA\\ from IBIS at DST/NSO, EUV images and magnetograms from the SDO, coronagraph images from STEREO and the X-ray flux observations from FERMI and GOES. We establish that the filament destabilisation and eruption are the main trigger for the flaring activity. A surge-like event with a circular ribbon in one of the filament footpoints is determined as the possible t...

Huang, Z; Koleva, K; Doyle, J G; Duchlev, P; Dechev, M; Reardon, K

2014-01-01

146

The Tremaine-Weinberg method for pattern speeds using H-alpha emission from ionized gas  

CERN Document Server

The Fabry-Perot interferometer FaNTOmM was used at the 3.6m Canada France Hawaii Telescope and the 1.6m Mont Megantic Telescope to obtain data cubes in H-alpha of 9 nearby spiral galaxies from which maps in integrated intensity, velocity, and velocity dispersion were derived. We then applied the Tremaine-Weinberg method, in which the pattern speed can be deduced from its velocity field, by finding the integrated value of the mean velocity along a slit parallel to the major axis weighted by the intensity and divided by the weighted mean distance of the velocity points from the tangent point measured along the slit. The measured variables can be used either to make separate calculations of the pattern speed and derive a mean, or in a plot of one against the other for all the points on all slits, from which a best fit value can be derived. Linear fits were found for all the galaxies in the sample. For two galaxies a clearly separate inner pattern speed with a higher value, was also identified and measured.

Beckman, John E; Piñol, Núria; Toonen, Silvia; Hernandez, Olivier; Carignan, Claude

2007-01-01

147

A census of H$\\alpha$ emitters in the intergalactic medium of the NGC 2865 system  

CERN Document Server

Tidal debris which are rich in HI gas, formed in interacting and merging systems, are suitable laboratories to study star formation outside galaxies. Recently, several such systems were observed, which contained many young star forming regions outside the galaxies. In previous works, we have studied young star forming regions outside galaxies in different systems with optical and/or gaseous tidal debris, all of them with available archive GALEX/UV images, in order to understand how often they occur and in which type of environments. In this paper we searched for star forming regions around the galaxy NGC2865, a shell galaxy which is circled by a ring of HI, with a total mass of 1.2 x 10$^9$ M$_\\odot$. Using the Multi-Slit Imaging Spectroscopy Technique with the Gemini telescope, we detected all H$\\alpha$ emitting sources in the surroundings of the galaxy NGC2865, down to a flux limit of 10$^{-18}$ erg cm$^{-2}$ s$^{-1}$ \\AA$^{-1}$. Together with Near and Far-Ultraviolet flux information we characterize the st...

Urrutia-Viscarra, F; de Oliveira, C Mendes; Gerhard, O; Torres-Flores, S; Carrasco, E R; de Mello, D

2014-01-01

148

The H$\\alpha$ kinematics of interacting galaxies in 12 compact groups  

CERN Document Server

We present new Fabry-Perot observations for a sample of 42 galaxies located in twelve compact groups of galaxies: HCG 1, HCG 14, HCG 25, HCG 44, HCG 53, HCG 57, HCG 61, HCG 69, HCG 93, VV 304, LGG 455 and Arp 314. From the 42 observed galaxies, a total of 26 objects are spiral galaxies, which range from Sa to Im morphological types. The remaining 16 objects are E, S0 and S0a galaxies. Using these observations, we have derived velocity maps, monochromatic and velocity dispersion maps for 24 galaxies, where 18 are spiral, three are S0a, two are S0 and one is an Im galaxy. From the 24 velocity fields obtained, we could derive rotation curves for 15 galaxies; only two of them exhibit rotation curves without any clear signature of interactions. Based on kinematic information, we have evaluated the evolutionary stage of the different groups of the current sample. We identify groups that range from having no H$\\alpha$ emission to displaying an extremely complex kinematics, where their members display strongly pertur...

Torres-Flores, S; de Oliveira, C Mendes; Plana, H; Balkowski, C; Marcelin, M; Olave-Rojas, D

2014-01-01

149

Measurement of Star-Formation Rate from H-$\\alpha$ in field galaxies at z = 1  

CERN Document Server

We report the results of J-band infrared spectroscopy of a sample of 13 z=1 field galaxies drawn from the Canada-France Redshift Survey, targeting galaxies whose redshifts place the rest frame H-alpha line emission from HII regions in between the bright night sky OH lines. As a result we detect emission down to a flux limit of ~10^{-16} ergs/cm^2/s corresponding to a luminosity limit of these luminosities we derive estimates of the star-formation rates in these galaxies which are independent of previous estimates based upon their rest-frame ultraviolet (2800 Angstroms) luminosity. The mean star-formation rate at z=1, from this sample, is found to be three times as high as the ultraviolet estimates. The dust extinction in these galaxies is inferred to be moderate, with a typical A_V=0.5-1.0 mags, comparable to local field galaxies. This suggests that the bulk of star-formation is not heavily obscured. Star-forming galaxies have the bluest colours and a preponderance of disturbed/interacting morphologies. We al...

Glazebrook, K; Economou, F; Lilly, S; Colless, M; Glazebrook, Karl; Blake, Chris; Economou, Frossie; Lilly, Simon; Colless, Matthew

1998-01-01

150

Pattern Speeds of Bars and Spiral Arms From H-alpha Velocity Fields  

CERN Document Server

We have applied the Tremaine-Weinberg method to 10 late-type barred spiral galaxies using data cubes, in H-alpha emission, from the GHAFAS and FANTOMM Fabry-Perot spectrometers. We have combined the derived bar (and/or spiral) pattern speeds with angular frequency plots to measure the corotation radii for the bars in these galaxies. We base our results on a combination of this method with a morphological analysis designed to estimate the corotation radius to bar-length ratio using two independent techniques on archival near infrared images, and although we are aware of the limitation of the application of the Tremaine-Weinberg method using ionised gas observations, we find consistently excellent agreement between bar and spiral arm parameters derived using different methods. In general, the corotation radius, measured using the Tremaine-Weinberg method, is closely related to the bar length, measured independently from photometry and consistent with previous studies. Our corotation/bar-length ratios and patter...

Fathi, Kambiz; Piñol-Ferrer, Nuria; Hernandez, Olivier; Martinez-Valpuesta, Inma; Carignan, Claude

2009-01-01

151

Estimation of {sup 3}J{sub HN-H{alpha}} and {sup 3}J{sub H}{alpha}{sub -H{beta}} coupling constants from heteronuclear TOCSY spectra  

Energy Technology Data Exchange (ETDEWEB)

{sup 3}J proton-proton coupling constants bear information on the intervening dihedral angles. Methods have been developed to derive this information from NMR spectra of proteins. Using series expansion of the time dependent density matrix, and exploiting the simple topology of amino acid spin-systems, formulae for estimation of {sup 3}J{sub HN-H{alpha}} and {sup 3}J{sub H}{alpha}{sub -H{beta}} from HSQC-TOCSY spectra are derived. The results obtained on a protein entailing both {alpha}-helix and {beta}-sheet secondary structure elements agree very well with J-coupling constants computed from the X-ray structure. The method compares well with existing methods and requires only 2D spectra which would be typically otherwise recorded for structural studies.

Pagano, Katiuscia; Fogolari, Federico, E-mail: ffogolari@mail.dstb.uniud.it; Corazza, Alessandra; Viglino, Paolo; Esposito, Gennaro [Universita di Udine, Dipartimento di Scienze e Tecnologie Biomediche (Italy)

2007-11-15

152

High specific activity N-Acetyl-3{sup H}-{alpha}-Aspartyl- L-Glutamic at micro mole scale; Sintesis de N-Acetil-3{sup H}- {alpha} -Aspartil-Glutamico a escala de Micromoles  

Energy Technology Data Exchange (ETDEWEB)

High specific activity N-Acetyl-3{sup H}- {alpha} -Aspartyl-I-Glutamic acid at micro mole scale in prepared acetylating L- {alpha} -Aspartyl-L-glutamic with 3{sup H}-acetic anhydride in re distilled toluene. The product le purified through cationic and anionic columns. The radiochemical purity as determined by thin-layer chromatography is greater then 99% at the time preparation. (Author) 5 refs.

Suarez, C.

1984-07-01

153

Artificial neural network based calibrations for the prediction of galactic [NII] $\\lambda$ 6584 and H$\\alpha$ line luminosities  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The artificial neural network (ANN) is a well-established mathematical technique for data prediction, based on the identification of correlations and pattern recognition in input training sets. We present the application of ANNs to predict the emission line luminosities of H$\\alpha$ and [NII] $\\lambda$6584 in galaxies. These important spectral diagnostics are used for metallicities, active galactic nuclei (AGN) classification and star formation rates, yet are shifted into th...

Teimoorinia, Hossein; Ellison, Sara L.

2014-01-01

154

High resolution Ly-alpha images obtained with the transition region camera (TRC): A comparison with H-alpha observations  

Science.gov (United States)

Comparing high spatial resolution (approximately 1 sec) images observed in Ly-alpha with the Transition Region Camera (TRC) and in H-alpha at Sacramento Peak and Meudon Observatories, we notice that some structures are well correlated in the two lines (plages), while others are less correlated (chromospheric network, filaments). This is an indication of the inhomogeneous distribution of physical parameters in these structures.

Wiik, J. E.; Foing, B. H.; Martens, P.; Fleck, B.; Schmieder, B.

155

On the Nature of the Unique H$\\alpha$-Emitting T Dwarf 2MASS J12373919+6526148  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We explore and discount the hypothesis that the strong, continual H$\\alpha$-emitting T dwarf 2MASS J12373919+6526148 can be explained as a young, low gravity, very low mass brown dwarf. The source is already known to have a marginally-fainter absolute magnitude than similar T dwarfs with trigonometric parallax measurements, and has a tangential velocity consistent with old disk kinematics. Applying the technique of Burgasser, Burrows & Kirkpatrick on new near infrared spectr...

Liebert, James; Burgasser, Adam J.

2006-01-01

156

Evidence of Environmental Dependencies of Type Ia Supernovae from the Nearby Supernova Factory indicated by Local H{\\alpha}  

Digital Repository Infrastructure Vision for European Research (DRIVER)

(Abridged) We study the host galaxy regions in close proximity to Type Ia supernovae (SNe Ia) to analyze relations between the properties of SN Ia events and environments most similar to where their progenitors formed. We focus on local H\\alpha\\ emission as an indicator of young environments. The Nearby Supernova Factory has obtained flux-calibrated spectral timeseries for SNe Ia using integral field spectroscopy, allowing the simultaneous measurement of the SN and its immed...

Rigault, M.; Copin, Y.; Aldering, G.; Antilogus, P.; Aragon, C.; Bailey, S.; Baltay, C.; Bongard, S.; Buton, C.; Canto, A.; Cellier-holzem, F.; Childress, M.; Chotard, N.; Fakhouri, H. K.; Feindt, U.

2013-01-01

157

H-Alpha and Hard X-Ray Observations of a Two-Ribbon Flare Associated with a Filament Eruption  

CERN Document Server

We perform a multi-wavelength study of a two-ribbon flare on 2002 September 29 and its associated filament eruption, observed simultaneously in the H-alpha line by a ground-based imaging spectrograph and in hard X-rays by RHESSI. The flare ribbons contain several H-alpha bright kernels that show different evolutional behaviors. In particular, we find two kernels that may be the footpoints of a loop. A single hard X-ray source appears to cover these two kernels and to move across the magnetic neutral line. We explain this as a result of the merging of two footpoint sources that show gradually asymmetric emission owing to an asymmetric magnetic topology of the newly reconnected loops. In one of the H-alpha kernels, we detect a continuum enhancement at the visible wavelength. By checking its spatial and temporal relationship with the hard X-ray emission, we ascribe it as being caused by electron beam precipitation. In addition, we derive the line-of-sight velocity of the filament plasma based on the Doppler shif...

Ding, M D; Li, J P; Chen, P F

2003-01-01

158

Bright OB stars in the Galaxy.II. Wind variability in O supergiants as traced by H-alpha  

CERN Document Server

We investigate the line-profile variability (lpv) of H-alpha for a large sample of O-type supergiants. We used the Temporal Variance Spectrum (TVS) analysis, developed by Fullerton et al 1996 and modified by us to take into account the effects of wind emission. By means of a comparative analysis we put a number of constraints on the properties of the variability as a function of stellar and wind parameters. The results of our analysis show that all the stars in the sample show evidence of significant lpv in H-alpha, mostly dominated by processes in the wind. The variations occur between zero and 0.3 v_inf (i.e., below ~1.5 R_star), in good agreement with the results from similar studies. A comparison between observations and line-profile simulations indicates that for stars with intermediate wind densities the H-alpha variability can be explained by simple models, consisting of coherent or broken shells (blobs) uniformly distributed over the wind volume, with an intrinsic scatter in the maximum density contra...

Markova, N; Scuderi, S; Markov, H

2005-01-01

159

A comparison between Pa alpha and H alpha emission The relation between HII region reddening, local gas density and metallicity  

CERN Document Server

We measure reddenings to HII regions in NGC 2903, NGC 1512, M51, NGC 4449 and NGC 6946 from Hubble Space Telescope Pa alpha and H alpha images. Extinctions range from A_V ~ 5 - 0 depending upon the galaxy. For the galaxies with HST images in both lines, NGC 2903, NGC 1512 and M51, the Pa alpha and H alpha emission are almost identical in morphology which implies that little emission from bright HII regions is hidden from view by regions of comparatively high extinction. The scatter in the measured extinctions is only +- 0.5 mag. We compare the reddenings we measure in five galaxies using the Pa alpha to H alpha ratios to those measured previously from the Balmer decrement in the LMC and as a function of radius in M101 and M51. We find that luminosity weighted mean extinctions are correlated with gas surface density and metallicity. The correlation is consistent with the mean extinction depending on dust density where the dust to gas mass ratio scales with the metallicity. This trend is expected if HII regions...

Quillen, A C; Yukita, Mihoko

2001-01-01

160

Disparity between H\\alpha\\ and H\\beta\\ in SN 2008in: inhomogeneous external layers of type IIP supernovae?  

CERN Document Server

We study disparity between H\\alpha\\ and H\\beta\\ in early spectra of the type IIP supernova SN 2008in. The point is that these lines cannot be described simultaneously in a spherically-symmetric model with the smooth density distribution. It is shown that an assumption of a clumpy structure of external layers of the envelope resolves the problem. We obtain estimates of the velocity at the inner border of the inhomogeneous zone (\\approx6100 km s^{-1}), the filing factor of inhomogeneities (\\leq0.5), and the mass of the inhomogeneous layers (~ 0.03 M_{\\odot}). The amplitude of flux fluctuations in the early spectrum of H\\alpha\\ (\\Delta F/F ~ 10^{-2}) imposes a constraint on the size of inhomogeneities (\\leq 200 km s^{-1}). A detection of fluctuations in the early H\\alpha\\ of type IIP supernovae might become an observational test of the inhomogeneous structure of their envelopes. We propose also the indirect test of the clumpy structure of external layers: the study of properties of the initial radiation outburst...

Chugai, N N

2013-01-01

 
 
 
 
161

Evidence of Environmental Dependencies of Type Ia Supernovae from the Nearby Supernova Factory indicated by Local H{\\alpha}  

CERN Document Server

(Abridged) We study the host galaxy regions in close proximity to Type Ia supernovae (SNe Ia) to analyze relations between the properties of SN Ia events and environments most similar to where their progenitors formed. We focus on local H\\alpha\\ emission as an indicator of young environments. The Nearby Supernova Factory has obtained flux-calibrated spectral timeseries for SNe Ia using integral field spectroscopy, allowing the simultaneous measurement of the SN and its immediate vicinity. For 89 SNe Ia we measure H\\alpha\\ emission tracing ongoing star formation within a 1 kpc radius around each SN. This constitutes the first direct study of the local environment for a large sample of SNe Ia also having accurate luminosity, color and stretch measurements. We find that SNe Ia with local H\\alpha\\ emission are redder by 0.036+/-0.017 mag, and that the previously-noted correlation between stretch and host mass is entirely driven by the SNe Ia coming from passive regions. Most importantly, the mean standardized bri...

Rigault, M; Aldering, G; Antilogus, P; Aragon, C; Bailey, S; Baltay, C; Bongard, S; Buton, C; Canto, A; Cellier-Holzem, F; Childress, M; Chotard, N; Fakhouri, H K; Feindt, U; Fleury, M; Gangler, E; Greskovic, P; Guy, J; Kim, A G; Kowalski, M; Lombardo, S; Nordin, J; Nugent, P; Pain, R; Pécontal, E; Pereira, R; Perlmutter, S; Rabinowitz, D; Runge, K; Saunders, C; Scalzo, R; Smadja, G; Tao, C; Thomas, R C; Weaver, B A

2013-01-01

162

Comparison Of UV And H-alpha SFR Indicators At Intermediate Redshift: Extraction Of GALEX UV Fluxes  

Science.gov (United States)

We present preliminary results of an on-going study of the systematics between two commonly used star formation rate (SFR) indicators, UV and H-alpha emission, at z 0.8. This poster reports on the construction of a PSF-based flux catalog, which effectively deals with object blending, using data from the GALEX ultra-deep imaging survey in the Extended Groth Strip. A companion poster presents the work done to extract H-alpha fluxes from new near-IR narrowband imaging observations in the same region. From the rest-frame far-UV flux and the UV slope, we calculate dust-corrected SFRs. For galaxies at z 0.8 having spectroscopic redshifts in DEEP2, our UV SFRs are compared to those obtained in the H-alpha analysis. We hope our study aids in a better understanding of these two indicators, since the systematics of both have not been extensively studied in the intermediate and high redshift regimes. Walton's research was supported by the NOAO/KPNO Research Experiences for Undergraduates (REU) Program which is funded by the National Science Foundation through Scientific Program Order No. 3 (AST-0243875) of the Cooperative Agreement No. AST-0132798 between the Association of Universities for Research in Astronomy (AURA) and the NSF.

Walton, Josiah; Esselman, A.; Salim, S.; Lee, J.

2007-12-01

163

Cosmic Star Formation Activity at z=2.2 Probed by H-alpha Emission Line Galaxies  

CERN Document Server

We present a pilot narrow-band survey of H-alpha emitters at z=2.2 in the Great Observatories Origins Deep Survey North (GOODS-N) field with MOIRCS instrument on the Subaru telescope. The survey reached a 3 sigma limiting magnitude of 23.6 (NB209) which corresponds to a 3 sigma limiting line flux of 2.5 x 10^-17 erg s^-1 cm^-2 over a 56 arcmnin^2 contiguous area (excluding a shallower area). From this survey, we have identified 11 H-alpha emitters and one AGN at z=2.2 on the basis of narrow-band excesses and photometric redshifts. We obtained spectra for seven new objects among them, including one AGN, and an emission line above 3 sigma is detected from all of them. We have estimated star formation rates (SFR) and stellar masses (M_star) for individual galaxies. The average SFR and M_star is 27.8M_solar yr^-1 and 4.0 x 10^10M_solar, respectivly. Their specific star formation rates are inversely correlated with their stellar masses. Fitting to a Schechter function yields the H-alpha luminosity function with lo...

Tadaki, Ken-ichi; Koyama, Yusei; Hayashi, Masao; Tanaka, Ichi; Tokoku, Chihiro

2010-01-01

164

The Second Data Release of the INT Photometric H\\alpha\\ Survey of the Northern Galactic Plane (IPHAS DR2)  

CERN Document Server

The INT/WFC Photometric H-Alpha Survey of the Northern Galactic Plane (IPHAS) is a 1800 square degrees imaging survey covering Galactic latitudes |b| < 5 deg and longitudes l = 30 to 215 deg in the r, i and H\\alpha\\ filters using the Wide Field Camera (WFC) on the 2.5-metre Isaac Newton Telescope (INT) in La Palma. We present the first quality-controlled and globally-calibrated source catalogue derived from the survey, providing single-epoch photometry for 219 million unique sources across 92% of the footprint. The observations were carried out between 2003 and 2012 at a median seeing of 1.1 arcsec (sampled at 0.33 arcsec/pixel) and to a mean 5\\sigma-depth of 21.2 (r), 20.0 (i) and 20.3 (H\\alpha) in the Vega magnitude system. We explain the data reduction and quality control procedures, describe and test the global re-calibration, and detail the construction of the new catalogue. We show that the new calibration is accurate to 0.03 mag (rms) and recommend a series of quality criteria to select the most rel...

Barentsen, Geert; Drew, J E; González-Solares, E A; Greimel, R; Irwin, M J; Miszalski, B; Ruhland, C; Groot, P; Mampaso, A; Sale, S E; Henden, A A; Aungwerojwit, A; Barlow, M J; Carter, P J; Corradi, R L M; Drake, J J; Eislöffel, J; Fabregat, J; Gänsicke, B T; Fusillo, N P Gentile; Greiss, S; Hales, A S; Hodgkin, S; Huckvale, L; Irwin, J; King, R; Knigge, C; Kupfer, T; Lagadec, E; Lennon, D J; Lewis, J R; Mohr-Smith, M; Morris, R A H; Naylor, T; Parker, Q A; Phillipps, S; Pyrzas, S; Raddi, R; Roelofs, G H A; Rodríguez-Gil, P; Sabin, L; Scaringi, S; Steeghs, D; Suso, J; Tata, R; Unruh, Y C; van Roestel, J; Viironen, K; Vink, J S; Walton, N A; Wright, N J; Zijlstra, A A

2014-01-01

165

Nature of H-alpha selected galaxies at z>2. II. Clumpy galaxies and compact star-forming galaxies  

CERN Document Server

We present the morphological properties of 109 H\\alpha-selected galaxies at z>2 in SXDF-UDS-CANDELS field. With high-resolution optical/near-infrared images obtained by Hubble Space Telescope, we identify giant clumps within the H\\alpha emitters (HAEs). We find that at least 41% of our sample show clumpy structures in the underlying disks. The color gradient of clumps is commonly seen in the sense that the clumps near the galactic center tend to be redder than those in the outer regions. The mid-infrared detection in galaxies with red clumps and the spatial distribution of H\\alpha emission suggest that dusty star-formation activity is probably occurring in the nuclear red clumps. A gas supply to a bulge component through the clump migration is one of the most potent physical processes to produce such dusty star-forming clumps and form massive bulges in local early-type galaxies. They would become large quiescent galaxies at later times just by consumption or blowout of remaining gas. Also, while most of the H...

Tadaki, Ken-ichi; Tanaka, Ichi; Hayashi, Masao; Koyama, Yusei; Shimakawa, Rhythm

2013-01-01

166

Resonances and resonance widths  

International Nuclear Information System (INIS)

Two-dimensional betatron resonances are much more important than their simple one-dimensional counterparts and exhibit a strong dependence on the betatron phase advance per cell. A practical definition of ''width'' is expanded upon in order to display these relations in tables. A primarily pedagogical introduction is given to explain the tables, and also to encourage a wider capability for deriving resonance behavior and wider use of ''designer'' resonances

167

Transition of the H-alpha line from absorption to a double-peaked emission in the Be star HD 224544  

Science.gov (United States)

We report the observation of an emission event in H-alpha for the Be star HD 224544. Spectra were obtained at the Observatoire de Haute Provence, France, with a 0.2m telescope and a Lhires III spectrograph.

Desnoux, V.

2014-08-01

168

Sub-THz and H{\\alpha} activity during the preflare and main phases of a GOES class M2 event  

CERN Document Server

Radio and optical observations of the evolution of flare-associated phenomena have shown an initial and rapid burst at 0.4 THz only followed subsequently by a localized chromospheric heating producing an H{\\alpha} brightening with later heating of the whole active region. A major instability occurred several minutes later producing one impulsive burst at microwaves only, associated with an M2.0 GOES X-ray flare that exhibited the main H{\\alpha} brightening at the same site as the first flash. The possible association between long-enduring time profiles at soft X-rays, microwaves, H{\\alpha} and sub-THz wavelengths is discussed. In the decay phase the H{\\alpha} movie shows a disrupting magnetic arch structure ejecting dark, presumably chromospheric, material upwards. The time sequence of events suggests genuine interdependent and possibly non-thermal instabilities triggering phenomena, with concurrent active region plasma heating and material ejection.

Kaufmann, Pierre; de Castro, C Guillermo Giménez; White, Stephen M; Raulin, Jean-Pierre; Correia, Emilia; Fernandes, Luis Olavo; de Souza, Rodney V; Godoy, Rodolfo; Marun, Adolfo; Pereyra, Pablo

2011-01-01

169

SUB-THz AND H{alpha} ACTIVITY DURING THE PREFLARE AND MAIN PHASES OF A GOES CLASS M2 EVENT  

Energy Technology Data Exchange (ETDEWEB)

Radio and optical observations of the evolution of flare-associated phenomena have shown an initial and rapid burst at 0.4 THz only followed subsequently by a localized chromospheric heating producing an H{alpha} brightening with later heating of the whole active region. A major instability occurred several minutes later producing one impulsive burst at microwaves only, associated with an M2.0 GOES X-ray flare that exhibited the main H{alpha} brightening at the same site as the first flash.The possible association between long-enduring time profiles at soft X-rays, microwaves, H{alpha}, and sub-THz wavelengths is discussed. In the decay phase, the H{alpha} movie shows a disrupting magnetic arch structure ejecting dark, presumably chromospheric, material upward. The time sequence of events suggests genuine interdependent and possibly non-thermal instabilities triggering phenomena, with concurrent active region plasma heating and material ejection.

Kaufmann, Pierre; Gimenez de Castro, C. Guillermo; Raulin, Jean-Pierre; Correia, Emilia; Fernandes, Luis Olavo; De Souza, Rodney V. [CRAAM, Escola de Engenharia, Universidade Presbiteriana Mackenzie, Sao Paulo (Brazil); Marcon, Rogerio [IFGW, Universidade Estadual de Campinas (Brazil); White, Stephen M. [AFRL, Space Vehicles Directorate, Albuquerque, NM (United States); Godoy, Rodolfo; Marun, Adolfo; Pereyra, Pablo [Complejo Astronomico El Leoncito, CONICET, San Juan (Argentina)

2011-12-01

170

Time evolution of a miniflare as seen in H-alpha, UV lines, and X-rays  

Science.gov (United States)

A miniflare that occurred in active region Hale 16896 on 1980 June 15 was observed in H-alpha, UV lines, and soft X-rays. These data allow us to analyze the flare emission and derive the energetics and dynamics of the chromospheric plasma involved. Our results indicate that the energy released by the miniflare was about 10(exp 28) ergs, about four orders of magnitude smaller than that of a large flare. However, hard X-rays (5.5-8.0 keV) were observed which indicated a plasma with temperature as high as 27 x 10(exp 6) K. The H-alpha wings, C IV, and X-rays all showed a short-lived and compact (3 sec x 3 sec) brightening in a location near the leading sunspot. At this location, small-scale changes in the magnetic field were observed from about 2 hr before to about 6 hr after the miniflare. Only very small velocities seem to have been associated with most of the event in H-alpha. The data are consistent with short and dense loops at temperatures above 10(exp 7) K which lost a large fraction of their energy via downward conduction through regions at the footpoints. Several secondary events appear to have been triggered by the miniflare along an arch filament which itself was not greatly affected. A number of much less energetic (10(exp 25)-10(exp 26) erg) events preceded and followed the mini-flare. One of these occurred 11 minutes after the mini-flare and displayed a highly Doppler-shifted signature from the foot-point of a C IV arch. This arch delineates the connection that existed between the location of the mini-flare and the location of secondary events triggered by the flare.

Fontenla, J.; Schmieder, B.; Simnett, G. M.; Tandberg-Hanssen, E.

1994-01-01

171

On the Center Shifts of Raman Scattered He II and H$\\alpha$ Wings in Symbiotic Stars  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Using a Monte Carlo technique, we investigate the center shifts that are expected to occur for the broad H$\\alpha$ wings and the He II $\\lambda$ 6545 feature as a function of the neutral hydrogen column density in symbiotic stars.These two features are proposed to be formed via Raman scattering of UV continuum around Ly$\\beta$ and He II $\\lambda$ 1025 emission line by neutral hydrogen. The branching ratio of Raman scattering to Rayleigh scattering for UV radiation around Ly$...

Jung, Yang Chan; Lee, Hee-won

2004-01-01

172

H-Alpha and N II forbidden emission-line profiles of the dwarf starburst galaxy He 2-10  

International Nuclear Information System (INIS)

Line profiles for H-Alpha and the N II 6584 A forbidden line were obtained in the dwarf starburst galaxy, He 2-10. A two-Gaussian profile fit showed that the emission-line region of the galaxy has a broad component of FWHM = 230-280 km/s which is blueshifted by 15 km/s relative to the narrow component. The broad component is interpreted as emission from gas outflowing from W-R (Wolf-Rayet) stars. 14 references

173

SBS 0335-052 E and W: implications of new broad-band and H-alpha photometry  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present the results of deep multicolour CCD imaging with the 6-m telescope of the pair of extremely metal-deficient gas-rich dwarf galaxies SBS 0335-052 E and W. The total magnitudes in U,B,V,R,I bands and the integrated fluxes of H-alpha emission are measured for both galaxies, and their integrated colours are derived. The analysis of their surface brightness (SB) distributions is performed with the use of the azimuthally-averaged SB profiles. The latter were modeled by ...

Pustilnik, S. A.; Pramskij, A. G.; Kniazev, A. Y.

2004-01-01

174

WHAM Observations of $H-\\alpha$, [S II], and [N II] toward the Orion and Perseus Arms Probing the Physical Conditions of the Warm Ionized Medium  

CERN Document Server

A large portion of the Galaxy (l = 123 deg to 164 deg, b = -6 deg to -35 deg), which samples regions of the Local (Orion) spiral arm and the more distant Perseus arm, has been mapped with the Wisconsin H-Alpha Mapper (WHAM) in the H-Alpha, [S II] 6716, and [N II] 6583 lines. Several trends noticed in emission-line investigations of diffuse gas in other galaxies are confirmed in the Milky Way and extended to much fainter emission. We find that the [S II]/H-Alpha and [N II]/H-Alpha ratios increase as absolute H-Alpha intensities decrease. For the more distant Perseus arm emission, the increase in these ratios is a strong function of Galactic latitude and thus, of height above the Galactic plane. The [S II]/[N II] ratio is relatively independent of H-Alpha intensity. Scatter in this ratio appears to be physically significant, and maps of it suggest regions with similar ratios are spatially correlated. The Perseus arm [S II]/[N II] ratio is systematically lower than Local emission by 10%--20%. With [S II]/[N II] ...

Haffner, L M; Tufte, S L

1999-01-01

175

H$_{\\alpha}$ emission fluxes and lithium abundances of low mass stars in the young open cluster IC 4665  

CERN Document Server

As part of a long term effort to understand pre-main sequence Li burning, we have obtained high resolution spectroscopic observations of 14 late type stars (G0--M1) in the young open cluster IC~4665. Most of the stars have \\ha filled-in and \\li absorption, as expected for their young age. From the equivalent widths of \\ha emission excess (obtained using the spectral subtraction technique) and the \\lii feature, we have derived \\ha emission fluxes and photospheric Li abundances. The mean Li abundance of IC~4665 solar-type stars is log N(Li)=3.1; the same as in other young clusters (\\alpha~Per, Pleiades) and T Tauri stars. Our results support the conclusions from previous works that PMS Li depletion is very small for masses \\sim 1 \\msun . Among the IC 4665 late-G and early K-type stars, there is a spread in Li abundances of about one order of magnitude. The Li-poor IC~4665 members have low \\ha excess and vsin{\\it i}\\le10. Hence, the Li-activity-rotation connection which has been clearly established in the Pleiad...

Martín, E L

1996-01-01

176

Fluxes in H\\alpha and Ca II H and K for a sample of Southern stars  

CERN Document Server

The main chromospheric activity indicator is the S index, which is esentially the ratio of the flux in the core of the Ca II H and K lines to the continuum nearby, and is well studied basically for stars from F to K. Another usual chromospheric proxy is the H\\alpha line, which is beleived to be tightly correlated with the Ca II index. In this work we characterize both chromospheric activity indicators, one associated with the H and K Ca II lines and the other with H\\alpha, for the whole range of late type stars, from F to M. We present periodical medium-resolution echelle observations covering the complete visual range, which were taken at the CASLEO Argentinean Observatory. These observations are distributed along 7 years. We use a total of 917 flux-calibrated spectra for 109 stars which range from F6 to M5. We statistically study these two indicators for stars of different activity levels and spectral types. We directly derive the conversion factor which translate the known S index to flux in the Ca II core...

Cincunegui, C; Mauas, P J D; Cincunegui, Carolina; D\\'iaz, Rodrigo F.; Mauas, Pablo J. D.

2007-01-01

177

A search for Ejecta Nebulae around Wolf-Rayet Stars using the SHS H$\\alpha$ survey  

CERN Document Server

Recent large scale Galactic Plane H$\\alpha$ surveys allow a re-examination of the environs of Wolf-Rayet (WR) stars for the presence of a circumstellar nebula. Using the morphologies of WR nebulae known to be composed of stellar ejecta as a guide, we constructed ejecta nebula criteria similar to those of Chu (1991) and searched for likely WR ejecta nebula in the SHS H$\\alpha$ survey. A new Wolf-Rayet ejecta nebula around WR 8 is found and its morphology discussed. The fraction of WR stars with ejecta type nebulae is roughly consistent between the MilkyWay (MW) and LMC at around 5-6%, with the MW sample dominated by nitrogen rich WR central stars (WN type) and the LMC stars having a higher proportion of carbon rich WR central stars (WC type). We compare our results with those of previous surveys, including those of Marston (1997) and Miller & Chu (1993), and find broad consistency. We investigate several trends in the sample: most of the clear examples of ejecta nebulae have WNh central stars; and very few...

Stock, D J

2010-01-01

178

Photometric H alpha and [O II] Luminosity Function of SDF and SXDF Galaxies: Implications for Future Baryon Oscillation Surveys  

CERN Document Server

Efficient selection of emission line galaxies at z > 1 by photometric information in wide field surveys is one of the keys for future spectroscopic surveys to constrain dark energy using the baryon acoustic oscillation (BAO) signature. Here we estimate the H alpha and [O II] line luminosity functions of galaxies at z = 0.5-1.7 using a novel approach where multi-wavelength imaging data is used to jointly estimate both photometric redshifts and star-formation rates. These photometric estimates of line luminosities at high-redshift use the large data sets of the Subaru Deep Field and Subaru XMM-Newton Deep Field (covering \\sim 1 deg^2) and are calibrated with the spectroscopic data of the local Sloan Digital Sky Survey galaxies. The derived luminosity functions (especially H alpha) are in reasonable agreement with the past estimates based on spectroscopic or narrow-band-filter surveys. This dataset is useful for examining the photometric selection of target galaxies for BAO surveys because of the large cosmologi...

Sumiyoshi, Masanao; Oshige, Shunsuke; Glazebrook, Karl; Akiyama, Masayuki; Morokuma, Tomoki; Motohara, Kentaro; Shimasaku, Kazuhiro; Hayashi, Masao; Yoshida, Makiko; Kashikawa, Nobunari; Kodama, Tadayuki

2009-01-01

179

Artificial neural network based calibrations for the prediction of galactic [NII] $\\lambda$ 6584 and H$\\alpha$ line luminosities  

CERN Document Server

The artificial neural network (ANN) is a well-established mathematical technique for data prediction, based on the identification of correlations and pattern recognition in input training sets. We present the application of ANNs to predict the emission line luminosities of H$\\alpha$ and [NII] $\\lambda$6584 in galaxies. These important spectral diagnostics are used for metallicities, active galactic nuclei (AGN) classification and star formation rates, yet are shifted into the infra-red for galaxies above $z \\sim 0.5$, or may not be covered in spectra with limited wavelength coverage. The ANN is trained with a large sample of emission line galaxies selected from the Sloan Digital Sky Survey using various combinations of emission lines and stellar mass. The ANN is tested for galaxies dominated by both star formation and AGN; in both cases the H$\\alpha$ and [NII] $\\lambda$6584 line luminosities can be predicted with a scatter $\\sigma <$ 0.1 dex. We also show that the performance of the ANN does not depend sig...

Teimoorinia, Hossein

2014-01-01

180

Profile variability of the H-alpha and H-beta broad emission lines in NGC5548  

CERN Document Server

Between 1996 and 2002, we have carried out a spectral monitoring program for the Seyfert galaxy NGC 5548. High quality spectra (S/N>50), covering the spectral range (4000-7500)AA were obtained with the 6 m and 1 m telescopes of SAO (Russia) and with the 2.1 m telescope GHO (Mexico). We found that both the flux in the lines and the continuum gradually decreased, reaching minimum values during May-June 2002. The mean, rms, and the averaged over years, observed and difference line profiles of H-alpha and H-beta reveal the double peaked structure at the radial velocity ~+-1000km/s. The relative intensity of these peaks changes with time. During 1996, the red peak was the brightest, while in 1998 - 2002, the blue peak became the brighter one. In 2000-2002 a distinct third peak appeared in the red wing of H-alpha and H-beta line profiles. The radial velocity of this feature decreased between 2000 and 2002 from ~+2500 km/s to ~+2000 km/s. The fluxes of the various parts of the line profiles are well correlated with ...

Shapovalova, A I; Bochkarev, N G; Carrasco, A N B L; Chavushyan, V H; Collin, S; Valdés, J R; Borisov, N; Dumont, A M; Vlasuyk, V V; Chilingarian, I; Fioktistova, I S; Martinez, O M

2004-01-01

 
 
 
 
181

Using MHD simulations to model H-alpha and UV spectral lines for interpretation of IRIS and NST data  

CERN Document Server

We present results of non-LTE modeling of H-alpha 6563 A and Mg II k&h 2796 A and 2803 A lines. This modeling is important for interpretation of coordinated observations from the recently launched NASA's IRIS mission and from the New Solar Telescope at Big Bear Solar Observatory. Among available codes for the non-LTE modeling, the RH code is chosen as the most appropriate for modeling of the line profiles. The most suitable Hydrogen and Magnesium atomic models are selected by performing several tests of the code. The influence of the ionization degree on the line profiles is also studied. Radiative-MHD simulations of the solar atmosphere, obtained with the Bifrost code, are used as input data for calculation of synthetic spectra of the H-alpha and Mg II h&k lines for particular locations evolving with time. The spectral line variations reveal the presence of MHD waves in the simulation results. We construct oscillation power spectra of the line intensity for different wavelength, and compare these wit...

Sadykov, Viacheslav M

2014-01-01

182

Width of nonlinear resonance  

International Nuclear Information System (INIS)

Two approximations are made, one essential and the other not so essential but convenient to keep the analytical treatment manageable: (1) Only one nonlinear resonance is considered at a time so that the treatment is best suited when the tune is close to one resonance only. To improve this approximation, one must go to the next order which involves a canonical transformation of dynamical variables. Analytical treatment of more than one resonance is not possible for general cases. (2) In the formalism using the action-angle variables, the Hamiltonian can have terms which are independent of the angle variables. These terms are called phase-independent terms or shear terms. The tune is then a function of the oscillation amplitudes. In the lowest-order treatment, the (4N)-pole components but not the (4N + 2)-pole components contribute to this dependence. In deriving the resonance width analytically, one ignores these terms in the Hamiltonian for the sake of simplicity. If these are retained, one needs at least three extra parameters and the analytical treatment becomes rather unwieldy

183

A star-bursting proto-cluster in making associated to a radio galaxy at z=2.53 discovered by H_alpha imaging  

CERN Document Server

We report a discovery of a proto-cluster in vigorous assembly and hosting strong star forming activities, associated to a radio galaxy USS 1558-003 at z=2.53, as traced by a wide-field narrow-band H_alpha imaging with MOIRCS on Subaru Telescope. We find 68 H_alpha emitters with dust-uncorrected SFRs down to 8.6 Msun/yr. Their spatial distribution indicates that there are three prominent clumps of H_alpha emitters, one surrounding the radio galaxy and another located at ~1.5 Mpc away to the south-west, and the other located in between the two. These contiguous three systems are very likely to merge together in the near future and may grow to a single more massive cluster at later times. Whilst most H_alpha emitters reside in the "blue cloud" on the color--magnitude diagram, some emitters have very red colors with J-Ks>1.38(AB). Interestingly, such red H_alpha emitters are located towards the faint end of the red sequence, and they tend to be located in the high density clumps. We do not see any statistically s...

Hayashi, Masao; Tadaki, Ken-ichi; Koyama, Yusei; Tanaka, Ichi

2012-01-01

184

Star Formation Rates and Stellar Masses of H-alpha Selected Star-Forming Galaxies at z=0.84: A Quantification of the Downsizing  

CERN Document Server

In this work we analyze the physical properties of a sample of 153 star forming galaxies at z~0.84, selected by their H-alpha flux with a NB filter. B-band luminosities of the objects are higher than those of local star forming galaxies. Most of the galaxies are located in the blue cloud, though some objects are detected in the green valley and in the red sequence. After the extinction correction is applied virtually all these red galaxies move to the blue sequence, unveiling their dusty nature. A check on the extinction law reveals that the typical extinction law for local starbursts is well suited for our sample but with E(B-V)_stars=0.55 E(B-V)_gas. We compare star formation rates (SFR) measured with different tracers (H-alpha, UV and IR) finding that they agree within a factor of three after extinction correction. We find a correlation between the ratios SFR_FUV/SFR_H-alpha, SFR_IR/SFR_H-alpha and the EW(H-alpha) (i.e. weighted age) which accounts for part of the scatter. We obtain stellar mass estimation...

Villar, V; Pérez-González, P-G; Barro, G; Zamorano, J; Noeske, K G; Koo, D C

2011-01-01

185

Observational studies of the symbiotic stars. III High-dispersion IUE and H-alpha observations of EG Andromedae  

Science.gov (United States)

High-dispersion IUE and optical spectra are presented for the symbiotic star EG Andromedae (HD 4174). Remarkable emission-line strength and profile variations are confirmed for the S IV, O IV, C IV, and He II ultraviolet lines as well as H-alpha. Accurate cross-correlation absorption-line velocities determined from Ti I, Ca I, and Fe I features convincingly demonstrate that EG And is a single-lined spectroscopic binary. The velocity curve suggests that the photometric ephemeris reported by Smith in 1980 should be revised by a redefinition of zero phase by about 0.08 of a period. The primary of the system may be similar to the central star of a planetary nebula embedded in a dense nebula with a mild stellar wind. The behavior of the emission lines is interpreted to indicate that the primary and its surrounding nebula suffer a partial eclipse by the cool giant secondary.

Oliversen, N. A.; Anderson, C. M.; Slovak, M. H.; Stencel, R. E.

1985-01-01

186

Mass loss in HR 1040 /A0 Ia/ - Analysis of Mg II lambda 2802 and H-alpha  

Science.gov (United States)

It is pointed out that International Ultraviolet Explorer (IUE) data for several early A type supergiants are now available to complement the ground-based spectroscopic data available for these bright stars. An examination of the resonance doublet of Mg II in the A type supergiants reveals that HR 1040 (HD 21389) is the only star in the observational literature in which a violet-shifted, deep absorption line is present without complete saturation. From an unsaturated profile, a good estimate of Mg(+) density can be found by means of accurate radiative transfer calculations. A relation can then be derived between mass loss rate and ionization balance. When certain velocity-related quantities can be estimated from a Mg II line profile, the H-alpha provides an estimate of the mass loss rate. The present investigation is concerned with an application of these diagnostics to HR 1040.

Kunasz, P. B.; Morrison, N. D.; Spressart, B.

1983-01-01

187

The W-boson width  

Science.gov (United States)

The analytic formulae for the partial decay width W +?f_1 bar f_2 are presented including the 1-loop electroweak and QCD corrections for arbitrary masses of the fermions. Numerical results are discussed for the physically interesting casesW^ + to tbar b and for the decay into a heavy lepton l + and a neutrino of a fourth fermion generation. Also the results for the total W width and the partial width into light fermion pairs are listed.

Denner, Ansgar; Sack, Thomas

1990-12-01

188

Multiwavelength optical observations of chromospherically active binary systems; 1, Simultaneous $H{\\alpha}, NaI D_{1}, D_{2}$, and $HeI D_{3}$ observations  

CERN Document Server

This is the first paper of a series aimed at studying the chromosphere of active binary systems using the information provided for several optical spectroscopic features. Simultaneous H{alpha}, Na I D{1}, D{2}, and He I D{3} spectroscopic observations are reported here for 18 systems. The chromospheric contribution in these lines have been determined using the spectral subtraction technique. Very broad wings have been found in the subtracted H{alpha} profile of some of the more active stars. These profiles are well matched using a two-components Gaussian fit (narrow and broad) and the broad component could be interpreted as arising from microflaring. Prominence-like extended material have been detected in a near-eclipse H{alpha} observation of the system AR Lac. The excess emission found in the Na I D{1} and D{2} lines by application of the spectral subtraction technique and the behaviour of the H{alpha} line in the corresponding simultaneous observations indicate that the filling-in of the core of these line...

Montes, D; De Castro, E; Sanz-Forcada, J

1997-01-01

189

Obscured star formation at z = 0.84 with HiZELS: the relationship between star formation rate and H-alpha or ultra-violet dust extinction  

CERN Document Server

[Abridged] We compare H-alpha, ultraviolet (UV) and infrared (IR) indicators of star formation rate (SFR) for a sample of z = 0.84 galaxies from the High-z Emission Line Survey (HiZELS). Using multi-wavelength diagnostics, we estimate that 5 - 11 per cent of H-alpha emitters at this redshift are active galactic nuclei. We detect 35 per cent of the H-alpha emitters individually at 24 microns, and stack the star-forming emitters on deep 24-micron images in order to calculate the typical SFRs of our galaxies. These are compared to the observed H-alpha line fluxes in order to estimate the extinction at z = 0.84, and we find a significant increase in dust extinction for galaxies with higher SFRs. We demonstrate that the local relationship between SFR and extinction is suitable for our sample, and attribute the overall increase in dust extinction for z = 0.84 galaxies to an increase in the average SFR, rather than to a change in dust properties. We calculate the UV extinction, and find a similar dependence on SFR, ...

Garn, Timothy; Best, Philip N; Geach, James E; Smail, Ian; Cirasuolo, Michele; Dalton, Gavin B; Dunlop, James S; McLure, Ross J; Farrah, Duncan

2009-01-01

190

The Wyoming Survey for H-alpha. III. A Multi-wavelength Look at Attenuation by Dust in Galaxies out to z~0.4  

CERN Document Server

We report results from the Wyoming Survey for H-alpha (WySH), a comprehensive four-square degree survey to probe the evolution of star-forming galaxies over the latter half of the age of the Universe. We have supplemented the H-alpha data from WySH with infrared data from the Spitzer Wide-area Infrared Extragalactic (SWIRE) Survey and ultraviolet data from the Galaxy Evolution Explorer (GALEX) Deep Imaging Survey. This dataset provides a multi-wavelength look at the evolution of the attenuation by dust, and here we compare a traditional measure of dust attenuation (L(TIR)/L(FUV)) to a diagnostic based on a recently-developed robust star formation rate (SFR) indicator, [H-alpha_obs+24-micron]/H-alpha_obs. With such data over multiple epochs, the evolution in the attenuation by dust with redshift can be assessed. We present results from the ELAIS-N1 and Lockman Hole regions at z~0.16, 0.24, 0.32 and 0.40. While the ensemble averages of both diagnostics are relatively constant from epoch to epoch, each epoch ind...

Moore, Carolynn A; Barlow, Rebecca J; Cohen, Seth A; Cook, David O; Johnson, L C; Kattner, ShiAnne M; Lee, Janice C; Staudaher, Shawn M

2010-01-01

191

A Spectacular H$\\alpha$ Complex in Virgo: Evidence for a Collision Between M86 and NGC 4438 and Implications for Collisional ISM Heating of Ellipticals  

CERN Document Server

Deep wide-field H$\\alpha$+[NII] imaging around the Virgo cluster giant elliptical galaxy M86 reveals a highly complex and disturbed ISM/ICM. The most striking feature is a set of H$\\alpha$ filaments which clearly connect M86 with the nearby disturbed spiral NGC 4438 (23$'$=120 kpc projected away), providing strong evidence for a previously unrecognized collision between them. Spectroscopy of selected regions show a fairly smooth velocity gradient between M86 and NGC 4438, consistent with the collision scenario. Such a collision would impart significant energy into the ISM of M86, probably heating the gas and acting to prevent the gas from cooling to form stars. We propose that cool gas stripped from NGC 4438 during the collision and deposited in its wake is heated by shocks, ram pressure drag, or thermal conduction, producing most of the H$\\alpha$ filaments. Some H$\\alpha$ filaments are associated with the well-known ridge of bright X-ray emission to the NW of the nucleus, suggesting that the collision is res...

Kenney, J D P; Crowl, H H; Feldmeier, J; Jacoby, G H

2008-01-01

192

Equivalent transfiguration of networks  

Energy Technology Data Exchange (ETDEWEB)

The concept of the equivalence of electrical networks is presented. The equivalence of networks with regard to their trees or cotrees is defined and discussed. The mathematical approach to the equivalence problem is formulated using the theory of the generalized inverse. The conditions of equivalence are derived and the method of determining the set of equivalent networks is given. Examples illustrating the equivalent transfiguration of a network are shown.

Klos, A.; Borkowska, B.

1979-04-01

193

The Stellar Parameters and Evolutionary State of the Primary in the d'-Symbiotic System StH\\alpha190  

CERN Document Server

We report on a high-resolution, spectroscopic stellar parameter and abundance analysis of a d' symbiotic star: the yellow component of StH\\alpha190. This star has recently been discovered, and confirmed here, to be a rapidly rotating (vsini=100 km/s) subgiant, or giant, that exhibits radial-velocity variations of probably at least 40 km/s, indicating the presence of a companion (a white dwarf star). It is found that the cool stellar component has Teff=5300K and log g=3.0. The iron and calcium abundances are close to solar, however, barium is overabundant, relative to Fe and Ca, by about +0.5 dex. The barium enhancement reflects mass-transfer of s-process enriched material when the current white dwarf was an asymptotic giant branch (AGB) star. The past and future evolution of this binary system depends critically on its current orbital period, which is not yet known. Concerted and frequent radial-velocity measurements are needed to provide crucial physical constraints to this d' symbiotic system.

Smith, V V; Cunha, K; Smith, Verne V.; Pereira, Claudio B.; Cunha, Katia

2001-01-01

194

HST/ACS H-alpha Imaging of the Carina Nebula: Outflow Activity Traced by Irradiated Herbig-Haro Jets  

CERN Document Server

We report the discovery of new Herbig-Haro (HH) jets in the Carina Nebula, and we discuss the protostellar outflow activity of a young OB association. These are the first results of an HST/ACS H-alpha imaging survey of Carina. Adding to the one previously known example (HH666), we detect 21 new HH jets, plus 17 new candidate jets, ranging in length from 0.005 to 3 pc. We derive jet mass-loss rates ranging from 8e-9 to 1e-6 Msun/yr, but a comparison to the distribution of jet mass-loss rates in Orion suggests that we may be missing a large fraction of the jets below 1e-8 Msun/yr. A key qualitative result is that even some of the smallest dark globules with sizes of 0.01pc are active sites of ongoing star formation because we see HH jets emerging from them, and that these offer potential analogs to the cradle of our Solar System because of their proximity to dozens of imminent supernovae that will enrich them with radioactive nuclides like 60Fe. HST images reveal proplyd structures in the core of the Tr14 clust...

Smith, Nathan; Walborn, Nolan R

2010-01-01

195

Synthesis of H-alpha absorption in old stellar systems: Formation of the cluster red sequence by "Downsizing"  

CERN Document Server

We compute population synthesis models for the variation of H-alpha absorption indices (HaA and HaF), as a function of age and metallicity in old stellar systems. The models are based on the STELIB spectral library, and defined at resolution of 3 Angstrom FWHM. The indices are found to be highly sensitive to age variation, with only moderate response to metallicity. For galaxies uncontaminated by nebular emission, our HaA index is more powerful in breaking the age/metallicity degeneracy than H-beta or H-gamma_F. Using a sample of red cluster galaxies carefully selected to exclude objects with emission, we find a steep decline of HaA with velocity dispersion (slope -0.75 +/- 0.07 Angstrom/dex). The slope can be translated to constraints on age and metallicity scaling relations, incorporating measurement and model errors. If the HaA-sigma slope is due only to age, we obtain Age proportional to sigma^{0.95 +/- 0.12}. Because HaA depends quite weakly on [Fe/H], a metallicity interpretation would require Fe/H prop...

Smith, R J

2005-01-01

196

Resolved H-alpha Maps of Star-forming Galaxies in Distant Clusters: Towards a Physical Model of Satellite Galaxy Quenching  

Science.gov (United States)

It has been known for decades that satellite galaxies are always less star forming than central galaxies of similar mass. New, sophisticated modeling of satellites at both z = 0 and z = 1 has shown that the quenching of star formation in satellites must be a rapid process, occurring on a timescale of only ~ 0.5 Gyr. Despite good constraints on the quenching timescale, the detailed physics of how satellites actually shut down their star formation is still heavily debated. What is now desperately needed are high-quality observations of satellite galaxies directly in the process of quenching. In particular, resolved H-alpha maps would be extremely informative because H-alpha is a near instantaneous measure of the current SFR, showing where and when star formation is quenched. Thus far, these maps are only available locally for satellite galaxies in the Virgo cluster; however, they are fascinating. In H-alpha emission Virgo satellites are completely different than central galaxies, with >50% having highly truncated and disturbed disks, suggesting an outside-in truncation of star formation. We propose to obtain the first resolved H-alpha maps of star-forming satellite galaxies in massive clusters at z ~ 1. This high-redshift data will be critical to determine how satellite quenching evolves over time, as satellites have much higher gas fractions and star formation rates at z ~ 1. We will compare the H-alpha luminosities, sizes and profiles of the satellites to central galaxies in the 3D-HST survey and quantify how quenching affects star-forming disks at z ~ 1. This information will be key input for the next generation of physical models of satellite quenching.

Muzzin, Adam

2014-10-01

197

The width of a proof  

Directory of Open Access Journals (Sweden)

Full Text Available This paper’s aim is to discuss the concept of width of a proof put forward by Timothy Gowers. It explains what this concept means and attempts to show how it relates to other concepts discussed in the existing literature on proof and proving. It also explores how the concept of width of a proof might be used productively in the mathematics curriculum and how it might fit with the various perspectives on learning to prove.

Gila Hanna

2014-09-01

198

THE PHOTOMETRIC AND KINEMATIC STRUCTURE OF FACE-ON DISK GALAXIES. III. KINEMATIC INCLINATIONS FROM H{alpha} VELOCITY FIELDS  

Energy Technology Data Exchange (ETDEWEB)

Using the integral field unit DensePak on the WIYN 3.5 m telescope we have obtained H{alpha} velocity fields of 39 nearly face-on disks at echelle resolutions. High-quality, uniform kinematic data and a new modeling technique enabled us to derive accurate and precise kinematic inclinations with mean i{sub kin} = 23 Degree-Sign for 90% of these galaxies. Modeling the kinematic data as single, inclined disks in circular rotation improves upon the traditional tilted-ring method. We measure kinematic inclinations with a precision in sin i of 25% at 20 Degree-Sign and 6% at 30 Degree-Sign . Kinematic inclinations are consistent with photometric and inverse Tully-Fisher inclinations when the sample is culled of galaxies with kinematic asymmetries, for which we give two specific prescriptions. Kinematic inclinations can therefore be used in statistical ''face-on'' Tully-Fisher studies. A weighted combination of multiple, independent inclination measurements yield the most precise and accurate inclination. Combining inverse Tully-Fisher inclinations with kinematic inclinations yields joint probability inclinations with a precision in sin i of 10% at 15 Degree-Sign and 5% at 30 Degree-Sign . This level of precision makes accurate mass decompositions of galaxies possible even at low inclination. We find scaling relations between rotation speed and disk-scale length identical to results from more inclined samples. We also observe the trend of more steeply rising rotation curves with increased rotation speed and light concentration. This trend appears to be uncorrelated with disk surface brightness.

Andersen, David R. [NRC Herzberg Institute of Astrophysics, 5071 W Saanich Road, Victoria, BC V9E 2E7 (Canada); Bershady, Matthew A., E-mail: david.andersen@nrc-cnrc.gc.ca, E-mail: mab@astro.wisc.edu [Department of Astronomy, University of Wisconsin, 475 N Charter Street, Madison, WI 53706 (United States)

2013-05-01

199

SHORT TIMESCALE VARIATIONS OF THE H{alpha} DOUBLE-PEAKED PROFILE OF THE NUCLEUS OF NGC 1097  

Energy Technology Data Exchange (ETDEWEB)

The broad (FWHM {approx} 10,000 km s{sup -1}) double-peaked H{alpha} profile from the LINER/Seyfert 1 nucleus of NGC 1097 was discovered in 1991 and monitored for the following 11 years. The profile showed variations attributed to the rotation of gas in a non-axisymmetric Keplerian accretion disk, ionized by a varying radiatively inefficient accretion flow (RIAF) located in the inner parts of the disk. We present and model 11 new spectroscopic observations of the double-peaked profile taken between 2010 March and 2011 March. This series of observations was motivated by the finding that in 2010 March the flux in the double-peaked line was again strong, indeed, in 2010 December, even stronger than in the observations of a decade ago. We also discovered shorter timescale variations than in the previous observations: (1) the first, of {approx}7 days, is interpreted as due to 'reverberation' of the variation of the ionizing source luminosity, and the timescale of 7 days as the light crossing time between the source and the accretion disk; this new timescale and its interpretation provides a distance between the emitting gas and the supermassive black hole and as such introduces a new constraint on its mass; (2) the second, of Almost-Equal-To 5 months, was attributed to the rotation of a spiral arm in the disk, which was found to occur on the dynamical timescale. We use two accretion disk models to fit theoretical profiles to the new data, both having non-axisymmetric emissivities produced by the presence of an one-armed spiral. Our modeling constrains the rotation period for the spiral to be Almost-Equal-To 18 months. This work supports our previous conclusion that the broad double-peaked Balmer emission lines in NGC 1097-and probably also in other low-luminosity active nuclei-originate from an accretion disk ionized by a central RIAF.

Schimoia, Jaderson S.; Storchi-Bergmann, Thaisa [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Campus do Vale, Porto Alegre, RS (Brazil); Nemmen, Rodrigo S. [NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, Maryland (United States); Winge, Claudia [Gemini South Observatory, c/o AURA Inc., Casilla 603, La Serena (Chile); Eracleous, Michael, E-mail: silva.schimoia@ufrgs.br [Department of Astronomy and Astrophysics, the Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States)

2012-04-01

200

Average radiation widths and the giant dipole resonance width  

International Nuclear Information System (INIS)

The average E1 radiation width can be calculated in terms of the energy E and width ? of the Giant Dipole Resonance (GDR). While various models can predict E quite reliably, the theoretical situation regarding E is much less satisfactory. The authors propose a simple phenomenological model which is able to provide ? values in good agreement with experimental data for spherical or deformed intermediate and heavy nuclei. In particular, this model can account for shell effects in ?, and can be used in conjunction with the droplet model. The ? values derived in such a way are used to compute average E1 radiation widths which are quite close to the experimental values. The method proposed for the calculation of ? also appears to be well suited when the GDR characteristics of extended sets of nuclei are required, as is namely the case in nuclear astrophysics. (Auth.)

 
 
 
 
201

CAWSES Related Projects in Japan : Grant-in-Aid for Creative Scientific Research ügBasic Study of Space Weather Predictionüh and CHAIN (Continuous H Alpha Imaging Network)  

Science.gov (United States)

The Grant-in-Aid for Creative Scientific Research of the Ministry of Education Science Sports Technology and Culture of Japan The Basic Study of Space Weather Prediction PI K Shibata Kyoto Univ has started in 2005 as 5 years projects with total budget 446Myen The purpose of this project is to develop a physical model of solar-terrestrial phenomena and space storms as a basis of space weather prediction by resolving fundamental physics of key phenomena from solar flares and coronal mass ejections to magnetospheric storms under international cooperation program CAWSES Climate and Weather of the Sun-Earth System Continuous H Alpha Imaging Network CHAIN Project led by H Kurokawa is a key project in this space weather study enabling continuous H alpha full Sun observations by connecting many solar telescopes in many countries through internet which provides the basis of the study of space weather prediction

Shibata, K.; Kurokawa, H.

202

H{alpha} ACTIVITY OF OLD M DWARFS: STELLAR CYCLES AND MEAN ACTIVITY LEVELS FOR 93 LOW-MASS STARS IN THE SOLAR NEIGHBORHOOD  

Energy Technology Data Exchange (ETDEWEB)

Through the McDonald Observatory M Dwarf Planet Search, we have acquired nearly 3000 high-resolution spectra of 93 late-type (K5-M5) stars over more than a decade using the High Resolution Spectrograph on the Hobby-Eberly Telescope. This sample provides a unique opportunity to investigate the occurrence of long-term stellar activity cycles for low-mass stars. In this paper, we examine the stellar activity of our targets as reflected in the H{alpha} feature. We have identified periodic signals for six stars, with periods ranging from days to more than 10 years, and find long-term trends for seven others. Stellar cycles with P {>=} 1 year are present for at least 5% of our targets. Additionally, we present an analysis of the time-averaged activity levels of our sample, and search for correlations with other stellar properties. In particular, we find that more massive, earlier type (M0-M2) stars tend to be more active than later type dwarfs. Furthermore, high-metallicity stars tend to be more active at a given stellar mass. We also evaluate H{alpha} variability as a tracer of activity-induced radial velocity (RV) variation. For the M dwarf GJ 1170, H{alpha} variation reveals stellar activity patterns matching those seen in the RVs, mimicking the signal of a giant planet, and we find evidence that the previously identified stellar activity cycle of GJ 581 may be responsible for the recently retracted planet f in that system. In general, though, we find that H{alpha} is not frequently correlated with RV at the precision (typically 6-7 m s{sup -1}) of our measurements.

Robertson, Paul; Endl, Michael; Cochran, William D.; Dodson-Robinson, Sarah E., E-mail: paul@astro.as.utexas.edu [Department of Astronomy and McDonald Observatory, University of Texas at Austin, Austin, TX 78712 (United States)

2013-02-10

203

Local Benchmarks for the Evolution of Major-Merger Galaxies (II) --Palomar H_alpha/H_beta Observations of a K-Band Selected Sample  

Science.gov (United States)

As part of a multi-wavelength study of a sample of K-Band selected major-merger galaxy pairs at z=0, narrow band H_alpha and H_beta imaging observations have been carried out using Palomar 200" telescope. The H_alpha emission, once corrected for the dust extinction, is one of the best measurements of the star formation rate (SFR). As demonstrated in the literature, the combined H_alpha and H_beta imaging can result in a reliable extinction map. Complementary to the Spitzer observations of the same sample (see Xu et al., this volume), we aim to obtain an unbiased statistics of the SFR and its spatial distribution in these interacting galaxy systems. Furthermore, fitting the multiband (ugrizJHK) images and optical spectrographs in the SDSS-DR3 and 2MASS database with the stellar synthesis model (Bruzual & Charlot 2003) and dust extinction model (Calzetti 1994) provides additional constraints to the star formation history of these major-merger pairs.

Cheng, Yi-Wen; Xu, C. K.; Lu, N.; Cutri, R.; Domingue, D.; Gao, Y.; Huang, J.; Mazzarella, J.; Surace, J.; Sun, W.

2006-12-01

204

Abrupt Changes in the Photospheric Magnetic Structures and H-alpha Chromosphere during the 2006 December 6 X6.5 Flare  

Science.gov (United States)

The active region NOAA 10930 produced the last X-class flares of Solar Cycle 23, including one at 18:29 UT on December 6. Here we investigate the relationships between signatures of this flare observed in the photospheric magnetic field and white light and continuum intensity, and H-alpha chromosphere. We use GONG 1-minute magnetograms and continuum intensity images and (1-minute?) ISOON white-light and H-alpha images to show that (1) the sunspot penumbral area and mean intensity decreased abruptly during the flare; (2) the magnetic field changed in large, contiguous patterns inside and immediately outside the southern and western penumbra resulting in a more vertical penumbral field on average; (3) H-alpha brightenings were observed to begin around the GOES start time, the earliest occurring near the sunspot and later brightenings progressively further north and south of the center of the active region near magnetic neutral lines; and (4) most of the detected photospheric flux cancellation (75%) occurred during the flare, and the remainder before the flare.

Petrie, Gordon; Balasubramaniam, K. S.; Burtseva, O.; Pevtsov, A. A.

2012-05-01

205

Equivalence principles and electromagnetism  

Science.gov (United States)

The implications of the weak equivalence principles are investigated in detail for electromagnetic systems in a general framework. In particular, it is shown that the universality of free-fall trajectories (Galileo weak equivalence principle) does not imply the validity of the Einstein equivalence principle. However, the Galileo principle plus the universality of free-fall rotation states does imply the Einstein principle.

Ni, W.-T.

1977-01-01

206

Width of radiative decay ?(1520)???  

International Nuclear Information System (INIS)

The radiative decay ?(1520)??? was measured in the study of exclusive reaction p+N??(1520)K++N with the SPHINX spectrometer. The values of branching ratio and partial width of this decay were determined: BR[?(1520)???]=(1.02±0.21)x10-2 and ?[?(1520)???]=159±35 keV (statistical uncertainty; systematic uncertainty is below 15 %)

207

CD(4) has bounded width  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We prove that the constraint languages invariant under a short sequence of J\\'onsson terms (containing at most three non-trivial ternary terms) are tractable by showing that they have bounded width. This improves the previous result by Kiss and Valeriote and presents some evidence that the Larose-Zadori conjecture holds in the congruence-distributive case.

Carvalho, Catarina; Dalmau, Vi?ctor; Markovic?, Petar; Maro?ti, Miklo?s

2007-01-01

208

Average radiation widths and the giant dipole resonance width  

Energy Technology Data Exchange (ETDEWEB)

The average E1 radiation width can be calculated in terms of the energy Esub(G) and width GAMMAsub(G) of the Giant Dipole Resonance (GDR). While various models can predict Esub(G) quite reliably, the theoretical situation regarding ..lambda..sub(G) is much less satisfactory. We propose a simple phenomenological model which is able to provide GAMMAsub(G) values in good agreement with experimental data for spherical or deformed intermediate and heavy nuclei. In particular, this model can account for shell effects in GAMMAsub(G), and can be used in conjunction with the droplet model. The GAMMAsub(G) values derived in such a way are used to compute average E1 radiation widths which are quite close to the experimental values. The method proposed for the calculation of GAMMAsub(G) also appears to be well suited when the GDR characteristics of extended sets of nuclei are required, as is namely the case in nuclear astrophysics.

Arnould, M.; Thielemann, F.K.

1982-11-01

209

Average radiation widths and the giant dipole resonance width  

International Nuclear Information System (INIS)

The average E1 radiation width can be calculated in terms of the energy Esub(G) and width GAMMAsub(G) of the Giant Dipole Resonance (GDR). While various models can predict Esub(G) quite reliably, the theoretical situation regarding ?sub(G) is much less satisfactory. We propose a simple phenomenological model which is able to provide GAMMAsub(G) values in good agreement with experimental data for spherical or deformed intermediate and heavy nuclei. In particular, this model can account for shell effects in GAMMAsub(G), and can be used in conjunction with the droplet model. The GAMMAsub(G) values derived in such a way are used to compute average E1 radiation widths which are quite close to the experimental values. The method proposed for the calculation of GAMMAsub(G) also appears to be well suited when the GDR characteristics of extended sets of nuclei are required, as is namely the case in nuclear astrophysics. (orig.)

210

An Equivalent Gauge and the Equivalence Theorem  

Science.gov (United States)

I describe a novel covariant formulation of massive gauge theories in which the longitudinal polarization vectors do not grow with the energy. Therefore in the present formalism, differently from the ordinary one, the energy and coupling power-counting is completely transparent at the level of individual Feynman diagrams, with obvious advantages both at the conceptual and practical level. Since power-counting is transparent, the high-energy limit of the amplitudes involving longitudinal particles is immediately taken, and the Equivalence Theorem is easily demonstrated at all orders in perturbation theory. Since the formalism makes the Equivalence Theorem self-evident, and because it is based on a suitable choice of the gauge, we can call it an “Equivalent Gauge”.

Wulzer, Andrea

2014-08-01

211

?(1520) ? ?? Radiative-Decay Width  

International Nuclear Information System (INIS)

The radiative decay ?(1520) ? ?? was recorded in the exclusive reaction p + N ? ?(1520)K+ + N at the SPHINX facility. The branching ratio for this decay and the corresponding partial width were found to be, respectively, Br[?(1520) ? ??] = (1.02 ± 0.21) x 10-2 and ?[?(1520) ? ??] = 159 ± 35 keV (the quoted errors are purely statistical, the systematic errors being within 15%)

212

V, R, I and H$\\alpha$ photometry of circumnuclear star forming regions in four galaxies with different levels of nuclear activity  

CERN Document Server

V,R,I continuum bands and Halpha + [NII] photometry for circumnuclear star forming regions (CNSFR) is presented, for galaxies with different kinds of nuclear activity: NGC 7469 (Sy 1), NGC 1068 (Sy 2), NGC 7177 (LINER) and NGC 3310 (Starburst). Their Halpha luminosities (0.02 - 7x10**40 erg/s; uncorrected for internal extinction), are comparable to those observed in other galaxies. No systematic differences in the broad band colours are found for the CNSFR in the different galaxies, except for those in NGC 3310 which are considerably bluer, partially due to a younger stellar population. Using theoretical evolutionary synthesis models some colours can be reproduced by single populations (between 7 and 300 Myr) and extinction 0.5-1.5 mag). However, in many cases, the observed equivalent width of Halpha, require a younger population. NGC 1068, 7177 and 7469, are fitted by a two-burst population model at solar metallicity; the age difference between both populations is around 5-7 Myr and the younger burst involve...

Díaz, A I; Terlevich, E; Terlevich, R J; Sánchez-Portál, M; Aretxaga, I; Diaz, Angeles I.; Alvarez, Mar Alvarez; Terlevich, Elena; Terlevich, Roberto; Portal, Miguel Sanchez; Aretxaga, Itziar

1999-01-01

213

A derived equivalence between cluster equivalent algebras  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Let $Q$ be an acyclic quiver. Associated with any element $w$ of the Coxeter group of $Q$, triangulated categories $\\underline{\\Sub}\\Lambda_w$ were introduced in \\cite{Bua2}. There are shown to be triangle equivalent to generalized cluster categories $\\Cc_{\\Gamma_w}$ associated to algebras $\\Gamma_w$ of global dimension $\\leq 2$ in \\cite{ART}. For $w$ satisfying a certain property, called co-$c$-sortable, other algebras $A_w$ of global dimension $\\leq 2$ are constructed in \\...

Amiot, Claire

2009-01-01

214

The environmental impacts on the star formation main sequence: an H-alpha study of the newly discovered rich cluster at z=1.52  

CERN Document Server

We report the discovery of a strong over-density of galaxies in the field of a radio galaxy at z=1.52 (4C65.22) based on our broad-band and narrow-band (H-alpha) photometry with Subaru Telescope. We find that H-alpha emitters are located in the outskirts of the density peak (cluster core) dominated by passive red-sequence galaxies. This resembles the situation in lower-redshift clusters, suggesting that the newly discovered structure is a well-evolved rich galaxy cluster at z=1.5. Our data suggest that the color-density and stellar mass-density relations are already in place at z~1.5, mostly driven by the passive red massive galaxies residing within Rc<200 kpc from the cluster core. These environmental trends almost disappear when we consider only star-forming (SF) galaxies. We do not find SFR-density or SSFR-density relations amongst SF galaxies, and the location of the SF main sequence does not significantly change with environment. Nevertheless, we find a tentative hint that star-bursting galaxies (up-s...

Koyama, Yusei; Tadaki, Ken-ichi; Hayashi, Masao; Tanaka, Ichi; Shimakawa, Rhythm

2014-01-01

215

M/L, H-alpha Rotation Curves, and HI Measurements for 329 Nearby Cluster and Field Spirals: II. Evidence for Galaxy Infall  

CERN Document Server

We have conducted a study of optical and HI properties of spiral galaxies (size, luminosity, H-alpha flux distribution, circular velocity, HI gas mass) to explore the role of gas stripping as a driver of morphological evolution in clusters. We find a strong correlation between the spiral and S0 fractions within clusters, and the spiral fraction scales tightly with cluster X-ray gas luminosity. We explore young star formation and identify spirals that are (1) asymmetric, with truncated H-alpha emission and HI gas reservoirs on the leading edge of the disk, on a first pass through the dense intracluster medium in the cores of rich clusters; (2) strongly HI deficient and stripped, with star formation confined to the inner 5 kpc/h and 3 disk scale lengths; (3) reddened, extremely HI deficient and quenched, where star formation has been halted across the entire disk. We propose that these spirals are in successive stages of morphological transformation, between infalling field spirals and cluster S0s, and that the...

Vogt, N P; Giovanelli, R; Herter, T; Vogt, Nicole P.; Haynes, Martha P.; Giovanelli, Riccardo; Herter, Terry

2004-01-01

216

Comparing H-alpha and HI Surveys as Means to a Complete Local Galaxy Catalog in the Advanced LIGO/Virgo Era  

CERN Document Server

Identifying the electromagnetic counterparts of gravitational wave (GW) sources detected by upcoming networks of advanced ground-based interferometers will be challenging due in part to the large number of unrelated astrophysical transients within the ~10-100 square degree sky localizations. A potential way to greatly reduce the number of such false positives is to limit detailed follow-up to only those candidates near galaxies within the GW sensitivity range of ~200 Mpc for binary neutron star mergers. Such a strategy is currently hindered by the fact that galaxy catalogs are grossly incomplete within this volume. Here we compare two methods for completing the local galaxy catalog: (1) a narrow-band H-alpha imaging survey; and (2) an HI emission line radio survey. Using H-alpha fluxes, stellar masses (M_star), and star formation rates (SFR) from galaxies in the Sloan Digital Sky Survey (SDSS), combined with HI data from the GALEX Arecibo SDSS Survey and the Herschel Reference Survey, we estimate that a H-alp...

Metzger, Brian D; Berger, Edo

2012-01-01

217

A Study of Selection Methods for H alpha Emitting Galaxies at z~1.3 for the Subaru/FMOS Galaxy Redshift Survey for Cosmology (FastSound)  

CERN Document Server

The efficient selection of high-redshift emission galaxies is important for future large galaxy redshift surveys for cosmology. Here we describe the target selection methods for the FastSound project, a redshift survey for H alpha emitting galaxies at z=1.2-1.5 using Subaru/FMOS to measure the linear growth rate f\\sigma 8 via Redshift Space Distortion (RSD) and constrain the theory of gravity. To select ~400 target galaxies in the 0.2 deg^2 FMOS field-of-view from photometric data of CFHTLS-Wide (u*g'r'i'z'), we test several different methods based on color-color diagrams or photometric redshift estimates from spectral energy distribution (SED) fitting. We also test the improvement in selection efficiency that can be achieved by adding near-infrared data from the UKIDSS DXS (J). The success rates of H alpha detection with FMOS averaged over two observed fields using these methods are 11.3% (color-color, optical), 13.6% (color-color, optical+NIR), 17.3% (photo-z, optical), and 15.1% (photo-z, optical+NIR). Sel...

Tonegawa, Motonari; Akiyama, Masayuki; Dalton, Gavin; Glazebrook, Karl; Iwamuro, Fumihide; Sumiyoshi, Masanao; Tamura, Naoyuki; Yabe, Kiyoto; Coupon, Jean; Goto, Tomotsugu; Spitler, Lee R

2013-01-01

218

The H$\\alpha$ line forming region of AB Aur spatially resolved at sub-AU with the VEGA/CHARA spectro-interferometer  

CERN Document Server

A crucial issue in star formation is to understand the physical mechanism by which mass is accreted onto and ejected by a young star. The visible spectrometer VEGA on the CHARA array can be an efficient means of probing the structure and the kinematics of the hot circumstellar gas at sub-AU. For the first time, we observed the Herbig Ae star AB Aur in the H$\\alpha$ emission line, using the VEGA low spectral resolution on two baselines of the array. We computed and calibrated the spectral visibilities between 610 nm and 700 nm. To simultaneously reproduce the line profile and the visibility, we used a 1-D radiative transfer code that calculates level populations for hydrogen atoms in a spherical geometry and synthetic spectro-interferometric observables. We clearly resolved AB Aur in the H$\\alpha$ line and in a part of the continuum, even at the smallest baseline of 34 m. The small P-Cygni absorption feature is indicative of an outflow but could not be explained by a spherical stellar wind model. Instead, it f...

Perraut, K; Mourard, D; Rajabi, S; Bacciotti, F; Bério, Ph; Bonneau, D; Chesneau, O; Clausse, J M; Delaa, O; Marcotto, A; Roussel, A; Spang, A; Stee, Ph; Tallon-Bosc, I; McAlister, H; Brummelaar, T ten; Sturmann, J; Sturmann, L; Turner, N; Farrington, C; Goldfinger, P J

2010-01-01

219

Macroclumping as solution of the discrepancy between H{\\alpha} and P v mass loss diagnostics for O-type stars  

CERN Document Server

Recent studies of O-type stars demonstrated that discrepant mass-loss rates are obtained when different diagnostic methods are employed - fitting the unsaturated UV resonance lines (e.g. P v) gives drastically lower values than obtained from the H{\\alpha} emission. Wind clumping may be the main cause for this discrepancy. In a previous paper, we have presented 3-D Monte-Carlo calculations for the formation of scattering lines in a clumped stellar wind. In the present paper we select five O-type supergiants (from O4 to O7) and test whether the reported discrepancies can be resolved this way. In the first step, the analyses start with simulating the observed spectra with Potsdam Wolf-Rayet (PoWR) non-LTE model atmospheres. The mass-loss rates are adjusted to fit best to the observed H{\\alpha} emission lines. For the unsaturated UV resonance lines (i.e. P v) we then apply our 3-D Monte-Carlo code, which can account for wind clumps of any optical depths, a non-void inter-clump medium, and a velocity dispersion in...

Šurlan, B; Aret, A; Kubát, J; Oskinova, L M; Torres, A F

2013-01-01

220

Forbidden line and H-alpha profiles in T Tauri star spectra - A probe of anisotropic mass outflows and circumstellar disks  

Science.gov (United States)

The results of a high-resolution spectroscopic study of 10 T Tauri stars (TTS) and two Herbig emission stars are presented based on red echelle spectra including the lines of forbidden O I 6300 A, forbidden N II 6584 A, forbidden S II 6716, 6731 A, as well as H-alpha. The forbidden lines display a continuous progression of profile types. The velocity structure in the forbidden lines is critically examined and compared to computed line profiles for a number of different wind models. Constant velocity spherical or conical winds fail to reproduce the observed line profiles, which are better explained by a wind with a latitude-dependent velocity field. A prediction of the wind model correlating the velocity of the reversal at H-alpha and the forbidden line velocity structure as a function of the view angle to the star is explored. Estimates of the average densities and sizes for the TTS forbidden emission regions are presented, and mass-loss rates are computed. IRAS far-IR fluxes are used to estimate the disk sizes.

Edwards, Suzan; Heyer, Ingeborg; Cabrit, Sylvie; Strom, Stephen E.; Strom, Karen M.

1987-01-01

 
 
 
 
221

M/L, H-alpha Rotation Curves, and HI Measurements for 329 Nearby Cluster and Field Spirals: III. Evolutionin Fundamental Galaxy Parameters  

CERN Document Server

We have conducted a study of optical and HI properties of spiral galaxies (size, luminosity, H-alpha flux distribution, circular velocity, HI gas mass) to investigate causes (e.g., nature versus nurture) for variation within the cluster environment. We find HI deficient cluster galaxies to be offset in Fundamental Plane space, with disk scale lengths decreased by a factor of 25%. This may be a relic of early galaxy formation, caused by the disk coalescing out of a smaller, denser halo (e.g., higher concentration index) or by truncation of the hot gas envelope due to the enhanced local density of neighbors, though we cannot completely rule out the effect of the gas stripping process. The spatial extent of H-alpha flux and the B-band radius also decreases, but only in early type spirals, suggesting that gas removal is less efficient within steeper potential wells (or that stripped late type spirals are quickly rendered unrecognizable). We find no significant trend in stellar mass-to-light ratios or circular vel...

Vogt, N P; Giovanelli, R; Herter, T; Vogt, Nicole P.; Haynes, Martha P.; Giovanelli, Riccardo; Herter, Terry

2004-01-01

222

Migraine equivalents in childhood.  

Science.gov (United States)

Migraine equivalents are a group of periodic and paroxysmal neurologic diseases. Because headache is not a prominent symptom, the diagnosis might be challenging. The objective of the study was to evaluate the frequency and outcome of migraine equivalents. This was a retrospective study. We included benign paroxysmal torticollis of infancy, benign paroxysmal vertigo of infancy, abdominal migraine, cyclic vomiting, aura without migraine, and confusional migraine. We evaluated the frequency of events, treatment, and outcome. Out of 674 children with headache, 38 (5.6%) presented with migraine equivalents. Twenty-one were boys and the mean age was 6.1 years. Fifteen had abdominal migraine, 12 benign paroxysmal vertigo, 5 confusional migraine, 3 aura without migraine, 2 paroxysmal torticollis, and 1 cyclic vomiting. Prophylactic treatment was introduced in 23 patients; 4 lost follow-up and 19 had significant improvement. We conclude that the correct diagnosis of migraine equivalents enables an effective treatment with an excellent outcome. PMID:24092892

Teixeira, Karine C S; Montenegro, Maria Augusta; Guerreiro, Marilisa M

2014-10-01

223

Neutron dose equivalent meter  

Science.gov (United States)

A neutron dose equivalent detector for measuring neutron dose capable of accurately responding to neutron energies according to published fluence to dose curves. The neutron dose equivalent meter has an inner sphere of polyethylene, with a middle shell overlying the inner sphere, the middle shell comprising RTV.RTM. silicone (organosiloxane) loaded with boron. An outer shell overlies the middle shell and comprises polyethylene loaded with tungsten. The neutron dose equivalent meter defines a channel through the outer shell, the middle shell, and the inner sphere for accepting a neutron counter tube. The outer shell is loaded with tungsten to provide neutron generation, increasing the neutron dose equivalent meter's response sensitivity above 8 MeV.

Olsher, Richard H. (Los Alamos, NM); Hsu, Hsiao-Hua (Los Alamos, NM); Casson, William H. (Los Alamos, NM); Vasilik, Dennis G. (Los Alamos, NM); Kleck, Jeffrey H. (Menlo Park, CA); Beverding, Anthony (Foster City, CA)

1996-01-01

224

Equivalent local Dirac potentials  

Science.gov (United States)

A transformation is used to obtain sets of equivalent Lorentz scalar, Lorentz four-vector, and tensor optical potentials. These potentials are used in the Dirac equation for describing elastic scattering observables.

Clark, B. C.; Hama, S.; Kalbermann, S. G.; Cooper, E. D.; Mercer, R. L.

1985-02-01

225

CIV Line-Width Anomalies  

DEFF Research Database (Denmark)

Comparison of six high-redshift quasar spectra obtained with the Large Binocular Telescope with previous observations from the Sloan Digital Sky Survey shows that failure to correctly identify absorption and other problems with accurate characterization of the CIV emission line profile in low S/N data can severely limit the reliability of single-epoch mass estimates based on the CIV emission line. We combine the analysis of these new high-quality data with a reanalysis of three other samples based on high S/N spectra of the CIV emission line region. We find that a large scatter between the Hbeta- and CIV-based masses remains even for this high S/N sample when using the FWHM to characterize the BLR velocity dispersion and the standard virial assumption to calculate the mass. However, we demonstrate that using high-quality data and the line dispersion to characterize the CIV line width leads to a high level of consistency between CIV- and Hbeta-based masses, with

Denney, Kelly D.; Pogge, Richard W.

2013-01-01

226

Gluing derived equivalences together  

CERN Document Server

The Grothendieck construction of a diagram X of categories can be seen as a process to construct a single category Gr(X) by gluing categories in the diagram together. Here we formulate diagrams of categories as oplax functors from a small category I to the 2-category k-Cat of small k-categories for a fixed commutative ring k. In our previous paper we defined derived equivalences of those oplax functors. Roughly speaking two oplax functors X, X' : I \\to k-Cat are derived equivalent if there exist a family of triangle equivalences F(i) from the derived categories D(Mod X(i)) to D(Mod X'(i)) indexed by the objects i in I such that for each morphism a : i \\to j in I F(j)D(Mod X)(a) is naturally isomorphic to D(Mod X')(a)F(i), where D(Mod X)(a) : D(Mod X(i)) \\to D(Mod X'(i)) is given by the left derived tensor product with an X(i)-X'(i)-bimodule \\bar{X(a)} naturally defined by the functor X(a) : X(i) \\to X(j). In this paper we glue the derived equivalences F(i) together to obtain a derived equivalence between Grot...

Asashiba, Hideto

2012-01-01

227

Exact calculation of alpha decay widths by the two body model and comparison with experimental widths  

International Nuclear Information System (INIS)

The alpha decay widths are computed exactly using two body model. The computed and experimental widths are compared and a very satisfactory agreement is obtained in both the absolute values and the dispersion of the widths

228

High-dispersion observations of H-alpha in the suspected brown dwarf, white dwarf binary system G29-38  

International Nuclear Information System (INIS)

High-dispersion spectroscopy of the H-alpha absorption line of the cool DA white dwarf G29-38 is reported. This is the star for which a recently detected IR excess has been suggested to be due to a possible brown dwarf companion. Three echelle spectra show no evidence for radial-velocity variations larger than about 1.1 + or - 8.7 km/s and are used to derive a weighted heliocentric radial velocity of 33.7 + or - 4.3 kms/s for the white dwarf. The observations of a sharp absorption-line core restricts the possible rotation of the white dwarf to 40 km/s or less and ensures that any surface magnetic field has a strength of 100,000 G or less. These results make it unlikely that the DA white dwarf has previously been in a cataclysmic variable accretion phase. 18 references

229

Very Large Telescope Observations of the peculiar globular cluster NGC6712. Discovery of a UV, H-alpha excess star in the core  

CERN Document Server

We present results from multi-band observations in the central region of the cluster NGC6712 with the ESO-Very Large Telescope. Using high resolution images we have identified three UV-excess stars. In particular two of them are within the cluster core, a few arcsec apart: the first object is star "S" which previous studies identified as the best candidate to the optical counterpart to the luminous X-ray source detected in this cluster. The other UV object shows clearcut H-alpha emission and, for this reason, is an additional promising interacting binary candidate (a quiescent LMXB or a CV). The presence of two unrelated interacting binary systems a few arcsec apart in the core of this low-density cluster is somewhat surprising and supports the hypothesis that the (internal) dynamical history of the cluster and/or the (external) interaction with the Galaxy might play a fundamental role in the formation of these peculiar objects.

Ferraro, F R; Paresce, F; De Marchi, G; Ferraro, Francesco R.; Paltrinieri, Barbara; Paresce, Francesco; Marchi, Guido De

2000-01-01

230

Hadron widths in mixed-phase matter  

CERN Document Server

We derive classically an expression for a hadron width in a two-phase region of hadron gas and quark-gluon plasma (QGP). The presence of QGP gives hadrons larger widths than they would have in a pure hadron gas. We find that the $\\phi$ width observed in a central Au+Au collision at $\\sqrt{s}=200$ GeV/nucleon is a few MeV greater than the width in a pure hadron gas. The part of observed hadron widths due to QGP is approximately proportional to $(dN/dy)^{-1/3}$.

Seibert, D; Seibert, David; Ko, Che Ming

1994-01-01

231

Cryogenic equivalence principle experiment  

International Nuclear Information System (INIS)

The Weak Equivalence Principle is the hypothesis that the ratio of passive gravitational mass to inertial mass is the same for all bodies regardless of their composition. This principle has a fundamental place in physics as the experimental basis for Einstein's Strong Equivalence Principle, which is a postulate of General Relativity. Since any violation of the principle would have very profound consequences for gravitational theory, it is important to test the principle to the greatest possible accuracy. The author describes an experiment which consists in directly comparing the accelerations of two test bodies floating in superconducting magnetic bearings. (Auth.)

232

Current Conveyor Equivalent Circuits  

Directory of Open Access Journals (Sweden)

Full Text Available An equivalence between a class of (current conveyor CC II+ and CC II- circuits is established. CC IIequivalent circuit uses one extra element. However, under certain condition, the extra element can be eliminated. As an illustration of the application of this equivalence, minimal first and second order all-pass filters are derived. Incertain cases, it is possible to compensate the effect of the input resistor of CC at port X. At the end, an open problem of realizing an Nth order (N > 2 minimal all-pass filter is stated.

Tejmal S. Rathore

2012-02-01

233

Equivalence Classes of Colorings  

Digital Repository Infrastructure Vision for European Research (DRIVER)

For any link and for any modulus $m$ we introduce an equivalence relation on the set of non-trivial m-colorings of the link (an m-coloring has values in Z/mZ). Given a diagram of the link, the equivalence class of a non-trivial m-coloring is formed by each assignment of colors to the arcs of the diagram that is obtained from the former coloring by a permutation of the colors in the arcs which preserves the coloring condition at each crossing. This requirement implies topolog...

Ge, Jun; Jablan, Slavik; Kauffman, Louis H.; Lopes, Pedro

2012-01-01

234

Reflective-coreflective equivalence  

CERN Document Server

We explore a curious type of equivalence between certain pairs of reflective and coreflective subcategories. We illustrate with examples involving noncommutative duality for C*-dynamical systems and compact quantum groups, as well as examples where the subcategories are actually isomorphic.

Bédos, Erik; Quigg, John

2010-01-01

235

Detonation cell widths in hydrogen-air-diluent mixtures  

International Nuclear Information System (INIS)

In this paper I report on the influence of steam and carbon dioxide on the detonability of hydrogen-air mixtures. Data were obtained on the detonation cell width in a heated detonation tube that is 0.43 m in diameter and 13.1 m long. The detonation cell widths were correlated using a characteristic length calculated from a chemical kinetic model. The addition of either diluent to a hydrogen-air mixture increased the cell width for all equivalence ratios. For equal diluent concentrations, however, carbon dioxide not only yielded larger increases in the cell width than steam, but its efficacy relative to steam was predicted to increase with increasing concentration. The range of detonable hydrogen concentrations in a hydrogen-air mixture initially at 1 atm pressure was found to be between 11.6 percent and 74.9 percent for mixtures at 20 degree C and 9.4 percent and 76.9 percent for mixtures at 100 degree C. The detonation limit was between 38.8 percent and 40.5 percent steam for a stoichiometric hydrogen-air-steam mixture initially at 100 degree C and 1 atm. 10 refs., 4 figs., 1 tab

236

Detonation cell widths in hydrogen-air-diluent mixtures  

Energy Technology Data Exchange (ETDEWEB)

In this paper I report on the influence of steam and carbon dioxide on the detonability of hydrogen-air mixtures. Data were obtained on the detonation cell width in a heated detonation tube that is 0.43 m in diameter and 13.1 m long. The detonation cell widths were correlated using a characteristic length calculated from a chemical kinetic model. The addition of either diluent to a hydrogen-air mixture increased the cell width for all equivalence ratios. For equal diluent concentrations, however, carbon dioxide not only yielded larger increases in the cell width than steam, but its efficacy relative to steam was predicted to increase with increasing concentration. The range of detonable hydrogen concentrations in a hydrogen-air mixture initially at 1 atm pressure was found to be between 11.6 percent and 74.9 percent for mixtures at 20{degree}C and 9.4 percent and 76.9 percent for mixtures at 100{degree}C. The detonation limit was between 38.8 percent and 40.5 percent steam for a stoichiometric hydrogen-air-steam mixture initially at 100{degree}C and 1 atm. 10 refs., 4 figs., 1 tab.

Stamps, D.W.

1990-01-01

237

Correspondences. Equivalence relations  

International Nuclear Information System (INIS)

We comment on sections paragraph 3 'Correspondences' and paragraph 6 'Equivalence Relations' in chapter II of 'Elements de mathematique' by N. Bourbaki in order to simplify their comprehension. Paragraph 3 exposes the ideas of a graph, correspondence and map or of function, and their composition laws. We draw attention to the following points: 1) Adopting the convention of writting from left to right, the composition law for two correspondences (A,F,B), (U,G,V) of graphs F, G is written in full generality (A,F,B)o(U,G,V) = (A,FoG,V). It is not therefore assumed that the co-domain B of the first correspondence is identical to the domain U of the second (EII.13 D.7), (1970). 2) The axiom of choice consists of creating the Hilbert terms from the only relations admitting a graph. 3) The statement of the existence theorem of a function h such that f = goh, where f and g are two given maps having the same domain (of definition), is completed if h is more precisely an injection. Paragraph 6 considers the generalisation of equality: First, by 'the equivalence relation associated with a map f of a set E identical to (x is a member of the set E and y is a member of the set E and x:f = y:f). Consequently, every relation R(x,y) which is equivalent to this is an equivalence relation in E (symmetrical, transitive, reflexive); then R admits a graph included in E x E, etc. Secondly, by means of the Hilbert term of a relation R submitted to the equivalence. In this last case, if R(x,y) is separately collectivizing in x and y, theta(x) is not the class of objects equivalent to x for R (EII.47.9), (1970). The interest of bringing together these two subjects, apart from this logical order, resides also in the fact that the theorem mentioned in 3) can be expressed by means of the equivalence relations associated with the functions f and g. The solutions of the examples proposed reveal their simplicity

238

A high-precision pulse-width modulator source  

International Nuclear Information System (INIS)

A novel high-resolution pulse-width modulator (PWM) is being developed for a new digital regulator for the Advanced Photon Source power converters. The circuit features 82-ps setability over an 80-(micro)s range. Our application requires a 50-(micro)s fill-scale range; therefore the 82-ps setability is equivalent to better than 19 bits. The circuit is presently implemented as a VME module and is an integral part of the digital regulator prototype. The design concept and performance results will be presented

239

An HNCO-based Pulse Scheme for the Measurement of 13C{alpha}-1H{alpha} One-bond Dipolar couplings in 15N, 13C Labeled Proteins  

Energy Technology Data Exchange (ETDEWEB)

A triple resonance pulse scheme is presented for recording 13C{alpha}-1H{alpha} one-bond dipolar couplings in 15N, 13C labeled proteins. HNCO correlation maps are generated where the carbonyl chemical shift is modulated by the 13C{alpha}-1H{alpha} coupling, with the two doublet components separated into individual data sets. The experiment makes use of recently described methodology whereby the protein of interest is dissolved in a dilute solution of bicelles which orient above a critical temperature, thus permitting measurement of significant couplings (Tjandra and Bax, 1997a). An application to the protein ubiquitin is described.

Yang Daiwen; Tolman, Joel R. [University of Toronto, The Protein Engineering Centers of Excellence and Departments of Medical Genetics, Biochemistry and Chemistry (Canada); Goto, Natalie K. [University of Toronto, Department of Biochemistry (Canada); Kay, Lewis E. [University of Toronto, The Protein Engineering Centers of Excellence and Departments of Medical Genetics, Biochemistry and Chemistry (Canada)

1998-08-15

240

Quantum Equivalence Principle  

CERN Document Server

A simple mapping procedure is presented by which classical orbits and path integrals for the motion of a point particle in flat space can be transformed directly into those in curved space with torsion. Our procedure evolved from well-established methods in the theory of plastic deformations, where crystals with defects are described mathematically as images of ideal crystals under active nonholonomic coordinate transformations. Our mapping procedure may be viewed as a natural extension of Einstein's famous equivalence principle. When applied to time-sliced path integrals, it gives rise to a new quantum equivalence principle which determines short-time action and measure of fluctuating orbits in spaces with curvature and torsion. The nonholonomic transformations possesses a nontrivial Jacobian in the path measure which produces in a curved space an additional term proportional to the curvature scalar R, thus canceling a similar term found earlier by DeWitt. This cancelation is important for correctly describi...

Kleinert, H

1996-01-01

 
 
 
 
241

Width Distributions for Convex Regular Polyhedra  

CERN Document Server

The mean width is a measure on three-dimensional convex bodies that enjoys equal status with volume and surface area [Rota]. As the phrase suggests, it is the mean of a probability density f. We verify formulas for mean widths of the regular tetrahedron and the cube. Higher-order moments of f_tetra and f_cube have not been examined until now. Assume that each polyhedron has edges of unit length. We deduce that the mean square width of the regular tetrahedron is 1/3+(3+sqrt(3))/(3*pi) and the mean square width of the cube is 1+4/pi.

Finch, Steven R

2011-01-01

242

Approximation Algorithms for Directed Width Parameters  

CERN Document Server

Treewidth of an undirected graph measures how close the graph is to being a tree. Several problems that are NP-hard on general graphs are solvable in polynomial time on graphs with bounded treewidth. Motivated by the success of treewidth, several directed analogues of treewidth have been introduced to measure the similarity of a directed graph to a directed acyclic graph (DAG). Directed treewidth, D-width, DAG-width, Kelly-width and directed pathwidth are some such parameters. In this paper, we present the first approximation algorithms for all these five directed width parameters. For directed treewidth and D-width we achieve an approximation factor of O(sqrt{logn}). For DAG-width, Kelly-width and directed pathwidth we achieve an O({\\log}^{3/2}{n}) approximation factor. Our algorithms are constructive, i.e., they construct the decompositions associated with these parameters. The width of these decompositions are within the above mentioned factor of the corresponding optimal width.

Kintali, Shiva; Kumar, Akash

2011-01-01

243

The effect of change in width on stress distribution along the curved segments of stents  

International Nuclear Information System (INIS)

Curved structural members are widely seen in our surroundings, such as railway supports in playgrounds resembling a c-ring structure. The common geometry of the curved member consists of a segment of a circular ring with a uniform width. The curved section is of constant width in most cardiovascular stents. This study focuses on curved strut members whose width changes along the curved segment. The location of the maximum equivalent stress varies depending on the manner in which the width changes. When the width is constant or larger toward the top, the maximum equivalent stress is developed at the top. Meanwhile, when the area is reduced toward the bottom, the largest equivalent stress is developed some distance from the top. Simple equations, based on the mechanics of materials and the theory of elasticity, were compared favorably with the results from finite element analysis. Included are elaborations of the distribution of the change of stress. The suggested strategy of changing the width, with refinements, could be applied to the optimal design of structural members, including pipes and medical devices such as stents

244

The effect of change in width on stress distribution along the curved segments of stents  

Energy Technology Data Exchange (ETDEWEB)

Curved structural members are widely seen in our surroundings, such as railway supports in playgrounds resembling a c-ring structure. The common geometry of the curved member consists of a segment of a circular ring with a uniform width. The curved section is of constant width in most cardiovascular stents. This study focuses on curved strut members whose width changes along the curved segment. The location of the maximum equivalent stress varies depending on the manner in which the width changes. When the width is constant or larger toward the top, the maximum equivalent stress is developed at the top. Meanwhile, when the area is reduced toward the bottom, the largest equivalent stress is developed some distance from the top. Simple equations, based on the mechanics of materials and the theory of elasticity, were compared favorably with the results from finite element analysis. Included are elaborations of the distribution of the change of stress. The suggested strategy of changing the width, with refinements, could be applied to the optimal design of structural members, including pipes and medical devices such as stents

Jang, Kyung Soon; Kang, Tae Won; Lee, Kee Sung; Kim, Chul; Kim, Tae Woo [Kookmin University, Seoul (Korea, Republic of)

2010-06-15

245

Mean Width of a Regular Simplex  

CERN Document Server

The mean width is a measure on n-dimensional convex bodies. An integral formula for the mean width of a regular n-simplex appeared in the electrical engineering literature in 1997. As a consequence, expressions for the expected range of a sample of n+1 normally distributed variables, for ninfty.

Finch, Steven R

2011-01-01

246

Upper Limits on the Higgs Width  

CERN Document Server

Slides for BSM-HW@LPC on: Direct and indirect measurements of the Higgs boson width from ATLAS and CMS. Direct limits on the Higgs boson width are approximately $<2.4$ GeV and indirect limits using the combination of on- and off-shell measurements are approximately $<5\\cdot$ SM expectation.

Long, Jonathan; The ATLAS collaboration

2014-01-01

247

Equivalence of Dual Graphs  

Directory of Open Access Journals (Sweden)

Full Text Available Because of interesting and useful geometric as well as topological properties, alternating knots (links were regarded to have an important role in knot theory and 3-manifold theory. Many knots with crossing number less than 10 are alternating. It was the properties of alternating knots that enable the earlier knot tabulators to construct tables with relatively few mistakes or omissions. Graphs of knots (links have been repeatedly employed in knot theory. This article is devoted to establish relationship between knots and planar graphs. This relationship not only enables us see the equivalence of the graphs corresponding to black regions and the dual graph corresponding to white regions.

M. Azram

2013-07-01

248

Spiral inflow feeding the nuclear starburst in M83, observed in H-alpha emission with the GHAFAS Fabry-Perot interferometer  

CERN Document Server

We present observations of the nearby barred starburst galaxy, M83 (NGC5236), with the new Fabry-Perot interferometer GHAFAS mounted on the 4.2 meter William Herschel Telescope on La Palma. The unprecedented high resolution observations, of 16 pc/FWHM, of the H-alpha-emitting gas cover the central two kpc of the galaxy. The velocity field displays the dominant disk rotation with signatures of gas inflow from kpc scales down to the nuclear regions. At the inner Inner Lindblad Resonance radius of the main bar and centerd at the dynamical center of the main galaxy disk, a nuclear $5.5 (\\pm 0.9) \\times 10^8 M_\\odot$ rapidly rotating disk with scale length of $60 \\pm 20$ pc has formed. The nuclear starburst is found in the vicinity as well as inside this nuclear disk, and our observations confirm that gas spirals in from the outer parts to feed the nuclear starburst, giving rise to several star formation events at different epochs, within the central 100 pc radius of M83.

Fathi, Kambiz; Lundgren, Andreas A; Carignan, Claude; Hernandez, Olivier; Amram, Philippe; Balard, Philippe; Boulesteix, Jacques; Gach, Jean-Luc; Knapen, Johan H; Relaño, Monica

2007-01-01

249

Dust Obscuration and Metallicity at High Redshift: New Inferences from UV, H-alpha, and 8 Micron Observations of z~2 Star-Forming Galaxies  

CERN Document Server

We use a sample of 90 spectroscopically-confirmed Lyman Break Galaxies with H-alpha and 24 micron observations to constrain the relationship between rest-frame 8 micron luminosity, L(8), and star formation rate (SFR) for L* galaxies at z~2. We find a tight correlation with 0.24 dex scatter between L8 and L(Ha)/SFR for z~2 galaxies with L(IR)~10^10 - 10^12 Lsun. Employing this relationship with a larger sample of 392 galaxies with spectroscopic redshifts, we find that the UV slope can be used to recover the dust attenuation of the vast majority of L* galaxies at z~2 to within 0.4 dex scatter using the local correlation. Separately, young galaxies with ages <100 Myr appear to follow an extinction curve that is steeper than the one found for local starburst galaxies. Therefore, such young galaxies may be significantly less dusty than inferred previously. Our results provide the first direct evidence, independent of the UV slope, for a correlation between UV and bolometric luminosity at high redshift, in the s...

Reddy, Naveen A; Pettini, Max; Steidel, Charles C; Shapley, Alice E

2010-01-01

250

Thermal width of quarkonium from holography  

Energy Technology Data Exchange (ETDEWEB)

From the AdS/CFT correspondence, the effects of charge and finite 't Hooft coupling correction on the thermal width of a heavy quarkonium are investigated. To study the charge effect,we consider Maxwell charge which is interpreted as quarkmedium. In the case of finite 't Hooft coupling corrections, R{sup 4} terms and Gauss-Bonnet gravity have been considered, respectively. It is shown that these corrections affect the thermal width. It is also argued that by decreasing the 't Hooft coupling, the thermal width becomes effectively smaller. Interestingly, this is similar to analogous calculations in a weakly coupled plasma. (orig.)

Fadafan, Kazem Bitaghsir; Tabatabaei, Seyed Kamal [Shahrood University, Physics Department, Shahrood (Iran, Islamic Republic of)

2014-04-15

251

Infinite-dimensional generalization of Kolmogorov widths  

CERN Document Server

Recently the theory of widths of Kolmogorov-Gelfand has received a great deal of interest due to its close relationship with the newly born area of Compressive Sensing in Signal Processing. However fundamental problems of the theory of widths in multidimensional Theory of Functions remain untouched, as well as analogous problems in the theory of multidimensional Signal Analysis. In the present paper we provide a multidimensional generalization of the original result of Kolmogorov about the widths of an "ellipsoidal sets" consisting of functions defined on an interval.

Kounchev, Ognyan

2011-01-01

252

Stuttering Equivalence for Parity Games  

CERN Document Server

We study the process theoretic notion of stuttering equivalence in the setting of parity games. We demonstrate that stuttering equivalent vertices have the same winner in the parity game. This means that solving a parity game can be accelerated by minimising the game graph with respect to stuttering equivalence. While, at the outset, it might not be clear that this strategy should pay off, our experiments using typical verification problems illustrate that stuttering equivalence speeds up solving parity games in many cases.

Cranen, Sjoerd; Willemse, Tim A C

2011-01-01

253

Radiative widths of neutron scattering resonances  

International Nuclear Information System (INIS)

The radiative widths of resonances with large neutron widths in 19F, 24Mg, 27Al, 28Si, 56Fe and 207Pb have been measured relative to gold in the 20-80 keV neutron energy range. Moxon-Rae ?-ray detectors were used with time-of-flight discrimination of scattered neutron events. These results help resolve existing discrepancies in the data by elucidating the contribution of resonance neutron scattering to capture ?-ray yields. (author)

254

Neutron beam compressors for pulse width reduction  

International Nuclear Information System (INIS)

In the context of intensity and resolution optimization of a neutron time-of-flight spectrometer several methods of beam width reduction at the chopper are considered aiming at a reduction of the neutron pulse width at minimum loss of intensity. The most advantageous technique discussed uses a double-trumpet arrangement in which the chopper is placed in between converging and diverging neutron guide sections. 7 refs., 1 fig

255

Quadrupole radiative widths in deformed nuclei  

International Nuclear Information System (INIS)

Within the quasiparticle-phonon model of nuclei the reduced widths of quadrupole radiative transitions and ratio of partial widths ?E1/?E2 with the weighting function of second order are calculated. Calculated values of KE2 and ?E1/?E2 for 156Gd, 158Gd and 168Er deformed even-even nuclei are in qualitative agreement with the available experimental data

256

Equivalent nozzles in thermomechanical problems  

International Nuclear Information System (INIS)

Axisymmetric nozzle-sphere geometry models for finite element analysis are described which are equivalent to three-dimensional nozzle-cylinder intersections in the sense of giving the same maximum equivalent stress. This equivalence is obtained by varying the radius of the sphere. Both mechanical and thermal load cases typical of actual operating conditions are considered, although it is shown that it is not possible to use the same equivalent model on both types of load. The implications are that cheaper computing costs could be obtained for expensive non-linear calculations provided the loss in accuracy of the results through using the equivalence model was not too severe. (author)

257

Appropriate energy window width for gamma camera  

International Nuclear Information System (INIS)

Introduction: scatter radiation is one of the major sources of error in nuclear medicine data processing. Different methods of scatter correction have been introduced in order to improve the quality of data. However the best method is to avoid recording of scatter photons in acquisition. The only difference between scattered and non-scattered photon is the energy. Pulse height analyzer is the only option available to discriminate primary photons from scattered ones. Energy resolutions of the gamma camera is gradually improving consequently the energy window width has to be decreased accordingly. In this study we tried to determine the most appropriate energy window width for present gamma camera systems. Methods and materials: since it is not possible to retrieve the data spectrum from the most of the gamma camera systems a simple method was developed to extract the data from the image of the energy spectrum. Using a scattered phantom different level of scatter and count rate were generated and corresponding energy spectrum data were analyzed. It was assumed that around the peak of the spectrum the primary photons obey a Gaussian distribution. Results: the data were analyzed using three different methods. All methods proved that the optimum window width regarding the present gamma camera energy resolution is 15%. At this level the scattered radiation is decreased to 5%. In comparison to the conventional window width of 20% the sensitivity does not change dramatically. Conclusion: at the present, for the most gamma camera the energy window width of 20% is recommended. However occasionally energy window width of 15 % and 25% are also used. In this study the energy spectrum at different levels of scatter were analyzed and the most suitable energy window width was found to be 15% for the gamma camera having approximate energy resolution of 11%. At this window setting the scatter decreases to 5% of the total counts recorded. Visually the quality of images does not improves significantly. However accuracy of data quantification improve significantly

258

Appropriate energy window width for gamma camera  

Directory of Open Access Journals (Sweden)

Full Text Available Introduction: Scatter radiation is one of the major sources of error in nuclear medicine data processing. Different methods of scatter correction have been introduced in order to improve the quality of data. However the best method is to avoid recording of scatter photons in acquisition. The only difference between scattered and non-scattered photons is the energy. Pulse height analyzer is the only option available to discriminate primary photons from scattered ones. Energy resolution of the gamma camera is gradually improving consequently the energy window width has to be decreased accordingly. In this study we tried to determine the most appropriate energy window width for present gamma camera systems. Methods and Materials: Since it is not possible to retrieve the data spectrum from the most of the gamma camera systems, a simple method was developed to extract the data from the image of the energy spectrum. Using a scatter phantom different level of scatter and count rate were generated and corresponding energy spectrum data were analyzed. It was assumed that around the peak of the spectrum, the primary photons obey a Gaussian distribution. Results: The data were analyzed using three different methods. All methods prove that the optimum window width regarding the present gamma camera energy resolution is 15%. At this level, the scattered radiation is decreased to 5%. In comparison to the conventional widow width of 20%, the sensitivity does not change dramatically. Conclusion: At the present, for most gamma camera, the energy window width of 20% is recommended. However occasionally energy window width of 15% and 25% are also used. In this study the energy spectrum at different levels of scatter were analyzed and the most suitable energy window width was found to be 15% for the gamma camera having approximate energy resolution of 11%. At this window setting the scatter decreases to 5% of the total counts recorded. Visually the quality of the images dose not improves significantly. However accuracy of data quantification improve significantly.

Jabbari N

2004-06-01

259

Biomonitoring Equivalents for selenium.  

Science.gov (United States)

Selenium is an essential nutrient for human health with a narrow range between essentiality and toxicity. Selenium is incorporated into several proteins that perform important functions in the body. With insufficient selenium intake, the most notable effect is Keshan disease, an endemic cardiomyopathy in children. Conversely, excessive selenium intake can result in selenosis, manifested as brittle nails and hair and gastro-intestinal disorders. As such, guidance values have been established to protect against both insufficient and excessive selenium exposures. Dietary Reference Intakes (DRIs) have been established as standard reference values for nutritional adequacy in North America. To protect against selenosis resulting from exposure to excessive amounts of selenium, several government and non-governmental agencies have established a range of guidance values. Exposure to selenium is primarily through the diet, but monitoring selenium intake is difficult. Biomonitoring is a useful means of assessing and monitoring selenium status for both insufficient and excessive exposures. However, to be able to interpret selenium biomonitoring data, levels associated with both DRIs and toxicity guidance values are required. Biomonitoring Equivalents (BEs) were developed for selenium in whole blood, plasma and urine. The BEs associated with assuring adequate selenium intake (Estimated Average Requirements - EAR) are 100, 80 and 10?g/L in whole blood, plasma and urine, respectively. The BEs associated with protection against selenosis range from 400 to 480?g/L in whole blood, 180-230?g/L in plasma, and 90-110?g/L in urine. These BE values can be used by both regulatory agencies and public health officials to interpret selenium biomonitoring data in a health risk context. PMID:25068883

Hays, Sean M; Macey, Kristin; Nong, Andy; Aylward, Lesa L

2014-10-01

260

Line width of Josephson flux flow oscillators  

DEFF Research Database (Denmark)

A combination of wide-band electronic tunability and moderate free-running line width makes the Josephson flux flow oscillator (FFO) a perfect on-chip local oscillator for integrated submillimeter-wave SIS receivers. The possibility of FFO phase locking at all frequencies of interest has to be proven before one initiates real FFO applications. To achieve this goal a comprehensive set of line width measurements of the FFO operating in different regimes has been performed. FFOs with tapered shape have been successfully implemented in order to avoid the superfine resonant structure with voltage spacing of about 20 nV and extremely low differential resistance, recently observed in the IVC of the standard rectangular geometry. The obtained results have been compared with existing theories and FFO models in order to understand and possibly eliminate excess noise in the FFO. The intrinsic line width increases considerably at voltages above the boundary voltage because of the abrupt increase of the internal damping due to Josephson self-coupling. The influence of FFO parameters, in particular the differential resistances associated both with the bias current and with the applied magnetic field on the radiation line width, has been studied. Possible means of decreasing the free-running FFO line width will be discussed.

Mygind, Jesper

2002-01-01

 
 
 
 
261

Alliances and Bisection Width for Planar Graphs  

DEFF Research Database (Denmark)

An alliance in a graph is a set of vertices (allies) such that each vertex in the alliance has at least as many allies (counting the vertex itself) as non-allies in its neighborhood of the graph. We show that any planar graph with minimum degree at least 4 can be split into two alliances in polynomial time. We base this on a proof of an upper bound of n on the bisection width for 4-connected planar graphs with an odd number of vertices. This improves a recently published n?+?1 upper bound on the bisection width of planar graphs without separating triangles and supports the folklore conjecture that a general upper bound of n exists for the bisection width of planar graphs.

Olsen, Martin; Revsbæk, Morten

2013-01-01

262

Effect of stimulus width on simultaneous contrast  

Directory of Open Access Journals (Sweden)

Full Text Available Perceived brightness of a stimulus depends on the background against which the stimulus is set, a phenomenon known as simultaneous contrast. For instance, the same gray stimulus can look light against a black background or dark against a white background. Here we quantified the perceptual strength of simultaneous contrast as a function of stimulus width. Previous studies have reported that wider stimuli result in weaker simultaneous contrast, whereas narrower stimuli result in stronger simultaneous contrast. However, no previous research has quantified this relationship. Our results show a logarithmic relationship between stimulus width and perceived brightness. This relationship is well matched by the normalized output of a Difference-of-Gaussians (DOG filter applied to stimuli of varied widths.

Veronica Shi

2013-09-01

263

Constraints on widths of mixed pentaquark multiplets  

CERN Document Server

We determine constraints on the partial widths of mixed pentaquark multiplets in the framework of heavy baryon chiral perturbation theory (HB$\\chi$PT). The partial widths satisfy a GMO-type relation at leading order in HB$\\chi$PT, for arbitrary mixing. The widths of N(1440), N(1710), and $\\Theta(1540)$ are not consistent with ideal mixing, $\\theta_{N} = 35.3^{\\circ}$, but are consistent with $\\theta_{N} \\lesssim 25^{\\circ}$. Furthermore, there are parameter values in HB$\\chi$PT that produce such a mixing angle while allowing the identification of the mass spectrum above. As an alternative to non-ideal mixing, we also suggest reasons for giving up on N(1440) as a pure pentaquark state.

Mohta, V

2004-01-01

264

High Fin Width Mosfet Using Gaa Structure  

Directory of Open Access Journals (Sweden)

Full Text Available This paper describes the design and optimization of gate-all-around (GAA MOSFETs structures. The optimum value of Fin width and Fin height are investigated for superior subthreshold behavior. Also the performance of Fin shaped GAA with gate oxide HfO2 are simulated and compared with conventional gate oxide SiO2 for the same structure. As a result, it was observed that the GAA with high K dielectric gate oxide has more possibility to optimize the Fin width with improved performance. All the simulations are performed on 3-D TCAD device simulator.

S.L.Tripathi

2012-11-01

265

The Gromov width of complex Grassmannians  

CERN Document Server

We show that the Gromov width of the Grassmannian of complex k-planes in C^n is equal to one when the symplectic form is normalized so that it generates the integral cohomology in degree 2. We deduce the lower bound from more general results. For example, if a compact manifold N with an integral symplectic form \\omega admits a Hamiltonian circle action with a fixed point p such that all the isotropy weights at p are equal to one, then the Gromov width of (N,\\omega) is at least one. We use holomorphic techniques to prove the upper bound.

Karshon, Yu; Karshon, Yael; Tolman, Susan

2004-01-01

266

Fixed-Width Group CSD Multiplier Design  

Science.gov (United States)

This paper presents an error compensation method for fixed-width group canonic signed digit (GCSD) multipliers that receive a W-bit input and generate a W-bit product. To efficiently compensate for the truncation error, the encoded signals from the GCSD multiplier are used for the generation of the error compensation bias. By Synopsys simulations, it is shown that the proposed method leads to up to 84% reduction in power consumption and up to 78% reduction in area compared with the fixed-width modified Booth multipliers.

Kim, Yong-Eun; Cho, Kyung-Ju; Chung, Jin-Gyun; Huang, Xinming

267

Rad equivalence for photoactivated furocoumarins  

International Nuclear Information System (INIS)

The results allow a definition of the parameters needed for an eventual calculation of a RAD EQUIVALENCE. It was seen that the different factors which can influence the calculation can be in part determined exactly (for example, dependence on drug concentration, calculation on different survival levels), other factors (for example, the interrelationship between the RAD EQUIVALENCE for survival and the RAD EQUIVALENCE for mutational events) can probably be determined expirically. In the case of the furocoumarins biochemical experiments look rather promising which relate the RAD EQUIVALENCE to a defined number of lesions induced in the DNA and to their repair

268

Logic Petri Nets and Equivalency  

Directory of Open Access Journals (Sweden)

Full Text Available Logic Petri nets (LPN can describe and analyze batch processing function and passing value indeterminacy in cooperative systems and its practical applications are shown with some nontrivial examples. This study focuses on the analysis of the modeling power of LPNs and the equivalency between LPNs and Petri nets with inhibitor arcs (IPN. The equivalency is proved formally and a constructing algorithm of equivalent IPNs from LPNs is proposed based on the disjunctive normal forms of logic input/output expressions. Moreover, the size of an LPN model is smaller than that of the equivalent IPN model.

Y.Y. Du

2009-01-01

269

Estimating equivalence with quantile regression.  

Science.gov (United States)

Equivalence testing and corresponding confidence interval estimates are used to provide more enlightened statistical statements about parameter estimates by relating them to intervals of effect sizes deemed to be of scientific or practical importance rather than just to an effect size of zero. Equivalence tests and confidence interval estimates are based on a null hypothesis that a parameter estimate is either outside (inequivalence hypothesis) or inside (equivalence hypothesis) an equivalence region, depending on the question of interest and assignment of risk. The former approach, often referred to as bioequivalence testing, is often used in regulatory settings because it reverses the burden of proof compared to a standard test of significance, following a precautionary principle for environmental protection. Unfortunately, many applications of equivalence testing focus on establishing average equivalence by estimating differences in means of distributions that do not have homogeneous variances. I discuss how to compare equivalence across quantiles of distributions using confidence intervals on quantile regression estimates that detect differences in heterogeneous distributions missed by focusing on means. I used one-tailed confidence intervals based on inequivalence hypotheses in a two-group treatment-control design for estimating bioequivalence of arsenic concentrations in soils at an old ammunition testing site and bioequivalence of vegetation biomass at a reclaimed mining site. Two-tailed confidence intervals based both on inequivalence and equivalence hypotheses were used to examine quantile equivalence for negligible trends over time for a continuous exponential model of amphibian abundance. PMID:21516905

Cade, Brian S

2011-01-01

270

Bounding the Higgs boson width through interferometry.  

Science.gov (United States)

We study the change in the diphoton-invariant-mass distribution for Higgs boson decays to two photons, due to interference between the Higgs resonance in gluon fusion and the continuum background amplitude for gg???. Previously, the apparent Higgs mass was found to shift by around 100 MeV in the standard model in the leading-order approximation, which may potentially be experimentally observable. We compute the next-to-leading-order QCD corrections to the apparent mass shift, which reduce it by about 40%. The apparent mass shift may provide a way to measure, or at least bound, the Higgs boson width at the Large Hadron Collider through "interferometry." We investigate how the shift depends on the Higgs width, in a model that maintains constant Higgs boson signal yields. At Higgs widths above 30 MeV, the mass shift is over 200 MeV and increases with the square root of the width. The apparent mass shift could be measured by comparing with the ZZ* channel, where the shift is much smaller. It might be possible to measure the shift more accurately by exploiting its strong dependence on the Higgs transverse momentum. PMID:24074073

Dixon, Lance J; Li, Ye

2013-09-13

271

Theoretical determination of etab's electromagnetic decay width  

CERN Document Server

We discuss the theoretical predictions for the two photon decay width of the pseudoscalar etab meson. Predictions from potential models are examined. It is found that various models are in good agreement with each other. Results for etab are also compared with those from Upsilon data through the NRQCD procedure.

Fabiano, N

2003-01-01

272

A Window Width Optimized S-Transform  

Directory of Open Access Journals (Sweden)

Full Text Available Energy concentration of the S-transform in the time-frequency domain has been addressed in this paper by optimizing the width of the window function used. A new scheme is developed and referred to as a window width optimized S-transform. Two optimization schemes have been proposed, one for a constant window width, the other for time-varying window width. The former is intended for signals with constant or slowly varying frequencies, while the latter can deal with signals with fast changing frequency components. The proposed scheme has been evaluated using a set of test signals. The results have indicated that the new scheme can provide much improved energy concentration in the time-frequency domain in comparison with the standard S-transform. It is also shown using the test signals that the proposed scheme can lead to higher energy concentration in comparison with other standard linear techniques, such as short-time Fourier transform and its adaptive forms. Finally, the method has been demonstrated on engine knock signal analysis to show its effectiveness.

Jin Jiang

2008-02-01

273

Bounding the Higgs Boson Width Through Interferometry  

CERN Document Server

We study the change in the di-photon invariant mass distribution for Higgs boson decays to two photons, due to interference between the Higgs resonance in gluon fusion and the continuum background amplitude for gluon pair to photon pair. Previously, the apparent Higgs mass was found to shift by around 100 MeV in the Standard Model in the leading order approximation, which may potentially be experimentally observable. We compute the next-to-leading order QCD corrections to the apparent mass shift, which reduce it by about 40%. The apparent mass shift may provide a way to measure, or at least bound, the Higgs boson width at the Large Hadron Collider through "interferometry". We investigate how the shift depends on the Higgs width, in a model that maintains constant Higgs boson signal yields. At Higgs widths above 30 MeV the mass shift is over 200 MeV and increases almost linearly with the width. The apparent mass shift could be measured by comparing with the ZZ* channel, where the shift should be much smaller. ...

Dixon, Lance J

2013-01-01

274

Morita Equivalence of Noncommutative Supertori  

CERN Document Server

In this paper we study an extension of the Morita equivalence of noncommutative tori to the supersymmetric case. We restrict our investigation mainly to the two dimensional case in which noncommutative supertori have been constructed recently. Our main focus is to know how the supersymmetry affect the symmetry relations giving the Morita equivalence in the bosonic noncommutative tori case. It turns out that the structure of the symmetry group acting on the noncommutativity parameters yielding the Morita equivalence remains intact but its field become supersymmetric having both body and soul parts. The extension of the Morita equivalence to the higher dimensional case could not be carried out due to lack of complete understanding of the classification and construction of all possible higher dimensional noncommutative supertori. However, even in the higher dimensional case there seems to be a certain indication that the structure of the symmetry group yielding Morita equivalence remains unchanged from the boson...

Chang-Young, Ee; Nakajima, Hiroaki

2009-01-01

275

Determination of the 190Po ? reduced width  

International Nuclear Information System (INIS)

The isotope 190Po was produced in the 144Sm(48Ti,2n) reaction and its ?-decay energy and half-life were measured to be 7.49(4) MeV and 2.0-1.0+0.5 ms, respectively. These data compare as follows with preliminary values reported by Quint et al.: E?=7482(20) keV and a T1/2=9.6-4.4+47 ms. While the two energies agree, the half-lives differ by a factor of almost 5. The earlier data yield an ? reduced width which is much smaller than those of neighboring nuclides; our 190Po energy and half-life result in a width that fits the overall ?-decay-rate systematics in the mass region above the Z=82 closed shell. copyright 1996 The American Physical Society

276

Two photon width of heavy pseudoscalar mesons  

CERN Document Server

We discuss the partial width of the pseudoscalar charmonium state eta_c and bottomonium state eta_b into two photons. Predictions from potential models are examined and compared with experimental values for the eta_c case. Through the NRQCD factorisation procedure results for eta_c are also compared with those from J/psi data, and results for eta_b to the Upsilon decay data.

Fabiano, N; Fabiano, Nicola; Pancheri, Giulia

2002-01-01

277

Two photon width of eta_c  

CERN Document Server

We discuss the measured partial width of the pseudoscalar charmonium state, $\\eta_c$, into two photons. Predictions from potential models are examined and compared with experimental values. Including radiative corrections, it is found that present measurements are compatible both with a QCD type potential and with a static Coulomb potential, with $\\alpha_s$ evaluated at two loops. Results are also compared with those from $\\jpsi$ data through the NRQCD model.

Fabiano, N; Fabiano, Nicola; Pancheri, Giulia

2002-01-01

278

LEP hadronic Z0 partial widths  

International Nuclear Information System (INIS)

The experimental situation on hadronic Z0 partial widths at LEP is reviewed. In the absence of recent results on light quarks, only new data concerning Z0 ? b b bar and Z0 ? cc bar are considered. A LEP average value of Rb (with a 1% precision) implying low top quark mass or new phenomena within the Standard Model framework is presented. A slight deviation of Rb from the Standard Model value is observed. 6 figs., 18 refs

279

The width of the colour flux tube  

International Nuclear Information System (INIS)

We discuss and rederive in a general way the logarithmic growth of the mean squared width of the colour flux tube as a function of the interquark separation. Recent data on 3D Z2 gauge theory, combined with high precision data on the interface physics of the 3D Ising model fit nicely this behaviour over a range of more than two orders of magnitude. ((orig.))

280

The width of the colour flux tube  

Energy Technology Data Exchange (ETDEWEB)

We discuss and rederive in a general way the logarithmic growth of the mean squared width of the colour flux tube as a function of the interquark separation. Recent data on 3D Z{sub 2} gauge theory, combined with high precision data on the interface physics of the 3D Ising model fit nicely this behaviour over a range of more than two orders of magnitude. ((orig.)).

Caselle, M. [Turin Univ. (Italy). Dipartimento di Fisica Teorica and INFN; Gliozzi, F. [Turin Univ. (Italy). Dipartimento di Fisica Teorica and INFN; Magnea, U. [State Univ. of New York, Stony Brook, NY (United States); Vinti, S. [Turin Univ. (Italy). Dipartimento di Fisica Teorica and INFN

1995-04-01

 
 
 
 
281

The width of the colour flux tube  

CERN Document Server

We discuss and rederive in a general way the logarithmic growth of the mean squared width of the colour flux tube as a function of the interquark separation. Recent data on 3D Z_2 gauge theory, combined with high precision data on the interface physics of the 3D Ising model fit nicely this behaviour over a range of more than two orders of magnitude.

Caselle, M; Magnea, U; Vinti, S; Caselle, M; Gliozzi, F; Magnea, U; Vinti, S

1994-01-01

282

Dynamics of niche width and resource partitioning.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This article examines the effects of crowding in a market center on rates of change in organizational niche width and on organizational mortality. It proposes that, although firms with wide niches benefit from risk spreading and economies of scale, they are simultaneously exposed to intense competition. An analysis of organizational dynamics in automobile manufacturing firms in France, Germany, and Great Britain shows that competitive pressure not only increases the hazard of disbanding but a...

Dobrev, S.; Kim, T-y; Hannan, M. T.

2001-01-01

283

Determination of the ?(1s) leptonic width  

International Nuclear Information System (INIS)

The data recorded with the MD-1 detector operated at the VEPP-4 storage ring were analyzed and the ?(1s) resonance leptonic partial width and mass are determined. ?ee=1.29+-0.03+-0.03 keV, M=9460.59+-0.09+-0.05 MeV/c2 are find. Thies new value of the ?(1s) nass should superside the previously published value. 26 refs.; 6 figs.; 1 tab

284

Vision-based weld pool width control  

Energy Technology Data Exchange (ETDEWEB)

Methods for controlling weld penetration for arc welding processes from top-side measurements have long been sought. One indirect variable that has been reported to correlate with penetration is weld pool geometry. A system which uses weld pool geometry sensing for controlling weld penetration is described in this paper. The system uses a miniature camera mounted in a modified coaxial viewing torch to view the weld pool. A robust machine vision algorithm has been developed for this system to measure weld pool width. The algorithm was designed to locate the edges of the weld pool despite the presence of other edges caused by the heat affected zone, scratches, marks, and weld pool impurities. The algorithm uses a matched edge filter and a majority voting scheme to measure the width of the pool. A control system was developed to regulate weld pool width in the presence of disturbances caused by such items as incorrect parameter settings, small variations in material composition, and material thickness changes. Experiments were conducted to test the control system by simulating some of these disturbances. The experiments demonstrated that for certain classes of materials, this technique works quite well. However, for other materials such as stainless steel 304, surface impurities in the weld pool visually obscure the weld pool and its edges to such a degree that the system fails to lock onto the edges of the pool.

Pietrzak, K.A.; Packer, S.M. (United Technologies Research Center, East Hartford, CT (United States))

1994-02-01

285

Meson widths from string worldsheet instantons  

CERN Document Server

We show that open strings living on a D-brane which lies outside an AdS black hole can tunnel into the black hole through worldsheet instantons. These instantons have a simple interpretation in terms of thermal quarks in the dual Yang-Mills (YM) theory. As an application we calculate the width of a meson in a strongly coupled quark-gluon plasma which is described holographically as a massless mode on a D7 brane in AdS_5 \\times S_5. While the width of the meson is zero to all orders in the 1/\\sqrt{\\lambda} expansion with \\lambda the 't Hooft coupling, it receives non-perturbative contributions in 1/\\sqrt{\\lambda} from worldsheet instantons. We find that the width increases quadratically with momentum at large momentum and comment on potential phenomenological implications of this enhancement for heavy ion collisions. We also comment on how this non-perturbative effect has important consequences for the phase structure of the YM theory obtained in the classical gravity limit.

Faulkner, Thomas

2008-01-01

286

Biologic Width - The No Encroachment Zone  

Directory of Open Access Journals (Sweden)

Full Text Available Dentistry of modern era is dominated by restorative procedures which are carried out to meet the demands of not only function but also esthetics. The dentist is having a narrow room of flexibility to wander in order to achieve a good esthetic restoration which is fully functional, the design of preparation and the technique sensitive fabrication form one side of the coin and establishing a harmonious margin for a crown on abutment forms the other side of the coin when trying to insert a fixed prosthetic restoration for replacing missing teeth, the phenomenon of biologic width was less understood till very recently but the growing clinical experience and better diagnostic skills of today has helped us to understand the intricacies of this concept and the need for its maintenance, the violation of which leads to the ultimate failure of the prosthesis. This article attempts to explain the ways of diagnosing biologic width violation, the care needed to exert when preparing a teeth to receive a crown and exactly deciding where to place the margins of the crown to avoid biologic width violation

Hari Krishna Reddy S

2010-12-01

287

Finite width effects in \\phi radiative decays  

CERN Document Server

The decay widths \\phi \\to \\gamma f_0(980) and \\phi \\to \\gamma a_0(980) are calculated taking into account the finite widths of the scalar resonances f_0(980) and a_0(980). The latter are shown to be essential in order to obtain meaningful results. Simultaneously we also study the decays \\phi\\to \\gamma \\pi^0\\pi^0 and \\gamma \\pi^0\\eta where a good reproduction of the recent experimental data is obtained, pointing out the necessity of a \\phi\\gamma K^0\\bar{K}^0 contact vertex. The calculated decay rates to \\gamma f_0(980) and \\gamma a_0(980) are in good agreement with the experimental ones without invoking isospin breaking in the couplings of the f_0(980) and a_0(980) resonances to the K^+ K^- and K^0 \\bar{K}^0 channels, at odds with recent proposals. The derived formula for calculating these \\phi radiative decay widths can be also applied in their own experimental analyses in order to obtain more precise results.

Oller, J A

2003-01-01

288

Morita equivalence of noncommutative supertori  

International Nuclear Information System (INIS)

In this paper we study the extension of Morita equivalence of noncommutative tori to the supersymmetric case. The structure of the symmetry group yielding Morita equivalence appears to be intact but its parameter field becomes supersymmetrized having both body and soul parts. Our result is mainly in the two dimensional case in which noncommutative supertori have been constructed recently: The group SO(2,2,VZ0), where VZ0 denotes Grassmann even number whose body part belongs to Z, yields Morita equivalent noncommutative supertori in two dimensions.

289

Width and partial widths of unstable particles in the light of the Nielsen identities  

International Nuclear Information System (INIS)

Fundamental properties of unstable particles, including mass, width, and partial widths, are examined on the basis of the Nielsen identities (NI) that describe the gauge dependence of Green functions. In particular, we prove that the pole residues and associated definitions of branching ratios and partial widths are gauge independent to all orders. A simpler, previously discussed definition of branching ratios and partial widths is found to be gauge independent through next-to-next-to-leading order. It is then explained how it may be modified in order to extend the gauge independence to all orders. We also show that the physical scattering amplitude is the most general combination of self-energy, vertex, and box contributions that is gauge independent for arbitrary s, discuss the analytical properties of the NI functions, and exhibit explicitly their one-loop expressions in the Z-? sector of the standard model

290

Tissue Engineered Human Skin Equivalents  

Directory of Open Access Journals (Sweden)

Full Text Available Human skin not only serves as an important barrier against the penetration of exogenous substances into the body, but also provides a potential avenue for the transport of functional active drugs/reagents/ingredients into the skin (topical delivery and/or the body (transdermal delivery. In the past three decades, research and development in human skin equivalents have advanced in parallel with those in tissue engineering and regenerative medicine. The human skin equivalents are used commercially as clinical skin substitutes and as models for permeation and toxicity screening. Several academic laboratories have developed their own human skin equivalent models and applied these models for studying skin permeation, corrosivity and irritation, compound toxicity, biochemistry, metabolism and cellular pharmacology. Various aspects of the state of the art of human skin equivalents are reviewed and discussed.

Zheng Zhang

2012-01-01

291

Artifacts for Calibration of Submicron Width Measurements  

Science.gov (United States)

Artifacts that are fabricated with the help of molecular-beam epitaxy (MBE) are undergoing development for use as dimensional calibration standards with submicron widths. Such standards are needed for calibrating instruments (principally, scanning electron microscopes and scanning probe microscopes) for measuring the widths of features in advanced integrated circuits. Dimensional calibration standards fabricated by an older process that involves lithography and etching of trenches in (110) surfaces of single-crystal silicon are generally reproducible to within dimensional tolerances of about 15 nm. It is anticipated that when the artifacts of the present type are fully developed, their critical dimensions will be reproducible to within 1 nm. These artifacts are expected to find increasing use in the semiconductor-device and integrated- circuit industries as the width tolerances on semiconductor devices shrink to a few nanometers during the next few years. Unlike in the older process, one does not rely on lithography and etching to define the critical dimensions. Instead, one relies on the inherent smoothness and flatness of MBE layers deposited under controlled conditions and defines the critical dimensions as the thicknesses of such layers. An artifact of the present type is fabricated in two stages (see figure): In the first stage, a multilayer epitaxial wafer is grown on a very flat substrate. In the second stage, the wafer is cleaved to expose the layers, then the exposed layers are differentially etched (taking advantage of large differences between the etch rates of the different epitaxial layer materials). The resulting structure includes narrow and well-defined trenches and a shelf with thicknesses determined by the thicknesses of the epitaxial layers from which they were etched. Eventually, it should be possible to add a third fabrication stage in which durable, electronically inert artifacts could be replicated in diamondlike carbon from a master made by MBE and etching as described above.

Grunthaner, Frank; Grunthaner, Paula; Bryson, Charles, III

2003-01-01

292

Radiative decay widths of the ?*(1520) resonance  

International Nuclear Information System (INIS)

In order to study the quark wave functions of the baryon spectra, the study of the radiative decay of the narrowest S = -1 state, the ?*(1520), Jsup(?)=3/2-, GAMMA = 15.6+-1 MeV, has been undertaken. This resonance was excited through the K- + p reaction, and the transitions are the ?(1520) ? ?(1116) and ?(1520) ? ?0(1193). The authors find for the first transition a radiative width inferior to 30 keV, result in disagreement with a value reported in an other reference. Experiences are still in progress

293

Statistical analysis of partial reduced width distributions  

International Nuclear Information System (INIS)

The aim of this study was to develop rigorous methods for analysing experimental event distributions according to a law in chi2 and to check if the number of degrees of freedom ? is compatible with the value 1 for the reduced neutron width distribution. Two statistical methods were used (the maximum-likelihood method and the method of moments); it was shown, in a few particular cases, that ? is compatible with 1. The difference between ? and 1, if it exists, should not exceed 3%. These results confirm the validity of the compound nucleus model

294

Aptitude test and classification of materials with class width of statistically evaluated distinction  

International Nuclear Information System (INIS)

Classification into classes of statistically evaluated distinction is an appropriate means of assigning various materials properties simply and quickly into the relevant groups of being equivalent or different. This information, however, is subject to statistical uncertainties due to the relatively small number of samples used for materials properties testing; the large variety of materials properties modify the information on possible differences. One factor to be taken into account in determining the class width is a sufficient probability by which a difference between two materials properties can be stated when the average sample data are differing by one or more class widths. For this case, formulas for determining the required class widths, derived by a test well-known in statistical mathematics, are presented in this paper and described by numerical examples. (orig./RW)

295

Using tissue equivalent proportional counters to determine dose equivalent  

International Nuclear Information System (INIS)

Tissue equivalent proportional counters (TEPCs) have been used in the laboratory for over 30 years to determine neutron dose in mixed radiation fields, but they are seldom used by operational health physicists. But a number of TEPC-based instruments are being developed in Europe and in the United States. The purpose of this paper is: to introduce operational health physicists to tissue equivalent proportional counters, to examine some of the algorithms used to convert data from TEPCs into dose equivalent, to examine how TEPC measurements meet the requirements of DOE Order 5480.11 (DOE 1988) and 10CFR20, and to examine some of the TEPC-based instruments that are available. Many operational health physicists are not familiar with the concept of microdosimetry and the specialized terms that are used in analyzing the data from TEPCs, so a brief discussion is included. At present, quality factors are defined in terms of linear energy transfer, but TEPCs measure lineal energy

296

Exploiting the width difference in Bs???  

International Nuclear Information System (INIS)

The photon polarization in B?V? is a sensitive probe of right-handed currents. In the time dependent decay rate of Bs??? the coefficients S and H in front of the sin(?mst) and the sinh(??s/2t) terms are sensitive to those right-handed currents. As compared to the Bd system there is a sizable width difference in Bs mesons which leads to the additional measurable observable H. We show with a Monte Carlo simulation that the expected resolution on S and H will be about 0.15 at the LHCb experiment for ??s/?s=0.15 and a data sample of 2 fb-1. We also show that the observable H can be measured from the untagged decay rate of Bs mesons which has considerable experimental advantages as no flavour tag will be required. The resolution on H is inversely proportional to the Bs width difference ??s. These experimental prospects have to be compared with the Standard Model predictions S??=0±0.002 and H??=0.047±0.025+0.015 presented in this Letter. We also give the Standard Model prediction and the experimental sensitivity for the direct CP asymmetry in Bs???

297

Symmetries of dynamically equivalent theories  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english A natural and very important development of constrained system theory is a detail study of the relation between the constraint structure in the Hamiltonian formulation with specific features of the theory in the Lagrangian formulation, especially the relation between the constraint structure with th [...] e symmetries of the Lagrangian action. An important preliminary step in this direction is a strict demonstration, and this is the aim of the present article, that the symmetry structures of the Hamiltonian action and of the Lagrangian action are the same. This proved, it is sufficient to consider the symmetry structure of the Hamiltonian action. The latter problem is, in some sense, simpler because the Hamiltonian action is a first-order action. At the same time, the study of the symmetry of the Hamiltonian action naturally involves Hamiltonian constraints as basic objects. One can see that the Lagrangian and Hamiltonian actions are dynamically equivalent. This is why, in the present article, we consider from the very beginning a more general problem: how the symmetry structures of dynamically equivalent actions are related. First, we present some necessary notions and relations concerning infinitesimal symmetries in general, as well as a strict definition of dynamically equivalent actions. Finally, we demonstrate that there exists an isomorphism between classes of equivalent symmetries of dynamically equivalent actions.

D. M., Gitman; I. V., Tyutin.

298

EQUIVALENCE VERSUS NON-EQUIVALENCE IN ECONOMIC TRANSLATION  

Directory of Open Access Journals (Sweden)

Full Text Available This paper aims at highlighting the fact that “equivalence” represents a concept worth revisiting and detailing upon when tackling the translation process of economic texts both from English into Romanian and from Romanian into English. Far from being exhaustive, our analysis will focus upon the problems arising from the lack of equivalence at the word level. Consequently, relevant examples from the economic field will be provided to account for the following types of non-equivalence at word level: culturespecific concepts; the source language concept is not lexicalised in the target language; the source language word is semantically complex; differences in physical and interpersonal perspective; differences in expressive meaning; differences in form; differences in frequency and purpose of using specific forms and the use of loan words in the source text. Likewise, we shall illustrate a number of translation strategies necessary to deal with the afore-mentioned cases of non-equivalence: translation by a more general word (superordinate; translation by a more neutral/less expressive word; translation by cultural substitution; translation using a loan word or loan word plus explanation; translation by paraphrase using a related word; translation by paraphrase using unrelated words; translation by omission and translation by illustration.

Cristina, Chifane

2012-01-01

299

From equivalent weighting functions to equivalent contraction kernels  

Science.gov (United States)

Burt introduced 1983 'equivalent weighting function': 'Iterative pyramid generation is equivalent to convolving the image g0 with a set of 'equivalent weighting functions' hl' gl equals hl * g0 equals h * gl-1, l > 1. It allowed him to study the effects of iterated reduction using the single parameter hl without giving up the efficient iterative computation. A similar concept applies to graph pyramids built by dual graph contraction. This new algorithm reduces the number of vertices and of edges of a pair of dual image graphs while, at he same time, the topological relations among the 'surviving' components are preserved. Repeated application produces a stack of successively smaller graphs: a pari of dual irregular pyramids. The process is controlled by selected decimation parameters which consist of a subset of surviving vertices and associated contraction kernels. These pay a similar role for graph pyramids than the convolution kernels of Gaussian pyramids. Equivalent contraction kernels combine two or more contraction kernels int one single dual contraction. The basic concepts are elaborated and discussed. The new theory opens a large variety of possibilities to explore the domain of 'all' graph pyramids.

Kropatsch, Walter G.

1998-02-01

300

Equivalent linearization of nonlinear forces  

Science.gov (United States)

A method used for equivalent linearization of the two orthogonal squeeze-film forces is extended here to the general case of n degrees of freedom and n components of nonlinear forces, and the expressions for equivalent linear coefficients are derived. Nonlinear forces can be linearized by the methods of Fourier expansion, active and reactive powers, or mean-square error. The n components of nonlinear forces can all be expressed formally as the sum of an average force, a linear spring force, and a linear damping force. This paper also gives a flow chart for calculating the steady-state responses of a nonlinear system with many degrees of freedom, using the method of equivalent linearization. The resulting saving in computation time is demonstrated by a numerical example of a flexible rotor-bearing system with a noncentralized squeeze-film damper.

Meng, Guang; Xue, Zhongqing

1987-07-01

 
 
 
 
301

REI EQUIVALENTS WITH SYNCHROPHASOR MEASUREMENTS  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a new static network equivalencing technique that take in to consideration the influence of changes occurring in the reduced system based on voltage phasor measurements from this system. The method was developed around the REI equivalent, but in principle it can be used with any other equivalencing technique. Numerical simulations have shown that real-time measurements provided by PMUs installed on the buses of the external system can considerably improve simulation results produced by traditional REI equivalents for the operating conditions in the internal, obser ved power system.

Mihai Gavrilas

2009-11-01

302

Characterizing Width Uniformity by Wave Propagation  

CERN Document Server

This work describes a novel image analysis approach to characterize the uniformity of objects in agglomerates by using the propagation of normal wavefronts. The problem of width uniformity is discussed and its importance for the characterization of composite structures normally found in physics and biology highlighted. The methodology involves identifying each cluster (i.e. connected component) of interest, which can correspond to objects or voids, and estimating the respective medial axes by using a recently proposed wavefront propagation approach, which is briefly reviewed. The distance values along such axes are identified and their mean and standard deviation values obtained. As illustrated with respect to synthetic and real objects (in vitro cultures of neuronal cells), the combined use of these two features provide a powerful description of the uniformity of the separation between the objects, presenting potential for several applications in material sciences and biology.

Costa, L F; Schubert, D; Costa, Luciano da F.; Mutinari, Giancarlo; Schubert, David

2003-01-01

303

Characterizing width uniformity by wave propagation  

Science.gov (United States)

This work describes a different image analysis approach to characterize the uniformity of objects in agglomerates by using the propagation of normal wave fronts. The problem of width uniformity is discussed and its importance for the characterization of composite structures normally found in physics and biology highlighted. The methodology involves identifying each cluster (i.e., connected component) of interest, which can correspond to objects or voids, and estimating the respective medial axes by using a recently proposed wave front propagation approach, which is briefly reviewed. The distance values along such axes are identified and their mean and standard deviation values obtained. As illustrated with respect to synthetic and real objects (in vitro cultures of neuronal cells), the combined use of these two features provides a powerful description of the uniformity of the separation between the objects, presenting potential for several applications in material sciences and biology.

Costa, Luciano Da; Mutinari, Giancarlo; Schubert, David

2003-11-01

304

Direct measurement of the W boson width  

Energy Technology Data Exchange (ETDEWEB)

We present a direct measurement of the width of the W boson using the shape of the transverse mass distribution of W {yields} e{nu} candidates selected in 1 fb{sup -1} of data collected with the D0 detector at the Fermilab Tevatron collider in p{bar p} collisions at {radical}s = 1.96 TeV. We use the same methods and data sample that were used for our recently published W boson mass measurement, except for the modeling of the recoil, which is done with a new method based on a recoil library. Our result, 2.028 {+-} 0.072 GeV, is in agreement with the predictions of the standard model and is the most precise direct measurement result from a single experiment to date.

Abazov, V.M.; /Dubna, JINR; Abbott, B.; /Oklahoma U.; Abolins, M.; /Michigan State U.; Acharya, B.S.; /Tata Inst.; Adams, M.; /Illinois U., Chicago; Adams, T.; /Florida State U.; Aguilo, E.; /Alberta U. /Simon Fraser U. /McGill U.; Ahsan, M.; /Kansas State U.; Alexeev, G.D.; /Dubna, JINR; Alkhazov, G.; /St. Petersburg, INP; Alton, A.; /Michigan U. /Northeastern U.

2009-09-01

305

A high spatial resolution X-ray and H-alpha study of hot gas in the halos of star-forming disk galaxies. I. Spatial and spectral properties of the diffuse X-ray emission  

CERN Document Server

We present arcsecond resolution Chandra X-ray and ground-based optical H-alpha imaging of a sample of ten edge-on star-forming disk galaxies (seven starburst and three ``normal'' spiral galaxies), a sample which covers the full range of star-formation intensity found in disk galaxies. We use the unprecedented spatial resolution of the Chandra X-ray observatory to robustly remove point sources, and hence obtain the X-ray properties of the diffuse thermal emission alone. The X-ray observations are combined with comparable-resolution H-alpha and R-band imaging, and presented as a mini-atlas of images on a common spatial and surface brightness scale. The vertical distribution of the halo-region X-ray surface brightness is best described as an exponential, with the observed scale heights lying in the range H_eff = 2 -- 4 kpc. The ACIS X-ray spectra of extra-planar emission from all these galaxies can be fit with a common two-temperature spectral model with an enhanced alpha-to-iron element ratio. This is consisten...

Strickland, D K; Colbert, E J M; Hoopes, C G; Weaver, K A

2003-01-01

306

Joint H-alpha and X-ray Observations of Massive X-ray Binaries. I. The B-Supergiant System LS I +65 010 = 2S 0114+650  

CERN Document Server

We report on a three year spectroscopic monitoring program of the H-alpha emission in the massive X-ray binary LS I +65 010 = 2S 0114+650, which consists of a B-supergiant and a slowly rotating X-ray pulsar. We present revised orbital elements that yield a period of P=11.5983 +/- 0.0006 d and confirm that the orbit has a non-zero eccentricity e=0.18 +/- 0.05. The H-alpha emission profile is formed in the base of the wind of the B-supergiant primary, and we show how this spectral feature varies on timescales that are probably related to the rotational period of the B-supergiant. We also examine the X-ray fluxes from the Rossi X-ray Timing Explorer All-Sky Monitor instrument, and we show that the X-ray orbital light curve has a maximum at periastron and a minimum at the inferior conjunction of the B-supergiant. We also show that the wind emission strength and the high energy X-ray flux appear to vary in tandem on timescales of approximately a year.

Grundstrom, E D; Gies, D R; Huang, W; McSwain, M V; Raghavan, D; Riddle, R L; Subasavage, J P; Wingert, D W; Levine, A M; Remillard, R A

2006-01-01

307

Complex Variability of the H$\\alpha$ Emission Line Profile of the T Tauri Binary System KH 15D: The Influence of Orbital Phase, Occultation by the Circumbinary Disk, and Accretion Phenomenae  

CERN Document Server

We have obtained 48 high resolution echelle spectra of the pre-main sequence eclipsing binary system KH~15D (V582 Mon, P = 48.37 d, $e$ $\\sim$ 0.6, M$_{A}$ = 0.6 M$_{\\odot}$, M$_{B}$ = 0.7 M$_{\\odot}$). The eclipses are caused by a circumbinary disk seen nearly edge on, which at the epoch of these observations completely obscured the orbit of star B and a large portion of the orbit of star A. The spectra were obtained over five contiguous observing seasons from 2001/2002 to 2005/2006 while star A was fully visible, fully occulted, and during several ingress and egress events. The H$\\alpha$ line profile shows dramatic changes in these time series data over timescales ranging from days to years. A fraction of the variations are due to "edge effects" and depend only on the height of star A above or below the razor sharp edge of the occulting disk. Other observed variations depend on the orbital phase: the H$\\alpha$ emission line profile changes from an inverse P Cygni type profile during ingress to an enhanced d...

Hamilton, Catrina M; Mundt, Reinhard; Herbst, William; Winn, Joshua N

2012-01-01

308

Research on Fairway Width Based on the Statistical Theory  

Directory of Open Access Journals (Sweden)

Full Text Available The fairway with certain width is one of prerequisite for ship’s safety navigation. Channel’s width is closely linked to ship’s safety navigation. It is essential to research channel’s width. The relationship between fairway’s width and marine accident is analyzed in the present study and mathematical model of fairway’s width is also put forward based on statistical theory in this study. Analysis shows that the fairway’s width mathematical model put forward in this study can provide good guide for fairway’s maintenance.

Ding Tian-Ming

2013-01-01

309

Line-width compression of the distributed feedback laser with an external parallel feedback cavity  

Science.gov (United States)

The distributed feedback laser (DFB) is a typical laser diode where the active region of the device is periodically structured as a diffraction grating. The output of a DFB laser has one single longitudinal mode and a relatively narrow line-width, usually several megahertz or one order less. However, applications such as coherent optical communication and accurate fiber sensing demand an even narrower line-width. An effective method for compressing a DFB laser is demonstrated. The line-width of a DFB laser, 200 KHz detected originally, is suppressed to sub kilohertz by adding an external parallel feedback cavity. The DFB laser is normatively designed but without the output isolator. The parallel feedback cavity is constructed by inserting several pieces of multimode fiber into a standard linear single-mode fiber cavity. In multimode fiber, each transverse mode has a different propagation constant. Equivalently, when a light beam propagates from single mode fiber to multimode fiber, it will split into a few parallel light paths with different propagation constants. The external cavity and DFB cavity form a compound resonant cavity for light beams. Lasing light in the compound cavity must fit the restrictions of all light paths, thus line-width of the final output is suppressed. When a passive external cavity is used, the line-width is suppressed to 1.25 KHz, detected by a delayed self-heterodyne interferometer with a 100km fiber delay line. By adding an erbium doped fiber amplifier (EDFA) into the external cavity for loss compensation, the result is updated to 430 Hz. This line-width suppressing method can be applied for other types of fiber lasers in a similar way. The parallel feedback mechanism is also suggested for general laser cavity designing to achieve ultra narrow line-width light source.

Wang, Zi-nan; Wang, Cui-yun; Wang, Da-liang; Lu, Ping; Yu, Xiao-qi; Xu, Lian-yu; Yang, Yi; Jiang, Yun; Zhu, Li-xin; Li, Zheng-bin

2011-06-01

310

Therapeutic equivalence of mesalamine products.  

Science.gov (United States)

No bioequivalence studies have been conducted for mesalamine because of differences in formulation. Based on U.S. Food and Drug Administration definitions for bioequivalence, none of these drugs can be classified as bioequivalent or therapeutically equivalent. No adequate comparative trials have been conducted with equivalent mesalamine doses to determine if any of the current formulations are superior in the treatment of ulcerative colitis. All of these mesalamine formulations are effective, but they differ with regard to where the drug is released in the intestinal tract, which may influence the outcome in some patients. Therefore, the selection of a mesalamine agent should be based on the results of the clinical trials, individual patient response, compliance issues, and price, until comparative clinical trials are published. PMID:15029108

Baker, Danial E

2004-01-01

311

Foxby equivalence over associative rings  

CERN Document Server

We extend the definition of a semidualizing module to associative rings. This enables us to define and study Auslander and Bass classes with respect to a semidualizing bimodule C. We then study the classes of C-flats, C-projectives, and C-injectives, and use them to provide a characterization of the modules in the Auslander and Bass classes. We extend Foxby equivalence to this new setting. This paper contains a few results which are new in the commutative, noetherian setting.

Holm, H; Holm, Henrik; White, Diana

2006-01-01

312

On equivalence of graded rings  

Directory of Open Access Journals (Sweden)

Full Text Available Let R=⊕g∈GRg be a G-graded ring. In this paper we define the ? ? homogeneousequivalence” concept between graded rings. We discuss some properties of the G-graded rings and investigate which of these are preserved under homogeneous-equivalence maps. Furthermore, we give some results in graded ring theory and also some applications of this concept to Z-graded rings.

Sofyan Obiedat

1998-03-01

313

Charge conservation and Equivalence principle  

CERN Document Server

The $TH\\epsilon\\mu$ formalism was developed to study nonmetric theories of gravitation. In this letter we show that theories that violate Local Lorentz Invariance (LLI) or Local Position Invariance (LPI) also violate charge conservation. Using upper bounds on this violation we can put very stringent limits to violations of Einstein Equivalence Principle (EEP). These limits, in turn, severely restrict string-based models of low energy physics.

Landau, S J; Vucetich, H; Landau, Susana J.; Sisterna, Pablo D.; Vucetich, Hector

2001-01-01

314

Changing step width alters lower extremity biomechanics during running.  

Science.gov (United States)

Step width is a spatiotemporal parameter that may influence lower extremity biomechanics at the hip and knee joint. The purpose of this study was to determine the biomechanical response of the lower extremity joints to step width changes during running. Lower extremity data from 30 healthy runners, half of them male, were collected during running in three step width conditions: preferred, wide, and narrow. Dependent variables and step width were analyzed using a mixed model ANOVA and pairwise t-tests for post hoc comparisons. Step width was successfully altered in the wide and narrow conditions. Generally, frontal plane peak values decreased as step width increased from narrow to preferred to wide. Peak hip adduction and rearfoot eversion angles decreased as step width increased from narrow to wide. Peak knee abduction moment and knee abduction impulse also decreased as step width increased from narrow to wide. Although men and women ran differently, gender only influenced the effect of step width on peak rearfoot inversion moment. In conclusion, step width influences lower extremity biomechanics in healthy runners. When step width increased from narrow to wide, peak values of frontal plane variables decreased. In addition to previously reported changes at the rearfoot, the hip and knee joint biomechanics were also influenced by changes in step width. PMID:23831430

Brindle, Richard A; Milner, Clare E; Zhang, Songning; Fitzhugh, Eugene C

2014-01-01

315

Correlation between Line Width and Line Flux of Double-Peaked Broad Halpha of 3C390.3  

CERN Document Server

In this manuscript, we carefully check the correlation between the line width and the line flux of the double-peaked broad H$\\alpha$ of the well-known mapped AGN 3C390.3, in order to show some further distinctions between double-peaked emitters and normal broad line AGN. Based on the Virialization assumption and the empirical relation about $R_{BLR}$, one strong negative correlation of line parameters of the double-peaked broad lines should be expected for 3C390.3, such as the negative correlation confirmed for the mapped broad line object NGC5548. But, based on the public spectra around 1995 from the AGNWATCH project for 3C390.3, one reliable positive correlation is found. In the context of the proposed theoretical accretion disk model for double-peaked emitters, the unexpected positive correlation can be naturally explained, due to different time delays for inner parts and outer parts of disk-like BLR of 3C390.3. Moreover, the Virialization assumption is checked and found to be still available for 3C390.3. ...

Zhang, XueGuang

2012-01-01

316

?onsolidation and creepof subfoundations having finite widths ???????????? ? ?????????? ????????? ??????????? ???????? ??????  

Directory of Open Access Journals (Sweden)

Full Text Available The authors formulate and solve the problem of consolidation and creep of saturated clay subfoundations exposed to localized loads (the two-dimensional problem formulation. The findings have proven that, if the two-dimensional problem is considered, any excessive pore pressure is concentrated immediately under the area exposed to the localized loading, and it penetrates into the depth equal to 1/2 of the strength of the compressed width. Subfoundation subsidence is caused by both shear and 3D deformations of soil. Besides, the ratio of shear-to-3D deformations reaches 10. Therefore, the authors propose to represent the subfoundation subsidence as the sum of shear and 3D deformations.The differential equation of the filter consolidation, if considered as the 2D problem, is solved using the Mathcad software. The software is used to analyze the isolines of excessive pore pressure at any moment following the loading application. New depen- dence representing the ratio of the changing area of the diagram of the average effective tension to the area of the diagram of the average tension in the stabilized condition is proposed by the authors.In the final section of the article, the authors solve the problem of prognostication of the subsidence pattern for the water saturated subfoundation with account for the shear creep of the soil skeleton. The authors employ the visco-elastic Bingham model characterized by time-dependent viscosity ratios. The authors have proven that in this case the subsidence following the shear load will develop as of the moment of application of the external load pro rata the logarithm of time irrespectively of the process of filtration consolidation.????????? ?????????? ? ??????? ????? ???????????? ? ?????????? ?????????????? ????????? ?? ????????? ??????? ??? ???????????? ??????? ???????? (??????? ??????. ????????, ??? ? ???????? ??????? ?????? ?????????? ??????? ???????? ? ????????? ?????? ?????????? ???????????? ??????????????? ??? ??????? ????????? ?? ??????? 1/2 ?? ???????? ????????? ????? ? ????? ????????? ???? ?? ??????? ? ??? ?????? ????????? ??????????? ??? ??????????, ??? ? ????????? ???????????? ??????. ????? ????, ??????????? ????????? ? ???????? ?????? ????????? 10. ??????? ?????????? ?????? ????????? ?????????? ? ???? ????? ?? ???????? ? ????????? ?????????? ? ???????????.??? ??????? ????????????????? ????????? ?????????????? ???????????? ? ???????? ?????????? ?????? ???????????? ??????????? ???????? Mathcad. ??? ????????? ??????????? ??????? ?? ??????????? ???????? ??????????? ???????? ???????? ??? ?????? ??????? ??????? ?? ?????? ?????????? ????????. ??? ??????????? ??????? ???????????? ?????? ?????????? ????? ??????????? ? ???? ????????? ???????????? ??????? ????? ???????? ???????????? ?????????? ? ??????? ????? ???????? ?????????? ? ????????????????? ?????????.? ?????????????? ??????? ?????? ????????? ??????? ?????? ?? ??????????????? ?????? ??????????????? ????????? ? ?????? ?????????

Ter-Martirosyan Zaven Grigor’evich

2013-04-01

317

Equivalent nozzle in thermomechanical problems  

International Nuclear Information System (INIS)

When analyzing nuclear vessels, it is most important to study the behavior of the nozzle cylinder-cylinder intersection. For the elastic field, this analysis in three dimensions is quite easy using the method of finite elements. The same analysis in the non-linear field becomes difficult for designs in 3-D. It is therefore necessary to resolve a nozzle in two dimensions equivalent to a 3-D nozzle. The purpose of the present work is to find an equivalent nozzle both with a mechanical and thermal load. This has been achieved by the analysis in three dimensions of a nozzle and a nozzle cylinder-sphere intersection, of a different radius. The equivalent nozzle will be a nozzle with a sphere radius in a given ratio to the radius of a cylinder; thus, the maximum equivalent stress is the same in both 2-D and 3-D. The nozzle examined derived from the intersection of a cylindrical vessel of radius R=191.4 mm and thickness T=6.7 mm with a cylindrical nozzle of radius r=24.675 mm and thickness t=1.350 mm, for which the experimental results for an internal pressure load are known. The structure was subdivided into 96 finite, three-dimensional and isoparametric elements with 60 degrees of freedom and 661 total nodes. Both the analysis with a mechanical load as well as the analysis with a thermal load were carried out on this structure according to the Bersafe system. The thermal load consisted of a transient typical of an accident occurring in a sodium-cooled fast reactor, with a peak of the temperature (5400C) for the sodium inside the vessel with an insulating argon temperature constant at 5250C. The maximum value of the equivalent tension was found in the internal area at the union towards the vessel side. The analysis of the nozzle in 2-D consists in schematizing the structure as a cylinder-sphere intersection, where the sphere has a given relation to the

318

Equivalence of conservation laws and equivalence of potential systems  

CERN Document Server

We study conservation laws and potential symmetries of (systems of) differential equations applying equivalence relations generated by point transformations between the equations. A Fokker-Planck equation and the Burgers equation are considered as examples. Using reducibility of them to the one-dimensional linear heat equation, we construct complete hierarchies of local and potential conservation laws for them and describe, in some sense, all their potential symmetries. Known results on the subject are interpreted in the proposed framework. This paper is an extended comment on the paper of J.-q. Mei and H.-q. Zhang [Internat. J. Theoret. Phys., 2006, in press].

Ivanova, N M; Ivanova, Nataliya M.; Popovych, Roman O.

2006-01-01

319

Scaling of the Divertor Heat Flux Width in the DIII-D Tokamak; Scaling of the Divertor Heat Flux Width in the DIII-D Tokamak  

International Nuclear Information System (INIS)

Full text: DIII-D measurements indicate a systematic narrowing of the divertor heat flux width ?q with plasma current in H-mode plasmas and significantly weaker dependence on other parameters. Comparisons of ?q with upstream SOL profiles indicate a similar variation, consistent with expectations from flux-limited transport. The inverse dependence of ?q on plasma current suggests that physics solutions for heat flux control may be more essential in next step devices to reduce the local heat flux below the maximum steady-state heat load sustainable by material surfaces of ? 10 MW/m2. We find that the heat flux profile is well fit by a two-parameter function with one parameter (?pvt) characterizing the profile in the private flux region and the second (?sol) characterizing the SOL. The heat flux integral width (integral of the profile divided by its peak value) of this function is a weighted linear sum of these two parameters. The integral width scales inversely with Ip, and has weaker dependencies on other parameters. However, ?sol is found to have a much simpler scaling, depending only on Ip (or equivalently, the poloidal magnetic field Bp). Measurements of upstream ne and Te profiles with an upgraded Thomson scattering diagnostic has made it possible to test parallel and radial transport models. The SOL profiles exhibit a narrowing ne with increasing Ip consistent with the measured divertor heat flux and a flux-limited parallel transport model. The strong dependence of ?q on Bp suggests two possible physics mechanisms setting the heat flux width. A semi-empirical model based on ion orbit drifts is consistent with the measured heat flux width and the dependence of the SOL ne profile. A critical pressure gradient model was also tested finding the SOL pressure profile width scaling consistently with a calculation of the ideal ballooning stability limit. A density scan from a low density attached state to a high density detached divertor state revealed SOL profile scale lengths related to the heat flux width for attached conditions. This suggests that the upstream profiles can be used to make inferences about radial transport under detached conditions where the divertor heat flux profile no longer represents the upstream SOL transport. (author)

320

Global synchronization of parallel processors using clock pulse width modulation  

Science.gov (United States)

A circuit generates a global clock signal with a pulse width modification to synchronize processors in a parallel computing system. The circuit may include a hardware module and a clock splitter. The hardware module may generate a clock signal and performs a pulse width modification on the clock signal. The pulse width modification changes a pulse width within a clock period in the clock signal. The clock splitter may distribute the pulse width modified clock signal to a plurality of processors in the parallel computing system.

Chen, Dong; Ellavsky, Matthew R.; Franke, Ross L.; Gara, Alan; Gooding, Thomas M.; Haring, Rudolf A.; Jeanson, Mark J.; Kopcsay, Gerard V.; Liebsch, Thomas A.; Littrell, Daniel; Ohmacht, Martin; Reed, Don D.; Schenck, Brandon E.; Swetz, Richard A.

2013-04-02

 
 
 
 
321

COMPLEX VARIABILITY OF THE H{alpha} EMISSION LINE PROFILE OF THE T TAURI BINARY SYSTEM KH 15D: THE INFLUENCE OF ORBITAL PHASE, OCCULTATION BY THE CIRCUMBINARY DISK, AND ACCRETION PHENOMENA  

Energy Technology Data Exchange (ETDEWEB)

We have obtained 48 high-resolution echelle spectra of the pre-main-sequence eclipsing binary system KH 15D (V582 Mon, P = 48.37 days, e {approx} 0.6, M{sub A} = 0.6 M{sub Sun }, M{sub B} = 0.7 M{sub Sun }). The eclipses are caused by a circumbinary disk (CBD) seen nearly edge on, which at the epoch of these observations completely obscured the orbit of star B and a large portion of the orbit of star A. The spectra were obtained over five contiguous observing seasons from 2001/2002 to 2005/2006 while star A was fully visible, fully occulted, and during several ingress and egress events. The H{alpha} line profile shows dramatic changes in these time series data over timescales ranging from days to years. A fraction of the variations are due to 'edge effects' and depend only on the height of star A above or below the razor sharp edge of the occulting disk. Other observed variations depend on the orbital phase: the H{alpha} emission line profile changes from an inverse P-Cygni-type profile during ingress to an enhanced double-peaked profile, with both a blue and a red emission component, during egress. Each of these interpreted variations are complicated by the fact that there is also a chaotic, irregular component present in these profiles. We find that the complex data set can be largely understood in the context of accretion onto the stars from a CBD with gas flows as predicted by the models of eccentric T Tauri binaries put forward by Artymowicz and Lubow, Guenther and Kley, and de Val-Borro et al. In particular, our data provide strong support for the pulsed accretion phenomenon, in which enhanced accretion occurs during and after perihelion passage.

Hamilton, Catrina M. [Department of Physics and Astronomy, Dickinson College, Carlisle, PA 17013 (United States); Johns-Krull, Christopher M. [Department of Physics and Astronomy, Rice University, Houston, TX 77005 (United States); Mundt, Reinhard [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Herbst, William [Astronomy Department, Wesleyan University, Middletown, CT 06459 (United States); Winn, Joshua N., E-mail: hamiltoc@dickinson.edu, E-mail: cmj@rice.edu, E-mail: mundt@mpia.de, E-mail: wherbst@wesleyan.edu, E-mail: jwinn@mit.edu [Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

2012-06-01

322

GAP WIDTH STUDY IN LASER BUTT-WELDING  

DEFF Research Database (Denmark)

In this paper the maximum allowable gap width in laser butt-welding is intensively studied. The gap width study (GWS) is performed on the material of SST of W1.4401 (AISI 316) under various welding conditions, which are the gap width : 0.00-0.50 mm, the welding speed : 0.5-2.0 m/min, the laser power : 2 and 2.6 kW and the focal point position : 0 and -1.2 mm. Quality of all the butt welds are destructively tested according to ISO 13919-1.Influences of the variable process parameters to the maximum allowable gap width are observed as (1) the maximum gap width is inversely related to the welding speed, (2) the larger laser power leads to the bigger maximum allowable gap width and (3) the focal point position has very little influence on the maximum gap width.

Gong, Hui; Olsen, Flemming Ove

1999-01-01

323

Conformal dynamical equivalence and applications  

Energy Technology Data Exchange (ETDEWEB)

The 'Conformal Dynamical Equivalence' (CDE) approach is briefly reviewed, and some of its applications, at various astrophysical levels (Sun, Solar System, Stars, Galaxies, Clusters of Galaxies, Universe as a whole), are presented. According to the CDE approach, in both the Newtonian and general-relativistic theories of gravity, the isentropic hydrodynamic flows in the interior of a bounded gravitating perfect-fluid source are dynamically equivalent to geodesic motions in a virtual, fully defined fluid source. Equivalently, the equations of hydrodynamic motion in the former source are functionally similar to those of the geodesic motions in the latter, physically, fully defined source. The CDE approach is followed for the dynamical description of the motions in the fluid source. After an observational introduction, taking into account all the internal physical characteristics of the corresponding perfect-fluid source, and based on the property of the isentropic hydrodynamic flows (quite reasonable for an isolated physical system), we examine a number of issues, namely, (i) the classical Newtonian explanation of the celebrated Pioneer-Anomaly effect in the Solar System, (ii) the possibility of both the attractive gravity and the repulsive gravity in a non-quantum Newtonian framework, (iii) the evaluation of the masses - theoretical, dynamical, and missing - and of the linear dimensions of non-magnetized and magnetized large-scale cosmological structures, (iv) the explanation of the flat-rotation curves of disc galaxies, (v) possible formation mechanisms of winds and jets, and (vi) a brief presentation of a conventional approach - toy model to the dynamics of the Universe, characterized by the dominant collisional dark matter (with its subdominant luminous baryonic 'contamination'), correctly interpreting the cosmological observational data without the need of the notions dark energy, cosmological constant, and universal accelerating expansion.

Spyrou, N K, E-mail: spyrou@astro.auth.gr [Astronomy Department, Aristoteleion University of Thessaloniki, 541.24 Thessaloniki, Macedonia, Hellas (Greece)

2011-02-01

324

Configuration of equivalent f electrons  

International Nuclear Information System (INIS)

The term 2F given to the ions Ce3+ and Yb3+ is due to an electron or to one hole, respectively, in the 4f configuration of the lanthanide elements. When the number of equivalent electrons (or holes) becomes larger than one, there is an increase in the number of terms. Considerations about the classification of terms to differentiate states of a given f sup(n) configuration are made on the basis of group theory. It is shown that different sets of quantum numbers are necessary to distinguish levels with the same representations and with different energies. (C.L.B.)

325

[Lscr]0-equivalence of maps  

Science.gov (United States)

We use the theory of the integral closure of an ideal to study the equivalence of map-germs under C0 coordinate changes in the target. We also derive a formula for the number of double points of a map germ from Cn [rightward arrow] C2n in terms of the Segre number of dimension 0 of an ideal associated to the double point locus of f, and the number of Whitney umbrellas of the composition of f with a generic projection to C2n[minus sign]1.

Gaffney, Terence

2000-05-01

326

Light WIMPs And Equivalent Neutrinos  

CERN Document Server

Very light WIMPs (chi), thermal relics that annihilate late in the early Universe, change the energy and entropy densities at BBN and at recombination. BBN, in combination with the CMB, can remove some of the degeneracies among light WIMPs and equivalent neutrinos, constraining the existence and properties of each. Depending on the nature of the light WIMP (Majorana or Dirac fermion, real or complex scalar) the joint BBN + CMB analyses set lower bounds to m_chi in the range 0.5 - 5 MeV (m_chi/m_e > 1 - 10), and they identify best fit values for m_chi in the range 5 - 10 MeV. The joint BBN + CMB analysis finds a best fit value for the number of equivalent neutrinos, Delta N_nu ~ 0.65, nearly independent of the nature of the WIMP. In the absence of a light WIMP (m_chi > 20 MeV), N_eff = 3.05(1 + Delta N_nu /3). In this case, there is excellent agreement between BBN and the CMB, but the joint fit reveals Delta N_nu = 0.40+-0.17, disfavoring standard big bang nucleosynthesis (SBBN) (Delta N_nu = 0) at ~ 2.4 sigma...

Steigman, Gary

2014-01-01

327

Chemical widths at composite interfaces: Relationships to structural widths and methods for measurement  

International Nuclear Information System (INIS)

Energy selected imaging with a Zeiss 912 ?-filter TEM was used to examine grain boundary solute distributions in an Si3N4/SiC(w) ceramic densified with Y2O3 + Al2O3 sintering aid. These results are compared to boundary region solute distributions in the same materials determined by field emission small probe electron energy loss spectroscopy and related methods. The intrinsic higher incident flux of the FEG small probe methods renders them the most useful for high spatial resolution local chemical width measurement. Energy selected imaging is fast and relatively simple for determining elemental distributions in boundaries at low magnifications. The methods are complementary

328

Pulse-width modulated external resistance increases the microbial fuel cell power output.  

Science.gov (United States)

This study describes MFC operation with a pulse-width modulated connection of the external resistor (R-PWM mode) at low and high frequencies. Analysis of the output voltage profiles acquired during R-PWM tests showed the presence of slow and fast dynamic components, which can be described by a simple equivalent circuit model suitable for process control applications. At operating frequencies above 100 Hz a noticeable improvement in MFC performance was observed with the power output increase of 22-43% as compared to MFC operation with a constant external resistance. PMID:23989037

Coronado, J; Perrier, M; Tartakovsky, B

2013-11-01

329

Measurement of the mass, full width, and radiative width of the B+ (1237) meson  

International Nuclear Information System (INIS)

An experiment was performed at Fermi National Accelerator Laboratory to investigate the coherent production of mesons on nuclear targets (lead and copper). The experiment used 200 GeV/c incident meson beam and a high resolution forward spectrometer consisting of proportional and drift chambers plus a liquid argon photon calorimeter. This thesis reports the results of the process ?+ + A ? ?+ omega + A. The ?+ omega spectrum was found to be dominated by the B+ (1237) meson. A fit was performed on the line shape of the ?+ omega mass spectrum and values of 1.271 +/- 0.011 GeV and 0.232 +/- 0.029 GeV were found for the mass and total width. The helicity zero decay probability of the omega, absolute value F02, was measured to be absolute value F02 = 0.15 +/- 0.035. The t distributions were analyzed allowing the electromagnetic and hadronic production processes to interfer. From these distributions a radiative width of 230 +/- 61 was extracted

330

Crack Width Analysis of Steel Fiber Reinforced Concrete Elements  

Directory of Open Access Journals (Sweden)

Full Text Available The article investigates the effectiveness of steel fiber reinforcement in RC concrete members in regard to ordinary reinforcement. The advantages and disadvantages of different shapes of steel fibers are discussed. The algorithm for calculating crack width based on EC2 and Rilem methodologies is presented. A comparison of theoretical and experimental crack widths has been performed. The relative errors of crack width predictions at different load levels were defined.Article in Lithuanian

Darius Ulbinas

2011-04-01

331

On absolute values of ?-widths for heavy spherical nuclei  

International Nuclear Information System (INIS)

On the basis of the ordinary ?-particle Saxon-Woods shell-model formfactors with configuration mixing the absolute values of ?-widths are calculated for heavy spherical nuclei. The importance of the pairing and superfluid correlations is demonstrated for all favourable and semi-favourable ?-transitions, including the same ?-transitions in Po210, Po211, Bi211 and Po212. The calculate ?-widths are close to the corresponding experimental ?-widths. (orig.)

332

Stability-Guaranteed Width Control for Hot Strip Mill  

Science.gov (United States)

We propose a stability-guaranteed width control (SGWC) for the hot strip finishing mill. It is shown that the proposed SGWC guarantees the stability of the width controller by the universal approximation of the neural network. It is shown through the field test in the hot strip mill of POSCO that the stability of the width controller is guaranteed by the proposed control scheme.

Park, Cheol Jae; Hwang, I. Cheol

333

A review of ultrabrief pulse width electroconvulsive therapy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The effect of shortening the pulse width of the electrical stimulus when administering electroconvulsive therapy (ECT) has recently been systematically studied with promising results. This review examines reported outcomes from three randomized controlled trials which compared ultrabrief (?0.3 ms) with brief (0.5–1.5 ms) pulse width ECT, and other recent clinical trials of ultrabrief pulse width ECT. The emerging evidence for ultrabrief pulse right unilateral (RUL) ECT suggests clinically...

Loo, Colleen K.; Katalinic, Natalie; Martin, Donel; Schweitzer, Isaac

2012-01-01

334

The significance of biometric parameters in determining anterior teeth width  

Directory of Open Access Journals (Sweden)

Full Text Available Background/Aim. An important element of prosthetic treatment of edentulous patients is selecting the size of anterior artificial teeth that will restore the natural harmony of one’s dentolabial structure as well as the whole face. The main objective of this study was to determine the correlation between the inner canthal distance (ICD and interalar width (IAW on one side and the width of both central incisors (CIW, the width of central and lateral incisors (CLIW, the width of anterior teeth (ATW, the width between the canine cusps (CCW, which may be useful in clinical practice. Methods. A total of 89 subjects comprising 23 male and 66 female were studied. Their age ranged from 19 to 34 years with the mean of 25 years. Only the subjects with the preserved natural dentition were included in the sample. All facial and intraoral tooth measurements were made with a Boley Gauge (Buffalo Dental Manufacturing Co., Brooklyn NY, USA having a resolution of 0.1mm. Results. A moderate correlation was established between the interalar width and combined width of anterior teeth and canine cusp width (r = 0.439, r = 0.374. A low correlation was established between the inner canthal distance and the width of anterior teeth and canine cusp width (r = 0.335, r = 0.303. The differences between the two genders were highly significant for all the parameters (p < 0.01. The measured facial distances and width of anterior teeth were higher in men than in women. Conclusion. The results of this study suggest that the examined interalar width and inner canthal distance cannot be considered reliable guidelines in the selection of artificial upper anterior teeth. However, they may be used as a useful additional factor combined with other methods for objective tooth selection. The final decision should be made while working on dentures fitting models with the patient’s consent.

Strajni? Ljiljana

2013-01-01

335

Radiological equivalent of chemical pollutants  

International Nuclear Information System (INIS)

The development of the peaceful uses of nuclear energy has caused continued effort toward public safety through radiation health protection measures and nuclear management practices. However, concern has not been focused on the development specifically in the operation of chemical pestrochemical industries as well as other industrial processes brought about by technological advancements. This article presents the comparison of the risk of radiation and chemicals. The methods used for comparing the risks of late effects of radiation and chemicals are considered at three levels. (a) as a frame of reference to give an impression of resolving power of biological tests; (b) as methods to quantify risks; (c) as instruments for an epidemiological survey of human populations. There are marked dissimilarities between chemicals and radiation and efforts to interpret chemical activity may not be achieved. Applicability of the concept of rad equivalence has many restrictions and as pointed out this approach is not an established one. (RTD)

336

Asymptotic estimation of widths of the quasistationary states  

International Nuclear Information System (INIS)

The new integral formalism for the calculation of the width of the quasistationary states without using smallness of the barrier penetration factor is proposed. Asymptotic formula for the width of the short-living quasistationary states on the base of saddle-point approximation is derived. On the base of our approach the widths of ?-decay of the Pb isotopes, baryon resonances and dibaryon resonances were calculated. A good agreement of the theory and experiment was demonstrated. The natural explanation of the small widths of low lying dibaryon resonances was argued. (author). 23 refs., 1 fig., 4 tabs

337

Congruences of strongly Morita equivalent posemigroups  

Directory of Open Access Journals (Sweden)

Full Text Available We prove that congruence lattices of strongly Morita equivalent posemigroupswith common joint weak local units are isomorphic. Moreover, the quotientposemigroups by the congruences that correspond to each other under this isomorphism are also strongly Morita equivalent.

T. Tärgla

2012-09-01

338

Silent Reading Rates in Grade Equivalents.  

Science.gov (United States)

Converts silent reading rates into grade equivalent units. Finds that growth in reading rate is approximately constant each year in school for typical students. Presents grade equivalent data which provides reasonably valid, criterion-referenced grade equivalents that may be used to evaluate the status and progress of individuals or groups. (RS)

Carver, Ronald P.

1989-01-01

339

The definition of the individual dose equivalent  

International Nuclear Information System (INIS)

A brief note examines the choice of the present definition of the individual dose equivalent, the new operational dosimetry quantity for external exposure. The consequences of the use of the individual dose equivalent and the danger facing the individual dose equivalent, as currently defined, are briefly discussed. (UK)

340

Equivalence in Bilingual Lexicography: Criticism and Suggestions*  

Directory of Open Access Journals (Sweden)

Full Text Available

Abstract: A reminder of general problems in the formation of terminology, as illustrated by theGerman Äquivalence (Eng. equivalence and äquivalent (Eng. equivalent, is followed by a critical discussionof the concept of equivalence in contrastive lexicology. It is shown that especially the conceptof partial equivalence is contradictory in its different manifestations. Consequently attemptsare made to give a more precise indication of the concept of equivalence in the metalexicography,with regard to the domain of the nominal lexicon. The problems of especially the metalexicographicconcept of partial equivalence as well as that of divergence are fundamentally expounded.In conclusion the direction is indicated to find more appropriate metalexicographic versions of theconcept of equivalence.

Keywords: EQUIVALENCE, LEXICOGRAPHIC EQUIVALENT, PARTIAL EQUIVALENCE,CONGRUENCE, DIVERGENCE, CONVERGENCE, POLYDIVERGENCE, SYNTAGM-EQUIVALENCE,ZERO EQUIVALENCE, CORRESPONDENCE

Abstrakt: Äquivalenz in der zweisprachigen Lexikographie: Kritik und Vorschläge.Nachdem an allgemeine Probleme der Begriffsbildung am Beispiel von dt. Äquivalenzund dt. äquivalent erinnert wurde, wird zunächst auf Äquivalenzbegriffe in der kontrastiven Lexikologiekritisch eingegangen. Es wird gezeigt, dass insbesondere der Begriff der partiellen Äquivalenzin seinen verschiedenen Ausprägungen widersprüchlich ist. Sodann werden Präzisierungenzu den Äquivalenzbegriffen in der Metalexikographie versucht, die sich auf den Bereich der Nennlexikbeziehen. Insbesondere der metalexikographische Begriff der partiellen Äquivalenz sowie derder Divergenz werden grundsätzlich problematisiert. In welche Richtung man gehen kann, umangemessenere metalexikographische Fassungen des Äquivalenzbegriffs zu finden, wird abschließendangedeutet.

Stichwörter: ÄQUIVALENZ, LEXIKOGRAPHISCHES ÄQUIVALENT, PARTIELLE ÄQUIVALENZ,KONGRUENZ, DIVERGENZ, KONVERGENZ, POLYDIVERGENZ, SYNTAGMENÄQUIVALENZ,NULLÄQUIVALENZ, KORRESPONDENZ

Herbert Ernst Wiegand

2011-10-01

 
 
 
 
341

A Discrete Equivalent of the Logistic Equation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A discrete equivalent and not analogue of the well-known logistic differential equation is proposed. This discrete equivalent logistic equation is of the Volterra convolution type, is obtained by use of a functional-analytic method, and is explicitly solved using the -transform method. The connection of the solution of the discrete equivalent logistic equation with the solution of the logistic differential ...

Petropoulou EugeniaN

2010-01-01

342

An equivalent sample circuit based on DSP  

International Nuclear Information System (INIS)

The author introduced an equivalent sample circuit which is based on DSP. With the technology of equivalent sample this circuit can sample signal with maximum 10 GHz equivalent sample rate under the condition of 40 MHz single-shot sample rate. The author describes the design theory and its advantage

343

Some spectral equivalences between Schroedinger operators  

International Nuclear Information System (INIS)

Spectral equivalences of the quasi-exactly solvable sectors of two classes of Schroedinger operators are established, using Gaudin-type Bethe ansatz equations. In some instances the results can be extended leading to full isospectrality. In this manner we obtain equivalences between PT-symmetric problems and Hermitian problems. We also find equivalences between some classes of Hermitian operators

344

Some spectral equivalences between Schroedinger operators  

Energy Technology Data Exchange (ETDEWEB)

Spectral equivalences of the quasi-exactly solvable sectors of two classes of Schroedinger operators are established, using Gaudin-type Bethe ansatz equations. In some instances the results can be extended leading to full isospectrality. In this manner we obtain equivalences between PT-symmetric problems and Hermitian problems. We also find equivalences between some classes of Hermitian operators.

Dunning, C [Institute of Mathematics, Statistics and Actuarial Science, University of Kent (United Kingdom); Hibberd, K E; Links, J [Centre for Mathematical Physics, School of Physical Sciences, University of Queensland, Brisbane 4072 (Australia)], E-mail: t.c.dunning@kent.ac.uk, E-mail: keh@maths.uq.edu.au, E-mail: jrl@maths.uq.edu.au

2008-08-08

345

Expanding shell and P Cygni profiles of 27 Canis Majoris  

International Nuclear Information System (INIS)

H-alpha and He I profiles of 27 CMa obtained between January 1985 and February 1989 are presented. Velocities of blue absorption and red emission components of H-alpha were different from that of He I, suggesting that the regions of formation of H-alpha and He I were different in the expanding shell of 27 CMa. Velocities of all the components of H-alpha were variable between April 16 and 18, 1989. But, from April 18, when the blue emission velocities were almost unchanged, the blue absorption and red emission velocities were decreasing and those for He I components were increasing. Equivalent widths of blue emission components of He I lines were almost constant during the observational interval, while red emission strengths of H-alpha profile displayed weak variations between April 16 and 26. He I and H-alpha profiles clearly show that 27 CMa has entered into a new shell phase. 22 refs

346

Quantifying River Widths of North America from Satellite Imagery  

Science.gov (United States)

River width is a fundamental predictor variable in many hydrologic, geomorphic, and biogeochemical models, yet current large-scale models rely on theoretical hydraulic geometry relationships that do not fully capture natural variability in river form. Here we present the first high-resolution dataset of long-term mean width of North American rivers wider than 30 m. The dataset contains 7.93 million georeferenced width measurements derived from Landsat TM and ETM+ imagery that were acquired when rivers were most likely to be at mean discharge. We built the dataset by developing an automated procedure that selects and downloads raw imagery, creates cloud-free normalized difference water index images, histogram balances and mosaics them together, and produces a water mask using a dynamic water-land threshold technique. We then visually inspected and corrected the mask for errors and used RivWidth software to calculate river width at each river centerline pixel. We validated our dataset using >1000 United States Geological Survey and Water Survey of Canada in situ gauge station measurements. Error analysis shows a robust relationship between the remotely sensed widths and in situ gauge measurements with an r 2 = 0.86 (Spearman's = 0.81) and a mean absolute error of 27.5 m. We find that North American river widths lie on logarithmic frequency curve with some notable exceptions at widths SWOT) satellite mission.

Allen, G. H.; Pavelsky, T.; Miller, Z.

2013-12-01

347

Measuring Slit Width and Separation in a Diffraction Experiment  

Science.gov (United States)

We present a procedure for measuring slit width and separation in single- and double-slit diffraction experiments. Intensity spectra of diffracted laser light are measured with an optical sensor (PIN diode). Slit widths and separations are extracted by fitting to the measured spectra. We present a simple fitting procedure to account for the…

Gan, K. K.; Law, A. T.

2009-01-01

348

He's variational iteration method for the modified equal width equation  

International Nuclear Information System (INIS)

Variational iteration method is introduced to solve the modified equal width equation. This method provides remarkable accuracy in comparison with the analytical solution. Three conservation quantities are reported. Numerical results demonstrate that this method is a promising and powerful tool for solving the modified equal width equation.

349

Equivalent velocity spectroscopy for development of femtosecond pulse radiolysis system  

International Nuclear Information System (INIS)

For studies of electron beam induced ultra-fast reaction process, femtosecond (fs) pulse radiolysis is under construction. To realize fs time resolution, fs electron and analyzing light pulses and their jitter compensation system are needed. About a 100fs electron pulse was generated by a photocathode RF gun LINAC and a magnetic pulse compressor. Synchronized Ti: Sapphire laser have a pulse width about 160fs. And, it is significant to avoid degradation of time resolution caused by velocity difference between electron and analyzing light in a sample. In the 'Equivalent velocity spectroscopy' method, incident analyzing light is slant toward electron beam with an angle associated with refractive index of sample. Then, to overlap light wave front and electron pulse shape, electron pulse shape is slanted toward the direction of travel. As a result of the equivalent velocity spectroscopy for hydrated electrons, using slanted electron pulse shape, optical absorption rise time was about 1.4ps faster than normal electron pulse shape. Thus, the 'Equivalent velocity spectroscopy' is effective for femtosecond pulse radiolysis. (author)

350

On SN-PN equivalence  

International Nuclear Information System (INIS)

We consider the artificial conversion of the discrete-ordinates (SN) equations into a system of spherical harmonic (PN) equations. This is done by adding to the SN equations an artificial source that has two components. The first component transforms the SN scattering term into PN-like scattering, while the second modifies the SN streaming operator into a lower-order PN streaming operator. Denoting by F and E the spaces of solutions of the SN and PN equations, respectively, we define SN-PN equivalence via a constructive Proposition based on two linear morphisms, ?? : F ? E and ?* : F ? F, such that if ? is the solution of the SN equations with source S + ?*(S), then ??? is solution of the PN equations with source ??S. We proceed then to prove this Proposition by constructing the two components of the artificial source. We also prove that when dim E ? dim F the morphism ?* is not unique, and propose a general form for the second component of the artificial source, which is shown to comprise all artificial sources previously proposed in the literature. (author)

351

Violation of the gauge equivalence  

CERN Document Server

F. V. Gubarev et al. (``On the significance of the vector potential squared'', Phys. Rev. Lett. 86, 2220) have argued that the minimum value of the volume integral of the vector potential squared may have physical meaning, in defiance of the gauge equivalence of potentials. Earlier, R. I. Khrapko proposed a gauge noninvariant electrodynamics spin tensor (``Spin density of electromagnetic waves'', [1]). The standard electrodynamics spin tensor is zero. Here we point out that the Biot-Savarat formula uniquely results in a preferred, "true" vector potential field which is generated from a given magnetic field. A similar integral formula uniquely permits to find a "true" scalar potential field generated from a given electric field even in the case of a nonpotential electric field. We say that an exterior derivative of a differential form is the boundary of this form and the integration of a form results in a new form named the generation. Generating from a generation yields zero. A boundary is closed. A generatio...

Khrapko, R I

2001-01-01

352

Equivalent Simplification Method of Micro-Grid  

Directory of Open Access Journals (Sweden)

Full Text Available The paper concentrates on the equivalent simplification method for the micro-grid system connection into distributed network. The equivalent simplification method proposed for interaction study between micro-grid and distributed network. Micro-grid network, composite load, gas turbine synchronous generation, wind generation are equivalent simplification and parallel connect into the point of common coupling. A micro-grid system is built and three phase and single phase grounded faults are performed for the test of the equivalent model of micro-grid. The simulation results show that the equivalent model of micro-grid is effective, and the dynamic of equivalent model is similar with the detailed model of micro-grid. The equivalent simplification method for the micro-grid network and distributed components is suitable for the study of micro-grid.  

Cai Changchun

2013-09-01

353

Neutron-induced background by an alpha-beam incident on a deuterium gas target and its implications for the study of the 2H(alpha,gamma)6Li reaction at LUNA  

CERN Document Server

The production of the stable isotope Li-6 in standard Big Bang nucleosynthesis has recently attracted much interest. Recent observations in metal-poor stars suggest that a cosmological Li-6 plateau may exist. If true, this plateau would come in addition to the well-known Spite plateau of Li-7 abundances and would point to a predominantly primordial origin of Li-6, contrary to the results of standard Big Bang nucleosynthesis calculations. Therefore, the nuclear physics underlying Big Bang Li-6 production must be revisited. The main production channel for Li-6 in the Big Bang is the 2H(alpha,gamma)6Li reaction. The present work reports on neutron-induced effects in a high-purity germanium detector that were encountered in a new study of this reaction. In the experiment, an {\\alpha}-beam from the underground accelerator LUNA in Gran Sasso, Italy, and a windowless deuterium gas target are used. A low neutron flux is induced by energetic deuterons from elastic scattering and, subsequently, the 2H(d,n)3He reaction....

Anders, M; Bellini, A; Aliotta, M; Bemmerer, D; Broggini, C; Caciolli, A; Costantini, H; Corvisiero, P; Davinson, T; Elekes, Z; Erhard, M; Formicola, A; Fülöp, Zs; Gervino, G; Guglielmetti, A; Gustavino, C; Gyürky, Gy; Junker, M; Lemut, A; Marta, M; Mazzocchi, C; Menegazzo, R; Prati, P; Alvarez, C Rossi; Scott, D; Somorjai, E; Straniero, O; Szücs, T

2013-01-01

354

Characterization and modeling of a piezoelectric micromachined ultrasonic transducer with a very large length/width aspect ratio  

International Nuclear Information System (INIS)

The objective of the current study was to characterize and model the performance of piezoelectric micromachined ultrasonic transducers (pMUTs) with large length/width aspect ratios. Single-element pMUTs with 20 different dimensions corresponding to aspect ratios ranging from 5:1 to 23:1 were designed. Multiple samples were fabricated for each design so that statistically meaningful data could be obtained. The pMUTs were characterized by the impedance measurement combined with an equivalent circuit analysis. A one-dimensional composite beam model was also used to correlate the equivalent circuit components with the structural parameters, and gain insight into the performance characteristics of pMUTs. The resonant frequencies were observed to decrease with the width of the membrane, but have no appreciable length dependence. With the correction of parasitic capacitance, the effective coupling coefficients were observed to increase with the width up to around 150 µm and then decrease. However, they did not show clear and consistent length dependence. The variation of the coupling coefficient as a function of width of the membrane was shown to be mainly due to the relative ratios between the electrode and membrane widths rather than membrane width itself. Although the model presented in this study was a simple one-dimensional electro-mechanical model, it did seem to offer both good qualitative and quantitative insights into the performance of pMUTs and provide a convenierformance of pMUTs and provide a convenient tool for designing thin membrane transducers with a large aspect ratio. The model can also take into consideration the residual stress effect and offer an even more realistic prediction

355

On graph classes with logarithmic boolean-width  

CERN Document Server

Boolean-width is a recently introduced graph parameter. Many problems are fixed parameter tractable when parametrized by boolean-width, for instance "Minimum Weighted Dominating Set" (MWDS) problem can be solved in $O^*(2^{3k})$ time given a boolean-decomposition of width $k$, hence for all graph classes where a boolean-decomposition of width $O(\\log n)$ can be found in polynomial time, MWDS can be solved in polynomial time. We study graph classes having boolean-width $O(\\log n)$ and problems solvable in $O^*(2^{O(k)})$, combining these two results to design polynomial algorithms. We show that for trapezoid graphs, circular permutation graphs, convex graphs, Dilworth-$k$ graphs, circular arc graphs and complements of $k$-degenerate graphs, boolean-decompositions of width $O(\\log n)$ can be found in polynomial time. We also show that circular $k$-trapezoid graphs have boolean-width $O(\\log n)$, and find such a decomposition if a circular $k$-trapezoid intersection model is given. For many of the graph classes ...

Belmonte, Rémy

2010-01-01

356

A New Method for Estimating the Widths of JPEG Images  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Image width is important for image understanding. We propose a novel method to estimate widths for JPEG images when their widths are not available. The key idea is that the distance between two decoded MCUs (Minimum Coded Unit) adjacent in the vertical direction is usually small, which is measured by the average Euclidean distance between the pixels from the bottom row of the top MCU and the top row of the bottom MCU. On PASCAL VOC 2010 challenge dataset and USC-SIPI image d...

Xianyan, Wu; Qi, Han; Dan, Le; Xiamu, Niu

2014-01-01

357

Pulse-width compression based on photonic crystal fiber  

Science.gov (United States)

According to the characteristics of high-order solitons, compressed picosecond pulses are numerically simulated in the photonic crystal fiber (PCF), by means of split-step Fourier method. The results show that, PCF enables input pulse with lower peak power to form high-order solitons for the purpose of femtosecond pulse-width compression. For example, 60- femtosecond pulse width was made for 1-ps initial pulse width only over the distance of 2.2 m. Besides, shorter optimum fiber length for compression and higher compression ratio could be obtained on the premise of pre-chirp technique.

Wang, Jing; Wang, Zhen-Li; Shi, Yan-Mei

2006-05-01

358

Bank stability and channel width adjustment, East Fork River, Wyoming.  

Science.gov (United States)

Frequent surveys of eight cross sections located in self-formed reaches of the East Fork River, Wyoming, during the 1974 snowmelt flood showed a close relation between channel morphology and scour and fill. Those cross sections narrower than the mean reach width filled at discharges less than bankfull and scoured at discharges greater than bankfull. Those cross sections wider than the mean reach width scoured at discharges less than bankfull and filled at discharges greater than bankfull. Bank stability, and to some extent the adjustment of stream channel width, in the East Fork River study reach appears to be controlled by the processes of scour and fill. -from Author

Andrews, E. D.

1982-01-01

359

Equivalent Simplification Method of Micro-Grid  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The paper concentrates on the equivalent simplification method for the micro-grid system connection into distributed network. The equivalent simplification method proposed for interaction study between micro-grid and distributed network. Micro-grid network, composite load, gas turbine synchronous generation, wind generation are equivalent simplification and parallel connect into the point of common coupling. A micro-grid system is built and three phase and single phase grounded faults are per...

Cai Changchun; Cao Xiangqin

2013-01-01

360

Homogeneous Dielectric Equivalents of Composite Material Shields  

Directory of Open Access Journals (Sweden)

Full Text Available The paper deals with the methodology of replacing complicated parts of an airplane skin by simple homogeneous equivalents, which can exhibit similar shielding efficiency. On one hand, the airplane built from the virtual homogeneous equivalents can be analyzed with significantly reduced CPU-time demands and memory requirements. On the other hand, the equivalent model can estimate the internal fields satisfactory enough to evaluate the electromagnetic immunity of the airplane.

P. Tobola

2009-04-01

 
 
 
 
361

Perverse Equivalences and Brou\\'e's Conjecture  

CERN Document Server

We give a new approach to the construction of derived equivalences between blocks of finite groups, based on perverse equivalences, in the setting of Brou\\'e's conjecture. We provide in particular local and global perversity data describing the principal blocks and the derived equivalences for a number of finite simple groups with Sylow subgroups C3xC3. We also examine extensions to automorphism groups in a general setting.

Craven, David A

2010-01-01

362

Discovering Classes of Strongly Equivalent Logic Programs  

CERN Document Server

In this paper we apply computer-aided theorem discovery technique to discover theorems about strongly equivalent logic programs under the answer set semantics. Our discovered theorems capture new classes of strongly equivalent logic programs that can lead to new program simplification rules that preserve strong equivalence. Specifically, with the help of computers, we discovered exact conditions that capture the strong equivalence between a rule and the empty set, between two rules, between two rules and one of the two rules, between two rules and another rule, and between three rules and two of the three rules.

Chen, Y; 10.1613/jair.2131

2011-01-01

363

The equivalent stress concept in multiaxial fatigue  

Directory of Open Access Journals (Sweden)

Full Text Available Some equivalent stress methods, applicable for life prediction in case of multiaxial loading, are presented in this paper, such as empirical equivalent stresses, frequency and “signed von Mises” stress. To apply the latter method, a calculation program that allows the transformation of a fluctuating load cycle into a fully reversed cycle is developed. The authors extend the equivalent stress concept towards critical plane models. This is illustrated by a calculated equivalent shear stress based on the Yokobori criterion. Both the „signed von Mises” and Yokobori approaches have the advantage of allowing multiaxial fatigue calculations for limited durability, as opposed to classical methods which are applicable only for unlimited durability.

DUMITRU Ion

2011-06-01

364

Evaluation of spectral line width of atoms in liquid helium  

International Nuclear Information System (INIS)

Laser induced fluorescence experiments indicate change of spectral line profiles of atoms and molecules compared to the free system when embedded under liquid helium. Based on relativistic density functional approach a model has been proposed here to estimate the width of the spectral lines embedded under liquid helium in which the central atom resides within a cluster of helium atoms. The model assumes an overall floppy motion of the liquid helium atoms due to finite temperature and subsequent determination of the width from the ab initio estimated potential energy diagram. Calculated width of the resonance lines of Rb and Cs show good agreement with available laser spectroscopic data. -- Highlights: ? We study the change of the resonant transitions of Alkali atoms in liquid Helium. ? Our model allows fully relativistic ab initio calculations of the line width of such a transition. ? Comparison with experiment for Rb and Cs is nearly complete.

365

Widths of some classes of convex functions and bodies  

Energy Technology Data Exchange (ETDEWEB)

We consider classes of uniformly bounded convex functions defined on convex compact bodies in R{sup d} and satisfying a Lipschitz condition and establish the exact orders of their Kolmogorov, entropy, and pseudo-dimension widths in the L{sub 1}-metric. We also introduce the notions of pseudo-dimension and pseudo-dimension widths for classes of sets and determine the exact orders of the entropy and pseudo-dimension widths of some classes of convex bodies in R{sup d}relative to the pseudo-metric defined as the d-dimensional Lebesgue volume of the symmetric difference of two sets. We also find the exact orders of the entropy and pseudo-dimension widths of the corresponding classes of characteristic functions in L{sub p}-spaces, 1{<=}p{<=}{infinity}.

Konovalov, V N [Institute of Mathematics of Ukrainian National Academy of Sciences, Kiev (Ukraine); Maiorov, Vitalii E [Technion - Israel Institute of Technology, Haifa (Israel)

2010-02-28

366

Optical waveguide device with an adiabatically-varying width  

Science.gov (United States)

Optical waveguide devices are disclosed which utilize an optical waveguide having a waveguide bend therein with a width that varies adiabatically between a minimum value and a maximum value of the width. One or more connecting members can be attached to the waveguide bend near the maximum value of the width thereof to support the waveguide bend or to supply electrical power to an impurity-doped region located within the waveguide bend near the maximum value of the width. The impurity-doped region can form an electrical heater or a semiconductor junction which can be activated with a voltage to provide a variable optical path length in the optical waveguide. The optical waveguide devices can be used to form a tunable interferometer (e.g. a Mach-Zehnder interferometer) which can be used for optical modulation or switching. The optical waveguide devices can also be used to form an optical delay line.

Watts; Michael R. (Albuquerque, NM), Nielson; Gregory N. (Albuquerque, NM)

2011-05-10

367

Mean Width of a Regular Cross-Polytope  

CERN Document Server

The expected range of a sample of n+1 normally distributed variables is known to be related to the mean width of a regular n-simplex. We show that the expected maximum mu_n of a sample of n half-normally distributed variables is related to the mean width of a regular n-crosspolytope. Both of these relations have mean square counterparts. An expression for mu_5 is found and is believed to be new.

Finch, Steven R

2011-01-01

368

Rinsing Processes in Open-width Washing Machines  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A simulator is described for rinsing processes carried out on open-width washing machines. In combination with a theoretical model, a simple method is given for testing rinsing processes. The method has been used to investigate the extraction of caustic soda from a cotton fabric, varying the temperature, fabric velocity and type of fabric. The results were verified by measurements in a commercial open-width washing machine. The absorption of carbon dioxide from the atmosphere in the washing w...

Kroezen, A. B. J.; Linden, H. J. L. J.; Groot Wassink, J.

1986-01-01

369

Bone Mineral Density Value Dependence on Bone Width  

Directory of Open Access Journals (Sweden)

Full Text Available Dual x-ray absorptiometry (DXA is the most widely used measurement for the assessment of bone mass in osteoporosis. In clinical measurement, bone width can affect bone mineral parameters. The purpose of this study was to examine the dependence of bone mineral pa-rameters on bone width. In this study, DXA measurements were conducted on rabbit bone in vivo using clinical instruments. We have selected rabbit’s bones that have low BMD and more collagen tissue to predict structure not only measures BMD, but is also sensitive to the structure of the bone. To investigate the effect of bone width on the measured parameters, three regions of femur and tibia bones (N=132 were processed: upper (1/3 of length, middle (1/2 of length and lower (2/3 of length for BMC, areal BMD and volumetric BMD. The ANOVA analysis of bone mineral extracted by DXA showed significant differences (P<0.05 between BMC, BMDa and BMDv of six groups of upper, middle and lower parts of the femur and the tibia. It shows that BMC and BMD correlate well with the bone width, but BMDv inversely correlates with bone width. Linear and nonlinear regression analyses were used to examine the relationship between DXA characteristics with bone width and the regression function for each parameter is given. We concluded that BMC, areal BMD, and volumetric BMD in rabbit's bone with collagen fibers more than bone mineral are dependent on bone width. This result may be at least in part due to large precision error measurement of the bone width, in vivo.

M. Mokhtari-Dizaji

2006-05-01

370

Determination of the radiative decay width of the ?c meson  

International Nuclear Information System (INIS)

An analysis of the reaction ????c was performed in five different decay channels of the ?c: KS0K±?F, K+K-?+?-, 2?+2?-, ?? and 2K+2K-. A value ???(?c)=(11.3±4.2) keV was obtained for the radiative decay width by combining the results from the first four channels. Using our result on the two-photon width we also determined the branching ratio for the decay ?c?2K+2K-. (orig.)

371

Unprecedented grain size effect on stacking fault width  

Directory of Open Access Journals (Sweden)

Full Text Available Using an atomistic-phase field dislocation dynamics model, we isolate and investigate grain size and stress effects on the stacking fault width created by partial dislocation emission from a boundary. We show that the nucleation stress for a Shockley partial is governed by size of the boundary defect and insensitive to grain size. We reveal a grain size regime in which the maximum value the stacking fault width attains increases with grain size.

A. Hunter

2013-09-01

372

Rossman/Chance Applet Collection: Selecting Histogram Bin-Width  

Science.gov (United States)

This applet demonstrates the impact of data bin width on the display of information in histograms. The user is able to control the bin width and the axes of the histogram with the resultant changes shown immediately. There are two data sets available for use, and the user can edit the data or create new data sets. This is part of a larger collection of applets on statistics from the California Poly San Luis Obispo.

Rossman, Allan; Chance, Beth

2008-09-04

373

Correlations for reduced-width amplitudes in 49V  

International Nuclear Information System (INIS)

Measurement of the relative sign of inelastic proton-channel amplitudes permits the determination of amplitude correlations. Data were obtained for 45 5/2+ resonances in 49V. Although the reduced widths in each channel followed a Porter-Thomas distribution, large amplitude correlations were observed. The results are compared with the reduced-width--amplitude distribution of Krieger and Porter. This is the first direct test of the Krieger-Porter distribution

374

The width of the giant dipole resonance at finite temperature  

International Nuclear Information System (INIS)

A method is proposed to evaluate the effect of the change of the Fermi sea on the width of the giant dipole resonance at finite temperature. In a schematic model it is found that, indeed, in 208Pb the width increases very sharply up to about T=4 MeV but shows a much weaker variation for higher temperature. (author) 26 refs., 7 figs., 2 tabs

375

SM Higgs decay branching ratios and total Higgs width  

CERN Multimedia

Upper: Higgs decay ratios as a function of Higgs mass. The largest branching ratio is not necessarily the most usefull one. The most usefull ones are gamma gamma bbar ZZ and WW as in those modes latter signal to background ratios can be achieved. Lower: Total Higgs decay width versus Higgs mass. At low masses the natural width is extremely small, thus observability depends on instrumental resolution primarily.

Daniel Denegri

2001-01-01

376

Constant Width Planar Computation Characterizes ACC0  

DEFF Research Database (Denmark)

We obtain a characterization of ACC 0 in terms of a natural class of constant width circuits, namely in terms of constant width polynomial size planar circuits. This is shown via a characterization of the class of acyclic digraphs which can be embedded on a cylinder surface in such a way that all arcs flow along the same direction of the axis of the cylinder.

Hansen, K.A.

2004-01-01

377

Slit width calibration with a radioactive photon source  

International Nuclear Information System (INIS)

Optical slits and similar small openings may be easily calibrated in width or area without the troublesome diffraction effects which occur at visible wavelengths and make accurate measurement very difficult. One employs photons of much shorter wavelengths, the soft X-rays emitted by a radioactive source, 55Fe for example. With such a source and a suitable photon detctor, width calibrations to micrometer dimensions are quickly made. (orig.)

378

Echo width of foam supports used in scattering measurements  

DEFF Research Database (Denmark)

Theoretically and experimentally determined echo widths of dielectric cylinders having circular, triangular, and quadratic cross sections have been compared. The cylinders were made of foam material having a relative dielectric constant of about 1.035. The purpose of the investigation was to find a cross section with a small echo width. The result can be used in selecting a proper support for test objects in backscattering measurement studies.

Appel-Hansen, JØrgen

1979-01-01

379

Crack width monitoring of concrete structures based on smart film  

Science.gov (United States)

Due to its direct link to structural security, crack width is thought to be one of the most important parameters reflecting damage conditions of concrete structures. However, the width problem is difficult to solve with the existing structural health monitoring methods. In this paper, crack width monitoring by means of adhering enameled copper wires with different ultimate strains on the surface of structures is proposed, based on smart film crack monitoring put forward by the present authors. The basic idea of the proposed method is related to a proportional relationship between the crack width and ultimate strain of the broken wire. Namely, when a certain width of crack passes through the wire, some low ultimate strain wires will be broken and higher ultimate strain wires may stay non-broken until the crack extends to a larger scale. Detection of the copper wire condition as broken or non-broken may indicate the width of the structural crack. Thereafter, a multi-layered stress transfer model and specimen experiment are performed to quantify the relationship. A practical smart film is then redesigned with this idea and applied to Chongqing Jiangjin Yangtze River Bridge.

Zhang, Benniu; Wang, Shuliang; Li, Xingxing; Zhang, Xu; Yang, Guang; Qiu, Minfeng

2014-04-01

380

22 CFR 1421.18 - Regular and substantially equivalent employment.  

Science.gov (United States)

... 2010-04-01 true Regular and substantially equivalent employment. 1421.18...SUBCHAPTER § 1421.18 Regular and substantially equivalent employment. Regular and substantially equivalent employment means...

2010-04-01

 
 
 
 
381

5 CFR 2421.17 - Regular and substantially equivalent employment.  

Science.gov (United States)

...2010-01-01 false Regular and substantially equivalent employment. 2421.17...SUBCHAPTER § 2421.17 Regular and substantially equivalent employment. Regular and substantially equivalent employment means...

2010-01-01

382

Equivalence of Some Affine Isoperimetric Inequalities  

Directory of Open Access Journals (Sweden)

Full Text Available We establish the equivalence of some affine isoperimetric inequalities which include the -Petty projection inequality, the -Busemann-Petty centroid inequality, the "dual" -Petty projection inequality, and the "dual" -Busemann-Petty inequality. We also establish the equivalence of an affine isoperimetric inequality and its inclusion version for -John ellipsoids.

Yu Wuyang

2009-01-01

383

Equivalence classes of block Jacobi matrices  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The paper contains two results on the equivalence classes of block Jacobi matrices: first, that the Jacobi matrix of type 2 in the Nevai class has A_n coefficients converging to 1, and second, that under an L1-type condition on the Jacobi coefficients, equivalent Jacobi matrices of type 1, 2 and 3 are pairwise asymptotic.

Kozhan, Rostyslav

2009-01-01

384

7 CFR 1000.54 - Equivalent price.  

Science.gov (United States)

...2010-01-01 2009-01-01 true Equivalent price. 1000.54 Section 1000.54 Agriculture Regulations of the Department...OF FEDERAL MILK MARKETING ORDERS Class Prices § 1000.54 Equivalent price. If for any reason a...

2010-01-01

385

Preschoolers' Recognition of Numerical Equivalence: Sequential Sets.  

Science.gov (United States)

Examined whether preschoolers could recognize numerical equivalence for comparisons involving sequentially presented sets. Found that children recognized numerical equivalence for static sets earlier than for sequential sets. Memory of the number of sequentially presented objects emerged earlier than memory for the number of sequential events.…

Mix, Kelly S.

1999-01-01

386

Effective dose equivalent concept in radiopharmaceutical dosimetry  

International Nuclear Information System (INIS)

The Effective Dose Equivalent Concept defined by the International Commission on Radiological Protection in 1977 considers the risk from irradiation including both hereditary and somatic effects. This paper will deal with the definition of a concept for somatic effects only, the somatically significant dose equivalent. This is defined as the dose equivalent which if received by every member of the population, would be expected to produce the same total somatic injury to the population as does the actual dose equivalent received by various individuals. The somatically effective dose equivalent for a particular radiopharmaceutical is the weighted sum of the average dose equivalent to various organs. The dose equivalent to various organs can be derived from an extended MIRD formalism also considering the rest of body excluding the source volumes and the re iden e times in total body and the target organs. Examples are given for the calculation of somatically effective dose equivalent for the most frequent examinations with radiopharmaceuticals in Sweden during 1979

387

A Measurement of the Total Width, the Electronic Width and the Mass of the Upsilon(10580) Resonance  

CERN Document Server

We present a preliminary measurement of the resonance parameters of the Upsilon(10580) resonance with the BABAR detector at the SLAC PEP-II asymmetric B factory. We measure the total decay width to be (20.7 +- 1.6 +- 2.5) MeV, the partial electronic width to be (0.321 +- 0.017 +- 0.029) kev and the mass to be (10.5793 +- 0.0004 +- 0.0012) GeV.

Aubert, Bernard; Abe, T; Abrams, G S; Adye, T; Ahmed, S; Alam, M S; Albert, J; Aleksan, Roy; Allison, J; Altenburg, D; Andreotti, M; Angelini, C; Anulli, F; Aston, D; Azzolini, V; Baak, M A; Back, J J; Bailey, S; Baldini-Ferroli, R; Band, H R; Banerjee, Sw; Barate, R; Barlow, N R; Barlow, R J; Bartoldus, R; Batignani, G; Bauer, J M; Beck, T W; Behera, P K; Bellini, F; Benayoun, M; Berger, N; Beringer, J; Bernard, D; Berryhill, J W; Best, D; Bettarini, S; Bettoni, D; Bevan, A J; Bhimji, W; Bianchi, F; Biasini, M; Blanc, F; Blaylock, G; Blinov, V E; Bloom, P; Bondioli, M; Bonneaud, G R; Borean, C; Borgland, A W; Bosisio, L; Boutigny, D; Bowerman, D A; Boyarski, A M; Boyd, J T; Bozzi, C; Brandt, T; Brau, B; Brau, J E; Breon, A B; Briand, H; Brigljevic, V; Brochard, F; Brose, J; Brown, C L; Brown, C M; Brown, D; Brown, D N; Bruinsma, M; Brunet, S; Bucci, F; Buchanan, C; Buchmüller, O L; Bugg, W; Bukin, A D; Burchat, Patricia R; Button-Shafer, J; Buzzo, A; Bóna, M; Cahn, R N; Calabrese, R; Calcaterra, A; Calderini, G; Campagnari, C; Capra, R; Carpinelli, M; Cartaro, C; Cavallo, N; Cavoto, G; Chao, M; Charles, E; Chauveau, J; Chen, E; Chen, J C; Chen, S; Cheng, C H; Chevalier, N; Christ, S; Cibinetto, G; Clark, P J; Cochran, J; Cohen-Tanugi, J; Colberg, T; Colecchia, F; Coleman, J P; Contri, R; Convery, M R; Cote-Ahern, D; Cottingham, W N; Coupal, D P; Cowan, G; Cowan, R; Crawley, H B; Cremaldi, L M; Crosetti, G; Dahmes, B; Dallapiccola, C; Danielson, N; Dasu, S; Datta, M; Dauncey, P D; David, P; Davier, M; Davis, C L; Day, C T; De Groot, N; De Nardo, Gallieno; De Sangro, R; Del Buono, L; Del Gamba, V; Del Re, D; Della Ricca, G; Di Lodovico, F; Dickopp, M; Dittongo, S; Donald, M; Dong, D; Dorfan, J; Dorigo, A; Dubitzky, R S; Dubois-Felsmann, G P; Dujmic, D; Dunwoodie, W M; Dvoretskii, A; Eckmann, R; Edwards, A J; Egede, U; Eichenbaum, A M; Eigen, G; Eisner, A M; Elmer, P; Emery, S; Ernst, J A; Eschenburg, V; Eschrich, I; Fabozzi, F; Faccini, R; Falciai, D; Farbin, A; Ferrarotto, F; Ferroni, F; Field, R C; Finocchiaro, G; Fisher, A; Flack, R L; Flächer, H U; Flood, K T; Ford, K; Ford, W T; Forti, A C; Forti, F; Fortin, D; Franek, B J; Frey, R; Fry, J R; Gabathuler, Erwin; Gabriel, T A; Gaidot, A; Gaillard, J M; Gaillard, J R; Galeazzi, F; Gallo, F; Gamba, D; Gamet, R; Gan, K K; Ganzhur, S F; Gaspero, M; Gatto, C; Geddes, N I; George, S; Gill, M S; Giorgi, M A; Giraud, P F; Gladney, L; Glanzman, T; Godang, R; Goetzen, K; Golubev, V B; Gopal, G P; Gowdy, S J; Grancagnolo, S; Graugès-Pous, E; Green, M G; Grenier, G J; Grenier, P; Gritsan, A V; Grosdidier, G; Groysman, Y; Guo, Q H; Hadavand, H K; Hadig, T; Haire, M; Halyo, V; Hamel de Monchenault, G; Hamon, O; Harrison, P F; Harrison, T J; Hart, P A; Hartfiel, B L; Harton, J L; Hast, C; Hauke, A; Hawkes, C M; Hearty, C; Held, T; Hertzbach, S S; Heusch, C A; Hicheur, A; Hill, E J; Hitlin, D G; Hodgkinson, M C; Honscheid, K; Hrynóva, T; Hu, T; Hufnagel, D; Höcker, A; Innes, W R; Ivanchenko, V N; Izen, J M; Jackson, F; Jackson, P D; Jacobsen, R G; Jawahery, A; Jayatilleke, S M; Jessop, C P; John, M J J; Johnson, J R; Judd, D; Kadel, R W; Kadyk, J; Kagan, H; Karyotakis, Yu; Kass, R; Kay, M; Kelly, M P; Kelsey, M H; Kerth, L T; Khan, A; Kim, H; Kim, P; Kirkby, D; Kitayama, I; Knowles, D J; Koch, H; Kocian, M L; Kofler, R; Kolomensky, Yu G; Koptchev, V B; Kovalskyi, D; Kowalewski, R V; Kozanecki, Witold; Kral, J F; Kravchenko, E A; Krishnamurthy, M; Kroeger, R; Kukartsev, G; Kurup, A; Kutter, P E; Kuznetsova, N; Kyberd, P; La Vaissière, C de; Lacker, H M; Lae, C K; Lafferty, G D; Lamsa, J; Lanceri, L; Lange, D J; Langenegger, U; Langer, M; Lankford, A J; Laplace, S; Latham, T E; Lavin, D; Lazzaro, A; Le Clerc, C; Le Diberder, F R; Lee, S J; Lees, J P; Legendre, M; Leith, D W G S; Lepeltier, V; Leruste, P; Levesque, J A; Levi, M E; Levy, S L; Lewandowski, B; Li, H; Lillard, V; Lista, L; Liu, R; Lo Vetere, M; LoSecco, J M; Lockman, W S; London, G W; Long, O; Lou, X C; Lu, A; Luitz, S; Luppi, E; Lusiani, A; Lutz, A M; Lynch, G; Lynch, H L; Lyon, A J; Lü, C; Lüth, V; MacFarlane, D B; MacKay, C; Macri, M; Mallik, U; Maly, E; Mancinelli, G; Mandelkern, M A; Manfredi, P F; Mangeol, D J J; Marchiori, G; Margoni, M; Marker, C E; Marsiske, H; Martínez-Vidal, F; Mattison, T S; Mayer, B; Mazur, M A; Mazzoni, M A; McKemey, A K; McKenna, J A; McMahon, T R; Meadows, B T; Messner, R; Meyer, T I; Meyer, W T; Miftakov, V; Mihályi, A; Mir, L M; Mohapatra, A K; Mommsen, R K; Monge, M R; Moore, T B; Morandin, M; Morgan, S E; Morganti, M; Morganti, S; Morii, M; Morton, G W; Muheim, F; Müller, D R; Müller-Pfefferkorn, R; Narsky, I; Nash, J A; Nauenberg, U; Neal, H; Negrini, M; Neri, N; Nicholson, H; Nogowski, R; O'Grady, C P; Ocariz, J; Oddone, P J; Ofte, I; Olaiya, E O; Olivas, A; Olsen, J; Onuchin, A P; Orimoto, T J; Otto, S; Ozcan, V E; Paar, H P

2003-01-01

388

Equivalence in Ventilation and Indoor Air Quality  

Energy Technology Data Exchange (ETDEWEB)

We ventilate buildings to provide acceptable indoor air quality (IAQ). Ventilation standards (such as American Society of Heating, Refrigerating, and Air-Conditioning Enginners [ASHRAE] Standard 62) specify minimum ventilation rates without taking into account the impact of those rates on IAQ. Innovative ventilation management is often a desirable element of reducing energy consumption or improving IAQ or comfort. Variable ventilation is one innovative strategy. To use variable ventilation in a way that meets standards, it is necessary to have a method for determining equivalence in terms of either ventilation or indoor air quality. This study develops methods to calculate either equivalent ventilation or equivalent IAQ. We demonstrate that equivalent ventilation can be used as the basis for dynamic ventilation control, reducing peak load and infiltration of outdoor contaminants. We also show that equivalent IAQ could allow some contaminants to exceed current standards if other contaminants are more stringently controlled.

Sherman, Max; Walker, Iain; Logue, Jennifer

2011-08-01

389

Bisimulations meet PCTL equivalences for probabilistic automata  

DEFF Research Database (Denmark)

Probabilistic automata (PAs) have been successfully applied in formal verification of concurrent and stochastic systems. Efficient model checking algorithms have been studied, where the most often used logics for expressing properties are based on probabilistic computation tree logic (PCTL) and its extension PCTL*. Various behavioral equivalences are proposed, as a powerful tool for abstraction and compositional minimization for PAs. Unfortunately, the equivalences are well-known to be sound, but not complete with respect to the logical equivalences induced by PCTL or PCTL*. The desire of a both sound and complete behavioral equivalence has been pointed out by Segala in [34], but remains open throughout the years. In this paper we introduce novel notions of strong bisimulation relations, which characterize PCTL and PCTL* exactly. We extend weak bisimulations that characterize PCTL and PCTL* without next operator, respectively. Further, we also extend the framework to simulation preorders. Thus, our paper bridges the gap between logical and behavioral equivalences and preorders in this setting.

Song, Lei; Zhang, Lijun

2013-01-01

390

On nice equivalence relations on 2^\\lambda  

CERN Document Server

The main question here is the possible generalization of the following theorem on ``simple'' equivalence relation on 2^omega to higher cardinals. Theorem: (1) Assume that: (a) E is a Borel 2-place relation on 2^omega, (b) E is an equivalence relation, (c) if eta, nu in 2^omega and (exists ! n)(eta(n) not= nu(n)), then eta, nu are not E --equivalent. Then there is a perfect subset of 2^omega of pairwise non E-equivalent members. (2) Instead of ``E is Borel'', ``E is analytic (or even a Borel combination of analytic relations)'' is enough. (3) If E is a Pi^1_2 relation which is an equivalence relation satisfying clauses (b)+(c) in V^Cohen, then the conclusion of (1) holds.

Shelah, S

2000-01-01

391

Saturated Widths of Magnetic Islands in Tokamak Discharges  

Science.gov (United States)

The new ISLAND module described in reference [1] implements a quasi-linear model to compute the widths of multiple magnetic islands driven by saturated tearing modes in toroidal plasmas of arbitrary aspect ratio and cross sectional shape. The distortion of the island shape caused by the radial variation in the perturbation is computed in the new module. In transport simulations, the enhanced transport caused by the magnetic islands has the effect of flattening the pressure and current density profiles. This self consistent treatment of the magnetic islands alters the development of the plasma profiles. In addition, it is found that islands closer to the magnetic axis influence the evolution of islands further out in the plasma. In order to investigate such phenomena, the ISLAND module is used within the BALDUR predictive modeling code to compute the widths of multiple magnetic islands in tokamak discharges. The interaction between the islands and sawtooth crashes is examined in simulations of DIII-D and JET discharges. The module is used to compute saturated neoclassical tearing mode island widths for multiple modes in ITER. Preliminary results for island widths in ITER are consistent with those presented [2] by Hegna. [1] F.D. Halpern, G. Bateman, A.H. Kritz and A.Y. Pankin, ``The ISLAND Module for Computing Magnetic Island Widths in Tokamaks,'' submitted to J. Plasma Physics (2005). [2] C.C. Hegna, 2002 Fusion Snowmass Meeting.

Halpern, F.; Pankin, A. Y.

2005-10-01

392

Symphysis pubis width and unaffected hip joint width in patients with slipped upper femoral epiphysis: widening compared with normal values  

International Nuclear Information System (INIS)

The exact pathomechanism of slipped upper femoral epiphysis (SUFE) remains elusive. This paper suggests a generalised abnormality of the development or maturation of cartilage as a possible cause. It is proposed that SUFE is part of a generalised abnormality of the cartilage formation or maturation resulting in abnormal measurements of cartilaginous joint structures. Radiographs of SUFE patients were assessed for the width of the unaffected hip joint and the symphysis pubis. Comparison with previously published normal values was made. Fifty-one patients were assessed, 35 male, 16 female. The average age was 12 years and 11 months combined for both sexes, 13 years 8 months for boys, 11 years 4 months for girls. Width of the symphysis pubis was assessed on 46 datasets, and comparison with normal values was performed using the Wilcoxon paired rank test. Statistical significance was set as p < 0.05. The average expected width was 5.8 mm (5.4-6.2 mm), the average measured width was 7.3 mm (3.5-12 mm), median value 7.0 mm, and the difference is statistically significant. Cartilage thickness of the uninvolved hip joint could be assessed in 46 cases, and comparison using the Wilcoxon paired rank test resulted in a statistically significant difference (significance set as p < 0.05). The average expected width was 4.9 mm (3.6-6.5 mm), the average measured width was 5.5 mm (4-8 mm), and median 5.3 mm. The results indicate that SUFE patients display a generalised increased width of joint cartilage for their age. This could be due to increased cartilage formation or decreased maturation or a combination of the two, and could explain the increased mechanical vulnerability of these children to normal or abnormal stresses, despite histologically normal organisation of the physis as shown in previous studies. (orig.)

393

Overtraining increases the strength of equivalence relations  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The present study investigated whether overtraining of the conditional discriminations that are the prerequisites of equivalence class formation strengthens the relations among stimuli in an equivalence class. Two groups of college students formed equivalence classes that consisted of faces that exp [...] ressed emotions (A) and arbitrary stimuli (B, C, D, and E). The overtraining group had twice as many training trials as the regular training group. For participants who formed equivalence classes, relational strength was evaluated by the generalization of expressed emotions from the A to the D stimuli, which was measured using a semantic differential. An untrained control group showed semantic differential scores that were positive for happy faces, negative for angry faces, and neutral for the D stimuli. For the experimental groups, the D stimuli, when included in equivalence classes, produced scores that were similar to those produced by the equivalent faces. The overtraining group, however, had average values closer to the values of the faces than the regular training group. These results indicate that the amount of training is an experimental parameter that influences the strength of relations between stimuli that are found to be equivalent in matching-to-sample tests.

Renato, Bortoloti; Naomi Cristina, Rodrigues; Mariéle Diniz, Cortez; Naiene, Pimentel; Julio C. de, Rose.

2013-12-01

394

Overtraining increases the strength of equivalence relations  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The present study investigated whether overtraining of the conditional discriminations that are the prerequisites of equivalence class formation strengthens the relations among stimuli in an equivalence class. Two groups of college students formed equivalence classes that consisted of faces that exp [...] ressed emotions (A) and arbitrary stimuli (B, C, D, and E). The overtraining group had twice as many training trials as the regular training group. For participants who formed equivalence classes, relational strength was evaluated by the generalization of expressed emotions from the A to the D stimuli, which was measured using a semantic differential. An untrained control group showed semantic differential scores that were positive for happy faces, negative for angry faces, and neutral for the D stimuli. For the experimental groups, the D stimuli, when included in equivalence classes, produced scores that were similar to those produced by the equivalent faces. The overtraining group, however, had average values closer to the values of the faces than the regular training group. These results indicate that the amount of training is an experimental parameter that influences the strength of relations between stimuli that are found to be equivalent in matching-to-sample tests.

Renato, Bortoloti; Naomi Cristina, Rodrigues; Mariéle Diniz, Cortez; Naiene, Pimentel; Julio C. de, Rose.

395

Modelling the widths of fission observables in GEF  

Directory of Open Access Journals (Sweden)

Full Text Available The widths of the mass distributions of the different fission channels are traced back to the probability distributions of the corresponding quantum oscillators that are coupled to the heat bath, which is formed by the intrinsic degrees of freedom of the fissioning system under the influence of pairing correlations and shell effects. Following conclusion from stochastic calculations of Adeev and Pashkevich, an early freezing due to dynamical effects is assumed. It is shown that the mass width of the fission channels in low-energy fission is strongly influenced by the zero-point motion of the corresponding quantum oscillator. The observed variation of the mass widths of the asymmetric fission channels with excitation energy is attributed to the energy-dependent properties of the heat bath and not to the population of excited states of the corresponding quantum oscillator.

Schmidt K.-H.

2013-03-01

396

Morphodynamics structures induced by variations of the channel width  

Science.gov (United States)

In alluvial channels, forcing effects, such as a longitudinally varying width, can induce the formation of steady bars (Olesen, 1984). The type of bars that form, such as alternate, central or multiple, will mainly depend on the local flow width-to-depth ratio and on upstream conditions (Struiksma et al., 1985). The effects on bar formation of varying the channel width received attention only recently and investigations, based on flume experiments and mathematical modelling, are mostly restricted to small longitudinal sinusoidal variations of the channel width (e.g. Repetto et al., 2002; Wu and Yeh, 2005, Zolezzi et al., 2012; Frascati and Lanzoni, 2013). In this work, we analyze the variations in equilibrium bed topography in a longitudinal width-varying channel with characteristic scales of the Waal River (The Netherlands) using two different 2D depth-averaged morphodynamic models, one based on the Delft3D code and one on Telemac-Mascaret system. In particular, we explore the effects of changing the wavelength of sinusoidal width variations in a straight channel, focusing on the effects of the spatial lag between bar formation and forcing that is observed in numerical models and laboratory experiments (e.g. Crosato et al, 2011). We extend the investigations to finite width variations in which longitudinal changes of the width-to-depth ratio are such that they may affect the type of bars that become unstable (alternate, central or multiple bars). Numerical results are qualitatively validated with field observations and the resulting morphodynamic pattern is compared with the physics-based predictor of river bar modes by Crosato and Mosselman (2009). The numerical models are finally used to analyse the experimental conditions of Wu and Yeh (2005). The study should be seen as merely exploratory. The aim is to investigate possible approaches for future research aiming at assessing the effects of artificial river widening and narrowing to control bar formation in alluvial rivers. References Crosato A. and Mosselman E., 2009. Simple physics-based predictor for the number of river bars and the transition between meandering and braiding. Water Resources Research, 45, W03424, doi: 10.1029/2008WR007242. Crosato A., Mosselman E., Desta F.B. and Uijttewaal W.S.J., 2011. Experimental and numerical evidence for intrinsic nonmigrating bars in alluvial channels. Water Resources Research, AGU, 47(3), W03511, doi 10.1029/2010WR009714. Frascati A. and Lanzoni S., 2013. A mathematical model for meandering rivers with varying width. J. Geophys. Res.Earth Surf., 118, doi:10.1002/jgrf.20084. Olesen K.W., 1984. Alternate bars in and meandering of alluvial rivers. In: River Meandering, Proc. of the Conf. Rivers '83, 24-26 Oct. 1983, New Orleans, Louisiana, U.S.A., ed. Elliott C.M., pp. 873-884, ASCE, New York. ISBN 0-87262-393-9. Repetto R., Tubino, M. and Paola C., 2002. Planimetric instability of channels with variable width. J. Fluid Mech., 457, 79-109. Struiksma N., Olesen K.W., Flokstra C. and De Vriend H.J., 1985. Bed deformation in curved alluvial channels. J. Hydraul. Res., 23(1), 57- 79. Wu F.-C. and Yeh T.-H., 2005. Forced bars induced by variations of channel width: Implications for incipient bifurcation. J. Geophys. Res., 110, F02009, doi:10.1029/2004JF000160. Zolezzi, G., R. Luchi, and M. Tubino (2012), Modeling morphodynamic processes in meandering rivers with spatial width variations, Rev. Geophys., 50, RG4005, doi:10.1029/2012RG000392.

Duro, Gonzalo; Crosato, Alessandra; Tassi, Pablo

2014-05-01

397

Thermal width and quarkonium dissociation by inelastic parton scattering  

CERN Document Server

In a weak-coupling effective field theory framework we study quarkonium dissociation induced by inelastic scattering with partons in the medium. This is the dominant dissociation process for temperatures such that the Debye mass is larger than the binding energy. We evaluate the dissociation cross section and the corresponding thermal decay width. At leading order we derive a convolution formula relating the two, which is consistent with the optical theorem and QCD at finite temperature. Bound state effects are systematically included. They add contributions to the cross section and width that are beyond a quasi-free approximation, whose validity is critically reviewed. For temperatures such that the Debye mass is smaller than the binding energy, the dominant dissociation mechanism is gluo-dissociation consisting in quarkonium dissociation induced by the absorbtion of a gluon from the medium. We calculate the gluo-dissociation cross section and width at next-to-leading-order accuracy.

Brambilla, Nora; Ghiglieri, Jacopo; Vairo, Antonio

2013-01-01

398

New Measurement of the ?0 Radiative Decay Width  

International Nuclear Information System (INIS)

High precision measurements of the differential cross sections for ?0 photoproduction at forward angles for two nuclei, 12C and 208Pb, have been performed for incident photon energies of 4.9-5.5 GeV to extract the ?0??? decay width. The experiment was done at Jefferson Lab using the Hall B photon tagger and a high-resolution multichannel calorimeter. The ?0??? decay width was extracted by fitting the measured cross sections using recently updated theoretical models for the process. The resulting value for the decay width is ?(?0???)=7.82±0.14(stat)±0.17(syst) eV. With the 2.8% total uncertainty, this result is a factor of 2.5 more precise than the current Particle Data Group average of this fundamental quantity, and it is consistent with current theoretical predictions.

399

Domain Wall Width in Different Ferroelectrics via Perturbation Route  

Directory of Open Access Journals (Sweden)

Full Text Available The domains are of fundamental interest for engineering a ferroelectric material. The domain wall and its width control the ferroelectric behavior to a great extent. The stability of polarization in the context of Landau-Ginzburg free energy functional has been worked out in a previous work by a perturbation approach, where two limits of domain wall width were estimated within the stability zone and they were also found to correspond well with the data on lithium niobate and lithium tantalate. In the present work, it is shown that this model is valid for a wide range of ferroelectric materials and also for a given ferroelectric, such as lithium niobate with different levels of impurities, which are known to affect the domain wall width.

Pratap C. Ray

2012-05-01

400

The width of the $\\omega$ meson in dense matter  

CERN Document Server

We obtain the width of the $\\omega$ meson in dense nuclear matter by taking into account (i) the free decay of the $\\omega$ into three pions, which is dominated by $\\rho \\pi$ mode, (ii) the processes induced by a vector-baryon interaction dominated by vector meson exchange, and (iii) the $\\omega \\to K \\bar K$ mechanism in matter. The $\\omega$ meson develops an important width in matter, coming from the dominant $\\omega \\to \\rho\\pi$ decay mode, with a value of $121 \\pm 10$ MeV at normal nuclear matter density for an $\\omega$ at rest. At finite momentum, the width of the $\\omega$ meson increases moderately with values of 200 MeV at 600 MeV/c.

Tolos, Laura; Oset, Eulogio; Ramos, Angels

2014-01-01

 
 
 
 
401

New Measurement of the ?0 radiative decay width.  

Science.gov (United States)

High precision measurements of the differential cross sections for ?0 photoproduction at forward angles for two nuclei, 12C and 208Pb, have been performed for incident photon energies of 4.9-5.5 GeV to extract the ?0??? decay width. The experiment was done at Jefferson Lab using the Hall B photon tagger and a high-resolution multichannel calorimeter. The ?0??? decay width was extracted by fitting the measured cross sections using recently updated theoretical models for the process. The resulting value for the decay width is ?(?0???)=7.82±0.14(stat)±0.17(syst)??eV. With the 2.8% total uncertainty, this result is a factor of 2.5 more precise than the current Particle Data Group average of this fundamental quantity, and it is consistent with current theoretical predictions. PMID:21599360

Larin, I; McNulty, D; Clinton, E; Ambrozewicz, P; Lawrence, D; Nakagawa, I; Prok, Y; Teymurazyan, A; Ahmidouch, A; Asratyan, A; Baker, K; Benton, L; Bernstein, A M; Burkert, V; Cole, P; Collins, P; Dale, D; Danagoulian, S; Davidenko, G; Demirchyan, R; Deur, A; Dolgolenko, A; Dzyubenko, G; Ent, R; Evdokimov, A; Feng, J; Gabrielyan, M; Gan, L; Gasparian, A; Gevorkyan, S; Glamazdin, A; Goryachev, V; Gyurjyan, V; Hardy, K; He, J; Ito, M; Jiang, L; Kashy, D; Khandaker, M; Kingsberry, P; Kolarkar, A; Konchatnyi, M; Korchin, A; Korsch, W; Kowalski, S; Kubantsev, M; Kubarovsky, V; Li, X; Martel, P; Matveev, V; Mecking, B; Milbrath, B; Minehart, R; Miskimen, R; Mochalov, V; Mtingwa, S; Overby, S; Pasyuk, E; Payen, M; Pedroni, R; Ritchie, B; Rodrigues, T E; Salgado, C; Shahinyan, A; Sitnikov, A; Sober, D; Stepanyan, S; Stephens, W; Underwood, J; Vasiliev, A; Vishnyakov, V; Wood, M; Zhou, S

2011-04-22

402

Comprehensive intermaxillary tooth width proportion of Bangkok residents  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Proper occlusion depends on the correct width ratio between upper and lower teeth, known as Bolton's ratio. In fact, this ratio can be calculated for each pair of teeth from the central incisor to the first permanent molar. This set of ratios, known as comprehensive cumulative percentage ratios (CPR [...] s), can be used not only to determine which tooth or teeth have a tooth width discrepancy, but can also enable the partial graphical analysis of tooth width discrepancy when there is agenesis of certain permanent teeth. Although CPRs have been calculated for Caucasians, tooth width is known to vary depending on racial origin. Therefore, a test of differences between racial groups should be carried out. If these ratios of the Caucasians and Bangkokians are significantly different, the ratio of the Bangkokians is recommended. The objective of this study was to measure tooth size disproportion for Thai patients and to calculate a corresponding set of CPRs. Thirty-seven pairs of dental models were made from a group of Bangkok residents with normal occlusion. Mesiodistal tooth width was measured for each model. The intra- and inter-examiner measurement errors were ascertained as insignificant (p > 0.05). CPRs were then calculated and compared to those derived from other studies. Ten of thirteen CPRs were significantly different from corresponding values derived from Caucasians. We conclude that tooth width ratios vary between different racial groups, and therefore that these should be calculated specifically for each patient racial group.

Somchai, Manopatanakul; Narumon, Watanawirun.

2011-04-01

403

Geometry of the local equivalence of states  

International Nuclear Information System (INIS)

We present a description of locally equivalent states in terms of symplectic geometry. Using the moment map between local orbits in the space of states and coadjoint orbits of the local unitary group, we reduce the problem of local unitary equivalence to an easy part consisting of identifying the proper coadjoint orbit and a harder problem of the geometry of fibers of the moment map. We give a detailed analysis of the properties of orbits of ‘equally entangled states’. In particular, we show connections between certain symplectic properties of orbits such as their isotropy and coisotropy with effective criteria of local unitary equivalence. (paper)

404

Simultaneity as an Invariant Equivalence relation  

CERN Document Server

This paper deals with the concept of simultaneity in classical and relativistic physics as construed in terms of group-invariant equivalence relations. A full examination of Newton, Galilei and Poincar\\'e invariant equivalence relations in $\\R^4$ is presented, which provides alternative proofs, additions and occasionally corrections of results in the literature, including Malament's theorem and some of its variants. It is argued that the interpretation of simultaneity as an invariant equivalence relation, although mathematically interesting, does not cut in the debate concerning the conventionality of simultaneity in special relativity.

Mamone-Capria, Marco

2012-01-01

405

Simultaneity as an Invariant Equivalence Relation  

Science.gov (United States)

This paper deals with the concept of simultaneity in classical and relativistic physics as construed in terms of group-invariant equivalence relations. A full examination of Newton, Galilei and Poincaré invariant equivalence relations in ?4 is presented, which provides alternative proofs, additions and occasionally corrections of results in the literature, including Malament's theorem and some of its variants. It is argued that the interpretation of simultaneity as an invariant equivalence relation, although interesting for its own sake, does not cut in the debate concerning the conventionality of simultaneity in special relativity.

Mamone-Capria, Marco

2012-11-01

406

The absorption theorem for affable equivalence relations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We prove a result about extension of a minimal AF-equivalence relation R on the Cantor set X, the extension being `small' in the sense that we modify R on a thin closed subset Y of X. We show that the resulting extended equivalence relation S is orbit equivalent to the original R, and so, in particular, S is affable. Even in the simplest case--when Y is a finite set--this result is highly non-trivial. The result itself--called the absorption theorem--is a powerful and crucia...

Giordano, Thierry; Matui, Hiroki; Putnam, Ian F.; Skau, Christian F.

2007-01-01

407

Validity of the Principle of Dynamic Equivalence  

Directory of Open Access Journals (Sweden)

Full Text Available The principle of dynamic equivalence aims at arousing similar response between the source text readers and the target text readers. To achieve this goal, a D-E translation should strive for the "closest natural equivalent" of the source text. This approach toward translation is of great validity which is based on linguistic commonness of all langages and cultural and psychological similarities of all human beings. The former enables the possibility of faithful reproduction of the original message, namely, the "closest natural equivalent of the source- language message" while the latter guarantee the possibility of "similar response."

Yinhua Xiang

2012-01-01

408

Geometry of the local equivalence of states  

Energy Technology Data Exchange (ETDEWEB)

We present a description of locally equivalent states in terms of symplectic geometry. Using the moment map between local orbits in the space of states and coadjoint orbits of the local unitary group, we reduce the problem of local unitary equivalence to an easy part consisting of identifying the proper coadjoint orbit and a harder problem of the geometry of fibers of the moment map. We give a detailed analysis of the properties of orbits of 'equally entangled states'. In particular, we show connections between certain symplectic properties of orbits such as their isotropy and coisotropy with effective criteria of local unitary equivalence. (paper)

Sawicki, A; Kus, M, E-mail: assawi@cft.edu.pl, E-mail: marek.kus@cft.edu.pl [Center for Theoretical Physics, Polish Academy of Sciences, Al Lotnikow 32/46, 02-668 Warszawa (Poland)

2011-12-09

409

Reduced alpha widths for nuclei with N?84,Z?84  

International Nuclear Information System (INIS)

The reduced alpha widths of even-even nuclei with N?84,Z?84 display a systematic behavior with only few anomalies. The widths were deduced from the known alpha-decay half-lives and branching ratios, with penetration factors calculated from realistic cluster wave functions. Predictions are reported for the half-lives of naturally occurring long-lived nuclei as well as the half-lives and branching ratios of short-lived proton-rich nuclei away from the line of beta stability

410

Radiative decay widths of mesons in a relativistic potential model  

Energy Technology Data Exchange (ETDEWEB)

The M1 transition among the low-lying vector and pseudoscalar mesons is investigated in a relativistic potential model of independent quarks. A static calculation of the partial decay widths of several possible M1 transitions is performed within the conventional picture of photon emission by a confined quark and/or antiquark. The model parameters are determined from a fit to the mass splittings of ground-state mesons in the strange, charm and bottom flavour sectors. The model accounts well for the observed decay widths of light mesons and predict decay rates of heavy mesons which are comparable with those of other model calculations. (author)

Jena, S.N.; Panda, P.; Sahu, K.P. [Physics Department, Berhampur University, Berhampur, Orissa (India)

2001-07-01

411

Radiative decay widths of mesons in a relativistic potential model  

International Nuclear Information System (INIS)

The M1 transition among the low-lying vector and pseudoscalar mesons is investigated in a relativistic potential model of independent quarks. A static calculation of the partial decay widths of several possible M1 transitions is performed within the conventional picture of photon emission by a confined quark and/or antiquark. The model parameters are determined from a fit to the mass splittings of ground-state mesons in the strange, charm and bottom flavour sectors. The model accounts well for the observed decay widths of light mesons and predict decay rates of heavy mesons which are comparable with those of other model calculations. (author)

412

Study of GDR width from angular momentum gated measurements  

International Nuclear Information System (INIS)

The study of high energy photons from the decay of the giant dipole resonance (GDR) built on excited states can provide information on the diverse properties of the nucleus like its shape and orientation fluctuations at finite temperature (T) and angular momentum (J). The influence of T and J on the width of the GDR (?) in hot rotating nuclei is a topic of current interest. The extraction of the GDR width from angular momentum gated measurements in the mass region A? 86 has been reported

413

Efficient algorithms for estimating the width of nearly normal distributions  

International Nuclear Information System (INIS)

Typical physics data samples often conform to Gaussian distributions with admixtures of more slowly varying backgrounds. Under such circumstances the standard deviation is known to be a poor statistical measure of distribution width. As an alternative, the performance of Gini's mean difference is compared with the standard deviation and the mean deviation. Variants which sum over subsets of all possible pairs are shown to have statistical efficiencies comparable to the mean difference and mean deviation but do not require extensive data storage or a priori knowledge of the sample mean. These statistics are reasonable candidates for monitoring the distribution width of a real time data stream. (orig.)

414

Fjords in viscous fingering: selection of width and opening scale  

Energy Technology Data Exchange (ETDEWEB)

Our experiments on viscous fingering of air into oil contained between closely spaced plates reveal two selection rules for the fjords of oil that separate fingers of air. (Fjords are the building blocks of solutions of the zero-surface-tension Laplacian growth equation.) Experiments in rectangular and circular geometries yield fjords with base widths {lambda}{sub c}/2, where {lambda}{sub c} is the most unstable wavelength from a linear stability analysis. Further, fjords open at an angle of 8.0{sup o}{+-}1.0{sup o}. These selection rules hold for a wide range of pumping rates and fjord lengths, widths, and directions.

Mineev-weinstein, Mark [Los Alamos National Laboratory; Ristroph, Leif [UT-AUSTIN; Thrasher, Matthew [UT-AUSTIN; Swinney, Harry [UT-AUSTIN

2008-01-01

415

Two-photon decay width of the sigma meson  

International Nuclear Information System (INIS)

We shortly report on the two-photon decay width of the light ?-meson interpreted as a quarkonium state. Results are given in dependence on the ?-mass and the constituent mass of the light quark. The triangle quark-loop diagram, responsible for the two-photon transition, is carefully evaluated: a term in the transition amplitude, often omitted in literature, results in destructive interference with the leading term. As a result we show that the two-photon decay width of the ? in the quarkonium picture is less than 1 keV for the physical range of parameters

416

X-ray line widths and coronal heating  

Science.gov (United States)

Preliminary results of spectroscopy and imaging of a solar active region and flare plasma in soft X-ray emission lines are presented. Observed X-ray line widths in a nonflaring active region are broader than the Doppler width corresponding to the local electron temperature. An analysis of 41 soft X-ray flares within a single active region reveals a preference for flares to occur at locations that already show enhanced X-ray emission and to favor magnetic complexity over high gradient. However, flares do not appear to be directly responsible for the heating and X-ray production of the active regions.

Acton, L. W.; Wolfson, C. J.; Joki, E. G.; Culhane, J. L.; Rapley, C. G.; Bentley, R. D.; Gabriel, A. H.; Phillips, K. J. H.; Hayes, R. W.; Antonucci, E.

1981-01-01

417

X-ray line widths and coronal heating  

International Nuclear Information System (INIS)

We present preliminary results of spectroscopy and imaging of a solar active region and flare plasma in soft X-ray emission lines. Observed X-ray line widths in a nonflaring active region are broader than the Doppler width corresponding to the local electron temperature. An analysis of 41 soft X-ray flares within a single active region reveals a preference for flares to occur at locations that already show enhanced X-ray emission and to favor magnetic complexity over high gradient. However, flares do not appear to be directly responsible for the heating and X-ray production of the active regions

418

Finite width effects on magnetostatic surface wave propagation  

International Nuclear Information System (INIS)

A model is proposed for the propagation of magnetostatic surface waves in a layered structure consisting of a ground plane and a YIG film separated by a dielectric. The standard assumption of an infinite sample width is replaced with an assumption of a sinusoidal transverse distribution of rf fields. Instead of a single solution, a multiplicity of solutions is found, each with a distinct dispersion relation. Experimental observation of the first two finite-width modes is in excellent agreement with predicted results derived from the model

419

Dose equivalent index for fast electrons  

International Nuclear Information System (INIS)

Monte Carlo calculations of the deep and shallow dose equivalent index produced by electron beams in the energy region 5-22 MeV have been performed for unidirectional, opposing, rotating and isotropic irradiations of the spherical tissue equivalent phantom. The observed dose maxima are attributed to multiple scattering and range effects and occur in the outer 10 mm shell. The isotropy factor varies from 2.48 at 5 MeV to 1.89 at 22 MeV. The signal of a detector with isotropic response and wall thickness 0.5 g/cm2 is shown to be a suitable measure of dose equivalent index for fast electrons. The average dose equivalent in the spherical phantom is discussed as an alternative concept. (author)

420

The equivalent fundamental-mode source  

International Nuclear Information System (INIS)

In 1960, Hansen analyzed the problem of assembling fissionable material in the presence of a weak neutron source. Using point kinetics, he defined the weak source condition and analyzed the consequences of delayed initiation during ramp reactivity additions. Although not clearly stated in Hansen's work, the neutron source strength that appears in the weak source condition corresponds to the equivalent fundamental-mode source. In this work, we describe the concept of an equivalent fundamental-mode source and we derive a deterministic expression for a factor, g*, that converts any arbitrary source distribution to an equivalent fundamental-mode source. We also demonstrate a simplified method for calculating g* in subcritical systems. And finally, we present a new experimental method that can be employed to measure the equivalent fundamental-mode source strength in a multiplying assembly. We demonstrate the method on the zero-power, XIX-1 assembly at the Fast Critical Assembly (FCA) Facility, Japan Atomic Energy Research Institute (JAERI)

 
 
 
 
421

The Economist Interactive: Equivalent Country Comparisons  

Science.gov (United States)

This interactive tools allows the user to learn which countries parallel the states, provinces or territories of the United States, China, India and Brazil and  presents country equivalent data for both GDP and population.

422

Bisimulations Meet PCTL Equivalences for Probabilistic Automata  

DEFF Research Database (Denmark)

Probabilistic automata (PA) [20] have been successfully applied in the formal verification of concurrent and stochastic systems. Efficient model checking algorithms have been studied, where the most often used logics for expressing properties are based on PCTL [11] and its extension PCTL? [4]. Various behavioral equivalences are proposed for PAs, as a powerful tool for abstraction and compositional minimization for PAs. Unfortunately, the behavioral equivalences are well-known to be strictly stronger than the logical equivalences induced by PCTL or PCTL?. This paper introduces novel notions of strong bisimulation relations, which characterizes PCTL and PCTL? exactly.We also extend weak bisimulations characterizing PCTL and PCTL? without next operator, respectively. Thus, our paper bridges the gap between logical and behavioral equivalences in this setting.

Zhang, Lijun; Godskesen, Jens Chr.

2011-01-01

423

Bisimulations Meet PCTL Equivalences for Probabilistic Automata  

CERN Document Server

Probabilistic automata (PA) have been successfully applied in the formal verification of concurrent and stochastic systems. Efficient model checking algorithms have been studied, where the most often used logics for expressing properties are based on PCTL and its extension PCTL*. Various behavioral equivalences are proposed for PAs, as a powerful tool for abstraction and compositional minimization for PAs. Unfortunately, the behavioral equivalences are well-known to be strictly stronger than the logical equivalences induced by PCTL or PCTL*. This paper introduces novel notions of strong bisimulation relations, which characterizes PCTL and PCTL* exactly. We also extend weak bisimulations characterizing PCTL and PCTL* without next operator, respectively. Thus, our paper bridges the gap between logical and behavioral equivalences in this setting.

Song, Lei; Godskesen, Jens Chr

2011-01-01

424

The Field Of Equivalent Some Numeral Methods  

Directory of Open Access Journals (Sweden)

Full Text Available This paper describes some properties of methods for numeral solving partial differential equations. A number of identities are proved to show there are regions of equivalency for finite differences methods and finite elements Ritz-method.

I. S. Kashirsky

2008-05-01

425

Equivalent multipole operators for degenerate Rydberg states  

International Nuclear Information System (INIS)

As shown by Pauli, [Z. Phys. 36, 336 (1926)], the electric dipole operator r can be replaced by the Runge-Lenz vector A when operating within the n2 degenerate manifold of hydrogenic states of principal quantum number n. We seek to develop similar rules for higher multipole operators by expressing equivalent operators in terms only of the two vector constants of motion - the orbital angular momentum L and the Runge-Lenz vector A - appropriate to the degenerate hydrogenic shell. Equivalence of two operators means here that they yield identical matrix elements within a subspace of Hilbert space that corresponds to fixed n. Such equivalent-operator techniques permit direct algebraic calculation of perturbations of Rydberg atoms by external fields and often exact analytical results for transition probabilities. Explicit expressions for equivalent quadrupole and octupole operators are derived, examples are provided, and general aspects of the problem are discussed

426

Nuclear Regulatory Commission equivalency evaluation report  

International Nuclear Information System (INIS)

This paper provides the basis for concluding that using the seismic design criteria, defined in DOE order 4580.28, Natural Phenomena Hazards Mitigation, and its implementing standards provides safety equivalent to NRC criteria

427

Asymptotic equivalence of sequences and summability  

Directory of Open Access Journals (Sweden)

Full Text Available For a sequence-to-sequence transformation A, let RmAx=∑n≥m|(Axn| and μmAx=supn≥m|(Axn|. The purpose of this paper is to study the relationship between the asymptotic equivalence of two sequences (limnxn/yn=1 and the variations of asymptotic equivalence based on the ratios RmAx/RmAy and μmAx/μmAy.

Jinlu Li

1997-12-01

428

Dark matter and the equivalence principle  

Science.gov (United States)

A survey is presented of the current understanding of dark matter invoked by astrophysical theory and cosmology. Einstein's equivalence principle asserts that local measurements cannot distinguish a system at rest in a gravitational field from one that is in uniform acceleration in empty space. Recent test-methods for the equivalence principle are presently discussed as bases for testing of dark matter scenarios involving the long-range forces between either baryonic or nonbaryonic dark matter and ordinary matter.

Frieman, Joshua A.; Gradwohl, Ben-Ami

1993-01-01

429

Methods for Equivalence and Noninferiority Testing  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Classical hypothesis testing focuses on testing whether treatments have differential effects on outcome. However, sometimes clinicians may be more interested in determining whether treatments are equivalent or whether one has noninferior outcomes. We review the hypotheses for these noninferiority and equivalence research questions, consider power and sample size issues, and discuss how to perform such a test for both binary and survival outcomes. The methods are illustrated on 2 recent studie...

Silva, Gisela Tunes Da; Logan, Brent R.; Klein, John P.

2009-01-01

430

Refining the Proof of Planar Equivalence  

CERN Document Server

We outline a full non-perturbative proof of planar (large-N) equivalence between bosonic correlators in a theory with Majorana fermions in the adjoint representation and one with Dirac fermions in the two-index (anti)symmetric representation. In a particular case (one flavor), this reduces to our previous result - planar equivalence between super-Yang--Mills theory and a non-supersymmetric ``orientifold field theory.'' The latter theory becomes one-flavor massless QCD at N=3.

Armoni, A; Veneziano, Gabriele

2005-01-01

431

Equivalent Hermitian operator from supersymmetric quantum mechanics  

International Nuclear Information System (INIS)

Full text: (author)The metric operator ?, which is the basic ingredient for studying a quantum system described by a pseudo-Hermitian Hamiltonian H, provides the necessary means for obtaining an equivalent description of the system using a Hermitian Hamiltonian h. In the framework of supersymmetric quantum mechanics, we propose a method of constructing the metric operators ? and ?? to obtain the Hermitian Hamiltonians h and h? equivalent to the pseudo-Hermitian H and H+

432

Explicit Homotopy Equivalences Between Some Operads  

CERN Document Server

In this work we present an explicit operad morphism that is also a homotopy equivalence between the operad given by the real Fulton MacPherson compactification of configuration spaces and the little $n$-disks operad. In particular, the construction gives an operadic homotopy equivalence between the associahedra and the little intervals explicitly. It can also be extended to the case of Kontsevich compactification and Voronov swiss-cheese operad.

Hoefel, Eduardo

2011-01-01

433

S-equivalents lagrangians in generalized mechanics  

International Nuclear Information System (INIS)

The problem of s-equivalent lagrangians is considered in the realm of generalized mechanics. Some results corresponding to the ordinary (non-generalized) mechanics are extended to the generalized case. A theorem for the reduction of the higher order lagrangian description to the usual order is found to be useful for the analysis of generalized mechanical systems and leads to a new class of equivalence between lagrangian functions. Some new perspectives are pointed out. (Author)

434