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Sample records for a1 remnant ratio

  1. Ratio of remnant to total liver volume or remnant to body weight: which one is more predictive on donor outcomes?

    PubMed Central

    Yaprak, Onur; Guler, Necdet; Altaca, Gulum; Dayangac, Murat; Demirbas, Tolga; Akyildiz, Murat; Ulusoy, Levent; Tokat, Yaman; Yuzer, Yildiray

    2012-01-01

    Backround Right lobe donations are known to expose the donors to more surgical risks than left lobe donations. In the present study, the effects of remnant volume on donor outcomes after right lobe living donor hepatectomies were investigated. Methods The data on 262 consecutive living liver donors who had undergone a right hepatectomy from January 2004 to June 2011 were retrospectively analysed. The influence of the remnant on the outcomes was investigated according to the two different definitions. These were: (i) the ratio of the remnant liver volume to total liver volume (RLV/TLV) and (ii) the remnant liver volume to donor body weight ratio (RLV/BWR). For RLV/TLV, the effects of having a percentage of 30% or below and for RLV/BWR, the effects of values lower than 0.6 on the results were investigated. Results Complication and major complication rates were 44.7% and 13.2% for donors with RLV/TLV of ≤30%, and 35.9% and 9.4% for donors with RLV/BWR of < 0.6, respectively. In donors with RLV/TLV of ≤30%, RLV/BWR being below or above 0.6 did not influence the results in terms of liver function tests, complications and hospital stay. The main impact on the outcome was posed by RLV/TLV of ≤30%. Conclusion Remnant volume in a right lobe living donor hepatectomy has adverse effects on donor outcomes when RLV/TLV is ≤30% independent from the rate of RLV/BWR with a cut-off point of 0.6. PMID:22672550

  2. Infrared Supernova Remnants and their Infrared-to-X-ray Flux Ratios

    NASA Astrophysics Data System (ADS)

    Koo, Bon-Chul; Lee, Jae-Joon; Jeong, Il-Gyo; Seok, Ji Yeon; Kim, Hyun-Jeong

    2016-04-01

    Recent high-resolution infrared space missions have revealed supernova remnants (SNRs) of diverse morphology in infrared (IR) dust emission that are often very different from their X-ray appearance. The observed range of infrared-to-X-ray (IRX) flux ratios of SNRs is also wide. For a sample of 20 Galactic SNRs, we obtain their IR and X-ray properties and investigate the physical causes for such large differences. We find that the observed IRX flux ratios ({R}{{IRX,obs}}) are related to the IRX morphology, with SNRs with the largest {R}{{IRX,obs}} showing anticorrelated IRX morphology. By analyzing the relation of {R}{{IRX,obs}} to X-ray and IR parameters, we show that the {R}{{IRX,obs}} of some SNRs agrees with theoretical ratios of SNR shocks in which dust grains are heated and destroyed by collisions with plasma particles. For the majority of SNRs, however, {R}{{IRX,obs}} values are either significantly smaller or significantly larger than the theoretical ratios. The latter SNRs have relatively low dust temperatures. We discuss how the natural and/or environmental properties of SNRs could have affected the IRX flux ratios and the IRX morphology of these SNRs. We conclude that the SNRs with largest {R}{{IRX,obs}} are probably located in a dense environment and that their IR emission is from dust heated by shock radiation rather than by collisions. Our result suggests that the IRX flux ratio, together with dust temperature, can be used to infer the nature of unresolved SNRs in external galaxies.

  3. A new limit on the time between the nucleosynthesis and the acceleration of cosmic rays in supernova remnants using the Co/Ni ratio

    NASA Technical Reports Server (NTRS)

    Webber, W. R.; Gupta, M.

    1990-01-01

    Using new cross section measurements of Ni into Co, data on the Co/Ni ratio in cosmic rays from the HEAO C spacecraft have been reinterpreted in terms of the time between nucleosynthesis and the acceleration of cosmic rays, delta t. The observed Co/Ni ratio is now consistent with interstellar fragmentation only, leading to a small or zero source abundance. In terms of the decay of e-process nucleosynthesis nuclides into Co after a supernova explosion, this permits an estimate of delta t = 4-30,000 yr for the time between nucleosynthesis and the acceleration of cosmic rays if supernovae are the direct progenitors of cosmic rays. These age limits are used in conjunction with models of the expansion of supernova remnants (SNRs), to estimate that cosmic rays are accelerated when the radius of these remnants is between 0.1 and 25 pc.

  4. Supernova remnants

    NASA Astrophysics Data System (ADS)

    Decourchelle, A.

    2016-06-01

    Supernova remnants result from the explosion of a star and keep trace, in their young ejecta-dominated phase, both of the explosion mechanism and to a lesser extent of the nature of the progenitor. They inject a large amount of energy into their surroundings, which impacts significantly the interstellar medium and to a larger extent the working of the galaxy by distributing heavy elements, heating to tens of million degrees large fractions of gas, accelerating high-energy particles, generating turbulence and amplification of the magnetic field. I will review the observational results on supernova remnants and their related scientific issues before suggesting directions for future ambitious XMM-Newton observations.

  5. Ortho-to-para Ratio Studies of Shocked H2 Gas in the Two Supernova Remnants IC 443 and HB 21

    NASA Astrophysics Data System (ADS)

    Shinn, Jong-Ho; Lee, Ho-Gyu; Moon, Dae-Sik

    2012-11-01

    We present near-infrared (2.5-5.0 μm) spectral studies of shocked H2 gas in two supernova remnants, IC 443 and HB 21, which are well known for their interactions with nearby molecular clouds. The observations were performed with the Infrared Camera aboard the AKARI satellite. At the energy range 7000 K lsim E(\\upsilon,J) lsim 20,000 K, the shocked H2 gas in IC 443 shows an ortho-to-para ratio (OPR) of 2.4+0.3 - 0.2, which is significantly lower than the equilibrium value 3, suggesting the existence of non-equilibrium OPR. The shocked gas in HB 21 also indicates a potential non-equilibrium OPR in the range of 1.8-2.0. The level populations are well described by the power-law thermal admixture model with a single OPR, where the temperature integration range is 1000-4000 K. We conclude that the obtained non-equilibrium OPR probably originates from the reformed H2 gas of dissociative J-shocks, considering several factors such as the shock combination requirement, the line ratios, and the possibility that H2 gas can form on grains with a non-equilibrium OPR. We also investigate C-shocks and partially dissociative J-shocks as the origin of the non-equilibrium OPR. However, we find that they are incompatible with the observed ionic emission lines for which dissociative J-shocks are required to explain. The difference in the collision energy of H atoms on grain surfaces would give rise to the observed difference between the OPRs of IC 443 and HB 21, if dissociative J-shocks are responsible for the H2 emission. Our study suggests that dissociative J-shocks can produce shocked H2 gas with a non-equilibrium OPR.

  6. Aerodynamic performance of a 1.35-pressure-ratio axial-flow fan stage

    NASA Technical Reports Server (NTRS)

    Osborn, W. M.; Moore, R. D.; Steinke, R. J.

    1978-01-01

    The overall blade element performances and the aerodynamic design parameters are presented for a 1.35-pressure-ratio fan stage. The fan stage was designed for a weight flow of 32.7 kilograms per second and a tip speed of 302.8 meters per second. At design speed the stage peak efficiency of 0.879 occurred at a pressure ratio of 1.329 and design flow. Stage stall margin was approximately 14 percent. At design flow rotor efficiency was 0.94 and the pressure ratio was 1.360.

  7. Aerodynamic performance of a 1.25-pressure-ratio axial-flow fan stage

    NASA Technical Reports Server (NTRS)

    Moore, R. D.; Steinke, R. J.

    1974-01-01

    Aerodynamic design parameters and overall and blade-element performances of a 1.25-pressure-ratio fan stage are reported. Detailed radial surveys were made over the stable operating flow range at rotative speeds from 70 to 120 percent of design speed. At design speed, the measured stage peak efficiency of 0.872 occurred at a weight flow of 34.92 kilograms per second and a pressure ratio of 1.242. Stage stall margin is about 20 percent based on the peak efficiency and stall conditions. The overall peak efficiency for the rotor was 0.911. The overall stage performance showed no significant change when the stators were positioned at 1, 2, or 4 chords downstream of the rotor.

  8. The ratio of glycated albumin to hemoglobin A1c measured in IFCC units accurately represents the glycation gap.

    PubMed

    Akatsuka, Junya; Mochizuki, Mie; Musha, Ikuma; Ohtake, Akira; Kobayashi, Kisho; Kikuchi, Toru; Kikuchi, Nobuyuki; Kawamura, Tomoyuki; Urakami, Tatsuhiko; Sugihara, Shigetaka; Hoshino, Tadao; Amemiya, Shin

    2015-01-01

    The glycation gap (G-gap: difference between measured hemoglobin A1c [A1C] and the value predicted by its regression on the fructosamine level) is stable and associated with diabetic complications. Measuring A1C level in International Federation of Clinical Chemistry (IFCC) units (A1C-SI; mmol/mol) and National Glycohemoglobin Standardization Program units (A1C-NGSP; %) and using glycated albumin (GA) level instead of fructosamine level for calculating the G-gap, we investigated whether the G-gap is better represented by GA/A1C ratio if expressed in SI units (GA/A1C-SI ratio) rather than in NGSP units (GA/A1C-% ratio). We examined 749 Japanese children with type 1 diabetes using simultaneous GA and A1C measurements. Of these, 369 patients were examined more than five times to assess the consistency of the G-gap and the GA/A1C ratio within individuals. The relationship of GA/A1C-% ratio to the corresponding A1C-NGSP was stronger than that of GA/A1C-SI ratio to A1C-IFCC. At enrollment, the inverse relationship between the GA/A1C-SI ratio and G-gap was highly significant (R(2) = 0.95) compared with that between the GA/A1C-% ratio and G-gap (R(2) = 0.69). A highly significant inverse relationship was also observed between the mean GA/A1C-SI ratio and the mean G-gaps obtained individually over time (R(2) = 0.95) compared with that using the corresponding A1C-NGSP (R(2) = 0.67). We conclude that the G-gap is better represented by the GA/A1C-SI ratio. We propose the use of mean GA/A1C-SI ratios easily obtained individually over time as reference values in Japanese children with type 1 diabetes (6.75 ± 0.60 [means ± SD]). PMID:25367400

  9. Ratio

    NASA Astrophysics Data System (ADS)

    Webster, Nathan A. S.; Pownceby, Mark I.; Madsen, Ian C.; Studer, Andrew J.; Manuel, James R.; Kimpton, Justin A.

    2014-12-01

    Effects of basicity, B (CaO:SiO2 ratio) on the thermal range, concentration, and formation mechanisms of silico-ferrite of calcium and aluminum (SFCA) and SFCA-I iron ore sinter bonding phases have been investigated using an in situ synchrotron X-ray diffraction-based methodology with subsequent Rietveld refinement-based quantitative phase analysis. SFCA and SFCA-I phases are the key bonding materials in iron ore sinter, and improved understanding of the effects of processing parameters such as basicity on their formation and decomposition may assist in improving efficiency of industrial iron ore sintering operations. Increasing basicity significantly increased the thermal range of SFCA-I, from 1363 K to 1533 K (1090 °C to 1260 °C) for a mixture with B = 2.48, to ~1339 K to 1535 K (1066 °C to 1262 °C) for a mixture with B = 3.96, and to ~1323 K to 1593 K (1050 °C to 1320 °C) at B = 4.94. Increasing basicity also increased the amount of SFCA-I formed, from 18 wt pct for the mixture with B = 2.48 to 25 wt pct for the B = 4.94 mixture. Higher basicity of the starting sinter mixture will, therefore, increase the amount of SFCA-I, considered to be more desirable of the two phases. Basicity did not appear to significantly influence the formation mechanism of SFCA-I. It did, however, affect the formation mechanism of SFCA, with the decomposition of SFCA-I coinciding with the formation of a significant amount of additional SFCA in the B = 2.48 and 3.96 mixtures but only a minor amount in the highest basicity mixture. In situ neutron diffraction enabled characterization of the behavior of magnetite after melting of SFCA produced a magnetite plus melt phase assemblage.

  10. A miniature Rotary Compressor with a 1:10 compression ratio

    NASA Astrophysics Data System (ADS)

    Dmitriev, Olly; Tabota, Eugene; Arbon EurIng, Ian; FIMechE, CEng

    2015-08-01

    Micro compressors have applications in medical devices, robotics and “nanosatellites”. The problem of active cooling for photo detectors in “nano-satellites” becomes more important because the majority of space missions target Earth observation, and passive cooling does not provide the required temperatures to achieve the desired SNR levels. Reciprocating compressors used in cryocoolers cause vibrations. VERT Rotors has built an ultralow-vibration rotary compressor with 40mm-long screws, and our prototype delivered 1:10 compression ratio. This “nano” compressor is a non-conventional conical type consisting of an Inner conical screw rotor revolving inside an Outer screw rotor.

  11. Remnant field detector

    DOEpatents

    Visser, Age T.

    1988-01-01

    A method apparatus for qualitatively detecting remnant magnetic fields in matched pairs of magnet cores. Equal magnitude and oppositely oriented magnetic flux is induced in the magnet cores by oppositely wound primary windings and current source. Identically wound secondary windings generate output voltages in response to the induced flux. The output voltages generated should be of equal magnitude and opposite polarity if there is no remnant field in the cores. The output voltages will be unequal which is detected if either core has a remnant field.

  12. Remnant field detector

    DOEpatents

    Visser, Age T.

    1988-05-03

    A method apparatus for qualitatively detecting remnant magnetic fields in matched pairs of magnet cores. Equal magnitude and oppositely oriented magnetic flux is induced in the magnet cores by oppositely wound primary windings and current source. Identically wound secondary windings generate output voltages in response to the induced flux. The output voltages generated should be of equal magnitude and opposite polarity if there is no remnant field in the cores. The output voltages will be unequal which is detected if either core has a remnant field.

  13. The Rediscovery of the Antlia Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Orchard, Alexander; Benjamin, Robert A.; Gostisha, Martin; Haffner, L. Matthew; Hill, Alex S.; Barger, Kathleen

    2015-01-01

    While undertaking a survey of velocity-resolved diffuse optical emission from the [S II] 6716 A line with the Wisconsin H-alpha Mapper, we have rediscovered the Antlia Supernova remnant, a 26 degree diameter remmant near the Gum Nebula that was originally detected in SHASSA (Southern H-alpha Sky Survey Atlas) by P. McCullough in 2002. The original discovery showed this remnant was associated with ¼ keV X-ray emission in the ROSAT All-Sky Survey, and argued that Antlia was potentially the closest remnant to the Sun. We will present an analysis of the H-alpha and [S II] lines in this direction: the ratio of these lines indicate the shell is consistent with being a supernova remnant and the velocities allow us to constrain its age. We discuss this remnant in the context of the evolution of the entire Gum Nebula region, noting that its proximity and age make it possible to search for geochemical evidence of this remnant on Earth. This work was supported by the National Science Foundation's REU program through NSF Award AST-1004881.

  14. Acoustic testing of a 1.5 pressure ratio, low tip speed fan (QEP fan B scale model)

    NASA Technical Reports Server (NTRS)

    Kazin, S. B.; Minzner, W. R.; Paas, J. E.

    1972-01-01

    A scale model (0.484 scale factor) of a single stage fan designed for a 1.5 pressure ratio and 1160 ft/sec tip speed was tested to determine its noise characteristics. The fan had 26 blades and 60 outlet guide vanes, with vanes spaced two rotor blade aerodynamic chords from the blades. The effects of speed, exhaust nozzle area and fan frame acoustic treatment on the scale model's noise characteristics were investigated.

  15. Transfusion of Plasma, Platelets, and Red Blood Cells in a 1:1:1 vs a 1:1:2 Ratio and Mortality in Patients With Severe Trauma

    PubMed Central

    Holcomb, John B.; Tilley, Barbara C.; Baraniuk, Sarah; Fox, Erin E.; Wade, Charles E.; Podbielski, Jeanette M.; del Junco, Deborah J.; Brasel, Karen J.; Bulger, Eileen M.; Callcut, Rachael A.; Cohen, Mitchell Jay; Cotton, Bryan A.; Fabian, Timothy C.; Inaba, Kenji; Kerby, Jeffrey D.; Muskat, Peter; O’Keeffe, Terence; Rizoli, Sandro; Robinson, Bryce R. H.; Scalea, Thomas M.; Schreiber, Martin A.; Stein, Deborah M.; Weinberg, Jordan A.; Callum, Jeannie L.; Hess, John R.; Matijevic, Nena; Miller, Christopher N.; Pittet, Jean-Francois; Hoyt, David B.; Pearson, Gail D.; Leroux, Brian; van Belle, Gerald

    2015-01-01

    IMPORTANCE Severely injured patients experiencing hemorrhagic shock often require massive transfusion. Earlier transfusion with higher blood product ratios (plasma, platelets, and red blood cells), defined as damage control resuscitation, has been associated with improved outcomes; however, there have been no large multicenter clinical trials. OBJECTIVE To determine the effectiveness and safety of transfusing patients with severe trauma and major bleeding using plasma, platelets, and red blood cells in a 1:1:1 ratio compared with a 1:1:2 ratio. DESIGN, SETTING, AND PARTICIPANTS Pragmatic, phase 3, multisite, randomized clinical trial of 680 severely injured patients who arrived at 1 of 12 level I trauma centers in North America directly from the scene and were predicted to require massive transfusion between August 2012 and December 2013. INTERVENTIONS Blood product ratios of 1:1:1 (338 patients) vs 1:1:2 (342 patients) during active resuscitation in addition to all local standard-of-care interventions (uncontrolled). MAIN OUTCOMES AND MEASURES Primary outcomes were 24-hour and 30-day all-cause mortality. Prespecified ancillary outcomes included time to hemostasis, blood product volumes transfused, complications, incidence of surgical procedures, and functional status. RESULTS No significant differences were detected in mortality at 24 hours (12.7% in 1:1:1 group vs 17.0% in 1:1:2 group; difference, −4.2% [95% CI, −9.6% to 1.1%]; P = .12) or at 30 days (22.4% vs 26.1%, respectively; difference, −3.7% [95% CI, −10.2% to 2.7%]; P = .26). Exsanguination, which was the predominant cause of death within the first 24 hours, was significantly decreased in the 1:1:1 group (9.2% vs 14.6% in 1:1:2 group; difference, −5.4% [95% CI, −10.4% to −0.5%]; P = .03). More patients in the 1:1:1 group achieved hemostasis than in the 1:1:2 group (86% vs 78%, respectively; P = .006). Despite the 1:1:1 group receiving more plasma (median of 7 U vs 5 U, P < .001) and

  16. "Suzaku Highlight Results on Supernova Remnants"

    NASA Technical Reports Server (NTRS)

    Petre, Robert

    2006-01-01

    Highlights of the early Suzaku (formerly Astro-E2) observations of supernova remnants are presented. Suzaku offers unique capabilities for the study of supernova remnants. The unprecedented combination of imaging and spectral resolution below 1 keV in the X-ray Imaging Spectrometer (XIS) makes possible mapping of C, N and O abundances in Galactic remnants of all ages. The first detection of carbon lines in the Cygnus Loop and mapping of the O VII to O VIII ratio in SN 1006 demonstrate this capability. The XIS sensitivity to soft, low surface brightness emission is exemplified by spectroscopy in the 0.3-1.0 keV band of the North Polar Spur and other Galactic ISM structures. Such observations make possible inferences about plasma conditions and abundances. The sensitivity above 6 keV via a combination of the XIS (below 10 keV) and the Hard X-ray Detector (above 10 keV) allows broad band (2-40 keV) spectroscopy and mapping of extended remnants with hard emission components. These components are generally associated with sites of particle acceleration, and measuring their spectral shape potentially provides information about the TeV electron population and its acceleration and energy loss mechanisms. Examples of such remnants observed by Suzaku are the non-thermal emission dominated remnants RX J1713.7-3946 and RX J0852.0-4622, for which flux beyond 30 keV has been detected. The status of the mission and prospects for future groundbreaking observations of supernova remnants will be discussed.

  17. Remnants, fuzzballs or wormholes?

    NASA Astrophysics Data System (ADS)

    Mathur, Samir D.

    2014-11-01

    The black hole information paradox has caused enormous confusion over four decades. But in recent years, the theorem of quantum strong-subadditivity has sorted out the possible resolutions into three sharp categories: (i) No new physics at r ≫ lp; this necessarily implies remnants/information loss. A realization of remnants is given by a baby universe attached near r 0. (ii) Violation of the "no-hair" theorem by nontrivial effects at the horizon r M. This possibility is realized by fuzzballs in string theory, and gives unitary evaporation. (iii) Having the vacuum at the horizon, but requiring that Hawking quanta at r M3 be somehow identified with degrees of freedom inside the black hole. A model for this "extreme nonlocality" is realized by conjecturing that wormholes connect the radiation quanta to the hole.

  18. ANTIPROTONS PRODUCED IN SUPERNOVA REMNANTS

    SciTech Connect

    Berezhko, E. G.; Ksenofontov, L. T.

    2014-08-20

    We present the energy spectrum of an antiproton cosmic ray (CR) component calculated on the basis of the nonlinear kinetic model of CR production in supernova remnants (SNRs). The model includes the reacceleration of antiprotons already existing in the interstellar medium as well as the creation of antiprotons in nuclear collisions of accelerated protons with gas nuclei and their subsequent acceleration by SNR shocks. It is shown that the production of antiprotons in SNRs produces a considerable effect in their resultant energy spectrum, making it essentially flatter above 10 GeV so that the spectrum at TeV energies increases by a factor of 5. The calculated antiproton spectrum is consistent with the PAMELA data, which correspond to energies below 100 GeV. As a consistency check, we have also calculated within the same model the energy spectra of secondary nuclei and show that the measured boron-to-carbon ratio is consistent with the significant SNR contribution.

  19. Molecular environment of the supernova remnant IC 443: Discovery of the molecular shells surrounding the remnant

    SciTech Connect

    Su, Yang; Fang, Min; Yang, Ji; Zhou, Ping; Chen, Yang

    2014-06-20

    We have carried out {sup 12}CO, {sup 13}CO, and C{sup 18}O observations toward the mixed morphology supernova remnant (SNR) IC 443. The observations cover a 1.°5 × 1.°5 area and allow us to investigate the overall molecular environment of the remnant. Some northern and northeastern partial shell structure of CO gas is around the remnant. One of the partial shells, about 5' extending beyond the northeastern border of the remnant's bright radio shell, seems to just confine the faint radio halo. On the other hand, some faint CO clumps can be discerned along the eastern boundary of the faint remnant's radio halo. Connecting the eastern CO clumps, the northeastern partial shell structures, and the northern CO partial shell, we can see that a half molecular ring structure appears to surround the remnant. The LSR velocity of the half-ring structure is in the range of –5 km s{sup –1} to –2 km s{sup –1}, which is consistent with that of the –4 km s{sup –1} molecular clouds. We suggest that the half-ring structure of the CO emission at V {sub LSR} ∼ –4 km s{sup –1} is associated with the SNR. The structures are possibly swept up by the stellar winds of SNR IC 443's massive progenitor. Based on the Wide-field Infrared Survey Explorer and the Two Micron All Sky Survey near-IR database, 62 young stellar object (YSO) candidates are selected within the radio halo of the remnant. These YSO candidates concentrated along the boundary of the remnant's bright radio shell are likely to be triggered by the stellar winds from the massive progenitor of SNR IC 443.

  20. Featured Image: Modeling Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-05-01

    This image shows a computer simulation of the hydrodynamics within a supernova remnant. The mixing between the outer layers (where color represents the log of density) is caused by turbulence from the Rayleigh-Taylor instability, an effect that arises when the expanding core gas of the supernova is accelerated into denser shell gas. The past standard for supernova-evolution simulations was to perform them in one dimension and then, in post-processing, manually smooth out regions that undergo Rayleigh-Taylor turbulence (an intrinsically multidimensional effect). But in a recent study, Paul Duffell (University of California, Berkeley) has explored how a 1D model could be used to reproduce the multidimensional dynamics that occur in turbulence from this instability. For more information, check out the paper below!CitationPaul C. Duffell 2016 ApJ 821 76. doi:10.3847/0004-637X/821/2/76

  1. What Shapes Supernova Remnants?

    NASA Astrophysics Data System (ADS)

    Lopez, Laura A.

    2014-01-01

    Evidence has mounted that Type Ia and core-collapse (CC) supernovae (SNe) can have substantial deviations from spherical symmetry; one such piece of evidence is the complex morphologies of supernova remnants (SNRs). However, the relative role of the explosion geometry and the environment in shaping SNRs remains an outstanding question. Recently, we have developed techniques to quantify the morphologies of SNRs, and we have applied these methods to the extensive X-ray and infrared archival images available of Milky Way and Magellanic Cloud SNRs. In this proceeding, we highlight some results from these studies, with particular emphasis on SNR asymmetries and whether they arise from ``nature'' or ``nurture''.

  2. Sedimentary Rock Remnants

    NASA Technical Reports Server (NTRS)

    2005-01-01

    29 July 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows knobs of remnant, wind-eroded, layered sedimentary rock that once completely covered the floor of a crater located west of the Sinus Meridiani region of Mars. Sedimentary rock outcrops are common throughout the Sinus Meridiani region and its surrounding cratered terrain.

    Location near: 2.2oN, 7.9oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Autumn

  3. Supernova Remnants And GLAST

    SciTech Connect

    Slane, Patrick; /Harvard-Smithsonian Ctr. Astrophys.

    2011-11-29

    It has long been speculated that supernova remnants represent a major source of cosmic rays in the Galaxy. Observations over the past decade have ceremoniously unveiled direct evidence of particle acceleration in SNRs to energies approaching the knee of the cosmic ray spectrum. Nonthermal X-ray emission from shell-type SNRs reveals multi-TeV electrons, and the dynamical properties of several SNRs point to efficient acceleration of ions. Observations of TeV gamma-ray emission have confirmed the presence of energetic particles in several remnants as well, but there remains considerable debate as to whether this emission originates with high energy electrons or ions. Equally uncertain are the exact conditions that lead to efficient particle acceleration. Based on the catalog of EGRET sources, we know that there is a large population of Galactic gamma-ray sources whose distribution is similar to that of SNRs.With the increased resolution and sensitivity of GLAST, the gamma-ray SNRs from this population will be identified. Their detailed emission structure, along with their spectra, will provide the link between their environments and their spectra in other wavebands to constrain emission models and to potentially identify direct evidence of ion acceleration in SNRs. Here I summarize recent observational and theoretical work in the area of cosmic ray acceleration by SNRs, and discuss the contributions GLAST will bring to our understanding of this problem.

  4. A Multiwavelength Study of Tycho's Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Petre, Robert

    The remnant of the supernova of 1572 A.D., now known as Tycho's Supernova Remnant (SNR), is one of the most well studied SNRs in existence, having been observed with telescopes from radio waves to gamma-rays. We propose a multi-wavelength study of this remnant, with particular focus on archival data in the infrared from Spitzer, WISE, and Herschel, and in gamma-rays from Fermi. The IR data is of extremely high-quality, and will allow us to answer or further constrain several mysteries regarding Tycho, known to be the remnant of a Type Ia supernova. Is the remnant a source of particle acceleration producing cosmic-rays in excess of 10^15 ev? What is the source of the gamma-ray emission seen at both GeV and TeV energies? What is the nature of the medium surrounding the remnant, into which it is currently expanding at over 4000 km/s? Has any dust formed in the iron-rich ejected material from the supernova? The answers to all of these questions will require a multi-wavelength approach, and we will supplement the IR and gamma-ray data here with archival X-ray data from both Chandra and XMM- Newton. In young SNRs like Tycho, IR and X-ray emission is inherently connected, since the hot ions and electrons that give rise to the thermal X-ray emission also heat (and destroy) dust grains in the post-shock gas. Infrared spectroscopy is a highly sensitive function of gas density, and provides a more powerful diagnostic tool for this parameter than X-rays alone do. This post-shock density is a crucial parameter for both particle acceleration and gamma-ray emission models, and the IR data will allow us to measure this density at any point in the remnant. We will explore the relationship between dust and gas in the immediate post-shock region. Because the blast wave is encountering the ambient Galactic ISM, this will provide strong constraints on the dust composition and dust-to-gas mass ratio in the general ISM. At all wavelengths, Tycho is a wealth of information, and by

  5. PROGENITORS OF RECOMBINING SUPERNOVA REMNANTS

    SciTech Connect

    Moriya, Takashi J.

    2012-05-01

    Usual supernova remnants have either ionizing plasma or plasma in collisional ionization equilibrium, i.e., the ionization temperature is lower than or equal to the electron temperature. However, the existence of recombining supernova remnants, i.e., supernova remnants with ionization temperature higher than the electron temperature, has been recently confirmed. One suggested way to have recombining plasma in a supernova remnant is to have a dense circumstellar medium at the time of the supernova explosion. If the circumstellar medium is dense enough, collisional ionization equilibrium can be established in the early stage of the evolution of the supernova remnant and subsequent adiabatic cooling, which occurs after the shock wave gets out of the dense circumstellar medium, makes the electron temperature lower than the ionization temperature. We study the circumstellar medium around several supernova progenitors and show which supernova progenitors can have a circumstellar medium dense enough to establish collisional ionization equilibrium soon after the explosion. We find that the circumstellar medium around red supergiants (especially massive ones) and the circumstellar medium dense enough to make Type IIn supernovae can establish collisional ionization equilibrium soon after the explosion and can evolve to become recombining supernova remnants. Wolf-Rayet stars and white dwarfs have the possibility to be recombining supernova remnants but the fraction is expected to be very small. As the occurrence rate of the explosions of red supergiants is much higher than that of Type IIn supernovae, the major progenitors of recombining supernova remnants are likely to be red supergiants.

  6. Determinants of ApoB, ApoA1, and the ApoB/ApoA1 ratio in healthy schoolgirls, prospectively studied from mean ages 10 to 19 years: the Cincinnati National Growth and Health Study.

    PubMed

    Morrison, John A; Glueck, Charles J; Daniels, Stephen R; Horn, Paul S; Wang, Ping

    2012-10-01

    The objectives were to prospectively assess determinants of apolipoproteins B (ApoB), A1 (ApoA1), and the ApoB/ApoA1 ratio in 797 healthy black and white schoolgirls from mean ages 10 to 19. There was prospective 9-year follow-up, with measures of ApoB at mean ages 10, 12, 14, 16 and 19, ApoA1 at mean ages 12, 14, 16, and 19, and assessment of annual reports of delayed menstrual cyclicity (≥42 days) from ages 14 to 19. Studies of 402 black and 395 white healthy schoolgirls were done in public and private schools, in urban and suburban Cincinnati. Black girls had lower ApoB, higher ApoA1, and lower ApoB/ApoA1. SHBG at age 14 in white and black girls was inversely correlated with the ApoB/ApoA1. At age 19, ≥3 annual reports of menstrual delay ≥42 days and metabolic syndrome were associated with higher ApoB and a higher ApoB/ApoA1 ratio. From ages 14 to 19, BMI and TG were independently positively associated with ApoB. Menstrual cyclicity ≥42 days, metabolic syndrome, BMI, and TG were independently positively associated with ApoB/ApoA1 ratios, while black race was negatively associated. The atherogenic ApoB/ApoA1 ratio from ages 14 to 19 is lower in black girls, and positively associated with hyperandrogenism, menstrual cyclicity ≥42 days, BMI, TG, and the metabolic syndrome, facilitating an adolescent approach to primary prevention of cardiovascular disease. PMID:22512822

  7. Properties of optically selected supernova remnant candidates in M33

    SciTech Connect

    Lee, Jong Hwan; Lee, Myung Gyoon E-mail: mglee@astro.snu.ac.kr

    2014-10-01

    Narrowband images covering strong emission lines are efficient for surveying supernova remnants (SNRs) in nearby galaxies. Using the narrowband images provided by the Local Group Galaxy Survey, we searched for SNRs in M33. Culling the objects with enhanced [S II]/Hα and round morphology in the continuum-subtracted Hα and [S II] images, we produced a list of 199 sources. Among them, 79 are previously unknown. Their progenitor and morphology types were classified. A majority of the sample (170 objects) are likely remnants of core-collapse supernovae (SNe), and 29 are remnants of Type Ia SNe. The cumulative size distribution of these objects is found to be similar to that of the M31 remnants derived in a similar way. We obtain a power-law slope, α = 2.38 ± 0.05. Thus, a majority of the sources are considered to be in the Sedov-Taylor phase, consistent with previous findings. The histogram of the emission-line ratio ([S II]/Hα) of the remnants has two concentrations at [S II]/Hα ∼ 0.55 and ∼0.8, as in M31. Interestingly, L {sub X} (and L {sub 20cm}) of the compact center-bright objects are correlated with their optical luminosity. The remnants with X-ray emission have brighter optical surface brightnesses and smaller diameters than those without X-ray emission.

  8. Properties of Optically Selected Supernova Remnant Candidates in M33

    NASA Astrophysics Data System (ADS)

    Lee, Jong Hwan; Lee, Myung Gyoon

    2014-10-01

    Narrowband images covering strong emission lines are efficient for surveying supernova remnants (SNRs) in nearby galaxies. Using the narrowband images provided by the Local Group Galaxy Survey, we searched for SNRs in M33. Culling the objects with enhanced [S II]/Hα and round morphology in the continuum-subtracted Hα and [S II] images, we produced a list of 199 sources. Among them, 79 are previously unknown. Their progenitor and morphology types were classified. A majority of the sample (170 objects) are likely remnants of core-collapse supernovae (SNe), and 29 are remnants of Type Ia SNe. The cumulative size distribution of these objects is found to be similar to that of the M31 remnants derived in a similar way. We obtain a power-law slope, α = 2.38 ± 0.05. Thus, a majority of the sources are considered to be in the Sedov-Taylor phase, consistent with previous findings. The histogram of the emission-line ratio ([S II]/Hα) of the remnants has two concentrations at [S II]/Hα ~ 0.55 and ~0.8, as in M31. Interestingly, L X (and L 20 cm) of the compact center-bright objects are correlated with their optical luminosity. The remnants with X-ray emission have brighter optical surface brightnesses and smaller diameters than those without X-ray emission.

  9. Impact of corpulence parameters and haemoglobin A1c on metabolic control in type 2 diabetic patients: comparison of apolipoprotein B/A-I ratio with fasting and postprandial conventional lipid ratios

    PubMed Central

    Diaf, Mustapha; Khaled, Boumediene M.; Sellam, Fériel

    2015-01-01

    Background and objective The incidence of diabetes co-morbidities could probably be better assessed by studying its associations with major corpulence parameters and glycaemic control indicators. We assessed the utility of body mass index (BMI), waist circumference (WC), and glycosylated haemoglobin (HbA1c) levels in metabolic control for type 2 diabetic patients. Methods Fasting and postprandial blood samples were collected from 238 type 2 diabetic patients aged 57.4±11.9 years. The sera were analysed for glucose, HbA1c, total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), and apolipoproteins (apoA-I and apoB). Ratios of lipids and apolipoproteins were calculated and their associations with BMI, WC, and HbA1c levels were analysed. Results Our investigation showed increases in most fasting and postprandial lipid parameters according to BMI and WC. In men, postprandial HDL-c and TG levels were significantly higher (p<0.05) in overweight and obese patients, respectively, as well as in patients with abdominal obesity. Contrariwise, postprandial TC levels were significantly higher (p<0.01) in overweight and abdominal obese women. However, elevations of apoA-I and apoB levels were according to BMI and WC in both genders. There was a strong influence of BMI, WC, and HbA1c levels on the apoB/apoA-I ratio compared to traditional fasting and postprandial lipid ratios in both men and women. The apoB/apoA-I ratio was more correlated with postprandial TC/HDL and LDL-c/HDL-c ratios in men and with postprandial TG/HDL-c in women. Conclusion The apoB/apoA-I ratio is helpful in assessing metabolic risk caused by overall obesity, abdominal obesity and impaired glycaemia in type 2 diabetic patients. PMID:25959906

  10. Remnants of Lost Geology

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    In eastern Arabia Terra, remnants of a once vast layered terrain are evident as isolated buttes, mesas, and deeply-filled craters. The origin of the presumed sediments that created the layers is unknown, but those same sediments, now eroded, may be the source of the thick mantle of dust that covers much of Arabia Terra today.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

    Image information: VIS instrument. Latitude 20.5, Longitude 50 East (310 West). 19 meter/pixel resolution.

  11. The Associations of Novel Vitamin D3 Metabolic Gene CYP27A1 Polymorphism, Adiponectin/Leptin Ratio, and Metabolic Syndrome in Middle-Aged Taiwanese Males

    PubMed Central

    Liu, Chia-Chu; Huang, Chun-Nung; Lee, Yung-Chin; Chu, Chih-Sheng; Chang, Chu-Fen; Kuo, Po-Lin; Lai, Wen-Ter

    2015-01-01

    Metabolic syndrome (MetS) confers increased risks of cardiovascular disease (CVD). Both vitamin D3 and adipocytokines (especially adiponectin and leptin) have a great impact on CVD and MetS. In vitamin D3 metabolism, the vitamin D3 25-hydroxylase (CYP27A1) and 25-hydroxyvitamin D3 1-alpha-hydroxylase (CYP27B1) are two key enzymes. This study aimed to examine the influence of vitamin D3 CYP27 single nucleotide polymorphisms (SNPs) on adipocytokines and MetS. Cross-sectional data and DNA samples were collected from male volunteers (n = 649, age: 55.7 ± 4.7 years). Two tagging SNPs, CYP27A1 rs4674344 and CYP27B1 rs10877012, were selected from the HapMap project. MetS was significantly associated with the CYP27A1 rs4674344 SNP (P = 0.04) and the ratio of adiponectin/leptin (A/L ratio) was most correlated to the CYP27A1 rs4674344 SNP, appearing to be significantly lower in T-carriers than in AA subjects (3.7 ± 4.0 versus 5.1 ± 6.0, P = 0.001) and significantly negatively associated after adjustment. For each MetS component associated with the CYP27A1 rs4674344 SNP, the A/L ratios were significantly negative in preclinical stage (condition not meeting the individual criteria), except the blood pressure. In conclusion, CYP27A1 rs4674344 SNP, A/L ratio, and MetS are significantly associated and T-carriers might have a higher risk of developing MetS due to low A/L ratios in the preclinical stage. PMID:25628655

  12. G29.7-0.3: another supernova remnant with an identity crisis

    NASA Technical Reports Server (NTRS)

    Becker, R. H.; Helfand, D. J.; Szymkowiak, A. E.

    1983-01-01

    New radio and X-ray observations of the galactic supernova remnant G29.7-0.3 show that it is composed of two spectrally distinct components: a steep-spectrum, incomplete shell 3 arcmin in extent enclosing a flat-spectrum, X-ray emitting region 30 arcsec across. Thus, G29.7-0.3 joins the ranks of supernova remnants which exhibit a combination of Crab-like and shell remnant attributes. The Crab-like core has the highest ratio of X-ray radio luminosity of all the Crab-like remnants observed to date, suggesting that it is an extremely young object.

  13. Apolipoprotein A1, B levels, and their ratio and the risk of a first stroke: a meta-analysis and case-control study.

    PubMed

    Dong, Hongli; Chen, Wei; Wang, Xiangyu; Pi, Fuhua; Wu, Yubin; Pang, Shaojie; Xie, Yuqing; Xia, Fangfang; Zhang, Qingying

    2015-12-01

    The associations of levels of apolipoprotein A1 (ApoA1) and apolipoprotein B and ApoB/A1 ratio and risk of a first stroke have not been reliably documented. We performed a meta-analysis to summarize the relationships and confirmed them in a case-control study. We identified relevant publications in PubMed and Embase databases up to June 1, 2015. A Dersimonian-Laird random effects model was used to compute summary relative risks (RRs) and 95 % confidence intervals (CIs). A case-control study was conducted in a southern Chinese population. We included 8 cohort and 4 case-control studies (222,774 subjects; 10,032 first stroke events) in the meta-analysis. Reduced ApoA1 level and increased ApoB level and ApoB/A1 ratio was associated with a first stroke in cohort studies (RR 0.86 [95 % CI 0.79-0.94], 1.66 [1.62-1.69], and 1.66 [1.63-1.70], respectively) and reduced ApoA1 level and increased ApoB/A1 ratio in case-control studies (0.68 [0.47-0.99] and 1.76 [1.50-2.06], respectively). When stratified by stroke type in cohort studies, the RR for ischemic stroke was 0.83 (0.76-0.90), 1.36 (1.32-1.40), and 1.38 (1.35-1.42) for the 3 factors, respectively. In our case-control study (1013 cases; 1029 controls), the OR for a first ischemic stroke was 0.83 (0.74-0.92), 1.33 (1.18-1.48) and 2.10 (1.76-2.51), respectively, with increased ApoA1 level associated with hemorrhagic stroke (1.37 [1.06-1.78]). Meta-analysis suggests that reduced ApoA1 level and increased ApoB level and ApoB/A1 ratio are risk factors for a first ischemic but not hemorrhagic stroke. Elevated ApoA1 level may be a risk factor for a first hemorrhagic stroke. PMID:26363640

  14. Pulsar-supernova remnant associations

    NASA Astrophysics Data System (ADS)

    Manchester, R. N.

    1994-04-01

    Pulsars and supernova remnants (SNRs) are both believed to be formed in the supernova explosions of massive stars. Therefore one might expect to see associations between the two classes of object. In fact, up until a couple of years ago, there was only a handful of believable associations and even now there are only nine or ten. It is relatively easy to explain why such a small fraction of the 600 or so known pulsars are associated with supernova remnants. The average pulsar lifetime is of the order of 106 years, whereas the average supernova remnant is detectable for about 104 years. Therefore, one would expect only about one percent of pulsars to be still associated, as is observed. It is somewhat more difficult to explain why so few of the 150 known supernova remnants have associated pulsars. The main factor is that supernova remnants are seen throughout the Galaxy whereas most pulsars are detectable only relatively close to the Sun, within a few kiloparsec. Another factor is that pulsar emission is beamed, so even if a pulsar exists in a relatively nearby supernova remnant, it may be undetectable. The most believable of the suggested associations are listed. Associations which are possible but by no means certain are indicated by question mark. For the more certain associations, the pulsar position is within the SNR boundaries (an exception is 'The Duck', where the pulsar is at the tip of the 'beak'), the distance estimates for the pulsar and SNR are compatible, and the age estimates are likewise compatible. References to most of these associations may be found in the pulsar catalog of Taylor, Manchester and Lyne (1993, Astrophys. J. Suppl., 88, 529). Recent references not included in the catalog are for PSR B1706-44 (McAdam, Osborne and Parkinson, 1993, Nature, 361, 516) and PSR B2334+61 (Kulkarni et al., 1993, Nature, 362, 135).

  15. The Supernova Remnant CTA 1

    NASA Technical Reports Server (NTRS)

    Seward, Frederick D.

    1996-01-01

    The supernova remnants G327.1-1.1 and G327.4+0.4 (Kes 27) are located 1.5 deg apart in the constellation Norma. In 1980, Einstein IPC observations discovered that both were irregular filled-center X-ray sources with possible point sources superposed. This paper describes new ROSAT position sensitive proportional counter (PSPC) observations which both map the diffuse structure and clearly show several unresolved sources in each field. Both remnants have bright emitting regions inside the limb which might indicate the presence of high energy electrons accelerated by a pulsar. The interior region is more prominent in G327.1-1.1 than in Kes 27. The spectra are relatively strongly absorbed, as expected from distant remnants close to the galactic plane. Comparison of the X-ray and radio maps of each remnant allows us to attribute some emission to a shell and some to the interior. With this information, a blast-wave model is used to derive approximate ages and energy release. Indications are that the Kes 27 supernova deposited approximately 10(exp 51) ergs in the surrounding medium. The G327.1-1.1 event probably deposited a factor of 3-10 less.

  16. Constraints on black hole remnants

    SciTech Connect

    Giddings, S.B. )

    1994-01-15

    One possible fate of information lost to black holes is its preservation in black hole remnants. It is argued that a type of effective field theory describes such remnants (generically referred to as informons). The general structure of such a theory is investigated and the infinite pair production problem is revisited. A toy model for remnants clarifies some of the basic issues; in particular, infinite remnant production is not suppressed simply by the large internal volumes as proposed in cornucopion scenarios. Criteria for avoiding infinite production are stated in terms of couplings in the effective theory. Such instabilities remain a problem barring what would be described in that theory as a strong coupling conspiracy. The relation to Euclidean calculations of cornucopion production is sketched, and potential flaws in that analysis are outlined. However, it is quite plausible that pair production of ordinary black holes (e.g., Reissner-Noerdstrom or others) is suppressed due to strong effective couplings. It also remains an open possibility that a microsopic dynamics can be found yielding an appropriate strongly coupled effective theory of neutral informons without infinite pair production.

  17. Evolution of multiple supernova remnants

    NASA Astrophysics Data System (ADS)

    Vasiliev, Evgenii O.; Nath, Biman B.; Shchekinov, Yuri

    2015-01-01

    Heating of the interstellar medium (ISM) by multiple supernova (SN) explosions is at the heart of producing galaxy-scale outflows in starburst galaxies. Standard models of outflows assume a high efficiency of SNe in heating the gas to X-ray emitting temperatures and filling the central region of starburst with hot gas, in order to launch vigorous outflows. We use hydrodynamical simulations to study the efficiency of multiple SNe in heating the ISM and filling the volume with gas of high temperatures. We argue that it is important for SN remnants to have a large filling factor and a large heating efficiency. For this, they have to be clustered in space and time, and keep exploding until the hot gas percolates through the whole region, in order to compensate for the radiative loss. In the case of a limited number of SNe, we find that although the filling factor can be large, the heating efficiency declines after reaching a large value. In the case of a continuous series of SNe, the hot gas (T ≥ 3 × 106 K) can percolate through the whole region after the total volume filling factor reaches a threshold of ˜0.3. The efficiency of heating the gas to X-ray temperatures can be ≥0.1 after this percolation epoch, which occurs after a period of ≈10 Myr for a typical starburst SN rate density of νSN ≈ 10-9 pc-3 yr-1 and gas density of n ≈ 10 cm-3 in starburst nuclei regions. This matches the recent observations of a time delay of similar order between the onset of star formation and galactic outflows. The efficiency to heat gas up to X-ray temperatures (≥106.5 K) roughly scales as ν _SN^{0.2} n^{-0.6}. For a typical SN rate density and gas density in starburst nuclei, the heating efficiency is ˜0.15, also consistent with previous interpretations from X-ray observations. We discuss the implications of our results with regard to observational diagnostics of ionic ratios and emission measures in starburst nuclei regions.

  18. Einstein Observations of Galactic supernova remnants

    NASA Technical Reports Server (NTRS)

    Seward, Frederick D.

    1990-01-01

    This paper summarizes the observations of Galactic supernova remnants with the imaging detectors of the Einstein Observatory. X-ray surface brightness contours of 47 remnants are shown together with gray-scale pictures. Count rates for these remnants have been derived and are listed for the HRI, IPC, and MPC detectors.

  19. A SULT2A1 genetic variant identified by GWAS as associated with low serum DHEAS does not impact on the actual DHEA/DHEAS ratio

    PubMed Central

    Haring, Robin; Wallaschofski, Henri; Teumer, Alexander; Kroemer, Heyo; Taylor, Angela E; Shackleton, Cedric H L; Nauck, Matthias; Völker, Uwe; Homuth, Georg; Arlt, Wiebke

    2013-01-01

    DHEA is the major precursor of human sex steroid synthesis and is inactivated via sulfonation to DHEAS. A previous genome-wide association study related the single nucleotide polymorphism (SNP) rs2637125, located near the coding region of DHEA sulfotransferase, SULT2A1, to serum DHEAS concentrations. However, the functional relevance of this SNP with regard to DHEA sulfonation is unknown. Using data from 3300 participants of the population-based cohort Study of Health in Pomerania, we identified 43 individuals being homozygote for the minor allele of the SNP rs2637125 (AA) and selected two sex- and age-matched individuals with AG and GG genotype (n=172) respectively. Steroid analysis including measurement of serum DHEA and DHEAS was carried out by liquid chromatography/mass spectrometry, employing steroid oxime analysis for enhancing the sensitivity of DHEA detection. We applied quantile regression models to compare median hormone levels across SULT2A1 genotypes. Median comparisons by SULT2A1 genotype (AA vs AG and GG genotypes respectively) showed no differences in the considered hormones including DHEAS, DHEA, androstenedione, as well as cortisol and cortisone concentrations. SULT2A1 genotype also had no effect on the DHEA/DHEAS ratio. Sex-stratified analyses, as well as alternative use of the SULT2A1 SNP rs182420, yielded similar negative results. Genetic variants of SULT2A1 do not appear to have an effect on individual DHEA and DHEAS concentrations or the DHEA/DHEAS ratio as a marker of DHEA sulfonation capacity. PMID:23132913

  20. Numerical relativity simulations of neutron star merger remnants using conservative mesh refinement

    NASA Astrophysics Data System (ADS)

    Dietrich, Tim; Bernuzzi, Sebastiano; Ujevic, Maximiliano; Brügmann, Bernd

    2015-06-01

    We study equal- and unequal-mass neutron star mergers by means of new numerical relativity simulations in which the general relativistic hydrodynamics solver employs an algorithm that guarantees mass conservation across the refinement levels of the computational mesh. We consider eight binary configurations with total mass M =2.7 M⊙, mass ratios q =1 and q =1.16 , four different equations of state (EOSs) and one configuration with a stiff EOS, M =2.5 M⊙ and q =1.5 , which is one of the largest mass ratios simulated in numerical relativity to date. We focus on the postmerger dynamics and study the merger remnant, the dynamical ejecta, and the postmerger gravitational wave spectrum. Although most of the merger remnants are a hypermassive neutron star collapsing to a black hole+disk system on dynamical time scales, stiff EOSs can eventually produce a stable massive neutron star. During the merger process and on very short time scales, about ˜10-3- 10-2M⊙ of material become unbound with kinetic energies ˜1050 erg . Ejecta are mostly emitted around the orbital plane and favored by large mass ratios and softer EOS. The postmerger wave spectrum is mainly characterized by the nonaxisymmetric oscillations of the remnant neutron star. The stiff EOS configuration consisting of a 1.5 M⊙ and a 1.0 M⊙ neutron star, simulated here for the first time, shows a rather peculiar dynamics. During merger the companion star is very deformed; about ˜0.03 M⊙ of the rest mass becomes unbound from the tidal tail due to the torque generated by the two-core inner structure. The merger remnant is a stable neutron star surrounded by a massive accretion disk of rest mass ˜0.3 M⊙. This and similar configurations might be particularly interesting for electromagnetic counterparts. Comparing results obtained with and without the conservative mesh refinement algorithm, we find that postmerger simulations can be affected by systematic errors if mass conservation is not enforced in the

  1. HI Absorption in Merger Remnants

    NASA Technical Reports Server (NTRS)

    Teng, Stacy H.; Veileux, Sylvain; Baker, Andrew J.

    2012-01-01

    It has been proposed that ultraluminous infrared galaxies (ULIRGs) pass through a luminous starburst phase, followed by a dust-enshrouded AGN phase, and finally evolve into optically bright "naked" quasars once they shed their gas/dust reservoirs through powerful wind events. We present the results of our recent 21- cm HI survey of 21 merger remnants with the Green Bank Telescope. These remnants were selected from the QUEST (Quasar/ULIRG Evolution Study) sample of ULIRGs and PG quasars; our targets are all bolometrically dominated by AGN and sample all phases of the proposed ULIRG -> IR-excess quasar -> optical quasar sequence. We explore whether there is an evolutionary connection between ULIRGs and quasars by looking for the occurrence of HI absorption tracing neutral gas outflows; our results will allow us to identify where along the sequence the majority of a merger's gas reservoir is expelled.

  2. Detecting supernova remnants in external galaxies

    NASA Technical Reports Server (NTRS)

    Dickel, J. R.; Dodorico, S.

    1985-01-01

    Identification of supernova remnants (SNR) in external galaxies through the combined use of radio, optical and X-ray surveys is discussed. Some 24 likely distant galaxy SNR have been found in the past six years, though confirmation is often difficult. Radio surveys of other galaxies are restricted by background object contamination in the field, and confirmation of these candidates requires other techniques. Optical measurement of the ratio of the forbidden SII doublet at .6717 and .6731 microns to H-alpha, followed by spectroscopic or radio confirmation, has successfully identified SNR in the LMC and other galaxies, though few in number. Most of the SNR in the Magellanic Clouds have been detected as X-ray emitters, but towards M31 there are no coincidences between the lists of optical SNR and X-ray sources. An increase in SNR identifications should result from use of the Space Telescope and continued use of the VLA.

  3. New supernova remnant candidates in M 31.

    NASA Astrophysics Data System (ADS)

    Magnier, E. A.; Prins, S.; van Paradijs, J.; Lewin, W. H. G.; Supper, R.; Hasinger, G.; Pietsch, W.; Truemper, J.

    1995-12-01

    We have performed a CCD Hα, [SII], V survey of ~1.0 square degree of the disk of M 31 to search for new supernova remnant (SNR) candidates. We have identified candidates based on a combination of criteria: optical line-flux ratios, the presence or absence of ionizing blue stars, and optical morphology. We have identified a total of 178 candidate SNRs, divided into three confidence categories: 13 with the highest confidence, 54 with moderate confidence, and 111 with the lowest confidence. We have also identified 14 large structures with the characteristics of the superbubbles seen in the Galaxy and Magellanic Clouds. Of our 178 candidates, 15 have been identified in previous searches (Braun & Walterbos 1993; Blair et al. 1981; D'Odorico et al. 1980). We present finding charts of all candidate SNRs and the superbubbles we have noted. We also present a detailed discussion of SNR searches in the Local Group.

  4. Ruprecht 3: An old star cluster remnant?

    NASA Astrophysics Data System (ADS)

    Pavani, D. B.; Bica, E.; Ahumada, A. V.; Clariá, J. J.

    2003-02-01

    2MASS J and H photometry and integrated spectroscopy are employed to study the nature of the poorly populated compact concentration of stars Ruprecht 3, which was previously catalogued as an open cluster. The integrated spectrum remarkably resembles that of a moderately metal-rich globular cluster. The distribution of the object stars in the colour-magnitude diagram is compatible with that of a 1.5 +/- 0.5 Gyr open cluster or older, depending on whether the bluer stars are interpreted as turnoff stars or blue stragglers, respectively. We derive for the object a distance from the Sun dsun = 0.72 +0.04-0.03 kpc and a colour excess E(B-V) = 0.04. Although a globular cluster remnant cannot be ruled out, the integrated spectrum resemblance to that of a globular cluster probably reflects a stochastic effect owing to the few brighter stars. The structural and photometric properties of Ruprecht 3 are compatible with what would be expected for an intermediate-age open cluster remnant. Based on observations made at Complejo Astronómico El Leoncito, which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba and San Juan, Argentina.

  5. New Candidate Supernova Remnants in M31

    NASA Astrophysics Data System (ADS)

    Williams, B. F.; Schmitt, M. D.; Winkler, P. F.

    1995-05-01

    We have used pure emission-line images (deep CCD images from which a continuum image has been subtracted; see Winkler & Williams, companion paper) to search for supernova remnant (SNR) candidates in M31. The ratio of \\sii\\ lambda \\ 6724\\ to \\ha\\ is used to distinguish SNRs from \\hii\\ regions, a technique that has been used effectively in other galaxies as well as in earlier photographic surveys of M31 (D'Odorico et al 1980, A&A Supp 40, 67; Blair et al 1981, Ap J 247, 879). The extensive cooling zone typically found behind SNR shocks emits strongly in \\sii, while in photoionized material such as \\hii\\ regions most of the S is twice ionized and hence \\sii\\ is weak. SNRs almost always have \\sii/\\ha\\ ratios > 0.4\\ vs values < 0.2\\ for \\hii\\ regions. Using this criterion, we have identified 105 nebulae in M31 which are strong SNR candidates, of which 13 were previously identified by D'Odorico et al and/or Blair et al. While this number probably represents a small minorit y of the SNRs which are actually present in M31, confirmation of a substantial fraction of these would increase the population of known remnants in M31 several-fold and would make it the galaxy with the largest sample of known optical SNRs, including our own. For the cumulative number of SNRs as a function of diameter we find N(remnants that is inevitable with our coarse scale, 2'' pixel(-1) \\ with an effective resolution of only ~ 5arcsec , equivalent to 18 pc at the distance of M31. We can, however, rule out N(

  6. New supernova remnant results from radio surveys

    NASA Astrophysics Data System (ADS)

    Helfand, D. J.

    Our knowledge of the Galactic supernova remnant population is woefully incomplete A total of 231 remnants appear in the latest catalog Green 2004 whereas we expect the total population to be between 500 and 1000 Helfand et al 1989 The current discovery rate of new remnants has averaged about four per year over the past two decades In recent years a number of new Galactic plane radio surveys have been undertaken which offer the possibility of significantly increasing this discovery rate For example the VLA MAGPIS survey Helfand et al 2006 has identified fifty new remnant candidates in a 27-degree swath of Galactic longitude Unsurprisingly this high-resolution survey finds many more small-diameter remnants than past single-dish observations increasing by seven-fold the number of remnants with diameters less than 5 arcmin in this region of the Galaxy Brogan et al report 90 cm observations in this region identifying up to 35 new remnants I will review all published results on new radio remnants highlighting the impact of these discoveries on our understanding of the remnant population and noting the value of observations from the mid-infrared to TeV gamma rays in defining the Galaxy s remnant population This work is supported in part by grant AST 05-07598 from the National Science Foundation

  7. Modelling Hard Gamma-Ray Emission from Supernova Remnants

    NASA Technical Reports Server (NTRS)

    Baring, Matthew

    2000-01-01

    The observation by the CANGAROO experiment of TeV emission from SN 1006, in conjunction with several instances of non-thermal X-ray emission from supernova remnants, has led to inferences of super-TeV electrons in these extended sources. While this is sufficient to propel the theoretical community in their modelling of particle acceleration and associated radiation, the anticipated emergence in the next decade of a number of new experiments probing the TeV and sub-TeV bands provides further substantial motivation for modellers. In particular, the quest for obtaining unambiguous gamma-ray signatures of cosmic ray ion acceleration defines a "Holy Grail" for observers and theorists alike. This review summarizes theoretical developments in the prediction of MeV-TeV gamma-rays from supernova remnants over the last five years, focusing on how global properties of models can impact, and be impacted by, hard gamma-ray observational programs, thereby probing the supernova remnant environment. Properties of central consideration include the maximum energy of accelerated particles, the density of the unshocked interstellar medium, the ambient magnetic field, and the relativistic electron-to-proton ratio. Criteria for determining good candidate remnants for observability in the TeV band are identified.

  8. Modelling Hard Gamma-Ray Emission from Supernova Remnants

    NASA Technical Reports Server (NTRS)

    Baring, Matthew G.

    1999-01-01

    The observation by the CANGAROO (Collaboration of Australia and Nippon Gamma Ray Observatory at Outback) experiment of TeV emission from SN 1006, in conjunction with several instances of non-thermal X-ray emission from supernova remnants, has led to inferences of super-TeV electrons in these extended sources. While this is sufficient to propel the theoretical community in their modelling of particle acceleration and associated radiation, the anticipated emergence in the next decade of a number of new experiments probing the TeV and sub-TeV bands provides further substantial motivation for modellers. In particular, the quest for obtaining unambiguous gamma-ray signatures of cosmic ray ion acceleration defines a "Holy Grail" for observers and theorists alike. This review summarizes theoretical developments in the prediction of MeV-TeV gamma-rays from supernova remnants over the last five years, focusing on how global properties of models can impact, and be impacted by, hard gamma-ray observational programs, thereby probing the supernova remnant environment. Properties of central consideration include the maximum energy of accelerated particles, the density of the unshocked interstellar medium, the ambient magnetic field, and the relativistic electron-to-proton ratio. Criteria for determining good candidate remnants for observability in the TeV band are identified.

  9. Radio emission from supernova remnants

    NASA Astrophysics Data System (ADS)

    Dubner, Gloria; Giacani, Elsa

    2015-09-01

    The explosion of a supernova releases almost instantaneously about 10^{51} ergs of mechanic energy, changing irreversibly the physical and chemical properties of large regions in the galaxies. The stellar ejecta, the nebula resulting from the powerful shock waves, and sometimes a compact stellar remnant, constitute a supernova remnant (SNR). They can radiate their energy across the whole electromagnetic spectrum, but the great majority are radio sources. Almost 70 years after the first detection of radio emission coming from an SNR, great progress has been achieved in the comprehension of their physical characteristics and evolution. We review the present knowledge of different aspects of radio remnants, focusing on sources of the Milky Way and the Magellanic Clouds, where the SNRs can be spatially resolved. We present a brief overview of theoretical background, analyze morphology and polarization properties, and review and critically discuss different methods applied to determine the radio spectrum and distances. The consequences of the interaction between the SNR shocks and the surrounding medium are examined, including the question of whether SNRs can trigger the formation of new stars. Cases of multispectral comparison are presented. A section is devoted to reviewing recent results of radio SNRs in the Magellanic Clouds, with particular emphasis on the radio properties of SN 1987A, an ideal laboratory to investigate dynamical evolution of an SNR in near real time. The review concludes with a summary of issues on radio SNRs that deserve further study, and analysis of the prospects for future research with the latest-generation radio telescopes.

  10. Charged black hole remnants at the LHC

    NASA Astrophysics Data System (ADS)

    Alberghi, G. L.; Bellagamba, L.; Calmet, X.; Casadio, R.; Micu, O.

    2013-06-01

    We investigate possible signatures of long-lived (or stable) charged black holes at the Large Hadron Collider. In particular, we find that black hole remnants are characterised by quite low speed. Due to this fact, the charged remnants could, in some cases, be very clearly distinguished from the background events, exploiting dE/ dX measurements. We also compare the estimate energy released by such remnants with that of typical Standard Model particles, using the Bethe-Bloch formula.

  11. 16 CFR 303.13 - Sale of remnants and products made of remnants.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... ACTS OF CONGRESS RULES AND REGULATIONS UNDER THE TEXTILE FIBER PRODUCTS IDENTIFICATION ACT § 303.13... “remnants of undetermined fiber content.” (3) Where textile fiber products are made of such remnants,...

  12. 27 CFR 19.359 - Remnants.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., Packaging, and Removal of Products § 19.359 Remnants. When at the end of a bottling run fewer bottles remain than the number necessary to fill a case, the remaining bottles may be placed in a case marked as a... remnant bottles may later be used to complete the filling of a case, or may be used for another...

  13. Optical supernova remnant observations from Skinakas Observatory

    NASA Astrophysics Data System (ADS)

    Mavromatakis, F.; Papamastorakis, J.; Ventura, J.; Boumis, P.

    High energy studies of supernova remnants provide direct insight into major properties of these objects. Morphological and spectral studies of remnants in X-rays allow us to estimate parameters like the age of the remnant, the explosion energy and the ambient interstellar density. Optical studies of supernova remnants focus on the interaction of the primary blast wave with dense "clouds" found in the insterstellar medium. Optical observations of individual remnants performed at Skinakas Observatory in Crete, Greece consist of flux calibrated wide field CCD images taken with the 0.3 m telescope and absolute flux calibrated long-slit spectra obtained with the 1.3 m telescope. The site conditions and the unique capabilities of a small telescope equipped with a CCD camera allowed us to perform high quality deep observations leading to the discovery of optical emission from several remnants for the first time. We present results on the known supernova remnants G65.3+5.7, G82.2+5.3, G114.3+0.3 as well as current results on previously unknown filamentary structures and probable candidate remnants. Typical densities of the interstellar "clouds" are of the order of a few atoms per cm3 , and the shock velocities are found in the range of 90-140 km s-1 . The optical spectra further suggest the presence of moderate magnetic fields of several μG.

  14. A search for stellar remnants of supernovae

    NASA Technical Reports Server (NTRS)

    Fesen, R. A.; Kirshner, R. P.; Winkler, P. F., Jr.

    1979-01-01

    The slitless spectra of the stars in the central regions of six galactic supernova remnants Cas A, Kepler, Tycho, SN 1006, RCW 86, and the Cygnus Loop were obtained with the prime focus transmission gratings at the 4M telescopes on Kitt Peak and Cerro Tololo. It was found that no stellar remnant with an unusually blue or peculiar spectrum is present in any of the remnants down to the limit of m sub pg of 18.5. Except for the Cygnus Loop, the area searched in each remnant is large enough that objects with transverse velocities of 1000 km/s would be well within the field. The results are also compared with a computation of emission from gas near a neutron star and with the unpulsed emission from the Crab pulsar; in both cases upper limits were set which place constraints on a possible condensed stellar remnant.

  15. Supernovae, young remnants, and nucleosynthesis

    NASA Technical Reports Server (NTRS)

    Kirshner, R. P.

    1982-01-01

    Chemical abundance data from extragalactic supernovae and from supernova remnants (SNR) less than 1000 yrs old are employed to show that nuclear burning beyond helium synthesis actually occurs. Supernova (SN) are classified into types I or II, having no hydrogen lines or featuring hydrogen lines, respectively. The SN I's have been observed as having a preponderance of Fe lines, and emitting from a source at around 12,000 K with a center continuum of approximately 10 AU. Decay chains which could account for detected luminosities and spectra are presented, noting a good fit of Fe II spectrum with observed SN spectra. SNR pass through younger and older stages, going from the outpouring of material to diffusion in the interstellar medium. Expanding flocculi from young SNR show oxygen abundances as well as lines from sulfur, calcium, and argon, with a corresponding necessity of an explosive source of 15 solar masses.

  16. Effect of Polycalcium, a mixture of Polycan and calcium lactate-gluconate in a 1:9 weight ratio, on rats with surgery-induced osteoarthritis

    PubMed Central

    CHOI, JAE-SUK; SHIN, HYUN-SOO; KIM, KI YOUNG; KU, SAE KWANG; CHOI, IN SOON; KIM, JOO WAN

    2015-01-01

    In the present study, the beneficial and synergistic effects of Polycalcium, a mixture of Polycan and calcium (Ca) lactate-gluconate in a 1:9 weight ratio, on a rat model of osteoarthritis (OA) were explored. Polycalcium (50, 100 and 200 mg/kg) was administered orally once per day for 28 days from 1 week after the OA-modeling surgery. Diclofenac sodium (2 mg/kg) was administered as a reference drug. Following the OA surgery, increases in the maximum extension angles, edematous changes in knee and capsule thickness, reductions in chondrocyte proliferation and cartilage glycosaminoglycan (GAG) levels, as well as changes in cartilage degeneration were observed. However, these OA-related symptoms were inhibited after 28 days of continuous oral treatment with Polycalcium. Anti-OA effects, including the induction of chondrocyte proliferation, were detected in the Polycalcium-treated rats and were more favorable compared with those in rats treated with Polycan or Ca lactate-gluconate alone (100 mg). Therefore, a mixture of Polycan and Ca lactate-gluconate was demonstrated to have beneficial synergistic effects on OA. PMID:26136893

  17. Fan Performance From Duct Rake Instrumentation on a 1.294 Pressure Ratio, 725 ft/sec Tip Speed Turbofan Simulator Using Vaned Passage Casing Treatment

    NASA Technical Reports Server (NTRS)

    Fite, E. Brian

    2006-01-01

    A 1.294 pressure ratio, 725 ft/sec tip speed, variable pitch low noise fan was designed and tested in the NASA Glenn 9- by 15-foot Wind Tunnel. The design included a casing treatment that used recirculation to extend the fan stall line and provide an acceptable operating range. Overall aerodynamic experimental results are presented for this low tip speed, low noise fan without casing treatment as well as using several variants of the casing treatment that moved the air extraction and insertion axial locations. Measurements were made to assess effects on performance, operability, and noise. An unusual instability was discovered near the design operating line and is documented in the fan operating range. Measurements were made to compare stall margin improvements as well as measure the performance impact of the casing treatments. Experimental results in the presence of simulated inlet distortion, via screens, are presented for the baseline and recirculation casing treatment configurations. Estimates are made for the quantity of recirculation weight flow based on limited instrumentation in the recirculation system along with discussion of results and conclusions

  18. Acoustic testing of a 1.5 pressure ratio low tip speed fan with a serrated rotor (QEP fan B scale model). [reduction of engine noise

    NASA Technical Reports Server (NTRS)

    Kazin, S. B.; Paas, J. E.; Minzner, W. R.

    1973-01-01

    A scale model of the bypass flow region of a 1.5 pressure ratio, single stage, low tip speed fan was tested with a serrated rotor leading edge to determine its effects on noise generation. The serrated rotor was produced by cutting teeth into the leading edge of the nominal rotor blades. The effects of speed and exhaust nozzle area on the scale models noise characteristics were investigated with both the nominal rotor and serrated rotor. Acoustic results indicate the serrations reduced front quadrant PNL's at takeoff power. In particular, the 200 foot (61.0 m) sideline noise was reduced from 3 to 4 PNdb at 40 deg for nominal and large nozzle operation. However, the rear quadrant maximum sideline PNL's were increased 1.5 to 3 PNdb at approach thust and up to 2 PNdb at takeoff thust with these serrated rotor blades. The configuration with the serrated rotor produced the lowest maximum 200 foot (61.0 m) sideline PNL for any given thust when the large nozzle (116% of design area) was employed.

  19. Acoustic and aerodynamic performance of a 1.83-meter (6-ft) diameter 1.25-pressure-ratio fan (QF-8)

    NASA Technical Reports Server (NTRS)

    Woodward, R. P.; Lucas, J. G.

    1976-01-01

    A 1.25-pressure-ratio 1.83-meter (6-ft) tip diameter experimental fan stage with characteristics suitable for engine application on STOL aircraft was tested for acoustic and aerodynamic performance. The design incorporated proven features for low noise, including absence of inlet guide vanes, low rotor blade tip speed, low aerodynamic blade loading, and long axial spacing between the rotor and stator blade rows. The fan was operated with five exhaust nozzle areas. The stage noise levels generally increased with a decrease in nozzle area. Separation of the acoustic one-third octave results into broadband and pure-tone components showed the broadband noise to be greater than the corresponding pure-tone components. The sideline perceived noise was highest in the rear quadrants. The acoustic results of QF-8 were compared with those of two similar STOL application fans in the test series. The QF-8 had somewhat higher relative noise levels than those of the other two fans. The aerodynamic results of QF-8 and the other two fans were compared with corresponding results from 50.8-cm (20-in.) diam scale models of these fans and design values. Although the results for the full-scale and scale models of the other two fans were in reasonable agreement for each design, the full-scale fan QF-8 results showed poor performance compared with corresponding model results and design expectations. Facility effects of the full-scale fan QF-8 installation were considered in analyzing this discrepancy.

  20. Acoustic testing of a 1.5 pressure ratio low tip speed fan with casing tip bleed (QEP Fan B scale model)

    NASA Technical Reports Server (NTRS)

    Kazin, S. B.; Minzner, W. R.; Paas, J. E.

    1971-01-01

    A scale model of the bypass flow region of a 1.5 pressure ratio, single stage, low tip speed fan was tested with a rotor tip casing bleed slot to determine its effects on noise generation. The bleed slot was located 1/2 inch (1.3 cm) upstream of the rotor leading edge and was configured to be a continuous opening around the circumference. The bleed manifold system was operated over a range of bleed rates corresponding to as much as 6% of the fan flow at approach thrust and 4.25% of the fan flow at takeoff thrust. Acoustic results indicate that a bleed rate of 4% of the fan flow reduces the fan maximum approach 200 foot (61.0 m) sideline PNL 0.5 PNdB and the corresponding takeoff thrust noise 1.1 PNdB below the level with zero bleed. However, comparison of the standard casing (no bleed slot) and the slotted bleed casing with zero bleed shows that the bleed slot itself caused a noise increase.

  1. Performance of a 1.15-pressure-ratio axial-flow fan stage with a blade tip solidity of 0.5

    NASA Technical Reports Server (NTRS)

    Osborn, W. M.; Steinke, R. J.

    1974-01-01

    The overall and blade-element performance of a low-solidity, low-pressure-ratio, low-tip-speed fan stage is presented over the stable operating range at rotative speeds from 90 to 120 percent of design speed. At design speed a stage peak efficiency of 0.836 was obtained at a weight flow of 30.27 kilograms per second and a pressure ratio of 1.111. The pressure ratio was less than design pressure ratio, and the design energy input into the rotor was not achieved. A mismatch of the rotor and stator blade elements resulted due to the lower than design pressure ratio of the rotor.

  2. Optical supernova remnant observations from Skinakas Observatory

    NASA Astrophysics Data System (ADS)

    Mavromatakis, F.; Papamastorakis, J.; Ventura, J.; Boumis, P.

    High energy studies of supernova remnants provide direct insight into major properties of these objects. Morphological and spectral studies of remnants in X-rays allow us to estimate parameters like the age of the remnant, the explosion energy and the ambient interstellar density. Optical studies of supernova remnants focus on the interaction of the primary blast wave with dense "clouds" found in the interstellar medium. Optical observations of individual remnants performed at Skinakas Observatory in Crete, Greece consist of flux calibrated wide field CCD images taken with the 0.3 m telescope and absolute flux calibrated long-slit spectra obtained with the 1.3 m telescope. The site conditions and the unique capabilities of a small telescope equipped with a CCD camera allowed us to perform high quality deep observations leading to the discovery of optical emission from several remnants for the first time. We present results on the known supernova remnants G73.9+0.9, G82.2+5.3 as well as current results on previously unknown filamentary structures. Typical densities of the interstellar "clouds" are of the order of a few atoms per cm 3, and the shock velocities are found in the range of 90-140 km s -1. The optical spectra further suggest the presence of moderate magnetic fields.

  3. Further analysis of LDEF FRECOPA micrometeroid remnants

    NASA Technical Reports Server (NTRS)

    Borg, J.; Bunch, T. E.; Radicatidibrozolo, Filippo

    1992-01-01

    Experiments dedicated to the detection of interplanetary dust particles (IDP's) were exposed within the FRECOPA payload, installed on the face of the LDEF directly opposed to the velocity vector (west facing direction, location B3). We were mainly interested in the analysis of hypervelocity impact features of sizes less than or = 10 microns, found in thick Al targets devoted to the research of impact features. In the 15 craters found in the scanned area (approximately 4 sq. cm), the chemical analysis suggests an extraterrestrial origin for the impacting particles. The main elements we identified are usually refered to as chondrite elements: Na, Mg, Si, S, Ca, and Fe are found in various proportions, intrinsic Al being masked by the Al target; we notice a strong depletion in Ni, never observed in our samples. Furthermore, C and O are present in 90 percent of the cases; the C/O peak height ratio varies from 0.1 to 3. Impactor simulations by light gas gun hypervelocity impact experiments have shown that meaningful biogenic element and compound information maybe obtained from IDP residues below impacts of critical velocities, that are less than or = 4 km/sec for particles larger than 100 microns in diameter. Our results obtained for the smaller size fraction IDP's suggest that at such sizes, the critical velocity could be higher by a factor of 2 or 3, as chemical analysis of the remnants were possible in all the identified impact craters, performed on targets possibly hit at velocities greater than or = 7.5 km/s, which is the spacecraft velocity. These samples are now subjected to an imagery and analytical protocol that includes FESEM (field emission scanning electron microscopy) and LIMS (laser ionization mass spectrometry). The LIMS analyses were performed using the LIMA-ZA instrument. Results are presented, clearly indicating that such small events show crater features analogous to what is observed at larger sizes; our first analytical results, obtained for 2 events

  4. Progenitor's Signatures in Type Ia Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Chiotellis, A.; Kosenko, D.; Schure, K. M.; Vink, J.

    2013-01-01

    The remnants of Type Ia supernovae (SNe Ia) can provide important clues about their progenitor histories. We discuss two well-observed supernova remnants (SNRs) that are believed to have resulted from SNe Ia, and use various tools to shed light on the possible progenitor histories. We find that Kepler's SNR is consistent with a symbiotic binary progenitor consisting of a white dwarf and an AGB star. Our hydrosimulations can reproduce the observed kinematic and morphological properties. For Tycho's remnant we use the characteristics of the X-ray spectrum and kinematics to show that the ejecta has likely interacted with dense circumstellar gas.

  5. Dynamical Evolution of Supernova Remnants Breaking Through Molecular Clouds

    NASA Astrophysics Data System (ADS)

    Cho, Wankee; Kim, Jongsoo; Koo, Bon-Chul

    2015-04-01

    We carry out three-dimensional hydrodynamic simulations of the supernova remnants (SNRs) produced inside molecular clouds (MCs) near their surface using the HLL code tep{har83}. We explore the dynamical evolution and the X-ray morphology of SNRs after breaking through the MC surface for ranges of the explosion depths below the surface and the density ratios of the clouds to the intercloud media (ICM). We find that if an SNR breaks out through an MC surface in its Sedov stage, the outermost dense shell of the remnant is divided into several layers. The divided layers are subject to the Rayleigh-Taylor instability and fragmented. On the other hand, if an SNR breaks through an MC after the remnant enters the snowplow phase, the radiative shell is not divided to layers. We also compare the predictions of previous analytic solutions for the expansion of SNRs in stratified media with our one-dimensional simulations. Moreover, we produce synthetic X-ray surface brightness in order to research the center-bright X-ray morphology shown in thermal composite SNRs. In the late stages, a breakout SNR shows the center-bright X-ray morphology inside an MC in our results. We apply our model to the observational results of the X-ray morphology of the thermal composite SNR 3C 391.

  6. The First Reported Infrared Emission from the SN1006 Remnant

    NASA Technical Reports Server (NTRS)

    Winkler, P. Frank; Williams, Brian J.; Blair, William P.; Borkowski, Kazimierz J.; Ghavamian, Parviz; Long, Knox S.; Raymond, John C.; Reynolds, Stephen P.

    2012-01-01

    We report results of infrared imaging and spectroscopic observations of the SN 1006 remnant, carried out with the Spitzer Space Telescope. The 24 m image from MIPS clearly shows faint filamentary emission along the northwest rim of the remnant shell, nearly coincident with the Balmer filaments that delineate the present position of the expanding shock. The 24 m emission traces the Balmer filaments almost perfectly, but lies a few arcsec within, indicating an origin in interstellar dust heated by the shock. Subsequent decline in the IR behind the shock is presumably due largely to grain destruction through sputtering. The emission drops far more rapidly than current models predict, however, even for a higher proportion of small grains than would be found closer to the Galactic plane. The rapid drop may result in part from a grain density that has always been lowera relic effect from an earlier epoch when the shock was encountering a lower densitybut higher grain destruction rates still seem to be required. Spectra from three positions along the NW filament from the IRS instrument all show only a featureless continuum, consistent with thermal emission from warm dust. The dust-to-gas mass ratio in the pre-shock interstellar medium is lower than that expected for the Galactic ISM-as has also been observed in the analysis of IR emission from other SNRs but whose cause remains unclear. As with other SNIa remnants, SN1006 shows no evidence for dust grain formation in the supernova ejecta.

  7. Runaway Stars in Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Pannicke, Anna; Neuhaeuser, Ralph; Dinçel, Baha

    2016-07-01

    Half of all stars and in particular 70 % of the massive stars are a part of a multiple system. A possible development for the system after the core collapse supernova (SN) of the more massive component is as follows: The binary is disrupted by the SN. The formed neutron star is ejected by the SN kick whereas the companion star either remains within the system and is gravitationally bounded to the neutron star, or is ejected with a spatial velocity comparable to its former orbital velocity (up to 500 km/s). Such stars with a large peculiar space velocity are called runaway stars. We present our observational results of the supernova remnants (SNRs) G184.6-5.8, G74.0-8.5 and G119.5+10.2. The focus of this project lies on the detection of low mass runaway stars. We analyze the spectra of a number of candidates and discuss their possibility of being the former companions of the SN progenitor stars. The spectra were obtained with INT in Tenerife, Calar Alto Astronomical Observatory and the University Observatory Jena. Also we investigate the field stars in the neighborhood of the SNRs G74.0-8.5 and G119.5+10.2 and calculate more precise distances for these SNRs.

  8. Isaac's Remnants; Tropical Storms Kirk, Michael

    NASA Video Gallery

    Animation of GOES-13 satellite observations from Sept. 1-4, 2012, showing Isaac's remnants move from the central to eastern U.S., Tropical Storm Leslie nearing Bermuda, Kirk fading in the No. Atlan...

  9. Congenital esophageal stenosis owing to tracheobronchial remnants

    PubMed Central

    Rebelo, Priscila Guyt; Ormonde, João Victor C.; Ormonde, João Baptista C.

    2013-01-01

    OBJECTIVE To emphasize the need of an accurate diagnosis of congenital esophageal stenosis due to tracheobronchial remnants, since its treatment differs from other types of congenital narrowing. CASE DESCRIPTION Four cases of lower congenital esophageal stenosis due to tracheobronchial remnants, whose definitive diagnosis was made by histopathology. Except for the last case, in which a concomitant anti-reflux surgery was not performed, all had a favorable outcome after resection and anastomosis of the esophagus. COMMENTS The congenital esophageal stenosis is an intrinsic narrowing of the organâ€(tm)s wall associated with its structural malformation. The condition can be caused by tracheobronchial remnants, fibromuscular stenosis or membranous diaphragm and the first symptom is dysphagia after the introduction of solid food in the diet. The first-choice treatment to tracheobronchial remnants cases is the surgical resection and end-to-end anastomosis of the esophagus. PMID:24142326

  10. X-ray imaging - Supernova remnants

    NASA Technical Reports Server (NTRS)

    Helfand, D. J.

    1981-01-01

    Consideration is given to imaging observations of supernova remnants (SNRs) obtained during the first year of the Einstein Observatory's operation. Inferences are drawn regarding models for stellar explosions, remnant evolution, neutron star formation and the interstellar medium. Because the X-ray emission traces the expanding shock boundary and dominates the radiative energy losses of an SNR over much of its lifetime, it can provide data on the possible collapsed remnants of the explosion, such as neutron stars and/or black holes. X-ray emission also allows a supernova shock to be used as a probe of interstellar medium structure. The imaging instrument aboard the Einstein satellite has been used to observe over 30 known Galactic remnants, and a similar number of objects in other galaxies, in the 0.15-4.5 keV band.

  11. Fermi Proves Supernova Remnants Make Cosmic Rays

    NASA Video Gallery

    The husks of exploded stars produce some of the fastest particles in the cosmos. New findings by NASA's Fermi show that two supernova remnants accelerate protons to near the speed of light. The pro...

  12. X-ray spectra of supernova remnants

    NASA Technical Reports Server (NTRS)

    Szymkowiak, A. E.

    1985-01-01

    X-ray spectra were obtained from fields in three supernova remnants with the solid state spectrometer of the HEAO 2 satellite. These spectra, which contain lines from K-shell transitions of several abundant elements with atomic numbers between 10 and 22, were compared with various models, including some of spectra that would be produced by adiabatic phase remnants when the time-dependence of the ionization is considered.

  13. Observation of Crab-Like Supernova Remnants

    NASA Technical Reports Server (NTRS)

    Seward, Frederick D.

    2001-01-01

    The purpose of this program was to observe the supernova remnants 3C58 and G21.5-0.9 and to search for pulsed emission. If a pulsar were to be found, the period derivative and inferred magnetic field would have extreme values if pulsar evolution had followed the standard model. If this is not the case, the standard model must be revised. We also sought to obtain very accurate measurement of the synchrotron emission spectrum of each remnant.

  14. Constraining the Cosmic-ray Acceleration Efficiency in the Supernova Remnant IC 443

    NASA Astrophysics Data System (ADS)

    Ritchey, Adam Michael; Federman, Steven R.; Jenkins, Edward B.; Caprioli, Damiano; Wallerstein, George

    2015-08-01

    Supernova remnants are widely believed to be the sources responsible for the acceleration of Galactic cosmic rays. Over the last several years, observations made with the Fermi Gamma-ray Space Telescope have confirmed that cosmic-ray nuclei are indeed accelerated in some supernova remnants, including IC 443, which is a prototype for supernova remnants interacting with molecular clouds. However, the details concerning the particle acceleration processes in middle aged remnants are not fully understood, in part because the basic model parameters are not always well constrained. Here, we present preliminary results of a Hubble Space Telescope investigation into the physical conditions in diffuse molecular gas interacting with IC 443. We examine high-resolution FUV spectra of two stars, one that probes the interior region of the supernova remnant, and the other located just outside the visible edge of IC 443. With this arrangement, we are able to evaluate the densities and temperatures in neutral gas clumps positioned both ahead of and behind the supernova shock front. From these measurements, we obtain estimates for the post-shock temperature and the shock velocity in the interclump medium. We discuss the efficacy of these results for constraining both the age of IC 443, and also the cosmic-ray acceleration efficiency. Finally, we report the first detection of boron in a supernova remnant, and discuss the usefulness of the B/O ratio in constraining the cosmic-ray content of the gas interacting with IC 443.

  15. The combined effects of remnant vegetation and tree planting on farmland birds.

    PubMed

    Cunningham, Ross B; Lindenmayer, David B; Crane, Mason; Michael, Damian; MacGregor, Christopher; Montague-Drake, Rebecca; Fischer, Joern

    2008-06-01

    Biodiversity conservation on agricultural land is a major issue worldwide. We estimated separate and joint effects of remnant native woodland vegetation and recent tree plantings on birds on farms (approximately 500-1000 ha) in the heavily cleared wheat and sheep belt of southern Australia. Much of the variation (>70%) in bird responses was explained by 3 factors: remnant native-vegetation attributes (native grassland, scattered paddock trees, patches of remnant native woodland); presence or absence of planted native trees; and the size and shape of tree plantings. In terms of the number of species, remnant native vegetation was more important than tree planting, in a 3:1 ratio, approximately. Farms with high values for remnant native vegetation were those most likely to support declining or vulnerable species, although some individual species of conservation concern occurred on farms with large plantings. Farm management for improved bird conservation should account for the cumulative and complementary contributions of many components of remnant native-vegetation cover (e.g., scattered paddock trees and fallen timber) as well as areas of restored native vegetation. PMID:18477028

  16. TYPING SUPERNOVA REMNANTS USING X-RAY LINE EMISSION MORPHOLOGIES

    SciTech Connect

    Lopez, L. A.; Ramirez-Ruiz, E.; Badenes, C.; Huppenkothen, D.; Jeltema, T. E.

    2009-11-20

    We present a new observational method to type the explosions of young supernova remnants (SNRs). By measuring the morphology of the Chandra X-ray line emission in 17 Galactic and Large Magellanic Cloud SNRs with a multipole expansion analysis (using power ratios), we find that the core-collapse SNRs are statistically more asymmetric than the Type Ia SNRs. We show that the two classes of supernovae can be separated naturally using this technique because X-ray line morphologies reflect the distinct explosion mechanisms and structure of the circumstellar material. These findings are consistent with recent spectropolarimetry results showing that core-collapse supernovae explosions are intrinsically more asymmetric.

  17. High-energy antiprotons from old supernova remnants.

    PubMed

    Blasi, Pasquale; Serpico, Pasquale D

    2009-08-21

    A recently proposed model explains the rise in energy of the positron fraction measured by the PAMELA satellite in terms of hadronic production of positrons in aged supernova remnants, and acceleration therein. Here we present a preliminary calculation of the antiproton flux produced by the same mechanism. While the model is consistent with present data, a rise of the antiproton to proton ratio is predicted at high energy, which strikingly distinguishes this scenario from other astrophysical explanations of the positron fraction (such as pulsars). We briefly discuss important implications for dark matter searches via antimatter. PMID:19792708

  18. Supernova Remnant in 3-D

    NASA Technical Reports Server (NTRS)

    2009-01-01

    [figure removed for brevity, see original site] Click on the image for the movie

    For the first time, a multiwavelength three-dimensional reconstruction of a supernova remnant has been created. This stunning visualization of Cassiopeia A, or Cas A, the result of an explosion approximately 330 years ago, uses data from several telescopes: X-ray data from NASA's Chandra X-ray Observatory, infrared data from NASA's Spitzer Space Telescope and optical data from the National Optical Astronomy Observatory 4-meter telescope at Kitt Peak, Ariz., and the Michigan-Dartmouth-MIT 2.4-meter telescope, also at Kitt Peak. In this visualization, the green region is mostly iron observed in X-rays. The yellow region is a combination of argon and silicon seen in X-rays, optical, and infrared including jets of silicon plus outer debris seen in the optical. The red region is cold debris seen in the infrared. Finally, the blue reveals the outer blast wave, most prominently detected in X-rays.

    Most of the material shown in this visualization is debris from the explosion that has been heated by a shock moving inwards. The red material interior to the yellow/orange ring has not yet encountered the inward moving shock and so has not yet been heated. These unshocked debris were known to exist because they absorb background radio light, but they were only recently discovered in infrared emission with Spitzer. The blue region is composed of gas surrounding the explosion that was heated when it was struck by the outgoing blast wave, as clearly seen in Chandra images.

    To create this visualization, scientists took advantage of both a previously known phenomenon the Doppler effect and a new technology that bridges astronomy and medicine. When elements created inside a supernova, such as iron, silicon and argon, are heated they emit light at certain wavelengths. Material moving towards the observer will have shorter wavelengths and material moving away will have longer

  19. Supernova Remnant in 3-D

    NASA Technical Reports Server (NTRS)

    2009-01-01

    [figure removed for brevity, see original site] Click on the image for the movie

    For the first time, a multiwavelength three-dimensional reconstruction of a supernova remnant has been created. This stunning visualization of Cassiopeia A, or Cas A, the result of an explosion approximately 330 years ago, uses data from several telescopes: X-ray data from NASA's Chandra X-ray Observatory, infrared data from NASA's Spitzer Space Telescope and optical data from the National Optical Astronomy Observatory 4-meter telescope at Kitt Peak, Ariz., and the Michigan-Dartmouth-MIT 2.4-meter telescope, also at Kitt Peak. In this visualization, the green region is mostly iron observed in X-rays. The yellow region is a combination of argon and silicon seen in X-rays, optical, and infrared including jets of silicon plus outer debris seen in the optical. The red region is cold debris seen in the infrared. Finally, the blue reveals the outer blast wave, most prominently detected in X-rays.

    Most of the material shown in this visualization is debris from the explosion that has been heated by a shock moving inwards. The red material interior to the yellow/orange ring has not yet encountered the inward moving shock and so has not yet been heated. These unshocked debris were known to exist because they absorb background radio light, but they were only recently discovered in infrared emission with Spitzer. The blue region is composed of gas surrounding the explosion that was heated when it was struck by the outgoing blast wave, as clearly seen in Chandra images.

    To create this visualization, scientists took advantage of both a previously known phenomenon the Doppler effect and a new technology that bridges astronomy and medicine. When elements created inside a supernova, such as iron, silicon and argon, are heated they emit light at certain wavelengths. Material moving towards the observer will have shorter wavelengths and material moving away will have longer

  20. The ratio of FoxA1 to FoxA2 in lung adenocarcinoma is regulated by LncRNA HOTAIR and chromatin remodeling factor LSH

    PubMed Central

    Wang, Ranran; Shi, Ying; Chen, Ling; Jiang, Yiqun; Mao, Chao; Yan, Bin; Liu, Shuang; Shan, Bin; Tao, Yongguang; Wang, Xiang

    2015-01-01

    The lncRNA HOTAIR is a critical regulator of cancer progression. Chromatin remodeling factor LSH is critical for normal development of plants and mammals. However, the underlying mechanisms causing this in cancer are not entirely clear. The functional diversification of the FOXA1 and FOXA2 contributes to the target genes during evolution and carcinogenesis. Little is known about the ratio of FOXA1 to FOXA2 in cancer. We here found that both HOTAIR and LSH overexpression was significantly correlated with poor survival in patients with lung adenocarcinoma cancer (ADC). Also, the ratio of FOXA1 and FOXA2 is linked with poor survival in patients with lung ADC. HOTAIR regulates the ratio of FOXA1 to FOXA2 and migration and invasion. HOTAIR and the ratio of FOXA1 to FOXA2 are negatively correlated. HOTAIR knockdown inhibits migration and invasion. HOTAIR is associated with LSH, and this association linked with the binding of LSH in the promoter of FOXA1, not FOXA2. Targeted inhibition of HOTAIR suppresses the migratory and invasive properties. These data suggest that HOTAIR is an important mediator of the ratio of FOXA1 and FOXA2 and LSH involves in, and suggest that HOTAIR inhibition may represent a promising therapeutic option for suppressing lung ADC progression. PMID:26658322

  1. Overall and blade-element performance of a 1.20-pressure-ratio fan stage at design blade setting angle

    NASA Technical Reports Server (NTRS)

    Lewis, G. W., Jr.; Tysl, E. R.

    1974-01-01

    A 51-cm-diam. model of a short-haul fan stage was tested. Surveys of the air flow conditions ahead of the rotor, between the rotor and stator, and behind the stator were made over the stable operating range of the stage. At the design speed of 213.3 m/sec and weight flow of 26.7 kg/sec, the stage pressure ratio and efficiency are 1.18 and 0.87, respectively. The rotor peak efficiency of 0.92 occurred at flow rate of 30.5 kg/sec. Peak stage efficiency of 0.09 was obtained at 110 percent speed at a pressure ratio of 1.218 and a weight flow of 30.2 kg/sec. Maximum stage pressure ratio is 1.269 at 120 percent speed.

  2. Investigation of the Nebular Remnants of Novae

    NASA Astrophysics Data System (ADS)

    Ribeiro, Valério A. R. M.

    2011-01-01

    spectroscopy, using a combination of second generation spectrograph on the Liverpool Telescope and those of more established observatories, and X-ray observations were compared to determine that the emergence of the He II 4686Å line is related to the emergence of the super-soft source (SSS) phase in the X-ray. This could be a useful tool as a trigger for future X-ray observations. The SSS phase is an important phase for observations because it samples the continued extensive nuclear burning on the surface of the white dwarf following outburst. Morpho-kinematical modelling suggested that the morphology of the remnant was that of a dumbbell with a ratio between the major to minor axis of 4:1 with an inclination of 58+6-7 degrees and the maximum expansion velocity Vexp = 2800±200 km s-1. Future enhancements to the modelling code are suggested. Furthermore, the results given here present sufficient scientific motivation to justify for example a renewed program of Hubble Space Telescope observations of nova remnants.

  3. Structure of merger remnants. 4: Isophotal shapes

    NASA Technical Reports Server (NTRS)

    Heyl, Jeremy S.; Hernquist, Lars; Spergel, David N.

    1994-01-01

    This paper examines the shapes of isophotes of galaxy merger remnants. More specifically, we perform a series of numerical experiments to study galaxy mergers. The simulations explore a variety of encounter geometries, types of progenitor galaxies, and particle numbers. We 'observe' each of the remnants from 64 viewpoints to estimate how the isophotal shapes vary with the orientation of the remnant. Also, by comparing the results from the various simulations, we learn how encounter geometry and the structure of the progenitors can affect the shape of the remnants. The encounter geometry, the structure of the progenitors, and the orientation of the remnant play deciding roles in the shape of the 'observed' isophotes, so much so that these simulated merger remnants have both 'boxy' and 'disky' isophotes and ellipticities ranging from E0 to E7. Thus, the shapes seen in our merger simulation remnants span a similar range to observed isophotal shapes of real galaxies. Furthermore, to estimate the errors in this analysis, we introduce the statistical bootstrap. Bootstrapping is used rather widely in observational astronomy when dealing with small samples; however, its use is practically unheard of for tackling theoretical problems. We believe that bootstrapping can be extremely useful for dealing with the small samples found in numerical simulations; therefore, we present the rudiments and basis of the technique with emphasis on its use in N-body calculations. Also, by comparing the errors for the smaller simulations with those of the larger ones, we speculate on the number of particles required to accurately explore isophotal shapes in simulations.

  4. Radioiodine Remnant Ablation: A Critical Review

    PubMed Central

    Bal, Chandra Sekhar; Padhy, Ajit Kumar

    2015-01-01

    Radioiodine remnant ablation (RRA) is considered a safe and effective method for eliminating residual thyroid tissue, as well as microscopic disease if at all present in thyroid bed following thyroidectomy. The rationale of RRA is that in the absence of thyroid tissue, serum thyroglobulin (Tg) measurement can be used as an excellent tumor marker. Other considerations are like the presence of significant remnant thyroid tissue makes detection and treatment of nodal or distant metastases difficult. Rarely, microscopic disease in the thyroid bed if not ablated, in the future, could be a source of anaplastic transformation. On the other hand, microscopic tumor emboli in distant sites could be the cause of distant metastasis too. The ablation of remnant tissue would in all probability eliminate these theoretical risks. It may be noted that all these are unproven contentious issues except postablation serum Tg estimation that could be a good tumor marker for detecting early biochemical recurrence in long-term follow-up strategy. Radioactive iodine is administered as a form of “adjuvant therapy” for remnant ablation. There have been several reports with regard to the administered dose for remnant ablation. The first report of a prospective randomized clinical trial was published from India by a prospective randomized study conducted at the All India Institute of Medical Sciences, New Delhi in the year 1996. The study reported that increasing the empirical 131I initial dose to more than 50 mCi results in plateauing of the dose-response curve and thus, conventional high-dose remnant ablation needs critical evaluation. Recently, two important studies were published: One from French group and the other from UK on a similar line. Interestingly, all three studies conducted in three different geographical regions of the world showed exactly similar conclusion. The new era of low-dose remnant ablation has taken a firm scientific footing across the continents. PMID:26420983

  5. Observations of young core collapse supernova remnants

    NASA Astrophysics Data System (ADS)

    Tziamtzis, Anestis

    Studies of young remnants offer an opportunity to test theoretical models of stellar evolution, explosion models and nucleosynthesis, as well as our understanding of the compact objects in the centre of the exploded stars. The first part of the thesis involves observations of the Crab nebula. We have used photometric and spectroscopic observations to search for a faint halo around the visible nebula, that could carry the missing mass and kinetic energy of the nebula. No halo was found. In the photometric data due to psf contamination, and in the spectroscopic no fast velocity components were present. We have also used optical and IR photometry to check for variation in the emissivity and dynamic structure of the Crab pulsar wind nebula (PWN), to try to understand the nature of plerionic PWNe. There, we measured flux variations up to 20% in the IR and also shifting of the wisps with velocities up to 0.2c. We also showed that the nearby red knot moves in tandem with the Crab pulsar. The second part of the thesis, deals with photometric & spectroscopic observations of SN 1987A in the LMC. The aim of the project was to monitor the evolution of the outer rings (ORs) of SN 1987A. The fading of the ORs is consistent with recombination and cooling after the initial flash ionization by the supernova. From the spectroscopic data we measured the density and temperature in the ORs where we found temperatures of ~ 12,000 K for the [N II] gas, and ~ 25,000 K for the [O III]. Finally, from the [O II], and [S II] ratios we estimated electron densities of ~ 1,000 cm-3 and ~ 2,500 cm-3, respectively. From the evolution of Hα, we argue that the highest density in the ORs could be 5,000 cm-3.

  6. Thermal-solutal capillary-buoyancy flow of a low Prandtl number binary mixture with a -1 capillary ratio in an annular pool

    NASA Astrophysics Data System (ADS)

    Yu, Jia-Jia; Wu, Chun-Mei; Li, You-Rong; Chen, Jie-Chao

    2016-08-01

    A series of three-dimensional numerical simulations on thermal-solutal capillary-buoyancy flow in an annular pool were carried out. The pool was filled with silicon-germanium melt with an initial silicon mass fraction of 1.99%. The Prandtl number and the Lewis number of the working fluid are 6.37 × 10-3 and 2197.8, respectively. Both the radial temperature gradient and the solute concentration gradient were applied to the annular pool. The capillary ratio was assumed to be -1, which means that the solutal and thermal capillary effects were equal and opposite. Results show that the thermal-solutal capillary-buoyancy flow always occurs at this special case with the capillary ratio of -1, and even in a shallow annular pool with an aspect ratio of 0.05. With the increase of the thermal Marangoni number, four kinds of flow patterns appear orderly, including concentric rolls, petal-like, spoke, and rosebud-like patterns. These flow patterns are strongly influenced by the local interaction between the solutal and thermal capillary effects and the vertical solute concentration gradient near the outer cylinder. A small vortex driven by the dominant solutal capillary effect emerges near the inner cylinder, which is different from the flow pattern in a pure fluid. In addition, the critical thermal Marangoni number of the initial three-dimensional flow decreases with the increase of the aspect ratio of the annular pool.

  7. Multi-frequency study of supernova remnants in the Large Magellanic Cloud. Confirmation of the supernova remnant status of DEM L205

    NASA Astrophysics Data System (ADS)

    Maggi, P.; Haberl, F.; Bozzetto, L. M.; Filipović, M. D.; Points, S. D.; Chu, Y.-H.; Sasaki, M.; Pietsch, W.; Gruendl, R. A.; Dickel, J.; Smith, R. C.; Sturm, R.; Crawford, E. J.; De Horta, A. Y.

    2012-10-01

    Context. The Large Magellanic Cloud (LMC) is an ideal target for the study of an unbiased and complete sample of supernova remnants (SNRs). We started an X-ray survey of the LMC with XMM-Newton, which, in combination with observations at other wavelengths, will allow us to discover and study remnants that are either even fainter or more evolved (or both) than previously known. Aims: We present new X-ray and radio data of the LMC SNR candidate DEM L205, obtained by XMM-Newton and ATCA, along with archival optical and infrared observations. Methods: We use data at various wavelengths to study this object and its complex neighbourhood, in particular in the context of the star formation activity, past and present, around the source. We analyse the X-ray spectrum to derive some remnant's properties, such as age and explosion energy. Results: Supernova remnant features are detected at all observed wavelengths : soft and extended X-ray emission is observed, arising from a thermal plasma with a temperature kT between 0.2 keV and 0.3 keV. Optical line emission is characterised by an enhanced [S ii]-to-Hα ratio and a shell-like morphology, correlating with the X-ray emission. The source is not or only tentatively detected at near-infrared wavelengths (shorter than 10 μm), but there is a detection of arc-like emission at mid and far-infrared wavelengths (24 and 70 μm) that can be unambiguously associated with the remnant. We suggest that thermal emission from dust heated by stellar radiation and shock waves is the main contributor to the infrared emission. Finally, an extended and faint non-thermal radio emission correlates with the remnant at other wavelengths and we find a radio spectral index between -0.7 and -0.9, within the range for SNRs. The size of the remnant is ~79 × 64 pc and we estimate a dynamical age of about 35 000 years. Conclusions: We definitely confirm DEM L205 as a new SNR. This object ranks amongst the largest remnants known in the LMC. The numerous

  8. Isothermal blast wave model of supernova remnants

    NASA Technical Reports Server (NTRS)

    Solinger, A.; Buff, J.; Rappaport, S.

    1975-01-01

    The validity of the 'adiabatic' assumption in supernova-remnant calculations is examined, and the alternative extreme of an isothermal blast wave is explored. It is concluded that, because of thermal conductivity, the large temperature gradients predicted by the adiabatic model probably are not maintained in nature. Self-similar solutions to the hydrodynamic equations for an isothermal blast wave have been found and studied. These solutions are then used to determine the relationship between X-ray observations and inferred parameters of supernova remnants. A comparison of the present results with those for the adiabatic model indicates differences which are less than present observational uncertainties. It is concluded that most parameters of supernova remnants inferred from X-ray measurements are relatively insensitive to the specifics of the blast-wave model.

  9. Temperature relaxation in supernova remnants, revisited

    NASA Technical Reports Server (NTRS)

    Itoh, H.

    1984-01-01

    Some supernova remnants are expanding into a partially neutral medium. The neutral atoms which are engulfed by the fast blast shock are collisionally ionized to eject low-energy secondary electrons. Calculations are conducted of the temperature relaxation through Coulomb collisions among the secondary electrons, the shocked electrons, and the ions, assuming that the three species have Maxwellian velocity distributions. The results are applied to a self-similar blast wave. If the efficiency of collisionless electron heating at the shock front is high in young remnants such as Tycho, the secondary electrons may be much cooler than both the shocked electrons and the ions. In this case, the emergent X-ray continuum spectrum will have a two-temperature, or a power-law, appearance. This effect may have been observed in the bright rim of the remnant of SN 1006.

  10. REMNANTS OF BINARY WHITE DWARF MERGERS

    SciTech Connect

    Raskin, Cody; Scannapieco, Evan; Timmes, F. X.; Fryer, Chris; Rockefeller, Gabriel

    2012-02-10

    We carry out a comprehensive smooth particle hydrodynamics simulation survey of double-degenerate white dwarf binary mergers of varying mass combinations in order to establish correspondence between initial conditions and remnant configurations. We find that all but one of our simulation remnants share general properties such as a cold, degenerate core surrounded by a hot disk, while our least massive pair of stars forms only a hot disk. We characterize our remnant configurations by the core mass, the rotational velocity of the core, and the half-mass radius of the disk. We also find that some of our simulations with very massive constituent stars exhibit helium detonations on the surface of the primary star before complete disruption of the secondary. However, these helium detonations are insufficiently energetic to ignite carbon, and so do not lead to prompt carbon detonations.

  11. Serial segment method for measuring remnant

    NASA Technical Reports Server (NTRS)

    Magdaleno, R. E.

    1972-01-01

    For tracking tasks where a sum of sine waves forcing function is used it is often difficult and/or expensive to obtain the pilot's remnant in the vicinity of the sine waves. For the case where each sine wave has at least four times an integer number of cycle per run length, this paper illustrates the serial segments method for measuring remnant power spectral density in a frequency band centered on each sine wave. This method can be implemented on digital, hybrid, or analog Fourier coefficient analyzers, and is particularly advantageous on the latter since properties of Fourier coefficients are exploited to yield both a remnant measure and an improved estimate of the correlated component.

  12. Rayleigh-Taylor instabilities in Type Ia supernova remnants undergoing cosmic ray particle acceleration - low adiabatic index solutions

    NASA Astrophysics Data System (ADS)

    Wang, Chih-Yueh

    2011-07-01

    This study investigates the evolution of Rayleigh-Taylor (R-T) instabilities in Type Ia supernova remnants that are associated with a low adiabatic index γ, where γ < 5/3, which reflects the expected change in the supernova shock structure as a result of cosmic ray particle acceleration. Extreme cases, such as the case with the maximum compression ratio that corresponds to γ= 1.1, are examined. As γ decreases, the shock compression ratio rises, and an increasingly narrow intershock region with a more pronounced initial mixture of R-T unstable gas is produced. Consequently, the remnant outline may be perturbed by small-amplitude, small-wavelength bumps. However, as the instability decays over time, the extent of convective mixing in terms of the ratio of the radius of the R-T fingers to the blast wave does not strongly depend on the value of γ for γ≥ 1.2. As a result of the age of the remnant, the unstable gas cannot extend sufficiently far to form metal-enriched filaments of ejecta material close to the periphery of Tycho's supernova remnant. The consistency of the dynamic properties of Tycho's remnant with the adiabatic model γ= 5/3 reveals that the injection of cosmic rays is too weak to alter the shock structure. Even with very efficient acceleration of cosmic rays at the shock, significantly enhanced mixing is not expected in Type Ia supernova remnants.

  13. Phosphorus in the young supernova remnant Cassiopeia A.

    PubMed

    Koo, Bon-Chul; Lee, Yong-Hyun; Moon, Dae-Sik; Yoon, Sung-Chul; Raymond, John C

    2013-12-13

    Phosphorus ((31)P), which is essential for life, is thought to be synthesized in massive stars and dispersed into interstellar space when these stars explode as supernovae (SNe). Here, we report on near-infrared spectroscopic observations of the young SN remnant Cassiopeia A, which show that the abundance ratio of phosphorus to the major nucleosynthetic product iron ((56)Fe) in SN material is up to 100 times the average ratio of the Milky Way, confirming that phosphorus is produced in SNe. The observed range is compatible with predictions from SN nucleosynthetic models but not with the scenario in which the chemical elements in the inner SN layers are completely mixed by hydrodynamic instabilities during the explosion. PMID:24337291

  14. Spitzer Space Telescope Spectroscopy of the Kepler Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Roellig, T. L.; Onaka, T.

    2004-01-01

    The Infrared Spectrograph on the Spitzer Space Telescope was used for observations of the Kepler supernova remnant, with all four instrument modules targeted on the bright infrared knot located at 17h30m35.80s,-21d28m54.0s (J2000). The low spectral resolution modules data show a dust continuum spectrum consistent with dust grains heated by high-energy electrons, while the high resolution modules data show atomic emission line ratios consistent with excitation by a high velocity shock of greater than 100 kilometers per second and electron densities of approximately 1,000 per centimeter. The abundance ratios for the six detected elements show signs of heavy-element enhancement. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology. Support for this work was provided by NASA's Office of Space Science.

  15. Overall and blade element performance of a 1.20-pressure-ratio fan stage with rotor blades reset -5 deg

    NASA Technical Reports Server (NTRS)

    Lewis, G. W., Jr.; Osborn, W. M.; Moore, R. D.

    1976-01-01

    A 51-cm-diam model of a fan stage for a short haul aircraft was tested in a single stage-compressor research facility. The rotor blades were set 5 deg toward the axial direction (opened) from design setting angle. Surveys of the air flow conditions ahead of the rotor, between the rotor and stator, and behind the stator were made over the stable operating range of the stage. At the design speed of 213.3 m/sec and a weight flow of 31.5 kg/sec, the stage pressure ratio and efficiency were 1.195 and 0.88, respectively. The design speed rotor peak efficiency of 0.91 occurred at the same flow rate.

  16. HTR-PROTEUS Pebble Bed Experimental Program Cores 1, 1A, 2, and 3: Hexagonal Close Packing with a 1:2 Moderator-to-Fuel Pebble Ratio

    SciTech Connect

    John D. Bess; Barbara H. Dolphin; James W. Sterbentz; Luka Snoj; Igor Lengar; Oliver Köberl

    2012-03-01

    In its deployment as a pebble bed reactor (PBR) critical facility from 1992 to 1996, the PROTEUS facility was designated as HTR-PROTEUS. This experimental program was performed as part of an International Atomic Energy Agency (IAEA) Coordinated Research Project (CRP) on the Validation of Safety Related Physics Calculations for Low Enriched HTGRs. Within this project, critical experiments were conducted for graphite moderated LEU systems to determine core reactivity, flux and power profiles, reaction-rate ratios, the worth of control rods, both in-core and reflector based, the worth of burnable poisons, kinetic parameters, and the effects of moisture ingress on these parameters. Four benchmark experiments were evaluated in this report: Cores 1, 1A, 2, and 3. These core configurations represent the hexagonal close packing (HCP) configurations of the HTR-PROTEUS experiment with a moderator-to-fuel pebble ratio of 1:2. Core 1 represents the only configuration utilizing ZEBRA control rods. Cores 1A, 2, and 3 use withdrawable, hollow, stainless steel control rods. Cores 1 and 1A are similar except for the use of different control rods; Core 1A also has one less layer of pebbles (21 layers instead of 22). Core 2 retains the first 16 layers of pebbles from Cores 1 and 1A and has 16 layers of moderator pebbles stacked above the fueled layers. Core 3 retains the first 17 layers of pebbles but has polyethylene rods inserted between pebbles to simulate water ingress. The additional partial pebble layer (layer 18) for Core 3 was not included as it was used for core operations and not the reported critical configuration. Cores 1, 1A, 2, and 3 were determined to be acceptable benchmark experiments.

  17. HTR-PROTEUS Pebble Bed Experimental Program Cores 1, 1A, 2, and 3: Hexagonal Close Packing with a 1:2 Moderator-to-Fuel Pebble Ratio

    SciTech Connect

    John D. Bess; Barbara H. Dolphin; James W. Sterbentz; Luka Snoj; Igor Lengar; Oliver Köberl

    2013-03-01

    In its deployment as a pebble bed reactor (PBR) critical facility from 1992 to 1996, the PROTEUS facility was designated as HTR-PROTEUS. This experimental program was performed as part of an International Atomic Energy Agency (IAEA) Coordinated Research Project (CRP) on the Validation of Safety Related Physics Calculations for Low Enriched HTGRs. Within this project, critical experiments were conducted for graphite moderated LEU systems to determine core reactivity, flux and power profiles, reaction-rate ratios, the worth of control rods, both in-core and reflector based, the worth of burnable poisons, kinetic parameters, and the effects of moisture ingress on these parameters. Four benchmark experiments were evaluated in this report: Cores 1, 1A, 2, and 3. These core configurations represent the hexagonal close packing (HCP) configurations of the HTR-PROTEUS experiment with a moderator-to-fuel pebble ratio of 1:2. Core 1 represents the only configuration utilizing ZEBRA control rods. Cores 1A, 2, and 3 use withdrawable, hollow, stainless steel control rods. Cores 1 and 1A are similar except for the use of different control rods; Core 1A also has one less layer of pebbles (21 layers instead of 22). Core 2 retains the first 16 layers of pebbles from Cores 1 and 1A and has 16 layers of moderator pebbles stacked above the fueled layers. Core 3 retains the first 17 layers of pebbles but has polyethylene rods inserted between pebbles to simulate water ingress. The additional partial pebble layer (layer 18) for Core 3 was not included as it was used for core operations and not the reported critical configuration. Cores 1, 1A, 2, and 3 were determined to be acceptable benchmark experiments.

  18. The Retrograde Transposition of the Remnant Earlobe in Patients With Low-Set Microtia.

    PubMed

    Cheng, Lin; Hu, Jin-Tian; Zhou, Xu; Li, Zhi-Bin; Zhang, Yong-Biao; Cao, Yi-Lin; Zhang, Qing-Guo; Liu, Tun

    2015-10-01

    During auricle reconstruction, lobular transposition has become a routine technique applied by most of surgeons. But to some low-set remnant ears, it is difficult to manipulate the conventional lobule transposition method in clinical application. In this article, the authors introduce a method to retrogradely transpose the remnant ear with the the ratio of length:width of the lobular flap being 4-5:1. The lobule transposition could be applied during the first stage of Nagata method or the third stage using expansion method. The authors take the superior part of the remnant ear as the pedicle and make the incision at the middle and inferior parts of the remnant ear to form the lobular flap. Then the inferior lobule is rotated posteriorly and superiorly to cover the rear end of the framework and to form the inferior part of helical rim. The results of the reconstructed auricles are satisfactory with aesthetic natural earlobes and the location of the reconstructed ear is symmetric to the contralateral ear. The authors believe that to the 2% to 5% patients with low-set microtia, this is a good way to make use of remnant ear for the purpose of a real earlobe. PMID:26468806

  19. Mucoepidermoid carcinoma in a thyroglossal duct remnant

    PubMed Central

    Warner, E.; Ofo, E.; Connor, S.; Odell, E.; Jeannon, J.P.

    2015-01-01

    Introduction Thyroglossal duct cysts (TDC) are common midline neck swellings resulting from embryological remnants of the thyroglossal duct. They often contain ectopic thyroid tissue and malignant transformation has been reported, most commonly to papillary thyroid carcinoma. Mucoepidermoid carcinoma (MEC) usually occurs in the salivary glands and only rarely in the thyroid. This is the first case of a MEC occurring within a thyroglossal duct remnant. Presentation of a case A 73 year old lady presented with a thyroglossal duct cyst. She declined surgical excision, as she was adamant she wanted to avoid surgery. The neck mass rapidly enlarged at two years following initial diagnosis. Fine needle aspiration cytology was suspicious for carcinoma. She underwent total thyroidectomy and selective central compartment neck dissection with adjuvant radiotherapy. She remains alive and well two years post treatment. Discussion Mucoepidermoid carcinoma is the most common malignant neoplasm of salivary glands, although it has rarely been reported in diverse locations including the thyroid, lung and pancreas. To the best of our knowledge, this is the first reported case of mucoepidermoid carcinoma arising from a thyroglossal duct remnant. Conclusion This case adds weight to the literature favouring surgical excision of thyroglossal duct remnants due to the risk of malignant transformation. PMID:26101054

  20. The Cygnus Loop: An Older Supernova Remnant.

    ERIC Educational Resources Information Center

    Straka, William

    1987-01-01

    Describes the Cygnus Loop, one of brightest and most easily studied of the older "remnant nebulae" of supernova outbursts. Discusses some of the historical events surrounding the discovery and measurement of the Cygnus Loop and makes some projections on its future. (TW)

  1. 27 CFR 19.359 - Remnants.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Remnants. 19.359 Section 19.359 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL DISTILLED SPIRITS PLANTS Processing of Distilled Spirits Rules for Bottling, Packaging, and Removal of Products §...

  2. 27 CFR 19.359 - Remnants.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Remnants. 19.359 Section 19.359 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL DISTILLED SPIRITS PLANTS Processing of Distilled Spirits Rules for Bottling, Packaging, and Removal of Products §...

  3. 27 CFR 19.359 - Remnants.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Remnants. 19.359 Section 19.359 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS DISTILLED SPIRITS PLANTS Processing of Distilled Spirits Rules for Bottling, Packaging, and Removal of Products §...

  4. 27 CFR 19.389 - Remnants.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Remnants. 19.389 Section 19.389 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS DISTILLED SPIRITS PLANTS Processing Operations Other Than Denaturation and Manufacture of Articles Bottling, Packaging,...

  5. Spectral Mapping of Kepler's Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Reynolds, Stephen; Blair, William; Borkowski, Kazimierz; Ghavamian, Parviz; Long, Knox; Sankrit, Ravi; Williams, Brian

    2008-03-01

    We propose to leverage our extensive previous multi-wavelength investigations of Kepler's supernova remnant (SN 1604) by obtaining IRS spectral maps of this premier example of a 'massive Type Ia' remnant. Of particular interest is the dense circumstellar medium (CSM) evidently surrounding Kepler. This material is best investigated in infrared, where shock-heated dust reveals the thermal-gas density and possible composition clues such as the 10-micron silicate feature. Full LL coverage (14-38 um) will permit detailed mapping of continuum shape changes with spatial position that are only hinted at from our previous MIPS 24 and 70 um imaging. SL mapping of selected regions will permit detailed studies of changes in the silicate feature with position, suggested by two slit positions in earlier observations. Combined with our deep Chandra observation (750 ks), these data will permit a detailed study of dust destruction in fast shocks. Kepler also shows regions near the remnant edge dominated by synchrotron X-ray emission, indicating electron acceleration to energies of order 100 TeV. However, the dominance of synchrotron continuum means that properties of the thermal medium, important for understanding shock-acceleration physics, cannot be diagnosed with X-rays. Our IRS spectra should allow such diagnosis. Kepler's unique position among Type Ia supernova remnants makes it a critical target for the understanding of the Type Ia phenomenon.

  6. HTR-PROTEUS PEBBLE BED EXPERIMENTAL PROGRAM CORE 4: RANDOM PACKING WITH A 1:1 MODERATOR-TO-FUEL PEBBLE RATIO

    SciTech Connect

    John D. Bess; Leland M. Montierth

    2013-03-01

    In its deployment as a pebble bed reactor (PBR) critical facility from 1992 to 1996, the PROTEUS facility was designated as HTR-PROTEUS. This experimental program was performed as part of an International Atomic Energy Agency (IAEA) Coordinated Research Project (CRP) on the Validation of Safety Related Physics Calculations for Low Enriched HTGRs. Within this project, critical experiments were conducted for graphite moderated LEU systems to determine core reactivity, flux and power profiles, reaction-rate ratios, the worth of control rods, both in-core and reflector based, the worth of burnable poisons, kinetic parameters, and the effects of moisture ingress on these parameters. One benchmark experiment was evaluated in this report: Core 4. Core 4 represents the only configuration with random pebble packing in the HTR-PROTEUS series of experiments, and has a moderator-to-fuel pebble ratio of 1:1. Three random configurations were performed. The initial configuration, Core 4.1, was rejected because the method for pebble loading, separate delivery tubes for the moderator and fuel pebbles, may not have been completely random; this core loading was rejected by the experimenters. Cores 4.2 and 4.3 were loaded using a single delivery tube, eliminating the possibility for systematic ordering effects. The second and third cores differed slightly in the quantity of pebbles loaded (40 each of moderator and fuel pebbles), stacked height of the pebbles in the core cavity (0.02 m), withdrawn distance of the stainless steel control rods (20 mm), and withdrawn distance of the autorod (30 mm). The 34 coolant channels in the upper axial reflector and the 33 coolant channels in the lower axial reflector were open. Additionally, the axial graphite fillers used in all other HTR-PROTEUS configurations to create a 12-sided core cavity were not used in the randomly packed cores. Instead, graphite fillers were placed on the cavity floor, creating a funnel-like base, to discourage ordering

  7. HTR-PROTEUS PEBBLE BED EXPERIMENTAL PROGRAM CORE 4: RANDOM PACKING WITH A 1:1 MODERATOR-TO-FUEL PEBBLE RATIO

    SciTech Connect

    John D. Bess; Leland M. Montierth

    2014-03-01

    In its deployment as a pebble bed reactor (PBR) critical facility from 1992 to 1996, the PROTEUS facility was designated as HTR-PROTEUS. This experimental program was performed as part of an International Atomic Energy Agency (IAEA) Coordinated Research Project (CRP) on the Validation of Safety Related Physics Calculations for Low Enriched HTGRs. Within this project, critical experiments were conducted for graphite moderated LEU systems to determine core reactivity, flux and power profiles, reaction-rate ratios, the worth of control rods, both in-core and reflector based, the worth of burnable poisons, kinetic parameters, and the effects of moisture ingress on these parameters. One benchmark experiment was evaluated in this report: Core 4. Core 4 represents the only configuration with random pebble packing in the HTR-PROTEUS series of experiments, and has a moderator-to-fuel pebble ratio of 1:1. Three random configurations were performed. The initial configuration, Core 4.1, was rejected because the method for pebble loading, separate delivery tubes for the moderator and fuel pebbles, may not have been completely random; this core loading was rejected by the experimenters. Cores 4.2 and 4.3 were loaded using a single delivery tube, eliminating the possibility for systematic ordering effects. The second and third cores differed slightly in the quantity of pebbles loaded (40 each of moderator and fuel pebbles), stacked height of the pebbles in the core cavity (0.02 m), withdrawn distance of the stainless steel control rods (20 mm), and withdrawn distance of the autorod (30 mm). The 34 coolant channels in the upper axial reflector and the 33 coolant channels in the lower axial reflector were open. Additionally, the axial graphite fillers used in all other HTR-PROTEUS configurations to create a 12-sided core cavity were not used in the randomly packed cores. Instead, graphite fillers were placed on the cavity floor, creating a funnel-like base, to discourage ordering

  8. Shocks in Dense Clouds in the Vela Supernova Remnant: FUSE

    NASA Technical Reports Server (NTRS)

    Nichols, Joy; Sonneborn, George (Technical Monitor)

    2002-01-01

    We have obtained 8 LWRS FUSE spectra to study a recently identified interaction of the Vela supernova remnant with a dense cloud region along its western edge. The goal is to quantify the temperature, ionization, density, and abundance characteristics associated with this shock/dense cloud interface by means of UV absorption line studies. Our detection of high-velocity absorption line C I at +90 to +130 km/s with IUE toward a narrow region interior to the Vela SNR strongly suggests the Vela supernova remnant is interacting with a dense ISM or molecular cloud. The shock/dense cloud interface is suggested by (1) the rarity of detection of high-velocity C I seen in IUE spectra, (2) its very limited spatial distribution in the remnant, and (3) a marked decrease in X-ray emission in the region immediately west of the position of these stars where one also finds a 100 micron emission ridge in IRAS images. We have investigated the shock physics and general properties of this interaction region through a focussed UV absorption line study using FUSE spectra. We have FUSE data on OVI absorption lines observed toward 8 stars behind the Vela supernova remnant (SNR). We compare the OVI observations with IUE observations of CIV absorption toward the same stars. Most of the stars, which are all B stars, have complex continua making the extraction of absorption lines difficult. Three of the stars, HD 72088, HD 72089 and HD 72350, however, are rapid rotators (v sin i less than 100 km/s) making the derivation of absorption column densities much easier. We have measured OVI and CIV column densities for the "main component" (i.e. the low velocity component) for these stars. In addition, by removing the H2 line at 1032.35A (121.6 km/s relative to OVI), we find high velocity components of OVI at approximately 150 km/s that we attribute to the shock in the Vela SNR. The column density ratios and magnitudes are compared to both steady shock models and results of hydrodynamical SNR

  9. Expansion of the Optical Remnant from Tycho’s Supernova

    NASA Astrophysics Data System (ADS)

    Putko, Joseph; Winkler, P. Frank; Blair, William P.

    2015-01-01

    Tycho's supernova remnant (SNR) is the expanding remnant from SN 1572, the penultimate Galactic supernova to have been recorded by contemporary observers. Its optical light is almost exclusively faint hydrogen Balmer emission around the periphery of the SNR, produced where fast nonradiative shocks encounter partly neutral preshock interstellar material. A variety of filaments, presumably thin sheets oriented tangentially, surround about one-third of the radio/X-ray shell. We have used CCD images, taken from KPNO over seven epochs from 1986 to 2009, to give the first optical expansion measurement of Tycho's SNR of the CCD era. Thirty filaments were identified and measured; the majority of them are at or near the remnant's outer rim and have proper motions from 0.19‧‧ ± 0.01‧‧ yr-1 to 0.26‧‧ ± 0.02‧‧ yr-1. The associated expansion indices, defined as the ratio of the current expansion rate to the historical mean, range from 0.35 ± 0.03 to 0.52 ± 0.05. Our measurements are consistent with those from the classic study by Kamper & van den Bergh (1978, ApJ, 224, 851) for the same filaments, but the CCD measurements have higher precision, and we have measured several additional fainter filaments. For direct comparison with X-ray and radio measurements, we selected the subset of optical filaments lying exactly at the outer rim, as identified in Chandra and VLA images. Considering only these filaments, virtually all have expansion indices greater than 0.40, the Sedov value. In addition to the rim filaments, there are several seen in the interior (in projection) that have smaller proper motions; these may have been decelerated, and/or they could be directed non-tangentially. Our final epoch of images, taken from the 3.5m WIYN telescope in 2009, reveals previously undetected extremely faint optical emission surrounding well over half of the remnant shell. This newly detected faint emission agrees well with the limb as defined in X-ray and radio images

  10. Noise data from tests of a 1.83 meter (6-ft-) diameter variable-pitch 1.2-pressure-ratio fan (QF-9)

    NASA Technical Reports Server (NTRS)

    Glaser, F. W.; Wazyniak, J. A.; Friedman, R.

    1975-01-01

    Acoustic and aerodynamic data for a 1.83-meter (6-ft.) diameter fan suitable for a quiet engine for short-takeoff-and-landing (STOL) aircraft are documented. The QF-9 rotor blades had an adjustable pitch feature which provided a means for testing at several rotor blade setting angles, including one for reverse thrust. The fan stage incorporated features for low noise. Far-field noise around the fan was measured without acoustic suppression over a range of operating conditions for six different rotor blade setting angles in the forward thrust configuration, and for one in the reverse configuration. Complete results of one-third-octave band analysis of the data are presented in tabular form. Also included are power spectra, data referred to the source, and sideline perceived noise levels.

  11. Possible Population III remnants at redshift 3.5

    NASA Astrophysics Data System (ADS)

    Crighton, Neil H. M.; O'Meara, John M.; Murphy, Michael T.

    2016-03-01

    The first stars, known as Population III (PopIII), produced the first heavy elements, thereby enriching their surrounding pristine gas. Previous detections of metals in intergalactic gas clouds, however, find a heavy element enrichment larger than 1/1000 times that of the solar environment, higher than expected for PopIII remnants. In this letter, we report the discovery of a Lyman limit system (LLS) at z = 3.53 with the lowest metallicity seen in gas with discernable metals, 10-3.41±0.26 times the solar value, at a level expected for PopIII remnants. We make the first relative abundance measurement in such low metallicity gas: the carbon-to-silicon ratio is 10-0.26±0.17 times the solar value. This is consistent with models of gas enrichment by a PopIII star formation event early in the Universe, but also consistent with later, Population II enrichment. The metals in all three components comprising the LLS, which has a velocity width of 400 km s-1, are offset in velocity by ˜+6 km s-1 from the bulk of the hydrogen, suggesting the LLS was enriched by a single event. Relative abundance measurements in this near-pristine regime open a new avenue for testing models of early gas enrichment and metal mixing.

  12. Imagery and spectroscopy of supernova remnants and H-2 regions

    NASA Technical Reports Server (NTRS)

    Dufour, R. J.

    1984-01-01

    Research activities relating to supernova remnants were summarized. The topics reviewed include: progenitor stars of supernova remnants, UV/optical/radio/X-ray imagery of selected regions in the Cygnus Loop, UV/optical spectroscopy of the Cygnus Loop spur, and extragalactic supernova remnant spectra.

  13. New Candidate Supernova Remnants in the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Winkler, P. F.; Lewinter, R.

    1992-12-01

    We have surveyed six 30(') times 30(') fields in the Small Magellanic Cloud, using the Curtis Schmidt telescope at CTIO with a Thomson CCD, to search for previously undetected supernova remnants (SNRs). Narrow-band images are obtained in lines of [S II] (lambda lambda \\ 6716,31), Hα , and a nearby continuum band. The ratio of [S II]/Hα \\ emission discriminates well between shock-heated material charcteristic of SNRs and photo-ionized material such as H II regions. This technique has proved highly effective in surveys of other galaxies (e.g. Long et al., Ap J Supp, 72, 61). Deep emission-line images and a continuum band closely matched in wavelength enable us to subtract virtually the entire stellar contribution and thus achieve high sensitivity to faint, diffuse emission. We have identified 13 objects, all of which have [S II]/Hα \\ ratios > 0.4\\ and a full or partial shell-like morphology, making them extremely strong SNR candidates. Several other diffuse objects have high [S II]/Hα \\ ratios, and many of these may also be SNRs. Compared with the 12 previously known remnants of Mathewson et al., (Ap J Supp 51, 345; 55, 189), the new candidates are generally larger and have lower surface brightness. An investigation of the cumulative number vs diameter relation for our larger sample indicates a slope significantly steeper than the value near unity originally found by Mathewson et al., and is more consistent with standard models for SNR evolution. Selection effects may well have led to an excess of small, bright objects in the earlier samples. This work was supported in part by NSF grant AST-9114935 and by the W.M. Keck Foundation through the Keck Northeast Astronomy Consortium.

  14. An Optical Search For Supernova Remnants in NGC 2403

    NASA Astrophysics Data System (ADS)

    Matonick, David M.; Fesen, Robert A.; Blair, William P.; Long, Knox S.

    1997-12-01

    We present the results of an optical search for supernova remnants (SNRs) in the Scd galaxy NGC 2403 using image and spectral observations of a ~8' × 8' field covering nearly all of this galaxy. Our SNR identification technique consisted of constructing continuum-subtracted Hα and [S II] λλ6716, 6731 images, obtaining spectra of a few [S II]-bright emission nebulae found in these images, and then using the [S II]/Hα ratios obtained from these spectra to correct the image [S II]/Hα ratios. Thirty-five emission nebulae with [S II]/Hα >= 0.45 were identified as SNRs and have diameters of 20-200 pc, reddening-corrected Hα intensities of 2.2 × 10-15 to 1.4 × 10-13 ergs cm-2 s-1, [S II]/Hα ratios of 0.45-1.11, and a variety of optical morphologies (shell, arc, and filled). Spectra of 15 of these remnants were obtained and are presented. The two NGC 2403 SNRs previously identified by D'Odorico, Dopita, & Benvenuti were among the 35 SNRs detected. Our final NGC 2403 SNR sample appears biased against detecting large, faint remnants, and no SNRs were detected inside bright H II regions. An examination of the [S II]/Hα values for all the nebulae measured in NGC 2403 shows no sharp dividing line between SNRs and H II regions, similar to what was found in M31, NGC 300, and NGC 7793 (Walterbos & Braun; Blair & Long). We estimate roughly that there are about 4 times more SNRs in NGC 2403 than we detected, which, assuming the observable lifetime of a SNR is ~20,000 yr, yields a crude rate of 1 SN in 150 yr. Analysis of the 15 SNR spectra show a detectable nitrogen gradient, a larger scatter in oxygen abundances than in nitrogen, and a lower mean oxygen abundance than from published H II region data, all of which have been seen in previous SNR studies of other galaxies. Based in part on research done at the Michigan-Dartmouth-M.I.T. (MDM) Observatory, operated by the University of Michigan, Dartmouth College, and the Massachusetts Institute of Technology.

  15. The structure of common-envelope remnants

    NASA Astrophysics Data System (ADS)

    Hall, Philip D.

    2015-05-01

    We investigate the structure and evolution of the remnants of common-envelope evolution in binary star systems. In a common-envelope phase, two stars become engulfed in a gaseous envelope and, under the influence of drag forces, spiral to smaller separations. They may merge to form a single star or the envelope may be ejected to leave the stars in a shorter period orbit. This process explains the short orbital periods of many observed binary systems, such as cataclysmic variables and low-mass X-ray binary systems. Despite the importance of these systems, and of common-envelope evolution to their formation, it remains poorly understood. Specifically, we are unable to confidently predict the outcome of a common-envelope phase from the properties at its onset. After presenting a review of work on stellar evolution, binary systems, common-envelope evolution and the computer programs used, we describe the results of three computational projects on common-envelope evolution. Our work specifically relates to the methods and prescriptions which are used for predicting the outcome. We use the Cambridge stellar-evolution code STARS to produce detailed models of the structure and evolution of remnants of common-envelope evolution. We compare different assumptions about the uncertain end-of-common envelope structure and envelope mass of remnants which successfully eject their common envelopes. In the first project, we use detailed remnant models to investigate whether planetary nebulae are predicted after common-envelope phases initiated by low-mass red giants. We focus on the requirement that a remnant evolves rapidly enough to photoionize the nebula and compare the predictions for different ideas about the structure at the end of a common-envelope phase. We find that planetary nebulae are possible for some prescriptions for the end-of-common envelope structure. In our second contribution, we compute a large set of single-star models and fit new formulae to the core radii of

  16. Planets orbiting Quark Nova compact remnants

    NASA Astrophysics Data System (ADS)

    Keränen, P.; Ouyed, R.

    2003-08-01

    We explore planet formation in the Quark Nova scenario. If a millisecond pulsar explodes as a Quark Nova, a protoplanetary disk can be formed out of the metal rich fall-back material. The propeller mechanism transfers angular momentum from the born quark star to the disk that will go through viscous evolution with later plausible grain condensation and planet formation. As a result, earth-size planets on circular orbits may form within short radii from the central quark star. The planets in the PSR 1257+12 system can be explained by our model if the Quark Nova compact remnant is born with a period of ~ 0.5 ms following the explosion. We suggest that a good portion of the Quark Nova remnants may harbour planetary systems.

  17. Supernova Remnants in the Most Fertile Galaxy: NGC 6946

    NASA Astrophysics Data System (ADS)

    Winkler, P. Frank; Long, Knox S.; Blair, William P.

    2014-08-01

    As the host to more recorded supernovae (nine in the past century) than any other galaxy, ngal is a unique venue for studying young (and old) supernova remnants (SNRs). Using deep emission-line images of ngal we obtained from WIYN, we have identified 148 new emission nebulae through their high S II:Hα ratios, indicating that they are strong SNR candidates. This is over 5 times as many as have previously been identified; yet of the 175 total objects, only 6 have been spectroscopically confirmed. We propose multislit spectroscopy from GMOS-N to study the majority of those with no spectra to date. Some 26 are essentially unresolved in our images (diameters ≲ 1 arcsec=27 pc at ngal) and hence probably are relatively young. Several are also coincident with soft X-ray sources (a further indicator of youthful vigor) and have strong O III emission. Some may be rare, ejecta- dominated core-collapse SNRs akin to Cas A, where ``fresh" nucleosynthesis products can be seen. Only spectroscopy, to look for broad emission lines from fast-moving ejecta, can confirm this. We will include spectra of two of the nine recorded SNe in ngal-the first late-time spectrum of SN 2004et, and the first of SN 1980K with high signal-to-noise-adding to the extremely small number of spectra for SNRs only a few decades old. Finally we will use the H II:Hα ratio in a large number of ISM-dominated SNRs to map the N abundance and its gradient across the disk of ngal, and we will use archival HST images to identify the stellar environments that produced the SNe whose remnants we see today.

  18. HESS upper limits for Kepler's supernova remnant

    NASA Astrophysics Data System (ADS)

    Aharonian, F.; Akhperjanian, A. G.; Barres de Almeida, U.; Bazer-Bachi, A. R.; Behera, B.; Beilicke, M.; Benbow, W.; Berge, D.; Bernlöhr, K.; Boisson, C.; Bolz, O.; Borrel, V.; Braun, I.; Brion, E.; Brucker, J.; Bühler, R.; Bulik, T.; Büsching, I.; Boutelier, T.; Carrigan, S.; Chadwick, P. M.; Chounet, L.-M.; Clapson, A. C.; Coignet, G.; Cornils, R.; Costamante, L.; Dalton, M.; Degrange, B.; Dickinson, H. J.; Djannati-Ataï, A.; Domainko, W.; O'C. Drury, L.; Dubois, F.; Dubus, G.; Dyks, J.; Egberts, K.; Emmanoulopoulos, D.; Espigat, P.; Farnier, C.; Feinstein, F.; Fiasson, A.; Förster, A.; Fontaine, G.; Füßling, M.; Gallant, Y. A.; Giebels, B.; Glicenstein, J. F.; Glück, B.; Goret, P.; Hadjichristidis, C.; Hauser, D.; Hauser, M.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hoffmann, A.; Hofmann, W.; Holleran, M.; Hoppe, S.; Horns, D.; Jacholkowska, A.; de Jager, O. C.; Jung, I.; Katarzyński, K.; Kendziorra, E.; Kerschhaggl, M.; Khélifi, B.; Keogh, D.; Komin, Nu.; Kosack, K.; Lamanna, G.; Latham, I. J.; Lemoine-Goumard, M.; Lenain, J.-P.; Lohse, T.; Martin, J. M.; Martineau-Huynh, O.; Marcowith, A.; Masterson, C.; Maurin, D.; McComb, T. J. L.; Moderski, R.; Moulin, E.; Naumann-Godo, M.; de Naurois, M.; Nedbal, D.; Nekrassov, D.; Nolan, S. J.; Ohm, S.; Olive, J.-P.; de Oña Wilhelmi, E.; Orford, K. J.; Osborne, J. L.; Ostrowski, M.; Panter, M.; Pedaletti, G.; Pelletier, G.; Petrucci, P.-O.; Pita, S.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raubenheimer, B. C.; Raue, M.; Rayner, S. M.; Renaud, M.; Ripken, J.; Rob, L.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Ruppel, J.; Sahakian, V.; Santangelo, A.; Schlickeiser, R.; Schöck, F. M.; Schröder, R.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Shalchi, A.; Sol, H.; Spangler, D.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Superina, G.; Tam, P. H.; Tavernet, J.-P.; Terrier, R.; van Eldik, C.; Vasileiadis, G.; Venter, C.; Vialle, J. P.; Vincent, P.; Vivier, M.; Völk, H. J.; Volpe, F.; Wagner, S. J.; Ward, M.; Zdziarski, A. A.; Zech, A.

    2008-09-01

    Aims: Observations of Kepler's supernova remnant (G4.5+6.8) with the HESS telescope array in 2004 and 2005 with a total live time of 13 h are presented. Methods: Stereoscopic imaging of Cherenkov radiation from extensive air showers is used to reconstruct the energy and direction of the incident gamma rays. Results: No evidence for a very high energy (VHE: >100 GeV) gamma-ray signal from the direction of the remnant is found. An upper limit (99% confidence level) on the energy flux in the range 230 GeV{-}12.8 TeV of 8.6 × 10-13 erg cm-2 s-1 is obtained. Conclusions: In the context of an existing theoretical model for the remnant, the lack of a detectable gamma-ray flux implies a distance of at least 6.4 kpc. A corresponding upper limit for the density of the ambient matter of 0.7 cm-3 is derived. With this distance limit, and assuming a spectral index Γ = 2, the total energy in accelerated protons is limited to Ep < 8.6 × 1049 erg. In the synchrotron/inverse Compton framework, extrapolating the power law measured by RXTE between 10 and 20 keV down in energy, the predicted gamma-ray flux from inverse Compton scattering is below the measured upper limit for magnetic field values greater than 52 μ G.

  19. The first Fermi LAT supernova remnant catalog

    DOE PAGESBeta

    Acero, F.

    2016-05-16

    To uniformly determine the properties of supernova remnants (SNRs) at high energies, we have developed the first systematic survey at energies from 1 to 100 GeV using data from the Fermi Large Area Telescope. Based on the spatial overlap of sources detected at GeV energies with SNRs known from radio surveys, we classify 30 sources as likely GeV SNRs. We also report 14 marginal associations and 245 flux upper limits. A mock catalog in which the positions of known remnants are scrambled in Galactic longitude, allows us to determine an upper limit of 22% on the number of GeV candidatesmore » falsely identified as SNRs. We have also developed a method to estimate spectral and spatial systematic errors arising from the diffuse interstellar emission model, a key component of all Galactic Fermi LAT analyses. By studying remnants uniformly in aggregate, we measure the GeV properties common to these objects and provide a crucial context for the detailed modeling of individual SNRs. Combining our GeV results with multiwavelength (MW) data, including radio, X-ray, and TeV, demonstrates the need for improvements to previously sufficient, simple models describing the GeV and radio emission from these objects. As a result, we model the GeV and MW emission from SNRs in aggregate to constrain their maximal contribution to observed Galactic cosmic rays.« less

  20. Supernova remnants in the GC region

    NASA Astrophysics Data System (ADS)

    Asvarov, Abdul

    2016-07-01

    Along with the central Black hole the processes of active star formation play very important role in the energetics of the Galactic center region. The SNe and their remnants (SNRs) are the main ingredients of the processes of star formation. SNRs are also the sources of electromagnetic radiation of all wavelengths from the optical to hard gamma rays. In the presented work we consider the physics of supernova remnants evolving in extreme environmental conditions which are typical for the region of the Galactic center. Because of the high density and strong inhomogeneity of the surrounding medium these objects remain practically invisible at almost all wavelengths. We model evolution of SNR taking into account the pressure of the surrounding medium and the gravitational field of the matter (stars, compact clouds, dark matter) inside the remnant. As it is well established, considerable portion of the kinetic energy of the SNR can be converted into the cosmic ray particles by diffusive shock acceleration mechanism. Therefore the effect of particle acceleration is also included in the model (with the effectiveness of acceleration as a free parameter). Using the observed radiation fluxes at different wavelengths we attempt to obtain limits on the parameters of the model of the Galactic Center, namely, the frequency of star birth, the average density of the matter and radiation field, etc.

  1. The First Fermi LAT Supernova Remnant Catalog

    NASA Astrophysics Data System (ADS)

    Acero, F.; Ackermann, M.; Ajello, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonino, R.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caputo, R.; Caragiulo, M.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen, J. M.; Cohen-Tanugi, J.; Cominsky, L. R.; Condon, B.; Conrad, J.; Cutini, S.; D’Ammando, F.; de Angelis, A.; de Palma, F.; Desiante, R.; Digel, S. W.; Di Venere, L.; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Ferrara, E. C.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Gomez-Vargas, G. A.; Grenier, I. A.; Grondin, M.-H.; Guillemot, L.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Harding, A. K.; Hayashida, M.; Hays, E.; Hewitt, J. W.; Hill, A. B.; Horan, D.; Hou, X.; Iafrate, G.; Jogler, T.; Jóhannesson, G.; Johnson, A. S.; Kamae, T.; Katagiri, H.; Kataoka, J.; Katsuta, J.; Kerr, M.; Knödlseder, J.; Kocevski, D.; Kuss, M.; Laffon, H.; Lande, J.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Magill, J.; Maldera, S.; Marelli, M.; Mayer, M.; Mazziotta, M. N.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nemmen, R.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Petrosian, V.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Renaud, M.; Reposeur, T.; Rousseau, R.; Saz Parkinson, P. M.; Schmid, J.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Strong, A. W.; Suson, D. J.; Tajima, H.; Takahashi, H.; Tanaka, T.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Vianello, G.; Wells, B.; Wood, K. S.; Wood, M.; Yassine, M.; den Hartog, P. R.; Zimmer, S.

    2016-05-01

    To uniformly determine the properties of supernova remnants (SNRs) at high energies, we have developed the first systematic survey at energies from 1 to 100 GeV using data from the Fermi Large Area Telescope (LAT). Based on the spatial overlap of sources detected at GeV energies with SNRs known from radio surveys, we classify 30 sources as likely GeV SNRs. We also report 14 marginal associations and 245 flux upper limits. A mock catalog in which the positions of known remnants are scrambled in Galactic longitude allows us to determine an upper limit of 22% on the number of GeV candidates falsely identified as SNRs. We have also developed a method to estimate spectral and spatial systematic errors arising from the diffuse interstellar emission model, a key component of all Galactic Fermi LAT analyses. By studying remnants uniformly in aggregate, we measure the GeV properties common to these objects and provide a crucial context for the detailed modeling of individual SNRs. Combining our GeV results with multiwavelength (MW) data, including radio, X-ray, and TeV, we demonstrate the need for improvements to previously sufficient, simple models describing the GeV and radio emission from these objects. We model the GeV and MW emission from SNRs in aggregate to constrain their maximal contribution to observed Galactic cosmic rays.

  2. Shocked Clouds in the Vela Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Nichols, Joy S.; Slavin, Jonathan D.

    2004-01-01

    Unusually strong high-excitation C I has been detected in eleven lines of sight through the Vela supernova remnant by means of UV absorption-line studies of IUE data. Most of these lines of sight lie near the western edge of the X-ray bright region of the supernova remnant in a spatially distinct band approximately 1deg by 4deg oriented approximately north/south. The high-excitation C I (denoted C I*) is interpreted as evidence of a complex of shocked dense clouds inside the supernova remnant, due to the high pressures indicated in this region. To further analyze the properties of this region of C I*, we present new HIRES-processed IRAS data of the entire Vela SNR. A temperature map calculated from the HIRES IRAS data, based on a two-component dust model, reveals the signature of hot dust at several locations in the SNR. The hot dust is anti-correlated spatially with X-ray emission as revealed by ROSAT, as would be expected for a dusty medium interacting with a shock wave. The regions of hot dust are strongly correlated with optical filaments, supporting a scenario of dense clouds interior to the SNR that have been shocked and are now cooling behind the supernova blast wave. With few exceptions, the lines of sight to the strong C I* pass through regions of hot dust and optical filaments. Possible mechanisms for the production of the anomalously large columns of C I and C I* are discussed. Dense clouds on the back western hemisphere of the remnant may explain the relatively low X-ray emission in the western portion of the Vela supernova remnant due to the slower forward shock velocity in regions where the shock has encountered the dense clouds. An alternate explanation for the presence of neutral, excited state, and ionized species along the same line of sight may be a magnetic precusor that heats and compresses the gas ahead of the shock.

  3. 2 MASS Near-Infared Imaging of the Supernova Remnant IC443

    NASA Astrophysics Data System (ADS)

    Rho, Jeonghee; van Dyk, Schuyler; Jarrett, T.; Roc, C.; Reach, W. T.

    We present near-infrared imaging of IC443, covering the entire supernova remnant (50' diameter) from The Two Micron All Sky Survey (2MASS). 2MASS imaging is taken simultaneously in the J (1.25 microns), H (1.65 microns) and K_s (2.17 microns) bands using a 1.3 m telescope with a three-channel camera. The images have 3.5'' spatial resolution with a pixel size of 1''. The bands include lines of Pβ, [Ni~II] and [Fe~II] for J band, Br10 and [Fe~II] for H band, and Brγ and H_2 for K_s band. Emission from IC443 was detected in all 3 bands from most of the optically bright parts of the remnant, revealing a shell-like morphology. This is the first near-infrared image of the northeastern and eastern parts. The color and structure are very different between the northeastern and southern parts. The northeastern shell shows sheet-like filamentary structure, similar to that of optical emission, with J and H band emission equivalently bright, and weak K_s emission. The H flux is higher than the K flux in the northeast; its ratio is similar order of magnitude to that of previously measured infrared spectroscopy from 2 positions. The ratio implies that the H band emission from the northeastern shell is mostly [Fe II] (1.64 microns), and the [Fe II] emission is much stronger than Brγ. This contrasts to the ratio of 0.06 observed in H~II regions. The strong [Fe II] line is produced not only by efficient excitation of Fe but also by grain destruction. Most of bright J band emission can be explained by hydrogen line of Pβ (1.28 microns) when we estimate the expected intensity relative to Brγ and Hα. In contrast, the south ridge is dominated by K_s band light with knotty structure, and has weak J and H band emission. The shocked H_2 line emission is well known from the sinus ridge produced by an interaction with dense molecular clouds. The large field of view of the 2MASS image shows that the H_2 emission extends to the east and inner shell of northeastern optical emission, which

  4. Observing Supernovae and Supernova Remnants with JWST

    NASA Astrophysics Data System (ADS)

    Sonneborn, George; Temim, Tea; Williams, Brian J.; Blair, William P.

    2015-01-01

    The James Webb Space Telescope (JWST) will enable near- and mid-infrared studies of supernovae (SN) and supernova remnants (SNR) in the Milky Way and galaxies throughout the local universe and to high redshift. JWST's instrumentation provides imaging, coronography, and spectroscopy (R<3000) over the wavelength range 1-29 microns. The unprecedented sensitivity and angular resolution will enable spectroscopic study of new and recent supernovae, including molecule and dust formation, in galaxies at least out to 30 Mpc, and imaging to much greater distances. The Target of Opportunity response time can be as short as 48 hours, enabling quick follow-up observations of important SN events. JWST will be ideal for the study of Galactic and Magellanic Clouds supernova remnants, particularly young remnants with hot dust. Its high angular resolution (0.07" at 2 microns, 0.7" at 20 microns) will allow direct comparison between the IR, optical, and X-ray morphologies, identifying sites of dust emission in both the ejecta and the shocked ISM unresolved by previous IR telescopes. There is a rich spectrum of atomic lines (H, He I, [Si I], [Fe II], [Ni I-III], [Co II-III], [S III-IV], [Ar II-III], [Ne II, III, V], [O IV]) and molecules (CO, SiO, H2) of importance for SN and SNR studies. JWST is a large aperture (6.5m), cryogenic, infrared-optimized space observatory under construction by NASA, ESA, and CSA for launch in 2018. The JWST observatory will be placed in an Earth-Sun L2 orbit by an Ariane 5 launch vehicle provided by ESA. The observatory is designed for a 5-year prime science mission, with consumables for 10 years of science operations. The first call for proposals for JWST observations will be released in 2017.

  5. Induced population gradients in galaxy merger remnants

    NASA Technical Reports Server (NTRS)

    Mihos, J. Christopher; Hernquist, Lars

    1994-01-01

    We use numerical models to investigate the nature of induced population gradients in merger remnants. As noted by White, we find that the population mixing in stellar-dynamical mergers is rather moderate, leading to metallicity gradients in the remnant that are closely tied to gradients in the progenitor galaxies. Furthermore, the resultant metallicity gradients are poorly fitted by power laws, showing significant nonlinearities within an effective radius. If constant metallicity bulges are added to the progenitor disks, the strong relation between final and initial metallicity gradients is diluted, but the final gradients are still not well fitted by power laws. Detailed studies of the shape of the metallicity gradients in elliptical galaxies should help determine the degree to which stellar-dynamical mergers have contributed to the population of present-day ellipticals. We also consider the effects of centrally concentrated starbursts on metallicity gradients. Using simple models for metallicity enhancement, we find that addition of a metal-rich starburst population can reproduce the magnitude and shape of metallicity gradients observed in elliptical galaxies. However, even in such cases the metallicity gradients in the merger remnant should steepen significantly beyond an effective radius. Modelling such merger-induced starbursts with population synthesis techniques, we find that if the starburst is characterized by solar metallicity, it should be detectable as a bluing of the nuclear regions for several Gyr. However, if the starburst is metal-rich, the reddening effects of higher metallicity makes the broad-band signature of the starburst much more difficult to detect.

  6. Quantum remnants in the classical limit

    NASA Astrophysics Data System (ADS)

    Kowalski, A. M.; Plastino, A.

    2016-09-01

    We analyze here the common features of two dynamical regimes: a quantum and a classical one. We deal with a well known semi-classic system in its route towards the classical limit, together with its purely classic counterpart. We wish to ascertain i) whether some quantum remnants can be found in the classical limit and ii) the details of the quantum-classic transition. The so-called mutual information is the appropriate quantifier for this task. Additionally, we study the Bandt-Pompe's symbolic patterns that characterize dynamical time series (representative of the semi-classical system under scrutiny) in their evolution towards the classical limit.

  7. VHE Gamma-ray Supernova Remnants

    SciTech Connect

    Funk, Stefan; /KIPAC, Menlo Park

    2007-01-22

    Increasing observational evidence gathered especially in X-rays and {gamma}-rays during the course of the last few years support the notion that Supernova remnants (SNRs) are Galactic particle accelerators up to energies close to the ''knee'' in the energy spectrum of Cosmic rays. This review summarizes the current status of {gamma}-ray observations of SNRs. Shell-type as well as plerionic type SNRs are addressed and prospect for observations of these two source classes with the upcoming GLAST satellite in the energy regime above 100 MeV are given.

  8. ASCA observations of the Large Magellanic Cloud supernova remnant sample: Typing supernovae from their remnants

    NASA Technical Reports Server (NTRS)

    Hughes, John P.; Hayashi, Ichizo; Helfand, David; Hwang, Una; Itoh, Masayuki; Kirshner, Robert; Koyama, Katsuji; Markert, Thomas; Tsunemi, Hiroshi; Woo, Jonathan

    1995-01-01

    We present our first results from a study of the supernova remnants (SNRs) in the Large Magellanic Cloud (LMC) using data from ASCA. The three remnants we have analyzed to date, 0509-67.5, 0519-69.0, and N103B, are among the smallest, and presumably also the youngest, in the Cloud. The X-ray spectra of these SNRs show strong K alpha emission lines of silicon, sulfur, argon, and calcium with no evidence for corresponding lines of oxygen, neon, or magnesium. The dominant feature in the spectra is a broad blend of emission lines around 1 keV which we attribute to L-shell emission lines of iron. Model calculations (Nomoto, Thielemann, & Yokoi 1984) show that the major products of nucleosynthesis in Type Ia supernovae (SNs) are the elements from silicon to iron, as observed here. The calculated nucleosynthetic yields from Type Ib and II SNs are shown to be qualitatively inconsistent with the data. We conclude that the SNs which produced these remnants were of Type Ia. This finding also confirms earlier suggestions that the class of Balmer-dominated remnants arise from Type Ia SN explosions. Based on these early results from the LMC SNR sample, we find that roughly one-half of the SNRs produced in the LMC within the last approximately 1500 yr came from Type Ia SNs.

  9. The prevalence of supernova remnants among unidentified Galactic radio sources

    NASA Technical Reports Server (NTRS)

    Helfand, David J.; Velusamy, T.; Becker, R. H.; Lockman, Felix J.

    1989-01-01

    Nine Galactic radio sources were mapped to identify new Crab-like and composite supernova remnants. The sources were selected on the basis of existing stringent upper limits on their hydrogen recombination line fluxes. One new Cracb-like remnant, one new composite remnant, at least one, and probably two, new shell-like remnants, and a compact H II region were found, along with the expected collection of extragalactic objects. The results suggest that there are several hundred SNRs in the Galaxy which are detectable with current instruments, but which have yet to be identified.

  10. An Investigation into PAH Destruction in Nearby Supernova Remnants, North Polar Spur and Cygnus Loop

    NASA Astrophysics Data System (ADS)

    Burkhart, Sarah M.; Witt, Adolf N.

    2015-01-01

    Our goal in conducting this research was to look at the polycyclic aromatic hydrocarbon (PAH)/large dust grain emission intensity ratio in nearby supernova remnants to find evidence for selective PAH destruction by hot gas and high velocity shock waves within these regions, as predicted by the models of Arendt et al. (2010) and Micelotta et al. (2010a,b). Two supernova remnants were studied- the North Polar Spur (NPS) and the Cygnus Loop. The data for PAHs were obtained from the WISE W3 12 micron all-sky map processed by Meisner & Finkbeiner (2014), and the data for the larger grains come from the IRAS 100 micron all-sky map processed by Schlegel, Finkbeiner & Davis (1998). After obtaining a control PAH/large grain intensity ratio of ~2.8 (DN/px)/(MJy/sr) from two high latitude clouds, MBM 30 and MBM 32, we found that the intensity ratios across the NPS and Cygnus Loop were not far off- ~2.7 (DN/px)/(MJy/sr) and ~3.1 (DN/px)/(MJy/sr), respectively- showing no evidence of selective large-scale PAH destruction in supernova remnants. The individual intensities for both PAHs and large grains do decrease inside the Cygnus Loop, however, suggesting a decrease in abundances of both grain types, which could mean total dust grain destruction with the normal ratios coming from foreground and background dust located in the line of sight of the remnant. In addition, temperature and E(B-V) measurements taken from calibrated IRAS images show that while the dust column density increases in the Eastern Veil of the Cygnus Loop, the dust temperature reaches a local maximum, indicating the heating of large grains by interaction with the hot gas in the remnant. The PAH/large grain ratio in the Eastern Veil does decrease and could be indicative of currently ongoing active grain destruction there, with the PAHs being destroyed on a more rapid timescale than the large grains.We are grateful for financial support from the NSF REU Program grant to the Department of Physics & Astronomy at

  11. AN ATTEMPT AT A UNIFIED MODEL FOR THE GAMMA-RAY EMISSION OF SUPERNOVA REMNANTS

    SciTech Connect

    Yuan Qiang; Bi Xiaojun; Liu Siming

    2012-12-20

    Shocks of supernova remnants (SNRs) are important (and perhaps the dominant) agents for the production of the Galactic cosmic rays. Recent {gamma}-ray observations of several SNRs have made this case more compelling. However, these broadband high-energy measurements also reveal a variety of spectral shapes demanding more comprehensive modeling of emissions from SNRs. According to the locally observed fluxes of cosmic-ray protons and electrons, the electron-to-proton number ratio is known to be about 1%. Assuming such a ratio is universal for all SNRs and identical spectral shape for all kinds of accelerated particles, we propose a unified model that ascribes the distinct {gamma}-ray spectra of different SNRs to variations of the medium density and the spectral difference between cosmic-ray electrons and protons observed from Earth to transport effects. For low-density environments, the {gamma}-ray emission is inverse-Compton dominated. For high-density environments like systems of high-energy particles interacting with molecular clouds, the {gamma}-ray emission is {pi}{sup 0}-decay dominated. The model predicts a hadronic origin of {gamma}-ray emission from very old remnants interacting mostly with molecular clouds and a leptonic origin for intermediate-age remnants whose shocks propagate in a low-density environment created by their progenitors via, e.g., strong stellar winds. These results can be regarded as evidence in support of the SNR origin of Galactic cosmic rays.

  12. Characteristics of chylomicron remnant uptake into rat liver.

    PubMed

    Huettinger, M; Retzek, H; Eder, M; Goldenberg, H

    1988-04-01

    We have investigated uptake of 125I-labeled chylomicron remnants into livers of rats in the presence of lactoferrin. This glycoprotein possesses a cluster of four arginines at the N-terminus similar to the arginine rich binding sequence of apoprotein E (apoE) to the LDL-receptor. We found that this protein inhibits uptake of 125I-chylomicron remnant radioactivity by 50% when measured as accumulation of radioactivity into the intact organ, and even more pronounced, over 75%, when measured as uptake into an endosomal fraction prepared therefrom. Provided that the arginine rich sequence is responsible for the inhibition, a similarity in the characteristics of binding of apoE to the LDL (low density lipoprotein)- and chylomicron remnant-receptor is likely. Second, transferrin having sequence homologies with lactoferrin, but lacking the arginine cluster does not interfere with chylomicron remnant uptake. Third, lactoferrin does not inhibit the uptake of chylomicron remnants by the spleen, which is most likely mediated through scavenger cells by a mechanism different from the chylomicron remnant uptake system of the liver. We hypothesize from this that lactoferrin specifically interferes with the physiologically relevant chylomicron remnant uptake system of the liver. Investigation of the mechanism of this inhibition will provide information about the physical characteristics of the remnant receptor system. PMID:3390901

  13. Limitations of automated remnant lipoprotein cholesterol assay for diagnostic use

    Technology Transfer Automated Retrieval System (TEKTRAN)

    I wish to comment on the limitations of automated remnant lipoprotein cholesterol (RemL-C) assay reported in Clinical Chemistry. Remnants are lipoprotein particles produced after newly formed triglyceride-rich lipoproteins (TRLs) of either hepatic or intestinal origin enter the plasma space and unde...

  14. Interstellar and Ejecta Dust in the Cas A Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Arendt, Richard G.; Dwek, Eli; Kober, Gladys; Rho, Jonghee; Hwang, Una

    2013-01-01

    The ejecta of the Cas A supernova remnant has a complex morphology, consisting of dense fast-moving line emitting knots and diffuse X-ray emitting regions that have encountered the reverse shock, as well as more slowly expanding, unshocked regions of the ejecta. Using the Spitzer 5-35 micron IRS data cube, and Herschel 70, 100, and 160 micron PACS data, we decompose the infrared emission from the remnant into distinct spectral components associated with the different regions of the ejecta. Such decomposition allows the association of different dust species with ejecta layers that underwent distinct nuclear burning histories, and determination of the dust heating mechanisms. Our decomposition identified three characteristic dust spectra. The first, most luminous one, exhibits strong emission features at approx. 9 and 21 micron, and a weaker 12 micron feature, and is closely associated with the ejecta knots that have strong [Ar II] 6.99 micron and [Ar III] 8.99 micron emission lines. The dust features can be reproduced by magnesium silicate grains with relatively low MgO-to-SiO2 ratios. A second, very different dust spectrum that has no indication of any silicate features, is best fit by Al2O3 dust and is found in association with ejecta having strong [Ne II] 12.8 micron and [Ne III] 15.6 micron emission lines. A third characteristic dust spectrum shows features that best matched by magnesium silicates with relatively high MgO-to-SiO2 ratio. This dust is primarily associated with the X-ray emitting shocked ejecta and the shocked interstellar/circumstellar material. All three spectral components include an additional featureless cold dust component of unknown composition. Colder dust of indeterminate composition is associated with [Si II] 34.8 micron emission from the interior of the SNR, where the reverse shock has not yet swept up and heated the ejecta. The dust mass giving rise to the warm dust component is about approx. 0.1solar M. However, most of the dust mass

  15. Tongue abscess induced by embedded remnant fishbone.

    PubMed

    Chen, Pai-L; Chiang, C-W; Shiao, C-C

    2015-12-01

    The authors reported a 56-year-old man with progressive pain over left bottom of oral cavity involving tongue for 3 days. He had a puncture history of tongue by fishbone, which was immediately removed 3 weeks ago. The subsequent contrast-enhanced computed tomography scan of neck disclosed an abscess formation with a faint linear radiopaque material inside, consisting with remnant fishbone retention. The patient was treated conservatively with intravenous antibiotics, followed by an uneventful course during subsequent follow-up for more than 9 months until now. Tongue abscess is a rare but potentially life threatening clinical entity. Foreign body puncture-related tongue abscess should be listed as a differential diagnosis in cases with acute tongue swelling. PMID:26790560

  16. Type Ia Progenitor Hunt in Ancient Remnants

    NASA Astrophysics Data System (ADS)

    Kerzendorf, Wolfgang E.

    2013-01-01

    There is broad agreement that the stars which explode as Type Ia supernovae are white dwarfs. They have accreted material in a binary system until they are near the Chandrasekhar mass and detonate/deflagrate. The two main scenarios for this accretion process are merging with a companion white dwarf (double degenerate scenario), or accretion from a main-sequence to red giant donor (single degenerate scenario). The donor star survives post-explosion and would provide substantial evidence for the single degenerate scenario, if found. Our team is analyzing stars in close proximity to Galactic Type Ia remnants to find surviving donor stars. In my talk I will introduce the different progenitor systems and the expected state for a donor star today. I will outline our search using high resolution spectroscopy and will present updated results.

  17. Semiclassical geons as solitonic black hole remnants

    SciTech Connect

    Lobo, Francisco S.N.; Olmo, Gonzalo J.; Rubiera-Garcia, D. E-mail: gonzalo.olmo@csic.es

    2013-07-01

    We find that the end state of black hole evaporation could be represented by non-singular and without event horizon stable solitonic remnants with masses of the order the Planck scale and up to ∼ 16 units of charge. Though these objects are locally indistinguishable from spherically symmetric, massive electric (or magnetic) charges, they turn out to be sourceless geons containing a wormhole generated by the electromagnetic field. Our results are obtained by interpreting semiclassical corrections to Einstein's theory in the first-order (Palatini) formalism, which yields second-order equations and avoids the instabilities of the usual (metric) formulation of quadratic gravity. We also discuss the potential relevance of these solutions for primordial black holes and the dark matter problem.

  18. Multi-Wavelength Observations of Supernova Remnants

    NASA Technical Reports Server (NTRS)

    Williams, B.

    2012-01-01

    Supernova remnants (SNRs) provide a laboratory for studying various astrophysical processes, including particle acceleration, thermal and non thermal emission processes across the spectrum, distribution of heavy elements, the physics of strong shock waves, and the progenitor systems and environments of supernovae. Long studied in radio and X-rays, the past decade has seen a dramatic increase in the detection and subsequent study of SNRs in the infrared and gamma-ray regimes. Understanding the evolution of SNRs and their interaction with the interstellar medium requires a multi-wavelength approach. I will review the various physical processes observed in SNRs and how these processes are intertwined. In particular, I will focus on X-ray and infrared observations, which probe two very different but intrinsically connected phases of the ISM: gas and dust. I will discuss results from multi-wavelength studies of several SNRs at various stages of evolution, including Kepler, RCW 86, and the Cygnus Loop.

  19. Vivid View of Tycho's Supernova Remnant

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This composite image of the Tycho supernova remnant combines infrared and X-ray observations obtained with NASA's Spitzer and Chandra space observatories, respectively, and the Calar Alto observatory, Spain. It shows the scene more than four centuries after the brilliant star explosion witnessed by Tycho Brahe and other astronomers of that era.

    The explosion has left a blazing hot cloud of expanding debris (green and yellow). The location of the blast's outer shock wave can be seen as a blue sphere of ultra-energetic electrons. Newly synthesized dust in the ejected material and heated pre-existing dust from the area around the supernova radiate at infrared wavelengths of 24 microns (red). Foreground and background stars in the image are white.

  20. Black hole remnant from gravity's rainbow

    NASA Astrophysics Data System (ADS)

    Farag Ali, Ahmed

    2014-05-01

    In this work, we investigate black hole (BH) physics in the context of the gravity rainbow. We investigate this through rainbow functions that have been proposed by Amelino-Camelia [Living Rev. Relativity 16, 5 (2013)] and Amelino-Camelia et al. in [Int. J. Mod. Phys. A 12, 607 (1997)]. This modification will give corrections to both the temperature and the entropy of BHs, and hence it changes the picture of Hawking radiation greatly when the size of the BH approaches the Planck scale. It prevents the BH from total evaporation, predicting the existence of a BH remnant, which may resolve the catastrophic behavior of Hawking radiation as the BH mass approaches zero.

  1. Radio flux variation of young supernova remnants

    SciTech Connect

    Ivanov, V.P.; Bubukin, I.T.; Stankevich, K.S.

    1982-01-01

    The 31.5-cm radio flux density of Cas A, the Crab Nebula, and the remnant of the 1572 supernova relative to that of the radio galaxies Cyg A and Vir A was measured in 1981. Comparison with similar observations in 1964 and 1972 shows that over the past decade the decline of the Cas A flux has slowed by a factor 2.2 and now amounts to (0.413 +- 0.08)%/yr. The Crab flux was (3.5 +- 1.0)% weaker in 1981 than in 1964 and 1972; it probably dropped abruptly between 1972 and 1977. For the 1572 SNR the annual mean decline over the 17-yr period is (0.5 +- 0.15)%/yr.

  2. The Origin of Kepler's Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Patnaude, Daniel J.; Badenes, Carles; Park, Sangwook; Laming, J. Martin

    2012-09-01

    It is now well established that Kepler's supernova remnant (SNR) is the result of a Type Ia explosion. With an age of 407 yr and an angular diameter of ~4', Kepler is estimated to be between 3.0 and 7.0 kpc distant. Unlike other Galactic Type Ia SNRs such as Tycho and SN 1006, and SNR 0509-67.5 in the Large Magellanic Cloud, Kepler shows evidence for a strong circumstellar interaction. A bowshock structure in the north is thought to originate from the motion of a mass-losing system through the interstellar medium prior to the supernova. We present results of hydrodynamical and spectral modeling aimed at constraining the circumstellar environment of the system and the amount of 56Ni produced in the explosion. Using models that contain either 0.3 M ⊙ (subenergetic) or 1.0 M ⊙ (energetic) of 56Ni, we simulate the interaction between supernova Ia ejecta and various circumstellar density models. Based on dynamical considerations alone, we find that the subenergetic models favor a distance to the SNR of <6.4 kpc, while the model that produces 1 M ⊙ of 56Ni requires a distance to the SNR of >7 kpc. The X-ray spectrum is consistent with an explosion that produced ~1 M ⊙ of 56Ni, ruling out the subenergetic models, and suggesting that Kepler's SNR was an SN 1991T-like event. Additionally, the X-ray spectrum rules out a pure r -2 wind profile expected from isotropic mass loss up to the time of the supernova. Introducing a small cavity around the progenitor system results in modeled X-ray spectra that are consistent with the observed spectrum. If a wind-shaped circumstellar environment is necessary to explain the dynamics and X-ray emission from the shocked ejecta in Kepler's SNR, then we require that the distance to the remnant be greater than 7 kpc.

  3. Pressure-Distribution Measurements at Large Angles of Pitch on Fins of Different Span-Chord Ratio on a 1/40-Scale Model of the U. S. Airship "Akron."

    NASA Technical Reports Server (NTRS)

    Mchugh, James G

    1937-01-01

    Report presents the results of pressure-distribution measurements on a 1/40-scale model of the U. S. Airship "Akron" conducted in the NACA 20-foot wind tunnel. The measurements were made on the starboard fin of each of four sets of horizontal tail surfaces, all of approximately the same area but differing in span-chord ratio, for five angles of pitch varying from 11.6 degrees to 34 degrees, for four elevator angles, and at air speeds ranging from 56 to 77 miles per hour. Pressures were also measured at 13 stations along the rear half of the port side of the hull at one elevator setting for the same five angles of pitch and at an air speed of approximately 91 miles per hour. The normal force on the fin and the moment of forces about the fin root were determined. The results indicate that, ignoring the effect on drag, it would be advantageous from structural considerations to use a fin of lower span-chord ratio than that used on the "Akron."

  4. Modelling the interaction of thermonuclear supernova remnants with circumstellar structures: the case of Tycho's supernova remnant

    NASA Astrophysics Data System (ADS)

    Chiotellis, A.; Kosenko, D.; Schure, K. M.; Vink, J.; Kaastra, J. S.

    2013-10-01

    The well-established Type Ia remnant of Tycho's supernova (SN 1572) reveals discrepant ambient medium-density estimates based on either the measured dynamics or the X-ray emission properties. This discrepancy can potentially be solved by assuming that the supernova remnant (SNR) shock initially moved through a stellar wind bubble, but is currently evolving in the uniform interstellar medium with a relatively low density. We investigate this scenario by combining hydrodynamical simulations of the wind-loss phase and the SNR evolution with a coupled X-ray emission model, which includes non-equilibrium ionization. For the explosion models we use the well-known W7 deflagration model and the delayed detonation model that was previously shown to provide good fits to the X-ray emission of Tycho's SNR. Our simulations confirm that a uniform ambient density cannot simultaneously reproduce the dynamical and X-ray emission properties of Tycho. In contrast, models that considered that the remnant was evolving in a dense, but small, wind bubble reproduce reasonably well both the measured X-ray emission spectrum and the expansion parameter of Tycho's SNR. Finally, we discuss possible mass-loss scenarios in the context of single- and double-degenerate models which possibly could form such a small dense wind bubble.

  5. Interstellar scattering of compact radio sources near supernova remnants

    NASA Technical Reports Server (NTRS)

    Spangler, S. R.; Mutel, R. L.; Benson, J. M.; Cordes, J. M.

    1986-01-01

    A multifrequency VLBI search for interstellar scattering of extragalactic radio sources near supernova remnants is reported. VLBI observations at 610, 1663, and 4991 MHz were made of compact sources near the supernova remnants CTA 1, G33.6 + 0.1, G74.9 + 1.2, and HB 21, and 610 MHz observations were also made of a source near HB 9. These observations were motivated by the possibility of enhanced cosmic ray-induced turbulence in front of supernova remnants, as expected in 'diffusive' theories of shock wave acceleration. Angular broadening is definitely seen in the case of the source 2013 + 370, which lies within 4 arcmin of the supernova remnant G74.9 + 1.2. Present observations cannot unambiguously attribute the scattering material to the supernova remnant, as the line of sight also passes through the Cygnus OB1 association. The source 1849 + 005 appears to be highly scattered, as fringes were not detected even on short baselines at 5 GHz. This result may be due to the low galactic longitude of this source rather than its proximity to the supernova remnant G 33.6 + 0.1. Broadening was not detected for sources whose lines of sight pass close to the supernova remnants HB 9, HB 21, and CTA 1.

  6. HST/ACS Narrowband Imaging of the Kepler Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Sankrit, Ravi; Blair, William P.; Frattare, Lisa M.; Rudnick, Lawrence; DeLaney, Tracey; Harrus, Ilana M.; Ennis, Jessica A.

    2007-01-01

    We present narrowband images of the Kepler supernova remnant obtained with the Advanced Camera for Surveys aboard the Hubble Space Telescope. The images, with an angular resolution of 0.05" reveal the structure of the emitting gas in unprecedented detail. Radiative and nonradiative shocks are found in close proximity, unresolvable in gromd-based spectra, indicating that the pre-shock medium is highly clumped. The ionization structure, traced by differences in the [0 111] to [N 11] flux ratio, varies on subarcsecond scales. The variation is due to 110th differences in shock velocity as well as gradients in the evolutionary stage of the shocks. A prollinent complex of knots protruding beyond the boundary of the rennallt in the northwest is found to consist of bright radiative knots, collected by arcuate nonradiative filaments. Based on the coincidence of the optical emission with a bright isolated knot of X-ray emission, we infer that this feature is due to a Rayleigh-Taylor finger that formed at the contact discontinuity and overtook the primary blast wave.

  7. Three Great Eyes on Kepler's Supernova Remnant

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site] Composite

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Chandra X-Ray Data (blue) Chandra X-Ray Data (green)Hubble Telescope (visible-light)Spitzer Telescope (infrared)

    NASA's three Great Observatories -- the Hubble Space Telescope, the Spitzer Space Telescope, and the Chandra X-ray Observatory -- joined forces to probe the expanding remains of a supernova, called Kepler's supernova remnant, first seen 400 years ago by sky watchers, including astronomer Johannes Kepler.

    The combined image unveils a bubble-shaped shroud of gas and dust that is 14 light-years wide and is expanding at 4 million miles per hour (2,000 kilometers per second). Observations from each telescope highlight distinct features of the supernova remnant, a fast-moving shell of iron-rich material from the exploded star, surrounded by an expanding shock wave that is sweeping up interstellar gas and dust.

    Each color in this image represents a different region of the electromagnetic spectrum, from X-rays to infrared light. These diverse colors are shown in the panel of photographs below the composite image. The X-ray and infrared data cannot be seen with the human eye. By color-coding those data and combining them with Hubble's visible-light view, astronomers are presenting a more complete picture of the supernova remnant.

    Visible-light images from the Hubble telescope (colored yellow) reveal where the supernova shock wave is slamming into the densest regions of surrounding gas. The bright glowing knots are dense clumps from instabilities that form behind the shock wave. The Hubble data also show thin filaments of gas that look like rippled sheets seen edge-on. These filaments reveal where the shock wave is encountering lower-density, more uniform interstellar material.

    The Spitzer telescope shows microscopic dust particles (colored red) that have been heated by the

  8. Numerical simulations of composite supernova remnants for small σ pulsar wind nebulae

    NASA Astrophysics Data System (ADS)

    Vorster, M. J.; Ferreira, S. E. S.; de Jager, O. C.; Djannati-Ataï, A.

    2013-03-01

    Context. Composite supernova remnants consist of a pulsar wind nebula located inside a shell-type remnant. The presence of a shell has implications on the evolution of the nebula, although the converse is generally not true. Aims: The purpose of this paper is two-fold. The first aim is to determine the effect of the pulsar's initial luminosity and spin-down rate, the supernova ejecta mass, and density of the interstellar medium on the evolution of a spherically-symmetric, composite supernova remnant expanding into a homogeneous medium. The second aim is to investigate the evolution of the magnetic field in the pulsar wind nebula when the the composite remnant expands into a non-uniform interstellar medium. Methods: The Euler conservation equations for inviscid flow, together with the magnetohydrodynamic induction law in the kinematic limit, are solved numerically for a number of scenarios where the ratio of magnetic to particle energy is σ < 0.01. The simulations in the first part of the paper is solved in a one-dimensional configuration. In the second part of the paper, the effect of an inhomogeneous medium on the evolution is studied using a two-dimensional, axisymmetric configuration. Results: It is found that the initial spin-down luminosity and density of the interstellar medium has the largest influence on the evolution of the pulsar wind nebula. The spin-down time-scale of the pulsar only becomes important when this value is smaller than the time needed for the reverse shock of the shell remnant to reach the outer boundary of the nebula. For a remnant evolving in a non-uniform medium, the magnetic field along the boundary of the nebula will evolve to a value that is larger than the magnetic field in the interior. If the inhomogeneity of the interstellar medium is enhanced, while the spin-down luminosity is decreased, it is further found that a magnetic "cloud" is formed in a region that is spatially separated from the position of the pulsar.

  9. Electron acceleration by young supernova remnant blast waves

    NASA Technical Reports Server (NTRS)

    Blandford, R. D.

    1992-01-01

    Some general considerations regarding relativistic particle acceleration by young supernova remnants are reviewed. Recent radio observations of supernova remnants apparently locate the bounding shock and exhibit large electron density gradients which verify the presence of strong particle scattering. The radio 'rim' in Tycho's remnant has been found to contain a predominantly radial magnetic field. This may be attributable to an instability of the shock surface and a progress report on an investigation of the stability of strong shocks in partially ionized media is presented.

  10. Remnant cystic duct adenocarcinoma presenting as gastric outlet obstruction

    PubMed Central

    Lo, Samuel Tsoon Wuan; Cheng, Yue; Cheung, Frances; Tang, Chung Ngai

    2016-01-01

    Only a few case reports of remnant cystic duct carcinoma exist. The presented case of remnant cystic duct carcinoma with invasion to pylorus and bulbus of duodenum leading to gastric outlet obstruction was the first of its kind. We reviewed all cases of remnant cystic duct carcinoma that we found in the literature and summarized its definition, presentation, extent of invasion and clinical outcome after operation. The diagnosis can be difficult due to the rarity of disease, locally advanced nature of disease and distorted postoperative anatomy. A high index of suspicion can increase the likelihood of a preoperative diagnosis. PMID:27154747

  11. 2 MASS Near-Infrared Imaging of the Supernova Remnant IC443

    NASA Astrophysics Data System (ADS)

    Rho, J.; van Dyk, S.; Jarrett, T.; Cutri, R.; Reach, W.

    1999-05-01

    We present near-infrared imaging of IC443, covering the entire supernova remnant (50' diameter) from The Two Micron All Sky Survey (2MASS). 2MASS imaging is taken simultaneously in the J (1.25mu m), H (1.65mu m) and K_s (2.17mu m) bands using a 1.3 m telescope with a three-channel camera. The images have 3.5'' spatial resolution with a pixel size of 1''. The bands include lines of Pbeta , [Ni II] and [Fe II] for J band, Br10 and [Fe II] for H band, and Brgamma and H_2 for K_s band. Emission from IC443 was detected in all 3 bands from most of the optically bright parts of the remnant, revealing a shell-like morphology. This is the first near-infrared image of the northeastern and eastern parts. The color and structure are very different between the northeastern and southern parts. The northeastern shell shows sheet-like filamentary structure, similar to that of optical emission, with J and H band emission equivalently bright, and weak K_s emission. The H flux is higher than the K flux in the northeast; its ratio is similar order of magnitude to that of previously measured infrared spectroscopy from 2 positions. The ratio implies that the H band emission from the northeastern shell is mostly [Fe II] (1.64mu m), and the [Fe II] emission is much stronger than Brgamma . This contrasts to the ratio of 0.06 observed in H II regions. The strong [Fe II] line is produced not only by efficient excitation of Fe but also by grain destruction. Most of bright J band emission can be explained by hydrogen line of Pbeta (1.28mu m) when we estimate the expected intensity relative to Brgamma and Hα . In contrast, the south ridge is dominated by K_s band light with knotty structure, and has weak J and H band emission. The shocked H_2 line emission is well known from the sinus ridge produced by an interaction with dense molecular clouds. The large field of view of the 2MASS image shows that the H_2 emission extends to the east and inner shell of northeastern optical emission, which is

  12. Supernova remnants and diffuse ionized gas in M31

    NASA Astrophysics Data System (ADS)

    Walterbos, Rene; Braun, Robert

    1990-07-01

    Researchers have compiled an initial list of radio/optical supernova remnants (SNRs) in M31, by searching for radio identifications of emission-line sources with a high (SII)/H alpha ratio (greater than 0.60). The (SII) filter included both sulfur lines and the H alpha filter did not include (NII). This search revealed 11 SNRs, of which only two were known. In addition, researchers detected radio emission from 3 SNRs that were identified in previous optical surveys (D'Odorico et al., 1980), but that were outside the charge coupled device (CCD) fields. The 14 objects only include the most obvious candidates, but a full search is in progress and the researchers expect to find several more SNRs. Also not all optical SNRs show detectable radio emission and a pure optical list of SNR candidates based only on the ratio of (SII)/H alpha emission contains many more objects. Two conclusions are apparent. First, the radio properties of the SNRs in M31 are quite similar to those of Galactic SNRs as is illustrated. The brightnesses are not systematically lower as has been suggested in the past (Dickel and D'Odorico, 1984). Second, the slope of the relation is close to -2; this slope is expected from the intrinsic dependence between surface brightness and diameter. The radio luminosity of the SNRs does not seem to depend strongly on diameter, or age, contrary to model predictions. Selection effects, however, play an important role in these plots. The CCD images show widespread diffuse ionized gas with a ratio of (SII)/H alpha that is higher than that of discrete HII regions. Discrete HII regions typically show ratios between 0.2 to 0.3, while the diffuse gas in the arms consistently shows ratios of 0.5. Researchers can trace this gas across the spiral arms to emission measures below 5 pc cm (-6). Its properties seem to be similar to that of the diffuse gas in the solar neighborhood.

  13. A CHANDRA X-RAY SURVEY OF EJECTA IN THE CASSIOPEIA A SUPERNOVA REMNANT

    SciTech Connect

    Hwang, Una; Laming, J. Martin E-mail: laming@nrl.navy.mil

    2012-02-20

    We present a survey of the X-ray-emitting ejecta in the Cassiopeia A supernova remnant (SNR) based on an extensive analysis of over 6000 spectral regions extracted on 2.''5-10'' angular scales using the Chandra 1 Ms observation. We interpret these results in the context of hydrodynamical models for the evolution of the remnant. The distributions of fitted temperature and ionization age, and the implied mass coordinates, are highly peaked and suggest that the ejecta were subjected to multiple secondary shocks following reverse shock interaction with ejecta inhomogeneities. Based on the fitted emission measure and element abundances, and an estimate of the emitting volume, we derive masses for the X-ray-emitting ejecta and also show the distribution of the mass of various elements over the remnant. An upper limit to the total shocked Fe mass visible in X-rays appears to be roughly 0.13 M{sub Sun }, which accounts for nearly all of the mass expected in Fe ejecta. We find two populations of Fe ejecta, that associated with normal Si burning and that possibly associated with {alpha}-rich freezeout, with a mass ratio of approximately 2:1. Essentially all of the observed Fe (both components) lies well outside the central regions of the SNR, possibly having been ejected by hydrodynamic instabilities during the explosion. We discuss this and its implications for the neutron star kick.

  14. A Chandra X-Ray Survey of Ejecta in the Cassiopeia A Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Hwang, Una; Laming, J. Martin

    2011-01-01

    We present a survey of the X-ray emitting ejecta in the Cassiopeia A supernova remnant based on an extensive analysis of over 6000 spectral regions extracted on 2.5-10" angular scales using the Chandra 1 Ms observation. We interpret these results in the context of hydrodynamical models for the evolution of the remnant. The distributions of fitted temperature and ionization age are highly peaked and suggest that the ejecta were subjected to multiple secondary shocks. Based on the fitted emission measure and element abundances, and an estimate of the emitting volume, we derive masses for the X-ray emitting ejecta as well as showing the distribution of the mass of various elements over the remnant. The total shocked Fe mass appears to be roughly 0.14 Solar Mass, which accounts for nearly all of the mass expected in Fe ejecta. We find two populations of Fe ejecta, that associated with normal Si-burning and that associated with alpha-rich freeze-out, with a mass ratio of approximately 2:1. Surprisingly, essentially all of this Fe (both components) is well outside the central regions of the SNR, presumably having been ejected by hydrodynamic instabilities during the explosion. We discuss this, and its implications for the neutron star kick.

  15. Interstellar and ejecta dust in the cas a supernova remnant

    SciTech Connect

    Arendt, Richard G.; Dwek, Eli; Kober, Gladys; Rho, Jeonghee; Hwang, Una

    2014-05-01

    Infrared continuum observations provide a means of investigating the physical composition of the dust in the ejecta and swept up medium of the Cas A supernova remnant (SNR). Using low-resolution Spitzer IRS spectra (5-35 μm), and broad-band Herschel PACS imaging (70, 100, and 160 μm), we identify characteristic dust spectra, associated with ejecta layers that underwent distinct nuclear burning histories. The most luminous spectrum exhibits strong emission features at ∼9 and 21 μm and is closely associated with ejecta knots with strong Ar emission lines. The dust features can be reproduced by magnesium silicate grains with relatively low Mg to Si ratios. Another dust spectrum is associated with ejecta having strong Ne emission lines. It has no indication of any silicate features and is best fit by Al{sub 2}O{sub 3} dust. A third characteristic dust spectrum shows features that are best matched by magnesium silicates with a relatively high Mg to Si ratio. This dust is primarily associated with the X-ray-emitting shocked ejecta, but it is also evident in regions where shocked interstellar or circumstellar material is expected. However, the identification of dust composition is not unique, and each spectrum includes an additional featureless dust component of unknown composition. Colder dust of indeterminate composition is associated with emission from the interior of the SNR, where the reverse shock has not yet swept up and heated the ejecta. Most of the dust mass in Cas A is associated with this unidentified cold component, which is ≲ 0.1 M {sub ☉}. The mass of warmer dust is only ∼0.04 M {sub ☉}.

  16. MODIFIED EQUIPARTITION CALCULATION FOR SUPERNOVA REMNANTS

    SciTech Connect

    Arbutina, B.; Urosevic, D.; Andjelic, M. M.; Pavlovic, M. Z.; Vukotic, B.

    2012-02-10

    Determination of the magnetic field strength in the interstellar medium is one of the more complex tasks of contemporary astrophysics. We can only estimate the order of magnitude of the magnetic field strength by using a few very limited methods. Besides the Zeeman effect and Faraday rotation, the equipartition or minimum-energy calculation is a widespread method for estimating magnetic field strength and energy contained in the magnetic field and cosmic-ray particles by using only the radio synchrotron emission. Despite its approximate character, it remains a useful tool, especially when there are no other data about the magnetic field in a source. In this paper, we give a modified calculation that we think is more appropriate for estimating magnetic field strengths and energetics in supernova remnants (SNRs). We present calculated estimates of the magnetic field strengths for all Galactic SNRs for which the necessary observational data are available. The Web application for calculation of the magnetic field strengths of SNRs is available at http://poincare.matf.bg.ac.rs/{approx}arbo/eqp/.

  17. Further analysis of LDEF FRECOPA micrometeoroid remnants

    NASA Technical Reports Server (NTRS)

    Borg, Janet; Bunch, Ted E.; Radicatidibrozolo, Filippo; Mandeville, Jean Claude

    1993-01-01

    In the Al collectors of experiment A0138-1 of the French Cooperative Payload (FRECOPA) payload, we identified a population of small craters (3-9 microns in diameter) induced by the impacts of micron-sized grains, mainly of extraterrestrial origin. Chemical analyses of the Interplanetary Dust Particle (IDP) remnants were made in the bottoms and on the rims of the craters, in addition to immediate off-rim areas. So far, the compositional investigation of the craters by Energy Dispersive Spectroscopy (EDS) has shown evidence of an extraterrestrial origin for the impacting grains. The systematic presence of C and O in the residues has been reported and may be compared with the existence of particles showing high proportions of biogenic light elements and detected in the close environment of P-Halley comet nucleus (called CHON particles). An analytical protocol has been established in order to extract molecular and possible isotopic information on these grains, a fraction of which could be of cometary origin. Although these very small craters may show crater features that are typical of the larger Long Duration Exposure Facility (LDEF) population (greater than 50 microns), some show unique morphologies that we have not previously observed. Our initial Laser Induced Mass Spectrometry (LIMS) analytical results show strong signals for nitrogen-bearing ions in craters characterized by high C and O contents; they also suggest that carbon contents in some craters could exceed that known for carbonaceous chondrites.

  18. LIMITS ON THE NUMBER OF GALACTIC YOUNG SUPERNOVA REMNANTS EMITTING IN THE DECAY LINES OF {sup 44}Ti

    SciTech Connect

    Dufour, François; Kaspi, Victoria M.

    2013-09-20

    We revise the assumptions of the parameters involved in predicting the number of supernova remnants detectable in the nuclear lines of the decay chain of {sup 44}Ti. Specifically, we consider the distribution of the supernova progenitors, the supernova rate in the Galaxy, the ratios of supernova types, the Galactic production of {sup 44}Ti, and the {sup 44}Ti yield from supernovae of different types to derive credible bounds on the expected number of detectable remnants. We find that, within 1σ uncertainty, the Galaxy should contain an average of 5.1{sup +2.4}{sub -2.0} remnants detectable to a survey with a {sup 44}Ti decay line flux limit of 10{sup –5} photons cm{sup –2} s{sup –1}, with a probability of detecting a single remnant of 2.7{sup +10.0}{sub -2.4}%, and an expected number of detections between two and nine remnants, making the single detection of Cas A unlikely but consistent with our models. Our results show that the probability of detecting the brightest {sup 44}Ti flux source at the high absolute Galactic longitude of Cas A or above is ∼10%. Using the detected flux of Cas A, we attempt to constrain the Galactic supernova rate and Galactic production of {sup 44}Ti, but find the detection to be only weakly informative. We conclude that even future surveys having 200 times more sensitivity than state-of-the-art surveys can be guaranteed to detect only a few new remnants, with an expected number of detections between 8 and 21 at a limiting {sup 44}Ti decay flux of 10{sup –7} photons cm{sup –2} s{sup –1}.

  19. Measuring Changes in the Vicinity of the Seal Nunataks Ice Shelf Remnant from Imagery and Altimetry

    NASA Astrophysics Data System (ADS)

    Shuman, C. A.; Berthier, E.; Scambos, T.

    2015-12-01

    Analysis of repeated imagery and ICESat laser altimetry has enabled the ongoing losses from the northern Larsen ice shelf remnant to be assessed in detail. The remnant, the Seal Nunataks ice shelf (SNIS), has four ICESat tracks that cross it as well as adjacent tracks that cross Robertson Island (RI) and its remaining tributary, Rogosh Glacier (RG), on the Antarctic Peninsula. The altimetry data from ICESat (2003-2009) shows that elevation losses increase from west to east across the SNIS. Ice elevation differences suggest mean ice shelf thinning rates of up to 1.6 m a-1 and reveal processes impacting the remaining shelf ice as well. Limited altimetry data across RG suggests elevation losses of almost 1 m a-1 inland from the grounding zone with smaller losses further up the evolving tributary. Farther east, asymmetric elevation changes across RI suggest the magnitude of regional climate impacts vary distinctly depending on slope aspect. Imagery analysis using Landsat 7 and ASTER images from 2001-2013 shows that ice area losses continued on the shelf remnant following the Larsen A break up in 1995 as well as after the Larsen B break up in 2002. The largest losses (~350 km2) occurred on the north side of the remnant in late 2004 into 2005 with smaller losses along the remaining margins. Despite a slight regional cooling recently and more persistent sea ice since early 2008 as seen in MODIS imagery, the SNIS is still losing ice along its margins and appears to be retreating past its pinning nunataks. In contrast to SNIS, RI has experienced minor ice area losses that suggest most of its ice is grounded and thus less directly impacted by ocean interactions. Combining these remote sensing data sets provides additional insights about ongoing ice loss processes in this part of the Antarctic Peninsula.

  20. 11. REMNANTS OF FLUME BOX WITHIN CANAL. NOTE THE UPRIGHT ...

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

    11. REMNANTS OF FLUME BOX WITHIN CANAL. NOTE THE UPRIGHT SIDE POSTS BOLTED TO BASE STRINGER AND HORIZONTAL BOARD SIDE WALLS. VIEW IS TO THE SOUTHEAST. - Snake River Ditch, Headgate on north bank of Snake River, Dillon, Summit County, CO

  1. Remnants of track girder of east roadbed showing detail of ...

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

    Remnants of track girder of east roadbed showing detail of granite piers at low tide. View north - New York, New Haven & Hartford Railroad, Fort Point Channel Rolling Lift Bridge, Spanning Fort Point Channel, Boston, Suffolk County, MA

  2. 3. HISTORIC ROADWAY 2 WITH MILL REMNANTS TO THE RIGHT ...

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

    3. HISTORIC ROADWAY 2 WITH MILL REMNANTS TO THE RIGHT OF TREE. CAMERA POINTED WEST-SOUTHWEST. - Florida Mountain Mining Sites, Historic Roadway No. 2, West flank Florida Mountain, East of Rich Gulch Mine & Mill, Silver City, Owyhee County, ID

  3. Western end of ATSF rail yard with remnant of rail ...

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

    Western end of ATSF rail yard with remnant of rail spur and dumping location. Concrete vault foundation in foreground. Stone foundation and wood foundation in background. - Grand Canyon Village Utilities, Grand Canyon National Park, Grand Canyon Village, Coconino County, AZ

  4. Detail, corner pilaster remnant, gable return on facade, Our Corner ...

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

    Detail, corner pilaster remnant, gable return on facade, Our Corner Saloon, view to northeast (210mm lens with electronic flash fill) - Our Corner Saloon, 301 First Street, Eureka, Humboldt County, CA

  5. Hematite Mineralized Bacterial Remnants: Implications for Martian Hematite Deposits

    NASA Technical Reports Server (NTRS)

    Schelble, Rachel T.; Westall, Frances; Allen, Carlton C.; Brearley, Adrian J.

    2001-01-01

    Hematite mineralized bacterial remnants in the Gunflint Formation [early Proterozoic] can be used as an analog for potential microfossils in martian iron deposits. Additional information is contained in the original extended abstract.

  6. FEATURE C. MACHINE GUN POSITION WITH REMNANT OF MOUNT, VIEW ...

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

    FEATURE C. MACHINE GUN POSITION WITH REMNANT OF MOUNT, VIEW FACING SOUTH-SOUTHEAST. - Naval Air Station Barbers Point, Battery-Machine Gun Positions, South of Point Cruz Road & west of Coral Sea Road, Ewa, Honolulu County, HI

  7. Energy of Tycho's Supernova Remnant is increasing with time

    PubMed Central

    Barenblatt, Grigory Isaakovich

    2008-01-01

    It is shown, using the Zeldovich integral relations, that the energy of Tycho's Supernova Remnant is strongly growing with time, approximately as t1/3. This growth can be attributed to the exothermic reactions going inside the remnant. The use of the assumption of the adiabaticity of the motion inside of the shock front, and no losses or gain of energy at the front, seems therefore unjustified. PMID:18202174

  8. Ectopic endometrial tissue in mesonephric duct remnants in bitches.

    PubMed

    Bartel, C; Berghold, P; Walter, I

    2011-12-01

    Common congenital embryonic remnants of the canine female genital tract are Gartner cysts originating from mesonephric duct remnants. They can increase in size and lead to adverse effects in fertility and health. In the present study, three cases of mesonephric remnants in bitches were analysed. The mesonephric remnants featured an inner lining endometrium comprising surface epithelium, glands and stroma. This ectopic endometrium was further characterized by immunohistochemistry (oestrogen and progesterone receptors, proliferation activity, cytokeratin, alpha smooth muscle actin, and vimentin) and lectin histochemistry compared with normal uterine endometrium. Furthermore, hypertrophic cells at the serosal site of the uteri were detected and analysed in the same way compared with normal serosa. The ectopic endometrium of case no. 2 mesonephric remnant was comparable with normal endometrium whereas in nos 1 and 3 uteri the ectopic endometrium was reduced in thickness. In all mesonephric remnants, surface and glandular epithelial cells of the ectopic endometrium gave positive immunoreactions for cytokeratin, oestrogen and progesterone receptors and showed lectin-binding patterns comparable with normal endometrium. Some of the stromal cells of the ectopic endometria were smooth muscle actin and vimentin positive. Mitotic activity of the ectopic endometria was comparable with normal endometria. Hypertrophic epithelial cells of the serosal side showed positive reactions to anti-oestrogen receptor and anti-cytokeratin immunohistochemistry as well as lectin binding patterns and mitotic activity comparable with the normal canine serosa. The present study is the first considerable immunohistochemical characterization of canine mesonephric remnants and discusses the appearance of ectopic endometrium in mesonephric remnants. PMID:21366719

  9. Black hole remnants and the information loss paradox

    NASA Astrophysics Data System (ADS)

    Chen, P.; Ong, Y. C.; Yeom, D.-h.

    2015-11-01

    Forty years after the discovery of Hawking radiation, its exact nature remains elusive. If Hawking radiation does not carry any information out from the ever shrinking black hole, it seems that unitarity is violated once the black hole completely evaporates. On the other hand, attempts to recover information via quantum entanglement lead to the firewall controversy. Amid the confusions, the possibility that black hole evaporation stops with a "remnant" has remained unpopular and is often dismissed due to some "undesired properties" of such an object. Nevertheless, as in any scientific debate, the pros and cons of any proposal must be carefully scrutinized. We fill in the void of the literature by providing a timely review of various types of black hole remnants, and provide some new thoughts regarding the challenges that black hole remnants face in the context of the information loss paradox and its latest incarnation, namely the firewall controversy. The importance of understanding the role of curvature singularity is also emphasized, after all there remains a possibility that the singularity cannot be cured even by quantum gravity. In this context a black hole remnant conveniently serves as a cosmic censor. We conclude that a remnant remains a possible end state of Hawking evaporation, and if it contains large interior geometry, may help to ameliorate the information loss paradox and the firewall controversy. We hope that this will raise some interests in the community to investigate remnants more critically but also more thoroughly.

  10. Fluid dynamics nature of supernova remnant (Crab Nebula)

    NASA Astrophysics Data System (ADS)

    Estakhr, Ahmad Reza

    2015-04-01

    Supernova remnant (at early phase) is a high temperature fluid of gas and dust. after the explosion of a star in a supernova, the viscousity of supernova remnant changes with temperature. as supernova expand by time its temperature decreases and the viscousity increases, (or alternatively, the fluidity of supernova remnant tends to decreases) and leb to resistance phase of supernova remnant fluid to flow. Uμ = γ (c , u (r-> , t)) denotes four-velocity vector field of supernova. Jμ = ρUμ denotes four-current density of supernova fluid of gas and dust. Estakhr's Material-Geodesic equation is developed analogy of Navier Stokes equation and Einstein Geodesic equation to describe Fluid dynamics nature of supernova remnant (Crab Nebula): DJμ/Dτ =dJμ/Dτ + ΓαβμJαUβ =JνΩμν +∂νTμν + ΓαβμJαUβ Covariant formulation of Fluid dynamics nature of supernova remnant, describe the motion of fluid substances of supernova.

  11. Supernova Remnants, Cosmic Rays, and GLAST

    SciTech Connect

    Reynolds, Steve

    2006-02-13

    The shock waves of supernova remnants (SNRs) are the traditional sources of Galactic cosmic rays, at least up to about 3000 TeV (the 'knee' energy in the cosmic-ray spectrum). In the last decade or so, X-ray observations have confirmed in a few SNRs the presence of synchrotron-X-ray-emitting electrons with energies of order 100 TeV. TeV photons from SNRs have been observed with ground-based air Cerenkov telescopes as well, but it is still unclear whether they are due to hadronic processes (inelastic p-p scattering of cosmic-ray protons from thermal gas, with secondary neutral pions decaying to gamma rays), or to leptonic processes (inverse-Compton upscattering of cosmic microwave background photons, or bremsstrahlung). The spatial structure of synchrotron X-rays as observed with the Chandra X-ray Observatory suggests the remarkable possibility that magnetic fields are amplified by orders of magnitude in strong shock waves. The electron spectra inferred from X-rays reach 100 TeV, but at that energy are cutting off steeply, well below the 'knee' energy. Are the cutoff processes due only to radiative losses so that ion spectra might continue unsteepened? Can we confirm the presence of energetic ions in SNRs at all? Are typical SNRs capable of supplying the pool of Galactic cosmic rays? Is strong magnetic-field amplification a property of strong astrophysical shocks in general? These major questions require the next generation of observational tools. I shall outline the theoretical and observational framework of particle acceleration to high energies in SNRs, and shall describe how GLAST will advance this field.

  12. Supernova Remnants, Cosmic Rays, and GLAST

    SciTech Connect

    Reynolds, Steve

    2006-02-13

    The shock waves of supernova remnants (SNRs) are the traditional sources of Galactic cosmic rays, at least up to about 3000 TeV (the "knee" energy in the cosmic-ray spectrum). In the last decade or so, X-ray observations have confirmed in a few SNRs the presence of synchrotron-X-ray-emitting electrons with energies of order 100 TeV. TeV photons from SNRs have been observed with ground-based air Cerenkov telescopes as well, but it is still unclear whether they are due to hadronic processes (inelastic p-p scattering of cosmic-ray protons from thermal gas, with secondary neutral pions decaying to gamma rays), or to leptonic processes (inverse-Compton upscattering of cosmic microwave background photons, or bremsstrahlung). The spatial structure of synchrotron X-rays as observed with the Chandra X-ray Observatory suggests the remarkable possibility that magnetic fields are amplified by orders of magnitude in strong shock waves. The electron spectra inferred from X-rays reach 100 TeV, but at that energy are cutting off steeply, well below the "knee" energy. Are the cutoff processes due only to radiative losses so that ion spectra might continue unsteepened? Can we confirm the presence of energetic ions in SNRs at all? Are typical SNRs capable of supplying the pool of Galactic cosmic rays? Is strong magnetic-field amplification a property of strong astrophysical shocks in general? These major questions require the next generation of observational tools. I shall outline the theoretical and observational framework of particle acceleration to high energies in SNRs, and shall describe how GLAST will advance this field.

  13. Shock Destruction of Dust in Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Shull, J.

    2009-07-01

    In this AR-Theory program, we propose to carry out a series of investigations of grain injection, transport, and destruction using hydrodynamical models of reverse-shocked SN ejecta. In a young supernova remnant {SNR} such as Cas A or SN 1987A the outer blast wave strikes surrounding circumstellar matter, and reverse shocks propagate inward toward the interior debris, which may contain large amounts of newly formed dust. Our major theoretical goals are to determine how much dust is destroyed in shocked SNR ejecta, as they are decelerated by the reverse shocks, and to study how these ejecta are lighted up in optical, X-ray, andIR line emission. Numerical codes will be used to study grain destruction in metal-enriched ejecta and to interpret the morphologies, proper motions, and emissivities of these fast-moving ejecta, observed by Hubble in many young SNRs. We intend to undertake the following tasks: {1} Compile the latest gas-grain data {sputtering yields vs projectile energy for H, He, and heavy ions}; {2} Incorporate gas-grain and grain-grain interactions with radiative cooling rates {X-ray, optical, IR line emission} of sputtered atoms and ions; {3} Compute adaptive-mesh hydrodynamical models of ejecta-shock interactions; {4} Use these ejecta models to compute grain destruction, grain heating, plasma cooling, and spectral diagnostics in metal-enriched environments; {5} Apply our results to specific SNRs {Cas A, SN 1987A, G292, etc} to interpret ejecta morphologies, proper motions, and emissivities; {6} assess the net efficiency of supernova dust injection.

  14. Gamma-Ray Observations of Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Buckley, James

    2000-04-01

    Despite the growing evidence for shock acceleration of electrons in supernova remnants (SNR), there is still no direct evidence pointing unambiguously to SNR as sources of cosmic-ray nuclei. Observations of nonthermal synchrotron emission in the limbs of a number of shell-type SNR (SN1006, Tycho, Cas A, IC443, RCW86, and Kepler) provide convincing evidence for acceleration of electrons to energies greater than 10 TeV (Allen 1999). The CANGAROO group has now reported significant VHE gamma-ray emission from SN1006 (Tanimori et al. 1998) and RXJ1713-3946, and the HEGRA group has reported preliminary evidence for TeV emission from Cas A (Pülhofer et al. 1999); all of these measurements are consistent with the expected level of inverse-Compton emission in these objects. Following the predictions of an observable π^0-decay signal from nearby SNRs (e.g., Drury, Aharonian and Volk 1994) the discovery of >100 MeV emission from the direction of a number of SNR by the EGRET experiment (Esposito et al. 1996) and possible evidence for a π^0 component (Gaisser, Protheroe and Stanev 1996) led to some initial optimism that evidence for a SNR origin of cosmic-ray nuclei had been obtained. However, 200 GeV to 100 TeV measurements revealed no significant emission implying either a significantly steeper source spectrum than the canonical ~ E-2.1, a spectral cutoff below the knee energy in these sources, or that a re-interpretation of the EGRET results was required. I will discuss these results, as well as the considerable promise of future gamma-ray experiments to determine the sources of galactic cosmic-ray nuclei and to provide quantitative information about the acceleration mechanisms.

  15. Transport of magnetic turbulence in supernova remnants

    NASA Astrophysics Data System (ADS)

    Brose, R.; Telezhinsky, I.; Pohl, M.

    2016-08-01

    Context. Supernova remnants are known as sources of Galactic cosmic rays for their nonthermal emission of radio waves, X-rays, and gamma rays. However, the observed soft broken power-law spectra are hard to reproduce within standard acceleration theory based on the assumption of Bohm diffusion and steady-state calculations. Aims: We point out that a time-dependent treatment of the acceleration process together with a self-consistent treatment of the scattering turbulence amplification is necessary. Methods: We numerically solve the coupled system of transport equations for cosmic rays and isotropic Alfvénic turbulence. The equations are coupled through the growth rate of turbulence determined by the cosmic-ray gradient and the spatial diffusion coefficient of cosmic rays determined by the energy density of the turbulence. The system is solved on a comoving expanding grid extending upstream for dozens of shock radii, allowing for the self-consistent study of cosmic-ray diffusion in the vicinity of their acceleration site. The transport equation for cosmic rays is solved in a test-particle approach. Results: We demonstrate that the system is typically not in a steady state. In fact, even after several thousand years of evolution, no equilibrium situation is reached. The resulting time-dependent particle spectra strongly differ from those derived assuming a steady state and Bohm diffusion. Our results indicate that proper accounting for the evolution of the scattering turbulence and hence the particle diffusion coefficient is crucial for the formation of the observed soft spectra. In any case, the need to continuously develop magnetic turbulence upstream of the shock introduces nonlinearity in addition to that imposed by cosmic-ray feedback.

  16. Uptake of remnant like particles (RLP) in diabetic patients from mouse peritoneal macrophages.

    PubMed

    Tomono, S; Kawazu, S; Kato, N; Ono, T; Ishii, C; Ito, Y; Shimizu, M; Shimoyama, M; Nakano, T; Nakajima, K

    1994-01-01

    To investigate whether the remnant like particles (RLP), separated from serum by an immunoaffinity gel mixture of anti-apo B-100 and apo A-I monoclonal antibodies, are relevant to the initiation or progression of atherosclerosis, the incorporation of RLP into mouse macrophages was studied using histochemical and biochemical techniques. Remnant lipoproteins such as RLP are reported to contain a large quantity of chyloniron and very low density lipoprotein (VLDL) remnants, especially in diabetic patients. The RLP separated from the sera of 32 diabetic patients were found to be predominantly taken up into macrophages harvested from mouse abdominal cavities by the staining method applying oil red O. Furthermore, using 14C-oleate to prove the uptake of lipoproteins by macrophages, the uptake of RLP-VLDL, a VLDL fraction of RLP by ultracentrifugation, was the next highest to that of the oxidized LDL, which suggests that RLP-VLDL is also aggressively taken up by macrophages. The degree of uptake of RLP-VLDL by macrophages was positively correlated with HbA1c of these diabetic patients (r = 0.556, p < 0.01), irrespective of the ways of the treatment of diabetes. In conclusion, RLP can contribute to the foaming of macrophages, which in turn may explain the acceleration of atherosclerosis in diabetic patients. PMID:9222876

  17. High-Resolution X-Ray Spectroscopy of the Galactic Supernova Remnant Puppis A with the XMM-Newton RGS

    NASA Technical Reports Server (NTRS)

    Katsuda, Satoru; Tsunemi, Hiroshi; Mori, Koji; Uchida, Hiroyuki; Petre, Robert; Yamada, Shinya; Akamatsu, Hiroki; Konami, Saori; Tamagawa, Toru

    2012-01-01

    We present high-resolution X-ray spectra of cloud-shock interaction regions in the eastern and northern rims of the Galactic supernova remnant Puppis A, using the Reflection Grating Spectrometer onboard the XMM-Newton satellite. A number of emission lines including K(alpha) triplets of He-like N, O , and Ne are clearly resolved for the first time. Intensity ratios of forbidden to resonance lines in the triplets are found to be higher than predictions by thermal emission models having plausible plasma parameters. The anomalous line ratios cannot be reproduced by effects of resonance scattering, recombination, or inner-shell ionization processes, but could be explained by charge-exchange emission that should arise at interfaces between the cold/warm clouds and the hot plasma. Our observations thus provide observational support for charge-exchange X-ray emission in supernova remnants.

  18. Relationship Between Alcohol Drinking and Aspartate Aminotransferase:Alanine Aminotransferase (AST:ALT) Ratio, Mean Corpuscular Volume (MCV), Gamma-Glutamyl Transpeptidase (GGT), and Apolipoprotein A1 and B in the U.S. Population*

    PubMed Central

    Liangpunsakul, Suthat; Qi, Rong; Crabb, David W.; Witzmann, Frank

    2010-01-01

    Objective: The misuse of alcohol, even at levels just above two drinks per day, is a public health problem, but identifying patients with this potentially unhealthy drinking is hindered by the lack of tests. Several blood tests, such as those testing for gamma-glutamyl transpeptidase (GGT) or mean corpuscular volume (MCV), are among the commonly used markers to identify very heavy drinking, but combinations of these markers have rarely been tested in lighter drinkers. We examined the relationship between alcohol drinking and the levels of these markers in a national population-based study composed primarily of lighter drinkers. Method: Data were analyzed from 8,708 adult participants in the third U.S. National Health and Nutrition Examination Survey after excluding subjects with iron overload; with hepatitis B and C; who were pregnant; and who were taking prescription drugs such as phenytoin (Dilantin), barbiturates, and hydroxyurea (Droxia and Hydrea). The relationship between the amount of alcohol drinking and GGT, aspartate aminotransferase:alanine aminotransferase ratio, MCV of erythrocytes, and apolipoprotein A1 and B were analyzed and adjusted for potential liver injury risk factors. Results: The prevalence of unhealthy alcohol drinking (defined as consumption of more than two standard drinks per day) was 6.7%. Heavier drinkers tended to be younger and reported an average of 4.2 drinks per day. When tested alone or in combination, the sensitivity and positive predictive values for these blood tests were too low to be clinically useful in identifying the subjects in the heavier drinking category. Conclusions: In this large, national, population-based study, the markers of heavy drinking studied here, either alone or in combination, did not appear to be useful in identifying unhealthy drinking. More work is needed to find the novel marker(s) associated with risky alcohol drinking. PMID:20230722

  19. The Shock Structure of Supernova Remnant IC443

    NASA Technical Reports Server (NTRS)

    Haas, Michael R.; Higdon, S. J. U.; Burton, M. G.; Hollenbach, D. J.; Fonda, Mark (Technical Monitor)

    2003-01-01

    We present and discuss ISO observations of IC443, a supernova remnant interacting with a molecular cloud. An SWS spectrum centered on molecular hydrogen clump R10E (RA(2000) = 6 17 7.6, Decl(2000) = 22 25 34.6) is dominated by strong [SiII] (34 microns) emission and the pure rotational transitions of molecular hydrogen ranging from 0-0 S(1) to 0-0 S(13). Fits to these H$-2$ lines imply a large column (approx. 7E19 cm$ {-2)$) of warm (T approx. 700 K) gas and an ortho/para ratio for hydrogen near 3. LWS Fabry-Perot spectra of [OI] (63 microns) and [CII] (158 microns) at positions R10E and C (RA(2000) = 6 17 42.8, Decl(2000) = 22 21 38.1) find broad (approx. 75 km/s), blue-shifted (-40 km/s) line profiles; their similarity strongly suggests a common, shock-generated origin for these two lines. The surprisingly large [CII]/[OI] ratio (approx. 0.1 to 0.2) confirms previous observations with the Kuiper Airborne Observatory. These [CII] and [OI] line intensities, the [SiII] intensity (above), and LWS grating measurements of OH (119 microns) and [OI] (145 microns) are all readily fit by a single, fast J-shock model. Although the [OI] (63) emission can alternatively be produced by a slow C-shock, this ensemble of lines can not be produced by such a shock and provides strong evidence for the existence of a J-shock. A 24-arcmin strip map shows that this far-infrared line emission is spatially correlated with the H$-2$ 1-0 S(1) emission, which most likely arises in an associated C-shock. In addition to this spatially correlated shock emission, the strip map identifies extended [CII] and [OI] emission with a significantly larger line ratio (approx. 0.6); this 'background' component is compared with current J-shock, C-shock, photo-dissociation region (PDR), and X-ray dissociation region (XDR) models in an effort to explain its origin.

  20. The End of Amnesia: Measuring the Metallicities of Type Ia SN Progenitors with Manganese Lines in Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Badenes, Carles; Bravo, Eduardo; Hughes, John P.

    2009-05-01

    The Mn to Cr mass ratio in supernova ejecta has recently been proposed as a tracer of Type Ia SN progenitor metallicity. We review the advantages and problems of this observable quantity, and discuss them in the framework of the Tycho Supernova Remnant. The fluxes of the Mn and Cr Kα lines in the X-ray spectra of Tycho observed by the Suzaku satellite suggests a progenitors of supersolar metallicity.

  1. Discovery of optical candidate supernova remnants in Sagittarius

    NASA Astrophysics Data System (ADS)

    Alikakos, J.; Boumis, P.; Christopoulou, P. E.; Goudis, C. D.

    2012-08-01

    During an [O III] survey of planetary nebulae, we identified a region in Sagittarius containing several candidate supernova remants (SNRs) and obtained deep optical narrow-band images and spectra to explore their nature. We obtained images of the area of interest by acquiring observations in the emission lines of Hα + [N II], [S II] and [O III]. The resulting mosaic covers an area of 1.4° × 1.0°, where both filamentary and diffuse emission was discovered, suggesting that there is more than one SNR in the area. Deep long-slit spectra were also taken of eight different regions. Both the flux-calibrated images and the spectra show that the emission from the filamentary structures originates from shock-heated gas, while the photo-ionization mechanism is responsible for the diffuse emission. Part of the optical emission is found to be correlated with the radio at 4850 MHz suggesting that they are related, while the infrared emission found in the area at 12 μm and 22 μm marginally correlates with the optical. The presence of the [O III] emission line in one of the candidate SNRs implies that the shock velocities in the interstellar "clouds" are between 120 km s-1 and 200 km s-1, while its absence in the other candidate SNRs indicates that the shock velocities there are slower. For all candidate remnants, the [S II] λλ 6716/6731 ratio indicates that the electron densities are below 240 cm-3, while the Hα emission is measured to be between 0.6 and 41 × 10-17 erg s-1 cm-2 arcsec-2. The existence of eight pulsars within 1.5° of the center of the candidate SNRs also implies that there are many SNRs in the area as well as that the detected optical emission could be part of a number of supernovae explosions.

  2. SUPERNOVA REMNANT PROGENITOR MASSES IN M31

    SciTech Connect

    Jennings, Zachary G.; Williams, Benjamin F.; Dalcanton, Julianne J.; Gilbert, Karoline M.; Fouesneau, Morgan; Weisz, Daniel R.; Murphy, Jeremiah W.; Dolphin, Andrew E. E-mail: adolphin@raytheon.com

    2012-12-10

    Using Hubble Space Telescope photometry, we age-date 59 supernova remnants (SNRs) in the spiral galaxy M31 and use these ages to estimate zero-age main-sequence masses (M{sub ZAMS}) for their progenitors. To accomplish this, we create color-magnitude diagrams (CMDs) and employ CMD fitting to measure the recent star formation history of the regions surrounding cataloged SNR sites. We identify any young coeval population that likely produced the progenitor star, then assign an age and uncertainty to that population. Application of stellar evolution models allows us to infer the M{sub ZAMS} from this age. Because our technique is not contingent on identification or precise location of the progenitor star, it can be applied to the location of any known SNRs. We identify significant young star formation around 53 of the 59 SNRs and assign progenitor masses to these, representing a factor of {approx}2 increase over currently measured progenitor masses. We consider the remaining six SNRs as either probable Type Ia candidates or the result of core-collapse progenitors that have escaped their birth sites. In general, the distribution of recovered progenitor masses is bottom-heavy, showing a paucity of the most massive stars. If we assume a single power-law distribution, dN/dM{proportional_to}M{sup {alpha}}, then we find a distribution that is steeper than a Salpeter initial mass function (IMF) ({alpha} = -2.35). In particular, we find values of {alpha} outside the range -2.7 {>=} {alpha} {>=} -4.4 to be inconsistent with our measured distribution at 95% confidence. If instead we assume a distribution that follows a Salpeter IMF up to some maximum mass, then we find that values of M{sub Max} > 26 are inconsistent with the measured distribution at 95% confidence. In either scenario, the data suggest that some fraction of massive stars may not explode. The result is preliminary and requires more SNRs and further analysis. In addition, we use our distribution to estimate a

  3. A multiwavelength study of the remnant of nova GK Persei

    NASA Astrophysics Data System (ADS)

    Anupama, G. C.; Kantharia, N. G.

    2005-05-01

    We present new observations of the nebular remnant of the old nova GK Persei 1901 in the optical using the Himalayan Chandra Telescope (HCT) and at low radio frequencies using the Giant Metrewave Radio Telescope (GMRT). The dimensions of the shell in the optical emission lines of [NII], [OIII] and [OII] are 108× 94 arcsec2, 104× 94 arcsec2 and 99× 87 arcsec2, respectively. The evolution of the nova remnant indicates shock interaction with the ambient medium, especially in the southwest quadrant. Application of a simple model for the shock and its evolution to determine the time dependence of the radius of the shell in the southwest quadrant indicates that the shell is now expanding into an ambient medium that has a density of 0.12 cm-3, compared to the density of the ambient medium of 0.8 cm-3 ahead of the shock in 1987. There are indications of a recent interaction of the nova remnant with the ambient medium in the northeast quadrant. There is a distinct flattening of the shell, as well as an increase in the number and brightness of the knots in the region. The brightest optical knots in this region are also detected in the radio images. The nova remnant of GK Per is detected at all the observed radio frequencies and is of a similar extent to the optical remnant. Putting together our radio observations with VLA archival data on GK Per from 1997, we obtain three interesting results: 1. the spectrum above 1.4 GHz follows a power law with an index -0.7 (S∝ να) and below 1.4 GHz follows a power law with an index ˜ -0.85. This could be due to the presence of at least two populations of electrons dominating the global emission at different frequencies; 2. we record an annual secular decrease of 2.1% in the flux density of the nova remnant at 1.4 and 4.9 GHz between 1984 and 1997 which has left the spectral index unchanged at -0.7. No such decrease is observed in the flux densities below 1 GHz; 3. we record an increase in the flux density at 0.33 GHz compared to

  4. Fermi-LAT observations of supernova remnants Kesteven 79

    SciTech Connect

    Auchettl, Katie; Slane, Patrick; Castro, Daniel

    2014-03-01

    In this paper, we report on the detection of γ-ray emission coincident with the Galactic supernova remnant (SNR) Kesteven 79 (Kes 79). We analyzed approximately 52 months of data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. Kes 79 is thought to be interacting with adjacent molecular clouds, based on the presence of strong {sup 12}CO J = 1 → 0 and HCO{sup +} J = 1 → 0 emission and the detection of 1720 MHz line emission toward the east of the remnant. Acceleration of cosmic rays is expected to occur at SNR shocks, and SNRs interacting with dense molecular clouds provide a good testing ground for detecting and analyzing the production of γ-rays from the decay of π{sup 0} into two γ-ray photons. This analysis investigates γ-ray emission coincident with Kes 79, which has a detection significance of ∼7σ. Additionally, we present an investigation of the spatial and spectral characteristics of Kes 79 using multiple archival XMM-Newton observations of this remnant. We determine the global X-ray properties of Kes 79 and estimate the ambient density across the remnant. We also performed a similar analysis for Galactic SNR Kesteven 78 (Kes 78), but due to large uncertainties in the γ-ray background model, no conclusion can be made about an excess of GeV γ-ray associated with the remnant.

  5. Featured Image: A Supernova Remnant in X-Rays

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-09-01

    This is a three-color X-ray image taken by Chandra of the supernova remnant RCW 103. This supernova remnant is an unusual system: its young, but unlike other remnants of its age, metal-rich ejecta hadnt previously been discovered in it. In this paper, Kari Frank (Pennsylvania State University) and collaborators analyze the three deepest Chandra observations of RCW 103 and find the first evidence for metal-rich ejecta emission scattered throughout the remnant. Their analyses also help to constrain the identity of the mysterious compact stellar object powering the remnant. In this image, red = 0.30.85 keV, green = 0.851.70 keV, and blue = 1.73.0 keV; click on the image for the full view. For more information and the original image, see the paper here:Kari A. Frank et al 2015 ApJ 810 113 doi:10.1088/0004-637X/810/2/113.

  6. Extravasation Mucocele Arising from a Lingual Thyroglossal Duct Remnant

    PubMed Central

    Nakahira, Mitsuhiko; Nakatani, Hiroaki

    2015-01-01

    Although a thyroglossal duct cyst is a congenital anomaly, it can also appear in adults. Despite the presence of embryological remnants, it is still unclear why the cyst should suddenly develop later in life. We report a case of a 46-year-old male with an extravasation mucocele arising from a long-standing lingual thyroglossal duct remnant. MRI demonstrated a lingual cystic lesion near the hyoid bone associated with a suprahyoid tract-like structure masquerading as a thyroglossal duct cyst. However, histopathological examination demonstrated a mucocele secondary to a rupture of a thyroglossal duct remnant with numerous intramural heterotopic salivary glands. We propose a new mechanism of an acquired cystic formation of this congenital disease that excessive production of mucus from heterotopic salivary glands and a physical trauma such as swallowing may lead to extravasation of mucus from the thyroglossal duct. PMID:25861502

  7. Extravasation mucocele arising from a lingual thyroglossal duct remnant.

    PubMed

    Nakahira, Mitsuhiko; Nakatani, Hiroaki

    2015-01-01

    Although a thyroglossal duct cyst is a congenital anomaly, it can also appear in adults. Despite the presence of embryological remnants, it is still unclear why the cyst should suddenly develop later in life. We report a case of a 46-year-old male with an extravasation mucocele arising from a long-standing lingual thyroglossal duct remnant. MRI demonstrated a lingual cystic lesion near the hyoid bone associated with a suprahyoid tract-like structure masquerading as a thyroglossal duct cyst. However, histopathological examination demonstrated a mucocele secondary to a rupture of a thyroglossal duct remnant with numerous intramural heterotopic salivary glands. We propose a new mechanism of an acquired cystic formation of this congenital disease that excessive production of mucus from heterotopic salivary glands and a physical trauma such as swallowing may lead to extravasation of mucus from the thyroglossal duct. PMID:25861502

  8. A multiwavelength investigation of the supernova remnant IC 443

    NASA Astrophysics Data System (ADS)

    Mufson, S. L.; McCollough, M. L.; Dickel, J. R.; Petre, R.; White, R.; Chevalier, R.

    1986-12-01

    Multiwavelength observations of the supernova remnant IC 443 at radio, infrared, optical, ultraviolet, and X-ray wavelengths are presented. This morphological study of IC 443 presents a detailed picture of an adolescent supernova remnant in a multiphase interstellar medium. Radio observations show that better than 80 percent of the continuum emission at 18 cm is in a large-scale (greater than 18 arcmin) component. Decomposition of the infrared data shows that radiatively heated dust, shocked blackbody dust emission, and infrared line emission are all important components of the observed IRAS fluxes. The morphology of the IC 443 region is consistent with a supernova blast in an interstellar medium with a nonuniform distribution of clouds. The bright northeast rim and the great extent of the remnant to the southwest are most easily explained by a cloud filling factor which is greatest in the northeast and falls off toward the southwest.

  9. A multiwavelength investigation of the supernova remnant IC 443

    NASA Technical Reports Server (NTRS)

    Mufson, S. L.; Mccollough, M. L.; Dickel, J. R.; Petre, R.; White, R.

    1986-01-01

    Multiwavelength observations of the supernova remnant IC 443 at radio, infrared, optical, ultraviolet, and X-ray wavelengths are presented. This morphological study of IC 443 presents a detailed picture of an adolescent supernova remnant in a multiphase interstellar medium. Radio observations show that better than 80 percent of the continuum emission at 18 cm is in a large-scale (greater than 18 arcmin) component. Decomposition of the infrared data shows that radiatively heated dust, shocked blackbody dust emission, and infrared line emission are all important components of the observed IRAS fluxes. The morphology of the IC 443 region is consistent with a supernova blast in an interstellar medium with a nonuniform distribution of clouds. The bright northeast rim and the great extent of the remnant to the southwest are most easily explained by a cloud filling factor which is greatest in the northeast and falls off toward the southwest.

  10. A HIRES analysis of the FIR emission of supernova remnants

    NASA Technical Reports Server (NTRS)

    Wang, Zhong

    1994-01-01

    The high resolution (HiRes) algorithm has been used to analyze the far infrared emission of shocked gas and dust in supernova remnants. In the case of supernova remnant IC 443, we find a very good match between the resolved features in the deconvolved images and the emissions of shocked gas mapped in other wavelengths (lines of H2, CO, HCO+, and HI). Dust emission is also found to be surrounding hot bubbles of supernova remnants which are seen in soft X-ray maps. Optical spectroscopy on the emission of the shocked gas suggests a close correlation between the FIR color and local shock speed, which is a strong function of the ambient (preshock) gas density. These provide a potentially effective way to identify regions of strong shock interaction, and thus facilitate studies of kinematics and energetics in the interstellar medium.

  11. Multiwavelength Signatures of Cosmic Ray Acceleration by Young Supernova Remnants

    SciTech Connect

    Vink, Jacco

    2008-12-24

    An overview is given of multiwavelength observations of young supernova remnants, with a focus on the observational signatures of efficient cosmic ray acceleration. Some of the effects that may be attributed to efficient cosmic ray acceleration are the radial magnetic fields in young supernova remnants, magnetic field amplification as determined with X-ray imaging spectroscopy, evidence for large post-shock compression factors, and low plasma temperatures, as measured with high resolution optical/UV/X-ray spectroscopy. Special emphasis is given to spectroscopy of post-shock plasma's, which offers an opportunity to directly measure the post-shock temperature. In the presence of efficient cosmic ray acceleration the post-shock temperatures are expected to be lower than according to standard equations for a strong shock. For a number of supernova remnants this seems indeed to be the case.

  12. Hydrodynamic instabilities in supernova remnants - Self-similar driven waves

    NASA Technical Reports Server (NTRS)

    Chevalier, Roger A.; Blondin, John M.; Emmering, Robert T.

    1992-01-01

    An initial study aimed at elucidating the multidimensional aspects of the hydrodynamic instabilities in supernova remnants is presented. Self-similar solutions are found to exist for the interaction of a steep power-law density profile expanding into a relatively flat stationary power-law density profile. Consideration of the pressure and entropy profiles in the shocked 1D flows shows that the flows are subject to convective instability, by a local criterion. The growth rate for the instability becomes very large near the contact discontinuity between the two shocked regions. A linear analysis of the complete self-similar solutions shows that the solutions are unstable above a critical wavenumber and that the growth rate is greatest at the position of the contact discontinuity. The X-ray image of the remnant of SN 1572 (Tycho) shows emission from clumps of supernova ejecta, which is good evidence for instabilities in this remnant.

  13. 3D Simulations of Supernovae into the Young Remnant Phase

    NASA Astrophysics Data System (ADS)

    Ellinger, Carola I.; Young, P. A.; Fryer, C.; Rockefeller, G.; Park, S.

    2013-01-01

    The explosion of massive stars as core-collapse supernovae is an inherently three dimensional phenomenon. Observations of the young, ejecta dominated remnants of those explosions unambiguously demonstrate that asymmetry on large and small scales is the rule, rather than the exception. Numerical models of supernova remnants connect the observed remnants to models of the exploding stellar system and thus facilitate both improved interpretations of the observations as well as improve our understanding of the explosion mechanism. We present first 3D simulations of core- collapse supernovae evolving into supernova remnants calculated with SNSPH. The calculations were started from 1D collapsed models of 2 progenitor stars of different types, and follow the explosion from revival of the shock wave to shock break out in 3D. Two different interstellar media, a cold neutral medium and a dense molecular cloud, as well as a red supergiant stellar wind profile, were added to the explosion calculations shortly before shock breakout, so that the blast wave stays in the simulation. With this setup we can follow the dispersal of the nucleosynthesis products from the explosion into the Sedov stage of the supernova remnant evolution starting from realistic initial conditions for the supernova ejecta. We will present a first investigation in the mixing between stellar and interstellar matter as the supernova evolves into the young supernova remnant phase, and contrasts differences that are observed between the scenarios that are investigated. One of the goals is to distinguish between features that arose in instabilities during the explosion from those that were created in the interaction with the surrounding medium.

  14. The Kinematics of Kepler's Supernova Remnant as Revealed by Chandra

    NASA Astrophysics Data System (ADS)

    Vink, Jacco

    2008-12-01

    I have determined the expansion of the supernova remnant of SN 1604 (Kepler's supernova) based on archival Chandra ACIS-S observations made in 2000 and 2006. The measurements were done in several distinct energy bands, and were made for the remnant as a whole, and for six individual sectors. The average expansion parameter indicates that the remnant expands on average as r propto t0.5, but there are significant differences in different parts of the remnant: the bright northwestern part expands as r propto t0.35, whereas the rest of the remnant's expansion shows an expansion r propto t0.6. The latter is consistent with an explosion in which the outer part of the ejecta has a negative power law slope for density (ρ propto v-n) of n = 7, or with an exponential density profile [ρ propto exp (- v/ve) ]. The expansion parameter in the southern region, in conjunction with the shock radius, indicates a rather low value (<5 × 1050 erg) for the explosion energy of SN 1604 for a distance of 4 kpc. A higher explosion energy is consistent with the results if the distance is larger. The filament in the eastern part of the remnant, which is dominated by X-ray synchrotron radiation, seems to mark a region with a fast shock speed r propto t0.7, corresponding to a shock velocity of v = 4200 km s-1, for a distance to SN 1604 of 4 kpc. This is consistent with the idea that X-ray synchrotron emission requires shock velocities in excess of ~2000 km s-1. The X-ray-based expansion measurements reported are consistent with results based on optical and radio measurements but disagree with previous X-ray measurements based on ROSAT and Einstein observations.

  15. A Compact Central Object in the Supernova Remnant Kesteven 79

    NASA Astrophysics Data System (ADS)

    Seward, F. D.; Slane, P. O.; Smith, R. K.; Sun, M.

    2003-02-01

    A Chandra X-ray observation has detected an unresolved source at the center of the supernova remnant Kes 79. The best single-model fit to the source spectrum is a blackbody with an X-ray luminosity of LX(0.3-8.0keV)=7×1033 ergs s-1. There is no evidence for a surrounding pulsar wind nebula. There are no cataloged counterparts at other wavelengths, but the absorption is high. The source properties are similar to the central source in Cas A even though the Kes 79 remnant is considerably older.

  16. X-ray Observations of the Tycho Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Hughes, John P.

    2006-06-01

    In this presentation I summarize some key new findings from recent Chandra and XMM-Newton data on the remnant of the supernova (SN) observed by Tycho Brahe in 1572, which is widely believed to have been of Type Ia origin. Studies of the Tycho supernova remnant (SNR) at the current epoch address aspects of SN Ia physics, the evolution of young SNRs, and cosmic ray acceleration at high Mach-number shocks.Research on the Tycho SNR at Rutgers has been supported by Chandra grants GO3-4066X and AR5-6010X.

  17. Spitzer IRS observations of the XA region in the cygnus loop supernova remnant

    SciTech Connect

    Sankrit, Ravi; Bautista, Manuel; Williams, Brian J.; Blair, William P.; Borkowski, Kazimierz J.; Long, Knox S.

    2014-05-20

    We report on spectra of two positions in the XA region of the Cygnus Loop supernova remnant obtained with the InfraRed Spectrograph on the Spitzer Space Telescope. The spectra span the 10-35 μm wavelength range, which contains a number of collisionally excited forbidden lines. These data are supplemented by optical spectra obtained at the Whipple Observatory and an archival UV spectrum from the International Ultraviolet Explorer. Coverage from the UV through the IR provides tests of shock wave models and tight constraints on model parameters. Only lines from high ionization species are detected in the spectrum of a filament on the edge of the remnant. The filament traces a 180 km s{sup –1} shock that has just begun to cool, and the oxygen to neon abundance ratio lies in the normal range found for Galactic H II regions. Lines from both high and low ionization species are detected in the spectrum of the cusp of a shock-cloud interaction, which lies within the remnant boundary. The spectrum of the cusp region is matched by a shock of about 150 km s{sup –1} that has cooled and begun to recombine. The post-shock region has a swept-up column density of about 1.3 × 10{sup 18} cm{sup –2}, and the gas has reached a temperature of 7000-8000 K. The spectrum of the Cusp indicates that roughly half of the refractory silicon and iron atoms have been liberated from the grains. Dust emission is not detected at either position.

  18. A Detailed Chandra Archive Study of the Young O-Rich Supernova Remnant 1E 0102.2-7219 in the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Alan, Neslihan; Bilir, Selçuk; Park, Sangwook; Schenck, Andrew

    2016-07-01

    Based on the deep 273 ks archival Chandra data we performed detailed spatially-resolved spectral analysis of the oxygen-rich supernova remnant (SNR) 1E 0102.2-7219 (E0102) in the Small Magellanic Cloud. Our aim in this study is to reveal spatial and chemical structures of this remnant in unprecedented details. We examined radial and azimuthal structures in the electron temperature, ionization timescale, emission measure, and elemental abundances. We estimate the progenitor's mass (˜40 M _{sun}) based on O, Ne, and Mg abundance ratios. We estimate the Sedov age (˜3500 yr) and explosion energy (˜1.8x10 ^{51} erg) for E0102. We shortly discuss the implications of our results on the geometrical structure of the remnant, its circumstellar medium and the nature of the progenitor star.

  19. Remnant wharf with two bollards at the south end of ...

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

    Remnant wharf with two bollards at the south end of row within Pan American Airways/Naval Air Transport Service/destroyer base site. View facing south-southeast. - U.S. Naval Base, Pearl Harbor, Pearl City Peninsula, Pearl City, Honolulu County, HI

  20. Hot interstellar tunnels. 1: Simulation of interacting supernova remnants

    NASA Technical Reports Server (NTRS)

    Smith, B. W.

    1976-01-01

    The theory required to build a numerical simulation of interacting supernova remnants is developed. The hot cavities within a population of remnants will become connected, with varying ease and speed, for a variety of assumed conditions in the outer shells of old remnants. Apparently neither radiative cooling nor thermal conduction in a large-scale galactic magnetic field can destroy hot cavity regions, if they grow, faster than they are reheated by supernova shock waves, but interstellar mass motions disrupt the contiguity of extensive cavities necessary for the dispersal of these shocks over a wide volume. Monte Carlo simulations show that a quasi-equilibrium is reached in the test space within 10 million yrs of the first supernova and is characterized by an average cavity filling fraction of the interstellar volume. Aspects of this equilibrium are discussed for a range of supernova rates. Two predictions are not confirmed within this range: critical growth of hot regions to encompass the entire medium, and the efficient quenching of a remnant's expansion by interaction with other cavities.

  1. General exterior view showing remnants of loading dock at three ...

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

    General exterior view showing remnants of loading dock at three main doors, view to north - Charlestown Navy Yard, Oxygen Plant, Midway along northern boundary of Charlestown Navy Yard, on Little Mystic Channel, near junction of Eighteenth Street & Fourth Avenue, Boston, Suffolk County, MA

  2. Meteorological Station, interior with collapsed roof showing remnant wooden equipment ...

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

    Meteorological Station, interior with collapsed roof showing remnant wooden equipment switch box on east wall; view southeast - Fort McKinley, Meteorological Station, East side of Weymouth Way, approximately 225 feet south of Cove Side Drive, Great Diamond Island, Portland, Cumberland County, ME

  3. 15. VIEW SOUTH, DETAIL OF REMNANTS OF EAST SIDE BRIDGE ...

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

    15. VIEW SOUTH, DETAIL OF REMNANTS OF EAST SIDE BRIDGE ABUTMENT - Bald Eagle Cross-Cut Canal Lock, North of Water Street along West Branch of Susquehanna River South bank, 500 feet East of Jay Street Bridge, Lock Haven, Clinton County, PA

  4. 6. OLD AND NEW TIOGA ROAD. NOTE REMNANTS OF OLD ...

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

    6. OLD AND NEW TIOGA ROAD. NOTE REMNANTS OF OLD ROAD ON LEFT. NOTE ROAD CUT ON CANYON WALL IN CENTER REAR. LOOKING NNE. GIS: N-37 56 19.5 / W-119 13 53.3 - Tioga Road, Between Crane Flat & Tioga Pass, Yosemite Village, Mariposa County, CA

  5. 8. VIEW OF REMNANTS OF COULTERVILLE ROAD BELOW FORESTA. NOTE ...

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

    8. VIEW OF REMNANTS OF COULTERVILLE ROAD BELOW FORESTA. NOTE ASPHALT AT LEFT CENTER. NOTE RETAINING WALL AT RIGHT REAR. LOOKING NW. GIS: N-37 42 40.6 / W-119 43 27.6 - Coulterville Road, Between Foresta & All-Weather Highway, Yosemite Village, Mariposa County, CA

  6. Steam or water connection with remnant of concrete basin in ...

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

    Steam or water connection with remnant of concrete basin in foreground. Pipe connection located approximately 6' east of metal stairs leading to Bright Angel Lodge. Dry laid retaining wall in background. - Grand Canyon Village Utilities, Grand Canyon National Park, Grand Canyon Village, Coconino County, AZ

  7. Circumstellar Dust in the Remnant of Kepler's Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    Williams, Brian J.; Blair, W. P.; Borkowski, K. J.; Ghavamian, P.; Long, K. S.; Reynolds, S. P.; Sankrit, R.

    2012-01-01

    Kepler's Supernova Remnant, the remains of the supernova of 1604, is widely believed to be the result of a Type Ia supernova, and shows IR, optical, and X-ray evidence for an interaction of the blast wave with a dense circumstellar medium (CSM). We present low-resolution 7.5-38 μm IR spectra of selected regions within the remnant, obtained with the Spitzer Space Telescope. Spectra of those regions where the blast wave is encountering circumstellar material show strong features at 10 and 18 μm. These spectral features are most consistent with various silicate particles, likely formed in the stellar outflow from the progenitor system during the AGB stage of evolution. While it is possible that some features may arise from freshly formed ejecta dust, morphological evidence suggests that it is more likely that they originate from dust in the CSM. We isolate the dust grain absorption efficiencies for several regions in Kepler and compare them to laboratory data for dust particles of various compositions. The hottest dust in the remnant originates in the regions of dense, radiatively shocked clumps of gas, identified in optical images. Models of collisionally heated dust show that such shocks are capable of heating grains to temperatures of > 150 K. We confirm the finding that Kepler's SNR is still interacting with CSM in at least part of the remnant after 400 years. The significant quantities of silicate dust are consistent with a relatively massive progenitor.

  8. 15. CYLINDRICAL FISH SCALER Remnants of the wire screen remain, ...

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

    15. CYLINDRICAL FISH SCALER Remnants of the wire screen remain, through which the fish tumbled as the cylinder revolved. Note geared ring around cylinder, and the small drive shaft by which it was driven. - Hovden Cannery, 886 Cannery Row, Monterey, Monterey County, CA

  9. Six Balmer-dominated supernova remnants

    SciTech Connect

    Smith, R.C.; Kirshner, R.P.; Blair, W.P.; Winkler, P.F. Johns Hopkins University, Baltimore, MD Middlebury College, VT )

    1991-07-01

    Spectra of six Balmer-dominated SNRs are examined: the Galactic SNR of SN 1572 and SN 1006, the LMC SNR 0505-67.9, 0509-67.5, 0519-69.0, and 0548-70.4. A shock velocity is derived for each SNR with broad H-alpha and a possible lower limit of the shock velocity in 0509-67.5. Models are used which show that the use of the ratio of broad to narrow intensity as an indicator of shock velocity is not reliable. The observed intensity ratios do not correspond to either the commonly assumed case of no equilibration or to the other extreme of total equilibration. Distances to the filaments in SN 1572 and SN 1006 of 1.5-3.1 kpc and 1.4-2.8 kpc, respectively, are obtained. The ages are estimated to range from about 10,000 yr for 0505-67.9 and 0548-70.4 to less than 1500 yr for the small SNR 0509-67.5 and 0519-69.0.l. These two young SNR bring the number of SNe in the LMC to at least five in the past 1500 yr, making the SN rate per unit luminosity comparable to that reported for late spiral galaxies. 40 refs.

  10. Satellite Movie Shows Hurricane Dolores' Remnants Bring Rains to U.S. Southwest

    NASA Video Gallery

    This animation of images captured July 17 to 22 from NOAA's GOES-West satellite shows Hurricane Dolores' remnants streaming over the southwestern U.S. The remnants dropped heavy rainfall in Califor...

  11. An Optical Survey of Supernova Remnants in M83

    NASA Astrophysics Data System (ADS)

    Blair, William P.; Long, Knox S.

    2004-11-01

    Observations of the face-on spiral galaxy M83 (NGC 5236) performed at the Cerro Tololo Inter-American Observatory in Chile have yielded a catalog of optical supernova remnant (SNR) candidates. These observations were performed with the 4 m Blanco telescope and a prime focus CCD imaging system using narrowband interference filters centered on the light of [S II], Hα, [O III], and red and blue continuum bands. Based on strong relative [S II]:Hα emission, 71 emission nebulae have been identified as SNR candidates. Positions and Hα fluxes of the candidates are presented. Follow-up spectra of 25 of the SNR candidates, also performed at CTIO, have confirmed many of the SNR identifications, although the spectra of a few objects are discrepant, perhaps because of inaccurate aperture placement. In addition, the low mean excitation of M83 H II regions has allowed a separate search for young oxygen-dominated (core collapse) SNRs similar to Cas A in our Galaxy, using [O III]:Hα. This search found a number of the same objects as the [S II]:Hα search, indicating that many of these SNRs have shock velocities in excess of 100 km s-1. However, no bona fide young core-collapse SNRs were detected with this technique, with the possible exception of the independent recovery of SN 1957D, which had been seen previously. We have also attempted to identify optical counterparts for the six historical supernovae that have occurred in M83. Except for SN 1957D, none of the historical supernovae have been detected by this survey. We compare our SNR candidate list against the Chandra X-ray source list of Soria and Wu and identify 15 X-ray sources as likely SNRs, based on positional coincidence within 1". The sources identified have hardness ratios that are soft compared to the general X-ray source population in M83. Based on observations made with the Cerro Tololo Inter-American Observatory, La Serena, Chile.

  12. A 3D numerical model for Kepler's supernova remnant

    NASA Astrophysics Data System (ADS)

    Toledo-Roy, J. C.; Esquivel, A.; Velázquez, P. F.; Reynoso, E. M.

    2014-07-01

    We present new 3D numerical simulations for Kepler's supernova remnant. In this work we revisit the possibility that the asymmetric shape of the remnant in X-rays is the product of a Type Ia supernova explosion which occurs inside the wind bubble previously created by an AGB companion star. Due to the large peculiar velocity of the system, the interaction of the strong AGB wind with the interstellar medium results in a bow shock structure. In this new model we propose that the AGB wind is anisotropic, with properties such as mass-loss rate and density having a latitude dependence, and that the orientation of the polar axis of the AGB star is not aligned with the direction of motion. The ejecta from the Type Ia supernova explosion is modelled using a power-law density profile, and we let the remnant evolve for 400 yr. We computed synthetic X-ray maps from the numerical results. We find that the estimated size and peculiar X-ray morphology of Kepler's supernova remnant are well reproduced by considering an AGB mass-loss rate of 10-5 M⊙ yr-1, a wind terminal velocity of 10 km s-1, an ambient medium density of 10-3 cm-3 and an explosion energy of 7 × 1050 erg. The obtained total X-ray luminosity of the remnant in this model reaches 6 × 1050 erg, which is within a factor of 2 of the observed value, and the time evolution of the luminosity shows a rate of decrease in recent decades of ˜2.4 per cent yr-1 that is consistent with the observations.

  13. Asymmetric supernova remnants generated by Galactic, massive runaway stars

    NASA Astrophysics Data System (ADS)

    Meyer, D. M.-A.; Langer, N.; Mackey, J.; Velázquez, P. F.; Gusdorf, A.

    2015-07-01

    After the death of a runaway massive star, its supernova shock wave interacts with the bow shocks produced by its defunct progenitor, and may lose energy, momentum and its spherical symmetry before expanding into the local interstellar medium (ISM). We investigate whether the initial mass and space velocity of these progenitors can be associated with asymmetric supernova remnants. We run hydrodynamical models of supernovae exploding in the pre-shaped medium of moving Galactic core-collapse progenitors. We find that bow shocks that accumulate more than about 1.5 M⊙ generate asymmetric remnants. The shock wave first collides with these bow shocks 160-750 yr after the supernova, and the collision lasts until 830-4900 yr. The shock wave is then located 1.35-5 pc from the centre of the explosion, and it expands freely into the ISM, whereas in the opposite direction it is channelled into the region of undisturbed wind material. This applies to an initially 20 M⊙ progenitor moving with velocity 20 km s-1 and to our initially 40 M⊙ progenitor. These remnants generate mixing of ISM gas, stellar wind and supernova ejecta that is particularly important upstream from the centre of the explosion. Their light curves are dominated by emission from optically thin cooling and by X-ray emission of the shocked ISM gas. We find that these remnants are likely to be observed in the [O III] λ 5007 spectral line emission or in the soft energy-band of X-rays. Finally, we discuss our results in the context of observed Galactic supernova remnants such as 3C 391 and the Cygnus Loop.

  14. GT1_vgeers_1: Tracing Remnant Gas in Planet Forming Debris Disk Systems

    NASA Astrophysics Data System (ADS)

    Geers, V.

    2010-03-01

    Recent studies of gas emission lines with Spitzer and sub-millimeter telescopes have shown that 10-100 Myr old stars with debris disks have too little gas left to form Jupiter like gas giant planets. Whether enough gas remains in these systems to form ice giant planets is still unanswered. The [OI] emission line at 63 micron is one of the most sensitive tracers of gas mass in the ice-giant region of 10-50 AU in disks, and Herschel PACS is therefore uniquely suited to trace the remnant gas in planet-forming disks. We propose to obtain PACS line spectroscopy of [OI] (63 micron) for two nearby young stars, HR 8799 and HD 15115, which are two systems with detected giant planets or signs of planet formation, while still harbouring prominent debris disks that could be in the process of forming ice giants such as Neptune and Uranus. The proposed observations will probe down to gas masses of 0.01 Earth masses, and allow us to constrain prospects for ice giant formation, measure gas-to-dust ratios in evolved disks to compare with planet formation / disk evolution models, and put constraints on whether the dust dynamics in these systems is driven by the remnant gas or by the radiation. Note: this proposal is submitted under the Swiss part of the HIFI Guaranteed Time program; HIFI PI: Frank Helmich, HIFI Swiss Lead CoI: Arnold Benz.

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  16. Far Ultraviolet Spectroscopic Explorer Observation of the Nonradiative Collisionless Shock in the Remnant of SN 1006

    NASA Astrophysics Data System (ADS)

    Korreck, K. E.; Raymond, J. C.; Zurbuchen, T. H.; Ghavamian, P.

    2004-11-01

    The appearance of the young supernova remnant SN 1006 is dominated by emission from nonradiative shocks in the northeast and northwest regions. At X-ray energies the northeast shock exhibits predominantly nonthermal synchrotron emission, while the northwest shock exhibits a thermal spectrum. We present far-ultraviolet spectra of the northeast (NE) and northwest (NW) portions of SN 1006 acquired with the Far Ultraviolet Spectroscopic Explorer (FUSE). We have detected emission lines of O VI λλ1032, 1038 and broad Lyβ λ1025 in the NW filament but detect no emission lines in the NE region down to a level of 4.7×10-17 ergs cm-2 s-1 arcsec-2. We observed in the NW an O VI intensity of 2.0+/-0.2×10-16 ergs cm-2 s-1 arcsec-2 and measured an O VI line width of 2100+/-200 km s-1 at a position where the Hα width was measured to be 2290+/-80 km s-1. This implies less than mass-proportional heating of the ions. Using the ratio of intensities I(NW)/I(NE)~n(NW)/n(NE), the density ratio of the two regions is found to be >=4, a value that is consistent with the uncertainties of the ratio of 2.5 measured in 2003 by Long and coworkers. The derived O VI kinetic temperature is compared to previous estimates of electron, proton, and ion temperatures in the remnant to study the relative heating efficiency of various species at the shock front. The degree of postshock temperature equilibration may be crucial to particle acceleration, since the temperature of each species determines the number of high-speed particles available for injection into an acceleration process that could produce Galactic cosmic rays.

  17. Second Epoch Hubble Space Telescope Imaging of Kepler's Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Sankrit, Ravi; Blair, William P.; Borkowski, Kazimierz J.; Long, Knox S.; Patnaude, Daniel; Raymond, John C.; Reynolds, Stephen P.; Williams, Brian J.

    2015-01-01

    We have obtained new HST/WFC3 images of Kepler's supernova remnant in H-alpha (F656N) and [N II] (F658N) emission line filters. The bright radiative shocks in dense clumps are detected in both filters, while non-radiative shocks are seen as faint filaments only in the H-alpha image. Most of these Balmer filaments lie around the periphery of the remnant where the blast wave encounters partially neutral interstellar gas. We compare the new images with HST/ACS images taken nearly 10 years previously, and find that these filaments tracing the forward shock have moved 0.6"-0.9" between the two epochs. Assuming a distance of 4 kpc to the remnant, these proper motions correspond to shock velocities of 1160-1740 km/s, which are consistent with the published values, 1550-2000 km/s (e.g. Blair et al. 1991, ApJ 366, 484). We also find a few Balmer filaments with highly non-radial proper motions. In one particularly interesting case in the projected interior of the remnant, SE of the center, the shock appears to have wrapped around a sharp density enhancement and moved about 0.3" in the period between the observations.The images allow us to study the evolution of the shock around an ejecta knot, which is punching through the remnant boundary in the northwest. The forward shock, visible as an arcuate Balmer filament, has moved about 1". At the trailing edges, the system of radiative knots formed by Rayleigh-Taylor instabilities have undergone significant changes - some knots have disappeared, new ones have appeared, and many have changed in brightness. Elsewhere in the remnant we find changes in the relative intensities of many small, bright knots over the 10 year baseline, indicating the short radiative lifetimes of these features.This work has been supported in part by grant HST-GO-12885 to the Universities Space Research Association.

  18. Asymmetric Circumstellar Matter in Type Ia Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Borkowski, Kazimierz J.; Reynolds, S. P.; Blondin, J. M.

    2013-01-01

    The progenitors of Type Ia supernovae (SNe) are not well understood, but are likely to be of diverse origin, including single- and double-degenerate binary systems. Among single-degenerate progenitors, substantial amounts of circumstellar material (CSM) are expelled prior to the SN explosions by asymptotic giant branch (AGB) companions to the accreting white dwarfs. A subsequent collision of SN ejecta with the dense AGB wind has been detected among several distant SNe such as SN 2002ic, SN 2008J, and more recently PTF11kx. Dense CSM ejected by an AGB companion is present in the remnant of Kepler's SN of 1604, a Type Ia event. Observations of distant SNe hint at strongly asymmetric CSM distributions. A recent study of the CSM in Kepler's SNR by Burkey et al. indicates a large (factor of 10) density contrast between the dense, disk-like equatorial outflow and the more tenuous AGB wind above the orbital plane. A significant fraction of mature Type Ia SNRs in the Large Magellanic Cloud (LMC) shows the presence of dense Fe-rich ejecta in their interiors that cannot be explained by standard models of Type Ia explosions in a uniform ambient interstellar medium. We explore the hypothesis that these remnants originated in Type Ia explosions with strongly asymmetric CSM distributions such as found in Kepler's SNR. We present results of 2-D hydrodynamical simulations of the interaction of SN ejecta with asymmetric, disk-like AGB winds throughout the whole adiabatic stage of SNR evolution. Dense, asymmetric, and highly-ionized Fe-rich ejecta are indeed present in the simulated remnants, while the blast wave assumes a spherical shape shortly after passage through the ambient CSM. We also present simulated X-ray images and spectra and compare them with X-ray observations of selected remnants in the LMC. These remnants include DEM L238 and L249, recently observed by Suzaku, whose X-ray emission is strongly dominated by dense Fe-rich ejecta in their interiors. We contrast these

  19. Radio to Gamma-Ray Emission from Shell-Type Supernova Remnants: Predictions from Non-Linear Shock Acceleration Models

    NASA Technical Reports Server (NTRS)

    Baring, Matthew G.; Ellison, Donald C.; Reynolds, Stephen P.; Grenier, Isabelle A.; Goret, Philippe

    1998-01-01

    Supernova remnants (SNRs) are widely believed to be the principal source of galactic cosmic rays, produced by diffusive shock acceleration in the environs of the remnant's expanding blast wave. Such energetic particles can produce gamma-rays and lower energy photons via interactions with the ambient plasma. The recently reported observation of TeV gamma-rays from SN1006 by the CANGAROO Collaboration, combined with the fact that several unidentified EGRET sources have been associated with known radio/optical/X-ray-emitting remnants, provides powerful motivation for studying gamma-ray emission from SNRs. In this paper, we present results from a Monte Carlo simulation of non-linear shock structure and acceleration coupled with photon emission in shell-like SNRs. These non-linearities are a by-product of the dynamical influence of the accelerated cosmic rays on the shocked plasma and result in distributions of cosmic rays which deviate from pure power-laws. Such deviations are crucial to acceleration efficiency considerations and impact photon intensities and spectral shapes at all energies, producing GeV/TeV intensity ratios that are quite different from test particle predictions.

  20. Effects of display format on pilot describing function and remnant

    NASA Technical Reports Server (NTRS)

    Jex, H. R.; Allen, R. W.; Magdaleno, R. E.

    1972-01-01

    As part of a program to develop a comprehensive theory of manual control displays, six display formats were used by three instrument-rated pilots to regulate against random disturbances with a controlled element under both foveal and 10 deg parafoveal viewing conditions. The six display formats were: CRT line, CRT thermometer bar, 14-bar quantized on a CRT, a rotary dial and pointer, and two variations of a moving scale tape-drive. All were scaled to equivalent movement and apparent brightness. Measures included overall performance, describing functions, error remnant power spectra, critical instability scores, and subjective display ratings. The results show that the main effect of display format is on the loop closure properties. Less desirable displays induce lower bandwidth closures with consequent effects on the closed-loop remnant and performance.

  1. Heating of the interstellar medium by supernova remnants

    NASA Technical Reports Server (NTRS)

    Cox, D. P.

    1983-01-01

    Models for the mechanisms active during supernova (SN) heating of surrounding regions are examined. SNs heat both the matrix material and material in the nearby interstellar medium, and also accelerate cosmic rays with shock waves. Fountain and wind models vary according to the SN power and mass acquisition rate. Additionally, a warm intercloud medium may be fed by returning fountain material and stellar mass loss. The thermal wind temperature varies with the number of solar massess heated, although remnants have been observed to vanish in the LMC when more than 100 solar masses were heated. The possibility that the solar system is inside a remnant that produces the observed soft X-ray background is considered.

  2. A comparison of models for supernova remnants including cosmic rays

    NASA Astrophysics Data System (ADS)

    Kang, Hyesung; Drury, L. O'C.

    1992-11-01

    A simplified model which can follow the dynamical evolution of a supernova remnant including the acceleration of cosmic rays without carrying out full numerical simulations has been proposed by Drury, Markiewicz, & Voelk in 1989. To explore the accuracy and the merits of using such a model, we have recalculated with the simplified code the evolution of the supernova remnants considered in Jones & Kang, in which more detailed and accurate numerical simulations were done using a full hydrodynamic code based on the two-fluid approximation. For the total energy transferred to cosmic rays the two codes are in good agreement, the acceleration efficiency being the same within a factor of 2 or so. The dependence of the results of the two codes on the closure parameters for the two-fluid approximation is also qualitatively similar. The agreement is somewhat degraded in those cases where the shock is smoothed out by the cosmic rays.

  3. Radio structure of the remnant of Tycho's supernova (SN 1572)

    NASA Technical Reports Server (NTRS)

    Dickel, J. R.; Van Breugel, W. J. M.; Strom, R. G.

    1991-01-01

    The radio emission from the remnant of Tycho's supernova of 1572 arises in a nearly circular, clumpy shell. A very distinct, thin bright rim just outside the main shell can be seen around most of the periphery of the remnant. The outer edge of radio emission, usually defined by this bright rim, coincides perfectly with the outer X-ray boundary. Most of the emission is polarized by a modest amount, with the outer rim particularly prominent. Observations at several wavelengths are used to map out the rotation measure at high angular resolution, and determine the intrinsic magnetic field direction. The magnetic field shows a somewhat cellular pattern but with a net radial orientation and a generally fairly low degree of polarization.

  4. Radio structure of the remnant of Tycho's supernova (SN 1572)

    SciTech Connect

    Dickel, J.R.; Van breugel, W.J.M.; Strom, R.G. Lawrence Livermore National Laboratory, Livermore, CA Netherlands Foundation for Research in Astronomy, Dwingeloo )

    1991-06-01

    The radio emission from the remnant of Tycho's supernova of 1572 arises in a nearly circular, clumpy shell. A very distinct, thin bright rim just outside the main shell can be seen around most of the periphery of the remnant. The outer edge of radio emission, usually defined by this bright rim, coincides perfectly with the outer X-ray boundary. Most of the emission is polarized by a modest amount, with the outer rim particularly prominent. Observations at several wavelengths are used to map out the rotation measure at high angular resolution, and determine the intrinsic magnetic field direction. The magnetic field shows a somewhat cellular pattern but with a net radial orientation and a generally fairly low degree of polarization. 44 refs.

  5. Intermediate-mass black holes from Population III remnants in the first galactic nuclei

    NASA Astrophysics Data System (ADS)

    Ryu, Taeho; Tanaka, Takamitsu L.; Perna, Rosalba; Haiman, Zoltán

    2016-08-01

    We report the formation of intermediate-mass black holes (IMBHs) in suites of numerical N-body simulations of Population III remnant black holes (BHs) embedded in gas-rich protogalaxies at redshifts z ≳ 10. We model the effects of gas drag on the BHs' orbits, and allow BHs to grow via gas accretion, including a mode of hyper-Eddington accretion in which photon trapping and rapid gas inflow suppress any negative radiative feedback. Most initial BH configurations lead to the formation of one (but never more than one) IMBH in the centre of the protogalaxy, reaching a mass of 103-5 M⊙ through hyper-Eddington growth. Our results suggest a viable pathway to forming the earliest massive BHs in the centres of early galaxies. We also find that the nuclear IMBH typically captures a stellar-mass BH companion, making these systems observable in gravitational waves as extreme mass-ratio inspirals with eLISA.

  6. High-resolution Studies of Charge Exchange in Supernova Remnants with Magellan, XMM-Newton, and Micro-X

    NASA Astrophysics Data System (ADS)

    Heine, Sarah N.; Figueroa-Feliciano, Enectali; Castro, Daniel

    2015-01-01

    Charge exchange, the semi-resonant transfer of an electron from a neutral atom to an excited state in an energetic ion, can occur in plasmas where energetic ions are incident on a cold, at least partially neutral gas. Supernova remnants, especially in the immediate shock region, provide conditions conducive to charge exchange. The emission from post charge-exchange ions as the captured electron cascades down to the ground state, can shed light on the physical conditions of the shock and the immediate post-shock material, providing an important tool to understanding supernova explosions and their aftermath.I present a study of charge exchange in the galactic supernova remnant G296.1-0.5 in two bands: the optical and the X-ray. The optical study, performed using both imaging and spectroscopy from the IMACS instrument on the Magellan Baade Telescope at Las Companas Observatory, seeks to identify `Balmer-dominated shocks' in the remnant, which occur when charge exchange occurs between hot, post-shock protons and colder neutral hydrogen in the environment. The X-ray study probes line ratios in dispersed spectral data obtained with XMM-Newton RGS from an X-ray lobe in the NW of the remnant to hunt for signatures of charge exchange. The dispersed data are degraded by the extended nature of the source, blending many of the lines.We are working towards the future of spectroscopic studies in the X-ray for such extended sources with Micro-X: a sounding rocket-borne, high energy resolution X-ray telescope, utilizing an array of microcalorimeters to achieve high energy resolution for extended sources. I describe the design and commissioning of the payload and the steps toward launch, which is anticipated in the summer of 2015.

  7. Observations of nine supernova remnants at 10.6 GHz

    NASA Technical Reports Server (NTRS)

    Becker, R. H.; Kundu, M. R.

    1975-01-01

    Intensity contour and polarization observation maps of nine supernova remnants at a microwave frequency are presented and discussed. The data provided are the highest-frequency (10.6 GHz) measurements to date for several of these sources and should therefore be useful in determining their spectra. Polarization ranges from 2 or 3% to as high as 40-50%. Integrated fluxes for the sources vary from about 3 to more than 25.

  8. Cosmic Ray and Tev Gamma Ray Generation by Quasar Remnants

    NASA Technical Reports Server (NTRS)

    Boldt, Elihu; Loewenstein, Michael; White, Nicholas E. (Technical Monitor)

    2000-01-01

    Results from new broadband (radio to X-ray) high-resolution imaging studies of the dormant quasar remnant cores of nearby giant elliptical galaxies are now shown to permit the harboring of compact dynamos capable of generating the highest energy cosmic ray particles and associated curvature radiation of TeV photons. Confirmation would imply a global inflow of interstellar gas all the way to the accretion powered supermassive black hole at the center of the host galaxy.

  9. Recurrent Ectopic Pregnancy in the Tubal Remnant after Salpingectomy

    PubMed Central

    Samiei-Sarir, Bahareh; Diehm, Christopher

    2013-01-01

    We present two cases of ectopic pregnancy located within the remnant tube following ipsilateral salpingectomy. This particular pathology is rare and yet has significant consequences for the patient, with mortality rates 10–15 times higher than other ectopic pregnancies. It demonstrates that salpingectomy does not exclude ectopic pregnancy on the ipsilateral side. We suggest careful clinical consideration and bring attention to the current surgical technique. PMID:24151570

  10. Midbody remnant licenses primary cilia formation in epithelial cells.

    PubMed

    Ott, Carolyn M

    2016-08-01

    Tethered midbody remnants dancing across apical microvilli, encountering the centrosome, and beckoning forth a cilium-who would have guessed this is how polarized epithelial cells coordinate the end of mitosis and the beginning of ciliogenesis? New evidence from Bernabé-Rubio et al. (2016. J. Cell Biol http://dx.doi.org/10.1083/jcb.201601020) supports this emerging model. PMID:27482049

  11. Radio-Quiet Pulsars and Point Sources in Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Helfand, David

    2002-04-01

    Since Baade and Zwicky made their prescient remark identifying the central blue star in the Crab Nebula as a neutron star, this pulsar's period has increased by 0.9 msec, turning 10^48 ergs of rotational kinetic energy into a relativistic wind that has been deposited in its surroundings. This makes the compact remnant of the supernova of 1054 AD highly conspicuous. It also makes this remnant highly anomalous. Nowhere else in the Galaxy does such a luminous young pulsar exists, despite the fact that at least half a dozen core-collapse supernovae have occurred since the Crab's birth. Indeed, the newly discovered central object in Cas A is four orders of magnitude less luminous in the X-ray band. While the Chandra and XMM-Newton Observatories are discovering an increasing number of Crab-like synchrotron nebulae (albeit, far less luminous than the prototype), they are also revealing X-ray point sources inside supernova remnants that lack detectable radio pulses and show no evidence of a relativistic outflow to power a surrounding nebula. I will provide an inventory of these objects, discuss whether or not truly radio-silent young neutron stars exist, and speculate on the emission mechanisms and power sources which make such objects shine. I will conclude with a commentary on the implications of this population for the distributions of pulsar birth parameters such as spin period, magnetic field strength, and space velocity, as well as offer a glimpse of what future observations might reveal about the demographics of core-collapse remnants.

  12. Spatially resolved spectroscopy of young supernova remnants observed with Chandra

    NASA Astrophysics Data System (ADS)

    Stage, M. D.; Allen, G. E.; Houck, J. C.

    The Advanced CCD Imaging Spectrometer (ACIS) detectors on Chandra have captured the highest resolution X-ray images of several supernova remnants. These images of the shocks, filaments and interactions of the supernova shell with the interstellar medium (or in some cases central objects) are spectacular not only for the incredible imaging clarity they provide, but perhaps more so for the integrated spectral information they contain. Yet the volume of this spatial and spectral data--reaching a new extreme with the megasecond observation of Cassiopeia A this spring--can provide a challenge for analysis. Using a suite of software tools developed for use with the ISIS spectral fitting package, and utilzing distributed processing, we have mapped the variation of spectral line and continnum features throughout the Cassiopeia A and other supernova remnants. We present maps of the elemental distribution, distribution of thermal and non-thermal emission, and plasma temperatures for tens of thousands of individual regions in the remnants. These maps include the results of an analysis of the new megasecond observation of Cas A.

  13. Gravitational Waves from the Remnants of the First Stars

    NASA Astrophysics Data System (ADS)

    Hartwig, Tilman; Volonteri, Marta; Bromm, Volker; Klessen, Ralf S.; Barausse, Enrico; Magg, Mattis; Stacy, Athena

    2016-04-01

    Gravitational waves (GWs) provide a revolutionary tool to investigate yet unobserved astrophysical objects. Especially the first stars, which are believed to be more massive than present-day stars, might be indirectly observable via the merger of their compact remnants. We develop a self-consistent, cosmologically representative, semi-analytical model to simulate the formation of the first stars. By extrapolating binary stellar evolution models at 10 % solar metallicity to metal-free stars, we track the individual systems until the coalescence of the compact remnants. We estimate the contribution of primordial stars to the merger rate density and to the detection rate of the Advanced Laser Interferometer Gravitational-Wave Observatory (aLIGO). Owing to their higher masses, the remnants of primordial stars produce strong GW signals, even if their contribution in number is relatively small. We find a probability of ≳ 1% that the current detection GW150914 is of primordial origin. We estimate that aLIGO will detect roughly 1 primordial BH-BH merger per year for the final design sensitivity, although this rate depends sensitively on the primordial initial mass function. Turning this around, the detection of black hole mergers with a total binary mass of ˜ 300 M⊙ would enable us to constrain the primordial initial mass function.

  14. X-Ray Measured Dynamics of Tycho's Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Katsuda, Satoru; Petre, Robert; Hughes, John; Hwang, Una; Yamaguchi, Hiroya; Hayato, Asami; Mori, Koji; Tsunemi, Hiroshi

    2010-01-01

    We present X-ray proper-motion measurements of the forward shock and reverse-shocked ejecta in Tycho's supernova remnant, based on three sets of archival Chandra data taken in 2000, 2003, and 2007. We find that the proper motion of the edge of the remnant (i.e., the forward shock and protruding ejecta knots) varies from 0.''20 yr-1 (expansion index m = 0.33, where R = tm ) to 0.''40 yr-1 (m = 0.65) with azimuthal angle in 2000-2007 measurements, and 0.''14 yr-1 (m = 0.26) to 0.''40 yr-1 (m = 0.65) in 2003-2007 measurements. The azimuthal variation of the proper motion and the average expansion index of [approx]0.5 are consistent with those derived from radio observations. We also find proper motion and expansion index of the reverse-shocked ejecta to be 0.''21-0.''31 yr-1 and 0.43-0.64, respectively. From a comparison of the measured m-value with Type Ia supernova evolutionary models, we find a pre-shock ambient density around the remnant of [less, similar]0.2 cm-3.

  15. FERMI LARGE AREA TELESCOPE DETECTION OF SUPERNOVA REMNANT RCW 86

    SciTech Connect

    Yuan, Qiang; Huang, Xiaoyuan; Liu, Siming; Zhang, Bing

    2014-04-20

    Using 5.4 yr Fermi Large Area Telescope data, we report the detection of GeV γ-ray emission from the shell-type supernova remnant RCW 86 (G315.4-2.3) with a significance of ∼5.1σ. The data slightly favors an extended emission of this supernova remnant. The spectral index of RCW 86 is found to be very hard, Γ ∼ 1.4, in the 0.4-300 GeV range. A one-zone leptonic model can well fit the multi-wavelength data from radio to very high energy γ-rays. The very hard GeV γ-ray spectrum and the inferred low gas density seem to disfavor a hadronic origin for the γ-rays. The γ-ray behavior of RCW 86 is very similar to several other TeV shell-type supernova remnants, e.g., RX J1713.7-3946, RX J0852.0-4622, SN 1006, and HESS J1731-347.

  16. Structure of merger remnants. II - Progenitors with rotating bulges

    NASA Technical Reports Server (NTRS)

    Hernquist, Lars

    1993-01-01

    Mergers of identical galaxies consisting of self-gravitating disks, bulges, and halos are examined in the context of the suggestion that such events may form elliptical galaxies. Unlike earlier studies, the simulations reported here include effects arising from intrinsic spin of bulges. It is found that the disks and bulges are able to redistribute their angular momentum so that the luminous remnants rotate slowly near their centers. In addition, if the bulges are sufficiently concentrated, the core radii of the remnants are significantly reduced relative to those of end-states formed in mergers between pure stellar disks to the extent that the remnants share structural properties with observed elliptical galaxies. Nevertheless, it does appear that stellar-dynamical mergers between spiral progenitors will represent a viable mechanism for the production of massive elliptical galaxies only if sufficient mass resides already in dense, spheroidal components. These results suggest that any ellipticals formed in this manner having featureless light profiles were victims of a 'disk-bulge conspiracy' analogous to the disk-halo conspiracy thought to give rise to smooth rotation curves in spiral galaxies. Possible observational signatures of mergers are discussed, along with implications of the findings for our understanding of galaxy formation and evolution.

  17. Current status in remnant gastric cancer after distal gastrectomy.

    PubMed

    Ohira, Masaichi; Toyokawa, Takahiro; Sakurai, Katsunobu; Kubo, Naoshi; Tanaka, Hiroaki; Muguruma, Kazuya; Yashiro, Masakazu; Onoda, Naoyoshi; Hirakawa, Kosei

    2016-02-28

    Remnant gastric cancer (RGC) and gastric stump cancer after distal gastrectomy (DG) are recognized as the same clinical entity. In this review, the current knowledges as well as the non-settled issues of RGC are presented. Duodenogastric reflux and denervation of the gastric mucosa are considered as the two main factors responsible for the development of RGC after benign disease. On the other hand, some precancerous circumstances which already have existed at the time of initial surgery, such as atrophic gastritis and intestinal metaplasia, are the main factors associated with RGC after gastric cancer. Although eradication of Helicobacter pylori (H. pylori) in remnant stomach is promising, it is still uncertain whether it can reduce the risk of carcinogenesis. Periodic endoscopic surveillance after DG was reported useful in detecting RGC at an early stage, which offers a chance to undergo minimally invasive endoscopic treatment or laparoscopic surgery and leads to an improved prognosis in RGC patients. Future challenges may be expected to elucidate the benefit of eradication of H. pylori in the remnant stomach if it could reduce the risk for RGC, to build an optimal endoscopic surveillance strategy after DG by stratifying the risk for development of RGC, and to develop a specific staging system for RGC for the standardization of the treatment by prospecting the prognosis. PMID:26937131

  18. A comparison of remnants in noncommutative Bardeen black holes

    NASA Astrophysics Data System (ADS)

    Mehdipour, S. Hamid; Ahmadi, M. H.

    2016-09-01

    We derive the mass term of the Bardeen metric in the presence of a noncommutative geometry induced minimal length. In this setup, the proposal of a stable black hole remnant as a candidate to store information is confirmed. We consider the possibility of having an extremal configuration with one degenerate event horizon and compare different sizes of black hole remnants. As a result, once the magnetic charge g of the noncommutative Bardeen solution becomes larger, both the minimal nonzero mass M0 and the minimal nonzero horizon radius r0 get larger. This means, subsequently, under the condition of an adequate amount of g, the three parameters g, M0, and r0 are in a connection with each other linearly. According to our results, a noncommutative Bardeen black hole is colder than the noncommutative Schwarzschild black hole and its remnant is bigger, so the minimum required energy for the formation of such a black hole at particle colliders will be larger. We also find a closely similar result for the Hayward solution.

  19. Tycho: ambient medium structure by analysis of the supernova remnant

    NASA Astrophysics Data System (ADS)

    Beshley, V.; Dubner, G.; Kuzyo, T.; Miceli, M.; Orlando, S.; Ostrowski, M.; Petruk, O.

    2016-06-01

    The radio (VLA) and X-ray (Chandra) maps of the remnant of the Tycho supernova (SN1572) are used to study the interstellar medium (ISM) density and magnetic field gradients in the ambient medium surrounding the remnant. The analysis uses also the GeV gamma-ray spectrum derived from the recent Fermi data, the radio fluxes from different radio instruments, X-ray spectrum from Suzaku and TeV gamma-ray spectrum from VERITAS. The inferred orientation of ISM density gradient is verified by comparing it to the VLA maps of interstellar medium surrounding the remnant, while the revealed orientation of the magnetic field gradient is checked by measurements of the magnetic field strength in a number of local regions around the shock. The two approaches are applied in order to estimate the magnetic field strength, involving analysis of the temporal variations of the X-ray synchrotron radiation from the shock and modeling the radial X-ray external shock profiles. As a result we reveal that the magnetic field gradient in vicinity of Tycho is almost parallel to the Galactic plane while the interstellar plasma density gradient is almost perpendicular to it. One should note that different approaches adopted in this study lead to fully compatible results.

  20. Gravitational waves from the remnants of the first stars

    NASA Astrophysics Data System (ADS)

    Hartwig, Tilman; Volonteri, Marta; Bromm, Volker; Klessen, Ralf S.; Barausse, Enrico; Magg, Mattis; Stacy, Athena

    2016-07-01

    Gravitational waves (GWs) provide a revolutionary tool to investigate yet unobserved astrophysical objects. Especially the first stars, which are believed to be more massive than present-day stars, might be indirectly observable via the merger of their compact remnants. We develop a self-consistent, cosmologically representative, semi-analytical model to simulate the formation of the first stars. By extrapolating binary stellar-evolution models at 10 per cent solar metallicity to metal-free stars, we track the individual systems until the coalescence of the compact remnants. We estimate the contribution of primordial stars to the merger rate density and to the detection rate of the Advanced Laser Interferometer Gravitational-Wave Observatory (aLIGO). Owing to their higher masses, the remnants of primordial stars produce strong GW signals, even if their contribution in number is relatively small. We find a probability of ≳1 per cent that the current detection GW150914 is of primordial origin. We estimate that aLIGO will detect roughly 1 primordial BH-BH merger per year for the final design sensitivity, although this rate depends sensitively on the primordial initial mass function (IMF). Turning this around, the detection of black hole mergers with a total binary mass of ˜ 300 M⊙ would enable us to constrain the primordial IMF.

  1. Supernova remnant evolution in non-uniform media

    NASA Astrophysics Data System (ADS)

    Ferreira, S. E. S.; de Jager, O. C.

    In this work numerical simulations showing the time evolution of a supernova remnant (SNR) in an uniform and non-uniform intersteller medium (ISM) are presented. For this we use a hydrodynamic model including a kinematic calculation of the interstellar magnetic field. Important parameters include the ejecta mass and energy of the remnant, as well as interstellar medium density and adiabatic index. By varying these we constructed an analytical expression giving the return time of the reverse shock to the origin. We also computed the evolution of the remnant in non-uniform media. As the SNR evolves from one into another medium of higher density a reflection shock is created which is driven back toward the center. As the reflection shock moves inward it also drags some of the compressed ISM field lines with it and heats the inside of the SNR. When a SNR explodes in a medium with a high density and the blast waves propagate into a medium with a lower density a cavity is being blown away changing the geometry of the high density region. Also, once the forward shock moves into the medium of less density, a second reverse shock will start to form in this region.

  2. Are young supernova remnants interacting with circumstellar gas

    SciTech Connect

    Chevalier, R.A.

    1982-08-15

    The young remnants of galactic Type I supernovae (SN 1006, SN 1572, and SN 1604) appear to be interacting with moderately dense gas (n/sub O/> or =0.1 cm/sup -3/). If the gas in the ambient interstellar medium, the observations suggest that gas of this density is fairly pervasive. If the gas is circumstellar, there are important implications for the progenitors of Type I supernovae. A plausible density distribution for circumstellar gas is rhoinfinityr/sup -2/. The expansion of a supernova into such a medium is examined and is compared with expansion into a uniform medium. The two cases can be distinguished on the basis of their density profiles and their rates of expansion. Currently available data factor the hypothesis of expansion in a uniform medium for all three Type I remnants; the evidence is the strongest for SN 1572 and the weakest for SN 1604. Further X-ray and radio observations of the galactic remnants and of extragalactic Type I supernovae should serve to test this hypothesis.

  3. Forward Shock Proper Motions of Kepler's Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Katsuda, S.; Tsunemi, H.; Uchida, H.; Kimura, M.

    2008-12-01

    The X-ray structure of Kepler's supernova remnant shows a rounded shape delineated by forward shocks. We measure proper motions of the forward shocks on overall rims of the remnant, by using archival Chandra data taken in two epochs with time difference of 6.09 yr. The proper motions of the forward shocks on the northern rim are measured to be 0.076'' (±0.032'' ±0.016'') to 0.11'' (±0.014'' ±0.016'') yr-1, while those on the rest of the rims are measured to be 0.15'' (±0.017'' ±0.016'') to 0.30'' (±0.048'' ±0.016'') yr-1 here the first-term errors are statistical uncertainties and the second-term errors are systematic uncertainties. Combining the best-estimated shock velocity of 1660 +/- 120 km s-1 measured for Balmer-dominated filaments in the northern and central portions of the remnant (Sankrit et al. 2005) with the proper motions derived for the forward shocks on the northern rim, we estimate a distance of 3.3+1.6-0.4 kpc to the remnant. We measure the expansion indices, m (defined as R propto tm), to be 0.47-0.82 for most of the rims. These values are consistent with those expected in Type Ia SN explosion models, in which the ejecta and the circumstellar medium have power-law density profiles whose indices are 5-7 and 0-2, respectively. In addition, we should note the slower expansion on the northern rim than that on the southern rim. This is likely caused by the inhomogeneous circumstellar medium; the density of the circumstellar medium is higher in the north than that in the south of the remnant. The newly estimated geometric center, around which we believe the explosion point exists, is located at ~5'' offset to the north of the radio center.

  4. Optimal management of the pancreatic remnant after pancreaticoduodenectomy.

    PubMed Central

    Marcus, S G; Cohen, H; Ranson, J H

    1995-01-01

    OBJECTIVE: The authors evaluated methods of operative management of the pancreatic remnant after pancreaticoduodenectomy. SUMMARY BACKGROUND DATA: Despite reductions in mortality after pancreaticoduodenectomy, leakage from the pancreatic remnant still may cause significant morbidity. Patients with small, unobstructed pancreatic ducts or soft, friable pancreata are at particularly high risk. Although numerous surgical techniques have been described to avoid such complications, no single method is suitable for all patients. METHODS: The authors retrospectively reviewed the medical records of 114 consecutive patients who underwent pancreaticoduodenectomy. Sixty-nine patients were men (61%) and 45 were women (39%), with median age 66 years. Underlying disease was malignant in 87 (76%) and benign in 27 (24%). Patients were divided into groups based on risk for postoperative pancreatic fistula and on the operative management of the pancreatic remnant. Sixty-eight patients underwent end-to-side pancreaticojejunostomy, 13 of whom were high risk (group 1A) and 55 of whom were low risk (group 1B). Thirty-seven patients, all high risk, had either pancreatic duct closure by oversewing (N = 19, group 2) or end-to-end pancreaticojejunal invagination (N = 18, group 3). Nine patients underwent total pancreatectomy (group 4). Morbidity related to prolonged pancreatic drainage (PPD) of greater than 20 days was determined. RESULTS: Overall incidence of PPD was 17% and caused the only death. Patients considered high risk for postoperative pancreatic fistula had a 36% incidence of PPD compared with 2% in patients considered low risk (p < 0.0001). Prolonged pancreatic drainage frequency related to the method of pancreatic remnant management was as follows: group 1A, 15%; group 1B, 2%; group 2, 79%; and group 3, 6% (p < 0.001 for group 2 vs. other groups). No serious sequelae followed PPD in 15 patients (79%); however, 4 patients required reoperation for pseudocyst or abscess drainage

  5. EVOLUTION OF POST-IMPACT REMNANT HELIUM STARS IN TYPE Ia SUPERNOVA REMNANTS WITHIN THE SINGLE-DEGENERATE SCENARIO

    SciTech Connect

    Pan, Kuo-Chuan; Ricker, Paul M.; Taam, Ronald E. E-mail: pmricker@illinois.edu

    2013-08-10

    The progenitor systems of Type Ia supernovae (SNe Ia) are still under debate. Based on recent hydrodynamics simulations, non-degenerate companions in the single-degenerate scenario (SDS) should survive the supernova (SN) impact. One way to distinguish between the SDS and the double-degenerate scenario is to search for the post-impact remnant stars (PIRSs) in SN Ia remnants. Using a technique that combines multi-dimensional hydrodynamics simulations with one-dimensional stellar evolution simulations, we have examined the post-impact evolution of helium-rich binary companions in the SDS. It is found that these helium-rich PIRSs (He PIRSs) dramatically expand and evolve to a luminous phase (L {approx} 10{sup 4} L{sub Sun }) about 10 yr after an SN explosion. Subsequently, they contract and evolve to become hot blue-subdwarf-like (sdO-like) stars by releasing gravitational energy, persisting as sdO-like stars for several million years before evolving to the helium red-giant phase. We therefore predict that a luminous OB-like star should be detectable within {approx}30 yr after the SN explosion. Thereafter, it will shrink and become an sdO-like star in the central regions of SN Ia remnants within star-forming regions for SN Ia progenitors evolved via the helium-star channel in the SDS. These He PIRSs are predicted to be rapidly rotating (v{sub rot} {approx}> 50 km s{sup -1}) and to have high spatial velocities (v{sub linear} {approx}> 500 km s{sup -1}). Furthermore, if SN remnants have diffused away and are not recognizable at a later stage, He PIRSs could be an additional source of single sdO stars and/or hypervelocity stars.

  6. Apolipoprotein A-V Deficiency Results in MarkedHypertriglyceridemia Attributable to Decreased Lipolysis ofTriglyceride-Rich Lipoproteins and Removal of Their Remnants

    SciTech Connect

    Grosskopf, Itamar; Baroukh, Nadine; Lee, Sung-Joon; Kamari,Yehuda; Harats, Dror; Rubin, Edward M.; Pennacchio, Len A.; Cooper, AllenD.

    2005-09-01

    Objective--ApoAV, a newly discovered apoprotein, affectsplasma triglyceride level. To determine how this occurs, we studiedtriglyceride-rich lipoprotein (TRL) metabolism in mice deficient inapoAV. Methods and Results No significant difference in triglycerideproduction rate was found between apoa5_/_ mice and controls. Thepresence or absence of apoAV affected TRL catabolism. After the injectionof 14C-palmitate and 3H-cholesterol labeled chylomicrons and 125I-labeledchylomicron remnants, the disappearance of 14C, 3H, and 125I wassignificantly slower in apoa5_/_ mice relative to controls. This wasbecause of diminished lipolysis of TRL and the reduced rate of uptake oftheir remnants in apoa5_/_ mice. Observed elevated cholesterol level wascaused by increased high-density lipoprotein (HDL) cholesterol inapoa5_/_ mice. VLDL from apoa5_/_ mice were poor substrate forlipoprotein lipase, and did not bind to the low-density lipoprotein (LDL)receptor as well as normal very-low-density lipoprotein (VLDL). LDLreceptor levels were slightly elevated in apoa5_/_ mice consistent withlower remnant uptake rates. These alterations may be the result of thelower apoE-to-apoC ratio found in VLDL isolated from apoa5_/_mice.Conclusions These results support the hypothesis that the absence ofapoAV slows lipolysis of TRL and the removal of their remnants byregulating their apoproteins content after secretion.

  7. THE [O III] NEBULA OF THE MERGER REMNANT NGC 7252: A LIKELY FAINT IONIZATION ECHO

    SciTech Connect

    Schweizer, Francois; Kelson, Daniel D.; Villanueva, Edward V.; Seitzer, Patrick; Walth, Gregory L.

    2013-08-20

    We present images and spectra of a {approx}10 kpc-sized emission-line nebulosity discovered in the prototypical merger remnant NGC 7252 and dubbed the ''[O III] nebula'' because of its dominant [O III] {lambda}5007 line. This nebula seems to yield the first sign of episodic active galactic nucleus (AGN) activity still occurring in the remnant, {approx}220 Myr after the coalescence of two gas-rich galaxies. Its location and kinematics suggest it belongs to a stream of tidal-tail gas falling back into the remnant. Its integrated [O III] {lambda}5007 luminosity is 1.4 Multiplication-Sign 10{sup 40} erg s{sup -1}, and its spectrum features some high-excitation lines, including He II {lambda}4686. In diagnostic line-ratio diagrams, the nebula lies in the domain of Seyfert galaxies, suggesting that it is photoionized by a source with a power-law spectrum. Yet, a search for AGN activity in NGC 7252 from X-rays to radio wavelengths yields no detection, with the most stringent upper limit set by X-ray observations. The upper luminosity limit of L{sub 2-10{sub keV,0}}<5 Multiplication-Sign 10{sup 39} erg s{sup -1} estimated for the nucleus is {approx}10{sup 3} times lower than the minimum ionizing luminosity of {approx}> 5 Multiplication-Sign 10{sup 42} erg s{sup -1} necessary to excite the nebula. This large discrepancy suggests that the nebula is a faint ionization echo excited by a mildly active nucleus that has declined by {approx}3 orders of magnitude over the past 20,000-200,000 yr. In many ways this nebula resembles the prototypical ''Hanny's Voorwerp'' near IC 2497, but its size is 3 Multiplication-Sign smaller and its [O III] luminosity {approx}100 Multiplication-Sign lower. We propose that it be classified as an extended emission-line region (EELR). The [O III] nebula is then the lowest-luminosity ionization echo and EELR discovered so far, indicative of recent, probably sputtering AGN activity of Seyfert-like intensity in NGC 7252.

  8. Exploring properties of high-density matter through remnants of neutron-star mergers

    NASA Astrophysics Data System (ADS)

    Bauswein, Andreas; Stergioulas, Nikolaos; Janka, Hans-Thomas

    2016-03-01

    Remnants of neutron-star mergers are essentially massive, hot, differentially rotating neutron stars, which are initially strongly oscillating. As such they represent a unique probe for high-density matter because the oscillations are detectable via gravitational-wave measurements and are strongly dependent on the equation of state. The impact of the equation of state for instance is apparent in the frequency of the dominant oscillation mode of the remnant. For a fixed total binary mass a tight relation between the dominant postmerger oscillation frequency and the radii of nonrotating neutron stars exists. Inferring observationally the dominant postmerger frequency thus determines neutron star radii with high accuracy of the order of a few hundred meters. By considering symmetric and asymmetric binaries of the same chirp mass, we show that the knowledge of the binary mass ratio is not critical for this kind of radius measurements. We perform simulations which show that initial intrinsic neutron star rotation is unlikely to affect this method of constraining the high-density equation of state. We also summarize different possibilities about how the postmerger gravitational-wave emission can be employed to deduce the maximum mass of nonrotating neutron stars. We clarify the nature of the three most prominent features of the postmerger gravitational-wave spectrum and argue that the merger remnant can be considered to be a single, isolated, self-gravitating object that can be described by concepts of asteroseismology. We sketch how the consideration of the strength of secondary gravitational-wave peaks leads to a classification scheme of the gravitational-wave emission and postmerger dynamics. The understanding of the different mechanisms shaping the gravitational-wave signal yields a physically motivated analytic model of the gravitational-wave emission, which may form the basis for template-based gravitational-wave data analysis. We explore the observational

  9. OXYGEN-RICH SUPERNOVA REMNANT IN THE LARGE MAGELLANIC CLOUD

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This is a NASA Hubble Space Telescope image of the tattered debris of a star that exploded 3,000 years ago as a supernova. This supernova remnant, called N132D, lies 169,000 light-years away in the satellite galaxy, the Large Magellanic Cloud. A Hubble Wide Field Planetary Camera 2 image of the inner regions of the supernova remnant shows the complex collisions that take place as fast moving ejecta slam into cool, dense interstellar clouds. This level of detail in the expanding filaments could only be seen previously in much closer supernova remnants. Now, Hubble's capabilities extend the detailed study of supernovae out to the distance of a neighboring galaxy. Material thrown out from the interior of the exploded star at velocities of more than four million miles per hour (2,000 kilometers per second) plows into neighboring clouds to create luminescent shock fronts. The blue-green filaments in the image correspond to oxygen-rich gas ejected from the core of the star. The oxygen-rich filaments glow as they pass through a network of shock fronts reflected off dense interstellar clouds that surrounded the exploded star. These dense clouds, which appear as reddish filaments, also glow as the shock wave from the supernova crushes and heats the clouds. Supernova remnants provide a rare opportunity to observe directly the interiors of stars far more massive than our Sun. The precursor star to this remnant, which was located slightly below and left of center in the image, is estimated to have been 25 times the mass of our Sun. These stars 'cook' heavier elements through nuclear fusion, including oxygen, nitrogen, carbon, iron etc., and the titanic supernova explosions scatter this material back into space where it is used to create new generations of stars. This is the mechanism by which the gas and dust that formed our solar system became enriched with the elements that sustain life on this planet. Hubble spectroscopic observations will be used to determine the exact

  10. N157B: X-ray evidence for a Crab-like supernova remnant

    NASA Technical Reports Server (NTRS)

    Gotthelf, Eric V.; Wang, Q. Daniel

    1996-01-01

    The X-ray observation of the supernova remnant N 157B is described. The Rosat High Resolution Imager (HRI) X-ray emission from the remnant was decomposed into point-like sources. The spectra showed abundance-enhanced neon and magnesium lines, indicating that the remnant originated in a massive progenitor. The flat and featureless data from the Advanced Satellite for Cosmology and Astrophysics (ASCA) confirm the Crab-like nature of the remnant. By interpreting both the thermal spectral component and the shell as representing the remnant's outer shock, the age of the remnant was estimated to be 4 x 10(exp 3) yr and the energy release approximately 2 x 10(exp 50) erg.

  11. ROSAT HRI observations of Magellanic Cloud supernova remnants

    NASA Technical Reports Server (NTRS)

    Hughes, John P.

    1994-01-01

    Analysis of deep ROSAT high resolution imager (HRI) observations of two oxygen-rich supernova remnants (SNR's) in the Magellanic Clouds is described. For N132D, I exploit the limited spectral information provided by the HRI to investigate arcsecond scale spectral variations. I find that there is a region of harder X-ray emission near the southern limb and regions of softer emission near the center and northwestern limb. The remnant is believed to be interacting with a molecular cloud and the harder emission to the south is explained as a result of increased absorption along the line-of-sight there. I argue that the softer emission comes from X-ray emitting material with an enhanced abundance of oxygen. For the second SNR, E0102.2 72.2, the spatial structure is investigated in detail using two-dimensional image fitting techniques. Evidence is found for a ring-like and a spherically symmetric shell-like component both of which were modeled as homogeneous regions. In addition, a significant fraction of the observed flux (approximately 11 percent) must come from a resolved clumped component. A comparison with optical and radio imagery is made to provide a physical basis for the components identified in the X-ray analysis. The mass of X-ray emitting gas in the remnant is estimated and a value of approximately 75 M(solar mass) was determined. The dominant uncertainty on this quantity is the extent of unresolved clumping in the X-ray gas. Such clumping would tend to reduce the mass estimate by f(exp 1/2), where f is the mean volume filling factor of the gas.

  12. Observations of TeV Gamma Rays from Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Buckley, James H.

    1994-12-01

    Measurements of the gamma ray flux from a number of supernova remnants (SNRs) at energies above 250 GeV have been made with the Whipple Imaging air \\v Cerenkov detector. Observation of the gamma ray emission of SNRs at energies above 1 GeV should provide a sensitive test of shock acceleration models of particle acceleration in SNRs. Gamma-ray luminosities of supernova remnants are well constrained by the observed supernova rate and the cosmic ray flux if supernovae are indeed the source of cosmic rays. Drury et al. (Astron. Astrophys. 287, 959 (1994)) predict that the luminosity of nearby Sedov-phase SNRs should be observable by the Whipple telescope. In this model, diffusive shock acceleration produces energetic charged particles which interact with the ambient medium forming gamma rays. There is an indication that a number of unidentified EGRET sources may correspond to supernova remnants (G. Kanbach, private communication), although at these energies (>100 MeV) the diffuse background is somewhat uncertain. Measurements of the gamma-ray flux with the Whipple instrument have a similar sensitivity to the EGRET detector for a source spectral index of 2.15, and less sensitivity to diffuse background. A number of observations of SNRs including: Tycho, W66, IC443, and others have been made. Currently for Tycho an upper limit of 9times 10(-12) cm(-2) sec(-1) is obtained. The status of these observations will be presented, and it will be shown that these measurements combined with the EGRET observations are beginning to provide a useful constraint on models of cosmic ray origin. Gamma-ray observations may also be used to constrain models of particle acceleration in SNRs exhibiting pulser-powered synchrotron nebula (plerions). The status of observations of this class of objects, including the Crab nebula, will also be presented. Supported in part by the U.S. Dept. of Energy.

  13. PHYSICAL STRUCTURE AND NATURE OF SUPERNOVA REMNANTS IN M101

    SciTech Connect

    Franchetti, Nicholas A.; Gruendl, Robert A.; Chu, You-Hua; Dunne, Bryan C.; Pannuti, Thomas G.; Grimes, Caleb K.; Kuntz, Kip D.; Chen, C.-H. Rosie; Aldridge, Tabitha M. E-mail: gruendl@astro.illinois.edu E-mail: bdunne@astro.illinois.edu E-mail: ckgrim01@moreheadstate.edu E-mail: rchen@mpifr-bonn.mpg.de

    2012-04-15

    Supernova remnant (SNR) candidates in the giant spiral galaxy M101 have been previously identified from ground-based H{alpha} and [S II] images. We have used archival Hubble Space Telescope (HST) H{alpha} and broadband images as well as stellar photometry of 55 SNR candidates to examine their physical structure, interstellar environment, and underlying stellar population. We have also obtained high-dispersion echelle spectra to search for shocked high-velocity gas in 18 SNR candidates, and identified X-ray counterparts to SNR candidates using data from archival observations made by the Chandra X-Ray Observatory. Twenty-one of these 55 SNR candidates studied have X-ray counterparts, although one of them is a known ultraluminous X-ray source. The multi-wavelength information has been used to assess the nature of each SNR candidate. We find that within this limited sample, {approx}16% are likely remnants of Type Ia SNe and {approx}45% are remnants of core-collapse SNe. In addition, about {approx}36% are large candidates which we suggest are either superbubbles or OB/H II complexes. Existing radio observations are not sensitive enough to detect the non-thermal emission from these SNR candidates. Several radio sources are coincident with X-ray sources, but they are associated with either giant H II regions in M101 or background galaxies. The archival HST H{alpha} images do not cover the entire galaxy and thus prevents a complete study of M101. Furthermore, the lack of HST [S II] images precludes searches for small SNR candidates which could not be identified by ground-based observations. Such high-resolution images are needed in order to obtain a complete census of SNRs in M101 for a comprehensive investigation of the distribution, population, and rates of SNe in this galaxy.

  14. Asymmetries in the Expansion and Emission from Young Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Vigh, Carlos D.; Velázquez, Pablo F.; Gómez, Daniel O.; Reynoso, Estela M.; Esquivel, Alejandro; Matias Schneiter, E.

    2011-01-01

    We present two-dimensional and three-dimensional numerical simulations of asymmetric young supernova remnants (SNRs) carried out with the hydrodynamical code YGUAZÚ, aiming to quantitatively assess the role of different factors that may give origin to such asymmetries in their expansion. In particular, we are interested in modeling the morphology of Tycho's SNR to address whether the companion star of a Type Ia supernova progenitor has played a role in the subsequent evolution of the remnant. With the results from the numerical simulations, we can not only study the morphology of the SNR but also compute the emission of the remnant in different spectral bands. In particular, we simulate X-ray maps, which can be directly compared to recent and previous observations of Tycho's SNR. Our results suggest that the most likely explanation for Tycho's morphology is that after the supernova (SN) explosion the shock front stripped the envelope of its companion. We represent this effect by adding a conical region with an enhanced density into the initial sphere immediately after the explosion. Assuming that Tycho's companion was a massive red giant star, we explore different values of the angle of aperture and mass excess of the conical region. A good agreement with observational data was found for the model with a mass excess of 0.3 M sun and an aperture of 90°. After the collision with the SN shock wave, the companion would become an He-rich star. This scenario would gain observational support if a star with these characteristics is found in the vicinity of the center of the SN explosion.

  15. SPECTRUM OF GALACTIC COSMIC RAYS ACCELERATED IN SUPERNOVA REMNANTS

    SciTech Connect

    Ptuskin, Vladimir; Zirakashvili, Vladimir; Seo, Eun-Suk

    2010-07-20

    The spectra of high-energy protons and nuclei accelerated by supernova remnant (SNR) shocks are calculated, taking into account magnetic field amplification and Alfvenic drift both upstream and downstream of the shock for different types of SNRs during their evolution. The maximum energy of accelerated particles may reach 5 x 10{sup 18} eV for Fe ions in Type IIb SNRs. The calculated energy spectrum of cosmic rays after propagation through the Galaxy is in good agreement with the spectrum measured at the Earth.

  16. Final remnant of binary black hole mergers: Multipolar analysis

    SciTech Connect

    Owen, Robert

    2009-10-15

    Methods are presented to define and compute source multipoles of dynamical horizons in numerical relativity codes, extending previous work in the isolated and dynamical horizon formalisms to allow for horizons that are not axisymmetric. These methods are then applied to a binary black hole merger simulation, providing evidence that the final remnant is a Kerr black hole, both through the (spatially) gauge-invariant recovery of the geometry of the apparent horizon, and through a detailed extraction of quasinormal ringing modes directly from the strong-field region.

  17. Remnant percolative disorder in highly-cured networks

    SciTech Connect

    Adolf, D.; Hance, B.; Martin, J.E. )

    1993-05-24

    The authors have previously reported viscoelastic measurements demonstrating that fully-cured networks and critical gels exhibit similar relaxation spectra, implying that fully-cured networks are somewhat ill- connected. Here, they present restricted valence percolation simulations of networks well beyond the percolation transition that explicitly display remnant disorder over length scales less than the correlation length of the network. They conclude that the topology of highly-cured networks is not well described by a regular three- dimensional tennis net but is ill-connected over length scales that correspond to relaxation modes of practical interest.

  18. Minimum length, extra dimensions, modified gravity and black hole remnants

    NASA Astrophysics Data System (ADS)

    Maziashvili, Michael

    2013-03-01

    We construct a Hilbert space representation of minimum-length deformed uncertainty relation in presence of extra dimensions. Following this construction, we study corrections to the gravitational potential (back reaction on gravity) with the use of correspondingly modified propagator in presence of two (spatial) extra dimensions. Interestingly enough, for r→0 the gravitational force approaches zero and the horizon for modified Schwarzschild-Tangherlini space-time disappears when the mass approaches quantum-gravity energy scale. This result points out to the existence of zero-temperature black hole remnants in ADD brane-world model.

  19. Cosmic ray induced ionisation of a molecular cloud shocked by the W28 supernova remnant

    NASA Astrophysics Data System (ADS)

    Vaupré, S.; Hily-Blant, P.; Ceccarelli, C.; Dubus, G.; Gabici, S.; Montmerle, T.

    2014-08-01

    Cosmic rays are an essential ingredient in the evolution of the interstellar medium, as they dominate the ionisation of the dense molecular gas, where stars and planets form. However, since they are efficiently scattered by the galactic magnetic fields, many questions remain open, such as where exactly they are accelerated, what is their original energy spectrum, and how they propagate into molecular clouds. In this work we present new observations and discuss in detail a method that allows us to measure the cosmic ray ionisation rate towards the molecular clouds close to the W28 supernova remnant. To perform these measurements, we use CO, HCO+, and DCO+ millimetre line observations and compare them with the predictions of radiative transfer and chemical models away from thermodynamical equilibrium. The CO observations allow us to constrain the density, temperature, and column density towards each observed position, while the DCO+/HCO+ abundance ratios provide us with constraints on the electron fraction and, consequently, on the cosmic ray ionisation rate. Towards positions located close to the supernova remnant, we find cosmic ray ionisation rates much larger (≳100) than those in standard galactic clouds. Conversely, towards one position situated at a larger distance, we derive a standard cosmic ray ionisation rate. Overall, these observations support the hypothesis that the γ rays observed in the region have a hadronic origin. In addition, based on CR diffusion estimates, we find that the ionisation of the gas is likely due to 0.1-1 GeV cosmic rays. Finally, these observations are also in agreement with the global picture of cosmic ray diffusion, in which the low-energy tail of the cosmic ray population diffuses at smaller distances than the high-energy counterpart.

  20. Spectral and morphological analysis of the remnant of supernova 1987A with ALMA and ATCA

    SciTech Connect

    Zanardo, Giovanna; Staveley-Smith, Lister; Indebetouw, Remy; Chevalier, Roger A.; Matsuura, Mikako; Barlow, Michael J.; Gaensler, Bryan M.; Fransson, Claes; Lundqvist, Peter; Manchester, Richard N.; Baes, Maarten; Kamenetzky, Julia R.; Lakićević, Maša; Marcaide, Jon M.; Meixner, Margaret; Ng, C.-Y.; Park, Sangwook; and others

    2014-12-01

    We present a comprehensive spectral and morphological analysis of the remnant of supernova (SN) 1987A with the Australia Telescope Compact Array (ATCA) and the Atacama Large Millimeter/submillimeter Array (ALMA). The non-thermal and thermal components of the radio emission are investigated in images from 94 to 672 GHz (λ 3.2 mm to 450 μm), with the assistance of a high-resolution 44 GHz synchrotron template from the ATCA, and a dust template from ALMA observations at 672 GHz. An analysis of the emission distribution over the equatorial ring in images from 44 to 345 GHz highlights a gradual decrease of the east-to-west asymmetry ratio with frequency. We attribute this to the shorter synchrotron lifetime at high frequencies. Across the transition from radio to far infrared, both the synchrotron/dust-subtracted images and the spectral energy distribution (SED) suggest additional emission beside the main synchrotron component (S {sub ν}∝ν{sup –0.73}) and the thermal component originating from dust grains at T ∼ 22 K. This excess could be due to free-free flux or emission from grains of colder dust. However, a second flat-spectrum synchrotron component appears to better fit the SED, implying that the emission could be attributed to a pulsar wind nebula (PWN). The residual emission is mainly localized west of the SN site, as the spectral analysis yields –0.4 ≲ α ≲ –0.1 across the western regions, with α ∼ 0 around the central region. If there is a PWN in the remnant interior, these data suggest that the pulsar may be offset westward from the SN position.

  1. Spitzer Space Telescope Observations of Kepler's Supernova Remnant: A Detailed Look at the Circumstellar Dust Component

    NASA Astrophysics Data System (ADS)

    Blair, William P.; Ghavamian, Parviz; Long, Knox S.; Williams, Brian J.; Borkowski, Kazimierz J.; Reynolds, Stephen P.; Sankrit, Ravi

    2007-06-01

    We present 3.6-160 μm infrared images of Kepler's supernova remnant (SN 1604) obtained with the IRAC and MIPS instruments on the Spitzer Space Telescope. We also present MIPS SED low-resolution spectra in the 55-95 μm region. The observed emission in the MIPS 24 μm band shows the entire shell. Emission in the MIPS 70 μm and IRAC 8 μm bands is seen only from the brightest regions of 24 μm emission, which also correspond to the regions seen in optical Hα images. Shorter wavelength IRAC images are increasingly dominated by stars, although faint filaments are discernible. The SED spectrum of shows a faint continuum dropping off to longer wavelengths and confirms that strong line emission does not dominate the mid-IR spectral region. The emission we see is due primarily to warm dust emission from dust heated by the primary blast wave; no excess infrared emission is observed in regions where supernova ejecta are seen in X-rays. We use models of the dust to interpret the observed 70/24 μm ratio and constrain the allowed range of temperatures and densities. We estimate the current mass of dust in the warm dust component to be 5.4×10-4 Msolar, and infer an original mass of about 3×10-3 Msolar before grain sputtering. The MIPS 160 μm band shows no emission belonging to the remnant. We place a conservative but temperature-dependent upper limit on any cold dust component roughly a factor of 10 below the cold dust mass inferred from SCUBA observations. Finally, we comment on issues relevant to the possible precursor star and the supernova type. Based on observations made with the NASA Spitzer Space Telescope. Spitzer is operated for NASA by the Jet Propulsion Lab.

  2. A high sensitivity search for X-rays from supernova remnants in Aquila

    NASA Technical Reports Server (NTRS)

    Schwartz, D. A.; Bleach, D. A.; Boldt, E. A.; Holt, S. S.; Serlemitsos, P. J.

    1972-01-01

    A high sensitivity scan of the galactic plane was performed to search for 2-20 keV X-rays from supernova remnants. The spectra of five X-ray sources detected between 44 deg and 31 deg longitude, of which only two might be associated with suggested supernova remnants, are reported on. Upper limits are presented for the 19 possible supernova remnants scanned in this survey.

  3. A high-sensitivity search for X-rays from supernova remnants in Aquila.

    NASA Technical Reports Server (NTRS)

    Schwartz, D. A.; Boldt, E. A.; Holt, S. S.; Serlemitsos, P. J.; Bleach, R. D.

    1972-01-01

    A high-sensitivity scan of the galactic plane from 70 to 30 deg was performed to search for 2-20-keV X rays from supernova remnants. The spectra of five X-ray sources detected between 44 and 31 deg longitude are presented, of which only two might be associated with suggested supernova remnants. Upper limits are given for the 19 possible supernova remnants scanned.

  4. Remnant Trees Affect Species Composition but Not Structure of Tropical Second-Growth Forest

    PubMed Central

    Sandor, Manette E.; Chazdon, Robin L.

    2014-01-01

    Remnant trees, spared from cutting when tropical forests are cleared for agriculture or grazing, act as nuclei of forest regeneration following field abandonment. Previous studies on remnant trees were primarily conducted in active pasture or old fields abandoned in the previous 2–3 years, and focused on structure and species richness of regenerating forest, but not species composition. Our study is among the first to investigate the effects of remnant trees on neighborhood forest structure, biodiversity, and species composition 20 years post-abandonment. We compared the woody vegetation around individual remnant trees to nearby plots without remnant trees in the same second-growth forests (“control plots”). Forest structure beneath remnant trees did not differ significantly from control plots. Species richness and species diversity were significantly higher around remnant trees. The species composition around remnant trees differed significantly from control plots and more closely resembled the species composition of nearby old-growth forest. The proportion of old-growth specialists and generalists around remnant trees was significantly greater than in control plots. Although previous studies show that remnant trees may initially accelerate secondary forest growth, we found no evidence that they locally affect stem density, basal area, and seedling density at later stages of regrowth. Remnant trees do, however, have a clear effect on the species diversity, composition, and ecological groups of the surrounding woody vegetation, even after 20 years of forest regeneration. To accelerate the return of diversity and old-growth forest species into regrowing forest on abandoned land, landowners should be encouraged to retain remnant trees in agricultural or pastoral fields. PMID:24454700

  5. Discovery of X-Ray-Emitting O-Ne-Mg-Rich Ejecta in the Galactic Supernova Remnant Puppis A

    NASA Technical Reports Server (NTRS)

    Katsuda, Satoru; Hwang, Una; Petre, Robert; Park, Sangwook; Mori, Koji; Tsunemi, Hiroshi

    2010-01-01

    We report on the discovery of X-ray-emitting O-Ne-Mg-rich ejecta in the middle-aged Galactic O-rich supernova remnant Puppis A with Chandra and XMM-Newton. We use line ratios to identify a low-ionization filament running parallel to the northeastern edge of the remnant that requires super-solar abundances, particularly for O, Ne, and Mg, which we interpret to be from O-Ne-Mg-rich ejecta. Abundance ratios of Ne/O, Mg/O, and Fe/O are measured to be [approx]2, [approx]2, and <0.3 times the solar values. Our spatially resolved spectral analysis from the northeastern rim to the western rim otherwise reveals sub-solar abundances consistent with those in the interstellar medium. The filament is coincident with several optically emitting O-rich knots with high velocities. If these are physically related, the filament would be a peculiar fragment of ejecta. On the other hand, the morphology of the filament suggests that it may trace ejecta heated by a shock reflected strongly off the dense ambient clouds near the northeastern rim.

  6. DISCOVERY OF X-RAY-EMITTING O-Ne-Mg-RICH EJECTA IN THE GALACTIC SUPERNOVA REMNANT PUPPIS A

    SciTech Connect

    Katsuda, Satoru; Hwang, Una; Petre, Robert; Park, Sangwook; Mori, Koji; Tsunemi, Hiroshi

    2010-05-10

    We report on the discovery of X-ray-emitting O-Ne-Mg-rich ejecta in the middle-aged Galactic O-rich supernova remnant Puppis A with Chandra and XMM-Newton. We use line ratios to identify a low-ionization filament running parallel to the northeastern edge of the remnant that requires super-solar abundances, particularly for O, Ne, and Mg, which we interpret to be from O-Ne-Mg-rich ejecta. Abundance ratios of Ne/O, Mg/O, and Fe/O are measured to be {approx}2, {approx}2, and <0.3 times the solar values. Our spatially resolved spectral analysis from the northeastern rim to the western rim otherwise reveals sub-solar abundances consistent with those in the interstellar medium. The filament is coincident with several optically emitting O-rich knots with high velocities. If these are physically related, the filament would be a peculiar fragment of ejecta. On the other hand, the morphology of the filament suggests that it may trace ejecta heated by a shock reflected strongly off the dense ambient clouds near the northeastern rim.

  7. The population of X-ray supernova remnants in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Maggi, P.; Haberl, F.; Kavanagh, P. J.; Sasaki, M.; Bozzetto, L. M.; Filipović, M. D.; Vasilopoulos, G.; Pietsch, W.; Points, S. D.; Chu, Y.-H.; Dickel, J.; Ehle, M.; Williams, R.; Greiner, J.

    2016-01-01

    Aims: We present a comprehensive X-ray study of the population of supernova remnants (SNRs) in the Large Magellanic Cloud (LMC). Using primarily XMM-Newton observations, we conduct a systematic spectral analysis of LMC SNRs to gain new insight into their evolution and the interplay with their host galaxy. Methods: We combined all the archival XMM-Newton observations of the LMC with those of our Very Large Programme LMC survey. We produced X-ray images and spectra of 51 SNRs, out of a list of 59 objects compiled from the literature and augmented with newly found objects. Using a careful modelling of the background, we consistently analysed all the X-ray spectra and measure temperatures, luminosities, and chemical compositions. The locations of SNRs are compared to the distributions of stars, cold gas, and warm gas in the LMC, and we investigated the connection between the SNRs and their local environment, characterised by various star formation histories. We tentatively typed all LMC SNRs, in order to constrain the ratio of core-collapse to type Ia SN rates in the LMC. We also compared the column densities derived from X-ray spectra to H i maps, thus probing the three-dimensional structure of the LMC. Results: This work provides the first homogeneous catalogue of the X-ray spectral properties of SNRs in the LMC. It offers a complete census of LMC remnants whose X-ray emission exhibits Fe K lines (13% of the sample), or reveals the contribution from hot supernova ejecta (39%), which both give clues to the progenitor types. The abundances of O, Ne, Mg, Si, and Fe in the hot phase of the LMC interstellar medium are found to be between 0.2 and 0.5 times the solar values with a lower abundance ratio [α/Fe] than in the Milky Way. The current ratio of core-collapse to type Ia SN rates in the LMC is constrained to NCC/NIa=1.35(-0.24+0.11), which is lower than in local SN surveys and galaxy clusters. Our comparison of the X-ray luminosity functions of SNRs in Local Group

  8. Isotopic Ratio, Isotonic Ratio, Isobaric Ratio and Shannon Information Uncertainty

    NASA Astrophysics Data System (ADS)

    Ma, Chun-Wang; Wei, Hui-Ling

    2014-11-01

    The isoscaling and the isobaric yield ratio difference (IBD) probes, both of which are constructed by yield ratio of fragment, provide cancelation of parameters. The information entropy theory is introduced to explain the physical meaning of the isoscaling and IBD probes. The similarity between the isoscaling and IBD results is found, i.e., the information uncertainty determined by the IBD method equals to β - α determined by the isoscaling (α (β) is the parameter fitted from the isotopic (isotonic) yield ratio).

  9. Searches for Continuous Gravitational Waves from Nine Young Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Aasi, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Ain, A.; Ajith, P.; Alemic, A.; Allen, B.; Allocca, A.; Amariutei, D.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C.; Areeda, J. S.; Ast, S.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Aylott, B. E.; Babak, S.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barbet, M.; Barclay, S.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Bartlett, J.; Barton, M. A.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Bauer, Th. S.; Baune, C.; Bavigadda, V.; Behnke, B.; Bejger, M.; Belczynski, C.; Bell, A. S.; Bell, C.; Benacquista, M.; Bergman, J.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biscans, S.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackburn, L.; Blair, C. D.; Blair, D.; Bloemen, S.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, G.; Bojtos, P.; Bond, C.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, Sukanta; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Buchman, S.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Cadonati, L.; Cagnoli, G.; Calderón Bustillo, J.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Carbognani, F.; Caride, S.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, S.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C.; Colombini, M.; Cominsky, L.; Constancio, M., Jr.; Conte, A.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Coulon, J.-P.; Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Cutler, C.; Dahl, K.; Dal Canton, T.; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dartez, L.; Dattilo, V.; Dave, I.; Daveloza, H.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dereli, H.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; Díaz, M.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Virgilio, A.; Dojcinoski, G.; Dolique, V.; Dominguez, E.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S.; Eberle, T.; Edo, T.; Edwards, M.; Edwards, M.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Essick, R.; Etzel, T.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Fan, X.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Feldbaum, D.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fisher, R. P.; Flaminio, R.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fuentes-Tapia, S.; Fulda, P.; Fyffe, M.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S.; Garufi, F.; Gatto, A.; Gehrels, N.; Gemme, G.; Gendre, B.; Genin, E.; Gennai, A.; Gergely, L. Á.; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gleason, J.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gordon, N.; Gorodetsky, M. L.; Gossan, S.; Gossler, S.; Gouaty, R.; Gräf, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guido, C. J.; Guo, X.; Gushwa, K.; Gustafson, E. K.; Gustafson, R.; Hacker, J.; Hall, E. D.; Hammond, G.; Hanke, M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Heidmann, A.; Heintze, M.; Heinzel, G.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Hofman, D.; Hollitt, S. E.; Holt, K.; Hopkins, P.; Hosken, D. J.; Hough, J.; Houston, E.; Howell, E. J.; Hu, Y. M.; Huerta, E.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh, M.; Huynh-Dinh, T.; Idrisy, A.; Indik, N.; Ingram, D. R.; Inta, R.; Islas, G.; Isler, J. C.; Isogai, T.; Iyer, B. R.; Izumi, K.; Jacobson, M.; Jang, H.; Jaranowski, P.; Jawahar, S.; Ji, Y.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; K, Haris; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kasprzack, M.; Katsavounidis, E.; Katzman, W.; Kaufer, H.; Kaufer, S.; Kaur, T.; Kawabe, K.; Kawazoe, F.; Kéfélian, F.; Keiser, G. M.; Keitel, D.; Kelley, D. B.; Kells, W.; Keppel, D. G.; Key, J. S.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, C.; Kim, K.; Kim, N. G.; Kim, N.; Kim, Y.-M.; King, E. J.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kline, J.; Koehlenbeck, S.; Kokeyama, K.; Kondrashov, V.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Kringel, V.; Krishnan, B.; Królak, A.; Krueger, C.; Kuehn, G.; Kumar, A.; Kumar, P.; Kuo, L.; Kutynia, A.; Landry, M.; Lantz, B.; Larson, S.; Lasky, P. D.; Lazzarini, A.; Lazzaro, C.; Lazzaro, C.; Le, J.; Leaci, P.; Leavey, S.; Lebigot, E.; Lebigot, E. O.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levin, Y.; Levine, B.; Lewis, J.; Li, T. G. F.; Libbrecht, K.; Libson, A.; Lin, A. C.; Littenberg, T. B.; Lockerbie, N. A.; Lockett, V.; Logue, J.; Lombardi, A. L.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J.; Lubinski, M. J.; Lück, H.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Macarthur, J.; MacDonald, T.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña na-Sandoval, F.; Magee, R.; Mageswaran, M.; Maglione, C.; Mailand, K.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandel, I.; Mandic, V.; Mangano, V.; Mangano, V.; Mansell, G. L.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A.; Maros, E.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R. M.; Martynov, D.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McGuire, S. C.; McIntyre, G.; McIver, J.; McLin, K.; McWilliams, S.; Meacher, D.; Meadors, G. D.; Meidam, J.; Meinders, M.; Melatos, A.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyers, P. M.; Mezzani, F.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A.; Miller, J.; Millhouse, M.; Minenkov, Y.; Ming, J.; Mirshekari, S.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moe, B.; Moggi, A.; Mohan, M.; Mohanty, S. D.; Mohapatra, S. R. P.; Moore, B.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Mukherjee, S.; Mullavey, A.; Munch, J.; Murphy, D.; Murray, P. G.; Mytidis, A.; Nagy, M. F.; Nardecchia, I.; Nash, T.; Naticchioni, L.; Nayak, R. K.; Necula, V.; Nedkova, K.; Nelemans, G.; Neri, I.; Neri, M.; Newton, G.; Nguyen, T.; Nielsen, A. B.; Nissanke, S.; Nitz, A. H.; Nocera, F.; Nolting, D.; Normandin, M. E. N.; Nuttall, L. K.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oppermann, P.; Oram, R.; O'Reilly, B.; Ortega, W.; O'Shaughnessy, R.; Osthelder, C.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Padilla, C.; Pai, A.; Pai, S.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Papa, M. A.; Paris, H.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patrick, Z.; Pedraza, M.; Pekowsky, L.; Pele, A.; Penn, S.; Perreca, A.; Phelps, M.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Poeld, J.; Poggiani, R.; Post, A.; Poteomkin, A.; Powell, J.; Prasad, J.; Predoi, V.; Premachandra, S.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qin, J.; Quetschke, V.; Quintero, E.; Quiroga, G.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Rácz, I.; Radkins, H.; Raffai, P.; Raja, S.; Rajalakshmi, G.; Rakhmanov, M.; Ramirez, K.; Rapagnani, P.; Raymond, V.; Razzano, M.; Re, V.; Reed, C. M.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Reula, O.; Ricci, F.; Riles, K.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V.; Romano, R.; Romanov, G.; Romie, J. H.; Ro´ska, D.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Saleem, M.; Salemi, F.; Sammut, L.; Sandberg, V.; Sanders, J. R.; Sannibale, V.; Santiago-Prieto, I.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Savage, R.; Sawadsky, A.; Scheuer, J.; Schilling, R.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schreiber, E.; Schuette, D.; Schutz, B. F.; Scott, J.; Scott, S. M.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Serna, G.; Sevigny, A.; Shaddock, D. A.; Shah, S.; Shahriar, M. S.; Shaltev, M.; Shao, Z.; Shapiro, B.; Shawhan, P.; Shoemaker, D. H.; Sidery, T. L.; Siellez, K.; Siemens, X.; Sigg, D.; Silva, A. D.; Simakov, D.; Singer, A.; Singer, L.; Singh, R.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, J. R.; Smith, M. R.; Smith, R. J. E.; Smith-Lefebvre, N. D.; Son, E. J.; Sorazu, B.; Souradeep, T.; Staley, A.; Stebbins, J.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Steplewski, S.; Stevenson, S.; Stone, R.; Strain, K. A.; Straniero, N.; Strigin, S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sutton, P. J.; Swinkels, B.; Szczepanczyk, M.; Szeifert, G.; Tacca, M.; Talukder, D.; Tanner, D. B.; Tápai, M.; Tarabrin, S. P.; Taracchini, A.; Taylor, R.; Tellez, G.; Theeg, T.; Thirugnanasambandam, M. P.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, V.; Tomlinson, C.; Tonelli, M.; Torres, C. V.; Torrie, C. I.; Travasso, F.; Traylor, G.; Tse, M.; Tshilumba, D.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Vajente, G.; Valdes, G.; Vallisneri, M.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; van den Broeck, C.; van der Sluys, M. V.; van Heijningen, J.; van Veggel, A. A.; Vass, S.; Vasúth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Viceré, A.; Vincent-Finley, R.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; Wade, L.; Wade, M.; Walker, M.; Wallace, L.; Walsh, S.; Wang, H.; Wang, M.; Wang, X.; Ward, R. L.; Warner, J.; Was, M.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Wessels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; White, D. J.; Whiting, B. F.; Wilkinson, C.; Williams, L.; Williams, R.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Worden, J.; Xie, S.; Yablon, J.; Yakushin, I.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yang, Q.; Yvert, M.; Zadrożny, A.; Zanolin, M.; Zendri, J.-P.; Zhang, Fan; Zhang, L.; Zhang, M.; Zhang, Y.; Zhao, C.; Zhou, M.; Zhu, X. J.; Zucker, M. E.; Zuraw, S.; Zweizig, J.

    2015-11-01

    We describe directed searches for continuous gravitational waves (GWs) in data from the sixth Laser Interferometer Gravitational-wave Observatory (LIGO) science data run. The targets were nine young supernova remnants not associated with pulsars; eight of the remnants are associated with non-pulsing suspected neutron stars. One target's parameters are uncertain enough to warrant two searches, for a total of 10. Each search covered a broad band of frequencies and first and second frequency derivatives for a fixed sky direction. The searches coherently integrated data from the two LIGO interferometers over time spans from 5.3-25.3 days using the matched-filtering {F}-statistic. We found no evidence of GW signals. We set 95% confidence upper limits as strong (low) as 4 × 10-25 on intrinsic strain, 2 × 10-7 on fiducial ellipticity, and 4 × 10-5 on r-mode amplitude. These beat the indirect limits from energy conservation and are within the range of theoretical predictions for neutron-star ellipticities and r-mode amplitudes.

  10. The NuSTAR Program for Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Grefenstette, Brian; An, H.; Boggs, S. E.; Christensen, F.; Craig, W. W.; Freyer, C.; Hailey, C. J.; Harrison, F.; Humensky, B.; Jakobsen, S.; Kaspi, V.; Kitaguchi, T.; Lopez, L. A.; Madsen, K.; Miyasaka, H.; Mori, K.; Nynka, M.; Pivovaroff, M.; Reynolds, S. P.; Stern, D.; Westergaard, N. J.; Wik, D. R.; Zhang, W.; Zoglauer, A.; NuSTAR Team

    2013-01-01

    The Nuclear Spectroscopic Telescope Array (NuSTAR), successfully launched in June 2012, is the first telescope to bring the the hard X-ray (3 to 79 keV) sky into focus. One of NuSTAR's prime science goals is to study the morphology of the previously unresolved hard X-ray emission from supernova remnants (SNRs). Spatial and spectral characterization of the hard X-ray synchrotron emission is essential to understanding the physics of particle acceleration in SNR and has implications for origin of galactic cosmic rays. Young (< 1 kyr) remnants may also show emission from decay products of Ti-44, which has great importance in understanding supernova explosion mechanisms. In this poster we present NuSTAR plans for observing SNRs as well as early results from SNRs observed in the first six months since launch, including preliminary results for Cassiopeia A. Discussions of Pulsar Wind Nebulae (PWNe) and G21.5-0.9 are presented in a companion posters by K. Madsen and M. Nynka, respectively.

  11. Planck intermediate results. XXXI. Microwave survey of Galactic supernova remnants

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Arnaud, M.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Battaner, E.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bobin, J.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Brogan, C. L.; Burigana, C.; Cardoso, J.-F.; Catalano, A.; Chamballu, A.; Chiang, H. C.; Christensen, P. R.; Colombi, S.; Colombo, L. P. L.; Crill, B. P.; Curto, A.; Cuttaia, F.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Désert, F.-X.; Dickinson, C.; Diego, J. M.; Donzelli, S.; Doré, O.; Dupac, X.; Enßlin, T. A.; Eriksen, H. K.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Galeotta, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gregorio, A.; Gruppuso, A.; Hansen, F. K.; Harrison, D. L.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hobson, M.; Holmes, W. A.; Huffenberger, K. M.; Jaffe, A. H.; Jaffe, T. R.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lawrence, C. R.; Leonardi, R.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Maino, D.; Maris, M.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; Mazzotta, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Noviello, F.; Novikov, D.; Novikov, I.; Oppermann, N.; Oxborrow, C. A.; Pagano, L.; Pajot, F.; Paladini, R.; Pasian, F.; Peel, M.; Perdereau, O.; Perrotta, F.; Piacentini, F.; Piat, M.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Popa, L.; Pratt, G. W.; Puget, J.-L.; Rachen, J. P.; Reach, W. T.; Reich, W.; Reinecke, M.; Remazeilles, M.; Renault, C.; Rho, J.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rusholme, B.; Sandri, M.; Savini, G.; Scott, D.; Stolyarov, V.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L. A.; Yvon, D.; Zacchei, A.; Zonca, A.

    2016-02-01

    The all-sky Planck survey in 9 frequency bands was used to search for emission from all 274 known Galactic supernova remnants. Of these, 16 were detected in at least two Planck frequencies. The radio-through-microwave spectral energy distributions were compiled to determine the mechanism for microwave emission. In only one case, IC 443, is there high-frequency emission clearly from dust associated with the supernova remnant. In all cases, the low-frequency emission is from synchrotron radiation. As predicted for a population of relativistic particles with energy distribution that extends continuously to high energies, a single power law is evident for many sources, including the Crab and PKS 1209-51/52. A decrease in flux density relative to the extrapolation of radio emission is evident in several sources. Their spectral energy distributions can be approximated as broken power laws, Sν ∝ ν-α, with the spectral index, α, increasing by 0.5-1 above a break frequency in the range 10-60 GHz. The break could be due to synchrotron losses.

  12. Model images of radio halos around supernova remnants

    NASA Technical Reports Server (NTRS)

    Reynolds, Stephen P.

    1994-01-01

    I present model calculations of profiles and two-dimensional images of the radio synchrotron emission of young supernova remnants, concentrating on observable effects of relativistic eletrons diffusing upstream of the shock wave. If the preshock electron scattering mean free path is sufficiently long, observable synchrotron halos outside the bulk of the radio emission can potentially result; their absence can constrain the mean free path from above. If scattering is primarily due, as expected, to Alfven waves with amplitude detla(B), the halo is expected to extend a distance of order r(sub g)c(delta(B)/B)(exp 2)/v(sub s) beyond the shock, where r(sub g) is the gyroradius of the electrons emitting at the observed frequency, B is the upstream magnetic field strength, v(sub s) is the shock velocity, and the amplitude delta(B) refers to wave with wavelength comparable to r(sub g), of order 10(exp 13) cm for typical supernova-remnant parameters. However, the detailed geometry of the halo varies with the assumptions about particle acceleration in the shock wave. I present an atlas of model profiles and images as a function of preshock diffusion length, of aspect angle between the magnetic field and the line of sight, and of other relevant parameters.

  13. Tycho's Remnant Provides Shocking Evidence for Cosmic Rays

    NASA Astrophysics Data System (ADS)

    2005-09-01

    Astronomers have found compelling evidence that a supernova shock wave has produced a large amount of cosmic rays, particles of mysterious origin that constantly bombard the Earth. This discovery, made with NASA's Chandra X-ray Observatory, supports theoretical arguments that shock waves from stellar explosions may be a primary source of cosmic rays. This finding is important for understanding the origin of cosmic rays, which are atomic nuclei that strike the Earth's atmosphere with very high energies. Scientists believe that some are produced by flares on the Sun, and others by similar events on other stars, or pulsars or black hole accretion disks. But, one of the prime suspects has been supernova shock waves. Now, a team of astronomers has used Chandra observations of Tycho's supernova remnant to strengthen the case for this explanation. "With only a single object involved we can't state with confidence that supernova shock waves are the primary source of cosmic rays," said John P. Hughes of Rutgers University in Piscataway, New Jersey, and coauthor of a report to be published in an upcoming issue of The Astrophysical Journal. "What we have done is present solid evidence that the shock wave in at least one supernova remnant has accelerated nuclei to cosmic ray energies." In the year 1572, the Danish astronomer Tycho Brahe observed and studied the sudden appearance of a bright "new star" in the constellation Cassiopeia. Now known as Tycho's supernova remnant, the event created a sensation in Tycho's time because it exploded the myth that stars never change. Four centuries later, the Chandra results on Tycho's remnant show that some modern ideas of the aftermath of supernova explosions may have to be revised. The report by Hughes and colleagues demonstrates that the shock wave produced by the explosive disruption of the star behaves in a way that cannot be explained by the standard theory. The supernova debris is observed to expand at a speed of about six million

  14. Future GLAST Observations of Supernova Remnants And Pulsar Wind Nebulae

    SciTech Connect

    Funk, S.; /KIPAC, Menlo Park

    2007-09-26

    Shell-type Supernova remnants (SNRs) have long been known to harbour a population of ultra-relativistic particles, accelerated in the Supernova shock wave by the mechanism of diffusive shock acceleration. Experimental evidence for the existence of electrons up to energies of 100 TeV was first provided by the detection of hard X-ray synchrotron emission as e.g. in the shell of the young SNR SN1006. Furthermore using theoretical arguments shell-type Supernova remnants have long been considered as the main accelerator of protons - Cosmic rays - in the Galaxy; definite proof of this process is however still missing. Pulsar Wind Nebulae (PWN) - diffuse structures surrounding young pulsars - are another class of objects known to be a site of particle acceleration in the Galaxy, again through the detection of hard synchrotron X-rays such as in the Crab Nebula. Gamma-rays above 100 MeV provide a direct access to acceleration processes. The GLAST Large Area telescope (LAT) will be operating in the energy range between 30 MeV and 300 GeV and will provide excellent sensitivity, angular and energy resolution in a previously rather poorly explored energy band. We will describe prospects for the investigation of these Galactic particle accelerators with GLAST.

  15. Destruction of Interstellar Dust in Evolving Supernova Remnant Shock Waves

    NASA Technical Reports Server (NTRS)

    Slavin, Jonathan D.; Dwek, Eli; Jones, Anthony P.

    2015-01-01

    Supernova generated shock waves are responsible for most of the destruction of dust grains in the interstellar medium (ISM). Calculations of the dust destruction timescale have so far been carried out using plane parallel steady shocks, however that approximation breaks down when the destruction timescale becomes longer than that for the evolution of the supernova remnant (SNR) shock. In this paper we present new calculations of grain destruction in evolving, radiative SNRs. To facilitate comparison with the previous study by Jones et al. (1996), we adopt the same dust properties as in that paper. We find that the efficiencies of grain destruction are most divergent from those for a steady shock when the thermal history of a shocked gas parcel in the SNR differs significantly from that behind a steady shock. This occurs in shocks with velocities 200 km s(exp -1) for which the remnant is just beginning to go radiative. Assuming SNRs evolve in a warm phase dominated ISM, we find dust destruction timescales are increased by a factor of approximately 2 compared to those of Jones et al. (1996), who assumed a hot gas dominated ISM. Recent estimates of supernova rates and ISM mass lead to another factor of approximately 3 increase in the destruction timescales, resulting in a silicate grain destruction timescale of approximately 2-3 Gyr. These increases, while not able resolve the problem of the discrepant timescales for silicate grain destruction and creation, are an important step towards understanding the origin, and evolution of dust in the ISM.

  16. The X-ray surface brightness of Kepler's supernova remnant

    NASA Technical Reports Server (NTRS)

    White, R. L.; Long, K. S.

    1983-01-01

    The first X-ray images of Kepler's supernova remnant (SN Ophiuchi 1604) are presented, and consequences for SNR models are discussed. Observations made with the Einstein Observatory Imaging Proportional Counter and High Resolution Imager show the remnant to be circular, with a strong shell brighter in the north than in the south. A flux of 1.2 x 10 to the -10th ergs/sq cm per sec was measured in the 0.15-4.5 keV region, which corresponds to an X-ray luminosity of 1.0 x 10 to the 36th ergs/sec at a distance of 5 kpc and an interstellar medium density of 2.8 x 10 to the 21st/sq cm. The X-ray observations do not allow the determination of whether the SNR is in the adiabatic or free expansion phase, but in either case it is shown that the mean ISM density must be greater than about 0.1/cu cm. In addition, the density of the X-ray emitting gas must be high, and its electron temperature must be fairly low. The high ISM densities derived for Kepler's SNR and other SNRs thus suggest an atypical ISM, possibly influenced by mass lost from the pre-supernova star.

  17. Triglyceride-Rich Lipoproteins and Remnants: Targets for Therapy?

    PubMed

    Dallinga-Thie, Geesje M; Kroon, Jeffrey; Borén, Jan; Chapman, M John

    2016-07-01

    It is now evident that elevated circulating levels of triglycerides in the non-fasting state, a marker for triglyceride (TG)-rich remnant particles, are associated with increased risk of premature cardiovascular disease (CVD). Recent findings from basic and clinical studies have begun to elucidate the mechanisms that contribute to the atherogenicity of these apoB-containing particles. Here, we review current knowledge of the formation, intravascular remodelling and catabolism of TG-rich lipoproteins and highlight (i) the pivotal players involved in this process, including lipoprotein lipase, glycosylphosphatidylinositol HDL binding protein 1 (GPIHBP1), apolipoprotein (apo) C-II, apoC-III, angiopoietin-like protein (ANGPTL) 3, 4 and 8, apoA-V and cholesteryl ester transfer protein; (ii) key determinants of triglyceride (TG) levels and notably rates of production of very-low-density lipoprotein 1 (VLDL1) particles; and (iii) the mechanisms which underlie the atherogenicity of remnant particles. Finally, we emphasise the polygenic nature of moderate hypertriglyceridemia and briefly discuss modalities for its clinical management. Several new therapeutic strategies to attenuate hypertriglyceridemia have appeared recently, among which those targeted to apoC-III appear to hold considerable promise. PMID:27216847

  18. Searches for Continuous Gravitational Waves from Nine Young Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Aasi, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Ain, A.; Ajith, P.; Alemic, A.; Allen, B.; Allocca, A.; Amariutei, D.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C.; Areeda, J. S.; Ast, S.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Aylott, B. E.; Babak, S.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barbet, M.; Barclay, S.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Bartlett, J.; Barton, M. A.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Bauer, Th. S.; Baune, C.; Bavigadda, V.; Behnke, B.; Bejger, M.; Belczynski, C.; Bell, A. S.; Bell, C.; Benacquista, M.; Bergman, J.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biscans, S.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackburn, L.; Blair, C. D.; Blair, D.; Bloemen, S.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, G.; Bojtos, P.; Bond, C.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, Sukanta; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Buchman, S.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Cadonati, L.; Cagnoli, G.; Calderón Bustillo, J.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Carbognani, F.; Caride, S.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, S.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C.; Colombini, M.; Cominsky, L.; Constancio, M., Jr.; Conte, A.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Coulon, J.-P.; Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Cutler, C.; Dahl, K.; Dal Canton, T.; Damjanic, M.; Danilishin, S. L.; D’Antonio, S.; Danzmann, K.; Dartez, L.; Dattilo, V.; Dave, I.; Daveloza, H.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dereli, H.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; Díaz, M.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Virgilio, A.; Dojcinoski, G.; Dolique, V.; Dominguez, E.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S.; Eberle, T.; Edo, T.; Edwards, M.; Edwards, M.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Essick, R.; Etzel, T.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Fan, X.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Feldbaum, D.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fisher, R. P.; Flaminio, R.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fuentes-Tapia, S.; Fulda, P.; Fyffe, M.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S.; Garufi, F.; Gatto, A.; Gehrels, N.; Gemme, G.; Gendre, B.; Genin, E.; Gennai, A.; Gergely, L. Á.; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gleason, J.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gordon, N.; Gorodetsky, M. L.; Gossan, S.; Gossler, S.; Gouaty, R.; Gräf, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guido, C. J.; Guo, X.; Gushwa, K.; Gustafson, E. K.; Gustafson, R.; Hacker, J.; Hall, E. D.; Hammond, G.; Hanke, M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Heidmann, A.; Heintze, M.; Heinzel, G.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Hofman, D.; Hollitt, S. E.; Holt, K.; Hopkins, P.; Hosken, D. J.; Hough, J.; Houston, E.; Howell, E. J.; Hu, Y. M.

    2015-11-01

    We describe directed searches for continuous gravitational waves (GWs) in data from the sixth Laser Interferometer Gravitational-wave Observatory (LIGO) science data run. The targets were nine young supernova remnants not associated with pulsars; eight of the remnants are associated with non-pulsing suspected neutron stars. One target's parameters are uncertain enough to warrant two searches, for a total of 10. Each search covered a broad band of frequencies and first and second frequency derivatives for a fixed sky direction. The searches coherently integrated data from the two LIGO interferometers over time spans from 5.3–25.3 days using the matched-filtering {F}-statistic. We found no evidence of GW signals. We set 95% confidence upper limits as strong (low) as 4 × 10‑25 on intrinsic strain, 2 × 10‑7 on fiducial ellipticity, and 4 × 10‑5 on r-mode amplitude. These beat the indirect limits from energy conservation and are within the range of theoretical predictions for neutron-star ellipticities and r-mode amplitudes.

  19. THE ROLE OF DIFFUSIVE SHOCK ACCELERATION ON NONEQUILIBRIUM IONIZATION IN SUPERNOVA REMNANT SHOCKS. II. EMITTED SPECTRA

    SciTech Connect

    Patnaude, Daniel J.; Slane, Patrick; Raymond, John C.; Ellison, Donald C.

    2010-12-20

    We present a grid of nonequilibrium ionization models for the X-ray spectra from supernova remnants undergoing efficient diffusive shock acceleration. The calculation follows the hydrodynamics of the blast wave as well as the time-dependent ionization of the plasma behind the shock. The ionization state is passed to a plasma emissivity code to compute the thermal X-ray emission, which is combined with the emission from nonthermal synchrotron emission to produce a self-consistent model for the thermal and nonthermal emission from cosmic-ray dominated shocks. We show how plasma diagnostics such as the G'-ratio of He-like ions, defined as the ratio of the sum of the intercombination, forbidden, and satellite lines to the resonance line, can vary with acceleration efficiency, and discuss how the thermal X-ray emission, when the time-dependent ionization is not calculated self-consistently with the hydrodynamics, can differ from the thermal X-ray emission from models which do account for the hydrodynamics. Finally, we compare the thermal X-ray emission from models which show moderate acceleration ({approx}35%) to the thermal X-ray emission from test-particle models.

  20. SPECTRA OF COSMIC-RAY PROTONS AND HELIUM PRODUCED IN SUPERNOVA REMNANTS

    SciTech Connect

    Ptuskin, Vladimir; Zirakashvili, Vladimir; Seo, Eun-Suk

    2013-01-20

    Data obtained in the Advanced Thin Ionization Calorimeter (ATIC-2), Cosmic Ray Energetics and Mass (CREAM), and Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) experiments suggest that the elemental interstellar spectra of cosmic rays below the knee at a few times 10{sup 6} GeV are not simple power laws, but that they experience hardening at a magnetic rigidity of about 240 GV. Another essential feature is the difference between proton and helium energy spectra, such that the He/p ratio increases by more than 50% in the energy range from 10{sup 2} to 10{sup 4} GV. We consider the concavity of the particle spectrum resulting from the nonlinear nature of diffusive shock acceleration in supernova remnants (SNRs) as a possible reason for the observed spectrum hardening. The increase of the helium-to-proton ratio with energy can be interpreted as a consequence of cosmic-ray acceleration by forward and reverse shocks in SNRs. The contribution of particles accelerated by reverse shocks makes the concavity of the produced overall cosmic-ray spectrum more pronounced. The spectra of protons and helium nuclei accelerated in SNRs and released into the interstellar medium are calculated. The derived steady-state interstellar spectra are in reasonably good agreement with observations.

  1. Class I Methanol (CH3OH) Maser Conditions near Supernova Remnants

    NASA Astrophysics Data System (ADS)

    McEwen, Bridget C.; Pihlström, Ylva M.; Sjouwerman, Loránt O.

    2014-10-01

    We present results from calculations of the physical conditions necessary for the occurrence of 36.169 (4-1-30 E), 44.070 (70-61 A +), 84.521 (5-1-40 E), and 95.169 (80-71 A +) GHz methanol (CH3OH) maser emission lines near supernova remnants (SNRs), using the MOLPOP-CEP program. The calculations show that given a sufficient methanol abundance, methanol maser emission arises over a wide range of densities and temperatures, with optimal conditions at n ~ 104-106 cm-3 and T > 60 K. The 36 GHz and 44 GHz transitions display more significant maser optical depths compared to the 84 GHz and 95 GHz transitions over the majority of physical conditions. It is also shown that line ratios are an important and applicable probe of the gas conditions. The line ratio changes are largely a result of the E-type transitions becoming quenched faster at increasing densities. The modeling results are discussed using recent observations of CH3OH and hydroxyl (OH) masers near the SNRs G1.4-0.1, W28, and Sgr A East.

  2. DUST DESTRUCTION IN A NON-RADIATIVE SHOCK IN THE CYGNUS LOOP SUPERNOVA REMNANT

    SciTech Connect

    Sankrit, Ravi; Gaetz, Terrance J.; Raymond, John C.; Blair, William P.; Ghavamian, Parviz; Long, Knox S.

    2010-04-01

    We present 24 {mu}m and 70 {mu}m images of a non-radiative shock in the Cygnus Loop supernova remnant, obtained with the Multiband Imaging Photometer for Spitzer on board the Spitzer Space Telescope. The post-shock region is resolved in these images. The ratio of the 70 {mu}m to the 24 {mu}m flux rises from about 14 at a distance 0.'1 behind the shock front to about 22 in a zone 0.'75 further downstream, as grains are destroyed in the hot plasma. Models of dust emission and destruction using post-shock electron temperatures between 0.15 keV and 0.30 keV and post-shock densities, n{sub H}{approx} 2.0 cm{sup -3}, predict flux ratios that match the observations. Non-thermal sputtering (i.e., sputtering due to bulk motion of the grains relative to the gas) contributes significantly to the dust destruction under these shock conditions. From the model calculations, we infer that about 35% by mass of the grains are destroyed over a 0.14 pc region behind the shock front.

  3. The X-Ray Spectrum of the Supernova Remnant 1E 0102-72.3

    NASA Technical Reports Server (NTRS)

    Rasmussen, Andrew P.; Behar, Ehud; Kahn, Steven M.; denHerder, Jan Willem; vanderHeyden, Kurt

    1997-01-01

    In this letter we present the soft X-ray (5-35A) spectrum of the supernova remnant (SNR) IE 0102-72.3 in the Small Magellanic Cloud, acquired by the reflection grating spectrometer (RGS) aboard ESA's XMM-Newton Observatory. This extended-source X-ray spectrum of unprecedented spectral resolution (lambda/Delta(lambda) approx. 300) permits, for the first time, unabiguous identification and measurement of isolated emission lines and line complexes alike. The diagnostic power of performing spectroscopy using groups of emission lines from single ions is exemplified. In particular, the bright Lyman and helium series lines for light elements (C VI, O VII, O VIII, Ne IX, Ne X and possibly Mg XI & Mg XII) show peculiar ratios, where the values [1s - np] / [1s - (n + l)p] are systematically weaker than expected for electron impact excitation. These measured ratios resemble signatures of recombining or charge exchanging plasmas. We argue that charge exchange, given its large cross section and evidence for inhomogeneous media within the SNR, is a likely mechanism for the observed emission. Also. the well known temperature diagnostics G(T(sub e)) = (i + f)/r of helium- like triplets (O VII & Ne IX) indicate high temperatures, well above the maximum emission temperature T(sub m) for each ion, and consistent with a purely ionizing plasma. The density diagnostics R(n(sub e)) = f / i meanwhile, are consistent with the low density limit, as expected.

  4. Class I methanol (CH{sub 3}OH) maser conditions near supernova remnants

    SciTech Connect

    McEwen, Bridget C.; Pihlström, Ylva M.; Sjouwerman, Loránt O.

    2014-10-01

    We present results from calculations of the physical conditions necessary for the occurrence of 36.169 (4{sub –1}-3{sub 0} E), 44.070 (7{sub 0}-6{sub 1} A {sup +}), 84.521 (5{sub –1}-4{sub 0} E), and 95.169 (8{sub 0}-7{sub 1} A {sup +}) GHz methanol (CH{sub 3}OH) maser emission lines near supernova remnants (SNRs), using the MOLPOP-CEP program. The calculations show that given a sufficient methanol abundance, methanol maser emission arises over a wide range of densities and temperatures, with optimal conditions at n ∼ 10{sup 4}-10{sup 6} cm{sup –3} and T > 60 K. The 36 GHz and 44 GHz transitions display more significant maser optical depths compared to the 84 GHz and 95 GHz transitions over the majority of physical conditions. It is also shown that line ratios are an important and applicable probe of the gas conditions. The line ratio changes are largely a result of the E-type transitions becoming quenched faster at increasing densities. The modeling results are discussed using recent observations of CH{sub 3}OH and hydroxyl (OH) masers near the SNRs G1.4–0.1, W28, and Sgr A East.

  5. EFFECTS OF NEUTRAL HYDROGEN ON COSMIC-RAY PRECURSORS IN SUPERNOVA REMNANT SHOCK WAVES

    SciTech Connect

    Raymond, John C.; Vink, J.; Helder, E. A.; De Laat, A.

    2011-04-10

    Many fast supernova remnant shocks show spectra dominated by Balmer lines. The H{alpha} profiles have a narrow component explained by direct excitations and a thermally Doppler broadened component due to atoms that undergo charge exchange in the post-shock region. However, the standard model does not take into account the cosmic-ray shock precursor, which compresses and accelerates plasma ahead of the shock. In strong precursors with sufficiently high densities, the processes of charge exchange, excitation, and ionization will affect the widths of both narrow and broad line components. Moreover, the difference in velocity between the neutrals and the precursor plasma gives rise to frictional heating due to charge exchange and ionization in the precursor. In extreme cases, all neutrals can be ionized by the precursor. In this Letter we compute the ion and electron heating for a wide range of shock parameters, along with the velocity distribution of the neutrals that reach the shock. Our calculations predict very large narrow component widths for some shocks with efficient acceleration, along with changes in the broad-to-narrow intensity ratio used as a diagnostic for the electron-ion temperature ratio. Balmer lines may therefore provide a unique diagnostic of precursor properties. We show that heating by neutrals in the precursor can account for the observed H{alpha} narrow component widths and that the acceleration efficiency is modest in most Balmer line shocks observed thus far.

  6. Detailed Infrared views of the shock-cloud interactions in the supernova remnant HB 21

    NASA Astrophysics Data System (ADS)

    Shinn, Jong-Ho; Koo, Bon-Chul; Burton, Michael; Lee, Ho-Gyu; Moon, Dae-Sik

    HB 21 (G89.0+4.7) is a nearby (˜ 1 kpc), large (120 ×90 ), middle-aged (˜ 7000 yr) supernova remnant, whose interaction with nearby molecular clouds is known. We observed two specific regions (˜ 10 × 10 ), where the shock-cloud interactions are thought to be under way, with the Japanese infrared satellite AKARI. InfraRed Camera (IRC) onboard AKARI obtained several images at nearand mid-infrared wavebands (3, 4, 7, 11, 15, and 24 µm). Those images show diffuse filamentary features, together with some clumpy features, mainly in the 7, 11, and 15 µm bands. These features are generally consistent with those seen in H2 v = 1 → 0 S(1) 2.122 µm image. We analyzed the color ratios of the features in the IRC images using theoretically calculated emission lines from shocked H2 gas in local thermodynamic equilibrium and statistical equilibrium. The results show that the observed color-ratios are well described by power-law mixtures of H2 gas temperature, and that the degree of mixture varies from region to region (power-law index 4.0). Based on observations with AKARI, a JAXA project with the participation of ESA.

  7. Magnetic amplification and electron acceleration in supernova remnant shocks

    NASA Astrophysics Data System (ADS)

    Riquelme, Mario A.

    Supernova remnant (SNR) shocks are the main candidates for the acceleration of galactic cosmic rays (CRs). This assessment is supported by the success of the diffusive shock acceleration (DSA) mechanism to reproduce power-law energy distributions close to the ones of CRs. However, and despite extensive efforts, at present the connection between galactic CRs and SNR shocks has not been fully demonstrated, neither from theoretical nor from observational point of view. The situation is different for the case of accelerated electrons. X-ray observations of SNRs show the existence of thin non-thermal rims, which are interpreted as synchrotron emission by TeV electrons accelerated in SNR shocks. Also, the rapid variability and thinness of the rims (which depend on the synchrotron cooling time of the electrons) have allowed to estimate the strength of the magnetic field, suggesting amplitudes ˜100 times larger than the typical ˜3muG field in the ISM. Unveiling the mechanisms producing these electron acceleration and magnetic amplification are essential steps to understanding the physics of particle acceleration in SNRs, and are the subjects of this dissertation. In the first part of this thesis (chapters 2 and 3), we explore the idea, first proposed by Bell (2004), of the magnetic field amplification being driven by the CRs themselves. In chapter 2 we use particle-in-cell (PIC) plasma simulations to study the cosmic ray current-driven instability (CRCD), which in the last years has been the main candidate to explain magnetic amplification in SNRs. This instability consists of growing Alfvenic waves driven by the electric current of CRs streaming along the magnetic field in the upstream medium of the shocks. We confirm the existence of this instability in the kinetic regime, and determine its saturation mechanism. We find that the field growth saturates due to the deflection of the CR trajectories in the amplified field, and that, under optimistic assumptions, a maximum

  8. Supernova remnant masers: Shock interactions with molecular clouds

    NASA Astrophysics Data System (ADS)

    Hewitt, John William

    Maser emission from the 1720-MHz transition of hydroxyl(OH) has identified shock interactions in 10% of all supernova remnants(SNRs). Such maser-emitting SNRs are also bright in molecular line emission. Though somewhat rare, SNRs interacting with dense molecular clouds are an important class in which to study cosmic ray acceleration, SNR evolution, and effects on the energetics and chemistry of the interstellar medium. To study molecular shocks via a multiwavelength approach, the VLA, GBT, Spitzer Space Telescope have been used in the following ways: (i) With the GBT widespread OH(1720 MHz) emission and absorption in other OH lines is observed across the interaction site. Observations of all four ground-state transitions at 1720, 1667/5 and 1612 MHz allows us to model OH excitation, yielding the temperature, density and OH abundance in the post-shock gas. Maser emission is found to have a higher flux density with the GBT than with high-resolution VLA observations for 10 of 15 observed remnants, suggesting maser emission is present on large spatial scales. (ii) Sensitive VLA observations of select SNRs (W44, IC 443, Kes 69, 3C 391, G357.7+0.3) reveal the nature of enhanced 1720 MHz emission. Numerous weak compact masers as well as diffuse extended emission are detected tracing the shock-front. Zeeman splitting of masers permits the post-shock magnetic field strength and the line of sight field direction to be directly measured. (iii) Rotational lines of molecular hydrogen are detected at the position of several masers with Spitzer IRS spectroscopy between 5 and 35 mm. Excitation of the hydrogen lines requires the passage of a C-type shock through dense molecular gas, in agreement with the conditions derived from OH excitation. The presence of bright ionic lines requires multiple shocks present at the interaction site. (iv) A new survey for SNR-masers has identified four new interacting SNRs within 10 degrees of the Galactic Center. Maser-emitting SNRs are found to

  9. NUMERICAL STUDY OF THE VISHNIAC INSTABILITY IN SUPERNOVA REMNANTS

    SciTech Connect

    Michaut, C.; Cavet, C.; Bouquet, S. E.; Roy, F.; Nguyen, H. C.

    2012-11-10

    The Vishniac instability is thought to explain the complex structure of radiative supernova remnants in their Pressure-Driven Thin Shell (PDTS) phase after a blast wave (BW) has propagated from a central explosion. In this paper, the propagation of the BW and the evolution of the PDTS stage are studied numerically with the two-dimensional (2D) code HYDRO-MUSCL for a finite-thickness shell expanding in the interstellar medium (ISM). Special attention is paid to the adiabatic index, {gamma}, and three distinct values are taken for the cavity ({gamma}{sub 1}), the shell ({gamma}{sub 2}), and the ISM ({gamma}{sub 3}) with the condition {gamma}{sub 2} < {gamma}{sub 1}, {gamma}{sub 3}. This low value of {gamma}{sub 2} accounts for the high density in the shell achieved by a strong radiative cooling. Once the spherical background flow is obtained, the evolution of a 2D-axisymmetric perturbation is computed from the linear to the nonlinear regime. The overstable mechanism, previously demonstrated theoretically by E. T. Vishniac in 1983, is recovered numerically in the linear stage and is expected to produce and enhance anisotropies and clumps on the shock front, leading to the disruption of the shell in the nonlinear phase. The period of the increasing oscillations and the growth rate of the instability are derived from several points of view (the position of the perturbed shock front, mass fluxes along the shell, and density maps), and the most unstable mode differing from the value given by Vishniac is computed. In addition, the influence of several parameters (the Mach number, amplitude and wavelength of the perturbation, and adiabatic index) is examined and for wavelengths that are large enough compared to the shell thickness, the same conclusion arises: in the late stage of the evolution of the radiative supernova remnant, the instability is dampened and the angular initial deformation of the shock front is smoothed while the mass density becomes uniform with the

  10. Unilateral hypoplastic kidney and ureter associated with diverse mesonephric remnant hyperplasia

    PubMed Central

    Xiao, Guang-Qian; Jerome, Jean-Gilles; Wu, Guan

    2015-01-01

    Mesonephric remnants have been rarely reported in the genitourinary system and sometimes impose a diagnostic challenge both clinically and pathologically. We reported a case of mesonephric remnant hyperplasia with mixed acinar/tubular and epididymis/vas deferens-like morphologies occurring in the renal parenchyma of a unilateral hypoplastic kidney, which has not been previously described. PMID:26309900

  11. Early-type dwarf galaxies with multicomponent stellar structure: Are they remnants of disc galaxies strongly transformed by their environment?

    NASA Astrophysics Data System (ADS)

    Aguerri, J. Alfonso L.

    2016-03-01

    Context. The surface brightness distribution of ~30-40% of the early-type dwarf galaxies with - 18 ≤ MB ≤ -15 in the Virgo and the Coma clusters is fitted by models that include two structural components (Sérsic + exponential) as for bright disc galaxies. Aims: The goal of the present study is to determine whether early-type dwarf galaxies with a two-component stellar structure in the Virgo and the Coma clusters are low-luminosity copies of bright disc galaxies or are the remnants of bright galaxies strongly transformed by cluster environmental effects. Methods: I analysed the location of bright disc galaxies and early-type dwarfs in the rb,e/h- n plane. The location in this plane of the two-component dwarf galaxies was compared with the remnants of tidally disrupted disc galaxies reported by numerical simulations. Results: Bright unbarred disc galaxies show a strong correlation in the rb,e/h-n plane. Galaxies with larger Sérsic shape parameters show a higher rb,e/h ratio. In contrast, two-component early-type dwarf galaxies do not follow the same correlation. A fraction (~55%) of them are located outside the locus defined in this plane by having 95% of bright disc galaxies. This distribution indicates that they are not a low-mass replica of bright disc galaxies. The different location in the rb,e/h- n plane of two-component early-type dwarfs and bright galaxies can be qualitatively explain whether the former are remnants of disc galaxies strongly transformed by tidal processes. Conclusions: The progenitors of ~20-25% of early-type dwarf galaxies with - 18 ≤ MB ≤ -15 in the Virgo and Coma clusters could be bright disc galaxies transformed by effects of the environment. These tidally transformed galaxies can be selected according to their location in the rb,e/h-n plane.

  12. An Expanded HST/WFC3 Survey of M83: Project Overview and Targeted Supernova Remnant Search

    NASA Astrophysics Data System (ADS)

    Blair, William P.; Chandar, Rupali; Dopita, Michael A.; Ghavamian, Parviz; Hammer, Derek; Kuntz, K. D.; Long, Knox S.; Soria, Roberto; Whitmore, Bradley C.; Winkler, P. Frank

    2014-06-01

    We present an optical/NIR imaging survey of the face-on spiral galaxy M83, using data from the Hubble Space Telescope Wide Field Camera 3 (WFC3). Seven fields are used to cover a large fraction of the inner disk, with observations in nine broadband and narrowband filters. In conjunction with a deep Chandra survey and other new radio and optical ground-based work, these data enable a broad range of science projects to be pursued. We provide an overview of the WFC3 data and processing and then delve into one topic, the population of young supernova remnants (SNRs). We used a search method targeted toward soft X-ray sources to identify 26 new SNRs. Many compact emission nebulae detected in [Fe II] 1.644 μm align with known remnants and this diagnostic has also been used to identify many new remnants, some of which are hard to find with optical images. We include 37 previously identified SNRs that the data reveal to be <0.''5 in angular size and thus are difficult to characterize from ground-based data. The emission line ratios seen in most of these objects are consistent with shocks in dense interstellar material rather than showing evidence of ejecta. We suggest that the overall high elemental abundances in combination with high interstellar medium pressures in M83 are responsible for this result. Future papers will expand on different aspects of the these data including a more comprehensive analysis of the overall SNR population. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  13. An expanded HST/WFC3 survey of M83: Project overview and targeted supernova remnant search

    SciTech Connect

    Blair, William P.; Kuntz, K. D.; Chandar, Rupali; Dopita, Michael A.; Ghavamian, Parviz; Hammer, Derek; Long, Knox S.; Whitmore, Bradley C.; Soria, Roberto; Frank Winkler, P. E-mail: kuntz@pha.jhu.edu E-mail: Michael.Dopita@anu.edu.au E-mail: long@stsci.edu E-mail: whitmore@stsci.edu E-mail: winkler@middlebury.edu

    2014-06-10

    We present an optical/NIR imaging survey of the face-on spiral galaxy M83, using data from the Hubble Space Telescope Wide Field Camera 3 (WFC3). Seven fields are used to cover a large fraction of the inner disk, with observations in nine broadband and narrowband filters. In conjunction with a deep Chandra survey and other new radio and optical ground-based work, these data enable a broad range of science projects to be pursued. We provide an overview of the WFC3 data and processing and then delve into one topic, the population of young supernova remnants (SNRs). We used a search method targeted toward soft X-ray sources to identify 26 new SNRs. Many compact emission nebulae detected in [Fe II] 1.644 μm align with known remnants and this diagnostic has also been used to identify many new remnants, some of which are hard to find with optical images. We include 37 previously identified SNRs that the data reveal to be <0.''5 in angular size and thus are difficult to characterize from ground-based data. The emission line ratios seen in most of these objects are consistent with shocks in dense interstellar material rather than showing evidence of ejecta. We suggest that the overall high elemental abundances in combination with high interstellar medium pressures in M83 are responsible for this result. Future papers will expand on different aspects of the these data including a more comprehensive analysis of the overall SNR population.

  14. Radio observations of supernova remnants and the surrounding molecular gas

    NASA Astrophysics Data System (ADS)

    Dubner, G.

    Supernova Remnants (SNRs) are believed to be the main source of Galactic cosmic rays (CR). The strong SNR shocks provide ideal acceleration sites for particles of at least ˜ 1014 eV/nucleon. Radio continuum studies of SNRs carried out with good sensitivity and high angular resolution convey information about three main aspects of the SNRs: morphology, polarization and spectrum. Based on this information it is possible to localize sites of higher compression and particle acceleration as well as the orientation and degree of order of the magnetic fields, and in some cases even its intensity. All this information, when complemented with the study of the distribution and kinematics of the surrounding interstellar gas, results in a very useful dataset to investigate the role of SNRs as cosmic ray accelerators. In this presentation, I analyze the radio observations of SNRs and surrounding molecular clouds, showing the contribution of these studies to the understanding of the role of SNRs as factories of CRs.

  15. Type Ia supernova remnants: shaping by iron bullets

    NASA Astrophysics Data System (ADS)

    Tsebrenko, Danny; Soker, Noam

    2015-10-01

    Using 2D numerical hydrodynamical simulations of Type Ia supernova remnants (SNR Ia) we show that iron clumps few times denser than the rest of the SN ejecta might form protrusions in an otherwise spherical SNR. Such protrusions exist in some SNR Ia, e.g. SNR 1885 and Tycho. Iron clumps are expected to form in the deflagration to detonation explosion model. In SNR Ia where there are two opposite protrusions, termed `ears', such as Kepler's SNR and SNR G1.9+0.3, our scenario implies that the dense clumps, or iron bullets, were formed along an axis. Such a preferred axis can result from a rotating white dwarf progenitor. If our claim holds, this offers an important clue to the SN Ia explosion scenario.

  16. Grain destruction in a supernova remnant shock wave

    SciTech Connect

    Raymond, John C.; Gaetz, Terrance J.; Ghavamian, Parviz; Williams, Brian J.; Blair, William P.; Borkowski, Kazimierz J.; Sankrit, Ravi

    2013-12-01

    Dust grains are sputtered away in the hot gas behind shock fronts in supernova remnants (SNRs), gradually enriching the gas phase with refractory elements. We have measured emission in C IV λ1550 from C atoms sputtered from dust in the gas behind a non-radiative shock wave in the northern Cygnus Loop. Overall, the intensity observed behind the shock agrees approximately with predictions from model calculations that match the Spitzer 24 μm and the X-ray intensity profiles. Thus, these observations confirm the overall picture of dust destruction in SNR shocks and the sputtering rates used in models. However, there is a discrepancy in that the C IV intensity 10'' behind the shock is too high compared with the intensities at the shock and 25'' behind it. Variations in the density, hydrogen neutral fraction, and the dust properties over parsec scales in the pre-shock medium limit our ability to test dust destruction models in detail.

  17. Thrombin A-Chain: Activation Remnant or Allosteric Effector?

    PubMed Central

    Carter, Isis S. R.; Vanden Hoek, Amanda L.; Pryzdial, Edward L. G.; MacGillivray, Ross T. A.

    2010-01-01

    Although prothrombin is one of the most widely studied enzymes in biology, the role of the thrombin A-chain has been neglected in comparison to the other domains. This paper summarizes the current data on the prothrombin catalytic domain A-chain region and the subsequent thrombin A-chain. Attention is given to biochemical characterization of naturally occurring prothrombin A-chain mutations and alanine scanning mutants in this region. While originally considered to be simply an activation remnant with little physiologic function, the thrombin A-chain is now thought to play a role as an allosteric effector in enzymatic reactions and may also be a structural scaffold to stabilize the protease domain. PMID:22084659

  18. Historical Supernova Explosions in Our Galaxy and Their Remnants

    NASA Astrophysics Data System (ADS)

    Green, David A.

    Supernova explosions mark the end points of stellar evolution, releasing large amounts of material and energy into the interstellar medium. In our Galaxy the expected rate of supernovae is about 1 in every 50 years or so, although it is only the relatively nearby ones that are expected to be visible optically, due to obscuration. Over the last two thousand years or so there are historical records of nine Galactic supernovae. The majority of these records are from East Asia (i.e. China, Japan and Korea), although the most recent historical supernovae have European records, and there are a variety of Arabic records also available for some events. Here I review these records of the historical supernovae, and the modern observations of the supernova remnants that they have produced.

  19. The Likely Fermi Detection of the Supernova Remnant SN 1006

    NASA Astrophysics Data System (ADS)

    Xing, Yi; Wang, Zhongxiang; Zhang, Xiao; Chen, Yang

    2016-05-01

    We report the likely detection of γ-ray emission from the northeast shell region of the historical supernova remnant (SNR) SN 1006. Having analyzed seven years of Fermi Large Area Telescope Pass 8 data for the region of SN 1006, we found a GeV gamma-ray source detected with ∼ 4σ significance. Both the position and spectrum of the source match those of HESS J1504‑418, respectively, which is TeV emission from SN 1006. Considering the source as the GeV γ-ray counterpart to SN 1006, the broadband spectral energy distribution is found to be approximately consistent with the leptonic scenario that has been proposed for the TeV emission from the SNR. Our result has likely confirmed the previous study of the SNRs with TeV shell-like morphology: SN 1006 is one of them sharing very similar peak luminosity and spectral shape.

  20. NGC 2419-Another Remnant of Accretion by the Milky Way

    NASA Astrophysics Data System (ADS)

    Cohen, Judith G.; Kirby, Evan N.; Simon, Joshua D.; Geha, Marla

    2010-12-01

    We isolate a sample of 43 upper red giant branch stars in the extreme outer halo Galactic globular cluster (GC) NGC 2419 from two Keck/DEIMOS slitmasks. The probability that there is more than one contaminating halo field star in this sample is extremely low. Analysis of moderate-resolution spectra of these cluster members, as well as of our Keck/HIRES high-resolution spectra of a subsample of them, demonstrates that there is a small but real spread in Ca abundance of ~0.2 dex within this massive metal-poor GC. This provides additional support to earlier suggestions that NGC 2419 is the remnant of a dwarf galaxy accreted long ago by the Milky Way. Based in part on observations obtained at the W.M. Keck Observatory, which is operated jointly by the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration.

  1. Remnant group of local Lorentz transformations in f (T ) theories

    NASA Astrophysics Data System (ADS)

    Ferraro, Rafael; Fiorini, Franco

    2015-03-01

    It is shown that the extended teleparallel gravitational theories, known as f (T ) theories, inherit some on shell local Lorentz invariance associated with the tetrad field defining the spacetime structure. We discuss some enlightening examples, such as Minkowski spacetime and cosmological (Friedmann-Robertson-Walker and Bianchi type I) manifolds. In the first case, we show that the absence of gravity reveals itself as an incapability in the selection of a preferred parallelization at a local level, due to the fact that the infinitesimal local Lorentz subgroup acts as a symmetry group of the frame characterizing Minkowski spacetime. Finite transformations are also discussed in these examples and, contrary to the common lore on the subject, we conclude that the set of tetrads responsible for the parallelization of these manifolds is quite vast and that the remnant group of local Lorentz transformations includes one- and two-dimensional Abelian subgroups of the Lorentz group.

  2. Grain Destruction in a Supernova Remnant Shock Wave

    NASA Technical Reports Server (NTRS)

    Raymond, John C.; Ghavamian, Parviz; Williams, Brian J.; Blair, William P.; Borkowski, Kazimierz J.; Gaetz, Terrance J.; Sankrit, Ravi

    2014-01-01

    Dust grains are sputtered away in the hot gas behind shock fronts in supernova remnants, gradually enriching the gas phase with refractory elements. We have measured emission in C IV (lambda)1550 from C atoms sputtered from dust in the gas behind a non-radiative shock wave in the northern Cygnus Loop. Overall, the intensity observed behind the shock agrees approximately with predictions from model calculations that match the Spitzer 24 micron and the X-ray intensity profiles. Thus these observations confirm the overall picture of dust destruction in SNR shocks and the sputtering rates used in models. However, there is a discrepancy in that the CIV intensity 10'' behind the shock is too high compared to the intensities at the shock and 25'' behind it. Variations in the density, hydrogen neutral fraction and the dust properties over parsec scales in the pre- shock medium limit our ability to test dust destruction models in detail.

  3. New Candidates for Supernova Remnants in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Kavanagh, Patrick

    2013-10-01

    We propose observations of five new candidates for X-ray supernova remnants (SNRs) in the Large Magellanic Cloud (LMC), which were detected in ROSAT data and classified as SNR candidates based on their X-ray, radio, and optical properties. Five sources have already been observed (AO9 and AO12, Prop. IDs 65188 and 72044; AO11, VLP-LMC survey) and confirm the reliability of our candidate selection. The high sensitivity of XMM-Newton will allow us to detect SNRs that are X-ray faint due to their age or ambient medium, and complete the sample of known SNRs to lower fluxes. We will thus be able to perform statistical studies by, e.g., constructing a more complete X-ray luminosity function of SNRs in the LMC and will obtain information about typical abundances, densities, and initial supernova energies.

  4. SN1987A: The Birth of a Supernova Remnant

    NASA Technical Reports Server (NTRS)

    McCray, Richard

    2003-01-01

    This grant was intended to support the development of theoretical models needed to interpret and understand the observations by the Hubble Space Telescope and the Chandra X-ray telescope of the rapidly developing remnant of Supernova 1987A. In addition, we carried out a few investigations of related topics. The project was spectacularly successful. The models that we developed provide the definitive framework for predicting and interpreting this phenomenon. Following is a list of publications based on our work. Some of these papers include results of both theoretical modeling supported by this project and also analysis of data supported by the Space Telescope Science Institute and the Chandra X-ray Observatory. We first list papers published in refereed journals, then conference proceedings and book chapters, and also an educational web site.

  5. High-Resolution Polarimetry of Supernova Remnant Kesteven 69

    NASA Astrophysics Data System (ADS)

    Wood, C. A.; Mufson, S. L.; Dickel, J. R.

    2008-06-01

    Reported here are high-resolution 6 cm measurements of the adolescent supernova remnant (SNR) Kesteven 69 made with the hybrid BnC configuration of the Very Large Array. Several three-field mosaics of the polarized and total intensity have been used to study this SNR. These investigations lead to a coherent picture of this region. The expanding shock defines an outer rim of high total intensity, suggesting the front is running into large dense clouds with random magnetic field directions. The SNR consists of predominantly of two types of regions, those with high total and relatively weak polarized emission and those with relatively weak total and strong polarized emission. This morphology can be generally explained by the number of clouds with organized magnetic field along the line of sight. Within this SNR there are regions where the field is varying from radial to tangential. As the SN shock encounters clouds, magnetic fields within clouds will strongly affect cloud dynamics.

  6. Free at Last: AN Energetic Pulsar Escapes its Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Camilo, Fernando

    2002-09-01

    PSR J1016-5857 is a young and energetic pulsar located just outside the supernova remnant (SNR) G284.3-1.8. The morphology of the system argues that the pulsar has a high space velocity, and has caught up with and now overtaken its associated SNR. We have identified an EINSTEIN source, which in the above hypothesis is likely to be a cometary nebula powered by the pulsar. We here propose a short CHANDRA observation of this X-ray source to determine whether it is indeed associated with the pulsar. With the resulting morphological data, we can confirm or refute the pulsar/SNR association, and can probe the pulsar's spin history and interaction with its environment.

  7. Approximate supernova remnant dynamics with cosmic ray production

    NASA Technical Reports Server (NTRS)

    Voelk, H. J.; Dorfi, E. A.; Drury, L. O.

    1985-01-01

    Supernova explosions are the most violent and energetic events in the galaxy and have long been considered probably sources of Cosmic Rays. Recent shock acceleration models treating the Cosmic Rays (CR's) as test particles nb a prescribed Supernova Remnant (SNR) evolution, indeed indicate an approximate power law momentum distribution f sub source (p) approximation p(-a) for the particles ultimately injected into the Interstellar Medium (ISM). This spectrum extends almost to the momentum p = 1 million GeV/c, where the break in the observed spectrum occurs. The calculated power law index approximately less than 4.2 agrees with that inferred for the galactic CR sources. The absolute CR intensity can however not be well determined in such a test particle approximation.

  8. EVOLUTION OF SYNCHROTRON X-RAYS IN SUPERNOVA REMNANTS

    SciTech Connect

    Nakamura, Ryoko; Bamba, Aya; Dotani, Tadayasu; Ishida, Manabu; Kohri, Kazunori

    2012-02-20

    A systematic study of the synchrotron X-ray emission from supernova remnants (SNRs) has been conducted. We selected a total of 12 SNRs whose synchrotron X-ray spectral parameters are available in the literature with reasonable accuracy and studied how their luminosities change as a function of radius. It is found that the synchrotron X-ray luminosity tends to drop especially when the SNRs become larger than {approx}5 pc, despite large scatter. This may be explained by the change of spectral shape caused by the decrease of the synchrotron roll-off energy. A simple evolutionary model of the X-ray luminosity is proposed and is found to reproduce the observed data approximately, with reasonable model parameters. According to the model, the total energy of accelerated electrons is estimated to be 10{sup 47-48} erg, which is well below the supernova explosion energy. The maximum energies of accelerated electrons and protons are also discussed.

  9. 1. Remnants of the last lock on the George Washington ...

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

    1. Remnants of the last lock on the George Washington 'Potowmack Canal, just before the barge entered the Potomac River. The latter can be seen through the foliage of the tree which has grown up in the old canal bed. On the left hand side of the photograph, not shown here in its entirety, are the old iron studdings which held the gates, to permit the barges to pass easily into the river. On the right hand side of the photograph is shown the crumbling remains of the lock with their receased oval space clearly shown, into which the lock gate retrieved when the barge was lowered to the next level. The depth from the spot where the individual is shown pointing to the top of the lock, is about 24 or 25 ft., and the canal has been filled up with broken ... - Potowmack Company: Great Falls Canal, Locks No. 3, 4, 5, Great Falls, Fairfax County, VA

  10. Supernova remnants, planetary nebulae and the distance to NGC 4214

    NASA Astrophysics Data System (ADS)

    Dopita, Michael A.; Calzetti, Daniela; Maíz Apellániz, Jesús; Blair, William P.; Long, Knox S.; Mutchler, Max; Whitmore, Bradley C.; Bond, Howard E.; MacKenty, John; Balick, Bruce; Carollo, Marcella; Disney, Michael; Frogel, Jay A.; O'Connell, Robert; Hall, Donald; Holtzman, Jon A.; Kimble, Randy A.; McCarthy, Patrick; Paresce, Francesco; Saha, Abhijit; Walker, Alistair R.; Silk, Joe; Sirianni, Marco; Trauger, John; Windhorst, Rogier; Young, Erick

    2010-11-01

    We present narrow band, continuum subtracted H α, [S ii], H β, [O iii] and [O ii] data taken with the Wide Field Camera 3 on the Hubble Space Telescope in the nearby dwarf starburst galaxy NGC 4214. From these images, we identify seventeen new planetary nebula candidates, and seven supernova remnant candidates. We use the observed emission line luminosity function of the planetary nebulae to establish a new velocity-independent distance to NGC 4214. We conclude that the PNLF technique gives a reddening independent distance to NGC 4214 of 3.19±0.36 Mpc, and that our current best-estimate of the distance to this galaxy ids 2.98±0.13 Mpc.

  11. Remnant Pacemaker Lead Tips after Lead Extractions in Pacemaker Infections.

    PubMed

    Kim, Daehoon; Baek, Yong-Soo; Lee, Misol; Uhm, Jae-Sun; Pak, Hui-Nam; Lee, Moon-Hyoung; Joung, Boyoung

    2016-07-01

    Complete hardware removal is recommended in the case of patients with cardiovascular implantable electronic device (CIED) infections. However, the complete extraction of chronically implanted leads is not always achieved. The outcomes and optimal management of CIED infections with retained material after lead extractions have not been elucidated. In this case report, we present five patients with CIED infections with remnant lead tips even after lead extractions. Two patients had localized pocket infections, and were managed with antibiotics for a period of more than two weeks. The other three patients had infective endocarditis, and were managed with antibiotics for a period of more than four weeks. In one patient, the lead tip migrated to the right pulmonary artery, but did not produce any symptoms or complications. Only one of five patients experienced a resurgence of an infection. PMID:27482268

  12. NON-MAXWELLIAN Halpha PROFILES IN TYCHO'S SUPERNOVA REMNANT

    SciTech Connect

    Raymond, John C.; Winkler, P. Frank; Blair, William P.; Lee, Jae-Joon; Park, Sangwook E-mail: winkler@middlebury.ed E-mail: lee.j.joon@gmail.co

    2010-04-01

    The broad components of the Halpha lines in most non-radiative shocks can be fit with single-Gaussian components. We have obtained a high-quality spectrum of a position in Tycho's supernova remnant with the MMT and Blue Channel Spectrograph which shows, for the first time, that a single Gaussian does not provide an acceptable fit. This implies that a single temperature Maxwellian particle velocity distribution cannot produce the emission. Possible alternative explanations are explored, including multiple shocks along the line of sight, a pickup ion contribution, a non-thermal tail (Kappa distribution), emission from a precursor in a cosmic ray modified shock, or turbulence. An Hubble Space Telescope image shows a bright knot that might account for a low temperature contribution, and all the possibilities probably contribute at some level. We discuss the implications of each explanation for the shock parameters and physics of collisionless shocks, but cannot conclusively rule out any of them.

  13. Automatic template-guided classification of remnant trees

    NASA Astrophysics Data System (ADS)

    Kennedy, Peter

    Spectral features within satellite images change so frequently and unpredictably that spectral definitions of land cover are often only accurate for a single image. Consequently, land-cover maps are expensive, because the superior pattern recognition skills of human analysts are required to manually tune spectral definitions of land cover to individual images. To reduce mapping costs, this study developed the Template-Guided Classification (TGC) algorithm, which classifies land cover automatically by reusing class information embedded in freely available large-area land-cover maps. TGC was applied to map remnant forest within six 10-m resolution SPOT images of the Vermilion River watershed in Alberta, Canada. Although the accuracy of the resulting forest maps was low (58 % forest user's accuracy and 67 % forest producer's accuracy), there were 25 % and 8 % fewer errors of omission and commission than the original maps, respectively. This improvement would be very useful if it could be obtained automatically over large-areas.

  14. Gamma-Ray Emission From Crushed Clouds in Supernova Remnants

    SciTech Connect

    Uchiyama, Yasunobu; Blandford, Roger D.; Funk, Stefan; Tajima, Hiroyasu; Tanaka, Takaaki; /KIPAC, Menlo Park

    2010-10-27

    It is shown that the radio and gamma-ray emission observed from newly-found 'GeV-bright' supernova remnants (SNRs) can be explained by a model, in which a shocked cloud and shock-accelerated cosmic rays (CRs) frozen in it are simultaneously compressed by the supernova blastwave as a result of formation of a radiative cloud shock. Simple reacceleration of pre-existing CRs is generally sufficient to power the observed gamma-ray emission through the decays of {pi}{sup 0}-mesons produced in hadronic interactions between high-energy protons (nuclei) and gas in the compressed-cloud layer. This model provides a natural account of the observed synchrotron radiation in SNRs W51C, W44 and IC 443 with flat radio spectral index, which can be ascribed to a combination of secondary and reaccelerated electrons and positrons.

  15. Intermediate-age globular clusters in four galaxy merger remnants

    SciTech Connect

    Trancho, Gelys; Miller, Bryan W.; Schweizer, François; Burdett, Daniel P.; Palamara, David

    2014-08-01

    We present the results of combining Hubble Space Telescope optical photometry with ground-based K{sub s} -band photometry from the Gemini imagers NIRI and FLAMINGOS-I to study the globular cluster (GC) populations in four early-type galaxies that are candidate remnants of recent mergers (NGC 1700, NGC 2865, NGC 4382, and NGC 7727). These galaxies were chosen based on their blue colors and fine structure, such as shells and ripples that are indicative of past interactions. We fit the combined VIK{sub s} GC data with simple toy models of mixed cluster populations that contain three subpopulations of different age and metallicity. The fits, done via chi-squared mapping of the parameter space, yield clear evidence for the presence of intermediate-age clusters in each galaxy. We find that the ages of ∼1-2 Gyr for these GC subpopulations are consistent with the previously estimated merger ages for the host galaxies.

  16. What Are the Compact Central Objects in Supernova Remnants?

    NASA Astrophysics Data System (ADS)

    Graber, James

    2002-04-01

    Recent Chandra observations of the compact central objects in supernova remnants have shown puzzling results that do not seem to be consistent with either black holes or neutron stars. (See e.g. Pavlov, Sanwal, Garmire and Zavlin, astro-ph-0112322.) In particular, the inferred effective emitting surface is too small to be the entire surface of a neutron star, but too bright to be a black hole. We discuss the possibility that these compact objects might be red holes instead of black holes or neutron stars. Red holes, which occur in alternate theories of gravity, naturally predict both the greater brightness of the emissions and the smaller effective size of the emitting surface from a collapsed object of the appropriate mass.

  17. Remnant Pacemaker Lead Tips after Lead Extractions in Pacemaker Infections

    PubMed Central

    Kim, Daehoon; Baek, Yong-Soo; Lee, Misol; Uhm, Jae-Sun; Pak, Hui-Nam; Lee, Moon-Hyoung

    2016-01-01

    Complete hardware removal is recommended in the case of patients with cardiovascular implantable electronic device (CIED) infections. However, the complete extraction of chronically implanted leads is not always achieved. The outcomes and optimal management of CIED infections with retained material after lead extractions have not been elucidated. In this case report, we present five patients with CIED infections with remnant lead tips even after lead extractions. Two patients had localized pocket infections, and were managed with antibiotics for a period of more than two weeks. The other three patients had infective endocarditis, and were managed with antibiotics for a period of more than four weeks. In one patient, the lead tip migrated to the right pulmonary artery, but did not produce any symptoms or complications. Only one of five patients experienced a resurgence of an infection. PMID:27482268

  18. Shock Velocity Variations in Supernova Remnant Simulation Experiments

    NASA Astrophysics Data System (ADS)

    Drake, R. P.; Carroll, J. J., III; Smith, T. B.; Reisig, H. N.; Glendinning, S. G.; Estabrook, K.; Remington, B. A.; Wallace, R.; McCray, R.

    1998-11-01

    We are studying the hydrodynamic behavior of a laboratory system that is a good scaled model of young supernova remnants. The hydrodynamic effects are driven by a supersonic flow, produced by the Nova laser. It does this by driving a strong shock, produced by x-ray ablation, out the back of a plastic slab. The ejecta expand, accelerate, cool, and then impact a low-density foam. There the ejecta stagnate and form a reverse shock while driving a strong shock forward through the foam. We observe this hydrodynamic assembly by x-ray radiography. The shock velocities in one case agree with those found by a computer simulation, while in another case they do not. We will report our investigation of this discrepancy. (Work supported by the US Department of Energy under LLNL LDRD-ER Grant No. 97-ERD-022 and by the University of Michigan.)

  19. Comparing supernova remnants around strongly magnetized and canonical pulsars

    NASA Astrophysics Data System (ADS)

    Martin, J.; Rea, N.; Torres, D. F.; Papitto, A.

    2014-11-01

    The origin of the strong magnetic fields measured in magnetars is one of the main uncertainties in the neutron star field. On the other hand, the recent discovery of a large number of such strongly magnetized neutron stars is calling for more investigation on their formation. The first proposed model for the formation of such strong magnetic fields in magnetars was through alpha-dynamo effects on the rapidly rotating core of a massive star. Other scenarios involve highly magnetic massive progenitors that conserve their strong magnetic moment into the core after the explosion, or a common envelope phase of a massive binary system. In this work, we do a complete re-analysis of the archival X-ray emission of the supernova remnants (SNRs) surrounding magnetars, and compare our results with all other bright X-ray emitting SNRs, which are associated with compact central objects (which are proposed to have magnetar-like B-fields buried in the crust by strong accretion soon after their formation), high-B pulsars and normal pulsars. We find that emission lines in SNRs hosting highly magnetic neutron stars do not differ significantly in elements or ionization state from those observed in other SNRs, neither averaging on the whole remnants, nor studying different parts of their total spatial extent. Furthermore, we find no significant evidence that the total X-ray luminosities of SNRs hosting magnetars, are on average larger than that of typical young X-ray SNRs. Although biased by a small number of objects, we found that for a similar age, there is the same percentage of magnetars showing a detectable SNR than for the normal pulsar population.

  20. Hubble Space Telescope Image, Supernova Remnant Cassiopeia A

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The colorful streamers that float across the sky in this photo taken by NASA's Hubble Space Telescope (HST) were created by the universe's biggest firecracker, the titanic supernova explosion of a massive star. The light from the exploding star reached Earth 320 years ago, nearly a century before the United States celebrated its birth with a bang. The dead star's shredded remains are called Cassiopeia A, or 'Cas A' for short. Cas A is the youngest known supernova remnant in our Milky Way Galaxy and resides 10,000 light-years away in the constellation Cassiopeia, so the star actually blew up 10,000 years before the light reached Earth in the late 1600s. This HST image of Cas A shows for the first time that the debris is arranged into thousands of small, cooling knots of gas. This material eventually will be recycled into building new generations of stars and planets. Our own Sun and planets are constructed from the debris of supernovae that exploded billions of years ago. This photo shows the upper rim of the super nova remnant's expanding shell. Near the top of the image are dozens of tiny clumps of matter. Each small clump, originally just a small fragment of the star, is tens of times larger than the diameter of our solar system. The colors highlight parts of the debris where chemical elements are glowing. The dark blue fragments, for example, are richest in oxygen; the red material is rich in sulfur. The images were taken with the Wide Field and Planetary Camera 2 in January 2000 and January 2002. Image Credit: NASA and HST team (Stoics/AURA). Acknowledgment: R. Fesen (Darmouth) and J. Morse ( Univ. of Colorado).

  1. POPULATION III STARS AND REMNANTS IN HIGH-REDSHIFT GALAXIES

    SciTech Connect

    Xu Hao; Norman, Michael L.; Wise, John H. E-mail: mlnorman@ucsd.edu

    2013-08-20

    Recent simulations of Population III star formation have suggested that some fraction form in binary systems, in addition to having a characteristic mass of tens of solar masses. The deaths of metal-free stars result in the initial chemical enrichment of the universe and the production of the first stellar-mass black holes. Here we present a cosmological adaptive mesh refinement simulation of an overdense region that forms a few 10{sup 9} M{sub Sun} dark matter halos and over 13,000 Population III stars by redshift 15. We find that most halos do not form Population III stars until they reach M{sub vir} {approx} 10{sup 7} M{sub Sun} because this biased region is quickly enriched from both Population III and galaxies, which also produce high levels of ultraviolet radiation that suppress H{sub 2} formation. Nevertheless, Population III stars continue to form, albeit in more massive halos, at a rate of {approx}10{sup -4} M{sub Sun} yr{sup -1} Mpc{sup -3} at redshift 15. The most massive starless halo has a mass of 7 Multiplication-Sign 10{sup 7} M{sub Sun }, which could host massive black hole formation through the direct gaseous collapse scenario. We show that the multiplicity of the Population III remnants grows with halo mass above 10{sup 8} M{sub Sun }, culminating in 50 remnants located in 10{sup 9} M{sub Sun} halos on average. This has implications that high-mass X-ray binaries and intermediate-mass black holes that originate from metal-free stars may be abundant in high-redshift galaxies.

  2. An Optical Search For Supernova Remnants in Nearby Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Matonick, D. M.; Fesen, R. A.; Blair, W. P.; Long, K. S.

    1994-12-01

    Imaging with narrow-band Hα , [S II], and red continuum filters has been used to distinguish supernova remnant (SNR) candidates from photoionized nebulae in seven nearby spiral galaxies: NGC 2403, NGC 3031 (M81), NGC 5194 (M51), NGC 5204, NGC 5457 (M101), NGC 5585, and NGC 6946. Nebulae which show [S II]/Hα > 0.45, indicating shock-heated emission, are identified as SNR candidates. The number of SNRs found in each galaxy using this technique is 3 in NGC 5204, 5 in NGC 5585, 30 in NGC 2403, 32 in M81, 35 in NGC 6946, and 112 in M101. Spectra of some of the emission nebulae have also been obtained, and were used to confirm SNR identifications. Because of its comparatively high radial velocity, M51 could not be examined adequately with our filter set; however, one bright SNR was found and spectroscopically confirmed. In NGC 2403, we obtained spectra on remnant candidates 1 and 2 of D'Odorico et al. (1980, A&AS, 40, 67), and confirmed them to be SNRs. We also detect the optical SNR identified by Blair & Fesen (1994, ApJ, 424, L103) in NGC 6946, and find an optical SNR counterpart to the X-ray source S2 identified by Schlegel (1994, ApJ, 424, L99). Sizes of observed SNRs range from unresolved (< 50 pc) to over 300x150 pc for one object in NGC 5585. Although our search technique limits our detection of SNRs embedded in bright H II regions, in the galaxies with clearly defined spiral arms (i.e NGC 6946, M81, M101), most SNRs appear to trace the spiral arms. Analysis of luminosity functions, diameters, abundances, and distributions of the samples of SNRs will also be discussed.

  3. The Extraordinary Supernova Remnant in NGC 4449 Revisited

    NASA Astrophysics Data System (ADS)

    Long, Knox S.; Blair, William P.; Fesen, Robert A.; Milisavljevic, Dan; Winkler, P. Frank

    2015-01-01

    NGC 4449, a Magellanic-type irregular galaxy at a distance of about 4 Mpc, contains the most luminous known supernova remnant (SNR) in both X-ray and optical bands. Its optical spectrum is characterized by broad lines from O, Ne, S, Ar, and Ca, and its size and expansion velocity (6000 km/s) suggest that the unobserved SN exploded about 65 years ago. The remnant¹s extraordinary brightness can be attributed to the interaction of supernova ejecta with unusually dense and extensive circumstellar material. We will present new Chandra imaging, together with UV/Optical spectra of the SNR from HST/STIS and the MMT. The X-ray luminosity of the SNR is less than when it was detected with Einstein in 1980, but the luminosity and X-ray spectral shape have remained relatively constant over the last 10 years. In the FUV, the HST spectra show for the first time broad line emission from C IV 1550 Å, as well as Si IV + O IV at 1400 Å and O III] at 1660 Å. The new NUV and optical spectra are fairly similar to earlier HST/FOS spectra and to ground-based spectra we have obtained over the last decade. Here we describe these new observations, and our attempts to understand the nature of the progenitor of the SNR.We acknowledge support for this effort from NASA through grant GO-12462 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc, under NASA contract NAS5-26555, and through Chandra Award Number GO9-0075, issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory, under NASA contract NAS8-03060.

  4. Supernova remnant W49B and its environment

    SciTech Connect

    Zhu, H.; Tian, W. W.; Zuo, P. E-mail: tww@bao.ac.cn

    2014-10-01

    We study gamma-ray supernova remnant (SNR) W49B and its environment using recent radio and infrared data. Spitzer Infrared Spectrograph low resolution data of W49B shows shocked excitation lines of H{sub 2} (0,0) S(0)-S(7) from the SNR-molecular cloud interaction. The H{sub 2} gas is composed of two components with temperatures of ∼260 K and ∼1060 K, respectively. Various spectral lines from atomic and ionic particles are detected toward W49B. We suggest that the ionic phase has an electron density of ∼500 cm{sup –3} and a temperature of ∼10{sup 4} K by the spectral line diagnoses. The mid- and far-infrared data from MSX, Spitzer, and Herschel reveal a 151 ± 20 K hot dust component with a mass of 7.5 ± 6.6 × 10{sup –4} M {sub ☉} and a 45 ± 4 K warm dust component with a mass of 6.4 ± 3.2 M {sub ☉}. The hot dust is likely from materials swept up by the shock of W49B. The warm dust may possibly originate from the evaporation of clouds interacting with W49B. We build the H I absorption spectra of W49B and four nearby H II regions (W49A, G42.90+0.58, G42.43-0.26, and G43.19-0.53) and study the relation between W49B and the surrounding molecular clouds by employing the 2.12 μm infrared and CO data. We therefore obtain a kinematic distance of ∼10 kpc for W49B and suggest that the remnant is likely associated with the CO cloud at about 40 km s{sup –1}.

  5. Supernova remnant evolution in uniform and non-uniform media

    NASA Astrophysics Data System (ADS)

    Ferreira, S. E. S.; de Jager, O. C.

    2008-01-01

    Aims:In this work numerical simulations showing the time evolution of supernova remnants (SNRs) in uniform and non-uniform interstellar medium (ISM) are presented. Methods: We use a hydrodynamic model including a kinematic calculation of the interstellar magnetic field. Important parameters influencing SNR evolution include the ejecta mass and energy of the remnant, as well as the ISM density and adiabatic index. Results: By varying these parameters we constructed an analytical expression giving the return time of the SNR reverse shock to the origin, in terms of these parameters. We also found that the reverse shock spends half of its time moving outward and the other half returning to the origin. Also computed is SNR evolution in non-uniform media where the blast wave moves from one medium into either a less or more dense medium. As the SNR moves into a medium of higher density a reflection wave is created at the interface between the two media which is driven back toward the center. This drives mass via a nonspherical flow away from the discontinuity. As this wave moves inward it also drags some of the ISM field lines (if the field is parallel with the interface) with it and heats the inside of the SNR resulting in larger temperatures in this region. When a SNR explodes in a medium with a high density and the blast wave propagates into a medium with a lower density, a cavity is being blown away changing the geometry of the high density region. Also, once the forward shock moves into the medium of less density a second reverse shock will start to evolve in this region.

  6. A 3-dimensional Analysis of the Cassiopeia A Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Isensee, Karl

    We present a multi-wavelength study of the nearby supernova remnant Cassiopeia A (Cas A). Easily resolvable supernova remnants such as Cas A provide a unique opportunity to test supernova explosion models. Additionally, we can observe key processes in the interstellar medium as the ejecta from the initial explosion encounter Cas A's powerful shocks. In order to accomplish these science goals, we used the Spitzer Space Telescope's Infrared Spectrograph to create a high resolution spectral map of select regions of Cas A, allowing us to make a Doppler reconstruction of its 3-dimensional structure structure. In the center of the remnant, we find relatively pristine ejecta that have not yet reached Cas A's reverse shock or interacted with the circumstellar environment. We observe O, Si, and S emission. These ejecta can form both sheet-like structures as well as filaments. Si and O, which come from different nucleosynthetic layers of the star, are observed to be coincident in some regions, and separated by >500 km s -1 in others. Observed ejecta traveling toward us are, on average, ˜800 km s -1 slower than the material traveling away from us. We compare our observations to recent supernova explosion models and find that no single model can simultaneously reproduce all the observed features. However, models of different supernova explosions can collectively produce the observed geometries and structures of the emission interior to Cas A's reverse shock. We use the results from the models to address the conditions during the supernova explosion, concentrating on asymmetries in the shock structure. We also predict that the back surface of Cassiopeia A will begin brightening in ∼30 years, and the front surface in ˜100 years. We then used similar observations from 3 regions on Cas A's reverse shock in order to create more 3-dimensional maps. In these regions, we observe supernova ejecta both immediately before and during the shock-ejecta interaction. We determine that the

  7. G65.2+5.7: A Thermal Composite Supernova Remnant with a Cool Shell

    NASA Technical Reports Server (NTRS)

    Shelton, R. L.; Kuntz, K. D.; Petre, R.

    2004-01-01

    This paper presents archival ROSAT PSPC observations of the G65.2+5.7 supernova remnant (also known as G65.3+5.7). Little material obscures this remnant and so it was well observed, even at the softest end of ROSATs bandpass (approx. 0.11 to 0.28 keV). These soft X-ray images reveal the remnant s centrally-filled morphology which, in combination with existing radio frequency observations, places G65.2+5.7 in the thermal composite (mixed morphology) class of supernova remnants. Not only might G65.2+5.7 be the oldest known thermal composite supernova remnant, but owing to its optically revealed cool, dense shell, this remnant supports the proposal that thermal composite supernova remnants lack X-ray bright shells because they have evolved beyond the adiabatic phase. These observations also reveal a slightly extended point source centered on RA = l9(sup h) 36(sup m) 46(sup s). dec = 30 deg.40 min.07 sec.and extending 6.5 arc min in radius in the band 67 map. The source of this emission has yet to be discovered, as there is no known pulsar at this location.

  8. Receptor-mediated uptake of remnant lipoproteins by cholesterol-loaded human monocyte-macrophages

    SciTech Connect

    Van Lenten, B.J.; Fogelman, A.M.; Jackson, R.L.; Shapiro, S.; Haberland, M.E.; Edwards, P.A.

    1985-07-25

    Normal human monocyte-macrophages were cholesterol-loaded, and the rates of uptake and degradation of several lipoproteins were measured and compared to rates in control cells. Receptor activities for SVI-rabbit beta-very low density lipoproteins (beta-VLDL), SVI-human low density lipoprotein, and SVI-human chylomicrons were down-regulated in cholesterol-loaded cells; however, the rate of uptake and degradation of SVI-human chylomicron remnants was unchanged from control cells. Cholesterol-loaded alveolar macrophages from a Watanabe heritable hyperlipidemic rabbit, which lack low density lipoprotein receptors, showed receptor down-regulation for SVI-beta-VLDL but not for SVI-human chylomicron remnants. In addition to chylomicron remnants, apo-E-phospholipid complexes competed for SVI-chylomicron remnant uptake, but apo-A-I-phospholipid complexes did not. Chylomicron remnants and beta-VLDL were equally effective in competing for SVI-beta-VLDL and SVI-chylomicron remnant uptake in cholesterol-loaded macrophages. The authors conclude: 1) specific lipoprotein receptor activity persists in cholesterol-loaded cells; 2) this receptor activity recognizes lipo-proteins (at least in part) by their apo-E content; and 3) cholesteryl ester accumulation can occur in monocyte-macrophages incubated with chylomicron remnants.

  9. Modeling the shell type TeV supernove remnant RX J1713-3946

    SciTech Connect

    Fryer, Christopher Lee; Fan, Zhonghui; Liu, Siming

    2009-01-01

    We simulate the shock waves of shell type supernova remnants with a prototype progenitor of 15 M{sub {circle_dot}} and fit the size and lifetime of SNR RX J1713-3946 with a density of {approx} 1O{sup -26}g cm{sup -3} for the shocked downstream plasma. Such a density is required for efficient stochastic electron acceleration and leads to a thermal X-ray flux more than one order of magnitude lower than the observed featureless X-ray flux. Fast mode waves must be excited to have efficient stochastic electron acceleration. We find that (1) the acceleration efficiency needs to be at least 10 times higher than that through the cyclotron resonances, implying much more efficient acceleration through the transit-time damping process, and (2) the distribution of the accelerated electrons is very sensitive to the ratio of the speed in the downstream to the shock suggesting a dynamo process that can regulate the magnetic field in such a way that the electron distribution doesn't change dramatically throughout the evolution history of the shock waves.

  10. UNRAVELING THE ORIGIN OF OVERIONIZED PLASMA IN THE GALACTIC SUPERNOVA REMNANT W49B

    SciTech Connect

    Lopez, Laura A.; Castro, Daniel; Pearson, Sarah; Ramirez-Ruiz, Enrico; Yamaguchi, Hiroya; Slane, Patrick O.; Smith, Randall K.

    2013-11-10

    Recent observations have shown several supernova remnants (SNRs) have overionized plasmas, where ions are stripped of more electrons than they would be if in equilibrium with the electron temperature. Rapid electron cooling is necessary to produce this situation, yet the physical origin of that cooling remains uncertain. To assess the cooling scenario responsible for overionization, in this paper we identify and map the overionized plasma in the Galactic SNR W49B based on a 220 ks Chandra Advanced CCD Imaging Spectrometer observation. We performed a spatially resolved spectroscopic analysis, measuring the electron temperature by modeling the continuum and comparing it to the temperature given by the flux ratio of the He-like and H-like lines of sulfur and argon. Using these results, we find that W49B is overionized in the west, with a gradient of overionization increasing from east to west. As the ejecta expansion is impeded by molecular material in the east but not in the west, our overionization maps suggest the dominant cooling mechanism is adiabatic expansion of the hot plasma.

  11. Intermediate-mass black holes from Population III remnants in the first galactic nuclei

    NASA Astrophysics Data System (ADS)

    Ryu, Taeho; Tanaka, Takamitsu L.; Perna, Rosalba; Haiman, Zoltán

    2016-08-01

    We report the formation of intermediate-mass black holes (IMBHs) in suites of numerical $N$-body simulations of Population III remnant black holes (BHs) embedded in gas-rich protogalaxies at redshifts $z\\gtrsim10$. We model the effects of gas drag on the BHs' orbits, and allow BHs to grow via gas accretion, including a mode of hyper-Eddington accretion in which photon trapping and rapid gas inflow suppress any negative radiative feedback. Most initial BH configurations lead to the formation of one (but never more than one) IMBH in the center of the protogalaxy, reaching a mass of $10^{3-5}\\mathrm{M}_{\\odot}$ through hyper-Eddington growth. Our results suggest a viable pathway to forming the earliest massive BHs in the centers of early galaxies. We also find that the nuclear IMBH typically captures a stellar-mass BH companion, making these systems observable in gravitational waves as extreme mass-ratio inspirals (EMRIs) with \\textit{eLISA}.

  12. Discovery of Strong Radiative Recombination Continua from the Supernova Remnant IC 443 with Suzaku

    NASA Astrophysics Data System (ADS)

    Yamaguchi, H.; Ozawa, M.; Koyama, K.; Masai, K.; Hiraga, J. S.; Ozaki, M.; Yonetoku, D.

    2009-11-01

    We present the Suzaku spectroscopic study of the Galactic middle-aged supernova remnant (SNR) IC 443. The X-ray spectrum in the 1.75-6.0 keV band is described by an optically thin thermal plasma with the electron temperature of ~0.6 keV and several additional Lyman lines. We robustly detect, for the first time, strong radiative recombination continua (RRC) of H-like Si and S around at 2.7 and 3.5 keV. The ionization temperatures of Si and S determined from the intensity ratios of the RRC to He-like Kα lines are ~1.0 keV and ~1.2 keV, respectively. We thus find firm evidence for an extremely overionized (recombining) plasma. As the origin of the overionization, a thermal conduction scenario argued in previous work is not favored in our new results. We propose that the highly ionized gas was made at the initial phase of the SNR evolution in dense regions around a massive progenitor, and the low electron temperature is due to a rapid cooling by an adiabatic expansion.

  13. Thermal and Nonthermal X-Ray Emission from the Forward Shock in Tycho's Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Hwang, Una; Decourchelle, Anne; Holt, Stephen S.; Petre, Robert

    2002-12-01

    We present Chandra X-ray images of Tycho's supernova remnant that delineate its outer shock as a thin, smooth rim along the straight northeastern edge and most of the circular western half. The images also show that the Si and S ejecta are highly clumpy and have reached near the forward shock at numerous locations. Most of the X-ray spectra that we examine along the rim show evidence of line emission from Si and S ejecta, while the continuum is well represented by either a thermal or a nonthermal model. If the continuum is assumed to be thermal, the electron temperatures at the rim are all similar at about 2 keV, while the ionization ages are very low because of the overall weakness of the line emission. These electron temperatures are substantially below those expected for equilibration of the electron and ion temperatures, assuming shock velocities inferred from radio and X-ray expansion measurements; the electron-to-mean temperature ratios are <~0.1-0.2, indicating that collisionless heating of the electrons at the shock is modest. The nonthermal contribution to these spectra might be important, but cannot be strongly constrained by these data. It could account for as much as half of the flux in the 4-6 keV energy range, based on an extrapolation of the hard X-ray spectrum above 10 keV.

  14. Thermal and Nonthermal X-ray Emission from the Forward Shock in Tycho's Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Hwang, Una; Decourchelle, Anne; Holt, Stephen S.; Petre, Robert; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We present Chandra CCD images of Tycho's supernova remnant that delineate its outer shock, seen as a thin, smooth rim along the straight northeastern edge and most of the circular western half. The images also show that the Si and S ejecta are highly clumpy, and have reached the forward shock at numerous locations. Most of the X-ray spectra that we examine along the rim show line emission from Si and S, which in some cases must come from ejecta; the continuum is well represented by either thermal or nonthermal models. In the case that the continuum is assumed to be thermal, the temperatures at the rim are all similar at about 2 keV, and the ionization ages are very low because of the overall weakness of the line emission. Assuming shock velocities inferred from radio and X-ray expansion measurements, these temperatures are substantially below those expected for equilibration of the electron and ion temperatures; electron to mean temperature ratios of approximately less than 0.1 - 0.2 indicate at most modest collisionless heating of the electrons at the shock. The nonthermal contribution to these spectra may be important, however, and may account for as many as half of the counts in the 4-6 keV energy range, based on an extrapolation of the hard X-ray spectrum above 10 keV.

  15. A Deep Chandra Observation of Kepler's Supernova Remnant: A Type Ia Event with Circumstellar Interaction

    NASA Astrophysics Data System (ADS)

    Reynolds, Stephen P.; Borkowski, Kazimierz J.; Hwang, Una; Hughes, John P.; Badenes, Carles; Laming, J. M.; Blondin, J. M.

    2007-10-01

    We present initial results of a 750 ks Chandra observation of the remnant of Kepler's supernova of AD 1604. The strength and prominence of iron emission, together with the absence of O-rich ejecta, demonstrate that Kepler resulted from a thermonuclear supernova, even though evidence for circumstellar interaction is also strong. We have analyzed spectra of over 100 small regions, and find that they fall into three classes. (1) The vast majority show Fe L emission between 0.7 and 1 keV and Si and S Kα emission; we associate these with shocked ejecta. A few of these are found at or beyond the mean blast wave radius. (2) A very few regions show solar O/Fe abundance ratios; these we associate with shocked circumstellar medium (CSM). Otherwise O is scarce. (3) A few regions are dominated by continuum, probably synchrotron radiation. Finally, we find no central point source, with a limit ~100 times fainter than the central object in Cas A. The evidence that the blast wave is interacting with CSM may indicate a Ia explosion in a more massive progenitor.

  16. The Suzaku Key Project of the Kepler Supernova Remnant: A Status Report

    NASA Astrophysics Data System (ADS)

    Park, Sangwook; Badenes, C.; Hughes, J. P.; Slane, P. O.; Burrows, D. N.; Mori, K.

    2010-02-01

    The Kepler supernova remnant (SNR) is a historical (SN 1604) Type Ia SNR with a peculiar progenitor that exploded in the ambient medium modified by stellar winds. We detect atomic emission lines from trace ejecta elements Mn and Cr in the Kepler SNR using our initial 100 ks Suzaku observation. The detection of these low abundant metal species produced by incomplete Si-burning in the Type Ia SN provides a unique opportunity to reveal the progenitor's metallicity. We also detect K line emission from the Ni-rich ejecta which was produced in the nuclear statistical equilibrium at the deepest core of the progenitor. As the start of our Suzaku Key Project of the Kepler SNR to place a tight constraint on the progenitor's metallicity, we performed 220 ks background observations to reduce the systematic errors on the Mn and Cr line flux measurements. We report on the refined measurements of the Mn to Cr line flux ratio using our new background data. Our preliminary results suggest an enhanced metallicity (several times the Solar) for the Kepler SNR's progenitor. The completion of our Suzaku Key Project with the upcoming deep Kepler observation will be essential to pin down the suggested high metallicity of the progenitor by significantly reducing the large statistical uncertainties embedded in the current data.

  17. X-Ray Emission from a Merger Remnant, NGC 7252 (the ``Atoms-for-Peace'' Galaxy)

    NASA Astrophysics Data System (ADS)

    Awaki, Hisamitsu; Matsumoto, Hironori; Tomida, Hiroshi

    2002-03-01

    We observed a nearby merger remnant NGC 7252 with the X-ray satellite ASCA and detected X-ray emission with the X-ray flux of (1.8+/-0.3)×10-13 ergs s-1 cm-2 in the 0.5-10 keV band. This corresponds to the X-ray luminosity of 8.1×1040 ergs s-1. The X-ray emission is well described with a two-component model: a soft component with kT=0.72+/-0.13 keV and a hard component with kT>5.1 keV. Although NGC 7252 is referred to as a dynamically young protoelliptical, the 0.5-4 keV luminosity of the soft component is about 2×1040 ergs s-1, which is low for an early-type galaxy. The ratio of LX/LFIR suggests that the soft component originated from the hot gas due to star formation. Its low luminosity can be explained by the gas ejection from the galaxy as galaxy winds. Our observation reveals the existence of hard X-ray emission with the 2-10 keV luminosity of 5.6×1040 ergs s-1. This may indicate the existence of nuclear activity or an intermediate-mass black hole in NGC 7252.

  18. Two new supernova remnants in OB associations in the Large Magellanic Cloud

    NASA Technical Reports Server (NTRS)

    Smith, R. Chris; Chu, You-Hua; Mac Low, Mordecai-Mark; Oey, M. S.; Klein, Uli

    1994-01-01

    We discovered two extended x-ray sources in a Roentgen Satellite (ROSAT) Positron Sensitive Proportional Counter (PSPC) observation pointed at the H II region N9 in the Large Magellanic Cloud. These two sources are in the H II regions N4D and N9. The x-ray characteristics suggest that both might be supernova remnants (SNRs). Follow-up charge coupled device (CCD) images taken with interference filters show high (S II)/H-alpha ratios in the optical nebulae of these x-ray sources, confirming the presence of high velocity shocks commonly seen in SNRs. These two sources are also detected in the radio continuum at 8.55 and 4.75 GHz; both appear nonthermal compared to nearby H II regions. The confirmation of these two SNRs demonstrates that many SNRs in or near H II regions have been overlooked in previous surveys, and that the ROSAT x-ray survey combined with an optical CCD imaging survey of the Magellanic Clouds would provide the most effective way to uncover SNRs.

  19. 3D Simulations of Supernova Remnants from Type Ia Supernova Models

    NASA Astrophysics Data System (ADS)

    Johnson, Heather; Reynolds, S. P.; Frohlich, C.; Blondin, J. M.

    2014-01-01

    Type Ia supernovae (SNe) originate from thermonuclear explosions of white dwarfs. A great deal is still unknown about the explosion mechanisms, particularly the degree of asymmetry. However, Type Ia supernova remnants (SNRs) can bear the imprint of asymmetry long after the explosion. A SNR of interest is G1.9+0.3, the youngest Galactic SNR, which demonstrates an unusual spatial distribution of elements in the ejecta. While its X-ray spectrum is dominated by synchrotron emission, spectral lines of highly ionized Si, S, and Fe are seen in a few locations, with Fe near the edge of the remnant and with strongly varying Fe/Si ratios. An asymmetric explosion within the white dwarf progenitor may be necessary to explain these unusual features of G1.9+0.3, in particular the shocked Fe at large radii. We use the VH-1 hydrodynamics code to evolve initial Type Ia explosion models in 1, 2, and 3 dimensions at an age of 100 seconds provided by other researchers to study asymmetry, the ignition properties, and the nucleosynthesis resulting from these explosions. We follow the evolution of these models interacting with a uniform external medium to a few hundred years in age. We find the abundance and location of ejecta elements from our models to be inconsistent with the observations of G1.9+0.3; while our models show asymmetric element distributions, we find no tendency for iron-group elements to be found beyond intermediate-mass elements, or for significant iron to be reverse-shocked at all at the age of G1.9+0.3. We compare the amounts of shocked iron-group and intermediate-mass elements as a function of time in the different models. Some new kind of explosion asymmetry may be required to explain G1.9+0.3. This work was performed as part of NC State University's Undergraduate Research in Computational Astrophysics (URCA) program, an REU program supported by the National Science Foundation through award AST-1032736.

  20. Chandra Captures Remnant of Star-Shattering Explosion

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This is a true color image from the Chandra X-Ray Observatory (CXO) of N132D showing the remnant of an explosion of a massive star in the Large Magellanic Cloud, a nearby galaxy about 180,000 light years from Earth. The colors represent different ranges of X-rays, with red, green, and blue representing low, medium, and higher X-ray energies respectively. The horseshoe shaped remnant is thought to be due to shock waves from the collision of the supernova ejecta with cool giant gas clouds. As the shock wave moves through the gas, it is heated to millions of degrees, producing the glowing x-ray shell. The CXO, formerly the Advanced X-Ray Astrophysics Facility (AXAF), was renamed the CXO in honor of the late Indian-American Novel Laureate Subrahmanyan Chandrasekhar in 1999. The CXO is the world's most powerful and most sophisticated x-ray telescope ever built. It produces picture-like images of x-ray emissions analogous to those made in visible light, as well as gathers data on the chemical composition of x-ray radiating objects. The CXO helps astronomers worldwide better understand the structure and evolution of the universe by studying powerful sources of x-rays such as exploding stars, matter falling into black holes, and other exotic celestial objects. The Observatory has three major parts: (1) the x-ray telescope, whose mirrors will focus x-rays from celestial objects; (2) the science instruments that record the x-rays so that x-ray images can be produced and analyzed; and (3) the spacecraft, which provides the environment necessary for the telescope and the instruments to work. TRW, Inc. was the prime contractor for the development the CXO and NASA's Marshall Space Flight Center was responsible for its project management. The Smithsonian Astrophysical Observatory controls science and flight operations of the CXO for NASA from Cambridge, Massachusetts. The Observatory was launched July 22, 1999 aboard the Space Shuttle Columbia, STS-93 mission.

  1. Nitric Oxide Modulates Vascular Disease in the Remnant Kidney Model

    PubMed Central

    Kang, Duk-Hee; Nakagawa, Takahiko; Feng, Lili; Johnson, Richard J.

    2002-01-01

    A loss of the microvascular endothelium occurs in the remnant kidney model of renal disease and may play an important role in progression (Kang et al, J Am Soc Nephrol, 12:1434, 2001). Given that nitric oxide (NO) is a potent endothelial cell survival factor, we hypothesized that stimulating (with l-arginine) or blocking (with nitro-l-arginine methyl ester, (l-NAME)) NO synthesis could modulate the integrity of the microvasculature and hence affect progression of renal disease. Rats underwent 5/6 nephrectomy (RK) and then were randomized at 4 weeks to receive vehicle, l-NAME, or l-arginine for 4 weeks. Systolic blood pressure and renal function was measured, and tissues were collected at 8 weeks for histological and molecular analyses. The effect of modulation of NO on vascular endothelial growth factor (VEGF) expression in rat aortic vascular smooth muscle cells (SMC) and mouse medullary thick ascending limb tubular epithelial cells (mTAL) was also studied. Inhibition of NO with l-NAME was associated with more rapid progression compared to RK alone, with worse blood pressure, proteinuria, renal function, glomerulosclerosis, and tubulointerstitial fibrosis. The injury was also associated with more glomerular and peritubular capillary endothelial cell loss in association with an impaired endothelial proliferative response. Interestingly, the preglomerular endothelium remained intact or was occasionally hyperplastic, and this was associated with a pronounced proliferation of the vascular SMCs with de novo expression of VEGF. Cell culture studies confirmed a divergent effect of NO inhibition on VEGF expression, with inhibition of VEGF synthesis in mTAL cells and stimulation of VEGF in vascular SMC. In contrast to the effects of NO inhibition, stimulation of NO with l-arginine had minimal effects in this rat model of progressive renal disease. These studies confirm that blockade of NO synthesis accelerates progression of renal disease in the remnant kidney model, and

  2. A Study of Supernova Remnants with Center-Filled X-Ray Morphology

    NASA Technical Reports Server (NTRS)

    Slane, Patrick O.

    2001-01-01

    The proposed study entails use of archival data, primarily from past and active X-ray observatories, to study the properties of a class of supernova remnants (SNRs) which display a centrally-bright X-ray morphology. Several models which have been proposed to explain the morphology are being investigated for comparisons with measured characteristics of several remnants: nonthermal emission from a central synchrotron nebula; thermal emission enhanced by slow evaporation of cool clouds in the hot SNR interior; and relic thermal emission from the SNR interior after the remnant has entered the radiative phase of evolution, thus causing the shell emission to cease.

  3. Endovascular Coiling of Aneurysm Remnants after Clipping in Patients with Follow-up

    PubMed Central

    Mangiafico, S.; Cellerini, M.; Villa, G.; Ammannati, F.; Paoli, L.; Mennonna, P.

    2005-01-01

    Summary The vast majority of intracranial aneurysms can be obliterated completely with surgical clipping. However, postoperative remnants occur in about 4 to 8% of patients who undergo postoperative angiography. Endovascular embolization has been successfully performed in patients with postoperative aneurysm remnant and it may represent a therapeutic alternative to surgical reintervention. Twelve aneurysm remnants after surgical clipping were treated with endovascular embolization using GDC. All aneurysms were located in the anterior circulation. Our experience confirms the feasibility and relative safety of this treatment strategy that may be considered a valid alternative to reintervention. PMID:20584434

  4. Gamma-ray emission from young supernova remnants: Hadronic or leptonic?

    NASA Astrophysics Data System (ADS)

    Gabici, Stefano; Aharonian, Felix

    2016-07-01

    The debate on the nature of the gamma-ray emission from young supernova remnants is still open. Ascribing such emission to hadronic rather than leptonic processes would provide an evidence for the acceleration of protons and nuclei, and this fact would fit with the very popular (but not proven) paradigm that supernova remnants are the sources of Galactic cosmic rays. Here, we discuss this issue with a particular focus on the best studied gamma-ray-bright supernova remnant: RX J1713.7-3946.

  5. The x-ray structure of the supernova remnant W49B

    NASA Technical Reports Server (NTRS)

    Dickel, John R.; Murphy, Rosa; Chu, You-Hua; Garcia, Guillermo; Goscha, Daniel

    1994-01-01

    Comparison of x-ray and radio images of W49B and other supernova remnants (SNR) provides detailed information on the mechanisms responsible for the emission and on the evolution of the remnants. There is faint x-ray emission from all parts of W49B but most of it is concentrated near the center of the remnant, unlike the radio emission which arises in a shell near the periphery. This structure indicates that this SNR is in the adolescent phase of its lifetime.

  6. DEM L241, A SUPERNOVA REMNANT CONTAINING A HIGH-MASS X-RAY BINARY

    SciTech Connect

    Seward, F. D.; Charles, P. A.; Foster, D. L.; Dickel, J. R.; Romero, P. S.; Edwards, Z. I.; Perry, M.; Williams, R. M.

    2012-11-10

    A Chandra observation of the Large Magellanic Cloud supernova remnant DEM L241 reveals an interior unresolved source which is probably an accretion-powered binary. The optical counterpart is an O5III(f) star making this a high-mass X-ray binary with an orbital period likely to be of the order of tens of days. Emission from the remnant interior is thermal and spectral information is used to derive density and mass of the hot material. Elongation of the remnant is unusual and possible causes of this are discussed. The precursor star probably had mass >25 M {sub Sun}.

  7. X-ray iron-line emission from the SN 185 remnant

    NASA Technical Reports Server (NTRS)

    Winkler, P. F.

    1979-01-01

    Radio and optical research was carried out in order to show that the supernova remnant RCW86 is a remnant of the earliest supernova event ever recorded in history (185 AD). The results are as follows: (1) an iron-line emission was found at 6.7 keV; (2) the temperature measured from HEAO-1 was approximately 6 keV; and (3) the equivalent width was consistent within the uncertainties with a cosmic iron abundance. These results support the identification of the supernova remnant RCW86 (it's X-ray source) with the historic supernova event.

  8. Infrared Spectral Mapping of Supernova Remnants. I. N63A and Its Environment

    NASA Astrophysics Data System (ADS)

    Caulet, Adeline; Williams, Rosa M.

    2012-12-01

    We present Spitzer Space Telescope spectra of the supernova remnant (SNR) N63A and its native H II region N63 in the Large Magellanic Cloud. We measure nebular fine-structure lines, H2 lines, and polycyclic aromatic hydrocarbons (PAHs). The lines contribute half of the flux in the Spitzer 24 μm image of N63A shocked lobes, but only <=10% elsewhere. The mid-IR flux is largely due to thermal continuum emission from dust in and around N63A plasma. Electron densities are low everywhere; the differences in mid-IR line ratios separate N63A plasma and its high-excitation surroundings from N63A low-excitation optical lobes. We compare the observed line fluxes and ratios within N63A's shocked lobes and plasma with the predictions from models for moderate and fast shocks to constrain pre-shock densities and shock velocities. N63A's photoionized lobe contains a warm photodissociation region in pressure equilibrium with optically ionized gas. We apply a physical dust model to our spectra supplemented by MIPS photometry. We derive the intensity of radiation heating the dust, the mass fraction due to PAHs, and the masses of dust within our sampled regions and of cooler grains in the diffuse interstellar medium. N63A's shocked lobes and plasma contain ~0.07 M ⊙ of hot grains, comparable to amounts in other SNRs. Within N63A there is ~0.7 M ⊙ of warm grains exposed to >=100 times the intensity of the local interstellar radiation field. Within the regions, 92% of the total dust mass resides in cool grains emitting <=27% of their mid-IR luminosity. In loving memory of Sylvie Caulet-Maugendre: "I used to believe in forever, but forever is too good to be true." A. A. Milne, Winnie-the-Pooh.

  9. INFRARED SPECTRAL MAPPING OF SUPERNOVA REMNANTS. I. N63A AND ITS ENVIRONMENT

    SciTech Connect

    Caulet, Adeline; Williams, Rosa M.

    2012-12-20

    We present Spitzer Space Telescope spectra of the supernova remnant (SNR) N63A and its native H II region N63 in the Large Magellanic Cloud. We measure nebular fine-structure lines, H{sub 2} lines, and polycyclic aromatic hydrocarbons (PAHs). The lines contribute half of the flux in the Spitzer 24 {mu}m image of N63A shocked lobes, but only {<=}10% elsewhere. The mid-IR flux is largely due to thermal continuum emission from dust in and around N63A plasma. Electron densities are low everywhere; the differences in mid-IR line ratios separate N63A plasma and its high-excitation surroundings from N63A low-excitation optical lobes. We compare the observed line fluxes and ratios within N63A's shocked lobes and plasma with the predictions from models for moderate and fast shocks to constrain pre-shock densities and shock velocities. N63A's photoionized lobe contains a warm photodissociation region in pressure equilibrium with optically ionized gas. We apply a physical dust model to our spectra supplemented by MIPS photometry. We derive the intensity of radiation heating the dust, the mass fraction due to PAHs, and the masses of dust within our sampled regions and of cooler grains in the diffuse interstellar medium. N63A's shocked lobes and plasma contain {approx}0.07 M{sub Sun} of hot grains, comparable to amounts in other SNRs. Within N63A there is {approx}0.7 M{sub Sun} of warm grains exposed to {>=}100 times the intensity of the local interstellar radiation field. Within the regions, 92% of the total dust mass resides in cool grains emitting {<=}27% of their mid-IR luminosity.

  10. Ecosystem characteristics of remnant, headwater tallgrass prairie streams.

    PubMed

    Larson, Danelle M; Dodds, Walter K; Jackson, Karen E; Whiles, Matt R; Winders, Kyle R

    2013-01-01

    North America has lost >95% of its native tallgrass prairie due to land conversion, making prairie streams one of the most endangered ecosystems. Research on the basic ecosystem characteristics of the remaining natural prairie streams will inform conservation and management. We examined the structure and function of headwater streams draining tallgrass prairie tracts at Osage Prairie in Missouri and the Konza Prairie Biological Station in Kansas and compared those values with literature values for streams draining agricultural watersheds in the region. We quantified physicochemical and biological characteristics for 2 yr. Streams at Osage and Konza were characterized by low nutrients and low suspended sediments (substantially lower than impacted sites in the region), slight heterotrophic status, and high temporal variability. Suspended sediments and nutrient concentrations were generally low in all prairie streams, but storms increased concentrations of both by 3- to 12-fold. Spring prescribed burns were followed by a slight increase in chlorophyll and decreased nutrients, potentially due to greater light availability. Benthic macroinvertebrate communities at Osage showed seasonal patterns that were probably linked to variable hydrology. We found nine amphibian species using the Osage streams as habitat or breeding sites, but little usage at Konza was probably due to dry conditions and low discharge. Our study indicates that two remnant tallgrass prairie streams along a longitudinal gradient are fairly similar in terms of physicochemical features and have good water quality relative to agricultural watersheds but can differ considerably in macroinvertebrate and amphibian abundance. PMID:23673759

  11. Magnetic Field Amplification by Cosmic Rays in Supernova Remnant Shocks

    NASA Astrophysics Data System (ADS)

    Riquelme, Mario A.; Spitkovsky, A.

    2010-02-01

    Cosmic rays (CRs) accelerated in supernova remnant (SNR) shocks are though to produce significant magnetic field amplification (a factor of 100 in their downstream medium). This amplification is believed to be caused by plasma instabilities driven by CRs as they stream in front of the shocks. Using particle-in-cell plasma simulations, we investigate possible instabilities, considering arbitrary angles between the CR streaming and the magnetic field. In the limit of quasi-parallel propagation, we recover Bell's cosmic ray current-driven (CRCD) instability. In the quasi-perpendicular case we find a new instability, the perpendicular current-driven (PCD) instability, and elucidate its physical nature. The PCD instability is driven by CRs protruding into regions of pre-amplified transverse field, which is likely to occur near the shocks. We study the expected saturation mechanisms of these instabilities for the case of SNR shocks. We find that the maximum amplification factor of the PCD instability is 50 in the upstream medium of the shocks, which is 5 times larger than the one corresponding to the CRCD instability. This result shows that CR-driven instabilities would play an essential role in the magnetic amplification inferred from SNR shock observations.

  12. The Fate of the Compact Remnant in Neutron Star Mergers

    SciTech Connect

    Fryer, Chris L; Belczynski, Krzysztoff; Ramirez-Ruiz, Enrico; Rosswog, Stephan; Shen, Gang

    2015-01-01

    Neutron star (binary neutron star and neutron star - black hole) mergers are believed to produce short-duration gamma-ray bursts. They are also believed to be the dominant source of gravitational waves to be detected by the advanced LIGO and the dominant source of the heavy r-process elements in the universe. Whether or not these mergers produce short-duration GRBs depends sensitively on the fate of the core of the remnant (whether, and how quickly, it forms a black hole). In this paper, we combine the results of merger calculations and equation of state studies to determine the fate of the cores of neutron star mergers. Using population studies, we can determine the distribution of these fates to compare to observations. We find that black hole cores form quickly only for equations of state that predict maximum non-rotating neutron star masses below 2.3-2.4 solar masses. If quick black hole formation is essential in producing gamma-ray bursts, LIGO observed rates compared to GRB rates could be used to constrain the equation of state for dense nuclear matter.

  13. WHAM Observations of High-latitude Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Orchard, Alexander; Haffner, L. Matthew; Benjamin, Robert A.; Gostisha, Martin

    2016-01-01

    The Wisconsin H-Alpha Mapper Sky Survey (WHAM-SS) traces numerous large-angle, diffuse regions containing filamentary and shell-like structures. The largest of these are complex supershells that harbor recent and on-going star formation, such as the Orion-Eridanus complex, the Gum Nebula, and the extended emission above and below the W3/W4/W5 star-forming regions in the Perseus Arm. Several large-diameter regions with simpler morphologies are also present, which we focus on here. While some of these structures are diffuse H II regions powered by nearby, isolated stars, others are clearly supernova remnants (SNRs) due to their association with X-ray or non-thermal radio emission. We highlight the structure, kinematics, and multi-wavelength properties of several SNRs using Hα maps from the WHAM-SS and data from on-going WHAM multi-wavelength surveys. WHAM research and operations are supported through NSF Award AST-1108911.

  14. The Fate of the Compact Remnant in Neutron Star Mergers

    SciTech Connect

    Fryer, Chris L.; Belczynski, Krzysztoff; Ramirez-Ruiz, Enrico; Rosswog, Stephan; Shen, Gang; Steiner, Andrew W.

    2015-10-06

    Neutron star (binary neutron star and neutron star - black hole) mergers are believed to produce short-duration gamma-ray bursts. They are also believed to be the dominant source of gravitational waves to be detected by the advanced LIGO and the dominant source of the heavy r-process elements in the universe. Whether or not these mergers produce short-duration GRBs depends sensitively on the fate of the core of the remnant (whether, and how quickly, it forms a black hole). In this paper, we combine the results of merger calculations and equation of state studies to determine the fate of the cores of neutron star mergers. Using population studies, we can determine the distribution of these fates to compare to observations. We find that black hole cores form quickly only for equations of state that predict maximum non-rotating neutron star masses below 2.3-2.4 solar masses. If quick black hole formation is essential in producing gamma-ray bursts, LIGO observed rates compared to GRB rates could be used to constrain the equation of state for dense nuclear matter.

  15. The Fate of the Compact Remnant in Neutron Star Mergers

    DOE PAGESBeta

    Fryer, Chris L.; Belczynski, Krzysztoff; Ramirez-Ruiz, Enrico; Rosswog, Stephan; Shen, Gang; Steiner, Andrew W.

    2015-10-06

    Neutron star (binary neutron star and neutron star - black hole) mergers are believed to produce short-duration gamma-ray bursts. They are also believed to be the dominant source of gravitational waves to be detected by the advanced LIGO and the dominant source of the heavy r-process elements in the universe. Whether or not these mergers produce short-duration GRBs depends sensitively on the fate of the core of the remnant (whether, and how quickly, it forms a black hole). In this paper, we combine the results of merger calculations and equation of state studies to determine the fate of the coresmore » of neutron star mergers. Using population studies, we can determine the distribution of these fates to compare to observations. We find that black hole cores form quickly only for equations of state that predict maximum non-rotating neutron star masses below 2.3-2.4 solar masses. If quick black hole formation is essential in producing gamma-ray bursts, LIGO observed rates compared to GRB rates could be used to constrain the equation of state for dense nuclear matter.« less

  16. Pulsar Wind Nebulae, Space Velocities and Supernova Remnant

    NASA Technical Reports Server (NTRS)

    2005-01-01

    The original proposal for this LTSA grant was for X-ray studies of pulsars, and especially pulsar wind nebulae and what they could tell us about pulsar properties, especially their space velocities. By any metric, this program has been very successful. No fewer than 14 papers on directly related topics (and several dozen more on related topics) have been published in refereed journals with the PI as lead or co-author, all observational results that have had significant impact on the field. These include the first X-ray detection of the "Duck" pulsar, a clear demonstration that estimated pulsar ages can be off by over an order of magnitude (via observations of the young supernova remnant G11.2-0.3) and the detection of the first pulsar wind nebula around a millisecond pulsar. These publications have also resulted in 4 press releases. Moreover, they also represent the thesis work of two PhD students at MIT (Froney Crawford and Mike Pivovaroff) and one postdoctoral fellow, Bryan Gaensler, now Assistant Professor at Harvard.

  17. Search for surviving companions in type Ia supernova remnants

    SciTech Connect

    Pan, Kuo-Chuan; Ricker, Paul M.; Taam, Ronald E. E-mail: pmricker@illinois.edu E-mail: taam@asiaa.sinica.edu.tw

    2014-09-01

    The nature of the progenitor systems of type Ia supernovae (SNe Ia) is still unclear. One way to distinguish between the single-degenerate scenario and double-degenerate scenario for their progenitors is to search for the surviving companions (SCs). Using a technique that couples the results from multi-dimensional hydrodynamics simulations with calculations of the structure and evolution of main-sequence- (MS-) and helium-rich SCs, the color and magnitude of MS- and helium-rich SCs are predicted as functions of time. The SC candidates in Galactic type Ia supernova remnants (Ia SNR) and nearby extragalactic Ia SNRs are discussed. We find that the maximum detectable distance of MS SCs (helium-rich SCs) is 0.6-4 Mpc (0.4-16 Mpc), if the apparent magnitude limit is 27 in the absence of extinction, suggesting that the Large and Small Magellanic Clouds and the Andromeda Galaxy are excellent environments in which to search for SCs. However, only five Ia SNRs have been searched for SCs, showing little support for the standard channels in the singe-degenerate scenario. To better understand the progenitors of SNe Ia, we encourage the search for SCs in other nearby Ia SNRs.

  18. Asymmetric velocity anisotropies in remnants of collisionless mergers

    SciTech Connect

    Sparre, Martin; Hansen, Steen H. E-mail: hansen@dark-cosmology.dk

    2012-07-01

    Dark matter haloes in cosmological N-body simulations are affected by processes such as mergers, accretion and the gravitational interaction with baryonic matter. Typically the analysis of dark matter haloes is performed in spherical or elliptical bins and the velocity distributions are often assumed to be constant within those bins. However, the velocity anisotropy, which describes differences between the radial and tangential velocity dispersion, has recently been show to have a strong dependence on direction in the triaxial halos formed in cosmological simulations. In this study we derive properties of particles in cones parallel or perpendicular to the collision axis of merger remnants. We find that the velocity anisotropy has a strong dependence on direction. The finding that the direction-dependence of the velocity anisotropy of a halo depends on the merger history, explains the existence of such trends in cosmological simulations. It also explains why a large diversity is seen in the velocity anisotropy profiles in the outer parts of high-resolution simulations of cosmological haloes.

  19. Non-cosmological FRBs from young supernova remnant pulsars

    NASA Astrophysics Data System (ADS)

    Connor, Liam; Sievers, Jonathan; Pen, Ue-Li

    2016-05-01

    We propose a new extra but non-cosmological explanation for fast radio bursts (FRBs) based on very young pulsars in supernova remnants. Within a few hundred years of a core-collapse supernova, the ejecta is confined within ˜1 pc, providing a high enough column density of free electrons for the observed 375-1600 pc cm-3 of dispersion measure (DM). By extrapolating a Crab-like pulsar to its infancy in an environment like that of SN 1987A, we hypothesize such an object could emit supergiant pulses sporadically which would be bright enough to be seen at a few hundred megaparsecs. We hypothesize that such supergiant pulses would preferentially occur early in the pulsar's life when the free electron density is still high, which is why we do not see large numbers of moderate DM FRBs (≲300 pc cm-3). In this scenario, Faraday rotation at the source gives rotation measures (RMs) much larger than the expected cosmological contribution. If the emission were pulsar-like, then the polarization vector could swing over the duration of the burst, which is not expected from non-rotating objects. In this model, the scattering, large DM, and commensurate RM all come from one place which is not the case for the cosmological interpretation. The model also provides testable predictions of the flux distribution and repeat rate of FRBs, and could be furthermore verified by spatial coincidence with optical supernovae of the past several decades and cross-correlation with nearby galaxy maps.

  20. SUPERNOVA REMNANTS AND STAR FORMATION IN THE LARGE MAGELLANIC CLOUD

    SciTech Connect

    Desai, Karna M.; Chu, You-Hua; Gruendl, Robert A.; Dluger, William; Katz, Marshall; Wong, Tony; Looney, Leslie W.; Chen, C.-H. Rosie; Hughes, Annie; Muller, Erik; Ott, Juergen; Pineda, Jorge L.

    2010-08-15

    It has often been suggested that supernova remnants (SNRs) can trigger star formation. To investigate the relationship between SNRs and star formation, we have examined the known sample of 45 SNRs in the Large Magellanic Cloud (LMC) to search for associated young stellar objects (YSOs) and molecular clouds. We find seven SNRs associated with both YSOs and molecular clouds, three SNRs associated with YSOs but not molecular clouds, and eight SNRs near molecular clouds but not associated with YSOs. Among the 10 SNRs associated with YSOs, the association between the YSOs and SNRs either can be rejected or cannot be convincingly established for eight cases. Only two SNRs have YSOs closely aligned along their rims; however, the time elapsed since the SNR began to interact with the YSOs' natal clouds is much shorter than the contraction timescales of the YSOs, and thus we do not see any evidence of SNR-triggered star formation in the LMC. The 15 SNRs that are near molecular clouds may trigger star formation in the future when the SNR shocks have slowed down to <45 km s{sup -1}. We discuss how SNRs can alter the physical properties and abundances of YSOs.

  1. Acceleration of cosmic rays in supernova-remnants

    NASA Technical Reports Server (NTRS)

    Dorfi, E. A.; Drury, L. O.

    1985-01-01

    It is commonly accepted that supernova-explosions are the dominant source of cosmic rays up to an energy of 10 to the 14th power eV/nucleon. Moreover, these high energy particles provide a major contribution to the energy density of the interstellar medium (ISM) and should therefore be included in calculations of interstellar dynamic phenomena. For the following the first order Fermi mechanism in shock waves are considered to be the main acceleration mechanism. The influence of this process is twofold; first, if the process is efficient (and in fact this is the cas) it will modify the dynamics and evolution of a supernova-remnant (SNR), and secondly, the existence of a significant high energy component changes the overall picture of the ISM. The complexity of the underlying physics prevented detailed investigations of the full non-linear selfconsistent problem. For example, in the context of the energy balance of the ISM it has not been investigated how much energy of a SN-explosion can be transfered to cosmic rays in a time-dependent selfconsistent model. Nevertheless, a lot of progress was made on many aspects of the acceleration mechanism.

  2. Expectation on Observation of Supernova Remnants with the LHAASO Project

    NASA Astrophysics Data System (ADS)

    Liu, Ye; Cao, Zhen; Chen, Songzhan; Chen, Yang; Cui, Shuwang; He, Huihai; Huang, Xingtao; Ma, Xinhua; Yuan, Qiang; Zhang, Xiao; LHAASO Collaboration

    2016-07-01

    Supernova remnants (SNRs) are believed to be the most important acceleration sites for cosmic rays (CRs) below ∼1015 eV in the Galaxy. High-energy photons, either directly from the shocks of the SNRs or indirectly from the interaction between SNRs and the nearby clouds, are crucial probes for the CR acceleration. Big progresses on observations of SNRs have been achieved by space- and ground-based γ-ray facilities. However, whether γ-rays come from accelerated hadrons or not, as well as their connection with the CRs observed at Earth, remains in debate. Large High Altitude Air Shower Observatory (LHAASO), a next-generation experiment, is designed to survey the northern part of the very high energy γ-ray sky from ∼0.3 TeV to PeV with the sensitivity of ≲1% of the Crab Nebula flux. In this paper, we indicate that LHAASO will be dedicated to enlarging the γ-ray SNR samples and improving the spectral and morphological measurements. These measurements, especially at energies above 30 TeV, will be important for us to finally understand the CR acceleration in SNRs.

  3. A NEW EVOLUTIONARY PHASE OF SUPERNOVA REMNANT 1987A

    SciTech Connect

    Park, Sangwook; Zhekov, Svetozar A.; Burrows, David N.; Racusin, Judith L.; McCray, Richard

    2011-06-01

    We have been monitoring the supernova remnant (SNR) 1987A with Chandra observations since 1999. Here we report on the latest change in the soft X-ray light curve of SNR 1987A. For the last {approx}1.5 yr (since day {approx}8000), the soft X-ray flux has significantly flattened, staying (within uncertainties) at f{sub X} {approx} 5.7 x 10{sup -12} erg cm{sup -2} s{sup -1} (corresponding to L{sub X} {approx} 3.6 x 10{sup 36} erg s{sup -1}) in the 0.5-2 keV band. This remarkable change in the recent soft X-ray light curve suggests that the forward shock is now interacting with a decreasing density structure, after interacting with an increasing density gradient over {approx}10 yr prior to day {approx}8000. Possibilities may include the case that the shock is now propagating beyond a density peak of the inner ring. We briefly discuss some possible implications on the nature of the progenitor and the future prospects of our Chandra monitoring observations.

  4. Eocene Tibetan plateau remnants preserved in the northwest Himalaya

    NASA Astrophysics Data System (ADS)

    van der Beek, Peter; van Melle, Jérémie; Guillot, Stéphane; Pêcher, Arnaud; Reiners, Peter W.; Nicolescu, Stefan; Latif, Mohammad

    2009-05-01

    The northwest Himalaya shows strongly contrasting relief. Deeply incised mountain ranges that are characterized by extremely rapid exhumation and some of the highest peaks in the world are in contrast with high-elevation, low-relief areas such as the Deosai plateau in northern Pakistan, which lies at an altitude of 4,000m. The origin and evolution of such plateau regions at the convergence of the most active continental collision in the world remain elusive. Here we report low-temperature thermochronology data from the Deosai plateau and use thermal history modelling to show that the plateau has undergone continuous slow denudation at rates below 250mMyr-1 for the past 35Myr at least. This finding suggests tectonic and morphologic stability of the plateau since at least Eocene times, only 15-20Myr after the onset of the India-Asia collision. Our work contradicts the hypothesis that widespread low-relief surfaces in the northwest Himalaya result from efficient kilometre-scale glacial erosion during Quaternary times. We show that similarly stable surfaces exist throughout the entire northwest Himalaya and share common morphologic characteristics and denudation histories, which are comparable to those of the western Tibetan plateau. Our results suggest that these surfaces are preserved remnants of an Eocene southwestern Tibetan plateau that was more extensive than today.

  5. Cosmic ray acceleration at perpendicular shocks in supernova remnants

    SciTech Connect

    Ferrand, Gilles; Danos, Rebecca J.; Shalchi, Andreas; Safi-Harb, Samar; Edmon, Paul; Mendygral, Peter

    2014-09-10

    Supernova remnants (SNRs) are believed to accelerate particles up to high energies through the mechanism of diffusive shock acceleration (DSA). Except for direct plasma simulations, all modeling efforts must rely on a given form of the diffusion coefficient, a key parameter that embodies the interactions of energetic charged particles with magnetic turbulence. The so-called Bohm limit is commonly employed. In this paper, we revisit the question of acceleration at perpendicular shocks, by employing a realistic model of perpendicular diffusion. Our coefficient reduces to a power law in momentum for low momenta (of index α), but becomes independent of the particle momentum at high momenta (reaching a constant value κ{sub ∞} above some characteristic momentum p {sub c}). We first provide simple analytical expressions of the maximum momentum that can be reached at a given time with this coefficient. Then we perform time-dependent numerical simulations to investigate the shape of the particle distribution that can be obtained when the particle pressure back-reacts on the flow. We observe that for a given index α and injection level, the shock modifications are similar for different possible values of p {sub c}, whereas the particle spectra differ markedly. Of particular interest, low values of p {sub c} tend to remove the concavity once thought to be typical of non-linear DSA, and result in steep spectra, as required by recent high-energy observations of Galactic SNRs.

  6. Fermi-LAT Observation of Supernova Remnant S147

    SciTech Connect

    Katsuta, J.; Uchiyama, Y.; Tanaka, T.; Tajima, H.; Bechtol, K.; Funk, S.; Lande, J.; Ballet, J.; Hanabata, Y.; Lemoine-Goumard, M.; Takahashi, T.; /JAXA, Sagamihara

    2012-08-17

    We present an analysis of gamma-ray data obtained with the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope in the region around SNR S147 (G180.0-1.7). A spatially extended gamma-ray source detected in an energy range of 0.2-10 GeV is found to coincide with SNR S147. We confirm its spatial extension at >5{sigma} confidence level. The gamma-ray flux is (3.8 {+-} 0.6) x 10{sup -8} photons cm{sup -2} s{sup -1}, corresponding to a luminosity of 1.3 x 10{sup 34} (d/1.3 kpc){sup 2} erg s{sup -1} in this energy range. The gamma-ray emission exhibits a possible spatial correlation with prominent H{alpha} filaments of S147. There is no indication that the gamma-ray emission comes from the associated pulsar PSR J0538+2817. The gamma-ray spectrum integrated over the remnant is likely dominated by the decay of neutral {pi} mesons produced through the proton-proton collisions in the filaments. Reacceleration of pre-existing CRs and subsequent adiabatic compression in the filaments is sufficient to provide the required energy density of high-energy protons.

  7. Sub-Lyman-alpha observations of supernova remnants

    NASA Technical Reports Server (NTRS)

    Long, K. S.

    1993-01-01

    The first map of O VI lambda 1035 emission of the Cygnus Loop has now been obtained with Voyager. The first good spectra of the sub-Lyman-alpha region in the Cygnus Loop and in the Large Magellanic Cloud (LMC) remnant N49 have been obtained with the Hopkins Ultraviolet Telescope. The lines detected below 1200 A include S VI lambda lambda 933,945, C III lambda 977, N III lambda 991, and O VI lambda lambda 1032,1038. The O VI luminosities of the Cygnus Loop and of N49 exceed their soft X-ray luminosities. There is O VI emission at the primary shock front in the Cygnus Loop and from the bright optical filaments. The HUT spectra of the Cygnus Loop can be interpreted in terms of shocks with velocities of 170-190 km/s; the differences between the two spectra are due to the time since the beginning of the shock-cloud encounter.

  8. IS THERE A HIDDEN HOLE IN TYPE Ia SUPERNOVA REMNANTS?

    SciTech Connect

    Garcia-Senz, D.; Badenes, C.; Serichol, N. E-mail: carles@astro.tau.ac.il

    2012-01-20

    In this paper, we report on the bulk features of the hole carved by the companion star in the material ejected during a Type Ia supernova (SN Ia) explosion. In particular we are interested in the long-term evolution of the hole as well as in its fingerprint in the geometry of the supernova remnant (SNR) after several centuries of evolution, which is a hot topic in current SN Ia studies. We use an axisymmetric smoothed particle hydrodynamics code to characterize the geometric properties of the SNR resulting from the interaction of this ejected material with the ambient medium. Our aim is to use SNR observations to constrain the single degenerate scenario for SN Ia progenitors. Our simulations show that the hole will remain open during centuries, although its partial or total closure at later times due to hydrodynamic instabilities is not excluded. Close to the edge of the hole, the Rayleigh-Taylor instability grows faster, leading to plumes that approach the edge of the forward shock. We also discuss other geometrical properties of the simulations, like the evolution of the contact discontinuity.

  9. A XMM Survey for Compact Objects in Supernova Remnants

    NASA Technical Reports Server (NTRS)

    Kulkarni, Shrinivas R.

    2004-01-01

    The goal of the project is to identify candidate neutron stars in Galactic supernova remnants (SNRs) through their X-ray emission. With XMM we observed the SNRs and typically find 10 - 50 X-ray sources. Almost all are either background galaxies or foreground stars. Therefore we must also pursue detailed optical/infrared follow-up observations to find counterparts for these X-ray sources and classify them. At the depth of the XMM observations, practically all confusing X-ray sources should have identifiable optical/IR counterparts. We have done a preliminary analysis of the XMM data and identified likely counterparts to the X-ray sources from available surveys(DSS, 2MASS). We then obtained wide-field optical/IR data from Palomar to get counterparts for the remaining sources. This analysis is underway: while often a single bright source is in the XMM error circle and can be considered a counterpart, in a number of cases we must do more detailed studies and evaluate several fainter optical/lR sources. We hope to have the final analysis of the XMM + Palomar data done this Fall. It is possible that additional, deeper optical/IR data may be necessary. We expect to publish our results by the end of this year.

  10. The likely Fermi detection of the supernova remnant RCW 103

    SciTech Connect

    Xing, Yi; Wang, Zhongxiang; Zhang, Xiao; Chen, Yang

    2014-02-01

    We report on the results from our γ-ray analysis of the supernova remnant (SNR) RCW 103 region. The data were taken with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. An extended source is found at a position consistent with that of RCW 103 and its emission was only detected above 1 GeV (10σ significance), with a power-law spectrum with a photon index of 2.0 ± 0.1. We obtain its 1-300 GeV spectrum and the total flux gives a luminosity of 8.3 × 10{sup 33} erg s{sup –1} at a source distance of 3.3 kpc. Given the positional coincidence and property similarities of this source with other SNRs, we identify it as the likely Fermi γ-ray counterpart to RCW 103. Including radio measurements of RCW 103, the spectral energy distribution (SED) is modeled by considering emission mechanisms based on both hadronic and leptonic scenarios. We find that models in the two scenarios can reproduce the observed SED, while in the hadronic scenario the existence of SNR-molecular cloud interactions is suggested as a high density of the target protons is required.

  11. A Newly Recognized Very Young Supernova Remnant in M83

    NASA Astrophysics Data System (ADS)

    Blair, William P.; Winkler, P. Frank; Long, Knox S.; Whitmore, Bradley C.; Kim, Hwihyun; Soria, Roberto; Kuntz, K. D.; Plucinsky, Paul P.; Dopita, Michael A.; Stockdale, Christopher

    2015-01-01

    As part of a spectroscopic survey of supernova remnant candidates in M83 using the Gemini-South telescope and GMOS, we have discovered one object whose spectrum shows very broad lines at Halpha, [O I] 6300, and [O III] 5007, similar to those from other objects classified as `late time supernovae.' Although six historical supernovae have been observed in M83 since 1923, none were seen at the location of this object. Hubble Space Telescope Wide Field Camera 3 images show a nearly unresolved emission source, while Chandra and ATCA data reveal a bright X-ray source and nonthermal radio source at the position. Objects in other galaxies showing similar spectra are only decades post-supernova, which raises the possibility that the supernova that created this object occurred during the last century but was not observed. Using photometry of nearby stars from the HST data, we suggest the precursor was at least 17 M(sun), and the presence of broad Halpha in the spectrum makes a type II supernova likely. The supernova must predate the 1983 VLA radio detection of the object. We suggest examination of archival images of M83 to search for evidence of the supernova event that gave rise to this object, and thus provide a precise time since the explosion.We acknowledge STScI grants under the umbrella program ID GO-12513 to Johns Hopkins University, STScI, and Middlebury College. PFW acknowledges additional support from the National Science Foundation through grant AST-0908566.

  12. Thyroglossal Duct Remnant with Follicular Hyperplasia Presenting After Total Thyroidectomy

    PubMed Central

    Nelson, Ryan E.; Ahmad, Hassan; Hildrew, Douglas M.; Lawlor, Claire M.; Aslam, Rizwan; Sholl, Andrew; Kandil, Emad

    2016-01-01

    Background: The thyroglossal duct fails to involute in up to 7% of adults, creating a thyroglossal duct remnant (TGDR) attached to the hyoid bone. Thyroid malignancies have been reported in approximately 1% of TGDRs. In previous reports of TGDR carcinoma, patients had radiographic evidence of a TGDR at initial clinical presentation. Alternatively, hypertrophy of a TGDR is well described in patients with hypothyroidism because of the growth of functional ectopic thyroid tissue. We present the case of a patient who had no radiographic evidence of a TGDR prior to thyroidectomy but presented 14 months after surgery with a recurrent cervical mass. Case Report: A 58-year-old female underwent total thyroidectomy for micropapillary thyroid cancer. Fourteen months later, she presented with an enlarging cervical mass. She underwent a Sistrunk procedure, and surgical pathology revealed a TGDR with compensatory glandular hypertrophy. Conclusion: To our knowledge, this is the first report of a TGDR follicular adenoma initially appearing as a result of compensatory thyroid glandular hypertrophy following total thyroidectomy for a micropapillary thyroid carcinoma. Our case presented a novel clinical dilemma regarding the best management for a patient with a new TGDR along with a recent history of micropapillary thyroid cancer. PMID:27303226

  13. Search for Surviving Companions in Type Ia Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Pan, Kuo-Chuan; Ricker, Paul M.; Taam, Ronald E.

    2014-09-01

    The nature of the progenitor systems of type Ia supernovae (SNe Ia) is still unclear. One way to distinguish between the single-degenerate scenario and double-degenerate scenario for their progenitors is to search for the surviving companions (SCs). Using a technique that couples the results from multi-dimensional hydrodynamics simulations with calculations of the structure and evolution of main-sequence- (MS-) and helium-rich SCs, the color and magnitude of MS- and helium-rich SCs are predicted as functions of time. The SC candidates in Galactic type Ia supernova remnants (Ia SNR) and nearby extragalactic Ia SNRs are discussed. We find that the maximum detectable distance of MS SCs (helium-rich SCs) is 0.6-4 Mpc (0.4-16 Mpc), if the apparent magnitude limit is 27 in the absence of extinction, suggesting that the Large and Small Magellanic Clouds and the Andromeda Galaxy are excellent environments in which to search for SCs. However, only five Ia SNRs have been searched for SCs, showing little support for the standard channels in the singe-degenerate scenario. To better understand the progenitors of SNe Ia, we encourage the search for SCs in other nearby Ia SNRs.

  14. Pair of bollards and remnant seawall of Pan American Airways/Naval ...

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

    Pair of bollards and remnant seawall of Pan American Airways/Naval Air Transport Service/destroyer base site. View facing north. - U.S. Naval Base, Pearl Harbor, Pearl City Peninsula, Pearl City, Honolulu County, HI

  15. Two-temperature models of old supernova remnants with ion and electron thermal conduction

    NASA Technical Reports Server (NTRS)

    Cui, Wei; Cox, Donald P.

    1992-01-01

    To investigate the potential effects thermal conduction may have on the evolution of old supernova remnants, we present the results of 1D (spherically symmetric) numerical simulations of a remnant in a homogeneous interstellar medium for four different cases: (1) without thermal conduction; (2) with both electron and ion thermal conduction assuming equal temperatures; (3) with electron thermal conduction only, following electron and ion temperatures separately; and (4) with both electron and ion thermal conduction following separate temperatures. We followed the entire evolution until the completion of the remnant bubble collapse. Our most significant result is that in remnant evolution studies concerned principally with either the shell or bubble evolution at late times, reasonable results are obtained with single-temperature models. When the electron and ion temperatures are followed separately, however, ion thermal conduction cannot safely be ignored.

  16. Radio emission from young supernova remnants - Effects of an inhomogeneous circumstellar medium

    NASA Technical Reports Server (NTRS)

    Dickel, John R.; Eilek, Jean A.; Jones, Eric M.; Reynolds, Stephen P.

    1989-01-01

    The evolution of young supernova remnants has been modeled using a one-dimensional hydrodynamics code. Rayleigh-Taylor instabilities and the growth of Rayleigh-Taylor fingers have been included in the code. Turbulent dynamo amplification of magnetic fields and both turbulent and shock acceleration of relativistic electrons have been included macroscopically. From this, the distribution of synchrotron luminosity in the remnant has been calculated. It is found that the radio morphology of model remnants expanding into a homogeneous medium does not agree with observations. Expansion into a circumstellar medium with many small cloudlets does produce radio shells which agree with observations. It is suggested that supernova remnants reflect the interaction of ejected matter with a cloudy circumstellar medium.

  17. Satellite Sees Remnants from Hurricane Patricia Affecting Southern U.S.

    NASA Video Gallery

    This 21 second animation of infrared and visible imagery from NOAA's GOES-East satellite from Oct. 24-26 shows the remnants of Hurricane Patricia move through the Gulf of Mexico and Gulf Coast Stat...

  18. SUPERNOVA REMNANT KES 17: AN EFFICIENT COSMIC RAY ACCELERATOR INSIDE A MOLECULAR CLOUD

    SciTech Connect

    Gelfand, Joseph D.; Castro, Daniel; Slane, Patrick O.; Temim, Tea; Hughes, John P.; Rakowski, Cara E-mail: cara.rakowski@gmail.com

    2013-11-10

    The supernova remnant Kes 17 (SNR G304.6+0.1) is one of a few but growing number of remnants detected across the electromagnetic spectrum. In this paper, we analyze recent radio, X-ray, and γ-ray observations of this object, determining that efficient cosmic ray acceleration is required to explain its broadband non-thermal spectrum. These observations also suggest that Kes 17 is expanding inside a molecular cloud, though our determination of its age depends on whether thermal conduction or clump evaporation is primarily responsible for its center-filled thermal X-ray morphology. Evidence for efficient cosmic ray acceleration in Kes 17 supports recent theoretical work concluding that the strong magnetic field, turbulence, and clumpy nature of molecular clouds enhance cosmic ray production in supernova remnants. While additional observations are needed to confirm this interpretation, further study of Kes 17 is important for understanding how cosmic rays are accelerated in supernova remnants.

  19. Spatial Diagnostics of Potential X-ray Remnants in Old Novae T Aur and DK Lac

    NASA Astrophysics Data System (ADS)

    Drake, Jeremy

    2013-09-01

    We propose 5 and 3 ks ACIS-S snapshots of potentially extended X-ray remnants of two old classical novae, T Aur and DK Lac. They are the likely counterparts of X-ray sources discovered in our Swift survey of old classical novae, and each target has a spatially-resolved optical remnant with a size of order arcseconds. The additional short Chandra snapshots will confirm or reject the tentative Swift identifications through pinpoint astrometry, and will distinguish between extended remnant emission or rejuvenated accretion. Both are important for understanding binary evolution and also potential post-outburst hibernation, while detection of extended emission will represent extremely rare additions to the exclusive club of X-ray emitting classical nova remnants.

  20. Endocytic mechanisms for uptake and metabolism of chylomicron remnants in the liver.

    PubMed

    Windler, E; Greeve, J; Jäckle, S; Rinninger, F; Pox, C; Puchta, D; Petkova, D; Robenek, H; Daerr, W; Greten, H

    1996-06-01

    Removal of small chylomicron remnants by perfused rat livers closely correlates with the LDL-receptor mRNA modulated by various interventions. In contrast, removal of remnants of large chylomicrons is not appreciably influenced by the activity of the hepatic LDL-receptor. Their primary removal depends on a heparinase-sensitive binding site. Transient and stable transfection of the cDNAs of the two subunits of the human asialoglycoprotein receptor markedly increased the binding capacity for chylomicron remnants suggesting the asialoglycoprotein receptor to be an alternative mechanism for remnant removal. Some species can edit apolipoprotein B-100 mRNA and thus secret apolipoprotein B-48 containing lipoproteins of hepatic origin. Generally these animals have lower cholesterol levels and a more favorable lipoprotein profile. PMID:8767479

  1. The Golden Ratio

    ERIC Educational Resources Information Center

    Hyde, Hartley

    2004-01-01

    The Golden Ratio is sometimes called the "Golden Section" or the "Divine Proportion", in which three points: A, B, and C, divide a line in this proportion if AC/AB = AB/BC. "Donald in Mathmagicland" includes a section about the Golden Ratio and the ratios within a five-pointed star or pentagram. This article presents two computing exercises that…

  2. Magnetic resonance imaging and laparoscopic management of an ovarian remnant in a bitch.

    PubMed

    Krauss, Z; Krauss, M

    2015-01-01

    Ovarian remnant tissue was diagnosed in a 6-year-old female Pointer presented with a history of periodic signs of oestrus after ovariohysterectomy. The diagnosis was based on clinical gynaecological examination, vaginoscopy, vaginal cytology, analysis of serum progesterone concentration, and magnetic resonance imaging. The ovarian remnant tissue was approached in a minimally invasive manner via laparoscopy and resected with a vessel-sealing system. The oestrus signs disappeared within 14 days after laparoscopy. PMID:25771839

  3. Using Poisson statistics to analyze supernova remnant emission in the low counts X-ray regime

    NASA Astrophysics Data System (ADS)

    Roper, Quentin Jeffrey

    We utilize a Poisson likelihood in a maximum likelihood statistical analysis to analyze X-ray spectragraphic data. Specifically, we examine four extragalactic supernova remnants (SNR). IKT 5 (SNR 0047-73.5), IKT 25 (SNR 0104-72.3), and DEM S 128 (SNR 0103-72.4) which are designated as Type Ia in the literature due to their spectra and morphology. This is troublesome because of their asymmetry, a trait not usually associated with young Type Ia remnants. We present Chandra X-ray Observatory data on these three remnants, and perform a maximum likelihood analysis on their spectra. We find that the X-ray emission is dominated by interactions with the interstellar medium. In spite of this, we find a significant Fe overabundance in all three remnants. Through examination of radio, optical, and infrared data, we conclude that these three remnants are likely not "classical" Type Ia SNR, but may be examples of so-called "prompt" Type Ia SNR. We detect potential point sources that may be members of the progenitor systems of both DEM S 128 and IKT 5, which could suggest a new subclass of prompt Type Ia SNR, Fe-rich CC remnants. In addition, we examine IKT 18. This remnant is positionally coincident with the X-ray point source HD 5980. Due to an outburst in 1994, in which its brightness changed by 3 magnitudes (corrsponding to an increase in luminosity by a factor of 16) HD 5980 was classified as a luminous blue variable star. We examine this point source and the remnant IKT 18 in the X-ray, and find that its non-thermal photon index has decreased from 2002 to 2013, corresponding to a larger proportion of more energetic X-rays, which is unexpected.

  4. Distribution of novae and supernova remnants in the Large Magellanic Cloud

    SciTech Connect

    Van den Bergh, S.

    1988-12-01

    Novae in the LMC appear to be distributred like an old disk population. The fact that no concentration of novae is seen within the Bar of the Large Cloud suggests that this feature is of relatively recent origin. Supernova remnants are seen to exhibit concentrations in the 30 Dor region, in the Bar of the Large Cloud, and in Constellation III. This distribution supports the idea that most of the supernova remnants in the LMC had young massive progenitors. 11 references.

  5. Self-consistent models for the X-ray emission from supernova remnants - An application to Kepler's remnant

    NASA Technical Reports Server (NTRS)

    Hughes, J. P.; Helfand, D. J.

    1985-01-01

    A tool for exploring the evolution of X-ray emission from young SNRs is presented which employs a novel approach to the problem of time-dependent ionization in a shock-heated plasma. The solution of this problem is coupled to a spherically symmetric hydrodynamic calculation for the evolution of a point explosion in a uniform medium. The method is applied to Kepler's SNR, and two narrowly constrained classes of models which can simultaneously fit the spectral and morphological features of the object are found. One of these is a Sedov model in which the emission arises from shocked ambient gas, and the other is a reverse-shock model in which the SN ejecta is the dominant source of radiation. The emission from one specific model in each class is compared with the radial surface brightness profile, the 0.2-4.5 keV broadband spectrum, and the 1-3 keV moderate-resolution spectrum of the remnant. Reasonable fits are obtained in both cases.

  6. Remnant-Preserving Anterior Cruciate Ligament Reconstruction Using a Three-Dimensional Fluoroscopic Navigation System

    PubMed Central

    Inui, Hiroshi; Sanada, Takaki; Nakamura, Kensuke; Yamagami, Ryota; Masuda, Hironari; Tanaka, Sakae; Nakagawa, Takumi

    2014-01-01

    Introduction Recently, remnant-preserving anterior cruciate ligament (ACL) reconstruction has been increasingly performed to achieve revascularization, cell proliferation, and recovery of high-quality proprioception. However, poor arthroscopic visualization makes accurate socket placement during remnant-preserving ACL reconstruction difficult. This study describes a surgical technique used to create an anatomical femoral socket with a three-dimensional (3D) fluoroscopy based navigation system during technically demanding remnant-preserving ACL reconstruction. Surgical Technique After a reference frame was attached to the femur, an intraoperative image of the distal femur was obtained, transferred to the navigation system and reconstructed into a 3D image. A navigation computer helped the surgeon visualize the entire lateral wall of the femoral notch and lateral intercondylar ridge, even when the remnant of the ruptured ACL impeded arthroscopic visualization of the bone surface. When a guide was placed, the virtual femoral tunnel overlapped the reconstructed 3D image in real time; therefore, only minimal soft tissue debridement was required. Materials and Methods We treated 47 patients with remnant-preserving ACL reconstruction using this system. The center of the femoral socket aperture was calculated according to the quadrant technique using 3D computed tomography imaging. Results The femoral socket locations were considered to be an anatomical footprint in accordance with previous cadaveric studies. Conclusions The 3D fluoroscopy-based navigation can assist surgeons in creating anatomical femoral sockets during remnant-preserving ACL reconstruction. PMID:25229047

  7. Chandra Detection of a Pulsar Wind Nebula Associated With Supernova Remnant 3C 396

    NASA Technical Reports Server (NTRS)

    Olbert, C. M.; Keohane, J. W.; Arnaud, K. A.; Dyer, K. K.; Reynolds, S. P.; Safi-Harb, S.

    2003-01-01

    We present a 100 ks observation of the Galactic supernova remnant 3C396 (G39.2-0.3) with the Chandra X-Ray Observatory that we compare to a 20cm map of the remnant from the Very Large Array. In the Chandra images, a nonthermal nebula containing an embedded pointlike source is apparent near the center of the remnant which we interpret as a synchrotron pulsar wind nebula surrounding a yet undetected pulsar. From the 2-10 keV spectrum for the nebula (N(sub H) = 5.3 plus or minus 0.9 x 10(exp 22) per square centimeter, GAMMA =1.5 plus or minus 0.3) we derive an unabsorbed x-ray flux of S(sub z)=1.62 x 10(exp -12) erg per square centimeter per second, and from this we estimate the spin-down power of the neutron star to be E(sup dot) = 7.2 x 10(exp 36) ergs per second. The central nebula is morphologically complex, showing bent, extended structure. The radio and X-ray shells of the remnant correlate poorly on large scales, particularly on the eastern half of the remnant, which appears very faint in X-ray images. At both radio and X-ray wavelengths the western half of the remnant is substantially brighter than the east.

  8. Anterior Cruciate Ligament Remnant-Preserving Reconstruction Using a "Lasso-Loop" Knot Configuration.

    PubMed

    Boutsiadis, Achilleas; Karampalis, Christos; Tzavelas, Anastasios; Vraggalas, Vasileios; Christodoulou, Pavlos; Bisbinas, Ilias

    2015-12-01

    Anterior cruciate ligament (ACL) rupture predisposes to altered kinematics and possible knee joint degeneration. Graft fiber maturation and ligamentization may eliminate this risk during ACL reconstruction procedures. ACL remnant-sparing techniques support the theory that the preserved tissue enhances revascularization, preserves the mechanoreceptors, and leads to anatomic remodeling. The purpose of this article is to present a simple and reproducible technique of tensioning the preserved ACL remnant over the femur. A nonabsorbable suture is passed through the ACL remnant with a "lasso-loop" technique using a curved rotator cuff hook. Femoral and tibial tunnel preparation is performed according to a standard surgical technique for the EndoButton device (Smith & Nephew Endoscopy, Andover, MA). The free ends of the ACL remnant suture are retrieved through the tibial tunnel and passed through each outside hole of the EndoButton device. The hamstring graft is passed through the tibial and femoral tunnels and fixed to the femoral cortex by flipping the EndoButton and to the tibia by an interference screw. Finally, non-sliding half-stitch locking knots are made to secure the ACL remnant suture on the EndoButton device, by use of a knot pusher. This technique offers simple and secure tensioning of the ACL remnant on the fixation device. PMID:26870656

  9. ROSAT PSPC and HRI Observations of Supernova Remnant G292.0+1.8

    NASA Technical Reports Server (NTRS)

    Hughes, John P.

    1999-01-01

    The supernova remnant G292.0+1.8 was observed by the ROSAT PSPC for 18 ksec as part of this grant. Considerable effort was put into the analysis of the PSPC spectra. The major work went into nonequilibrium ionization joint spectral fits with the Einstein SSS and EXOSAT ME data which indicated that the two spatial regions of this remnant (a central bar and a plateau region covering a larger extent) had similar abundances, but different excitation conditions (temperature and ionization state), an important conclusion, if true. Unfortunately as this work was being finished, new ASCA data revealed the presence of a previously unknown, spectrally hard X-ray source near the center of the remnant which contaminated the SSS and ME data and as a consequence made our detailed spectral analysis done up until then un-publishable. We searched for evidence of this hard source in the PSPC data both spectrally and using timing searches (for a pulsar), but found nothing significant. ROSAT HRI data were also obtained on this remnant. These data were compared to the Einstein HRI data to search for evidence of spectral variations with position and possible expansion of the X-ray remnant. One feature in the remnant appears to have changed in brightness although it is not clear what is the cause of the change. No evidence for the hard ASCA source was apparent in the HRI data.

  10. Adiabatic Expansion of Supernova Remnants - an Explicit, Analytical Approximation in Two Dimensions

    NASA Astrophysics Data System (ADS)

    Maciejewski, W.; Shelton, R. L.; Cox, D. P.

    1996-05-01

    We propose a simple, analytical approximation for an adiabatic shock wave propagating in an exponentially stratified ambient medium. We aim to provide an effective tool for exploring the parameter space of 2-dimensional numerical models of supernova remnants (SNRs). We start from Kompaneets's (1960, Soviet Phys. Doklady, 5, 46) axisymmetric generalization of Sedov's spherically symmetric problem, to which he derived an implicit solution. We notice that the SNR shape in his solution can be closely approximated as an ellipsoid. In this case, an explicit solution for the size, eccentricity and expansion velocity of the remnant can be found. Our results are in excellent agreement with Kompaneets's solution, even when the ambient density varies across the remnant by factors as large as 1000. Beyond that, the blowout occurs, and Kompaneets's assumptions no longer hold. The remnant shapes are remarkably close to spherical for moderate density gradients. Using Kahn's cooling law (alpha T(-1/2) ) we derived a formula to estimate how long it takes for a cold shell to form. Even a small gradient in ambient density causes this time to vary substantially within a single remnant, so that for a period the H I shell will be only partially formed. To demonstrate how our approximation can be used, the parameter space for models of the supernova remnant W44 is explored.

  11. Validating the Supernova Remnant Hypothesis of the Cosmic Ray Origin

    NASA Astrophysics Data System (ADS)

    Malkov, Mikhail

    The century-old problem of the origin and acceleration of cosmic rays (CR) could soon be resolved. However, as it is impossible to trace CR back to their accelerators because of orbit scrambling in the galactic magnetic field, the solution will not be easy. Also the direct observations of a secondary gamma emission from supernova remnant (SNR) shocks, long suspected to be the main source of galactic CRs, are complicated by the contaminating electron emission. Therefore, the SNR hypothesis of the CR origin can be proven beyond a reasonable doubt only if the acceleration theory is fully consistent with the observations. However, the complexity of plasma dynamics in SNR shocks makes the validation of the SNR hypothesis very difficult. A study of the crucial plasma processes in SNR shocks is proposed. It will determine the three-way partitioning of the shock energy between accelerated particles (protons and electrons), turbulent magnetic fields and thermal plasma. The project includes a comparative analysis of three instabilities, arguably crucial to the diffusive shock acceleration (DSA) mechanism: i.) the cyclotron resonance CR instability, ii.) the non- resonant CR-current driven (kink-type) instability and iii.) the acoustic CR-pressure gradient driven instability. By identifying the dominant instability depending on the local SNR environment, the spectra of different species of accelerated particles, their losses, and the broadband radiation will be calculated and compared to both direct observations of the secondary emission from major SNRs and to the measurements of the background CRs. The comparison will show whether the DSA mechanism production of CR in SNR is consistent with the observed emission. The remnants most visible in gamma rays expand into weakly ionized, dense gases. The physics of the CR production in such environments based on the three instabilities will be studied. The proposer's previous work has shown that the propagation of CRs in a dense SNR

  12. Nest Predation by Commensal Rodents in Urban Bushland Remnants.

    PubMed

    Smith, Helen M; Dickman, Chris R; Banks, Peter B

    2016-01-01

    Exotic predators are a major threat to native wildlife in many parts of the world. Developing and implementing effective strategies to mitigate their effects requires robust quantitative data so that management can be evidence-based, yet in many ecosystems this is missing. Birds in particular have been severely impacted by exotic mammalian predators, and a plethora of studies on islands record predation of bird eggs, fledglings and adults by exotic species such as rodents, stoats and cats. By comparison, few studies have examined nest predation around mainland urban centres which often act as dispersal hubs, especially for commensal species such as rodents. Here, we experimentally examine nest predation rates in habitat patches with varying black rat (Rattus rattus) densities in Sydney, Australia and test whether these exotic rats have the effects expected of exotic predators using effect size benchmarks. In the case where black rats have replaced native Rattus spp., we expected that black rats, being more arboreal than native Rattus spp., would be a significant source of predation on birds because they can readily access the arboreal niche where many birds nest. We tested this idea using above-ground artificial nests to represent those of typical small bird species such as the New Holland honeyeater (Phylidonyris novaehollandiae). We found that fewer eggs were depredated by rodents on sites where we removed black rats compared to unmanipulated sites, and that the effect size calculated from the total number of eggs surviving beyond the typical incubation period was similar to that expected for an exotic predator. Our results suggest that, although Australian birds have co-evolved with native Rattus species, in the case where black rats have replaced native Rattus species, exotic black rats appear to pose an additive source of predation on birds in remnant habitats, most likely due to their ability to climb more efficiently than their native counterparts

  13. Nest Predation by Commensal Rodents in Urban Bushland Remnants

    PubMed Central

    2016-01-01

    Exotic predators are a major threat to native wildlife in many parts of the world. Developing and implementing effective strategies to mitigate their effects requires robust quantitative data so that management can be evidence-based, yet in many ecosystems this is missing. Birds in particular have been severely impacted by exotic mammalian predators, and a plethora of studies on islands record predation of bird eggs, fledglings and adults by exotic species such as rodents, stoats and cats. By comparison, few studies have examined nest predation around mainland urban centres which often act as dispersal hubs, especially for commensal species such as rodents. Here, we experimentally examine nest predation rates in habitat patches with varying black rat (Rattus rattus) densities in Sydney, Australia and test whether these exotic rats have the effects expected of exotic predators using effect size benchmarks. In the case where black rats have replaced native Rattus spp., we expected that black rats, being more arboreal than native Rattus spp., would be a significant source of predation on birds because they can readily access the arboreal niche where many birds nest. We tested this idea using above-ground artificial nests to represent those of typical small bird species such as the New Holland honeyeater (Phylidonyris novaehollandiae). We found that fewer eggs were depredated by rodents on sites where we removed black rats compared to unmanipulated sites, and that the effect size calculated from the total number of eggs surviving beyond the typical incubation period was similar to that expected for an exotic predator. Our results suggest that, although Australian birds have co-evolved with native Rattus species, in the case where black rats have replaced native Rattus species, exotic black rats appear to pose an additive source of predation on birds in remnant habitats, most likely due to their ability to climb more efficiently than their native counterparts

  14. Modeling of shocks in young and old supernova remnants

    NASA Astrophysics Data System (ADS)

    Patnaude, Daniel James

    We present results from a modeling effort of simple shock phenomena in the Cygnus Loop and Cassiopeia A. Using multi-epoch MDM observations of a small, isolated cloud in the southwest region of the Cygnus Loop, we measure the velocity of the Balmer-dominated shock filaments as well as the velocity of the internal cloud shock. These results are used to constrain the primary parameter for interstellar clouds: the density contrast between the cloud and the interstellar medium. These results are used to present models for a strong shock interacting with a lumpy, but diffuse cloud. This model represents a refinement over previous shock-cloud models. Using multi-epoch X-ray observations of the Cassiopeia A supernova remnant, we investigate a small bow shock which protrudes north of the identified forward shock front. Proper motion estimates for this object, combined with a spectral analysis suggest that the object is a bullet of ejecta, similar to those found in Vela. Model results are presented which show the evolution of an ejecta bullet across the SNR. These simulations suggest that bullet ejecta could arise in Cas A, and that the bullet material could survive the turbulent journey through shocked ejecta. Finally, preliminary results from a study of the reverse shock structure in Cas A are presented. We present regions which show decaying fluxes over a four year period, but also show an increase in X-ray line emission, suggesting that the gas in these regions is approaching ionization equilibrium. Models for reverse shock formation and the reverse shock-ejecta interaction are discussed.

  15. The Impact of a Supernova Remnant on Fast Radio Bursts

    NASA Astrophysics Data System (ADS)

    Piro, Anthony L.

    2016-06-01

    Fast radio bursts (FRBs) are millisecond bursts of radio radiation whose progenitors, so far, remain mysterious. Nevertheless, the timescales and energetics of these events have lead to many theories associating FRBs with young neutron stars (NSs). Motivated by this, I explore the interaction of FRBs with young supernova remnants (SNRs), and I discuss the potential observational consequences and constraints of such a scenario. As the supernova (SN) ejecta plows into the interstellar medium (ISM), a reverse shock is generated that passes back through the material and ionizes it. This leads to a dispersion measure (DM) associated with the SNR as well as a time derivative for DM. The times when DM is high are generally overshadowed by free–free absorption, which, depending on the mass of the ejecta and the density of the ISM, may be probed at frequencies of 400 {{MHz}}–1.4 {{GHz}} on timescales of ∼100–500 years after the SN. Magnetic fields generated at the reverse shock may be high enough to explain Faraday rotation that has been measured for one FRB. If FRBs are powered by the spin energy of a young NS (rather than by magnetic energy), the NS must have a magnetic field ≲ {10}11{--}{10}12 {{G}} to ensure that it does not spin down too quickly while the SNR is still optically thick at radio frequencies. In the future, once there are distance measurements to FRBs and their energetics are better understood, the spin of the NS can also be constrained.

  16. Expression of profibrotic genes in the murine remnant kidney model

    PubMed Central

    Yang, Binxia; Vohra, Pawan; Janardhanan, Rajiv; Misra, Khamal D.; Misra, Sanjay

    2011-01-01

    PURPOSE To test the hypothesis that there is increased expression of several profibrotic genes including matrix metalloproteinase–2 (MMP-2), and -9 (MMP-9), and its inhibitors (TIMP-1 and TIMP-2), a disintegrin and metalloproteinase with thrombospondin motif -1 (ADAMTS-1), and fibroblast specific protein-1 (FSP-1) in a murine remnant kidney (RK) model. MATERIALS AND METHODS CKD was created in ten C57BL/6 male mice (20-25 g) by performing a right nephrectomy and ligation of the upper pole of the left kidney (RK). Animals were sacrificed at 42 and 56 days later. Real time polymerase chain reaction (RT-PCR) for MMP-2, MMP-9, TIMP-1, TIMP-2, ADAMTS-1, and FSP-1 was performed in the RK. Histologic evaluation of the RK was performed using Ki-67, α-smooth muscle cell actin (α-SMA), hematoxylin and eosin, and Masson’s trichrome staining. Kidney function was assessed using serum BUN and creatinine. RESULTS The mean serum BUN and creatinine levels at day 42 and 56 were significantly higher than baseline (P <0 .05). By day 42, the mean expression of MMP-2, MMP-9, TIMP-1, ADAMTS-1, and FSP-1 was significantly higher in the RK when compared to normal kidney (P<0.05) and by day 56, only FSP-1 expression increased significantly higher (P<0.05). There was increased fibrosis by Masson’s trichrome, increased Ki-67, with increased α-SMA staining in the RK when compared to normal kidneys. CONCLUSIONS In the RK, there was increased fibrosis with increased α -SMA and Ki-67 staining with significantly increased expression of MMP-2, MMP-9, TIMP-1, ADAMTS-1, and FSP-1. PMID:22030458

  17. GSH 90-28-17: a possible old supernova remnant

    NASA Astrophysics Data System (ADS)

    Xiao, L.; Zhu, M.

    2014-02-01

    GSH 90-28-17 is a high-latitude Galactic H I supershell, identified in the H I supershell catalogues with a velocity vlsr ˜ -17 km s-1. We used the new Galactic Arecibo L-band Feed Array (GALFA) H I survey data, which have much higher resolution and sensitivity than was previously available, to re-examine the properties of the supershell. We derived a new distance of 400 pc for GSH 90-28-17 and suggested that it is related to the Lac OB1 association. The radius of GSH 90-28-17 is 66.0 ± 3.5 pc. The H I mass of the shell is (3.1 ± 0.1) × 104 M⊙. It has an age of ˜4.5 Myr and a total kinetic energy of (8.2 ± 0.3) × 1048 erg. We extracted radio continuum data for the GSH 90-28-17 region from the 408-MHz All-Sky Survey and Bonn 1420-MHz survey and filtered the diffuse background Galactic emission. A radio loop-like ridge is found to be associated with the H I shell at both frequencies and shows a non-thermal origin, with a temperature-temperature (TT)-plot index of α = -1.35 ± 0.69. In addition, the pulsar J2307+2225, with a similar distance, is found in the shell region. We conclude that GSH 90-28-17 is probably an old, type II supernova remnant in the solar neighbourhood.

  18. The Hubble Heritage Image of the Crab Nebula Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Blair, W. P.; English, J.; Bond, H. E.; Christian, C. A.; Frattare, L.; Hamilton, F.; Levay, Z.; Noll, K. S.

    2000-05-01

    The Hubble Heritage Project has the aim of providing the public with pictorially striking images of celestial objects obtained with NASA's Hubble Space Telescope. Here we present a 5-color Wide Field Planetary Camera 2 (WFPC2) image of the Crab Nebula, a ~950 year old supernova remnant located 6500 light-years distant in the constellation Taurus. The images were obtained in 1995 January and April, and the science investigation reporting results was published by Blair, W. P., et al. (1997, ApJS, 109, 473--480). Over 10 hours of exposure time through 5 separate optical continuum band and emission-line filters were used to study size scales and ionization structures of the filaments and newly synthesized dust within the expanding ejecta. The Heritage version of these data shows several important aspects of the Crab Nebula all in one spectacular image. The continuum image shows stars, including the enigmatic pulsar (the collapsed core of the original star) and the ghostly diffuse synchrotron nebula energized by the pulsar. The synchrotron nebula in turn heats and ionizes the surrounding clumpy filaments of gas and dust visible in the emission line images. These filaments are the supernova ejecta that were expelled during the explosion and are now expanding outward from the pulsar at high speed. The different colors in the picture show optical emission lines of hydrogen (orange), nitrogen (red), sulfur (pink) and oxygen (bluish-green). The subtle changes in color from one filament to the next arise because of varying temperatures and densities of the gas, and variable chemical abundances of the ``star stuff," or the doppler shifting of emission into or out of the various narrow filter bandpasses. Support for this work was provided by NASA through grant numbers GO-07632.01-96A and GO-5354.04-93A from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  19. A Newly Recognized Very Young Supernova Remnant in M83

    NASA Astrophysics Data System (ADS)

    Blair, William P.; Winkler, P. Frank; Long, Knox S.; Whitmore, Bradley C.; Kim, Hwihyun; Soria, Roberto; Kuntz, K. D.; Plucinsky, Paul P.; Dopita, Michael A.; Stockdale, Christopher

    2015-02-01

    As part of a spectroscopic survey of supernova remnant candidates in M83 using the Gemini-South telescope and Gemini Multi-Object Spectrograph, we have discovered one object whose spectrum shows very broad lines at Hα, [O I] λλ6300, 6363, and [O III] λλ4959, 5007, similar to those from other objects classified as "late time supernovae". Although six historical supernovae have been observed in M83 since 1923, none were seen at the location of this object. Hubble Space Telescope (HST) Wide Field Camera 3 images show a nearly unresolved emission source, while Chandra and ATCA data reveal a bright X-ray source and nonthermal radio source at the position. Objects in other galaxies showing similar spectra are only decades post-supernova, which raises the possibility that the supernova that created this object occurred during the last century but was missed. Using photometry of nearby stars from the HST data, we suggest the precursor was at least 17 M ⊙, and the presence of broad Hα in the spectrum makes a type II supernova likely. The supernova must predate the 1983 Very Large Array radio detection of the object. We suggest examination of archival images of M83 to search for evidence of the supernova event that gave rise to this object, and thus provide a precise age. Based on observations made with NASA's Chandra X-Ray Observatory, which is operated by the Smithsonian Astrophysical Observatory under contract # NAS83060, with data obtained through program GO1-12115.

  20. SN 1987A Transforms into SN Remnant 1987A

    NASA Astrophysics Data System (ADS)

    Crotts, Arlin; Heathcote, Stephen; Lawrence, Stephen

    2014-08-01

    The ejecta and circumstellar ring of SN 1987A are colliding violently. Over several years, we have seen radical changes in the circumstellar nebula as it is overrun by high-speed ejecta, giving birth to a supernova remnant (SNR). We have already discovered (and published), via this observational program, new interactions between ejecta and nebula, as several hot spots appearing every year, and see now the whole innermost nebula interacting. This means that observations, especially spectroscopy, of SNR 1987A have entered a new phase in which ground-based observations can reveal the collective behavior of the SNR, especially when combined with HST data. The collision is predicted (and observed) to produce intense IR/optical emission, in new and previously-observed lines. Depending on whether these arise in the ejecta or nebula, and whether shock or EUV-excited, they have linewidths ~10 to 15,000 km/s; frequent moderate- dispersion spectra are required. With the interaction region now enveloping the inner ring, ionizing radiation has started flooding the entire structure. SOAR/Goodman is ideal for this, covering velocity scales, wavelengths and time intervals unavailable to HST, allowing the first ever study of the creation of a nearby SNR. In particular we need timely, good-seeing Goodman spectra of the reverse shock of SN 1987A's circumstellar/ejecta interaction this semester to combine with our scheduled HST/STIS spectra and WFC3 images (in August 2014) and thereby measure of the compositon of deep layers in the SN progenitor star by studying ionic species measurements not seen by HST data alone.

  1. NGC 1252: a high altitude, metal poor open cluster remnant

    NASA Astrophysics Data System (ADS)

    de la Fuente Marcos, R.; de la Fuente Marcos, C.; Moni Bidin, C.; Carraro, G.; Costa, E.

    2013-09-01

    If stars form in clusters but most stars belong to the field, understanding the details of the transition from the former to the latter is imperative to explain the observational properties of the field. Aging open clusters are one of the sources of field stars. The disruption rate of open clusters slows down with age but, as an object gets older, the distinction between the remaining cluster or open cluster remnant (OCR) and the surrounding field becomes less and less obvious. As a result, finding good OCR candidates or confirming the OCR nature of some of the best candidates still remain elusive. One of these objects is NGC 1252, a scattered group of about 20 stars in Horologium. Here we use new wide-field photometry in the UBVI passbands, proper motions from the Yale/San Juan SPM 4.0 catalogue and high-resolution spectroscopy concurrently with results from N-body simulations to decipher NGC 1252's enigmatic character. Spectroscopy shows that most of the brightest stars in the studied area are chemically, kinematically and spatially unrelated to each other. However, after analysing proper motions, we find one relevant kinematic group. This sparse object is relatively close (˜1 kpc), metal poor and is probably not only one of the oldest clusters (3 Gyr) within 1.5 kpc from the Sun but also one of the clusters located farthest from the disc, at an altitude of nearly -900 pc. That makes NGC 1252 the first open cluster that can be truly considered a high Galactic altitude OCR: an unusual object that may hint at a star formation event induced on a high Galactic altitude gas cloud. We also conclude that the variable TW Horologii and the blue straggler candidate HD 20286 are unlikely to be part of NGC 1252. NGC 1252 17 is identified as an unrelated, Population II cannonball star moving at about 400 km s-1.

  2. ASYMMETRY IN THE OBSERVED METAL-RICH EJECTA OF THE GALACTIC TYPE IA SUPERNOVA REMNANT G299.2–2.9

    SciTech Connect

    Post, Seth; Park, Sangwook; Badenes, Carles; Burrows, David N.; Hughes, John P.; Lee, Jae-Joon; Mori, Koji; Slane, Patrick O. E-mail: badenes@pitt.edu E-mail: jph@physics.rutgers.edu E-mail: slane@cfa.harvard.edu

    2014-09-01

    We have performed a deep Chandra observation of the Galactic Type Ia supernova remnant G299.2–2.9. Here we report the initial results from our imaging and spectral analysis. The observed abundance ratios of the central ejecta are in good agreement with those predicted by delayed-detonation Type Ia supernovae models. We reveal inhomogeneous spatial and spectral structures of metal-rich ejecta in G299.2–2.9. The Fe/Si abundance ratio in the northern part of the central ejecta region is higher than that in the southern part. A significant continuous elongation of ejecta material extends out to the western outermost boundary of the remnant. In this western elongation, both the Si and Fe are enriched with a similar abundance ratio to that in the southern part of the central ejecta region. These structured distributions of metal-rich ejecta material suggest that this Type Ia supernova might have undergone a significantly asymmetric explosion and/or has been expanding into a structured medium.

  3. A CR-hydro-NEI model of the structure and broadband emission from Tycho's supernova remnant

    SciTech Connect

    Slane, P.; Patnaude, D. J.; Lee, S.-H.; Nagataki, S.; Ellison, D. C.; Hughes, J. P.; Eriksen, K. A.; Castro, D. E-mail: dpatnaude@cfa.harvard.edu E-mail: shigehiro.nagataki@riken.jp E-mail: jph@physics.rutgers.edu E-mail: castro@mit.edu

    2014-03-01

    Tycho's supernova remnant (SNR) is well-established as a source of particle acceleration to very high energies. Constraints from numerous studies indicate that the observed γ-ray emission results primarily from hadronic processes, providing direct evidence of highly relativistic ions that have been accelerated by the SNR. Here we present an investigation of the dynamical and spectral evolution of Tycho's SNR by carrying out hydrodynamical simulations that include diffusive shock acceleration of particles in the amplified magnetic field at the forward shock of the SNR. Our simulations provide a consistent view of the shock positions, the nonthermal emission, the thermal X-ray emission from the forward shock, and the brightness profiles of the radio and X-ray emission. We compare these with the observed properties of Tycho to determine the density of the ambient material, the particle acceleration efficiency and maximum energy, the accelerated electron-to-proton ratio, and the properties of the shocked gas downstream of the expanding SNR shell. We find that evolution of a typical Type Ia supernova in a low ambient density (n {sub 0} ∼ 0.3 cm{sup –3}), with an upstream magnetic field of ∼5 μG, and with ∼16% of the SNR kinetic energy being converted into relativistic electrons and ions through diffusive shock acceleration, reproduces the observed properties of Tycho. Under such a scenario, the bulk of observed γ-ray emission at high energies is produced by π{sup 0}-decay resulting from the collisions of energetic hadrons, while inverse-Compton emission is significant at lower energies, comprising roughly half of the flux between 1 and 10 GeV.

  4. A survey of infrared supernova remnants in the Large Magellanic Cloud

    SciTech Connect

    Seok, Ji Yeon; Koo, Bon-Chul; Onaka, Takashi

    2013-12-20

    We present a comprehensive infrared study of supernova remnants (SNRs) in the Large Magellanic Cloud (LMC) using near- to mid-infrared images taken by Infrared Array Camera (IRAC; 3.6, 4.5, 5.8, and 8 μm) and Multiband Imaging Photometer (MIPS; 24 and 70 μm) onboard the Spitzer Space Telescope. Among the 47 bona fide LMC SNRs, 29 were detected in infrared, giving a high detection rate of 62%. All 29 SNRs show emission at 24 μm, and 20 out of 29 show emission in one or several IRAC bands. We present their 4.5, 8, 24, and 70 μm images and a table summarizing their Spitzer fluxes. We find that the LMC SNRs are considerably fainter than the Galactic SNRs, and that, among the LMC SNRs, Type Ia SNRs are significantly fainter than core-collapse SNRs. We conclude that the MIPS emission of essentially all SNRs originates from dust emission, whereas their IRAC emissions originate from ionic/molecular lines, polycyclic aromatic hydrocarbons emission, or synchrotron emission. The infrared fluxes show correlation with radio and X-ray fluxes. For SNRs that have similar morphology in infrared and X-rays, the ratios of 24 to 70 μm fluxes have good correlation with the electron density of hot plasma. The overall correlation is explained well by the emission from collisionally heated silicate grains of 0.1 μm size, but for mature SNRs with relatively low gas temperatures, the smaller-sized grain population is favored more. For those that appear different between infrared and X-rays, the emission in the MIPS bands is probably from dust heated by shock radiation.

  5. Dust Processing in Supernova Remnants: Spitzer MIPS SED and IRS Observations

    NASA Technical Reports Server (NTRS)

    Hewitt, John W.; Petre, Robert; Katsuda Satoru; Andersen, M.; Rho, J.; Reach, W. T.; Bernard, J. P.

    2011-01-01

    We present Spitzer MIPS SED and IRS observations of 14 Galactic Supernova Remnants previously identified in the GLIMPSE survey. We find evidence for SNR/molecular cloud interaction through detection of [OI] emission, ionic lines, and emission from molecular hydrogen. Through black-body fitting of the MIPS SEDs we find the large grains to be warm, 29-66 K. The dust emission is modeled using the DUSTEM code and a three component dust model composed of populations of big grains, very small grains, and polycyclic aromatic hydrocarbons. We find the dust to be moderately heated, typically by 30-100 times the interstellar radiation field. The source of the radiation is likely hydrogen recombination, where the excitation of hydrogen occurred in the shock front. The ratio of very small grains to big grains is found for most of the molecular interacting SNRs to be higher than that found in the plane of the Milky Way, typically by a factor of 2--3. We suggest that dust shattering is responsible for the relative over-abundance of small grains, in agreement with prediction from dust destruction models. However, two of the SNRs are best fit with a very low abundance of carbon grains to silicate grains and with a very high radiation field. A likely reason for the low abundance of small carbon grains is sputtering. We find evidence for silicate emission at 20 $\\mu$m in their SEDs, indicating that they are young SNRs based on the strong radiation field necessary to reproduce the observed SEDs.

  6. Cr-K EMISSION LINE AS A CONSTRAINT ON THE PROGENITOR PROPERTIES OF SUPERNOVA REMNANTS

    SciTech Connect

    Yang, X. J.; Xiang, F. Y.; Xiao, H. P.; Zhong, J. X.; Tsunemi, H.; Lu, F. J.; Li, Aigen

    2013-03-20

    We perform a survey of the Cr, Mn, and Fe-K emission lines in young supernova remnants (SNRs) with the Japanese X-ray astronomy satellite Suzaku. The Cr and/or Mn emission lines are detected in 3C 397 and 0519-69.0 for the first time. We also confirm the detection of these lines in Kepler, W49B, N103B, and Cas A. We derive the line parameters (i.e., the line centroid energy, flux, and equivalent width (EW)) for these six sources and perform a correlation analysis for the line center energies of Cr, Mn, and Fe. Also included in the correlation analysis are Tycho and G344.7-0.1 for which the Cr, Mn, and Fe-K line parameters were available in the literature through Suzaku observations. We find that the line center energies of Cr correlate very well with that of Fe and that of Mn. This confirms our previous findings that Cr, Mn, and Fe are spatially co-located, share a similar ionization state, and have a common origin in the supernova nucleosynthesis. We find that the ratio of the EW of the Cr emission line to that of Fe ({gamma}{sub Cr/Fe}{identical_to}EW(Cr)/EW(Fe)) provides useful constraints on the SNR progenitors and on the SN explosion mechanisms: for SNRs with {gamma}{sub Cr/Fe} > 2%, a Type Ia origin is favored (e.g., N103B, G344.7-0.1, 3C 397, and 0519-69.0); for SNRs with {gamma}{sub Cr/Fe} < 2%, they could be of either core-collapse origin or carbon-deflagration Ia origin.

  7. Cr-K Emission Line as a Constraint on the Progenitor Properties of Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Yang, X. J.; Tsunemi, H.; Lu, F. J.; Li, Aigen; Xiang, F. Y.; Xiao, H. P.; Zhong, J. X.

    2013-03-01

    We perform a survey of the Cr, Mn, and Fe-K emission lines in young supernova remnants (SNRs) with the Japanese X-ray astronomy satellite Suzaku. The Cr and/or Mn emission lines are detected in 3C 397 and 0519-69.0 for the first time. We also confirm the detection of these lines in Kepler, W49B, N103B, and Cas A. We derive the line parameters (i.e., the line centroid energy, flux, and equivalent width (EW)) for these six sources and perform a correlation analysis for the line center energies of Cr, Mn, and Fe. Also included in the correlation analysis are Tycho and G344.7-0.1 for which the Cr, Mn, and Fe-K line parameters were available in the literature through Suzaku observations. We find that the line center energies of Cr correlate very well with that of Fe and that of Mn. This confirms our previous findings that Cr, Mn, and Fe are spatially co-located, share a similar ionization state, and have a common origin in the supernova nucleosynthesis. We find that the ratio of the EW of the Cr emission line to that of Fe (\\gamma _Cr/Fe\\equiv EW(Cr)/EW(Fe)) provides useful constraints on the SNR progenitors and on the SN explosion mechanisms: for SNRs with γCr/Fe > 2%, a Type Ia origin is favored (e.g., N103B, G344.7-0.1, 3C 397, and 0519-69.0) for SNRs with γCr/Fe < 2%, they could be of either core-collapse origin or carbon-deflagration Ia origin.

  8. A Survey of Infrared Supernova Remnants in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Seok, Ji Yeon; Koo, Bon-Chul; Onaka, Takashi

    2013-12-01

    We present a comprehensive infrared study of supernova remnants (SNRs) in the Large Magellanic Cloud (LMC) using near- to mid-infrared images taken by Infrared Array Camera (IRAC; 3.6, 4.5, 5.8, and 8 μm) and Multiband Imaging Photometer (MIPS; 24 and 70 μm) onboard the Spitzer Space Telescope. Among the 47 bona fide LMC SNRs, 29 were detected in infrared, giving a high detection rate of 62%. All 29 SNRs show emission at 24 μm, and 20 out of 29 show emission in one or several IRAC bands. We present their 4.5, 8, 24, and 70 μm images and a table summarizing their Spitzer fluxes. We find that the LMC SNRs are considerably fainter than the Galactic SNRs, and that, among the LMC SNRs, Type Ia SNRs are significantly fainter than core-collapse SNRs. We conclude that the MIPS emission of essentially all SNRs originates from dust emission, whereas their IRAC emissions originate from ionic/molecular lines, polycyclic aromatic hydrocarbons emission, or synchrotron emission. The infrared fluxes show correlation with radio and X-ray fluxes. For SNRs that have similar morphology in infrared and X-rays, the ratios of 24 to 70 μm fluxes have good correlation with the electron density of hot plasma. The overall correlation is explained well by the emission from collisionally heated silicate grains of 0.1 μm size, but for mature SNRs with relatively low gas temperatures, the smaller-sized grain population is favored more. For those that appear different between infrared and X-rays, the emission in the MIPS bands is probably from dust heated by shock radiation.

  9. A systematic study of evolved supernova remnants in the large and small Magellanic Clouds with Suzaku

    NASA Astrophysics Data System (ADS)

    Takeuchi, Yoko; Yamaguchi, Hiroya; Tamagawa, Toru

    2016-06-01

    Identifying the origin type (i.e., Type Ia or core-collapse) of supernova remnants (SNRs) is crucial to determining the rates of supernova (SN) explosions in a galaxy, which is a key to understanding its recent chemical evolution. However, evolved SNRs in the so-called Sedov phase are dominated by the swept-up interstellar medium (ISM), making it difficult to determine their ejecta composition and thus SN type. Here we present a systematic X-ray study of nine evolved SNRs in the Magellanic Clouds, DEM L238, DEM L249, 0534-69.9, 0548-70.4, B0532-71.0, B0532-67.5, 0103-72.6, 0049-73.6, and 0104-72.3, using archival data of the Suzaku satellite. Although Suzaku does not spatially resolve the SN ejecta from the swept-up ISM due to the limited angular resolution, its excellent energy resolution has enabled clear separation of emission lines in the soft X-ray band. This leads to the finding that the "spatially integrated" spectra of the evolved (˜104 yr) SNRs are still significantly contributed by emission from the ejecta at energies around 1 keV. The Fe/Ne mass ratios, determined mainly from the well-resolved Fe L-shell and Ne K-shell lines, clearly divide the observed SNRs into the Type Ia and core-collapse groups, confirming some previous typing made by Chandra observations that had utilized its extremely high angular resolution. This demonstrates that spatially integrated X-ray spectra of old SNRs can also be used to discriminate their progenitor type, which would be helpful for future systematic studies of extragalactic SNRs with ASTRO-H and beyond.

  10. Transition to the radiative phase in supernova remnant evolution

    NASA Astrophysics Data System (ADS)

    Wright, Eric Boyd

    1999-11-01

    The evolution of a supernova remnant (SNR) through the transition from an adiabatic Sedov-Taylor blastwave to a radiative pressure-driven snowplow phase is studied through a series of one-, two- and three-dimensional hydrodynamic (HD) and magnetohydrodynamic (MHD) simulations. This transition is marked by a catastrophic collapse of the postshock gas, forming a thin, dense shell behind the forward shock. Previous studies have shown that the thin, dense shell of gas present during this transition is susceptible to both radiative and dynamical instabilities. One-dimensional HD studies indicate the presence of a radial oscillation between the forward shock and the thin shell, due to the rapid cooling of the gas in the immediate postshock region. Two-dynamical HD simulations of this transition indicate the presence of violent dynamical instabilities that alter the initially spherical morphology of the blastwave, specifically, the Pressure-driven Thin Shell Overstability (PDTSO) and the Non-linear Thin Shell Instability (NTSI). Hydrodynamical simulations, by their very nature, ignore the effects of magnetic forces on moving fluids. In general, interstellar magnetic fields will be weak enough that their effects may be safely ignored. However, the transition to the radiative phase in SNR evolution is often triggered when the blastwave interacts with dense clouds of gas in the interstellar medium (ISM). The resulting compression of the gas during the transition also compresses the magnetic fields in the cloud, possibly enhancing the field sufficiently to play a role in the further evolution of the SNR. To better understand the role of the NTSI during the transition, and to study the effects of magnetic fields on the instability itself, we performed idealized two- and three-dimensional MHD simulations. The results of the two-dimensional simulations were found to depend strongly on the orientation of the ambient magnetic field when the postshock field is dynamically

  11. Magnetic Amplification by Magnetized Cosmic Rays in Supernova Remnant Shocks

    NASA Astrophysics Data System (ADS)

    Riquelme, Mario A.; Spitkovsky, Anatoly

    2010-07-01

    X-ray observations of synchrotron rims in supernova remnant (SNR) shocks show evidence of efficient electron acceleration and strong magnetic field amplification (a factor of ~100 between the upstream and downstream medium). This amplification may be due to plasma instabilities driven by shock-accelerated particles or cosmic rays (CRs), as they propagate ahead of the shocks. One candidate process is the cosmic ray current-driven (CRCD) instability caused by the electric current of "unmagnetized" CRs (i.e., CRs whose Larmor radii are much larger than the length scale of the CRCD modes) propagating parallel to the upstream magnetic field. Particle-in-cell (PIC) simulations have shown that the back-reaction of the amplified field on CRs would limit the amplification factor of this instability to less than ~10 in galactic SNRs (not including the additional field compression at the shock). In this paper, we study the possibility of further amplification driven near shocks by "magnetized" CRs, whose Larmor radii are smaller than the length scale of the field that was previously amplified by the CRCD instability. We find that additional amplification can occur due to a new instability, driven by the CR current perpendicular to the field, which we term the perpendicular current-driven instability (PCDI). We derive the growth rate of this instability and, using PIC simulations, study its non-linear evolution. We show that the maximum amplification of PCDI is determined by the disruption of CR current, which happens when CR Larmor radii in the amplified field become comparable to the length scale of the instability. We find that, in regions close to the shock, PCDI grows on scales smaller than the scales of the CRCD instability, and, therefore, it results in larger amplification of the field (amplification factor up to ~45). One possible observational signature of PCDI is the characteristic dependence of the amplified field on the shock velocity, B 2 vprop v 2 sh, which

  12. MAGNETIC AMPLIFICATION BY MAGNETIZED COSMIC RAYS IN SUPERNOVA REMNANT SHOCKS

    SciTech Connect

    Riquelme, Mario A.; Spitkovsky, Anatoly E-mail: anatoly@astro.princeton.ed

    2010-07-10

    X-ray observations of synchrotron rims in supernova remnant (SNR) shocks show evidence of efficient electron acceleration and strong magnetic field amplification (a factor of {approx}100 between the upstream and downstream medium). This amplification may be due to plasma instabilities driven by shock-accelerated particles or cosmic rays (CRs), as they propagate ahead of the shocks. One candidate process is the cosmic ray current-driven (CRCD) instability caused by the electric current of 'unmagnetized' CRs (i.e., CRs whose Larmor radii are much larger than the length scale of the CRCD modes) propagating parallel to the upstream magnetic field. Particle-in-cell (PIC) simulations have shown that the back-reaction of the amplified field on CRs would limit the amplification factor of this instability to less than {approx}10 in galactic SNRs (not including the additional field compression at the shock). In this paper, we study the possibility of further amplification driven near shocks by 'magnetized' CRs, whose Larmor radii are smaller than the length scale of the field that was previously amplified by the CRCD instability. We find that additional amplification can occur due to a new instability, driven by the CR current perpendicular to the field, which we term the perpendicular current-driven instability (PCDI). We derive the growth rate of this instability and, using PIC simulations, study its non-linear evolution. We show that the maximum amplification of PCDI is determined by the disruption of CR current, which happens when CR Larmor radii in the amplified field become comparable to the length scale of the instability. We find that, in regions close to the shock, PCDI grows on scales smaller than the scales of the CRCD instability, and, therefore, it results in larger amplification of the field (amplification factor up to {approx}45). One possible observational signature of PCDI is the characteristic dependence of the amplified field on the shock velocity, B {sup

  13. FAR-INFRARED LUMINOUS SUPERNOVA REMNANT Kes 17

    SciTech Connect

    Lee, Ho-Gyu; Moon, Dae-Sik; Koo, Bon-Chul; Onaka, Takashi; Sakon, Itsuki; Jeong, Woong-Seob; Shinn, Jong-Ho E-mail: moon@astro.utoronto.ca E-mail: onaka@astron.s.u-tokyo.ac.jp E-mail: jeongws@kasi.re.kr

    2011-10-10

    We present the results of infrared (IR; 2.5-160 {mu}m) observations of the supernova remnant (SNR) Kes 17 based on the data obtained with the AKARI and Spitzer satellites. We first detect bright continuum emission of its western shell in the mid- and far-IR wavebands together with its near-IR molecular line emission. We also detect hidden mid-IR emission of its southern shell after subtraction of the background emission in this region. The far-IR luminosity of the western shell is {approx}8100 L{sub sun}, which makes Kes 17 one of the few SNRs of significant far-IR emission. The fittings of the spectral energy distribution indicate the existence of two dust components: {approx}79 K (hot) and {approx}27 K (cold) corresponding to the dust masses of {approx}6.2 x 10{sup -4} M{sub sun} and {approx}6.7 M{sub sun}, respectively. We suggest that the hot component represents the dust emission of the material swept up by the SNR to its western and southern boundaries, compatible with the distribution of radio continuum emission overlapping the mid-IR emission in the western and southern shells. The existence of hot ({approx}2000 K), shocked dense molecular gas revealed by the near-IR molecular line emission in the western shell, on the other hand, suggests that the cold dust component represents the dust emission related to the interaction between the SNR and nearby molecular gas. The excitation conditions of the molecular gas appear to be consistent with those from shocked, clumpy admixture gas of different temperatures. We discuss three possibilities for the origin of the bright far-IR emission of the cold dust in the western shell: the emission of dust in the inter-clump medium of shocked molecular clouds, the emission of dust in evaporating flows of molecular clouds engulfed by hot gas, and the emission of dust of nearby molecular clouds illuminated by radiative shocks.

  14. Eocene Tibetan Plateau remnants preserved in the Northwest Himalaya

    NASA Astrophysics Data System (ADS)

    van der Beek, P. A.; van Melle, J.; Guillot, S.; Pêcher, A.; Reiners, P. W.; Nicolescu, S.; Latif, M.

    2009-04-01

    scattered published data from the other plateau and low-relief summit regions in the northwest Himalaya. We show that the plateau regions share common morphologic characteristics and denudation histories, which are comparable to those of the western Tibetan plateau. These results imply that they may be preserved remnants of an Eocene south-western Tibetan plateau that was more widespread than today and that was subsequently dissected by rivers following major faults.

  15. High-Velocity H I Gas in Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Koo, Bon-Chul

    1993-05-01

    Using the Hat Creek 85 foot telescope, we had carried out a survey of H I 21 cm emission lines toward all 103 known northern supernova remnants (SNRs) in order to find rapidly expanding SNR shells (Koo & Heiles 1991). We detected 15 SNRs that have associated high-velocity (HV) H I gas, most of which are quite likely the gas accelerated by the SN blast wave. Although the large beam-size (FWHM~ 30') of the 85 foot telescope prevented us to see the structure of the HV H I gas, the H I mass distribution in line-of-sight velocity suggested clumpy shell structures in several SNRs. In order to resolve the structure of the HV H I gas, we have been carrying out high-resolution H I 21 cm line observations using the Arecibo telescope and the VLA. We report preliminary results on two SNRs, CTB 80 and W51. In CTB 80, the VLA observations revealed fast moving H I clumps, which have a dense (n_H ~ 100 cm(-3) ) core surrounded by a relatively diffuse envelope. The clumps are small, 3 pc to 5 pc, and have velocities between +40 km s(-1) and +80 km s(-1) with respect to the systematic velocity of CTB 80. The clumps have relatively large momentum per unit volume, which implies that they have been swept-up at an early stage of the SNR evolution. By analyzing the Arecibo data, we found that the interstellar medium around CTB 80 is far from being uniform and homogeneous, which explains the peculiar morphology of CTB 80 in infrared and radio continuum. In W51, HV H I gas moving up to v_LSR>+150 km s(-1) has been detected. The H I distribution is elongated along the northwest-southeast direction, and the peak is very close to an X-ray bright region. We discuss the implications of our results in relation to the X-ray and the radio continuum morphology of W51. This work was supported in part by NON DIRECTED RESEARCH FUND, Korea Research Foundation, 1992.

  16. Detecting isotopic ratio outliers

    SciTech Connect

    Bayne, C.K.; Smith, D.H.

    1985-01-01

    An alternative method is proposed for improving isotopic ratio estimates. This method mathematically models pulse-count data and uses iterative reweighted Poisson regression to estimate model parameters to calculate the isotopic ratios. This computer-oriented approach provides theoretically better methods than conventional techniques to establish error limits and to identify outliers. 6 refs., 3 figs., 3 tabs.

  17. A distance determination for the supernova remnant G27.4+0.0 and its central X-ray source

    NASA Technical Reports Server (NTRS)

    Sanbonmatsu, K. Y.; Helfand, D. J.

    1992-01-01

    We have determined the distance to the supernova remnant G27.4+0.0, one of the handful of remnants with a bright central X-ray source. H I absorption data obtained with the VLA toward the remnant and adjacent H II regions allow us to constrain the distance to G27.4+0.0 to lie between 6 and 7.5 kpc. We briefly discuss the implications of this result for the nature of the central source.

  18. Chandra Observations and Models of the Mixed Morphology Supernova Remnant W44: Global Trends

    NASA Technical Reports Server (NTRS)

    Shelton, R. L.; Kuntz, K. D.; Petre, R.

    2004-01-01

    We report on the Chandra observations of the archetypical mixed morphology (or thermal composite) supernova remnant, W44. As with other mixed morphology remnants, W44's projected center is bright in thermal X-rays. It has an obvious radio shell, but no discernable X-ray shell. In addition, X-ray bright knots dot W44's image. The spectral analysis of the Chandra data show that the remnant s hot, bright projected center is metal-rich and that the bright knots are regions of comparatively elevated elemental abundances. Neon is among the affected elements, suggesting that ejecta contributes to the abundance trends. Furthermore, some of the emitting iron atoms appear to be underionized with respect to the other ions, providing the first potential X-ray evidence for dust destruction in a supernova remnant. We use the Chandra data to test the following explanations for W44's X-ray bright center: 1.) entropy mixing due to bulk mixing or thermal conduction, 2.) evaporation of swept up clouds, and 3.) a metallicity gradient, possibly due to dust destruction and ejecta enrichment. In these tests, we assume that the remnant has evolved beyond the adiabatic evolutionary stage, which explains the X-ray dimness of the shell. The entropy mixed model spectrum was tested against the Chandra spectrum for the remnant's projected center and found to be a good match. The evaporating clouds model was constrained by the finding that the ionization parameters of the bright knots are similar to those of the surrounding regions. While both the entropy mixed and the evaporating clouds models are known to predict centrally bright X-ray morphologies, their predictions fall short of the observed brightness gradient. The resulting brightness gap can be largely filled in by emission from the extra metals in and near the remnant's projected center. The preponderance of evidence (including that drawn from other studies) suggests that W44's remarkable morphology can be attributed to dust destruction

  19. Discovery of High-Velocity Gas in Absorption Associated with the Supernova Remnant W28

    NASA Astrophysics Data System (ADS)

    Ritchey, Adam M.; Wallerstein, G.

    2013-01-01

    We report the discovery of high-velocity interstellar absorption components observed toward the star CD-23 13777, an O-type supergiant located behind the supernova remnant W28. The interstellar Na I and Ca II profiles in this direction comprise numerous absorption components with velocities ranging from -150 km s-1 to +140 km s-1. The presence of gas at both high positive and high negative velocities indicates that the line of sight to CD-23 13777 probes both sides of the expanding shell of the remnant. The strongest interstellar absorption occurs at a velocity of +7.5 km s-1, consistent with the velocities of several nearby OH (1720 MHz) masers, which themselves are indicative of shock interactions between the supernova remnant and an adjacent molecular cloud. Moreover, the CD-23 13777 sight line passes very near a source of both GeV and TeV gamma rays, which likely result from collisions between high-energy particles, accelerated by the remnant, and the dense molecular gas in its vicinity. The identification of this line of sight as an exquisite probe of the interaction between the supernova remnant and the ambient molecular cloud paves the way for future observations in the UV and visible, which will enable a more detailed understanding of the physical conditions in the shocked gas and yield elemental abundances that can be used to study the chemical enrichment of the interstellar medium by the supernova explosion.

  20. Are supernovae radio sources - A search for radio emission from young supernova remnants

    NASA Technical Reports Server (NTRS)

    Brown, R. L.; Marscher, A. P.

    1978-01-01

    A search has been conducted for radio emission at 11 and 3.7 cm from 46 recent supernovae having accurately determined positions and ages of a few months to 79 years. None of these supernovae was detected at a flux density greater than 5-10 mJy. These negative results cannot be explained by internal absorption and are thus due to intrinsically weak synchrotron emission in young supernova remnants. There are two possibilities: either (1) relativistic particles are accelerated not by the supernova outburst but by processes occurring much later (at least about 75 years) in the remnant or (2) the magnetic field in the young remnants evolves very slowly, in proportion to the inverse square root of time, so that its value in the remnants observed was no more than about 0.002 gauss. The constraints the observations place on these possibilities and on the energy in cosmic rays in young remnants are discussed. Gamma-ray observations at times of no more than about 1 year following an outburst will allow one to discriminate between the two alternative explanations of the radio results.

  1. Uptake and processing of remnants of chylomicrons and very low density lipoproteins by rat liver

    SciTech Connect

    Jones, A.L.; Hradek, G.T.; Hornick, C.; Renaud, G.; Windler, E.E.; Havel, R.J.

    1984-11-01

    In the rat, chylomicron remnants and very low density lipoprotein (VLDL) remnants are taken up into the liver by high affinity processes and appear to undergo degradation by lysosomes. The relationship of this catabolic process to the known pathways of uptake and degradation of low density lipoproteins (LDL) and the involvement of nonparenchymal cells are addressed in these studies. The authors have utilized both light and electron microscopic radioautography to determine whether the pathway of intracellular transport and catabolism resembles that established for LDL in hepatocytes. Radioiodinated plasma VLDL remnants and lymph chylomicron remnants were injected into femoral veins of rats and the livers were fixed by perfusion 3 to 30 minutes later. Quantitative light microscopic radioautography showed little or no accumulation of grains over Kupffer cells. Electromicroscopic radioautography confirmed these observations and, in addition, demonstrated that very few grains were associated with endothelial cells. The processing of the remnant particles closely resembled that of LDL. Following an initial association of grains with the parenchymal cell plasma membrane, frequently in regions in close proximity to clathrin-coated endocytic pits, the grains were found in endocytic vesicles just beneath the plasma membrane. By 15 minutes the grains were found over multivesicular bodies located in the Golgi-lysosome region of the cell. Thirty minutes after injection, radioautographic grains began to be associated with secondary lysosomes.

  2. THE ABSENCE OF EX-COMPANIONS IN TYPE Ia SUPERNOVA REMNANTS

    SciTech Connect

    Di Stefano, R.; Kilic, Mukremin E-mail: kilic@ou.edu

    2012-11-01

    Type Ia supernovae (SNe Ia) play important roles in our study of the expansion and acceleration of the universe, but because we do not know the exact nature or natures of the progenitors, there is a systematic uncertainty that must be resolved if SNe Ia are to become more precise cosmic probes. No progenitor system has ever been identified either in the pre- or post-explosion images of a Ia event. There have been recent claims for and against the detection of ex-companion stars in several SNe Ia remnants. These studies, however, usually ignore the angular momentum gain of the progenitor white dwarf (WD), which leads to a spin-up phase and a subsequent spin-down phase before explosion. For spin-down timescales greater than 10{sup 5} years, the donor star could be too dim to detect by the time of explosion. Here we revisit the current limits on ex-companion stars to SNR 0509-67.5, a 400-year-old remnant in the Large Magellanic Cloud. If the effects of possible angular momentum gain on the WD are included, a wide range of single-degenerate progenitor models are allowed for this remnant. We demonstrate that the current absence of evidence for ex-companion stars in this remnant, as well as other SNe Ia remnants, does not necessarily provide the evidence of absence for ex-companions. We discuss potential ways to identify such ex-companion stars through deep imaging observations.

  3. DISCRIMINATING THE PROGENITOR TYPE OF SUPERNOVA REMNANTS WITH IRON K-SHELL EMISSION

    SciTech Connect

    Yamaguchi, Hiroya; Petre, Robert; Enoto, Teruaki; Badenes, Carles; Nakano, Toshio; Hiraga, Junko S.; Castro, Daniel; Hughes, John P.; Maeda, Yoshitomo; Nobukawa, Masayoshi; Uchida, Hiroyuki; Safi-Harb, Samar; Slane, Patrick O.; Smith, Randall K.

    2014-04-20

    Supernova remnants (SNRs) retain crucial information about both their parent explosion and circumstellar material left behind by their progenitor. However, the complexity of the interaction between supernova ejecta and ambient medium often blurs this information, and it is not uncommon for the basic progenitor type (Ia or core-collapse) of well-studied remnants to remain uncertain. Here we present a powerful new observational diagnostic to discriminate between progenitor types and constrain the ambient medium density of SNRs using solely Fe K-shell X-ray emission. We analyze all extant Suzaku observations of SNRs and detect Fe Kα emission from 23 young or middle-aged remnants, including five first detections (IC 443, G292.0+1.8, G337.2-0.7, N49, and N63A). The Fe Kα centroids clearly separate progenitor types, with the Fe-rich ejecta in Type Ia remnants being significantly less ionized than in core-collapse SNRs. Within each progenitor group, the Fe Kα luminosity and centroid are well correlated, with more luminous objects having more highly ionized Fe. Our results indicate that there is a strong connection between explosion type and ambient medium density, and suggest that Type Ia supernova progenitors do not substantially modify their surroundings at radii of up to several parsecs. We also detect a K-shell radiative recombination continuum of Fe in W49B and IC 443, implying a strong circumstellar interaction in the early evolutionary phases of these core-collapse remnants.

  4. HFPK 334: An Unusual Supernova Remnant in the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Crawford, E. J.; Filipović, M. D.; McEntaffer, R. L.; Brantseg, T.; Heitritter, K.; Roper, Q.; Haberl, F.; Urošević, D.

    2014-11-01

    We present new Australia Telescope Compact Array radio-continuum and XMM-Newton/Chandra X-ray Observatory observations of the unusual supernova remnant (SNR) HFPK 334 in the Small Magellanic Cloud (SMC). The remnant follows a shell-type morphology in the radio continuum and has a size of ~20 pc at the SMC distance. The X-ray morphology is similar; however, we detect a prominent point source close to the center of the SNR exhibiting a spectrum with a best-fit power law with a photon index of Γ = 2.7 ± 0.5. This central point source is most likely a background object and cannot be directly associated with the remnant. The high temperature, nonequilibrium conditions in the diffuse region suggest that this gas has been recently shocked and points toward a younger SNR with an age of <~ 1800 yr. With an average radio spectral index of α = -0.59 ± 0.09, we find that an equipartition magnetic field for the remnant is ~90 μG, a value typical of younger SNRs in low-density environments. Also, we report the detection of scattered radio polarization across the remnant at 20 cm, with a peak fractional polarization level of 25% ± 5%.

  5. The Gastric Remnant in Roux-en-Y Gastric Bypass: Challenges and Possibilities.

    PubMed

    Mala, Tom

    2016-08-01

    Laparoscopic Roux-en-Y gastric bypass (RYGB) is widely applied in the treatment of morbid obesity. Health personnel meeting these patients should thus be familiar with the potential clinical consequences of the modified anatomy induced by the surgery. After a RYGB, the stomach is left in situ after the closure of the upper part of the organ. This blind-ended gastric remnant may cause complications and surgical emergencies, but also opportunities for diagnostic and therapeutic intervention. The present review focuses on complications related to the gastric remnant including bleeding and acute dilatation in the early postoperative period and later adverse events such as gastroduodenal peptic disease, tumors, gastrogastric fistulas, and late dilatation. Opportunities offered by the remnant, including minimal invasive or open access for enteral nutrition, and therapeutic and diagnostic access to the bile ducts, the duodenum, and the gastric remnant, which is challenged by the modified anatomy, are discussed. Reversal of the gastric bypass and gastrointestinal reconstruction after esophageal resection have been commented on. The review aims to improve the awareness of issues related to the gastric remnant for physicians involved in the treatment and the follow-up of patients after a RYGB. PMID:27203428

  6. Excision of the urachal remnant using the abdominal wall-lift laparoscopy: A case report

    PubMed Central

    Kobayashi, Kosuke; Sasaki, Kazuhito; Iijima, Tatsuo; Yoshimi, Fuyo; Nagai, Hideo

    2016-01-01

    Introduction Here, we report the surgical excision of the urachal remnant using the abdominal wall-lift laparoscopy with a camera port in the umbilicus, combined with a small Pfannenstiel incision to optimally treat the bladder apex. Presentation of case A 21-year-old woman presented with periumbilical discharge and pain on urination. Contrast enhanced CT and MRI showed an abscess in the umbilical region that was connected to the bladder via a long tube-like structure. It was diagnosed as an infected urachal sinus. Partial excision of the umbilical fossa followed by dissection of the urachal remnant was easily performed using the abdominal wall-lift laparoscopy from the umbilicus down to the bladder without pneumoperitoneum or additional trocar placement. A Pfannenstiel incision was made above the pubis to get access to the junction between the urachal remnant and the bladder. Under direct vision, we succeeded in accurately dividing the remnant tract, and we adequately closed the bladder opening with absorbable sutures. This method has the advantage of easily closing peritoneal defects after excision of the urachal remnant with direct sutures under a laparoscopic view from the umbilicus. Cosmetic satisfaction was obtained postoperatively. Discussion and conclusion Urachal sinus excision using the abdominal wall-lift laparoscopy seems to surpass the previously reported methods in term of safety, cosmetics, and adequacy of surgical procedures. PMID:27064744

  7. HFPK 334: An unusual supernova remnant in the Small Magellanic Cloud

    SciTech Connect

    Crawford, E. J.; Filipović, M. D.; McEntaffer, R. L.; Brantseg, T.; Heitritter, K.; Roper, Q.; Haberl, F.; Urošević, D.

    2014-11-01

    We present new Australia Telescope Compact Array radio-continuum and XMM-Newton/Chandra X-ray Observatory observations of the unusual supernova remnant (SNR) HFPK 334 in the Small Magellanic Cloud (SMC). The remnant follows a shell-type morphology in the radio continuum and has a size of ∼20 pc at the SMC distance. The X-ray morphology is similar; however, we detect a prominent point source close to the center of the SNR exhibiting a spectrum with a best-fit power law with a photon index of Γ = 2.7 ± 0.5. This central point source is most likely a background object and cannot be directly associated with the remnant. The high temperature, nonequilibrium conditions in the diffuse region suggest that this gas has been recently shocked and points toward a younger SNR with an age of ≲ 1800 yr. With an average radio spectral index of α = –0.59 ± 0.09, we find that an equipartition magnetic field for the remnant is ∼90 μG, a value typical of younger SNRs in low-density environments. Also, we report the detection of scattered radio polarization across the remnant at 20 cm, with a peak fractional polarization level of 25% ± 5%.

  8. The Role of Small Woodland Remnants on Ground Dwelling Insect Conservation in Chaco Serrano, Central Argentina

    PubMed Central

    Moreno, María Laura; Fernández, María Guadalupe; Molina, Silvia Itati; Valladares, Graciela

    2013-01-01

    Many terrestrial ecosystems are changing due to extensive land use and habitat fragmentation, posing a major threat to biodiversity. In this study, the effects of patch size, isolation, and edge/interior localization on the ground dwelling insect communities in the Chaco Serrano woodland remnants in central Argentina were examined. Sampling was carried out in December 2003 and March 2004 in nine remnants (0.57 to 1000 hectares) using pitfall traps. In total, 7071 individuals representing 12 orders and 79 families were recorded. The taxonomic composition of these communities was linked to remnant size. Insect abundance increased (as did their richness, albeit marginally) as remnant area decreased, with no significant effects of isolation or edge/interior localization on abundance, richness, or diversity. No differential area effects were observed when abundance and richness of predators, scavengers, and herbivores were compared. Thus, ground insect communities in fragmented Chaco Serrano seem to respond mainly to patch level, rather than to within-patch (edge effects) or landscape (isolation) level variables. These results suggest that small Chaco Serrano remnants, by supporting larger ground-dwelling insect assemblages, may play an important role from a conservation viewpoint. PMID:23902409

  9. Endoscopic Submucosal Dissection for the Complete Resection of the Rectal Remnant Mucosa in a Patient With Familial Adenomatous Polyposis

    PubMed Central

    Akiyama, Hitoshi; Suzuki, Koyu; Fujita, Yoshiyuki

    2016-01-01

    A 47-year-old woman underwent prophylactic subtotal colectomy with ileorectal anastomosis (IRA) for familial adenomatous polyposis (FAP) 18 years ago. She underwent 5 transanal endoscopic microsurgeries for rectal remnant polyps, and was referred for the treatment of rectal remnant polyp recurrence. Endoscopic submucosal dissection (ESD) was performed to remove multiple polypoid lesions that circumferentially extended throughout the rectal remnant with lesions spreading onto the anastomotic site. The rectal remnant mucosa was resected in 2 pieces without complication. Specimens showed high-grade adenoma but no malignancy. Follow-up colonoscopy showed no recurrence. PMID:27144195

  10. Endoscopic Submucosal Dissection for the Complete Resection of the Rectal Remnant Mucosa in a Patient With Familial Adenomatous Polyposis.

    PubMed

    Ishii, Naoki; Akiyama, Hitoshi; Suzuki, Koyu; Fujita, Yoshiyuki

    2016-04-01

    A 47-year-old woman underwent prophylactic subtotal colectomy with ileorectal anastomosis (IRA) for familial adenomatous polyposis (FAP) 18 years ago. She underwent 5 transanal endoscopic microsurgeries for rectal remnant polyps, and was referred for the treatment of rectal remnant polyp recurrence. Endoscopic submucosal dissection (ESD) was performed to remove multiple polypoid lesions that circumferentially extended throughout the rectal remnant with lesions spreading onto the anastomotic site. The rectal remnant mucosa was resected in 2 pieces without complication. Specimens showed high-grade adenoma but no malignancy. Follow-up colonoscopy showed no recurrence. PMID:27144195

  11. Successful treatment of a patient with an infected urachal remnant via single-incision laparoscopic surgery: Report of a case.

    PubMed

    Nakamura, Hiroyuki; Oshita, Akihiko; Imamura, Yuji; Sasaki, Masaru; Kohyama, Mohei; Tazaki, Tatsuya; Sugiyama, Yoichi; Daimaru, Yutaka; Nakamitsu, Atsushi

    2016-02-01

    We report on a case of an infected urachal remnant successfully treated via a single-incisional laparoscopic technique. An 18-year-old woman was diagnosed with an infected urachal remnant. The center of the umbilicus was pulled and inverted from the skin, and the cephalic side of the urachus was dissected from the umbilicus. A single-incision laparoscopic technique employing ultrasonic coagulating shears was used to dissect the urachal remnant from the stump of the umbilicus to the caudal end. Single-incision laparoscopic excision of the urachal remnant can be used successfully as a minimally invasive technique with optimal cosmetic outcomes. PMID:26781536

  12. Deterrence and arrest ratios.

    PubMed

    Carmichael, Stephanie E; Piquero, Alex R

    2006-02-01

    In the limited research on the origins of sanction threat perceptions, researchers have focused on either the effects of actively engaging in crime or the effects of formal sanctioning but rarely on both (i.e., the arrest ratio or the number of arrests relative to the number of crimes committed). This article extends this line of research by using a sample of Colorado inmates and measures arrest ratios and sanction perceptions for eight different crime types. Analyses reveal that the offenders report both significant experiential and arrest ratio effects. Theoretical and policy implications, limitations, and directions for future research are outlined. PMID:16397123

  13. XMM-NEWTON OBSERVATIONS OF TWO CANDIDATE SUPERNOVA REMNANTS

    SciTech Connect

    Kargaltsev, O.; Schmitt, B. M.; Pavlov, G. G.; Misanovic, Z.

    2012-01-20

    Candidate supernova remnants (SNRs) G23.5+0.1 and G25.5+0.0 were observed by XMM-Newton in the course of a snapshot survey of plerionic and composite SNRs in the Galactic plane. In the field of G23.5+0.1, we detected an extended source, {approx}3' in diameter, which we tentatively interpret as a pulsar wind nebula (PWN) of the middle-aged radio pulsar B1830-08 (J1833-0827; P = 85.3 ms, {tau} = 147 kyr, E-dot = 5.8 Multiplication-Sign 10{sup 35} erg s{sup -1}, d = 5.7 kpc), with the PWN luminosity L{sub 0.2-10keV} Almost-Equal-To 5 Multiplication-Sign 10{sup 33} erg s{sup -1} Almost-Equal-To 8 Multiplication-Sign 10{sup -3} E-dot . The pulsar is not resolved in the EPIC images. Our analysis suggests an association between PSR B1830-08 and the surrounding diffuse radio emission. If the radio emission is due to the SNR, then the pulsar must be significantly younger than its characteristic age. Alternatively, the radio emission may come from a relic PWN. The field also contains SGR 1833-0832 and another middle-aged pulsar B1829-08 (J1832-0827; P = 647 ms, {tau} = 161 kyr, E-dot = 9.3 Multiplication-Sign 10{sup 33} erg s{sup -1}, d = 4.7 kpc), none of which are detected in our observation. In the field of G25.5+0.0, which contains the extended TeV source HESS J1837-069, we detected the recently discovered young high-energy pulsar J1838-0655 (P = 70.5 ms, {tau} = 23 kyr, E-dot = 5.5 Multiplication-Sign 10{sup 36} erg s{sup -1}) embedded in a PWN with extent of 1.'3. The unabsorbed pulsar + PWN luminosity is L{sub 2-11keV} Almost-Equal-To 2 Multiplication-Sign 10{sup 34} erg s{sup -1} Almost-Equal-To 4 Multiplication-Sign 10{sup -3} E-dot at an assumed distance of 7 kpc. We also detected another PWN candidate (AX J1837.3-0652) with an extent of 2' and unabsorbed luminosity L{sub 2-10keV} Almost-Equal-To 4 Multiplication-Sign 10{sup 33} erg s{sup -1} at d = 7 kpc. The third X-ray source, located within the extent of the HESS J1837-069, has a peculiar extended radio

  14. A Study of Supernova Remnants with Center-Filled X-Ray Morphology

    NASA Technical Reports Server (NTRS)

    Slane, Patrick O.

    1997-01-01

    CTA 1 is a center-filled supernova remnant (SNR) whose morphology and spectrum indicate the presence of a central pulsar, a synchrotron nebula, and a thermal component associated with the expansion of the blast wave into the interstellar medium. The centrally bright emission surrounds the position of a faint point source of x-rays observed with the ROSAT PSPC. Here we report on ASCA observations that confirm the nonthermal nature of the diffuse emission from the central regions of the remnant. We also present evidence for weak thermal emission that appears to increase in strength toward the outer boundary of the SNR. Thus, CTA 1 appears to be an x-ray composite remnant. Both the aftermath of the explosive supernova event and the energetic compact core are observable.

  15. G306.3-0.9: A NEWLY DISCOVERED YOUNG GALACTIC SUPERNOVA REMNANT

    SciTech Connect

    Reynolds, Mark T.; Miller, Jon M.; Maitra, Dipankar; Gueltekin, Kayhan; Reis, Rubens C.; Loi, Shyeh T.; Murphy, Tara; Moss, Vanessa; Reeves, Sarah; Robbins, William J.; Gaensler, B. M.; Gehrels, Neil; Petre, Robert; Kennea, Jamie A.; Siegel, Michael H.; Gelbord, Jonathan; Kuin, Paul

    2013-04-01

    We present X-ray and radio observations of the new Galactic supernova remnant (SNR) G306.3-0.9, recently discovered by Swift. Chandra imaging reveals a complex morphology, dominated by a bright shock. The X-ray spectrum is broadly consistent with a young SNR in the Sedov phase, implying an age of 2500 yr for a distance of 8 kpc, plausibly identifying this as one of the 20 youngest Galactic SNRs. Australia Telescope Compact Array imaging reveals a prominent ridge of radio emission that correlates with the X-ray emission. We find a flux density of {approx}160 mJy at 1 GHz, which is the lowest radio flux recorded for a Galactic SNR to date. The remnant is also detected at 24 {mu}m, indicating the presence of irradiated warm dust. The data reveal no compelling evidence for the presence of a compact stellar remnant.

  16. Probing the Reverse Shock in an Oxygen-Rich Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Sonneborn, George (Technical Monitor); Gaetz, Terrance J.

    2003-01-01

    The aim of this proposal was to examine the O VI emission at three positions around the X-ray bright ring of the remnant in order to investigate the relation between the O VI emission, the X-ray O VII and O VIII emission, and the optical [O III] emission, and how these vary around the rim of the remnant. So far, only one Far Ultraviolet Spectroscopic Explorer (FUSE) pointing at the remnant has been performed, together with the background pointing needed to subtract the diffuse scattered light from nearby O stars. The data were recalibrated using the CalFUSE calibration pipeline, but the emission is faint enough that hand processing will be needed for this pointing to optimize the extraction. Rereduction of the data is underway. A postdoctoral fellow has also been hired, and in part she will assist with the analysis.

  17. Supernovae. The bubble-like interior of the core-collapse supernova remnant Cassiopeia A.

    PubMed

    Milisavljevic, Dan; Fesen, Robert A

    2015-01-30

    The death of massive stars is believed to involve aspheric explosions initiated by the collapse of an iron core. The specifics of these catastrophic explosions remain uncertain, due partly to limited observational constraints on asymmetries deep inside the star. Here we present near-infrared observations of the young supernova remnant Cassiopeia A, descendant of a type IIb core-collapse explosion, and a three-dimensional map of its interior unshocked ejecta. The remnant's interior has a bubble-like morphology that smoothly connects to and helps explain the multiringed structures seen in the remnant's bright reverse-shocked main shell of expanding debris. This internal structure may originate from turbulent mixing processes that encouraged outwardly expanding plumes of radioactive (56)Ni-rich ejecta. If this is true, substantial amounts of its decay product, (56)Fe, may still reside in these interior cavities. PMID:25635094

  18. Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction With Remnant Preservation Using Outside-In Technique

    PubMed Central

    Lee, Byung-Ill; Kwon, Sai-Won; Choi, Hyung-Suk; Chun, Dong-Il; Kim, Yong-Beom; Kim, Byoung-Min

    2015-01-01

    This report describes a modified anatomic single-bundle anterior cruciate ligament (ACL) reconstruction technique using the FlipCutter guide pin (Arthrex, Naples, FL) as a retrograde drill and a cortical suspensory fixation device (TightRope; Arthrex) with an adjustable graft loop length. Preservation of the ACL remnant as a biological sleeve for the graft is an important issue from the viewpoints of acceleration of revascularization and ligamentization, preservation of the proprioceptive nerve fibers, enhancement of the biological environment for healing, and maintenance of the anchor point at the native tibial attachment, in addition to yielding a lower incidence of tibial bone tunnel enlargement. The goal of our technique is to obtain some advantages of the remnant-preserving technique through an anatomic single-bundle ACL reconstruction, which is performed to minimize damage to the ACL tibial remnant. PMID:26759771

  19. A Newly Discovered Supernova Remnant and MSH 11-62 and 3C58

    NASA Technical Reports Server (NTRS)

    Slane, Patrick O.

    2000-01-01

    CTA 1 is a center-filled supernova remnant (SNR) whose morphology and spectrum indicate the presence of a central pulsar, a synchrotron nebula, and a thermal component associated with the expansion of the blast wave into the interstellar medium. The centrally bright emission surrounds the position of a faint point source of X-rays observed with the ROSAT Position Sensitive Proportional Counter (PSPC). Here we report on Advanced Spacecraft for Cosmology Astrophysics (ASCA) observations that confirm the nonthermal nature of the diffuse emission from the central regions of the remnant. We also present evidence for weak thermal emission that appears to increase in strength toward the outer boundary of the SNR. Thus, CTA 1 appears to be an X-ray composite remnant. Both the aftermath of the explosive supernova event and the energetic compact core are observable.

  20. Optical emission from a fast shock wave - The remnants of Tycho's supernova and SN 1006

    NASA Technical Reports Server (NTRS)

    Chevalier, R. A.; Raymond, J. C.

    1978-01-01

    The faint optical filaments in Tycho's supernova remnant appear to be emission from a shock front moving at 5600 km/s. The intensity of the hydrogen lines, the absence of forbidden lines of heavy elements in the spectrum, and the width of the filaments are explained by a model in which a collisionless shock wave is moving into partially neutral gas. The presence of the neutral gas can be used to set an upper limit of approximately 5 x 10 to the 47th power ergs to the energy in ionizing radiation emitted by a Type I supernova. The patchy neutral gas is probably part of the warm neutral component of the interstellar medium. The existing information on the remnant of SN 1006 indicates that its emission is similar in nature to that from Tycho's remnant.

  1. G306.3-0.9: A Newly Discovered Young Galactic Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Reynolds, Mark T.; Loi, Syheh T.; Murphy, Tara; Miller, Jon M.; Maitra, Dipankar; Gueltekin, Kayhan; Gehrels, Neil; Kennea, Jamie A.; Siegel, Michael H.; Gelbord, Jonathan; Kuin, Paul; Moss, Vanessa; Reeves, Sarah; Robbins, William J.; Gaensler, B. M.; Reis, Rubens C.; Petre, Robert

    2013-01-01

    We present X-ray and radio observations of the new Galactic supernova remnant (SNR) G306.3-0.9, recently discovered by Swift. Chandra imaging reveals a complex morphology, dominated by a bright shock. The X-ray spectrum is broadly consistent with a young SNR in the Sedov phase, implying an age of 2500 yr for a distance of 8 kpc, plausibly identifying this as one of the 20 youngest Galactic SNRs. Australia Telescope Compact Array imaging reveals a prominent ridge of radio emission that correlates with the X-ray emission. We find a flux density of 160 mJy at 1 GHz, which is the lowest radio flux recorded for a Galactic SNR to date. The remnant is also detected at 24µm, indicating the presence of irradiated warm dust. The data reveal no compelling evidence for the presence of a compact stellar remnant.

  2. Simplifying Likelihood Ratios

    PubMed Central

    McGee, Steven

    2002-01-01

    Likelihood ratios are one of the best measures of diagnostic accuracy, although they are seldom used, because interpreting them requires a calculator to convert back and forth between “probability” and “odds” of disease. This article describes a simpler method of interpreting likelihood ratios, one that avoids calculators, nomograms, and conversions to “odds” of disease. Several examples illustrate how the clinician can use this method to refine diagnostic decisions at the bedside.

  3. High Aspect Ratio Wrinkles

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Cheng; Crosby, Alfred

    2015-03-01

    Buckling-induced surface undulations are widely found in living creatures, for instance, gut villi and the surface of flower petal cells. These undulations provide unique functionalities with their extremely high aspect ratios. For the synthetic systems, sinusoidal wrinkles that are induced by buckling a thin film attached on a soft substrate have been proposed to many applications. However, the impact of the synthetic wrinkles have been restricted by limited aspect ratios, ranging from 0 to 0.35. Within this range, wrinkle aspect ratio is known to increase with increasing compressive strain until a critical strain is reached, at which point wrinkles transition to localizations, such as folds or period doublings. Inspired by the living creatures, we propose that wrinkles can be stabilized in high aspect ratio by manipulating the strain energy in the substrate. We experimentally demonstrate this idea by forming a secondary crosslinking network in the wrinkled surface and successfully achieve aspect ratio as large as 0.8. This work not only provides insights for the mechanism of high aspect ratio structures seen in living creatures, but also demonstrates significant promise for future wrinkle-based applications.

  4. Agricultural Intensification Exacerbates Spillover Effects on Soil Biogeochemistry in Adjacent Forest Remnants

    PubMed Central

    Didham, Raphael K.; Barker, Gary M.; Bartlam, Scott; Deakin, Elizabeth L.; Denmead, Lisa H.; Fisk, Louise M.; Peters, Jennifer M. R.; Tylianakis, Jason M.; Wright, Hannah R.; Schipper, Louis A.

    2015-01-01

    Land-use intensification is a central element in proposed strategies to address global food security. One rationale for accepting the negative consequences of land-use intensification for farmland biodiversity is that it could ‘spare’ further expansion of agriculture into remaining natural habitats. However, in many regions of the world the only natural habitats that can be spared are fragments within landscapes dominated by agriculture. Therefore, land-sparing arguments hinge on land-use intensification having low spillover effects into adjacent protected areas, otherwise net conservation gains will diminish with increasing intensification. We test, for the first time, whether the degree of spillover from farmland into adjacent natural habitats scales in magnitude with increasing land-use intensity. We identified a continuous land-use intensity gradient across pastoral farming systems in New Zealand (based on 13 components of farmer input and soil biogeochemistry variables), and measured cumulative off-site spillover effects of fertilisers and livestock on soil biogeochemistry in 21 adjacent forest remnants. Ten of 11 measured soil properties differed significantly between remnants and intact-forest reference sites, for both fenced and unfenced remnants, at both edge and interior. For seven variables, the magnitude of effects scaled significantly with magnitude of surrounding land-use intensity, through complex interactions with fencing and edge effects. In particular, total C, total N, δ15N, total P and heavy-metal contaminants of phosphate fertilizers (Cd and U) increased significantly within remnants in response to increasing land-use intensity, and these effects were exacerbated in unfenced relative to fenced remnants. This suggests movement of livestock into surrounding natural habitats is a significant component of agricultural spillover, but pervasive changes in soil biogeochemistry still occur through nutrient spillover channels alone, even in fenced

  5. Mergers in galaxy groups. I. Structure and properties of elliptical remnants

    SciTech Connect

    Taranu, Dan S.; Dubinski, John; Yee, H. K. C.

    2013-11-20

    We present collisionless simulations of dry mergers in groups of 3 to 25 galaxies to test the hypothesis that elliptical galaxies form at the centers of such groups. Mock observations of the central remnants confirm their similarity to ellipticals, despite having no dissipational component. We vary the profile of the original spiral's bulge and find that ellipticals formed from spirals with exponential bulges have too low Sersic indices. Mergers of spirals with de Vaucouleurs (classical) bulges produce remnants with larger Sersic indices correlated with luminosity, as with Sloan Digital Sky Survey ellipticals. Exponential bulge mergers are better fits to faint ellipticals, whereas classical bulge mergers better match luminous ellipticals. Similarly, luminous ellipticals are better reproduced by remnants undergoing many (>5) mergers, and fainter ellipticals by those with fewer mergers. The remnants follow tight size-luminosity and velocity dispersion-luminosity (Faber-Jackson) relations (<0.12 dex scatter), demonstrating that stochastic merging can produce tight scaling relations if the merging galaxies also follow tight scaling relations. The slopes of the size-luminosity and Faber-Jackson relations are close to observations but slightly shallower in the former case. Both relations' intercepts are offset—remnants are too large but have too low dispersions at fixed luminosity. Some remnants show substantial (v/σ > 0.1) rotational support, although most are slow rotators and few are very fast rotators (v/σ > 0.5). These findings contrast with previous studies concluding that dissipation is necessary to produce ellipticals from binary mergers of spirals. Multiple, mostly minor and dry mergers can produce bright ellipticals, whereas significant dissipation could be required to produce faint, rapidly rotating ellipticals.

  6. Inverse Compton Emission from Galactic Supernova Remnants: Effect of the Interstellar Radiation Field

    SciTech Connect

    Porter, Troy A.; Moskalenko, Igor V.; Strong, Andrew W.; /Garching, Max Planck Inst., MPE

    2006-08-01

    The evidence for particle acceleration in supernova shells comes from electrons whose synchrotron emission is observed in radio and X-rays. Recent observations by the HESS instrument reveal that supernova remnants also emit TeV {gamma}-rays; long awaited experimental evidence that supernova remnants can accelerate cosmic rays up to the ''knee'' energies. Still, uncertainty exists whether these {gamma}-rays are produced by electrons via inverse Compton scattering or by protons via {pi}{sup 0}-decay. The multi-wavelength spectra of supernova remnants can be fitted with both mechanisms, although a preference is often given to {pi}{sup 0}-decay due to the spectral shape at very high energies. A recent study of the interstellar radiation field indicates that its energy density, especially in the inner Galaxy, is higher than previously thought. In this paper we evaluate the effect of the interstellar radiation field on the inverse Compton emission of electrons accelerated in a supernova remnant located at different distances from the Galactic Centre. We show that contribution of optical and infra-red photons to the inverse Compton emission may exceed the contribution of cosmic microwave background and in some cases broaden the resulted {gamma}-ray spectrum. Additionally, we show that if a supernova remnant is located close to the Galactic Centre its {gamma}-ray spectrum will exhibit a ''universal'' cutoff at very high energies due to the Klein-Nishina effect and not due to the cut-off of the electron spectrum. As an example, we apply our calculations to the supernova remnants RX J1713.7-3946 and G0.9+0.1 recently observed by HESS.

  7. Is RX J1713.7-3946 the remnant of the AD393 guest star?

    NASA Astrophysics Data System (ADS)

    Wang, Z. R.; Qu, Q.-Y.; Chen, Y.

    1997-02-01

    A new supernova remnant RX J1713.7-3946 in the constellation Scorpius is suggested to be the remnant of the AD393 guest star. The available historical records of the AD393 guest star are introduced in this letter. According to the ROSAT observation of RX J1713.7-3946 and the historical records of the AD393 guest star, the visual position, distance and age of both RX J1713.7-3949 and the AD393 guest star are in agreement.

  8. Three-dimensional simulations of the expanding remnant of SN 1987A

    NASA Astrophysics Data System (ADS)

    Potter, Toby; Staveley-Smith, Lister; Kirk, John; Reville, Brian; Bicknell, Geoff; Sutherland, Ralph; Wagner, Alexander; Zanardo, Giovanna

    2014-01-01

    SNR 1987A is the expanding remnant from the brightest supernova since the invention of the telescope. The remnant has been monitored extensively in the radio at variety of wavelengths and provides a wealth of data on which to base a simulation. Questions to be answered include estimating the efficiency of particle acceleration at shock fronts, determining the cause of the one-sided radio morphology for SNR 1987A and investigating the gas properties of the pre-supernova environment. We attempt to address these questions using a fully three-dimensional model of SNR 1987A.

  9. QUANTITATIVE EVALUATION OF THE HYPOTHESIS THAT BL LACERTAE OBJECTS ARE QSO REMNANTS

    SciTech Connect

    Borra, E. F.

    2014-11-20

    We evaluate with numerical simulations the hypothesis that BL Lacertae objects (BLLs) are the remnants of quasi-stellar objects. This hypothesis is based on their highly peculiar redshift evolution. They have a comoving space density that increases with decreasing redshift, contrary to all other active galactic nuclei. We assume that relativistic jets are below detection in young radio-quiet quasars and increase in strength with cosmic time so that they eventually are detected as BLLs. Our numerical simulations fit very well the observed redshift distributions of BLLs. There are strong indications that only the high-synchrotron-peaked BLLs could be QSO remnants.

  10. Surveying the South Pole-Aitken basin magnetic anomaly for remnant impactor metallic iron

    NASA Astrophysics Data System (ADS)

    Cahill, Joshua T. S.; Hagerty, Justin J.; Lawrence, David J.; Klima, Rachel L.; Blewett, David T.

    2014-11-01

    The Moon has areas of magnetized crust ("magnetic anomalies"), the origins of which are poorly constrained. A magnetic anomaly near the northern rim of South Pole-Aitken (SPA) basin was recently postulated to originate from remnant metallic iron emplaced by the SPA basin-forming impactor. Here, we remotely examine the regolith of this SPA magnetic anomaly with a combination of Clementine and Lunar Prospector derived iron maps for any evidence of enhanced metallic iron content. We find that these data sets do not definitively detect the hypothesized remnant metallic iron within the upper tens of centimeters of the lunar regolith.

  11. Five Years in the Mid-Infrared Development of the SN 1987A Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Dwek, Eliahu

    2009-01-01

    Spitzer has been used to monitor the mid-IR evolution of SN 1987A over a 5 year period as it develops into a supernova remnant through interaction with its surrounding environment. This interaction is dominated by the collision of the ejecta with the pre-existing equatorial ring. The mid-IR continuum indicates an increasing mass of shock-heated silicate dust, but without any significant change in temperature of the dust grains. Comparison of the IR and X-ray evolution of the remnant can be used to infer plasma conditions and the processing of the dust in the shock-heated X-ray emitting gas.

  12. Two evolved supernova remnants with newly identified Fe-rich cores in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Kavanagh, P. J.; Sasaki, M.; Bozzetto, L. M.; Points, S. D.; Crawford, E. J.; Dickel, J.; Filipović, M. D.; Haberl, F.; Maggi, P.; Whelan, E. T.

    2016-02-01

    Aims: We present a multi-wavelength analysis of the evolved supernova remnants MCSNR J0506-7025 and MCSNR J0527-7104 in the Large Magellanic Cloud. Methods: We used observational data from XMM-Newton, the Australian Telescope Compact Array, and the Magellanic Cloud Emission Line Survey to study their broad-band emission and used Spitzer and H i data to gain a picture of the environment into which the remnants are expanding. We performed a multi-wavelength morphological study and detailed radio and X-ray spectral analyses to determine their physical characteristics. Results: Both remnants were found to have bright X-ray cores, dominated by Fe L-shell emission, which is consistent with reverse shock-heated ejecta with determined Fe masses in agreement with Type Ia explosion yields. A soft X-ray shell, which is consistent with swept-up interstellar medium, was observed in MCSNR J0506-7025, suggestive of a remnant in the Sedov phase. Using the spectral fit results and the Sedov self-similar solution, we estimated the age of MCSNR J0506-7025 to be ~16-28 kyr, with an initial explosion energy of (0.07-0.84) × 1051 erg. A soft shell was absent in MCSNR J0527-7104, with only ejecta emission visible in an extremely elongated morphology that extends beyond the optical shell. We suggest that the blast wave has broken out into a low density cavity, allowing the shock heated ejecta to escape. We find that the radio spectral index of MCSNR J0506-7025 is consistent with the standard -0.5 for supernova remnants. Radio polarisation at 6 cm indicates a higher degree of polarisation along the western front and at the eastern knot with a mean fractional polarisation across the remnant of P ≅ (20 ± 6)%. Conclusions: The detection of Fe-rich ejecta in the remnants suggests that both resulted from Type Ia explosions. The newly identified Fe-rich cores in MCSNR J0506-7025 and MCSNR J0527-7104 make them members of the expanding class of evolved Fe-rich remnants in the Magellanic Clouds

  13. Surveying the South Pole-Aitken basin magnetic anomaly for remnant impactor metallic iron

    USGS Publications Warehouse

    Cahill, Joshua T.S.; Hagerty, Justin J.; Lawrence, David M.; Klima, Rachel L.; Blewett, David T.

    2014-01-01

    The Moon has areas of magnetized crust ("magnetic anomalies"), the origins of which are poorly constrained. A magnetic anomaly near the northern rim of South Pole-Aitken (SPA) basin was recently postulated to originate from remnant metallic iron emplaced by the SPA basin-forming impactor. Here, we remotely examine the regolith of this SPA magnetic anomaly with a combination of Clementine and Lunar Prospector derived iron maps for any evidence of enhanced metallic iron content. We find that these data sets do not definitively detect the hypothesized remnant metallic iron within the upper tens of centimeters of the lunar regolith.

  14. Surprisingly high-pressure shocks in the supernova remnant IC 443

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    The intensities of several lines of molecular hydrogen have been measured from two regions of the supernova-remnant/molecular-cloud shock in IC 443. The lines measured have upper-state energies ranging from 7000 K to 23,000 K. Their relative intensities differ in the two regions, but are consistent with those predicted from the post-shock regions of simple jump-type shocks of different pressure. The pressures so derived are far higher than the pressure in the supernova remnant itself, and a possible reason for this discrepancy is discussed.

  15. Onion-shell model for cosmic ray electrons and radio synchrotron emission in supernova remnants

    NASA Technical Reports Server (NTRS)

    Beck, R.; Drury, L. O.; Voelk, H. J.; Bogdan, T. J.

    1985-01-01

    The spectrum of cosmic ray electrons, accelerated in the shock front of a supernova remnant (SNR), is calculated in the test-particle approximation using an onion-shell model. Particle diffusion within the evolving remnant is explicity taken into account. The particle spectrum becomes steeper with increasing radius as well as SNR age. Simple models of the magnetic field distribution allow a prediction of the intensity and spectrum of radio synchrotron emission and their radial variation. The agreement with existing observations is satisfactory in several SNR's but fails in other cases. Radiative cooling may be an important effect, especially in SNR's exploding in a dense interstellar medium.

  16. Observationally constraining gravitational wave emission from short gamma-ray burst remnants

    NASA Astrophysics Data System (ADS)

    Lasky, Paul D.; Glampedakis, Kostas

    2016-05-01

    Observations of short gamma-ray bursts indicate ongoing energy injection following the prompt emission, with the most likely candidate being the birth of a rapidly rotating, highly magnetized neutron star. We utilize X-ray observations of the burst remnant to constrain properties of the nascent neutron star, including its magnetic field-induced ellipticity and the saturation amplitude of various oscillation modes. Moreover, we derive strict upper limits on the gravitational wave emission from these objects by looking only at the X-ray light curve, showing the burst remnants are unlikely to be detected in the near future using ground-based gravitational wave interferometers, such as Advanced LIGO.

  17. An astrophysics data program investigation of spatial structure of supernova remnants

    NASA Technical Reports Server (NTRS)

    Hughes, John P.

    1993-01-01

    The final report on astrophysics data program investigation of spatial structure of supernova remnants for the period 1 Aug. 1989 to 31 Jul. 1991 is presented. The goal of the project was the study of the spatial structure of supernova remnants (SNR's) as observed in the x-ray band. A number of software tools were developed for the analysis: (1) a program to fit various geometric models to high resolution x-ray data, and (2) programs for Fourier Transform analysis of clumping in SNR's. These programs were applied to high resolution imager (HRI) data on the young galactic SNR's Tycho and Kepler with some success.

  18. Spatially resolved X-ray line spectroscopy of Tycho's supernova remnant

    NASA Technical Reports Server (NTRS)

    Gotthelg, Eric V.; Hwang, Una

    1996-01-01

    Narrow band X-ray images of Tycho's supernova remnant, acquired with the solid-state spectrometer onboard the Advanced Satellite for Cosmology and Astrophysics (ASCA), are presented. The remnant is mapped in several prominent emission lines and in the 1.4 keV to 1.7 keV and 4 keV to 6 keV continua. A spatial resolution of approximately 0.5 min was obtained. No significant correlation was found for Tycho between the X-ray 4 keV to 6 keV continuum and the radio morphology.

  19. Maximum Energies of Shock-Accelerated Electrons in Young Shell Supernova Remnants

    NASA Technical Reports Server (NTRS)

    Reynolds, Stephen P.; Keohane, Jonathan W.; White, Nicholas E. (Technical Monitor)

    1999-01-01

    Young supernova remnants (SNRs) are often assumed to be the source of cosmic rays up to energies approaching the slight steepening in the cosmic ray spectrum at around 1000 TeV, known as the "knee." We show that the observed X-ray emission of 14 radio-bright shell remnants, including all five historical shells, can be used to put limits on E(sub max), the energy at which the electron energy distribution must steepen from its slope at radio-emitting energies. Most of the remnants show thermal spectra, so any synchrotron component must fall below the observed X-ray fluxes. We obtain upper limits on E(sub max) by considering the most rapid physically plausible cutoff in the relativistic electron distribution, an exponential, which is as sharp or sharper than found in any more elaborate models. This maximally curved model then gives us the highest possible E(sub max) consistent with not exceeding observed X-rays. Our results are thus independent of particular models for the electron spectrum in SNRs. Assuming homogeneous emitting volumes with a constant magnetic field strength of 10 uG, no object could reach 1000 TeV, and only one, Kes 73, has an upper limit on E(sub max), above 100 TeV. All the other remnants have limits at or below 80 TeV. E(sub max) is probably set by the finite remnant lifetime rather than by synchrotron losses for remnants younger than a few thousand years, so that an observed electron steepening should be accompanied by steepening at the same energy for protons. More complicated, inhomogeneous models could allow higher values of E(sub max) in parts of the remnant, but the emission-weighted average value, that characteristic of typical electrons, should obey these limits. The young remnants are not expected to improve much over their remaining lives at producing the highest energy Galactic cosmic rays; if they cannot, this picture of cosmic-ray origin may need major alteration.

  20. Influence of various scanning doses on subsequent I-131 ablation of thyroid remnants

    SciTech Connect

    Kim, C.K.; Tse, K.; San Pedro, E. |

    1994-05-01

    In postsurgical patients with thyroid cancer, there is no universal agreement on the I-131 dose for total body scanning as well as on the dose for ablation (ABL) of the thyroid remnant. The objective of this study was to determine (1) whether or not using a higher scanning dose results in a lower success rate on subsequent ABL of thyroid remnant, and (2) whether or not ABL with 100 mCi is more effective than ABL with 30 mCi regardless of the scanning dose.

  1. High-velocity emission in young supernova remnants: SN 1006 and SN 1572

    NASA Technical Reports Server (NTRS)

    Kirshner, Robert; Winkler, P. Frank; Chevalier, Roger A.

    1987-01-01

    The paper reports the discovery of broad H-alpha emission from the SN 1006 remnant with a FWHM velocity of 2600 + or - 100 km/s. This emission is similar to that seen in the remnant of SN 1572 which has a FWHM for H-alpha of 1800 km/s. The nonradiative model was used to interpret the line widths and the derived shock velocity was compared with proper motion measurements to derive distances of 1.4-2.1 kpc to SN 1006 and 2.0-2.8 kpc to SN 1572.

  2. High-velocity emission in young supernova remnants: SN 1006 and SN 1572

    SciTech Connect

    Kirshner, R.; Winkler, P.F.; Chevalier, R.A.

    1987-04-01

    The paper reports the discovery of broad H-alpha emission from the SN 1006 remnant with a FWHM velocity of 2600 + or - 100 km/s. This emission is similar to that seen in the remnant of SN 1572 which has a FWHM for H-alpha of 1800 km/s. The nonradiative model was used to interpret the line widths and the derived shock velocity was compared with proper motion measurements to derive distances of 1.4-2.1 kpc to SN 1006 and 2.0-2.8 kpc to SN 1572. 24 references.

  3. CO J = 1-0 AND J = 2-1 LINE OBSERVATIONS OF THE MOLECULAR-CLOUD-BLOCKED SUPERNOVA REMNANT 3C434.1

    SciTech Connect

    Jeong, Il-Gyo; Koo, Bon-Chul; Cho, Wan-Kee; Kramer, Carsten; Stutzki, Juergen; Byun, Do-Young E-mail: koo@astro.snu.ac.kr

    2013-06-20

    We present the results of CO emission line observations toward the semicircular Galactic supernova remnant (SNR) 3C434.1 (G94.0+1.0). We mapped an area covering the whole SNR in the {sup 12}CO J = 1-0 emission line using the Seoul Radio Astronomy Observatory 6 m telescope and found a large molecular cloud superposed on the faint western part of the SNR. The cloud was elongated along the north-south direction and showed a very good spatial correlation with the radio features of the SNR. We carried out {sup 12}CO J = 2-1 line observations of this cloud using the Koelner Observatorium fuer Sub-Millimeter Astronomie 3 m telescope and found a region in which the {sup 12}CO J = 2-1 to J = 1-0 ratio was high ({approx}1.6). This higher excitation, together with the morphological relation, strongly suggested that the molecular cloud was interacting with the SNR. The systemic velocity of the molecular cloud (-13 km s{sup -1}) gave a kinematic distance of 3.0 kpc to the SNR-molecular cloud system. We derived the physical parameters of the SNR based on this new distance. We examined the variation of the radio spectral index over the remnant and found that it was flatter in the western part, wherein the SNR was interacting with the molecular cloud. We therefore propose that 3C434.1 is the remnant of a supernova explosion that occurred just outside the boundary of a relatively thin, sheet-like molecular cloud. We present a hydrodynamic model showing that its asymmetric radio morphology can result from its interaction with this blocking molecular cloud.

  4. New identifications of extended GeV gamma rays from Supernova Remnants with Fermi-LAT Pass 8 data

    NASA Astrophysics Data System (ADS)

    Hewitt, John; Caragiulo, Micaela; Condon, Benjamin; Giordano, Francesco; Lemoine-Goumard, Marianne; Fermi-LAT Collaboration

    2015-04-01

    Identifying gamma-ray emission from supernova remnants is crucial to test the paradigm for the origin of Galactic cosmic rays. Despite the excellent sensitivity and spatial resolution of the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope, it remains difficult to clearly identify cosmic ray sources buried within the diffuse Galactic background and possibly confused with other gamma-ray sources, such as pulsars. The LAT collaboration has developed a new Pass 8 event reconstruction with improved spatial resolution and acceptance that permits the first detection of extended emission in GeV gamma rays from several supernova remnants. These include the young TeV shell-type remnant RCW 86, and older supernova remnants that are interacting with molecular clouds, such as CTB 37A. The improvements with Pass 8 promise to rapidly grow the population of gamma-ray supernova remnants identified through their spatial extension.

  5. A Recipe for Ratio

    ERIC Educational Resources Information Center

    Moffett, Pamela

    2012-01-01

    Many learners still struggled to appreciate, and understand the difference between, the concepts of fractions and ratio. This is not just a UK phenomenon, which is demonstrated here by the use of a resource developed by the Wisconsin Centre for Education, in association with the Freudenthal Institute of the University of Utrecht, with a group of…

  6. The unfolding instability of the remnant Larsen B Ice Shelf and its tributary glaciers

    NASA Astrophysics Data System (ADS)

    Khazendar, A.; Borstad, C. P.; Scheuchl, B.; Rignot, E. J.; Seroussi, H.

    2014-12-01

    The disintegration of the northern and central parts of the Larsen B Ice Shelf in 2002 demonstrated the strong interaction between ice shelves and their tributary glaciers. The surviving southern part of the ice shelf and its glaciers have hitherto received less attention, based on the assumption that the remnant ice shelf continued to provide the glaciers with sufficient buttressing. Our findings here contradict this view, revealing significant changes since 2002 or earlier from IceBridge altimetry measurements and InSAR-derived flow speeds. The surfaces of Leppard and Flask glaciers directly upstream of their grounding lines lowered persistently by 15 to 20 m in the period 2002-2011. The thinning appears to be dynamic as the flow of both glaciers and the remnant ice shelf accelerated in the same period. Flask in particular started accelerating as early as 2000 almost doubling its flow speed by 2012. These changes are associated with a reduction in the buttressing afforded by the remnant ice shelf and an increase in its fracture as shown by our numerical modeling. One large rift in particular, only 12 km downstream of the grounding line, is revealed by the observations and modeling to be rapidly extending across the ice shelf, defining the likely front of the next large calving event. The increased fracture and continued flow acceleration of the remnant Larsen B Ice Shelf presage its approaching demise.

  7. Endoscopic Submucosal Dissection for Early Gastric Neoplasia Occurring in the Remnant Stomach after Distal Gastrectomy

    PubMed Central

    Lee, Ji Young; Min, Byung-Hoon; Lee, Jung Gyu; Noh, Donghyo; Lee, Jun Haeng; Rhee, Poong-Lyul; Kim, Jae J.

    2016-01-01

    Background/Aims: Endoscopic submucosal dissection (ESD) for tumors occurring in the remnant stomach is technically difficult to perform because of limited working space and severe fibrosis and staples present around the suture line. We aimed to elucidate the feasibility and clinical outcomes of performing ESD for tumors in the remnant stomach. Methods: Between December 2007 and January 2013, 18 patients underwent ESD for tumors (six adenomas and 12 differentiated-type early gastric cancers [EGCs]) occurring in the remnant stomach after distal gastrectomy. Clinicopathologic features and clinical outcomes after ESD were retrospectively analyzed. Results: Two-thirds of the lesions were located on the body, and half were located on the suture line. En bloc resection, R0 resection, and en bloc with R0 resection rates were 88.9%, 100%, and 88.9%, respectively. Curative resection rate for EGC was 91.7%. Perforation occurred in one patient (5.6%) and was successfully managed by endoscopic closure with metallic clips and conservative management. There was no significant bleeding after ESD. During a median follow-up of 47.5 months, no local, metachronous, or extragastric recurrence was seen for either EGC or adenoma lesions. Conclusions: ESD is a feasible and effective treatment modality and can be considered a primary intervention for early gastric neoplasia occurring in the remnant stomach. PMID:26879552

  8. ROSAT observation of a new supernova remnant in the constellation Scorpius.

    NASA Astrophysics Data System (ADS)

    Pfeffermann, E.; Aschenbach, B.

    1996-02-01

    During the ROSAT X-ray all-sky survey a previously unknown extended X-ray source was discovered centered at α(2000) = 17h13m42s, δ(2000) = -39°46″7″ The source has a slightly elliptical shape with a maximum extent of ≡70'. The size, the morphology and the energy spectrum suggest a thermal, shell-type galactic supernova remnant. The X-ray spectrum of the remnant shows pronounced absorption at low energies with significant variation of the absorbing column density across the emission region. The X-ray flux is 4.4×10-10erg cm-2s-1 between 0.1-2.4 keV ranking it among the brightest galactic supernova remnants. The Sedov solution with a canonical SN explosion energy of 1051erg puts the remnant at a distance of 1.1 kpc, with a surprising low age of ≡2100 yr. Two X-ray point sources have been detected in the extended emission region. Candidates for the eastern point source are the Wolf-Rayet star WR 85 embedded in an Hα region of 13' radius (RCW 118) and a G5IA star. A counterpart for the second source could not yet be found.

  9. Vocal cord paralysis following I-131 ablation of a postthyroidectomy remnant

    SciTech Connect

    Lee, T.C.; Harbert, J.C.; Dejter, S.W.; Mariner, D.R.; VanDam, J.

    1985-01-01

    Vocal cord paralysis has been reported following I-131 therapy of thyrotoxicosis and following ablation of the whole thryoid. However, this rare complication has not previously been described following I-131 ablation of a postthyroidectomy remnant. The authors report a patient who required tracheostomy for bilateral vocal cord paralysis following I-131 ablation after near-total thyroidectomy for papillary thyroid carcinoma.

  10. Stepladder incision technique for radical excision of suprasternal thyroglossal duct remnant.

    PubMed

    Ceccanti, Silvia; Frediani, Simone; Morgante, Debora; Iaconelli, Romina; Mele, Ermelinda; Cozzi, Denis A

    2011-10-01

    Thyroglossal duct remnant localized to the suprasternal notch is an exceedingly rare condition. We report on a novel case occurring in an 8-year-old girl who presented with acute onset of a suprasternal abscess. After incision and drainage, a Sistrunk procedure was successfully carried out using 2 stepladder incisions. This approach combined optimal surgical exposure and satisfactory cosmesis. PMID:22008349

  11. Rebleeding of a neck remnant in a case of ruptured aneurysm initially treated with coils.

    PubMed

    Benaissa, Azzedine; Pierot, Laurent

    2016-05-01

    The follow-up and indications for retreatment of intracranial aneurysms treated endovascularly are still a matter of debate. We report the case of a patient with a ruptured aneurysm who was treated twice with coils and regularly followed up with MRI/MR angiography which showed a neck remnant that finally rebled. PMID:25895511

  12. Observations of supernova remnants and pulsar wind nebulae at gamma-ray energies

    NASA Astrophysics Data System (ADS)

    Hewitt, John W.; Lemoine-Goumard, Marianne

    2015-08-01

    In the past few years, gamma-ray astronomy has entered a golden age thanks to two major breakthroughs: Cherenkov telescopes on the ground and the Large Area Telescope (LAT) onboard the Fermi satellite. The sample of supernova remnants (SNRs) detected at gamma-ray energies is now much larger: it goes from evolved supernova remnants interacting with molecular clouds up to young shell-type supernova remnants and historical supernova remnants. Studies of SNRs are of great interest, as these analyses are directly linked to the long standing issue of the origin of the Galactic cosmic rays. In this context, pulsar wind nebulae (PWNe) need also to be considered since they evolve in conjunction with SNRs. As a result, they frequently complicate interpretation of the gamma-ray emission seen from SNRs and they could also contribute directly to the local cosmic ray spectrum, particularly the leptonic component. This paper reviews the current results and thinking on SNRs and PWNe and their connection to cosmic ray production. xml:lang="fr"

  13. A Peculiar Linear Radio Feature In The Supernova Remnant N206

    NASA Astrophysics Data System (ADS)

    Klinger, R. J.; Dickel, J. R.; Fields, B. D.; Milne, D. K.

    We present images of the supernova remnant N206 in the Large Magellanic Cloud, taken with the Australia Telescope Compact Array at 3 and 6 cm. Based on our data and previously published flux densities, the spectral index of N206 is -0.27+-0.06. The 6-cm radio morphology shows a filled center morphology, which along with the spectral index has led us to classify this remnant as Crab-type. Most interesting is the discovery of a peculiar linear feature previously undetected at any wavelength. The feature lies to the east of the center of the remnant, stretching from about one-fourth to three-fourths of the remnant's radius. It is wedge-shaped, with a steady opening angle from an apex on the eastern side. The feature resembles the disturbance expected from an object moving through the material supersonically. We present arguments suggesting that the linear feature may have been produced by the passage of a low-mass companion star ejected at about 800 km/s from a binary system whose other member was the star responsible for the supernova explosion.

  14. Effect of adhesive remnant removal on enamel topography after bracket debonding

    PubMed Central

    Cardoso, Larissa Adrian Meira; Valdrighi, Heloísa Cristina; Vedovello, Mario; Correr, Américo Bortolazzo

    2014-01-01

    INTRODUCTION: At orthodontic treatment completion, knowledge about the effects of adhesive remnant removal on enamel is paramount. OBJECTIVE: This study aimed at assessing the effect of different adhesive remnant removal methods on enamel topography (ESI) and surface roughness (Ra) after bracket debonding and polishing. METHODS: A total of 50 human premolars were selected and divided into five groups according to the method used for adhesive remnant removal: high speed tungsten carbide bur (TCB), Sof-Lex discs (SL), adhesive removing plier (PL), ultrasound (US) and Fiberglass burs (FB). Metal brackets were bonded with Transbond XT, stored at 37oC for 24 hours before debonding with adhesive removing plier. Subsequently, removal methods were carried out followed by polishing with pumice paste. Qualitative and quantitative analyses were conducted with pre-bonding, post-debonding and post-polishing analyses. Results were submitted to statistical analysis with F test (ANOVA) and Tukey's (Ra) as well as with Kruskal-Wallis and Bonferroni tests (ESI) (P < 0.05). RESULTS: US Ra and ESI were significantly greater than TCB, SL, PL and FB. Polishing minimized Ra and ESI in the SL and FB groups. CONCLUSION: Adhesive remnant removal with SL and FB associated with polishing are recommended due to causing little damage to the enamel. PMID:25628087

  15. The influence of thermal pressure on equilibrium models of hypermassive neutron star merger remnants

    SciTech Connect

    Kaplan, J. D.; Ott, C. D.; Roberts, L.; O'Connor, E. P.; Kiuchi, K.; Duez, M.

    2014-07-20

    The merger of two neutron stars leaves behind a rapidly spinning hypermassive object whose survival is believed to depend on the maximum mass supported by the nuclear equation of state (EOS), angular momentum redistribution by (magneto-)rotational instabilities, and spindown by gravitational waves. The high temperatures (∼5-40 MeV) prevailing in the merger remnant may provide thermal pressure support that could increase its maximum mass and, thus, its life on a neutrino-cooling timescale. We investigate the role of thermal pressure support in hypermassive merger remnants by computing sequences of spherically symmetric and axisymmetric uniformly and differentially rotating equilibrium solutions to the general-relativistic stellar structure equations. Using a set of finite-temperature nuclear EOS, we find that hot maximum-mass critically spinning configurations generally do not support larger baryonic masses than their cold counterparts. However, subcritically spinning configurations with mean density of less than a few times nuclear saturation density yield a significantly thermally enhanced mass. Even without decreasing the maximum mass, cooling and other forms of energy loss can drive the remnant to an unstable state. We infer secular instability by identifying approximate energy turning points in equilibrium sequences of constant baryonic mass parameterized by maximum density. Energy loss carries the remnant along the direction of decreasing gravitational mass and higher density until instability triggers collapse. Since configurations with more thermal pressure support are less compact and thus begin their evolution at a lower maximum density, they remain stable for longer periods after merger.

  16. HIGH RESOLUTION 36 GHz IMAGING OF THE SUPERNOVA REMNANT OF SN 1987A

    SciTech Connect

    Potter, T. M.; Staveley-Smith, L.; Zanardo, G.; Ng, C.-Y.; Gaensler, B. M.; Ball, Lewis; Kesteven, M. J.; Manchester, R. N.; Tzioumis, A. K.

    2009-11-01

    The aftermath of supernova (SN) 1987A continues to provide spectacular insights into the interaction between an SN blastwave and its circumstellar environment. We here present 36 GHz observations from the Australia Telescope Compact Array of the radio remnant of SN 1987A. These new images, taken in 2008 April and 2008 October, substantially extend the frequency range of an ongoing monitoring and imaging program conducted between 1.4 and 20 GHz. Our 36.2 GHz images have a diffraction-limited angular resolution of 0.''3-0.''4, which covers the gap between high resolution, low dynamic range VLBI images of the remnant and low resolution, high dynamic range images at frequencies between 1 and 20 GHz. The radio morphology of the remnant at 36 GHz is an elliptical ring with enhanced emission on the eastern and western sides, similar to that seen previously at lower frequencies. Model fits to the data in the Fourier domain show that the emitting region is consistent with a thick inclined torus of mean radius 0.''85, and a 2008 October flux density of 27 +- 6 mJy at 36.2 GHz. The spectral index for the remnant at this epoch, determined between 1.4 GHz and 36.2 GHz, is alpha = -0.83. There is tentative evidence for an unresolved central source with flatter spectral index.

  17. Xanthogranulomatous gastritis of the remnant stomach mimicking a malignant tumor: A case report

    PubMed Central

    OKAMURA, AKIHIKO; TAKAHASHI, TSUNEHIRO; SAIKAWA, YOSHIRO; NAKADAI, JUMPEI; ONO, TAIKI; NAKAMURA, RIEKO; WADA, NORIHITO; KAWAKUBO, HIROFUMI; TAKEUCHI, HIROYA; EMOTO, KATSURA; SASAKI, AYA; KAMEYAMA, KAORI; KITAGAWA, YUKO

    2016-01-01

    Xanthogranulomas are known to develop in the gallbladder and kidney. Xanthogranuloma of the stomach is a rare disease, and to the best of our knowledge, only a few cases have been reported to date. The present patient was a 64-year-old man who underwent a wide resection of the stomach following a Billroth-I reconstruction for a gastric ulcer ~40 years prior to the current presentation. Due to tarry stools, a gastrointestinal endoscopy was performed, leading to identification of an ulcerated gastric lesion located at the previous suture line at the lesser curvature of the remnant stomach. This lesion was elevated, appearing to indicate a submucosal tumor. Positron emission tomography revealed uptake of fluorodeoxyglucose radiotracer by the tumor. Although not indicated by the biopsy specimens, a malignant tumor of the remnant stomach was suspected, in the form of a malignant gastrointestinal tumor or remnant gastric cancer. Curative resection of the tumor was successfully performed. Histological examination of the resected specimens revealed xanthogranulomatous inflammation consisting of foamy histiocytes and plasma cells, however, no cancer cells were observed. The tumor was diagnosed as xanthogranulomatous gastritis that mimicked a malignant tumor of the remnant stomach. The present study therefore indicates that inflammatory tumors should be considered in the differential diagnosis of malignant tumors. PMID:26893759

  18. High resolution X-ray spectroscopy of supernova remnants with ASTRO-H

    NASA Astrophysics Data System (ADS)

    Hughes, John

    The high spectral resolution and sensitivity of the Soft X-ray Spectrometer (SXS) on the upcoming ASTRO-H mission will open a new window of discovery for the study of supernova remnants. In this presentation, I will offer some illustrative examples of the types of science that the ASTRO-H team hopes to pursue. In young, ejecta-dominated remnants, abundance measurements based on emission line diagnostics will allow for a closer link to the different types of supernova progenitor models. Line widths probe ion temperatures and turbulent gas velocities on small scales, while offsets in observed line centroids characterize the bulk expansion motion of a remnant. For older remnants, much of the line-rich thermal plasma arises from shocks in the ambient, interstellar material. SXS observations will address a number of existing concerns with the intepretation of low resolution CCD spectra, including for example the issue of low inferred abundances at the rims of the Cygnus Loop, Puppis A, and others; and the physical origin of recombination-dominated plasmas.

  19. Second Epoch Hubble Space Telescope Observations of Kepler's Supernova Remnant: The Proper Motions of Balmer Filaments

    NASA Astrophysics Data System (ADS)

    Sankrit, Ravi; Raymond, John C.; Blair, William P.; Long, Knox S.; Williams, Brian J.; Borkowski, Kazimierz J.; Patnaude, Daniel J.; Reynolds, Stephen P.

    2016-01-01

    We report on the proper motions of Balmer-dominated filaments in Kepler’s supernova remnant using high resolution images obtained with the Hubble Space Telescope at two epochs separated by about 10 years. We use the improved proper motion measurements and revised values of shock velocities to derive a distance to Kepler of {5.1}-0.7+0.8 kpc. The main shock around the northern rim of the remnant has a typical speed of 1690 km s-1 and is encountering material with densities of about 8 cm-3. We find evidence for the variation of shock properties over small spatial scales, including differences in the driving pressures as the shock wraps around a curved cloud surface. We find that the Balmer filaments ahead of the ejecta knot on the northwest boundary of the remnant are becoming fainter and more diffuse. We also find that the Balmer filaments associated with circumstellar material in the interior regions of the remnant are due to shocks with significantly lower velocities and that the brightness variations among these filaments trace the density distribution of the material, which may have a disk-like geometry. Based on observations made with the Hubble Space Telescope.

  20. AN X-RAY INVESTIGATION OF THREE SUPERNOVA REMNANTS IN THE LARGE MAGELLANIC CLOUD

    SciTech Connect

    Klimek, Matthew D.; Points, S. D.; Smith, R. C.; Shelton, R. L.; Williams, R. E-mail: spoints@ctio.noao.ed E-mail: rls@physast.uga.ed

    2010-12-20

    We have investigated three supernova remnants (SNRs) in the LMC using multi-wavelength data. These SNRs are generally fainter than the known sample (see Section 4) and may represent a previously missed population. One of our SNRs is the second LMC remnant analyzed which is larger than any Galactic remnant for which a definite size has been established. The analysis of such a large remnant contributes to the understanding of the population of highly evolved SNRs. We have obtained X-ray images and spectra of three of these recently identified SNRs using the XMM-Newton observatory. These data, in conjunction with pre-existing optical emission-line images and spectra, were used to determine the physical conditions of the optical- and X-ray-emitting gas in the SNRs. We have compared the morphologies of the SNRs in the different wavebands. The physical properties of the warm ionized shell were determined from the H{alpha} surface brightness and the SNR expansion velocity. The X-ray spectra were fit with a thermal plasma model and the physical conditions of the hot gas were derived from the model fits. Finally, we have compared our observations with simulations of SNR evolution.

  1. LOFAR discovery of a 700-kpc remnant radio galaxy at low redshift

    NASA Astrophysics Data System (ADS)

    Brienza, M.; Godfrey, L.; Morganti, R.; Vilchez, N.; Maddox, N.; Murgia, M.; Orru, E.; Shulevski, A.; Best, P. N.; Brüggen, M.; Harwood, J. J.; Jamrozy, M.; Jarvis, M. J.; Mahony, E. K.; McKean, J.; Röttgering, H. J. A.

    2016-01-01

    Context. Remnant radio galaxies represent the final dying phase of radio galaxy evolution in which the jets are no longer active. Remnants are rare in flux-limited samples, comprising at most a few percent. As a result of their rarity and because they are difficult to identify, this dying phase remains poorly understood and the luminosity evolution is largely unconstrained. Aims: Here we present the discovery and detailed analysis of a large (700 kpc) remnant radio galaxy with a low surface brightness that has been identified in LOFAR images at 150 MHz. Methods: By combining LOFAR data with new follow-up Westerbork observations and archival data at higher frequencies, we investigated the source morphology and spectral properties from 116 to 4850 MHz. By modelling the radio spectrum, we probed characteristic timescales of the radio activity. Results: The source has a relatively smooth, diffuse, amorphous appearance together with a very weak central compact core that is associated with the host galaxy located at z = 0.051. From our ageing and morphological analysis it is clear that the nuclear engine is currently switched off or, at most, active at a very low power state. We find that the source has remained visible in the remnant phase for about 60 Myr, significantly longer than its active phase of 15 Myr, despite being located outside a cluster. The host galaxy is currently interacting with another galaxy located at a projected separation of 15 kpc and a radial velocity offset of ~ 300 km s-1. This interaction may have played a role in the triggering and/or shut-down of the radio jets. Conclusions: The spectral shape of this remnant radio galaxy differs from most of the previously identified remnant sources, which show steep or curved spectra at low to intermediate frequencies. Our results demonstrate that remnant radio galaxies can show a wide range of evolutionary paths and spectral properties. In light of this finding and in preparation for new-generation deep

  2. Coronagraphic imaging of pre-main-sequence stars: Remnant evvelopes of star formation seen in reflection

    NASA Technical Reports Server (NTRS)

    Nakajima, Tadashi; Golimowski, David A.

    1995-01-01

    We have obtained R- and I-band coronagraphic images of the vicinities of 11 pre-main sequence (PMS) stars to search for faint, small-scale reflection nebulae. The inner radius of the search and the field of view are 1.9 arcsec and 1x1 arcmin, respectively. Reflection nebulae were imaged around RY Tau, T Tau,DG Tau, SU Aur, AB Aur, FU Ori, and Z CMa. No nebulae were detected around HBC 347, GG Tau, V773 Tau, and V830 Tau. Categorically speaking, most of the classical T Tauri program stars and all the FU Orionis-type program stars are associated with the reflection nebulae, while none of the weak-line T Tauri program stars are associated with nebulae. The detected nebulae range in size from 250 to 37 000 AU. From the brightness ratios of the stars and nebulae, we obtain a lower limit to the visual extinction of PMS star light through the nebulae of (A(sub V))(sub neb) = 0.1. The lower limits of masses and volume densities of the nebulae associated with the classical T Tauri stars are 10(exp-6) Solar mass and N(sub H) = 10(exp 5)/cu cm, respectively. Lower limits for the nebulae around FU Orionis stars are 10(exp -5) Solar mass and n(sub H) = 10 (exp 5)/cu cm, respectively. Some reflection nebulae may trace the illuminated surfaces of the optically thick dust nebulae, so these mass estimates are not stringent. All the PMS stars with associated nebulae are strong far-infrared emitters. Both the far-infrared emission and the reflection nebulae appear to originate from the remnant envelopes of star formation. The 100 micrometers emitting regions of SU Aur and FU Ori are likely to be cospatial with the reflection nebulae. A spatial discontinuity between FU Ori and its reflection nebula may explain the dip in the far-infrared spectral energy distribution at 60 micrometers. The warped, disk-like nebulae around T Tau and Z CMa are aligned with and embrace the inner star/circumstellar disk systems. The arc-shaped nebula around DG Tau may be in contact with the coaligned inner

  3. Characterizing Supernova Remnant and Molecular Cloud Interaction Sites Using Methanol (CH3OH) Masers

    NASA Astrophysics Data System (ADS)

    McEwen, Bridget; Pihlstrom, Ylva; Sjouwerman, Lorant

    2016-01-01

    Astronomical masers are useful probes of the physical conditions of the gas in which they are formed. Masers form under specific physical conditions and therefore, can be used to trace distinct environments. In particular, collisionally excited 36 and 44 GHz methanol (CH3OH) and 1720 MHz hydroxl (OH) masers are found associated with shocked gas produced by the interaction between supernova remnants (SNRs) and molecular clouds (MCs). The overall goal of my thesis research is to combine modeling and observations to characterize the properties and formation of CH3OH masers in these SNR/MC interaction regions. More accurate information of the density (and density gradients) could, for example, be used as inputs or constraints for models of SNR cosmic ray acceleration. In this talk, I will present results from calculations of the physical conditions necessary for the occurence of 36.169, 44.070, 84.521, and 95.169 GHz CH3OH maser lines near SNRs, using a coupled radiative transfer and level population code. The modeling shows that given a sufficient CH3OH abundance, CH3OH maser emission arises over a wide range of densities and temperatures, with optimal conditions at n ~ 104 to 106 cm-3 and T > 60 K, overlapping with masing conditions for OH masers. Furthermore, the 36 and 44 GHz transitions display more significant maser optical depths compared to the 84 and 95 GHz transitions over the majority of the physical conditions. The line intensity ratios between multiple transitions significantly change with altering physical conditions and can be used to constrain the physical parameters of the gas where CH3OH masers are detected. I use the modeling results as a diagnostic tool to interpret the observational results of a sample of SNRs with previous and recent CH3OH maser detections (G1.4-0.1, W28, Sgr A East, G5.7-0.0, W44 and W51C). I will also discuss the close spatial and kinematic correlation of CH3OH masers and ammonia (NH3 (3,3)) emission peaks, which is a reliable

  4. Thin shell formation in radiative shocks. 1: Supernova remnants in low-density media

    NASA Technical Reports Server (NTRS)

    Franco, Jose; Miller, Walter Warren, III; Arthur, S. J.; Tenorio-Tagle, Guillermo; Terlevich, Roberto

    1994-01-01

    This paper explores the onset of thin-shell formation in interstellar shocks associated with supernova explosions. We outline a simple but useful scheme that indicates the time at which thin shell formation begins for supernova remnants (SNRs) evolving in a range of interstellar environments, extending the previous analytical models to arbitrary power-law density media. The result depends on the gas cooling properties and the shock velocity and radius. This is then applied to the specific case of SNRs in low-density media. The procedure for defining the time for the onset of shell formation, t(sub sf), equates the value of the adiabat, kappa = p/rho(exp gamma), to zero using the known time dependence of the shock radius and velocity. For the case of a power-law density ambient medium of the form rho(r) = Br(exp -omega), it is found that shell formation can be prevented when the ambient density drops faster than a critical rate. For a cooling function of the form Lambda = Lambda(sub 0) tau(exp beta), with beta = -0.5 (appropriate for line cooling), shell formation never occurs for omega greater than or equal to 9/5. The shell formation time is then computed for spherical shocks in a power-law density medium. For omega = 0, the onset of shell formation is found to be at t(sub sf) approx. equal to 2.87 x 10(exp 4) E51(exp 3/14) n(sub 0 exp -4.7) yr, which agrees well with previous estimates derived by other means. We compare the analytical shell formation time with the results of detailed numerical models for omega = 0 and three different ambient densities and find good agreement. The extension of the criterion for the onset of thin shell formation using the ratio of cooling to swept-up column density is also described. This method provides a useful approximation for cases when the exact solution is not known.

  5. Housing shortages in urban regions: aggressive interactions at tree hollows in forest remnants.

    PubMed

    Davis, Adrian; Major, Richard E; Taylor, Charlotte E

    2013-01-01

    Urbanisation typically results in a reduction of hollow-bearing trees and an increase in the density of particularly species, potentially resulting in an increased level of competition as cavity-nesting species compete for a limited resource. To improve understanding of hollow usage between urban cavity-nesting species in Australia, particularly parrots, we investigated how the hollow-using assemblage, visitation rate, diversity and number of interactions varied between hollows within urban remnant forest and continuous forest. Motion-activated video cameras were installed, via roped access to the canopy, and hollow usage was monitored at 61 hollows over a two-year period. Tree hollows within urban remnants had a significantly different assemblage of visitors to those in continuous forest as well as a higher rate of visitation than hollows within continuous forest, with the rainbow lorikeet making significantly more visitations than any other taxa. Hollows within urban remnants were characterised by significantly higher usage rates and significantly more aggressive interactions than hollows within continuous forest, with parrots responsible for almost all interactions. Within urban remnants, high rates of hollow visitation and both interspecific and intraspecific interactions observed at tree hollows suggest the number of available optimal hollows may be limiting. Understanding the usage of urban remnant hollows by wildlife, as well as the role of parrots as a potential flagship for the conservation of tree-hollows, is vital to prevent a decrease in the diversity of urban fauna, particularly as other less competitive species risk being outcompeted by abundant native species. PMID:23555657

  6. The evolving instability of the remnant Larsen B Ice Shelf and its tributary glaciers

    NASA Astrophysics Data System (ADS)

    Khazendar, Ala; Borstad, Christopher P.; Scheuchl, Bernd; Rignot, Eric; Seroussi, Helene

    2015-06-01

    Following the 2002 disintegration of the northern and central parts of the Larsen B Ice Shelf, the tributary glaciers of the southern surviving part initially appeared relatively unchanged and hence assumed to be buttressed sufficiently by the remnant ice shelf. Here, we modify this perception with observations from IceBridge altimetry and InSAR-inferred ice flow speeds. Our analyses show that the surfaces of Leppard and Flask glaciers directly upstream from their grounding lines lowered by 15 to 20 m in the period 2002-2011. The thinning appears to be dynamic as the flow of both glaciers and the remnant ice shelf accelerated in the same period. Flask Glacier started accelerating even before the 2002 disintegration, increasing its flow speed by ∼55% between 1997 and 2012. Starbuck Glacier meanwhile did not change much. We hypothesize that the different evolutions of the three glaciers are related to their dissimilar bed topographies and degrees of grounding. We apply numerical modeling and data assimilation that show these changes to be accompanied by a reduction in the buttressing afforded by the remnant ice shelf, a weakening of the shear zones between its flow units and an increase in its fracture. The fast flowing northwestern part of the remnant ice shelf exhibits increasing fragmentation, while the stagnant southeastern part seems to be prone to the formation of large rifts, some of which we show have delimited successive calving events. A large rift only 12 km downstream from the grounding line is currently traversing the stagnant part of the ice shelf, defining the likely front of the next large calving event. We propose that the flow acceleration, ice front retreat and enhanced fracture of the remnant Larsen B Ice Shelf presage its approaching demise.

  7. Searching for the Remnants of Southern Seas: Cassini Observations of the South Pole of Titan

    NASA Astrophysics Data System (ADS)

    Stofan, Ellen R.; Aharonson, O.; Hayes, A. G.; Kirk, R.; Lopes, R.; Lorenz, R. D.; Lucas, A.; Lunine, J. I.; Malaska, M.; Radebaugh, J.; Stiles, B. W.; Turtle, E. P.; Wall, S. D.; Wood, C. A.; Cassini Radar Team

    2012-10-01

    The north polar region of Titan is home to three large seas along with hundreds of smaller lakes, while the south pole apparently has only two partially filled basins of liquid hydrocarbons. Aharonson et al. [2009] has suggested that cycles analogous to Croll-Milankovich cycles on Earth cause long-term cyclic transfer of hydrocarbons from pole to pole, with the north pole now containing the bulk of the liquids. Less than 50,000 years ago, the cycle would have been reversed, suggesting that the south polar region should contain remnants of southern seas. To identify such seas, we search for features enclosed by an apparent remnant shoreline, with an interior region of smooth (radar-dark) plains. Two such features can be readily identified, each with areal extents of over 100,000 km2, along with several other possible candidate remnant seas or large lakes. One of the possible seas now contains Ontario Lacus. Analysis of the morphologic and topographic characteristics of the two candidate remnant seas can help constrain the possible depth and basin characteristics of the northern seas, as well as possible rates of surface modification in the time since the seas have (largely) dried up. In addition, analysis of the radar characteristics of the remnant sea basins may help us to determine if such processes also acted at equatorial regions where evidence of rainfall [Turtle et al., 2011] and a possible lake has recently been presented [Griffith et al., 2012], and at the more homogeneous mid-latitudes on Titan. References: Aharonson, O. et al., Nature Geoscience 2, 851-854; Griffith, C. et al., Nature 486, 237-239; Turtle, E.P. et al., Science 331, 1414-1417.

  8. Housing Shortages in Urban Regions: Aggressive Interactions at Tree Hollows in Forest Remnants

    PubMed Central

    Davis, Adrian; Major, Richard E.; Taylor, Charlotte E.

    2013-01-01

    Urbanisation typically results in a reduction of hollow-bearing trees and an increase in the density of particularly species, potentially resulting in an increased level of competition as cavity-nesting species compete for a limited resource. To improve understanding of hollow usage between urban cavity-nesting species in Australia, particularly parrots, we investigated how the hollow-using assemblage, visitation rate, diversity and number of interactions varied between hollows within urban remnant forest and continuous forest. Motion-activated video cameras were installed, via roped access to the canopy, and hollow usage was monitored at 61 hollows over a two-year period. Tree hollows within urban remnants had a significantly different assemblage of visitors to those in continuous forest as well as a higher rate of visitation than hollows within continuous forest, with the rainbow lorikeet making significantly more visitations than any other taxa. Hollows within urban remnants were characterised by significantly higher usage rates and significantly more aggressive interactions than hollows within continuous forest, with parrots responsible for almost all interactions. Within urban remnants, high rates of hollow visitation and both interspecific and intraspecific interactions observed at tree hollows suggest the number of available optimal hollows may be limiting. Understanding the usage of urban remnant hollows by wildlife, as well as the role of parrots as a potential flagship for the conservation of tree-hollows, is vital to prevent a decrease in the diversity of urban fauna, particularly as other less competitive species risk being outcompeted by abundant native species. PMID:23555657

  9. Deep Radio Imaging with MERLIN of the Supernova Remnants in M82

    NASA Astrophysics Data System (ADS)

    Muxlow, T. W. B.; Pedlar, A.; Riley, J. D.; McDonald, A. R.; Beswick, R. J.; Wills, K. A.

    An 8 day MERLIN deep integration at 5GHz of the central region of the starburst galaxy M82 has been used to investigate the radio structure of a number of supernova remnants in unprecedented detail revealing new shells and partial shell structures for the first time. In addition, by comparing the new deep 2002 image with an astrometrically aligned image from 36 hours of data taken in 1992, it has been possible to directly measure the expansion velocities of 4 of the most compact remnants in M82. For the two most compact remnants, 41.95+575 and 43.31+592, expansion velocities of 2800 ± 300 km s-1 and 8750 ± 400 km s-1 have been derived. These confirm and refine the measured expansion velocities which have been derived from VLBI multi-epoch studies. For remnants 43.18+583 and 44.01+596, expansion velocities of 10500 ± 750 km s -1 and 2400 ± 250 km s-1 have been measured for the first time. In addition, the peak of the radio emission for SNR 45.17+612 has moved between the two epochs implying velocities around 7500km s-1. The relatively compact remnants in M82 are thus found to be expanding over a wide range of velocities which appear unrelated to their size. The new 2002 map is the most sensitive high-resolution image yet made of M82, achieving an rms noise level of 17µJy beam-1. This establishes a first epoch for subsequent deep studies of expansion velocities for many SNR within M82.

  10. A High-Resolution X-ray Atlas of Supernova Remnants in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Williams, R. M.; Chu, Y.-H.; Dickel, J. R.; Petre, R.; Smith, R. C.; Tavarez, M.

    1998-12-01

    The Large Magellanic Cloud (LMC) presents a unique opportunity to study a large and varied sample of supernova remnants (SNRs), at a common distance ( ~ 50 kpc) and with little interstellar obscuration. These factors allow us to avoid the uncertainties in distances and absorptions that plague the study of Galactic SNRs. Reasonable resolutions can be achieved for LMC SNRs with current instruments in the X-ray, optical, and radio regimes; thus, they can be studied at a level of detail unrivaled by most extragalactic remnants. LMC remnants cover the range of evolutionary stages, from the newly forming SNR of SN 1987A, to the largest remnant yet known (SNR 0450-709, 104x75 pc). They arise from both Type I and Type II progenitors, and expand into environments ranging from a stellar-wind bubble to an HII complex. This extensive sample allows us to examine SNRs both individually and as a group. We can study specific processes such as the collision of two SNRs (DEML316), SNR breakouts (N11L, N86), the expansion of an SNR in a cloudy medium (N63A), Crab-type SNRs (N158A, N157B), and unusual SNR structures (Honeycomb SNR). More importantly, we can identify common features between SNRs and correlate these with their evolutionary states and environments. In this poster we present a high-resolution atlas of the X-ray emission from LMC SNRs, and use the X-ray morphologies to examine SNR conditions and structures. We find five types of SNRs in the LMC. While the Peaked Emission SNRs are dominated by a pulsar-powered nebula, and the Irregular SNRs by the details of their environments, the remaining three categories (Shell, Diffuse Face, and Centrally Peaked) seem to represent an evolutionary trend, as shown by their correlation with remnant sizes. We will discuss the intriguing implications of our findings for SNR development and interactions with the interstellar medium.

  11. 3-D Model of Broadband Emission from Supernova Remnants Undergoing Non-linear Diffusive Shock Acceleration

    SciTech Connect

    Lee, Shiu-Hang; Kamae, Tuneyoshi; Ellison, Donald C.

    2008-07-02

    We present a 3-dimensional model of supernova remnants (SNRs) where the hydrodynamical evolution of the remnant is modeled consistently with nonlinear diffusive shock acceleration occurring at the outer blast wave. The model includes particle escape and diffusion outside of the forward shock, and particle interactions with arbitrary distributions of external ambient material, such as molecular clouds. We include synchrotron emission and cooling, bremsstrahlung radiation, neutral pion production, inverse-Compton (IC), and Coulomb energy-loss. Boardband spectra have been calculated for typical parameters including dense regions of gas external to a 1000 year old SNR. In this paper, we describe the details of our model but do not attempt a detailed fit to any specific remnant. We also do not include magnetic field amplification (MFA), even though this effect may be important in some young remnants. In this first presentation of the model we don't attempt a detailed fit to any specific remnant. Our aim is to develop a flexible platform, which can be generalized to include effects such as MFA, and which can be easily adapted to various SNR environments, including Type Ia SNRs, which explode in a constant density medium, and Type II SNRs, which explode in a pre-supernova wind. When applied to a specific SNR, our model will predict cosmic-ray spectra and multi-wavelength morphology in projected images for instruments with varying spatial and spectral resolutions. We show examples of these spectra and images and emphasize the importance of measurements in the hard X-ray, GeV, and TeV gamma-ray bands for investigating key ingredients in the acceleration mechanism, and for deducing whether or not TeV emission is produced by IC from electrons or pion-decay from protons.

  12. X-Ray Synchrotron Emission From 10-100 TeV Cosmic-Ray Electrons In The Supernova Remnant SN 1006

    NASA Technical Reports Server (NTRS)

    Allen, G. E.; Petre, R.; Gotthelf, E. V.

    2001-01-01

    We present the results of a joint spectral analysis of RXTE PCA, ASCA SIS, and ROSAT PSPC data of the supernova remnant SN 1006. This work represents the first attempt to model both the thermal and nonthermal X-ray emission over the entire X-ray energy band from 0.12 to 17 key. The thermal flux is described by a nonequilibrium ionization model with an electron temperature kTe = 0.6 key, an ionization timescale n(sub 0)t = 9 x 10(exp 9)/cc s, and a relative elemental abundance of silicon that is 10 - 18 times larger than the solar abundance. The nonthermal X-ray spectrum is described by a broken power law model with low- and high-energy photon indices Gamma(sub 1) = 2.1 and Gamma(sub 2) = 3.0, respectively. Since the nonthermal X-ray spectrum steepens with increasing energy, the results of the present analysis corroborate previous claims that the nonthermal X-ray emission is produced by synchrotron radiation. We argue that the magnetic field strength is significantly larger than previous estimates of about 10 micro G and arbitrarily use a value of 40 micro G to estimate the parameters of the cosmic-ray electron, proton, and helium spectra of the remnant. The results for the ratio of the number densities of protons and electrons (R = 160 at 1 GeV), the total energy in cosmic rays (E(sub cr) = 1 x 10(exp 50) ergs), and the spectral index of the electrons at 1 GeV (Gamma(sub e) = 2.14 +/- 0.12) are consistent with the hypothesis that Galactic cosmic rays are accelerated predominantly in the shocks of supernova remnants. Yet, the remnant may or may not accelerate nuclei to energies as high as the energy of the "knee," depending on the reason why the maximum energy of the electrons is only 10 TeV.

  13. The End of Amnesia: A New Method for Measuring the Metallicity of Type Ia Supernova Progenitors Using Manganese Lines in Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Badenes, Carles; Bravo, Eduardo; Hughes, John P.

    2008-06-01

    We propose a new method to measure the metallicity of Type Ia supernova progenitors using Mn and Cr lines in the X-ray spectra of young supernova remnants. We show that the Mn-to-Cr mass ratio in Type Ia supernova ejecta is tightly correlated with the initial metallicity of the progenitor, as determined by the neutron excess of the white dwarf material before thermonuclear runaway. We use this correlation, together with the flux of the Cr and Mn Kα X-ray lines in the Tycho supernova remnant recently detected by Suzaku, to derive a metallicity of log (Z) = - 1.32+ 0.67-0.33 for the progenitor of this supernova, which corresponds to log (Z/Z⊙) = 0.60+ 0.31-0.60 according to the latest determination of the solar metallicity by Asplund and coworkers. The uncertainty in the measurement is large, but metallicities much smaller than the solar value can be confidently discarded. We discuss the implications of this result for future research on Type Ia supernova progenitors.

  14. An X-Ray and Radio Study of the Varying Expansion Velocities in Tycho’s Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Williams, Brian J.; Chomiuk, Laura; Hewitt, John W.; Blondin, John M.; Borkowski, Kazimierz J.; Ghavamian, Parviz; Petre, Robert; Reynolds, Stephen P.

    2016-06-01

    We present newly obtained X-ray and radio observations of Tycho’s supernova remnant using Chandra and the Karl G. Jansky Very Large Array in 2015 and 2013/14, respectively. When combined with earlier epoch observations by these instruments, we now have time baselines for expansion measurements of the remnant of 12–15 years in the X-rays and 30 years in the radio. The remnant’s large angular size allows for proper motion measurements at many locations around the periphery of the blast wave. Consistent with earlier measurements, we find a clear gradient in the expansion velocity of the remnant, despite its round shape. The proper motions on the western and southwestern sides of the remnant are about a factor of two higher than those in the east and northeast. We showed in an earlier work that this is related to an offset of the explosion site from the geometric center of the remnant due to a density gradient in the ISM, and using our refined measurements reported here, we find that this offset is ∼23″ toward the northeast. An explosion center offset in such a circular remnant has implications for searches for progenitor companions in other remnants.

  15. Initial hepatic removal of chylomicron remnants is unaffected but endocytosis is delayed in mice lacking the low density lipoprotein receptor.

    PubMed Central

    Herz, J; Qiu, S Q; Oesterle, A; DeSilva, H V; Shafi, S; Havel, R J

    1995-01-01

    Two endocytic receptors, the low density lipoprotein (LDL) receptor (LDLR) and the LDLR-related protein (LRP), are thought to act in concert in the hepatic uptake of partially metabolized dietary lipoproteins, the chylomicron remnants. We have evaluated the role of these two receptors in the hepatic metabolism of chylomicron remnants in normal mice and in LDLR-deficient [LDLR (-/-)] mice. The rate of chylomicron remnant removal by the liver was normal up to 30 min after intravenous injection of chylomicrons into LDLR (-/-) mice and was unaffected by receptor-associated protein (RAP), a potent inhibitor of ligand binding to LRP. In contrast, endocytosis of the remnants by the hepatocytes, measured by their accumulation in the endosomal fraction and by the rate of hydrolysis of component cholesteryl esters, was dramatically reduced in the absence of the LDLR. Coadministration of RAP prevented the continuing hepatic removal of chylomicron remnants in LDL (-/-) mice after 30 min, consistent with blockade of the slow endocytosis by a RAP-sensitive process. Taken together with previous studies, our results are consistent with a model in which the initial hepatic removal of chylomicron remnants is primarily mediated by mechanisms that do not include LDLR or LRP, possibly involving glycosaminoglycan-bound hepatic lipase and apolipoprotein E. After the remnants bind to these alternative sites on the hepatocyte surface, endocytosis is predominantly mediated by the LDLR and also by a slower and less efficient backup process that is RAP sensitive and therefore most likely involves LRP. PMID:7753850

  16. Fingerprints of the First Stars: The Discovery of Possible Population III Remnants at Redshift 3.5

    NASA Astrophysics Data System (ADS)

    O'Meara, John; Crighton, Neil H. M.; Murphy, Michael

    2016-01-01

    The first stars, known as population III, produced the first heavy elements, thereby enriching their surrounding pristine gas. However, previous detections of metals in intergalactic gas clouds find a heavy element enrichment 1/1000 to ˜ 1 times that of the solar environment, which is higher than expected for population III remnants. Here, we report the discovery of a Lyman limit system at redshift 3.53 with the lowest metallicity seen in gas with discernable metals, 10^(-3.44±0.24) times the solar value. The carbon-to-silicon abundance ratio is 10^(-0.21±0.16) times the solar value, and the metals are offset in velocity by 6 to 10 km/s from the bulk of the hydrogen. These properties are all consistent with enrichment by a population III star formation event. A recent enrichment scenario by population II stars cannot be ruled out, but the large cloud size (> 30 kpc) suggests it is not part of a cold accretion stream, and the 400 km/s velocity width of the system suggests it is not in a low-mass halo. Relative abundance measurements in this near-pristine regime open a new avenue for testing models of early gas enrichment and metal mixing.

  17. An atlas of supernova remnant candidates in Messier 31

    NASA Technical Reports Server (NTRS)

    Braun, R.; Walterbos, R. A. M.

    1993-01-01

    Narrow-band CCD imagery in H-alpha and forbidden SII of a large fraction of the spiral arms in the Northeast half of Messier 31 has been used to isolate a sample of 52 'forbidden-line' SNR candidates for which the integrated ratio forbidden SII:H-alpha is greater than 0.5. An atlas of images in these emission lines, red optical continuum, and 1465 MHz radio continuum is presented, together with the tabulated integral properties of these sources. Assessing the completeness of the sample yields a crude estimate of the massive supernova rate (due to stars more massive than 7 solar masses) of 1 in 80 yr. The range of measured luminosities in both H-alpha and radio continuum is fully consistent with those found for 'forbidden-line' SNR in Messier 33, the LMC, and the Galaxy. With the inclusion of our candidates the number of extragalactic SNRs (with well-known distances) now exceeds the number of known galactic SNRs.

  18. Chylomicron remnants and nonesterified fatty acids differ in their ability to inhibit genes involved in lipogenesis in rats.

    PubMed

    Kohan, Alison B; Qing, Yang; Cyphert, Holly A; Tso, Patrick; Salati, Lisa M

    2011-02-01

    Primary hepatocytes treated with nonesterified PUFA have been used as a model for analyzing the inhibitory effects of dietary polyunsaturated fats on lipogenic gene expression. Although nonesterified fatty acids play an important signaling role in starvation, they do not completely recapitulate the mechanism of dietary fat presentation to the liver, which is delivered via chylomicron remnants. To test the effect of remnant TG on lipogenic enzyme expression, chylomicron remnants were generated from the lymph of rats intubated with either safflower oil or lard. The remnants were added to the medium of primary rat hepatocytes in culture and the accumulation of mRNA for genes involved in carbohydrate and lipid metabolism was measured. Both PUFA-enriched remnants and nonesterified PUFA inhibited the expression and maturation of sterol response element binding protein-1c (SREBP-1c) and the expression of lipogenic genes regulated by this transcription factor. These remnants also inhibited the expression of glucose-6-phosphate dehydrogenase (G6PD), a gene regulated at post-transcriptional steps. In contrast, PUFA-enriched remnants did not inhibit the accumulation of mRNA for malic enzyme, glucokinase, and L-pyruvate kinase, whereas nonesterified fatty acids caused a decrease in these mRNA. These genes are regulated independently of SREBP-1c. SFA-enriched remnants did not inhibit lipogenic gene expression, which is consistent with a lack of inhibition of lipogenesis by dietary saturated fats. Thus, the inhibitory action of dietary polyunsaturated fats on lipogenesis involves a direct action of chylomicron remnants on the liver. PMID:21169224

  19. Putative Nanobacteria Represent Physiological Remnants and Culture By-Products of Normal Calcium Homeostasis

    PubMed Central

    Young, John D.; Young, Lena; Wu, Cheng-Yeu; Young, Andrew

    2009-01-01

    Putative living entities called nanobacteria (NB) are unusual for their small sizes (50–500 nm), pleomorphic nature, and accumulation of hydroxyapatite (HAP), and have been implicated in numerous diseases involving extraskeletal calcification. By adding precipitating ions to cell culture medium containing serum, mineral nanoparticles are generated that are morphologically and chemically identical to the so-called NB. These nanoparticles are shown here to be formed of amorphous mineral complexes containing calcium as well as other ions like carbonate, which then rapidly acquire phosphate, forming HAP. The main constituent proteins of serum-derived NB are albumin, fetuin-A, and apolipoprotein A1, but their involvement appears circumstantial since so-called NB from different body fluids harbor other proteins. Accordingly, by passage through various culture media, the protein composition of these particles can be modulated. Immunoblotting experiments reveal that antibodies deemed specific for NB react in fact with either albumin, fetuin-A, or both, indicating that previous studies using these reagents may have detected these serum proteins from the same as well as different species, with human tissue nanoparticles presumably absorbing bovine serum antigens from the culture medium. Both fetal bovine serum and human serum, used earlier by other investigators as sources of NB, paradoxically inhibit the formation of these entities, and this inhibition is trypsin-sensitive, indicating a role for proteins in this inhibitory process. Fetuin-A, and to a lesser degree albumin, inhibit nanoparticle formation, an inhibition that is overcome with time, ending with formation of the so-called NB. Together, these data demonstrate that NB are most likely formed by calcium or apatite crystallization inhibitors that are somehow overwhelmed by excess calcium or calcium phosphate found in culture medium or in body fluids, thereby becoming seeds for calcification. The structures

  20. Putative nanobacteria represent physiological remnants and culture by-products of normal calcium homeostasis.

    PubMed

    Young, John D; Martel, Jan; Young, Lena; Wu, Cheng-Yeu; Young, Andrew; Young, David

    2009-01-01

    Putative living entities called nanobacteria (NB) are unusual for their small sizes (50-500 nm), pleomorphic nature, and accumulation of hydroxyapatite (HAP), and have been implicated in numerous diseases involving extraskeletal calcification. By adding precipitating ions to cell culture medium containing serum, mineral nanoparticles are generated that are morphologically and chemically identical to the so-called NB. These nanoparticles are shown here to be formed of amorphous mineral complexes containing calcium as well as other ions like carbonate, which then rapidly acquire phosphate, forming HAP. The main constituent proteins of serum-derived NB are albumin, fetuin-A, and apolipoprotein A1, but their involvement appears circumstantial since so-called NB from different body fluids harbor other proteins. Accordingly, by passage through various culture media, the protein composition of these particles can be modulated. Immunoblotting experiments reveal that antibodies deemed specific for NB react in fact with either albumin, fetuin-A, or both, indicating that previous studies using these reagents may have detected these serum proteins from the same as well as different species, with human tissue nanoparticles presumably absorbing bovine serum antigens from the culture medium. Both fetal bovine serum and human serum, used earlier by other investigators as sources of NB, paradoxically inhibit the formation of these entities, and this inhibition is trypsin-sensitive, indicating a role for proteins in this inhibitory process. Fetuin-A, and to a lesser degree albumin, inhibit nanoparticle formation, an inhibition that is overcome with time, ending with formation of the so-called NB. Together, these data demonstrate that NB are most likely formed by calcium or apatite crystallization inhibitors that are somehow overwhelmed by excess calcium or calcium phosphate found in culture medium or in body fluids, thereby becoming seeds for calcification. The structures described