Science.gov

Sample records for albeit ultraviolet bright

  1. Extreme Ultraviolet Explorer Bright Source List

    NASA Technical Reports Server (NTRS)

    Malina, Roger F.; Marshall, Herman L.; Antia, Behram; Christian, Carol A.; Dobson, Carl A.; Finley, David S.; Fruscione, Antonella; Girouard, Forrest R.; Hawkins, Isabel; Jelinsky, Patrick

    1994-01-01

    Initial results from the analysis of the Extreme Ultraviolet Explorer (EUVE) all-sky survey (58-740 A) and deep survey (67-364 A) are presented through the EUVE Bright Source List (BSL). The BSL contains 356 confirmed extreme ultraviolet (EUV) point sources with supporting information, including positions, observed EUV count rates, and the identification of possible optical counterparts. One-hundred twenty-six sources have been detected longward of 200 A.

  2. Bright tunable ultraviolet squeezed light.

    PubMed

    Bell, A S; Riis, E; Ferguson, A I

    1997-04-15

    We have produced bright tunable squeezed light by second-harmonic generation in a singly resonant cavity. We have investigated the effect of input coupling and fundamental power on the squeezing. Up to 400 mW of continuous-wave mode-locked tunable squeezed light was produced at wavelengths as short as 389 nm, and more than 1.5 dB of squeezing was inferred.

  3. An ultraviolet imager to study bright UV sources

    NASA Astrophysics Data System (ADS)

    Mathew, Joice; Prakash, Ajin; Sarpotdar, Mayuresh; Sreejith, A. G.; Safonova, Margarita; Murthy, Jayant

    2016-07-01

    We have designed and developed a compact ultraviolet imaging payload to y on a range of possible platforms such as high altitude balloon experiments, cubesats, space missions, etc. The primary science goals are to study the bright UV sources (mag < 10) and also to look for transients in the Near UV (200 - 300 nm) domain. Our first choice is to place this instrument on a spacecraft going to the Moon as part of the Indian entry into Google lunar X-Prize competition. The major constraints for the instrument are, it should be lightweight (< 2Kg), compact (length < 50cm) and cost effective. The instrument is an 80 mm diameter Cassegrain telescope with a field of view of around half a degree designated for UV imaging. In this paper we will discuss about the various science cases that can be performed by having observations with the instrument on different platforms. We will also describe the design, development and the current state of implementation of the instrument. This includes opto-mechanical and electrical design of the instrument. We have adopted an all spherical optical design which would make the system less complex to realize and a cost effective solution compared to other telescope configuration. The structural design has been chosen in such a way that it will ensure that the instrument could withstand all the launch load vibrations. An FPGA based electronics board is used for the data acquisition, processing and CCD control. We will also brie y discuss about the hardware implementation of the detector interface and algorithms for the detector readout and data processing.

  4. Observations of ultraviolet-bright stars in globular clusters with the Hopkins Ultraviolet Telescope

    NASA Technical Reports Server (NTRS)

    Van Dyke Dixon, W.; Davidsen, Arthur F.; Ferguson, Henry C.

    1994-01-01

    Two UV-bright stars in globular clusters, UV5 in NGC 1851 and vZ 1128 in M3, were observed with the Hopkins Ultraviolet Telescope (HUT) during the Astro-1 space shuttle mission in 1990 December. The stars' spectra show weak absorption features and no significant emission features other than well known geocoronal lines. Detailed fitting of Kurucz (1991) stellar atmosphere models using a chi(sup 2) minimization technique indicates T(sub eff) = 16 000 K, log g = 2.5, and abundance (-1.0) (logarithm of abundance of elements heavier than helium relative to solar) for UV5, and T(sub eff) = 35 000 K, log g = 4.0, and abundance (-3.5) for vZ 1128. The Kurucz model which best fits vZ 1128 overpredicts the flux in the region below approximately 1000 A, an effect seen in previous models of O-type stars. Our results are robust (to within approximately 1000 K) with respect to uncertainties in interstellar reddening and atomic and molecular hydrogen column densities. We do not see significant molecular hydrogen absorption, which might have indicated material in a circumstellar shell, in either star's spectrum. We estimate the stellar luminosities to be log L/solar luminosity = 3.33 +/- 0.15 for UV5 and log L/solar luminosity = 3.21 +/- 0.12 for vZ 1128. These atmospheric parameters place both stars on the Schoenberner (post-AGB) tracks, though the stellar masses derived from the best-fitting Kurucz models are somewhat less than those predicted by the Schoenberner models. Examination of individual absorption line strengths reveals no significant abundance anomalies in either star.

  5. Observations of the Ultraviolet-Bright Type IIP Supernova ASASSN-14ha

    NASA Astrophysics Data System (ADS)

    Quick, Andrew; Brown, Peter J.; Suntzeff, Nicholas B.

    2017-01-01

    We present ASASSN-14ha, an ultraviolet-bright type IIP supernova (SN) observed by the Swift Ultra- Violet/Optical Telescope (UVOT). Swift/UVOT has observed numerous SNe II, mostly at very low redshifts, giving a great sampling of the fading UV flux and the changing fraction of luminosity coming from the ultraviolet (UV). We present photometric properties of a sample of Type IIP SNe from the Swift Optical/Ultraviolet Supernova Archive (SOUSA), comparing their absolute magnitudes and color evolution. Through comparison to other Type IIP SNe observed by Swift, we find ASASSN-14ha to be the bluest of the sample in the UV colors while demonstrating normal behavior in the optical. We further compare ASASSN-14ha to models of Type IIP SNe to explore which progenitor parameters could explain it’s unique color behavior.

  6. Numerical evaluation of a 13.5-nm high-brightness microplasma extreme ultraviolet source

    SciTech Connect

    Hara, Hiroyuki Arai, Goki; Dinh, Thanh-Hung; Higashiguchi, Takeshi; Jiang, Weihua; Miura, Taisuke; Endo, Akira; Ejima, Takeo; Li, Bowen; Dunne, Padraig; O'Sullivan, Gerry; Sunahara, Atsushi

    2015-11-21

    The extreme ultraviolet (EUV) emission and its spatial distribution as well as plasma parameters in a microplasma high-brightness light source are characterized by the use of a two-dimensional radiation hydrodynamic simulation. The expected EUV source size, which is determined by the expansion of the microplasma due to hydrodynamic motion, was evaluated to be 16 μm (full width) and was almost reproduced by the experimental result which showed an emission source diameter of 18–20 μm at a laser pulse duration of 150 ps [full width at half-maximum]. The numerical simulation suggests that high brightness EUV sources should be produced by use of a dot target based microplasma with a source diameter of about 20 μm.

  7. Evolution of laser-produced Sn extreme ultraviolet source diameter for high-brightness source

    SciTech Connect

    Roy, Amitava E-mail: aroy@barc.gov.in; Arai, Goki; Hara, Hiroyuki; Higashiguchi, Takeshi; Ohashi, Hayato; Sunahara, Atsushi; Li, Bowen; Dunne, Padraig; O'Sullivan, Gerry; Miura, Taisuke; Mocek, Tomas; Endo, Akira

    2014-08-18

    We have investigated the effect of irradiation of solid Sn targets with laser pulses of sub-ns duration and sub-mJ energy on the diameter of the extreme ultraviolet (EUV) emitting region and source conversion efficiency. It was found that an in-band EUV source diameter as low as 18 μm was produced due to the short scale length of a plasma produced by a sub-ns laser. Most of the EUV emission occurs in a narrow region with a plasma density close to the critical density value. Such EUV sources are suitable for high brightness and high repetition rate metrology applications.

  8. Stable droplet generator for a high brightness laser produced plasma extreme ultraviolet source

    NASA Astrophysics Data System (ADS)

    Vinokhodov, A.; Krivokorytov, M.; Sidelnikov, Yu.; Krivtsun, V.; Medvedev, V.; Bushuev, V.; Koshelev, K.; Glushkov, D.; Ellwi, S.

    2016-10-01

    We present the results of the low-melting liquid metal droplets generation based on excited Rayleigh jet breakup. We discuss on the operation of the industrial and in-house designed and manufactured dispensing devices for the droplets generation. Droplet diameter can be varied in the range of 30-90 μm. The working frequency of the droplets, velocity, and the operating temperature were in the ranges of 20-150 kHz, 4-15 m/s, and up to 250 °C, respectively. The standard deviations for the droplet center of mass position both their diameter σ < 1 μm at the distance of 45 mm from the nozzle. Stable operation in the long-term (over 1.5 h) was demonstrated for a wide range of the droplet parameters: diameters, frequencies, and velocities. Physical factors affecting the stability of the generator operation have been identified. The technique for droplet synchronization, allowing using the droplet as a target for laser produced plasma, has been created; in particular, the generator has been successfully used in a high brightness extreme ultraviolet (EUV) light source. The operation with frequency up to 8 kHz was demonstrated as a result of the experimental simulation, which can provide an average brightness of the EUV source up to ˜1.2 kW/mm2 sr.

  9. Droplet-based, high-brightness extreme ultraviolet laser plasma source for metrology

    NASA Astrophysics Data System (ADS)

    Vinokhodov, A. Yu.; Krivokorytov, M. S.; Sidelnikov, Yu. V.; Krivtsun, V. M.; Medvedev, V. V.; Koshelev, K. N.

    2016-10-01

    We report on the development of a high brightness source of extreme ultraviolet radiation (EUV) with a working wavelength of 13.5 nm. The source is based on a laser-produced plasma driven by pulsed radiation of a Nd:YAG laser system. Liquid droplets of Sn-In eutectic alloy were used as the source fuel. The droplets were created by a droplet generator operating in the jet break-up regime. The EUV emission properties of the plasma, including the emission spectrum, time profile, and conversion efficiency of laser radiation into useful 13.5 nm photons, have been characterized. Using the shadowgraphy technique, we demonstrated the production of corpuscular debris by the plasma source and the influence of the plasma on the neighboring droplet targets. The high-frequency laser operation was simulated by usage of the dual pulse regime. Based on the experimental results, we discuss the physical phenomena that could affect the source operation at high repetition rates. Finally, we estimate that an average source brightness of 1.2 kW/mm2 sr is feasible at a high repetition rate.

  10. Extended Ultraviolet Disks and Ultraviolet-bright Disks in Low-mass E/S0 Galaxies

    NASA Astrophysics Data System (ADS)

    Moffett, Amanda J.; Kannappan, Sheila J.; Baker, Andrew J.; Laine, Seppo

    2012-01-01

    We have identified 15 extended ultraviolet (XUV) disks in a largely field sample of 38 E/S0 galaxies that have stellar masses primarily below ~4 × 1010 M ⊙ and comparable numbers on the red and blue sequences. We use a new purely quantitative XUV-disk definition designed with reference to the "Type 1" XUV-disk definition found in the literature, requiring UV extension relative to a UV-defined star formation threshold radius. The 39% ± 9% XUV-disk frequency for these E/S0s is roughly twice the ~20% reported for late-type galaxies (although differences in XUV-disk criteria complicate the comparison), possibly indicating that XUV disks are preferentially associated with galaxies experiencing weak or inefficient star formation. Consistent with this interpretation, we find that the XUV disks in our sample do not correlate with enhanced outer-disk star formation as traced by blue optical outer-disk colors. However, UV-Bright (UV-B) disk galaxies with blue UV colors outside their optical 50% light radii do display enhanced optical outer-disk star formation as well as enhanced atomic gas content. UV-B disks occur in our E/S0s with a 42+9 -8% frequency and need not coincide with XUV disks; thus their combined frequency is 61% ± 9%. For both XUV and UV-B disks, UV colors typically imply <1 Gyr ages, and most such disks extend beyond the optical R 25 radius. XUV disks occur over the full sample mass range and on both the red and blue sequences, suggesting an association with galaxy interactions or another similarly general evolutionary process. In contrast, UV-B disks favor the blue sequence and may also prefer low masses, perhaps reflecting the onset of cold-mode gas accretion or another mass-dependent evolutionary process. Virtually all blue E/S0s in the gas-rich regime below stellar mass M t ~ 5 × 109 M ⊙ (the "gas-richness threshold mass") display UV-B disks, supporting the previously suggested association of this population with active disk growth.

  11. EXTENDED ULTRAVIOLET DISKS AND ULTRAVIOLET-BRIGHT DISKS IN LOW-MASS E/S0 GALAXIES

    SciTech Connect

    Moffett, Amanda J.; Kannappan, Sheila J.; Baker, Andrew J.; Laine, Seppo

    2012-01-20

    We have identified 15 extended ultraviolet (XUV) disks in a largely field sample of 38 E/S0 galaxies that have stellar masses primarily below {approx}4 Multiplication-Sign 10{sup 10} M{sub Sun} and comparable numbers on the red and blue sequences. We use a new purely quantitative XUV-disk definition designed with reference to the 'Type 1' XUV-disk definition found in the literature, requiring UV extension relative to a UV-defined star formation threshold radius. The 39% {+-} 9% XUV-disk frequency for these E/S0s is roughly twice the {approx}20% reported for late-type galaxies (although differences in XUV-disk criteria complicate the comparison), possibly indicating that XUV disks are preferentially associated with galaxies experiencing weak or inefficient star formation. Consistent with this interpretation, we find that the XUV disks in our sample do not correlate with enhanced outer-disk star formation as traced by blue optical outer-disk colors. However, UV-Bright (UV-B) disk galaxies with blue UV colors outside their optical 50% light radii do display enhanced optical outer-disk star formation as well as enhanced atomic gas content. UV-B disks occur in our E/S0s with a 42{sup +9}{sub -8}% frequency and need not coincide with XUV disks; thus their combined frequency is 61% {+-} 9%. For both XUV and UV-B disks, UV colors typically imply <1 Gyr ages, and most such disks extend beyond the optical R{sub 25} radius. XUV disks occur over the full sample mass range and on both the red and blue sequences, suggesting an association with galaxy interactions or another similarly general evolutionary process. In contrast, UV-B disks favor the blue sequence and may also prefer low masses, perhaps reflecting the onset of cold-mode gas accretion or another mass-dependent evolutionary process. Virtually all blue E/S0s in the gas-rich regime below stellar mass M{sub t} {approx} 5 Multiplication-Sign 10{sup 9} M{sub Sun} (the 'gas-richness threshold mass') display UV-B disks

  12. Bright high-repetition-rate source of narrowband extreme-ultraviolet harmonics beyond 22 eV

    PubMed Central

    Wang, He; Xu, Yiming; Ulonska, Stefan; Robinson, Joseph S.; Ranitovic, Predrag; Kaindl, Robert A.

    2015-01-01

    Novel table-top sources of extreme-ultraviolet light based on high-harmonic generation yield unique insight into the fundamental properties of molecules, nanomaterials or correlated solids, and enable advanced applications in imaging or metrology. Extending high-harmonic generation to high repetition rates portends great experimental benefits, yet efficient extreme-ultraviolet conversion of correspondingly weak driving pulses is challenging. Here, we demonstrate a highly-efficient source of femtosecond extreme-ultraviolet pulses at 50-kHz repetition rate, utilizing the ultraviolet second-harmonic focused tightly into Kr gas. In this cascaded scheme, a photon flux beyond ≈3 × 1013 s−1 is generated at 22.3 eV, with 5 × 10−5 conversion efficiency that surpasses similar harmonics directly driven by the fundamental by two orders-of-magnitude. The enhancement arises from both wavelength scaling of the atomic dipole and improved spatio-temporal phase matching, confirmed by simulations. Spectral isolation of a single 72-meV-wide harmonic renders this bright, 50-kHz extreme-ultraviolet source a powerful tool for ultrafast photoemission, nanoscale imaging and other applications. PMID:26067922

  13. Bright high-repetition-rate source of narrowband extreme-ultraviolet harmonics beyond 22 eV

    SciTech Connect

    Wang, He; Xu, Yiming; Ulonska, Stefan; Robinson, Joseph S.; Ranitovic, Predrag; Kaindl, Robert A.

    2015-06-11

    Novel table-top sources of extreme-ultraviolet light based on high-harmonic generation yield unique insight into the fundamental properties of molecules, nanomaterials or correlated solids, and enable advanced applications in imaging or metrology. Extending high-harmonic generation to high repetition rates portends great experimental benefits, yet efficient extreme-ultraviolet conversion of correspondingly weak driving pulses is challenging. In this article, we demonstrate a highly-efficient source of femtosecond extreme-ultraviolet pulses at 50-kHz repetition rate, utilizing the ultraviolet second-harmonic focused tightly into Kr gas. In this cascaded scheme, a photon flux beyond ≈3 × 1013 s-1 is generated at 22.3 eV, with 5 × 10-5 conversion efficiency that surpasses similar harmonics directly driven by the fundamental by two orders-of-magnitude. The enhancement arises from both wavelength scaling of the atomic dipole and improved spatio-temporal phase matching, confirmed by simulations. Finally, spectral isolation of a single 72-meV-wide harmonic renders this bright, 50-kHz extreme-ultraviolet source a powerful tool for ultrafast photoemission, nanoscale imaging and other applications.

  14. Bright high-repetition-rate source of narrowband extreme-ultraviolet harmonics beyond 22 eV.

    PubMed

    Wang, He; Xu, Yiming; Ulonska, Stefan; Robinson, Joseph S; Ranitovic, Predrag; Kaindl, Robert A

    2015-06-11

    Novel table-top sources of extreme-ultraviolet light based on high-harmonic generation yield unique insight into the fundamental properties of molecules, nanomaterials or correlated solids, and enable advanced applications in imaging or metrology. Extending high-harmonic generation to high repetition rates portends great experimental benefits, yet efficient extreme-ultraviolet conversion of correspondingly weak driving pulses is challenging. Here, we demonstrate a highly-efficient source of femtosecond extreme-ultraviolet pulses at 50-kHz repetition rate, utilizing the ultraviolet second-harmonic focused tightly into Kr gas. In this cascaded scheme, a photon flux beyond ≈3 × 10(13) s(-1) is generated at 22.3 eV, with 5 × 10(-5) conversion efficiency that surpasses similar harmonics directly driven by the fundamental by two orders-of-magnitude. The enhancement arises from both wavelength scaling of the atomic dipole and improved spatio-temporal phase matching, confirmed by simulations. Spectral isolation of a single 72-meV-wide harmonic renders this bright, 50-kHz extreme-ultraviolet source a powerful tool for ultrafast photoemission, nanoscale imaging and other applications.

  15. Hubble Space Telescope Near-Ultraviolet Spectroscopy of Bright CEMP-s Stars

    NASA Astrophysics Data System (ADS)

    Placco, Vinicius M.; Beers, Timothy C.; Ivans, Inese I.; Filler, Dan; Imig, Julie A.; Roederer, Ian U.; Abate, Carlo; Hansen, Terese; Cowan, John J.; Frebel, Anna; Lawler, James E.; Schatz, Hendrik; Sneden, Christopher; Sobeck, Jennifer S.; Aoki, Wako; Smith, Verne V.; Bolte, Michael

    2015-10-01

    We present an elemental-abundance analysis, in the near-ultraviolet (NUV) spectral range, for the bright carbon-enhanced metal-poor (CEMP) stars HD 196944 (V=8.40, [Fe/H] = -2.41) and HD 201626 (V=8.16, [Fe/H] = -1.51), based on data acquired with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope. Both of these stars belong to the sub-class CEMP-s, and exhibit clear over-abundances of heavy elements associated with production by the slow neutron-capture process. HD 196944 has been well-studied in the optical region, but we add abundance results for six species (Ge, Nb, Mo, Lu, Pt, and Au) that are only accessible in the NUV. In addition, we provide the first determination of its orbital period, P = 1325 days. HD 201626 has only a limited number of abundance results based on previous optical work—here we add five new species from the NUV, including Pb. We compare these results with models of binary-system evolution and s-process element production in stars on the asymptotic giant branch, with the goal of explaining their origin and evolution. Our best-fitting models for HD 196944 ({M}1,i=0.9{M}⊙ , {M}2,i=0.86{M}⊙ , for [Fe/H] = -2.2), and HD 201626 ({M}1,i=0.9{M}⊙ , {M}2,i=0.76{M}⊙ , for [Fe/H] = -2.2; {M}1,i=1.6{M}⊙ , {M}2,i=0.59{M}⊙ , for [Fe/H] = -1.5) are consistent with the current accepted scenario for the formation of CEMP-s stars. The data presented herein were obtained with the (i) NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. (These observations are associated with program GO-12554, data sets OBQ601010-30 and OBQ602010-30.); and (ii) 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

  16. Supernova 2009kf: An Ultraviolet Bright Type IIP Supernova Discovered With Pan-Starrs 1 and Galex

    DTIC Science & Technology

    2010-07-01

    reserved. Printed in the U.S.A. SUPERNOVA 2009kf: AN ULTRAVIOLET BRIGHT TYPE IIP SUPERNOVA DISCOVERED WITH PAN-STARRS 1 AND GALEX M. T. Botticella1, C...January 29; accepted 2010 May 12; published 2010 June 16 ABSTRACT We present photometric and spectroscopic observations of a luminous Type IIP Supernova ...magnitude MNUV = −21.5 ± 0.5 mag suggests such SNe could be discovered out to z ∼ 2.5 in the PS1 survey. Key words: stars: evolution – supernovae

  17. BRIGHT RAY-LIKE FEATURES IN THE AFTERMATH OF CORONAL MASS EJECTIONS: WHITE LIGHT VERSUS ULTRAVIOLET SPECTRA

    SciTech Connect

    Ciaravella, A.; Webb, D. F.; Giordano, S.; Raymond, J. C.

    2013-03-20

    Current sheets (CSs) are important signatures of magnetic reconnection in the eruption of confined solar magnetic structures. Models of coronal mass ejections (CMEs) involve formation of a CS connecting the ejected flux rope with the post-eruption magnetic loops. CSs have been identified in white light (WL) images of CMEs as narrow rays trailing the outward moving CME core, and in ultraviolet spectra as narrow bright features emitting the [Fe XVIII] line. In this work, samples of rays detected in WL images or in ultraviolet spectra have been analyzed. Temperatures, widths, and line intensities of the rays have been measured, and their correlation to the CME properties has been studied. The samples show a wide range of temperatures with hot, coronal, and cool rays. In some cases, the UV spectra support the identification of rays as CSs, but they show that some WL rays are cool material from the CME core. In many cases, both hot and cool material are present, but offset from each other along the Ultraviolet Coronagraph Spectrometer slit. We find that about 18% of the WL rays show very hot gas consistent with the CS interpretation, while about 23% show cold gas that we attribute to cool prominence material draining back from the CME core. The remaining events have ordinary coronal temperatures, perhaps because they have relaxed back to a quiescent state.

  18. Bright Points and Subflares in Ultraviolet Lines and X-Rays

    NASA Technical Reports Server (NTRS)

    Rovira, M.; Schmieder, B.; Demoulin, P.; Simnett, G. M.; Hagyard, M. J.; Reichmann, E.; Reichmann, E.; Tandberg-Hanssen, E.

    1999-01-01

    We have analyzed an active region which was observed in H.alpha (Multichannel Subtractive Double Pass Spectrograph), in UV lines (SMM/UVSP), and in X-rays (SMM/HXIS). In this active region there were only a few subflares and many small bright points visible in UV and in X-rays. Using an extrapolation based on the Fourier transform, we have computed magnetic field lines connecting different photospheric magnetic polarities from ground-based magnetograms. Along the magnetic inversion lines we find two different zones: (1) a high-shear region (> 70 deg) where subflares occur, and (2) a low-shear region along the magnetic inversion line where UV bright points are observed. In these latter regions the magnetic topology is complex with a mixture of polarities. According to the velocity field observed in the Si IV lamda.1402 line and the extrapolation of the magnetic field, we notice that each UV bright point is consistent with emission from low-rising loops with downflows at both ends. We notice some hard X-ray emissions above the bright-point regions with temperatures up to 8 x 10(exp 6) K, which suggests some induced reconnection due to continuous emergence of new flux. This reconnection is also enhanced by neighboring subflares.

  19. The ultraviolet-bright stars of Omega Centauri, M3, and M13

    NASA Technical Reports Server (NTRS)

    Landsman, Wayne B.; O'Connell, Robert W.; Whitney, Jonathan H.; Bohlin, Ralph C.; Hill, Robert S.; Maran, Stephen P.; Parise, Ronald A.; Roberts, Morton S.; Smith, Andrew A.; Stecher, Theodore P.

    1992-01-01

    Two new UV-bright stars detected within 2 arcmin of the center of Omega Cen are spectroscopically investigated with the short-wavelength spectrograph of the IUE. The IUE spectra of the UV-bright stars UIT-1 and UIT-2 in the core of Omega Cen superficially resemble those of Population I mid-B stars. The absorption lines of the core UV-bright stars are significantly weaker than in Population I stars, consistent with their membership in the cluster. Synthetic spectra calculated from low-metallicity Kurucz model stellar atmospheres are compared with the spectra. These objects are insufficiently luminous to be classical hydrogen-burning post-AGB stars. They may be evolved hot horizontal branch stars which have been brightened by more than 3 mag since leaving the zero-age horizontal branch. It is inferred from the spectra and luminosity of the core UV-bright stars that similar objects could provide the source of the UV light in elliptical galaxies.

  20. Bright subcycle extreme ultraviolet bursts from a single dense relativistic electron sheet.

    PubMed

    Ma, W J; Bin, J H; Wang, H Y; Yeung, M; Kreuzer, C; Streeter, M; Foster, P S; Cousens, S; Kiefer, D; Dromey, B; Yan, X Q; Meyer-ter-Vehn, J; Zepf, M; Schreiber, J

    2014-12-05

    Double-foil targets separated by a low density plasma and irradiated by a petawatt-class laser are shown to be a copious source of coherent broadband radiation. Simulations show that a dense sheet of relativistic electrons is formed during the interaction of the laser with the tenuous plasma between the two foils. The coherent motion of the electron sheet as it transits the second foil results in strong broadband emission in the extreme ultraviolet, consistent with our experimental observations.

  1. Generation of ultrashort coherent vacuum ultraviolet pulses using electron storage rings: a new bright light source for experiments.

    PubMed

    De Ninno, G; Allaria, E; Coreno, M; Curbis, F; Danailov, M B; Karantzoulis, E; Locatelli, A; Menteş, T O; Nino, M A; Spezzani, C; Trovò, M

    2008-08-01

    We demonstrate for the first time that seeded harmonic generation on electron storage rings can produce coherent optical pulses in the vacuum ultraviolet spectral range. The experiment is performed at Elettra, where coherent pulses are generated at 132 nm, with a duration of about 100 fs. The light source has a repetition rate of 1 kHz and adjustable polarization; it is very bright, with a peak power several orders of magnitude above that of spontaneous synchrotron radiation. Owing to high stability, the source is used in a test photoemission electron microscopy experiment. We anticipate that seeded harmonic generation on storage rings can lead to unprecedented developments in time-resolved femtosecond spectroscopy and microscopy.

  2. An Ultraviolet and Near-Infrared View of NGC 4214: A Starbursting Core Embedded in a Low Surface Brightness Disk

    NASA Astrophysics Data System (ADS)

    Fanelli, Michael N.; Waller, William W.; Smith, Denise A.; Freedman, Wendy L.; Madore, Barry; Neff, Susan G.; O'Connell, Robert W.; Roberts, Morton S.; Bohlin, Ralph; Smith, Andrew M.; Stecher, Theodore P.

    1997-05-01

    During the Astro-2 Spacelab mission in 1995 March, the Ultraviolet Imaging Telescope (UIT) obtained far-UV (λ = 1500 Å) imagery of the nearby Sm/Im galaxy NGC 4214. The UIT images have a spatial resolution of ~3" and a limiting surface brightness, μ1500 > 25 mag arcsec-2, permitting detailed investigation of the intensity and spatial distribution of the young, high-mass stellar component. These data provide the first far-UV imagery covering the full spatial extent of NGC 4214. Comparison with a corresponding I-band image reveals the presence of a starbursting core embedded in an extensive low surface brightness disk. In the far-UV (FUV), NGC 4214 is resolved into several components: a luminous, central knot; an inner region (r <~ 2.5 kpc) with ~15 resolved sources embedded in bright, diffuse emission; and a population of fainter knots extending to the edge of the optically defined disk (r ~ 5 kpc). The FUV light, which traces recent massive star formation, is observed to be more centrally concentrated than the I-band light, which traces the global stellar population. The FUV radial light profile is remarkably well represented by an R1/4 law, providing evidence that the centrally concentrated massive star formation in NGC 4214 is the result of an interaction, possibly a tidal encounter, with a dwarf companion(s). The brightest FUV source produces ~8% of the global FUV luminosity. This unresolved source, corresponding to the Wolf-Rayet knot described by Sargent & Filippenko, is located at the center of the FUV light distribution, giving NGC 4214 an active galactic nucleus-like morphology. Another strong source is present in the I band, located 19" west, 10" north of the central starburst knot, with no FUV counterpart. The I-band source may be the previously unrecognized nucleus of NGC 4214 or an evolved star cluster with an age greater than ~200 Myr. The global star formation rate derived from the total FUV flux is consistent with rates derived using data at other

  3. The ultraviolet spectrum and continuum energy distribution of the bright quasar H1821 + 643

    NASA Technical Reports Server (NTRS)

    Kolman, Michiel; Halpern, Jules P.; Shrader, Chris R.; Filippenko, Alexei V.

    1991-01-01

    The first UV observations of the bright QSO H1821 + 643 are reported. With V = 14.2 mag and z = 0.297, H1821 + 643 is the second brightest object in the sky at z above 0.1. The IUE data are combined with new optical spectroscopy, and existing IR and X-ray data, to reveal a strong optical/UV 'big bump', which continues past the Lyman limit in the rest frame of the QSO. A possible turnover at the high-frequency side of the UV continuum constrains fits of a thin accretion disk model to a large black hole mass and high accretion rate, but a small disk size. The shape of the UV continuum was found to be variable, with a hardening of the spectrum when the source was brighter. Because of its location, only 3 deg from the ecliptic pole, H1821 + 643 will be an important object for simultaneous UV and soft X-ray monitoring to test for a common origin of the UV bump and soft X-ray excess.

  4. Observations of the bright novalike variable IX Velorum with the Hopkins Ultraviolet Telescope

    NASA Technical Reports Server (NTRS)

    Long, Knox S.; Wade, Richard A.; Blair, William P.; Davidsen, Arthur F.; Hubeny, Ivan

    1994-01-01

    The Hopkins Ultraviolet Telescope, an experiment flown on the Space Shuttle as part of the Astro-1 mission, was used to obtain a spectrum of the novalike variable IX Vel (= CPD -48 deg 1577) in the wavelength range 830-1860 A. The observation revealed a rich absorption-line and continuum spectrum that peaks near 1050 A at a flux of 1.6 x 10(exp -11) ergs/sq cm/s/A. In the sub-Lyman-alpha region, some of the more prominent absorption lines are S VI lambda lambda-933, 945, C III lambda-977, Lyman-beta, O VI lambda lambda-1032, 1038, P V lambda lambda-1118, 1128, and C III lambda-1176. No emission was detected below the Lyman limit. The overall continuum shape of IX Vel in the FUV can be approximated using models of an optically thick accretion disk in which the integrated spectrum has been constructed by summing model stellar atmospheres or proper disk model spectra. However, if the distance to IX Vel is approximately 95 pc, standard disk models without reddening cannot simultaneously reproduce the color and flux in the UV. While interstellar reddening can reconcile this difference, the amount of reddening appears inconsistent with the absence of a 2200 A bump in the spectrum and the very low H I column density measured along the line of sight. Improved fits to the data can be obtained by modifying the accretion disk stucture within three white dwarf radii. None of the models reproduces the profiles of the Li- and Na-like ions, which are observed as strong but relatively narrow absorption lines, and which are almost surely due to a wind above the disk.

  5. The infrared-ultraviolet dispersed fluorescence spectrum of acetylene: New classes of bright states

    NASA Astrophysics Data System (ADS)

    Hoshina, Kennosuke; Iwasaki, Atsushi; Yamanouchi, Kaoru; Jacobson, Matthew P.; Field, Robert W.

    2001-05-01

    Single rotational levels of ungerade vibrational levels, 2ν3'+ν6' and 3ν3'+ν6' (both with bu symmetry), in the à 1Au electronically excited state of acetylene were excited by an IR-UV double resonance scheme via the ν3″ fundamental level in the X˜ 1Σg+ state, and the rotationally resolved dispersed fluorescence (DF) spectra were recorded at 3.2-4.5 cm-1 resolution. The term values of the new ungerade levels were determined within an accuracy of 0.56 cm-1(1σ) through careful calibration achieved by frequency standard atomic Fe and Hg lines. A total of 111 new ungerade vibrational levels with Σu+, Σu-, and Δu symmetry below 10 000 cm-1 was identified in the high-resolution IR-UV-DF spectra, which provide access to new classes of X˜ 1Σg+ bright states: (i) (0,v2″,0,v4″1,1-1)Σu+, (0,v2″,0,v4″1,11)Δu, and (0,v2″,0,v4″3,1-1)Δu, which are the Franck-Condon (FC) bright levels from the nν3'+ν6' (n=2,3) levels in the à 1Au state; (ii) (0,v2″,0,v4″-1,11)Σu- levels which appear through the a-axis Corioris interaction between nν3'+ν6' and nν3'+ν4' (n=2,3) in the à 1Au state; and (iii) (0,v2″,1,v4″0,0)Σu+ and (0,v2″,1,v4″2,0)Δu levels which gain transition intensity from the Duschinsky effect associated with the bent-linear ÖX˜ transition. All observed ungerade term values and previously determined gerade and ungerade term values below 10 000 cm-1 were fitted by two effective model Hamiltonians, i.e., a pure-bend effective Hamiltonian and a stretch-bend effective Hamiltonian. The stretch-bend effective Hamiltonian is expressed in terms of 31 Dunham expansion parameters and 11 anharmonic resonance parameters associated with (i) five stretch-bend anharmonic resonances; (ii) one stretch-stretch and two bend-bend Darling-Dennison resonances; and (iii) one vibrational l resonance. The parameters in this Hamiltonian were determined from a least-squares fit of 287 vibrational term values (111 new ungerade levels, 128 levels from

  6. Sparkling extreme-ultraviolet bright dots observed with Hi-C

    SciTech Connect

    Régnier, S.; Alexander, C. E.; Walsh, R. W.; Winebarger, A. R.; Cirtain, J.; Golub, L.; Korreck, K. E.; Weber, M.; Mitchell, N.; Platt, S.; De Pontieu, B.; Title, A.; Kobayashi, K.; Kuzin, S.; DeForest, C. E.

    2014-04-01

    Observing the Sun at high time and spatial scales is a step toward understanding the finest and fundamental scales of heating events in the solar corona. The high-resolution coronal (Hi-C) instrument has provided the highest spatial and temporal resolution images of the solar corona in the EUV wavelength range to date. Hi-C observed an active region on 2012 July 11 that exhibits several interesting features in the EUV line at 193 Å. One of them is the existence of short, small brightenings 'sparkling' at the edge of the active region; we call these EUV bright dots (EBDs). Individual EBDs have a characteristic duration of 25 s with a characteristic length of 680 km. These brightenings are not fully resolved by the SDO/AIA instrument at the same wavelength; however, they can be identified with respect to the Hi-C location of the EBDs. In addition, EBDs are seen in other chromospheric/coronal channels of SDO/AIA, which suggests a temperature between 0.5 and 1.5 MK. Based on their frequency in the Hi-C time series, we define four different categories of EBDs: single peak, double peak, long duration, and bursty. Based on a potential field extrapolation from an SDO/HMI magnetogram, the EBDs appear at the footpoints of large-scale, trans-equatorial coronal loops. The Hi-C observations provide the first evidence of small-scale EUV heating events at the base of these coronal loops, which have a free magnetic energy of the order of 10{sup 26} erg.

  7. Three-Dimensional Structure and Evolution of Extreme-Ultraviolet Bright Points Observed by STEREO/SECCHI/EUVI

    NASA Technical Reports Server (NTRS)

    Kwon, Ryun Young; Chae, Jongchul; Davila, Joseph M.; Zhang, Jie; Moon, Yong-Jae; Poomvises, Watanachak; Jones, Shaela I.

    2012-01-01

    We unveil the three-dimensional structure of quiet-Sun EUV bright points and their temporal evolution by applying a triangulation method to time series of images taken by SECCHI/EUVI on board the STEREO twin spacecraft. For this study we examine the heights and lengths as the components of the three-dimensional structure of EUV bright points and their temporal evolutions. Among them we present three bright points which show three distinct changes in the height and length: decreasing, increasing, and steady. We show that the three distinct changes are consistent with the motions (converging, diverging, and shearing, respectively) of their photospheric magnetic flux concentrations. Both growth and shrinkage of the magnetic fluxes occur during their lifetimes and they are dominant in the initial and later phases, respectively. They are all multi-temperature loop systems which have hot loops (approx. 10(exp 6.2) K) overlying cooler ones (approx 10(exp 6.0) K) with cool legs (approx 10(exp 4.9) K) during their whole evolutionary histories. Our results imply that the multi-thermal loop system is a general character of EUV bright points. We conclude that EUV bright points are flaring loops formed by magnetic reconnection and their geometry may represent the reconnected magnetic field lines rather than the separator field lines.

  8. THREE-DIMENSIONAL STRUCTURE AND EVOLUTION OF EXTREME-ULTRAVIOLET BRIGHT POINTS OBSERVED BY STEREO/SECCHI/EUVI

    SciTech Connect

    Kwon, Ryun-Young; Poomvises, Watanachak; Chae, Jongchul; Davila, Joseph M.; Jones, Shaela I.; Zhang Jie; Moon, Yong-Jae

    2012-10-01

    We unveil the three-dimensional structure of quiet-Sun EUV bright points and their temporal evolution by applying a triangulation method to time series of images taken by SECCHI/EUVI on board the STEREO twin spacecraft. For this study we examine the heights and lengths as the components of the three-dimensional structure of EUV bright points and their temporal evolutions. Among them we present three bright points which show three distinct changes in the height and length: decreasing, increasing, and steady. We show that the three distinct changes are consistent with the motions (converging, diverging, and shearing, respectively) of their photospheric magnetic flux concentrations. Both growth and shrinkage of the magnetic fluxes occur during their lifetimes and they are dominant in the initial and later phases, respectively. They are all multi-temperature loop systems which have hot loops ({approx}10{sup 6.2} K) overlying cooler ones ({approx}10{sup 6.0} K) with cool legs ({approx}10{sup 4.9} K) during their whole evolutionary histories. Our results imply that the multi-thermal loop system is a general character of EUV bright points. We conclude that EUV bright points are flaring loops formed by magnetic reconnection and their geometry may represent the reconnected magnetic field lines rather than the separator field lines.

  9. Observations of the vacuum ultraviolet and x-ray brightness profiles of Fe, Ni, and Ge in magnetically confined fusion plasmas.

    PubMed

    May, M J; Finkenthal, M; Moos, H W; Fournier, K B; Goldstein, W H; Mattioli, M; Pacella, D; Mazzitelli, G; Leigheb, M; Gabellieri, L

    2001-09-01

    The spatial brightness profiles of emission lines for the K-like through He-like ionization states of Fe, Ge, and Ni have been measured during a set of experiments in which Fe and Ge were introduced into FTU tokamak plasmas by using the laser blowoff technique. Nickel was an intrinsic impurity observed during these experiments that was sputtered from the inconel limiter. The brightness profiles were measured by spatially scanable, photometrically calibrated vaccum ultraviolet and x-ray spectrometers that covered the 1 to 1700 A region. Simulations of these profiles and the time evolution of the laser blowoffs were performed with the MIST transport code using several sets of atomic physics compilations [ADPAK (originally in MIST), Arnaud and Raymond (AR92), Arnaud and Rothenflug (AR85), Mazzotta et al., and Mattioli (an extension to Mazzotta)]. The goal was to determine which set of available rates could best simulate the measured spatial brightness profiles and the charge state balance in the plasma. The Mazzotta et al. (for Fe and Ni), the Mattioli (for Ge), and the AR92 (for Fe only) rates adequately simulated the He-, Li-, Be-, Na-, Mg-like ionization states. The F- to B-like charge states could not be simulated by these compilations unless the relevant dielectronic rates were multiplied by a factor of 2. The ADPAK rates could not adequately predict any of the charge states of Fe, Ge, or Ni.

  10. Resonances in the Photoionization Cross Sections of Atomic Nitrogen Shape the Far-ultraviolet Spectrum of the Bright Star in 47 Tucanae

    NASA Astrophysics Data System (ADS)

    Dixon, William V.; Chayer, Pierre

    2013-08-01

    The far-ultraviolet spectrum of the Bright Star (B8 III) in 47 Tuc (NGC 104) shows a remarkable pattern: it is well fit by local thermodynamic equilibrium models at wavelengths longer than Lyβ, but at shorter wavelengths it is fainter than the models by a factor of two. A spectrum of this star obtained with the Far Ultraviolet Spectroscopic Explorer shows broad absorption troughs with sharp edges at 995 and 1010 Å and a deep absorption feature at 1072 Å none of which are predicted by the models. We find that these features are caused by resonances in the photoionization cross sections of the first and second excited states of atomic nitrogen (2s 2 2p 3 2 D 0 and 2 P 0). Using cross sections from the Opacity Project, we can reproduce these features, but only if we use the cross sections at their full resolution, rather than the resonance-averaged cross sections usually employed to model stellar atmospheres. These resonances are strongest in stellar atmospheres with enhanced nitrogen and depleted carbon abundances, a pattern typical of post-asymptotic giant branch stars.

  11. RESONANCES IN THE PHOTOIONIZATION CROSS SECTIONS OF ATOMIC NITROGEN SHAPE THE FAR-ULTRAVIOLET SPECTRUM OF THE BRIGHT STAR IN 47 TUCANAE

    SciTech Connect

    Dixon, William V.; Chayer, Pierre E-mail: chayer@stsci.edu

    2013-08-10

    The far-ultraviolet spectrum of the Bright Star (B8 III) in 47 Tuc (NGC 104) shows a remarkable pattern: it is well fit by local thermodynamic equilibrium models at wavelengths longer than Ly{beta}, but at shorter wavelengths it is fainter than the models by a factor of two. A spectrum of this star obtained with the Far Ultraviolet Spectroscopic Explorer shows broad absorption troughs with sharp edges at 995 and 1010 A and a deep absorption feature at 1072 A; none of which are predicted by the models. We find that these features are caused by resonances in the photoionization cross sections of the first and second excited states of atomic nitrogen (2s {sup 2} 2p {sup 3} {sup 2} D {sup 0} and {sup 2} P {sup 0}). Using cross sections from the Opacity Project, we can reproduce these features, but only if we use the cross sections at their full resolution, rather than the resonance-averaged cross sections usually employed to model stellar atmospheres. These resonances are strongest in stellar atmospheres with enhanced nitrogen and depleted carbon abundances, a pattern typical of post-asymptotic giant branch stars.

  12. Solid-core and hollow-core photonic crystal fiber for generation of bright ultraviolet light (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Joly, Nicolas Y.; Jiang, Xin; Travers, John C.; Ermolov, Alexey; Russell, Philip S.

    2016-09-01

    Over the last two decades the interest in photonic crystal fiber (PCF) has grown considerably, particularly in nonlinear optics where it allows enhanced control over the dispersion landscape. Although silica is the material most commonly used to fabricate PCF, its limited window of transmission and its susceptibility to optical damage at wavelengths below 350nm is driving the development of fibers made from glasses with transmission windows extending into the deep ultraviolet and the mid-infrared. An alternative is offered by gas-filled hollow-core fiber, in which the light propagates predominantly in the gas. In kagomé-style hollow-core PCF filled with noble gas, the weak anomalous dispersion of the empty fiber is balanced by the normal dispersion of the filling gas, resulting in a versatile system whose dispersion landscape can be adjusted in real time [Travers et al., JOSAB 28, A11 (2011)]. Under appropriate conditions the launched pulse undergoes soliton self-compression followed by emission of a band of dispersive radiation in the UV. UV light tunable down to 113 nm has been generated with this technique [Russell et al., Nat. Photon. 8, 278 (2014)]. Solid-core ZBLAN (fluorozirconate) glass PCF is transparent from 0.2 to 7.8µm. Launching 1nJ 140fs pulses at 1µm wavelength into a 1µm diameter core resulted, after 4cm of propagation, in generation of a supercontinuum spectrum extending from 210nm to beyond 2µm. In strong contrast to silica PCF, the ZBLAN PCF showed no signs of any solarization-related damage, even when operating over many hours [Jiang et al., Nat. Photon. 9, 133 (2015)].

  13. Hubble space telescope near-ultraviolet spectroscopy of the bright cemp-no star BD+44°493

    SciTech Connect

    Placco, Vinicius M.; Beers, Timothy C.; Smith, Verne V.; Roederer, Ian U.; Cowan, John J.; Frebel, Anna; Filler, Dan; Ivans, Inese I.; Lawler, James E.; Schatz, Hendrik; Sneden, Christopher; Sobeck, Jennifer S.; Aoki, Wako

    2014-07-20

    We present an elemental-abundance analysis, in the near-ultraviolet (NUV) spectral range, for the extremely metal-poor star BD+44°493 a ninth magnitude subgiant with [Fe/H] =–3.8 and enhanced carbon, based on data acquired with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. This star is the brightest example of a class of objects that, unlike the great majority of carbon-enhanced metal-poor (CEMP) stars, does not exhibit over-abundances of heavy neutron-capture elements (CEMP-no). In this paper, we validate the abundance determinations for a number of species that were previously studied in the optical region, and obtain strong upper limits for beryllium and boron, as well as for neutron-capture elements from zirconium to platinum, many of which are not accessible from ground-based spectra. The boron upper limit we obtain for BD+44°493, log ε (B) <–0.70, the first such measurement for a CEMP star, is the lowest yet found for very and extremely metal-poor stars. In addition, we obtain even lower upper limits on the abundances of beryllium, log ε (Be) <–2.3, and lead, log ε (Pb) <–0.23 ([Pb/Fe] <+1.90), than those reported by previous analyses in the optical range. Taken together with the previously measured low abundance of lithium, the very low upper limits on Be and B suggest that BD+44°493 was formed at a very early time, and that it could well be a bona-fide second-generation star. Finally, the Pb upper limit strengthens the argument for non-s-process production of the heavy-element abundance patterns in CEMP-no stars.

  14. The ultraviolet-bright, slowly declining transient PS1-11af as a partial tidal disruption event

    SciTech Connect

    Chornock, R.; Berger, E.; Zauderer, B. A.; Kamble, A.; Soderberg, A. M.; Czekala, I.; Dittmann, J.; Drout, M.; Foley, R. J.; Fong, W.; Kirshner, R. P.; Lunnan, R.; Marion, G. H.; Narayan, G.; Gezari, S.; Rest, A.; Riess, A. G.; Chomiuk, L.; Huber, M. E.; Lawrence, A.; and others

    2014-01-01

    We present the Pan-STARRS1 discovery of the long-lived and blue transient PS1-11af, which was also detected by Galaxy Evolution Explorer with coordinated observations in the near-ultraviolet (NUV) band. PS1-11af is associated with the nucleus of an early type galaxy at redshift z = 0.4046 that exhibits no evidence for star formation or active galactic nucleus activity. Four epochs of spectroscopy reveal a pair of transient broad absorption features in the UV on otherwise featureless spectra. Despite the superficial similarity of these features to P-Cygni absorptions of supernovae (SNe), we conclude that PS1-11af is not consistent with the properties of known types of SNe. Blackbody fits to the spectral energy distribution are inconsistent with the cooling, expanding ejecta of a SN, and the velocities of the absorption features are too high to represent material in homologous expansion near a SN photosphere. However, the constant blue colors and slow evolution of the luminosity are similar to previous optically selected tidal disruption events (TDEs). The shape of the optical light curve is consistent with models for TDEs, but the minimum accreted mass necessary to power the observed luminosity is only ∼0.002 M {sub ☉}, which points to a partial disruption model. A full disruption model predicts higher bolometric luminosities, which would require most of the radiation to be emitted in a separate component at high energies where we lack observations. In addition, the observed temperature is lower than that predicted by pure accretion disk models for TDEs and requires reprocessing to a constant, lower temperature. Three deep non-detections in the radio with the Very Large Array over the first two years after the event set strict limits on the production of any relativistic outflow comparable to Swift J1644+57, even if off-axis.

  15. Heavy element abundances in Ap stars from ultraviolet data. I - The bright reference stars Alpha Lyrae and Alpha Canis Majoris A

    NASA Technical Reports Server (NTRS)

    Boiarchuk, A. A.; Snow, T. P., Jr.

    1978-01-01

    Curve-of-growth analysis is used to derive chemical abundances in Alpha Lyr and Alpha CMa, based on ultraviolet spectra obtained with Copernicus. This analysis is part of a program to study the abundances of the heavy elements mercury and platinum and the short-lived element technetium in the atmospheres of Ap and Am stars. Ultraviolet Fe II lines are used to establish the curves of growth for Alpha Lyr and Alpha CMa A; abundances of a variety of elements, along with upper limits on Hg, Pt, and Tc, are derived. In cases where previous studies based on visual spectra have included elements in common with the present analysis, the agreement is good within the known uncertainties. One new element, cadmium, is observed for these two stars. The upper limits on Pt and Hg, as well as Tc, show that these elements are probably not enhanced in Alpha CMa A by more than about one order of magnitude.

  16. UV-bright stars in globular clusters

    NASA Technical Reports Server (NTRS)

    Landsman, Wayne B.

    1994-01-01

    This paper highlights globular cluster studies with Ultraviolet Imaging Telescope (UIT) in three areas: the discrepancy between observed ultraviolet HB magnitudes and predictions of theoretical HB models; the discovery of two hot subdwarfs in NGC 1851, a globular not previously known to contain such stars; and spectroscopic follow up of newly identified UV-bright stars in M79 and w Cen. I also present results of a recent observation of NGC 6397 with the Voyager ultraviolet spectrometer.

  17. Exceptionally bright, compact starburst nucleus

    SciTech Connect

    Margon, B.; Anderson, S.F.; Mateo, M.; Fich, M.; Massey, P.

    1988-11-01

    Observations are reported of a remarkably bright (V about 13) starburst nucleus, 0833 + 652, which has been detected at radio, infrared, optical, ultraviolet, and X-ray wavelengths. Despite an observed flux at each of these wavelengths which is comparable to that of NGC 7714, often considered the 'prototypical' example of the starburst phenomenon, 0833 + 652 appears to be a previously uncataloged object. Its ease of detectability throughout the electromagnetic spectrum should make it useful for a variety of problems in the study of compact emission-line galaxies. 30 references.

  18. Ultraviolet Waves

    ERIC Educational Resources Information Center

    Molde, Trevor

    1973-01-01

    Outlines the discovery and nature of ultraviolet light, discusses some applications for these wavelengths, and describes a number of experiments with ultraviolet radiation suitable for secondary school science classes. (JR)

  19. Ultraviolet observations of comets

    NASA Technical Reports Server (NTRS)

    Code, A. D.; Houck, T. E.; Lillie, C. F.

    1972-01-01

    The first observations of a comet in the vacuum ultraviolet were obtained on January 14, 1970, when OAO-2 recorded the spectrum of the bright comet Tago-Sato-Kosaka (1969g). The observations revealed, among other things, the predicted extensive hydrogen Lyman alpha halo. OAO-2 continued to collect spectrophotometric measurements of this comet throughout January of that year; a photograph of the nucleus in Lyman alpha revealed finer scale structures. In February of 1970, the bright comet Bennet (1969i) became favorable for space observations. On the basis of the OAO discovery, OGO-V made several measurements of comet Bennet with low spatial resolution photometers. Comet Enke was detected by OGO in January of 1971 at a large heliocentric distance from its Lyman alpha emission.

  20. Ultraviolet filters.

    PubMed

    Shaath, Nadim A

    2010-04-01

    The chemistry, photostability and mechanism of action of ultraviolet filters are reviewed. The worldwide regulatory status of the 55 approved ultraviolet filters and their optical properties are documented. The photostabilty of butyl methoxydibenzoyl methane (avobenzone) is considered and methods to stabilize it in cosmetic formulations are presented.

  1. Compact, passively Q-switched, all-solid-state master oscillator-power amplifier-optical parametric oscillator (MOPA-OPO) system pumped by a fiber-coupled diode laser generating high-brightness, tunable, ultraviolet radiation.

    PubMed

    Peuser, Peter; Platz, Willi; Fix, Andreas; Ehret, Gerhard; Meister, Alexander; Haag, Matthias; Zolichowski, Paul

    2009-07-01

    We report on a compact, tunable ultraviolet laser system that consists of an optical parametric oscillator (OPO) and a longitudinally diode-pumped Nd:YAG master oscillator-power amplifier (MOPA). The pump energy for the whole laser system is supplied via a single delivery fiber. Nanosecond pulses are produced by an oscillator that is passively Q-switched by a Cr(4+):YAG crystal. The OPO is pumped by the second harmonic of the Nd:YAG MOPA. Continuously tunable radiation is generated by an intracavity sum-frequency mixing process within the OPO in the range of 245-260 nm with high beam quality. Maximum pulse energies of 1.2 mJ were achieved, which correspond to an optical efficiency of 3.75%, relating to the pulse energy of the MOPA at 1064 nm.

  2. THE LBT BOOeTES FIELD SURVEY. I. THE REST-FRAME ULTRAVIOLET AND NEAR-INFRARED LUMINOSITY FUNCTIONS AND CLUSTERING OF BRIGHT LYMAN BREAK GALAXIES AT Z {approx} 3

    SciTech Connect

    Bian Fuyan; Fan Xiaohui; Jiang Linhua; McGreer, Ian; Dave, Romeel; Dey, Arjun; Green, Richard F.; Maiolino, Roberto; Walter, Fabian; Lee, Kyoung-Soo

    2013-09-01

    We present a deep LBT/LBC U{sub spec}-band imaging survey (9 deg{sup 2}) covering the NOAO Booetes field. A total of 14,485 Lyman break galaxies (LBGs) at z {approx} 3 are selected, which are used to measure the rest-frame UV luminosity function (LF). The large sample size and survey area reduce the LF uncertainties due to Poisson statistics and cosmic variance by {>=}3 compared to previous studies. At the bright end, the LF shows excess power compared to the best-fit Schechter function, which can be attributed to the contribution of z {approx} 3 quasars. We compute the rest-frame near-infrared LF and stellar mass function (SMF) of z {approx} 3 LBGs based on the R-band and [4.5 {mu}m]-band flux relation. We investigate the evolution of the UV LFs and SMFs between z {approx} 7 and z {approx} 3, which supports a rising star formation history in the LBGs. We study the spatial correlation function of two bright LBG samples and estimate their average host halo mass. We find a tight relation between the host halo mass and the galaxy star formation rate (SFR), which follows the trend predicted by the baryonic accretion rate onto the halo, suggesting that the star formation in LBGs is fueled by baryonic accretion through the cosmic web. By comparing the SFRs with the total baryonic accretion rates, we find that cosmic star formation efficiency is about 5%-20% and it does not evolve significantly with redshift, halo mass, or galaxy luminosity.

  3. Ultraviolet Extensions

    NASA Technical Reports Server (NTRS)

    2008-01-01

    [figure removed for brevity, see original site] Side-by-Side Comparison Click on image for larger view

    This ultraviolet image from NASA's Galaxy Evolution Explorer shows the Southern Pinwheel galaxy, also know as Messier 83 or M83. It is located 15 million light-years away in the southern constellation Hydra.

    Ultraviolet light traces young populations of stars; in this image, young stars can be seen way beyond the main spiral disk of M83 up to 140,000 light-years from its center. Could life exist around one of these far-flung stars? Scientists say it's unlikely because the outlying regions of a galaxy are lacking in the metals required for planets to form.

    The image was taken at scheduled intervals between March 15 and May 20, 2007. It is one of the longest-exposure, or deepest, images ever taken of a nearby galaxy in ultraviolet light. Near-ultraviolet light (or longer-wavelength ultraviolet light) is colored yellow, and far-ultraviolet light is blue.

    What Lies Beyond the Edge of a Galaxy The side-by-side comparison shows the Southern Pinwheel galaxy, or M83, as seen in ultraviolet light (right) and at both ultraviolet and radio wavelengths (left). While the radio data highlight the galaxy's long, octopus-like arms stretching far beyond its main spiral disk (red), the ultraviolet data reveal clusters of baby stars (blue) within the extended arms.

    The ultraviolet image was taken by NASA's Galaxy Evolution Explorer between March 15 and May 20, 2007, at scheduled intervals. Back in 2005, the telescope first photographed M83 over a shorter period of time. That picture was the first to reveal far-flung baby stars forming up to 63,000 light-years from the edge of the main spiral disk. This came as a surprise to astronomers because a galaxy's outer territory typically lacks high densities of star-forming materials.

    The newest picture of M83 from the Galaxy Evolution Explorer is shown at the right, and was taken over a longer period of

  4. [Bright light therapy].

    PubMed

    Poirrier, R; Cambron, L

    2007-01-01

    Bright light therapy is a treatment that emerged in the eighties of the last century. It can be used in different pathologies such as seasonal affective disorders, major depressions, and many disorders of the wake-sleep rhythm, whether they are of primary or secondary origin. Important progress made at the basic neuroscience levels, allows today a sound understanding of the bright light mode of action. Moreover, the main indications are now the subject of consensus reports and meta-analyses which show good levels of evidence-based medicine. Bright light therapy constitutes a first choice indication in seasonal affective disorder. It is also perfectly possible to prescribe bright light therapy in the major depression disorders. It has been demonstrated that the effect size is the same as with antidepressants of reference. It is admitted nowadays that bright light therapy may be at least, an adjunct to pharmacotherapy, in order to accelerate the antidepressant effect onset, or to prolong this effect after withdrawal of the drug. Bright light therapy can also be viewed as an alternative to the pharmacological approach especially when this one is impossible, not tolerated or not accepted by the patient. The contraindications are rare.

  5. Understanding the Ultraviolet Flux from Supernovae

    NASA Astrophysics Data System (ADS)

    Brown, Peter J.

    2016-01-01

    The conversion of observed magnitudes into flux densities for the creation of spectral energy distributions or integrating bolometric fluxes depends on the spectral shape of the source and the characteristics of the filters. Such details are often neglected, though the effects can be significant. We demonstrate the complexities of conversion as they relate to ultraviolet observations of supernovae, though the principles have broader application. These complexities include spectral model testing, the meaning of effective wavelengths, the endpoints of integration, and extinction corrections. Using data from the Swift Optical Ultraviolet Supernova Archive (SOUSA) we will present integrated luminosity curves from example supernovae of all types. We will also show the unprecedented ultraviolet luminosity of ASASSN-15lh/SN2015L. The creation of ultraviolet/optical spectral energy distributions is helpful in predicting the observed brightness and detectability of these supernovae at higher redshifts with optical telescopes such as the Dark Energy Survey and the Large Synoptic Survey Telescope.

  6. Female butterflies prefer males bearing bright iridescent ornamentation

    PubMed Central

    Kemp, Darrell J

    2007-01-01

    Butterflies are among nature's most colourful animals, and provide a living showcase for how extremely bright, chromatic and iridescent coloration can be generated by complex optical mechanisms. The gross characteristics of male butterfly colour patterns are understood to function for species and/or sex recognition, but it is not known whether female mate choice promotes visual exaggeration of this coloration. Here I show that females of the sexually dichromatic species Hypolimnas bolina prefer conspecific males that possess bright iridescent blue/ultraviolet dorsal ornamentation. In separate field and enclosure experiments, using both dramatic and graded wing colour manipulations, I demonstrate that a moderate qualitative reduction in signal brightness and chromaticity has the same consequences as removing the signal entirely. These findings validate a long-held hypothesis, and argue for the importance of intra- versus interspecific selection as the driving force behind the exaggeration of bright, iridescent butterfly colour patterns. PMID:17284412

  7. High Brightness OLED Lighting

    SciTech Connect

    Spindler, Jeffrey; Kondakova, Marina; Boroson, Michael; Hamer, John

    2016-05-25

    In this work we describe the technology developments behind our current and future generations of high brightness OLED lighting panels. We have developed white and amber OLEDs with excellent performance based on the stacking approach. Current products achieve 40-60 lm/W, while future developments focus on achieving 80 lm/W or higher.

  8. Brightness predictions for comets

    NASA Astrophysics Data System (ADS)

    Green, Daniel W. E.; Marsden, Brian G.; Morris, Charles S.

    2001-02-01

    Daniel W E Green, Brian G Marsden and Charles S Morris write with the aim of illuminating the issue of cometary light curves and brightness predictions, following the publication in this journal last October of the letter by John McFarland (2000).

  9. A Bright Shining Lesson

    ERIC Educational Resources Information Center

    Hurowitz, Amanda

    2010-01-01

    Sometimes students come up with crazy ideas. When this author first started teaching at Thomas Jefferson High School for Science and Technology in Virginia five years ago, she had a sophomore share such an idea with her. He wanted to put solar panels on the school's roof as a way to reduce the school's carbon footprint and set a bright clean…

  10. Bright Fireball Over Georgia

    NASA Video Gallery

    A camera in Cartersville, Ga., captured this view of a bright fireball over Georgia on the night of Mar. 7, 2012, at approx. 10:19:11 EST. The meteor was first recorded at an altitude of 51.5 miles...

  11. Bright Streak on Amalthea

    NASA Technical Reports Server (NTRS)

    2000-01-01

    These two images of Jupiter's small, irregularly shaped moon Amalthea, obtained by the camera onboard NASA's Galileo spacecraft in August 1999(left) and November 1999 (right), form a 'stereo pair' that helps scientists determine this moon's shape and the topography of its surface features. Features as small as 3.8 kilometers (2.4 miles) across can be resolved in these images, making them among the highest-resolution images ever taken of Amalthea.

    The large impact crater visible in both images, near the right-hand edge of Amalthea's disk, is about 40 kilometers (about 29 miles) across; two ridges, tall enough to cast shadows, extend from the top of the crater in a V-shape reminiscent of a 'rabbit ears' television antenna. To the left of these ridges, in the top center portion of Amalthea's disk, is a second large impact crater similar in size to the first crater. To the left of this second crater is a linear 'streak' of relatively bright material about 50 kilometers (31 miles) long. In previous spacecraft images of Amalthea taken from other viewing directions, this bright feature was thought to be a small, round, bright 'spot' and was given the name Ida. These new images reveal for the first time that Ida is actually a long, linear 'streak.' This bright streak may represent material ejected during the formation of the adjacent impact crater, or it may just mark the crest of a local ridge. Other patches of relatively bright material can be seen elsewhere on Amalthea's disk, although none of these other bright spots has Ida's linear shape.

    In both images, sunlight is coming from the left and north is approximately up. Note that the north pole of Amalthea is missing in the right-hand image (it was cut off by the edge of the camera frame). The bright streak, Ida, is on the side of the moon that faces permanently away from Jupiter, and the crater near the right-hand edge of the disk is in the center of Amalthea's leading side (the side of the moon that 'leads

  12. Bright field illumination system

    NASA Technical Reports Server (NTRS)

    Huber, Edward D. (Inventor)

    1998-01-01

    A Bright Field Illumination system for inspecting a range of characteristically different kinds of defects, depressions, and ridges in a selected material surface. The system has an illumination source placed near a first focus of an elliptical reflector. In addition, a camera facing the inspected area is placed near the illumination source and the first focus. The second focus of the elliptical reflector is located at a distance approximately twice the elliptical reflector's distance above the inspected surface. The elliptical reflector directs the light from the source onto the inspected surface. Due to the shape of the elliptical reflector, light that is specularly reflected from the inspected surface is directed into the camera is which located at the position of the reflected second focus of the ellipse. This system creates a brightly lighted background field against which damage sites appear as high contrast dark objects which can be easily detected by a person or an automated inspection system. In addition, the Bright Field Illumination system and method can be used in combination with a vision inspection system providing for multiplexed illumination and data handling of multiple kinds of surface characteristics including abrupt and gradual surface variations and differences between measured characteristics of different kinds and prior instruments.

  13. Kiloamp high-brightness beams

    SciTech Connect

    Caporaso, G.J.

    1987-01-01

    Brightness preservation of high-current relativistic electron beams under two different types of transport is discussed. Recent progress in improving the brightness of laser-guided beams in the Advanced Test Accelerator is reviewed. A strategy for the preservation of the brightness of space-charge-dominated beams in a solenoidal transport system is presented.

  14. A survey of ultraviolet interstellar absorption lines

    NASA Technical Reports Server (NTRS)

    Bohlin, R. C.; Jenkins, E. B.; Spitzer, L., Jr.; York, D. G.; Hill, J. K.; Savage, B. D.; Snow, T. P., Jr.

    1983-01-01

    A telescope-spectrometer on the Copernicus spacecraft made possible the measurement of many ultraviolet absorption lines produced by the interstellar gas. The present survey provides data on ultraviolet absorption lines in the spectra of 88 early-type stars. The stars observed are divided into four classes, including reddened stars, unreddened bright stars, moderately reddened bright stars, and unreddened and moderately reddened faint stars. Data are presented for equivalent width, W, radial velocity V, and rms line width, D, taking into account some 10 to 20 lines of N I, O I, Si II, P II, S II, Cl I, Cl II, Mn II, Fe II, Ni II, Cu II, and H2. The data are based on multiple scans for each line. Attention is given to details of observations, the data reduction procedure, and the computation of equivalent width, mean velocity, and velocity dispersion.

  15. HI Surface brightness mapping

    NASA Astrophysics Data System (ADS)

    Pen, Ue-Li; Staveley-Smith, Lister; Chang, Tzu-Ching; Peterson, Jeff; Bandura, Kevin

    2008-04-01

    We propose to scan the 2dF survey field with Parkes multibeam in driftscan mode to make a map to cross correlate with galaxy redshifts. This allows a statistical detection of HI large scale structure out to z=0.15. In this cross correlation, the HI in ALL galaxies contributes, not only the bright ones, which significantly boosts the sensitivity. The proposed 40 hours on the fields result in a forecasted 20 sigma detection. The survey volume is 10 million cubic megaparsec, which contain 10^15 solar masses of hydrogen.

  16. Low surface brightness galaxies

    NASA Technical Reports Server (NTRS)

    Vanderhulst, J. M.; Deblok, W. J. G.; Mcgaugh, S. S.; Bothun, G. D.

    1993-01-01

    A program to investigate the properties of low surface brightness (LSB) galaxies involving surface photometry in U, B, V, R, I, and H-alpha, HI imaging with the Westerbork Synthesis Radio Telescope (WSRT) and the very large array (VLA) and spectrophotometry of H2 regions in LSB galaxies is underway. The goal is to verify the idea that LSB galaxies have low star formation rates because the local gas density falls below the critical density for star formation, and to study the stellar population and abundances in LSB galaxies. Such information should help understanding the evolutionary history of LSB galaxies. Some preliminary results are reported.

  17. Ultraviolet fluxes for globular clusters in M31 - A rediscussion

    SciTech Connect

    Crotts, A.P.S.; Kron, R.G.; Cacciari, C.; Fusi-Pecci, F. McDonald Observatory, Austin, TX Yerkes Observatory, Williams Bay, WI Osservatorio Astronomico, Bologna Bologna Universita )

    1990-07-01

    Long-exposure observations of three bright globular clusters in M31 obtained with both the short- and long-wavelength low-resolution cameras of the International Ultraviolet Explorer satellite are discussed. All of the clusters are seen at the longer wavelengths, but only one of the clusters is seen at short wavelengths, and this detection is marginal. The ultraviolet fluxes are in fact known with only poor precision, and previous conclusions concerning the stellar population are weakened accordingly. Discrepancies between the ultraviolet fluxes obtained here and in other published work are described. 16 refs.

  18. High brightness electron sources

    SciTech Connect

    Sheffield, R.L.

    1995-07-01

    High energy physics accelerators and free electron lasers put increased demands on the electron beam sources. This paper describes the present research on attaining intense bright electron beams using photoinjectors. Recent results from the experimental programs will be given. The performance advantages and difficulties presently faced by researchers will be discussed, and the following topics will be covered. Progress has been made in photocathode materials, both in lifetime and quantum efficiency. Cesium telluride has demonstrated significantly longer lifetimes than cesium antimonide at 10{sup {minus}8} torr. However, the laser system is more difficult because cesium telluride requires quadrupled YLF instead of the doubled YLF required for cesium antimonide. The difficulty in using photoinjectors is primarily the drive laser, in particular the amplitude stability. Finally, emittance measurements of photoinjector systems can be complicated by the non-thermal nature of the electron beam. An example of the difficulty in measuring beam emittance is given.

  19. High brightness electron accelerator

    DOEpatents

    Sheffield, Richard L.; Carlsten, Bruce E.; Young, Lloyd M.

    1994-01-01

    A compact high brightness linear accelerator is provided for use, e.g., in a free electron laser. The accelerator has a first plurality of acclerating cavities having end walls with four coupling slots for accelerating electrons to high velocities in the absence of quadrupole fields. A second plurality of cavities receives the high velocity electrons for further acceleration, where each of the second cavities has end walls with two coupling slots for acceleration in the absence of dipole fields. The accelerator also includes a first cavity with an extended length to provide for phase matching the electron beam along the accelerating cavities. A solenoid is provided about the photocathode that emits the electons, where the solenoid is configured to provide a substantially uniform magnetic field over the photocathode surface to minimize emittance of the electons as the electrons enter the first cavity.

  20. Tunable High Brightness Semiconductor Sources

    DTIC Science & Technology

    2015-05-01

    AFRL-RY-WP-TR-2015-0066 TUNABLE HIGH BRIGHTNESS SEMICONDUCTOR SOURCES Robert Bedford, Saima Husaini, Charles Reyner, and Tuoc Dang...3. DATES COVERED (From - To) May 2015 Final 5 November 2010 – 1 February 2015 4. TITLE AND SUBTITLE TUNABLE HIGH BRIGHTNESS SEMICONDUCTOR SOURCES 5a...included within the Tunable High Brightness Semiconductor Sources work unit includes several technology advancements. First, theoretical advances in mid

  1. The Ultraviolet Albedo of Ganymede

    NASA Technical Reports Server (NTRS)

    McGrath, Melissa; Hendrix, Amanda

    2013-01-01

    A large set of ultraviolet images of Ganymede have been acquired with the Hubble Space Telescope over the last 15 years. These images have been used almost exclusively to study Ganymede's stunning auroral emissions (Feldman et al. 2000; Eviatar et al. 2001; McGrath et al. 2004; Saur et al. 2011; McGrath et al. 2013), and even the most basic information about Ganymede's UV albedo has yet to be gleaned from these data. We will present a first-cut analysis of both disk-averaged and spatially-resolved UV albedos of Ganymede, with focus on the spatially-resolved Lyman-alpha albedo, which has never been considered previously for this satellite. Ganymede's visibly bright regions are known to be rich in water ice, while the visibly dark regions seem to be more carbonaceous (Carlson et al., 1996). At Lyman-alpha, these two species should also have very different albedo values.

  2. Statistical Properties of Solar Coronal Bright Points

    NASA Astrophysics Data System (ADS)

    Alipour, N.; Safari, H.

    2015-07-01

    Here, we aim to study the statistical properties (i.e., spatial, temporal, and magnetic structures) of extreme ultraviolet coronal bright points (CBPs) observed by SDO during a 4.4 yr period (2010 June 1 to 2014 October 31). We developed the automatic detection method for CBPs based on the machine-learning technique and Zernike image moments. The average number and the mean density of CBPs are estimated to be about 572 (per full disk image taken at 193 Å) and 1.9× {10}-4 Mm-2, respectively. There is a negative correlation (-0.7) between the number of CBPs and the number of sunspots. The size and lifetime frequency distribution of CBPs show the lognormal and power-law (exponent equal to -1.6) behaviors, respectively. The relationship between the lifetime and size of CBPs is clearly treated by a power-law function with an exponent equal to 0.13. Around 1.3% of the solar surface is covered by the bright cores of CBPs and 2.6% of that is covered by their total area. About 52% of CBPs have lifetimes of less than 20 minutes and the remaining 48% have mean lifetimes of 6 hr. More than 95% of CBPs with lifetimes of less than 20 hr and nine CBPs with lifetimes of more than 72 hr are detected. The average number of the new CBPs emerging every 45 s in the whole of the Sun is about 27 ± 3. The temporal self-affinity of the time series of CBPs that emerged, indexed by the Hurst exponent determined using both detrended fluctuation analysis and R/S analysis, is 0.78. This long-temporal correlation suggests that CBPs form a system of self-organized criticality.

  3. Ultraviolet observations of LMC nova 1988

    SciTech Connect

    Starrfield, S.; Stryker, L.L.; Sonneborn, G.; Sparks, W.M.; Sion, E.M.; Wagner, R.M.; Ferland, G.; Gallagher, J.S.; Wade, R.; Williams, R.E.; Heathcote, S.; Kenyon, S.; Shaviv, G.; Wehrse, R.; Hauschildt, P.; Truran, J.W.; Wu, C.C.; Gehrz, R.D.; Ney, E.P.

    1988-01-01

    This current bright novae was first detected in outburst on March 21, 1988. Its discovery has given us the opportunity of studying the first extragalactic nova in the ultraviolet and we have, therefore, obtained a number of LWP and SWP spectra when it was at maximum. We have also obtained a high dispersion LWP spectrum in order to study the ISM in the Large Magellanic Cloud on a slightly different line-of-sight from that analyzed using SN 1987A. 10 refs., 2 figs.

  4. Investigation of ultraviolet fluxes of normal and peculiar stars

    NASA Technical Reports Server (NTRS)

    Deutschman, W. A.; Schild, R. E.

    1974-01-01

    Data from Project Celescope, a program that photographed the ultraviolet sky, in order to study several problems in current astrophysics are analyzed. Two star clusters, the Pleiades and the Hyades, reveal differences between the two that we are unable to explain simply from their differences in chemical abundance, rotation, or reddening. Data for Orion show large scatter, which appears to be in the sense that the Orion stars are too faint for their ground-based photometry. Similarly, many supergiants in the association Sco OB1 are too faint in the ultraviolet, but the ultraviolet brightness appears to be only poorly correlated with spectral type. Ultraviolet Celescope data for several groups of peculiar stars have also been analyzed. The strong He I stars are too faint in the ultraviolet, possibly owing to enhancement of O II continuous opacity due to oxygen overabundance. The Be stars appear to have ultraviolet colors normal for their MK spectral types. The P Cygni stars are considerably fainter than main-sequence stars of comparable spectral type, probably owing, at least in part, to line blocking by resonance lines of multiply ionized light metals. The Wolf-Rayet stars have ultraviolet color temperatures of O stars.

  5. High brightness picosecond electron gun

    SciTech Connect

    Merano, M.; Collin, S.; Renucci, P.; Gatri, M.; Sonderegger, S.; Crottini, A.; Ganiere, J.D.; Deveaud, B.

    2005-08-15

    We have developed a high brightness picosecond electron gun. We have used it to replace the thermionic electron gun of a commercial scanning electron microscope (SEM) in order to perform time-resolved cathodoluminescence experiments. Picosecond electron pulses are produced, at a repetition rate of 80.7 MHz, by femtosecond mode-locked laser pulses focused on a metal photocathode. This system has a normalized axial brightness of 93 A/cm{sup 2} sr kV, allowing for a spatial resolution of 50 nm in the secondary electron imaging mode of the SEM. The temporal width of the electron pulse is 12 ps.

  6. In Situ Mosaic Brightness Correction

    NASA Technical Reports Server (NTRS)

    Deen, Robert G.; Lorre, Jean J.

    2012-01-01

    In situ missions typically have pointable, mast-mounted cameras, which are capable of taking panoramic mosaics comprised of many individual frames. These frames are mosaicked together. While the mosaic software applies radiometric correction to the images, in many cases brightness/contrast seams still exist between frames. This is largely due to errors in the radiometric correction, and the absence of correction for photometric effects in the mosaic processing chain. The software analyzes the overlaps between adjacent frames in the mosaic and determines correction factors for each image in an attempt to reduce or eliminate these brightness seams.

  7. Orientation of migratory birds under ultraviolet light.

    PubMed

    Wiltschko, Roswitha; Munro, Ursula; Ford, Hugh; Stapput, Katrin; Thalau, Peter; Wiltschko, Wolfgang

    2014-05-01

    In view of the finding that cryptochrome 1a, the putative receptor molecule for the avian magnetic compass, is restricted to the ultraviolet single cones in European Robins, we studied the orientation behaviour of robins and Australian Silvereyes under monochromatic ultraviolet (UV) light. At low intensity UV light of 0.3 mW/m(2), birds showed normal migratory orientation by their inclination compass, with the directional information originating in radical pair processes in the eye. At 2.8 mW/m(2), robins showed an axial preference in the east-west axis, whereas silvereyes preferred an easterly direction. At 5.7 mW/m(2), robins changed direction to a north-south axis. When UV light was combined with yellow light, robins showed easterly 'fixed direction' responses, which changed to disorientation when their upper beak was locally anaesthetised with xylocaine, indicating that they were controlled by the magnetite-based receptors in the beak. Orientation under UV light thus appears to be similar to that observed under blue, turquoise and green light, albeit the UV responses occur at lower light levels, probably because of the greater light sensitivity of the UV cones. The orientation under UV light and green light suggests that at least at the level of the retina, magnetoreception and vision are largely independent of each other.

  8. Ultraviolet spectrophotometry from Gemini 11 of stars in Orion

    NASA Technical Reports Server (NTRS)

    Morgan, T. H.; Spear, G. G.; Kondo, Y.; Henize, K. G.

    1975-01-01

    Ultraviolet spectrophotometry in the wavelength region 2600-3600 A is reported for the bright early-type stars beta, eta, gamma, delta, iota, epsilon, sigma, zeta, and kappa Ori. The results are in good agreement with other observations, and, with the possible exception of the supergiants, are in good agreement with recent line-blanketed model atmospheres. There is evidence that the supergiants possess a small ultraviolet deficiency shortward of 3000 A relative to main-sequence stars of similar spectral type. The most extreme example of this phenomenon is the star kappa Ori.

  9. Far-ultraviolet imagery of the Orion Nebula

    NASA Technical Reports Server (NTRS)

    Carruthers, G. R.; Opal, C. B.

    1977-01-01

    Two electrographic cameras carried on a sounding rocket have yielded useful-resolution far-ultraviolet (1000-2000 A) imagery of the Orion Nebula. The brightness distribution in the images is consistent with a primary source which is due to scattering of starlight by dust grains, although an emission-line contribution, particularly in the fainter outer regions, is not ruled out. The results are consistent with an albedo of the dust grains that is high in the far-ultraviolet and which increases toward shorter wavelengths below 1230 A.

  10. The Surface Compositon of Enceladus: Clues from the Ultraviolet

    NASA Technical Reports Server (NTRS)

    Hendrix, Amanda R.; Hansen, Candice J.

    2009-01-01

    The reflectance of Saturn's moon Enceladus has been measured at far ultraviolet (FUV) wavelengths (115-190 nm) by Cassini's UltraViolet Imaging Spectrograph (UVIS). At visible and near infrared (VNIR) wavelengths Enceladus' reflectance spectrum is very bright, consistent with a surface composed primarily of H2O ice. At FUV wavelengths, however, Enceladus is surprisingly dark - darker than would be expected for pure water ice. We find that the low FUV reflectance of Enceladus can be explained by the presence of a small amount of NH3 and a small amount of a tholin in addition to H?O ice on the surface.

  11. Bright Beginnings. WWC Intervention Report

    ERIC Educational Resources Information Center

    What Works Clearinghouse, 2009

    2009-01-01

    Bright Beginnings is an early childhood curriculum, based in part on High/Scope[R] and Creative Curriculum[R], with an additional emphasis on literacy skills. The curriculum consists of nine thematic units designed to enhance children's cognitive, social, emotional, and physical development, and each unit includes concept maps, literacy lessons,…

  12. Network based sky Brightness Monitor

    NASA Astrophysics Data System (ADS)

    McKenna, Dan; Pulvermacher, R.; Davis, D. R.

    2009-01-01

    We have developed and are currently testing an autonomous 2 channel photometer designed to measure the night sky brightness in the visual wavelengths over a multi-year campaign. The photometer uses a robust silicon sensor filtered with Hoya CM500 glass. The Sky brightness is measured every minute at two elevation angles typically zenith and 20 degrees to monitor brightness and transparency. The Sky Brightness monitor consists of two units, the remote photometer and a network interface. Currently these devices use 2.4 Ghz transceivers with a free space range of 100 meters. The remote unit is battery powered with day time recharging using a solar panel. Data received by the network interface transmits data via standard POP Email protocol. A second version is under development for radio sensitive areas using an optical fiber for data transmission. We will present the current comparison with the National Park Service sky monitoring camera. We will also discuss the calibration methods used for standardization and temperature compensation. This system is expected to be deployed in the next year and be operated by the International Dark Sky Association SKYMONITOR project.

  13. Ultraviolet absorption hygrometer

    DOEpatents

    Gersh, Michael E.; Bien, Fritz; Bernstein, Lawrence S.

    1986-01-01

    An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined.

  14. Ultraviolet absorption hygrometer

    DOEpatents

    Gersh, M.E.; Bien, F.; Bernstein, L.S.

    1986-12-09

    An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined. 5 figs.

  15. The Ultraviolet Albedo of Ganymede

    NASA Astrophysics Data System (ADS)

    McGrath, Melissa; Hendrix, A.

    2013-10-01

    A large set of ultraviolet images of Ganymede have been acquired with the Hubble Space Telescope over the last 15 years. These images have been used almost exclusively to study Ganymede’s stunning auroral emissions (Feldman et al. 2000; Eviatar et al. 2001; McGrath et al. 2004; Saur et al. 2011; McGrath et al. 2013), and even the most basic information about Ganymede’s UV albedo has yet to be gleaned from these data. We will present a first-cut analysis of both disk-averaged and spatially-resolved UV albedos of Ganymede, with focus on the spatially-resolved Lyman-alpha albedo, which has never been considered previously for this satellite. Ganymede's visibly bright regions are known to be rich in water ice, while the visibly dark regions seem to be more carbonaceous (Carlson et al., 1996). At Lyman-alpha, these two species should also have very different albedo values. References Carlson, R. and 39 co-authors, Near-infrared spectroscopy and spectral mapping of Jupiter and the Galilean satellites: Results from Galileo’s initial orbit, Science, 274, 385-388, 1996. Eviatar, A., D. F. Strobel, B. C. Wolven, P. D. Feldman, M. A. McGrath, and D. J. Williams, Excitation of the Ganymede ultraviolet aurora, Astrophys. J, 555, 1013-1019, 2001. Feldman, P. D., M. A. McGrath, D. F. Strobel, H. W. Moos, K. D. Retherford, and B. C. Wolven, HST/STIS imaging of ultraviolet aurora on Ganymede, Astrophys. J, 535, 1085-1090, 2000. McGrath M. A., Lellouch E., Strobel D. F., Feldman P. D., Johnson R. E., Satellite Atmospheres, Chapter 19 in Jupiter: The Planet, Satellites and Magnetosphere, ed. F. Bagenal, T. Dowling, W. McKinnon, Cambridge University Press, 2004. McGrath M. A., Jia, Xianzhe; Retherford, Kurt; Feldman, Paul D.; Strobel, Darrell F.; Saur, Joachim, Aurora on Ganymede, J. Geophys. Res., doi: 10.1002/jgra.50122, 2013. Saur, J., S. Duling, S., L. Roth, P. D. Feldman, D. F. Strobel, K. D. Retherford, M. A. McGrath, A. Wennmacher, American Geophysical Union, Fall Meeting

  16. Near Ultraviolet Spectrograph for Cubesats

    NASA Astrophysics Data System (ADS)

    Aickara Gopinathan, Sreejith; Mathew, Joice; Sarpotdar, Mayuresh; Suresh, Ambily; Kaippacheri, Nirmal; Safonova, Margarita; Murthy, Jayant

    2017-01-01

    We have designed a near ultraviolet (200 - 400 nm) spectrograph to fit into a 2U CubeSat and planned for flight in mid-2017 with a scientific goal of obtaining NUV spectra of bright sources (< 6th magnitude) with a spectral resolution of 10 Å. The aggressive timeline drives the design to include only off-the-shelf items to minimize procurement delays and cost. Our baseline optical design consists of a collecting mirror with a 70 mm diameter which reflects light onto a concave reflection grating with a spacing of 1200 lines per mm. The grating focuses the light onto a linear array back-thinned FFT CCD with a pixel size of 14-μm × 14-μm.We will present the design of the payload and the choices forced on us by the restrictive CubeSat environment and the short lead times. This payload is a part of our program to build payloads that will address limited scientific goals but making full use of the opportunities that are arising for CubeSat class missions.

  17. Investigation of the diffuse ultraviolet background using satellite data: Dynamics explorer guest investigator program

    NASA Technical Reports Server (NTRS)

    Fix, J. D.

    1986-01-01

    The imaging instrumentation for the Dynamics Explorer Mission was designed primarily to obtain global auroral images. The instrument, however, was also used successfully to study marine bioluminescence, the geocorona, and the global distribution of atmospheric ozone. The imager has considerable potential for the study of astronomical sources of ultraviolet radiation as well. The data produced by the imager is used to study the brightness and isotrophy of the diffuse ultraviolet background.

  18. THE ULTRAVIOLET BRIGHTEST TYPE Ia SUPERNOVA 2011de

    SciTech Connect

    Brown, Peter J.

    2014-11-20

    We present and discuss the ultraviolet (UV)/optical photometric light curves and absolute magnitudes of the Type Ia supernova (SN Ia) 2011de from the Swift Ultraviolet/Optical Telescope. We find it to be the UV brightest SN Ia yet observed—more than a factor of 10 brighter than normal SNe Ia in the mid-ultraviolet. We find that the UV/optical brightness and broad light curve evolution can be modeled with additional flux from the shock of the ejecta hitting a relatively large red giant companion separated by 6 × 10{sup 13} cm. However, the post-maximum behavior of other UV-bright SNe Ia can also be modeled in a similar manner, including objects with UV spectroscopy or pre-maximum photometry which is inconsistent with this model. This suggests that similar UV luminosities can be intrinsic or caused by other forms of shock interaction. The high velocities reported for SN 2011de make it distinct from the UV-bright ''super-Chandrasekhar'' SNe Ia and the NUV-blue group of normal SNe Ia. SN 2011de is an extreme example of the UV variations in SNe Ia.

  19. Brightness-equalized quantum dots

    PubMed Central

    Lim, Sung Jun; Zahid, Mohammad U.; Le, Phuong; Ma, Liang; Entenberg, David; Harney, Allison S.; Condeelis, John; Smith, Andrew M.

    2015-01-01

    As molecular labels for cells and tissues, fluorescent probes have shaped our understanding of biological structures and processes. However, their capacity for quantitative analysis is limited because photon emission rates from multicolour fluorophores are dissimilar, unstable and often unpredictable, which obscures correlations between measured fluorescence and molecular concentration. Here we introduce a new class of light-emitting quantum dots with tunable and equalized fluorescence brightness across a broad range of colours. The key feature is independent tunability of emission wavelength, extinction coefficient and quantum yield through distinct structural domains in the nanocrystal. Precise tuning eliminates a 100-fold red-to-green brightness mismatch of size-tuned quantum dots at the ensemble and single-particle levels, which substantially improves quantitative imaging accuracy in biological tissue. We anticipate that these materials engineering principles will vastly expand the optical engineering landscape of fluorescent probes, facilitate quantitative multicolour imaging in living tissue and improve colour tuning in light-emitting devices. PMID:26437175

  20. Low-brightness quantum radar

    NASA Astrophysics Data System (ADS)

    Lanzagorta, Marco

    2015-05-01

    One of the major scientific thrusts from recent years has been to try to harness quantum phenomena to dramatically increase the performance of a wide variety of classical information processing devices. These advances in quantum information science have had a considerable impact on the development of standoff sensors such as quantum radar. In this paper we analyze the theoretical performance of low-brightness quantum radar that uses entangled photon states. We use the detection error probability as a measure of sensing performance and the interception error probability as a measure of stealthiness. We compare the performance of quantum radar against a coherent light sensor (such as lidar) and classical radar. In particular, we restrict our analysis to the performance of low-brightness standoff sensors operating in a noisy environment. We show that, compared to the two classical standoff sensing devices, quantum radar is stealthier, more resilient to jamming, and more accurate for the detection of low reflectivity targets.

  1. Brightness-equalized quantum dots.

    PubMed

    Lim, Sung Jun; Zahid, Mohammad U; Le, Phuong; Ma, Liang; Entenberg, David; Harney, Allison S; Condeelis, John; Smith, Andrew M

    2015-10-05

    As molecular labels for cells and tissues, fluorescent probes have shaped our understanding of biological structures and processes. However, their capacity for quantitative analysis is limited because photon emission rates from multicolour fluorophores are dissimilar, unstable and often unpredictable, which obscures correlations between measured fluorescence and molecular concentration. Here we introduce a new class of light-emitting quantum dots with tunable and equalized fluorescence brightness across a broad range of colours. The key feature is independent tunability of emission wavelength, extinction coefficient and quantum yield through distinct structural domains in the nanocrystal. Precise tuning eliminates a 100-fold red-to-green brightness mismatch of size-tuned quantum dots at the ensemble and single-particle levels, which substantially improves quantitative imaging accuracy in biological tissue. We anticipate that these materials engineering principles will vastly expand the optical engineering landscape of fluorescent probes, facilitate quantitative multicolour imaging in living tissue and improve colour tuning in light-emitting devices.

  2. Iapetus Bright and Dark Terrains

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Saturn's outermost large moon, Iapetus, has a bright, heavily cratered icy terrain and a dark terrain, as shown in this Voyager 2 image taken on August 22, 1981. Amazingly, the dark material covers precisely the side of Iapetus that leads in the direction of orbital motion around Saturn (except for the poles), whereas the bright material occurs on the trailing hemisphere and at the poles. The bright terrain is made of dirty ice, and the dark terrain is surfaced by carbonaceous molecules, according to measurements made with Earth-based telescopes. Iapetus' dark hemisphere has been likened to tar or asphalt and is so dark that no details within this terrain were visible to Voyager 2. The bright icy hemisphere, likened to dirty snow, shows many large impact craters. The closest approach by Voyager 2 to Iapetus was a relatively distant 600,000 miles, so that our best images, such as this, have a resolution of about 12 miles. The dark material is made of organic substances, probably including poisonous cyano compounds such as frozen hydrogen cyanide polymers. Though we know a little about the dark terrain's chemical nature, we do not understand its origin. Two theories have been developed, but neither is fully satisfactory--(1) the dark material may be organic dust knocked off the small neighboring satellite Phoebe and 'painted' onto the leading side of Iapetus as the dust spirals toward Saturn and Iapetus hurtles through the tenuous dust cloud, or (2) the dark material may be made of icy-cold carbonaceous 'cryovolcanic' lavas that were erupted from Iapetus' interior and then blackened by solar radiation, charged particles, and cosmic rays. A determination of the actual cause, as well as discovery of any other geologic features smaller than 12 miles across, awaits the Cassini Saturn orbiter to arrive in 2004.

  3. LSST Site: Sky Brightness Data

    NASA Astrophysics Data System (ADS)

    Burke, Jamison; Claver, Charles

    2015-01-01

    The Large Synoptic Survey Telescope (LSST) is an upcoming robotic survey telescope. At the telescope site on Cerro Pachon in Chile there are currently three photodiodes and a Canon camera with a fisheye lens, and both the photodiodes and Canon monitor the night sky continuously. The NIST-calibrated photodiodes directly measure the flux from the sky, and the sky brightness can also be obtained from the Canon images via digital aperture photometry. Organizing and combining the two data sets gives nightly information of the development of sky brightness across a swath of the electromagnetic spectrum, from blue to near infrared light, and this is useful for accurately predicting the performance of the LSST. It also provides data for models of moonlight and twilight sky brightness. Code to accomplish this organization and combination was successfully written in Python, but due to the backlog of data not all of the nights were processed by the end of the summer.Burke was supported by the NOAO/KPNO Research Experiences for Undergraduates (REU) Program which is funded by the National Science Foundation Research Experiences for Undergraduates Program (AST-1262829).

  4. The ultraviolet spectra of M31 globular clusters

    NASA Technical Reports Server (NTRS)

    Cowley, A. P.; Burstein, D.

    1988-01-01

    Ultraviolet spectra of 11 of the brightest globular clusters in M31 show that some exhibit residual flux below 3000 A, greater than that expected from the bright, evolved stars in the cluster. There seems to be no apparent correlation of the strength of this ultraviolet flux with parameters such as metallicity, U-B color, visual magnitude, X-ray emission, or location within the parent galaxy. However, comparison of the ultraviolet colors of the M31 globular clusters with those in the Galaxy and in the Large Magellanic Cloud suggests that the M31 clusters may contain a high percentage of blue horizontal-branch stars or that some clusters could be as young as about 2 x 10 to the 9th yr.

  5. High-brightness rf linear accelerators

    SciTech Connect

    Jameson, R.A.

    1986-01-01

    The issue of high brightness and its ramifications in linacs driven by radio-frequency fields is discussed. A history of the RF linacs is reviewed briefly. Some current applications are then examined that are driving progress in RF linacs. The physics affecting the brightness of RF linacs is then discussed, followed by the economic feasibility of higher brightness machines. (LEW)

  6. Comparative Analysis of a Transition Region Bright Point with a Blinker and Coronal Bright Point Using Multiple EIS Emission Lines

    NASA Astrophysics Data System (ADS)

    Orange, N. Brice; Oluseyi, Hakeem M.; Chesny, David L.; Patel, Maulik; Hesterly, Katie; Preuss, Lauren; Neira, Chantale; Turner, Niescja E.

    2014-05-01

    Since their discovery 20 year ago, transition region bright points have never been observed spectroscopically. Bright point properties have not been compared with similar transition region and coronal structures. In this work we have investigated three transient quiet Sun brightenings including a transition region bright point (TR BP), a coronal bright point (CBP) and a blinker. We use time-series observations of the extreme-ultraviolet emission lines of a wide range of temperature T (log T=5.3 - 6.4) from the EUV Imaging Spectrometer (EIS) onboard the Hinode satellite. We present the EIS temperature maps and Doppler maps, which are compared with magnetograms from the Michelson Doppler Imager (MDI) onboard the SOHO satellite. Doppler velocities of the TR BP and blinker are ≤ 25 km s-1, which is typical of transient TR phenomena. The Doppler velocities of the CBP were found to be ≤ 20 km s-1 with exception of those measured at log T=6.2 where a distinct bi-directional jet is observed. From an EM loci analysis we find evidence of single and double isothermal components in the TR BP and CBP, respectively. TR BP and CBP loci curves are characterized by broad distributions suggesting the existence of unresolved structure. By comparing and contrasting the physical characteristics of the events we find that the BP phenomena are an indication of multi-scaled self-similarity, given the similarities in both their underlying magnetic field configuration and evolution in relation to EUV flux changes. In contrast, the blinker phenomena and the TR BP are sufficiently dissimilar in their observed properties as to constitute different event classes. Our work is an indication that the measurement of similar characteristics across multiple event types holds class-predictive power, and is a significant step towards automated solar atmospheric multi-class classification of unresolved transient EUV sources. Finally, the analysis performed here establishes a connection between solar

  7. High brightness beams and applications

    SciTech Connect

    Sheffield, R.L.

    1995-09-01

    This paper describes the present research on attaining intense bright electron beams. Thermionic systems are briefly covered. Recent and past results from the photoinjector programs are given. The performance advantages and difficulties presently faced by researchers using photoinjectors is discussed. The progress that has been made in photocathode materials, both in lifetime and quantum efficiency, is covered. Finally, a discussion of emittance measurements of photoinjector systems and how the measurement is complicated by the non-thermal nature of the electron beam is presented.

  8. ASASSN-15lh: A Superluminous Ultraviolet Rebrightening Observed by Swift and Hubble

    NASA Astrophysics Data System (ADS)

    Brown, Peter J.; Yang, Yi; Cooke, Jeff; Olaes, Melanie; Quimby, Robert M.; Baade, Dietrich; Gehrels, Neil; Hoeflich, Peter; Maund, Justyn; Mould, Jeremy; Wang, Lifan; Wheeler, J. Craig

    2016-09-01

    We present and discuss ultraviolet and optical photometry from the Ultraviolet/Optical Telescope, X-ray limits from the X-Ray Telescope on Swift, and imaging polarimetry and ultraviolet/optical spectroscopy with the Hubble Space Telescope, all from observations of ASASSN-15lh. It has been classified as a hydrogen-poor superluminous supernova (SLSN I), making it more luminous than any other supernova observed. ASASSN-15lh is not detected in the X-rays in individual or co-added observations. From the polarimetry we determine that the explosion was only mildly asymmetric. We find the flux of ASASSN-15lh to increase strongly into the ultraviolet, with an ultraviolet luminosity 100 times greater than the hydrogen-rich, ultraviolet-bright SLSN II SN 2008es. We find that objects as bright as ASASSN-15lh are easily detectable beyond redshifts of ˜4 with the single-visit depths planned for the Large Synoptic Survey Telescope. Deep near-infrared surveys could detect such objects past a redshift of ˜20, enabling a probe of the earliest star formation. A late rebrightening—most prominent at shorter wavelengths—is seen about two months after the peak brightness, which is itself as bright as an SLSN. The ultraviolet spectra during the rebrightening are dominated by the continuum without the broad absorption or emission lines seen in SLSNe or tidal disruption events (TDEs) and the early optical spectra of ASASSN-15lh. Our spectra show no strong hydrogen emission, showing only Lyα absorption near the redshift previously found by optical absorption lines of the presumed host. The properties of ASASSN-15lh are extreme when compared to either SLSNe or TDEs. Based on observations with the NASA/ESA Hubble Space Telescope (HST) obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555.

  9. Jupiter in blue, ultraviolet and near infrared

    NASA Technical Reports Server (NTRS)

    2000-01-01

    These three images of Jupiter, taken through the narrow angle camera of NASA's Cassini spacecraft from a distance of 77.6 million kilometers (48.2 million miles) on October 8, reveal more than is apparent to the naked eye through a telescope.

    The image on the left was taken through the blue filter. The one in the middle was taken in the ultraviolet. The one on the right was taken in the near infrared.

    The blue-light filter is within the part of the electromagnetic spectrum detectable by the human eye. The appearance of Jupiter in this image is, consequently, very familiar. The Great Red Spot (below and to the right of center) and the planet's well-known banded cloud lanes are obvious. The brighter bands of clouds are called zones and are probably composed of ammonia ice particles. The darker bands are called belts and are made dark by particles of unknown composition intermixed with the ammonia ice.

    Jupiter's appearance changes dramatically in the ultraviolet and near infrared images. These images are near negatives of each other and illustrate the way in which observations in different wavelength regions can reveal different physical regimes on the planet.

    All gases scatter sunlight efficiently at short wavelengths; this is why the sky appears blue on Earth. The effect is even more pronounced in the ultraviolet. The gases in Jupiter's atmosphere, above the clouds, are no different. They scatter strongly in the ultraviolet, making the deep banded cloud layers invisible in the middle image. Only the very high altitude haze appears dark against the bright background. The contrast is reversed in the near infrared, where methane gas, abundant on Jupiter but not on Earth, is strongly absorbing and therefore appears dark. Again the deep clouds are invisible, but now the high altitude haze appears relatively bright against the dark background. High altitude haze is seen over the poles and the equator.

    The Great Red Spot, prominent in all images, is

  10. Ultraviolet Mars Reveals Cloud Formation

    NASA Video Gallery

    Images from MAVEN's Imaging UltraViolet Spectrograph were used to make this movie of rapid cloud formation on Mars on July 9-10, 2016. The ultraviolet colors of the planet have been rendered in fal...

  11. Ultraviolet reflective coating

    NASA Technical Reports Server (NTRS)

    Schutt, J. B.

    1974-01-01

    Composition consists of dispersion of barium sulphate in aqueous solution of water-soluble inorganic binder. Binder is selected from group consisting of alkali metal sulphates. Coating exhibits high reflectance of ultraviolet light to wavelengths of approximately 200.0 nm, which compares favorably with high reflectance of virgin barium sulphate power.

  12. Ultraviolet radiation changes

    NASA Technical Reports Server (NTRS)

    Mckenzie, Richard L.; Frederick, John E.; Ilyas, Mohammad; Filyushkin, V.; Wahner, Andreas; Stamnes, K.; Muthusubramanian, P.; Blumthaler, M.; Roy, Colin E.; Madronich, Sasha

    1991-01-01

    A major consequence of ozone depletion is an increase in solar ultraviolet (UV) radiation received at the Earth's surface. This chapter discusses advances that were made since the previous assessment (World Meteorological Organization (WMO)) to our understanding of UV radiation. The impacts of these changes in UV on the biosphere are not included, because they are discussed in the effects assessment.

  13. Development of ultraviolet lasers

    NASA Technical Reports Server (NTRS)

    Walters, G. K.

    1974-01-01

    The pulsed electron accelerator selected for use in the development of ultraviolet laser capability suitable for use in photoexcitation and photoionization studies of the upper atmosphere is reported. Performance figures, installation specifications, and total cost of the equipment are briefly shown, and plans for further studies are outlined.

  14. Psoriasis and ultraviolet radiation

    SciTech Connect

    Farber, E.M.; Nall, L. )

    1993-09-01

    Prevention and detection screening programs as a public health service in curtailing the ever-increasing incidence of all forms of skin cancer are reviewed. The effect of solar and artificial ultraviolet radiation on the general population and persons with psoriasis is examined. 54 refs.

  15. International Ultraviolet Explorer

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This report is the November 6, 1996 - October 9, 1997, IUE Final Report for the International Ultraviolet Explorer Final Archive contract. The ultimate objective of this contract is the completion of the archival reprocessing of all IUE data obtained at GSFC between 1978 and 1995.

  16. International Ultraviolet Explorer (IUE) ultraviolet spectral atlas of selected astronomical objects

    NASA Technical Reports Server (NTRS)

    Wu, Chi-Chao; Reichert, Gail A.; Ake, Thomas B.; Boggess, Albert; Holm, Albert V.; Imhoff, Catherine L.; Kondo, Yoji; Mead, Jaylee M.; Shore, Steven N.

    1992-01-01

    The IUE Ultraviolet Spectral Atlas of Selected Astronomical Objects (or 'the Atlas'), is based on the data that were available in the IUE archive in 1986, and is intended to be a quick reference for the ultraviolet spectra of many categories of astronomical objects. It shows reflected sunlight from the Moon, planets, and asteroids, and also shows emission from comets. Comprehensive compilations of UV spectra for main sequence, subgiant, giant, bright giant, and supergiant stars are published elsewhere. This Atlas contains the spectra for objects occupying other areas of the Hertzsprung-Russell diagram: pre-main sequence stars, chemically peculiar stars, pulsating variables, subluminous stars, and Wolf-Rayet stars. This Atlas also presents phenomena such as the chromospheric and transition region emissions from late-type stars; composite spectra of stars, gas streams, accretion disks and gas envelopes of binary systems; the behavior of gas ejecta shortly after the outburst of novac and supernovac; and the H II regions, planetary nebulae, and supernova remnants. Population 2 stars, globular clusters, and luminous stars in the Magellanic Clouds, M31, and M33, are also included in this publication. Finally, the Atlas gives the ultraviolet spectra of galaxies of different Hubble types and of active galaxies.

  17. How Bright Can Supernovae Get?

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-04-01

    Supernovae enormous explosions associated with the end of a stars life come in a variety of types with different origins. A new study has examined how the brightest supernovae in the Universe are produced, and what limits might be set on their brightness.Ultra-Luminous ObservationsRecent observations have revealed many ultra-luminous supernovae, which haveenergies that challenge our abilities to explain them usingcurrent supernova models. An especially extreme example is the 2015 discovery of the supernova ASASSN-15lh, which shone with a peak luminosity of ~2*1045 erg/s, nearly a trillion times brighter than the Sun. ASASSN-15lh radiated a whopping ~2*1052 erg in the first four months after its detection.How could a supernova that bright be produced? To explore the answer to that question, Tuguldur Sukhbold and Stan Woosley at University of California, Santa Cruz, have examined the different sources that could produce supernovae and calculated upper limits on the potential luminosities ofeach of these supernova varieties.Explosive ModelsSukhbold and Woosley explore multiple different models for core-collapse supernova explosions, including:Prompt explosionA stars core collapses and immediately explodes.Pair instabilityElectron/positron pair production at a massive stars center leads to core collapse. For high masses, radioactivity can contribute to delayed energy output.Colliding shellsPreviously expelled shells of material around a star collide after the initial explosion, providing additional energy release.MagnetarThe collapsing star forms a magnetar a rapidly rotating neutron star with an incredibly strong magnetic field at its core, which then dumps energy into the supernova ejecta, further brightening the explosion.They then apply these models to different types of stars.Setting the LimitThe authors show that the light curve of ASASSN-15lh (plotted in orange) can be described by a model (black curve) in which a magnetar with an initial spin period of 0.7 ms

  18. Limb displacement and brightness seismology

    NASA Astrophysics Data System (ADS)

    Emilio, Marcelo; Cunnyngham, Ian; Kuhn, Jeff; Mehret, Leandro; Bush, Rock; Scholl, Isabelle

    2015-08-01

    The Helioseismic and Magnetic Imager (HMI) abord the Solar Dynamics Observatory (SDO) has been used to obtain the most sensitive spectrally resolved observation of individual p-modes at the extreme solar limb. Such oscillation observations of the limb displacement and brightness for some spatial and temporal regimes are even competitive in signal-to-noise to full-disk doppler measurements of the p-mode spectrum. Limb measurements of 5-min p-modes, while having many similarities to full-disk doppler observations, have significantly different sensitivities to the solar rotation and the 5-min mode solar atmospheric structure. These may provide information about the solar structure which is complementary to full-disk measurements. In this work we present results from Individual spherical harmonic p-modes that were detected around solar limb with amplitudes at the micro-arcsecond level.

  19. Bright diode laser light source.

    PubMed

    Lassila, Erkki; Hernberg, Rolf

    2006-05-20

    A simplified multiwavelength prototype of an axially symmetric diode laser device based on stacks made of single emitters has been made, and the performance of the device has been demonstrated experimentally. The results verify that kilowatt-level light power can be focused into a circular spot with a 1/e2 diameter of 360 microm, a focal length of 100 mm, and a numerical aperture of 0.24, thus producing an average power density in excess of 10 kW/mm2 and a brightness of 6x10(10) W m-2 sr-1. The experiments also predict that it will be possible to increase these values to more than 60 kW/mm2 and 3x10(11) W m-2 sr-1.

  20. Night sky brightness measurement at PERMATApintar observatory

    NASA Astrophysics Data System (ADS)

    Azhar, A. D.; Gopir, G.; Kamil, W. M. A. Wan Mohd; Mohamad, N. S.; Azmi, N. Che

    2016-11-01

    One of the quality parameter of an astronomical site testing is sky brightness. We measure the night sky brightness over PERMATApintar Observatory to obtain the first preliminary sky brightness reading. The measurement is done by using an Unihedron Sky Quality Meter (SQM-LU) with a position pointing zenith. Six measurements have been done during the period of January to March 2016. The measurement is taken between approximately 7 p.m. to 11 p.m. on each of the night. The best (darken) night sky brightness reading is 19.54 mag/arcsec2 obtained on March 11th, 2016. The preliminary average reading of sky brightness is 17.20 mag/arcsec2. Comparison with previous similar measurement for the same type of area (suburban area) shows that our data is within the range of the sky brightness for suburban area, which is 19.5 to 20.7 mag/arcsec2.

  1. Far ultraviolet instrument technology

    NASA Astrophysics Data System (ADS)

    Paxton, Larry J.; Schaefer, Robert K.; Zhang, Yongliang; Kil, Hyosub

    2017-02-01

    The far ultraviolet (FUV) spectral range (from about 115 nm to 180 nm) is one of the most useful spectral regions for characterizing the upper atmosphere (thermosphere and ionosphere). The principal advantages are that there are FUV signatures of the major constituents of the upper atmosphere as well as the signatures of the high-latitude energy inputs. Because of the absorption by thermospheric O2, the FUV signatures are seen against a "black" background, i.e., one that is not affected by ground albedo or clouds and, as a consequence, can make useful observations of the aurora during the day or when the Moon is above the horizon. In this paper we discuss the uses of FUV remote sensing, summarize the various techniques, and discuss the technological challenges. Our focus is on a particular type of FUV instrument, the scanning imaging spectrograph or SIS: an instrument exemplified by the Defense Meteorological Satellite Program Special Sensor Ultraviolet Imager and Thermosphere Ionosphere Mesosphere Energetics and Dynamics Global Ultraviolet Imager. The SIS combines spatial imaging of the disk with limb profiles as well as spectral information at each point in the scan.

  2. The GALEX Ultraviolet Atlas of Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Gil de Paz, Armando; Boissier, Samuel; Madore, Barry F.; Seibert, Mark; Joe, Young H.; Boselli, Alessandro; Wyder, Ted K.; Thilker, David; Bianchi, Luciana; Rey, Soo-Chang; Rich, R. Michael; Barlow, Tom A.; Conrow, Tim; Forster, Karl; Friedman, Peter G.; Martin, D. Christopher; Morrissey, Patrick; Neff, Susan G.; Schiminovich, David; Small, Todd; Donas, José; Heckman, Timothy M.; Lee, Young-Wook; Milliard, Bruno; Szalay, Alex S.; Yi, Sukyoung

    2007-12-01

    We present images, integrated photometry, and surface-brightness and color profiles for a total of 1034 nearby galaxies recently observed by the Galaxy Evolution Explorer (GALEX) satellite in its far-ultraviolet (FUV; λeff=1516 Å) and near-ultraviolet (NUV; λeff=2267 Å) bands. Our catalog of objects is derived primarily from the GALEX Nearby Galaxies Survey (NGS) supplemented by galaxies larger than 1' in diameter serendipitously found in these fields and in other GALEX exposures of similar of greater depth. The sample analyzed here adequately describes the distribution and full range of properties (luminosity, color, star formation rate [SFR]) of galaxies in the local universe. From the surface brightness profiles obtained we have computed asymptotic magnitudes, colors, and luminosities, along with the concentration indices C31 and C42. We have also morphologically classified the UV surface brightness profiles according to their shape. This data set has been complemented with archival optical, near-infrared, and far-infrared fluxes and colors. We find that the integrated (FUV-K) color provides robust discrimination between elliptical and spiral/irregular galaxies and also among spiral galaxies of different subtypes. Elliptical galaxies with brighter K-band luminosities (i.e., more massive) are redder in (NUV-K) color but bluer in (FUV-NUV) (a color sensitive to the presence of a strong UV upturn) than less massive ellipticals. In the case of the spiral/irregular galaxies our analysis shows the presence of a relatively tight correlation between the (FUV-NUV) color (or, equivalently, the slope of the UV spectrum, β) and the total infrared-to-UV ratio. The correlation found between (FUV-NUV) color and K-band luminosity (with lower luminosity objects being bluer than more luminous ones) can be explained as due to an increase in the dust content with galaxy luminosity. The images in this Atlas along with the profiles and integrated properties are publicly

  3. Research in extreme ultraviolet and far ultraviolet astronomy

    NASA Technical Reports Server (NTRS)

    Labov, S. E.

    1985-01-01

    Instruments designed to explore different aspects of far and extreme ultraviolet cosmic radiation were studied. The far ultraviolet imager (FUVI) was flown on the Aries sounding rocket. Its unique large format 75mm detector mapped out the far ultraviolet background radiation with a resolution of only a few arc minutes. Analysis of this data indicates to what extent the FUVI background is extra galactic in origin. A power spectrum of the spatial fluctuations will have direct consequences for galactic evolution.

  4. Brightness alteration with interweaving contours.

    PubMed

    Roncato, Sergio

    2012-01-01

    Chromatic induction is observed whenever the perceived colour of a target surface shifts towards the hue of a neighbouring surface. Some vivid manifestations may be seen in a white background where thin coloured lines have been drawn (assimilation) or when lines of different colours are collinear (neon effect) or adjacent (watercolour) to each other. This study examines a particular colour induction that manifests in concomitance with an opposite effect of colour saturation (or anti-spread). The two phenomena can be observed when a repetitive pattern is drawn in which outline thin contours intercept wider contours or surfaces, colour spreading appear to fill the surface occupied by surfaces or thick lines whereas the background traversed by thin lines is seen as brighter or filled of a saturated white. These phenomena were first observed by Bozzi (1975) and Kanizsa (1979) in figural conditions that did not allow them to document their conjunction. Here we illustrate various manifestations of this twofold phenomenon and compare its effects with the known effects of brightness and colour induction. Some conjectures on the nature of these effects are discussed.

  5. Bright Star Astrometry with URAT

    NASA Astrophysics Data System (ADS)

    Zacharias, N.

    2015-10-01

    The U.S. Naval Observatory Robotic Astrometric Telescope (URAT) is observing the northern sky since April 2012 for an astrometric survey. Multiple overlaps per year are performed in a single bandpass (680-750 nm) using the "redlens" 20 cm aperture astrograph and a mosaic of large CCDs. Besides the regular, deep survey to magnitude 18.5, short exposures with an objective grating are taken to access stars as bright as 3rd magnitude. A brief overview of the program, observing and reductions is given. Positions on the 8 to 20 mas level are obtained of 66,202 Hipparcos stars at current epochs. These are compared to the Hipparcos Catalog to investigate its accuracy. About 20% of the observed Hipparcos stars are found to have inconsistent positions with the Hipparcos Catalog prediction on the 3 sigma level or over (about 75 mas or more discrepant position offsets). Some stars are now seen at an arcsec (or 25 sigma) off their Hipparcos Catalog predicted position.

  6. Spatial Brightness Perception of Trichromatic Stimuli

    SciTech Connect

    Royer, Michael P.; Houser, Kevin W.

    2012-11-16

    An experiment was conducted to examine the effect of tuning optical radiation on brightness perception for younger (18-25 years of age) and older (50 years of age or older) observers. Participants made forced-choice evaluations of the brightness of a full factorial of stimulus pairs selected from two groups of four metameric stimuli. The large-field stimuli were created by systematically varying either the red or the blue primary of an RGB LED mixture. The results indicate that light stimuli of equal illuminance and chromaticity do not appear equally bright to either younger or older subjects. The rank-order of brightness is not predicted by any current model of human vision or theory of brightness perception including Scotopic to Photopic or Cirtopic to Photopic ratio theory, prime color theory, correlated color temperature, V(λ)-based photometry, color quality metrics, linear brightness models, or color appearance models. Age may affect brightness perception when short-wavelength primaries are used, especially those with a peak wavelength shorter than 450 nm. The results suggest further development of metrics to predict brightness perception is warranted, and that including age as a variable in predictive models may be valuable.

  7. Vehicle/Atmosphere Interaction Glows: Far Ultraviolet, Visible, and Infrared

    NASA Technical Reports Server (NTRS)

    Swenson, G.

    1999-01-01

    Spacecraft glow information has been gathered from a number of spacecraft including Atmospheric and Dynamic satellites, and Space Shuttles (numerous flights) with dedicated pallet flow observations on STS-39 (DOD) and STS-62 (NASA). In addition, a larger number of laboratory experiments with low energy oxygen beam studies have made important contributions to glow understanding. The following report provides information on three engineering models developed for spacecraft glow including the far ultraviolet to ultraviolet (1400-4000 A), and infrared (0.9-40 microns) spectral regions. The models include effects resulting from atmospheric density/altitude, spacecraft temperature, spacecraft material, and ram angle. Glow brightness would be predicted as a function of distance from surfaces for all wavelengths.

  8. Observing SN 1987A with the International Ultraviolet Explorer

    NASA Technical Reports Server (NTRS)

    Kirshner, Robert P.

    1991-01-01

    The International Ultraviolet Explorer (IUE) satellite played a leading role in elucidating the nature of SN 1987A, providing a unique ultraviolet perspective on the brightest supernova since 1604. IUE observations of SN 1987A began promptly after discovery and were frequent through 1988 and 1989, using the FES (Fine Error Sensor) for photometry, low dispersion spectra for the supernova spectrum, high dispersion observations for the interstellar medium when the supernova was bright, and for circumstellar gas surrounding the supernova as the initial event faded. The UV data were especially useful in determining which star exploded, assessing the ionizing pulse produced as the shock hit the surface of the star, and in constraining the stellar evolution that preceded the explosion through observation of a circumstellar shell.

  9. The Lunar Phase Curve in the Near Ultraviolet

    NASA Technical Reports Server (NTRS)

    Hendrix, A. R.

    2002-01-01

    We present results from an ongoing program to perform UV measurements (215.0 and 237.0 nm) of the Moon at varying solar phase angles to understand the lunar phase curve at ultraviolet wavelengths. We use new observations from the Ultraviolet Spectrometer (UVS) aboard the Student Nitric Oxide Explorer (SNOE) combined with existing observations from the Galileo UVS. The lunar UV phase curve can be used to further understand the scattering properties of the lunar surface. The Moon's scattering properties at visible wavelengths are well understood; studying scattering properties at shorter wavelengths may provide insight into the roles of volume scattering vs. surface scattering and how weathering processes may affect scattering properties. The UV lunar phase curve can also be helpful for UV observers, as the Moon is often used as a UV calibration source, but the UV brightness variation with phase angle has not been well understood.

  10. Galileo Ultraviolet Spectrometer experiment

    NASA Technical Reports Server (NTRS)

    Hord, C. W.; Mcclintock, W. E.; Stewart, A. I. F.; Barth, C. A.; Esposito, L. W.; Thomas, G. E.; Sandel, B. R.; Hunten, D. M.; Broadfoot, A. L.; Shemansky, D. E.

    1992-01-01

    The Galileo ultraviolet spectrometer experiment uses data obtained by the Ultraviolet Spectrometer (UVS) mounted on the pointed orbiter scan platform and from the Extreme Ultraviolet Spectrometer (EUVS) mounted on the spinning part of the orbiter with the field of view perpendicular to the spin axis. The UVS is a Ebert-Fastie design that covers the range 113-432 nm with a wavelength resolution of 0.7 nm below 190 and 1.3 nm at longer wavelengths. The UVS spatial resolution is 0.4 deg x 0.1 deg for illuminated disk observations and 1 deg x 0.1 deg for limb geometries. The EUVS is a Voyager design objective grating spectrometer, modified to cover the wavelength range from 54 to 128 nm with wavelength resolution 3.5 nm for extended sources and 1.5 nm for point sources and spatial resolution of 0.87 deg x 0.17 deg. The EUVS instrument will follow up on the many Voyager UVS discoveries, particularly the sulfur and oxygen ion emissions in the Io torus and molecular and atomic hydrogen auroral and airglow emissions from Jupiter. The UVS will obtain spectra of emission, absorption, and scattering features in the unexplored, by spacecraft, 170-432 nm wavelength region. The UVS and EUVS instruments will provide a powerful instrument complement to investigate volatile escape and surface composition of the Galilean satellites, the Io plasma torus, micro- and macro-properties of the Jupiter clouds, and the composition structure and evolution of the Jupiter upper atmosphere.

  11. Bright Sparks of Our Future!

    NASA Astrophysics Data System (ADS)

    Riordan, Naoimh

    2016-04-01

    My name is Naoimh Riordan and I am the Vice Principal of Rockboro Primary School in Cork City, South of Ireland. I am a full time class primary teacher and I teach 4th class, my students are aged between 9-10 years. My passion for education has developed over the years and grown towards STEM (Science, Technology, Engineering and Mathematics) subjects. I believe these subjects are the way forward for our future. My passion and beliefs are driven by the unique after school programme that I have developed. It is titled "Sparks" coming from the term Bright Sparks. "Sparks" is an after school programme with a difference where the STEM subjects are concentrated on through lessons such as Science, Veterinary Science Computer Animation /Coding, Eco engineering, Robotics, Magical Maths, Chess and Creative Writing. All these subjects are taught through activity based learning and are one-hour long each week for a ten-week term. "Sparks" is fully inclusive and non-selective which gives all students of any level of ability an opportunity to engage into these subjects. "Sparks" is open to all primary students in County Cork. The "Sparks" after school programme is taught by tutors from the different Universities and Colleges in Cork City. It works very well because the tutor brings their knowledge, skills and specialised equipment from their respective universities and in turn the tutor gains invaluable teaching practise, can trial a pilot programme in a chosen STEM subject and gain an insight into what works in the physical classroom.

  12. Bright Streaks and Dark Fans

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The south polar region of Mars is covered every year by a layer of carbon dioxide ice. In a region called the 'cryptic terrain,' the ice is translucent and sunlight can penetrate through the ice to warm the surface below.

    The ice layer sublimates (evaporates) from the bottom. The dark fans of dust seen in this image come from the surface below the layer of ice, carried to the top by gas venting from below. The translucent ice is 'visible' by virtue of the effect it has on the tone of the surface below, which would otherwise have the same color and reflectivity as the fans.

    Bright streaks in this image are fresh frost. The CRISM team has identified the composition of these streaks to be carbon dioxide.

    Observation Geometry Image PSP_003113_0940 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 26-Mar-2007. The complete image is centered at -85.8 degrees latitude, 106.0 degrees East longitude. The range to the target site was 244.9 km (153.0 miles). At this distance the image scale is 49.0 cm/pixel (with 2 x 2 binning) so objects 147 cm across are resolved. The image shown here has been map-projected to 50 cm/pixel . The image was taken at a local Mars time of 06:20 PM and the scene is illuminated from the west with a solar incidence angle of 79 degrees, thus the sun was about 11 degrees above the horizon. At a solar longitude of 207.6 degrees, the season on Mars is Northern Autumn.

  13. Ultraviolet Background Radiation (Preprint)

    DTIC Science & Technology

    1991-03-01

    5.4 Apollo-Soyuz 3 5 5.5 Evidence for Scattering From Dust ? 3 8 5.6 More Evidence For Scattering From Dust ? 4 0 5.7 More Observations 4 2...Emission from cold interstellar dust . This has been observed by IRAS as the 100 u.m cosmic cirrus (64). The existence of such dust at moderate and... DUST 4 6 CONCLUSIONS 4 7 6.1 Spectral Structure in the Diffuse 4 7 Ultraviolet Background 6.2 Is There Light Scattered From Dust ? 4 7 6.3

  14. Ultraviolet atomic emission detector

    NASA Technical Reports Server (NTRS)

    Braun, W.; Peterson, N. C.; Bass, A. M.; Kurylo, M. J., III (Inventor)

    1972-01-01

    A device and method are provided for performing qualitative and quantitative elemental analysis through the utilization of a vacuum UV chromatographic detector. The method involves the use of a carrier gas at low pressure. The gas carries a sample to a gas chromatograph column; the column output is directed to a microwave cavity. In this cavity, a low pressure microwave discharge produces fragmentation of the compounds present and generates intense atomic emissions in the vacuum ultraviolet. These emissions are isolated by a monochromator and measured by photometer to establish absolute concentration for the elements.

  15. Transparent ultraviolet photovoltaic cells.

    PubMed

    Yang, Xun; Shan, Chong-Xin; Lu, Ying-Jie; Xie, Xiu-Hua; Li, Bing-Hui; Wang, Shuang-Peng; Jiang, Ming-Ming; Shen, De-Zhen

    2016-02-15

    Photovoltaic cells have been fabricated from p-GaN/MgO/n-ZnO structures. The photovoltaic cells are transparent to visible light and can transform ultraviolet irradiation into electrical signals. The efficiency of the photovoltaic cells is 0.025% under simulated AM 1.5 illumination conditions, while it can reach 0.46% under UV illumination. By connecting several such photovoltaic cells in a series, light-emitting devices can be lighting. The photovoltaic cells reported in this Letter may promise the applications in glass of buildings to prevent UV irradiation and produce power for household appliances in the future.

  16. Absolute measurement of undulator radiation in the extreme ultraviolet

    NASA Astrophysics Data System (ADS)

    Maezawa, H.; Mitani, S.; Suzuki, Y.; Kanamori, H.; Tamamushi, S.; Mikuni, A.; Kitamura, H.; Sasaki, T.

    1983-04-01

    The spectral brightness of undulator radiation emitted by the model PMU-1 incorporated in the SOR-RING, the dedicated synchrotron radiation source in Tokyo, has been studied in the extreme ultraviolet region from 21.6 to 72.9 eV as a function of the electron energy γ, the field parameter K, and the angle of observation ϴ in the absolute scale. A series of measurements covering the first and the second harmonic component of undulator radiation was compared with the fundamental formula λ n= {λ 0}/{2nγ 2}( {1+K 2}/{2}+γϴ 2 and the effects of finite emittance were studied. The brightness at the first peak was smaller than the theoretical value, while an enhanced second harmonic component was observed.

  17. Far-ultraviolet observations of the supernova remnant N49 using the Hopkins Ultraviolet Telescope

    NASA Technical Reports Server (NTRS)

    Vancura, Olaf; Blair, William P.; Long, Knox S.; Davidsen, Arthur F.; Bowers, Charles W.; Dixon, W. V. D.; Durrance, Samuel T.; Feldman, Paul D.; Ferguson, Henry C.; Henry, Richard C.

    1992-01-01

    The Hopkins Ultraviolet Telescope has been used to obtain the first sub-Lyman-alpha spectrum of an extragalactic SNR, N49, in the LMC. Emission from O VI 1032, 1038 has been detected in this spectral region. The measured fluxes of C IV, semiforbidden O IV, and O VI and the upper limit on N V provide stringent limits on the shocks responsible for the bulk of the O VI production. O VI cannot originate in the shocks with velocities of 140 km/s or less because the postshock temperature is not high enough. The nonradiative main blast wave cannot account for the brightness of the observed O VI emission. The majority of the O VI must originate in an optically faint system of shocks with velocities of 190-270 km/s and preshock densities of 20-40 cu cm. The emission from such high-velocity shocks is dominated by O VI.

  18. Brightness of the solar F-corona

    NASA Astrophysics Data System (ADS)

    Kimura, Hiroshi; Mann, Ingrid

    1998-06-01

    We discuss our present knowledge about the brightness of the solar F-corona in the wavelength range from the visible to the middle infrared. From the general trend of the observational data, the F-corona is regarded as the continuous extension of the zodiacal light at smaller elongation of the line of sight. A contribution of thermal emission from dust is indicated by the increasing F-coronal brightness in comparison to the solar spectrum towards longer wavelength. As compared with the F-coronal brightness, the polarization and color in the visible regime are not well determined due to the high sensitivity of these quantities to the observational accuracy. Aside from observational problems, our present interpretation of the F-coronal brightness is also limited due to ambiguities in the inversion of the line of sight integral. Nevertheless, the measurements and model calculations of the brightness can be used to deduce some physical properties of dust grains. We show that the hump of the near-infrared brightness at 4 solar radii, which was sometimes observed in the corona, is related rather to the physical properties of dust grains along the line of sight than to the existence of a dust ring as previously discussed. We also show that the appearance or disappearance of the near-infrared peak in the coronal brightness cannot be described in any periodic cycle for each wavelength range.

  19. Galaxy Selection and the Surface Brightness Distribution

    NASA Astrophysics Data System (ADS)

    McGaugh, Stacy S.; Bothun, Gregory D.; Schombert, James M.

    1995-08-01

    Optical surveys for galaxies are biased against the inclusion of low surface brightness (LSB) galaxies. Disney [Nature, 263,573(1976)] suggested that the constancy of disk central surface brightness noticed by Freeman [ApJ, 160,811(1970)] was not a physical result, but instead was an artifact of sample selection. Since LSB galaxies do exist, the pertinent and still controversial issue is if these newly discovered galaxies constitute a significant percentage of the general galaxy population. In this paper, we address this issue by determining the space density of galaxies as a function of disk central surface brightness. Using the physically reasonable assumption (which is motivated by the data) that central surface brightness is independent of disk scale length, we arrive at a distribution which is roughly flat (i.e., approximately equal numbers of galaxies at each surface brightness) faintwards of the Freeman (1970) value. Brightwards of this, we find a sharp decline in the distribution which is analogous to the turn down in the luminosity function at L^*^. An intrinsically sharply peaked "Freeman law" distribution can be completely ruled out, and no Gaussian distribution can fit the data. Low surface brightness galaxies (those with central surface brightness fainter than 22 B mag arcsec^-2^) comprise >~ 1/2 the general galaxy population, so a representative sample of galaxies at z = 0 does not really exist at present since past surveys have been insensitive to this component of the general galaxy population.

  20. The Ultraviolet Sky as Observed by the Shuttle-Borne Ultraviolet Imaging Telescope

    NASA Astrophysics Data System (ADS)

    Waller, W. H.; Marsh, M.; Bohlin, R. C.; Cornett, R. H.; Dixon, W. V.; Isensee, J. E.; Murthy, J.; O'Connell, R. W.; Roberts, M. S.; Smith, A. M.; Stecher, T. P.

    1995-09-01

    Analysis of 489 wide-field images obtained by the Shuttle-borne Ultraviolet Imaging Telescope (UIT) has yielded positive detections of FUV and NUV backgrounds in both the orbital daytime and nighttime skies. The daytime backgrounds can be attributed to atmospheric dayglow line emission (in the FUV) and solar stray-light contamination (in the NUV). A few of the nighttime backgrounds (in both bands) appear to be affected by stray light from UV-bright stars just beyond the imaged fields of view. In both bands, the highest nighttime background levels are found in nebular fields at low galactic latitude. The diffuse backgrounds in these fields are probably associated with the adjoining nebulosity. Away from the galactic plane, the nighttime FUV backgrounds are confused by O I nightglow emission and possible photometric errors. The more tightly constrained NUV intensities correlate with those predicted from corresponding optical measurements of the Zodiacal light, yielding a NUV/Vis "color" of 0.5 +/- 0.2 for the Zodiacal light. After subtraction of the predicted Zodiacal component, the residual NUV intensities correlate with FIR measurements of the corresponding fields. Extrapolation to negligible FIR intensities yields an extragalactic NUV component of 300 photon units or less. This upper limit supports the low intensities that have been proposed in the debate over the strength and structure of the UV background (cf. Henry, ARA&A, 29,89, 1991; Bowyer, ARA&A, 29,59 1991). Such low values reinforce the characterization of the ultraviolet sky as the "window" of choice in the search for nearby low- surface-brightness galaxies and faint primeval galaxies much farther away.

  1. Investigation of ultraviolet interstellar extinction

    NASA Technical Reports Server (NTRS)

    Payne, C.; Haramundanis, K. L.

    1973-01-01

    Results concerning interstellar extinction in the ultraviolet are reported. These results were initially obtained by using data from main-sequence stars and were extended to include supergiants and emission stars. The principal finding of the analysis of ultraviolet extinction is not only that it is wavelength dependent, but that if changes with galactic longitude in the U3 passband (lambda sub eff = 1621 A); it does not change significantly in the U2 passband (lambda sub eff = 2308 A). Where data are available in the U4 passband (lambda sub eff = 1537 A), they confirm the rapid rise of extinction in the ultraviolet found by other investigators. However, in all cases, emission stars must be used with great caution. It is important to realize that while extinction continues to rise toward shorter wavelengths in the ultraviolet, including the shortest ultraviolet wavelengths measured (1100 A), it no longer plays an important role in the X-ray region (50 A).

  2. Just How Bright Is a Laser?

    ERIC Educational Resources Information Center

    Van Baak, David A.

    1995-01-01

    Attempts to quantify the subjective sensation of brightness of the spot projected by a helium-neon laser and compares this with conventional sources of light. Provides an exercise in using the blackbody radiation formulas. (JRH)

  3. Erratum: ``Infrared Surface Brightness Fluctuations of Magellanic Star Clusters'' (ApJ, 611, 270 [2004])

    NASA Astrophysics Data System (ADS)

    González, Rosa A.; Liu, Michael C.; Bruzual A., Gustavo

    2005-03-01

    Because their coordinates were mistyped, the Two Micron All-Sky Survey (2MASS) point source list for the Large Magellanic Cloud (LMC) cluster NGC 2002 (SWB class I), and the images and point source list for the Small Magellanic Cloud (SMC) cluster IC 1655 (SWB class II) were retrieved incorrectly. After rectifying the problem, the surface brightness fluctuation (SBF) magnitudes of the supercluster class SWB I are now ~ 0.15 mag brighter, and those of the SWB II are ~ 0.05 mag fainter. The colors of the two superclusters have also changed, albeit very slightly, and hence the fits of fluctuation color versus age for the supercluster set have also changed slightly. We list the new values of the fluctuation magnitudes, fluctuation colors, and fitting parameters in the tables here, which correspond to Tables 4 and 6 in the original paper.

  4. New Observations of Subarcsecond Photospheric Bright Points

    NASA Technical Reports Server (NTRS)

    Berger, T. E.; Schrijver, C. J.; Shine, R. A.; Tarbell, T. D.; Title, A. M.; Scharmer, G.

    1995-01-01

    We have used an interference filter centered at 4305 A within the bandhead of the CH radical (the 'G band') and real-time image selection at the Swedish Vacuum Solar Telescope on La Palma to produce very high contrast images of subarcsecond photospheric bright points at all locations on the solar disk. During the 6 day period of 1993 September 15-20 we observed active region NOAA 7581 from its appearance on the East limb to a near-disk-center position on September 20. A total of 1804 bright points were selected for analysis from the disk center image using feature extraction image processing techniques. The measured Full Width at Half Maximum (FWHM) distribution of the bright points in the image is lognormal with a modal value of 220 km (0 sec .30) and an average value of 250 km (0 sec .35). The smallest measured bright point diameter is 120 km (0 sec .17) and the largest is 600 km (O sec .69). Approximately 60% of the measured bright points are circular (eccentricity approx. 1.0), the average eccentricity is 1.5, and the maximum eccentricity corresponding to filigree in the image is 6.5. The peak contrast of the measured bright points is normally distributed. The contrast distribution variance is much greater than the measurement accuracy, indicating a large spread in intrinsic bright-point contrast. When referenced to an averaged 'quiet-Sun' area in the image, the modal contrast is 29% and the maximum value is 75%; when referenced to an average intergranular lane brightness in the image, the distribution has a modal value of 61% and a maximum of 119%. The bin-averaged contrast of G-band bright points is constant across the entire measured size range. The measured area of the bright points, corrected for pixelation and selection effects, covers about 1.8% of the total image area. Large pores and micropores occupy an additional 2% of the image area, implying a total area fraction of magnetic proxy features in the image of 3.8%. We discuss the implications of this

  5. New Observations of Subarcsecond Photospheric Bright Points

    NASA Technical Reports Server (NTRS)

    Berger, T. E.; Schrijver, C. J.; Shine, R. A.; Tarbell, T. D.; Title, A. M.; Scharmer, G.

    1995-01-01

    We have used an interference filter centered at 4305 A within the bandhead of the CH radical (the 'G band') and real-time image selection at the Swedish Vacuum Solar Telescope on La Palma to produce very high contrast images of subarcsecond photospheric bright points at all locations on the solar disk. During the 6 day period of 15-20 Sept. 1993 we observed active region NOAA 7581 from its appearance on the East limb to a near-disk-center position on 20 Sept. A total of 1804 bright points were selected for analysis from the disk center image using feature extraction image processing techniques. The measured FWHM distribution of the bright points in the image is lognormal with a modal value of 220 km (0.30 sec) and an average value of 250 km (0.35 sec). The smallest measured bright point diameter is 120 km (0.17 sec) and the largest is 600 km (O.69 sec). Approximately 60% of the measured bright points are circular (eccentricity approx. 1.0), the average eccentricity is 1.5, and the maximum eccentricity corresponding to filigree in the image is 6.5. The peak contrast of the measured bright points is normally distributed. The contrast distribution variance is much greater than the measurement accuracy, indicating a large spread in intrinsic bright-point contrast. When referenced to an averaged 'quiet-Sun' area in the image, the modal contrast is 29% and the maximum value is 75%; when referenced to an average intergranular lane brightness in the image, the distribution has a modal value of 61% and a maximum of 119%. The bin-averaged contrast of G-band bright points is constant across the entire measured size range. The measured area of the bright points, corrected for pixelation and selection effects, covers about 1.8% of the total image area. Large pores and micropores occupy an additional 2% of the image area, implying a total area fraction of magnetic proxy features in the image of 3.8%. We discuss the implications of this area fraction measurement in the context of

  6. Apparent brightness distribution of GRB host galaxies

    NASA Astrophysics Data System (ADS)

    Bagoly, Zsolt; Racz, Istvan; Gyorgy Balazs, Lajos; Toth, Viktor; Horvath, Istvan

    2015-08-01

    We studied the relationship between the Swift GRB data and the optical brightness of the host galaxy measured by the Keck telescope. We calculated the unbiased distribution of the host's optical brightness by making use the survival analysis. Based on the sample obtained from merging the Swift GRB table and the Keck optical data we studied also the dependence of this distribution on the GRB's data.

  7. Observations and diagnostics in high brightness beams

    NASA Astrophysics Data System (ADS)

    Cianchi, A.; Anania, M. P.; Bisesto, F.; Castellano, M.; Chiadroni, E.; Pompili, R.; Shpakov, V.

    2016-09-01

    The brightness is a figure of merit largely used in the light sources, like FEL (Free Electron Lasers), but it is also fundamental in several other applications, as for instance Compton backscattering sources, beam driven plasma accelerators and THz sources. Advanced diagnostics are essential tools in the development of high brightness beams. 6D electron beam diagnostics will be reviewed with emphasis on emittance measurement.

  8. The analogy between stereo depth and brightness.

    PubMed

    Brookes, A; Stevens, K A

    1989-01-01

    Apparent depth in stereograms exhibits various simultaneous-contrast and induction effects analogous to those reported in the luminance domain. This behavior suggests that stereo depth, like brightness, is reconstructed, ie recovered from higher-order spatial derivatives or differences of the original signal. The extent to which depth is analogous to brightness is examined. There are similarities in terms of contrast effects but dissimilarities in terms of the lateral inhibition effects traditionally attributed to underlying spatial-differentiation operators.

  9. Observations of the far ultraviolet airflow by the Ultraviolet Limb Imaging experiment on STS-39

    NASA Technical Reports Server (NTRS)

    Budzien, S. A.; Feldman, P. D.; Conway, R. R.

    1994-01-01

    The Ultraviolet Limb Imaging (UVLIM) experiment flew on STS-39 in the spring of 1991 to observe the Earth's thermospheric airglow and included a far ultraviolet (1080-1800 A) spectrometer. We present first results from this spectrometer, including a spectroscopic analysis at 6-A resolution of H, O, N, and N2 dayglow emissions and modeling of the observed limb-scan profiles of dayglow emissions. The observed N2 Lyman-Birge-Hopfield (LBH) emission reflects a vibrational population distribution in the a(1 Pi)(sub g) state that differs significantly from those predicted for direct electron excitation and excitation with cascade from the a('1 Sigma)(sub u)(-) and w(1 Delta)(sub u) states. The vibrational population distribution and LBH brightness suggest a total cascade rate 45% that of direct excitation, in contrast to laboratory measurements. For the first time, pronounced limb brightening is observed in both the N I lambda 1200 limb emission profiles, as expected for emissions excited by N2 dissociation which produces kinetically fast N fragments; however, optically thick components of these features are also observed. Preliminary modeling of the OI lambda 1356, HI lambda 1216, and OI lambda 1304 and OI lambda 1641 emissions agrees to within roughly 10% of the observed limb-scan profiles, but the models underestimate the N2 LBH profiles by a factor of 1.4-1.6, consistent with the inferred cascade effect. Other findings include: an OI lambda 1152/lambda 1356 intensity ratio that is inconsistent with the large cascade contribution to OI lambda 1356 from np 5P states required by laboratory and nightglow observations; nightglow observations of the tropical ultraviolet arcs exhibit a wide range of OI lambda 1356/lambda 1304 intensity ratios and illustrate the complicated observing geometry and radiative transfer effects that must be modeled; and we find a 3-sigma upper limit of 8.5 R to the total LBH vehicle glow emission.

  10. Mars ultraviolet simulation facility.

    PubMed

    Zill, L P; Mack, R; DeVincenzi, D L

    1979-12-01

    A facility was established for long-duration ultraviolet (UV) radiation exposure of natural and synthetic materials in order to test hypotheses concerning Martian soil chemistry observed by the Viking Mars landers. The system utilized a 2500 watt xenon lamp as the radiation source, with the beam passing through a heat-dissipating water filter before impinging upon an exposure chamber containing the samples to be irradiated. The chamber was designed to allow for continuous tumbling of the samples, maintenance of temperatures below 0 degrees C during exposure, and monitoring of beam intensity. The facility also provided for sample preparation under a variety of atmospheric conditions, in addition to the Mars nominal. As many as 33 sealed sample ampules have been irradiated in a single exposure. Over 100 samples have been irradiated for approximately 100 to 700 h. The facility has performed well in providing continuous UV irradiation of multiple samples for long periods of time under simulated Mars atmospheric and thermal conditions.

  11. Ultraviolet laser excitation source

    NASA Technical Reports Server (NTRS)

    Lee, J. H.; Mcfarland, D. R.; Hohl, F.

    1980-01-01

    A new intense ultraviolet light source has been developed from an array of hypocycloidal pinch (HCP) devices. The basic unit of the array is constructed with three disk electrodes and is capable of producing dense plasmas at temperatures up to 10,000,000 K. Very high input power levels to the array are possible without significantly shortening its useful life, in strong contrast with conventional xenon flashlamps. The new light source, when operated with Ar and Xe gas mixtures at high pressures (approximately 5 x 10 to the 4th Pa), produced a light output of over 100 MW in the near-UV spectral range and successfully pumped an iodine photodissociation laser at 1.315 microns. A xenon recombination laser at 2.027 microns was also pumped in the HCP array.

  12. Ultraviolet radiation effects

    NASA Technical Reports Server (NTRS)

    Slemp, Wayne S.

    1989-01-01

    Solar ultraviolet testing was not developed which will provide highly accelerated (20 to 50X) exposures that correlate to flight test data. Additional studies are required to develop an exposure methodology which will assure that accelerated testing can be used for qualification of materials and coatings for long duration space flight. Some conclusions are listed: Solar UV radiation is present in all orbital environments; Solar UV does not change in flux with orbital altitude; UV radiation can degrade most coatings and polymeric films; Laboratory UV simulation methodology is needed for accelerated testing to 20 UV solar constants; Simulation of extreme UV (below 200 nm) is needed to evaluate requirements for EUV in solar simulation.

  13. Carmencita, The CARMENES Input Catalogue of Bright, Nearby M Dwarfs

    NASA Astrophysics Data System (ADS)

    Caballero, J. A.; Cortés-Contreras, M.; Alonso-Floriano, F. J.; Montes, D.; Quirrenbach, A.; Amado, P. J.; Ribas, I.; Reiners, A.; Abellan, F. J.; Béjar, V. J. S.; Brinkmöller, M.; Czesla, S.; Dorda, R.; Gallardo, I.; González-Álvarez, E.; Hidalgo, D.; Holgado, G.; Jeffers, S. V.; Kim, M.; Klutsch, A.; Lamert, A.; Llamas, M.; López-Santiago, J.; Martínez-Rodríguez, H.; Morales, J. C.; Mundt, R.; Passegger, V. M.; Schöfer, P.; Seifert, W.; Zechmeister, M.

    2016-08-01

    CARMENES, the brand-new, Spanish-German, two-channel, ultra-stabilised, high-resolution spectrograph at the 3.5 m Calar Alto telescope, started its science survey on 01 Jan 2016. In one shot, it covers from 0.52 to 1.71 μm with resolution R = 94,600 (λ < 0.96 μm) and 80,400 (λ > 0.96 μm). During guaranteed time observations, CARMENES carries out the programme for which the instrument was designed: radial-velocity monitoring of bright, nearby, low-mass dwarfs with spectral types be- tween M0.0 V and M9.5 V. Carmencita is the "CARMEN(ES) Cool dwarf Information and daTa Archive", our input catalogue, from which we select the about 300 targets being observed during guaranteed time. Besides that, Carmencita is perhaps the most comprehensive database of bright, nearby M dwarfs ever built, as well as a useful tool for forthcoming exo-planet hunters: ESPRESSO, HPF, IRD, SPIRou, TESS or even PLATO. Carmencita contains dozens of parameters measured by us or compiled from the literature for about 2,200 M dwarfs in the solar neighbourhood brighter than J = 11.5 mag: accurate coordinates, spectral types, photometry from ultraviolet to mid-infrared, parallaxes and spectro-photometric distances, rotational and radial velocities, Hα pseudo-equivalent widths, X-ray count rates and hardness ratios, close and wide multiplicity data, proper motions, Galactocentric space velocities, metallicities, full references, homogeneously derived astrophysical parameters, and much more. In my talk at Cool Stars 19, I explained how we build Carmencita standing on the shoulders of giants and observing with 2-m class telescopes, and produce a dozen MSc theses and several PhD theses in the process (http://carmenes.caha.es).

  14. Differential Rotation via Tracking of Coronal Bright Points.

    NASA Astrophysics Data System (ADS)

    McAteer, James; Boucheron, Laura E.; Osorno, Marcy

    2016-05-01

    The accurate computation of solar differential rotation is important both as a constraint for, and evidence towards, support of models of the solar dynamo. As such, the use of Xray and Extreme Ultraviolet bright points to elucidate differential rotation has been studied in recent years. In this work, we propose the automated detection and tracking of coronal bright points (CBPs) in a large set of SDO data for re-evaluation of solar differential rotation and comparison to other results. The big data aspects, and high cadence, of SDO data mitigate a few issues common to detection and tracking of objects in image sequences and allow us to focus on the use of CBPs to determine differential rotation. The high cadence of the data allows to disambiguate individual CBPs between subsequent images by allowing for significant spatial overlap, i.e., by the fact that the CBPs will rotate a short distance relative to their size. The significant spatial overlap minimizes the effects of incorrectly detected CBPs by reducing the occurrence of outlier values of differential rotation. The big data aspects of the data allows to be more conservative in our detection of CBPs (i.e., to err on the side of missing CBPs rather than detecting extraneous CBPs) while still maintaining statistically larger populations over which to study characteristics. The ability to compute solar differential rotation through the automated detection and tracking of a large population of CBPs will allow for further analyses such as the N-S asymmetry of differential rotation, variation of differential rotation over the solar cycle, and a detailed study of the magnetic flux underlying the CBPs.

  15. Bright high-order harmonic generation with controllable polarization from a relativistic plasma mirror.

    PubMed

    Chen, Zi-Yu; Pukhov, Alexander

    2016-08-17

    Ultrafast extreme ultraviolet (XUV) sources with a controllable polarization state are powerful tools for investigating the structural and electronic as well as the magnetic properties of materials. However, such light sources are still limited to only a few free-electron laser facilities and, very recently, to high-order harmonic generation from noble gases. Here we propose and numerically demonstrate a laser-plasma scheme to generate bright XUV pulses with fully controlled polarization. In this scheme, an elliptically polarized laser pulse is obliquely incident on a plasma surface, and the reflected radiation contains pulse trains and isolated circularly or highly elliptically polarized attosecond XUV pulses. The harmonic polarization state is fully controlled by the laser-plasma parameters. The mechanism can be explained within the relativistically oscillating mirror model. This scheme opens a practical and promising route to generate bright attosecond XUV pulses with desirable ellipticities in a straightforward and efficient way for a number of applications.

  16. Bright high-order harmonic generation with controllable polarization from a relativistic plasma mirror

    PubMed Central

    Chen, Zi-Yu; Pukhov, Alexander

    2016-01-01

    Ultrafast extreme ultraviolet (XUV) sources with a controllable polarization state are powerful tools for investigating the structural and electronic as well as the magnetic properties of materials. However, such light sources are still limited to only a few free-electron laser facilities and, very recently, to high-order harmonic generation from noble gases. Here we propose and numerically demonstrate a laser–plasma scheme to generate bright XUV pulses with fully controlled polarization. In this scheme, an elliptically polarized laser pulse is obliquely incident on a plasma surface, and the reflected radiation contains pulse trains and isolated circularly or highly elliptically polarized attosecond XUV pulses. The harmonic polarization state is fully controlled by the laser–plasma parameters. The mechanism can be explained within the relativistically oscillating mirror model. This scheme opens a practical and promising route to generate bright attosecond XUV pulses with desirable ellipticities in a straightforward and efficient way for a number of applications. PMID:27531047

  17. Generation of Bright Phase-matched Circularly-polarized Extreme Ultraviolet High Harmonics

    DTIC Science & Technology

    2014-12-08

    element-specific imaging and spectroscopy of multiple elements simultaneously in magnetic and other chiral media with very high spatial and temporal...investigating chirality -sensitive light–matter inter- actions. It enables studies of chiral molecules using photoelectron circular dichroism1, ultrafast...of the significantly suppressed 3m harmonics is also chiral , with the same helicity as the 3m + 1 harmonics. This observation agrees with the

  18. Energy-exchange collisions of dark-bright-bright vector solitons.

    PubMed

    Radhakrishnan, R; Manikandan, N; Aravinthan, K

    2015-12-01

    We find a dark component guiding the practically interesting bright-bright vector one-soliton to two different parametric domains giving rise to different physical situations by constructing a more general form of three-component dark-bright-bright mixed vector one-soliton solution of the generalized Manakov model with nine free real parameters. Moreover our main investigation of the collision dynamics of such mixed vector solitons by constructing the multisoliton solution of the generalized Manakov model with the help of Hirota technique reveals that the dark-bright-bright vector two-soliton supports energy-exchange collision dynamics. In particular the dark component preserves its initial form and the energy-exchange collision property of the bright-bright vector two-soliton solution of the Manakov model during collision. In addition the interactions between bound state dark-bright-bright vector solitons reveal oscillations in their amplitudes. A similar kind of breathing effect was also experimentally observed in the Bose-Einstein condensates. Some possible ways are theoretically suggested not only to control this breathing effect but also to manage the beating, bouncing, jumping, and attraction effects in the collision dynamics of dark-bright-bright vector solitons. The role of multiple free parameters in our solution is examined to define polarization vector, envelope speed, envelope width, envelope amplitude, grayness, and complex modulation of our solution. It is interesting to note that the polarization vector of our mixed vector one-soliton evolves in sphere or hyperboloid depending upon the initial parametric choices.

  19. Ultraviolet diversity of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Foley, Ryan J.; Pan, Yen-Chen; Brown, P.; Filippenko, A. V.; Fox, O. D.; Hillebrandt, W.; Kirshner, R. P.; Marion, G. H.; Milne, P. A.; Parrent, J. T.; Pignata, G.; Stritzinger, M. D.

    2016-09-01

    Ultraviolet (UV) observations of Type Ia supernovae (SNe Ia) probe the outermost layers of the explosion, and UV spectra of SNe Ia are expected to be extremely sensitive to differences in progenitor composition and the details of the explosion. Here, we present the first study of a sample of high signal-to-noise ratio SN Ia spectra that extend blueward of 2900 Å. We focus on spectra taken within 5 d of maximum brightness. Our sample of 10 SNe Ia spans, the majority of the parameter space of SN Ia optical diversity. We find that SNe Ia have significantly more diversity in the UV than in the optical, with the spectral variance continuing to increase with decreasing wavelengths until at least 1800 Å (the limit of our data). The majority of the UV variance correlates with optical light-curve shape, while there are no obvious and unique correlations between spectral shape and either ejecta velocity or host-galaxy morphology. Using light-curve shape as the primary variable, we create a UV spectral model for SNe Ia at peak brightness. With the model, we can examine how individual SNe vary relative to expectations based on only their light-curve shape. Doing this, we confirm an excess of flux for SN 2011fe at short wavelengths, consistent with its progenitor having a subsolar metallicity. While most other SNe Ia do not show large deviations from the model, ASASSN-14lp has a deficit of flux at short wavelengths, suggesting that its progenitor was relatively metal rich.

  20. Skylab experiment SO73: Gegenschein/zodiacal light. [electrophotometry of surface brightness and polarization

    NASA Technical Reports Server (NTRS)

    Weinberg, J. L.

    1976-01-01

    A 10 color photoelectric polarimeter was used to measure the surface brightness and polarization associated with zodiacal light, background starlight, and spacecraft corona during each of the Skylab missions. Fixed position and sky scanning observations were obtained during Skylab missions SL-2 and SL-3 at 10 wavelenghts between 4000A and 8200A. Initial results from the fixed-position data are presented on the spacecraft corona and on the polarized brightness of the zodiacal light. Included among the fixed position regions that were observed are the north celestial pole, south ecliptic pole, two regions near the north galactic pole, and 90 deg from the sun in the ecliptic. The polarized brightness of the zodiacal light was found to have the color of the sun at each of these positions. Because previous observations found the total brightness to have the color of the sun from the near ultraviolet out to 2.4 micrometers, the degree of polarization of the zodiacal light is independent of wavelength from 4000A to 8200A.

  1. Microwave Brightness Temperatures of Tilted Convective Systems

    NASA Technical Reports Server (NTRS)

    Hong, Ye; Haferman, Jeffrey L.; Olson, William S.; Kummerow, Christian D.

    1998-01-01

    Aircraft and ground-based radar data from the Tropical Ocean and Global Atmosphere Coupled-Ocean Atmosphere Response Experiment (TOGA COARE) show that convective systems are not always vertical. Instead, many are tilted from vertical. Satellite passive microwave radiometers observe the atmosphere at a viewing angle. For example, the Special Sensor Microwave/Imager (SSM/I) on Defense Meteorological Satellite Program (DMSP) satellites and the Tropical Rainfall Measurement Mission (TRMM) Microwave Imager (TMI) on the TRMM satellite have an incident angle of about 50deg. Thus, the brightness temperature measured from one direction of tilt may be different than that viewed from the opposite direction due to the different optical depth. This paper presents the investigation of passive microwave brightness temperatures of tilted convective systems. To account for the effect of tilt, a 3-D backward Monte Carlo radiative transfer model has been applied to a simple tilted cloud model and a dynamically evolving cloud model to derive the brightness temperature. The radiative transfer results indicate that brightness temperature varies when the viewing angle changes because of the different optical depth. The tilt increases the displacements between high 19 GHz brightness temperature (Tb(sub 19)) due to liquid emission from lower level of cloud and the low 85 GHz brightness temperature (Tb(sub 85)) due to ice scattering from upper level of cloud. As the resolution degrades, the difference of brightness temperature due to the change of viewing angle decreases dramatically. The dislocation between Tb(sub 19) and Tb(sub 85), however, remains prominent.

  2. ULTRAVIOLET PROTECTIVE COMPOUNDS AS A RESPONSE TO ULTRAVIOLET RADIATION EXPOSURE

    EPA Science Inventory

    Life on Earth has evolved adaptations to many environmental stresses over the epochs. One consistent stress has been exposure to ultraviolet radiation. In response to UVR organisms have adapted myriad responses; behavioral, morphological and physiological. Behaviorally, some orga...

  3. Rhodium nanoparticles for ultraviolet plasmonics.

    PubMed

    Watson, Anne M; Zhang, Xiao; Alcaraz de la Osa, Rodrigo; Marcos Sanz, Juan; González, Francisco; Moreno, Fernando; Finkelstein, Gleb; Liu, Jie; Everitt, Henry O

    2015-02-11

    The nonoxidizing catalytic noble metal rhodium is introduced for ultraviolet plasmonics. Planar tripods of 8 nm Rh nanoparticles, synthesized by a modified polyol reduction method, have a calculated local surface plasmon resonance near 330 nm. By attaching p-aminothiophenol, local field-enhanced Raman spectra and accelerated photodamage were observed under near-resonant ultraviolet illumination, while charge transfer simultaneously increased fluorescence for up to 13 min. The combined local field enhancement and charge transfer demonstrate essential steps toward plasmonically enhanced ultraviolet photocatalysis.

  4. Ultraviolet radiation induced discharge laser

    DOEpatents

    Gilson, Verle A.; Schriever, Richard L.; Shearer, James W.

    1978-01-01

    An ultraviolet radiation source associated with a suitable cathode-anode electrode structure, disposed in a gas-filled cavity of a high pressure pulsed laser, such as a transverse electric atmosphere (TEA) laser, to achieve free electron production in the gas by photoelectric interaction between ultraviolet radiation and the cathode prior to the gas-exciting cathode-to-anode electrical discharge, thereby providing volume ionization of the gas. The ultraviolet radiation is produced by a light source or by a spark discharge.

  5. AN ALL-SKY CATALOG OF BRIGHT M DWARFS

    SciTech Connect

    Lepine, Sebastien; Gaidos, Eric

    2011-10-15

    We present an all-sky catalog of M dwarf stars with apparent infrared magnitude J < 10. The 8889 stars are selected from the ongoing SUPERBLINK survey of stars with proper motion {mu} > 40 mas yr{sup -1}, supplemented on the bright end with the Tycho-2 catalog. Completeness tests which account for kinematic (proper motion) bias suggest that our catalog represents {approx}75% of the estimated {approx}11, 900 M dwarfs with J < 10 expected to populate the entire sky. Our catalog is, however, significantly more complete for the northern sky ({approx}90%) than it is for the south ({approx}60%). Stars are identified as cool, red M dwarfs from a combination of optical and infrared color cuts, and are distinguished from background M giants and highly reddened stars using either existing parallax measurements or, if such measurements are lacking, using their location in an optical-to-infrared reduced proper motion diagram. These bright M dwarfs are all prime targets for exoplanet surveys using the Doppler radial velocity or transit methods; the combination of low-mass and bright apparent magnitude should make possible the detection of Earth-size planets on short-period orbits using currently available techniques. Parallax measurements, when available, and photometric distance estimates are provided for all stars, and these place most systems within 60 pc of the Sun. Spectral type estimated from V - J color shows that most of the stars range from K7 to M4, with only a few late M dwarfs, all within 20 pc. Proximity to the Sun also makes these stars good targets for high-resolution exoplanet imaging searches, especially if younger objects can be identified on the basis of X-ray or UV excess. For that purpose, we include X-ray flux from ROSAT and FUV/NUV ultraviolet magnitudes from GALEX for all stars for which a counterpart can be identified in those catalogs. Additional photometric data include optical magnitudes from Digitized Sky Survey plates and infrared magnitudes from

  6. Research in extreme ultraviolet and far ultraviolet astronomy

    NASA Technical Reports Server (NTRS)

    Bowyer, C. S.

    1985-01-01

    The Far Ultraviolet imager (FUVI) was flown on the Aries class sounding rocket 24.015, producing outstanding results. The diffuse extreme ultraviolet (EUV) background spectrometer which is under construction is described. It will be launched on the Black Brant sounding rocket flight number 27.086. Ongoing design studies of a high resolution spectrometer are discussed. This instrument incorporates a one meter normal incidence mirror and will be suitable for an advanced Spartan mission.

  7. Solar Cycle 23 in Coronal Bright Points

    NASA Astrophysics Data System (ADS)

    Sattarov, Isroil; Pevtsov, Alexei A.; Karachik, Nina V.; Sherdanov, Chori T.; Tillaboev, A. M.

    2010-04-01

    We describe an automatic routine to identify coronal bright points (CBPs) and apply this routine to SOHO/EIT observations taken in the 195 Å spectral range during solar cycle 23. We examine the total number of CBPs and its change in the course of this solar cycle. Unlike some other recent studies, we do find a modest ≈30% decrease in the number of CBPs associated with maximum of sunspot activity. Using the maximum brightness of CBPs as a criterion, we separate them on two categories: dim CBPs, associated with areas of a quiet Sun, and bright CBPs, associated with an active Sun. We find that the number of dim coronal bright points decreases at the maximum of sunspot cycle, while the number of bright CBPs increases. The latitudinal distributions suggest that dim CBPs are distributed uniformly over the solar disk. Active Sun CBPs exhibit a well-defined two-hump latitudinal profile suggestive of enhanced production of this type of CBPs in sunspot activity belts. Finally, we investigate the relative role of two mechanisms in cycle variations of CBP number, and conclude that a change in fraction of solar surface occupied by the quiet Sun’s magnetic field is the primary cause, with the visibility effect playing a secondary role.

  8. 21 CFR 872.6350 - Ultraviolet detector.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ultraviolet detector. 872.6350 Section 872.6350...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6350 Ultraviolet detector. (a) Identification. An ultraviolet detector is a device intended to provide a source of ultraviolet light which is...

  9. 21 CFR 872.6350 - Ultraviolet detector.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ultraviolet detector. 872.6350 Section 872.6350...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6350 Ultraviolet detector. (a) Identification. An ultraviolet detector is a device intended to provide a source of ultraviolet light which is...

  10. 21 CFR 872.6350 - Ultraviolet detector.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ultraviolet detector. 872.6350 Section 872.6350...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6350 Ultraviolet detector. (a) Identification. An ultraviolet detector is a device intended to provide a source of ultraviolet light which is...

  11. 21 CFR 872.6350 - Ultraviolet detector.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ultraviolet detector. 872.6350 Section 872.6350...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6350 Ultraviolet detector. (a) Identification. An ultraviolet detector is a device intended to provide a source of ultraviolet light which is...

  12. 21 CFR 872.6350 - Ultraviolet detector.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ultraviolet detector. 872.6350 Section 872.6350...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6350 Ultraviolet detector. (a) Identification. An ultraviolet detector is a device intended to provide a source of ultraviolet light which is...

  13. Ultraviolet light curves of galactic and extra-galactic classical CNO novae: PW Vul, OS, and LMC 1988 no. 1 and no. 2

    NASA Technical Reports Server (NTRS)

    Austin, S.; Starrfield, Sumner G.; Saizar, P.; Shore, Steven N.; Sonneborn, George

    1990-01-01

    In order to determine the comparative energy budgets of novae in outburst, the ultraviolet light curves for a number of novae are determined. The low dispersion IUE (International Ultraviolet Explorer) spectra of PW Vul 1984, OS And 1986, LMC 1988 number 1 and number 2 and obtained values for the integrated energy emitted in the wavelength interval from 1200 to 3400 A, not including the geocoronal Lyman-alpha emission line are re-examined. The light curves show that the brightness of the nova declines much more slowly in the ultraviolet than the optical, that the maximum brightness of the nova occurs much later in the ultraviolet than in the optical, and the peak luminosity is super Eddington for LMC 1988 number 2.

  14. GMRT H I study of giant low surface brightness galaxies

    NASA Astrophysics Data System (ADS)

    Mishra, A.; Kantharia, N. G.; Das, M.; Omar, A.; Srivastava, D. C.

    2017-01-01

    We present H I observations of four giant low surface brightness (GLSB) galaxies UGC 1378, UGC 1922, UGC 4422 and UM 163 using the Giant Meterwave Radio Telescope. We include H I results on UGC 2936, UGC 6614 and Malin 2 from literature. H I is detected from all the galaxies and the extent is roughly twice the optical size; in UM 163, H I is detected along a broken disc encircling the optical galaxy. We combine our results with those in literature to further understand these systems. The main results are the following: (1) the peak H I surface densities in GLSB galaxies are several times 1021 cm-2. The H I mass is between 0.3 and 4 × 1010 M⊙; dynamical mass ranges from a few times 1011 M⊙ to a few times 1012 M⊙. (2) The rotation curves of GLSB galaxies are flat to the outermost measured point with rotation velocities of the seven GLSB galaxies being between 225 and 432 km s-1. (3) Recent star formation traced by near-ultraviolet emission in five GLSB galaxies in our sample appears to be located in rings around the galaxy centre. We suggest that this could be due to a stochastic burst of star formation at one location in the galaxy being propagated along a ring over a rotation period. (4) The H I is correlated with recent star formation in five of the seven GLSB galaxies.

  15. QUIET-SUN NETWORK BRIGHT POINT PHENOMENA WITH SIGMOIDAL SIGNATURES

    SciTech Connect

    Chesny, D. L.; Oluseyi, H. M.; Orange, N. B.; Champey, P. R.

    2015-12-01

    Ubiquitous solar atmospheric coronal and transition region bright points (BPs) are compact features overlying strong concentrations of magnetic flux. Here, we utilize high-cadence observations from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory to provide the first observations of extreme ultraviolet quiet-Sun (QS) network BP activity associated with sigmoidal structuring. To our knowledge, this previously unresolved fine structure has never been associated with such small-scale QS events. This QS event precedes a bi-directional jet in a compact, low-energy, and low-temperature environment, where evidence is found in support of the typical fan-spine magnetic field topology. As in active regions and micro-sigmoids, the sigmoidal arcade is likely formed via tether-cutting reconnection and precedes peak intensity enhancements and eruptive activity. Our QS BP sigmoid provides a new class of small-scale structuring exhibiting self-organized criticality that highlights a multi-scaled self-similarity between large-scale, high-temperature coronal fields and the small-scale, lower-temperature QS network. Finally, our QS BP sigmoid elevates arguments for coronal heating contributions from cooler atmospheric layers, as this class of structure may provide evidence favoring mass, energy, and helicity injections into the heliosphere.

  16. Chandra's Darkest Bright Star: not so Dark after All?

    NASA Astrophysics Data System (ADS)

    Ayres, Thomas R.

    2008-11-01

    The Chandra High Resolution camera (HRC) has obtained numerous short exposures of the ultraviolet (UV)-bright star Vega (α Lyrae; HD 172167: A0 V), to calibrate the response of the detector to out-of-band (non-X-ray) radiation. A new analysis uncovered a stronger "blue leak" in the imaging section (HRC-I) than reported in an earlier study of Vega based on a subset of the pointings. The higher count rate—a factor of nearly 2 above prelaunch estimates—raised the possibility that genuine coronal X-rays might lurk among the out-of-band events. Exploiting the broader point-spread function of the UV leak compared with soft X-rays identified an excess of counts centered on the target, technically at 3σ significance. A number of uncertainties, however, prevent a clear declaration of a Vegan corona. A more secure result would be within reach of a deep uninterrupted HRC-I pointing.

  17. Quiet-Sun Network Bright Point Phenomena with Sigmoidal Signatures

    NASA Astrophysics Data System (ADS)

    Chesny, D. L.; Oluseyi, H. M.; Orange, N. B.; Champey, P. R.

    2015-12-01

    Ubiquitous solar atmospheric coronal and transition region bright points (BPs) are compact features overlying strong concentrations of magnetic flux. Here, we utilize high-cadence observations from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory to provide the first observations of extreme ultraviolet quiet-Sun (QS) network BP activity associated with sigmoidal structuring. To our knowledge, this previously unresolved fine structure has never been associated with such small-scale QS events. This QS event precedes a bi-directional jet in a compact, low-energy, and low-temperature environment, where evidence is found in support of the typical fan-spine magnetic field topology. As in active regions and micro-sigmoids, the sigmoidal arcade is likely formed via tether-cutting reconnection and precedes peak intensity enhancements and eruptive activity. Our QS BP sigmoid provides a new class of small-scale structuring exhibiting self-organized criticality that highlights a multi-scaled self-similarity between large-scale, high-temperature coronal fields and the small-scale, lower-temperature QS network. Finally, our QS BP sigmoid elevates arguments for coronal heating contributions from cooler atmospheric layers, as this class of structure may provide evidence favoring mass, energy, and helicity injections into the heliosphere.

  18. Ultraviolet fluorescence monitor

    SciTech Connect

    Hargis, P.J. Jr.; Preppernau, B.L.; Aragon, B.P.

    1997-05-01

    A multispectral ultraviolet (UV) fluorescence imaging fluorometer and a pulsed molecular beam laser fluorometer were developed to detect volatile organic compounds of interest in environmental monitoring and drug interdiction applications. The UV fluorescence imaging fluorometer is a relatively simple instrument which uses multiple excitation wavelengths to measure the excitation/emission matrix for irradiated samples. Detection limits in the high part-per-million to low part-per-million range were measured for a number of volatile organic vapors in the atmosphere. Detection limits in the low part-per-million range were obtained using cryogenic cooling to pre-concentrate unknown samples before introducing them into the imaging fluorometer. A multivariate analysis algorithm was developed to analyze the excitation/emission matrix and used to determine the relative concentrations of species in computer synthesized mixtures containing up to five organic compounds. Analysis results demonstrated the utility of multispectral UV fluorescence in analytical measurements. A transportable UV fluorescence imaging fluorometer was used in two field tests. Field test results demonstrated that detection limits in the part-per-billion range were needed to reliably identify volatile organic compounds in realistic field test measurements. The molecular beam laser fluorometer, a more complex instrument with detection limits in the part-per-billion to part-per-trillion range, was therefore developed to satisfy detection sensitivity requirements for field test measurements. High-resolution spectroscopic measurements made with the molecular beam laser fluorometer demonstrated its utility in identifying volatile organic compounds in the atmosphere.

  19. Extreme ultraviolet lithography machine

    DOEpatents

    Tichenor, Daniel A.; Kubiak, Glenn D.; Haney, Steven J.; Sweeney, Donald W.

    2000-01-01

    An extreme ultraviolet lithography (EUVL) machine or system for producing integrated circuit (IC) components, such as transistors, formed on a substrate. The EUVL machine utilizes a laser plasma point source directed via an optical arrangement onto a mask or reticle which is reflected by a multiple mirror system onto the substrate or target. The EUVL machine operates in the 10-14 nm wavelength soft x-ray photon. Basically the EUV machine includes an evacuated source chamber, an evacuated main or project chamber interconnected by a transport tube arrangement, wherein a laser beam is directed into a plasma generator which produces an illumination beam which is directed by optics from the source chamber through the connecting tube, into the projection chamber, and onto the reticle or mask, from which a patterned beam is reflected by optics in a projection optics (PO) box mounted in the main or projection chamber onto the substrate. In one embodiment of a EUVL machine, nine optical components are utilized, with four of the optical components located in the PO box. The main or projection chamber includes vibration isolators for the PO box and a vibration isolator mounting for the substrate, with the main or projection chamber being mounted on a support structure and being isolated.

  20. Ultraviolet studies of Cepheids

    NASA Technical Reports Server (NTRS)

    Boehm-Vitense, Erika

    1992-01-01

    We discuss whether with new evolutionary tracks we still have a problem fitting the Cepheids and their evolved companions on the appropriate evolutionary tracks. We find that with the Bertelli et al. tracks with convective overshoot by one pressure scale height the problem is essentially removed, though somewhat more mixing would give a better fit. By using the results of recent nonlinear hydrodynamic calculations, we find that we also have no problem matching the observed pulsation periods of the Cepheids with those expected from their new evolutionary masses, provided that Cepheids with periods less than 9 days are overtone pulsators. We investigate possible mass loss of Cepheids from UV studies of the companion spectrum of S Mus and from the ultraviolet spectra of the long period Cepheid l Carinae. For S Mus with a period of 9.6 days we derive an upper limit for the mass loss of M less than 10(exp -9) solar mass, if a standard velocity law is assumed for the wind. For l Carinae with a period of 35.5 days we find a probable mass loss of M is approximately 10(exp -5+/-2) solar mass.

  1. Light, Including Ultraviolet

    PubMed Central

    Maverakis, Emanual; Miyamura, Yoshinori; Bowen, Michael P.; Correa, Genevieve; Ono, Yoko; Goodarzi, Heidi

    2009-01-01

    Ultraviolet (UV) light is intricately linked to the functional status of the cutaneous immune system. In susceptible individuals, UV radiation can ignite pathogenic inflammatory pathways leading to allergy or autoimmunity. In others, this same UV radiation can be used as a phototherapy to suppress pathogenic cutaneous immune responses. These vastly different properties are a direct result of UV light’s ability to ionize molecules in the skin and thereby chemically alter them. Sometimes these UV-induced chemical reactions are essential, the formation of pre-vitamin D3 from 7-dehydrocholesterol, for example. In other instances they can be potentially detrimental. UV radiation can ionize a cell’s DNA causing adjacent pyrimidine bases to chemically bond to each other. To prevent malignant transformation, a cell may respond to this UV-induced DNA damage by undergoing apoptosis. Although this pathway prevents skin cancer it also has the potential of inducing or exacerbating autoreactive immune responses by exposing the cell’s nuclear antigens. Ultaviolet-induced chemical reactions can activate the immune system by a variety of other mechanisms as well. In response to UV irradiation keratinocytes secrete cytokines and chemokines, which activate and recruit leukocytes to the skin. In some individuals UV-induced chemical reactions can synthesize novel antigens resulting in a photoallergy. Alternatively, photosensitizing molecules can damage cells by initiating sunburn-like phototoxic reactions. Herein we review all types of UV-induced skin reactions, especially those involving the immune system. PMID:20018479

  2. Higgs ultraviolet softening

    NASA Astrophysics Data System (ADS)

    Brivio, I.; Éboli, O. J. P.; Gavela, M. B.; Gonzalez-García, M. C.; Merlo, L.; Rigolin, S.

    2014-12-01

    We analyze the leading effective operators which induce a quartic momentum dependence in the Higgs propagator, for a linear and for a non-linear realization of electroweak symmetry breaking. Their specific study is relevant for the understanding of the ultraviolet sensitivity to new physics. Two methods of analysis are applied, trading the Lagrangian coupling by: i) a "ghost" scalar, after the Lee-Wick procedure; ii) other effective operators via the equations of motion. The two paths are shown to lead to the same effective Lagrangian at first order in the operator coefficients. It follows a modification of the Higgs potential and of the fermionic couplings in the linear realization, while in the non-linear one anomalous quartic gauge couplings, Higgs-gauge couplings and gauge-fermion interactions are induced in addition. Finally, all LHC Higgs and other data presently available are used to constrain the operator coefficients; the future impact of pp → 4 leptons data via off-shell Higgs exchange and of vector boson fusion data is considered as well. For completeness, a summary of pure-gauge and gauge-Higgs signals exclusive to non-linear dynamics at leading-order is included.

  3. Ultraviolet radiation and cyanobacteria.

    PubMed

    Rastogi, Rajesh Prasad; Sinha, Rajeshwar P; Moh, Sang Hyun; Lee, Taek Kyun; Kottuparambil, Sreejith; Kim, Youn-Jung; Rhee, Jae-Sung; Choi, Eun-Mi; Brown, Murray T; Häder, Donat-Peter; Han, Taejun

    2014-12-01

    Cyanobacteria are the dominant photosynthetic prokaryotes from an ecological, economical, or evolutionary perspective, and depend on solar energy to conduct their normal life processes. However, the marked increase in solar ultraviolet radiation (UVR) caused by the continuous depletion of the stratospheric ozone shield has fueled serious concerns about the ecological consequences for all living organisms, including cyanobacteria. UV-B radiation can damage cellular DNA and several physiological and biochemical processes in cyanobacterial cells, either directly, through its interaction with certain biomolecules that absorb in the UV range, or indirectly, with the oxidative stress exerted by reactive oxygen species. However, cyanobacteria have a long history of survival on Earth, and they predate the existence of the present ozone shield. To withstand the detrimental effects of solar UVR, these prokaryotes have evolved several lines of defense and various tolerance mechanisms, including avoidance, antioxidant production, DNA repair, protein resynthesis, programmed cell death, and the synthesis of UV-absorbing/screening compounds, such as mycosporine-like amino acids (MAAs) and scytonemin. This study critically reviews the current information on the effects of UVR on several physiological and biochemical processes of cyanobacteria and the various tolerance mechanisms they have developed. Genomic insights into the biosynthesis of MAAs and scytonemin and recent advances in our understanding of the roles of exopolysaccharides and heat shock proteins in photoprotection are also discussed.

  4. Ultraviolet Communication for Medical Applications

    DTIC Science & Technology

    2015-06-01

    AWARD NUMBER: W81XWH-12-C-0043 TITLE: Ultraviolet Communication for Medical Applications PRINCIPAL INVESTIGATOR Jeff Guy Directed Energy , Inc...SUPPLEMENTARY NOTES Report contains color. 14. ABSTRACT Under this Phase II SBIR effort, Directed Energy Inc.’s (DEI) proprietary ultraviolet (UV...non-line-of-sight (NLOS) optical communication data links operating in the solar blind region (200–280 nm). The intended application is covert

  5. Plasmonic EIT-like switching in bright-dark-bright plasmon resonators.

    PubMed

    Chen, Junxue; Wang, Pei; Chen, Chuncong; Lu, Yonghua; Ming, Hai; Zhan, Qiwen

    2011-03-28

    In this paper we report the study of the electromagnetically induced transparency (EIT)-like transmission in the bright-dark-bright plasmon resonators. It is demonstrated that the interferences between the dark plasmons excited by two bright plasmon resonators can be controlled by the incident light polarization. The constructive interference strengthens the coupling between the bright and dark resonators, leading to a more prominent EIT-like transparency window of the metamaterial. In contrary, destructive interference suppresses the coupling between the bright and dark resonators, destroying the interference pathway that forms the EIT-like transmission. Based on this observation, the plasmonic EIT switching can be realized by changing the polarization of incident light. This phenomenon may find applications in optical switching and plasmon-based information processing.

  6. A selective deficit in the appreciation and recognition of brightness: brightness agnosia?

    PubMed

    Nijboer, Tanja C W; Nys, Gudrun M S; van der Smagt, Maarten J; de Haan, Edward H F

    2009-01-01

    We report a patient with extensive brain damage in the right hemisphere who demonstrated a severe impairment in the appreciation of brightness. Acuity, contrast sensitivity as well as luminance discrimination were normal, suggesting her brightness impairment is not a mere consequence of low-level sensory impairments. The patient was not able to indicate the darker or the lighter of two grey squares, even though she was able to see that they differed. In addition, she could not indicate whether the lights in a room were switched on or off, nor was she able to differentiate between normal greyscale images and inverted greyscale images. As the patient recognised objects, colours, and shapes correctly, the impairment is specific for brightness. As low-level, sensory processing is normal, this specific deficit in the recognition and appreciation of brightness appears to be of a higher, cognitive level, the level of semantic knowledge. This appears to be the first report of 'brightness agnosia'.

  7. Laser-induced two-photon blackbody radiation in the vacuum ultraviolet

    NASA Technical Reports Server (NTRS)

    Zych, L. J.; Young, J. F.; Harris, S. E.; Lukasik, J.

    1978-01-01

    Experimental measurements of a new type of vacuum-ultraviolet radiation source are reported. It is shown that the maximum source brightness, within its narrow linewidth, is that of a blackbody at the temperature of a metastable storage level. The laser-induced emission at 569 A from a He glow discharge corresponded to a metastable temperature of 22,700 K and was over 100 times brighter than the 584-A He resonance line.

  8. The diffuse far-ultraviolet cosmic background radiation field observed from the Space Shuttle

    NASA Technical Reports Server (NTRS)

    Murthy, J.; Henry, R. C.; Feldman, P. D.; Tennyson, P. D.

    1989-01-01

    The paper presents 17-A resolution spectra of the diffuse far-ultraviolet (1200-1700 A) cosmic background in eight regions of the sky obtained from the Johns Hopkins University UVX experiment aboard the Space Shuttle Columbia (STS-61C) in January 1986. A spectrally flat background is found with brightnesses between 100 and 700 + or - 200 photons/sq cm s sr A, with some evidence for spatial variations, but not for the high-intensity regions found by other experiments.

  9. Brightness Discrimination in Budgerigars (Melopsittacus undulatus)

    PubMed Central

    Lind, Olle; Karlsson, Sandra; Kelber, Almut

    2013-01-01

    Birds have excellent spatial acuity and colour vision compared to other vertebrates while spatial contrast sensitivity is relatively poor for unknown reasons. Contrast sensitivity describes the detection of gratings of varying spatial frequency. It is unclear whether bird brightness discrimination between large uniform fields is poor as well. Here we show that budgerigars (Melopsittacus undulatus) need a Michelson contrast of 0.09 to discriminate between large spatially separated achromatic fields in bright light conditions. This is similar to the peak contrast sensitivity of 10.2 (0.098 Michelson contrast) for achromatic grating stimuli established in earlier studies. The brightness discrimination threshold described in Weber fractions is 0.18, which is modest compared to other vertebrates. PMID:23349946

  10. Ultraviolet investigations for lunar missions

    USGS Publications Warehouse

    Hemphill, William R.; Fischer, William A.; Dornbach, J.E.; Narin, Francis

    1966-01-01

    Preliminary field tests of an active ultraviolet imaging system have shown that it is possible to produce linages of the terrain from distances as great as 75 feet by means of reflected ultraviolet light at wavelengths longer than 3300 A. Minerals that luminesce when exposed to ultraviolet energy have been detected from distances as great as 200 feet. With appropriate design modifications, it may be possible to utilize a similar system in detecting luminescing minerals from greater distances. Also, with a similar system and appropriate auxiliary equipment such as image intensifiers, it may be possible to discriminate between naturally occurring materials on the basis of reflected ultraviolet energy at wavelengths shorter than 3000 A. In this part of the spectrum image contrast for some rock types may exceed that from visible light. Information from these and related ultraviolet spectralanalysis studies may be useful in evaluating data obtained from passive ultraviolet systems in lunar orbit as well as from active systems on the lunar surface.

  11. Extreme Ultraviolet Explorer. Long look at the next window

    NASA Technical Reports Server (NTRS)

    Maran, Stephen P.

    1991-01-01

    The Extreme Ultraviolet Explorer (EUVE) will map the entire sky to determine the existence, direction, brightness, and temperature of thousands of objects that are sources of so-called extreme ultraviolet (EUV) radiation. The EUV spectral region is located between the x-ray and ultraviolet regions of the electromagnetic spectrum. From the sky survey by EUVE, astronomers will determine the nature of sources of EUV light in our galaxy, and infer the distribution of interstellar gas for hundreds of light years around the solar system. It is from this gas and the accompanying dust in space that new stars and solar systems are born and to which evolving and dying stars return much of their material in an endless cosmic cycle of birth, death, and rebirth. Besides surveying the sky, astronomers will make detailed studies of selected objects with EUVE to determine their physical properties and chemical compositions. Also, they will learn about the conditions that prevail and the processes at work in stars, planets, and other sources of EUV radiation, maybe even quasars. The EUVE mission and instruments are described. The objects that EUVE will likely find are described.

  12. Richard Bright and his neurological studies.

    PubMed

    Pearce, J M S

    2009-01-01

    Richard Bright was one of the famous triumvirate of Guy's Hospital physicians in the Victorian era. Remembered for his account of glomerulonephritis (Bright's disease) he also made many important and original contributions to medicine and neurology. These included his work on cortical epileptogenesis, descriptions of simple partial (Jacksonian) seizures, infantile convulsions, and a variety of nervous diseases. Most notable were his reports of neurological studies including papers on traumatic tetanus, syringomyelia, arteries of the brain, contractures of spinal origin, tumours of the base of the brain, and narcolepsy. His career and these contributions are outlined.

  13. Kinematics of Low Surface Brightness Galaxies

    NASA Astrophysics Data System (ADS)

    Cardullo, A.; Pizzella, A.; Corsini, E. M.; Bertola, F.

    2008-10-01

    We analyzed the kinematic of 12 low surface-brightness (LSB) galaxies to study the correlation between the disk circular velocity V_{c} and the central velocity dispersion of the spheroidal component σ_{0}. This relation has been claimed to be either the same power-law relation tep{buy} or a different linear one tep{piz} with respect to high surface-brightness (HSB) galaxies. We confirm here that LSB and HSB galaxies follow two different linear V_{c}-σ_{0} relations.

  14. An Updated Ultraviolet Catalog of GALEX Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Bai, Yu; Zou, Hu; Liu, JiFeng; Wang, Song

    2015-09-01

    The ultraviolet (UV) catalog of nearby galaxies compiled by Gil de Paz et al. presents the integrated photometry and surface brightness profiles for 1034 nearby galaxies observed by GALEX. We provide an updated catalog of 4138 nearby galaxies based on the latest Genral Release (GR6/GR7) of GALEX. These galaxies are selected from HyperLeda with apparent diameters larger than 1‧. From the surface brightness profiles accurately measured using the deep NUV and FUV images, we have calculated the asymptotic magnitudes, aperture (D25) magnitudes, colors, structural parameters (effective radii and concentration indices), luminosities, and effective surface brightness for these galaxies. Archival optical and infrared photometry from HyperLeda, 2MASS, and IRAS are also integrated into the catalog. Our parameter measurements and some analyses are consistent with those of Paz et al. The (FUV - K) color provides a good criterion to distinguish between early- and late-type galaxies, which can be improved further using the concentration indices. The IRX-β relation is reformulated with our UV-selected nearby galaxies.

  15. AN UPDATED ULTRAVIOLET CATALOG OF GALEX NEARBY GALAXIES

    SciTech Connect

    Bai, Yu; Zou, Hu; Liu, JiFeng; Wang, Song E-mail: zouhu@nao.cas.cn E-mail: songw@nao.cas.cn

    2015-09-15

    The ultraviolet (UV) catalog of nearby galaxies compiled by Gil de Paz et al. presents the integrated photometry and surface brightness profiles for 1034 nearby galaxies observed by GALEX. We provide an updated catalog of 4138 nearby galaxies based on the latest Genral Release (GR6/GR7) of GALEX. These galaxies are selected from HyperLeda with apparent diameters larger than 1′. From the surface brightness profiles accurately measured using the deep NUV and FUV images, we have calculated the asymptotic magnitudes, aperture (D25) magnitudes, colors, structural parameters (effective radii and concentration indices), luminosities, and effective surface brightness for these galaxies. Archival optical and infrared photometry from HyperLeda, 2MASS, and IRAS are also integrated into the catalog. Our parameter measurements and some analyses are consistent with those of Paz et al. The (FUV − K) color provides a good criterion to distinguish between early- and late-type galaxies, which can be improved further using the concentration indices. The IRX–β relation is reformulated with our UV-selected nearby galaxies.

  16. Modelling ultraviolet threats

    NASA Astrophysics Data System (ADS)

    James, I.

    2016-10-01

    Electro-optically (EO) guided surface to air missiles (SAM) have developed to use Ultraviolet (UV) wavebands supplementary to the more common Infrared (IR) wavebands. Missiles such as the US Stinger have been around for some time but are not considered a proliferation risk. The Chinese FN-16 and Russian SA-29 (Verba) are considered a much higher proliferation risk. As a result, models of the missile seekers must be developed to understand the characteristics of the seeker and the potential performance enhancement that are included. Therefore, the purpose of this paper is to introduce the steps that have been taken to characterise and model these missiles. It begins by outlining some of the characteristics of the threats, the key elements of a UV scene, the potential choice of waveband for a detector, the initial modelling work to represent the UV detector of the missile and presents initial results. The modelling shows that the UV detection range of a typical aircraft is dependent on both the size of the aircraft and its reflectivity. However, the strength of this correlation is less than expected. As a result, further work is required to model more seeker types and to investigate what is causing the weak correlations found in these initial investigations. In addition, there needs to be further study of the sensitivities of the model to other variables, such as the modelled detectivity of the detector and the signal to noise ratio assumed. Overall, the outcome of this work will be to provide specifications for aircraft size and reflectivity that limit the effectiveness of the UV channels.

  17. Far Ultraviolet Astronomy

    NASA Technical Reports Server (NTRS)

    Sonneborn, George; Rabin, Douglas M. (Technical Monitor)

    2002-01-01

    The Far Ultraviolet Spectroscopic Explorer (FUSE) is studying a wide range of astronomical problems in the 905-1187 Angstrom wavelength region through the use of high resolution spectroscopy. The FUSE bandpass forms a nearly optimal complement to the spectral coverage provided by the Hubble Space Telescope (HST), which extends down to approximately 1170 Angstroms. The photoionization threshold of atomic hydrogen (911 Angstroms) sets a natural short-wavelength limit for the FUV. FUSE was launched in June 1999 from Cape Canaveral, Florida, on a Delta II rocket into a 768 km circular orbit. Scientific observations started later that year. This spectral region is extremely rich in spectral diagnostics of astrophysical gases over a wide range of temperatures (100 K to over 10 million K). Important strong spectral lines in this wavelength range include those of neutral hydrogen, deuterium, nitrogen, oxygen, and argon (H I, D I, N I, O I, and Ar I), molecular hydrogen (H2), five-times ionized oxygen (O VI), and several ionization states of sulfur (S III - S VI). These elements are essential for understanding the origin and evolution of the chemical elements, the formation of stars and our Solar System, and the structure of galaxies, including our Milky Way. FUSE is one of NASA's Explorer missions and a cooperative project of NASA and the space agencies of Canada and France. These missions are smaller, more scientifically focused missions than the larger observatories, like Hubble and Chandra. FUSE was designed, built and operated for NASA by the Department of Physics and Astronomy at Johns Hopkins University. Hundreds of astronomers world-wide are using FUSE for a wide range of scientific research. Some of the important scientific discoveries from the first two years of the mission are described.

  18. Photochemistry: A bright future for sunscreens

    NASA Astrophysics Data System (ADS)

    Stavros, Vasilios G.

    2014-11-01

    Understanding the intrinsic properties of molecules that protect our skin from the harmful rays of the Sun is critical to developing more efficacious sunscreen products. Now, gas-phase spectroscopy and microsolvation studies of model ultraviolet-filter molecules have shown that they may provide a route to developing improved sunscreens.

  19. The dark side of solar photospheric G-band bright points

    NASA Astrophysics Data System (ADS)

    Riethmüller, T. L.; Solanki, S. K.

    2017-02-01

    Bright, small-scale magnetic elements found mainly in intergranular lanes at the solar surface are named bright points (BPs). They show high contrasts in Fraunhofer G-band observations and are described by nearly vertical slender flux tubes or sheets. A recent comparison between BP observations in the ultraviolet (UV) and visible spectral range recorded with the balloon-borne observatory Sunrise and state-of-the-art magnetohydrodynamical (MHD) simulations revealed a kilogauss magnetic field for 98% of the synthetic BPs. Here we address the opposite question, namely which fraction of pixels hosting kilogauss fields coincides with an enhanced G-band brightness. We carried out 3D radiation MHD simulations for three magnetic activity levels (corresponding to the quiet Sun, weak and strong plage) and performed a full spectral line synthesis in the G-band. Only 7% of the kilogauss pixels in our quiet-Sun simulation coincide with a brightness lower than the mean quiet-Sun intensity, while 23% of the pixels in the weak-plage simulation and even 49% in the strong-plage simulation are associated with a local darkening. Dark strong-field regions are preferentially found in the cores of larger flux patches that are rare in the quiet Sun, but more common in plage regions, often in the vertices of granulation cells. The significant brightness shortfall in the core of larger flux patches coincides with a slight magnetic field weakening. Kilogauss elements in the quiet Sun are, on average, brighter than similar features in plage regions. Almost all strong-field pixels display a more or less vertical magnetic field orientation. Hence, in the quiet Sun, G-band BPs correspond almost one-to-one with kilogauss elements. In weak plage, the correspondence is still very good, but not perfect.

  20. A remarkable auroral event on jupiter observed in the ultraviolet with the hubble space telescope.

    PubMed

    Gérard, J C; Grodent, D; Dols, V; Prangé, R; Waite, J H; Gladstone, G R; Franke, K A; Paresce, F; Storrs, A; Jaffel, L B

    1994-12-09

    Two sets of ultraviolet images of the Jovian north aurora were obtained with the Faint Object Camera on board the Hubble Space Telescope. The first series shows an intense discrete arc in near corotation with the planet. The maximum apparent molecular hydrogen emission rate corresponds to an electron precipitation of approximately 1 watt per square meter, which is about 30,000 times larger than the solar heating by extreme ultraviolet radiation. Such a particle heating rate of the auroral upper atmosphere of Jupiter should cause a large transient temperature increase and generate strong thermospheric winds. Twenty hours after initial observation, the discrete arc had decreased in brightness by more than one order of magnitude. The time scale and magnitude of the change in the ultraviolet aurora leads us to suggest that the discrete Jovian auroral precipitation is related to large-scale variations in the current system, as is the case for Earth's discrete aurorae.

  1. Simultaneous brightness contrast of foraging Papilio butterflies

    PubMed Central

    Kinoshita, Michiyo; Takahashi, Yuki; Arikawa, Kentaro

    2012-01-01

    This study focuses on the sense of brightness in the foraging Japanese yellow swallowtail butterfly, Papilio xuthus. We presented two red discs of different intensity on a grey background to butterflies, and trained them to select one of the discs. They were successfully trained to select either a high intensity or a low intensity disc. The trained butterflies were tested on their ability to perceive brightness in two different protocols: (i) two orange discs of different intensity presented on the same intensity grey background and (ii) two orange discs of the same intensity separately presented on a grey background that was either higher or lower in intensity than the training background. The butterflies trained to high intensity red selected the orange disc of high intensity in protocol 1, and the disc on the background of low intensity grey in protocol 2. We obtained similar results in another set of experiments with purple discs instead of orange discs. The choices of the butterflies trained to low intensity red were opposite to those just described. Taken together, we conclude that Papilio has the ability to learn brightness and darkness of targets independent of colour, and that they have the so-called simultaneous brightness contrast. PMID:22179808

  2. Simultaneous brightness contrast of foraging Papilio butterflies.

    PubMed

    Kinoshita, Michiyo; Takahashi, Yuki; Arikawa, Kentaro

    2012-05-22

    This study focuses on the sense of brightness in the foraging Japanese yellow swallowtail butterfly, Papilio xuthus. We presented two red discs of different intensity on a grey background to butterflies, and trained them to select one of the discs. They were successfully trained to select either a high intensity or a low intensity disc. The trained butterflies were tested on their ability to perceive brightness in two different protocols: (i) two orange discs of different intensity presented on the same intensity grey background and (ii) two orange discs of the same intensity separately presented on a grey background that was either higher or lower in intensity than the training background. The butterflies trained to high intensity red selected the orange disc of high intensity in protocol 1, and the disc on the background of low intensity grey in protocol 2. We obtained similar results in another set of experiments with purple discs instead of orange discs. The choices of the butterflies trained to low intensity red were opposite to those just described. Taken together, we conclude that Papilio has the ability to learn brightness and darkness of targets independent of colour, and that they have the so-called simultaneous brightness contrast.

  3. Sky brightness during eclipses: a review.

    PubMed

    Silverman, S M; Mullen, E G

    1975-12-01

    This paper is abstracted from the introductory section of "Sky Brightness During Eclipses: A Compendium from the Literature," AFCRL-TR-74-0363, Special Reports 180, Air Force Cambridge Research Laboratories, Hanscom AFB, Massachusetts 01731. This report should be consulted for fuller details and tables.

  4. AMSR-E/Aqua Gridded Brightness Temperatures

    NASA Astrophysics Data System (ADS)

    Savoie, M.; Brodzik, M. J.; Knowles, K.

    2006-12-01

    Passive microwave brightness temperature data are a major component in many geophysical models and algorithms. For many researchers, a major difficulty in using these data is transforming the satellite swath data into a model-friendly, gridded format. Two new data sets and improvements to a toolkit at the National Snow and Ice Data Center (NSIDC) will help scientists incorporate these data into their research. We have produced "AMSR-E/Aqua Daily EASE-Grid Brightness Temperatures" from the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) instrument aboard NASA's Earth Observing System (EOS) Aqua satellite. This data set will complement and extend NSIDC's existing EASE-grid brightness temperature data sets, with new data beginning June 2002 and continuing throughout the life-cycle of the instrument. Additionally, in order to respond to user demand for quarter-degree data, we are distributing "AMSR-E/Aqua Daily Global Quarter-Degree Gridded Brightness Temperatures" also spanning the AMSR-E time period. Researchers whose needs are not met by the above data sets can create customized grids with our AMSR-E Swath to Grid Toolkit. Recent improvements to the toolkit allow subsetted swath data as input, greatly reducing the initial data volume required to produce customized grids.

  5. Bright Meteor Lights Up Atlanta Skies

    NASA Video Gallery

    This video shows a very bright meteor that streaked over the skies of Atlanta, Ga., on the night of Aug. 28, 2011. The view is from an all sky camera in Cartersville, Ga., operated by NASA’s Mars...

  6. Brightness versus roughness: a multiscale approach

    NASA Astrophysics Data System (ADS)

    Bigerelle, M.; Marteau, J.; Paulin, C.

    2015-03-01

    A link between roughness and brightness is sought for brass specimens that were superfinished, sandblasted and brushed. Only the blasting conditions are varied in order to get different roughness and brightness. First, a relation between roughness and brightness is sought for specimens that were superfinished and sandblasted. The best relation is obtained using the mean height of the motifs, calculated using a low-pass filter and cut-off length equal to 30 μm, with a logarithmic-logarithmic model. Then, the same type of relation is determined after superfinishing sandblasting and brushing. The core material volume Vmc, computed using a high-pass filter with a cut-off length of 60 μm and a linear-logarithmic relationship, gives the best results. A relation between roughness and brightness that is common to both the pre-brushing state and post-brushing state is identified: the best roughness parameter is the arithmetic mean deviation Sa using a high-pass filter with a cut-off of 15 μm, with a logarithmic-logarithmic relationship. Finally, it is shown that the use of these filtering conditions enables us to verify the model of Beckmann and Spizzichino for the examined specimens. This scale corresponds to the end of the fractal regime and is close to the end of the signal correlation.

  7. Brightness of synchrotron radiation from wigglers

    NASA Astrophysics Data System (ADS)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

    2016-01-01

    According to the literature, while calculating the brightness of synchrotron radiation from wigglers, one needs to account for the so-called 'depth-of-field' effects. In fact, the particle beam cross-section varies along the wiggler. It is usually stated that the effective photon source size increases accordingly, while the brightness is reduced. Here we claim that this is a misconception originating from an analysis of the wiggler source based on geometrical arguments, regarded as almost self-evident. According to electrodynamics, depth-of-field effects do not exist: we demonstrate this statement both theoretically and numerically, using a well-known first-principle computer code. This fact shows that under the usually accepted approximations, the description of the wiggler brightness turns out to be inconsistent even qualitatively. Therefore, there is a need for a well-defined procedure for computing the brightness from a wiggler source. We accomplish this task based on the use of a Wigner function formalism. We exemplify this formalism in simple limiting cases. We consider the problem of the calculation of the wiggler source size by means of numerical simulations alone, which play the same role of an experiment. We report a significant numerical disagreement between exact calculations and approximations currently used in the literature.

  8. Learning Resources on Ultraviolet Astronomy: The Shuttle-Borne Spacelab/Astro Missions

    NASA Astrophysics Data System (ADS)

    Waller, W. H.; Stecher, T. P.

    1994-12-01

    Beyond the blue, beyond the violet, and into the ultraviolet part of the electromagnetic spectrum, the radiant universe appears strangely altered. At these shorter wavelengths and higher photon energies, the hottest stars shine brightly, while the cooler more common stars like the Sun virtually disappear from view. Clusters and associations of young stars are dominated by just a few massive ultraviolet-bright stars, while ancient globular clusters are reduced to their hottest, most rapidly evolving members. Spiral galaxies that look like graceful pinwheels in visible-light images are transformed into knotty webs --- each knot containing thousands of young hot stars. And the space between the stars, clusters, and galaxies appears profoundly black --- up to 100 times darker than the nighttime sky as seen at visible wavelengths. Until the last decade, our view of the ultraviolet universe was impeded by the stratospheric ozone layer that protects life on Earth from the Sun's harmful UV radiation. Subsequent balloon, sounding rocket, and satellite flights have yielded fascinating glimpses of the ultraviolet universe. In 1990, the Space Shuttle Columbia flew the Spacelab/Astro-1 mission. Astro is the first and only true astronomical observatory to operate onboard the Space Shuttle. It consists of 3 ultraviolet telescopes which are attached to a single pointing system in the Shuttle bay. During the Astro-1 mission, these instruments obtained UV images and spectra of hundreds of astronomical objects. Learning resources relating to this mission include a new slide set and booklet, ``Beyond the Blue: Greatest Hits of the Ultraviolet Imaging Telescope,'' which is being distributed by the ASP through its mail-order catalogue. There is also a teacher's guide with activities, ``Astro-1: Seeing in a New Light'' which is available from the NASA Teacher Resource Laboratories. Sources of information on the upcoming flight of Spacelab/Astro-2 aboard the Endeavour (currently scheduled

  9. Future Directions in Ultraviolet Spectroscopy

    NASA Technical Reports Server (NTRS)

    Sonneborn, George (Editor); Moos, Warren; VanSteenberg, Michael

    2009-01-01

    The 'Future Directions in Ultraviolet Spectroscopy' conference was inspired by the accomplishments of the Far Ultraviolet Spectroscopic Explorer (FUSE) Mission. The FUSE mission was launched in June 1999 and spent over eight years exploring the far-ultraviolet universe, gathering over 64 million seconds of high-resolution spectral data on nearly 3000 astronomical targets. The goal of this conference was not only to celebrate the accomplishments of FUSE, but to look toward the future and understand the major scientific drivers for the ultraviolet capabilities of the next generation fo space observatories. Invited speakers presented discussions based on measurements made by FUSE and other ultraviolet instruments, assessed their connection with measurements made with other techniques and, where appropriate, discussed the implications of low-z measurements for high-z phenomena. In addition to the oral presentations, many participants presented poster papers. The breadth of these presentation made it clear that much good science is still in progress with FUSE data and that these result will continue to have relevance in many scientific areas.

  10. Harmful effects of ultraviolet radiation

    SciTech Connect

    Not Available

    1989-07-21

    Tanning for cosmetic purposes by sunbathing or by using artificial tanning devices is widespread. The hazards associated with exposure to ultraviolet radiation are of concern to the medical profession. Depending on the amount and form of the radiation, as well as on the skin type of the individual exposed, ultraviolet radiation causes erythema, sunburn, photodamage (photoaging), photocarcinogenesis, damage to the eyes, alteration of the immune system of the skin, and chemical hypersensitivity. Skin cancers most commonly produced by ultraviolet radiation are basal and squamous cell carcinomas. There also is much circumstantial evidence that the increase in the incidence of cutaneous malignant melanoma during the past half century is related to increased sun exposure, but this has not been proved. Effective and cosmetically acceptable sunscreen preparations have been developed that can do much to prevent or reduce most harmful effects to ultraviolet radiation if they are applied properly and consistently. Other safety measures include (1) minimizing exposure to ultraviolet radiation, (2) being aware of reflective surfaces while in the sun, (3) wearing protective clothing, (4) avoiding use of artificial tanning devices, and (5) protecting infants and children.

  11. Ultraviolet-radiation-curable paints

    SciTech Connect

    Grosset, A M; Su, W F.A.; Vanderglas, E

    1981-09-30

    In product finishing lines, ultraviolet radiation curing of paints on prefabricated structures could be more energy efficient than curing by natural gas fired ovens, and could eliminate solvent emission. Diffuse ultraviolet light can cure paints on three dimensional metal parts. In the uv curing process, the spectral output of radiation sources must complement the absorption spectra of pigments and photoactive agents. Photosensitive compounds, such as thioxanthones, can photoinitiate unsaturated resins, such as acrylated polyurethanes, by a free radical mechanism. Newly developed cationic photoinitiators, such as sulfonium or iodonium salts (the so-called onium salts) of complex metal halide anions, can be used in polymerization of epoxy paints by ultraviolet light radiation. One-coat enamels, topcoats, and primers have been developed which can be photoinitiated to produce hard, adherent films. This process has been tested in a laboratory scale unit by spray coating these materials on three-dimensional objects and passing them through a tunnel containing uv lamps.

  12. Ultraviolet spectrophotometry of three LINERs

    NASA Technical Reports Server (NTRS)

    Goodrich, R. W.; Keel, W. C.

    1986-01-01

    Three galaxies known to be LINERs were observed spectroscopically in the ultraviolet in an attempt to detect the presumed nonthermal continuum source thought to be the source of photoionization in the nuclei. NGC 4501 was found to be too faint for study with the IUE spectrographs, while NGC 5005 had an extended ultraviolet light profile. Comparison with the optical light profile of NGC 5005 indicates that the ultraviolet source is distributed spatially in the same manner as the optical starlight, probably indicating that the ultraviolet excess is due to a component of hot stars in the nucleus. These stars contribute detectable absorption features longward of 2500 A; together with optical data, the IUE spectra suggest a burst of star formation about 1 billion yr ago, with a lower rate continuing to produce a few OB stars. In NGC 4579, a point source contributing most of the ultraviolet excess is found that is much different than the optical light distribution. Furthermore, the ultraviolet to X-ray spectral index in NGC 4579 is 1.4, compatible with the UV to X-ray indices found for samples of Seyfert galaxies. This provides compelling evidence for the detection of the photoionizing continuum in NGC 4579 and draws the research fields of normal galaxies and active galactic nuclei closer together. The emission-line spectrum of NGC 4579 is compared with calculations from a photoionization code, CLOUDY, and several shock models. The photoionization code is found to give superior results, adding to the increasing weight of evidence that the LINER phenomenon is essentially a scaled-down version of the Seyfert phenomenon.

  13. Ultraviolet corona detection sensor study

    NASA Technical Reports Server (NTRS)

    Schmitt, R. J.; MATHERN

    1976-01-01

    The feasibility of detecting electrical corona discharge phenomena in a space simulation chamber via emission of ultraviolet light was evaluated. A corona simulator, with a hemispherically capped point to plane electrode geometry, was used to generate corona glows over a wide range of pressure, voltage, current, electrode gap length and electrode point radius. Several ultraviolet detectors, including a copper cathode gas discharge tube and a UV enhanced silicon photodiode detector, were evaluated in the course of the spectral intensity measurements. The performance of both silicon target vidicons and silicon intensified target vidicons was evaluated analytically using the data generated by the spectroradiometer scans and the performance data supplied by the manufacturers.

  14. Jovian ultraviolet auroral activity, 1981-1991

    NASA Technical Reports Server (NTRS)

    Livengood, T. A.; Moos, H. W.; Ballester, G. E.; Prange, R. M.

    1992-01-01

    IUE observations of H2 UV emissions for the 1981-1991 period are presently used to investigate the auroral brightness distribution on the surface of Jupiter. The brightness, which is diagnostic of energy input to the atmosphere as well as of magnetospheric processes, is determined by comparing model-predicted brightnesses against empirical ones. The north and south aurorae appear to be correlated in brightness and in variations of the longitude of peak brightness. There are strong fluctuations in all the parameters of the brightness distribution on much shorter time scales than those of solar maximum-minimum.

  15. The Ultraviolet Spectroscopic Legacy of HST

    NASA Astrophysics Data System (ADS)

    Ayres, Thomas R.

    2016-01-01

    Hubble Space Telescope has been a spectacularly successful platform for spectroscopy in the diagnostic-rich far-ultraviolet (FUV: 120-170 nm) and near-ultraviolet (NUV: 170-310 nm) regions. HST has hosted four generations of UV instruments, beginning with Faint Object Spectrograph (FOS) and Goddard High-Resolution Spectrograph (GHRS) in the original 1990 payload, followed by Space Telescope Imaging Spectrograph (STIS) in 1997, and more recently Cosmic Origins Spectrograph (COS) as part of Servicing Mission 4 in 2009. The latter two instruments have contributed by far the lion's share of HST's spectroscopic archive: STIS, because of its longevity (thirteen years in operation so far, although with a hiatus between 2004-2009); and COS because of its high sensitivity, which allows efficient observations, and thus many more targets in a typical GO program. STIS benefits from a compact echelle design, and the sharp stable imaging of HST, to provide high-resolution (3-7 km s-1) spectra of bright objects, including stars, nebulae, quasars, novae, and so forth. COS achieves astounding sensitivity in the FUV by a sophisticated design that compensates for the spherical abberation of HST's primary mirror, disperses the target's light, and focuses the spectral image all with just a single optical element. While the spectral resolution of COS (about 18 km s-1) is not as high as that of STIS, it is adequate for diverse investigations, including faint broad-lined AGN at the edge of the Universe, hot stars in nearby galaxies, and magnetically active planet-hosting red dwarfs in the solar neighborhood. Thanks in part to the "UV Initiative" in recent HST proposal cycles, there have been several large efforts involving both STIS and COS, to assemble important spectral collections, including full UV atlases of representative hot and cool stars at high resolution with STIS; long time series of archetype AGN ("reverberation mapping") with COS; and hundreds of sightlines to distant

  16. Image mosaic with color and brightness correction

    NASA Astrophysics Data System (ADS)

    Zhao, Yili; Xu, Dan; Pan, Zhigeng

    2004-03-01

    Image mosaic is comprised of building a large field of view from a sequence of smaller images. It can be performed by registering, projective warping, resampling and compositing a serials of images. Due to the many possible factors for color and brightness variations when taking images, it is possible to lead to misalignment and obtain poor stitching result. Despite image mosaic can be manually adjusted using some photo editors like PhotoShop, this is not only tedious but also requires skills, knowledge and experience. Automatic adjustment is therefore desirable. By converting images to lαβ space and applying a special statistical analysis, color and brightness correction can be done automatically and improved image mosaic can be obtained.

  17. Nonlinear Brightness Optimization in Compton Scattering

    SciTech Connect

    Hartemann, Fred V.; Wu, Sheldon S. Q.

    2013-07-26

    In Compton scattering light sources, a laser pulse is scattered by a relativistic electron beam to generate tunable x and gamma rays. Because of the inhomogeneous nature of the incident radiation, the relativistic Lorentz boost of the electrons is modulated by the ponderomotive force during the interaction, leading to intrinsic spectral broadening and brightness limitations. We discuss these effects, along with an optimization strategy to properly balance the laser bandwidth, diffraction, and nonlinear ponderomotive force.

  18. Australia 31-GHz brightness temperature exceedance statistics

    NASA Technical Reports Server (NTRS)

    Gary, B. L.

    1988-01-01

    Water vapor radiometer measurements were made at DSS 43 during an 18 month period. Brightness temperatures at 31 GHz were subjected to a statistical analysis which included correction for the effects of occasional water on the radiometer radome. An exceedance plot was constructed, and the 1 percent exceedance statistics occurs at 120 K. The 5 percent exceedance statistics occurs at 70 K, compared with 75 K in Spain. These values are valid for all of the three month groupings that were studied.

  19. Spectral Characterization of Bright Materials on Vesta

    NASA Technical Reports Server (NTRS)

    Capaccioni, Fabrizio; DeSanctis, M. C.; Ammannito, E.; Li, Jian-Yang; Longobardo, A.; Mittlefehldt, David W.; Palomba, E.; Pieters, C. M.; Schroeder, S. E.; Tosi, F.; Hiesinger, H.; Blewett, D. T.; Russell, C. T.; Raymond, C. A.

    2012-01-01

    The surface of Vesta, as observed by the camera and imaging spectrometer onboard the Dawn spacecraft, displays large surface diversity in terms of its geology and mineralogy with noticeably dark and bright areas on the surface often associated with various geological features and showing remarkably different forms. Here we report our initial attempt to spectrally characterize the areas that are distinctively brighter than their surroundings.

  20. iPTF report of bright transients

    NASA Astrophysics Data System (ADS)

    Cannella, Chris; Kuesters, Daniel; Ferretti, Raphael; Blagorodnova, Nadejda; Adams, Scott; Kupfer, Thomas; Neill, James D.; Walters, Richard; Yan, Lin; Kulkarni, Shri

    2017-02-01

    The intermediate Palomar Transient Factory (iPTF; ATel #4807) reports the following bright ( Our automated candidate vetting to distinguish a real astrophysical source (1.0) from bogus artifacts (0.0) is powered by three generations of machine learning algorithms: RB2 (Brink et al. 2013MNRAS.435.1047B), RB4 (Rebbapragada et al. 2015AAS...22543402R), and RB5 (Wozniak et al. 2013AAS...22143105W).

  1. Nonlinear Brightness Optimization in Compton Scattering

    NASA Astrophysics Data System (ADS)

    Hartemann, Fred V.; Wu, Sheldon S. Q.

    2013-07-01

    In Compton scattering light sources, a laser pulse is scattered by a relativistic electron beam to generate tunable x and gamma rays. Because of the inhomogeneous nature of the incident radiation, the relativistic Lorentz boost of the electrons is modulated by the ponderomotive force during the interaction, leading to intrinsic spectral broadening and brightness limitations. These effects are discussed, along with an optimization strategy to properly balance the laser bandwidth, diffraction, and nonlinear ponderomotive force.

  2. Modular Zero Energy. BrightBuilt Home

    SciTech Connect

    Aldrich, Robb; Butterfield, Karla

    2016-03-01

    With funding from the Building America Program, part of the U.S. Department of Energy Building Technologies Office, the Consortium for Advanced Residential Buildings (CARB) worked with BrightBuilt Home (BBH) to evaluate and optimize building systems. CARB’s work focused on a home built by Black Bros. Builders in Lincolnville, Maine (International Energy Conservation Code Climate Zone 6). As with most BBH projects to date, modular boxes were built by Keiser Homes in Oxford, Maine.

  3. Bright and Dark Slopes on Ganymede

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Ridges on the edge of Ganymede's north polar cap show bright east-facing slopes and dark west-facing slopes with troughs of darker material below the larger ridges. North is to the top. The bright slopes may be due to grain size differences, differences in composition between the original surface and the underlying material, frost deposition, or illumination effects. The large 2.4 kilometer (1.5 mile) diameter crater in this image shows frost deposits located on the north-facing rim slope, away from the sun. A smaller 675 meter (2200 foot) diameter crater in the center of the image is surrounded by a bright deposit which may be ejecta from the impact. Ejecta deposits such as this are uncommon for small craters on Ganymede. This image measures 18 by 19 kilometers (11 by 12 miles) and has a resolution of 45 meters (148 feet) per pixel. NASA's Galileo spacecraft obtained this image on September 6, 1996 during its second orbit around Jupiter.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

  4. Brightness Changes in Sun-like Stars

    NASA Technical Reports Server (NTRS)

    Henry, Stephen M.; Henry, Gregory W.

    1998-01-01

    Does the Sun's energy output vary with time? Are observable climatic changes on the earth caused by changes in the Sun? Can we gain greater insight into this relation-ship by studying other stars with properties similar to the Sun's? In recent years, satellite observations have shown that the solar irradiance varies in phase with the 1 l-year sunspot cycle. The Sun is brighter by about O.l% at the peak of the sunspot cycle when solar magnetic activity is at its maximum. Over longer intervals, changes in the cart h's climate and solar magnetic activity seem to be correlated. We are using automatic photoelectric telescopes to measure brightness changes in a sample of 150 Sun-like stars. Lowell Observatory astronomers have also observed about 30 of these same stars with a manual telescope in a program that began 10 years before ours. Since these two data sets were acquired with different instruments and so have significant systematic differences, we developed software to combine them accurately and, therefore, extend our observational time coverage. We show sample results of brightness variations over 14 years in several Sun-like stars with different ages. Longitudinal studies like these, combined with cross-sectional studies of the larger sample of stars, may eventually allow us to infer with confidence the Sun's long-term brightness history and its impact on the earth's climate.

  5. Brightness illusion in the guppy (Poecilia reticulata).

    PubMed

    Agrillo, Christian; Miletto Petrazzini, Maria Elena; Bisazza, Angelo

    2016-02-01

    A long-standing debate surrounds the issue of whether human and nonhuman species share similar perceptual mechanisms. One experimental strategy to compare visual perception of vertebrates consists in assessing how animals react in the presence of visual illusions. To date, this methodological approach has been widely used with mammals and birds, while few studies have been reported in distantly related species, such as fish. In the present study we investigated whether fish perceive the brightness illusion, a well-known illusion occurring when 2 objects, identical in physical features, appear to be different in brightness. Twelve guppies (Poecilia reticulata) were initially trained to discriminate which rectangle was darker or lighter between 2 otherwise identical rectangles. Three different conditions were set up: neutral condition between rectangle and background (same background used for both darker and lighter rectangle); congruent condition (darker rectangle in a darker background and lighter rectangle in a lighter background); and incongruent condition (darker rectangle in a lighter background and lighter rectangle in a darker background). After reaching the learning criterion, guppies were presented with the illusory pattern: 2 identical rectangles inserted in 2 different backgrounds. Guppies previously trained to select the darker rectangle showed a significant choice of the rectangle that appears to be darker by human observers (and vice versa). The human-like performance exhibited in the presence of the illusory pattern suggests the existence of similar perceptual mechanisms between humans and fish to elaborate the brightness of objects.

  6. Search for bright stars with infrared excess

    SciTech Connect

    Raharto, Moedji

    2014-03-24

    Bright stars, stars with visual magnitude smaller than 6.5, can be studied using small telescope. In general, if stars are assumed as black body radiator, then the color in infrared (IR) region is usually equal to zero. Infrared data from IRAS observations at 12 and 25μm (micron) with good flux quality are used to search for bright stars (from Bright Stars Catalogues) with infrared excess. In magnitude scale, stars with IR excess is defined as stars with IR color m{sub 12}−m{sub 25}>0; where m{sub 12}−m{sub 25} = −2.5log(F{sub 12}/F{sub 25})+1.56, where F{sub 12} and F{sub 25} are flux density in Jansky at 12 and 25μm, respectively. Stars with similar spectral type are expected to have similar color. The existence of infrared excess in the same spectral type indicates the existence of circum-stellar dust, the origin of which is probably due to the remnant of pre main-sequence evolution during star formation or post AGB evolution or due to physical process such as the rotation of those stars.

  7. Personal audio with a planar bright zone.

    PubMed

    Coleman, Philip; Jackson, Philip J B; Olik, Marek; Pedersen, Jan Abildgaard

    2014-10-01

    Reproduction of multiple sound zones, in which personal audio programs may be consumed without the need for headphones, is an active topic in acoustical signal processing. Many approaches to sound zone reproduction do not consider control of the bright zone phase, which may lead to self-cancellation problems if the loudspeakers surround the zones. Conversely, control of the phase in a least-squares sense comes at a cost of decreased level difference between the zones and frequency range of cancellation. Single-zone approaches have considered plane wave reproduction by focusing the sound energy in to a point in the wavenumber domain. In this article, a planar bright zone is reproduced via planarity control, which constrains the bright zone energy to impinge from a narrow range of angles via projection in to a spatial domain. Simulation results using a circular array surrounding two zones show the method to produce superior contrast to the least-squares approach, and superior planarity to the contrast maximization approach. Practical performance measurements obtained in an acoustically treated room verify the conclusions drawn under free-field conditions.

  8. Bright Ray Craters in Ganymede's Northern Hemisphere

    NASA Technical Reports Server (NTRS)

    1979-01-01

    GANYMEDE COLOR PHOTOS: This color picture as acquired by Voyager 1 during its approach to Ganymede on Monday afternoon (the 5th of March). At ranges between about 230 to 250 thousand km. The images show detail on the surface with a resolution of four and a half km. This picture is of a region in the northern hemisphere near the terminator. It shows a variety of impact structures, including both razed and unrazed craters, and the odd, groove-like structures discovered by Voyager in the lighter regions. The most striking features are the bright ray craters which have a distinctly 'bluer' color appearing white against the redder background. Ganymede's surface is known to contain large amounts of surface ice and it appears that these relatively young craters have spread bright fresh ice materials over the surface. Likewise, the lighter color and reflectivity of the grooved areas suggests that here, too, there is cleaner ice. We see ray craters with all sizes of ray patterns, ranging from extensive systems of the crater in the southern part of this picture, which has rays at least 300-500 kilometers long, down to craters which have only faint remnants of bright ejects patterns (such as several of the craters in the southern half of PIA01516; P21262). This variation suggests that, as on the Moon, there are processes which act to darken ray material, probably 'gardening' by micrometeoroid impact. JPL manages and controls the Voyager project for NASA's Office of Space Science.

  9. Ultraviolet, visible, and infrared rays

    NASA Technical Reports Server (NTRS)

    Taylor, J. H.; Letavet, A. A.

    1975-01-01

    Sources of infrared, visible and ultraviolet radiation are discussed, and important associated biological and psychophysiological effects are described. The problem of protection from excessively high or low levels of radiant energy in these spectral regions is considered and optimal levels are suggested.

  10. Ultraviolet and Light Absorption Spectrometry.

    ERIC Educational Resources Information Center

    Hargis, L. G.; Howell, J. A.

    1984-01-01

    Reviews developments in ultraviolet and light absorption spectrometry from December 1981 through November 1983, focusing on the chemistry involved in developing suitable reagents, absorbing systems, and methods of determination, and on physical aspects of the procedures. Includes lists of spectrophotometric methods for metals, non-metals, and…

  11. A vacuum ultraviolet spectrophotometric system

    NASA Technical Reports Server (NTRS)

    Spann, James F.; Keffer, Charles E.; Zukic, Muamer

    1993-01-01

    The development of a vacuum ultraviolet spectrophotometric system for measuring transmittance and reflectance at variable angles is presented. Using various detectors and sources, the spectrophotometric system has been used for wavelengths from 80 nm to 300 nm with optical components up to 80 mm in diameter. The capability exists to make measurements through the visible range.

  12. Active Processes: Bright Streaks and Dark Fans

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Figure 1Figure 2

    In a region of the south pole known informally as 'Ithaca' numerous fans of dark frost form every spring. HiRISE collected a time lapse series of these images, starting at Ls = 185 and culminating at Ls = 294. 'Ls' is the way we measure time on Mars: at Ls = 180 the sun passes the equator on its way south; at Ls = 270 it reaches its maximum subsolar latitude and summer begins.

    In the earliest image (figure 1) fans are dark, but small narrow bright streaks can be detected. In the next image (figure 2), acquired at Ls = 187, just 106 hours later, dramatic differences are apparent. The dark fans are larger and the bright fans are more pronounced and easily detectable. The third image in the sequence shows no bright fans at all.

    We believe that the bright streaks are fine frost condensed from the gas exiting the vent. The conditions must be just right for the bright frost to condense.

    Observation Geometry Image PSP_002622_0945 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 16-Feb-2007. The complete image is centered at -85.2 degrees latitude, 181.5 degrees East longitude. The range to the target site was 246.9 km (154.3 miles). At this distance the image scale is 49.4 cm/pixel (with 2 x 2 binning) so objects 148 cm across are resolved. The image shown here has been map-projected to 50 cm/pixel . The image was taken at a local Mars time of 05:46 PM and the scene is illuminated from the west with a solar incidence angle of 88 degrees, thus the sun was about 2 degrees above the horizon. At a solar longitude of 185.1 degrees, the season on Mars is Northern Autumn.

  13. Unusual satellite data: A black hole?. [International Ultraviolet Explorer observations

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Data obtained by the NASA-launched European Space Agency's International Ultraviolet Explorer satellite suggests the possibility of a massive black hole at the center of some globular clusters (star groups) in our galaxy. Six of these clusters, three of them X-ray sources, were closely examined. Onboard short wavelength UV instrumentation penetrated the background denseness of the clusters 15,000 light years away where radiation, probably from a group of 10 to 20 bright blue stars orbiting the core, was observed. The stars may well be orbiting a massive black hole the size of 1,000 solar systems. The existence of the black hole is uncertain. The dynamics of the stars must be studied first to determine how they rotate in relation to the center of the million-star cluster. This may better indicate what provides the necessary gravitational pull that holds them in orbit.

  14. Two types of coronal bright points their characteristics, and evolution

    NASA Astrophysics Data System (ADS)

    Sattarov, Isroil; Karachik, Nina V.; Sherdanov, Chori T.; Tillaboev, Azlarxon M.; Pevtsov, Alexei A.

    2011-08-01

    Using maximum brightness of coronal bright point's (CBP) as a criterion, we separate them on two categories: dim CBPs, associated with areas of a quiet Sun, and bright CBPs, associated with an active Sun. This study reports on characteristics of two types of CBPs and their evolution.

  15. 7 CFR 51.2000 - Clean and bright.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Clean and bright. 51.2000 Section 51.2000 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing....2000 Clean and bright. Clean and bright means that the individual filbert and the lot as a whole...

  16. 7 CFR 51.2000 - Clean and bright.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Clean and bright. 51.2000 Section 51.2000 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing....2000 Clean and bright. Clean and bright means that the individual filbert and the lot as a whole...

  17. An Increasing Stellar Baryon Fraction in Bright Galaxies at High Redshift

    NASA Astrophysics Data System (ADS)

    Finkelstein, Steven L.; Song, Mimi; Behroozi, Peter; Somerville, Rachel S.; Papovich, Casey; Milosavljević, Miloš; Dekel, Avishai; Narayanan, Desika; Ashby, Matthew L. N.; Cooray, Asantha; Fazio, Giovanni G.; Ferguson, Henry C.; Koekemoer, Anton M.; Salmon, Brett; Willner, S. P.

    2015-12-01

    Recent observations have shown that the characteristic luminosity of the rest-frame ultraviolet (UV) luminosity function does not significantly evolve at 4 < z < 7 and is approximately {M}{UV}*˜ -21. We investigate this apparent non-evolution by examining a sample of 173 bright, MUV < -21 galaxies at z = 4-7, analyzing their stellar populations and host halo masses. Including deep Spitzer/IRAC imaging to constrain the rest-frame optical light, we find that {M}{UV}* galaxies at z = 4-7 have similar stellar masses of log(M/M⊙) = 9.6-9.9 and are thus relatively massive for these high redshifts. However, bright galaxies at z = 4-7 are less massive and have younger inferred ages than similarly bright galaxies at z = 2-3, even though the two populations have similar star formation rates and levels of dust attenuation for a fixed dust-attenuation curve. Matching the abundances of these bright z = 4-7 galaxies to halo mass functions from the Bolshoi ΛCDM simulation implies that the typical halo masses in ˜ {M}{{UV}}* galaxies decrease from log(Mh/M⊙) = 11.9 at z = 4 to log(Mh/M⊙) = 11.4 at z = 7. Thus, although we are studying galaxies at a similar stellar mass across multiple redshifts, these galaxies live in lower mass halos at higher redshift. The stellar baryon fraction in ˜ {M}{{UV}}* galaxies in units of the cosmic mean Ωb/Ωm rises from 5.1% at z = 4 to 11.7% at z = 7; this evolution is significant at the ˜3σ level. This rise does not agree with simple expectations of how galaxies grow, and implies that some effect, perhaps a diminishing efficiency of feedback, is allowing a higher fraction of available baryons to be converted into stars at high redshifts.

  18. Calculation of gyrosynchrotron radiation brightness temperature for outer bright loop of ICME

    NASA Astrophysics Data System (ADS)

    Sun, Weiying; Wu, Ji; Wang, C. B.; Wang, S.

    :Solar polar orbit radio telescope (SPORT) is proposed to detect the high density plasma clouds of outer bright loop of ICMEs from solar orbit with large inclination. Of particular interest is following the propagation of the plasma clouds with remote sensor in radio wavelength band. Gyrosynchrotron emission is a main radio radiation mechanism of the plasma clouds and can provide information of interplanetary magnetic field. In this paper, we statistically analyze the electron density, electron temperature and magnetic field of background solar wind in time of quiet sun and ICMEs propagation. We also estimate the fluctuation range of the electron density, electron temperature and magnetic field of outer bright loop of ICMEs. Moreover, we calculate and analyze the emission brightness temperature and degree of polarization on the basis of the study of gyrosynchrotron emission, absorption and polarization characteristics as the optical depth is less than or equal to 1.

  19. Dark and Bright Ridges on Europa

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This high-resolution image of Jupiter's moon Europa, taken by NASA's Galileo spacecraft camera, shows dark, relatively smooth region at the lower right hand corner of the image which may be a place where warm ice has welled up from below. The region is approximately 30 square kilometers in area. An isolated bright hill stands within it. The image also shows two prominent ridges which have different characteristics; youngest ridge runs from left to top right and is about 5 kilometers in width (about 3.1 miles). The ridge has two bright, raised rims and a central valley. The rims of the ridge are rough in texture. The inner and outer walls show bright and dark debris streaming downslope, some of it forming broad fans. This ridge overlies and therefore must be younger than a second ridge running from top to bottom on the left side of the image. This dark 2 km wide ridge is relatively flat, and has smaller-scale ridges and troughs along its length.

    North is to the top of the picture, and the sun illuminates the surface from the upper left. This image, centered at approximately 14 degrees south latitude and 194 degrees west longitude, covers an area approximately 15 kilometers by 20 kilometers (9 miles by 12 miles). The resolution is 26 meters (85 feet) per picture element. This image was taken on December 16, 1997 at a range of 1300 kilometers (800 miles) by Galileo's solid state imaging system.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/ galileo.

  20. High-brightness laser-induced EUV source based on tin plasma with an unlimited lifetime of electrodes

    SciTech Connect

    Vinokhodov, A Yu; Lash, A A; Krivtsun, V M; Koshelev, K N; Borisov, V M; Yakushev, O F

    2016-01-31

    Characteristics of a source of laser-induced radiation in the extreme ultraviolet (EUV) range, obtained in a discharge between two jets of liquid tin, are investigated. The possibility of designing a high-brightness EUV source on this basis for employing in mask inspection techniques in projection EUV lithography is demonstrated. The average efficiency of converting the electric energy to radiation in the spectral range of 13.5 ± 0.135 nm is approximately 2%/2π sr with the size of emitting plasma 0.2 ± 0.35 mm. The possibility of producing a EUV source with a brightness of about 200 W (mm{sup 2} sr){sup -1} is demonstrated. (euv lithography sources)

  1. Indirect Ultraviolet-Reactivation of Phage λ

    PubMed Central

    George, Jacqueline; Devoret, Raymond; Radman, Miroslav

    1974-01-01

    When an F- recipient Escherichia coli K12 bacterium receives Hfr or F-lac+ DNA from an ultraviolet-irradiated donor, its capacity to promote DNA repair and mutagenesis of ultraviolet-damaged phage λ is substantially increased. We call this phenomenon indirect ultraviolet-reactivation, since its features are essentially the same as those of ultraviolet-reactivation; this repair process occurs in pyrimidine dimer excision-deficient strains and produces clear plaque mutations of the restored phage. Moreover, this process is similar to indirect ultraviolet-induction of prophage λ, since it is promoted by conjugation. However, contrarily to indirect induction, it is produced by Hfr donors and occurs in recipients restricting the incoming ultraviolet-damaged donor DNA. The occurrence of indirect ultraviolet-reactivation provides evidence for the existence in E. coli of an inducible error-prone mechanism for the repair of DNA. PMID:4589889

  2. Raman beam combining for laser brightness enhancement

    DOEpatents

    Dawson, Jay W.; Allen, Graham S.; Pax, Paul H.; Heebner, John E.; Sridharan, Arun K.; Rubenchik, Alexander M.; Barty, Chrisopher B. J.

    2015-10-27

    An optical source capable of enhanced scaling of pulse energy and brightness utilizes an ensemble of single-aperture fiber lasers as pump sources, with each such fiber laser operating at acceptable pulse energy levels. Beam combining involves stimulated Raman scattering using a Stokes' shifted seed beam, the latter of which is optimized in terms of its temporal and spectral properties. Beams from fiber lasers can thus be combined to attain pulses with peak energies in excess of the fiber laser self-focusing limit of 4 MW while retaining the advantages of a fiber laser system of high average power with good beam quality.

  3. Two-color bright squeezed vacuum

    SciTech Connect

    Agafonov, Ivan N.; Chekhova, Maria V.

    2010-07-15

    In a strongly pumped nondegenerate traveling-wave optical parametric amplifier, we produce a two-color squeezed vacuum with up to millions of photons per pulse. Our approach to registering this macroscopic quantum state is direct detection of a large number of transverse and longitudinal modes, which is achieved by making the detection time and area much larger than the coherence time and area, respectively. Using this approach, we obtain a record value of twin-beam squeezing for direct detection of bright squeezed vacuum. This makes direct detection of macroscopic squeezed vacuum a practical tool for quantum information applications.

  4. Apparent brightness distribution of GRB host galaxies

    NASA Astrophysics Data System (ADS)

    Bagoly, Zsolt; Rácz, István I.; Balázs, Lajos G.; Horváth, István; Tóth, L. Viktor

    We studied the unbiased optical brightness distribution which was calculated from the survival analysis of host galaxies (HGs) data and its relationship with the Swift GRB data of the host galaxies observed by the Keck telescope. Based on the sample obtained from merging the Swift GRB table and the Keck optical data we also studied the dependence of this distribution on the GRB's data. Finally, we compared the HGs distribution with standard galaxies distribution of the DEEP2 redshift survey and checked the result with the VIPERS catalogue too.

  5. Rotation and macroturbulence in bright giants

    SciTech Connect

    Gray, D.F.; Toner, C.G.

    1986-11-01

    Spectral line profiles of 35 F, G, and K bright giants were analyzed to obtain rotation rates, v sin i, and macroturbulence dispersion. This sample indicates that rotation rates of cool class II giants is less than 11 km/s, in contrast with some recent periodicity measurements. Macroturbulence dispersion generally increases with effective temperature, but the range of values at a given effective temperature is much larger than seen for lower luminosity classes; this is interpreted in terms of red-giant and blue-loop evolution. No evidence is found for angular momentum dissipation on the first crossing of the H-R diagram. 57 references.

  6. Ultraviolet photofragmentation of biomolecular ions

    PubMed Central

    Reilly, James P.

    2009-01-01

    Mass spectrometric identification of all types of molecules relies on the observation and interpretation of ion fragmentation patterns. Peptides, proteins, carbohydrates and nucleic acids that are often found as components of complex biological samples represent particularly important challenges. The most common strategies for fragmenting biomolecular ions include low- and high-energy collisional activation, post-source decay, and electron capture or transfer dissociation. Each of these methods has its own idiosyncrasies and advantages but encounters problems with some types of samples. Novel fragmentation methods that can offer improvements are always desirable. One approach that has been under study for years but is not yet incorporated into a commercial instrument is ultraviolet photofragmentation. This review discusses experimental results on various biological molecules that have been generated by several research groups using different light wavelengths and mass analyzers. Work involving short-wavelength vacuum ultraviolet light is particularly emphasized. The characteristics of photofragmentation are examined and its advantages summarized. PMID:19241462

  7. International Ultraviolet Explorer Observatory operations

    NASA Technical Reports Server (NTRS)

    1985-01-01

    This volume contains the final report for the International Ultraviolet Explorer IUE Observatory Operations contract. The fundamental operational objective of the International Ultraviolet Explorer (IUE) program is to translate competitively selected observing programs into IUE observations, to reduce these observations into meaningful scientific data, and then to present these data to the Guest Observer in a form amenable to the pursuit of scientific research. The IUE Observatory is the key to this objective since it is the central control and support facility for all science operations functions within the IUE Project. In carrying out the operation of this facility, a number of complex functions were provided beginning with telescope scheduling and operation, proceeding to data processing, and ending with data distribution and scientific data analysis. In support of these critical-path functions, a number of other significant activities were also provided, including scientific instrument calibration, systems analysis, and software support. Routine activities have been summarized briefly whenever possible.

  8. Method for extreme ultraviolet lithography

    DOEpatents

    Felter, T. E.; Kubiak, G. D.

    2000-01-01

    A method of producing a patterned array of features, in particular, gate apertures, in the size range 0.4-0.05 .mu.m using projection lithography and extreme ultraviolet (EUV) radiation. A high energy laser beam is used to vaporize a target material in order to produce a plasma which in turn, produces extreme ultraviolet radiation of a characteristic wavelength of about 13 nm for lithographic applications. The radiation is transmitted by a series of reflective mirrors to a mask which bears the pattern to be printed. The demagnified focused mask pattern is, in turn, transmitted by means of appropriate optics and in a single exposure, to a substrate coated with photoresists designed to be transparent to EUV radiation and also satisfy conventional processing methods.

  9. Method for extreme ultraviolet lithography

    DOEpatents

    Felter, T. E.; Kubiak, Glenn D.

    1999-01-01

    A method of producing a patterned array of features, in particular, gate apertures, in the size range 0.4-0.05 .mu.m using projection lithography and extreme ultraviolet (EUV) radiation. A high energy laser beam is used to vaporize a target material in order to produce a plasma which in turn, produces extreme ultraviolet radiation of a characteristic wavelength of about 13 nm for lithographic applications. The radiation is transmitted by a series of reflective mirrors to a mask which bears the pattern to be printed. The demagnified focused mask pattern is, in turn, transmitted by means of appropriate optics and in a single exposure, to a substrate coated with photoresists designed to be transparent to EUV radiation and also satisfy conventional processing methods.

  10. Interstellar extinction in the ultraviolet

    NASA Technical Reports Server (NTRS)

    Bless, R. C.; Savage, B. D.

    1972-01-01

    Interstellar extinction curves over the region 3600-1100 A for 17 stars are presented. The observations were made by the two Wisconsin spectrometers onboard the OAO-2 with spectral resolutions of 10 A and 20 A. The extinction curves generally show a pronounced maximum at 2175 plus or minus 25 A, a broad minimum in the region 1800-1350 A, and finally a rapid rise to the far ultraviolet. Large extinction variations from star to star are found, especially in the far ultraviolet; however, with only two possible exceptions in this sample, the wavelength at the maximum of the extinction bump is essentially constant. These data are combined with visual and infrared observations to display the extinction behavior over a range in wavelength of about a factor of 20.

  11. Ultraviolet, optical and infrared astronomy

    NASA Astrophysics Data System (ADS)

    Wampler, E. J.

    1982-11-01

    The principal scientific currents in ultraviolet, optical, and infrared astronomy are discussed, with detailed descriptions of the major recommendations of the Panel on Ultraviolet, Optical and Infrared Astronomy of the National Academy of Sciences' Astronomy Survey Committee. The task of this panel was to survey progress and capabilities and to set priorities for new instrumentation in those branches of astronomy devoted to collecting and analyzing the information carried by cosmic photons with wavelengths between about 100 angstroms and 1 mm. It is pointed out that the best astronomical site in the U.S., the 14,000-foot-high summit of Mauna Kea, Hawaii, now has more square meters of telescope aperture operated by French, Canadian, and English groups than by U.S. groups. The panel named two instruments as major components of the programs for the 1980s. These are the Space Telescope and the Shuttle Infrared Telescope Facility.

  12. Ultraviolet-Resistant Bacterial Spores

    NASA Technical Reports Server (NTRS)

    Venkateswaran, Kasthuri; Newcombe, David; LaDuc, Myron T.; Osman, Shariff R.

    2007-01-01

    A document summarizes a study in which it was found that spores of the SAFR-032 strain of Bacillus pumilus can survive doses of ultraviolet (UV) radiation, radiation, and hydrogen peroxide in proportions much greater than those of other bacteria. The study was part of a continuing effort to understand the survivability of bacteria under harsh conditions and develop means of sterilizing spacecraft to prevent biocontamination of Mars that could interfere with the search for life there.

  13. Sublimation in bright spots on (1) Ceres

    NASA Astrophysics Data System (ADS)

    Nathues, A.; Hoffmann, M.; Schaefer, M.; Le Corre, L.; Reddy, V.; Platz, T.; Cloutis, E. A.; Christensen, U.; Kneissl, T.; Li, J.-Y.; Mengel, K.; Schmedemann, N.; Schaefer, T.; Russell, C. T.; Applin, D. M.; Buczkowski, D. L.; Izawa, M. R. M.; Keller, H. U.; O'Brien, D. P.; Pieters, C. M.; Raymond, C. A.; Ripken, J.; Schenk, P. M.; Schmidt, B. E.; Sierks, H.; Sykes, M. V.; Thangjam, G. S.; Vincent, J.-B.

    2015-12-01

    The dwarf planet (1) Ceres, the largest object in the main asteroid belt with a mean diameter of about 950 kilometres, is located at a mean distance from the Sun of about 2.8 astronomical units (one astronomical unit is the Earth-Sun distance). Thermal evolution models suggest that it is a differentiated body with potential geological activity. Unlike on the icy satellites of Jupiter and Saturn, where tidal forces are responsible for spewing briny water into space, no tidal forces are acting on Ceres. In the absence of such forces, most objects in the main asteroid belt are expected to be geologically inert. The recent discovery of water vapour absorption near Ceres and previous detection of bound water and OH near and on Ceres (refs 5, 6, 7) have raised interest in the possible presence of surface ice. Here we report the presence of localized bright areas on Ceres from an orbiting imager. These unusual areas are consistent with hydrated magnesium sulfates mixed with dark background material, although other compositions are possible. Of particular interest is a bright pit on the floor of crater Occator that exhibits probable sublimation of water ice, producing haze clouds inside the crater that appear and disappear with a diurnal rhythm. Slow-moving condensed-ice or dust particles may explain this haze. We conclude that Ceres must have accreted material from beyond the ‘snow line’, which is the distance from the Sun at which water molecules condense.

  14. Coronal Bright Points Associated with Minifilament Eruptions

    NASA Astrophysics Data System (ADS)

    Hong, Junchao; Jiang, Yunchun; Yang, Jiayan; Bi, Yi; Li, Haidong; Yang, Bo; Yang, Dan

    2014-12-01

    Coronal bright points (CBPs) are small-scale, long-lived coronal brightenings that always correspond to photospheric network magnetic features of opposite polarity. In this paper, we subjectively adopt 30 CBPs in a coronal hole to study their eruptive behavior using data from the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory. About one-quarter to one-third of the CBPs in the coronal hole go through one or more minifilament eruption(s) (MFE(s)) throughout their lifetimes. The MFEs occur in temporal association with the brightness maxima of CBPs and possibly result from the convergence and cancellation of underlying magnetic dipoles. Two examples of CBPs with MFEs are analyzed in detail, where minifilaments appear as dark features of a cool channel that divide the CBPs along the neutral lines of the dipoles beneath. The MFEs show the typical rising movements of filaments and mass ejections with brightenings at CBPs, similar to large-scale filament eruptions. Via differential emission measure analysis, it is found that CBPs are heated dramatically by their MFEs and the ejected plasmas in the MFEs have average temperatures close to the pre-eruption BP plasmas and electron densities typically near 109 cm-3. These new observational results indicate that CBPs are more complex in dynamical evolution and magnetic structure than previously thought.

  15. Coronal bright points associated with minifilament eruptions

    SciTech Connect

    Hong, Junchao; Jiang, Yunchun; Yang, Jiayan; Bi, Yi; Li, Haidong; Yang, Bo; Yang, Dan

    2014-12-01

    Coronal bright points (CBPs) are small-scale, long-lived coronal brightenings that always correspond to photospheric network magnetic features of opposite polarity. In this paper, we subjectively adopt 30 CBPs in a coronal hole to study their eruptive behavior using data from the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory. About one-quarter to one-third of the CBPs in the coronal hole go through one or more minifilament eruption(s) (MFE(s)) throughout their lifetimes. The MFEs occur in temporal association with the brightness maxima of CBPs and possibly result from the convergence and cancellation of underlying magnetic dipoles. Two examples of CBPs with MFEs are analyzed in detail, where minifilaments appear as dark features of a cool channel that divide the CBPs along the neutral lines of the dipoles beneath. The MFEs show the typical rising movements of filaments and mass ejections with brightenings at CBPs, similar to large-scale filament eruptions. Via differential emission measure analysis, it is found that CBPs are heated dramatically by their MFEs and the ejected plasmas in the MFEs have average temperatures close to the pre-eruption BP plasmas and electron densities typically near 10{sup 9} cm{sup –3}. These new observational results indicate that CBPs are more complex in dynamical evolution and magnetic structure than previously thought.

  16. At Bright Band Inside Victoria Crater

    NASA Technical Reports Server (NTRS)

    2007-01-01

    A layer of light-toned rock exposed inside Victoria Crater in the Meridiani Planum region of Mars appears to mark where the surface was at the time, many millions of years ago, when an impact excavated the crater. NASA's Mars Exploration Rover Opportunity drove to this bright band as the science team's first destination for the rover during investigations inside the crater.

    Opportunity's left front hazard-identification camera took this image just after the rover finished a drive of 2.25 meters (7 feet, 5 inches) during the rover's 1,305th Martian day, or sol, (Sept. 25, 2007). The rocks beneath the rover and its extended robotic arm are part of the bright band.

    Victoria Crater has a scalloped shape of alternating alcoves and promontories around the crater's circumference. Opportunity descended into the crater two weeks earlier, within an alcove called 'Duck Bay.' Counterclockwise around the rim, just to the right of the arm in this image, is a promontory called 'Cabo Frio.'

  17. Sublimation in bright spots on (1) Ceres.

    PubMed

    Nathues, A; Hoffmann, M; Schaefer, M; Le Corre, L; Reddy, V; Platz, T; Cloutis, E A; Christensen, U; Kneissl, T; Li, J-Y; Mengel, K; Schmedemann, N; Schaefer, T; Russell, C T; Applin, D M; Buczkowski, D L; Izawa, M R M; Keller, H U; O'Brien, D P; Pieters, C M; Raymond, C A; Ripken, J; Schenk, P M; Schmidt, B E; Sierks, H; Sykes, M V; Thangjam, G S; Vincent, J-B

    2015-12-10

    The dwarf planet (1) Ceres, the largest object in the main asteroid belt with a mean diameter of about 950 kilometres, is located at a mean distance from the Sun of about 2.8 astronomical units (one astronomical unit is the Earth-Sun distance). Thermal evolution models suggest that it is a differentiated body with potential geological activity. Unlike on the icy satellites of Jupiter and Saturn, where tidal forces are responsible for spewing briny water into space, no tidal forces are acting on Ceres. In the absence of such forces, most objects in the main asteroid belt are expected to be geologically inert. The recent discovery of water vapour absorption near Ceres and previous detection of bound water and OH near and on Ceres (refs 5-7) have raised interest in the possible presence of surface ice. Here we report the presence of localized bright areas on Ceres from an orbiting imager. These unusual areas are consistent with hydrated magnesium sulfates mixed with dark background material, although other compositions are possible. Of particular interest is a bright pit on the floor of crater Occator that exhibits probable sublimation of water ice, producing haze clouds inside the crater that appear and disappear with a diurnal rhythm. Slow-moving condensed-ice or dust particles may explain this haze. We conclude that Ceres must have accreted material from beyond the 'snow line', which is the distance from the Sun at which water molecules condense.

  18. A high brightness field emission display

    SciTech Connect

    Palevsky, A.

    1996-12-31

    The military requirement for avionics display performance requires that displays be legible with 10,000 foot-candles (fc) bright light shining into the pilot`s eyes, or 10,000 fc shining directly on the display. The contrast ratio under these conditions must be at least 4.66:1. In addition, instant-on operation is sought for temperatures as low as {minus}54 C. Currently these specifications can barely be met by monochrome CRTs whose use is counter-indicated by other factors. No color display can achieve optimum performance in the areas mentioned, nor do any current contenders, primarily AMLCD`s, have any prospects of achieving full compliance. The FED being developed by Raytheon shows strong promise of being able to achieve the brightness and contrast ratios desired. The FED is also inherently able to provide instant-on functionality at any terrestrial temperature and does not require any heating at low temperatures. The technical objective of the Raytheon development program is to develop a high performance, full color, FED Panel that meets the performance and environmental operating condition requirements specified for military and other high performance display applications.

  19. Synchrotron brightness distribution of turbulent radio jets

    NASA Technical Reports Server (NTRS)

    Henriksen, R. N.; Bridle, A. H.; Chan, K. L.

    1981-01-01

    Radio jets are considered as turbulent mixing regions and it is proposed that the essential small scale viscous dissipation in these jets is by emission of MHD waves and by their subsequent strong damping due, at least partly, to gyro-resonant acceleration of supra-thermal particles. A formula relating the synchrotron surface brightness of a radio jet to the turbulent power input is deduced from physical postulates, and is tested against the data for NGC315 and 3C31 (NGC383). The predicted brightness depends essentially on the collimation behavior of the jet, and, to a lesser extent, on the CH picture of a 'high' nozzle with accelerating flow. The conditions for forming a large scale jet at a high nozzle from a much smaller scale jet are discussed. The effect of entrainment on the prediction is discussed with the use of similarity solutions. Although entrainment is inevitably associated with the turbulent jet, it may or may not be a dominant factor depending on the ambient density profile.

  20. Hubble Space Telescope faint object spectrograph Quasar Absorption System Snapshot Survey (AbSnap). 1: Astrometric optical positions and finding charts of 269 bright QSO

    NASA Technical Reports Server (NTRS)

    Bowen, David V.; Osmer, Samantha J.; Blades, J. Chris; Tytler, David; Cottrell, Lance; Fan, Xiao-Ming; Lanzetta, Kenneth M.

    1994-01-01

    We present finding charts and optical positions accurate to less than 1 arcsec for 269 bright (V less than or = 18.5) Quasi-Stellar Objects (QSOs). These objects were selected as candidates for the Hubble Space Telescope (HST) Quasar Absorption System Snapshot Survey (AbSnap), a program designed to use the Faint Object Spectrograph (FOS) to obtain short exposure ultraviolet (UV) spectra of bright QSOs. Many quasars were included because of their proximity to bright, low redshift galaxies and positions of these QSOs are measured accurately for the first time. Data were obtained using the digitized sky survey produced by the Space Telescope Science Institute's Guide Stars Selection System Astrometric Support Program.

  1. Bright hot impacts by erupted fragments falling back on the Sun: a template for stellar accretion.

    PubMed

    Reale, Fabio; Orlando, Salvatore; Testa, Paola; Peres, Giovanni; Landi, Enrico; Schrijver, Carolus J

    2013-07-19

    Impacts of falling fragments observed after the eruption of a filament in a solar flare on 7 June 2011 are similar to those inferred for accretion flows on young stellar objects. As imaged in the ultraviolet (UV)-extreme UV range by the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory, many impacts of dark, dense matter display uncommonly intense, compact brightenings. High-resolution hydrodynamic simulations show that such bright spots, with plasma temperatures increasing from ~10(4) to ~10(6) kelvin, occur when high-density plasma (>10(10) particles per cubic centimeter) hits the solar surface at several hundred kilometers per second, producing high-energy emission as in stellar accretion. The high-energy emission comes from the original fragment material and is heavily absorbed by optically thick plasma, possibly explaining the lower mass accretion rates inferred from x-rays relative to UV-optical-near infrared observations of young stars.

  2. EUV light source with high brightness at 13.5 nm

    NASA Astrophysics Data System (ADS)

    Borisov, V. M.; Koshelev, K. N.; Prokof'ev, A. V.; Khadzhiyskiy, F. Yu; Khristoforov, O. B.

    2014-11-01

    The results of the studies on the development of a highbrightness radiation source in the extreme ultraviolet (EUV) range are presented. The source is intended for using in projection EUV lithography, EUV mask inspection, for the EUV metrology, etc. Novel approaches to creating a light source on the basis of Z-pinch in xenon allowed the maximal brightness [130 W(mm2 sr)-1] to be achieved in the vicinity of plasma for this type of radiation sources within the 2% spectral band centred at the wavelength of 13.5 nm that corresponds to the maximal reflection of multilayer Mo/Si mirrors. In this spectral band the radiation power achieves 190 W in the solid angle of 2π at a pulse repetition rate of 1.9 kHz and an electric power of 20 kW, injected into the discharge.

  3. EUV light source with high brightness at 13.5 nm

    SciTech Connect

    Borisov, V M; Prokof'ev, A V; Khristoforov, O B; Koshelev, K N; Khadzhiyskiy, F Yu

    2014-11-30

    The results of the studies on the development of a highbrightness radiation source in the extreme ultraviolet (EUV) range are presented. The source is intended for using in projection EUV lithography, EUV mask inspection, for the EUV metrology, etc. Novel approaches to creating a light source on the basis of Z-pinch in xenon allowed the maximal brightness [130 W(mm{sup 2} sr){sup -1}] to be achieved in the vicinity of plasma for this type of radiation sources within the 2% spectral band centred at the wavelength of 13.5 nm that corresponds to the maximal reflection of multilayer Mo/Si mirrors. In this spectral band the radiation power achieves 190 W in the solid angle of 2π at a pulse repetition rate of 1.9 kHz and an electric power of 20 kW, injected into the discharge. (laser applications and other topics in quantum electronics)

  4. Does Stevens's Power Law for Brightness Extend to Perceptual Brightness Averaging?

    ERIC Educational Resources Information Center

    Bauer, Ben

    2009-01-01

    Stevens's power law ([Psi][infinity][Phi][beta]) captures the relationship between physical ([Phi]) and perceived ([Psi]) magnitude for many stimulus continua (e.g., luminance and brightness, weight and heaviness, area and size). The exponent ([beta]) indicates whether perceptual magnitude grows more slowly than physical magnitude ([beta] less…

  5. Solving the Brightness-from-Luminance Problem: A Neural Architecture for Invariant Brightness Perception

    DTIC Science & Technology

    1989-02-01

    lightness. Behavioral and Brain Sciences, 6, 625-692. Grossberg, S. (1987a). Cortical dynamics of three-dimensional form , color , and brightness...perception, I: Monocular theory. Perception and Psychophysics, 41, 87-116. Grossberg, S. (1987b). Cortical dynamics of three-dimensional form , color , and

  6. Larger Planet Radii Inferred from Stellar "Flicker" Brightness Variations of Bright Planet-host Stars

    NASA Astrophysics Data System (ADS)

    Bastien, Fabienne A.; Stassun, Keivan G.; Pepper, Joshua

    2014-06-01

    Most extrasolar planets have been detected by their influence on their parent star, typically either gravitationally (the Doppler method) or by the small dip in brightness as the planet blocks a portion of the star (the transit method). Therefore, the accuracy with which we know the masses and radii of extrasolar planets depends directly on how well we know those of the stars, the latter usually determined from the measured stellar surface gravity, log g. Recent work has demonstrated that the short-timescale brightness variations ("flicker") of stars can be used to measure log g to a high accuracy of ~0.1-0.2 dex. Here, we use flicker measurements of 289 bright (Kepmag < 13) candidate planet-hosting stars with T eff = 4500-6650 K to re-assess the stellar parameters and determine the resulting impact on derived planet properties. This re-assessment reveals that for the brightest planet-host stars, Malmquist bias contaminates the stellar sample with evolved stars: nearly 50% of the bright planet-host stars are subgiants. As a result, the stellar radii, and hence the radii of the planets orbiting these stars, are on average 20%-30% larger than previous measurements had suggested.

  7. LARGER PLANET RADII INFERRED FROM STELLAR ''FLICKER'' BRIGHTNESS VARIATIONS OF BRIGHT PLANET-HOST STARS

    SciTech Connect

    Bastien, Fabienne A.; Stassun, Keivan G.; Pepper, Joshua

    2014-06-10

    Most extrasolar planets have been detected by their influence on their parent star, typically either gravitationally (the Doppler method) or by the small dip in brightness as the planet blocks a portion of the star (the transit method). Therefore, the accuracy with which we know the masses and radii of extrasolar planets depends directly on how well we know those of the stars, the latter usually determined from the measured stellar surface gravity, log g. Recent work has demonstrated that the short-timescale brightness variations ({sup f}licker{sup )} of stars can be used to measure log g to a high accuracy of ∼0.1-0.2 dex. Here, we use flicker measurements of 289 bright (Kepmag < 13) candidate planet-hosting stars with T {sub eff} = 4500-6650 K to re-assess the stellar parameters and determine the resulting impact on derived planet properties. This re-assessment reveals that for the brightest planet-host stars, Malmquist bias contaminates the stellar sample with evolved stars: nearly 50% of the bright planet-host stars are subgiants. As a result, the stellar radii, and hence the radii of the planets orbiting these stars, are on average 20%-30% larger than previous measurements had suggested.

  8. NO TIME FOR DEAD TIME: TIMING ANALYSIS OF BRIGHT BLACK HOLE BINARIES WITH NuSTAR

    SciTech Connect

    Bachetti, Matteo; Barret, Didier; Harrison, Fiona A.; Cook, Rick; Grefenstette, Brian W.; Fürst, Felix; Tomsick, John; Boggs, Steven E.; Craig, William W.; Schmid, Christian; Christensen, Finn E.; Fabian, Andrew C.; Kara, Erin; Gandhi, Poshak; Hailey, Charles J.; Maccarone, Thomas J.; Miller, Jon M.; Pottschmidt, Katja; Stern, Daniel; Uttley, Phil; and others

    2015-02-20

    Timing of high-count-rate sources with the NuSTAR Small Explorer Mission requires specialized analysis techniques. NuSTAR was primarily designed for spectroscopic observations of sources with relatively low count rates rather than for timing analysis of bright objects. The instrumental dead time per event is relatively long (∼2.5 msec) and varies event-to-event by a few percent. The most obvious effect is a distortion of the white noise level in the power density spectrum (PDS) that cannot be easily modeled with standard techniques due to the variable nature of the dead time. In this paper, we show that it is possible to exploit the presence of two completely independent focal planes and use the cospectrum, the real part of the cross PDS, to obtain a good proxy of the white-noise-subtracted PDS. Thereafter, one can use a Monte Carlo approach to estimate the remaining effects of dead time, namely, a frequency-dependent modulation of the variance and a frequency-independent drop of the sensitivity to variability. In this way, most of the standard timing analysis can be performed, albeit with a sacrifice in signal-to-noise ratio relative to what would be achieved using more standard techniques. We apply this technique to NuSTAR observations of the black hole binaries GX 339–4, Cyg X-1, and GRS 1915+105.

  9. No Time for Dead Time: Timing Analysis of Bright Black Hole Binaries with NuSTAR

    NASA Astrophysics Data System (ADS)

    Bachetti, Matteo; Harrison, Fiona A.; Cook, Rick; Tomsick, John; Schmid, Christian; Grefenstette, Brian W.; Barret, Didier; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Fabian, Andrew C.; Fürst, Felix; Gandhi, Poshak; Hailey, Charles J.; Kara, Erin; Maccarone, Thomas J.; Miller, Jon M.; Pottschmidt, Katja; Stern, Daniel; Uttley, Phil; Walton, Dominic J.; Wilms, Jörn; Zhang, William W.

    2015-02-01

    Timing of high-count-rate sources with the NuSTAR Small Explorer Mission requires specialized analysis techniques. NuSTAR was primarily designed for spectroscopic observations of sources with relatively low count rates rather than for timing analysis of bright objects. The instrumental dead time per event is relatively long (~2.5 msec) and varies event-to-event by a few percent. The most obvious effect is a distortion of the white noise level in the power density spectrum (PDS) that cannot be easily modeled with standard techniques due to the variable nature of the dead time. In this paper, we show that it is possible to exploit the presence of two completely independent focal planes and use the cospectrum, the real part of the cross PDS, to obtain a good proxy of the white-noise-subtracted PDS. Thereafter, one can use a Monte Carlo approach to estimate the remaining effects of dead time, namely, a frequency-dependent modulation of the variance and a frequency-independent drop of the sensitivity to variability. In this way, most of the standard timing analysis can be performed, albeit with a sacrifice in signal-to-noise ratio relative to what would be achieved using more standard techniques. We apply this technique to NuSTAR observations of the black hole binaries GX 339-4, Cyg X-1, and GRS 1915+105.

  10. Far ultraviolet astronomy using the FAUST telescope

    NASA Technical Reports Server (NTRS)

    Bowyer, C. S.

    1981-01-01

    The Far Ultraviolet Space Telescope (FAUST) a compact, wide field-of-view, far ultraviolet instrument designed for astronomical observations of extended and point sources is discussed. The design and application of the instrument are described. The prime objective is to observe faint astronomical sources with sensitivities higher than previously available. Scientific programs will include: (1) a search for ultraviolet stars which are predicted to exist at the stage of evolution prior to the final death of a star; (2) observations of galaxies and quasars; and (3) joint programs with other Spacelab 1 experiments. The secondary objective is to verify the suitability of the Spacelab as a platform for far ultraviolet astronomy: data will be provided on the ultraviolet background levels due to astronomical, terrestrial, and spacecraft generated sources; the levels of contaminants which affect ultraviolet instruments; and the capability of the Orbiter for stable pointing at celestial sources for useful periods of time.

  11. Infrared Sky Brightness Monitors for Antarctica

    NASA Astrophysics Data System (ADS)

    Storey, J. W. V.; Ashley, M. C. B.; Boccas, M.; Phillips, M. A.; Schinckel, A. E. T.

    1999-06-01

    Two sky brightness monitors-one for the near-infrared and one for the mid-infrared-have been developed for site survey work in Antarctica. The instruments, which we refer to as the NISM (Near-Infrared Sky Monitor) and the MISM (Mid-Infrared Sky Monitor), are part of a suite of instruments being deployed in the Automated Astrophysical Site-Testing Observatory (AASTO). The chief design constraints include reliable, autonomous operation, low power consumption, and of course the ability to operate under conditions of extreme cold. The instruments are currently operational at the Amundsen-Scott South Pole Station, prior to deployment at remote, unattended sites on the high antarctic plateau.

  12. Extinction and Sky Brightness at Dome C

    NASA Astrophysics Data System (ADS)

    Faurobert, M.; Arnaud, J.; Vernisse, Y.

    2012-06-01

    We have installed a small telescope to monitor the sky brightness around the sun at the French-Italian station Concordia at Dome C in Antarctica. Previous campaigns have been performed with the same instrument at Haleakala in Hawai and Sunspot in New Mexico. We compare here the results of the first year of the campaign at Dome C (2008) to the purest sky observed at Haleakala. We show that Dome C is an outstanding site for coronal observations. Compared to Haleaka, it appears to be more transparent, and to contain less aerosols. Its water vapour content is also significantly smaller. These results still have to be confirmed by the analysis of the 2009 and 2010 data.

  13. Dark Skies, Bright Kids Year 7

    NASA Astrophysics Data System (ADS)

    Bittle, Lauren E.; Johnson, Kelsey E.; Borish, H. Jacob; Burkhardt, Andrew; Firebaugh, Ariel; Hancock, Danielle; Rochford Hayes, Christian; Linden, Sean; Liss, Sandra; Matthews, Allison; Prager, Brian; Pryal, Matthew; Sokal, Kimberly R.; Troup, Nicholas William; Wenger, Trey

    2016-01-01

    We present updates from our seventh year of operation including new club content, continued assessments, and our fifth annual Star Party. Dark Skies, Bright Kids (DSBK) is an entirely volunteer-run outreach organization based out of the Department of Astronomy at the University of Virginia. Our core mission is to enhance elementary science education and literacy in Central Virginia through fun, hands-on activities that introduce basic Astronomy concepts. Our primary focus is hosting an 8-10 week after-school astronomy club at underserved elementary and middle schools. Each week, DSBK volunteers take the role of coaches to introduce astronomy-related concepts ranging from the Solar System to galaxies to astrobiology, and to lead students in interactive learning activities. Another hallmark of DSBK is hosting our Annual Central Virginia Star Party, a free event open to the community featuring star-gazing and planetarium shows.

  14. Dark Skies, Bright Kids Year 8

    NASA Astrophysics Data System (ADS)

    Bittle, Lauren E.; Wenger, Trey; Johnson, Kelsey E.; Angell, Dylan; Burkhardt, Andrew; Davis, Blair; Firebaugh, Ariel; Hancock, Danielle; Richardson, Whitney; Rochford Hayes, Christian; Linden, Sean; Liss, Sandra; Matthews, Allison; McNair, Shunlante; Prager, Brian; Pryal, Matthew; Troup, Nicholas William

    2017-01-01

    We present activities from the eighth year of Dark Skies Bright Kids (DSBK), an entirely volunteer-run outreach organization based out of the Department of Astronomy at the University of Virginia. Our core mission is to enhance elementary science education and literacy in Central Virginia through fun, hands-on activities that introduce basic Astronomy concepts. Over the past seven years, our primary focus has been hosting an 8-10 week after-school astronomy club at underserved elementary and middle schools, and over the past several years, we have partnered with local businesses to host our Annual Central Virginia Star Party, a free event open to the community featuring star-gazing and planetarium shows. This past summer we expanded our reach through a new initiative to bring week-long summer day camps to south and southwest Virginia, home to some of the most underserved communities in the commonwealth.

  15. High brightness angled cavity quantum cascade lasers

    SciTech Connect

    Heydari, D.; Bai, Y.; Bandyopadhyay, N.; Slivken, S.; Razeghi, M.

    2015-03-02

    A quantum cascade laser (QCL) with an output power of 203 W is demonstrated in pulsed mode at 283 K with an angled cavity. The device has a ridge width of 300 μm, a cavity length of 5.8 mm, and a tilt angle of 12°. The back facet is high reflection coated, and the front facet is anti-reflection coated. The emitting wavelength is around 4.8 μm. In distinct contrast to a straight cavity broad area QCL, the lateral far field is single lobed with a divergence angle of only 3°. An ultrahigh brightness value of 156 MW cm{sup −2 }sr{sup −1} is obtained, which marks the brightest QCL to date.

  16. Visualizing individual microtubules by bright field microscopy

    NASA Astrophysics Data System (ADS)

    Gutiérrez-Medina, Braulio; Block, Steven M.

    2010-11-01

    Microtubules are slender (˜25 nm diameter), filamentous polymers involved in cellular structure and organization. Individual microtubules have been visualized via fluorescence imaging of dye-labeled tubulin subunits and by video-enhanced, differential interference-contrast microscopy of unlabeled polymers using sensitive CCD cameras. We demonstrate the imaging of unstained microtubules using a microscope with conventional bright field optics in conjunction with a webcam-type camera and a light-emitting diode illuminator. The light scattered by microtubules is image-processed to remove the background, reduce noise, and enhance contrast. The setup is based on a commercial microscope with a minimal set of inexpensive components, suitable for implementation in a student laboratory. We show how this approach can be used in a demonstration motility assay, tracking the gliding motions of microtubules driven by the motor protein kinesin.

  17. High brightness angled cavity quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Heydari, D.; Bai, Y.; Bandyopadhyay, N.; Slivken, S.; Razeghi, M.

    2015-03-01

    A quantum cascade laser (QCL) with an output power of 203 W is demonstrated in pulsed mode at 283 K with an angled cavity. The device has a ridge width of 300 μm, a cavity length of 5.8 mm, and a tilt angle of 12°. The back facet is high reflection coated, and the front facet is anti-reflection coated. The emitting wavelength is around 4.8 μm. In distinct contrast to a straight cavity broad area QCL, the lateral far field is single lobed with a divergence angle of only 3°. An ultrahigh brightness value of 156 MW cm-2 sr-1 is obtained, which marks the brightest QCL to date.

  18. Bright Solitonic Matter-Wave Interferometer

    NASA Astrophysics Data System (ADS)

    McDonald, G. D.; Kuhn, C. C. N.; Hardman, K. S.; Bennetts, S.; Everitt, P. J.; Altin, P. A.; Debs, J. E.; Close, J. D.; Robins, N. P.

    2014-07-01

    We present the first realization of a solitonic atom interferometer. A Bose-Einstein condensate of 1×104 atoms of rubidium-85 is loaded into a horizontal optical waveguide. Through the use of a Feshbach resonance, the s-wave scattering length of the Rb85 atoms is tuned to a small negative value. This attractive atomic interaction then balances the inherent matter-wave dispersion, creating a bright solitonic matter wave. A Mach-Zehnder interferometer is constructed by driving Bragg transitions with the use of an optical lattice colinear with the waveguide. Matter-wave propagation and interferometric fringe visibility are compared across a range of s-wave scattering values including repulsive, attractive and noninteracting values. The solitonic matter wave is found to significantly increase fringe visibility even compared with a noninteracting cloud.

  19. Modelling Solar and Stellar Brightness Variabilities

    NASA Astrophysics Data System (ADS)

    Yeo, K. L.; Shapiro, A. I.; Krivova, N. A.; Solanki, S. K.

    2016-04-01

    Total and spectral solar irradiance, TSI and SSI, have been measured from space since 1978. This is accompanied by the development of models aimed at replicating the observed variability by relating it to solar surface magnetism. Despite significant progress, there remains persisting controversy over the secular change and the wavelength-dependence of the variation with impact on our understanding of the Sun's influence on the Earth's climate. We highlight the recent progress in TSI and SSI modelling with SATIRE. Brightness variations have also been observed for Sun-like stars. Their analysis can profit from knowledge of the solar case and provide additional constraints for solar modelling. We discuss the recent effort to extend SATIRE to Sun-like stars.

  20. The GPM Common Calibrated Brightness Temperature Product

    NASA Technical Reports Server (NTRS)

    Stout, John; Berg, Wesley; Huffman, George; Kummerow, Chris; Stocker, Erich

    2005-01-01

    The Global Precipitation Measurement (GPM) project will provide a core satellite carrying the GPM Microwave Imager (GMI) and will use microwave observations from a constellation of other satellites. Each partner with a satellite in the constellation will have a calibration that meets their own requirements and will decide on the format to archive their brightness temperature (Tb) record in GPM. However, GPM multi-sensor precipitation algorithms need to input intercalibrated Tb's in order to avoid differences among sensors introducing artifacts into the longer term climate record of precipitation. The GPM Common Calibrated Brightness Temperature Product is intended to address this problem by providing intercalibrated Tb data, called "Tc" data, where the "c" stands for common. The precipitation algorithms require a Tc file format that is both generic and flexible enough to accommodate the different passive microwave instruments. The format will provide detailed information on the processing history in order to allow future researchers to have a record of what was done. The format will be simple, including the main items of scan time, latitude, longitude, and Tc. It will also provide spacecraft orientation, spacecraft location, orbit, and instrument scan type (cross-track or conical). Another simplification is to store data in real numbers, avoiding the ambiguity of scaled data. Finally, units and descriptions will be provided in the product. The format is built on the concept of a swath, which is a series of scans that have common geolocation and common scan geometry. Scan geometry includes pixels per scan, sensor orientation, scan type, and incidence angles. The Tc algorithm and data format are being tested using the pre-GPM Precipitation Processing System (PPS) software to generate formats and 1/0 routines. In the test, data from SSM/I, TMI, AMSR-E, and WindSat are being processed and written as Tc products.

  1. Ultraviolet light and hyperpigmentation in healing wounds

    SciTech Connect

    Wiemer, D.R.; Spira, M.

    1983-10-01

    The concept of permanent hyperpigmentation in wounds following ultraviolet light exposure during the postoperative period has found a place in plastic surgical literature but has not been documented. This study evaluates the effect of ultraviolet light on healing wounds in paraplegics. It failed to confirm permanent alteration in pigmentation response to ultraviolet exposure and suggests that other factors are of greater importance in the development of hyperpigmentation in the healing wound.

  2. Polymerizable ultraviolet stabilizers for outdoor use

    NASA Technical Reports Server (NTRS)

    Vogl, O.

    1982-01-01

    Polymeric materials that are stable enough to use outdoors without changes in excess of 20 years are investigated. Ultraviolet stabilizers or plastic materials were synthesized, polymerizable ultraviolet stabilizers, particularly of the 2(2-hydroxyphenyl)2H-benzotriazole family were prepared their polymerization, copolymerization and grafting onto other polymers were demonstrated, and ultraviolet stabilizing systems were devised. These materials were evaluated from the photophysical point of view.

  3. Photospheric electric current and transition region brightness within an active region

    NASA Technical Reports Server (NTRS)

    Deloach, A. C.; Hagyard, M. J.; Rabin, D.; Moore, R. L.; Smith, B. J., Jr.; West, E. A.; Tandberg-Hanssen, E.

    1984-01-01

    Distributions of vertical electrical current density J(z) calculated from vector measurements of the photospheric magnetic field are compared with ultraviolet spectroheliograms to investigate whether resistive heating is an important source of enhanced emission in the transition region. The photospheric magnetic fields in Active Region 2372 were measured on April 6 and 7, 1980 with the Marshall Space Flight Center vector magnetograph; ultraviolet wavelength spectroheliograms (L-alpha and N V 1239 A) were obtained with the UV Spectrometer and Polarimeter experiment aboard the Solar Maximum Mission satellite. Spatial registration of the J(z) (5 arcsec resolution) and UV (3 arcsec resolution) maps indicates that the maximum current density is cospatial with a minor but persistent UV enhancement, but there is little detected current associated with other nearby bright areas. It is concluded that, although resistive heating may be important in the transition region, the currents responsible for the heating are largely unresolved in the present measurements and have no simple correlation with the residual current measured on 5-arcsec scales.

  4. Formation of a Bright Polar Hood over the Summer North Pole of Saturn in 2016

    NASA Astrophysics Data System (ADS)

    Sayanagi, Kunio M.; Blalock, John J.; Ingersoll, Andrew P.; Dyudina, Ulyana A.; Ewald, Shawn P.

    2016-10-01

    We report that a bright polar hood has formed over the north pole of Saturn, seen first in images captured by the Cassini ISS camera in 2016. When the north pole was observed during the previous period of Cassini spacecraft's high-inclination orbits in 2012-2013, the concentration of light-scattering aerosols within 2-degree latitude of the north pole appeared to be less than that of the surrounding region, and appeared as a dark hole in all ISS filters, in particular in the shorter wavelength filters BL1 (460 nm), and VIO (420 nm). The north pole's appearance in 2012 was in contrast to that of the south pole in 2007, when the south pole had a bright polar hood in those short wavelengths; the south pole appeared dark in all other ISS filters in 2007. The difference between the south pole in 2007 and the north pole in 2012 was interpreted to be seasonal; in 2007, Saturn was approaching the equinox of 2009 and the south pole had been continuously illuminated since the previous equinox in 1995. In 2012, the north pole had been illuminated for only ~3 years after the long winter polar night. The bright hood over the summer south pole in 2007 was hypothesized to consist of aerosols produced by ultraviolet photodissociation of hydrocarbon molecules. Fletcher et al (2015) predicted that a similar bright hood should form over the north pole as Saturn approaches the 2017 solstice. In 2016, the Cassini spacecraft raised its orbital inclination again in preparation for its Grande Finale phase of the mission, from where it has a good view of the north pole. New images captured in 2016 show that the north pole has developed a bright polar hood. We present new images of the north polar region captured in 2016 that show the north pole, and other seasonally evolving high-latitude features including the northern hexagon. Our research has been supported by the Cassini Project, NASA grants OPR NNX11AM45G, CDAPS NNX15AD33G PATM NNX14AK07G, and NSF grant AAG 1212216.

  5. Upper limits for a lunar dust exosphere from far-ultraviolet spectroscopy by LRO/LAMP

    NASA Astrophysics Data System (ADS)

    Feldman, Paul D.; Glenar, David A.; Stubbs, Timothy J.; Retherford, Kurt D.; Randall Gladstone, G.; Miles, Paul F.; Greathouse, Thomas K.; Kaufmann, David E.; Parker, Joel Wm.; Alan Stern, S.

    2014-05-01

    Since early 2012, the Lyman-Alpha Mapping Project (LAMP) far-ultraviolet spectrograph on the Lunar Reconnaissance Orbiter (LRO) spacecraft has carried out a series of limb observations from within lunar shadow to search for the presence of a high altitude dust exosphere via forward-scattering of sunlight from dust grains. Bright “horizon-glow” was observed from orbit during several Apollo missions and interpreted in terms of dust at altitudes of several km and higher. However, no confirmation of such an exosphere has been made since that time. This raises basic questions about the source(s) of excess brightness in the early measurements and also the conditions for producing observable dust concentrations at km altitudes and higher. Far-ultraviolet measurements between 170 and 190 nm, near the LAMP long wavelength cutoff, are especially sensitive to scattering by small (0.1-0.2 μm radius) dust grains, since the scattering cross-section is near-maximum, and the solar flux is rising rapidly with wavelength. An additional advantage of ultraviolet measurements is the lack of interference by background zodiacal light which must be taken into account at longer wavelengths. As of July 2013, LAMP has completed several limb-observing sequences dedicated to the search for horizon glow, but no clear evidence of dust scattering has yet been obtained. Upper limits for vertical dust column abundance have been estimated at less than 10 grains cm-2 (0.1 μm grain radius), by comparing the measured noise-equivalent brightness with the results of Mie scattering simulations for the same observing geometries. These results indicate that Lunar Atmosphere Dust Environment Explorer (LADEE) UVS lunar dust observations will be considerably more challenging than planned.

  6. An ultraviolet-visible investigation of the globular cluster NGC 1851

    NASA Technical Reports Server (NTRS)

    Parise, Ronald A.; Maran, Stephen P.; Landsman, Wayne B.; Bohlin, Ralph C.; Cheng, Kwang-Ping; Greason, Michael R.; Hintzen, Paul M. N.; O'Connell, Robert W.; Roberts, Morton S.; Smith, Andrew M.

    1994-01-01

    Two-color ultraviolet images of the globular cluster NGC 1851 were obtained with the Ultraviolet Imaging Telescope (UIT) during the 1990 December Astro-1 Spacelab mission. A total of 133 stars are detected at 2490 A and 74 stars at 1520 A. An ultraviolet color-magnitude diagram based on the 46 well-photometered stars that appear in both images is presented. Thirty-nine of the 45 horizontal branch (HB) stars fall below the zero-age horizontal branch (ZAHB) of Z = 0.001 and Y = 0.23 predicted by Sweigart by as much as 0.6 mag if the interstellar reddening to the cluster is E(B - V) = 0.02. Supporting ground-based V and B observations, however, show excellent correlation with the same model ZAHB. A newly detected hot subdwarf star with T(sub eff) is approximately 26,000 K appears to be an extreme horizontal branch star. The measured flux for this star also falls approximately 0.6 mag below the position on the color-magnitude diagrams (CMD) predicted by parameters derived from ground-based spectroscopy by Landsman. The far-ultraviolet image is dominated by the ultraviolet-bright member star UV 5, which contributes 30% of the total flux at 1520 A. The UIT photometry is consistent with the classification of UV 5 as a post-asymptotic giant branch (PAGB) star. To a limit of 16.5 mag at 1520 A we find no ultraviolet counterpart within 6 minutes of the position of the X-ray source MX 0513-40.

  7. Influence of the crustal magnetic field on the Mars aurora electron flux and UV brightness

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    Observations with the SPICAM instrument on board Mars Express have shown the occasional presence of localized ultraviolet nightside emissions associated with enhanced energetic electron fluxes. These features generally occur in regions with significant radial crustal magnetic field. We use a Monte-Carlo electron transport model to investigate the role of the magnetic field on the downward and upward electron fluxes, the brightness and the emitted power of auroral emissions. Simulations based on an ASPERA-3 measured auroral electron precipitation indicate that magnetic mirroring leads to an intensification of the energy flux carried by upward moving electrons- from about 20% in the absence of crustal magnetic field up to 33-78% when magnetic field is included depending on magnetic field topology. Conservation of the particle flux in a flux tube implies that the presence of the B-field does not appreciably modify the emission rate profiles for an initially isotropic pitch angle distribution. However, we find that crustal magnetic field results in increase of the upward electron flux, and, consequently, in reduction of the total auroral brightness for given energy flux of precipitating electrons.

  8. Multiwavelength study of nearly face-on low surface brightness disk galaxies

    NASA Astrophysics Data System (ADS)

    Gao, Dong; Liang, Yan-Chun; Liu, Shun-Fang; Zhong, Guo-Hu; Chen, Xiao-Yan; Yang, Yan-Bin; Hammer, Francois; Yang, Guo-Chao; Deng, Li-Cai; Hu, Jing-Yao

    2010-12-01

    We study the ages of a large sample (1802) of nearly face-on disk low surface brightness galaxies (LSBGs) using the evolutionary population synthesis (EPS) model PEGASE with an exponentially decreasing star formation rate to fit their multiwavelength spectral energy distributions (SEDs) from far-ultraviolet (FUV) to near-infrared (NIR). The derived ages of LSBGs are 1-5 Gyr for most of the sample no matter if constant or varying dust extinction is adopted, which are similar to most of the previous studies on smaller samples. This means that these LSBGs formed the majority of their stars quite recently. However, a small part of the sample (~2%-3%) has larger ages of 5-8 Gyr, meaning their major star forming process may have occurred earlier. At the same time, a large sample (5886) of high surface brightness galaxies (HSBGs) are selected and studied using the same method for comparisons. The derived ages are 1-5 Gyr for most of the sample (97%) as well. These results probably mean that these LSBGs have not much different star formation histories from their HSBGs counterparts. However, we should notice that the HSBGs are generally about 0.2 Gyr younger, which could mean that the HSBGs may have undergone more recent star forming activities than the LSBGs.

  9. Ultraviolet photometry from the orbiting astronomical observatory. XXX - The Orion reflection nebulosity

    NASA Technical Reports Server (NTRS)

    Witt, A. N.; Lillie, C. F.

    1978-01-01

    Surface-brightness measurements are presented that cover the region of Orion in nine intermediate-width bandpasses ranging from 4250 to 1550 A. The existence of an extended ultraviolet reflection nebulosity in this area is confirmed, and the characteristics of its spectrum and spatial distribution are derived. The observations are consistent with a model in which the dense molecular cloud complex in Orion is illuminated by the foreground Orion aggregate of early-type stars. The interpretation is complicated by the fact that foreground dust may contribute to the observed scattered light. The scattering particles in the cloud appear to exhibit a wavelength-dependent albedo similar to that found for interstellar grains in general, with a strong indication that the phase function changes to a less forward-scattering form in the ultraviolet.

  10. Investigations on the emission in the extreme ultraviolet of a pseudospark based discharge light source

    NASA Astrophysics Data System (ADS)

    Bergmann, Klaus; Vieker, Jochen; von Wezyk, Alexander

    2016-10-01

    A new concept of a discharge based extreme ultraviolet radiation source is presented. This concept is based on an electrode system that consists of two consecutive pseudospark discharge stages. The first stage is used to create a pinch plasma as emitter in the extreme ultraviolet and soft X-ray range and the second stage is used as a high current switch between the storage capacity and the first stage. First results on the emission characteristics for the working gases nitrogen, krypton, and xenon, with focus on the emission at 2.88 nm, 6-7 nm, and around 13.5 nm, respectively, are disclosed under the aspect of the access to a larger discharge parameter range. It is shown that this increased range opens a path to a higher spectral peak brightness.

  11. Ultraviolet Radiation and Stratospheric Ozone

    NASA Technical Reports Server (NTRS)

    Stolarski, R.

    2003-01-01

    Ultraviolet radiation from the sun produces ozone in the stratosphere and it participates in the destruction of ozone. Absorption of solar ultraviolet radiation by ozone is the primary heating mechanism leading to the maximum in temperature at the stratopause. Variations of solar ultraviolet radiation on both the 27-day solar rotation period and the 11-year solar cycle affect ozone by several mechanisms. The temperature and ozone in the upper stratosphere respond to solar uv variations as a coupled system. An increase in uv leads to an increase in the production of ozone through the photolysis of molecular oxygen. An increase in uv leads to an increase in temperature through the heating by ozone photolysis. The increase in temperature leads to a partially-offsetting decrease in ozone through temperature-dependent reaction rate coefficients. The ozone variation modulates the heating by ozone photolysis. The increase in ozone at solar maximum enhances the uv heating. The processes are understood and supported by long-term data sets. Variation in the upper stratospheric temperatures will lead to a change in the behavior of waves propagating upward from the troposphere. Changes in the pattern of wave dissipation will lead to acceleration or deceleration of the mean flow and changes in the residual or transport circulation. This mechanism could lead to the propagation of the solar cycle uv variation from the upper stratosphere downward to the lower stratosphere. This process is not well-understood and has been the subject of an increasing number of model studies. I will review the data analyses for solar cycle and their comparison to model results.

  12. Combined ultraviolet studies of astronomical sources

    NASA Technical Reports Server (NTRS)

    Dupree, A. K.; Baliunas, S. L.; Blair, W. P.; Hartmann, L. W.; Huchra, J. P.; Raymond, J. C.; Smith, G. H.; Sonderblom, D. R.

    1985-01-01

    Ultraviolet studies of various astronomical entities are reported. Among the specific phenomena examined were supernova remnants, dwarf novae, red giant stars, stellar winds, binary stars, and galaxies.

  13. Ultraviolet and thermally stable polymer compositions

    NASA Technical Reports Server (NTRS)

    Adamson, M. J.; Gloria, H. R.; Goldsberry, R. E.; Reinisch, R. F.

    1972-01-01

    Copolymers, produced from aromatic substituted aromatic azine-siloxane compositions, are thermally stable, solar ultraviolet light non-degradable by wavelengths shorter than those reaching earth surface.

  14. Microgap ultra-violet detector

    DOEpatents

    Wuest, Craig R.; Bionta, Richard M.

    1994-01-01

    A microgap ultra-violet detector of photons with wavelengths less than 400 run (4000 Angstroms) which comprises an anode and a cathode separated by a gas-filled gap and having an electric field placed across the gap. Either the anode or the cathode is semi-transparent to UV light. Upon a UV photon striking the cathode an electron is expelled and accelerated across the gap by the electric field causing interactions with other electrons to create an electron avalanche which contacts the anode. The electron avalanche is detected and converted to an output pulse.

  15. Microgap ultra-violet detector

    DOEpatents

    Wuest, C.R.; Bionta, R.M.

    1994-09-20

    A microgap ultra-violet detector of photons with wavelengths less than 400 run (4,000 Angstroms) which comprises an anode and a cathode separated by a gas-filled gap and having an electric field placed across the gap is disclosed. Either the anode or the cathode is semi-transparent to UV light. Upon a UV photon striking the cathode an electron is expelled and accelerated across the gap by the electric field causing interactions with other electrons to create an electron avalanche which contacts the anode. The electron avalanche is detected and converted to an output pulse. 2 figs.

  16. ORIGIN OF THE DIFFUSE, FAR ULTRAVIOLET EMISSION IN THE INTERARM REGIONS OF M101

    SciTech Connect

    Crocker, Alison F.; Chandar, Rupali; Calzetti, Daniela; Holwerda, Benne Willem; Leitherer, Claus; Popescu, Cristina; Tuffs, R. J.

    2015-07-20

    We present images from the Solar Blind Channel on the Hubble Space Telescope that resolve hundreds of far-ultraviolet (FUV) emitting stars in two ∼1 kpc{sup 2} interarm regions of the grand-design spiral M101. The luminosity functions of these stars are compared with predicted distributions from simple star formation histories, and are best reproduced when the star formation rate has recently declined (past 10–50 Myr). This pattern is consistent with stars forming within spiral arms and then streaming into the interarm regions. We measure the diffuse FUV surface brightness after subtracting all of the detected stars, clusters, and background galaxies. A residual flux is found for both regions, which can be explained by a mix of stars below our detection limit and scattered FUV light. The amount of scattered light required is much larger for the region immediately adjacent to a spiral arm, a bright source of FUV photons.

  17. Probing 67P/Churyumov-Gerasimenko's Electron Environment Through Ultraviolet Emission by Rosetta Alice Observations

    NASA Astrophysics Data System (ADS)

    Schindhelm, Eric; Noonan, John; Keeney, Brian A.; Broiles, Thomas; Bieler, Andre; A'Hearn, Michael F.; Bertaux, Jean-Loup; Feaga, Lori M.; Feldman, Paul D.; Parker, Joel Wm.; Steffl, Andrew Joseph; Stern, S. Alan; Weaver, Harold A.

    2016-10-01

    The Alice Far-Ultraviolet (FUV) Spectrograph onboard ESA's Rosetta spacecraft has observed the coma of comet 67P/Churyumov-Gerasimenko from far approach in summer 2014 until the end of mission in September 2016. We present an overall perspective of the bright FUV emission lines (HI 1026 Å, OI 1302/1305/1306 Å multiplet, OI] 1356 Å, CO 1510 (1-0) Å, and CI 1657 Å) above the sunward hemisphere, detailing their spatial extent and brightness as a function of time and the heliocentric distance of the comet. We compare our observed gas column densities derived using electron temperatures and densities from the Ion Electron Sensor (IES) with those derived using the Inner Coma Environment Simulator (ICES) models in periods when electron-impact excited emission dominates over solar fluorescence emission. The electron population is characterized with 2 three-dimensional kappa functions, one dense and warm, one rarefied and hot.

  18. Large-solid-angle illuminators for extreme ultraviolet lithography with laser plasmas

    SciTech Connect

    Kubiak, G.D.; Tichenor, D.A.; Sweatt, W.C.; Chow, W.W.

    1995-06-01

    Laser Plasma Sources (LPSS) of extreme ultraviolet radiation are an attractive alternative to synchrotron radiation sources for extreme ultraviolet lithography (EUVL) due to their modularity, brightness, and modest size and cost. To fully exploit the extreme ultraviolet power emitted by such sources, it is necessary to capture the largest possible fraction of the source emission half-sphere while simultaneously optimizing the illumination stationarity and uniformity on the object mask. In this LDRD project, laser plasma source illumination systems for EUVL have been designed and then theoretically and experimentally characterized. Ellipsoidal condensers have been found to be simple yet extremely efficient condensers for small-field EUVL imaging systems. The effects of aberrations in such condensers on extreme ultraviolet (EUV) imaging have been studied with physical optics modeling. Lastly, the design of an efficient large-solid-angle condenser has been completed. It collects 50% of the available laser plasma source power at 14 nm and delivers it properly to the object mask in a wide-arc-field camera.

  19. Investigation of the moving structures in a coronal bright point

    SciTech Connect

    Ning, Zongjun; Guo, Yang

    2014-10-10

    We have explored the moving structures in a coronal bright point (CBP) observed by the Solar Dynamic Observatory Atmospheric Imaging Assembly (AIA) on 2011 March 5. This CBP event has a lifetime of ∼20 minutes and is bright with a curved shape along a magnetic loop connecting a pair of negative and positive fields. AIA imaging observations show that a lot of bright structures are moving intermittently along the loop legs toward the two footpoints from the CBP brightness core. Such moving bright structures are clearly seen at AIA 304 Å. In order to analyze their features, the CBP is cut along the motion direction with a curved slit which is wide enough to cover the bulk of the CBP. After integrating the flux along the slit width, we get the spacetime slices at nine AIA wavelengths. The oblique streaks starting from the edge of the CBP brightness core are identified as moving bright structures, especially on the derivative images of the brightness spacetime slices. They seem to originate from the same position near the loop top. We find that these oblique streaks are bi-directional, simultaneous, symmetrical, and periodic. The average speed is about 380 km s{sup –1}, and the period is typically between 80 and 100 s. Nonlinear force-free field extrapolation shows the possibility that magnetic reconnection takes place during the CBP, and our findings indicate that these moving bright structures could be the observational outflows after magnetic reconnection in the CBP.

  20. The Ultraviolet Spectrum of the Jovian Dayglow

    NASA Technical Reports Server (NTRS)

    Liu, Weihong; Dalgarno, A.

    1995-01-01

    The ultraviolet spectra of molecular hydrogen H2 and HD due to solar fluorescence and photoelectron excitation are calculated and compared with the Jovian equatorial dayglow spectrum measured at 3 A resolution at solar maximum. The dayglow emission is accounted for in both brightness and spectral shape by the solar fluorescence and photoelectron excitation and requires no additional energy source. The emission is characterized by an atmospheric temperature of 530 K and an H2 column density of 10(exp 20) cm(exp -2). The dayglow spectrum contains a cascade contribution to the Lyman band emission from high-lying E and F states. Its relative weakness at short wavelengths is due to both self-absorption by H2 and absorption by CH4. Strong wavelength coincidences of solar emission lines and absorption lines of H2 and HD produce unique line spectra which can be identified in the dayglow spectrum. The strongest fluorescence is due to absorption of the solar Lyman-beta line at 1025.72 A by the P(1) line of the (6, 0) Lyman band of H2 at 1025.93 A. The fluorescence lines due to absorption of the solar O 6 line at 1031.91 A by vibrationally excited H2 via the Q(3) line of the (1, 1) Werner band at 1031.86 A are identified. The fluorescence lines provide a sensitive measure of the atmospheric temperature. There occurs an exact coincidence of the solar O 6 line at 1031.91 A and the R(0) line of the (6, 0) Lyman band of HD at 1031-91 A, but HD on Jupiter is difficult to detect due to the dominance of the H2 emission where the HD emission is particularly strong. Higher spectral resolution and higher sensitivity may make possible such a detection. The high resolution (0.3 A) spectra of H2 and HD are presented to stimulate search for the HD on Jupiter with the Hubble Space Telescope.

  1. A Second Ultraviolet ``Light Bulb'' behind the Supernova Remnant SN 1006

    NASA Astrophysics Data System (ADS)

    Winkler, P. Frank; Long, Knox S.

    1997-09-01

    A point X-ray source located 9' NE of the center of SN 1006 has been spectroscopically identified as a background QSO, with a redshift of 0.335. The object is moderately bright, with magnitude V = 18.3. If its ultraviolet spectrum is typical of low-z quasars, this object will be a second source (after the Schweizer-Middleditch star) to use for absorption spectroscopy of material within SN 1006. Absorption spectra provide a unique probe for unshocked ejecta within this supernova remnant and can possibly solve the long-standing problem of ``missing'' iron in the remnants of Type Ia supernovae.

  2. A Comparison of Variable Total and Ultraviolet Solar Irradiance Inputs to 20 th Century Global Warming

    NASA Astrophysics Data System (ADS)

    Foukal, P. V.

    2002-05-01

    Analysis of spaceborne radiometry has shown that the total solar irradiance variation over the past two activity cycles was approximately proportional to the weighted difference between areas of dark spots and bright faculae and enhanced network. Empirical models of ultraviolet irradiance variation indicate that its behavior is dominated by changes in area of the bright component alone, whose photometric contrast increases at shorter wavelength.This difference in time behavior of total and UV irradiances could help to discriminate between their relative importance in forcing of global warming. Our recent digitization of archival Ca K images from Mt Wilson and NSO provides the first direct measurement of variations in area of the bright component, extending between 1915 and 1999 (previous models have relied on the sunspot number or other proxies to estimate the bright - component contribution). We use these more direct measurements to derive the time behavior of solar total and UV irradiance variation, over this period .We find that they are significantly different;the total irradiance variation accounts for over 80 percent of the variance in global temperature during this period, while the ultraviolet irradiance variation accounts for only about 20 percent. The amplitude of total irradiance variation in our model is smaller than required to influence global warming,in current climate models.Also, the impact of sulfate aerosol variations on the extended cooling between the 1940's and 1970's must be better understood before the significance of correlations between 20 th century global warming, and any solar activity index can be properly assessed. Despite these caveats, the lower correlation we find between global temperature and UV,compared to total, irradiance requires consideration in the search for physical mechanisms linking solar activity and climate. This work was supported in part under NASA grant NAG5-7607 to CRI, Inc., and NAG5-10998 to the Applied Physics

  3. Type IA supernovae in the ultraviolet, optical, and near-infrared

    NASA Astrophysics Data System (ADS)

    Smitka, Michael Thomas

    We present an ultraviolet (UV) spectroscopic atlas containing 91 spectra of 22 unique Type Ia supernovae (SNe Ia). The spectra were observed using the Ultraviolet/Optical Telescope (UVOT) onboard the Swift space telescope. We present a new technique of decontaminating UVOT grism spectra, which we apply to 40 of the spectra in our sample. We present the first UV spectroscopic series of a peculiar 1999aa-like SN Ia, iPTF14bdn, and compare to normal SNe in our sample. We find this SN to be very blue at early times due to a bright feature between 2800 - 3200A. We attribute this to a lower UV opacity caused by higher temperatures above the SN photosphere, likely due to a greater quantity of 56Ni in this region. We also identify the spectroscopic feature differences between 2700 - 3300A responsible for the near-UV (NUV) photometric diversity. Comparison of these features to model data suggest that NUV-bluer SNe result from lower metal abundances in the outer ejecta layers. We combine our UV spectral atlas with UV, optical and NIR photometry, and spectra to generate a UV-O-IR spectral series atlas for 8 SNe Ia near peak brightness. The UV-O-IR SEDs represent time evolution within -10 to +30 days of peak brightness, decline rates between 0.9 < Deltam 15(B) < 1.8, and UV subclassification (when known). Using these data, we calculate integrated bolometric luminosities and synthesized 56 Ni masses. We demonstrate that our UV-O-IR SEDs provide an improved method of calculating K-corrections for B-band optical photometry, and present an analysis of SNe Ia UV K-corrections. We present a method of calculating bolometric corrections which take the SNe decline rates into account for SNe near peak brightness.

  4. Dust near luminous ultraviolet stars

    NASA Technical Reports Server (NTRS)

    Henry, Richard C.

    1992-01-01

    More than 700 luminous stars in the infrared astronomical satellite (IRAS) Skyflux plates were examined for the presence of dust heated by a nearby star. This dust may be distinguished from the ubiquitous cool cirrus by its higher temperature and thus enhanced 60 micron emission. More than 120 dust clouds were found around only 106 of the stars with a volume filling factor of 0.006 and an intercloud separation of 46 pc. A region of dust smoothly distributed through the volume of space heated by the star could not be found and hence an upper limit of 0.05 cm(exp -3) is placed on the equivalent gas density in the intercloud regions. The clouds have an average density of 0.22 cm(exp -3) and a radius of 1.9 pc, albeit with wide variations in their properties. Two different scale heights of 140 and 540 pc were found. This was interpreted as evidence for different distributions of dust in and out of the galactic disk.

  5. Ultraviolet Spectra of Uranian Satellites

    NASA Astrophysics Data System (ADS)

    Roush, Ted

    1996-07-01

    The ultraviolet reflectance spectra of the icy satellites ofUranus are largely unknown. We propose to use the HubbleSpace Telescope Faint Object Spectrograph in order to obtainthe first high S/N UV spectra of Ariel, Titania, and Oberon.Because of our innovative targeting approach, we have alsobeen able to include Umbriel in our observational plans.These satellites sample almost the full range of UV albedosand UV/VIS colors exhibited by the large Uranian satellites.The spectral resolution and range will overlap with earth-based telescopic and spacecraft observations of these objectsallowing for comparisons of the UV data with existing visualand near-infrared spectra of these objects. These comparisonswill ultimately provide greater constraints on the relativelylow albedo spectrally neutral non-ice component on the Uraniansatellites. The existance of UV spectral features due tospecies such as O_3, H_2O_2 or carbon-rich macromolecules(e.g. polycyclic aromatic hydrocarbons) can provide evidencefor modification of the surfaces via plasma or meteoriticbombardment, alteration by high-energy ultraviolet radiation,or accretion of particles from nearby sources such asplanetary rings or dust bands.

  6. The International Ultraviolet Explorer (IUE)

    NASA Technical Reports Server (NTRS)

    Kondo, Yoji

    1990-01-01

    The International Ultraviolet Explorer (IUE) was launched into a geosynchronous orbit on 26 January 1978. It is equipped with a 45-cm mirror and spectrographs operating in the far-ultraviolet (1150-2000 A) and the midultraviolet (1900-3200 A) wavelength regions. In a low-dispersion mode, the spectral resolution is some 6-7 A. In a high-dispersion echelle mode, the resolution is about 0.1 Aat the shortest wavelength and about 0.3 A at the longest. It is a collaborative program among NASA, ESA, and the British SERC. The IUE is operated in real time 16 hours a day from NASA Goddard Space Flight Center near Washington, D.C. and 8 hours daily from ESA's Villafranca groundstation near Madrid, Spain. By the end of 1989, 1870 papers, using IUE observations, have been published in referred journals. During the same period, over 1700 different astronomers from all over the world used the IUE for their research.

  7. Ultraviolet light and ocular diseases.

    PubMed

    Yam, Jason C S; Kwok, Alvin K H

    2014-04-01

    The objective of this study is to review the association between ultraviolet (UV) light and ocular diseases. The data are sourced from the literature search of Medline up to Nov 2012, and the extracted data from original articles, review papers, and book chapters were reviewed. There is a strong evidence that ultraviolet radiation (UVR) exposure is associated with the formation of eyelid malignancies [basal cell carcinoma (BCC) and squamous cell carcinoma (SCC)], photokeratitis, climatic droplet keratopathy (CDK), pterygium, and cortical cataract. However, the evidence of the association between UV exposure and development of pinguecula, nuclear and posterior subcapsular cataract, ocular surface squamous neoplasia (OSSN), and ocular melanoma remained limited. There is insufficient evidence to determine whether age-related macular degeneration (AMD) is related to UV exposure. It is now suggested that AMD is probably related to visible radiation especially blue light, rather than UV exposure. From the results, it was concluded that eyelid malignancies (BCC and SCC), photokeratitis, CDK, pterygium, and cortical cataract are strongly associated with UVR exposure. Evidence of the association between UV exposure and development of pinguecula, nuclear and posterior subcapsular cataract, OSSN, and ocular melanoma remained limited. There is insufficient evidence to determine whether AMD is related to UV exposure. Simple behaviural changes, appropriate clothing, wearing hats, and UV blocking spectacles, sunglasses or contact lens are effective measures for UV protection.

  8. High Brightness Neutron Source for Radiography

    SciTech Connect

    Cremer, J. T.; Piestrup, Melvin, A.; Gary, Charles, K.; Harris, Jack, L. Williams, David, J.; Jones, Glenn, E.; Vainionpaa, J. , H.; Fuller, Michael, J.; Rothbart, George, H.; Kwan, J., W.; Ludewigt, B., A.; Gough, R.., A..; Reijonen, Jani; Leung, Ka-Ngo

    2008-12-08

    This research and development program was designed to improve nondestructive evaluation of large mechanical objects by providing both fast and thermal neutron sources for radiography. Neutron radiography permits inspection inside objects that x-rays cannot penetrate and permits imaging of corrosion and cracks in low-density materials. Discovering of fatigue cracks and corrosion in piping without the necessity of insulation removal is possible. Neutron radiography sources can provide for the nondestructive testing interests of commercial and military aircraft, public utilities and petrochemical organizations. Three neutron prototype neutron generators were designed and fabricated based on original research done at the Lawrence Berkeley National Laboratory (LBNL). The research and development of these generators was successfully continued by LBNL and Adelphi Technology Inc. under this STTR. The original design goals of high neutron yield and generator robustness have been achieved, using new technology developed under this grant. In one prototype generator, the fast neutron yield and brightness was roughly 10 times larger than previously marketed neutron generators using the same deuterium-deuterium reaction. In another generator, we integrate a moderator with a fast neutron source, resulting in a high brightness thermal neutron generator. The moderator acts as both conventional moderator and mechanical and electrical support structure for the generator and effectively mimics a nuclear reactor. In addition to the new prototype generators, an entirely new plasma ion source for neutron production was developed. First developed by LBNL, this source uses a spiral antenna to more efficiently couple the RF radiation into the plasma, reducing the required gas pressure so that the generator head can be completely sealed, permitting the possible use of tritium gas. This also permits the generator to use the deuterium-tritium reaction to produce 14-MeV neutrons with increases

  9. Discovery of a bright eclipsing cataclysmic variable

    NASA Astrophysics Data System (ADS)

    Sing, D. K.; Green, E. M.; Howell, S. B.; Holberg, J. B.; Lopez-Morales, M.; Shaw, J. S.; Schmidt, G. D.

    2007-11-01

    Aims:We report on the discovery of J0644+3344, a bright, deeply-eclipsing cataclysmic variable (CV) binary. Methods: Optical photometric and spectroscopic observations were obtained to determine the nature and characteristics of this CV. Results: Spectral signatures of both binary components and an accretion disk can be seen at optical wavelengths. The optical spectrum shows broad H I, He I, and He II accretion disk emission lines with deep narrow absorption components from H I, He I, Mg II, and Ca II. The absorption lines are seen throughout the orbital period, disappearing only during primary eclipse. These absorption lines are either the result of an optically-thick inner accretion disk or from the photosphere of the primary star. Radial velocity measurements show that the H I, He I, and Mg II absorption lines phase with the primary star, while weak absorption features in the continuum, between Hα and Hβ, phase with the secondary star. Radial velocity solutions give a 150±4 km s-1 semi-amplitude for the primary star and 192.8±5.6 km s-1 for the secondary, resulting in a primary to secondary mass ratio of q = 1.285. The individual stellar masses are 0.63-0.69 M⊙ for the primary and 0.49-0.54 M⊙ for the secondary, with the uncertainty largely due to the inclination. Conclusions: The bright eclipsing nature of this binary has helped provide masses for both components with an accuracy rarely achieved for CVs. This binary most closely resembles a nova-like UX UMa or SW Sex type of CV. J0644+3344, however, has a longer orbital period than most UX UMa or SW Sex stars. Assuming an evolution toward shorter orbital periods, J0644+3344 is therefore likely to be a young interacting binary. The secondary star is consistent with the size and spectral type of a K8 star, but has the mass of a M0.

  10. Transmitting and reflecting diffuser. [using ultraviolet grade fused silica coatings

    NASA Technical Reports Server (NTRS)

    Keafer, L. S., Jr.; Burcher, E. E.; Kopia, L. P. (Inventor)

    1977-01-01

    An ultraviolet grade fused silica substrate is coated with vaporized fused silica. The coating thickness is controlled, one thickness causing ultraviolet light to diffuse and another thickness causing ultraviolet light to reflect a near Lambertian pattern.

  11. Near-ultraviolet laser diodes for brilliant ultraviolet fluorophore excitation.

    PubMed

    Telford, William G

    2015-12-01

    Although multiple lasers are now standard equipment on most modern flow cytometers, ultraviolet (UV) lasers (325-365 nm) remain an uncommon excitation source for cytometry. Nd:YVO4 frequency-tripled diode pumped solid-state lasers emitting at 355 nm are now the primary means of providing UV excitation on multilaser flow cytometers. Although a number of UV excited fluorochromes are available for flow cytometry, the cost of solid-state UV lasers remains prohibitively high, limiting their use to all but the most sophisticated multilaser instruments. The recent introduction of the brilliant ultraviolet (BUV) series of fluorochromes for cell surface marker detection and their importance in increasing the number of simultaneous parameters for high-dimensional analysis has increased the urgency of including UV sources in cytometer designs; however, these lasers remain expensive. Near-UV laser diodes (NUVLDs), a direct diode laser source emitting in the 370-380 nm range, have been previously validated for flow cytometric analysis of most UV-excited probes, including quantum nanocrystals, the Hoechst dyes, and 4',6-diamidino-2-phenylindole. However, they remain a little-used laser source for cytometry, despite their significantly lower cost. In this study, the ability of NUVLDs to excite the BUV dyes was assessed, along with their compatibility with simultaneous brilliant violet (BV) labeling. A NUVLD emitting at 375 nm was found to excite most of the available BUV dyes at least as well as a UV 355 nm source. This slightly longer wavelength did produce some unwanted excitation of BV dyes, but at sufficiently low levels to require minimal additional compensation. NUVLDs are compact, relatively inexpensive lasers that have higher power levels than the newest generation of small 355 nm lasers. They can, therefore, make a useful, cost-effective substitute for traditional UV lasers in multicolor analysis involving the BUV and BV dyes.

  12. Pen Ink as an Ultraviolet Dosimeter

    ERIC Educational Resources Information Center

    Downs, Nathan; Turner, Joanna; Parisi, Alfio; Spence, Jenny

    2008-01-01

    A technique for using highlighter ink as an ultraviolet dosimeter has been developed for use by secondary school students. The technique requires the students to measure the percentage of colour fading in ink drawn onto strips of paper that have been exposed to sunlight, which can be calibrated to measurements of the ultraviolet irradiance using…

  13. Clear Film Protects Against Ultraviolet Radiation

    NASA Technical Reports Server (NTRS)

    Gupta, A.; Yavrouian, A.

    1983-01-01

    Acrylic film contains screeing agent filtering ultraviolet radiation up to 380 nanometers in wavelength but passes other components of Sunlight. Film used to protect such materials as rubber and plastics degraded by ultraviolet light. Used as protective cover on outdoor sheets or pipes made of such materials as polyethylene or polypropylene and on solar cells.

  14. Ultraviolet Echelle spectropolarimeter for the ARAGO mission.

    NASA Astrophysics Data System (ADS)

    Perea Abarca, B.; Gómez de Castro, A. I.; Marcos-Arenal, P.

    2017-03-01

    In this contribution, we describe an efficient instrument designed for mid resolution (25.000) spectropolarimetric observations in the ultraviolet wavelength range (119-320 nm). Spectropolarimetry in the ultraviolet range introduces challenging constraints in the image quality of the echellé design that are addressed via the introduction special optical elements.

  15. Ultraviolet light-an FDA approved technology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ultraviolet Light (254 nm) is a U.S. Food and Drug Administration approved nonthermal intervention technology that can be used for decontamination of food and food contact surfaces. Ultraviolet light is a green technology that leaves no chemical residues. Results from our laboratory indicate that ex...

  16. The Bright Future of Gravitational Wave Astronomy

    NASA Astrophysics Data System (ADS)

    Gonzalez, Gabriela

    2008-04-01

    These are exciting times in the search for gravitational waves. Gravitational waves are expected from many different astrophysical sources: brief transients from violent events like supernova explosions and collisions of neutron stars and black holes, coalescence of compact binary systems, continuous waves from rotating systems, and stochastic signals from cosmological origin or unresolved transients. The LIGO gravitational wave detectors have achieved unprecedented sensitivity to gravitational waves, and other detectors around the world are expected to reach similar sensitivities. The LIGO Scientific Collaboration (LSC) has recently completed their most sensitive observation run to date with LIGO and GEO detectors, including several months of joint observations with the European VIRGO detector. The LIGO Laboratory and the LSC, as well as the Virgo Collaboration, are actively preparing for operating enhanced detectors in the very near future. The next decade will see the construction and commissioning of Advanced LIGO and VIRGO, and quite possibly the launch of the space-based LISA mission, starting for sure then, if not earlier, a new era for gravitational wave astronomy. Plans for a world-wide network of ground based detectors involving more detectors in Europe, Japan and Australia are becoming more concrete. The future of gravitational wave astronomy is bright indeed! In this talk, will briefly describe the present status of the ground and space based detector projects and discuss the science we may expect to do with the detectors (and detections!) we will have in the upcoming era of gravitational wave astronomy.

  17. High output lamp with high brightness

    DOEpatents

    Kirkpatrick, Douglas A.; Bass, Gary K.; Copsey, Jesse F.; Garber, Jr., William E.; Kwong, Vincent H.; Levin, Izrail; MacLennan, Donald A.; Roy, Robert J.; Steiner, Paul E.; Tsai, Peter; Turner, Brian P.

    2002-01-01

    An ultra bright, low wattage inductively coupled electrodeless aperture lamp is powered by a solid state RF source in the range of several tens to several hundreds of watts at various frequencies in the range of 400 to 900 MHz. Numerous novel lamp circuits and components are disclosed including a wedding ring shaped coil having one axial and one radial lead, a high accuracy capacitor stack, a high thermal conductivity aperture cup and various other aperture bulb configurations, a coaxial capacitor arrangement, and an integrated coil and capacitor assembly. Numerous novel RF circuits are also disclosed including a high power oscillator circuit with reduced complexity resonant pole configuration, parallel RF power FET transistors with soft gate switching, a continuously variable frequency tuning circuit, a six port directional coupler, an impedance switching RF source, and an RF source with controlled frequency-load characteristics. Numerous novel RF control methods are disclosed including controlled adjustment of the operating frequency to find a resonant frequency and reduce reflected RF power, controlled switching of an impedance switched lamp system, active power control and active gate bias control.

  18. Dark Skies, Bright Kids Year 6

    NASA Astrophysics Data System (ADS)

    Liss, Sandra; Troup, Nicholas William; Johnson, Kelsey E.; Barcos-Munoz, Loreto D.; Beaton, Rachael; Bittle, Lauren; Borish, Henry J.; Burkhardt, Andrew; Corby, Joanna; Dean, Janice; Hancock, Danielle; King, Jennie; Prager, Brian; Romero, Charles; Sokal, Kimberly R.; Stierwalt, Sabrina; Wenger, Trey; Zucker, Catherine

    2015-01-01

    Now entering our sixth year of operation, Dark Skies, Bright Kids (DSBK) is an entirely volunteer-run outreach organization based out of the Department of Astronomy at the University of Virginia. Our core mission is to enhance elementary science education and literacy in central Virginia through fun, hands-on activities that introduce basic Astronomy concepts beyond Virginia's Standards of Learning. Our primary focus is hosting an 8-10 week after-school astronomy club at underserved elementary and middle schools. Each week, DSBK volunteers take the role of coaches to introduce astronomy-related concepts ranging from the Solar System to galaxies to astrobiology, and to lead students in interactive learning activities. Another hallmark of DSBK is hosting our Annual Central Virginia Star Party, a free event open to the community featuring star-gazing and planetarium shows.DSBK has amassed over 15,000 contact hours since 2009 and we continue to broaden our impact. One important step we have taken in the past year is to establish a graduate student led assessment program to identify and implement directed learning goals for DSBK outreach. The collection of student workbooks, observations, and volunteer surveys indicates broad scale success for the program both in terms of student learning and their perception of science. The data also reveal opportunities to improve our organizational and educational practices to maximize student achievement and overall volunteer satisfaction for DSBK's future clubs and outreach endeavors.

  19. NuSTAR Observations of Bright AGNs

    NASA Astrophysics Data System (ADS)

    Elvis, Martin; Ballantyne, D. R.; Blandford, R. D.; Boggs, S.; Boydstun, K.; Brenneman, L.; Cappi, M.; Christensen, F.; Craig, W.; Fabian, A.; Fuerst, F.; Guainazzi, M.; Hailey, C. J.; Harrison, F.; Madejski, G. M.; Marinucci, A.; Matt, G.; Nandra, K.; Reynolds, C. S.; Stern, D.; Walton, D.; Zhang, W.; NuSTAR Team

    2013-01-01

    The dramatically improved signal-to-noise provided by NuSTAR up to ~80 keV allows a qualitative change in our understanding of the X-ray emission of Active Galactic Nuclei (AGNs). Despite intensive investigation for over 30 years, during which the 0.1-10 keV spectra and variability of AGNs have been mapped out in detail, we do not know the origin of the X-ray source in AGNs. The "standard model" of supermassive black hole, accretion disk and relativistic jet does not predict an X-ray source in a straightforward way. It is usually assumed that the X-rays were UV photons from the accretion disk that have been Compton up-scattered in a "hot corona", but the temperature, optical depth and geometry of this corona are unknown - if it exists. NuSTAR enables the measurement of the high energy cut-off of the X-ray spectrum, and so the corona temperature, to be measured precisely for the first time, and tests the relativistic Fe-K line and Compton reflection models. If this model is correct then, with Suzaku and XMM-Newton, NuSTAR can measure black hole spins to high accuracy. We outline the NuSTAR GTO program on bright, unobscured, AGNs including simultaneous observations with Suzaku and XMM-Newton, and show early data.

  20. Intercomparisons of nine sky brightness detectors.

    PubMed

    den Outer, Peter; Lolkema, Dorien; Haaima, Marty; van der Hoff, Rene; Spoelstra, Henk; Schmidt, Wim

    2011-01-01

    Nine Sky Quality Meters (SQMs) have been intercompared during a night time measurement campaign held in the Netherlands in April 2011. Since then the nine SQMs have been distributed across The Netherlands and form the Dutch network for monitoring night sky brightness. The goal of the intercomparison was to infer mutual calibration factors and obtain insight into the variability of the SQMs under different meteorological situations. An ensemble average is built from the individual measurements and used as a reference to infer the mutual calibration factors. Data required additional synchronization prior to the calibration determination, because the effect of moving clouds combined with small misalignments emerges as time jitter in the measurements. Initial scatter of the individual instruments lies between ±14%. Individual night time sums range from -16% to +20%. Intercalibration reduces this to 0.5%, and -7% to +9%, respectively. During the campaign the smallest luminance measured was 0.657 ± 0.003 mcd/m(2) on 12 April, and the largest value was 5.94 ± 0.03 mcd/m(2) on 2 April. During both occurrences interfering circumstances like snow cover or moonlight were absent.

  1. Bright visible light emission from graphene

    NASA Astrophysics Data System (ADS)

    Kim, Young Duck; Kim, Hakseong; Cho, Yujin; Ryoo, Ji Hoon; Park, Cheol-Hwan; Kim, Pilkwang; Kim, Yong Seung; Lee, Sunwoo; Li, Yilei; Park, Seung-Nam; Shim Yoo, Yong; Yoon, Duhee; Dorgan, Vincent E.; Pop, Eric; Heinz, Tony F.; Hone, James; Chun, Seung-Hyun; Cheong, Hyeonsik; Lee, Sang Wook; Bae, Myung-Ho; Park, Yun Daniel

    2015-08-01

    Graphene and related two-dimensional materials are promising candidates for atomically thin, flexible and transparent optoelectronics. In particular, the strong light-matter interaction in graphene has allowed for the development of state-of-the-art photodetectors, optical modulators and plasmonic devices. In addition, electrically biased graphene on SiO2 substrates can be used as a low-efficiency emitter in the mid-infrared range. However, emission in the visible range has remained elusive. Here, we report the observation of bright visible light emission from electrically biased suspended graphene devices. In these devices, heat transport is greatly reduced. Hot electrons (˜2,800 K) therefore become spatially localized at the centre of the graphene layer, resulting in a 1,000-fold enhancement in thermal radiation efficiency. Moreover, strong optical interference between the suspended graphene and substrate can be used to tune the emission spectrum. We also demonstrate the scalability of this technique by realizing arrays of chemical-vapour-deposited graphene light emitters. These results pave the way towards the realization of commercially viable large-scale, atomically thin, flexible and transparent light emitters and displays with low operation voltage and graphene-based on-chip ultrafast optical communications.

  2. Modular Zero Energy. BrightBuilt Home

    SciTech Connect

    Aldrich, Robb; Butterfield, Karla

    2016-03-01

    Kaplan Thompson Architects (KTA) has specialized in sustainable, energy-efficient buildings, and they have designed several custom, zero-energy homes in New England. These zero-energy projects have generally been high-end, custom homes with budgets that could accommodate advanced energy systems. In an attempt to make zero energy homes more affordable and accessible to a larger demographic, KTA explored modular construction as way to provide high-quality homes at lower costs. In the mid-2013, KTA formalized this concept when they launched BrightBuilt Home (BBH). The BBH mission is to offer a line of architect-designed, high-performance homes that are priced to offer substantial savings off the lifetime cost of a typical home and can be delivered in less time. For the past two years, CARB has worked with BBH and Keiser Homes (the primary modular manufacturer for BBH) to discuss challenges related to wall systems, HVAC, and quality control. In Spring of 2014, CARB and BBH began looking in detail on a home to be built in Lincolnville, ME by Black Bros. Builders. This report details the solution package specified for this modular plan and the challenges that arose during the project.

  3. Broken Surface Brightness Profiles in Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Herrmann, Kimberly A.; Hunter, D. A.; Zhang, H. X.; LITTLE THINGS Team

    2011-01-01

    Recently it has been well shown that there are three different surface brightness profile types in spiral galaxies: (I) the minority, where the light falls off with a single exponential; (II) truncated, the majority, where the light falls off with one exponential to a break radius and then falls off more steeply; and (III) anti-truncated, where the light falls off with a more shallow exponential beyond the break radius. Additionally, Bakos, Trujillo, & Pohlen (2008) showed that each type has a characteristic color trend with respect to the break location. In dwarf disk galaxies, however, there is a fourth type which is perhaps a special Type II case: the light profile is flat on the inside and then falls off exponentially beyond the break radius. We will show the different color trends for these four profile types from a large photometric study of dwarf disk galaxies and explore the ramifications of the differences between spirals and dwarfs. We gratefully acknowledge funding for this research from the National Science Foundation (AST-0707563).

  4. Challenging Exceptionally Bright Children in Early Childhood Classrooms

    ERIC Educational Resources Information Center

    Gadzikowski, Ann

    2013-01-01

    Nearly every group of children includes at least one exceptionally bright child. From the especially creative child to the child who has already mastered learning outcomes to the "twice exceptional" child, exceptionally bright children have a wide range of talents and behaviors. This book will help you understand what it means to be…

  5. Spain 31-GHz observations of sky brightness temperatures

    NASA Technical Reports Server (NTRS)

    Gary, B. L.

    1988-01-01

    A water vapor radiometer was deployed at DSS 63 for 3 months of sky brightness temperature measurements at 31 GHz. An exceedance plot was derived from this data showing the fraction of time that 31 GHz 30 degree elevation angle brightness temperature exceeds specified values. The 5 percent exceedance statistics occurs at 75 K, compared with 70 K in Australia.

  6. Analysis of Bright Harvest Remote Analysis for Residential Solar Installations

    SciTech Connect

    Nangle, John; Simon, Joseph

    2015-06-17

    Bright Harvest provides remote shading analysis and design products for residential PV system installers. The National Renewable Energy Laboratory (NREL) through the NREL Commercialization Assistance Program, completed comparative assessments between on-site measurements and remotely calculated values to validate the accuracy of Bright Harvest’s remote shading and power generation.

  7. Spatial Model of Sky Brightness Magnitude in Langkawi Island, Malaysia

    NASA Astrophysics Data System (ADS)

    Redzuan Tahar, Mohammad; Kamarudin, Farahana; Umar, Roslan; Khairul Amri Kamarudin, Mohd; Hazmin Sabri, Nor; Ahmad, Karzaman; Rahim, Sobri Abdul; Sharul Aikal Baharim, Mohd

    2017-03-01

    Sky brightness is an essential topic in the field of astronomy, especially for optical astronomical observations that need very clear and dark sky conditions. This study presents the spatial model of sky brightness magnitude in Langkawi Island, Malaysia. Two types of Sky Quality Meter (SQM) manufactured by Unihedron are used to measure the sky brightness on a moonless night (or when the Moon is below the horizon), when the sky is cloudless and the locations are at least 100 m from the nearest light source. The selected locations are marked by their GPS coordinates. The sky brightness data obtained in this study were interpolated and analyzed using a Geographic Information System (GIS), thus producing a spatial model of sky brightness that clearly shows the dark and bright sky areas in Langkawi Island. Surprisingly, our results show the existence of a few dark sites nearby areas of high human activity. The sky brightness of 21.45 mag arcsec{}-2 in the Johnson-Cousins V-band, as the average of sky brightness equivalent to 2.8 × {10}-4{cd} {{{m}}}-2 over the entire island, is an indication that the island is, overall, still relatively dark. However, the amount of development taking place might reduce the number in the near future as the island is famous as a holiday destination.

  8. 7 CFR 51.2000 - Clean and bright.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Clean and bright. 51.2000 Section 51.2000 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Grades of Filberts in the Shell 1 Definitions § 51.2000 Clean and bright. Clean and...

  9. 7 CFR 51.2000 - Clean and bright.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Clean and bright. 51.2000 Section 51.2000 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Grades of Filberts in the Shell 1 Definitions § 51.2000 Clean and bright. Clean and...

  10. 7 CFR 51.2000 - Clean and bright.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Clean and bright. 51.2000 Section 51.2000 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Grades of Filberts in the Shell 1 Definitions § 51.2000 Clean and bright. Clean and...

  11. Ultraviolet safety assessments of insect light traps

    PubMed Central

    Sliney, David H.; Gilbert, David W.; Lyon, Terry

    2016-01-01

    ABSTRACT Near-ultraviolet (UV-A: 315–400 nm), “black-light,” electric lamps were invented in 1935 and ultraviolet insect light traps (ILTs) were introduced for use in agriculture around that time. Today ILTs are used indoors in several industries and in food-service as well as in outdoor settings. With recent interest in photobiological lamp safety, safety standards are being developed to test for potentially hazardous ultraviolet emissions. A variety of UV “Black-light” ILTs were measured at a range of distances to assess potential exposures. Realistic time-weighted human exposures are shown to be well below current guidelines for human exposure to ultraviolet radiation. These UV-A exposures would be far less than the typical UV-A exposure in the outdoor environment. Proposals are made for realistic ultraviolet safety standards for ILT products. PMID:27043058

  12. Ultraviolet safety assessments of insect light traps.

    PubMed

    Sliney, David H; Gilbert, David W; Lyon, Terry

    2016-01-01

    Near-ultraviolet (UV-A: 315-400 nm), "black-light," electric lamps were invented in 1935 and ultraviolet insect light traps (ILTs) were introduced for use in agriculture around that time. Today ILTs are used indoors in several industries and in food-service as well as in outdoor settings. With recent interest in photobiological lamp safety, safety standards are being developed to test for potentially hazardous ultraviolet emissions. A variety of UV "Black-light" ILTs were measured at a range of distances to assess potential exposures. Realistic time-weighted human exposures are shown to be well below current guidelines for human exposure to ultraviolet radiation. These UV-A exposures would be far less than the typical UV-A exposure in the outdoor environment. Proposals are made for realistic ultraviolet safety standards for ILT products.

  13. Solar CIV Vacuum-Ultraviolet Fabry-Perot Interferometers

    NASA Technical Reports Server (NTRS)

    Gary, G. Allen; West, Edward A.; Rees, David; McKay, Jack A.; Zukic, Maumer; Herman, Peter

    2006-01-01

    Aims: A tunable, high spectral resolution, high effective finesse, vacuum ultraviolet (VUV) Fabry-Perot interferometer (PPI) is designed for obtaining narrow-passband images, magnetograms, and Dopplergrams of the transition region emission line of CIV (155 nm). Methods: The integral part of the CIV narrow passband filter package (with a 2-10 pm FWHM) consists of a multiple etalon system composed of a tunable interferometer that provides high-spectral resolution and a static low-spectral resolution interferometer that allows a large effective free spectral range. The prefilter for the interferometers is provided by a set of four mirrors with dielectric high-reflective coatings. A tunable interferometer, a VUV piezoelectric-control etalon, has undergone testing using the surrogate F2 eximer laser line at 157 nm for the CIV line. We present the results of the tests with a description of the overall concept for a complete narrow-band CIV spectral filter. The static interferometer of the filter is envisioned as being hudt using a set of fixed MgF2 plates. The four-mirror prefilter is designed to have dielectric multilayer n-stacks employing the design concept used in the Ultraviolet Imager of NASA's Polar Spacecraft. A dual etalon system allows the effective free spectral range to be commensurate with the prefilter profile. With an additional etalon, a triple etalon system would allow a spectrographic resolution of 2 pm. The basic strategy has been to combine the expertise of spaceflight etalon manufacturing with VUV coating technology to build a VUV FPI which combines the best attributes of imagers and spectrographs into a single compact instrument. Results. Spectro-polarimetry observations of the transition region CIV emission can be performed to increase the understanding of the magnetic forces, mass motion, evolution, and energy release within the solar atmosphere at the base of the corona where most of the magnetic field is approximately force-free. The 2D imaging

  14. Detection of latent fingerprints by ultraviolet spectral imaging

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Xu, Xiaojing; Wang, Guiqiang

    2013-12-01

    Spectral imaging technology research is becoming more popular in the field of forensic science. Ultraviolet spectral imaging technology is an especial part of the full spectrum of imaging technology. This paper finished the experiment contents of the ultraviolet spectrum imaging method and image acquisition system based on ultraviolet spectral imaging technology. Ultraviolet spectral imaging experiments explores a wide variety of ultraviolet reflectance spectra of the object material curve and its ultraviolet spectrum of imaging modalities, can not only gives a reference for choosing ultraviolet wavelength to show the object surface potential traces of substances, but also gives important data for the ultraviolet spectrum of imaging technology development.

  15. A Closer Look At the Fluctuations in the Brightness of Sn 2009ip During Its Late 2012 Eruption

    NASA Astrophysics Data System (ADS)

    Martin, J. C.; Hambsch, F.-J.; Margutti, R.; Tan, T. G.; Curtis, I.; Soderberg, A.

    2015-01-01

    The supernova (SN) impostor SN 2009ip has re-brightened several times since its initial discovery in 2009 August. During its last outburst in late 2012 September, it reached a peak brightness of mv ˜13.5 (Mv brighter than -18), causing some to speculate that it had undergone a terminal core-collapse SN. Relatively high-cadence multi-wavelength photometry of the post-peak decline revealed bumps in brightness infrequently observed in other SNe IIn. These bumps occurred synchronously in all ultraviolet (UV) and optical bands with amplitudes of 0.1-0.4 mag at intervals of 10-30 days. Episodic continuum brightening and dimming in the UV and optical with these characteristics is not easily explained within the context of models that have been proposed for the late September 2012 outburst of SN 2009ip. We also present evidence that the post-peak fluctuations in brightness occur at regular intervals and raise more questions about their origin.

  16. A dense plasma ultraviolet source

    NASA Technical Reports Server (NTRS)

    Lee, J. H.; Mcfarland, D. R.

    1978-01-01

    The intense ultraviolet emission from the NASA Hypocycloidal-Pinch (HCP) plasma is investigated. The HCP consists of three disk electrodes whose cross section has a configuration similar to the cross section of a Mather-type plasma focus. Plasma foci were produced in deuterium, helium, xenon, and krypton gases in order to compare their emission characteristics. Time-integrated spectra in the wavelength range from 200 nm to 350 nm and temporal variations of the uv emission were obtained with a uv spectrometer and a photomultiplier system. Modifications to enhance uv emission in the iodine-laser pump band (250 to 290 nm) and preliminary results produced by these modifications are presented. Finally, the advantages of the HCP as a uv over use of conventional xenon lamps with respect to power output limit, spectral range, and lifetime are discussed.

  17. Global Ultraviolet Imager (GUVI) investigation

    NASA Technical Reports Server (NTRS)

    Christensen, Andrew B.

    1995-01-01

    This report covers the activities performed under NAS5-32572. The results of those activities are included in this Final Report. TIMED Science Objectives: (1) To determine the temperature, density, and wind structure of the MLTI (mixed layer thermal inertia), including the seasonal and latitudinal variations; and (2) To determine the relative importance of the various radiative, chemical, electrodynamical, and dynamical sources and sinks of energy for the thermal structure of the MLTI. GUVI Science Goals: (1) Determine the spatial and temporal variations of temperature and constituent densities in the lower thermosphere; and (2) Determine the importance of auroral energy sources and solar EUV (extreme ultraviolet) to the energy balance of the region.

  18. International ultraviolet explorer observatory operations

    NASA Technical Reports Server (NTRS)

    1986-01-01

    This volume contains the Final Report for the International Ultraviolet Explorer (IUE) Observatory Operations contract, NAS5-28787. The report summarizes the activities of the IUE Observatory over the 13-month period from November 1985 through November 1986 and is arranged in sections according to the functions specified in the Statement of Work (SOW) of the contract. In order to preserve numerical correspondence between the technical SOW elements specified by the contract and the sections of this report, project management activities (SOW element 0.0.) are reported here in Section 7, following the reports of technical SOW elements 1.0 through 6.0. Routine activities have been summarized briefly whenever possible; statistical compilations, reports, and more lengthy supplementary material are contained in the Appendices.

  19. Ultraviolet, Visible, and Fluorescence Spectroscopy

    NASA Astrophysics Data System (ADS)

    Penner, Michael H.

    Spectroscopy in the ultraviolet-visible (UV-Vis) range is one of the most commonly encountered laboratory techniques in food analysis. Diverse examples, such as the quantification of macrocomponents (total carbohydrate by the phenol-sulfuric acid method), quantification of microcomponents, (thiamin by the thiochrome fluorometric procedure), estimates of rancidity (lipid oxidation status by the thiobarbituric acid test), and surveillance testing (enzyme-linked immunoassays), are presented in this text. In each of these cases, the analytical signal for which the assay is based is either the emission or absorption of radiation in the UV-Vis range. This signal may be inherent in the analyte, such as the absorbance of radiation in the visible range by pigments, or a result of a chemical reaction involving the analyte, such as the colorimetric copper-based Lowry method for the analysis of soluble protein.

  20. The ultraviolet astronomy mission: Columbus

    NASA Technical Reports Server (NTRS)

    Wilson, R.

    1984-01-01

    An ultraviolet astronomy mission (Columbus) is described. It exploits the spectral region between 900 and 1200A, which is extremely rich in containing the Lyman lines of hydrogen and deuterium and the Lyman band of their molecules, together with the resonance lines of many important ions. High resolving power and high sensitivity provide a unique capability for studying the brightest members of neighboring galaxies, the HeI and HeII absorption systems in quasars out to a red shift of 2, and the halos of intervening galaxies. Complementary focal plane instruments are planned in order to allow observations to longer (2000A) and shorter (100A) wavelengths. This wide coverage embraces the resonance lines of all the cosmically abundant elements and a wide range of temperature zones up to 100 million K.

  1. Ultraviolet spectroscopy of cometary comae

    NASA Technical Reports Server (NTRS)

    Feldman, Paul D.

    1991-01-01

    During the past decade, vacuum ultraviolet spectra of over 30 comets have been obtained with the IUE satellite observatory. With few exceptions, the spectra of these comets appear to be similar, with OH and H produced by the photodissociation of water being the dominant species and emissions of C, O, S, CS and CO2(+) usually present. Although signs of variabiity of many kinds in comet spectra appear, the evidence from the UV observations suggests that all comets have the same basic chemical composition and that observed differences are due to evolution and ageing processes. During the 1985-86 apparition of Comet Halley, spectra were also obtained by other spacecraft and by sounding rocket instruments, including a long-slit imaging spectrograph.

  2. The calibration of read-out-streak photometry in the XMM-Newton Optical Monitor and the construction of a bright-source catalogue

    NASA Astrophysics Data System (ADS)

    Page, M. J.; Chan, N.; Breeveld, A. A.; Talavera, A.; Yershov, V.; Kennedy, T.; Kuin, N. P. M.; Hancock, B.; Smith, P. J.; Carter, M.

    2017-04-01

    The dynamic range of the XMM-Newton Optical Monitor (XMM-OM) is limited at the bright end by coincidence loss, the superposition of multiple photons in the individual frames recorded from its micro-channel-plate (MCP) intensified charge-coupled device (CCD) detector. One way to overcome this limitation is to use photons that arrive during the frame transfer of the CCD, forming vertical read-out streaks for bright sources. We calibrate these read-out streaks for photometry of bright sources observed with XMM-OM. The bright-source limit for read-out-streak photometry is set by the recharge time of the MCPs. For XMM-OM, we find that the MCP recharge time is 5.5 × 10-4 s. We determine that the effective bright limits for read-out-streak photometry with XMM-OM are approximately 1.5 mag brighter than the bright-source limits for normal aperture photometry in full-frame images. This translates into bright-source limits in Vega magnitudes of UVW2=7.1, UVM2=8.0, UVW1=9.4, U=10.5, B=11.5, V=10.2, and White=12.5 for data taken early in the mission. The limits brighten by up to 0.2 mag, depending on filter, over the course of the mission as the detector ages. The method is demonstrated by deriving UVW1 photometry for the symbiotic nova RR Telescopii, and the new photometry is used to constrain the e-folding time of its decaying ultraviolet (UV) emission. Using the read-out-streak method, we obtain photometry for 50 per cent of the missing UV source measurements in version 2.1 of the XMM-Newton Serendipitous UV Source Survey catalogue.

  3. The variation of Io's auroral footprint brightness with the location of Io in the plasma torus

    NASA Astrophysics Data System (ADS)

    Serio, Andrew W.; Clarke, John T.

    2008-09-01

    Ultraviolet and near-infrared observations of auroral emissions from the footprint of Io's magnetic Flux Tube (IFT) mapping to Jupiter's ionosphere have been interpreted via a combination of the unipolar inductor model [Goldreich, P., Lynden-Bell, D., 1969. Astrophys. J. 156, 59-78] and the multiply-reflected Alfvén wave model [ Belcher, J.W., 1987. Science 238, 170-176]. While both models successfully explain the general nature of the auroral footprint and corotational wake, and both predict the presence of multiple footprints, the details of the interaction near Io are complicated [ Saur, J., Neubauer, F.M., Connerney, J.E.P., Zarka, P., Kivelson, M.G., 2004. In: Bagenal, F., Dowling, T.E., McKinnon, W.B. (Eds.), Jupiter: The Planet, Satellites and Magnetosphere. Cambridge University Press, Cambridge, UK, pp. 537-560; Kivelson, M.G., Bagenal, F., Kurth, W.S., Neubauer, F.M., Paranicas, C., Saur, J., 2004. In: Bagenal, F., Dowling, T.E., McKinnon, W.B. (Eds.), Jupiter: The Planet, Satellites and Magnetosphere. Cambridge University Press, Cambridge, UK, pp. 513-536]. The auroral footprint brightness is believed to be a good remote indicator of the strength of the interaction near Io, indicating the energy and current strength linking Io with Jupiter's ionosphere. The brightness may also depend in part on local auroral acceleration processes near Jupiter. The relative importance of different physical processes in this interaction can be tested as Jupiter's rotation and Io's orbital motion shift Jupiter's magnetic centrifugal equator past Io, leading to longitudinal variations in the plasma density near Io and functionally different variations in the local field strength near Jupiter where the auroral emissions are produced. Initial HST WFPC2 observations found a high degree of variability in the footprint brightness with time, and some evidence for systematic variations with longitude [Clarke, J.T., Ben Jaffel, L., Gérard, J.-C., 1998. J. Geophys. Res. 103, 20217

  4. Ultraviolet spectrometer observations of uranus.

    PubMed

    Broadfoot, A L; Herbert, F; Holberg, J B; Hunten, D M; Kumar, S; Sandel, B R; Shemansky, D E; Smith, G R; Yelle, R V; Strobel, D F; Moos, H W; Donahue, T M; Atreya, S K; Bertaux, J L; Blamont, J E; McConnell, J C; Dessler, A J; Linick, S; Springer, R

    1986-07-04

    Data from solar and stellar occultations of Uranus indicate a temperature of about 750 kelvins in the upper levels of the atmosphere (composed mostly of atomic and molecular hydrogen) and define the distributions of methane and acetylene in the lower levels. The ultraviolet spectrum of the sunlit hemisphere is dominated by emissions from atomic and molecular hydrogen, which are kmown as electroglow emissions. The energy source for these emissions is unknown, but the spectrum implies excitation by low-energy electrons (modeled with a 3-electron-volt Maxwellian energy distribution). The major energy sink for the electrons is dissociation of molecular hydrogen, producing hydrogen atoms at a rate of 10(29) per second. Approximately half the atoms have energies higher than the escape energy. The high temperature of the atmosphere, the small size of Uranus, and the number density of hydrogen atoms in the thermosphere imply an extensive thermal hydrogen corona that reduces the orbital lifetime of ring particles and biases the size distribution toward larger particles. This corona is augmented by the nonthermal hydrogen atoms associated with the electroglow. An aurora near the magnetic pole in the dark hemisphere arises from excitation of molecular hydrogen at the level where its vertical column abundance is about 10(20) per square centimeter with input power comparable to that of the sunlit electroglow (approximately 2x10(11) watts). An initial estimate of the acetylene volume mixing ratio, as judged from measurements of the far ultraviolet albedo, is about 2 x 10(-7) at a vertical column abundance of molecular hydrogen of 10(23) per square centimeter (pressure, approximately 0.3 millibar). Carbon emissions from the Uranian atmosphere were also detected.

  5. The Ultraviolet Radiation Environment around M Dwarf Exoplanet Host Stars

    NASA Technical Reports Server (NTRS)

    France, Kevin; Froning, Cynthia S.; Linsky, Jeffrey L.; Roberge, Aki; Stocke, John T.; Tian, Feng; Bushinsky, Rachel; Desert, Jean-Michel; Mauas, Pablo; Mauas, Pablo; Walkowicz, Lucianne M.

    2013-01-01

    The spectral and temporal behavior of exoplanet host stars is a critical input to models of the chemistry and evolution of planetary atmospheres. Ultraviolet photons influence the atmospheric temperature profiles and production of potential biomarkers on Earth-like planets around these stars. At present, little observational or theoretical basis exists for understanding the ultraviolet spectra of M dwarfs, despite their critical importance to predicting and interpreting the spectra of potentially habitable planets as they are obtained in the coming decades. Using observations from the Hubble Space Telescope, we present a study of the UV radiation fields around nearby M dwarf planet hosts that covers both far-UV (FUV) and near-UV (NUV) wavelengths. The combined FUV+NUV spectra are publicly available in machine-readable format. We find that all six exoplanet host stars in our sample (GJ 581, GJ 876, GJ 436, GJ 832, GJ 667C, and GJ 1214) exhibit some level of chromospheric and transition region UV emission. No "UV-quiet" M dwarfs are observed. The bright stellar Lyman-alpha emission lines are reconstructed, and we find that the Lyman-alpha line fluxes comprise approximately 37%-75% of the total 1150-3100 A flux from most M dwarfs; approximately greater than 10(exp3) times the solar value. We develop an empirical scaling relation between Lyman-alpha and Mg II emission, to be used when interstellar H I attenuation precludes the direct observation of Lyman-alpha. The intrinsic unreddened flux ratio is F(Lyman-alpha)/F(Mg II) = 10(exp3). The F(FUV)/F(NUV) flux ratio, a driver for abiotic production of the suggested biomarkers O2 and O3, is shown to be approximately 0.5-3 for all M dwarfs in our sample, greather than 10(exp3) times the solar ratio. For the four stars with moderate signal-to-noise Cosmic Origins Spectrograph time-resolved spectra, we find UV emission line variability with amplitudes of 50%.500% on 10(exp2)-10(exp3) s timescales. This effect should be taken

  6. THE ULTRAVIOLET RADIATION ENVIRONMENT AROUND M DWARF EXOPLANET HOST STARS

    SciTech Connect

    France, Kevin; Froning, Cynthia S.; Stocke, John T.; Bushinsky, Rachel; Linsky, Jeffrey L.; Roberge, Aki; Tian, Feng; Desert, Jean-Michel; Mauas, Pablo; Vieytes, Mariela; Walkowicz, Lucianne M.

    2013-02-15

    The spectral and temporal behavior of exoplanet host stars is a critical input to models of the chemistry and evolution of planetary atmospheres. Ultraviolet photons influence the atmospheric temperature profiles and production of potential biomarkers on Earth-like planets around these stars. At present, little observational or theoretical basis exists for understanding the ultraviolet spectra of M dwarfs, despite their critical importance to predicting and interpreting the spectra of potentially habitable planets as they are obtained in the coming decades. Using observations from the Hubble Space Telescope, we present a study of the UV radiation fields around nearby M dwarf planet hosts that covers both far-UV (FUV) and near-UV (NUV) wavelengths. The combined FUV+NUV spectra are publicly available in machine-readable format. We find that all six exoplanet host stars in our sample (GJ 581, GJ 876, GJ 436, GJ 832, GJ 667C, and GJ 1214) exhibit some level of chromospheric and transition region UV emission. No 'UV-quiet' M dwarfs are observed. The bright stellar Ly{alpha} emission lines are reconstructed, and we find that the Ly{alpha} line fluxes comprise {approx}37%-75% of the total 1150-3100 A flux from most M dwarfs; {approx}>10{sup 3} times the solar value. We develop an empirical scaling relation between Ly{alpha} and Mg II emission, to be used when interstellar H I attenuation precludes the direct observation of Ly{alpha}. The intrinsic unreddened flux ratio is F(Ly{alpha})/F(Mg II) = 10 {+-} 3. The F(FUV)/F(NUV) flux ratio, a driver for abiotic production of the suggested biomarkers O{sub 2} and O{sub 3}, is shown to be {approx}0.5-3 for all M dwarfs in our sample, >10{sup 3} times the solar ratio. For the four stars with moderate signal-to-noise Cosmic Origins Spectrograph time-resolved spectra, we find UV emission line variability with amplitudes of 50%-500% on 10{sup 2}-10{sup 3} s timescales. This effect should be taken into account in future UV transiting

  7. The Mystery of the Cosmic Diffuse Ultraviolet Background Radiation

    NASA Astrophysics Data System (ADS)

    Henry, Richard Conn; Murthy, Jayant; Overduin, James; Tyler, Joshua

    2015-01-01

    The diffuse cosmic background radiation in the Galaxy Evolution Explorer far-ultraviolet (FUV, 1300-1700 Å) is deduced to originate only partially in the dust-scattered radiation of FUV-emitting stars: the source of a substantial fraction of the FUV background radiation remains a mystery. The radiation is remarkably uniform at both far northern and far southern Galactic latitudes and increases toward lower Galactic latitudes at all Galactic longitudes. We examine speculation that this might be due to interaction of the dark matter with the nuclei of the interstellar medium, but we are unable to point to a plausible mechanism for an effective interaction. We also explore the possibility that we are seeing radiation from bright FUV-emitting stars scattering from a "second population" of interstellar grains—grains that are small compared with FUV wavelengths. Such grains are known to exist, and they scatter with very high albedo, with an isotropic scattering pattern. However, comparison with the observed distribution (deduced from their 100 μm emission) of grains at high Galactic latitudes shows no correlation between the grains' location and the observed FUV emission. Our modeling of the FUV scattering by small grains also shows that there must be remarkably few such "smaller" grains at high Galactic latitudes, both north and south; this likely means simply that there is very little interstellar dust of any kind at the Galactic poles, in agreement with Perry and Johnston. We also review our limited knowledge of the cosmic diffuse background at ultraviolet wavelengths shortward of Lyα—it could be that our "second component" of the diffuse FUV background persists shortward of the Lyman limit and is the cause of the reionization of the universe.

  8. THE ABSOLUTE MAGNITUDES OF TYPE Ia SUPERNOVAE IN THE ULTRAVIOLET

    SciTech Connect

    Brown, Peter J.; Roming, Peter W. A.; Ciardullo, Robin; Gronwall, Caryl; Hoversten, Erik A.; Pritchard, Tyler; Milne, Peter; Bufano, Filomena; Mazzali, Paolo; Elias-Rosa, Nancy; Filippenko, Alexei V.; Li Weidong; Foley, Ryan J.; Hicken, Malcolm; Kirshner, Robert P.; Gehrels, Neil; Holland, Stephen T.; Immler, Stefan; Phillips, Mark M.; Still, Martin

    2010-10-01

    We examine the absolute magnitudes and light-curve shapes of 14 nearby (redshift z = 0.004-0.027) Type Ia supernovae (SNe Ia) observed in the ultraviolet (UV) with the Swift Ultraviolet/Optical Telescope. Colors and absolute magnitudes are calculated using both a standard Milky Way extinction law and one for the Large Magellanic Cloud that has been modified by circumstellar scattering. We find very different behavior in the near-UV filters (uvw1{sub rc} covering {approx}2600-3300 A after removing optical light, and u {approx} 3000-4000 A) compared to a mid-UV filter (uvm2 {approx}2000-2400 A). The uvw1{sub rc} - b colors show a scatter of {approx}0.3 mag while uvm2-b scatters by nearly 0.9 mag. Similarly, while the scatter in colors between neighboring filters is small in the optical and somewhat larger in the near-UV, the large scatter in the uvm2 - uvw1 colors implies significantly larger spectral variability below 2600 A. We find that in the near-UV the absolute magnitudes at peak brightness of normal SNe Ia in our sample are correlated with the optical decay rate with a scatter of 0.4 mag, comparable to that found for the optical in our sample. However, in the mid-UV the scatter is larger, {approx}1 mag, possibly indicating differences in metallicity. We find no strong correlation between either the UV light-curve shapes or the UV colors and the UV absolute magnitudes. With larger samples, the UV luminosity might be useful as an additional constraint to help determine distance, extinction, and metallicity in order to improve the utility of SNe Ia as standardized candles.

  9. Four-wave mixing experiments with extreme ultraviolet transient gratings

    NASA Astrophysics Data System (ADS)

    Bencivenga, F.; Cucini, R.; Capotondi, F.; Battistoni, A.; Mincigrucci, R.; Giangrisostomi, E.; Gessini, A.; Manfredda, M.; Nikolov, I. P.; Pedersoli, E.; Principi, E.; Svetina, C.; Parisse, P.; Casolari, F.; Danailov, M. B.; Kiskinova, M.; Masciovecchio, C.

    2015-04-01

    Four-wave mixing (FWM) processes, based on third-order nonlinear light-matter interactions, can combine ultrafast time resolution with energy and wavevector selectivity, and enable the exploration of dynamics inaccessible by linear methods. The coherent and multi-wave nature of the FWM approach has been crucial in the development of advanced technologies, such as silicon photonics, subwavelength imaging and quantum communications. All these technologies operate at optical wavelengths, which limits the spatial resolution and does not allow the probing of excitations with energy in the electronvolt range. Extension to shorter wavelengths--that is, the extreme ultraviolet and soft-X-ray ranges--would allow the spatial resolution to be improved and the excitation energy range to be expanded, as well as enabling elemental selectivity to be achieved by exploiting core resonances. So far, FWM applications at such wavelengths have been prevented by the absence of coherent sources of sufficient brightness and of suitable experimental set-ups. Here we show how transient gratings, generated by the interference of coherent extreme-ultraviolet pulses delivered by the FERMI free-electron laser, can be used to stimulate FWM processes at suboptical wavelengths. Furthermore, we have demonstrated the possibility of observing the time evolution of the FWM signal, which shows the dynamics of coherent excitations as molecular vibrations. This result opens the way to FWM with nanometre spatial resolution and elemental selectivity, which, for example, would enable the investigation of charge-transfer dynamics. The theoretical possibility of realizing these applications has already stimulated ongoing developments of free-electron lasers: our results show that FWM at suboptical wavelengths is feasible, and we hope that they will enable advances in present and future photon sources.

  10. Four-wave mixing experiments with extreme ultraviolet transient gratings.

    PubMed

    Bencivenga, F; Cucini, R; Capotondi, F; Battistoni, A; Mincigrucci, R; Giangrisostomi, E; Gessini, A; Manfredda, M; Nikolov, I P; Pedersoli, E; Principi, E; Svetina, C; Parisse, P; Casolari, F; Danailov, M B; Kiskinova, M; Masciovecchio, C

    2015-04-09

    Four-wave mixing (FWM) processes, based on third-order nonlinear light-matter interactions, can combine ultrafast time resolution with energy and wavevector selectivity, and enable the exploration of dynamics inaccessible by linear methods. The coherent and multi-wave nature of the FWM approach has been crucial in the development of advanced technologies, such as silicon photonics, subwavelength imaging and quantum communications. All these technologies operate at optical wavelengths, which limits the spatial resolution and does not allow the probing of excitations with energy in the electronvolt range. Extension to shorter wavelengths--that is, the extreme ultraviolet and soft-X-ray ranges--would allow the spatial resolution to be improved and the excitation energy range to be expanded, as well as enabling elemental selectivity to be achieved by exploiting core resonances. So far, FWM applications at such wavelengths have been prevented by the absence of coherent sources of sufficient brightness and of suitable experimental set-ups. Here we show how transient gratings, generated by the interference of coherent extreme-ultraviolet pulses delivered by the FERMI free-electron laser, can be used to stimulate FWM processes at suboptical wavelengths. Furthermore, we have demonstrated the possibility of observing the time evolution of the FWM signal, which shows the dynamics of coherent excitations as molecular vibrations. This result opens the way to FWM with nanometre spatial resolution and elemental selectivity, which, for example, would enable the investigation of charge-transfer dynamics. The theoretical possibility of realizing these applications has already stimulated ongoing developments of free-electron lasers: our results show that FWM at suboptical wavelengths is feasible, and we hope that they will enable advances in present and future photon sources.

  11. THE MYSTERY OF THE COSMIC DIFFUSE ULTRAVIOLET BACKGROUND RADIATION

    SciTech Connect

    Henry, Richard Conn; Murthy, Jayant; Overduin, James; Tyler, Joshua E-mail: jmurthy@yahoo.com E-mail: 97tyler@cardinalmail.cua.edu

    2015-01-01

    The diffuse cosmic background radiation in the Galaxy Evolution Explorer far-ultraviolet (FUV, 1300-1700 Å) is deduced to originate only partially in the dust-scattered radiation of FUV-emitting stars: the source of a substantial fraction of the FUV background radiation remains a mystery. The radiation is remarkably uniform at both far northern and far southern Galactic latitudes and increases toward lower Galactic latitudes at all Galactic longitudes. We examine speculation that this might be due to interaction of the dark matter with the nuclei of the interstellar medium, but we are unable to point to a plausible mechanism for an effective interaction. We also explore the possibility that we are seeing radiation from bright FUV-emitting stars scattering from a ''second population'' of interstellar grains—grains that are small compared with FUV wavelengths. Such grains are known to exist, and they scatter with very high albedo, with an isotropic scattering pattern. However, comparison with the observed distribution (deduced from their 100 μm emission) of grains at high Galactic latitudes shows no correlation between the grains' location and the observed FUV emission. Our modeling of the FUV scattering by small grains also shows that there must be remarkably few such ''smaller'' grains at high Galactic latitudes, both north and south; this likely means simply that there is very little interstellar dust of any kind at the Galactic poles, in agreement with Perry and Johnston. We also review our limited knowledge of the cosmic diffuse background at ultraviolet wavelengths shortward of Lyα—it could be that our ''second component'' of the diffuse FUV background persists shortward of the Lyman limit and is the cause of the reionization of the universe.

  12. PULSE: the Palomar Ultraviolet Laser for the Study of Exoplanets

    NASA Astrophysics Data System (ADS)

    Bottom, Michael; Dekany, R.; Bowler, B. P.; Baranec, C.; Burruss, R.

    2014-01-01

    PULSE is a project to augment the currently operating 5.1-m Hale PALM-3000 exoplanet adaptive optics system with an ultraviolet Rayleigh laser and associated wavefront sensor. By using a bright (U ~ 7) ultraviolet laser to measure the high spatial and temporal order turbulence near the telescope aperture, where it dominates, one can extend the faintness limit of natural guide stars needed by PALM-3000. Initial simulations indicate that very-high infrared contrast ratios and good visible-light adaptive optics performance will be achieved by such an upgraded system on stars as faint as mV = 16-17 using an optimized low-order NGS sensor. This will enable direct imaging searches for, and subsequent characterization of, companions around cool, low-mass stars for the first time, as well as routine visible-light imaging twice as sharp as HST for fainter targets. PULSE will reuse the laser and wavefront sensor technology developed for the automated Robo-AO laser system currently operating at the Palomar 60-inch telescope, as well as take advantage of pending optimization of low-order NGS wavefront sensing and planned new interfaces to the PALM-3000 real-time reconstruction computer. PULSE will dramatically extend the AO sky coverage of the telescope from 1% to 50%. More specifically, this will boost the yield from a number of operational exoplanet instruments at Palomar including PHARO, a NIR imager, spectrograph, and coronagraph; a fiber nulling interferometer; and Project 1640, a coronagraph and IFS. Two additional funded instruments expected to benefit from PULSE in the coming years are the SDC; a NIR/visible self-calibrating vector vortex coronagraph, and DARKNESS; an energy-resolving, photon counting MKIDS camera.

  13. Impact of snow on surface brightness

    NASA Astrophysics Data System (ADS)

    Kukla, George J.; Brown, Jeffrey A.

    The snow-covered land surface has different albedo than the snow-free surface, depending primarily on the type and density of the vegetation, the relief, and the continuity and age of the snow blanket. This is clearly demonstrated by the winter mosaic of east central Asia shown on the front cover. It is a section of a larger composite assembled from cloud-free satellite images to portray the land surface under continuous snow cover. The mosaic is a valuable tool for distinguishing (from remote positions) snow from clouds and for charting snow cover where illumination is poor. It also can be used to determine relative sensitivity of surface albedo to the occurrence of snow.Segments with a minimum of clouds along the orbital subtrack were selected from the transparencies of the Defense Meteorological Satellite Program (DMSP). Satellite sensors record in the spectral band 0.4-1.2 µm. The satellite is in polar orbit at a mean altitude of 830 km (450 nm) and crosses the equator at approximately local noon. The spatial resolution along the orbital subtrack is about 0.6 km [Dickinson et al., 1974]. The mosaic is assembled from imagery taken between mid-January and mid-February of 1979. The original hard-copy transparencies (on loan from the DMSP library) were reproduced as contact negatives to preserve detail.The snow cover marks the land surface with a characteristic signature that depends on the distribution, density, and type of vegetation; relief; presence of water bodies; distribution and type of land use, etc. This signature can be readily utilized, among others, to distinguish snow-covered land from clouds and from snow-free land [Barnes et al., 1974; Lillesand et al., 1982]. We have compared the brightness fields in the imagery with the vegetation density and land-use patterns charted in the World Forestry Atlas [Wiebecke, 1971].

  14. Dark Skies, Bright Kids! Year 5

    NASA Astrophysics Data System (ADS)

    Prager, Brian; Johnson, K. E.; Barcos-Munoz, L. D.; Beaton, R.; Bittle, L.; Borish, H.; Burkhardt, A.; Corby, J.; Damke, G.; Dean, J.; Dorsey, G.; Graninger, D.; Lauck, T.; Liss, S.; Oza, A.; Peacock, S.; Romero, C.; Sokal, K. R.; Stierwalt, S.; Walker, L.; Wenger, T.; Zucker, C.

    2014-01-01

    Our public outreach group Dark Skies, Bright Kids! (DSBK) fosters science literacy in Virginia by bringing a hands-on approach to astronomy that engages children's natural excitement and curiosity. We are an entirely volunteer-run group based out of the Department of Astronomy at the University of Virginia and we enthusiastically utilize astronomy as a 'gateway science.' We create long-term relationships with students during an 8 to 10 week long, after-school astronomy club at under served elementary schools in neighboring counties, and we visited 3 different schools in 2013. Additionally, we organize and participate in science events throughout the community. The fifth year of DSBK was marked by surpassing 10,000 contact hours in Spring 2013 Semester and by ringing in the fall semester with our biggest, most successful star party to date. We hosted the Third Annual Central Virginia Star Party, free and open to the community to encourage families to enjoy astronomy together. Nearly four hundred people of all ages attended, double the number from previous years. Joining with local astronomical societies, we offered an enlightening and exciting night with resources rarely accessible to the public, such as an IR camera and a portable planetarium. With numerous telescopes pointed at the sky, and a beautifully clear night with views of the Milky Way, the International Space Station, and numerous meteors, the star party was a fantastic opportunity to introduce many of our guests to the natural wonders of our night sky and enjoy some of the darkest skies on the eastern seaboard.

  15. All Bright Cold Classical KBOs are Binary

    NASA Astrophysics Data System (ADS)

    Noll, Keith S.; Parker, Alex H.; Grundy, William M.

    2014-11-01

    When sorted by absolute magnitude as seen in ground based observations, an extremely high fraction of the brightest Cold Classical (CC) Kuiper Belt objects (KBO) are, in fact resolved as binaries when observed at higher angular resolution. Of the 22 CCs brighter than H=6.1 observed by HST, 16 have been found to be binary yielding a binary fraction of 73±10%. When low inclination interlopers from the hot population and close binaries are considered, this very high fraction is consistent with 100% of bright CCs being binary. At fainter absolute magnitudes, this fraction drops to ~20%. Such a situation is a natural outcome of a broken size distribution with a steep drop-off in the number of CCs with individual component diameters larger than 150 km (for an assumed albedo of 0.15). A sharp cutoff in the size distribution for CCs is consistent with formation models that suggest that most planetesimals form at a preferred modal size of order 100 km.The very high fraction of binaries among the largest CCs also serves to limit the separation distribution of KBO binaries. At most, 27% of the brightest CCs are possible unresolved binaries. The apparent power law distribution of binary separation must cut off near the current observational limits of HST ( 1800 km at 43 AU). It is worth noting, however, that this observation does not constrain how many components of resolved binaries may themselves be unresolved multiples like 47171 1999 TC36. Finally, it is important to point out that, when sorted by the size of the primary rather than absolute magnitude of the unresolved pair, the fraction of binaries is relatively constant with size (Nesvorny et al. 2011, AJ 141, 159) eliminating observational bias as cause of the pile up of binaries among the brightest Cold Classical Kuiper Belt objects.The very high fraction of binaries among the brightest CCs appears to be an effect of the underlying CC size distribution.

  16. Chromospheric evaporation in sympathetic coronal bright points

    NASA Astrophysics Data System (ADS)

    Zhang, Q. M.; Ji, H. S.

    2013-09-01

    Context. Chromospheric evaporation is a key process in solar flares that has been extensively investigated using spectroscopic observations. However, direct soft X-ray (SXR) imaging of the process is rare, especially in remote brightenings associated with the primary flares that have recently attracted a great deal of attention. Aims: We intend to find the evidence for chromospheric evaporation and figure out the cause of the process in sympathetic coronal bright points (CBPs), i.e., remote brightenings induced by the primary CBP. Methods: We utilised the high-cadence and high-resolution SXR observations of CBPs from the X-ray Telescope (XRT) aboard the Hinode spacecraft on 2009 August 23. Results: We discovered a thermal conduction front propagating from the primary CBP (hereafter BP1) to the first of the sympathetic CBPs (hereafter BP2) that is 60″ away from BP1. The apparent velocity of the thermal conduction is ~138 km s-1. Afterwards, hot plasma flowed upwards into the loop connecting BP1 and BP2 at a speed of ~76 km s-1, a clear signature of chromospheric evaporation. Similar upflow was also observed in the loop connecting BP1 and the other sympathetic CBP (hereafter BP3) that is 80″ away from BP1, though less significant than BP2. The apparent velocity of the upflow is ~47 km s-1. The thermal conduction front propagating from BP1 to BP3 was not well identified except for the jet-like motion also originating from BP1. Conclusions: We propose that the gentle chromospheric evaporation in the sympathetic CBPs were caused by thermal conduction originating from the primary CBP.

  17. Bright Times for an Ancient Star

    NASA Astrophysics Data System (ADS)

    Fuhrmann, K.; Chini, R.

    2017-01-01

    Field stars of Population II are among the oldest sources in the Galaxy. Most of their solar-type dwarfs are non-single and, given their extreme age, a significant fraction is accompanied by stellar remnants. Here we report the discovery of the bright F7V star 49 Lib as a massive and very metal-rich Population II field blue straggler, along with evidence for a white dwarf as its dark and unseen companion. 49 Lib is known as a relatively fast-rotating, single-lined spectroscopic binary in a 3 year orbit and with an apparent age of about τ ≃ 2.3 Gyr. Its chemistry and kinematics, however, both consistently imply that 49 Lib must be an ancient Population II star at τ ≃ 12 Gyr. With reference to the inclination from the astrometric orbit, leading to a {M}{WD}={0.50}-0.04+0.03 M⊙ low-mass white dwarf, and in view of the {M}{BS}={1.55}-0.13+0.07 M⊙ massive, evolved F-type blue straggler star, we demonstrate that 49 Lib must have been the subject of a mostly conservative mass transfer with a near-equal-mass M ≃ 1.06 + 1.00 M⊙ G-type binary at birth. For its future evolution, we point to the possibility as a progenitor system toward a type Ia supernova. Most importantly, however, we note that the remarkable metal enrichment of 49 Lib at [Mg/H] = +0.23 and [Fe/H] = ‑0.11 has principally very relevant implications for the early epoch when the Milky Way came into being.

  18. MAGNETIC FLUX SUPPLEMENT TO CORONAL BRIGHT POINTS

    SciTech Connect

    Mou, Chaozhou; Huang, Zhenghua; Xia, Lidong; Li, Bo; Fu, Hui; Jiao, Fangran; Hou, Zhenyong; Madjarska, Maria S.

    2016-02-10

    Coronal bright points (BPs) are associated with magnetic bipolar features (MBFs) and magnetic cancellation. Here we investigate how BP-associated MBFs form and how the consequent magnetic cancellation occurs. We analyze longitudinal magnetograms from the Helioseismic and Magnetic Imager to investigate the photospheric magnetic flux evolution of 70 BPs. From images taken in the 193 Å passband of the Atmospheric Imaging Assembly (AIA) we dermine that the BPs’ lifetimes vary from 2.7 to 58.8 hr. The formation of the BP MBFs is found to involve three processes, namely, emergence, convergence, and local coalescence of the magnetic fluxes. The formation of an MBF can involve more than one of these processes. Out of the 70 cases, flux emergence is the main process of an MBF buildup of 52 BPs, mainly convergence is seen in 28, and 14 cases are associated with local coalescence. For MBFs formed by bipolar emergence, the time difference between the flux emergence and the BP appearance in the AIA 193 Å passband varies from 0.1 to 3.2 hr with an average of 1.3 hr. While magnetic cancellation is found in all 70 BPs, it can occur in three different ways: (I) between an MBF and small weak magnetic features (in 33 BPs); (II) within an MBF with the two polarities moving toward each other from a large distance (34 BPs); (III) within an MBF whose two main polarities emerge in the same place simultaneously (3 BPs). While an MBF builds up the skeleton of a BP, we find that the magnetic activities responsible for the BP heating may involve small weak fields.

  19. Dark Skies, Bright Kids! Year 3

    NASA Astrophysics Data System (ADS)

    Whelan, David G.; Johnson, K. E.; Barcos-Munoz, L. D.; Beaton, R. L.; Borish, J.; Corby, J. F.; Dorsey, G.; Gugliucci, N. E.; Prager, B. J.; Ries, P. A.; Romero, C. E.; Sokal, K. R.; Tang, X.; Walker, L. M.; Yang, A. J.; Zasowski, G.

    2012-01-01

    Dark Skies, Bright Kids! (DSBK) is a program that brings astronomy education to elementary schools throughout central Virginia. In a relaxed, out-of-classroom atmosphere, we are able to foster the innate curiosity that young students have about science and the world around them. We target schools that are under-served due to their rural locale or special needs students, demonstrating that science is a fun and creative process to a segment of the population that might not otherwise be exposed to astronomy. Families are included in the learning experience during semi-annual `star parties'. Since last January, we have expanded the breadth and depth of our educational capabilities. We have developed new programs for use in our digital planetarium. We held the first Central Virginia Star Party, providing an atmosphere where local children from multiple schools were able to share their love for astronomy. Local government and University officials were also invited so that they could experience our focused science outreach. Most recently, we have become part of Ivy Creek School's Club Day activities, bringing our program to a new segment of the elementary school system in Albemarle County: those that have `low-incidence' disabilities, requiring special attention. We continue to develop a curriculum for after-school programs that functions as either a series of one-time activities or several months of focused outreach at one school. Many of these activities are provided on our website, http://www.astro.virginia.edu/dsbk/, for the wider astronomical community, including the new planetarium work. We have extended our book project to include two bilingual astronomy books called `Snapshots of the Universe,' one in Spanish and English, the other in French and English. These books introduce young people to some of the many wonders of the Universe through art and captions developed by DSBK volunteers.

  20. Dark Skies, Bright Kids! Year 4

    NASA Astrophysics Data System (ADS)

    Sokal, Kimberly R.; Johnson, K. E.; Barcos-Munoz, L. D.; Beaton, R.; Borish, J.; Crawford, S. B.; Corby, J.; Damke, G.; Dean, J.; Dorsey, G.; Jackson, L.; Liss, S.; Oza, A.; Peacock, S.; Prager, B.; Romero, C.; Sivakoff, G. R.; Walker, L.; Whelan, D. G.; Zucker, C.

    2013-01-01

    Aiming to engage young children's natural excitement and curiosity, the outreach group Dark Skies, Bright Kids (DSBK) brings a hands-on approach to astronomy to elementary schools in Virginia. We hope to enhance children's view and understanding of science while exploring the Universe using fun activities. DSBK focuses on rural and underserved schools in Albemarle County and offers a semester-long astronomy club for third through fifth grade students. We believe regular interactions foster personal relationships between students and volunteers that encourage a life-long interest in science. In our fourth year of hosting clubs, we returned to Ivy Creek Elementary School, where we saw wonderful responses from a special group of students with `low-incidence' disabilities. DSBK has grown to realize a broader reach beyond local astronomy clubs; we hope to ignite a spark of interest in astronomy and science more widely- in more children, their families, and their teachers. We also hosted the Second Annual Central Virginia Star Party with an open invitation to the community to encourage families to enjoy astronomy together. Throughout the year, DSBK now holds 'one-off' programs (akin to astronomy field days) for elementary schools and children's groups throughout Virginia. Furthermore, we are in the final stages of a project to create two bilingual astronomy books called "Snapshots of the Universe", in Spanish and French with English translations. This art book will be made available online and we are working to get a copy in every elementary school in the state. DSBK has begun to reach out to elementary school teachers in order to provide them with useful and engaging classroom material. We have adapted our volunteer-created activities into useful and ready-to-use lessons, available online. After improvements based on research through interactions and feedback from teachers, we have explicitly identified the learning goals in terms of Virginia's Standards of Learning

  1. Dark Skies, Bright Kids: Year 2

    NASA Astrophysics Data System (ADS)

    Carlberg, Joleen K.; Johnson, K.; Lynch, R.; Walker, L.; Beaton, R.; Corby, J.; de Messieres, G.; Drosback, M.; Gugliucci, N.; Jackson, L.; Kingery, A.; Layman, S.; Murphy, E.; Richardson, W.; Ries, P.; Romero, C.; Sivakoff, G.; Sokal, K.; Trammell, G.; Whelan, D.; Yang, A.; Zasowski, G.

    2011-01-01

    The Dark Skies, Bright Kids (DSBK) outreach program brings astronomy education into local elementary schools in central Virginia's Southern Albemarle County through an after-school club. Taking advantage of the unusually dark night skies in the rural countryside, DSBK targets economically disadvantaged schools that tend to be underserved due to their rural locale. The goals of DSBK are to foster children's natural curiosity, demonstrate that science is a fun and creative process, challenge students' conceptions of what a scientist is and does, and teach some basic astronomy. Furthermore, DSBK works to assimilate families into students' education by holding family observing nights at the school. Now in its third semester, DSBK has successfully run programs at two schools with very diverse student populations. Working with these students has helped us to revise our activities and to create new ones. A by-product of our work has been the development of lesson plans, complete with learning goals and detailed instructions, that we make publically available on our website. This year we are expanding our repertoire with our new planetarium, which allows us to visualize topics in novel ways and supplements family observing on cloudy nights. The DSBK volunteers have also created a bilingual astronomy artbook --- designed, written, and illustrated by UVa students --- that we will publish and distribute to elementary schools in Virginia. Our book debuted at the last AAS winter meeting, and since then it has been extensively revised and updated with input from many individuals, including parents, professional educators, and a children's book author. Because the club is currently limited to serving a few elementary schools, this book will be part of our efforts to broaden our impact by bringing astronomy to schools we cannot go to ourselves and reaching out to Spanish-speaking communities at the same time.

  2. Ultraviolet colour opponency in the turtle retina.

    PubMed

    Ventura, D F; Zana, Y; de Souza, J M; DeVoe, R D

    2001-07-01

    We have examined the functional architecture of the turtle Pseudemys scripta elegans retina with respect to colour processing, extending spectral stimulation into the ultraviolet, which has not been studied previously in the inner retina. We addressed two questions. (i) Is it possible to deduce the ultraviolet cone spectral sensitivity function through horizontal cell responses? (ii) Is there evidence for tetrachromatic neural mechanisms, i.e. UV/S response opponency? Using a constant response methodology we have isolated the ultraviolet cone input into the S/LM horizontal cell type and described it in fine detail. Monophasic (luminosity), biphasic L/M (red-green) and triphasic S/LM (yellow-blue) horizontal cells responded strongly to ultraviolet light. The blue-adapted spectral sensitivity function of a S/LM cell peaked in the ultraviolet and could be fitted to a porphyropsin cone template with a peak at 372 nm. In the inner retina eight different combinations of spectral opponency were found in the centre of the receptive field of ganglion cells. Among amacrine cells the only types found were UVSM-L+ and its reverse. One amacrine and four ganglion cells were also opponent in the receptive field surround. UV/S opponency, seen in three different types of ganglion cell, provides a neural basis for discrimination of ultraviolet colours. In conclusion, the results strongly suggest that there is an ultraviolet channel and a neural basis for tetrachromacy in the turtle retina.

  3. Easy way to estimate meteor brightness on TV frames

    NASA Astrophysics Data System (ADS)

    Leonov, V. A.; Bagrov, A. V.

    2016-01-01

    The traditional method of the meteor brightness measurements claims that the meteor brightness is equal to the stellar magnitude of a star that looks like a meteor in the brightest point of its track. This rule was convenient for the comparison of meteor observations by different observers and for the analysis of the brightness distributions of meteors from observed showers. This traditional method suffers from systematic errors, particularly those that arise from using stellar brightness measured in specific spectral wave bands different from the observer's ones, but mainly due to neglecting the influence of the meteor angular velocity on the real meteor brightness. To get a proper estimate of the meteor brightness that is a measure of the ground meteor illumination in the non-systematic units, an observer must take into account that the effective exposition of a meteor image in any resolution element of its track is a few times shorter than the corresponding exposition of a star image in the same frame. We propose a very simple method for improved estimations of meteor brightness by applying a correction to the meteor stellar magnitude obtained within the traditional framework.

  4. Condition-dependent variation in the blue-ultraviolet coloration of a structurally based plumage ornament

    PubMed Central

    Keyser, A. J.; Hill, G. E.

    1999-01-01

    After years of investigation into the function of sexually dimorphic ornamental traits, researchers are beginning to understand how bright plumage colour in birds acts as an intraspecific signal. This work has focused primarily on pigment-based ornaments because they are highly variable in patch size, hue and brightness for some species. In contrast, structurally based ornaments have been little studied, in part because they do not appear to be as variable as pigment-based ornaments. We investigated a structurally based plumage ornament in a wild population of blue grosbeaks (Guiraca caerulea), a sexually dimorphic passerine. We report plumage variation that extends into the ultraviolet region of the spectrum. The pattern of covariation between four out of five elements of plumage variation suggests that structurally based ornamentation is pushed towards extreme expression of the trait as predicted by the sexual selection theory. The 'bluest' birds have the highest percentage of blue feathers on the body. These ornamental feathers reflect light maximally at the shortest wavelengths (ultraviolet), with the greatest intensity and the greatest contrast. Age may have some effect on expression of blueness. In addition, plumage variables are correlated with growth bars in tail feathers (a record of nutritional condition during moult in a non-ornamental trait). This suggests that the ornament is partially condition dependent. Thus, blue plumage in male grosbeaks may serve as an honest indicator of age and quality.

  5. Measurements of the diffuse ultraviolet radiation

    NASA Technical Reports Server (NTRS)

    Fix, John D.; Craven, John D.; Frank, Louis A.

    1989-01-01

    The imaging instrumentation on the Dynamics Explorer 1 satellite has been used to measure the intensity of the diffuse ultraviolet radiation on two great circles about the sky. It is found that the isotropic component of the diffuse ultraviolet radiation (possibly of extragalactic origin) has an intensity of 530 + or - 80 units (a unit is 1 photon per sq cm s A sr) at a wavelength of 150 nm. The Galactic component of the diffuse ultraviolet radiation has a dependence on Galactic latitude which requires strongly forward scattering particles if it is produced by dust above the Galactic plane.

  6. Ultraviolet phototherapy and photochemotherapy of acne vulgaris.

    PubMed

    Mills, O H; Kligman, A M

    1978-02-01

    The therapeutic value of various ultraviolet treatments was assessed in patients with moderately severe papulopustular acne. The results did not verify the common belief that ultraviolet radiation is highly beneficial. In no instance was the comedo count appreciably reduced. Modest improvement was observed with sunburn rays (UV-B) and slightly more with the combination of long ultraviolet radiation (UV-A) and UV-B. UV-A alone had the least effect. Photosensitization with coal tar and UV-A greatly aggravated acne and was notably comedogenic. Photosensitization with methoxsalen (8-methoxypsoralen) applied topically was neither harmful nor helpful.

  7. World Space Observatory Ultraviolet mission: status 2016

    NASA Astrophysics Data System (ADS)

    Sachkov, Mikhail; Shustov, Boris; Gómez de Castro, Ana Inés.

    2016-07-01

    The WSO-UV (World Space Observatory - Ultraviolet) project is intended to built and operate an international space observatory designed for observations in the UV (115 - 310 nm) range, where some of the most important astrophysical processes can be efficiently studied. It is the solution to the problem of future access to UV spectroscopy. Dedicated to spectroscopic and imaging observations of the ultraviolet sky, the World Space Observatory - Ultraviolet mission is a Russian-Spanish collaboration with potential Mexican minor contribution. This paper provides a summary on the project, its status and the major outcomes since the last SPIE meeting.

  8. The 'Brightness Rules' alternative conception for light bulb circuits

    NASA Astrophysics Data System (ADS)

    Bryan, Joel A.; Stuessy, Carol

    2006-11-01

    An alternative conception for the observed differences in light bulb brightness was revealed during an unguided inquiry investigation in which prospective elementary teachers placed identical bulbs in series, parallel, and combination direct current circuits. Classroom observations, document analyses, and video and audio transcriptions led to the discovery of this alternative conception, appropriately christened 'Brightness Rules'. Assessments administered three weeks after the activity confirmed that several prospective teachers maintained the 'Brightness Rules' conception even after instructor-led intervention. Implications of the discovery of this alternative conception are discussed with respect to a previously administered assessment question that could not identify the presence of this alternative conception.

  9. High-speed CuBr brightness amplifier beam profile

    NASA Astrophysics Data System (ADS)

    Evtushenko, G. S.; Torgaev, S. N.; Trigub, M. V.; Shiyanov, D. V.; Evtushenko, T. G.; Kulagin, A. E.

    2017-01-01

    This paper addresses the experimental study of the beam profile of the CuBr brightness amplifier operating at a wide range of pulse repetition frequencies. The use of a medium-size gas discharge tube (2 cm) ensures the operation of the brightness amplifier both at typical PRFs (520 kHz) and at higher PRFs (up to 100 kHz), either with or without HBr additive. The effect of the active additive on the beam profile is demonstrated. The testing results on kinetic modeling of radial processes in the laser (brightness amplifier) plasma are also discussed.

  10. Cosmological models and the brightness profile of distant galaxies

    NASA Astrophysics Data System (ADS)

    Olivares-Salaverri, I.; Ribeiro, Marcelo B.

    2010-11-01

    This work aims to determine the feasibility of an assumed cosmological model by means of a detailed analysis of the brightness profiles of distant galaxies. Starting from the theory of Ellis & Perry (1979) connecting the angular diameter distance obtained from a relativistic cosmological model and the detailed photometry of galaxies, we assume the presently most accepted cosmology with Λ ¬ = 0 and seek to predict the brightness profile of a galaxy in a given redshift z. To do so, we have to make assumptions concerning the galactic brightness structure and evolution, assuming a scenario where the specific emitted surface brightness Be,νe can be characterized as, Be,νe (r,z) = B0(z)J(νe,z)f[r(z)/a(z)]. Here r is the intrinsic galactic radius, νe the emitted frequency, B0(z) the central surface brightness, J(νe,z) the spectral energy distribution (SED), f[r(z)/a(z)] characterizes the shape of the surface profile distribution and a(z) is the scaling radius. The dependence on z is due to the galactic evolution. As spacetime curvature affects the received surface brightness, the reciprocity theorem (Ellis 1971) allows us to predict the theoretical received surface brightness. So, we are able to compare the theoretical surface brightness with its equivalent observational data already available for high redshift galaxies in order to test the consistency of the assumed cosmological model. The function f[r(z)/a(z)] is represented in the literature by various different shapes, like the Hubble, Hubble-Oemler and Abell-Mihalas single parameter profiles, characterizing the galactic surface brightness quite well when the disk or bulge dependence is dominant. Sérsic and core-Sérsic profiles use two or more parameters and reproduce the galactic profile almost exactly (Trujillo et al. 2004). If we consider all wavelengths, the theory tells us that the total intensity is equal to the surface brightness, so the chosen bandwidth should include most of the SED. In order to

  11. HUBBLE FINDS MANY BRIGHT CLOUDS ON URANUS

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A recent Hubble Space Telescope view reveals Uranus surrounded by its four major rings and by 10 of its 17 known satellites. This false-color image was generated by Erich Karkoschka using data taken on August 8, 1998, with Hubble's Near Infrared Camera and Multi-Object Spectrometer. Hubble recently found about 20 clouds - nearly as many clouds on Uranus as the previous total in the history of modern observations. The orange-colored clouds near the prominent bright band circle the planet at more than 300 mph (500 km/h), according to team member Heidi Hammel (MIT). One of the clouds on the right-hand side is brighter than any other cloud ever seen on Uranus. The colors in the image indicate altitude. Team member Mark Marley (New Mexico State University) reports that green and blue regions show where the atmosphere is clear and sunlight can penetrate deep into Uranus. In yellow and grey regions the sunlight reflects from a higher haze or cloud layer. Orange and red colors indicate very high clouds, such as cirrus clouds on Earth. The Hubble image is one of the first images revealing the precession of the brightest ring with respect to a previous image [LINK to PRC97-36a]. Precession makes the fainter part of the ring (currently on the upper right-hand side) slide around Uranus once every nine months. The fading is caused by ring particles crowding and hiding each other on one side of their eight-hour orbit around Uranus. The blue, green and red components of this false-color image correspond to exposures taken at near-infrared wavelengths of 0.9, 1.1, and 1.7 micrometers. Thus, regions on Uranus appearing blue, for example, reflect more sunlight at 0.9 micrometer than at the longer wavelengths. Apparent colors on Uranus are caused by absorption of methane gas in its atmosphere, an effect comparable to absorption in our atmosphere which can make distant clouds appear red. Credit: Erich Karkoschka (University of Arizona) and NASA

  12. Bright Coherent Optical Waveforms from the Infrared to the Vacuum Ultraviolet for Manipulation and Detection of Molecules

    DTIC Science & Technology

    2012-12-13

    Margaret Murnane. Invited talk, ITAMP Winter School on Atomic, Molecular and Optical Physics ( Biosphere 2 , AZ, January 2012). McElvain Lecture...Molecular and Optical Physics ( Biosphere 2 , AZ, January 2012). McElvain Lecture, University of Wisconsin Chemistry Department, February 2012. Seminar...80309 -0572 REPORT DOCUMENTATION PAGE b. ABSTRACT UU c. THIS PAGE UU 2 . REPORT TYPE Final Report 17. LIMITATION OF ABSTRACT UU 15. NUMBER OF PAGES

  13. Melanoma induction by ultraviolet A but not ultraviolet B radiation requires melanin pigment.

    PubMed

    Noonan, Frances P; Zaidi, M Raza; Wolnicka-Glubisz, Agnieszka; Anver, Miriam R; Bahn, Jesse; Wielgus, Albert; Cadet, Jean; Douki, Thierry; Mouret, Stephane; Tucker, Margaret A; Popratiloff, Anastas; Merlino, Glenn; De Fabo, Edward C

    2012-06-06

    Malignant melanoma of the skin (CMM) is associated with ultraviolet radiation exposure, but the mechanisms and even the wavelengths responsible are unclear. Here we use a mammalian model to investigate melanoma formed in response to precise spectrally defined ultraviolet wavelengths and biologically relevant doses. We show that melanoma induction by ultraviolet A (320-400 nm) requires the presence of melanin pigment and is associated with oxidative DNA damage within melanocytes. In contrast, ultraviolet B radiation (280-320 nm) initiates melanoma in a pigment-independent manner associated with direct ultraviolet B DNA damage. Thus, we identified two ultraviolet wavelength-dependent pathways for the induction of CMM and describe an unexpected and significant role for melanin within the melanocyte in melanomagenesis.

  14. Coordinated observations of X-ray bright BL Lacertae objects

    NASA Technical Reports Server (NTRS)

    Urry, C. M.

    1986-01-01

    No new International Ultraviolet Explorer (IUE) observations were scheduled. The work on the spectral extraction routine was continued. The computer code was adapted from the RDAF PDP 11/44 computer to a VAX 11/750, in order that it run more quickly. A chapter on ultraviolet observations of blazars for a book celebrating the scientific accomplishment of IUE was written in colloboration. A copy of the final draft is attached.

  15. Solar ultraviolet radiation in a changing climate

    NASA Astrophysics Data System (ADS)

    Williamson, Craig E.; Zepp, Richard G.; Lucas, Robyn M.; Madronich, Sasha; Austin, Amy T.; Ballaré, Carlos L.; Norval, Mary; Sulzberger, Barbara; Bais, Alkiviadis F.; McKenzie, Richard L.; Robinson, Sharon A.; Häder, Donat-P.; Paul, Nigel D.; Bornman, Janet F.

    2014-06-01

    The projected large increases in damaging ultraviolet radiation as a result of global emissions of ozone-depleting substances have been forestalled by the success of the Montreal Protocol. New challenges are now arising in relation to climate change. We highlight the complex interactions between the drivers of climate change and those of stratospheric ozone depletion, and the positive and negative feedbacks among climate, ozone and ultraviolet radiation. These will result in both risks and benefits of exposure to ultraviolet radiation for the environment and human welfare. This Review synthesizes these new insights and their relevance in a world where changes in climate as well as in stratospheric ozone are altering exposure to ultraviolet radiation with largely unknown consequences for the biosphere.

  16. Ultraviolet Variability of B[e] Stars

    NASA Astrophysics Data System (ADS)

    Krtička, J.; Krtičková, I.

    2017-02-01

    Hot stars emit most of their light in the ultraviolet. Therefore, the visual domain in which the variability is mostly studied traces just a small part of the spectral energy distribution. To overcome this, we searched archival data of the IUE satellite for the ultraviolet spectra of B[e] stars. We studied each star individually and identified the differences between the variability in the near and far ultraviolet domains. Although the data are typically very sparse, we detected the variability of the spectral energy distribution and of the line profiles. The variability has several sources of origin, including the light absorption by the dust clouds and the disk, pulsations, and eclipses in the case of binaries. The ultraviolet domain is the key to understanding the variability of B[e] stars.

  17. Synthetic Ultraviolet Spectroscopic Indices in Stars

    NASA Astrophysics Data System (ADS)

    Chávez, M.; Rodríguez-Merino, L. H.; Bertone, E.; Buzzoni, A.; Bressan, A.

    2007-12-01

    We present a progress report on the calculation of ultraviolet spectroscopic indices by using the UVBLUE library of synthetic spectra. The ensemble of indices are aimed at complementing empirical databases for the study of stellar populations. The definitions for the set of indices are mainly those empirically built upon data collected with the International Ultraviolet Explorer (IUE). Because the far-ultraviolet (far-UV) and mid-ultraviolet (mid-UV) are sensitive to quite dissimilar stellar populations, they are presented separately. We provide a few examples on the effects of the leading atmospheric parameters on index values. This analysis is, to our knowledge, the first based upon high resolution synthetic spectra and we envisage important applications on the study of stellar aggregates at UV wavelengths.

  18. Astronomy and the Extreme Ultraviolet Explorer satellite.

    PubMed

    Bowyer, S

    1994-01-07

    The extreme ultraviolet wave band (100 to 912 angstroms) was thought until recently to be useless to astronomy, primarily because the opacity of the interstellar medium would prevent observations at these wavelengths. However, the interstellar medium has been found to be markedly inhomogeneous in both density and ionization state and the sun is fortunately located in a region of low extreme ultraviolet opacity. The Extreme Ultraviolet Explorer, launched in June 1992, has surveyed the sky in this wave band and has detected a wide variety of astronomical sources at considerable distances, including some extragalactic objects. Studies in the extreme ultraviolet band have already begun to increase our understanding of the contents of the universe.

  19. Astronomy and the Extreme Ultraviolet Explorer satellite

    NASA Technical Reports Server (NTRS)

    Bowyer, S.

    1994-01-01

    The extreme ultraviolet wave band (100 to 912 angstroms) was thought until recently to be useless to astronomy, primarily because the opacity of the interstellar medium would prevent observations at these wavelengths. However, the interstellar medium has been found to be markedly inhomogeneous in both density and ionization state and the sun is fortunately located in a region of low extreme ultraviolet opacity. The Extreme Ultraviolet Explorer, launched in June 1992, has surveyed the sky in this wave band and has detected a wide variety of astronomical sources at considerable distances, including some extragalactic objects. Studies in the extreme ultraviolet band have already begun to increase our understanding of the contents of the universe.

  20. Improving Performance in Planetary Ultraviolet Spectrographs

    NASA Astrophysics Data System (ADS)

    Davis, M. W.; Gladstone, G. R.; Retherford, K. D.

    2016-10-01

    Four planetary ultraviolet spectrographs by SwRI have successfully operated on different planetary missions. Two more will operate aboard the JUICE and Europa missions with advancements to allow operations in the Jovian environment.

  1. Dust near luminous ultraviolet stars

    NASA Technical Reports Server (NTRS)

    Henry, Richard C.

    1993-01-01

    This report describes research activities related to the Infrared Astronomical Satellite (IRAS) sky survey. About 745 luminous stars were examined for the presence of interstellar dust heated by a nearby star. The 'cirrus' discovered by IRAS is thermal radiation from interstellar dust at moderate and high galactic latitudes. The IRAS locates the dust which must (at some level) scatter ultraviolet starlight, although it was expected that thermal emission would be found around virtually every star, most stars shown no detectable emission. And the emission found is not uniform. It is not that the star is embedded in 'an interstellar medium', but rather what is found are discrete clouds that are heated by starlight. An exception is the dearth of clouds near the very hottest stars, implying that the very hottest stars play an active role with respect to destroying or substantially modifying the dust clouds over time. The other possibility is simply that the hottest stars are located in regions lacking in dust, which is counter-intuitive. A bibliography of related journal articles is attached.

  2. [Ultraviolet: a regulator of immunity].

    PubMed

    Komura, Kazuhiro

    2008-06-01

    Humans establish acquired immune systems during the growth, which can sufficiently eliminate pathogen avoiding immune responses to self, such as allergy and autoimmunity. An imbalance of the acquired immune system leads up to immune-mediated disorders. Ultraviolet (UV) exposure helps to establish the normal peripheral tolerance to contact allergen avoiding excessive immune responses. By contrast, UV develops kinds of autoimmune diseases on rare occasions, suggesting that abnormality in the process of UV-induced peripheral tolerance may induce these diseases. To elucidate the mechanism of UV-induced tolerance is possible to provide a new approach for the management of immune diseases. In the current review, focus is on the suggested players of UV-induced tolerance, blocking mechanisms on the elicitation phase of contact hypersensitivity, and the association between UV and autoimmunity. The major impact in basic immunology in this area is the discovery of cell surface marker of regulatory T cells. Therefore, we first discuss about the association of regulatory/suppressor T cells with UV-induced tolerance. Since the elicitation phase depends on cellular influx into the inflammatory sites, which is tightly regulated by adhesion molecules, we also focused on the role of adhesion molecules. Finally, this paper also includes statistical findings concerning the association between UV-radiation and the prevalence of a myositis specific autoantibody. Thus, UV is one of the nice regulators of an immune network and the knowledge of UV-mediated immune regulation will be translated into new therapeutic strategies to human immune-mediated disorders.

  3. The Diffuse Extreme Ultraviolet Background

    NASA Technical Reports Server (NTRS)

    Vallerga, John; Slavin, Jonathan

    1996-01-01

    Observations of the diffuse EUV background towards 138 different directions using the spectrometers aboard the Extreme Ultraviolet Explorer satellite (EUVE) have been combined into a spectrum from 150A to 730A and represent an effective exposure of 18 million seconds. There is no significant evidence of any non-local line flux in the resultant spectrum such as that from a hot coronal plasma. These results are inconsistent with the Wisconsin C and B broad-band surveys assuming the source is a logT = 5.8 - 6.1 hot plasma in ionization equilibrium with solar abundances, confirming the previous result of Jelinksy, Vallerga and Edelstein) (hereafter Paper 1) using an observation along the ecliptic with the same instrument. To make these results consistent with the previous broad-band surveys, the plasma responsible for the emission must either be depleted in Fe by a factor of approximately 6, be behind an absorbing slab of neutral H with a column of 2 x 10(exp 19)/sq cm, or not be in collisional ionization equilibrium (CIE). One such non-CIE model (Breitswerdt and Schmutzier) that explains the soft x-ray results is also inconsistent with this EUV data.

  4. Visible Color and Photometry of Bright Materials on Vesta

    NASA Technical Reports Server (NTRS)

    Schroder, S. E.; Li, J. Y.; Mittlefehldt, D. W.; Pieters, C. M.; De Sanctis, M. C.; Hiesinger, H.; Blewett, D. T.; Russell, C. T.; Raymond, C. A.; Keller, H. U.

    2012-01-01

    The Dawn Framing Camera (FC) collected images of the surface of Vesta at a pixel scale of 70 m in the High Altitude Mapping Orbit (HAMO) phase through its clear and seven color filters spanning from 430 nm to 980 nm. The surface of Vesta displays a large diversity in its brightness and colors, evidently related to the diverse geology [1] and mineralogy [2]. Here we report a detailed investigation of the visible colors and photometric properties of the apparently bright materials on Vesta in order to study their origin. The global distribution and the spectroscopy of bright materials are discussed in companion papers [3, 4], and the synthesis results about the origin of Vestan bright materials are reported in [5].

  5. Proposal for a High-Brightness Pulsed Electron Source

    SciTech Connect

    Zolotorev, Max; Commins, Eugene D.; Heifets, Sam; Sannibale,Fernando

    2006-03-15

    We propose a novel scheme for a high-brightness pulsedelectron source, which has the potential for many useful applications inelectron microscopy, inverse photo-emission, low energy electronscattering experiments, and electron holography. A description of theproposed scheme is presented.

  6. Perspective of Bright Angel stone vault, view south, with HAER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Perspective of Bright Angel stone vault, view south, with HAER field team measuring (Michael Lee and Dominic Duran foreground, Christopher Marston rear). - Grand Canyon Village Utilities, Grand Canyon National Park, Grand Canyon Village, Coconino County, AZ

  7. South and west elevations of Bright Angel boiler house. Red ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    South and west elevations of Bright Angel boiler house. Red Horse log cabin visible in background. - Grand Canyon Village Utilities, Grand Canyon National Park, Grand Canyon Village, Coconino County, AZ

  8. Yellow steam and electrical pipes across from Bright Angel Lodge. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Yellow steam and electrical pipes across from Bright Angel Lodge. Note control valve to right of control box, view E. - Grand Canyon Village Utilities, Grand Canyon National Park, Grand Canyon Village, Coconino County, AZ

  9. Bright Angel stone vault, with HAER field team members Dominic ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Bright Angel stone vault, with HAER field team members Dominic Duran, Christopher Marston, and Michael Lee (l to r). - Grand Canyon Village Utilities, Grand Canyon National Park, Grand Canyon Village, Coconino County, AZ

  10. Significant increase in the optical brightness of V2492 Cyg

    NASA Astrophysics Data System (ADS)

    Ibryamov, Sunay; Semkov, Evgeni

    2017-03-01

    We observed a recent increase in the optical brightness of the young eruptive star V2492 Cyg using the 2-m and the 50/70-cm Schmidt telescopes administered by National Astronomical Observatory Rozhen in Bulgaria.

  11. Detail of Bright Angel stone vault, containing condenser, Hoffman condensation ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail of Bright Angel stone vault, containing condenser, Hoffman condensation pump, Jennings vacuum heating pump, and misc. pipes and valves. - Grand Canyon Village Utilities, Grand Canyon National Park, Grand Canyon Village, Coconino County, AZ

  12. Zernike analysis of all-sky night brightness maps.

    PubMed

    Bará, Salvador; Nievas, Miguel; Sánchez de Miguel, Alejandro; Zamorano, Jaime

    2014-04-20

    All-sky night brightness maps (calibrated images of the night sky with hemispherical field-of-view (FOV) taken at standard photometric bands) provide useful data to assess the light pollution levels at any ground site. We show that these maps can be efficiently described and analyzed using Zernike circle polynomials. The relevant image information can be compressed into a low-dimensional coefficients vector, giving an analytical expression for the sky brightness and alleviating the effects of noise. Moreover, the Zernike expansions allow us to quantify in a straightforward way the average and zenithal sky brightness and its variation across the FOV, providing a convenient framework to study the time course of these magnitudes. We apply this framework to analyze the results of a one-year campaign of night sky brightness measurements made at the UCM observatory in Madrid.

  13. Ultraviolet Light and Skin Cancer in Athletes

    PubMed Central

    Harrison, Shannon C.; Bergfeld, Wilma F.

    2009-01-01

    The incidence of melanoma and nonmelanoma skin cancers is increasing worldwide. Ultraviolet light exposure is the most important risk factor for cutaneous melanoma and nonmelanoma skin cancers. Nonmelanoma skin cancer includes basal cell carcinoma and squamous cell carcinoma. Constitutive skin color and genetic factors, as well as immunological factors, play a role in the development of skin cancer. Ultraviolet light also causes sunburn and photoaging damage to the skin. PMID:23015891

  14. THE RELATION BETWEEN VISUAL ACUITY AND BRIGHTNESS DISCRIMINATION

    PubMed Central

    Hendley, Charles D.

    1948-01-01

    1. Visual acuity depends on the brightness contrast between test object and background; and conversely, brightness discrimination depends on the target size. Both functions vary with the brightness of the background. Measurements with rectangular targets of length-width ratio 2 were made over a range of sizes, contrasts, and brightnesses sufficient to determine the relations among these three variables. The rectangles were from 2' to 50' wide; the contrast fraction, ΔI/I, ranged from 0.01 to 40; the background brightness varied from 0.0001 to 2500 millilamberts. 2. When ΔI/I or visual acuity is plotted as a function of brightness the data do, in general, follow Hecht's equation. The departure from a simple photochemical theory which the larger targets show is probably due to changes in the functional retinal mosaic with changing brightness. 3. In general also, the relation between visual acuity and brightness, at selected contrasts, fits Hecht's derivation. At low contrasts, as the brightness is reduced a point is reached at which the test object becomes invisible at any size. 4. No simple relation emerges from the data relating visual acuity to contrast, at set levels of illumination. Over only a very short range are visual acuity and contrast directly related. At high contrasts, visual acuity reaches a maximum, whereas at low visual acuity, ΔI/I reaches a minimum which cannot be passed regardless of size. 5. The shape of the curves relating ΔI/I to brightness is not significantly altered by changing the exposure time. There is some evidence to show that a 3 second exposure of the target is equivalent to two looks of 0.2 second each. 6. In all these studies the thresholds were determined by a frequency of seeing method, and the data have been considered in terms of a quantum theory of threshold seeing. It was found that a threshold response involves between four and eight independent critical events, which are largely independent of size, brightness, and

  15. LONG-TERM VARIABILITY OF RADIO-BRIGHT BL LACERTAE OBJECTS

    SciTech Connect

    Nieppola, Elina; Hovatta, Talvikki; Tornikoski, Merja; Valtaoja, Esko; Aller, Margo F.; Aller, Hugh D.

    2009-06-15

    Radio-bright BL Lacertae objects (BLOs) are typically very variable and exhibit prominent flaring. We use a sample of 24 BLOs, regularly monitored at Metsaehovi Radio Observatory, to get a clear idea of their flaring behavior in the radio domain and to find possible commonalities in their variability patterns. Our goal was to compare the results given by computational timescales and the observed variability parameters determined directly from the flux curves. Also, we wanted to find out if the BLO flares adhere to the generalized shock model, which gives a schematic explanation for the physical process giving rise to the variability. We use long-term monitoring data from 4.8, 8, 14.5, 22, 37, 90, and 230 GHz, obtained mainly from the University of Michigan and Metsaehovi Radio Observatories. The structure function, discrete correlation function, and Lomb-Scargle periodogram timescales, calculated in a previous study, are analyzed in more detail. Also, we determine flare durations, rise and decay times, and absolute and relative peak fluxes from the monitoring data. We find that radio-bright BLOs demonstrate a wide range of variability behavior, and few common denominators can be found. BLOs include sources with fast and strong variability, such as OJ 287, PKS 1749+096, and BL Lac, but also sources with more rolling fluctuations such as PKS 0735+178. The most extreme flares can last for up to 13 years or have peak fluxes of approximately 12 Jy in the observer's frame. When the Doppler boosting effect is taken into account, the peak flux of a flare does not depend on the duration of the flare. A rough analysis of the time lags and peak flux evolution indicates that, typically, BLO flares in the mm-cm wavelengths are high peaking, i.e., are in the adiabatic stage. Thus, the results concur with the generalized shock model, which assigns shocks traveling in the jet as the main cause for active galactic nucleus variability. Comparing the computational timescales and the

  16. Insights into the deactivation of 5-bromouracil after ultraviolet excitation.

    PubMed

    Peccati, Francesca; Mai, Sebastian; González, Leticia

    2017-04-28

    5-Bromouracil is a nucleobase analogue that can replace thymine in DNA strands and acts as a strong radiosensitizer, with potential applications in molecular biology and cancer therapy. Here, the deactivation of 5-bromouracil after ultraviolet irradiation is investigated in the singlet and triplet manifold by accurate quantum chemistry calculations and non-adiabatic dynamics simulations. It is found that, after irradiation to the bright ππ* state, three main relaxation pathways are, in principle, possible: relaxation back to the ground state, intersystem crossing (ISC) and C-Br photodissociation. Based on accurate MS-CASPT2 optimizations, we propose that ground-state relaxation should be the predominant deactivation pathway in the gas phase. We then employ different electronic structure methods to assess their suitability to carry out excited-state dynamics simulations. MRCIS (multi-reference configuration interaction including single excitations) was used in surface hopping simulations to compute the ultrafast ISC dynamics, which mostly involves the (1)nOπ* and (3)ππ* states.This article is part of the themed issue 'Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces'.

  17. Ultraviolet vision in birds: the importance of transparent eye media

    PubMed Central

    Lind, Olle; Mitkus, Mindaugas; Olsson, Peter; Kelber, Almut

    2014-01-01

    Ultraviolet (UV)-sensitive visual pigments are widespread in the animal kingdom but many animals, for example primates, block UV light from reaching their retina by pigmented lenses. Birds have UV-sensitive (UVS) visual pigments with sensitivity maxima around 360–373 nm (UVS) or 402–426 nm (violet-sensitive, VS). We describe how these pigments are matched by the ocular media transmittance in 38 bird species. Birds with UVS pigments have ocular media that transmit more UV light (wavelength of 50% transmittance, λT0.5, 323 nm) than birds with VS pigments (λT0.5, 358 nm). Yet, visual models predict that colour discrimination in bright light is mostly dependent on the visual pigment (UVS or VS) and little on the ocular media. We hypothesize that the precise spectral tuning of the ocular media is mostly relevant for detecting weak UV signals, e.g. in dim hollow-nests of passerines and parrots. The correlation between eye size and UV transparency of the ocular media suggests little or no lens pigmentation. Therefore, only small birds gain the full advantage from shifting pigment sensitivity from VS to UVS. On the other hand, some birds with VS pigments have unexpectedly low UV transmission of the ocular media, probably because of UV blocking lens pigmentation. PMID:24258716

  18. Stargazing from New Horizons: Ultraviolet Stellar Occultations by Pluto's Atmosphere

    NASA Astrophysics Data System (ADS)

    Kammer, Joshua A.; Stern, S. Alan; Weaver, Harold A.; Young, Leslie; Ennico, Kimberly; Olkin, Catherine B.; Gladstone, Randy; Summers, Michael; Steffl, Andrew; Greathouse, Thomas K.; Versteeg, Maarten; Retherford, Kurt D.; Parker, Joel Wm.; Schindhelm, Eric; Strobel, Darrell F.; New Horizons ATM Theme Team, New Horizons Science Team

    2016-10-01

    Not long after the New Horizons encounter with Pluto last July, the Alice ultraviolet imaging spectrograph observed signatures of UV absorption by Pluto's atmosphere during two distinct occultation events. During these events, UV bright stars (the Sun, as well as two B-type stars) passed behind Pluto as seen by the spacecraft, and the attenuated starlight revealed the clear presence of nitrogen, methane, and several other hydrocarbons. Their mixing ratios vary with altitude, including localized peaks in the density of minor hydrocarbons such as C2H2 and C2H4. At about 300 km above Pluto's surface, these particular species are found to have mixing ratios relative to CH4 of approximately 10% and 1%, respectively. While this overall composition was expected pre-New Horizons, the vertical profiles of these species were surprising. In this presentation I will discuss the analysis of these occultations, including several profiles of key atmospheric species, and how they might play a role in explaining the presence of high-altitude haze on this cold, small, distant planet.

  19. Sunscreens for delay of ultraviolet induction of skin tumors

    SciTech Connect

    Wulf, H.C.; Poulsen, T.; Brodthagen, H.; Hou-Jensen, K.

    1982-08-01

    Sunscreens with different sun protection factors (SPFs) have been tested for their capability of delaying or preventing actinic damage and skin cancer development in groups of hairless, pigmented mice exposed to artificial ultraviolet (UV) light of increasing intensity. The dose delivered was less than or equal to 1 minimal erythema dose (MED) in the group of untreated mice, so that the mice to which sunscreens were applied never obtained a sunburn after UV exposure. The quality of UV light was similar to bright midday sun at a latitude of 56 degrees (city of Copenhagen). Tumorigenesis was demonstrated to be delayed corresponding to the SPF claimed by the manufacturer, but almost all of the UV-irradiated mice developed skin tumors. Histologic examination revealed actinic degeneration and tumors of squamous cell type with marked variation in differentiation. Metastases to lymph nodes and lungs were found in only 10%. Toxic reactions, such as eczematous-like skin reactions, dark coloring, and amyloidosis, were observed predominantly in the group treated with the sunscreen of highest SPF value. Long-term investigations seem to be necessary to unveil these problems--in particular, the specific SPF value, in sunscreens, that should be recommended to the public for prevention or delay of actinic damage and/or cancer development.

  20. Ultraviolet vision in birds: the importance of transparent eye media.

    PubMed

    Lind, Olle; Mitkus, Mindaugas; Olsson, Peter; Kelber, Almut

    2014-01-07

    Ultraviolet (UV)-sensitive visual pigments are widespread in the animal kingdom but many animals, for example primates, block UV light from reaching their retina by pigmented lenses. Birds have UV-sensitive (UVS) visual pigments with sensitivity maxima around 360-373 nm (UVS) or 402-426 nm (violet-sensitive, VS). We describe how these pigments are matched by the ocular media transmittance in 38 bird species. Birds with UVS pigments have ocular media that transmit more UV light (wavelength of 50% transmittance, λ(T0.5), 323 nm) than birds with VS pigments (λ(T0.5), 358 nm). Yet, visual models predict that colour discrimination in bright light is mostly dependent on the visual pigment (UVS or VS) and little on the ocular media. We hypothesize that the precise spectral tuning of the ocular media is mostly relevant for detecting weak UV signals, e.g. in dim hollow-nests of passerines and parrots. The correlation between eye size and UV transparency of the ocular media suggests little or no lens pigmentation. Therefore, only small birds gain the full advantage from shifting pigment sensitivity from VS to UVS. On the other hand, some birds with VS pigments have unexpectedly low UV transmission of the ocular media, probably because of UV blocking lens pigmentation.

  1. Laser-heated X-ray flashlamp brightness measurements

    SciTech Connect

    Matthews, D.L.; Campbell, E.M.; Hagelstein, P.; Halsey, W.; Kauffman, R.L.; Koppel, L.; Phillion, D.; Price, R.; Toor, A.

    1983-12-01

    The authors present measurements of the X-ray emission characteristics of laser-irradiated flashlamp foils which are candidates to produce by resonant photoexcitation a population inversion in either a neon or fluorine lasant gas. Using the Shiva 1.06 ..mu.. laser, the authors heated Fe, Cr, and Ni foils to study the brightness and centroid energies of X-ray lines stemming from L-M transitions. Results indicate that appropriately bright and uniform sources can be produced.

  2. Catalogue of Galactic globular-cluster surface-brightness profiles

    NASA Technical Reports Server (NTRS)

    Trager, S. C.; King, Ivan R.; Djorgovski, S.

    1995-01-01

    We present a catalogue of surface-brightness profiles (SBPs) of 125 Galactic globular clusters, the largest such collection ever gathered. The SPBs are constructed from generally inhomogeneous data, but are based heavily on the Berkeley Global Cluster Survey of Djorgovski & King. All but four of the SBPs have photometric zero points. We derive central surface brightness, King-model concentrations, core radii, half-light, and other fraction-of-light radii where data permit, and we briefly discuss their use.

  3. Sky Brightness Analysis using a Million GEODSS Observations

    NASA Astrophysics Data System (ADS)

    Mandeville, W. Jody; McLaughlin, Tim; Six, Steve; Hollm, Rick

    2012-09-01

    Brightness of the sky background due to lunar phase and location can dramatically affect the limiting magnitude of astronomical detectors. Formerly, theoretical models have attained limited data sets with 10-20% differences between model and observation. This paper compares and contrasts previous investigations with over a million data points collected from various GEODSS sites located around the world and attempts to refine predictive modeling of sky brightness for use in scheduling as well as modeling and simulation tools.

  4. Dynamic properties of ultraviolet-exposed polyurea

    NASA Astrophysics Data System (ADS)

    Youssef, George; Whitten, Ian

    2016-11-01

    Polyurea is used in military and civilian applications, where exposure to the sun in long durations is imminent. Extended exposure to ultraviolet radiation from the sun can deteriorate its mechanical performance to suboptimal levels. This study reports on the dynamic mechanical properties of polyurea as a function of ultraviolet radiation exposure duration. Six sets of samples were continuously exposed to ultraviolet radiation for different durations up to 18 weeks. Control samples were also tested that did not receive ultraviolet exposure. The dynamic properties were measured using a dynamic mechanical analyzer. Exposed samples exhibited significant color changes from transparent yellow to opaque tan after 18 weeks of exposure. Changes of color were observed as early as 3 weeks of exposure. The dynamic properties showed an initial increase in the dynamic modulus after 3 weeks of exposure, with no further significant change in the stiffness thereafter. The ultraviolet exposure had a significant impact at relatively short loading times or low temperature, for example, up to 6 decades of time. As loading time increases or polyurea operates at high temperature, the effect of ultraviolet exposure and temperature on the performance become highly coupled.

  5. Discovery and imaging of a Galactic cirrus cloud with the far ultraviolet space telescope

    NASA Technical Reports Server (NTRS)

    Haikala, Lauri K.; Mattila, Kalevi; Bowyer, Stuart; Sasseen, Timothy P.; Lampton, Michael; Knude, Jens

    1995-01-01

    We present new far-ultraviolet (1400-1800 A) data concerning a Galactic cirrus cloud G251.2+73.3 near the north Galactic pole obtained with the space-borne imaging telescope FAUST (Far Ultraviolet Space Telescope). We obtain a good correlation between the far-ultraviolet (FUV) and IRAS 100 micrometers surface brightnesses, their relation being I(sub FUV) = (128 +/- 3) I(sub 100 micrometers) - (264 +/- 9), where the I(sub FUV) flux is given in units of photon/s/sq cm/A/sr and I(sub 100 micrometers) in MJy/sr. Using uvbyH-beta photometry, we get a distance of 120 pc and a visual extinction in the center of the cloud of 0.39 mag corresponding to an extinction of 1.0 mag at 1565 A. We have performed a multiple scattering calculation for the scattered light using the Monte Carlo method. These calculations provide restrictions on the FUV scattering properties of the interstellar dust.

  6. Ultraviolet surprise: Efficient soft x-ray high-harmonic generation in multiply ionized plasmas.

    PubMed

    Popmintchev, Dimitar; Hernández-García, Carlos; Dollar, Franklin; Mancuso, Christopher; Pérez-Hernández, Jose A; Chen, Ming-Chang; Hankla, Amelia; Gao, Xiaohui; Shim, Bonggu; Gaeta, Alexander L; Tarazkar, Maryam; Romanov, Dmitri A; Levis, Robert J; Gaffney, Jim A; Foord, Mark; Libby, Stephen B; Jaron-Becker, Agnieszka; Becker, Andreas; Plaja, Luis; Murnane, Margaret M; Kapteyn, Henry C; Popmintchev, Tenio

    2015-12-04

    High-harmonic generation is a universal response of matter to strong femtosecond laser fields, coherently upconverting light to much shorter wavelengths. Optimizing the conversion of laser light into soft x-rays typically demands a trade-off between two competing factors. Because of reduced quantum diffusion of the radiating electron wave function, the emission from each species is highest when a short-wavelength ultraviolet driving laser is used. However, phase matching--the constructive addition of x-ray waves from a large number of atoms--favors longer-wavelength mid-infrared lasers. We identified a regime of high-harmonic generation driven by 40-cycle ultraviolet lasers in waveguides that can generate bright beams in the soft x-ray region of the spectrum, up to photon energies of 280 electron volts. Surprisingly, the high ultraviolet refractive indices of both neutral atoms and ions enabled effective phase matching, even in a multiply ionized plasma. We observed harmonics with very narrow linewidths, while calculations show that the x-rays emerge as nearly time-bandwidth-limited pulse trains of ~100 attoseconds.

  7. The Ultraviolet Surprise. Efficient Soft X-Ray High Harmonic Generation in Multiply-Ionized Plasmas

    DOE PAGES

    Popmintchev, Dimitar; Hernandez-Garcia, Carlos; Dollar, Franklin; ...

    2015-12-04

    High-harmonic generation is a universal response of matter to strong femtosecond laser fields, coherently upconverting light to much shorter wavelengths. Optimizing the conversion of laser light into soft x-rays typically demands a trade-off between two competing factors. Reduced quantum diffusion of the radiating electron wave function results in emission from each species which is highest when a short-wavelength ultraviolet driving laser is used. But, phase matching—the constructive addition of x-ray waves from a large number of atoms—favors longer-wavelength mid-infrared lasers. We identified a regime of high-harmonic generation driven by 40-cycle ultraviolet lasers in waveguides that can generate bright beams inmore » the soft x-ray region of the spectrum, up to photon energies of 280 electron volts. Surprisingly, the high ultraviolet refractive indices of both neutral atoms and ions enabled effective phase matching, even in a multiply ionized plasma. We observed harmonics with very narrow linewidths, while calculations show that the x-rays emerge as nearly time-bandwidth–limited pulse trains of ~100 attoseconds.« less

  8. The Ultraviolet Surprise. Efficient Soft X-Ray High Harmonic Generation in Multiply-Ionized Plasmas

    SciTech Connect

    Popmintchev, Dimitar; Hernandez-Garcia, Carlos; Dollar, Franklin; Mancuso, Christopher; Perez-Hernandez, Jose A.; Chen, Ming-Chang; Hankla, Amelia; Gao, Xiaohui; Shim, Bonggu; Gaeta, Alexander L.; Tarazkar, Maryam; Romanov, Dmitri A.; Levis, Robert J.; Gaffney, Jim A.; Foord, Mark; Libby, Stephen B.; Jaron-Becker, Agnieskzka; Becker, Andreas; Plaja, Luis; Muranane, Margaret M.; Kapteyn, Henry C.; Popmintchev, Tenio

    2015-12-04

    High-harmonic generation is a universal response of matter to strong femtosecond laser fields, coherently upconverting light to much shorter wavelengths. Optimizing the conversion of laser light into soft x-rays typically demands a trade-off between two competing factors. Reduced quantum diffusion of the radiating electron wave function results in emission from each species which is highest when a short-wavelength ultraviolet driving laser is used. But, phase matching—the constructive addition of x-ray waves from a large number of atoms—favors longer-wavelength mid-infrared lasers. We identified a regime of high-harmonic generation driven by 40-cycle ultraviolet lasers in waveguides that can generate bright beams in the soft x-ray region of the spectrum, up to photon energies of 280 electron volts. Surprisingly, the high ultraviolet refractive indices of both neutral atoms and ions enabled effective phase matching, even in a multiply ionized plasma. We observed harmonics with very narrow linewidths, while calculations show that the x-rays emerge as nearly time-bandwidth–limited pulse trains of ~100 attoseconds.

  9. Global View of the Bright Material on Vesta

    NASA Technical Reports Server (NTRS)

    Zambon, F.; DeSanctis, C.; Schroeder, S.; Tosi, F.; Li, J.-Y.; Longobardo, A.; Ammannito, E.; Blewett, D. T.; Palomba, E.; Capaccioni, F.; Frigeri, A.; Capria, M. T.; Fonte, S.; Mittlefehldt, D. W.; Nathues, A.; Pieters, C.; Russell, C. T.; Raymond, C. A.

    2014-01-01

    At 525 km in mean diameter, Vesta is the second-most massive and one of the brightest asteroids of the main-belt. Here we give a global view of the bright material (BM) units on Vesta. We classified the BMs according to the normal visual albedo. The global albedo map of Vesta allows to be divided the surface into three principal types of terrains: bright regions, dark regions and intermediate regions. The distribution of bright regions is not uniform. The mid-southern latitudes contain the most bright areas, while the northern hemisphere is poor in bright regions. The analysis of the spectral parameters and the normal visual albedo show a dependence between albedo and the strength (depth) of ferrous iron absorption bands, strong bands correspond with high albedo units. Vesta's average albedo is 0.38, but there are bright material whose albedo can exceed 0.50. Only the E-Type asteroids have albedos comparable to those of the BMs on Vesta. The Dawn mission observed a large fraction of Vesta's surface at high spatial resolution, allowing a detailed study of the morphology and mineralogy of it. In particular, reflectance spectra provided by the Visible and InfraRed spectrometer (VIR), confirmed that Vesta's mineralogy is dominated by pyroxenes. All Vesta spectra show two strong absorption bands at approx 0.9 and 1.9 micron, typical of the pyroxenes and associated with the howardite, eucrite and diogenite (HED) meteorites.

  10. The Influence of Microphysical Cloud Parameterization on Microwave Brightness Temperatures

    NASA Technical Reports Server (NTRS)

    Skofronick-Jackson, Gail M.; Gasiewski, Albin J.; Wang, James R.; Zukor, Dorothy J. (Technical Monitor)

    2000-01-01

    The microphysical parameterization of clouds and rain-cells plays a central role in atmospheric forward radiative transfer models used in calculating passive microwave brightness temperatures. The absorption and scattering properties of a hydrometeor-laden atmosphere are governed by particle phase, size distribution, aggregate density., shape, and dielectric constant. This study identifies the sensitivity of brightness temperatures with respect to the microphysical cloud parameterization. Cloud parameterizations for wideband (6-410 GHz observations of baseline brightness temperatures were studied for four evolutionary stages of an oceanic convective storm using a five-phase hydrometeor model in a planar-stratified scattering-based radiative transfer model. Five other microphysical cloud parameterizations were compared to the baseline calculations to evaluate brightness temperature sensitivity to gross changes in the hydrometeor size distributions and the ice-air-water ratios in the frozen or partly frozen phase. The comparison shows that, enlarging the rain drop size or adding water to the partly Frozen hydrometeor mix warms brightness temperatures by up to .55 K at 6 GHz. The cooling signature caused by ice scattering intensifies with increasing ice concentrations and at higher frequencies. An additional comparison to measured Convection and Moisture LA Experiment (CAMEX 3) brightness temperatures shows that in general all but, two parameterizations produce calculated T(sub B)'s that fall within the observed clear-air minima and maxima. The exceptions are for parameterizations that, enhance the scattering characteristics of frozen hydrometeors.

  11. Synthesizing SMOS Zero-Baselines with Aquarius Brightness Temperature Simulator

    NASA Technical Reports Server (NTRS)

    Colliander, A.; Dinnat, E.; Le Vine, D.; Kainulainen, J.

    2012-01-01

    SMOS [1] and Aquarius [2] are ESA and NASA missions, respectively, to make L-band measurements from the Low Earth Orbit. SMOS makes passive measurements whereas Aquarius measures both passive and active. SMOS was launched in November 2009 and Aquarius in June 2011.The scientific objectives of the missions are overlapping: both missions aim at mapping the global Sea Surface Salinity (SSS). Additionally, SMOS mission produces soil moisture product (however, Aquarius data will eventually be used for retrieving soil moisture too). The consistency of the brightness temperature observations made by the two instruments is essential for long-term studies of SSS and soil moisture. For resolving the consistency, the calibration of the instruments is the key. The basis of the SMOS brightness temperature level is the measurements performed with the so-called zero-baselines [3]; SMOS employs an interferometric measurement technique which forms a brightness temperature image from several baselines constructed by combination of multiple receivers in an array; zero-length baseline defines the overall brightness temperature level. The basis of the Aquarius brightness temperature level is resolved from the brightness temperature simulator combined with ancillary data such as antenna patterns and environmental models [4]. Consistency between the SMOS zero-baseline measurements and the simulator output would provide a robust basis for establishing the overall comparability of the missions.

  12. An observational correlation between stellar brightness variations and surface gravity.

    PubMed

    Bastien, Fabienne A; Stassun, Keivan G; Basri, Gibor; Pepper, Joshua

    2013-08-22

    Surface gravity is a basic stellar property, but it is difficult to measure accurately, with typical uncertainties of 25 to 50 per cent if measured spectroscopically and 90 to 150 per cent if measured photometrically. Asteroseismology measures gravity with an uncertainty of about 2 per cent but is restricted to relatively small samples of bright stars, most of which are giants. The availability of high-precision measurements of brightness variations for more than 150,000 stars provides an opportunity to investigate whether the variations can be used to determine surface gravities. The Fourier power of granulation on a star's surface correlates physically with surface gravity: if brightness variations on timescales of hours arise from granulation, then such variations should correlate with surface gravity. Here we report an analysis of archival data that reveals an observational correlation between surface gravity and root mean squared brightness variations on timescales of less than eight hours for stars with temperatures of 4,500 to 6,750 kelvin, log surface gravities of 2.5 to 4.5 (cgs units) and overall brightness variations of less than three parts per thousand. A straightforward observation of optical brightness variations therefore allows a determination of the surface gravity with a precision of better than 25 per cent for inactive Sun-like stars at main-sequence to giant stages of evolution.

  13. Brightness of Solar Magnetic Elements As a Function of Magnetic Flux at High Spatial Resolution

    NASA Astrophysics Data System (ADS)

    Kahil, F.; Riethmüller, T. L.; Solanki, S. K.

    2017-03-01

    We investigate the relationship between the photospheric magnetic field of small-scale magnetic elements in the quiet-Sun (QS) at disk center and the brightness at 214, 300, 313, 388, 397, and 525.02 nm. To this end, we analyzed spectropolarimetric and imaging time series acquired simultaneously by the Imaging Magnetograph eXperiment magnetograph and the SuFI filter imager on board the balloon-borne observatory {{S}}{{UNRISE}} during its first science flight in 2009, with high spatial and temporal resolution. We find a clear dependence of the contrast in the near ultraviolet and the visible on the line-of-sight component of the magnetic field, B LOS, which is best described by a logarithmic model. This function effectively represents the relationship between the Ca ii H-line emission and B LOS and works better than the power-law fit adopted by previous studies. This, along with the high contrast reached at these wavelengths, will help with determining the contribution of small-scale elements in the QS to the irradiance changes for wavelengths below 388 nm. At all wavelengths, including the continuum at 525.40 nm, the intensity contrast does not decrease with increasing B LOS. This result also strongly supports the fact that {{S}}{{UNRISE}} has resolved small strong magnetic field elements in the internetwork, resulting in constant contrasts for large magnetic fields in our continuum contrast at 525.40 nm versus the B LOS scatterplot, unlike the turnover obtained in previous observational studies. This turnover is due to the intermixing of the bright magnetic features with the dark intergranular lanes surrounding them.

  14. Design of high-brightness TEM00-mode solar-pumped laser for renewable material processing

    NASA Astrophysics Data System (ADS)

    Liang, D.; Almeida, J.

    2014-08-01

    The conversion of sunlight into laser light by direct solar pumping is of ever-increasing importance because broadband, temporally constant, sunlight is converted into laser light, which can be a source of narrowband, collimated, rapidly pulsed, radiation with the possibility of obtaining extremely high brightness and intensity. Nonlinear processes, such as harmonic generation, might be used to obtain broad wavelength coverage, including the ultraviolet wavelengths, where the solar flux is very weak. The direct excitation of large lasers by sunlight offers the prospect of a drastic reduction in the cost of coherent optical radiation for high average power materials processing. This renewable laser has a large potential for many applications such as high-temperature materials processing, renewable magnesium-hydrogen energy cycle and so on. We propose here a scalable TEM00 mode solar laser pumping scheme, which is composed of four firststage 1.13 m diameter Fresnel lenses with its respective folding mirrors mounted on a two-axis automatic solar tracker. Concentrated solar power at the four focal spots of these Fresnel lenses are focused individually along a common 3.5 mm diameter, 70 mm length Nd:YAG rod via four pairs of second-stage fused-silica spherical lenses and third-stage 2D-CPCs (Compound Parabolic Concentrator), sitting just above the laser rod which is also double-pass pumped by four V-shaped pumping cavities. Distilled water cools both the rod and the concentrators. 15.4 W TEM00 solar laser power is numerically calculated, corresponding to 6.7 times enhancement in laser beam brightness.

  15. A medium-bright quasar sample - New quasar surface densities in the magnitude range from 16.4 to 17.65 for B

    NASA Technical Reports Server (NTRS)

    Mitchell, K. J.; Warnock, A., III; Usher, P. D.

    1984-01-01

    A new medium-bright quasar sample (MBQS) is constructed from spectroscopic observations of 140 bright objects selected for varying degrees of blue and ultraviolet excess (B-UVX) in five Palomar 1.2 m Schmidt fields. The MBQS contains 32 quasars with B less than 17.65 mag. The new integral surface densities in the B range from 16.45 to 17.65 mag are approximately 40 percent (or more) higher than expected. The MBQS and its redshift distribution increase the area of the Hubble diagram covered by complete samples of quasars. The general spectroscopic results indicate that the three-color classification process used to catalog the spectroscopic candidates (1) has efficiently separated the intrinsically B-UVX stellar objects from the Population II subdwarfs and (2) has produced samples of B-UVX objects which are more complete than samples selected by (U - B) color alone.

  16. Generation of Bright, Spatially Coherent Soft X-Ray High Harmonics in a Hollow Waveguide Using Two-Color Synthesized Laser Pulses

    NASA Astrophysics Data System (ADS)

    Jin, Cheng; Stein, Gregory J.; Hong, Kyung-Han; Lin, C. D.

    2015-07-01

    We investigate the efficient generation of low-divergence high-order harmonics driven by waveform-optimized laser pulses in a gas-filled hollow waveguide. The drive waveform is obtained by synthesizing two-color laser pulses, optimized such that highest harmonic yields are emitted from each atom. Optimization of the gas pressure and waveguide configuration has enabled us to produce bright and spatially coherent harmonics extending from the extreme ultraviolet to soft x rays. Our study on the interplay among waveguide mode, atomic dispersion, and plasma effect uncovers how dynamic phase matching is accomplished and how an optimized waveform is maintained when optimal waveguide parameters (radius and length) and gas pressure are identified. Our analysis should help laboratory development in the generation of high-flux bright coherent soft x rays as tabletop light sources for applications.

  17. Modeling Ultraviolet Emissions Near Io

    NASA Technical Reports Server (NTRS)

    Linker, Jon A.

    2000-01-01

    In this report, we describe work awarded to Science Applications International Corporation, for the period 6/l/99 to 5/31/00. During this time period, we have investigated the interaction of Io, Jupiter's innermost Galilean satellite, with the Io plasma torus, and the role this interaction plays in producing ultraviolet (UV) emissions from neutral oxygen and sulfur. Io, the innermost of Jupiter's Galilean satellites, plays a unique role in the jovian magnetosphere. Neutral material that escapes from Io is ionized to form the lo torus, a dense, heavy-ion plasma that corotates with Jupiter and interacts with Io. Io supplies not only the torus, but is a major source of plasma for the entire magnetosphere. Ionization and charge-exchange of neutrals near lo strongly influences the plasma interaction, and Io's neutral atmosphere plays an important role in the generation of currents that couple Io to Jupiter. There have been no in situ measurements of the neutral density near Io, but remote observations of neutrals near lo have been performed for many years. Recent observations from the Hubble Space Telescope (HST) have shown detailed structure in UV emissions from neutral species near Io. Electron-impact of the neutrals by the Io torus plasma is the primary mechanism responsible for exciting these emissions. Previously, we have modeled the Io plasma environment using three-dimensional magnetohydrodynamic (MHD) simulations, and we have shown that the interaction between Io and the plasma torus plays an important role in producing the morphology of the observed emissions. In the past year, we have extended these studies to use both UV observations and Galileo particle and field measurements to investigate the Io interaction.

  18. Ultraviolet resources over Northern Eurasia.

    PubMed

    Chubarova, Natalia; Zhdanova, Yekaterina

    2013-10-05

    We propose a new climatology of UV resources over Northern Eurasia, which includes the assessments of both detrimental (erythema) and positive (vitamin D synthesis) effects of ultraviolet radiation on human health. The UV resources are defined by using several classes and subclasses - UV deficiency, UV optimum, and UV excess - for 6 different skin types. To better quantifying the vitamin D irradiance threshold we accounted for an open body fraction S as a function of effective air temperature. The spatial and temporal distribution of UV resources was estimated by radiative transfer (RT) modeling (8 stream DISORT RT code) with 1×1° grid and monthly resolution. For this purpose special datasets of main input geophysical parameters (total ozone content, aerosol characteristics, surface UV albedo, UV cloud modification factor) have been created over the territory of Northern Eurasia. The new approaches were used to retrieve aerosol parameters and cloud modification factor in the UV spectral region. As a result, the UV resources were obtained for clear-sky and mean cloudy conditions for different skin types. We show that the distribution of UV deficiency, UV optimum and UV excess is regulated by various geophysical parameters (mainly, total ozone, cloudiness and open body fraction) and can significantly deviate from latitudinal dependence. We also show that the UV optimum conditions can be simultaneously observed for people with different skin types (for example, for 4-5 skin types at the same time in spring over Western Europe). These UV optimum conditions for different skin types occupy a much larger territory over Europe than that over Asia.

  19. Results of Satellite Brightness Modeling Using Kringing Optimized Interpolation

    NASA Astrophysics Data System (ADS)

    Weeden, C.; Hejduk, M.

    At the 2005 AMOS conference, Kriging Optimized Interpolation (KOI) was presented as a tool to model satellite brightness as a function of phase angle and solar declination angle (J.M Okada and M.D. Hejduk). Since November 2005, this method has been used to support the tasking algorithm for all optical sensors in the Space Surveillance Network (SSN). The satellite brightness maps generated by the KOI program are compared to each sensor's ability to detect an object as a function of the brightness of the background sky and angular rate of the object. This will determine if the sensor can technically detect an object based on an explicit calculation of the object's probability of detection. In addition, recent upgrades at Ground-Based Electro Optical Deep Space Surveillance Sites (GEODSS) sites have increased the amount and quality of brightness data collected and therefore available for analysis. This in turn has provided enough data to study the modeling process in more detail in order to obtain the most accurate brightness prediction of satellites. Analysis of two years of brightness data gathered from optical sensors and modeled via KOI solutions are outlined in this paper. By comparison, geo-stationary objects (GEO) were tracked less than non-GEO objects but had higher density tracking in phase angle due to artifices of scheduling. A statistically-significant fit to a deterministic model was possible less than half the time in both GEO and non-GEO tracks, showing that a stochastic model must often be used alone to produce brightness results, but such results are nonetheless serviceable. Within the Kriging solution, the exponential variogram model was the most frequently employed in both GEO and non-GEO tracks, indicating that monotonic brightness variation with both phase and solar declination angle is common and testifying to the suitability to the application of regionalized variable theory to this particular problem. Finally, the average nugget value, or

  20. Ultraviolet Spectroscopy of Asteroid(4) Vesta

    NASA Technical Reports Server (NTRS)

    Li, Jian-Yang; Bodewits, Dennis; Feaga, Lori M.; Landsman, Wayne; A'Hearn, Michael F.; Mutchler, Max J.; Russell, Christopher T.; McFadden, Lucy A.; Raymond, Carol A.

    2011-01-01

    We report a comprehensive review of the UV-visible spectrum and rotational lightcurve of Vesta combining new observations by Hubble Space Telescope and Swift with archival International Ultraviolet Explorer observations. The geometric albedos of Vesta from 220 nm to 953 nm arc derived by carefully comparing these observations from various instruments at different times and observing geometries. Vesta has a rotationally averaged geometric albedo of 0.09 at 250 nm, 0.14 at 300 nm, 0.26 at 373 nm, 0.38 at 673 nm, and 0.30 at 950 nm. The linear spectral slope in the ultraviolet displays a sharp minimum ncar sub-Earth longitude of 20deg, and maximum in the eastern hemisphere. This is completely consistent with the distribution of the spectral slope in the visible wavelength. The uncertainty of the measurement in the ultraviolet is approx.20%, and in the visible wavelengths better than 10%. The amplitude of Vesta's rotational lightcurves is approx.10% throughout the range of wavelengths we observed, but is smaller at 950 nm (approx.6%) ncar the 1-micron mafic band center. Contrary to earlier reports, we found no evidence for any difference between the phasing of the ultraviolet and visible/ncar-infrared lightcurves with respect to sub-Earth longitude. Vesta's average spectrum between 220 and 950 nm can well be described by measured reflectance spectra of fine particle howardite-like materials of basaltic achondrite meteorites. Combining this with the in-phase behavior of the ultraviolet, visible. and ncar-infrared lightcurves, and the spectral slopes with respect to the rotational phase, we conclude that there is no global ultraviolet/visible reversal on Vesta. Consequently, this implies lack of global space weathering on Vesta. Keyword,: Asteroid Vesta; Spectrophotometry; Spectroscopy; Ultraviolet observations; Hubble Space Telescope observations

  1. [Preparation of reactive bright blue praseodymium dyestuff and its spectral properties].

    PubMed

    Liu, Xiao-Zhen; Yuan, Ya-Qin; Cai, Yu; Zhu, Xian; Wang, Yan-Hong

    2004-08-01

    Reactive bright blue praseodymium dyestuff was prepared by using reactive bright blue and praseodymium oxide. The spectra of reactive bright blue praseodymium and dyed silk cloth by reactive bright blue praseodymium dyestuff were studied by UV-Vis and IR spectra respectively. In the range of 200-800 nm, reactive bright blue has four absorption peaks, and lambda(max) is 259 nm; reactive bright blue praseodymium has three absorption peaks, while lambda(max), is 264.00 nm. In the range of 420-760 nm, reactive bright blue has two absorption peaks at 661.50 and 625.50 nm, respectively, and lambda(max) is 661.50 nm; reactive bright blue praseodymium has only one absorption peak at 618.00 nm. Coordinate bond links reactive bright blue to praseodymium ion. Reactive bright blue praseodymium increases linking radicals as compared with reactive bright blue.

  2. Properties and Frequency Conversion of High-Brightness Diode-Laser Systems

    NASA Astrophysics Data System (ADS)

    Boller, Klaus-Jochen; Beier, Bernard; Wallenstein, Richard

    An overview of recent developments in the field of high-power, high-brightness diode-lasers, and the optically nonlinear conversion of their output into other wavelength ranges, is given. We describe the generation of continuous-wave (CW) laser beams at power levels of several hundreds of milliwatts to several watts with near-perfect spatial and spectral properties using Master-Oscillator Power-Amplifier (MOPA) systems. With single- or double-stage systems, using amplifiers of tapered or rectangular geometry, up to 2.85 W high-brightness radiation is generated at wavelengths around 810nm with AlGaAs diodes. Even higher powers, up to 5.2W of single-frequency and high spatial quality beams at 925nm, are obtained with InGaAs diodes. We describe the basic properties of the oscillators and amplifiers used. A strict proof-of-quality for the diode radiation is provided by direct and efficient nonlinear optical conversion of the diode MOPA output into other wavelength ranges. We review recent experiments with the highest power levels obtained so far by direct frequency doubling of diode radiation. In these experiments, 100mW single-frequency ultraviolet light at 403nm was generated, as well as 1W of single-frequency blue radiation at 465nm. Nonlinear conversion of diode radiation into widely tunable infrared radiation has recently yielded record values. We review the efficient generation of widely tunable single-frequency radiation in the infrared with diode-pumped Optical Parametric Oscillators (OPOs). With this system, single-frequency output radiation with powers of more than 0.5W was generated, widely tunable around wavelengths of 2.1,m and 1.65,m and with excellent spectral and spatial quality. These developments are clear indicators of recent advances in the field of high-brightness diode-MOPA systems, and may emphasize their future central importance for applications within a vast range of optical

  3. Ultraviolet spectroscopy of the extended solar corona

    NASA Astrophysics Data System (ADS)

    Kohl, John L.; Noci, Giancarlo; Cranmer, Steven R.; Raymond, John C.

    2006-04-01

    The first observations of ultraviolet spectral line profiles and intensities from the extended solar corona (i.e., more than 1.5 solar radii from Sun-center) were obtained on 13 April 1979 when a rocket-borne ultraviolet coronagraph spectrometer of the Harvard-Smithsonian Center for Astrophysics made direct measurements of proton kinetic temperatures, and obtained upper limits on outflow velocities in a quiet coronal region and a polar coronal hole. Following those observations, ultraviolet coronagraphic spectroscopy has expanded to include observations of over 60 spectral lines in coronal holes, streamers, coronal jets, and solar flare/coronal mass ejection (CME) events. Spectroscopic diagnostic techniques have been developed to determine proton, electron and ion kinetic temperatures and velocity distributions, proton and ion bulk flow speeds and chemical abundances. The observations have been made during three sounding rocket flights, four Shuttle deployed and retrieved Spartan 201 flights, and the Solar and Heliospheric Observatory (SOHO) mission. Ultraviolet spectroscopy of the extended solar corona has led to fundamentally new views of the acceleration regions of the solar wind and CMEs. Observations with the Ultraviolet Coronagraph Spectrometer (UVCS) on SOHO revealed surprisingly large temperatures, outflow speeds, and velocity distribution anisotropies in coronal holes, especially for minor ions. Those measurements have guided theorists to discard some candidate physical processes of solar wind acceleration and to increase and expand investigations of ion cyclotron resonance and related processes. Analyses of UVCS observations of CME plasma properties and the evolution of CMEs have provided the following: temperatures, inflow velocities and derived values of resistivity and reconnection rates in CME current sheets, compression ratios and extremely high ion temperatures behind CME shocks, and three dimensional flow velocities and magnetic field chirality in

  4. ULTRAVIOLET SPECTRA OF THE C-2003K7 COMET: EVIDENCE FOR DUST SUBLIMATION IN Si AND C LINES

    SciTech Connect

    Ciaravella, A.; Raymond, J. C.; Giordano, S.

    2010-04-10

    UV spectra of the bright sungrazing comet C-2003K7 detected at 2.37 R {sub sun} above the Sun surface by the Ultraviolet Coronagraph Spectrometer (UVCS) during the daily synoptic scan show bright lines of H I Ly{alpha}, Si III {lambda} 1206, and C III {lambda} 977. The derived outgassing rate is an order of magnitude larger than those of the other sungrazers observed by UVCS. Analysis of the spectra suggests that the comet broke apart into smaller pieces before it reached the UVCS slit. The observations provide lower and upper limits to the values of the Si III/C III ratio, in the range 8-22. The ratio indicates a larger abundance of silicates in the cometary dust as compared to organic refractory materials.

  5. An Overview of Ultraviolet Through Infrared Reflectance Spectroscopic Observations of Mercury During the First MESSENGER Flyby

    NASA Astrophysics Data System (ADS)

    Izenberg, N. R.; McClintock, W. E.; Holsclaw, G. M.; Robinson, M. S.; Blewett, D. T.; Domingue, D. L.; Head, J. W.; Jensen, E. A.; Kochte, M. C.; Lankton, M. R.; Murchie, S. L.; Sprague, A. L.; Vilas, F.; Solomon, S. C.

    2008-05-01

    During the first MESSENGER flyby of Mercury on January 14, 2008, the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) measured reflectance spectra from Mercury's surface over the wavelength range 220-1450 nm. These are the first high-spatial-resolution (<10 km) spectra at any wavelength and the first reported ultraviolet (UV, wavelength < 360 nm) observations of the surface. MASCS observed the sunlit surface for approximately 14 minutes after closest approach, acquiring over 650 spectra with the Visible and Infrared Spectrograph (VIRS) detectors of MASCS sensitive to wavelengths of 350-1450 nm. MASCS also obtained just under four grating scans in the middle ultraviolet (220-320 nm) using MASCS's Ultraviolet and Visible Spectrometer (UVVS) component. Most of the near-equatorial ground track of the observation covered terrain in the previously unseen hemisphere of Mercury but also crossed into the hemisphere viewed by Mariner 10 south of Mozart crater and in Tir Planitia. Ground-based observations of Mercury reveal a surface with a red, nearly featureless spectrum in the visible and near-infrared (wavelengths greater than ~ 500 nm) that has been interpreted as evidence for a largely iron-poor feldspathic composition. Initial analyses of VIRS spectra also show strongly red-sloped, near featureless spectra, appearing to support contentions of low iron abundance in surface materials. However, interpretation of Mercury's spectral reflectance is complicated by our lack of knowledge about the effects on its surface materials of space weathering, which both suppresses the strength of spectral absorption features and reddens the spectrum. Brightness variations and absorption bands in ultraviolet reflectance may help determine both the nature and extent of processes that modify observed reflectance at longer wavelengths. MASCS surface observation data demonstrate spectral variations across the Mercury surface that can be related to previous telescopic

  6. Ultraviolet Views of Enceladus, Tethys, and Dione

    NASA Technical Reports Server (NTRS)

    Hansen, C. J.; Hendrix, A. R.

    2005-01-01

    The Cassini Ultraviolet Imaging Spectrograph (UVIS) has collected ultraviolet observations of many of Saturn's icy moons since Cassini's insertion into orbit around Saturn. We will report on results from Enceladus, Tethys and Dione, orbiting in the Saturn system at distances of 3.95, 4.88 and 6.26 Saturn radii, respectively. Icy satellite science objectives of the UVIS include investigations of surface age and evolution, surface composition and chemistry, and tenuous exospheres. We address these objectives by producing albedo maps, and reflection and emission spectra, and observing stellar occultations. UVIS has four channels: EUV: Extreme Ultraviolet (55 nm to 110 nm), FUV: Far Ultraviolet (110 to 190 nm), HSP: High Speed Photometer, and HDAC: Hydrogen-Deuterium Absorption Cell. The EUV and FUV spectrographs image onto a 2-dimensional detector, with 64 spatial rows by 1024 spectral columns. To-date we have focused primarily on the far ultraviolet data acquired with the low resolution slit width (4.8 angstrom spectral resolution). Additional information is included in the original extended abstract.

  7. Ultraviolet radiation therapy and UVR dose models.

    PubMed

    Grimes, David Robert

    2015-01-01

    Ultraviolet radiation (UVR) has been an effective treatment for a number of chronic skin disorders, and its ability to alleviate these conditions has been well documented. Although nonionizing, exposure to ultraviolet (UV) radiation is still damaging to deoxyribonucleic acid integrity, and has a number of unpleasant side effects ranging from erythema (sunburn) to carcinogenesis. As the conditions treated with this therapy tend to be chronic, exposures are repeated and can be high, increasing the lifetime probability of an adverse event or mutagenic effect. Despite the potential detrimental effects, quantitative ultraviolet dosimetry for phototherapy is an underdeveloped area and better dosimetry would allow clinicians to maximize biological effect whilst minimizing the repercussions of overexposure. This review gives a history and insight into the current state of UVR phototherapy, including an overview of biological effects of UVR, a discussion of UVR production, illness treated by this modality, cabin design and the clinical implementation of phototherapy, as well as clinical dose estimation techniques. Several dose models for ultraviolet phototherapy are also examined, and the need for an accurate computational dose estimation method in ultraviolet phototherapy is discussed.

  8. Ultraviolet radiation therapy and UVR dose models

    SciTech Connect

    Grimes, David Robert

    2015-01-15

    Ultraviolet radiation (UVR) has been an effective treatment for a number of chronic skin disorders, and its ability to alleviate these conditions has been well documented. Although nonionizing, exposure to ultraviolet (UV) radiation is still damaging to deoxyribonucleic acid integrity, and has a number of unpleasant side effects ranging from erythema (sunburn) to carcinogenesis. As the conditions treated with this therapy tend to be chronic, exposures are repeated and can be high, increasing the lifetime probability of an adverse event or mutagenic effect. Despite the potential detrimental effects, quantitative ultraviolet dosimetry for phototherapy is an underdeveloped area and better dosimetry would allow clinicians to maximize biological effect whilst minimizing the repercussions of overexposure. This review gives a history and insight into the current state of UVR phototherapy, including an overview of biological effects of UVR, a discussion of UVR production, illness treated by this modality, cabin design and the clinical implementation of phototherapy, as well as clinical dose estimation techniques. Several dose models for ultraviolet phototherapy are also examined, and the need for an accurate computational dose estimation method in ultraviolet phototherapy is discussed.

  9. Oxygen abundances in low surface-brightness galaxies

    NASA Technical Reports Server (NTRS)

    Roennback, Jari

    1993-01-01

    Recent theories predict that some protogalaxies, in low-density environments of the field, are contracting and interacting so slowly that global star formation can be delayed until today. These systems should be gas rich and have low surface-brightness. Blue compact galaxies (BCG's) and other compact HII region galaxies currently experiencing a burst of star formation are good candidates of truly young galaxies (in the sense that global star formation recently has been initiated). If they really are young, they ought to have a recent phase when their brightness was much lower than in the bursting phase. No claims of observations of such proto-BCG's exist. Observations of galaxies in their juvenile phases would undoubtedly be of great interest, e.g. the determination of the primordial helium abundance would improve. A proper place to search for young nearby galaxies could be among blue low surface-brightness galaxies (BLSBG's) in the local field. The study of low surface-brightness galaxies (LSBG's) as a group began relatively recently. They are galaxies with extraordinary properties both as individuals and as a group. A few years ago we started an optical study of a sample of BLSBG's selected from the ESO/Uppsala catalogue. Results of spectroscopic observations obtained on a subsample - 8 galaxies - of our selection are reported. The HII region oxygen chemical abundances and its relation to the blue absolute magnitude and surface-brightness is investigated.

  10. Dark-bright soliton interactions beyond the integrable limit

    NASA Astrophysics Data System (ADS)

    Katsimiga, G. C.; Stockhofe, J.; Kevrekidis, P. G.; Schmelcher, P.

    2017-01-01

    In this work we present a systematic theoretical analysis regarding dark-bright solitons and their interactions, motivated by recent advances in atomic two-component repulsively interacting Bose-Einstein condensates. In particular, we study analytically via a two-soliton ansatz adopted within a variational formulation the interaction between two dark-bright solitons in a homogeneous environment beyond the integrable regime, by considering general inter- and intra-atomic interaction coefficients. We retrieve the possibility of a fixed point in the case where the bright solitons are out of phase. As the intercomponent interaction is increased, we also identify an exponential instability of the two-soliton state, associated with a subcritical pitchfork bifurcation. The latter gives rise to an asymmetric partition of the bright soliton mass and dynamically leads to spontaneous splitting of the bound pair. In the case of the in-phase bright solitons, we explain via parsing the analytical approximations and monitoring the direct dynamics why no such pair is identified, despite its prediction by the variational analysis.

  11. Night Sky Brightness at San Pedro Martir Observatory

    NASA Astrophysics Data System (ADS)

    Plauchu-Frayn, I.; Richer, M. G.; Colorado, E.; Herrera, J.; Córdova, A.; Ceseña, U.; Ávila, F.

    2017-03-01

    We present optical UBVRI zenith night sky brightness measurements collected on 18 nights during 2013 to 2016 and SQM measurements obtained daily over 20 months during 2014 to 2016 at the Observatorio Astronómico Nacional on the Sierra San Pedro Mártir (OAN-SPM) in México. The UBVRI data is based upon CCD images obtained with the 0.84 m and 2.12 m telescopes, while the SQM data is obtained with a high-sensitivity, low-cost photometer. The typical moonless night sky brightness at zenith averaged over the whole period is U = 22.68, B = 23.10, V = 21.84, R = 21.04, I = 19.36, and SQM = 21.88 {mag} {{arcsec}}-2, once corrected for zodiacal light. We find no seasonal variation of the night sky brightness measured with the SQM. The typical night sky brightness values found at OAN-SPM are similar to those reported for other astronomical dark sites at a similar phase of the solar cycle. We find a trend of decreasing night sky brightness with decreasing solar activity during period of the observations. This trend implies that the sky has become darker by Δ U = 0.7, Δ B = 0.5, Δ V = 0.3, Δ R=0.5 mag arcsec‑2 since early 2014 due to the present solar cycle.

  12. PROFFIT: Analysis of X-ray surface-brightness profiles

    NASA Astrophysics Data System (ADS)

    Eckert, Dominique

    2016-08-01

    PROFFIT analyzes X-ray surface-brightness profiles for data from any X-ray instrument. It can extract surface-brightness profiles in circular or elliptical annuli, using constant or logarithmic bin size, from the image centroid, the surface-brightness peak, or any user-given center, and provides surface-brightness profiles in any circular or elliptical sectors. It offers background map support to extract background profiles, can excise areas using SAO DS9-compatible (ascl:0003.002) region files to exclude point sources, provides fitting with a number of built-in models, including the popular beta model, double beta, cusp beta, power law, and projected broken power law, uses chi-squared or C statistic, and can fit on the surface-brightness or counts data. It has a command-line interface similar to HEASOFT’s XSPEC (ascl:9910.005) package, provides interactive help with a description of all the commands, and results can be saved in FITS, ROOT or TXT format.

  13. Sky brightness and twilight measurements at Jogyakarta city, Indonesia

    NASA Astrophysics Data System (ADS)

    Herdiwijaya, Dhani

    2016-11-01

    The sky brightness measurements were performed using a portable photometer. A pocket-sized and low-cost photometer has 20 degree area measurement, and spectral ranges between 320-720 nm with output directly in magnitudes per arc second square (mass) unit. The sky brightness with 3 seconds temporal resolutions was recorded at Jogyakarta city (110° 25’ E; 70° 52’ S; elevation 100 m) within 136 days in years from 2014 to 2016. The darkest night could reach 22.61 mpass only in several seconds, with mean value 18.8±0.7 mpass and temperature variation 23.1±1.2 C. The difference of mean sky brightness between before and after midnight was about -0.76 mpass or 2.0 times brighter. Moreover, the sky brightness and temperature fluctuations were more stable in after midnight than in before midnight. It is suggested that city light pollution affects those variations, and subsequently duration of twilight. By comparing twilight brightness for several places, we also suggest a 17° solar dip or about 66 minutes before sunrise for new time of Fajr prayer.

  14. Hyperspectral bright greenish-yellow fluorescence (BGYF) imaging of aflatoxin contaminated corn kernels

    NASA Astrophysics Data System (ADS)

    Yao, Haibo; Hruska, Zuzana; Brown, Robert L.; Cleveland, Thomas E.

    2006-10-01

    Aflatoxin contaminated corn poses a serious threat to both domestic animals and humans, because of its carcinogenic properties. Traditionally, corn kernels have been examined for evidence of bright greenish-yellow fluorescence (BGYF), which is an indication of possible presence of Aspergillus flavus, one of the aflatoxin producing strains of fungi, when illuminated with a high-intensity ultra-violet light. The BGYF test is typically the first step that leads to an in-depth chemical analysis for possible aflatoxin contamination. The objective of the present study was to analyze hyperspectral BGYF response of corn kernels under UVA excitation. The target corn samples were collected from a commercial corn field in 2005 and showed abundant BGYF response. The BGYF positive kernels were manually picked out and imaged under a visible near-infrared hyperspectral imaging system under UV radiation with excitation wavelength centered at 365 nm. Initial results exhibited strong emission spectra with peaks centered from 500 nm to 515 nm wavelength range for BGYF positive kernels. Aflatoxin levels on the BGYF positive and negative corn kernels (used as control) were measured subsequently with high performance liquid chromatography. The mean aflatoxin concentration level was 5114 ppb for the BGYF positive and undetectable for the normal kernels.

  15. DISCOVERY OF A BRIGHT, EXTREMELY LOW MASS WHITE DWARF IN A CLOSE DOUBLE DEGENERATE SYSTEM

    SciTech Connect

    Vennes, S.; Kawka, A.; Nemeth, P.; Thorstensen, J. R.; Skinner, J. N.; Pigulski, A.; Steslicki, M.; Kolaczkowski, Z.; Srodka, P.

    2011-08-10

    We report the discovery of a bright (V {approx} 13.7), extremely low mass white dwarf in a close double degenerate system. We originally selected GALEX J171708.5+675712 for spectroscopic follow-up among a group of white dwarf candidates in an ultraviolet-optical reduced proper-motion diagram. The new white dwarf has a mass of 0.18 M{sub sun} and is the primary component of a close double degenerate system (P = 0.246137 days, K{sub 1} = 288 km s{sup -1}) comprising a fainter white dwarf secondary with M{sub 2} {approx} 0.9 M{sub sun}. Light curves phased with the orbital ephemeris show evidence of relativistic beaming and weaker ellipsoidal variations. The light curves also reveal secondary eclipses (depth {approx}8 mmag) while the primary eclipses appear partially compensated by the secondary gravitational deflection and are below detection limits. Photospheric abundance measurements show a nearly solar composition of Si, Ca, and Fe (0.1-1 sun), while the normal kinematics suggest a relatively recent formation history. Close binary evolutionary scenarios suggest that extremely low mass white dwarfs form via a common-envelope phase and possible Roche lobe overflow.

  16. Second COS FUV Lifetime Position: Verification of FUV Bright Object Aperture (BOA) Operations (FCAL4)

    NASA Astrophysics Data System (ADS)

    Debes, John H.

    2013-05-01

    As part of the calibration of the second lifetime position on the Cosmic Origins Spectrograph (COS) far-ultraviolet (FUV) detectors, observations of the external target, G191-B2B, were obtained with the G130M, G160M, and G140L gratings in combi- nation with the Bright Object Aperture. The observations were designed to verify the performance of these spectroscopic modes by reproducing similar observations taken during the SM4 Servicing Mission Observatory Verification (SMOV) of COS. These observations allowed for a detailed determination of the spatial location and profile of the spectra from the three gratings, as well as a determination of the spectral resolution of the G130M grating prior to and after the lifetime move. In general, the negligi- ble differences which exist between the two lifetime positions can be attributed to slight differences in the optical path. In particular, the spectral resolution appears to be slightly improved. The stability of the absolute and relative flux calibration was investigated for G130M as well using STIS echelle data of G191-B2B. We determine that the COS ab- solute flux calibration with the BOA is accurate to 10%, and flux calibrated data are reproducible at the 1-2% level since SMOV.

  17. The effect of surface brightness dimming in the selection of high-z galaxies

    SciTech Connect

    Calvi, V.; Stiavelli, M.; Bradley, L.; Pizzella, A.; Kim, S.

    2014-12-01

    Cosmological surface brightness (SB) dimming of the form (1 + z){sup –4} affects all sources. The strong dependence of SB dimming on redshift z suggests the presence of a selection bias when searching for high-z galaxies, i.e., we tend to detect only those galaxies with a high SB. However, unresolved knots of emission are not affected by SB dimming, thus providing a way to test the clumpiness of high-z galaxies. Our strategy relies on the comparison of the total flux detected for the same source in surveys characterized by different depth. For all galaxies, deeper images permit the better investigation of low-SB features. Cosmological SB dimming makes these low-SB features hard to detect when going to higher and higher redshifts. We used the GOODS and HUDF Hubble Space Telescope legacy data sets to study the effect of SB dimming on low-SB features of high-z galaxies and compare it to the prediction for smooth sources. We selected a sample of Lyman-break galaxies at z ∼ 4 (i.e., B {sub 435}-band dropouts) detected in all of the data sets and found no significant trend when comparing the total magnitudes measured from images with different depth. Through Monte Carlo simulations we derived the expected trend for galaxies with different SB profiles. The comparison to the data hints at a compact distribution for most of the rest-frame ultraviolet light emitted from high-z galaxies.

  18. The XMM-Newton Bright Survey sample of absorbed quasars: X-ray and accretion properties

    NASA Astrophysics Data System (ADS)

    Ballo, L.; Severgnini, P.; Della Ceca, R.; Caccianiga, A.; Vignali, C.; Carrera, F. J.; Corral, A.; Mateos, S.

    2014-11-01

    Although absorbed quasars are extremely important for our understanding of the energetics of the Universe, the main physical parameters of their central engines are still poorly known. In this work, we present and study a complete sample of 14 quasars (QSOs) that are absorbed in the X-rays (column density NH > 4 × 1021 cm-2 and X-ray luminosity L 2-10 keV > 1044 ergs-1; XQSO2) belonging to the XMM-Newton Bright Serendipitous Survey (XBS). From the analysis of their ultraviolet-to-mid-infrared spectral energy distribution, we can separate the nuclear emission from the host galaxy contribution, obtaining a measurement of the fundamental nuclear parameters, like the mass of the central supermassive black hole and the value of Eddington ratio, λ Edd. Comparing the properties of XQSO2s with those previously obtained for the X-ray unabsorbed QSOs in the XBS, we do not find any evidence that the two samples are drawn from different populations. In particular, the two samples span the same range in Eddington ratios, up to λ Edd ˜ 0.5; this implies that our XQSO2s populate the `forbidden region' in the so-called `effective Eddington limit paradigm'. A combination of low grain abundance, presence of stars inwards of the absorber, and/or anisotropy of the disc emission can explain this result.

  19. Bright and Not-So-Bright Prospects for Women in Physics in China-Beijing

    NASA Astrophysics Data System (ADS)

    Wu, Ling-An; Yang, Zhongqin; Ma, Wanyun

    2009-04-01

    Science in China-Beijing is enjoying a healthy increase in funding year by year, so the prospects for physicists are also bright. However, employment discrimination against women, formerly unthinkable, is becoming more and more explicit as the country evolves toward a market economy. Some recruitment notices bluntly state that only men will be considered, or impose restrictions upon potential female candidates. Female associate professors in many institutions are forced to retire at age 55, compared with 60 for men. This double-pinching discrimination against both younger and older women threatens to lead to a "pincer" effect, more serious than the "scissors" effect. Indeed, the ratio of senior-level women physicists in general has dropped significantly in recent years in China. Ironically, the number of female students applying for graduate studies is on the rise, as it is becoming increasingly difficult for them to compete with men in the job market with just an undergraduate degree. The Chinese Physical Society has made certain efforts to promote the image of women physicists, but it will take time and effort to reverse the trend.

  20. Far ultraviolet excitation processes in comets

    NASA Technical Reports Server (NTRS)

    Feldman, P. D.; Opal, C. B.; Meier, R. R.; Nicolas, K. R.

    1976-01-01

    Recent observations of atomic oxygen and carbon in the far ultraviolet spectrum of comet Kohoutek have demonstrated the existence of these atomic species in the cometary coma. However, in order to identify the source of their origin, it is necessary to relate the observed ultraviolet flux to the atomic production rate. Analyses of observed OI wavelength 1304 and CI wavelength 1657 A multiplets have been carried out using high resolution solar spectra. Also examined is the possibility of observing ultraviolet fluorescence from molecules such as CO and H2, as well as resonance scattering either from atomic ions for which there are strong corresponding solar lines (CII) or from atoms for which there is an accidental wavelength coincidence (SI).

  1. Rocket observations of the diffuse ultraviolet background

    NASA Technical Reports Server (NTRS)

    Jakobsen, P.; Bowyer, S.; Kimble, R.; Jelinsky, P.; Grewing, M.; Kraemer, G.; Wulf-Mathies, C.

    1984-01-01

    The objective of the experiment reported here was to obtain additional information on the absolute intensity level and spatial variation of the diffuse ultraviolet background and thereby gain insight into the origin of this radiation. The experiment used three ultraviolet sensitive photometers placed in the focal plane of a 95-cm, f/2.8 normal incidence telescope flown on board an Aries sounding rocket. The measured intensities clearly refute the hypothesis of an isotropic background, the intensities of the high galactic latitude being definitely lower than the intensities seen at intermediate latitudes. Moreover, the count rates in all three channels along the slow scan exhibit local enhancements as well as an overall trend. In general, the spatial variations exhibited by the data correlate with the line of sight of neutral hydrogen column density as determined from 21-cm radio observations. This fact demonstrates that there is a galactic component to the diffuse ultraviolet radiation field.

  2. Photoresist composition for extreme ultraviolet lithography

    DOEpatents

    Felter, T. E.; Kubiak, G. D.

    1999-01-01

    A method of producing a patterned array of features, in particular, gate apertures, in the size range 0.4-0.05 .mu.m using projection lithography and extreme ultraviolet (EUV) radiation. A high energy laser beam is used to vaporize a target material in order to produce a plasma which in turn, produces extreme ultraviolet radiation of a characteristic wavelength of about 13 nm for lithographic applications. The radiation is transmitted by a series of reflective mirrors to a mask which bears the pattern to be printed. The demagnified focused mask pattern is, in turn, transmitted by means of appropriate optics and in a single exposure, to a substrate coated with photoresists designed to be transparent to EUV radiation and also satisfy conventional processing methods. A photoresist composition for extreme ultraviolet radiation of boron carbide polymers, hydrochlorocarbons and mixtures thereof.

  3. Occupational Skin Hazards From Ultraviolet (UV) Exposures

    NASA Astrophysics Data System (ADS)

    Urbach, F.; Wolbarsht, M. L.

    1981-11-01

    The various types of UV effects on the skin are classified according to the part of the spectrum and their beneficial or deleterious nature. Some hazardous ultraviolet sources used in industrial processes are described, and examples of photoallergy, phototoxicity, and photosensitization resulting from UV exposures are given. The incidence of skin cancer as a function of geographical location and exposure to sunlight is discussed in relation to natural and artificial exposures to long and short wavelength UV, especially in connection with tanning booths. The conclusion is reached that there is enough ultraviolet in a normal environment to propose a hazard, and additional ultraviolet exposure from industrial or consumer sources is not necessary, and should be eliminated wherever possible.

  4. Occupational Skin Hazards From Ultraviolet (UV) Exposures

    NASA Astrophysics Data System (ADS)

    Urbach, F.; Wolbarsht, M. L.

    1980-10-01

    The various types of UV effects on the skin are classified according to the part of the spectrum and their beneficial or deleterious nature. Some hazardous ultraviolet sources used in industrial processes are described, and examples of photoallergy, phototoxicity, and photosensitization resulting from UV exposures are given. The incidence of skin cancer as a function of geographical location and exposure to sunlight is discussed in relation to natural and artificial exposures to long and short wavelength UV, especially in connection with tanning booths. The conclusion is reached that there is enough ultraviolet in a normal environment to propose a hazard, and additional ultraviolet exposure from industrial or consumer sources is not necessary, and should be eliminated wherever possible.

  5. Photoresist composition for extreme ultraviolet lithography

    SciTech Connect

    Felter, T.E.; Kubiak, G.D.

    1999-11-23

    A method of producing a patterned array of features, in particular, gate apertures, in the size range 0.4--0.05 {mu}m using projection lithography and extreme ultraviolet (EUV) radiation is disclosed. A high energy laser beam is used to vaporize a target material in order to produce a plasma which in turn, produces extreme ultraviolet radiation of a characteristic wavelength of about 13 nm for lithographic applications. The radiation is transmitted by a series of reflective mirrors to a mask which bears the pattern to be printed. The demagnified focused mask pattern is, in turn, transmitted by means of appropriate optics and in a single exposure, to a substrate coated with photoresists designed to be transparent to EUV radiation and also satisfy conventional processing methods. A photoresist composition for extreme ultraviolet radiation of boron carbide polymers, hydrochlorocarbons and mixtures thereof.

  6. Cell structure imaging with bright and homogeneous nanometric light source.

    PubMed

    Fukuta, Masahiro; Ono, Atsushi; Nawa, Yasunori; Inami, Wataru; Shen, Lin; Kawata, Yoshimasa; Terekawa, Susumu

    2017-04-01

    Label-free optical nano-imaging of dendritic structures and intracellular granules in biological cells is demonstrated using a bright and homogeneous nanometric light source. The optical nanometric light source is excited using a focused electron beam. A zinc oxide (ZnO) luminescent thin film was fabricated by atomic layer deposition (ALD) to produce the nanoscale light source. The ZnO film formed by ALD emitted the bright, homogeneous light, unlike that deposited by another method. The dendritic structures of label-free macrophage receptor with collagenous structure-expressing CHO cells were clearly visualized below the diffraction limit. The inner fiber structure was observed with 120 nm spatial resolution. Because the bright homogeneous emission from the ZnO film suppresses the background noise, the signal-to-noise ratio (SNR) for the imaging results was greater than 10. The ALD method helps achieve an electron beam excitation assisted microscope with high spatial resolution and high SNR.

  7. Brightness of the Sky during a Solar Eclipse

    NASA Astrophysics Data System (ADS)

    Milisavljevic, D.; Nedeljkovic, S.; Miovic, V.

    2000-01-01

    Observations of the relative brightness of the sky were carried out in Horgos, Yugoslavia, and in Kamen Bryag, Bulgaria, during the total solar eclipse on August 11, 1999. The results were compared with observations of the partial solar eclipse of October 24, 1995, in Calcutta, India, and with some simple eclipse models based on the approximations for the limb darkening of the solar disc. The differences between the relative brightness of the sky during partial and during total solar eclipses are noticed, The measured brightness curve of the total eclipse rapidly declines immediately before, and it starts to grow rapidly immediately after the eclipse totality, while the curve of the partial eclipse has neither rapid declining nor growing.

  8. Shiftwork in space - Bright light as a chronobiologic countermeasure

    NASA Technical Reports Server (NTRS)

    Gander, Philippa H.; Samel, Alexander

    1991-01-01

    The potential of timed exposures to bright light as a countermeasure to the changes in the work/rest schedules during space missions was investigated. In the experiments, four human subjects were exposed to two sessions of eleven days of simulated weightlessness (6-deg head-down-tilt bedrest) with 6-hr extensions of the scheduled wake time on days 3 and 4 (a 12-hr phase delay). In a blind crossover design, subjects were exposed to bright light (greater than 3500 lux) for 5 hrs on each of the two shift days and on the following day, at times expected to accelerate adaptation to the phase delay (experimental group), or have no phase shifting effect (control group). Results indicate that bright light may accelerate the rate of adaptation to work/rest schedule delays under simulated weightlessness conditions. However, such effect was found to be largely independent of the timing of the light exposure.

  9. Intensity oscillations in chromospheric bright points and network elements

    NASA Astrophysics Data System (ADS)

    Kariyappa, R.

    1994-09-01

    From a 35-min time series of photographic spectra in the Ca II H-line obtained at the Vacuum Tower Telescope (VTT) of the Sacramento Peak Observatory under high spatial, spectral, and temporal resolution, we have derived a large number of H-line profiles at the sites of the bright points in the interior of the supergranulation cells, and at the network elements, on a quiet region at the center of the solar disc. It is shown that the bright points are associated with 3-min periodicity in their intensity oscillations whereas the network elements exhibit approximately 7-min periodicity. It is surmised that the large difference in periods of the intensity oscillations, the strength of the magnetic fields, and the intensity enhancements at the sites of the bright points and the network elements themselves may probably be taken as evidence to argue that the mechanisms of heating in the two cases are dissimilar, irrespective of the sizes of these structures.

  10. Bright Stuff on Ceres = Sulfates and Carbonates on CI Chondrites

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael; Chan, Queenie H. S.; Gounelle, Matthieu; Fries, Marc

    2016-01-01

    Recent reports of the DAWN spacecraft's observations of the surface of Ceres indicate that there are bright areas, which can be explained by large amounts of the Mg sulfate hexahydrate (MgSO4•6(H2O)), although the identification appears tenuous. There are preliminary indications that water is being evolved from these bright areas, and some have inferred that these might be sites of contemporary hydro-volcanism. A heat source for such modern activity is not obvious, given the small size of Ceres, lack of any tidal forces from nearby giant planets, probable age and presumed bulk composition. We contend that observations of chondritic materials in the lab shed light on the nature of the bright spots on Ceres

  11. The ASAS-SN Bright Supernova Catalog - II. 2015

    NASA Astrophysics Data System (ADS)

    Holoien, T. W.-S.; Brown, J. S.; Stanek, K. Z.; Kochanek, C. S.; Shappee, B. J.; Prieto, J. L.; Dong, Subo; Brimacombe, J.; Bishop, D. W.; Basu, U.; Beacom, J. F.; Bersier, D.; Chen, Ping; Danilet, A. B.; Falco, E.; Godoy-Rivera, D.; Goss, N.; Pojmanski, G.; Simonian, G. V.; Skowron, D. M.; Thompson, Todd A.; Woźniak, P. R.; Ávila, C. G.; Bock, G.; Carballo, J.-L. G.; Conseil, E.; Contreras, C.; Cruz, I.; Andújar, J. M. F.; Guo, Zhen; Hsiao, E. Y.; Kiyota, S.; Koff, R. A.; Krannich, G.; Madore, B. F.; Marples, P.; Masi, G.; Morrell, N.; Monard, L. A. G.; Munoz-Mateos, J. C.; Nicholls, B.; Nicolas, J.; Wagner, R. M.; Wiethoff, W. S.

    2017-01-01

    This manuscript presents information for all supernovae discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN) during 2015, its second full year of operations. The same information is presented for bright (mV ≤ 17), spectroscopically confirmed supernovae discovered by other sources in 2015. As with the first ASAS-SN bright supernova catalog, we also present redshifts and near-UV through IR magnitudes for all supernova host galaxies in both samples. Combined with our previous catalog, this work comprises a complete catalog of 455 supernovae from multiple professional and amateur sources, allowing for population studies that were previously impossible. This is the second of a series of yearly papers on bright supernovae and their hosts from the ASAS-SN team.

  12. On the relation between zenith sky brightness and horizontal illuminance

    NASA Astrophysics Data System (ADS)

    Kocifaj, M.; Posch, Th.; Solano Lamphar, H. A.

    2015-01-01

    The effects of artificial light at night are an emergent research topic for astronomers, physicists, engineers and biologists around the world. This leads to a need for measurements of the night sky brightness (= diffuse luminance of the night sky) and nocturnal illuminance. Currently, the most sensitive light meters measure the zenith sky brightness in magV/arcsec2 or - less frequently - in cd m-2. However, the horizontal illuminance resulting only from the night sky is an important source of information that is difficult to obtain with common instruments. Here we present a set of approximations to convert the zenith luminance into horizontal illuminance. Three different approximations are presented for three idealized atmospheric conditions: homogeneous sky brightness, an isotropically scattering atmosphere and a turbid atmosphere. We also apply the resulting conversion formulae to experimental data on night sky luminance, obtained during the past three years.

  13. Modelling and Display of the Ultraviolet Sky

    NASA Astrophysics Data System (ADS)

    Daniels, J.; Henry, R.; Murthy, J.; Allen, M.; McGlynn, T. A.; Scollick, K.

    1994-12-01

    A computer program is currently under development to model in 3D - one dimension of which is wavelength - all the known and major speculated sources of ultraviolet (900 A - 3100 A ) radiation over the celestial sphere. The software is being written in Fortran 77 and IDL and currently operates under IRIX (the operating system of the Silicon Graphics Iris Machine); all output models are in FITS format. Models along with display software will become available to the astronomical community. The Ultraviolet Sky Model currently includes the Zodiacal Light, Point Sources of Emission, and the Diffuse Galactic Light. The Ultraviolet Sky Model is currently displayed using SkyView: a package under development at NASA/ GSFC, which allows users to retrieve and display publically available all-sky astronomical survey data (covering many wavebands) over the Internet. We present a demonstration of the SkyView display of the Ultraviolet Model. The modelling is a five year development project: the work illustrated here represents product output at the end of year one. Future work includes enhancements to the current models and incorporation of the following models: Galactic Molecular Hydrogen Fluorescence; Galactic Highly Ionized Atomic Line Emission; Integrated Extragalactic Light; and speculated sources in the intergalactic medium such as Ionized Plasma and radiation from Non-Baryonic Particle Decay. We also present a poster which summarizes the components of the Ultraviolet Sky Model and outlines a further package that will be used to display the Ultraviolet Model. This work is supported by United States Air Force Contract F19628-93-K-0004. Dr J. Daniels is supported with a post-doctoral Fellowship from the Leverhulme Foundation, London, United Kingdom. We are also grateful for the encouragement of Dr Stephen Price (Phillips Laboratory, Hanscomb Air Force Base, MA)

  14. Life-threatening motor vehicle crashes in bright sunlight.

    PubMed

    Redelmeier, Donald A; Raza, Sheharyar

    2017-01-01

    Bright sunlight may create visual illusions that lead to driver error, including fallible distance judgment from aerial perspective. We tested whether the risk of a life-threatening motor vehicle crash was increased when driving in bright sunlight.This longitudinal, case-only, paired-comparison analysis evaluated patients hospitalized because of a motor vehicle crash between January 1, 1995 and December 31, 2014. The relative risk of a crash associated with bright sunlight was estimated by evaluating the prevailing weather at the time and place of the crash compared with the weather at the same hour and location on control days a week earlier and a week later.The majority of patients (n = 6962) were injured during daylight hours and bright sunlight was the most common weather condition at the time and place of the crash. The risk of a life-threatening crash was 16% higher during bright sunlight than normal weather (95% confidence interval: 9-24, P < 0.001). The increased risk was accentuated in the early afternoon, disappeared at night, extended to patients with different characteristics, involved crashes with diverse features, not apparent with cloudy weather, and contributed to about 5000 additional patient-days in hospital. The increased risk extended to patients with high crash severity as indicated by ambulance involvement, surgical procedures, length of hospital stay, intensive care unit admission, and patient mortality. The increased risk was not easily attributed to differences in alcohol consumption, driving distances, or anomalies of adverse weather.Bright sunlight is associated with an increased risk of a life-threatening motor vehicle crash. An awareness of this risk might inform driver education, trauma staffing, and safety warnings to prevent a life-threatening motor vehicle crash.

  15. The possible origin of facular brightness in the solar atmosphere

    NASA Astrophysics Data System (ADS)

    Kostik, R.; Khomenko, E.

    2016-05-01

    This paper studies the dependence of the Ca ii H line core brightness on the strength and inclination of the photospheric magnetic field, and on the parameters of convective and wave motions in a facular region at the center of the solar disc. We use three simultaneous data sets that were obtained at the German Vacuum Tower Telescope (Observatorio del Teide, Tenerife): (1) spectra of Ba ii 4554 Å line, registered with the instrument TESOS to measure the variations of intensity and velocity through the photosphere up to the temperature minimum; (2) spectropolarimetric data in Fe i 1.56 μm lines (registered with the instrument TIP II) to measure photospheric magnetic fields; (3) filtergrams in Ca ii H that give information about brightness fluctuations in the chromosphere. The results show that the Ca ii H brightness in the facula strongly depends on the power of waves with periods in the 5-min range, which propagate upwards, and also on the phase shift between velocity oscillations at the bottom photosphere and around the temperature minimum height that is measured from Ba ii line. The Ca ii H brightness is maximum at locations where the phase shift between temperature and velocity oscillations lies within 0°-100°. There is an indirect influence of convective motions on the Ca ii H brightness. The higher the amplitude of convective velocities is and the greater the height is where they change their direction of motion, the brighter the facula. In summary, our results lead to conclusions that facular regions appear bright not only because of the Wilson depression in magnetic structures, but also owing to real heating.

  16. Brightness discrimination in the South African fur seal (Arctocephalus pusillus).

    PubMed

    Scholtyssek, C; Dehnhardt, G

    2013-05-24

    Underwater, the contrast between object and background is much larger reduced with increasing distance between object and observer than in air. For marine predators, such as pinnipeds, it would therefore be advantageous to possess a high sensitivity for brightness differences, since this would increase the distance at which prey can be detected visually. Few studies have examined the brightness discrimination thresholds of pinnipeds. Two studies with phocid seals have confirmed low brightness discrimination thresholds in pinnipeds whereas the threshold obtained for the South African fur seal seems to be twice as high as that of the phocids. However, the experiments with the South African fur seal have been conducted under inadequate conditions which likely resulted in an underestimation of the brightness discrimination ability of this species. The study at hand reinvestigated the brightness discrimination threshold of the South African fur seal under well controlled conditions. In a two alternative forced choice task, one fur seal was trained to indicate the position of the brighter of two gray discs presented on a black background on a monitor. The thresholds were determined for 11 standard intensities each tested against 8 lower comparison intensities. It was found that the fur seal was able to perceive brightness differences of 8-10%, which is better than the phocid species tested so far. For low standard intensities, however, the threshold increased which could to be due to a relative slow dark adaptation rate of the fur seal. The results are discussed in terms of the relevance of visual information for pinnipeds during foraging dives and are directly compared to the results obtained for the harbor seal which has been tested under the same conditions as the fur seal in a previous study.

  17. Life-threatening motor vehicle crashes in bright sunlight

    PubMed Central

    Redelmeier, Donald A.; Raza, Sheharyar

    2017-01-01

    Abstract Bright sunlight may create visual illusions that lead to driver error, including fallible distance judgment from aerial perspective. We tested whether the risk of a life-threatening motor vehicle crash was increased when driving in bright sunlight. This longitudinal, case-only, paired-comparison analysis evaluated patients hospitalized because of a motor vehicle crash between January 1, 1995 and December 31, 2014. The relative risk of a crash associated with bright sunlight was estimated by evaluating the prevailing weather at the time and place of the crash compared with the weather at the same hour and location on control days a week earlier and a week later. The majority of patients (n = 6962) were injured during daylight hours and bright sunlight was the most common weather condition at the time and place of the crash. The risk of a life-threatening crash was 16% higher during bright sunlight than normal weather (95% confidence interval: 9–24, P < 0.001). The increased risk was accentuated in the early afternoon, disappeared at night, extended to patients with different characteristics, involved crashes with diverse features, not apparent with cloudy weather, and contributed to about 5000 additional patient-days in hospital. The increased risk extended to patients with high crash severity as indicated by ambulance involvement, surgical procedures, length of hospital stay, intensive care unit admission, and patient mortality. The increased risk was not easily attributed to differences in alcohol consumption, driving distances, or anomalies of adverse weather. Bright sunlight is associated with an increased risk of a life-threatening motor vehicle crash. An awareness of this risk might inform driver education, trauma staffing, and safety warnings to prevent a life-threatening motor vehicle crash. Level of evidence: Epidemiologic Study, level III. PMID:28072708

  18. Effects of bright light treatment on psychomotor speed in athletes

    PubMed Central

    Tulppo, Mikko P.; Jurvelin, Heidi; Roivainen, Eka; Nissilä, Juuso; Hautala, Arto J.; Kiviniemi, Antti M.; Kiviniemi, Vesa J.; Takala, Timo

    2014-01-01

    Purpose: A recent study suggests that transcranial brain targeted light treatment via ear canals may have physiological effects on brain function studied by functional magnetic resonance imaging (fMRI) techniques in humans. We tested the hypothesis that bright light treatment could improve psychomotor speed in professional ice hockey players. Methods: Psychomotor speed tests with audio and visual warning signals were administered to a Finnish National Ice Hockey League team before and after 24 days of transcranial bright light or sham treatment. The treatments were given during seasonal darkness in the Oulu region (latitude 65 degrees north) when the strain on the players was also very high (10 matches during 24 days). A daily 12-min dose of bright light or sham (n = 11 for both) treatment was given every morning between 8 and 12 am at home with a transcranial bright light device. Mean reaction time and motor time were analyzed separately for both psychomotor tests. Analysis of variance for repeated measures adjusted for age was performed. Results: Time × group interaction for motor time with a visual warning signal was p = 0.024 after adjustment for age. In Bonferroni post-hoc analysis, motor time with a visual warning signal decreased in the bright light treatment group from 127 ± 43 to 94 ± 26 ms (p = 0.024) but did not change significantly in the sham group 121 ± 23 vs. 110 ± 32 ms (p = 0.308). Reaction time with a visual signal did not change in either group. Reaction or motor time with an audio warning signal did not change in either the treatment or sham group. Conclusion: Psychomotor speed, particularly motor time with a visual warning signal, improves after transcranial bright light treatment in professional ice-hockey players during the competition season in the dark time of the year. PMID:24860513

  19. Bright and dark excitons in semiconductor carbon nanotubes

    SciTech Connect

    Tretiak, Sergei

    2008-01-01

    We report electronic structure calculations of finite-length semiconducting carbon nanotubes using the time dependent density functional theory (TD-DFT) and the time dependent Hartree Fock (TD-HF) approach coupled with semiempirical AM1 and ZINDO Hamiltonians. We specifically focus on the energy splitting, relative ordering, and localization properties of the optically active (bright) and optically forbidden (dark) states from the lowest excitonic band of the nanotubes. These excitonic states are very important in competing radiative and non-radiative processes in these systems. Our analysis of excitonic transition density matrices demonstrates that pure DFT functionals overdelocalize excitons making an electron-hole pair unbound; consequently, excitonic features are not presented in this method. In contrast, the pure HF and A111 calculations overbind excitons inaccurately predicting the lowest energy state as a bright exciton. Changing AM1 with ZINDO Hamiltonian in TD-HF calculations, predicts the bright exciton as the second state after the dark one. However, in contrast to AM1 calculations, the diameter dependence of the excitation energies obtained by ZINDO does not follow the experimental trends. Finally, the TD-DFT approach incorporating hybrid functions with a moderate portion of the long-range HF exchange, such as B3LYP, has the most generality and predictive capacity providing a sufficiently accurate description of excitonic structure in finite-size nanotubes. These methods characterize four important lower exciton bands. The lowest state is dark, the upper band is bright, and the two other dark and nearly degenerate excitons lie in-between. Although the calculated energy splittings between the lowest dark and the bright excitons are relatively large ({approx}0.1 eV), the dense excitonic manifold below the bright exciton allows for fast non-radiative relaxation leasing to the fast population of the lowest dark exciton. This rationalizes the low

  20. Pluto's Far Ultraviolet Spectrum and Airglow Emissions

    NASA Astrophysics Data System (ADS)

    Steffl, A.; Schindhelm, E.; Kammer, J.; Gladstone, R.; Greathouse, T. K.; Parker, J. W.; Strobel, D. F.; Summers, M. E.; Versteeg, M. H.; Ennico Smith, K.; Hinson, D. P.; Linscott, I.; Olkin, C.; Parker, A. H.; Retherford, K. D.; Singer, K. N.; Tsang, C.; Tyler, G. L.; Weaver, H. A., Jr.; Woods, W. W.; Young, L. A.; Stern, A.

    2015-12-01

    The Alice far ultraviolet spectrograph on the New Horizons spacecraft is the second in a family of six instruments in flight on, or under development for, NASA and ESA missions. Here, we present initial results from the Alice observations of Pluto during the historic flyby. Pluto's far ultraviolet spectrum is dominated by sunlight reflected from the surface with absorption by atmospehric constituents. We tentatively identify C2H2 and C2H4 in Pluto's atmosphere. We also present evidence for weak airglow emissions.

  1. Far and extreme ultraviolet astronomy with ORFEUS

    NASA Technical Reports Server (NTRS)

    Kraemer, G.; Barnstedt, J.; Eberhard, N.; Grewing, M.; Gringel, W.; Haas, C.; Kaelble, A.; Kappelmann, N.; Petrik, J.; Appenzeller, I.

    1990-01-01

    ORFEUS (Orbiting and Retrievable Far and Extreme Ultraviolet Spectrometer) is a 1 m normal incidence telescope for spectroscopic investigations of cosmic sources in the far and extreme ultraviolet spectral range. The instrument will be integrated into the freeflyer platform ASTRO-SPAS. ORFEUS-SPAS is scheduled with STS ENDEAVOUR in September 1992. We describe the telescope with its two spectrometer and their capabilities i.e., spectral range, resolution and overall sensitivity. The main classes of objects to be observed with the instrument are discussed and two examples of simulated spectra for the white dwarf HZ43 and an O9-star in LMC are shown.

  2. Lunar Ultraviolet Telescope Experiment (LUTE) overview

    NASA Astrophysics Data System (ADS)

    McBrayer, R. O.; Frazier, J.; Nein, M.

    1993-09-01

    The Lunar Ultraviolet Telescope Experiment (LUTE) is a 1-m aperture telescope for imaging the stellar ultraviolet spectrum from the lunar surface. The aspects of Lute's educational value and the information it can provide on designing for the long-term exposure to the lunar environment are important considerations. This paper briefly summarizes the status of the phase A study by the Marshall Space Flight Center's (MSFC) LUTE Task Team. The primary focus will be a discussion of the merits of LUTE as a small and relatively inexpensive project that benefits a wide spectrum of interests and could be operating on the lunar surface by the turn of the century.

  3. Defect-tolerant extreme ultraviolet nanoscale printing.

    PubMed

    Urbanski, L; Isoyan, A; Stein, A; Rocca, J J; Menoni, C S; Marconi, M C

    2012-09-01

    We present a defect-free lithography method for printing periodic features with nanoscale resolution using coherent extreme ultraviolet light. This technique is based on the self-imaging effect known as the Talbot effect, which is produced when coherent light is diffracted by a periodic mask. We present a numerical simulation and an experimental verification of the method with a compact extreme ultraviolet laser. Furthermore, we explore the extent of defect tolerance by testing masks with different defect layouts. The experimental results are in good agreement with theoretical calculations.

  4. Ultraviolet colors of old LMC clusters

    NASA Technical Reports Server (NTRS)

    Cowley, A. P.; Hartwick, F. D. A.

    1992-01-01

    New ultraviolet spectra for five red LMC globular clusters have been obtained with IUE. These have been supplemented with archival spectra for eleven old LMC clusters. These data strengthen and extend the UV-color versus age relation for clusters older than about 10 exp 9 yr, but do not offer much precision in age determination, presumably because the ultraviolet colors of the oldest clusters depend strongly on the horizontal-branch morphology. Comparison of LMC data with UV colors for the brightest M31 clusters suggests their ages might be only a few gigayears.

  5. RXS J16437+3402: A New Bright Cataclysmic Variable

    NASA Astrophysics Data System (ADS)

    Mickaelian, A. M.; Balayan, S. K.; Ilovaisky, S.; Chevalier, C.; Veron-Cetty, M. P.; Veron, P.

    The Second part of the FBS was devoted to search and study of blue stellar objects. Optical identifications have been made for a number of ROSAT sources to find new QSO and Sy candidates. One of the objects, RXS J16437+3402, appeared to be a bright (m = 15.2) and very interesting cataclysmic variable: the Byurakan 2.6 m and OHP 1.93 m observations in 2000 show rapid variations of brightness, colour, and spectral lines. The object is possibly a low-inclination SW Sextantis star.

  6. Laser ion source for high brightness heavy ion beam

    SciTech Connect

    Okamura, M.

    2016-09-01

    A laser ion source is known as a high current high charge state heavy ion source. But, we place great emphasis on the capability to realize a high brightness ion source. A laser ion source has a pinpoint small volume where materials are ionized and can achieve quite uniform low temperature ion beam. Those features may enable us to realize very small emittance beams. Furthermore, a low charge state high brightness laser ion source was successfully commissioned in Brookhaven National Laboratory in 2014. Now most of all the solid based heavy ions are being provided from the laser ion source for regular operation.

  7. Laser ion source for high brightness heavy ion beam

    DOE PAGES

    Okamura, M.

    2016-09-01

    A laser ion source is known as a high current high charge state heavy ion source. But, we place great emphasis on the capability to realize a high brightness ion source. A laser ion source has a pinpoint small volume where materials are ionized and can achieve quite uniform low temperature ion beam. Those features may enable us to realize very small emittance beams. Furthermore, a low charge state high brightness laser ion source was successfully commissioned in Brookhaven National Laboratory in 2014. Now most of all the solid based heavy ions are being provided from the laser ion sourcemore » for regular operation.« less

  8. A bright PPKTP waveguide source of polarization entangled photons

    SciTech Connect

    Fanto, Michael; Tison, Christoper C.; Holwand, Gregory A; Preble, Dr. Stefan F; Alsing, Paul; Smith IV, Amos M

    2015-01-01

    The need for bright efficient sources of entangled photons has been a subject of tremendous research over the last decade. Researchers have been working to increase the brightness and purity to help overcome the spontaneous nature of the sources. Periodic poling has been implemented to allow for the use of crystals that would not normally satisfy the phase matching conditions. Utilizing periodic poling and single mode waveguide confinement of the pump field has yielded extremely large effective nonlinearities in sources easily producing millions of photon pairs. Here we will demonstrate these large nonlinearity effects in a periodically poled potassium titanyl phosphate (PPKTP) waveguide as well as characterizing the source purity.

  9. Bright solitons in non-equilibrium coherent quantum matter

    PubMed Central

    Pinsker, F.; Flayac, H.

    2016-01-01

    We theoretically demonstrate a mechanism for bright soliton generation in spinor non-equilibrium Bose–Einstein condensates made of atoms or quasi-particles such as polaritons in semiconductor microcavities. We give analytical expressions for bright (half) solitons as minimizing functions of a generalized non-conservative Lagrangian elucidating the unique features of inter and intra-competition in non-equilibrium systems. The analytical results are supported by a detailed numerical analysis that further shows the rich soliton dynamics inferred by their instability and mutual cross-interactions. PMID:26997892

  10. Histogram Equalization with Variable Enhancement Degree for Preserving Mean Brightness

    NASA Astrophysics Data System (ADS)

    Kawakami, Takashi; Murahira, Kota; Taguchi, Akira

    The histogram equalization (HE) is one of the common methods used for improving contrast in digital images. However, this technique causes a fluctuation of mean brightness. The fluctuation leads to the flicker for video signal. In order to preserve the mean brightness, the dynamic histogram equalization (DHE) is proposed. In this letter, we propose a novel DHE which is called the DHE with variable enhancement degree (DHEwVED). This method can change from DHE to HE by turning one parameter. We also show the effectiveness of the proposed method.

  11. A Complete Sample of Long Bright Swift GRBs

    NASA Astrophysics Data System (ADS)

    Tagliaferri, G.; Salvaterra, R.; Campana, S.; Covino, S.; D'Avanzo, P.; Fugazza, D.; Ghirlanda, G.; Ghisellini, G.; Melandri, A.; Sbarufatti, B.; Vergani, S.; Nava, L.

    2013-07-01

    Starting from the Swift sample we defined a complete sub-sample of 58 bright long Gamma Ray Bursts (GRB), 52 of them (90%) with a redshift determination, in order to characterize their properties. This complete sample of bright long- GRBs allowed us to investigate their evolution with cosmic time and properties. We focused in particular on the GRB luminosity function, on the spectral-energy correlations of their prompt emission, on the nature of dark bursts and on possible correlations between the prompt and the X-ray afterglow properties.

  12. Erratum - the Lowest Surface Brightness Disc Galaxy Known

    NASA Astrophysics Data System (ADS)

    Davies, J. I.; Phillipps, S.; Disney, M. J.

    1988-11-01

    The paper "The lowest surface brightness disc galaxy known' by J.I. Davies, S. Phillipps and M.J. Disney was published in Mon. Not. R. astr. Soc. (1988), 231, 69p. The declination of the object given in section 2 of the paper is incorrect and should be changed to +19^deg^48'23". Thus the object cannot be identified with GP 1444 as in the original paper. To minimize confusion we propose to refer to the low surface brightness galaxy as GP 1444A.

  13. Laser ion source for high brightness heavy ion beam

    NASA Astrophysics Data System (ADS)

    Okamura, M.

    2016-09-01

    A laser ion source is known as a high current high charge state heavy ion source. However we place great emphasis on the capability to realize a high brightness ion source. A laser ion source has a pinpoint small volume where materials are ionized and can achieve quite uniform low temperature ion beam. Those features may enable us to realize very small emittance beams. In 2014, a low charge state high brightness laser ion source was successfully commissioned in Brookhaven National Laboratory. Now most of all the solid based heavy ions are being provided from the laser ion source for regular operation.

  14. ESA innovation rescues Ultraviolet Observatory

    NASA Astrophysics Data System (ADS)

    1995-10-01

    Astrophysicist Freeman J. Dyson from the Institute for Advanced Studies in Princeton characterizes IUE as "A little half-meter mirror sitting in the sky, unnoticed by the public, pouring out results". By use of the IUE satellite, astronomers obtain access to the ultraviolet radiation of celestial bodies in unique ways not available by any other means, neither from the ground nor by any other spacecraft currently in orbit. IUE serves a wide community of astronomers all over Europe, the United States and many other parts of the world. It allows the acquisition of critical data for fundamental studies of comets and their evaporation when they approach the Sun, of the mechanisms driving the stellar winds which make many stars lose a significant fraction of their mass (before they die slowly as White Dwarfs or in sudden Supernova explosions), as well as in the search to understand the ways in which black holes possibly power the violent nuclei of Active galaxies. One year ago the project was threatened with termination and serious concern was expressed by astronomers about the potential loss of IUE's capabilities, as a result of NASA not continuing to operate the spacecraft. Under the leadership of ESA, the three Agencies involved in the operations of IUE (ESA, NASA and the United Kingdom's Particle Physics and Astronomy Research Council, PPARC), reviewed the operations agreements of the Project. A minor investment allowing the implementation of modern management and engineering techniques as well as a complete revision of the communication infrastructure of the project and continuous improvements in efficiency in the ESA management, also taking advantage of today's technologies, both in computing and communications, have made it possible to continue IUE operations within the financial means available, with ESA taking up most of NASA's share in the operations. According to Dr. Willem Wamsteker, ESA's Dutch IUE Project Scientist, "it was a extremely interesting

  15. The Ultraviolet Spectrograph on the Europa Mission (Europa-UVS)

    NASA Astrophysics Data System (ADS)

    Retherford, K. D.; Gladstone, R.; Greathouse, T. K.; Steffl, A.; Davis, M. W.; Feldman, P. D.; McGrath, M. A.; Roth, L.; Saur, J.; Spencer, J. R.; Stern, S. A.; Pope, S.; Freeman, M. A.; Persyn, S. C.; Araujo, M. F.; Cortinas, S. C.; Monreal, R. M.; Persson, K. B.; Trantham, B. J.; Versteeg, M. H.; Walther, B. C.

    2015-12-01

    NASA's Europa multi-flyby mission is designed to provide a diversity of measurements suited to enrich our understanding of the potential habitability of this intriguing ocean world. The Europa mission's Ultraviolet Spectrograph, Europa-UVS, is the sixth in a series of successful ultraviolet imaging spectrographs (Rosetta-Alice, New Horizons Pluto-Alice, LRO-LAMP) and, like JUICE-UVS (now under Phase B development), is largely based on the most recent of these to fly, Juno-UVS. Europa-UVS observes photons in the 55-210 nm wavelength range, at moderate spectral and spatial resolution along a 7.5° slit. Three distinct apertures send light to the off-axis telescope mirror feeding the long-slit spectrograph: i) a main entrance airglow port is used for most observations (e.g., airglow, aurora, surface mapping, and stellar occultations); ii) a high-spatial-resolution port consists of a small hole in an additional aperture door, and is used for detailed observations of bright targets; and iii) a separate solar port allows for solar occultations, viewing at a 60° offset from the nominal payload boresight. Photon event time-tagging (pixel list mode) and programmable spectral imaging (histogram mode) allow for observational flexibility and optimal science data management. As on Juno-UVS, the effects of penetrating electron radiation on electronic parts and data quality are mitigated through contiguous shielding, filtering of pulse height amplitudes, management of high-voltage settings, and careful use of radiation-hard parts. The science goals of Europa-UVS are to: 1) Determine the composition & chemistry, source & sinks, and structure & variability of Europa's atmosphere, from equator to pole; 2) Search for and characterize active plumes in terms of global distribution, structure, composition, and variability; 3) Explore the surface composition & microphysics and their relation to endogenic & exogenic processes; and 4) Investigate how energy and mass flow in the Europa

  16. The Ultraviolet Spectrograph (UVS) on ESA’s JUICE Mission

    NASA Astrophysics Data System (ADS)

    Gladstone, Randy; Retherford, K.; Steffl, A.; Eterno, J.; Davis, M.; Versteeg, M.; Greathouse, T.; Araujo, M.; Walther, B.; Persson, K.; Persyn, S.; Dirks, G.; McGrath, M.; Feldman, P.; Bagenal, F.; Spencer, J.; Schindhelm, E.; Fletcher, L.

    2013-10-01

    The Jupiter Icy Moons Explorer (JUICE) was selected in May 2012 as the first L-class mission of ESA’s Cosmic Vision Program. JUICE will launch in 2022 on a 7.6-year journey to the Jovian system, including a Venus and multiple Earth gravity assists, before entering Jupiter orbit in January 2030. JUICE will study the entire Jovian system for 3.5 years, concentrating on Europa, Ganymede, and Callisto, with the last 10 months spent in Ganymede orbit. The Ultraviolet Spectrograph (UVS) on JUICE was jointly selected by NASA and ESA as part of its ~130 kg payload of 11 scientific instruments. UVS is the fifth in a series of successful ultraviolet imaging spectrographs (Rosetta-Alice, New Horizons Pluto-Alice, LRO-LAMP) and is largely based on the most recent of these, Juno-UVS. It observes photons in the 55-210 nm wavelength range, at moderate spectral and spatial resolution along a 7.5-degree slit. A main entrance “airglow port” (AP) is used for most observations (e.g., airglow, aurora, surface mapping, and stellar occultations), while a separate “solar port” (SP) allows for solar occultations. Another aperture door, with a small hole through the centre, is used as a “high-spatial-resolution port” (HP) for detailed observations of bright targets. Time-tagging (pixel list mode) and programmable spectral imaging (histogram mode) allow for observational flexibility and optimal data management. As on Juno-UVS, the effects of penetrating electron radiation on electronic parts and data quality are substantially mitigated through contiguous shielding, filtering of pulse height amplitudes, management of high voltage settings, and careful use of radiation-hard, flight-tested parts. The science goals of UVS are to: 1) explore the atmospheres, plasma interactions, and surfaces of the Galilean satellites; 2) determine the dynamics, chemistry, and vertical structure of Jupiter’s upper atmosphere from equator to pole; and 3) investigate the Jupiter-Io connection by

  17. Ultraviolet Signposts of Resonant Dynamics in the Starburst-ringed SAB Galaxy M94 (NGC 4736)

    NASA Astrophysics Data System (ADS)

    Waller, William H.; Fanelli, Michael N.; Keel, William C.; Bohlin, Ralph; Collins, Nicholas R.; Madore, Barry F.; Marcum, Pamela M.; Neff, Susan G.; O'Connell, Robert W.; Offenberg, Joel D.; Roberts, Morton S.; Smith, Andrew M.; Stecher, Theodore P.

    2001-03-01

    The dynamic orchestration of star-birth activity in the starburst-ringed galaxy M94 (NGC 4736) is investigated using images from the Ultraviolet Imaging Telescope (UIT; far-ultraviolet [FUV] band), Hubble Space Telescope (HST; near-ultraviolet [NUV] band), Kitt Peak 0.9 m telescope (Hα, R, and I bands), and Palomar 5 m telescope (B band), along with spectra from the International Ultraviolet Explorer (IUE) and the Lick 1 m telescope. The wide-field UIT image shows FUV emission from (1) an elongated nucleus, (2) a diffuse inner disk, where Hα is observed in absorption, (3) a bright inner ring of H II regions at the perimeter of the inner disk (R=48"=1.1 kpc), and (4) two 500 pc size knots of hot stars exterior to the ring on diametrically opposite sides of the nucleus (R=130"=2.9 kpc). The HST Faint Object Camera image resolves the NUV emission from the nuclear region into a bright core and a faint 20" long ``minibar'' at a position angle of 30°. Optical and IUE spectroscopy of the nucleus and diffuse inner disk indicates a ~107-108 yr old stellar population from low-level star-birth activity blended with some LINER activity. Analysis of the Hα-, FUV-, NUV-, B-, R-, and I-band emissions, along with other observed tracers of stars and gas in M94, indicates that most of the star formation is being orchestrated via ring-bar dynamics, involving the nuclear minibar, inner ring, oval disk, and outer ring. The inner starburst ring and bisymmetric knots at intermediate radius, in particular, argue for bar-mediated resonances as the primary drivers of evolution in M94 at the present epoch. Similar processes may be governing the evolution of the ``core-dominated'' galaxies that have been observed at high redshift. The gravitationally lensed ``Pretzel Galaxy'' (0024+1654) at a redshift of ~1.5 provides an important precedent in this regard.

  18. The ultraviolet attenuation law in backlit spiral galaxies

    SciTech Connect

    Keel, William C.; Manning, Anna M.; Holwerda, Benne W.; Lintott, Chris J.; Schawinski, Kevin E-mail: ammanning@bama.ua.edu E-mail: Twitter@BenneHolwerda E-mail: Twitter@chrislintott E-mail: Twitter@kevinschawinski

    2014-02-01

    The effective extinction law (attenuation behavior) in galaxies in the emitted ultraviolet (UV) regime is well known only for actively star-forming objects and combines effects of the grain properties, fine structure in the dust distribution, and relative distributions of stars and dust. We use Galaxy Evolution Explorer, XMM Optical Monitor, and Hubble Space Telescope (HST) data to explore the UV attenuation in the outer parts of spiral disks which are backlit by other UV-bright galaxies, starting with the candidate list of pairs provided by Galaxy Zoo participants. New optical images help to constrain the geometry and structure of the target galaxies. Our analysis incorporates galaxy symmetry, using non-overlapping regions of each galaxy to derive error estimates on the attenuation measurements. The entire sample has an attenuation law across the optical and UV that is close to the Calzetti et al. form; the UV slope for the overall sample is substantially shallower than found by Wild et al., which is a reasonable match to the more distant galaxies in our sample but not to the weighted combination including NGC 2207. The nearby, bright spiral NGC 2207 alone gives an accuracy almost equal to the rest of our sample, and its outer arms have a very low level of foreground starlight. Thus, this widespread, fairly 'gray' law can be produced from the distribution of dust alone, without a necessary contribution from differential escape of stars from dense clouds. Our results indicate that the extrapolation needed to compare attenuation between backlit galaxies at moderate redshifts from HST data, and local systems from Sloan Digital Sky Survey and similar data, is mild enough to allow the use of galaxy overlaps to trace the cosmic history of dust in galaxies. For NGC 2207, HST data in the near-UV F336W band show that the covering factor of clouds with small optical attenuation becomes a dominant factor farther into the UV, which opens the possibility that widespread

  19. Extremely Low Passive Microwave Brightness Temperatures Due to Thunderstorms

    NASA Technical Reports Server (NTRS)

    Cecil, Daniel J.

    2015-01-01

    Extreme events by their nature fall outside the bounds of routine experience. With imperfect or ambiguous measuring systems, it is appropriate to question whether an unusual measurement represents an extreme event or is the result of instrument errors or other sources of noise. About three weeks after the Tropical Rainfall Measuring Mission (TRMM) satellite began collecting data in Dec 1997, a thunderstorm was observed over northern Argentina with 85 GHz brightness temperatures below 50 K and 37 GHz brightness temperatures below 70 K (Zipser et al. 2006). These values are well below what had previously been observed from satellite sensors with lower resolution. The 37 GHz brightness temperatures are also well below those measured by TRMM for any other storm in the subsequent 16 years. Without corroborating evidence, it would be natural to suspect a problem with the instrument, or perhaps an irregularity with the platform during the first weeks of the satellite mission. Automated quality control flags or other procedures in retrieval algorithms could treat these measurements as errors, because they fall outside the expected bounds. But the TRMM satellite also carries a radar and a lightning sensor, both confirming the presence of an intense thunderstorm. The radar recorded 40+ dBZ reflectivity up to about 19 km altitude. More than 200 lightning flashes per minute were recorded. That same storm's 19 GHz brightness temperatures below 150 K would normally be interpreted as the result of a low-emissivity water surface (e.g., a lake, or flood waters) if not for the simultaneous measurements of such intense convection. This paper will examine records from TRMM and related satellite sensors including SSMI, AMSR-E, and the new GMI to find the strongest signatures resulting from thunderstorms, and distinguishing those from sources of noise. The lowest brightness temperatures resulting from thunderstorms as seen by TRMM have been in Argentina in November and December. For

  20. Increasing the response of PIN photodiodes to the ultraviolet

    NASA Technical Reports Server (NTRS)

    Burrous, C. N.; Whiting, E. E.

    1972-01-01

    Solid state device uses sapphire windows and avoids coatings which absorb ultraviolet radiation and ultimately alter detector geometry. Ultimate solution for ultraviolet response is geometry with maximum peripheral area and horizontal field structure to draw out photon induced current carriers.

  1. View of Gemini 11 experiment S-13 Ultraviolet Astronomical Camera

    NASA Technical Reports Server (NTRS)

    1966-01-01

    View of Gemini 11 experiment S-13 Ultraviolet Astronomical Camera before flight. Its object was to obtain data on ultraviolet radiation of hot stars and to develop and evaluate basic techniques for photography of celestial objects from manned spacecraft.

  2. 21 CFR 880.6500 - Medical ultraviolet air purifier.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Miscellaneous Devices § 880.6500 Medical ultraviolet air purifier. (a) Identification. A medical ultraviolet air purifier is a device intended for medical purposes that is used to destroy bacteria in the air by...

  3. 21 CFR 880.6500 - Medical ultraviolet air purifier.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Miscellaneous Devices § 880.6500 Medical ultraviolet air purifier. (a) Identification. A medical ultraviolet air purifier is a device intended for medical purposes that is used to destroy bacteria in the air by...

  4. 21 CFR 880.6500 - Medical ultraviolet air purifier.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Miscellaneous Devices § 880.6500 Medical ultraviolet air purifier. (a) Identification. A medical ultraviolet air purifier is a device intended for medical purposes that is used to destroy bacteria in the air by...

  5. 21 CFR 880.6500 - Medical ultraviolet air purifier.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Miscellaneous Devices § 880.6500 Medical ultraviolet air purifier. (a) Identification. A medical ultraviolet air purifier is a device intended for medical purposes that is used to destroy bacteria in the air by...

  6. The Lunar Phase Curve in the Near Ultraviolet

    NASA Technical Reports Server (NTRS)

    Hendrix, A. R.

    2002-01-01

    We present the ultraviolet phase curve of the Moon at two wavelengths, 215 and 237 nm, as measured by the Ultraviolet Spectrometer on board the Student Nitric Oxide Explorer. Additional information is contained in the original extended abstract.

  7. A database of synthetic photometry in the GALEX ultraviolet bands for the stellar sources observed with the International Ultraviolet Explorer

    NASA Astrophysics Data System (ADS)

    Beitia-Antero, Leire; Gómez de Castro, Ana I.

    2016-11-01

    Context. The Galaxy Evolution Explorer (GALEX) has produced the largest photometric catalogue of ultraviolet (UV) sources. As such, it has defined the new standard bands for UV photometry: the near UV band (NUV) and the far UV band (FUV). However, due to brightness limits, the GALEX mission has avoided the Galactic plane which is crucial for astrophysical research and future space missions. Aims: The International Ultraviolet Explorer (IUE) satellite obtained 63 755 spectra in the low dispersion mode (λ/δλ 300) during its 18-year lifetime. We have derived the photometry in the GALEX bands for the stellar sources in the IUE Archive to extend the GALEX database with observations including the Galactic plane. Methods: Good quality spectra have been selected for the IUE classes of stellar sources. The GALEX FUV and NUV magnitudes have been computed using the GALEX transmission curves, as well as the conversion equations between flux and magnitudes provided by the mission. Results: Consistency between GALEX and IUE synthetic photometries has been tested using white dwarfs (WD) contained in both samples. The non-linear response performance of GALEX inferred from this data agrees with the results from GALEX calibration. The photometric database is made available to the community through the services of the Centre de Données Stellaires at Strasbourg (CDS). The catalogue contains FUV magnitudes for 1628 sources, ranging from FUV = 1.81 to FUV = 18.65 mag. In the NUV band, the catalogue includes observations for 999 stars ranging from NUV = 3.34 to NUV = 17.74 mag. Conclusions: UV photometry for 1490 sources not included in the GALEX AIS GR5 catalogue is provided; most of them are hot (O-A spectral type) stars. The sources in the catalogue are distributed over the full sky, including the Galactic plane. Full Tables A.1 and B.1 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc

  8. Biological effects of ultraviolet irradiation on bees

    SciTech Connect

    Es`kov, E.K.

    1995-09-01

    The influence of natural solar and artificial ultraviolet irradiation on developing bees was studied. Lethal exposures to irradiation at different stages of development were determined. The influence of irradiation on the variability of the morphometric features of bees was revealed. 5 refs., 1 fig.

  9. High-intensity source of extreme ultraviolet

    NASA Technical Reports Server (NTRS)

    Paresce, E.; Kumar, S.; Bowyer, S.

    1972-01-01

    High intensity ultraviolet radiation source was developed which is suitable for emission below 500 A. Source, useful for 100 to 1000 A range, is simple and inexpensive to construct, easy to operate, and very stable. Because of sufficiently intense output spectrum, source can be used with monochromator at wavelengths as low as 160 A.

  10. Comet Kohoutek - Ultraviolet images and spectrograms

    NASA Technical Reports Server (NTRS)

    Opal, C. B.; Carruthers, G. R.; Prinz, D. K.; Meier, R. R.

    1974-01-01

    Emissions of atomic oxygen (1304 A), atomic carbon (1657 A), and atomic hydrogen (1216 A) from Comet Kohoutek were observed with ultraviolet cameras carried on a sounding rocket on Jan. 8, 1974. Analysis of the Lyman alpha halo at 1216 A gave an atomic hydrogen production rate of 4.5 x 10 to the 29th atoms per second.

  11. Combined ultraviolet studies of astronomical sources

    NASA Technical Reports Server (NTRS)

    Baliunas, S. L.; Dupree, A. K.; Elvis, M.; Huchra, J. P.; Kenyon, S.; Raymond, J. C.

    1986-01-01

    Topics addressed include: Cygnus Loop; P Cygni profiles in dwarf novae; YY Gem; nova shells; HZ Herculis; activity cycles in cluster giants; Alpha Ori; metal deficient giant stars; ultraviolet spectra of symbiotic stars detected by the Very Large Array; time variability in symbiotic stars; blue galaxies; and quasistellar objects with X-ray spectra.

  12. Microwave-driven ultraviolet light sources

    DOEpatents

    Manos, Dennis M.; Diggs, Jessie; Ametepe, Joseph D.

    2002-01-29

    A microwave-driven ultraviolet (UV) light source is provided. The light source comprises an over-moded microwave cavity having at least one discharge bulb disposed within the microwave cavity. At least one magnetron probe is coupled directly to the microwave cavity.

  13. Ultraviolet Emission from Rocket Motor Plumes

    DTIC Science & Technology

    1994-06-01

    who..t’ "-. bsorption band is centred near 255 nm Ozone concentrations vary with location and show regular htne-,oral variations over diurnal and...34Flame Spectroscopy " (John Wiley and Sons, New York, 1965) 25. Yates, G. J., Wilke, M.. King. N and Lumpkn. A. "Ultraviolet imaging of hydrogen

  14. Photodiode-Based, Passive Ultraviolet Dosimeters

    NASA Technical Reports Server (NTRS)

    Vaughn, Jason A.; Gray, Perry

    2004-01-01

    Simple, passive instruments have been developed for measuring the exposure of material specimens to vacuum ultraviolet (VUV) radiation from the Sun. Each instrument contains a silicon photodiode and a coulometer. The photocharge generated in the photodiode is stored in the coulometer. The accumulated electric charge measured by use of the coulometer is assumed to be proportional to the cumulative dose of VUV radiation expressed in such convenient units as equivalent Sun hours (ESH) [defined as the number of hours of exposure to sunlight at normal incidence]. Intended originally for use aboard spacecraft, these instruments could also be adapted to such terrestrial uses as monitoring the curing of ultraviolet-curable epoxies. Each instrument includes a photodiode and a coulometer assembly mounted on an interface plate (see figure). The photodiode assembly includes an aluminum housing that holds the photodiode, a poly(tetrafluoroehylene) cosine receptor, and a narrow-band optical filter. The cosine receptor ensures that the angular response of the instrument approximates the ideal angular response (proportional to the cosine of the angle of incidence). The filter is chosen to pass the ultraviolet wavelength of interest in a specific experiment. The photodiode is electrically connected to the coulometer. The factor of proportionality between the charge stored in the coulometer and ultraviolet dosage (in units of ESH) is established, prior to use, in calibration experiments that involve the use of lamps and current sources traceable to the National Institute of Standards and Technology.

  15. Ionospheric Profiles from Ultraviolet Remote Sensing

    DTIC Science & Technology

    1997-09-30

    The long-term goal of this project is to obtain ionospheric profiles from ultraviolet remote sensing of the ionosphere from orbiting space platforms... Remote sensing of the nighttime ionosphere is a more straightforward process because of the absence of the complications brought about by daytime

  16. Comet kohoutek: ultraviolet images and spectrograms.

    PubMed

    Opal, C B; Carruthers, G R; Prinz, D K; Meier, R R

    1974-08-23

    Emissions of atomic oxygen (1304 angstroms), atomic carbon (1657 angstroms), and atomic hydrogen (1216 angstroms) from Comet Kohoutek were observed with ultraviolet cameras carried on a sounding rocket on 8 January 1974. Analysis of the Lyman alpha halo at 1216 angstroms gave an atomic hydrogen production rate of 4.5 x 10(29) atoms per second.

  17. Ultraviolet Light: Some Considerations for Vision Stimulation.

    ERIC Educational Resources Information Center

    Knowlton, Marie

    1986-01-01

    The article examines evidence of visual impairment caused by excessive amounts of ultraviolet (UV) light. Among considerations when using a source of UV light for vision stimulation are the position of the child and teacher, use of window glass filters or protective glasses, and careful recordkeeping of all UV stimulation. (Author/JW)[

  18. Ultraviolet Viewing with a Television Camera.

    ERIC Educational Resources Information Center

    Eisner, Thomas; And Others

    1988-01-01

    Reports on a portable video color camera that is fully suited for seeing ultraviolet images and offers some expanded viewing possibilities. Discusses the basic technique, specialized viewing, and the instructional value of this system of viewing reflectance patterns of flowers and insects that are invisible to the unaided eye. (CW)

  19. Apollo 17 ultraviolet spectrometer experiment (S-169)

    NASA Technical Reports Server (NTRS)

    Fastie, W. G.

    1974-01-01

    The scientific objectives of the ultraviolet spectrometer experiment are discussed, along with design and operational details, instrument preparation and performance, and scientific results. Information gained from the experiment is given concerning the lunar atmosphere and albedo, zodiacal light, astronomical observations, spacecraft environment, and the distribution of atomic hydrogen in the solar system and in the earth's atmosphere.

  20. Ultraviolet Radiation: Human Exposure and Health Risks.

    ERIC Educational Resources Information Center

    Tenkate, Thomas D.

    1998-01-01

    Provides an overview of human exposure to ultraviolet radiation and associated health effects as well as risk estimates for acute and chronic conditions resulting from such exposure. Demonstrates substantial reductions in health risk that can be achieved through preventive actions. Also includes a risk assessment model for skin cancer. Contains 36…

  1. Solar ultraviolet radiation in a changing climate

    EPA Science Inventory

    The projected large increases in damaging ultraviolet radiation as a result of global emissions of ozone-depleting substances have been forestalled by the success of the Montreal Protocol. New challenges are now arising in relation to climate change. We highlight the complex inte...

  2. Enhancement of comedogenic substances by ultraviolet radiation.

    PubMed

    Mills, O H; Porte, M; Kligman, A M

    1978-02-01

    Ultraviolet radiation enhanced the capacity of human sebum, sulphur, cocoa butter, squalene, and coal tar to produce comedones in the external ear canals of rabbits. An enhancement of the comedogenicity of coal tar and squalene was similarly demonstrated in man. We conjecture that in occasional patients sunbathing may aggravate acne by augmenting the comedogenicity of sebum.

  3. Ultraviolet imaging and spectroscopy of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Gerard, Jean-Claude

    1994-01-01

    The main scientific results of the participation of the Institute of Astrophysics (Belgium) in the NASA's Pioneer Venus mission are reported on. The data were obtained with the Pioneer Orbiter's Ultraviolet Spectrometer (POUVS). The instrument provided a morphological study of the nitric oxide ultraviolet night glow. Information concerning the altitude of the airglow emitting layer was also collected and used to constrain models of turbulent transport on the night side of the planet. Models of the odd nitrogen thermospheric chemistry and transport were developed to analyze the observations and derive the properties of the global circulation of Venus' upper atmosphere. Images of the Jovian ultraviolet aurora were obtained. The morphology and the time variations of the HI Ly-alpha and H2 Lyman and Werner bands were acquired at different longitudes. The observed distribution was compared with the results of the spectrometric observations made with the Voyager and the International Ultraviolet Explorer missions. Images concerning the Io surface albedo and Saturn's disk and ring's reflectivity were also obtained.

  4. Ultraviolet Stellar Astronomy - Skylab Experiment S019

    NASA Technical Reports Server (NTRS)

    1970-01-01

    This chart provides information about Skylab's Ultraviolet (UV) Stellar Astronomy experiment (SO19), a scientific airlock-based facility/experiment that would study UV spectra of early-type stars and galaxies. The Marshall Space Flight Center had program management responsibility for the development of Skylab hardware and experiments.

  5. ULTRAVIOLET DISINFECTION STUDIES WITH CCL LISTED MICROORGANISMS

    EPA Science Inventory

    Resistance to ultraviolet (UV) disinfection is an essential aspect regarding all microbial groups listed on the CCL. The U.S. drinking water industry is interested in including UV light treatment as an amendment to conventional treatment for disinfecting water supplies. UV disi...

  6. Some Thoughts on Teaching about Ultraviolet Radiation

    ERIC Educational Resources Information Center

    Thumm, Walter

    1975-01-01

    Describes the major obstacles in the study of ultraviolet radiation (UV). Presents the beneficial aspects of UV such as vitamin O production, sterilization, clinical treatment of diseases and wounds, and the marking of patients for radiotherapy. Warns of the dangers of UV exposure such as skin cancer and early aging. (GS)

  7. The difficulty of ultraviolet emssion from supernovae

    NASA Technical Reports Server (NTRS)

    Colgate, S. A.

    1971-01-01

    There are certain conceptual difficulties in the theory of the generation of ultraviolet radiation which is presumed for the creation of the optical fluorescence mechanism of supernova light emission and ionization of a nebula as large as the Gum nebula. Requirements concerning the energy distribution of the ultraviolet photons are: 1) The energy of the greater part of the photons must be sufficient to cause both helium fluorescence and hydrogen ionization. 2) If the photons are emitted in an approximate black body spectrum, the fraction of energy emitted in the optical must be no more than what is already observed. Ultraviolet black body emission depends primarily on the energy source. The probability that the wide mixture of elements present in the interstellar medium and supernova ejecta results in an emission localized in a limited region with less than 0.001 emission in the visible, for either ionization or fluorescence ultraviolet, is remote. Therefore transparent emission must be excluded as unlikely, and black body or at least quasi-black-body emission is more probable.

  8. Brightness Rural Electrification Program: Renewable Energy in China

    SciTech Connect

    Not Available

    2004-04-01

    Fact sheet describes China's New Brightness Rural Electrification Program to provide electricity for 23 million people in remote areas of China using renewable energy such as wind energy and solar power (photovoltaics). Targets, results, and progress are described. Regions targeted are Inner Mongolia, Tibet, and Gansu.

  9. RESPONSES OF BRIGHT, NORMAL, AND RETARDED CHILDREN TO LEARNING TASKS.

    ERIC Educational Resources Information Center

    CARRIER, NEIL A.; AND OTHERS

    THE RELATIONSHIPS AMONG THE VARIABLES OF INTELLIGENCE, LEARNING TASK PERFORMANCE, EMOTIONAL TENSION, AND TASK MOTIVATION WERE STUDIED. ABOUT 120 BRIGHT, NORMAL, AND RETARDED CHILDREN PERFORMED SIX TRIALS OF NUMBER LEARNING, CONCEPT FORMATION, PROBLEM SOLVING, PERCEPTUAL-MOTOR COORDINATION, AND VERBAL LEARNING TASKS. DURING THE LEARNING SESSIONS,…

  10. Proposal for a High-Brightness Pulsed Electron Source

    SciTech Connect

    Zolotorev, M.; Commins, E.D.; Heifets, S.; Sannibale, F.; /LBL, Berkeley /UC, Berkeley /SLAC

    2006-10-16

    We propose a novel scheme for a high-brightness pulsed electron source, which has the potential for many useful applications in electron microscopy, inverse photo-emission, low energy electron scattering experiments, and electron holography. A description of the proposed scheme is presented.

  11. Bright Sneezes and Dark Coughs, Loud Sunlight and Soft Moonlight.

    ERIC Educational Resources Information Center

    Marks, Lawrence E.

    1982-01-01

    In a series of four experiments, subjects used scales of loudness, pitch, and brightness to evaluate the meanings of a variety of synesthetic metaphors--expressions in which words or phrases describing experiences proper to one sense modality transfer their meaning to another modality. (Author/PN)

  12. Dynamical behaviour of photospheric bright points during merging

    NASA Astrophysics Data System (ADS)

    Criscuoli, S.; Stangalini, M.; Ermolli, I.; Zuccarello, F.; Cristaldi, A.; Falco, M.; Guglielmino, S.; Giorgi, F.

    2014-12-01

    We investigate the merging of bright points observed at high spatial and temporal resolution with CRISP/SST in a quiet region region. We analyze the MHD perturbations excited during the merging, their role in the energy budget of the magnetic structure and the potential role that they can play in heating the upper layers of the Sun's atmosphere.

  13. The "Brightness Rules" Alternative Conception for Light Bulb Circuits

    ERIC Educational Resources Information Center

    Bryan, Joel A.; Stuessy, Carol

    2006-01-01

    An alternative conception for the observed differences in light bulb brightness was revealed during an unguided inquiry investigation in which prospective elementary teachers placed identical bulbs in series, parallel, and combination direct current circuits. Classroom observations, document analyses, and video and audio transcriptions led to the…

  14. Apparatus Would Position Bright Spot On Projection Screen

    NASA Technical Reports Server (NTRS)

    Rayman, Marc D.

    1996-01-01

    Proposed apparatus aims beam of visible light at wavelength lambda(2) to create bright spot at desired position in image on projection screen. Intended to replace handheld laser and flashlight pointers lecturers sometimes use to indicate features in projected images. Beam of light cannot be inadvertently aimed toward audience.

  15. Scattering models for the solar infrared F-corona brightness

    NASA Astrophysics Data System (ADS)

    Davidson, W. C.; MacQueen, R. M.; Mann, I.

    1995-02-01

    Model calculations are made of the infrared brightness in the solar F-corona motivated by recent infrared solar eclipse observations. Two different approaches are employed to describe the scattering properties of interplanetary dust : Mie scattering theory and diffraction theory, with and without an isotropic scattering term. In addition. two different particle size distributions are used in the calculations and the resultant line of sight brightness is compared with observational data of the solar F-corona between 3 and 8 solar radii ( R) in the ecliptic plane. It is found that the use of diffraction theory without an isotropic scattering contribution gives a very poor match with the observations, for both assumed particle size distributions. However, both the diffraction theory including isotropic scattering and the Mie scattering theory agree reasonably with the observed brightness, and especially its radial slope within the corona. for the model size distribution which is dominated by large particles. Only Mie theory may be employed in describing the second model size distribution because diffraction theory poorly describes the scattering due to the small particles which dominate this size distribution. It is concluded that the derivation of particle size distributions from the F-coronal brightness is still ambiguous and a further analysis needs either improved observations, or the application of further reasonable physical assumptions.

  16. Variations in the Fe mineralogy of bright Martian soil

    NASA Technical Reports Server (NTRS)

    Murchie, Scott; Mustard, John; Erard, Stephane; Geissler, Paul; Singer, Robert

    1993-01-01

    Bright regions on Mars are interpreted as 'soil' derived by chemical alteration of crustal rocks, whose main pigmentary component is ferric oxide or oxyhydroxide. The mineralogy and mineralogic variability of ferric iron are important evidence for the evolution of Martian soil: mineralogy of ferric phases is sensitive to chemical conditions in their genetic environments, and the spatial distributions of different ferric phases would record a history of both chemical environments and physical mixing. Reflectance spectroscopic studies provide several types of evidence that discriminate possible pigmentary phases, including the position of a crystal field absorption near 0.9 microns and position and strengths of absorptions in the UV-visible wavelength region. Recent telescopic spectra and laboratory measurements of Mars soil analogs suggest that spectral features of bright soil can be explained based on a single pigmentary phase, hematite (alpha-Fe2O3), occurring in both 'nanophase' and more crystalline forms. Here we report on a systematic investigation of Martian bright regions using ISM imaging spectrometer data, in which we examined spatial variations in the position and shape of the approximately 0.9 microns absorption. We found both local and regional heterogeneities that indicate differences in Fe mineralogy. These results demonstrate that bright soils do not represent a single lithology that has been homogenized by eolian mixing, and suggest that weathering of soils in different geologic settings has followed different physical and chemical pathways.

  17. High Precision Photometry of Bright Transiting Exoplanet Hosts

    NASA Astrophysics Data System (ADS)

    Wilson, Maurice; Eastman, Jason; Johnson, John A.

    2016-01-01

    Within the past two decades, the successful search for exoplanets and the characterization of their physical properties have shown the immense progress that has been made towards finding planets with characteristics similar to Earth. For most exoplanets with a radius about the size of Earth, evaluating their physical properties, such as the mass, radius and equilibrium temperature, cannot be determined with satisfactory precision. The MINiature Exoplanet Radial Velocity Array (MINERVA) was recently built to obtain spectroscopic and photometric measurements to find, confirm, and characterize Earth-like exoplanets. MINERVA's spectroscopic survey targets the brightest, nearby stars which are well-suited to the array's capabilities, while its primary photometric goal is to search for transits around these bright targets. Typically, it is difficult to find satisfactory comparison stars within a telescope's field of view when the primary target is very bright. This issue is resolved by using one of MINERVA's telescopes to observe the primary bright star while the other telescopes observe a distinct field of view that contains satisfactory bright comparison stars. We describe the code used to identify nearby comparison stars, schedule the four telescopes, produce differential photometry from multiple telescopes, and show the first results from this effort.This work has been funded by the Ronald E. McNair Post-Baccalaureate Achievement Program, the ERAU Honors Program, the ERAU Undergraduate Research Spark Fund, and the Banneker Institute at the Harvard-Smithsonian Center for Astrophysics.

  18. iPTF discovery and identification of bright transients

    NASA Astrophysics Data System (ADS)

    Kupfer, Thomas; Ho, Anna; Karamehmetoglu, Emir; Petrushevska, Tanja; Adams, Scott; Neill, James D.; Walters, Richard; Cannella, Chris; Blagorodnova, Nadejda; Yan, Lin; Kulkarni, Shri

    2017-02-01

    The intermediate Palomar Transient Factory (ATel #4807) reports the discovery of the following bright transients. We report as ATel alerts all objects brighter than 19 mag. Our discoveries are reported in two filters: sdss-g and Mould-I, denoted as g, and I. Both are in the AB magnitude system.

  19. SKYMONITOR: A Global Network for Night Sky Brightness Measurements

    NASA Astrophysics Data System (ADS)

    McKenna, Dan; Davis, Donald; Boley, Paul

    2015-03-01

    We have deployed a network of autonomous photometers that continuously measures the night sky brightness in the visual region at two sky positions simultaneously, typically near the zenith and the second at an elevation angle of 20 degrees. The Photometers are calibrated as a network to better than 5.

  20. Aviation -- Where Career Opportunities are Bright, Counselor's Guide.

    ERIC Educational Resources Information Center

    Zaharevitz, Walter; Marshall, Jane N.

    This aviation occupations guide is designed for use as a unit as well as in conjunction with an aviation careers package of material that contains a film strip and recording. Chapter One contains the script of the film strip, Aviation--Where Career Opportunities are Bright, and includes all photographs used in the film strip plus numerous…