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Sample records for 1987a sn 1987a

  1. SN1987A's Twentieth Anniversary

    NASA Astrophysics Data System (ADS)

    2007-02-01

    Looking back at 20 Years of Observations of this Supernova with ESO telescopes The unique supernova SN 1987A has been a bonanza for astrophysicists. It provided several observational 'firsts,' like the detection of neutrinos from an exploding star, the observation of the progenitor star on archival photographic plates, the signatures of a non-spherical explosion, the direct observation of the radioactive elements produced during the blast, observation of the formation of dust in the supernova, as well as the detection of circumstellar and interstellar material. ESO PR Photo 08a/07 ESO PR Photo 08a/07 SN1987A in the Large Magellanic Cloud Today, it is exactly twenty years since the explosion of Supernova 1987A in the Large Magellanic Cloud was first observed, at a distance of 163,000 light-years. It was the first naked-eye supernova to be seen for 383 years. Few events in modern astronomy have met with such an enthusiastic response by the scientists and now, after 20 years, it continues to be an extremely exciting object that is further studied by astronomers around the world, in particular using ESO's telescopes. When the first signs of Supernova 1987A, the first supernova of the year 1987, were noticed early on 24 February of that year, it was clear that this would be an unusual event. It was discovered by naked-eye and on a panoramic photographic plate taken with a 10-inch astrograph on Las Campanas in Chile by Oscar Duhalde and Ian Shelton, respectively. A few hours earlier, still on 23 February, two large underground detectors - in Japan and the USA - had registered the passage of high-energy neutrinos. Since SN 1987A exploded in the Large Magellanic Cloud (LMC), it was only accessible to telescopes in the Southern Hemisphere, more particularly in Australia, South Africa, and South America. In Chile, ESO's observatory at La Silla with its armada of telescopes with sizes between 0.5 and 3.6-m, played an important role. ESO PR Photo 08c/07 ESO PR Photo 08c/07 The

  2. 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.

  3. Axions and SN1987A

    NASA Technical Reports Server (NTRS)

    Burrows, Adam; Turner, Michael S.; Brinkmann, R. P.

    1988-01-01

    The effect of free-streaming axion emission on numerical models for the cooling of the newly born neutron star associated with SN1987A is considered. It is found that for an axion mass of greater than approximately 10 to the -3 eV, axion emission shortens the duration of the expected neutrino burst so significantly that it would be inconsistent with the neutrino observations made by the Kamiokande II and Irvine-Michigan-Brookhaven detectors. However, the possibility has not been investigated that axion trapping (which should occur for masses greater than or equal to 0.02 eV) sufficiently reduces axion emission so that axion masses greater than approximately 2 eV would be consistent with the neutrino observations.

  4. Dirac neutrinos and SN 1987A

    NASA Technical Reports Server (NTRS)

    Turner, Michael S.

    1991-01-01

    Previous work has shown that the cooling of SN 1987A excludes a Dirac-neutrino mass greater than theta(20 keV) for nu(sub e), nu(sub mu), or nu(sub tau). The emission of wrong-helicity, Dirac neutrinos from SN 1987A, is re-examined. It is concluded that the effect of a Dirac neutrino on the cooling of SN 1987A has been underestimated due to neutrino degeneracy and additional emission processes. The limit that follows from the cooling of SN 1987A is believed to be greater (probably much greater) than 10 keV. This result is significant in light of the recent evidence for a 17 keV mass eigenstate that mixes with the electron neutrino.

  5. The Progenitor of SN 1987A. [IUE

    NASA Technical Reports Server (NTRS)

    Sonneborn, G.

    1988-01-01

    Spatially resolved IUE spectra (1150 to 2000 A) taken at the position of SN 1987A in March 1987 show that the 12th mag B3 I star Sk -69 deg 202 disappeared. Only the fainter companion stars (Star 2 and Star 3) are present near the site of the supernova. It is concluded that Sk -69 deg 202 exploded to produce SN 1987A. The known characteristics of Sk -69 deg 202 are consistent with the interpretation that the progenitor was a relatively compact star, having a high-velocity low-density stellar wind prior to the outburst. Recent IUE spectra of SN 1987A (May 1988) show no evidence that Sk -69 deg 202 still exists inside the expanding ejecta.

  6. SAINTS - The SN 1987A Intensive Study

    NASA Astrophysics Data System (ADS)

    Kirshner, Robert

    2010-09-01

    SAINTS is a program to observe SN 1987A, the brightest supernova since 1604, as it matures into the youngest supernova remnant at age 23. HST is the essential tool for observing SN 1987A's many physical components. A violent encounter is underway between the fastest-moving debris and the circumstellar ring: shocks excite "hotspots." Radio, optical, infrared and X-ray fluxes have been rising rapidly: we have organized VLT, Spitzer, and Chandra observations to understand the several emission mechanisms at work. The inner debris, excited by radioactive isotopes from the explosion, is now resolved and seen to be aspherical, providing direct evidence on the shape of the explosion itself and on dust that formed in the debris. Questions about SN 1987A remain unanswered. For example, whereis the compact object whose formation sent neutrinos our way in February 1987 ? A rich and unbroken data set from SAINTS will help answer these central questions and will build an archive for the future to help answer questions we have not yet thought to ask. For Cycle 18, these data will include novel observations with the IR channel of WFC3 and UV observations with COS.

  7. The Continuing Fall of SN 1987A

    NASA Astrophysics Data System (ADS)

    Dwek, Eli; Arendt, Richard; Bouchet, Patrice; Danziger, John; Frank, Kari; Gehrz, Robert; Park, Sangwook; Woodward, Charles

    2016-08-01

    We propose to use a total of 0.8 hr to obtain 3.6 and 4.5 micron photometry of SNR 1987A at four final epochs between 10900 and 11500 days after the explosion. SN 1987A has been monitored at approximately 6 month intervals throughout the Spitzer mission. The latest IRAC data clearly show that at 3.6 and 4.5 micron, the SN emission has peaked and is now in decline. Continued observation of SN 1987A will allow us to track the decline as the blast wave moves completely past the equatorial ring (ER). The rate at which new dust is swept up should be dropping to zero, and as the presently swept up dust is gradually destroyed (or cools) the emission should continue to fade. The dust traced at these wavelengths is thought to be collisionally-heated by the SN blast wave that also gives rise to the soft X-ray emission from the ER. Early in the mission, the intensity of the mid-IR emission (24 micron) was generally well correlated with that of the X-ray emission. However, the 3.6 and 4.5 micron emission are no longer tracking the brightness of the soft X-ray emission. These differences could stem from a variety of causes, including the sputtering of the dust or changes in the morphology of the ER. Ongoing X-ray observations of the remnant are taking place. Supplementing these with IR observations is essential for determining the spatial distribution, nature, and evolution of this hot dust component. Additionally, the observations may still reveal the appearance of a new emission component from the SN ejecta which is currently interacting with the reverse shock. These observations will complete the record of Spitzer's observations of SN 1987A, spanning more than 15 years from launch to end of mission.

  8. Linear polarimetric study of SN 1987A

    NASA Astrophysics Data System (ADS)

    Clocchiatti, A.; Mendez, M.; Benvenuto, O.; Feinstein, C.; Marraco, H.

    Linear polarization measurements of SN 1987A were made with 0.83-m and a 2.15-m telescopes. It is found that the polarization decreases with time (Benvenuto et al., 1987) Because the polarization produced by the interstellar matter is time independent and the wavelength dependence of the observed polarization is far from the interstellar relation (Serkowski et al., 1975) it is suggested that the time dependent characteristic is due to an intrinsic polarization vector.

  9. The Infrared Evolution of SN1987A

    NASA Astrophysics Data System (ADS)

    Dwek, Eli; Arendt, Richard; Bouchet, Patrice; Burrows, David; Challis, Peter; Danziger, John; De Buizer, James; Gehrz, Robert; Kirshner, Robert; McCray, Richard; Park, Sangwook; Polomski, Elisha; Woodward, Charles

    2006-05-01

    We will use the SPITZER to continue the ongoing monitoring of SN1987A, the youngest supernova remnant that is undergoing noticable evolutionary changes during the lifetime of the Great Observatories. At infrared wavelengths SN1987A provides a unique complimentary view of the interaction of the SN blast wave with the equatorial ring (ER). Dust in theÊ ERÊ is being swept up by the expanding shock and collisionally heated by the X-ray emitting gas observed with CHANDRA, giving rise to IR emission that reveals the composition and amount of dust that formed in the outflow of the presupernova star. The IR observations also provide a unique tool for studying physical processes - the collisional heating and destruction of dust -Ê in dusty X-ray emitting plasmas. Parts of the blast wave has penetrated the denser regions of the ER, creating the "hotspots" observed with HUBBLE. IR line emission from these regions provide important information on the physical conditions and theÊelemental and dust composition in these cooling shocks. Additionally, the ejecta of the SN explosion contains dust that was observed to have formed about 530 days after the explosion. Its imminent interaction with the ring will heat up this dust, which will be observable with SPITZER. In addition to providing useful information on SN1987A and its environment, the proposed observations will address key global issues regarding the origin and evolution of dust in the universe: how much dust is formed in SN ejecta and in quiescent stellar outflows, and how efficiently grains are destroyed by interstellar shock waves.

  10. IUE investigations of SN 1987A

    NASA Technical Reports Server (NTRS)

    Kirshner, Robert P.

    1989-01-01

    IUE observations of the SN 1987A began shortly after the discovery and have been frequent through 1988 and 1989, using the fine error sensor for photometry, low dispersion spectra for the supernova spectrum, and high dispersion observations for the interstellar medium when the supernova was bright and for circumstellar gas surrounding the supernova as the initial event faded. The UV data were very useful in determining which star exploded, assessing the ionizing pulse produced as the shock hit the surface of the star, and in constraining the stellar evolution that preceded the explosion through observations of a circumstellar shell.

  11. Massive Dirac neutrinos and SN 1987A

    NASA Technical Reports Server (NTRS)

    Burrows, Adam; Gandhi, Raj; Turner, Michael S.

    1992-01-01

    The wrong-helicity states of a Dirac neutrino can provide an important cooling mechanism for young neutron stars. Based on numerical models of the early cooling of the neutron star associated with SN 1987A which self-consistently incorporate wrong-helicity neutrino emission, it is argued that a Dirac neutrino of mass greater than 30 keV (25 keV if it is degenerate) leads to shortening of the neutrino burst that is inconsistent with the Irvine-Michigan-Brookhaven and Kamiokande II data. If pions are as abundant as nucleons in the cores of neutron stars, the present limit improves to 15 keV.

  12. Theoretical infrared spectra of SN 1987A

    NASA Technical Reports Server (NTRS)

    Colgan, Sean W. J.; Hollenbach, David J.

    1988-01-01

    A simple model for the ejecta of SN 1987A is used to show that the expected fluxes in infared fine structure lines from nickel, cobalt, iron, argon, sulfur, silicon, and neon are likely to be detectable for several years following the supernova explosion. Energy sources due to radioactive decay and a central pulsar are considered separately. Most of the mass of heavy elements resides in the inner, pure metal shells of the ejecta, so that the infrared lines will probe the temperature, ejecta masses, and dynamics of this region and not the overlying, hydrogen-rich envelope.

  13. Hydrogen Molecules in SN 1987A

    NASA Technical Reports Server (NTRS)

    Culhane, Michael; McCray, Richard

    1995-01-01

    The observations of CO and SiO in the infrared spectrum of SN 1987A clearly indicate that molecules can form in the debris of a supernova explosion. Since H2 is not easily observable we compute its abundance theoretically. For conditions typical of the inner (v less than 2500 km/s) envelope of SN 1987A, the fraction of H that is in molecular form rises to approx. 1% by t approx. 800 days. For t less than 500 days the formation is dominated by the gas-phase reactions H + H(+) yields H2(+) + hv; H2(+) + H yields H2 + H(+). Thereafter, the formation is dominated by the reactions H + e yields H(-) + hv; H(-) + H yields H2 + e. At early times the H(-) may absorb approx. 10%-30% of visible photons, contributing to the apparent paucity of H alpha emission. For t greater than 1000 days the abundance of H2 'freezes out' due to the slowing of all reactions. The opacity of the supernova envelope in the range 912 less than lambda less than or approx. equal to 1400 A (the upper limit depending on temperature) is dominated by resonance scattering in the Lyman and Werner bands of H2. The resulting fluorescence emission bands of H2 in the range 1150 less than lambda less than 1650 A may be observable in the UV spectra of supernovae at late times.

  14. Axions and SN 1987A: Axion trapping

    NASA Technical Reports Server (NTRS)

    Burrows, Adam; Ressell, M. Ted; Turner, Michael S.

    1990-01-01

    If an axion of mass between about 10(exp -3) and 10 eV exists, axion emission would have significantly affected the cooling of the nascent neutron star associated with SN 1987A. For an axion of mass greater than about 10(exp -2) eV axions would, like neutrinos, have a mean-free path that is smaller than the size of a neutron star, and thus would become trapped and radiated from an axion sphere. The trapping regime is treated by using numerical models of the initial cooling of a hot neutron star that incorporate a diffusion approximation for axion-energy transport. The axion opacity due to inverse nucleon-nucleon, axion bremsstrahlung is computed; and then the numerical models are used to calculate the integrated axion luminosity, the temperature of the axion sphere, and the effect of axion emission on the neutrino bursts detected by the Kamiokande II (KII) and Irvine-Michigan-Brookhaven (IMB) water-Cherenkov detectors. The larger the axion mass, the stronger the trapping and the smaller the axion luminosity. The estimate of the axion mass is confirmed above which trapping is so strong that axion emission does not significantly affect the neutrino burst. Based upon the neutrino-burst duration - the most sensitive barometer of axion cooling - it is concluded that for an axion mass greater than about 3 eV axion emission would not have had a significant effect on the neutrino bursts detected by KII and IMB. It is strongly suggested that an axion with mass in the interval 10(exp -3) to 3 eV is excluded by the observation of neutrinos from SN 1987A.

  15. Axions and SN 1987A: Axion trapping

    NASA Technical Reports Server (NTRS)

    Burrows, Adam; Ressell, M. Ted; Turner, Michael S.

    1990-01-01

    If an axion of mass between about 10(exp -3) eV and 1 eV exists, axion emission would have significantly affected the cooling of the nascent neutron star associated with SN 1987A. For an axion of mass less than about 10(exp -2) eV, axions produced deep inside the neutron star simply stream out; in a previous paper this case has been addressed. Remarkably, for an axion of mass greater than about 10(exp -2) eV axions would, like neutrinos, have a mean-free path that is smaller than the size of a neutron star, and thus would become 'trapped' and radiated from an axion sphere. In this paper the trapping regime is treated by using numerical models of the initial cooling of a hot neutron star that incorporate a leakage approximation scheme for axion-energy transport. The axion opacity is computed due to inverse nucleon-nucleon, axion bremsstrahlung, and numerical models are used to calculate the integrated axion luminosity, the temperature of the axion sphere, and the effect of axion emission on the neutrino bursts detected by the Kamiokande 2 (K2) and Irvine-Michigan-Brookhaven (IMB) water-Cherenkov detectors. The larger the axion mass, the stronger the trapping and the smaller the axion luminosity. The earlier estimate is confirmed and refined of the axion mass above which trapping is so strong that axion emission does not significantly affect the neutrino burst. Based upon the neutrino-burst duration--the most sensitive barometer of axion cooling--it is concluded that for an axion mass of greater than about 0.3 eV, axion emission would not have had a significant effect on the neutrino bursts detected by K2 and IMB. The present work, together with the previous work, strongly suggests that an axion with mass in the interval 10(exp -3) eV to 0.3 eV is excluded by SN 1987A.

  16. LSND, SN1987A, and CPT violation

    SciTech Connect

    Murayama, Hitoshi; Yanagida, T.

    2000-10-17

    We point out that neutrino events observed at Kamiokande andIMB from SN1987A disfavor the neutrino oscillation parameters preferredby the LSND experiment. For Delta m2>0 (the light side), theelectron neutrinos from the neutronization burst would be lost, while thefirst event at Kamiokande is quite likely to be due to an electronneutrino. For Delta m2<0 (the dark side), the average energy of thedominantly bar nu e events is already lower than the theoreticalexpectations, which would get aggravated by a complete conversion frombar nu mu to bar nu e. If taken seriously, the LSND data are disfavoredindependent of the existence of a sterile neutrino. A possible remedy isCPT violation, which allows different mass spectra for neutrinos andanti-neutrinos and hence can accommodate atmospheric, solar and LSND datawithout a sterile neutrino. If this is the case, Mini-BooNE must run inbar nu rather than the planned nu mode to test the LSND signal. Wespeculate on a possible origin of CPT violation.

  17. Dust and Other Recent Discoveries in SN 1987A

    NASA Technical Reports Server (NTRS)

    Sonneborn, George

    2011-01-01

    Supernova 1987 A in the Large Magellanic Cloud is one of the most intensively studied objects in the universe and a Rosetta Stone for understanding the explosions of massive stars. Now almost 25 years old, SN 1987 A is a very young supernova remnant, a phase previously unobserved in any other supernova. In this talk I will discuss recent observations from the far ultraviolet to the far-infrared with HST, the VLT, and the Herschel Space Observatory. These data reveal new insights into the composition, geometry, and heating of the explosion debris, the shock interaction with circumstellar material, and dust in the SN 1987 A system.

  18. Simulating the Outer Nebula of SN 1987A

    NASA Astrophysics Data System (ADS)

    Fitzpatrick, Ben; Morris, Thomas; Podsiadlowski, Philipp

    2014-01-01

    As has been shown previously, the triple-ring nebula around SN 1987A can be understood as a direct consequence of the merger of two stars, some 20,000 yr before the explosion. Here we present new SPH simulations that also include the pre-merger mass loss and show that this may be able to explain other structures observed around SN 1987A, such as Napoleon's hat and various light echoes.

  19. Neutrino astrophysics and SN 1987A

    NASA Astrophysics Data System (ADS)

    Aglietta, M.; Badino, G.; Bologna, G.; Castagnoli, C.; Castellina, A.

    1990-04-01

    The Mont Blanc observation of the Large Magellanic Cloud supernova, exploded on February 23, 1987 is summarized. The problem of two bursts, recorded in different underground detectors and separated in time by 4.7 hours, is also discussed. Since the different observations are not contradictory from the experimental point of view, some changes are required in the current predictions of the theoretical models of a gravitational stellar collapse in order to fit all the experimental data. Finally, the combined analysis of the data, recorded in all the neutrino and gravitational wave detectors running at the time of the supernova, clearly indicates a long duration of the phenomenon. Thus, any serious tentative to explain how a star ends its life as a supernova should be based on all the experimental data available, recorded in different, independent experiments running at intercontinental distances at the time of supernova 1987A.

  20. The circumstellar ring of SN 1987A

    NASA Astrophysics Data System (ADS)

    Fransson, Claes; Migotto, Katia; Larsson, Josefin; Pesce, Dominic; Challis, Peter; Chevalier, Roger A.; France, Kevin; Kirshner, Robert P.; Leibundgut, Bruno; Lundqvist, Peter; McCray, Richard; Spyromilio, Jason; Taddia, Francesco; Jerkstrand, Anders; Mattila, Seppo; Smith, Nathan; Sollerman, Jesper; Wheeler, J. Craig; Crotts, Arlin; Garnavich, Peter; Heng, Kevin; Lawrence, Stephen S.; Panagia, Nino; Pun, Chun S. J.; Sonneborn, George; Sugerman, Ben

    2016-06-01

    The circumstellar ring of supernova 1987A first became visible a few months after the explosion due to photoionisation by the supernova flash. From 1995 hotspots appeared in the ring and their brightness increased nearly exponentially as a result of interaction with the supernova blast wave. Imaging and spectroscopic observations with the Hubble Space Telescope and the Very Large Telescope now show that both the shocked and the unshocked emission components from the ring have been decreasing since ~ 2009. In addition, the most recent images reveal the brightening of new spots outside the ring. These observations indicate that the hotspots are being dissolved by the shocks and that the blast wave is now expanding and interacting with dense clumps beyond the ring. Based on the currently observed decay we predict that the ring will be destroyed by ~ 2025, while the blast wave will reveal the distribution of gas as it expands outside the ring, thus tracing the mass-loss history of the supernova progenitor.

  1. What does SN1987A say about extra dimensions?

    NASA Astrophysics Data System (ADS)

    Veerahanumak, Satheeshkumar

    2010-02-01

    There has been a tremendous progress in the last decade in our efforts to confront the String-inspired ideas with experiments or observations. There are two approaches to this problem. One is to use the LHC data and other is to use astronomical data. Among the latter, using SN1987A data for placing the constraints on the models of extra dimensions is very popular. In this poster, we consider all the possible energy loss mechanisms of SN1987A and study the constraints they place on the number and size of extra dimensions and the higher dimensional Planck scale in the ADD scenario. )

  2. SN 1987A: The Supernova of the Century

    NASA Technical Reports Server (NTRS)

    Sonneborne, George

    2012-01-01

    Supernova 1987 A in the Large Magellanic Cloud is one of the most intensively studied objects in the universe and a Rosetta Stone for understanding the explosions of massive stars. Approaching its 25th anniversary, SN 1987 A is a very young supernova remnant, a phase previously unobserved in any other supernova. The supernova of the 20th Century is now the supernova remnant of the 21st Century. In this talk I will discuss recent observations from the far-ultraviolet to the far-infrared with HST, the VLT, Spitzer, and the Herschel Space Observatory. These data reveal new insights into the composition, geometry, and heating of the explosion debris, the shock interaction with circumstellar material, and dust in the SN 1987 A system.

  3. OSSE Observations of 57Co In SN1987A

    DTIC Science & Technology

    1992-01-01

    ray--observations; nucleosynthesis ; X-rays: general 1E.O. Hulburt Center for Space Research, Naval Research Laboratory, Washington DC 20375 2Dept...gamma-ray thickness of the ejecta. Nucleosynthetic models for SN1987A and general nucleosynthesis constraints suggest that the production ratio of 57Ni

  4. Similarity Analysis of Experiments on SN 1987A Hydrodynamics

    NASA Astrophysics Data System (ADS)

    Ryutov, D.; Kane, J.; Remington, B.

    1997-11-01

    Similarity criteria for experimentally studying hydrodynamic aspects of the SN 1987A explosion are considered. Particular emphasis is made on the study of Richtmyer-Meshkov and Rayleigh-Taylor instabilities. At the early stage of the explosion (t ~a few hours), for the power-law adiabat equations and high pressure in the pusher, there exist a universal similarity that allows one to establish direct links between the SN event and laboratory experiments of the type described in [1]. For the late stage (t ~20 yr) the plasma becomes weakly collisional and transparent to radiation. Radiation losses are insignificant at this stage. We predict an important role of the fire-hose instability in the plasma flow past the SN 1987A ring. We discuss experimental setting where these phenomena could be simulated in a correct way. [1] B. Remington et al. "Phys. Plasmas", v. 4, 1994 (1997); J. Kane et al., ApJ. 478, L75 (1997)

  5. Supernova 1987A

    NASA Astrophysics Data System (ADS)

    McCray, R.; Murdin, P.

    2002-10-01

    Supernova 1987A (SN1987A) in the LARGE MAGELLANIC CLOUD (LMC) is the brightest supernova to be observed since SN1604 (Kepler), the first to be observed in every band of the ELECTROMAGNETIC SPECTRUM and the first to be detected through its initial burst of NEUTRINOS. Although the bolometric luminosity of SN1987A today is ≈10-6 of its value at maximum light (Lmax≈2.5×108L⊙), it ...

  6. Light echoes and transient luminescence near SN 1987A

    NASA Technical Reports Server (NTRS)

    Crotts, Arlin P. S.; Kunkel, William E.; Mccarthy, Patrick J.

    1989-01-01

    The discovery of two new light echoes from sheets of material behind supernova 1987A and present images of the progenitor's circumstellar shell are reported, indicating diffuse echoes from the star's red giant wind. The echo sheets' geometry explains well the behavior of SN 1987's 10-micron flux, but the circumstellar shell appears to be 70 percent larger than the prediction from the analysis of narrow UV emission lines. The sheets' recombination time show them relatively thin and dense. The data also constrain the existence of any fourth star in the Sanduleak -69 deg 202 system and show that the feature reported 8 arcsecs from the supernova is probably not an echo from a thin sheet in SN 1987A's foreground.

  7. Possible binary star progenitor for SN1987A

    NASA Astrophysics Data System (ADS)

    White, Graeme L.; Malin, D. F.

    1987-05-01

    Accurate optical astrometry gives a position (B1950.0) for the Large Magellanic Cloud supernova, SN 1987A, relative to the FK 4 system as right ascension, RA = 05h 35min 49.95 s±0.039 s, declination δ = -69°17arcmin57.9arcsec±0.27arcsec. Differential astrometry carried out on prime-focus plates taken with the AAT indicates that the component, star 1, of Sanduleak's star Sk -69202 is within 0.05±0.13 arc s of the supernova. The authors conclude that the progenitor of SN 1987A was star 1 or a fainter binary companion.

  8. Observing SN 1987A with the International Ultraviolet Explorer

    NASA Technical Reports Server (NTRS)

    Kirshner, Robert P.

    1991-01-01

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

  9. First results from the Faint Object Camera - SN 1987A

    NASA Technical Reports Server (NTRS)

    Jakobsen, P.; Albrecht, R.; Barbieri, C.; Blades, J. C.; Boksenberg, A.

    1991-01-01

    The first images of SN 1987A taken on day 1278 after outburst with the Faint Object Camera on board the Hubble Space Telescope are presented. The supernova is well detected and resolved spatially in three broadband ultraviolet exposures spanning the 1500-3800 A range and in a narrow-band image centered on the forbidden O III 5007 line. Simple uniform disk fits to the profiles of SN 1987A yield an average angular diameter of 170 + or - 30 mas, corresponding to an average expansion velocity of 6000 km/s. The derived broadband ultraviolet fluxes, when corrected for interstellar absorption, indicate a blue ultraviolet spectrum corresponding to a color temperature near 13,000 K.

  10. Regularly pulsed neutrinos from supernova SN1987A?

    NASA Technical Reports Server (NTRS)

    Harwit, Martin; Wasserman, Ira M.; Biermann, Peter L.; Meyer, Hinrich

    1987-01-01

    Some consequences of the 8.9 millisecond periodicity observed in neutrino events from SN1987A with the Kamiokonde and IMB experiments are discussed. Interpreting the apparent period as a rotation of a compact object would imply that the neutrino emission is anisotropic and that the neutrino mass, averaged over all observed flavors, is less than 0.2 eV/c-squared. It is also noted that P = 8.9 ms is a reasonable period for very young pulsars.

  11. The Mont Blanc detection of neutrinos from SN 1987A.

    NASA Astrophysics Data System (ADS)

    Aglietta, M.; Badino, G.; Bologna, G.; Castagnoli, C.; Castellina, A.; Dadykin, V. L.; Fulgione, W.; Galeotti, P.; Kalchukov, F. F.; Kortchaguin, V. B.; Kortchaguin, P. V.; Malguin, A. S.; Ryassny, V. G.; Ryazhkaya, O. G.; Saavedra, O.; Talochkin, V. P.; Trinchero, G.; Vernetto, S.; Zatsepin, G. T.; Yakushev, V. F.

    The authors discuss the event detected in the Mont Blanc Underground Neutrino Observatory on February 23, 1987, during the occurrence of supernova SN 1987A. The pulse amplitudes, the background imitation probability, and the energetics connected with the event are reported. It is also shown that some interactions recorded at the same time in other underground experiments, with a lower detection efficiency, are consistent with the Mont Blanc event.

  12. The Origin of the Rings Around SN1987A

    NASA Astrophysics Data System (ADS)

    Martin, Crystal L.; Arnett, David

    1994-12-01

    Hubble Space Telescope (HST) images show three elliptical rings of fluorescing gas around SN1987A. The progenitor's mass loss history is encoded in this circumstellar structure, and the spatial and temporal variations in the winds' velocity, density, and chemical composition can be derived if the formation of the nebula is understood. Hence, SN1987A's nebula provides a unique opportunity to learn how the outer layers of a massive star were changing during the relatively short, late evolutionary stages preceeding core collapse. A successful model may have applications in a much broader context as well, since the morphology of SN1987A's nebula is not unique. The Crab Nebula, Eta Carina, and a class of planetary nebulae share the same basic geometry -- a double-lobed bubble constricted at the waist by higher density gas in a disk or torus. We present a direct comparison of the interacting-winds model for the formation of SN1987A's nebula and HST images. New two-dimensional hydrodynamic calculations of the interaction of the fast wind from the blue supergiant progenitor with a slower wind expelled during an earlier red supergiant phase are used to construct emission-measure images. The similarity of the overall morphology of these images and the HST images suggests the interacting-winds model is the likely solution for the origin of the nebula. We demonstrate the remarkable agreement between the time scales in this model and a series of stellar evolution calculations. Further work with the interacting-winds model is needed to establish the physical processes responsible for the extreme flattening inferred for the red supergiant wind and the subtle differences between the images.

  13. The Continuing Infrared Evolution of SN1987A

    NASA Astrophysics Data System (ADS)

    Dwek, Eli; Arendt, Richard; Bouchet, Patrice; Burrows, David; Challis, Peter; Danziger, John; De Buizer, James; Gehrz, Robert; Kirshner, Robert; McCray, Richard; Park, Sangwook; Polomski, Elisha; Woodward, Charles

    2008-03-01

    We will use the SPITZER to continue the ongoing monitoring of SN1987A, the youngest supernova remnant that is undergoing noticable evolutionary changes during the lifetime of the Great Observatories. At infrared wavelengths SN1987A provides a unique complimentary view of the interaction of the SN blast wave with the equatorial ring (ER). Dust in the ER is being swept up by the expanding shock and collisionally heated by the X-ray emitting gas observed with CHANDRA, giving rise to IR emission that reveals the composition and amount of dust that formed in the outflow of the presupernova star. The IR observations also provide a unique tool for studying physical processes - the collisional heating and destruction of dust - in dusty X-ray emitting plasmas. Parts of the blast wave has penetrated the denser regions of the ER, creating the 'hotspots' observed with HUBBLE. IR line emission from these regions provide important information on the physical conditions and the elemental and dust composition in these cooling shocks. Additionally, the ejecta of the SN explosion contains dust that was observed to have formed about 530 days after the explosion. Its imminent interaction with the ring will heat up this dust, which will be observable with SPITZER. In addition to providing useful information on SN1987A and its environment, the proposed observations will address key global issues regarding the origin and evolution of dust in the universe: how much dust is formed in SN ejecta and in quiescent stellar outflows, and how efficiently grains are destroyed by interstellar shock waves.

  14. The Continuing Infrared Evolution of SN1987A

    NASA Astrophysics Data System (ADS)

    Dwek, Eli; Arendt, Richard; Bouchet, Patrice; Burrows, David; Challis, Peter; Danziger, John; De Buizer, James; Gehrz, Robert; Kirshner, Robert; McCray, Richard; Park, Sangwook; Polomski, Elisha; Woodward, Charles

    2007-05-01

    We will use the SPITZER to continue the ongoing monitoring of SN1987A, the youngest supernova remnant that is undergoing noticable evolutionary changes during the lifetime of the Great Observatories. At infrared wavelengths SN1987A provides a unique complimentary view of the interaction of the SN blast wave with the equatorial ring (ER). Dust in theÊ ERÊ is being swept up by the expanding shock and collisionally heated by the X-ray emitting gas observed with CHANDRA, giving rise to IR emission that reveals the composition and amount of dust that formed in the outflow of the presupernova star. The IR observations also provide a unique tool for studying physical processes - the collisional heating and destruction of dust -Ê in dusty X-ray emitting plasmas. Parts of the blast wave has penetrated the denser regions of the ER, creating the 'hotspots' observed with HUBBLE. IR line emission from these regions provide important information on the physical conditions and theÊelemental and dust composition in these cooling shocks. Additionally, the ejecta of the SN explosion contains dust that was observed to have formed about 530 days after the explosion. Its imminent interaction with the ring will heat up this dust, which will be observable with SPITZER. In addition to providing useful information on SN1987A and its environment, the proposed observations will address key global issues regarding the origin and evolution of dust in the universe: how much dust is formed in SN ejecta and in quiescent stellar outflows, and how efficiently grains are destroyed by interstellar shock waves.

  15. NASA plans for observations of SN1987A

    NASA Technical Reports Server (NTRS)

    Riegler, Guenter R.

    1987-01-01

    The scientific aims and technological implementation of NASA observations of SN 1987A are outlined in a status report. Key questions to be answered involve nucleosynthesis and the light curves of type II SN; the multilayer structure of the progenitor and the SNR; circumstellar gas, shock-wave, and dust formation; and the evolution of the core remnant. Consideration is given to continued SMM, IUE, Voyager UVS, and DSN observations; future space missions such as GRO, AXAF, and Rosat; balloon-borne gamma-ray, rocket-borne X-ray, and airborne IR observations; and the Science Communications Network and Data Archive.

  16. ALMA resolves SN 1987A's dust factory and particle accelerator

    NASA Astrophysics Data System (ADS)

    Indebetouw, Remy; SN1987A ALMA Cycle 0 Team

    2014-01-01

    SN1987A in the Large Magellanic Cloud is the closest supernova to earth to be observed since 1604, making it a unique laboratory to study supernova physics in real time. Among SN87A's remarkable properties are a very large mass of new dust forming in the supernova ejecta. This dust was inferred from Herschel data, but its location not proven since Herschel could not resolve the 1.8" diameter remnant. Another mystery is whether the explosion left behind a neutron star - neither pulsar nor pulsar wind nebula has been detected so far. Excess emission from a PWN should be easiest to detect at millimeter wavelengths, if it can be spatially resolved from the synchrotron-emitting supernova shock. We present the first spatially resolved images of SN1987A at 450um, 870um, and 1.4mm, observed with the Atacama Large Millimeter/Submillimeter Array (ALMA). ALMA resolves emission from the newly formed dust, unambiguously locating it within the ejecta, interior to the reverse shock. The shocked ring is also well-resolved, and separated spatially from the ejecta. The ring shows no spectral break compared to centimeter wavelengths, and no free-free or PWN emission is required to explain the data. We discuss physical properties of the components of the remnant determined from these high resolution ALMA images.

  17. Axions, SN 1987A, and one pion exchange

    NASA Technical Reports Server (NTRS)

    Turner, Michael S.; Kang, Ho-Shik; Steigman, Gary

    1988-01-01

    Nucleon-nucleon, axion bremsstrahlung is the primary mechanism for axion emission from the nascent neutron star associated with SN 1987A, and the rate for this process has been calculated in the one pion exchange approximation (OPE). The axion mass limit which follows from SN 1987A, m sub a less than or approx equal to 10 to the -3 eV, is the most stringent astrophysical bound, and has received much scrutiny. It has been suggested that by using OPE to calculate the cross section for the analog process, pp yields pp + pi sup o, and comparing the result of the experimental data one can test the validity of this approximation, and further, that such a comparison indicates that OPE leads to a value for this cross section which is a factor of 30 to 40 too large. If true, this would suggest that the axion mass limit should be revised upward by a factor of approximately 6. The cross section for pp yields pp + pi sup o using OPE is carefully evaluated, and excellent agreement found (to better than a factor of 2) with the experimental data.

  18. Rapid ionization of the environment of SN 1987A

    NASA Technical Reports Server (NTRS)

    Raga, A. C.

    1987-01-01

    It has been suggested by some authors that IUE observations of the supernova SN 1987A show the presence of a strong component of the interstellar C IV 1550 and Si IV 1393 absorption lines at a velocity that approximately corresponds to the velocity of the LMC. It is possible that this component might come from originally neutral (or at least not very highly ionized) gas which has been photoionized by the initially very strong ionizing radiation field of the supernova. Theoretical considerations of this scenario lead to the study of fast (with velocities of about c) ionization fronts. It is shown that for reasonable model parameters it is possible to obtain considerably large C IV column densities, in agreement with the IUE observations. On the other hand, the models do not so easily predict the large Si IV column densities that are also obtained from the IUE observations. It is found that only models in which the interstellar medium surrounding SN 1987A is initially composed of already ionized hydrogen and helium predict substantial Si IV column densities. This result provides an interesting prediction of the ionization state of the environment of the presupernova star.

  19. SN 1987A: A Unique Laboratory for Shock Physics

    NASA Technical Reports Server (NTRS)

    Sonneborn, George

    2012-01-01

    Supernova 1987 A is the brightest and nearest supernova observed since Kepler's SN1604, and is the only one close enough to resolve and directly observe the temporal growth of the ejecta. Over the past 25 years, intensive observations across the electromagnetic spectrum with observatories on the ground (Australia Telescope Compact Array, Gemini-S, Magellan, VLT) and in space (IUE, KAO, CGRO, Hubble, Chandra, Spitzer, Herschel) have given us an unprecedented view of the evolution of the debris of the supernova and of its shock interaction with circumstellar matter. The outer supernova debris, now expanding with velocities -8000 km/s, encountered the relatively dense circumstellar ring formed by presupernova mass loss starting in 1994. The resulting shock interaction has been manifested by: rapidly brightening UV-optical "hotspots", an expanding X-ray ring. an expanding ring of knotty non-thermal radio emission, and a ring of thermal IR emission from silicate dust. The recent evolution of these emissions reveal new details about the shock interaction, circumstellar material, and the star that exploded. Certain critical problems about SN 1987 A, such as the still undiscovered compact object formed in the explosion and the structure of the central debris, require the capabilities of JWST.

  20. SN 1987A: Chandra Witnesses the End of an Era

    NASA Astrophysics Data System (ADS)

    Frank, Kari A.; Burrows, David N.

    2016-04-01

    Due to its age and close proximity, the remnant of SN 1987A is the only supernova remnant in which we can study the early developmental stages in detail, providing insight into stellar evolution, the mechanisms of the supernova explosion, and the transition from supernova to supernova remnant as the debris begins to interact with the surrounding circumstellar medium (CSM). We present the latest results from 16 years of Chandra ACIS observations of SN 1987A, now covering 4600 - 10500 days after the supernova. At approximately day 7500, the east-west asymmetry of the ring began to reverse, while the spectra and soft X-ray light curve revealed that the increase in soft X-ray emission slowed dramatically. This suggests the average CSM density encountered by the blast wave decreased at this time, likely due to lack of new emission from the densest clumps in the equatorial ring. Since day 9700 the soft X-ray light curve has flattened and remained approximately constant, evidence that the blast wave has now left the dense material of the known equatorial ring and is beginning to probe the unknown territory beyond.

  1. THE DESTRUCTION OF THE CIRCUMSTELLAR RING OF SN 1987A

    SciTech Connect

    Fransson, Claes; Migotto, Katia; Lundqvist, Peter; Taddia, Francesco; Sollerman, Jesper; Larsson, Josefin; Pesce, Dominic; Chevalier, Roger A.; Challis, Peter; Kirshner, Robert P.; France, Kevin; Leibundgut, Bruno; Spyromilio, Jason; McCray, Richard; Jerkstrand, Anders; Mattila, Seppo; Smith, Nathan; Wheeler, J. Craig; Crotts, Arlin; Garnavich, Peter; and others

    2015-06-10

    We present imaging and spectroscopic observations with Hubble Space Telescope and Very Large Telescope of the ring of SN 1987A from 1994 to 2014. After an almost exponential increase of the shocked emission from the hotspots up to day ∼8000 (∼2009), both this and the unshocked emission are now fading. From the radial positions of the hotspots we see an acceleration of these up to 500–1000 km s{sup −1}, consistent with the highest spectroscopic shock velocities from the radiative shocks. In the most recent observations (2013 and 2014), we find several new hotspots outside the inner ring, excited by either X-rays from the shocks or by direct shock interaction. All of these observations indicate that the interaction with the supernova ejecta is now gradually dissolving the hotspots. We predict, based on the observed decay, that the inner ring will be destroyed by ∼2025.

  2. The Emission Line Spectrum of SN 1987A

    NASA Astrophysics Data System (ADS)

    Li, Hongwei

    With Supernova 1987A (SN 1987A) we have an unprecedented view of the optical and infrared spectrum of a supernova. Here, we develop the basic theory to describe the emission line spectrum of a supernova in the nebular phase and we apply this theory to three of the most prominent important emission line systems: the (OI) lambda lambda 6300, 6364 doublet; the (Ca II) lambda lambda 7300 and Ca II lambda lambda 8600 system, and the optical and infrared lines of Fe, Co and Ni. As a first example, we analyze the evolution of the (OI) lambda lambda 6300, 6364 doublet. We find that the ratio of the mass of OI to its filling factor, M_{rm O}/f_{rm O} , must be about 11, so that for a reasonable value of M_{rm O} = 1.3 Modot, f _{rm O} ~ 0.12. Second, we analyze the near-infrared emission lines of Ca II. We find that UV pumping is required for t _sp{~}> 350 days to fit the (Ca II) lambda lambda 7300 and Ca II lambda lambda 8600 lines. Moreover, we find that the Ca II lines came from the primordial gas rather than the freshly nucleosynthesised products. Iron, cobalt and nickel lines are extremely important in understanding the physical processes in the envelope of SN 1987A. Radioactive decays of ^{56 }Co, 57Co, 44Ti and ^ {22}Na are the dominant energy sources of radiation of SN 1987A in the nebular phase. We find that the nickel-cobalt-iron clumps must have expanded by a factor ~30 or more during a few weeks after outburst as a result of heating by 56Ni and ^{56 }Co decay. This expansion leads to a large filling factor of iron clumps, f_{ rm Fe}~ 0.5, and a small filling factor, f_{rm H,He}~ 0.1-0.2, for primordial gas, such as H, He, etc. From the conditions of thermal equilibrium and ionization equilibrium we determine the evolution of temperature and ionization of the iron clumps. We can account for the light curves (for 150 days_sp ~> t_sp ~> 2 yr) of almost all the observed emission lines of Fe I, Fe II, Co I, Co II, Ni I and Ni II within the uncertainties in

  3. Signatures of neutrino cooling in the SN1987A scenario

    NASA Astrophysics Data System (ADS)

    Fraija, N.; Bernal, C. G.; Hidalgo-Gaméz, A. M.

    2014-07-01

    The neutrino signal from SN1987A confirmed the core-collapse scenario and the possible formation of a neutron star. Although this compact object has eluded all observations, theoretical and numerical developments have allowed a glimpse of the fate of it. In particular, a hypercritical accretion model has been proposed to forecast the accretion of ˜0.15 M⊙ in two hours and the subsequent submergence of the magnetic field in the newborn neutron star. In this paper, we revisit Chevalier's model in a numerical framework, focusing on the neutrino cooling effect on the supernova fall-back dynamics. For that, using a customized version of the FLASH code, we carry out numerical simulations of the accretion of matter on to the newborn neutron star in order to estimate the size of the neutrino-sphere, the emissivity and luminosity of neutrinos. As a signature of this phase, we estimate the neutrinos expected on SK neutrino experiment and their flavour ratios. This is academically important because, although currently it was very difficult to detect 1.46 thermal neutrinos and their oscillations, these fingerprints are the only viable and reliable way to confirm the hypercritical phase. Perhaps new techniques for detecting neutrino oscillations will arise in the near future allowing us to confirm our estimates.

  4. Iron, Cobalt, and Nickel in SN 1987A

    NASA Technical Reports Server (NTRS)

    Li, Hongwei; McCray, Richard; Sunyaev, Rashid A.

    1993-01-01

    During the first several weeks after the explosion of SN 1987A, Fe/Co/Ni clumps, containing approx. 1% of the mass of the supernova envelope, absorbed most of the energy release by Ni-56 and Co-56 decay. As a result, the clumps expanded relative to the substrate, forming a 'nickel bubble' of low-density Fe/Co/Ni. Later the clumps captured approx. 10% of the radioactive luminosity of gamma rays and positrons. Assuming that these elements are not mixed microscopically with other elements, we find that the clumps must occupy approx. greater than 30% of the volume of the emitting region (radial velocity approx. less than 2500 km/s). The result indicates that the emission at late times is dominated by an extra source of heating and ionization, most likely photoionization by two-photon continuum from metastable helium in the gas surrounding the clumps. The resulting 'frothy' structure, consisting of bubbles of low-density Fe surrounded by higher-density filaments of H, He, and other elements, will persist and may be seen in the spectra and structure of supernova remnants.

  5. Co-57 and Ti-44 production in SN 1987A

    NASA Technical Reports Server (NTRS)

    Woosley, S. E.; Hoffman, Robert D.

    1991-01-01

    A survey of parameterized explosive silicon burning is carried out in order to limit the range of allowed masses of Co-57 produced by SN 1987A. The most likely value is between 0.5 and 2.5 times that implied by a solar ratio for Fe-57/Fe-56. Values more than four and less than one-third times the solar ratio would pose very severe problems for the theory of stellar nucleosynthesis, implying, for example, that Fe-56 was not the dominant iron group isotope or that no electron capture occurred during oxygen burning. Though dependent somewhat on the neutron excess, the Fe-57 yield is most sensitive to the occurrence of an alpha-rich freeze-out. An accurate measurement of the Fe-57 yield, as reflected observationally by the current abundance of radioactive Co-57, is thus an important constraint upon the supernova explosion mechanism. The abundance of Ti-44, another nucleus produced exclusively in the alpha-rich freeze-out, cannot be much greater than that implied by the solar ratio of Ca-44/Fe-56.

  6. SN 1987A - The evolution from red to blue

    SciTech Connect

    Tuchman, Y.; Wheeler, J.C. )

    1989-11-01

    Envelope models in thermal and dynamic equilibrium are used to explore the nature of the transition of SK -69 deg 202, the progenitor of SN 1987A, from the Hayashi track to its final blue position in the H-R diagram. Loci of possible thermal equilibrium solutions are presented as a function of Teff and M(C/O), the mass of the carbon/oxygen core interior to the helium burning shell. It is found that uniform helium enrichment of the envelope results in red-blue evolution but that the resulting blue solution is much hotter than SK -69 deg 202. Solutions in which the only change is to redistribute the portion of the envelope enriched in helium during main-sequence convective core contraction into a step function with Y of about 0.5 at a mass cut of about 10 solar masses give a natural transition from red to blue and a final value of Teff in agreement with observations. It is argued that SK -69 deg 202 probably fell on a post-Hayashi track sequence at moderate Teff. The possible connection of this sequence to the step distribution in the H-R diagram of the LMC. 19 refs.

  7. The Three-dimensional Circumstellar Environment of SN 1987A

    NASA Astrophysics Data System (ADS)

    Sugerman, Ben E. K.; Crotts, Arlin P. S.; Kunkel, William E.; Heathcote, Stephen R.; Lawrence, Stephen S.

    2005-07-01

    Surrounding SN 1987A is a three-ring nebula attributed to interacting stellar winds, yet no model has successfully reproduced this system. Fortunately, the progenitor's mass-loss history can be reconstructed using light echoes, in which scattered light from the supernova traces the three-dimensional morphology of its circumstellar dust. In this paper, we construct and analyze the most complete map to date of the progenitor's circumstellar environment, using ground- and space-based imaging from the past 16 years. PSF-matched difference-imaging analyses of data from 1988 through 1997 reveal material between 1 and 28 lt-yr from the SN. Previously known structures, such as an inner hourglass, Napoleon's Hat, and a contact discontinuity, are probed in greater spatial detail than before. Previously unknown features are also discovered, such as a southern counterpart to Napoleon's Hat. Careful analyses of these echoes allows the reconstruction of the probable circumstellar environment, revealing a richly structured bipolar nebula. An outer, double-lobed ``Peanut,'' which is believed to be the contact discontinuity between red supergiant and main-sequence winds, is a prolate shell extending 28 lt-yr along the poles and 11 lt-yr near the equator. Napoleon's Hat, previously believed to be an independent structure, is the waist of this Peanut, which is pinched to a radius of 6 lt-yr. Interior to this is a cylindrical hourglass, 1 lt-yr in radius and 4 lt-yr long, which connects to the Peanut by a thick equatorial disk. The nebulae are inclined 41° south and 8° east of the line of sight, slightly elliptical in cross section, and marginally offset west of the SN. From the hourglass to the large, bipolar lobes, echo fluxes suggest that the gas density drops from 1-3 to >~0.03 cm-3, while the maximum dust-grain size increases from ~0.2 to 2 μm, and the silicate:carbonaceous dust ratio decreases. The nebulae have a total mass of ~1.7 Msolar. The geometry of the three rings is

  8. The impact of SN 1987A with its circumstellar ring

    NASA Technical Reports Server (NTRS)

    Luo, Ding; Mccray, Richard; Slavin, Johnathan

    1994-01-01

    The envleope of SN 1987A will strike its circumstellar ring in 12 +/- 3 yr after explosion (A.D. 1999+/-3), the exact time depending weakly on the uncertain density of diffuse gas between the supernova and the ring. The impact will drive a radiative shock into the ring with velocity approximatley 200-400 km s(exp -1). The shocked ring will become a bright optical and ultraviolet emsiison-line source. A bright arc will suddenly appear at the near side of the ring and grow into an entire ring about 11 months later. The luminosities of the brightest lines, H-alpha H-alpha, N v lambda lambda 1238, 1242, and O VI lambda lambda 1032, 1038 will rise rapidly to approxminately 10(exp 36)-10(exp 37) ergs s(exp -1) and remain bright for several years after impact. The emission lines from the shocked ring will have FWHM approximatley 300-600 km s(exp -1) and complex profiles that will depend on position and will be sensitive to the details of the density distribution of gas in the ring. Strong EUV radiation from the shock will photoionize the unshocked ring, causing emission of narrow FWHM equivalent to 15 km s(exp -1) H-alpha, H-beta and (O III) lambda lambda 4959, 5007 lines with luminosities approximatley 10(exp 35) ergs s(exp -1).The EUV radiation will probably cause the nebulosity beyond the ring to become visable again. The EUV radiation may also illuminate the unshocked outer supernova envelope, causing visible emission of broad FWHM equivalent to 10(exp 4) km s(exp -1) H-alpha and H-beta lines.

  9. SN Refsdal: Classification as a Luminous and Blue SN 1987A-like Type II Supernova

    NASA Astrophysics Data System (ADS)

    Kelly, P. L.; Brammer, G.; Selsing, J.; Foley, R. J.; Hjorth, J.; Rodney, S. A.; Christensen, L.; Strolger, L.-G.; Filippenko, A. V.; Treu, T.; Steidel, C. C.; Strom, A.; Riess, A. G.; Zitrin, A.; Schmidt, K. B.; Bradač, M.; Jha, S. W.; Graham, M. L.; McCully, C.; Graur, O.; Weiner, B. J.; Silverman, J. M.; Taddia, F.

    2016-11-01

    We have acquired Hubble Space Telescope (HST) and Very Large Telescope near-infrared spectra and images of supernova (SN) Refsdal after its discovery as an Einstein cross in fall 2014. The HST light curve of SN Refsdal has a shape consistent with the distinctive, slowly rising light curves of SN 1987A-like SNe, and we find strong evidence for a broad Hα P-Cygni profile and Na I D absorption in the HST grism spectrum at the redshift (z = 1.49) of the spiral host galaxy. SNe IIn, largely powered by circumstellar interaction, could provide a good match to the light curve of SN Refsdal, but the spectrum of a SN IIn would not show broad and strong Hα and Na I D absorption. From the grism spectrum, we measure an Hα expansion velocity consistent with those of SN 1987A-like SNe at a similar phase. The luminosity, evolution, and Gaussian profile of the Hα emission of the WFC3 and X-shooter spectra, separated by ˜2.5 months in the rest frame, provide additional evidence that supports the SN 1987A-like classification. In comparison with other examples of SN 1987A-like SNe, photometry of SN Refsdal favors bluer B - V and V - R colors and one of the largest luminosities for the assumed range of potential magnifications. The evolution of the light curve at late times will provide additional evidence about the potential existence of any substantial circumstellar material. Using MOSFIRE and X-shooter spectra, we estimate a subsolar host-galaxy metallicity (8.3 ± 0.1 dex and <8.4 dex, respectively) near the explosion site.

  10. The Type II supernovae 2006V and 2006au: two SN 1987A-like events

    NASA Astrophysics Data System (ADS)

    Taddia, F.; Stritzinger, M. D.; Sollerman, J.; Phillips, M. M.; Anderson, J. P.; Ergon, M.; Folatelli, G.; Fransson, C.; Freedman, W.; Hamuy, M.; Morrell, N.; Pastorello, A.; Persson, S. E.; Gonzalez, S.

    2012-01-01

    Context. Supernova 1987A revealed that a blue supergiant (BSG) star can end its life as a core-collapse supernova (SN). SN 1987A and other similar objects exhibit properties that distinguish them from ordinary Type II Plateau (IIP) SNe, whose progenitors are believed to be red supergiants (RSGs). Similarities among 1987A-like events include a long rise to maximum, early luminosity fainter than that of normal Type IIP SNe, and radioactivity acting as the primary source powering the light curves. Aims: We present and analyze two SNe monitored by the Carnegie Supernova Project that are reminiscent of SN 1987A. Methods: Optical and near-infrared (NIR) light curves, and optical spectroscopy of SNe 2006V and 2006au are presented. These observations are compared to those of SN 1987A, and are used to estimate properties of their progenitors. Results: Both objects exhibit a slow rise to maximum and light curve evolution similar to that of SN 1987A. At the earliest epochs, SN 2006au also displays an initial dip which we interpret as the signature of the adiabatic cooling phase that ensues shock break-out. SNe 2006V and 2006au are both found to be bluer, hotter and brighter than SN 1987A. Spectra of SNe 2006V and 2006au are similar to those of SN 1987A and other normal Type II objects, although both consistently exhibit expansion velocities higher than SN 1987A. Semi-analytic models are fit to the UVOIR light curve of each object from which physical properties of the progenitors are estimated. This yields ejecta mass estimates of Mej ≈ 20 M⊙, explosion energies of E ≈ 2-3 × 1051 erg s-1, and progenitor radii of R ≈ 75-100 R⊙ for both SNe. Conclusions: The progenitors of SNe 2006V and 2006au were most likely BSGs with a larger explosion energy as compared to that of SN 1987A. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (ESO Programme 076.A-0156). This paper includes data gathered with the 6

  11. 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.

  12. SN 1987 A: A Unique Laboratory for Shock Physics

    NASA Technical Reports Server (NTRS)

    Sonneborn, George

    2012-01-01

    Supernova 1987 A has given us an unprecedented view of the evolution of the explosion debris and its interaction with circumstellar matter. The outer supernova debris, now expanding with velocities approx.8000 km/s, encountered the relatively dense circumstellar ring formed by presupernova mass loss in the early 1990s. The shock interaction is manifested by UV-optical "hotspots", an expanding X-ray ring, an expanding ring of knotty non-thermal radio emission, and a ring of thermal IR emission from silicate dust Recent ultraviolet observations of the emissions from the reverse shock and the ring with the HST/COS reveal new details about the shock interaction. Lyman alpha emission from the reverse shock is much stronger than H alpha and they have different emission morphologies, pointing to different emission mechanisms. The reverse shock was detected for the first time in C IV 1550. The N V to C IV brightness ratio indicates the N/C abundance ratio in the expanding debris is about 100X solar, about 3X N/C in the inner ring.

  13. Supernova SN1987A in the Large Magellanic Cloud

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Glittering stars and wisps of gas create a breathtaking backdrop for the self-destruction of a massive star, called supernova 1987A, in the Large Magellanic Cloud, a nearby galaxy. Astronomers in the Southern hemisphere witnessed the brilliant explosion of this star on Feb. 23, 1987. Shown in this NASA Hubble Space Telescope image, the supernova remnant, surrounded by inner and outer rings of material, is set in a forest of ethereal, diffuse clouds of gas. This three-color image is composed of several pictures of the supernova and its neighboring region taken with the Wide Field and Planetary Camera 2 in Sept. 1994, Feb. 1996 and July 1997. The many bright blue stars nearby the supernova are massive stars, each more than six times heftier than our Sun. They are members of the same generation of stars as the star that went supernova about 12 million years ago. The presence of bright gas clouds is another sign of the youth of this region, which still appears to be a fertile breeding ground for new stars. In a few years the supernova's fast moving material will sweep the inner ring with full force, heating and exciting its gas, and will produce a new series of cosmic fireworks that will offer a striking view for more than a decade.

  14. SN1987A IN THE LARGE MAGELLANIC CLOUD

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Glittering stars and wisps of gas create a breathtaking backdrop for the self-destruction of a massive star, called supernova 1987A, in the Large Magellanic Cloud, a nearby galaxy. Astronomers in the Southern hemisphere witnessed the brilliant explosion of this star on Feb. 23, 1987. Shown in this NASA Hubble Space Telescope image, the supernova remnant, surrounded by inner and outer rings of material, is set in a forest of ethereal, diffuse clouds of gas. This three-color image is composed of several pictures of the supernova and its neighboring region taken with the Wide Field and Planetary Camera 2 in Sept. 1994, Feb. 1996 and July 1997. The many bright blue stars nearby the supernova are massive stars, each more than six times heftier than our Sun. With ages of about 12 million years old, they are members of the same generation of stars as the star that went supernova. The presence of bright gas clouds is another sign of the youth of this region, which still appears to be a fertile breeding ground for new stars. In a few years the supernova's fast moving material will sweep the inner ring with full force, heating and exciting its gas, and will produce a new series of cosmic fireworks that will offer a striking view for more than a decade. Credit: Hubble Heritage Team (AURA/STScI/NASA)

  15. Experimental limits on the radiative decay of SN 1987A neutrinos

    NASA Technical Reports Server (NTRS)

    Chupp, Edward L.; Vestrand, W. Thomas; Reppin, Claus

    1989-01-01

    SMM gamma-ray spectrometer data are examined to look for gamma-ray emission coincident with the about-10-s neutrino burst from SN 1987A. The absence of a detectable signal suggests that the energy radiated into MeV gamma rays by neutrino decay (or any other process) is less than 10 to the -10th of that in supernova neutrinos above 9 MeV. The results are used to set a direct limit on the lifetime of any massive neutrino type generated in the core collapse leading to SN 1987A.

  16. Supernova 1987A

    NASA Technical Reports Server (NTRS)

    Mccray, Richard; Li, Hong Wei

    1988-01-01

    Supernova 1987A (February 23, 1987) in the Large Magellanic Cloud is the brightest supernova to be observed since SN 1604 AD (Kepler). Detection of a burst of neutrinos indicates that a neutron star was formed. Radioactive decay of about 0.07 solar mass of Co-56 is responsible for the observed optical light as well as hard X-rays and gamma-ray lines. Ultraviolet, optical, and infrared 'light echoes' and soft X-rays provide information on the distribution of circumstellar matter and the evolution of the progenitor star.

  17. Neutrinos from SN 1987A and cooling of the nascent neutron star

    NASA Technical Reports Server (NTRS)

    Lamb, D. Q.; Loredo, Thomas J.; Melia, Fulvio

    1988-01-01

    The implications of the detection of neutrinos from SN 1987A for the cooling of the nascent neutron star are considered. The nu-bar(e) number N, the apparent temperature, the cooling time scale measured by the Kamioka and IMB detectors, and the inferred neutron star apparent radius and binding energy are all found to provide striking verification of current supernova theory.

  18. Ti-44 Gamma-Ray Emission Lines from SN1987A Reveal an Asymmetric Explosion

    NASA Technical Reports Server (NTRS)

    Boggs, S. E.; Harrison, F. A.; Miyasaka, H.; Grefenstette, B. W.; Zoglauer, A.; Fryer, C. L.; Reynolds, S. P.; Alexander, D. M.; An, H.; Barret, D.; Christensen, F. E.; Craig, W. W.; Forster, K.; Giommi, P.; Hailey, C. J.; Hornstrup, A.; Kitaguchi, T.; Koglin, J. E.; Madsen, K. K.; Zhang, W. W.

    2015-01-01

    In core-collapse supernovae, titanium-44 (Ti-44) is produced in the innermost ejecta, in the layer of material directly on top of the newly formed compact object. As such, it provides a direct probe of the supernova engine. Observations of supernova 1987A (SN1987A) have resolved the 67.87- and 78.32-kilo-electron volt emission lines from decay of Ti-44 produced in the supernova explosion. These lines are narrow and redshifted with a Doppler velocity of 700 kilometers per second, direct evidence of large-scale asymmetry in the explosion.

  19. ASYMMETRY IN THE OUTBURST OF SN 1987A DETECTED USING LIGHT ECHO SPECTROSCOPY

    SciTech Connect

    Sinnott, B.; Welch, D. L.; Sutherland, P. G.; Rest, A.; Bergmann, M.

    2013-04-10

    We report direct evidence for asymmetry in the early phases of SN 1987A via optical spectroscopy of five fields of its light echo system. The light echoes allow the first few hundred days of the explosion to be reobserved, with different position angles providing different viewing angles to the supernova. Light echo spectroscopy therefore allows a direct spectroscopic comparison of light originating from different regions of the photosphere during the early phases of SN 1987A. Gemini multi-object spectroscopy of the light echo fields shows fine structure in the H{alpha} line as a smooth function of position angle on the near-circular light echo rings. H{alpha} profiles originating from the northern hemisphere of SN 1987A show an excess in redshifted emission and a blue knee, while southern hemisphere profiles show an excess of blueshifted H{alpha} emission and a red knee. This fine structure is reminiscent of the 'Bochum event' originally observed for SN 1987A, but in an exaggerated form. Maximum deviation from symmetry in the H{alpha} line is observed at position angles 16 Degree-Sign and 186 Degree-Sign , consistent with the major axis of the expanding elongated ejecta. The asymmetry signature observed in the H{alpha} line smoothly diminishes as a function of viewing angle away from the poles of the elongated ejecta. We propose an asymmetric two-sided distribution of {sup 56}Ni most dominant in the southern far quadrant of SN 1987A as the most probable explanation of the observed light echo spectra. This is evidence that the asymmetry of high-velocity {sup 56}Ni in the first few hundred days after explosion is correlated to the geometry of the ejecta some 25 years later.

  20. Thirteen years of pummeling the circumstellar ring around SN 1987A

    NASA Astrophysics Data System (ADS)

    Dwek, Eli; Arendt, Richard G.; Bouchet, Patrice; Danziger, John

    2016-06-01

    Since 2003, about 6000 days after the explosion, the radiative energy output from SN 1987A has shifted from being dominated by the release of radioactive energy from the ejecta, to the release of mechanical energy caused by the interaction of the SN blast wave with the circumstellar ring. The energy from the interaction is released at X-ray, UV-optical, and infrared (IR) wavelengths. The 5-35 micron IR spectrum from the ring is dominated by the emission from collisionally-heated silicate dust. The circumstellar ring around SN 1987A therefore provides astronomers with a unique laboratory for studying the physical conditions and gas-dust interaction in dusty astrophysical plasmas. In particular, the X-ray and IR observations can be used to determine the erosion efficiency of dust grains in such hostile astrophysical environment. In this talk I will summarize what we have learned from 12 years of Gemini and Spitzer observations of the ring around SN 1987A.

  1. Origin of pulsed emission from the young supernova remnant SN 1987A

    NASA Technical Reports Server (NTRS)

    Ruderman, M.; Kluzniak, W.; Shaham, Jacob

    1989-01-01

    To overcome difficulties in understanding the origin of the submillisecond optical pulses from SN 1987A a model similar to that of Kundt and Krotscheck for pulsed synchrotron emission from the Crab was applied. The interaction of the expected ultrarelativistic e(sup + or -) pulsar wind with the pulsar dipole electromagnetic wave reflected from the walls of a pulsar cavity within the SN 1987A nubula can generate pulsed optical emission with efficiency at most eta(sub max) is approximately equal to 10(exp -3). The maximum luminosity of the source is reproduced and other observational constraints can be satisfied for an average wind energy flow is approximately equal to 10(exp 38) erg/(s steradian) and for electron Lorentz factor gamma is approximately equal to 10(exp 5). This model applied to the Crab yields pulsations of much lower luminosity and frequency.

  2. Origin of the Napoleon's hat nebula around SN1987A and implications for the progenitor

    NASA Astrophysics Data System (ADS)

    Podsiadlowski, Ph.; Fabian, A. C.; Stevens, I. R.

    1991-11-01

    A simple geometrical model for the emission nebula around SN1987A, whose morphology has been likened to Napoleon's hat, is presented. The model consists of a ring and a truncated double cone. When the effects of light travel time are included, the model reproduces the important topological structures of the nebula and makes detailed quantitative predictions for its future appearance. In particular, the hat-shaped northern rim is simply explained as the interaction of the light front with the northern cone. To explain the origin of the double cone, it is argued that the progenitor of SN1987A was in a binary system: its strong wind, colliding with a weaker wind from the companion star, created an asymptotic shock surface that was spread out into the required geometry by the rotation of the binary.

  3. Chandra Observations of SN 1987A: The Soft X-Ray Light Curve Revisited

    NASA Technical Reports Server (NTRS)

    Helder, E. A.; Broos, P. S.; Dewey, D.; Dwek, E.; McCray, R.; Park, S.; Racusin, J. L.; Zhekov, S. A.; Burrows, D. N.

    2013-01-01

    We report on the present stage of SN 1987A as observed by the Chandra X-Ray Observatory. We reanalyze published Chandra observations and add three more epochs of Chandra data to get a consistent picture of the evolution of the X-ray fluxes in several energy bands. We discuss the implications of several calibration issues for Chandra data. Using the most recent Chandra calibration files, we find that the 0.5-2.0 keV band fluxes of SN 1987A have increased by approximately 6 x 10(exp-13) erg s(exp-1)cm(exp-2) per year since 2009. This is in contrast with our previous result that the 0.5-2.0 keV light curve showed a sudden flattening in 2009. Based on our new analysis, we conclude that the forward shock is still in full interaction with the equatorial ring.

  4. The structure of SN 1987A's outer circumstellar envelope as probed by light echoes

    NASA Astrophysics Data System (ADS)

    Crotts, Arlin; Sugerman, Ben; Lawrence, Stephen; Kunkel, William

    2001-05-01

    We present ground-based and HST images processed by image subtraction to highlight transient reflection nebulae or ``light echoes'' of the maximum light pulse of the explosion of SN 1987A from surrounding material. Along with numerous structures already discussed elsewhere, we have found (in multiple epochs of data) a new feature opposite the SN from the mysterious ``Napoleon's Hat'' which indicates a symmetric structure due to shocks internal to the SN's red supergiant wind and probably caused by the pile-up of gas due to differential velocities within the outflow. We also show how echoes betray the ram pressure distribution of the progenitor mass loss flow. .

  5. SN 2009mw: a member of the tiny group of 1987A-like supernovae

    NASA Astrophysics Data System (ADS)

    Takats, Katalin; Pignata, Giuliano

    2015-08-01

    SN 1987A was an event that have had a great role in forming our understanding of supernovae (SNe). It was an unusal object, different from type II-P SNe, with a broad light curve that reached the peak about 3 months after the explosion. Even today, there have been only a handful of similar objects studied.We present an event belonging to this elite group. SN 2009mw was discovered by the Chilean Supernova Search project soon after its explosion. We present our observational data of the SN, analyse its nature and compare it to the other similar objects.

  6. The neutrino burst from SN 1987A detected in the Mont Blanc LSD experiment.

    NASA Astrophysics Data System (ADS)

    Aglietta, M.; Badino, G.; Bologna, G.; Castagnoli, C.; Castellina, A.; Dadykin, V. L.; Fulgione, W.; Galeotti, P.; Kalchukov, F. F.; Khalchukov, F. F.; Kortchaguin, V. B.; Korchagin, V. B.; Kortchaguin, P. V.; Korchagin, P. V.; Malguin, A. S.; Mal'Gin, A. S.; Ryassny, V. G.; Ryasnyj, V. G.; Ryazhkaya, O. G.; Saavedra, O.; Talochkin, V. P.; Trinchero, G.; Vernetto, S.; Zatsepin, G. T.; Yakushev, V. F.

    The authors discuss the event, (5 interactions recorded during 7 seconds) detected in the Mont Blanc Underground Neutrino Observatory on February 23, 1987, during the occurrence of supernova SN 1987A. The pulse amplitudes, the background imitation probability, and the energetics connected with the event are reported. It is also shown that some interactions recorded at the same time in other underground experiments, with a lower detection efficiency, are consistent with the Mont Blanc event.

  7. Oriented Scintillation Spectrometer Experiment observations of Co-57 in SN 1987A

    NASA Technical Reports Server (NTRS)

    Kurfess, J. D.; Johnson, W. N.; Kinzer, R. L.; Kroeger, R. A.; Strickman, M. S.; Grove, J. E.; Leising, M. D.; Clayton, D. D.; Grabelsky, D. A.; Purcell, W. R.

    1992-01-01

    The Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma Ray Observatory has observed SN 1987A for two 2 week periods during the first 9 months of the mission. Evidence for gamma-ray line and continuum emission from Co-57 is observed with an intensity of about 10 exp -4 gamma/sq cm/s. This photon flux between 50 and 136 keV is demonstrated by Monte Carlo calculations to be independent of the radial distribution of Co-57 for models of low optical depth, viz., models having photoelectric absorption losses of 122 keV photons no greater than several percent. For such models the observed Co-57 flux indicates that the ratio Ni-57/Ni-56 produced in the explosion was about 1.5 times the solar system ratio of Fe-57/Fe-56. When compared with nearly contemporaneous bolometric estimates of the luminosity for SN 1987A, our observations imply that Co-57 radioactivity does not account for most of the current luminosity of the supernova remnant in low optical depth models. We suggest alternatives, including a large optical depth model that is able to provide the SN 1987A luminosity and is consistent with the OSSE flux. It requires a 57/56 production ratio about twice solar.

  8. Core collapse supernovae from blue supergiant progenitors : The evolutionary history of SN 1987A

    NASA Astrophysics Data System (ADS)

    Menon, Athira

    2015-08-01

    SN 1987A is historically one of the most remarkable supernova explosions to be seen from Earth. Due to the proximity of its location in the LMC, it remains the most well-studied object outside the solar system. It was also the only supernova whose progenitor was observed prior to its explosion.SN 1987A however, was a unique and enigmatic core collapse supernova. It was the first Type II supernova to have been observed to have exploded while its progenitor was a blue supergiant (BSG). Until then Type II supernovae were expected to originate from explosions of red supergiants (RSGs). A spectacular triple-ring nebula structure, rich in helium and nitrogen, was observed around the remnant, indicating a recent RSG phase before becoming a BSG. Even today it is not entirely understood what the evolutionary history may have been to cause a BSG to explode. The most commonly accepted hypothesis for its origin is the merger of a massive binary star system.An evolutionary scenario for such a binary system, was proposed by Podsiadlowski (1992) (P92). Through SPH simulations of the merger and the stellar evolution of the post-merger remnant, Ivanova & Podsiadlowski (2002) and (2003) (I&M) could successfully obtain the RSG to BSG transition of the progenitor.The aim of the present work is to produce the evolutionary history of the progenitor of SN 1987A and its explosion. We construct our models based on the results of P92 and I&M. Here, the secondary (less massive) star is accreted on the primary, while being simultaneously mixed in its envelope over a period of 100 years. The merged star is evolved until the onset of core collapse. For this work we use the 1-dimensional, implicit, hydrodynamical stellar evolution code, KEPLER. A large parameter space is explored, consisting of primary (16-20 Ms) and secondary masses (5-8 Ms), mixing boundaries, and accreting timescales. Those models whose end states match the observed properties of the progenitor of SN 1987A are exploded. The

  9. The quest for blue supergiants : The evolution of the progenitor of SN 1987A

    NASA Astrophysics Data System (ADS)

    Menon, Athira; Heger, Alexander

    2015-08-01

    SN 1987A is historically one of the most remarkable supernova explosions to be seen from Earth. Due to the proximity of its location in the LMC, it remains the most well-studied object outside the solar system. It was also the only supernova whose progenitor was observed prior to its explosion.SN 1987A however, was a unique and enigmatic core collapse supernova. It was the first Type II supernova to have been observed to have exploded while its progenitor was a blue supergiant (BSG). Until then Type II supernovae were expected to originate from explosions of red supergiants (RSGs). A spectacular triple-ring nebula structure, rich in helium and nitrogen, was observed around the remnant, indicating a recent RSG phase before becoming a BSG. Even today it is not entirely understood what the evolutionary history may have been to cause a BSG to explode. The most commonly accepted hypothesis for its origin is the merger of a massive binary star system.An evolutionary scenario for such a binary system, was proposed by Podsiadlowski (1992) (P92). Through SPH simulations of the merger and the stellar evolution of the post-merger remnant, Ivanova & Podsiadlowski (2002) and (2003) (I&M) could successfully obtain the RSG to BSG transition of the progenitor.The aim of the present work is to produce the evolutionary history of the progenitor of SN 1987A and its explosion. We construct our models based on the results of P92 and I&M. Here, the secondary (less massive) star is accreted on the primary, while being simultaneously mixed in its envelope over a period of 100 years. The merged star is evolved until the onset of core collapse. For this work we use the 1-dimensional, implicit, hydrodynamical stellar evolution code, KEPLER. A large parameter space is explored, consisting of primary (16-20 Ms) and secondary masses (5-8 Ms), mixing boundaries, and accreting timescales. Those models whose end states match the observed properties of the progenitor of SN 1987A are exploded. The

  10. Search for O VI Emission from the Shocked Circurmstellar Gas of SN 1987A

    NASA Technical Reports Server (NTRS)

    Sonneborn, G.; Iping, R. C.; Lundqvist, P.; Fransson, C.

    2008-01-01

    The Far Ultraviolet Spectroscopic Explorer (FUSE) was used to search for broad O VI emission from the shock interaction zones produced by the collision of high-velocity supernova ejecta with the dense inner circumstellar ring of SN 1987A. Since the shock interaction with the inner ring began in 1997, broad (FWHM = 300 km/sec) emission from optical coronal lines (e.g. [Fe X], [Fe XI], and [Fe XIV]) has emerged and increased exponentially in strength. O VI 1032-1038 Angstrom emission is expected to track the coronal lines. O VI is also expected to be the primary cooling transition for the million-degree shocked gas. An accurate measurement of the O VI line strength would significantly improve current models of the shock interaction. FUSE observations of SN 1987A in 2000 and 2001 did not detect broad O VI due to spectral contamination fiom two earlytype stars within a few arc seconds of the SN. However, O VI emission was detected with narrow line widths (FWHM less than 35 km/sec) and a heliocentric radial velocity of +280 km/sec. This places the emitting gas at rest relative to the supernova and is interpreted as emission from unshocked circumstellar gas. A new FUSE observation of SN 1987A obtained in May 2007 used a narrow slit (1.25 x 20 arcsec) to significantly reduce the spectral contamination from the two early-type stars. Yet the 2007 spectrum does not reveal any significant O VI emission. The implications of these results are discussed.

  11. The nature of the Napoleon's Hat nebula of SN 1987A

    NASA Astrophysics Data System (ADS)

    Wang, L.; Dyson, J. E.; Kahn, F. D.

    1993-03-01

    The interstellar and circumstellar environment of SN 1987A is modeled. The geometries of Napoleon's Hat nebula and the dark bay suggest that there is relative motion between the SN progenitor and the surrounding ISM. Most of the dark bay can be identified with the bubble produced by the fast blue supergiant (BSG) wind before the red supergiant (RSG) stage. The relative motion between the star and the ISM is the primary reason for the star being at the edge of this bubble. After the first BSG stage, the star evolves to the RSG stage; the wind velocity is now typically 10 km/s and the mass loss rate is around 10 exp -5 solar mass/yr. The star eventually breaks through the bubble produced in the early BSG stage and starts to interact directly with the ISM outside, thus producing Napoleon's Hat. The success of this model is convincing proof of the BSG-RSG-BSG evolutionary model for the SN 1987A progenitors, and shows that is has moved from the site where it was formed.

  12. 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.

  13. 9500 Nights of Mid-Infrared Observations of SN 1987A: the birth of the remnant

    NASA Astrophysics Data System (ADS)

    Bouchet, Patrice; Danziger, John

    2014-01-01

    The one-in-a-life-time event Supernova SN 1987A, the brightest supernova seen since Kepler's in 1604, has given us a unique opportunity to study the mechanics of a supernova explosion and now to witness the birth of a supernova remnant. A violent encounter is underway between the fastest-moving debris and the circumstellar ring: shocks excite ``hotspots''. ATCA/ANTF, Gemini, VLT, HST, Spitzer, Chandra, and recently ALMA observations have been so far organized to help understanding the several emission mechanisms at work. In the mid-infrared SN 1987A has transformed from a SN with the bulk of its radiation from the ejecta to a SNR whose emission is dominated by the interaction of the blast wave with the surrounding interstellar medium, a process in which kinetic energy is converted into radiative energy. Currently this remnant emission is dominated by material in or near the inner equatorial ring (ER). We give here a brief history of our mid-infrared observations, and present our last data obtained with the SPITZER infrared satellite and the ESO VLT and Gemini telescopes: we show how together with Chandra observations, they contribute to the understanding of this fascinating object. We argue also that our imaging observations suggest that warm dust is still present in the ejecta, and we dispute the presence of huge amount of very cold dust in it, as it has been claimed on the basis of data obtained with the HERSCHELl satellite.

  14. New analysis for the correlation between gravitational wave and neutrino detectors during SN1987A

    NASA Astrophysics Data System (ADS)

    Galeotti, P.; Pizzella, G.

    2016-08-01

    Two major problems, still associated with the SN1987A, are: (a) the signals observed with the gravitational waves detectors, (b) the duration of the collapse. Indeed, (a) the sensitivity of the gravitational wave detectors seems to be small for detecting gravitational waves and, (b) while some experimental data indicate a duration of order of hours, most theories assume that the collapse develops in a few seconds. Since recent data of the X-ray NuSTAR satellite show a clear evidence of an asymmetric collapse, we have revisited the experimental data recorded by the underground and gravitational wave detectors running during the SN1987A. New evidence is shown that confirms previous results, namely that the data recorded by the gravitational wave detectors running in Rome and in Maryland are strongly correlated with the data of both the Mont Blanc and the Kamiokande detectors, and that the correlation extends over a long period of time (1 or 2 h) centered at the Mont Blanc time. This result indicates that also Kamiokande detected neutrinos at the Mont Blanc time, and these interactions were not identified because not grouped in a burst.

  15. Revisiting the SN1987A gamma-ray limit on ultralight axion-like particles

    SciTech Connect

    Payez, Alexandre; Ringwald, Andreas; Evoli, Carmelo; Mirizzi, Alessandro; Fischer, Tobias; Giannotti, Maurizio E-mail: carmelo.evoli@desy.de E-mail: mgiannotti@barry.edu E-mail: andreas.ringwald@desy.de

    2015-02-01

    We revise the bound from the supernova SN1987A on the coupling of ultralight axion-like particles (ALPs) to photons. In a core-collapse supernova, ALPs would be emitted via the Primakoff process, and eventually convert into gamma rays in the magnetic field of the Milky Way. The lack of a gamma-ray signal in the GRS instrument of the SMM satellite in coincidence with the observation of the neutrinos emitted from SN1987A therefore provides a strong bound on their coupling to photons. Due to the large uncertainty associated with the current bound, we revise this argument, based on state-of-the-art physical inputs both for the supernova models and for the Milky-Way magnetic field. Furthermore, we provide major amendments, such as the consistent treatment of nucleon-degeneracy effects and of the reduction of the nuclear masses in the hot and dense nuclear medium of the supernova. With these improvements, we obtain a new upper limit on the photon-ALP coupling: g{sub aγ} ∼< 5.3 × 10{sup -12} GeV{sup -1}, for m{sub a} ∼< 4.4 × 10{sup -10} eV, and we also give its dependence at larger ALP masses m{sub a}. Moreover, we discuss how much the Fermi-LAT satellite experiment could improve this bound, should a close-enough supernova explode in the near future.

  16. EXITE/IPC observations of SN1987A and southern targets

    NASA Technical Reports Server (NTRS)

    Grindlay, Jonathan E.

    1991-01-01

    The Energetic X-ray Imaging Telescope Experiment (EXITE) was developed to a flight-ready status and conducted two flights (May 18, 1988, and May 8-10, 1989) from Alice Springs, Australia, as part of the campaigns to observe the supernova SN1987A. The basic operation of the detector and gondola systems in the laboratory was tested on the first flight and found to meet expected performance values. A bizarre 'balloon tape' insulation problem, however, prevented normal telescope pointing on the first flight so no data on SN1987A or other targets were obtained. Following a successful second EXITE flight from Ft. Sumner, NM, in October 1988, the experiment was flown again on a successful 30 hour flight as part of the final 1989 supernova campaign. A second x-ray imaging experiment from MSFC was also flown (piggy-back) for this third flight. Good data were obtained on the supernova and a variety of high priority galactic targets, and final analysis is still in progress. Preliminary results from this flight are presented.

  17. Extra dimensions, SN1987a, and nucleon-nucleon scattering data

    SciTech Connect

    Christoph Hanhart; Daniel R. Phillips; Sanjay Reddy; Martin J. Savage

    2001-02-01

    One of the strongest constraints on the existence of large, compact, ''gravity-only'' dimensions comes from SN1987a. If the rate of energy loss into these putative extra dimensions is too high, then the neutrino pulse from the supernova will differ from that actually seen. The dominant mechanism for the production of Kaluza-Klein gravitons and dilatons in the supernova is via gravistrahlung and dilastrahlung from the nucleon-nucleon system. In this paper we compute the rates for these processes in a model-independent way using low-energy theorems which relate the emissivities to the measured nucleon-nucleon cross section. This is possible because for soft gravitons and dilatons the leading contribution to the energy-loss rate is from graphs in which the gravitational radiation is produced from external nucleon legs. Previous calculations neglected these mechanisms. We re-evaluate the bounds on toroidally-compactified ''gravity-only'' dimensions (GODs), and find that consistency with the observed SN1987a neutrino signal requires that if there are two such dimensions then their radius must be less than 1 micron.

  18. Non-LTE model calculations for SN 1987A and the extragalactic distance scale

    NASA Technical Reports Server (NTRS)

    Schmutz, W.; Abbott, D. C.; Russell, R. S.; Hamann, W.-R.; Wessolowski, U.

    1990-01-01

    This paper presents model atmospheres for the first week of SN 1987A, based on the luminosity and density/velocity structure from hydrodynamic models of Woosley (1988). The models account for line blanketing, expansion, sphericity, and departures from LTE in hydrogen and helium and differ from previously published efforts because they represent ab initio calculations, i.e., they contain essentially no free parameters. The formation of the UV spectrum is dominated by the effects of line blanketing. In the absorption troughs, the Balmer line profiles were fit well by these models, but the observed emissions are significantly stronger than predicted, perhaps due to clumping. The generally good agreement between the present synthetic spectra and observations provides independent support for the overall accuracy of the hydrodynamic models of Woosley. The question of the accuracy of the Baade-Wesselink method is addressed in a detailed discussion of its approximations. While the application of the standard method produces a distance within an uncertainty of 20 percent in the case of SN 1987A, systematic errors up to a factor of 2 are possible, particularly if the precursor was a red supergiant.

  19. Revisiting the SN1987A gamma-ray limit on ultralight axion-like particles

    NASA Astrophysics Data System (ADS)

    Payez, Alexandre; Evoli, Carmelo; Fischer, Tobias; Giannotti, Maurizio; Mirizzi, Alessandro; Ringwald, Andreas

    2015-02-01

    We revise the bound from the supernova SN1987A on the coupling of ultralight axion-like particles (ALPs) to photons. In a core-collapse supernova, ALPs would be emitted via the Primakoff process, and eventually convert into gamma rays in the magnetic field of the Milky Way. The lack of a gamma-ray signal in the GRS instrument of the SMM satellite in coincidence with the observation of the neutrinos emitted from SN1987A therefore provides a strong bound on their coupling to photons. Due to the large uncertainty associated with the current bound, we revise this argument, based on state-of-the-art physical inputs both for the supernova models and for the Milky-Way magnetic field. Furthermore, we provide major amendments, such as the consistent treatment of nucleon-degeneracy effects and of the reduction of the nuclear masses in the hot and dense nuclear medium of the supernova. With these improvements, we obtain a new upper limit on the photon-ALP coupling: gaγ lesssim 5.3 × 10-12 GeV-1, for ma lesssim 4.4 × 10-10 eV, and we also give its dependence at larger ALP masses ma. Moreover, we discuss how much the Fermi-LAT satellite experiment could improve this bound, should a close-enough supernova explode in the near future.

  20. Balloon-borne measurements of the SN1987A hard x ray continuum

    NASA Technical Reports Server (NTRS)

    Pendleton, Geoffrey N.; Paciesas, William S.; Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.

    1994-01-01

    SN1987A hard x ray continuum spectra obtained on 29 Oct. 1987, 9-10 Apr. 1988, and 11 Nov. 1988, from balloon flight measurements are presented. The spectra, spanning the energy range from 25 keV to 300 keV, were analyzed using a detector response matrix inversion technique that converts the spectra from counts/sec-sq cm-kev to photons/sec-sq cm-kev allowing direct comparison with theoretical models. The results indicate that the bulk of the Co-56 is mixed moderately through the inner regions of the SN envelope but they do not preclude the mixing of a small amount of the Co-56 further out into the envelope necessary to account for the observed Co-56 line fluxes. The effect of the ratio of Co-57 to Co-56 on the 11 Nov. 1988, continuum spectrum is discussed.

  1. The Shape of SN 1987A's Circumstellar Nebula (and The Distance to the LMC)

    NASA Astrophysics Data System (ADS)

    Crotts, A. P. S.; Kunkel, W. E.; Heathcote, S. R.; Blanton, E. L.

    1993-12-01

    The circumstellar continuum nebula around SN 1987A, discovered in 1989, disappeared in early 1992 after evolving during the intervening period. We interpret this continuum nebulosity as the light echo from the SN maximum light pulse propagating through reflecting material. In this case the nebula appears consistent with a squat, double-lobed structure with a rotational axis inclined about 45(deg) to the line of sight (and oriented nearly north-south). A least-squares fit, in spherical coordinates, yields R(phi ) = [1 - 0.29phi (2) ](2.47 ly), for -0.45pi < phi < 0.45pi , where phi = 0 along the rotational axis. The equatorial pinch corresponds closely to the position inferred for the small elliptical ring centered on SN 1987A, assuming that it is expanding, and assuming that it is roughly circular. We investigate, by examining the morphology of the diffuse wind beyond this double-lobed nebula, how this non-spherical geometry was created. Presumably this nebula is created at the interface of the inner, blue-supergiant (BSG) wind, and the earlier, denser and slower red-giant (RG) wind. The distribution of this RG wind suggests that the anisotropy of this interface is due both to anisotropic RG wind density and velocity fields. Panagia et al. 1991 suggested that the angular diameter of the inner ring compared to the light-propagation time from its front to back can be used to establish the distance to the SN, therefore the Large Magellanic Cloud (LMC). This idea was further refined by Dwek & Felten 1992 and Gould 1993. A major uncertainty in this determination is the ring's angle of inclination. The double-lobed nebula we have mapped suggests this is close to 45(deg) , indicating a distance to the LMC of about 52 kpc. (We will give a more detailed determination of D_{LMC} in our poster!)

  2. Hydrogen recombination at high optical depth and the spectrum of SN 1987A

    NASA Technical Reports Server (NTRS)

    Xu, Yueming; Mccray, Richard; Oliva, Ernesto; Randich, Sofia

    1992-01-01

    A general theory is presented for hydrogen recombination line formation in an expanding medium in which some of the lines are optically thick. This theory is used to calculate the time evolution of the hydrogen lines of SN 1987A at t equal to or greater than 150 days, assuming that the supernova envelope is a homologously expanding uniform sphere. The theoretical luminosities and ratios of the recombination lines agree remarkably well with the observations. For the first 2 yr, the supernova envelope is optically thick to Balmer continuum. For t equal to or less than 400 days, hydrogen is ionized primarily from the n = 2 level by Balmer continuum photons, which are provided partly by the two-photon decay of the 2s state and partly by emission lines of heavy elements.

  3. Constraints to the decays of Dirac neutrinos from SN 1987A

    NASA Technical Reports Server (NTRS)

    Dodelson, Scott; Frieman, Joshua A.; Turner, Michael S.

    1992-01-01

    The decay mode of a keV-mass Dirac neutrino is addressed with reference to the nineteen neutrino events associated with SN 1987A that were detected by the Kamiokande II and Irvine-Brookhaven-Michigan detectors. A complementary constraint is presented which is based upon a distinctive signal associated with the decay of wrong-helicity neutrinos that was not seen: high-energy (50 MeV and higher) neutrino events. The absence of such events excludes the decay of wrong-helicity neutrinos into proper-helicity neutrinos for a Dirac neutrino of mass between 1 and 300 keV. The constraint also rules out models of the 17-keV neutrino.

  4. Balloon-borne measurements of the SN 1987A hard X-ray continuum

    NASA Technical Reports Server (NTRS)

    Pendleton, Geoffrey N.; Paciesas, William S.; Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.

    1995-01-01

    SN 1987A hard X-ray continuum spectra obtained on 1987 October 29, 1988 April 9-10, and 1988 November 11 from balloon-flight measurments are presented. The spectra, spanning the energy range from 25 keV to 300 keV, have been analyzed using a detector response matrix inversion technique that converts the spectra form counts/s/sq cm keV to photons/s/sq cm keV allowing direct comparison with theoretical models. The results indicate that the bulk of the (56)Co is mixed moderately through the inner regions of the supernova envelope but they do not preclude the mixing of a small amount of the (56)Co farther out into the envelope necessary to account for the observed (56)Co line fluxes. The effect of the ratio (57)Co to (56)Co on the 1988 November 11 continuum spectrum is discussed.

  5. SN1987A-Neutrino emission from Supernova': in Dynamic universe model of cosmology

    NASA Astrophysics Data System (ADS)

    Naga Parameswara Gupta, Satyavarapu

    SN1987A-Neutrino emission from supernova before the star bursts' is an important discovery, when viewed from `Dynamic universe model of cosmology' point of view. In OMEG05, we have successfully presented the reasons for calculation error called `missing mass' in an inhomoge-neous, anisotropic and multi-body Dynamic universe Model, where this error is not occurring. But there are some new voices that say about generation of some flavors of neutrinos during Bigbang. We find from SN1987A Neutrino generation covers all flavors. Remaining flavors of Neutrinos are generated from sun and stars. This covers the whole spectrum. This paper covers all these aspects. And other earlier results by Dynamic Universe Model 1. Offers Singularity free solutions 2. Non-collapsing Galaxy structures 3. Solving Missing mass in Galaxies, and it finds reason for Galaxy circular velocity curves. . . . 4. Blue shifted and red shifted Galaxies co-existence. . . 5. Explains the force behind expansion of universe. 6. Explains the large voids and non-uniform matter densities. 7. Explains the Pioneer anomaly 8. Predicts the trajectory of New Horizons satellite. 9 Jeans swindle test 10. Existence of large number of blue shifted Galaxies `SITA Simulations' software was developed about 18 years back for Dynamic Universe Model of Cosmology. It is based on Newtonian physics. It is Classical singularity free N-body tensor solution to the old problem announced by King Oscar II and tried by Poincare in year AD1888 for 133 masses, tested extensively for so many years. This was developed on 486 based PC of those days; the same software was used repeatedly for so many years for solving different Physical problems on Different PCs and Laptops. It is based on Dynamic Universe Model's mathematical back ground.

  6. Three-dimensional hydrodynamic modeling of SN 1987A from the supernova explosion till the Athena era

    NASA Astrophysics Data System (ADS)

    Orlando, Salvatore

    2016-06-01

    The proximity of SN 1987A and the wealth of observations collected at all wavelenght bands since its outburst allow us to study in details the evolution of a supernova remnant (SNR) from the immediate aftermath of the SN explosion till its expansion through the highly inhomogeneous circumstellar medium (CSM). We investigate the interaction between SN 1987A and the surrounding CSM through three-dimensional hydrodynamic modeling. The aim is to determine the contribution of shocked ejecta and shocked CSM to the detected X-ray flux and to derive the density structure of the inhomogeneous CSM and clues on the early structure of ejecta. We show that the physical model reproducing the main observables of SN 1987A reproduces also the X-ray emission of the subsequent expanding remnant, thus bridging the gap between supernovae and supernova remnants. By comparing model results with observations, we constrain the explosion energy in the range 1.2 - 1.4 × 10^(51) erg and the envelope mass in the range 15 - 17 M_{⊙}) . We find that the shape of X-ray lightcurves and spectra at early epochs (< 15 years) reflect the structure of outer ejecta. At later epochs, the shape of X-ray lightcurves and spectra reflect the density structure of the nebula around SN 1987A. This enabled us to ascertain the origin of the multi-thermal X-ray emission, to disentangle the imprint of the supernova on the remnant emission from the effects of the remnant interaction with the environment, and to constrain the pre-supernova structure of the nebula. Finally the remnant evolution is followed for 40 years, providing predictions on the future of SN 1987A until the adventof Athena.

  7. Supernovae. ⁴⁴Ti gamma-ray emission lines from SN1987A reveal an asymmetric explosion.

    PubMed

    Boggs, S E; Harrison, F A; Miyasaka, H; Grefenstette, B W; Zoglauer, A; Fryer, C L; Reynolds, S P; Alexander, D M; An, H; Barret, D; Christensen, F E; Craig, W W; Forster, K; Giommi, P; Hailey, C J; Hornstrup, A; Kitaguchi, T; Koglin, J E; Madsen, K K; Mao, P H; Mori, K; Perri, M; Pivovaroff, M J; Puccetti, S; Rana, V; Stern, D; Westergaard, N J; Zhang, W W

    2015-05-08

    In core-collapse supernovae, titanium-44 ((44)Ti) is produced in the innermost ejecta, in the layer of material directly on top of the newly formed compact object. As such, it provides a direct probe of the supernova engine. Observations of supernova 1987A (SN1987A) have resolved the 67.87- and 78.32-kilo-electron volt emission lines from decay of (44)Ti produced in the supernova explosion. These lines are narrow and redshifted with a Doppler velocity of ~700 kilometers per second, direct evidence of large-scale asymmetry in the explosion.

  8. The Evolution of Dust Mass in the Ejecta of SN1987A

    NASA Astrophysics Data System (ADS)

    Dwek, Eli; Arendt, Richard G.

    2015-09-01

    We present a new analysis of the infrared (IR) emission from the ejecta of SN 1987A covering days 615, 775, 1144, 8515, and 9090 after the explosion. We show that the observations are consistent with the rapid formation of about 0.4 {M}⊙ of dust, consisting of mostly silicates (MgSiO3), near day 615, and evolving to about 0.45 {M}⊙ of composite dust grains consisting of ˜0.4 {M}⊙ of silicates and ˜0.05 {M}⊙ of amorphous carbon after day ˜8500. The proposed scenario challenges previous claims that dust in supernova (SN) ejecta is predominantly carbon, and that it grew from an initial mass of ˜10-3 {M}⊙ , to over 0.5 {M}⊙ by cold accretion. It alleviates several problems with previous interpretations of the data: (1) it reconciles the abundances of silicon, magnesium, and carbon with the upper limits imposed by nucleosynthesis calculations, (2) it eliminates the requirement that most of the dust observed around day 9000 grew by cold accretion onto the ˜10-3 {M}⊙ of dust previously inferred for days 615 and 775 after the explosion, and (3) establishes the dominance of silicate over carbon dust in the SN ejecta. At early epochs, the IR luminosity of the dust is powered by the radioactive decay of 56Co, and at late times by at least (1.3-1.6) × 10-4 {M}⊙ of 44Ti.

  9. Production and Collimation of Astrophysical Jets or Accretion: M87 and SN 1987A Scenarios

    NASA Astrophysics Data System (ADS)

    Bernal, C. G.; Page, D.

    2006-06-01

    Jets and outflows of various degrees of collimation and energetics are an ubiquitous phenomenon in astrophysics. They are present at all length scales, ranging from those found in young stellar objects (YSOs, Reipurth & Bally1991) and the galactic microquasars (Mirabel & Rodriguez 1994, Fender & Belloni 2004), to kpc-scale relativistic jets in AGNs. In many cases these appear to be symmetrical, with two oppositely directed lines of flow, and almost always they seem to be directly connected with accretion onto a central object at the base of the collimated outflow. The energy in the outflow itself ultimately comes from the gravitational potential well created by the central object. The structure and evolution of jet-like structures under a variety of physical conditions is a problem that generally requires numerical modelling. However, in certain cases valuable insight can be gained from purely hydrodynamical analytical solutions which exhibit outflows (or accretion) of varying characteristics. We show here several solutions of this type, applicable to various accretion scenarios. Assuming that our solutions are Jets, we applied the model to M87 scenario and to SN1987A scenario, assuming that our solutions are like accretion.

  10. Analysis of the SN 1987A neutrinos with a flexible spectral shape

    SciTech Connect

    Mirizzi, Alessandro; Raffelt, Georg G.

    2005-09-15

    We analyze the neutrino events from the supernova (SN) 1987A detected by the Kamiokande-II (KII) and Irvine-Michigan-Brookhaven (IMB) experiments. For the time-integrated flux we assume a quasithermal spectrum of the form (E/E{sub 0}){sup {alpha}}e{sup -({alpha}{sup +1})E/E{sub 0}} where {alpha} plays the role of a spectral index. This simple representation not only allows one to fit the total energy E{sub tot} emitted in {nu}{sub e} and the average energy , but also accommodates a wide range of shapes, notably antipinched spectra that are broader than a thermal distribution. We find that the pile-up of low-energy events near threshold in KII forces the best-fit value for {alpha} to the lowest value of any assumed prior range. This applies to the KII events alone as well as to a common analysis of the two data sets. The preference of the data for an 'unphysical' spectral shape implies that one can extract meaningful values for and E{sub tot} only if one fixes a prior value for {alpha}. The tension between the KII and IMB data sets and theoretical expectations for is not resolved by an antipinched spectrum.

  11. Explosive nucleosynthesis in SN 1987A. II - Composition, radioactivities, and the neutron star mass

    NASA Technical Reports Server (NTRS)

    Thielemann, Friedrich-Karl; Hashimoto, Masa-Aki; Nomoto, Ken'ichi

    1990-01-01

    The 20 solar mass model of Nomoto and Hashimoto (1988) is utilized with a 6 solar mass. He core is used to perform explosive nucleosynthesis calculations. The employed explosion energy of 10 to the 51st ergs lies within the uncertainty range inferred from the bolometric light curve. The nucleosynthesis processes and their burning products are discussed in detail. The results are compared with abundances from IR observations of SN 1987A and the average nucleosynthesis expected for Type II supernovae in Galactic chemical evolution. The abundances of long-lived radioactive nuclei and their importance for the late light curve and gamma-ray observations are predicted. The position of the mass cut between the neutron star and the ejecta is deduced from the total amount of ejected Ni-56. This requires a neutron star with a baryonic mass of 1.6 + or - 0.045 solar mass, which corresponds to a gravitational mass of 1.43 + or - 0.05 solar mass after subtracting the binding energy of a nonrotating neutron star.

  12. INFRARED CONTINUUM AND LINE EVOLUTION OF THE EQUATORIAL RING AROUND SN 1987A

    SciTech Connect

    Arendt, Richard G.; Frank, Kari A.; Gehrz, Robert D.; Woodward, Charles E.; Park, Sangwook

    2016-03-15

    Spitzer observations of SN 1987A have now spanned more than a decade. Since day ∼4000, mid-infrared (mid-IR) emission has been dominated by that from shock-heated dust in the equatorial ring (ER). From 6000 to 8000 days after the explosion, Spitzer observations included broadband photometry at 3.6–24 μm, and low and moderate resolution spectroscopy at 5–35 μm. Here we present later Spitzer observations, through day 10,377, which include only the broadband measurements at 3.6 and 4.5 μm. These data show that the 3.6 and 4.5 μm brightness has clearly begun to fade after day ∼8500, and no longer tracks the X-ray emission as well as it did at earlier epochs. This can be explained by the destruction of the dust in the ER on timescales shorter than the cooling time for the shocked gas. We find that the evolution of the late time IR emission is also similar to the now fading optical emission. We provide the complete record of the IR emission lines, as seen by Spitzer prior to day 8000. The past evolution of the gas as seen by the IR emission lines seems largely consistent with the optical emission, although the IR [Fe ii] and [Si ii] lines show different, peculiar velocity structures.

  13. RE-EXAMINATION OF THE EXPECTED GAMMA-RAY EMISSION OF SUPERNOVA REMNANT SN 1987A

    SciTech Connect

    Berezhko, E. G.; Ksenofontov, L. T.; Völk, H. J.

    2015-09-01

    A nonlinear kinetic theory, combining cosmic-ray (CR) acceleration in supernova remnants (SNRs) with their gas dynamics, is used to re-examine the nonthermal properties of the remnant of SN 1987A for an extended evolutionary period of 5–50 year. This spherically symmetric model is approximately applied to the different features of the SNR, consisting of (i) a blue supergiant wind and bubble, and (ii) of the swept-up red supergiant (RSG) wind structures in the form of an H ii region, an equatorial ring (ER), and an hourglass region. The RSG wind involves a mass loss rate that decreases significantly with elevation above and below the equatorial plane. The model adapts recent three-dimensional hydrodynamical simulations by Potter et al. in 2014 that use a significantlysmaller ionized mass of the ER than assumed in the earlier studies by the present authors. The SNR shock recently swept up the ER, which is the densest region in the immediate circumstellar environment. Therefore, the expected gamma-ray energy flux density at TeV energies in the current epoch has already reached its maximal value of ∼10{sup −13} erg cm{sup −2} s{sup −1}. This flux should decrease by a factor of about two over the next 10 years.

  14. Infrared Continuum and Line Evolution of the Equatorial Ring around SN 1987A

    NASA Astrophysics Data System (ADS)

    Arendt, Richard G.; Dwek, Eli; Bouchet, Patrice; Danziger, I. John; Frank, Kari A.; Gehrz, Robert D.; Park, Sangwook; Woodward, Charles E.

    2016-03-01

    Spitzer observations of SN 1987A have now spanned more than a decade. Since day ˜4000, mid-infrared (mid-IR) emission has been dominated by that from shock-heated dust in the equatorial ring (ER). From 6000 to 8000 days after the explosion, Spitzer observations included broadband photometry at 3.6-24 μm, and low and moderate resolution spectroscopy at 5-35 μm. Here we present later Spitzer observations, through day 10,377, which include only the broadband measurements at 3.6 and 4.5 μm. These data show that the 3.6 and 4.5 μm brightness has clearly begun to fade after day ˜8500, and no longer tracks the X-ray emission as well as it did at earlier epochs. This can be explained by the destruction of the dust in the ER on timescales shorter than the cooling time for the shocked gas. We find that the evolution of the late time IR emission is also similar to the now fading optical emission. We provide the complete record of the IR emission lines, as seen by Spitzer prior to day 8000. The past evolution of the gas as seen by the IR emission lines seems largely consistent with the optical emission, although the IR [Fe ii] and [Si ii] lines show different, peculiar velocity structures.

  15. Infrared Continuum and Line Evolution of the Equatorial Ring Around SN 1987A

    NASA Technical Reports Server (NTRS)

    Arendt, Richard G.; Dwek, Eli; Bouchet, Patrice; Danziger, I. John; Frank, Kari A.; Gehrz, Robert D.; Park, Sangwook; Woodward, Charles E.

    2017-01-01

    Spitzer observations of SN 1987A have now spanned more than a decade. Since day approximately 4000, mid-infrared (mid-IR) emission has been dominated by that from shock-heated dust in the equatorial ring (ER). From 6000 to 8000 days after the explosion, Spitzer observations included broadband photometry at 3.6-24 micrometer, and low and moderate resolution spectroscopy at 5-35 micrometer. Here we present later Spitzer observations, through day 10,377, which include only the broadband measurements at 3.6 and 4.5 micrometer. These data show that the 3.6 and 4.5 micrometer brightness has clearly begun to fade after day approximately 8500, and no longer tracks the X-ray emission as well as it did at earlier epochs. This can be explained by the destruction of the dust in the ER on timescales shorter than the cooling time for the shocked gas. We find that the evolution of the late time IR emission is also similar to the now fading optical emission. We provide the complete record of the IR emission lines, as seen by Spitzer prior to day 8000. The past evolution of the gas as seen by the IR emission lines seems largely consistent with the optical emission, although the IR [Fe(II)]and [Si(II)]lines show different, peculiar velocity structures.

  16. Re-examination of the Expected Gamma-Ray Emission of Supernova Remnant SN 1987A

    NASA Astrophysics Data System (ADS)

    Berezhko, E. G.; Ksenofontov, L. T.; Völk, H. J.

    2015-09-01

    A nonlinear kinetic theory, combining cosmic-ray (CR) acceleration in supernova remnants (SNRs) with their gas dynamics, is used to re-examine the nonthermal properties of the remnant of SN 1987A for an extended evolutionary period of 5-50 year. This spherically symmetric model is approximately applied to the different features of the SNR, consisting of (i) a blue supergiant wind and bubble, and (ii) of the swept-up red supergiant (RSG) wind structures in the form of an H ii region, an equatorial ring (ER), and an hourglass region. The RSG wind involves a mass loss rate that decreases significantly with elevation above and below the equatorial plane. The model adapts recent three-dimensional hydrodynamical simulations by Potter et al. in 2014 that use a significantlysmaller ionized mass of the ER than assumed in the earlier studies by the present authors. The SNR shock recently swept up the ER, which is the densest region in the immediate circumstellar environment. Therefore, the expected gamma-ray energy flux density at TeV energies in the current epoch has already reached its maximal value of ˜10-13 erg cm-2 s-1. This flux should decrease by a factor of about two over the next 10 years.

  17. Far-infrared spectrophotometry of SN 1987A - Days 265 and 267

    NASA Technical Reports Server (NTRS)

    Moseley, S. H.; Dwek, E.; Silverberg, R. F.; Glaccum, W.; Graham, J. R.; Loewenstein, R. F.

    1989-01-01

    The paper presents 16-66-micron spectra of SN 1987A taken on days 266 and 268 after core collapse. The spectrum consists of a nearly flat continuum, strong emission lines of hydrogen, and fine-structure lines of Fe II, Fe III, Co II, S I, and possibly Fe I, Ni II, and S III. From the relative strength of three lines which arise from transitions within the ground and excited states of Fe II, the temperature and a lower limit on the density of the line-emitting region are derived. From the line strengths, the abundances of Fe and S I, the end products of explosive nucleosynthesis in the supernova are estimated. An upper limit is also set to the amount of Co II remaining in the mantle. The low measured mass of Fe suggests that the ejecta are clumpy. The flat continuum is most likely free-free emission from the expanding supernova ejecta. About 35 percent of this emission arises from the ionized metals in the mantle; the rest arises from ionized hydrogen. At the time of these observations, there is no evidence for any emission from dust that may have formed in the supernova ejecta or from preexisting dust in the surrounding medium.

  18. Far-infrared spectrophotometry of SN 1987A - Days 265 and 267

    SciTech Connect

    Moseley, S.H.; Dwek, E.; Silverberg, R.F.; Glaccum, W.; Graham, J.R.; Loewenstein, R.F. Applied Research Corp., Landover, MD California Institute of Technology, Pasadena Yerkes Observatory, Williams Bay, WI )

    1989-12-01

    The paper presents 16-66-micron spectra of SN 1987A taken on days 266 and 268 after core collapse. The spectrum consists of a nearly flat continuum, strong emission lines of hydrogen, and fine-structure lines of Fe II, Fe III, Co II, S I, and possibly Fe I, Ni II, and S III. From the relative strength of three lines which arise from transitions within the ground and excited states of Fe II, the temperature and a lower limit on the density of the line-emitting region are derived. From the line strengths, the abundances of Fe and S I, the end products of explosive nucleosynthesis in the supernova are estimated. An upper limit is also set to the amount of Co II remaining in the mantle. The low measured mass of Fe suggests that the ejecta are clumpy. The flat continuum is most likely free-free emission from the expanding supernova ejecta. About 35 percent of this emission arises from the ionized metals in the mantle; the rest arises from ionized hydrogen. At the time of these observations, there is no evidence for any emission from dust that may have formed in the supernova ejecta or from preexisting dust in the surrounding medium. 53 refs.

  19. Neutrino properties from SN 1987A and from future observations of GSC.

    NASA Astrophysics Data System (ADS)

    Dar, A.

    The early neutrino signal reported by the Mont Blanc group on Feb 23, 1987 was not produced by a neutrino burst from SN 1987A. The second neutrino burst that was reported by the KAMIOKANDE II, the IMB and the Baksan groups is consistent with the general theoretical picture of supernovae explosions, but it also has unexpected features. Analysis of the neutrino burst yields new limits on the lifetime, mass, mixing, and electric charge of the νe, and new limits on the magnetic moment and the radiative lifetime of light neutrinos. These limits imply that neither decay, nor mixing, nor electric charge, nor magnetic moment of the νe are responsible for the solar neutrino problem. Similar limits on the properties of the νμ and the ντ require the observation of a gravitational stellar collapse in the Galaxy with more advanced neutrino telescopes which are under construction. Such limits, when obtained, will resolve the question whether relic neutrinos from the big bang can close the universe.

  20. SN 1987A after 18 Years: Mid-Infrared GEMINI and SPITZER Observations of the Remnant

    NASA Technical Reports Server (NTRS)

    Bouchet, Patrice; Dwek, Eli; Danziger, John; Arendt, Richard G.; DeBuizer, James M.; Park, Sangwook; Suntzeff, Nicholas B.; Kirshner, Robert P.; Challis, Peter

    2007-01-01

    We present high resolution 11.7 and 18.3 micron mid-IR images of SN 1987A obtained on day 6526 since the explosion with the Thermal-Region Camera and Spectrograph (T-ReCS) attached to the Gemini South 8m telescope. The 11.7 micron flux has increased significantly since our last observations on day 6067. The images clearly show that all the emission arises from the equatorial ring (ER). Nearly contemporaneous spectra obtained on day 6184 with the MIPS at 24 micron, on day 6130 with the IRAC in 3.6- 8 micron region, and on day 6190 with the IRS in the 12-37 micron instruments on board the Spitzer Space Telescope's show that the emission consists of thermal emission from silicate dust that condensed out in the red giant wind of the progenitor star. The dust temperature is 1662(sup +18) (sub -12) K, and the emitting dust mass is (2.6(sup +2.0 (sub -1.4)) x 10 (exp -6) M(solar). Lines of [Ne II] 12.82 micron and [Ne III] 15.56 pm are clearly present in the Spitzer spectrum, as well as a weak [Si II] 3 34.8 micron line. We also detect two lines near 26 micron which we tentatively ascribe to [Fe II] 25.99 pm and [0 IV] 25.91 micron. Comparison of the mid-IR Gemini 11.7 micron image with X-ray images obtained by Chandra, UV-optical images obtained by HST, and radio synchrotron images obtained by the ATCA show generally good correlation of the images across all wavelengths. Because of the limited resolution of the mid-IR images we cannot uniquely determine the location. or heating mechanism of the dust giving rise to the emission. The dust could be collisionally heated by the X-ray emitting plasma, providing a unique diagnostic of plasma conditions. Alternatively, the dust could be radiatively heated in the dense UV-optical knots that are overrun by the advancing supernova blast wave. In either case the dust-to-gas mass ratio in the circumstellar medium around the supernova is significantly lower than that in the general interstellar medium of the LMC, suggesting either a

  1. q -deformed statistics and the role of light fermionic dark matter in SN1987A cooling

    NASA Astrophysics Data System (ADS)

    Guha, Atanu; J, Selvaganapathy; Das, Prasanta Kumar

    2017-01-01

    The light dark matter (≃1 - 30 MeV ) particles pair produced in electron-positron annihilation e-e+→ γ χ χ ¯ inside the supernova core can take away the energy released in the supernova SN1987A explosion. Working within the formalism of q -deformed statistics [with the average value of the supernovae core temperature (fluctuating) being TS N=30 MeV ] and using the Raffelt's criterion on the emissivity for any new channel ɛ ˙ (e+e-→χ χ ¯ )≤1 019 erg g-1 s-1 , we find that as the deformation parameter q changes from 1.0 (undeformed scenario) to 1.1 (deformed scenario), the lower bound on the scale Λ of the dark matter effective theory varies from 3.3 ×1 06 TeV to 3.2 ×1 07 TeV for a dark matter fermion of mass mχ=30 MeV . Using the optical depth criteria on the free streaming of the dark matter fermion, we find the lower bound on Λ ˜1 08 TeV for mχ=30 MeV . In a scenario, where the dark matter fermions are pair produced in the outermost sector of the supernova core [with radius 0.9 Rc≤r ≤Rc , Rc(=10 km ) being the supernova core radius or the radius of protoneutron star], we find that the bound on Λ (˜3 ×1 07 TeV ) obtained from SN cooling criteria (Raffelt's criteria) is comparable with the bound obtained from free streaming (optical depth criterion) for light fermion dark matter of mass mχ=10 - 30 MeV .

  2. A New View of the Circumstellar Environment of SN 1987A

    NASA Astrophysics Data System (ADS)

    Sugerman, Ben E. K.; Crotts, Arlin P. S.; Kunkel, William E.; Heathcote, Stephen R.; Lawrence, Stephen S.

    2005-07-01

    We summarize the analysis of a uniform set of both previously known and newly discovered scattered-light echoes, detected within 30" of SN 1987A in 10 years of optical imaging, and with which we have constructed the most complete three-dimensional model of the progenitor's circumstellar environment. Surrounding the SN is a richly structured bipolar nebula. An outer, double-lobed ``peanut,'' which we believe is the contact discontinuity between the red supergiant and main-sequence winds, is a prolate shell extending 28 lt-yr along the poles and 11 lt-yr near the equator. Napoleon's Hat, previously believed to be an independent structure, is the waist of this peanut, which is pinched to a radius of 6 lt-yr. Interior, the innermost circumstellar material lies along a cylindrical hourglass, 1 lt-yr in radius and 4 lt-yr long, which connects to the peanut by a thick equatorial disk. The nebulae are inclined 41° south and 8° east of the line of sight, slightly elliptical in cross section, and marginally offset west of the SN. The three-dimensional geometry of the three circumstellar rings is studied, suggesting the northern and southern rings are located 1.3 and 1.0 lt-yr from the SN, while the equatorial ring is elliptical (b/a<~0.98) and spatially offset in the same direction as the hourglass. Dust-scattering models of the observed echo fluxes suggest that between the hourglass and bipolar lobes: the gas density drops from 1 to 3 cm-3 to >~0.03 cm-3 the maximum dust-grain size increases from ~0.2 to 2 μm and the silicate:carbonaceous dust ratio decreases. The nebulae have a total mass of ~1.7 Msolar, yielding a red-supergiant mass loss around 5×10-6 Msolar yr-1. We compare these results to current formation models and find that no model has successfully reproduced this system. However, our results suggest a heuristic evolutionary sequence in which the progenitor evolves through two ``blue loops,'' perhaps accompanied by a close binary companion.

  3. Coincidences among Mont Blanc, Kamiokande, Baksan, IMB, Frejus, Homestake and Plateau Rosa detectors during SN1987A.

    NASA Astrophysics Data System (ADS)

    Aglietta, M.; Badino, G.; Bologna, G.; Castagnoli, C.; Castellina, A.; Fulgione, W.; Galeotti, P.; Saavedra, O.; Trinchero, G.; Vernetto, S.

    Correlation analysis has been performed among the events recorded during the occurrence of SN1987A by the underground detectors of Mont Blanc, Kamiokande, Baksan, IMB, Frejus, Homestake and the EAS array of Plateau Rosa. A significative excess of coincidence exists between low energy events of Mont Blanc and IMB muons, in the time interval from 1:45 to 3:45 UT on Feb. 23, 1987.

  4. Tsallis Statistics and the Role of a Stabilized Radion in the Supernovae SN1987A Cooling

    NASA Astrophysics Data System (ADS)

    Das, Prasanta Kumar; Selvaganapathy, J.; Sharma, Chandradew; Jha, Tarun Kumar; Kumar, V. Sunil

    2013-11-01

    The radion in the two-brane Randall-Sundrum model is required to stabilize the size of the fifth (extra) spatial dimension. It can be copiously produced inside the supernova core due to electron-positron annihilation (e+e-→ϕ), plasmon-plasmon annihilation (γP+γP→ϕ) and nucleon-nucleon bremsstrahlung and can take away the energy released in SN1987A explosion. Working within the q-deformed statistics (Tsallis statistics) and using the "Raffelt criterion" on the supernovae cooling rate ˙ {ǎrepsilon}<= 1019 ergs g-1 s-1, we find that in Case I (cooling due to e+e-→ϕ channel): for q = 1.22, as the radion mass mϕ changes from 20 GeV to 150 GeV, the lower bound <ϕ> changes from 7 TeV to 1.5 TeV and in Case II (cooling due to γP+γP→ϕ channel): for q = 1.11, as mϕ ranges from 20 GeV to 150 GeV, the lower bound <ϕ> changes from 201 TeV to 3.3 TeV. We investigate the dependence of <ϕ> on q and found that in Case I: mϕ = 50(100) GeV, <ϕ> changes from 0.5(0.2) TeV (for q = 1.18) to 5.5(4.8) TeV (for q = 1.30) and in Case II: for mϕ = 50(100) GeV, <ϕ> changes from 0.8( 0.1) TeV (for q = 1.09) to 569(216) TeV (for q = 1.13). We also verified that the normal Fermi-Dirac and Bose-Einstein statistics get recovered from the Tsallis statistics in the q→1 limit.

  5. Multi-dimensional simulations of the expanding supernova remnant of SN 1987A

    SciTech Connect

    Potter, T. M.; Staveley-Smith, L.; Reville, B.; Ng, C.-Y.; Bicknell, G. V.; Sutherland, R. S.; Wagner, A. Y.

    2014-10-20

    The expanding remnant from SN 1987A is an excellent laboratory for investigating the physics of supernovae explosions. There is still a large number of outstanding questions, such as the reason for the asymmetric radio morphology, the structure of the pre-supernova environment, and the efficiency of particle acceleration at the supernova shock. We explore these questions using three-dimensional simulations of the expanding remnant between days 820 and 10,000 after the supernova. We combine a hydrodynamical simulation with semi-analytic treatments of diffusive shock acceleration and magnetic field amplification to derive radio emission as part of an inverse problem. Simulations show that an asymmetric explosion, combined with magnetic field amplification at the expanding shock, is able to replicate the persistent one-sided radio morphology of the remnant. We use an asymmetric Truelove and McKee progenitor with an envelope mass of 10 M {sub ☉} and an energy of 1.5 × 10{sup 44} J. A termination shock in the progenitor's stellar wind at a distance of 0.''43-0.''51 provides a good fit to the turn on of radio emission around day 1200. For the H II region, a minimum distance of 0.''63 ± 0.''01 and maximum particle number density of (7.11 ± 1.78) × 10{sup 7} m{sup –3} produces a good fit to the evolving average radius and velocity of the expanding shocks from day 2000 to day 7000 after explosion. The model predicts a noticeable reduction, and possibly a temporary reversal, in the asymmetric radio morphology of the remnant after day 7000, when the forward shock left the eastern lobe of the equatorial ring.

  6. Multi-dimensional Simulations of the Expanding Supernova Remnant of SN 1987A

    NASA Astrophysics Data System (ADS)

    Potter, T. M.; Staveley-Smith, L.; Reville, B.; Ng, C.-Y.; Bicknell, G. V.; Sutherland, R. S.; Wagner, A. Y.

    2014-10-01

    The expanding remnant from SN 1987A is an excellent laboratory for investigating the physics of supernovae explosions. There is still a large number of outstanding questions, such as the reason for the asymmetric radio morphology, the structure of the pre-supernova environment, and the efficiency of particle acceleration at the supernova shock. We explore these questions using three-dimensional simulations of the expanding remnant between days 820 and 10,000 after the supernova. We combine a hydrodynamical simulation with semi-analytic treatments of diffusive shock acceleration and magnetic field amplification to derive radio emission as part of an inverse problem. Simulations show that an asymmetric explosion, combined with magnetic field amplification at the expanding shock, is able to replicate the persistent one-sided radio morphology of the remnant. We use an asymmetric Truelove & McKee progenitor with an envelope mass of 10 M ⊙ and an energy of 1.5 × 1044 J. A termination shock in the progenitor's stellar wind at a distance of 0.''43-0.''51 provides a good fit to the turn on of radio emission around day 1200. For the H II region, a minimum distance of 0.''63 ± 0.''01 and maximum particle number density of (7.11 ± 1.78) × 107 m-3 produces a good fit to the evolving average radius and velocity of the expanding shocks from day 2000 to day 7000 after explosion. The model predicts a noticeable reduction, and possibly a temporary reversal, in the asymmetric radio morphology of the remnant after day 7000, when the forward shock left the eastern lobe of the equatorial ring.

  7. Supernova 1987A at 30

    NASA Astrophysics Data System (ADS)

    Spyromilio, J.; Leibundgut, B.; Fransson, C.; Larsson, J.; Migotto, K.; Girard, J.

    2017-03-01

    Thirty years on, SN 1987A continues to develop and, over the last decade in particular, has: revealed the presence of a large centrally concentrated reservoir of dust; shown the presence of molecular species within the ejecta; expanded such that the ejecta structure is angularly resolved; begun the destruction of the circumstellar ring and transitioned to being dominated by energy sources external to the ejecta. We are participating in a live experiment in the creation of a supernova remnant and here the recent progress is briefly overviewed. Exciting developments can be expected as the ejecta and the reverse shock continue their interaction, the X-rays penetrate into the cold molecular core and we observe the return of the material into the interstellar medium. We anticipate that the nature of the remnant of the leptonisation event in the centre will also be revealed.

  8. The triple-ring nebula around SN 1987A: fingerprint of a binary merger.

    PubMed

    Morris, Thomas; Podsiadlowski, Philipp

    2007-02-23

    Supernova 1987A, the first naked-eye supernova observed since Kepler's supernova in 1604, defies a number of theoretical expectations. Its anomalies have long been attributed to a merger between two massive stars that occurred some 20,000 years before the explosion, but so far there has been no conclusive proof that this merger took place. Here, we present three-dimensional hydrodynamical simulations of the mass ejection associated with such a merger and the subsequent evolution of the ejecta, and we show that this accurately reproduces the properties of the triple-ring nebula surrounding the supernova.

  9. The light curve of SN 1987A revisited: constraining production masses of radioactive nuclides

    SciTech Connect

    Seitenzahl, Ivo R.; Timmes, F. X.; Magkotsios, Georgios

    2014-09-01

    We revisit the evidence for the contribution of the long-lived radioactive nuclides {sup 44}Ti, {sup 55}Fe, {sup 56}Co, {sup 57}Co, and {sup 60}Co to the UVOIR light curve of SN 1987A. We show that the V-band luminosity constitutes a roughly constant fraction of the bolometric luminosity between 900 and 1900 days, and we obtain an approximate bolometric light curve out to 4334 days by scaling the late time V-band data by a constant factor where no bolometric light curve data is available. Considering the five most relevant decay chains starting at {sup 44}Ti, {sup 55}Co, {sup 56}Ni, {sup 57}Ni, and {sup 60}Co, we perform a least squares fit to the constructed composite bolometric light curve. For the nickel isotopes, we obtain best fit values of M({sup 56}Ni) = (7.1 ± 0.3) × 10{sup –2} M {sub ☉} and M({sup 57}Ni) = (4.1 ± 1.8) × 10{sup –3} M {sub ☉}. Our best fit {sup 44}Ti mass is M({sup 44}Ti) = (0.55 ± 0.17) × 10{sup –4} M {sub ☉}, which is in disagreement with the much higher (3.1 ± 0.8) × 10{sup –4} M {sub ☉} recently derived from INTEGRAL observations. The associated uncertainties far exceed the best fit values for {sup 55}Co and {sup 60}Co and, as a result, we only give upper limits on the production masses of M({sup 55}Co) < 7.2 × 10{sup –3} M {sub ☉} and M({sup 60}Co) < 1.7 × 10{sup –4} M {sub ☉}. Furthermore, we find that the leptonic channels in the decay of {sup 57}Co (internal conversion and Auger electrons) are a significant contribution and constitute up to 15.5% of the total luminosity. Consideration of the kinetic energy of these electrons is essential in lowering our best fit nickel isotope production ratio to [{sup 57}Ni/{sup 56}Ni] = 2.5 ± 1.1, which is still somewhat high but is in agreement with gamma-ray observations and model predictions.

  10. The Light Curve of SN 1987A Revisited: Constraining Production Masses of Radioactive Nuclides

    NASA Astrophysics Data System (ADS)

    Seitenzahl, Ivo R.; Timmes, F. X.; Magkotsios, Georgios

    2014-09-01

    We revisit the evidence for the contribution of the long-lived radioactive nuclides 44Ti, 55Fe, 56Co, 57Co, and 60Co to the UVOIR light curve of SN 1987A. We show that the V-band luminosity constitutes a roughly constant fraction of the bolometric luminosity between 900 and 1900 days, and we obtain an approximate bolometric light curve out to 4334 days by scaling the late time V-band data by a constant factor where no bolometric light curve data is available. Considering the five most relevant decay chains starting at 44Ti, 55Co, 56Ni, 57Ni, and 60Co, we perform a least squares fit to the constructed composite bolometric light curve. For the nickel isotopes, we obtain best fit values of M(56Ni) = (7.1 ± 0.3) × 10-2 M ⊙ and M(57Ni) = (4.1 ± 1.8) × 10-3 M ⊙. Our best fit 44Ti mass is M(44Ti) = (0.55 ± 0.17) × 10-4 M ⊙, which is in disagreement with the much higher (3.1 ± 0.8) × 10-4 M ⊙ recently derived from INTEGRAL observations. The associated uncertainties far exceed the best fit values for 55Co and 60Co and, as a result, we only give upper limits on the production masses of M(55Co) < 7.2 × 10-3 M ⊙ and M(60Co) < 1.7 × 10-4 M ⊙. Furthermore, we find that the leptonic channels in the decay of 57Co (internal conversion and Auger electrons) are a significant contribution and constitute up to 15.5% of the total luminosity. Consideration of the kinetic energy of these electrons is essential in lowering our best fit nickel isotope production ratio to [57Ni/56Ni] = 2.5 ± 1.1, which is still somewhat high but is in agreement with gamma-ray observations and model predictions.

  11. Supernova 1987A in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Kafatos, Minas; Michalitsianos, Andrew G.

    2006-11-01

    Foreword; Acknowledgements; Workshop participants; 1. Images and spectrograms of Sanduleak - 69º202, the SN 1987a progenitor N. R. Walborn; 2. The progenitor of SN 1987A G. Sonneborn; 3. Another supernova with a blue progenitor C. M. Gaskell and W. C. Keel; 4. Optical and infrared observations of SN 1987A from Cerro Tololo Inter-American Observatory M. M. Phillips; 5. SN 1987A: observational results obtained at ESO I. J. Danziger, P. Bouchet, R. A. E. Fosbury, C. Gouiffes, L. B. Lucy, A. F. M. Moorwood, E. Oliva and F. Rufener; 6. Observations of SN 1987A at the South African Astronomical Observatory (SAAO) M. W. Feast; 7. Observations of SN 1987A at the Anglo-Australian Telescope W. J. Couch; 8. Linear polarimetric study of SN 1987A A. Clocchiatti, M. Méndez, O. Benvenuto, C. Feinstein, H. Marraco, B. García and N. Morrell; 9. Infrared spectroscopy of SN 1987A from the NASA Kuiper Airborne Observatory H. P. Larson, S. Drapatz, M. J. Mumma and H. A. Weaver; 10. Radio observations of SN 1987A N. Bartel et al.; 11. Ultraviolet observations of SN 1987A: clues to mass loss R. P. Kirshner; 12. On the energetics of SN 1987A N. Panagia; 13. On the nature and apparent uniqueness of SN 1987A A. V. Filippenko; 14. A comparison of the SN 1987A light curve with other type II supernovae, and the detectability of similar supernovae M. F. Schmitz and C. M. Gaskell; 15. P-Cygni features and photospheric velocities L. Bildsten and J. C. L. Wang; 16. The Neutrino burst from SN 1987A detected in the Mont Blanc LSD experiment M. Aglietta et al.; 17. Toward observational neutrino astrophysics M. Koshiba; 18. The discovery of neutrinos from SN 1987A with the IMB detector J. Matthews; 19. Peering into the abyss: the neutrinos from SN 1987A A. Burrows; 20. Phenomenological analysis of neutrino emission from SN 1987A J. N. Bahcall, D. N. Spergel and W. H. Press; 21. Mass determination of neutrinos H. Y. Chiu; 22. Neutrino transport in a type II supernova D. C. Ellison, P. M. Giovanoni

  12. Modelling supernova line profile asymmetries to determine ejecta dust masses: SN 1987A from days 714 to 3604

    NASA Astrophysics Data System (ADS)

    Bevan, Antonia; Barlow, M. J.

    2016-02-01

    The late-time optical and near-IR line profiles of many core-collapse supernovae exhibit a red-blue asymmetry as a result of greater extinction by internal dust of radiation emitted from the receding parts of the supernova ejecta. We present here a new code, DAMOCLES, that models the effects of dust on the line profiles of core-collapse supernovae in order to determine newly formed dust masses. We find that late-time dust-affected line profiles may exhibit an extended red scattering wing (as noted by Lucy et al. 1989) and that they need not be flux-biased towards the blue, although the profile peak will always be blueshifted. We have collated optical spectra of SN 1987A from a variety of archival sources and have modelled the Hα line from days 714 to 3604 and the [O I] 6300,6363 Å doublet between days 714 and 1478. Our line profile fits rule out day 714 dust masses >3 × 10-3 M⊙ for all grain types apart from pure magnesium silicates, for which no more than 0.07 M⊙ can be accommodated. Large grain radii ( ≥ 0.6 μm) are generally required to fit the line profiles even at the earlier epochs. We find that a large dust mass (≥0.1 M⊙) had formed by day 3604 and infer that the majority of the present dust mass must have formed after this epoch. Our findings agree with recent estimates from spectral energy distribution fits for the dust mass evolution of SN 1987A and support the inference that the majority of SN 1987A's dust formed many years after the initial explosion.

  13. Neutrino Signal of Collapse-induced Thermonuclear Supernovae: The Case for Prompt Black Hole Formation in SN 1987A

    NASA Astrophysics Data System (ADS)

    Blum, Kfir; Kushnir, Doron

    2016-09-01

    Collapse-induced thermonuclear explosion (CITE) may explain core-collapse supernovae (CCSNe). We analyze the neutrino signal in CITE and compare it to the neutrino burst of SN 1987A. For strong (≳ {10}51 erg) CCSNe, such as SN 1987A, CITE predicts a proto-neutron star (PNS) accretion phase lasting up to a few seconds that is cut off by black hole (BH) formation. The neutrino luminosity can later be revived by accretion disk emission after a dead time of a few to a few tens of seconds. In contrast, the neutrino mechanism for CCSNe predicts a short (≲s) PNS accretion phase, followed by slowly declining PNS cooling luminosity. We repeat statistical analyses used in the literature to interpret the neutrino mechanism, and apply them to CITE. The first 1-2 s of the neutrino burst are equally compatible with CITE and with the neutrino mechanism. However, the data points toward a luminosity drop at t = 2-3 s, which is in some tension with the neutrino mechanism but can be naturally attributed to BH formation in CITE. The occurrence of neutrino signal events at 5 s suggests that, within CITE, the accretion disk formed by that time. We perform two-dimensional numerical simulations showing that CITE may be able to accommodate this disk formation time while reproducing the ejected 56Ni mass and ejecta kinetic energy within factors of 2-3 of observations. We estimate the accretion disk neutrino luminosity, finding it to be on the low side but compatible with the data to a factor of 10. Given comparable uncertainties in the disk luminosity simulation, we conclude that direct BH formation may have occurred in SN 1987A.

  14. Nickel, argon and cobalt in the infrared spectrum of SN1987A - The core becomes visible

    NASA Technical Reports Server (NTRS)

    Rank, D. M.; Pinto, P. A.; Woosley, S. E.; Bregman, J. D.; Witteborn, F. C.

    1988-01-01

    Infrared spectra of supernova 1987A taken in April and November 1987 are presented, showing two distinctly different stages in the evolution of the expanding gas shell. The optical and infrared spectrum in April originated from the hydrogen envelope and show weak hydrogen lines rising above a 5,000-K photospheric continuum. The November spectrum was dominated by strong emission lines from heavy elements as well as many lines from highly excited levels of hydrogen, with peak flux levels in the lines at or slightly above the level of the continuum in April. It is concluded that the inner regions of the supernova were just becoming visible in early 1988. It is expected that these regions contain heavy elements produced by advanced nuclear burning stages in the progenitor star and in the shock wave that ejected all material external to the iron core.

  15. Limits to the radiative decays of neutrinos and axions from gamma-ray observations of SN 1987A

    NASA Technical Reports Server (NTRS)

    Kolb, Edward W.; Turner, Michael S.

    1989-01-01

    Gamma-ray observations obtained by the SMM gamma-ray spectrometer in the energy range 4.1-6.4 MeV are used to provide limits on the possible radiative decay of neutrinos and axions emitted by SN 1987A. For branching ratio values for the radiative decay modes of less than about 0.0001, the present limits are more stringent than those based upon the photon flux from decaying relic neutrinos. The data are also used to set an axion mass limit.

  16. A 2.14 ms candidate optical pulsar in SN1987A: Ten years after

    SciTech Connect

    Middleditch, J.; Kristian, J.A.; Kunkel, W.E.; Hill, K.M.; Watson, R.D.

    1997-09-01

    We have monitored Supernova 1987A in optical/near-infrared bands from a few weeks following its birth until the present time in order to search for a pulsar remnant. We have found an apparent pattern of emission near the frequency of 467.5 Hz - a 2.14 ms pulsar candidate, first detected in data taken on the remnant at the Las Campanas Observatory (LCO) 2.5-m Dupont telescope during 14-16 Feb. 1992 UT. We detected further signals near the 2.14 ms period on numerous occasions over the next four years in data taken with a variety of telescopes, data systems and detectors, at a number of ground- and space-based observatories. The sequence of detections of this signal from Feb. `92 through August `93, prior to its apparent subsequent fading, is highly improbable (< 10{sup -10} for any noise source). We also find evidence for modulation of the 2.14 ms period with a {approx}1,000 s period which, when taken with the high spindown of the source (2-3 x 10{sup -10} Hz/s), is consistent with precession and spindown via gravitational radiation of a neutron star with a non- axisymmetric oblateness of {approx}10{sup -6}, and an implied gravitational luminosity exceeding that of the Crab Nebula pulsar by an order of magnitude.

  17. Neutrinos from SN 1987A - Implications for cooling of the nascent neutron star and the mass of the electron antineutrino

    NASA Technical Reports Server (NTRS)

    Loredo, Thomas J.; Lamb, Don Q.

    1989-01-01

    Data on neutrinos from SN 1987A are compared here with parameterized models of the neutrino emission using a consistent and straightforward statistical methodology. The empirically measured detector background spectra are included in the analysis, and the data are compared with a much wider variety of neutrino emission models than was explored previously. It is shown that the inferred neutrino emission model parameters are strongly correlated. The analysis confirms that simple models of the neutrino cooling of the nascent neutron star formed by the SN adequately explain the data. The inferred radius and binding energy of the neutron star are in excellent agreement with model calculations based on a wide range of equations of state. The results also raise the upper limit of the electron antineutrino rest mass to roughly 25 eV at the 95 percent confidence level, roughly 1.5-5 times higher than found previously.

  18. Correlation analysis of the data recorded by the Baksan, Kamioka, and Mont Blanc detectors during SN 1987A

    NASA Astrophysics Data System (ADS)

    Aglietta, M.; Badino, G.; Bologna, G.; Castagnoli, C.; Castellina, A.

    1989-12-01

    Results are presented on the correlation analysis of data recorded by the Baksan, Kamioka, and Mont Blanc underground detectors during the explosion of the SN 1987. The analysis was performed in order to reinvestigate the observations of two burst of several pulses each occurring several hours before first optical observations. The Mont Blanc computer detected a burst of five pulses about 8 hrs before the first optical observation, followed by a second burst of three pulses about 2 hrs later; Kamioka and Baksan reported observations of a burst made by eleven and five pulses, respectively, delayed by 4.7 hrs in comparison with the Mont Blanc burst. The results of the analysis strongly suggest that the event was real, occurring a few hours before the first optical observation of SN 1987A.

  19. Unparticle constraints from supernova 1987A

    SciTech Connect

    Hannestad, Steen; Raffelt, Georg; Wong, Yvonne Y. Y.

    2007-12-15

    The existence of an unparticle sector, weakly coupled to the standard model, would have a profound impact on supernova (SN) physics. Emission of energy into the unparticle sector from the core of SN 1987A would have significantly shortened the observed neutrino burst. The unparticle interaction with nucleons, neutrinos, electrons and muons is constrained to be so weak that it is unlikely to provide any missing-energy signature at colliders. One important exception are models where scale invariance in the hidden sector is broken by the Higgs vacuum expectation value. In this case the SN emission is suppressed by threshold effects.

  20. Airborne spectrophotometry of SN 1987A from 1.7 to 12.6 microns - Time history of the dust continuum and line emission

    NASA Technical Reports Server (NTRS)

    Wooden, Diane H.; Rank, David M.; Bregman, Jesse D.; Witteborn, Fred C.; Tielens, A. G. G. M.; Cohen, Martin; Pinto, Philip A.; Axelrod, Timothy S.

    1993-01-01

    Spectrophotometric observations of SN 1987A from the Kuiper Airborne Observatory are presented for five epochs at 60, 260, 415, 615, and 775 days after the explosion. The low-resolution (lambda/Delta lambda = 50-100) spectra of SN 1987A are combined with data from other wavelengths to model the continuum, subtract the continuum from the spectra to determine line strengths and reveal molecular bands, separate the atomic continuum radiation from the dust continuum, and derive constraints on the grain temperatures and optical depths. A scenario for the evolution of SN 1987A and that of the ejecta from which it arises is obtained on the basis of the analysis of the continuum emission.

  1. The bolometric light curve of SN 1987A. I - Results from ESO and CTIO U to Q0 photometry

    NASA Astrophysics Data System (ADS)

    Suntzeff, Nicholas B.; Bouchet, Patrice

    1990-02-01

    The UV, optical, and IR (UVOIR) bolometric luminosity curve of SN 1987A was derived from ESO, CTIO, and NASA Kuiper Airborne Observatory spectrophotometry for days 1-903 since outburst. It is found that the sum of this UVOIR flux and the high-energy flux predicted by models is consistent with the energy liberated by 0.071 solar mass of Co-56, with no need for additional energy sources for days 126-903 since outburst. By day 400, the flux at wavelegths larger than 5 microns was found to increase rapidly, and by day 650, the UVOIR flux shifted from the optical to a thermal IR source with a temperature of 200-300 K. The optical colors began to fade more rapidly at the time the FIR flux increased, consistent with dust formation local to the supernova.

  2. Hubble Observations of Supernova 1987A, 1994-2006

    NASA Video Gallery

    A time-lapse sequence of 12 years of Hubble observing SN 1987A shows the onrushing stellar shock wave from the stellar explosion as it is slamming into, heating up, and illuminating the inner regio...

  3. Gamma rays, X-rays, and optical light from the cobalt and the neutron star in SN 1987A

    NASA Technical Reports Server (NTRS)

    Kumagai, Shiomi; Shigeyama, Toshikazu; Nomoto, Ken'ichi; Itoh, Masayuki; Nishimura, Jun

    1989-01-01

    Recent developments in modeling the X-ray and gamma-ray emission from SN 1987A are discussed by taking into account both the decaying cobalt and the buried neutron star. The light curve and the spectra evolution of X-rays and gamma-rays are well modeled up to day of about 300 if mixing of Co-56 into hydrogen-rich envelope is assumed. However, the 16-28 keV flux observed by Ginga declines very slowly, whereas the spherical mixing model predicts that the flux should have decreased by a large factor at t greater than 300d. It is shown that this problem can be solved if the photoelectric absorption of X-rays is effectively reduced as a result of the formation of chemically inhomogeneous clumps. Based on the adopted hydrodynamical model and the abundance distribution, predictions are offered for future optical, X-ray, and gamma-ray light curves by taking into account other radioactive sources and various types of the central source, e.g., a buried neutron star accreting the reinfalling material or an isolated pulsar.

  4. Reduced upper limits on the equivalent width of interstellar Li I 670.8 towards SN 1987 A

    NASA Astrophysics Data System (ADS)

    Baade, D.; Cristiani, S.; Lanz, T.; Malaney, R. A.; Sahu, K. S.; Vladilo, G.

    1991-11-01

    A new search for interstellar Li I 670.8 along the line of sight to SN 1987 A has been carried out using all 34 known high-resolution Reticon spectra obtained at the European Southern Observatory. The most probably 3-sigma detection limit in equivalent width is 7.3 x 10 exp -6 nm. For the cloud at radial velocity +286 km/s, standard relations then imply a maximum abundance, Li/H, of 1.7 x 10 exp -11 in the gaseous interstellar medium of the LMC. If depletion to dust grains is the same for both lithium and potassium, this figure has to be increased by 1.1 dex. Accordingly, conventional present-day reasoning suggests that the elemental abundance of lithium does not exceed 2.7 x 10 exp -10. However, the cumulative uncertainties are such that a primordial abundance which is an order of magnitude higher is not firmly ruled out. Constraints on primordial nucleosynthesis models are, therefore, only weak.

  5. High-resolution mid-infrared spectra of Co II, Ni I, and Fe II in SN 1987A

    NASA Technical Reports Server (NTRS)

    Jennings, D. E.; Boyle, R. J.; Wiedemann, G. R.; Moseley, S. H.

    1993-01-01

    Ground-based infrared observations of SN 1987A on day 612 after the explosion have yielded resolved line profiles of Co II, Ni I, Fe II at 10.52, 11.31, and 17.94 micron, respectively. The spectra were taken at a resolving power of about 1000 with an array grating spectrometer on the 4 m telescope of Cerro Tololo Inter-American Observatory. Based on the observed line intensities we have estimated the minimum mass of each ion: M(Co II) = (6.0 +/- 1.8) x 10 exp -5 solar mass; M(Ni I) = (1.1 +/- 0.1) x 10 exp -3 solar mass; and M(Fe II) = (8.0 +/- 1.5) x 10 exp -3 solar mass. From these we infer total masses for cobalt, nickel, and iron in the ejecta. The nickel and iron line profiles are markedly asymmetric. We interpret these as arising from two components, one centered on the stellar rest velocity with an approximately 3250 km/s full width, and the second at about +1200 km/s with an approximately 1100 km/s full width. The asymmetry may represent a large-scale fracturing of the ejecta by Rayleigh-Taylor instabilities.

  6. High-resolution mid-infrared spectra of Co II, Ni I, and Fe II in SN 1987A

    NASA Astrophysics Data System (ADS)

    Jennings, D. E.; Boyle, R. J.; Wiedemann, G. R.; Moseley, S. H.

    1993-05-01

    Ground-based infrared observations of SN 1987A on day 612 after the explosion have yielded resolved line profiles of Co II, Ni I, Fe II at 10.52, 11.31, and 17.94 micron, respectively. The spectra were taken at a resolving power of about 1000 with an array grating spectrometer on the 4 m telescope of Cerro Tololo Inter-American Observatory. Based on the observed line intensities we have estimated the minimum mass of each ion: M(Co II) = (6.0 +/- 1.8) x 10 exp -5 solar mass; M(Ni I) = (1.1 +/- 0.1) x 10 exp -3 solar mass; and M(Fe II) = (8.0 +/- 1.5) x 10 exp -3 solar mass. From these we infer total masses for cobalt, nickel, and iron in the ejecta. The nickel and iron line profiles are markedly asymmetric. We interpret these as arising from two components, one centered on the stellar rest velocity with an approximately 3250 km/s full width, and the second at about +1200 km/s with an approximately 1100 km/s full width. The asymmetry may represent a large-scale fracturing of the ejecta by Rayleigh-Taylor instabilities.

  7. SN1987A: correlation between the data recorded by the Mont Blanc neutrino detector and by the Maryland and Rome gravitational wave antennas.

    NASA Astrophysics Data System (ADS)

    Pallottino, G. V.

    The author reports the analysis of gravitational wave and neutrino detectors over a period of 18 hours that includes the Mont Blanc 5 neutrino burst time. There is statistical evidence for correlations during a period of about two hours, centered on the 5 neutrino burst: the effect is mainly due to a dozen of large amplitude Maryland and Rome events. The interpretation of these events as due to gravitational radiation from SN1987A should be rejected, according to the standard theory of the cross-section of g.w. detectors, since it would imply an emission of energy too large by a factor of about 104.

  8. IAUS 331: Supernova 1987A thirty years later

    NASA Astrophysics Data System (ADS)

    Ray, Alak

    2017-04-01

    First the neutrinos arrived, then the burst of light: messengers of a cataclysmic event in the galaxy next door. Alak Ray recounts IAUS 331, a conference that celebrated the thirtieth anniversary of the supernova of a lifetime, SN1987A, and explored the critical role of asymmetry in the explosions, surroundings and initial conditions.

  9. Radio evolution of the remnant of Supernova 1987A

    NASA Astrophysics Data System (ADS)

    Zanardo, Giovanna

    Radio supernovae result from the collision between a supernova (SN) shock and the progenitor's circumstellar medium (CSM). Supernova 1987A in the Large Magellanic Cloud, as the only nearby core-collapse supernova observed with a telescope since its early stages, has allowed unique studies of the SN-CSM interaction and the complex structure of the resulting emission. This thesis investigates the evolution of the remnant of SN 1987A, as the shock wave impacts the dense CSM in the equatorial ring, and the possible presence of a compact object in the remnant interior, using new data from the Australia Telescope Compact Array, the Atacama Large Millimeter/submillimeter Array, the Australian Long Baseline Array, and the Parkes telescope.

  10. HST-COS OBSERVATIONS OF HYDROGEN, HELIUM, CARBON, AND NITROGEN EMISSION FROM THE SN 1987A REVERSE SHOCK

    SciTech Connect

    France, Kevin; Penton, Steven V.; McCray, Richard; Kirshner, Robert P.; Challis, Peter; Laming, Martin J.; Bouchet, Patrice; Garnavich, Peter M.; Fransson, Claes; Larsson, Josefin; Lundqvist, Peter; Sollerman, Jesper; Heng, Kevin; Lawrence, Stephen; Panagia, Nino; Pun, Chun S. J.; Smith, Nathan; Sonneborn, George; Sugerman, Ben; and others

    2011-12-20

    We present the most sensitive ultraviolet observations of Supernova 1987A to date. Imaging spectroscopy from the Hubble Space Telescope-Cosmic Origins Spectrograph shows many narrow ({Delta}v {approx} 300 km s{sup -1}) emission lines from the circumstellar ring, broad ({Delta}v {approx} 10-20 Multiplication-Sign 10{sup 3} km s{sup -1}) emission lines from the reverse shock, and ultraviolet continuum emission. The high signal-to-noise ratio (>40 per resolution element) broad Ly{alpha} emission is excited by soft X-ray and EUV heating of mostly neutral gas in the circumstellar ring and outer supernova debris. The ultraviolet continuum at {lambda} > 1350 A can be explained by H I two-photon (2s {sup 2} S{sub 1/2}-1s {sup 2} S{sub 1/2}) emission from the same region. We confirm our earlier, tentative detection of N V {lambda}1240 emission from the reverse shock and present the first detections of broad He II {lambda}1640, C IV {lambda}1550, and N IV] {lambda}1486 emission lines from the reverse shock. The helium abundance in the high-velocity material is He/H = 0.14 {+-} 0.06. The N V/H{alpha} line ratio requires partial ion-electron equilibration (T{sub e} /T{sub p} Almost-Equal-To 0.14-0.35). We find that the N/C abundance ratio in the gas crossing the reverse shock is significantly higher than that in the circumstellar ring, a result that may be attributed to chemical stratification in the outer envelope of the supernova progenitor. The N/C abundance may have been stratified prior to the ring expulsion, or this result may indicate continued CNO processing in the progenitor subsequent to the expulsion of the circumstellar ring.

  11. HST-COS Observations on Hydrogen, Helium, Carbon, and Nitrogen Emission from the SN 1987A Reverse Shock

    NASA Technical Reports Server (NTRS)

    France, Kevin; McCray, Richard; Penton, Steven V.; Kirshner, Robert P.; Challis, Peter; Laming, J. Martin; Bouchet, Patrice; Chevalier, Roger; Garnavich, Peter M.; Fransson, Claes; Heng, Kevin; Larsson, Josefin; Lawrence, Stephen; Lundqvist, Peter; Panagia, Nino; Pun, Chun S. J.; Smith, Nathan; Sollerman, Jesper; Sonneborn, George; Sugerman, Ben; Wheeler, J. Craig

    2011-01-01

    We present the most sensitive ultraviolet observations of Supernova 1987 A to date. Imaging spectroscopy from the Hubble Space Telescope-Cosmic Origins Spectrograph shows many narrow (Delta v approximates 300 km/s) emission lines from the circumstellar ring, broad Delta v approximates 10-20 x 10(exp 3) km/s) emission lines from the reverse shock, and ultraviolet continuum emission. The high signal-to-noise ratio (>40 per resolution element) broad Ly-alpha emission is excited by soft X-ray and EUV heating of mostly neutral gas in the circumstellar ring and outer supernova debris. The ultraviolet continuum at lambda > 1350 A can be explained by H-I two-photon (2s(exp 2)S(sub 1/2)-l(exp 2)S(sub 1/2)) emission from the same region. We confirm our earlier, tentative detection of N V lambda 1240 emission from the reverse shock and present the first detections of broad He II lambda1640, C IV lambda 1550, and N IV ] lambda1486 emission lines from the reverse shock. The helium abundance in the high-velocity material is He/H = 0.14 +/- 0.06. The N V /H alpha line ratio requires partial ion-electron equilibration (T(sub e)/T(sub p) approximately equal to 0.14-0.35). We find that the N/C abundance ratio in the gas crossing the reverse shock is significantly higher than that in the circumstellar ring, a result that may be attributed to chemical stratification in the outer envelope of the supernova progenitor. The N/C abundance may have been stratified prior to the ring expUlsion, or this result may indicate continued CNO processing in the progenitor subsequent to the expUlsion of the circumstellar ring.

  12. The Remnant of Supernova 1987A

    NASA Astrophysics Data System (ADS)

    McCray, Richard; Fransson, Claes

    2016-09-01

    Although it has faded by a factor of ˜107, SN 1987A is still bright enough to be observed in almost every band of the electromagnetic spectrum. Today, the bolometric luminosity of the debris is dominated by a far-infrared (˜200μm) continuum from ˜0.5 M⊙ of dust grains in the interior debris. The dust is heated by UV, optical, and near-infrared (NIR) emission resulting from radioactive energy deposition by 44Ti. The optical light of the supernova debris is now dominated by illumination of the debris by X-rays resulting from the impact of the outer supernova envelope with an equatorial ring (ER) of gas that was expelled some 20,000 years before the supernova explosion. X-ray and optical observations trace a complex system of shocks resulting from this impact, whereas radio observations trace synchrotron radiation from relativistic electrons accelerated by these shocks. The luminosity of the remnant is dominated by an NIR (˜20μm) continuum from dust grains in the ER heated by collisions with ions in the X-ray emitting gas. With the Atacama Large Millimeter Array (ALMA), we can observe the interior debris at millimeter/submillimeter wavelengths, which are not absorbed by the interior dust. The ALMA observations reveal bright emission lines from rotational transitions of CO and SiO lines that provide a new window into the interior structure of the supernova debris. Optical, NIR, and ALMA observations all indicate strongly asymmetric ejecta. Intensive searches have failed to yield any evidence for the compact object expected to reside at the center of the remnant. The current upper limit to the luminosity of such an object is a few tens of solar luminosities.

  13. Toward Connecting Core-Collapse Supernova Theory with Observations: Nucleosynthetic Yields and Distribution of Elements in a 15 M⊙ Blue Supergiant Progenitor with SN 1987A Energetics

    NASA Astrophysics Data System (ADS)

    Plewa, Tomasz; Handy, Timothy; Odrzywolek, Andrzej

    2014-03-01

    We compute and discuss the process of nucleosynthesis in a series of core-collapse explosion models of a 15 solar mass, blue supergiant progenitor. We obtain nucleosynthetic yields and study the evolution of the chemical element distribution from the moment of core bounce until young supernova remnant phase. Our models show how the process of energy deposition due to radioactive decay modifies the dynamics and the core ejecta structure on small and intermediate scales. The results are compared against observations of young supernova remnants including Cas A and the recent data obtained for SN 1987A. The work has been supported by the NSF grant AST-1109113 and DOE grant DE-FG52-09NA29548. This research used resources of the National Energy Research Scientific Computing Center, which is supported by the U.S. DoE under Contract No. DE-AC02-05CH11231.

  14. SN 1987 A - Correlations between the Maryland and Rome gravitational wave detector data and the Mont Blanc and KAMIOKANDE neutrino detector data

    NASA Astrophysics Data System (ADS)

    Pallottino, G. V.

    1990-02-01

    The paper describes the analysis of data obtained in the period 12 h of February 22, 1987 to 6 h of February 23, 1987, that includes the time of neutrino observation with the Mont Blanc detector during SN 1987 A. A very significant correlation has been observed among the data of the above detectors in a period of one or two hours which includes the time of the Mont Blanc 5-neutrino observation. The correlation between the gravitational wave detector data and the Kamiokande data is found if a time of 7.8 s is added to the Kamioka recorded time; this is very close to the time difference, 6.2 s, between the IMB and Kamioka large neutrino bursts observed at about 7 h 35 min.

  15. Supernova 1987 A - The nebular loops and 'Napoleon's Hat'

    NASA Astrophysics Data System (ADS)

    Wang, L.; Wampler, E. J.

    1992-08-01

    We discuss observations of the circumstellar environment of SN 1987A that were obtained between August 1989 and January 1992 at ESO's New Technology Telescope. We find that the angular dimensions of the two nebular loops (Wampler et al., 1990) have not changed during this period. Therefore these loops are confined to a small region. The expansion velocity of the loops is less than about 40 km/s if the loops expanded with a uniform velocity from a common origin. This structure and velocity is hard to reproduce with existing wind interaction models. Our observations further suggest that the Napoleon's Hat nebula does not originate from the general background LMC dust, but from a bow shock dust whose origins are closely related to the stellar winds from the progenitor star of SN 1987A.

  16. Preliminary results from a search for TeV {gamma}-ray emission from SN1987A and the surrounding field with H.E.S.S

    SciTech Connect

    Rowell, G.; Hinton, J.; Benbow, W.

    2005-02-21

    H.E.S.S. has observed the very young supernova remnant SN1987A during 2003 in a search for TeV {gamma}-ray emission. These observations were taken during a build-up phase of H.E.S.S. with 2 operating telescopes, {approx}6400 days after the initial explosion. Preliminary analysis so far reveals no convincing evidence for TeV emission and the 99% upper limit is compared with a predicted light curve. The H.E.S.S. field of view encompasses a number of other interesting objects including the X-ray shell 30 Dor C, the Crab-like plerion PSR B0540-69, the SNR N157B, and the X-ray binary LMC X-1. These objects may be associated with several features seen in the H.E.S.S. skymaps at marginal significances, and further observations in 2004/2005 with 4 telescopes will be valuable for confirmation.

  17. Observing Supernova 1987A with the Refurbished Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    France, Kevin; McCray, Richard; Heng, Kevin; Kirshner, Robert P.; Challis, Peter; Bouchet, Patrice; Crotts, Arlin; Dwek, Eli; Fransson, Claes; Garnavich, Peter M.; Larsson, Josefin; Lundqvist, Peter; Panagia, Nino; Pun, Chun S. J.; Smith, Nathan; Sollerman, Jesper; Sonneborn, George; Stocke, John T.; Wheeler, J. Craig

    2010-01-01

    The young remnant of supernova 1987A (SN 1987A) offers an unprecedented glimpse into the hydrodynamics and kinetics of fast astrophysical shocks. We have been monitoring SN 1987A with the Hubble Space Telescope (HST) since it was launched. The recent repair of the Space Telescope Imaging Spectrograph (STIS) allows us to compare observations in 2004, just before its demise, with those in 2010, shortly after its resuscitation by NASA astronauts. We find that the Ly-alpha and H-alpha lines from shock emission continue to brighten, while their maximum velocities continue to decrease. We report evidence for nearly coherent, resonant scattering of Lya photons (to blueshifts approximately -12,000 km /s) from hotspots on the equatorial ring. We also report emission to the red of Ly-alpha that we attribute to N v lambda lambda 1239,1243 Angstrom line emission. These lines are detectable because, unlike hydrogen atoms, N4+ ions emit hundreds of photons before they are ionized. The profiles of the N v lines differ markedly from that of H-alpha. We attribute this to scattering of N4+ ions by magnetic fields in the ionized plasma. Thus, N v emission provides a unique probe of the isotropization zone of the collisionless shock. Observations with the recently installed Cosmic Origins Spectrograph (COS) will enable us to observe the N v lambda lambda 1239,1243 Angstrom line profiles with much higher signal-to-noise ratios than possible with STIS and may reveal lines of other highly ionized species (such as C IVlambda lambda 1548,1551 Angstrom) that will test our explanation for the N v emission

  18. Supernova 1987A: The Supernova of a Lifetime

    NASA Astrophysics Data System (ADS)

    Kirshner, Robert

    2017-01-01

    Supernova 1987A, the brightest supernova since Kepler's in 1604, was detected 30 years ago at a distance of 160 000 light years in the Large Magellanic Cloud, a satellite galaxy of the Milky Way. Visible with the naked eye and detected with the full range of technology constructed since Kepler's time, SN 1987A has continued to be a rich source of empirical information to help understand supernova explosions and their evolution into supernova remnants. While the light output has faded by a factor of 10 000 000 over those 30 years, instrumentation, like the Hubble Space Telescope, the Chandra X-ray Observatory, and the Atacama Large Millimeter Array has continued to improve so that this supernova continues to be visible in X-rays, ultraviolet light, visible light, infrared light and in radio emission. In this review, I will sketch what has been learned from these observations about the pre-supernova star and its final stages of evolution, the explosion physics, the energy sources for emission, and the shock physics as the expanding debris encounters the circumstellar ring that was created about 20 000 years before the explosion. Today, SN 1987A is making the transition to a supernova remnant- the energetics are no longer dominated by the radioactive elements produced in the explosion, but by the interaction of the expanding debris with the surrounding gas. While we are confident that the supernova explosion had its origin in gravitational collapse, careful searches for a compact object at the center of the remnant place upper limits of a few solar luminosities on that relic. Support for HST GO programs 13401 and 13405 was provided by NASA through grants 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. The X-ray evolution of SNR 1987A

    NASA Astrophysics Data System (ADS)

    Burrows, David N.; Frank, Kari A.; Park, Sangwook; McCray, Richard; Zhekov, Svetozar

    2016-06-01

    Due to its age and close proximity, the remnant of SN 1987A is the only supernova remnant in which we can study the early developmental stages in detail, providing insight into stellar evolution, the mechanisms of the supernova explosion, and the transition from supernova to supernova remnant as the debris begins to interact with the surrounding circumstellar medium (CSM). We present the latest results from 16 years of Chandra ACIS observations of SN 1987A, now covering 4600-10600 days after the supernova. At approximately day 7500, the east-west asymmetry of the ring began to reverse, while the soft X-ray light curve switched from an exponential increase to a linear brightening. Since day 9700 the soft X-ray light curve has flattened and remained approximately constant at about 8×10^(12) ergs/cm^2/s, evidence that the blast wave has now left the dense material of the known equatorial ring and is beginning to probe the unknown territory beyond.

  20. Five Years of Mid-Infrared Evolution of the Remnant of SN 1987A: The Encounter Between the Blast Wave and the Dusty Equatorial Ring

    NASA Technical Reports Server (NTRS)

    Dwek, Eli; Arendt, Richard G.; Bouchet, Patrice; Burrows, David N.; Challis, Peter; Danziger, I. John; De Buizer, James M.; Gehrz, Robert D.; Park, Sangwook; Polomski, Elisha F.; Slavin, Jonathan D.; Woodward, Charles E.

    2010-01-01

    We have used the Spitzer satellite to monitor the laid-IR evolution of SN 1987A over a 5 year period spanning the epochs between days 6000 and 8000 since the explosion. The supernova (SN) has evolved into a supernova remnant (SNR) and its radiative output, is dominated by the interaction of the SN blast wave with the pre-existing equatorial ring (ER). The mid-IR spectrum is dominated by emission from approximately 180 K silicate dust, collisionally-heated by the hot X-ray emitting gas with a temperature and density of 5 x 10(exp 6) K and approximately 3 x 10(exp 4) per cubic centimeter, respectively. The mass of the radiating dust is approximately 1.2 x 10(exp -6) solar mass on day 7554, and scales linearly with IR flux. Comparison of the IR data with the soft X-ray flux derived from Chandra observations shows that the IR-to-X-ray flux ratio, IRX, is roughly constant with a value of 2.5. Gas-grain collisions therefore dominate the cooling of the shocked gas. The constancy of IRX is most consistent with the scenario that very little grain processing or gas cooling have occurred throughout this epoch. The shape of the dust spectrum remained unchanged during the observations while the total flux increased by a factor of approximately 5 with a time dependence of t(sup '0.87 plus or minus 0.20), t' being the time since the first encounter between the blast wave and the ER. These observations are consistent with the transitioning of the blast wave from free expansion to a Sedov phase as it propagates into the main body of the ER, as also suggested by X-ray observations. The constant spectral shape of they IR, emission provides strong constraints on the density and temperature of the shocked gas in which the interaction takes place. The IR spectra also suggest the presence of a secondary population of very small, hot (T greater than or equal to 350 K), featureless dust. If these grains spatially coexists with the silicates, then they must have shorter lifetimes. The data

  1. Toward connecting core-collapse supernova theory with observations. I. Shock revival in a 15 M {sub ☉} blue supergiant progenitor with SN 1987A energetics

    SciTech Connect

    Handy, Timothy; Plewa, Tomasz; Odrzywołek, Andrzej

    2014-03-10

    We study the evolution of the collapsing core of a 15 M {sub ☉} blue supergiant supernova progenitor from the core bounce until 1.5 s later. We present a sample of hydrodynamic models parameterized to match the explosion energetics of SN 1987A. We find the spatial model dimensionality to be an important contributing factor in the explosion process. Compared to two-dimensional (2D) simulations, our three-dimensional (3D) models require lower neutrino luminosities to produce equally energetic explosions. We estimate that the convective engine in our models is 4% more efficient in 3D than in 2D. We propose that the greater efficiency of the convective engine found in 3D simulations might be due to the larger surface-to-volume ratio of convective plumes, which aids in distributing energy deposited by neutrinos. We do not find evidence of the standing accretion shock instability or turbulence being a key factor in powering the explosion in our models. Instead, the analysis of the energy transport in the post-shock region reveals characteristics of penetrative convection. The explosion energy decreases dramatically once the resolution is inadequate to capture the morphology of convection on large scales. This shows that the role of dimensionality is secondary to correctly accounting for the basic physics of the explosion. We also analyze information provided by particle tracers embedded in the flow and find that the unbound material has relatively long residency times in 2D models, while in 3D a significant fraction of the explosion energy is carried by particles with relatively short residency times.

  2. Light echoes - supernovae 1987A and 1986G

    SciTech Connect

    Schaefer, B.E.

    1987-12-01

    The sudden brilliance of a supernova (SN) eruption will be reflected on surrounding dust grains to create a phantom nebula. The paper presents a series of calculations in which the apparent brightness of this light echo is predicted for a variety of situations where the dust is part of the interstellar medium (ISM). It is found that the supernova 1987 A will have a very bright echo off the ISM that may perhaps be visible with binoculars for many years. At a time of 400 days past maximum, the SN 1986G is found to be 2.7 mag brighter than would be predicted by an extrapolation of its light curve. This unique property has an easy explanation as a light echo off the dust in the dust lane of Cen A. 24 references.

  3. Hubble Reveals Structure Of Supernova 1987a Explosion Debris

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This Hubble Space Telescope picture shows Supernova 1987A and its neighborhood. The series of four panels shows the evolution of the SN 1987A debris from February 1994 to February 1996. Material from the stellar interior was ejected into space during the supernova explosion in February 1987. The explosion debris is expanding at nearly 6 million miles per hour. Ten years now after the explosion, this cosmic fireball is large enough --- about one-sixth of a light-year in diameter --- to be resolved from the Earth's orbit with the Hubble Space Telescope. The debris is resolved into two opposing blobs and is dim in the center. The apparent direction of ejection is the same as the short axis of the bright inner ring that surrounds the supernova. This suggests that the explosion is directed out of the plane of the ring. The ring is probably composed of materials lost by the pre-supernova star in the last stages of its evolution. Supernova 1987A is located 167,000 light-years away from Earth in the Large Magellanic Cloud. The telescope captured the images with the Wide Field and Planetary Camera 2. The central image of the supernova and the ring system was taken in light emitted by nitrogen gas (658 nanometers) on Sept. 24, 1994. The series of debris images were taken using a visible light filter of wavelength around 550 nanometers taken (from left to right) on Feb. 4, 1994, Sept. 24, 1994, March 5, 1995, and Feb. 6, 1996. Credit: Chun Shing Jason Pun (NASA/GSFC), Robert P. Kirshner (Harvard-Smithsonian Center for Astrophysics), and NASA

  4. Revisiting Supernova 1987A constraints on dark photons

    NASA Astrophysics Data System (ADS)

    Chang, Jae Hyeok; Essig, Rouven; McDermott, Samuel D.

    2017-01-01

    We revisit constraints on dark photons with masses below ˜ 100 MeV from the observations of Supernova 1987A. If dark photons are produced in sufficient quantity, they reduce the amount of energy emitted in the form of neutrinos, in conflict with observations. For the first time, we include the effects of finite temperature and density on the kinetic-mixing parameter, ɛ, in this environment. This causes the constraints on ɛ to weaken with the dark-photon mass below ˜ 15 MeV. For large-enough values of ɛ, it is well known that dark photons can be reabsorbed within the supernova. Since the rates of reabsorption processes decrease as the dark-photon energy increases, we point out that dark photons with energies above the Wien peak can escape without scattering, contributing more to energy loss than is possible assuming a blackbody spectrum. Furthermore, we estimate the systematic uncertainties on the cooling bounds by deriving constraints assuming one analytic and four different simulated temperature and density profiles of the proto-neutron star. Finally, we estimate also the systematic uncertainty on the bound by varying the distance across which dark photons must propagate from their point of production to be able to affect the star. This work clarifies the bounds from SN1987A on the dark-photon parameter space.

  5. PHOTOMETRIC DETERMINATION OF THE MASS ACCRETION RATES OF PRE-MAIN-SEQUENCE STARS. I. METHOD AND APPLICATION TO THE SN 1987A FIELD

    SciTech Connect

    De Marchi, Guido; Panagia, Nino; Romaniello, Martino E-mail: panagia@stsci.ed

    2010-05-20

    We have developed and successfully tested a new self-consistent method to reliably identify pre-main-sequence (PMS) objects actively undergoing mass accretion in a resolved stellar population, regardless of their age. The method does not require spectroscopy and combines broadband V and I photometry with narrowband H{alpha} imaging to (1) identify all stars with excess H{alpha} emission, (2) convert the excess H{alpha} magnitude into H{alpha} luminosity L(H{alpha}), (3) estimate the H{alpha} emission equivalent width, (4) derive the accretion luminosity L{sub acc} from L(H{alpha}), and finally (5) obtain the mass accretion rate M-dot{sub acc} from L{sub acc} and the stellar parameters (mass and radius). By selecting stars with an accuracy of 15% or better in the H{alpha} photometry, the statistical uncertainty on the derived M-dot{sub acc} is typically {approx_lt}17% and is dictated by the precision of the H{alpha} photometry. Systematic uncertainties, of up to a factor of 3 on the value of M-dot{sub acc}, are caused by our incomplete understanding of the physics of the accretion process and affect all determinations of the mass accretion rate, including those based on a spectroscopic H{alpha} line analysis. As an application of our method, we study the accretion process in a field of 9.16 arcmin{sup 2} around SN 1987A, using existing Hubble Space Telescope photometry. We identify as bona fide PMS stars a total of 133 objects with a H{alpha} excess above the 4{sigma} level and a median age of 13.5 Myr. Their median mass accretion rate of 2.6 x 10{sup -8} M{sub sun} yr{sup -1} is in excellent agreement with previous determinations based on the U-band excess of the stars in the same field, as well as with the value measured for G-type PMS stars in the Milky Way. The accretion luminosity of these PMS objects shows a strong dependence on their distance from a group of hot massive stars in the field and suggests that the ultraviolet radiation of the latter is rapidly

  6. Herschel Detects a Massive Dust Reservoir in Supernova 1987A

    NASA Technical Reports Server (NTRS)

    Matsuura, M.; Dwek, E.; Meixner, M.; Otsuka, M.; Babler, B.; Barlow, M. J.; Roman-Duval, J.; Engelbracht, C.; Sandstrom K.; Lakicevic, M.; vanLoon, J. Th.; Sonneborn, G.; Clayton, G. C.; Long, K. S.; Lundqvist, P.; Nozawa, T.; Gordon, K. D.; Hony, S.; Okumura, K.; Misselt, K. A.; Montiel, E.; Sauvage, M.

    2011-01-01

    We report far-infrared and submillimeter observations of Supernova 1987A, the star that exploded on February 23, 1987 in the Large Magellanic Cloud, a galaxy located 160,000 light years away. The observations reveal the presence of a population of cold dust grains radiating with a temperature of approx.17-23 K at a rate of about 220 stellar luminosity. The intensity and spectral energy distribution of the emission suggests a dust mass of approx.0.4-0.7 stellar mass. The radiation must originate from the SN ejecta and requires the efficient precipitation of all refractory material into dust. Our observations imply that supernovae can produce the large dust masses detected in young galaxies at very high red shifts.

  7. Line fluorescence from the ring around supernova 1987A

    NASA Technical Reports Server (NTRS)

    Dwek, Eli; Felten, James E.

    1992-01-01

    Observations in lambda 5007 which reveal an ellipse of line emission around SN 1987A are reviewed. A simple expression for the rate at which the kinematically accessible paraboloid sweeps over the length of a thin uniform circular ring is derived, and a simple integral expression for the light curve F(t) of a fluorescent line in terms of epsilon(t), the local line emissivity, is presented. Many simple examples of the relationship between epsilon(t) and F(t) are graphed, and the results are used to deduce the characteristics of the local emissivity functions which produce the best fit to the observed semiforbidden N III 1750 and N V 1240 light curves. The N III and N V light curves are inverted to find the functions epsilon(t) which give best fits to the observations.

  8. Supernova 1987A Interpreted through the SLIP Pulsar Model

    NASA Astrophysics Data System (ADS)

    Middleditch, John

    2010-01-01

    The model of pulsar emission through superluminally induced polarization currents (SLIP) predicts that pulsations produced by such currents, induced by a rotating, magnetized body at many light cylinder radii, as would be the case for a neutron star born within any star of >1.5 solar masses, will drive pulsations close to the axis of rotation. Such highly collimated pulsations (<= 1 in 10,000), and the similarly collimated jets of particles which it drove, including 1e-6 solar masses with velocities of up to 0.95 c, were responsible for the features of its very early light curve (days 3 - 20), the "Mystery Spot," observed slightly later (days 30 - 50 and >), and later, in less collimated form, the bipolarity of SN 1987A itself. The pulsations and jet interacted with circumstellar material (CM), to produce features observed in the very early light curve which correspond to: 1) the entry of the pulsed beam into the CM; 2) the entry of the 0.95 c particles into the CM; 3) the exit of the pulsed beam from the CM (with contributions in the B and I bands -- the same as later inferred/observed for its 2.14 ms pulsations); and 4) the exit of the fastest particles from the CM. Because of the energy requirements of the jet in these early stages, the spindown required of its pulsar could exceed 1e-5 Hz/s at a rotation rate of 500 Hz. There is no reason to suggest that this mechanism is not universally applicable to all SNe with gaseous remnants remaining, and thus SN 1987A is the Rosetta Stone for 99% of SNe, gamma-ray bursts, and millisecond pulsars. This work was supported in part by the Department of Energy through the Los Alamos Directed Research Grant DR20080085.

  9. CARBON MONOXIDE IN THE COLD DEBRIS OF SUPERNOVA 1987A

    SciTech Connect

    Kamenetzky, J.; McCray, R.; Glenn, J.; Indebetouw, R.; Barlow, M. J.; Matsuura, M.; Baes, M.; Blommaert, J. A. D. L.; Decin, L.; Bolatto, A.; Dunne, L.; Fransson, C.; Gomez, H. L.; Groenewegen, M. A. T.; Hopwood, R.; Kirshner, R. P.; Lakicevic, M.; Marcaide, J.; Meixner, M.; and others

    2013-08-20

    We report spectroscopic and imaging observations of rotational transitions of cold CO and SiO in the ejecta of SN1987A, the first such emission detected in a supernova remnant. In addition to line luminosities for the CO J = 1-0, 2-1, 6-5, and 7-6 transitions, we present upper limits for all other transitions up to J = 13-12, collectively measured from the Atacama Large Millimeter Array, the Atacama Pathfinder EXperiment, and the Herschel Spectral and Photometric Imaging REceiver. Simple models show the lines are emitted from at least 0.01 M{sub Sun} of CO at a temperature >14 K, confined within at most 35% of a spherical volume expanding at {approx}2000 km s{sup -1}. Moreover, we locate the emission within 1'' of the central debris. These observations, along with a partial observation of SiO, confirm the presence of cold molecular gas within supernova remnants and provide insight into the physical conditions and chemical processes in the ejecta. Furthermore, we demonstrate the powerful new window into supernova ejecta offered by submillimeter observations.

  10. SUPERNOVA 1987A: A TEMPLATE TO LINK SUPERNOVAE TO THEIR REMNANTS

    SciTech Connect

    Orlando, S.; Miceli, M.; Pumo, M. L.; Bocchino, F.

    2015-09-10

    The emission of supernova remnants (SNRs) reflects the properties of both the progenitor supernovae (SNe) and the surrounding environment. The complex morphology of the remnants, however, hampers the disentanglement of the two contributions. Here, we aim at identifying the imprint of SN 1987A on the X-ray emission of its remnant and at constraining the structure of the environment surrounding the SN. We performed high-resolution hydrodynamic simulations describing SN 1987A soon after the core-collapse and the following three-dimensional expansion of its remnant between days 1 and 15,000 after the SN. We demonstrated that the physical model reproducing the main observables of SN 1987A during the first 250 days of evolution also reproduces the X-ray emission of the subsequent expanding remnant, thus bridging the gap between SNe and SNRs. By comparing model results with observations, we constrained the explosion energy in the range 1.2–1.4 × 10{sup 51} erg and the envelope mass in the range 15–17 M{sub ⊙}. We found that the shape of X-ray lightcurves and spectra at early epochs (<15 years) reflects the structure of outer ejecta: our model reproduces the observations if the outermost ejecta have a post-explosion radial profile of density approximated by a power law with index α = −8. At later epochs, the shapes of X-ray lightcurves and spectra reflect the density structure of the nebula around SN 1987A. This enabled us to ascertain the origin of the multi-thermal X-ray emission, disentangle the imprint of the SN on the remnant emission from the effects of the remnant interaction with the environment, and constrain the pre-supernova structure of the nebula.

  11. Supernova 1987A: a Template to Link Supernovae to Their Remnants

    NASA Astrophysics Data System (ADS)

    Orlando, S.; Miceli, M.; Pumo, M. L.; Bocchino, F.

    2015-09-01

    The emission of supernova remnants (SNRs) reflects the properties of both the progenitor supernovae (SNe) and the surrounding environment. The complex morphology of the remnants, however, hampers the disentanglement of the two contributions. Here, we aim at identifying the imprint of SN 1987A on the X-ray emission of its remnant and at constraining the structure of the environment surrounding the SN. We performed high-resolution hydrodynamic simulations describing SN 1987A soon after the core-collapse and the following three-dimensional expansion of its remnant between days 1 and 15,000 after the SN. We demonstrated that the physical model reproducing the main observables of SN 1987A during the first 250 days of evolution also reproduces the X-ray emission of the subsequent expanding remnant, thus bridging the gap between SNe and SNRs. By comparing model results with observations, we constrained the explosion energy in the range 1.2-1.4 × 1051 erg and the envelope mass in the range 15-17 M ⊙. We found that the shape of X-ray lightcurves and spectra at early epochs (<15 years) reflects the structure of outer ejecta: our model reproduces the observations if the outermost ejecta have a post-explosion radial profile of density approximated by a power law with index α = -8. At later epochs, the shapes of X-ray lightcurves and spectra reflect the density structure of the nebula around SN 1987A. This enabled us to ascertain the origin of the multi-thermal X-ray emission, disentangle the imprint of the SN on the remnant emission from the effects of the remnant interaction with the environment, and constrain the pre-supernova structure of the nebula.

  12. High-Velocity Ly(Alpha) Emission from SMR 1987A

    NASA Technical Reports Server (NTRS)

    Michael, Eli; McCray, Richard; Borkowski, Kazimierz J.; Pun, Chu S. J.; Sonneborn, George

    1998-01-01

    The high-velocity Ly(Alpha) emission from SN 1987A observed with the Space Telescope Imaging Spectrograph (STIS) evidently comes from a reverse shock formed where the outer envelope of SN 1987A strikes ionized gas inside the inner circumstellar ring. The observations can be explained by a simple kinematic model, in which the Ly(Alpha) emission comes from hydrogen atoms with radial velocity approximately 15,000 km s(exp -1) crossing a reverse shock in the shape of a slightly prolate ellipsoid with equatorial radius 4.8 x 10(exp 17) cm or approximately 80% of the distance to the inner surface of the inner ring. N v double Lambda 1239, 1243 emission, if present, has a net luminosity approximately less than 30% times that of the Ly(Alpha) emission. Future STIS observations should enable us to predict the time of impact with the inner ring and to determine unambiguously whether or not N v emission is present. These observations will offer a unique opportunity to probe the structure of SN 1987A's circumstellar environment and the hydrodynamics and kinetics of very fast shocks.

  13. Supernova 1987A: neutrino-driven explosions in three dimensions and light curves

    NASA Astrophysics Data System (ADS)

    Utrobin, V. P.; Wongwathanarat, A.; Janka, H.-Th.; Müller, E.

    2015-09-01

    Context. The well-observed and well-studied type IIP Supernova 1987A (SN 1987A), produced by the explosion of a blue supergiant in the Large Magellanic Cloud, is a touchstone for the evolution of massive stars, the simulation of neutrino-driven explosions, and the modeling of light curves and spectra. Aims: In the framework of the neutrino-driven explosion mechanism, we study the dependence of explosion properties on the structure of different blue supergiant progenitors and compare the corresponding light curves with observations of SN 1987A. Methods: Three-dimensional (3D) simulations of neutrino-driven explosions are performed with the explicit, finite-volume, Eulerian, multifluid hydrodynamics code Prometheus, using of four available presupernova models as initial data. At a stage of almost homologous expansion, the hydrodynamical and composition variables of the 3D models are mapped to a spherically symmetric configuration, and the simulations are continued with the implicit, Lagrangian radiation-hydrodynamics code Crab to follow the blast-wave evolution into the SN outburst. Results: All of our 3D neutrino-driven explosion models, with explosion energies compatible with SN 1987A, produce 56Ni in rough agreement with the amount deduced from fitting the radioactively powered light-curve tail. Two of our models (based on the same progenitor) yield maximum velocities of around 3000 km s-1 for the bulk of ejected 56Ni, consistent with observational data. In all of our models inward mixing of hydrogen during the 3D evolution leads to minimum velocities of hydrogen-rich matter below 100 km s-1, which is in good agreement with spectral observations. However, the explosion of only one of the considered progenitors reproduces the shape of the broad light curve maximum of SN 1987A fairly well. Conclusions: The considered presupernova models, 3D explosion simulations, and light-curve calculations can explain the basic observational features of SN 1987A, except for those

  14. When will a pulsar in supernova 1987a be seen?

    PubMed

    Michel, F C; Kennel, C F; Fowler, W A

    1987-11-13

    The means by which a pulsar might be detected in the remnant of supernova 1987a in the Large Magelanic Cloud is examined. One possibility is that the slower-than-radioactive decay typically seen in the type II light curves is itself the sign of powering by the underlying pulsar, with the decline representing not the spinning down of the pulsar but rather the declining nebular opacity that would allow increasing amounts of the energy to escape as gamma rays. The test of this hypothesis (if the supernova conforms to type II expectations) would be to look for the "missing" energy in the form of those gamma rays that escape from the remnant instead of powering it.

  15. When will a pulsar in supernova 1987a be seen?

    NASA Technical Reports Server (NTRS)

    Michel, F. Curtis; Kennel, C. F.; Fowler, William A.

    1987-01-01

    The means by which a pulsar might be detected in the remnant of supernova 1987a in the Large Magellanic Cloud is examined. One possibility is that the slower-than-radioactive decay typically seen in the type II light curves is itself the sign of powering by the underlying pulsar, with the decline representing not the spinning down of the pulsar but rather the declining nebular opacity that would allow increasing amounts of the energy to escape as gamma rays. The test of this hypothesis (if the supernova conforms to type II expectations) would be to look for the 'missing' energy in the form of those gamma rays that escape from the remnant instead of powering it.

  16. Observing supernova 1987A with the refurbished Hubble Space Telescope.

    PubMed

    France, Kevin; McCray, Richard; Heng, Kevin; Kirshner, Robert P; Challis, Peter; Bouchet, Patrice; Crotts, Arlin; Dwek, Eli; Fransson, Claes; Garnavich, Peter M; Larsson, Josefin; Lawrence, Stephen S; Lundqvist, Peter; Panagia, Nino; Pun, Chun S J; Smith, Nathan; Sollerman, Jesper; Sonneborn, George; Stocke, John T; Wang, Lifan; Wheeler, J Craig

    2010-09-24

    Observations with the Hubble Space Telescope (HST), conducted since 1990, now offer an unprecedented glimpse into fast astrophysical shocks in the young remnant of supernova 1987A. Comparing observations taken in 2010 with the use of the refurbished instruments on HST with data taken in 2004, just before the Space Telescope Imaging Spectrograph failed, we find that the Lyα and Hα lines from shock emission continue to brighten, whereas their maximum velocities continue to decrease. We observe broad, blueshifted Lyα, which we attribute to resonant scattering of photons emitted from hot spots on the equatorial ring. We also detect N v λλ1239, 1243 angstrom line emission, but only to the red of Lyα. The profiles of the N v lines differ markedly from that of Hα, suggesting that the N4+ ions are scattered and accelerated by turbulent electromagnetic fields that isotropize the ions in the collisionless shock.

  17. Herschel detects a massive dust reservoir in supernova 1987A.

    PubMed

    Matsuura, M; Dwek, E; Meixner, M; Otsuka, M; Babler, B; Barlow, M J; Roman-Duval, J; Engelbracht, C; Sandstrom, K; Lakićević, M; van Loon, J Th; Sonneborn, G; Clayton, G C; Long, K S; Lundqvist, P; Nozawa, T; Gordon, K D; Hony, S; Panuzzo, P; Okumura, K; Misselt, K A; Montiel, E; Sauvage, M

    2011-09-02

    We report far-infrared and submillimeter observations of supernova 1987A, the star whose explosion was observed on 23 February 1987 in the Large Magellanic Cloud, a galaxy located 160,000 light years away. The observations reveal the presence of a population of cold dust grains radiating with a temperature of about 17 to 23 kelvin at a rate of about 220 times the luminosity of the Sun. The intensity and spectral energy distribution of the emission suggest a dust mass of about 0.4 to 0.7 times the mass of the Sun. The radiation must originate from the supernova ejecta and requires the efficient precipitation of all refractory material into dust. Our observations imply that supernovae can produce the large dust masses detected in young galaxies at very high redshifts.

  18. Neutrino out-blow from supernova 1987A detected in the Mont Blanc observatory

    NASA Astrophysics Data System (ADS)

    Aglietta, M.; Badino, G.; Bologna, G.; Castagnoli, C.; Castellina, A.

    The authors discuss the neutrino outflow connected with the event detected in the Mont Blanc Underground Neutrino Observatory on February 23, 1987, and consisting of 5 interactions recorded during 7 seconds. The measured energies of the 5 pulses, the duration of the burst, and the advance of the detection time in comparison with the first optical observations give evidence that the event can be explained in terms of detection of neutrinos emitted during the stellar collapse in the Large Magellanic Cloud, which originated supernova SN 1987A.

  19. Dust Production and Particle Acceleration in Supernova 1987A Revealed with ALMA

    NASA Technical Reports Server (NTRS)

    Indebetouw, R.; Matsuura, M.; Dwek, E.; Zanardo, G.; Barlow, M. J.; Baes, M.; Bouchet, P.; Burrows, D. N.; Chevalier, R.; Clayton, G. C.; Fransson, C.; Gaensler, B.; Kirshner, R.; Lakicevic, M.; Long, K. S.; Lundqvist, P.; Marti-Vidal, I.; Marcaide, J.; McCray, R.; Meixner, M.; Ng, C.-Y.; Park, S.; Sonneborn, G.; Staveley-Smith, L.; vanLoon, J.

    2014-01-01

    Supernova (SN) explosions are crucial engines driving the evolution of galaxies by shock heating gas, increasing the metallicity, creating dust, and accelerating energetic particles. In 2012 we used the Atacama Large Millimeter/ Submillimeter Array to observe SN1987A, one of the best-observed supernovae since the invention of the telescope. We present spatially resolved images at 450 µm, 870 µm, 1.4 mm, and 2.8 mm, an important transition wavelength range. Longer wavelength emission is dominated by synchrotron radiation from shock-accelerated particles, shorter wavelengths by emission from the largest mass of dust measured in a supernova remnant (>0.2 Solar Mass). For the first time we show unambiguously that this dust has formed in the inner ejecta (the cold remnants of the exploded star's core). The dust emission is concentrated at the center of the remnant, so the dust has not yet been affected by the shocks. If a significant fraction survives, and if SN 1987A is typical, supernovae are important cosmological dust producers.

  20. Dust Production and Particle Acceleration in Supernova 1987A Revealed with ALMA

    NASA Astrophysics Data System (ADS)

    Indebetouw, R.; Matsuura, M.; Dwek, E.; Zanardo, G.; Barlow, M. J.; Baes, M.; Bouchet, P.; Burrows, D. N.; Chevalier, R.; Clayton, G. C.; Fransson, C.; Gaensler, B.; Kirshner, R.; Lakićević, M.; Long, K. S.; Lundqvist, P.; Martí-Vidal, I.; Marcaide, J.; McCray, R.; Meixner, M.; Ng, C.-Y.; Park, S.; Sonneborn, G.; Staveley-Smith, L.; Vlahakis, C.; van Loon, J.

    2014-02-01

    Supernova (SN) explosions are crucial engines driving the evolution of galaxies by shock heating gas, increasing the metallicity, creating dust, and accelerating energetic particles. In 2012 we used the Atacama Large Millimeter/Submillimeter Array to observe SN 1987A, one of the best-observed supernovae since the invention of the telescope. We present spatially resolved images at 450 μm, 870 μm, 1.4 mm, and 2.8 mm, an important transition wavelength range. Longer wavelength emission is dominated by synchrotron radiation from shock-accelerated particles, shorter wavelengths by emission from the largest mass of dust measured in a supernova remnant (>0.2 M ⊙). For the first time we show unambiguously that this dust has formed in the inner ejecta (the cold remnants of the exploded star's core). The dust emission is concentrated at the center of the remnant, so the dust has not yet been affected by the shocks. If a significant fraction survives, and if SN 1987A is typical, supernovae are important cosmological dust producers.

  1. DUST PRODUCTION AND PARTICLE ACCELERATION IN SUPERNOVA 1987A REVEALED WITH ALMA

    SciTech Connect

    Indebetouw, R.; Chevalier, R.; Matsuura, M.; Barlow, M. J.; Dwek, E.; Zanardo, G.; Baes, M.; Bouchet, P.; Burrows, D. N.; Clayton, G. C.; Fransson, C.; Lundqvist, P.; Gaensler, B.; Kirshner, R.; Lakićević, M.; Long, K. S.; Meixner, M.; Martí-Vidal, I.; Marcaide, J.; and others

    2014-02-10

    Supernova (SN) explosions are crucial engines driving the evolution of galaxies by shock heating gas, increasing the metallicity, creating dust, and accelerating energetic particles. In 2012 we used the Atacama Large Millimeter/Submillimeter Array to observe SN 1987A, one of the best-observed supernovae since the invention of the telescope. We present spatially resolved images at 450 μm, 870 μm, 1.4 mm, and 2.8 mm, an important transition wavelength range. Longer wavelength emission is dominated by synchrotron radiation from shock-accelerated particles, shorter wavelengths by emission from the largest mass of dust measured in a supernova remnant (>0.2 M {sub ☉}). For the first time we show unambiguously that this dust has formed in the inner ejecta (the cold remnants of the exploded star's core). The dust emission is concentrated at the center of the remnant, so the dust has not yet been affected by the shocks. If a significant fraction survives, and if SN 1987A is typical, supernovae are important cosmological dust producers.

  2. Formation of the three-ring structure around supernova 1987A.

    PubMed

    Tanaka, T; Washimi, H

    2002-04-12

    From a magnetohydrodynamic simulation, we reproduce a three-ring structure in the circumstellar space of the supernova (SN) 1987A observed by the Hubble Space Telescope. When a star develops from a red supergiant (RSG) to a blue supergiant (BSG) just before the SN explosion, a wind-wind interaction occurs between the slow stellar wind from the RSG and the subsequent fast stellar wind from the BSG. This process is simulated numerically under an assumption that the density and velocity distributions around the RSG are anisotropic owing to the existence of toroidal magnetic field and coronal holes. The three rings with observed size and position are reproduced by the magnetic pinch effect and amplification of initial density asymmetry through the dynamical interaction.

  3. A STUBBORNLY LARGE MASS OF COLD DUST IN THE EJECTA OF SUPERNOVA 1987A

    SciTech Connect

    Matsuura, M.; Barlow, M. J.; Dwek, E.; Babler, B.; Baes, M.; Fritz, Jacopo; Meixner, M.; Cernicharo, José; Clayton, Geoff C.; Dunne, L.; Fransson, C.; Lundqvist, P.; Gear, Walter; Gomez, H. L.; Groenewegen, M. A. T.; Indebetouw, R.; Ivison, R. J.; Jerkstrand, A.; Lebouteiller, V.; and others

    2015-02-10

    We present new Herschel photometric and spectroscopic observations of Supernova 1987A, carried out in 2012. Our dedicated photometric measurements provide new 70 μm data and improved imaging quality at 100 and 160 μm compared to previous observations in 2010. Our Herschel spectra show only weak CO line emission, and provide an upper limit for the 63 μm [O I] line flux, eliminating the possibility that line contaminations distort the previously estimated dust mass. The far-infrared spectral energy distribution (SED) is well fitted by thermal emission from cold dust. The newly measured 70 μm flux constrains the dust temperature, limiting it to nearly a single temperature. The far-infrared emission can be fitted by 0.5 ± 0.1 M {sub ☉} of amorphous carbon, about a factor of two larger than the current nucleosynthetic mass prediction for carbon. The observation of SiO molecules at early and late phases suggests that silicates may also have formed and we could fit the SED with a combination of 0.3 M {sub ☉} of amorphous carbon and 0.5 M {sub ☉} of silicates, totalling 0.8 M {sub ☉} of dust. Our analysis thus supports the presence of a large dust reservoir in the ejecta of SN 1987A. The inferred dust mass suggests that supernovae can be an important source of dust in the interstellar medium, from local to high-redshift galaxies.

  4. X-Ray Heating of the Ejecta of Supernova 1987A

    NASA Technical Reports Server (NTRS)

    Sonneborn, George; Larsson, Josefin; Fransson, Claes; Kirshner, Robert; Challis, Peter; McCray, Richard

    2012-01-01

    Analysis of Hubble Space Telescope Band R band images from 1994 to 2009 show that the optical luminosity of SN 1987A has transitioned from being powered by radioactive decay of Ti-44 to energy deposited by X-rays produced as the ejecta interacts with the surrounding material (Larsson et al. 2011, Nature, 474, 484). The B and R band flux from the densest, central parts of the ejecta followed the expected exponential decline until 2001 (about day 5000) when the flux in these bands started increasing, more than doubling by the end of 2009. This increase is the result of heat deposited by X-rays from the shock interaction of the fast-moving outer ejecta with the inner circumstellar ring. In time, the X-rays will penetrate farther into the ejecta, enabling us to analyze the structure and chemistry of the vanished star.

  5. The emergence of X-rays and gamma-rays from supernova 1987A

    NASA Technical Reports Server (NTRS)

    Shull, J. Michael; Xu, Yueming

    1988-01-01

    Attempts to arrive at a unified scenario for the optical, X-ray, and gamma-ray emission of SN 1987A are discussed. Theoretical spectra are in reasonable agreement with recent observations of hard X-rays by the Ginga and Mir satellites, but the early turn-on of X-rays suggests that the mantle and envelope may be 'leaky', perhaps as a result of Rayleigh-Taylor instabilities and clumping. The soft X-ray spectrum should be dominated by a 6.4 keV Fe K-alpha fluorescence line. The reported Ginga detection of 4-10 keV X-ray emission is also discussed.

  6. The theory of gamma-ray emergence in supernova 1987A

    NASA Technical Reports Server (NTRS)

    Pinto, Philip A.; Woosley, S. E.

    1988-01-01

    It was anticipated that the decay of Co-56 to Fe-56 in SN1987A would give rise to detectable gamma-ray emission at 847 and 1238 keV with a peak flux of 0.001 photon/sq cm/s about one year after the explosion. Both these lines were detected in August, with a strength within a factor of two of 0.001 photon/sq cm/s, but about six months earlier than predicted. It is shown here that the early emergence of gamma-rays can be accounted for in a 'mixed' model in which an approximately isotropic process destroys chemical segregation with respect to radial mass coordinate and velocity.

  7. Far-infrared observations of thermal dust emission from supernova 1987A

    NASA Technical Reports Server (NTRS)

    Moseley, S. H.; Dwek, E.; Glaccum, W.; Graham, J. R.; Loewenstein, R. F.

    1989-01-01

    Observations of SN1987A in the spectral range 18-35 microns taken on November 16 and 23, 1988, 632 and 639 days after core collapse, are reported. A strong and rather flat continuum underlies weak fine-structure lines from heavy elements and declines slowly between 24 and 30 microns. The spectral shape indicates thermal emission from an almost featureless dust component, probably graphite, with silicates contributing less than 20 percent of the emitting dust mass. Some of the emission may be an 'echo' of supernova light reflected from a preexisting dust cloud, but a better explanation which can account for the entirety of emission from infrared to gamma wavelengths, is that dust is being formed in the supernova ejecta. This also accounts more naturally for the inferred dust composition.

  8. Mapping High-Velocity H-alpha and Lyman-alpha Emission from Supernova 1987A

    NASA Technical Reports Server (NTRS)

    France, Kevin; McCray, Richard; Fransson, Claes; Larsson, Josefin; Frank, Kari A.; Burrows, David N.; Challis, Peter; Kirshner, Robert P.; Chevalier, Roger A.; Garnavich, Peter; Heng, Kevin; Lawrence, Stephen S.; Lundqvist, Peter; Smith, Nathan; Sonneborn, George

    2015-01-01

    We present new Hubble Space Telescope images of high-velocity H-alpha and Lyman-alpha emission in the outer debris of SN 1987A. The H-alpha images are dominated by emission from hydrogen atoms crossing the reverse shock. For the first time we observe emission from the reverse shock surface well above and below the equatorial ring, suggesting a bipolar or conical structure perpendicular to the ring plane. Using the H-alpha imaging, we measure the mass flux of hydrogen atoms crossing the reverse shock front, in the velocity intervals (-7,500 < V(sub obs) < -2,800 km/s) and (1,000 < V(sub obs) < 7,500 km/s), ?M(sub H) = 1.2 × 10(exp -3) M/ y. We also present the first Lyman-alpha imaging of the whole remnant and new Chandra X-ray observations. Comparing the spatial distribution of the Lyman-alpha and X-ray emission, we observe that the majority of the high-velocity Lyman-alpha emission originates interior to the equatorial ring. The observed Lyman-alpha/H-alpha photon ratio, R(L-alpha/H-alpha) approx. = 17, is significantly higher than the theoretically predicted ratio of approx. = 5 for neutral atoms crossing the reverse shock front. We attribute this excess to Lyman-alpha emission produced by X-ray heating of the outer debris. The spatial orientation of the Lyman-alpha and X-ray emission suggests that X-ray heating of the outer debris is the dominant Lyman-alpha production mechanism in SN 1987A at this phase in its evolution.

  9. Three-dimensional Distribution of Ejecta in Supernova 1987A at 10,000 Days

    NASA Astrophysics Data System (ADS)

    Larsson, J.; Fransson, C.; Spyromilio, J.; Leibundgut, B.; Challis, P.; Chevalier, R. A.; France, K.; Jerkstrand, A.; Kirshner, R. P.; Lundqvist, P.; Matsuura, M.; McCray, R.; Smith, N.; Sollerman, J.; Garnavich, P.; Heng, K.; Lawrence, S.; Mattila, S.; Migotto, K.; Sonneborn, G.; Taddia, F.; Wheeler, J. C.

    2016-12-01

    Due to its proximity, SN 1987A offers a unique opportunity to directly observe the geometry of a stellar explosion as it unfolds. Here we present spectral and imaging observations of SN 1987A obtained ˜10,000 days after the explosion with HST/STIS and VLT/SINFONI at optical and near-infrared wavelengths. These observations allow us to produce the most detailed 3D map of Hα to date, the first 3D maps for [Ca ii] λ λ 7292,7324, [O i] λ λ 6300,6364, and Mg ii λ λ 9218,9244, as well as new maps for [Si i]+[Fe ii] 1.644 μ {{m}} and He i 2.058 μm. A comparison with previous observations shows that the [Si i]+[Fe ii] flux and morphology have not changed significantly during the past ten years, providing evidence that this line is powered by 44Ti. The time evolution of Hα shows that it is predominantly powered by X-rays from the ring, in agreement with previous findings. All lines that have sufficient signal show a similar large-scale 3D structure, with a north-south asymmetry that resembles a broken dipole. This structure correlates with early observations of asymmetries, showing that there is a global asymmetry that extends from the inner core to the outer envelope. On smaller scales, the two brightest lines, Hα and [Si i]+[Fe ii] 1.644 μm, show substructures at the level of ˜200-1000 km s-1and clear differences in their 3D geometries. We discuss these results in the context of explosion models and the properties of dust in the ejecta.

  10. X ray radiation from Supernova 1987A. The results of the Kvant module in 1987-1989

    NASA Technical Reports Server (NTRS)

    Sunyaev, Rashid A.; Kaniovsky, A. S.; Efremov, V. V.; Grebenev, S. A.; Kuznetsov, A. V.; Churasov, E.; Gilfanov, M.; Yamburenko, N.; Englhauser, J.; Doebereiner, S.

    1991-01-01

    The results of two years of SN1987A hard X-ray observations by the HEXE instrument aboard the Kvant module are summarized. By May to June 1989, the hard x-ray flux had declined more than 8.5 times in comparison with the maximum of the x-ray light curve. The upper limit of the ratio of Co-57/Co-56 abundances at the level of ratio of Fe-57/Fe-56 abundances at the Earth is a factor of 1.5.

  11. The search for gamma radiation from supernova 1987A in an experiment aboard the Salut-7/Cosmos-1686 complex

    NASA Astrophysics Data System (ADS)

    Bachilova, R. N.; Bloch, G. M.; Pankov, V. M.; Prohin, V. L.; Rutkovsky, A. I.; Rumin, S. P.

    1988-07-01

    Gamma-quanta flux measurements were carried out during February-October 1987 in a search for radiation from SN 1987A. The time dependence of the mean monthly gamma-quanta flux measured with the Nega telescope at an altitude of 500 km in the equatorial region is analyzed. The upper limit of the gamma-quanta flux is determined to be 1.5 x 10 to the -6th/sq cm s keV on the 3-sigma level for the 1.5-4.4 MeV energy interval.

  12. 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.

  13. X-Ray Illumination of the Ejecta of Supernova 1987A

    NASA Technical Reports Server (NTRS)

    Larsson, J.; Fransson, C.; Oestlin, G.; Groeningsson, P.; Jerkstrand, A.; Kozma, C.; Sollerman, J.; Challis, P.; Kirshner, R. P.; Chevalier, R. A.; Heng, K.; McCray, R.; Suntzeff, N. B.; Bouchet, P.; Crotts, A.; Danziger, J.; Dwek, E.; France, K.; Garnavich, P. M.; Lawrence, S. S.; Leibundgut, B.; Lundqvist, P.; Panagia, N.; Pun, C. S. J.; Sonneborn, G.

    2011-01-01

    When a massive star explodes as a supernova, substantial amounts of radioactive elements-primarily Ni-56, Ni-57 and Ti-44 are produced. After the initial from shock heating, the light emitted by the supernova is due to the decay of these elements. However, after decades, the energy powering a supernova remnant comes from the shock interaction between the ejecta and the surrounding medium. The transition to this phase has hitherto not been observed: supernovae occur too infrequently in the Milky Way to provide a young example, and extragalactic supernovae are generally too faint and too small. Here we report observations that show this transition in the supernova SN 1987A in the Large Magellan Cloud. From 1994 to 200l, the ejecta faded owing to radioactive decay of Ti-44 as predicted. Then the flux started to increase, more than doubling by the end of 2009. We show that this increase is the result of heat deposited by X-rays produced as the ejecta interacts with the surrounding material. In time, the X-rays will penetrate farther into the ejects, enabling us to analyse the structure and chemistry of the vanished star.

  14. X-ray illumination of the ejecta of supernova 1987A.

    PubMed

    Larsson, J; Fransson, C; Ostlin, G; Gröningsson, P; Jerkstrand, A; Kozma, C; Sollerman, J; Challis, P; Kirshner, R P; Chevalier, R A; Heng, K; McCray, R; Suntzeff, N B; Bouchet, P; Crotts, A; Danziger, J; Dwek, E; France, K; Garnavich, P M; Lawrence, S S; Leibundgut, B; Lundqvist, P; Panagia, N; Pun, C S J; Smith, N; Sonneborn, G; Wang, L; Wheeler, J C

    2011-06-08

    When a massive star explodes as a supernova, substantial amounts of radioactive elements--primarily (56)Ni, (57)Ni and (44)Ti--are produced. After the initial flash of light from shock heating, the fading light emitted by the supernova is due to the decay of these elements. However, after decades, the energy powering a supernova remnant comes from the shock interaction between the ejecta and the surrounding medium. The transition to this phase has hitherto not been observed: supernovae occur too infrequently in the Milky Way to provide a young example, and extragalactic supernovae are generally too faint and too small. Here we report observations that show this transition in the supernova SN 1987A in the Large Magellanic Cloud. From 1994 to 2001, the ejecta faded owing to radioactive decay of (44)Ti as predicted. Then the flux started to increase, more than doubling by the end of 2009. We show that this increase is the result of heat deposited by X-rays produced as the ejecta interacts with the surrounding material. In time, the X-rays will penetrate farther into the ejecta, enabling us to analyse the structure and chemistry of the vanished star.

  15. Mystery spot in supernova 1987A - Reflection or fluorescence by an interstellar cloud?

    NASA Technical Reports Server (NTRS)

    Felten, James E.; Dwek, Eli; Viegas-Aldrovandi, Sueli M.

    1989-01-01

    This paper explores fluorescence and reflection models of the companion to SN 1987A obseved by speckle interferometry, recalling a 1901 precedent. The apparent small angular size of the companion is a severe constraint. A fluorescence model cannot reach the observed brightness unless the ultraviolet burst from the supernova contained as many as 2 x 10 to the 58th ionizing photons. This is about 25 times stronger than generous current models. Even then, the expected line ratios and widths do not fit the observations. The absence of narrow H-alpha and H-beta lines in the supernova spectrum, the ratio of fluxes of the companion in H-alpha and forbidden N II line filters, the invisibility of the companion at 4861 (H-beta), and its detection at 5330 fail to agree with theory. A dust-reflection model is more promising, and the color can be reddened by the evaporation of small grains, but the model still falls more than about 1 mag short in brightness. Furthermore, a dust reflection should have increased in relative brightness in May-June 1987, rather than disappearing as the mystery spot did. If all the observations are correct, neither model is likely to work.

  16. Confirmation of Dust Condensation in the Ejecta of Supernova 1987a

    NASA Astrophysics Data System (ADS)

    Gehrz, R. D.; Ney, E. P.

    1990-06-01

    Shortly after its outburst, we suggested that supernova 1987a might condense a dust shell of substantial visual optical thickness as many classical novae do and predicted that dust might form within a year after the explosion. A critical examination of recent optical and infrared observations reported by others confirms that dust grains had begun to grow at a temperature of 1000 K after 300 days and that the dust shell had become optically thick by day 600. After day 600, the infrared luminosity closely followed the intrinsic luminosity expected for thermalized 56Co γ rays, demonstrating that the luminosity is powered by radioactivity and that the dust is outside the radioactivity zone. The infrared luminosity sets an upper limit to the soft intrinsic bolometric luminosity of a pulsar central engine. This upper limit for the pulsar in supernova 1987a is the same luminosity as the Crab pulsar has today 936 years after its formation. It is unlikely that the rotation rate for a pulsar in supernova 1987a can be much higher than ≈ 30 revolutions per sec. The relatively long time required for the shell to grow to maximum optical depth as compared with the dust in nova shells may be related to the relatively low outflow velocity of the condensible ejecta.

  17. Confirmation of dust condensation in the ejecta of supernova 1987a.

    PubMed Central

    Gehrz, R D; Ney, E P

    1990-01-01

    Shortly after its outburst, we suggested that supernova 1987a might condense a dust shell of substantial visual optical thickness as many classical novae do and predicted that dust might form within a year after the explosion. A critical examination of recent optical and infrared observations reported by others confirms that dust grains had begun to grow at a temperature of 1000 K after 300 days and that the dust shell had become optically thick by day 600. After day 600, the infrared luminosity closely followed the intrinsic luminosity expected for thermalized 56Co gamma rays, demonstrating that the luminosity is powered by radioactivity and that the dust is outside the radioactivity zone. The infrared luminosity sets an upper limit to the soft intrinsic bolometric luminosity of a pulsar central engine. This upper limit for the pulsar in supernova 1987a is the same luminosity as the Crab pulsar has today 936 years after its formation. It is unlikely that the rotation rate for a pulsar in supernova 1987a can be much higher than approximately 30 revolutions per sec. The relatively long time required for the shell to grow to maximum optical depth as compared with the dust in nova shells may be related to the relatively low outflow velocity of the condensible ejecta. PMID:11607082

  18. A search for gamma-ray lines from the decay of Fe-59 in Supernova 1987A

    NASA Technical Reports Server (NTRS)

    Harris, M. J.; Leising, M. D.

    1994-01-01

    We have searched spectra of Supernova (SN) 1987A, accumulated during several 35-day intervals after the explosion by the Solar Maximum Mission (SMM) Gamma Ray Spectrometer (GRS), for gamma-ray lines at 1.099 and 1.292 MeV from the decay of Fe-59 which may have been produced in the progenitor's helium shell. We find no evidence for these lines, down to 3-sigma upper limits approximately = 7 x 10(exp -4) gamma/sq cm/s for the 1.099 MeV line, or approximately = 4.5 x 10(exp -4) gamma/sq cm/s for the 1.292 MeV line, in any 35-day interval. We derive a conservative 3-sigma upper limit on the mass fraction of Fe-59 in the helium shell of 2.9 x 10(exp -3).

  19. Low radio frequency observations and spectral modelling of the remnant of Supernova 1987A

    NASA Astrophysics Data System (ADS)

    Callingham, J. R.; Gaensler, B. M.; Zanardo, G.; Staveley-Smith, L.; Hancock, P. J.; Hurley-Walker, N.; Bell, M. E.; Dwarakanath, K. S.; Franzen, T. M. O.; Hindson, L.; Johnston-Hollitt, M.; Kapińska, A.; For, B.-Q.; Lenc, E.; McKinley, B.; Morgan, J.; Offringa, A. R.; Procopio, P.; Wayth, R. B.; Wu, C.; Zheng, Q.

    2016-10-01

    We present Murchison Widefield Array observations of the supernova remnant (SNR) 1987A between 72 and 230 MHz, representing the lowest frequency observations of the source to date. This large lever arm in frequency space constrains the properties of the circumstellar medium created by the progenitor of SNR 1987A when it was in its red supergiant phase. As of late 2013, the radio spectrum of SNR 1987A between 72 MHz and 8.64 GHz does not show any deviation from a non-thermal power law with a spectral index of -0.74 ± 0.02. This spectral index is consistent with that derived at higher frequencies, beneath 100 GHz, and with a shock in its adiabatic phase. A spectral turnover due to free-free absorption by the circumstellar medium has to occur below 72 MHz, which places upper limits on the optical depth of ≤0.1 at a reference frequency of 72 MHz, emission measure of ≲13 000 cm-6 pc, and an electron density of ≲110 cm-3. This upper limit on the electron density is consistent with the detection of prompt radio emission and models of the X-ray emission from the supernova. The electron density upper limit implies that some hydrodynamic simulations derived a red supergiant mass-loss rate that is too high, or a wind velocity that is too low. The mass-loss rate of ˜5 × 10-6 M⊙ yr-1 and wind velocity of 10 km s-1 obtained from optical observations are consistent with our upper limits, predicting a current turnover frequency due to free-free absorption between 5 and 60 MHz.

  20. Hydrodynamic study of Supernova 1987A: The phase of a wave of cooling and recombination

    NASA Technical Reports Server (NTRS)

    Utrobin, V. P.

    1991-01-01

    The dependence of the bolometric light curve and of the effective temperature on the density distribution in a progenitor, its chemical composition, mass, radius, and explosion energy is studied. It is shown that, just before the supernova 1987 A outburst, the outside layers of the blue supergiant Sk-69.202 deg had a density distribution similar to that of the polytropic model with an index of n equals 3, a chemical composition with a mass fraction of hydrogen of the order of 0.1, and a relative helium abundance of about 0.9.

  1. STIS DISCOVERS HIGH-SPEED GAS FROM COLLISION AROUND SUPERNOVA 1987A

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This image from the Hubble's Space Telescope Imaging Spectrograph (STIS) shows a new and unprecedented look at the light-year wide ring of glowing gas around supernova 1987A, the nearest stellar explosion in 400 years, which occurred in February 1987. The STIS long-slit spectrograph viewed the entire ring system, dissecting its light and producing a detailed image of the ring in each of its component colors. This image shows the ring in the optical light of hydrogen (center) flanked by images in nitrogen emission. The arrow points to a streak produced by gas rushing toward us at 200 miles per sec. This is the same place where the bright knot is seen in Hubble's WFPC-2 images. This is the first hint that the collision between the high-speed supernova debris and gases in the glowing ring has begun. Supernova 1987A is located 167,000 light years away from Earth in the Large Magellanic Cloud. Credit: George Sonneborn and Jason Pun (NASA

  2. Correlation mass method for analysis of neutrinos from supernova 1987A

    NASA Technical Reports Server (NTRS)

    Chiu, Hong-Yee; Chan, Kwing L.; Kondo, Yoji

    1988-01-01

    Application of a time-energy correlation method to the Kamiokande II (KII) observations of neutrinos apparently emitted from supernova 1987A has yielded a neutrino rest mass of 3.6 eV. A Monte Carlo analysis shows a reconfirming probabilty distribution for the neutrino rest mass peaked at 2.8, and dropping to 50 percent of the peak at 1.4 and 4.8 eV. Although the KII data indicate a very short time scale of emission, over an extended period on the order of 10 sec, both data from the Irvine-Michigan-Brookhaven experiment and the KII data show a tendency for the more energetic neutrinos to be emitted earlier at the source, suggesting the possibility of cooling.

  3. An optical and near infrared search for a pulsar in Supernova 1987A

    SciTech Connect

    Sasseen, T.P.

    1990-12-01

    We describe a search for an optical pulsar in the remnant of Supernova 1987A. We have performed over one hundred separate observations of the supernova, covering wavelengths from 3500 angstroms to 1.8 microns, with sensitivity to pulsations as faint as magnitude 22.7. As of September 26, 1990, we have not seen evidence for pulsations due to a pulsar in the supernova. We discuss the implications of this result on predictions of pulsar optical luminosity. We have constructed for the search two photodiode detectors and a data system. We describe their design, calibration and performance. These detectors have allowed us to increase our sensitivity as much as a factor of 5 over standard photomultiplier tubes, and extend this search to near infrared wavelengths. 59 refs., 10 figs., 1 tab.

  4. Coincidences among the data recorded by the Baksan, KAMIOKA and Mont Blanc underground neutrino detectors, and by the Maryland and Rome gravitational-wave detectors during Supernova 1987 A

    NASA Astrophysics Data System (ADS)

    Aglietta, M.; Castellina, A.; Fulgione, W.; Trinchero, G.; Vernetto, S.

    1991-04-01

    Data recorded with neutrino detectors at Mont Blanc, Kamioka, and Baksan and with gravitational wave detectors in Maryland and Rome are analyzed. An attempt is made to find correlations associated with SN 1987 A. The time when an excess of coincidences is found is centered at a 5-pulse burst detected at Mont Blanc.

  5. The confirmation of the 2.1 ms candidate for PSR1987A and the 1000-hour Arecibo Piggyback ms Pulsar Survey. Final report

    SciTech Connect

    Middleditch, J.; Kulkarni, S.

    1995-06-01

    The authors objectives included (1) The confirmation of the 2.1 ms candidate for the pulsar (PSR1987A) in Supernova 1987A (SN1987A), and, provided the candidate is real (and if it is real, the authors have successfully tracked its frequency for two years), (2) to determine the nature of its spindown, including whether it is a result of gravitational radiation (GR), inertia transfer associated with differential rotation, changes in the moment of inertia, or the affects of a wide binary system. The authors have decent results to support the supposition that the spindown of this candidate for PSR1987A is indeed due almost entirely to gravitational radiation. The observations with the University of Tasmania 1-m telescope were successful in detecting the 2.1 ms candidate pulsar on at least three occasions. They can conclude that there is now little doubt that SN1987A was the result of a merger of two giant stars which resulted in: (1) The ejection of the three rings during a common-envelope/Roche lobe overflow phase which may have lasted only 300 to 1,000 years some 30,000 years ago, (2) The extreme mixing of the elements during the spiraling in phase of the two {approximately}0.7 solar mass white dwarf cores, (3) The blue supergiant nature of the progenitor star, Sk-69 202, and (4) the formation of a weak-field ms pulsar spinning every 2.1 ms. The importance of this finding is nearly inestimable. The authors now know that neutron stars can sustain or grow oblatenesses of 5 parts in ten million some 5-7 years after their explosive birth, and that pulsars born in such a way can outshine all other compact solar mass type objects by an order of magnitude in nearly pure gravitational radiation. They know now that most weak field ms, pulsars are born in such core mergers, which explains their drastic overabundance in the globular clusters relative to the low mass X-ray binaries, which were previously, and erroneously thought of as their progenitors.

  6. Limits on neutrino radiative decay from SN1987A

    NASA Technical Reports Server (NTRS)

    Jaffe, Andrew H.; Fenimore, ED; Turner, Michael S.

    1993-01-01

    We calculate limits on the properties of neutrinos using data from gamma ray detectors on the Pioneer Venus Orbiter and Solar Max Mission satellites. A massive neutrino decaying in flight from the supernova would produce gamma rays detectable by these instruments. The lack of such a signal allows us to constrain the mass, radiative lifetime, and branching ratio to photons of a massive neutrino species produced in the supernova.

  7. The Wild, Hidden Cousin of SN 1987A

    NASA Astrophysics Data System (ADS)

    2008-09-01

    First Optically Active Magnetar-Candidate Discovered Astronomers have discovered a most bizarre celestial object that emitted 40 visible-light flashes before disappearing again. It is most likely to be a missing link in the family of neutron stars, the first case of an object with an amazingly powerful magnetic field that showed some brief, strong visible-light activity. Hibernating Stellar Magnet ESO PR Photo 31/08 The Hibernating Stellar Magnet This weird object initially misled its discoverers as it showed up as a gamma-ray burst, suggesting the death of a star in the distant Universe. But soon afterwards, it exhibited some unique behaviour that indicates its origin is much closer to us. After the initial gamma-ray pulse, there was a three-day period of activity during which 40 visible-light flares were observed, followed by a brief near-infrared flaring episode 11 days later, which was recorded by ESO's Very Large Telescope. Then the source became dormant again. "We are dealing with an object that has been hibernating for decades before entering a brief period of activity", explains Alberto J. Castro-Tirado, lead author of a paper in this week's issue of Nature. The most likely candidate for this mystery object is a 'magnetar' located in our own Milky Way galaxy, about 15 000 light-years away towards the constellation of Vulpecula, the Fox. Magnetars are young neutron stars with an ultra-strong magnetic field a billion billion times stronger than that of the Earth. "A magnetar would wipe the information from all credit cards on Earth from a distance halfway to the Moon," says co-author Antonio de Ugarte Postigo. "Magnetars remain quiescent for decades. It is likely that there is a considerable population in the Milky Way, although only about a dozen have been identified." Some scientists have noted that magnetars should be evolving towards a pleasant retirement as their magnetic fields decay, but no suitable source had been identified up to now as evidence for this evolutionary scheme. The newly discovered object, known as SWIFT J195509+261406 and showing up initially as a gamma-ray burst (GRB 070610), is the first candidate. The magnetar hypothesis for this object is reinforced by another analysis, based on another set of data, appearing in the same issue of Nature.

  8. Possible explanation of the correlations between events recorded by underground detectors during the Supernova 1987A explosion

    SciTech Connect

    Alexeyev, E. N.

    2010-02-15

    A possible explanation of the time correlations between the data from underground detectors (Baksan telescope, LSD, IMB, Kamiokande II) and from the Rome and Maryland gravitational-wave antennas obtained during the Supernova 1987A explosion is proposed. It is shown that the synchronization of the events recorded by various underground facilities could be produced by gravitational radiation from the Supernova.

  9. The Death of a Star: Supernova 1987a. NASA Educational Briefs for the Upper Elementary-Level Classroom.

    ERIC Educational Resources Information Center

    National Aeronautics and Space Administration, Washington, DC.

    This material discusses supernova, the violent death of a massive star, at a level appropriate for upper elementary students. Background information on Supernova 1987a is presented. Observation techniques using visible light, ultraviolet waves, radio waves, neutrinos, X-rays, and gamma-rays are described. A vocabulary list, 11 questions, and 6…

  10. Spectral line profiles of nickel and argon in supernova 1987A - Expansion velocity and electron scattering effects

    NASA Technical Reports Server (NTRS)

    Witteborn, F. C.; Bregman, J. D.; Wooden, D. H.; Pinto, P. A.; Rank, D. M.

    1989-01-01

    Spectra of SN 1987A showing the Ni II 6.634-micron and Ar II 6.983-micron fine-structure lines were obtained from the Kuiper Airborne Observatory in April 1988. The signal-to-noise ratio of 100 near the peaks and resolving power of 200 are sufficient to show the average velocity of expansion from the core of about 1400 km/s and to indicate the range of velocities. An asymmetry in the profiles of both lines and a redshift of the line centroids of about 440 km/s above the 280-km/s recessional velocity of the LMC can be explained in terms of scattering of the photons by electrons in the expanding hydrogen envelope of the supernova. A mass of 0.0030 solar masses of Ni II can be deduced from the line strength of the Ni II line and a mass of 0.0009 solar masses of Ar II from the Ar II line strength.

  11. On the Possibility of Dust Condensation in the Ejecta of Supernova 1987a

    NASA Astrophysics Data System (ADS)

    Gehrz, R. D.; Ney, E. P.

    1987-10-01

    We suggest that supernova 1987a may condense dust of substantial visual optical thickness as do many novae. The dust will act as a calorimeter of the photon luminosity of any central engine that is dominant at the time of dust formation. Observations of novae suggest that dust formation may occur when the expanding ejecta reach a temperature of 1000 K. The early luminosity of the supernova may be dominated by radioactivity that is unrelated to the central engine that determines the energy balance for the long-term development of the supernova. We discuss the possibility that a constant luminosity central power source such as a pulsar dominates the luminosity of the supernova ejecta by the time that dust can condense and argue that, if a shell mass of more than a few tenths of one solar mass was ejected, emission from dust may be observable in the thermal infrared spectral region. Maximum dust optical depth should occur by late 1987 or early 1988. If the dust becomes optically thick, the visual light from the supernova may drop precipitously. The characteristics of an optically thick dust shell as a calorimeter of the luminosity of the central engine are discussed and are related to previous observations of dust formation in type II supernovae. It is suggested that dust of several chemical compositions may form at different epochs.

  12. On the possibility of dust condensation in the ejecta of supernova 1987a

    PubMed Central

    Gehrz, R. D.; Ney, E. P.

    1987-01-01

    We suggest that supernova 1987a may condense dust of substantial visual optical thickness as do many novae. The dust will act as a calorimeter of the photon luminosity of any central engine that is dominant at the time of dust formation. Observations of novae suggest that dust formation may occur when the expanding ejecta reach a temperature of 1000 K. The early luminosity of the supernova may be dominated by radioactivity that is unrelated to the central engine that determines the energy balance for the long-term development of the supernova. We discuss the possibility that a constant luminosity central power source such as a pulsar dominates the luminosity of the supernova ejecta by the time that dust can condense and argue that, if a shell mass of more than a few tenths of one solar mass was ejected, emission from dust may be observable in the thermal infrared spectral region. Maximum dust optical depth should occur by late 1987 or early 1988. If the dust becomes optically thick, the visual light from the supernova may drop precipitously. The characteristics of an optically thick dust shell as a calorimeter of the luminosity of the central engine are discussed and are related to previous observations of dust formation in type II supernovae. It is suggested that dust of several chemical compositions may form at different epochs. PMID:16593876

  13. EVOLUTION OF THE RADIO REMNANT OF SUPERNOVA 1987A: MORPHOLOGICAL CHANGES FROM DAY 7000

    SciTech Connect

    Ng, C.-Y.; Zanardo, G.; Potter, T. M.; Staveley-Smith, L.; Gaensler, B. M.; Manchester, R. N.; Tzioumis, A. K.

    2013-11-10

    We present radio imaging observations of supernova remnant 1987A at 9 GHz, taken with the Australia Telescope Compact Array over 21 years from 1992 to 2013. By employing a Fourier modeling technique to fit the visibility data, we show that the remnant structure has evolved significantly since day 7000 (mid-2006): the emission latitude has gradually decreased such that the overall geometry has become more similar to a ring structure. Around the same time, we find a decreasing trend in the east-west asymmetry of the surface emissivity. These results could reflect the increasing interaction of the forward shock with material around the circumstellar ring, and the relative weakening of the interaction with the lower-density material at higher latitudes. The morphological evolution caused an apparent break in the remnant expansion measured with a torus model, from a velocity of 4600{sup +150}{sub -}200 km s{sup –1} between day 4000 and 7000 to 2400{sup +100}{sub -200} km s{sup –1} after day 7000. However, we emphasize that there is no conclusive evidence for a physical slowing of the shock at any given latitude in the expanding remnant, and that a change of radio morphology alone appears to dominate the evolution. This is supported by our ring-only fits which show a constant expansion of 3890 ± 50 km s{sup –1} without deceleration between days 4000 and 9000. We suggest that once the emission latitude no longer decreases, the expansion velocity obtained from the torus model should return to the same value as that measured with the ring model.

  14. The late behavior of supernova 1987A. I - The light curve. II - Gamma-ray transparency of the ejecta

    NASA Technical Reports Server (NTRS)

    Arnett, W. David; Fu, Albert

    1989-01-01

    Observations of the late (t = 20-1500 days) bolometric light curve and the gamma-lines and X-rays from supernova 1987A are compared to theoretical models. It is found that 0.073 + or - 0.015 solar masses of freshly synthesized Ni-56 must be present to fit the bolometric light curve. The results place limits on the luminosity and presumed period of the newly formed pulsar/neutron star. In the second half of the paper, the problem of computing the luminosities in gamma-ray lines and in X-rays from supernova 1987A is addressed. High-energy observations suggest the development of large-scale clumping and bubbling of radioactive material in the ejecta. A model is proposed with a hydrogen envelope mass of about 7 solar masses, homologous scale expansion velocities of about 3000 km/s, and an approximately uniform mass distribution.

  15. Infrared and X-Ray Evidence for Circumstellar Grain Destruction by the Blast Wave of Supernova 1987A

    NASA Technical Reports Server (NTRS)

    Dwek, Eliahu; Arendt, Richard G.; Bouchet, Patrice; Burrows, David N.; Challis, Peter; Danziger, John; DeBuizer James M.; Gehrz, Robert D.; Kirshner, Robert P.; McCray, Richard; Park, Sangwok; Polomski, Elisha; Woodward, Charles

    2007-01-01

    Multiwavelength observations of supernova remnant (SNR) 1987A show that its morphology and luminosity are rapidly changing at X-ray, optical, infrared, and radio wavelengths as the blast wave from the explosion expands into the circumstellar equatorial ring, produced by mass loss from the progenitor star. The observed infrared (IR) radiation arises from the interaction of dust grains that formed in mass outflow with the soft X-ray emitting plasma component of the shocked gas. Spitzer IRS spectra at 5 - 30 microns taken on day 6190 since the explosion show that the emission arises from approx. 1.1 x 10(exp -6) solar mass of silicate grains radiating at a temperature of approx. 180+/-(15-20) K. Subsequent observations on day 7137 show that the IR flux had increased by a factor of 2 while maintaining an almost identical spectral shape. The observed IR-to-X-ray flux ratio (IRX) is consistent with that of a dusty plasma with standard LMC dust abundances. This flux ratio has decreased by a factor of approx. 2 between days 6190 and 7137, providing the first direct observation of the ongoing destruction of dust in an expanding SN blast wave on dynamic time scales. Detailed models consistent with the observed dust temperature, the ionization fluence of the soft X-ray emission component, and the evolution of IRX suggest that the radiating si1icate grains are immersed in a 3.5 x 10(exp 6) K plasma with a density of (0.3 - 1) x 10(exp 4)/cu cm, and have a size distribution that is confined to a narrow range of radii between 0.02 and 0.2 microns. Smaller grains may have been evaporated by the initial UV flash from the supernova.

  16. New Hubble Space Telescope Observations of High-Velocity Ly(alpha) and H(alpha) in SNR 1987A

    NASA Technical Reports Server (NTRS)

    Michael, Eli; McCray, Richard; Pun, C. S. J.; Borkowski, Kazimierz; Garnavich, Peter; Challis, Peter; Kirshner, Robert P.; Chevalier, Roger; Filippenko, Alexei V.; Fransson, Claes; Panagia, Nino; Phillips, Mark; Schmidt, Brian; Suntzef, Nicholas

    1998-01-01

    We describe and model high-velocity (approximately 15,000 km S(exp -1)) Ly Alpha and H Alpha emission from the supernova remnant SNR 1987A seen in 1997 September and October with the Space Telescope Imaging Spectrograph. Part of this emission comes from a reverse shock located at approximately 75% of the radius of the inner boundary ofthe innercircumstellar ring and confined within + or - 30 degrees of the equatorial plane. Departure from axisymmetry in the Ly Alpha and H Alpha emission correlates with that seen in nonthermal radio emission and reveals an asymmetry in the circumstellar gas distribution. We also see diffuse high-velocity Ly-Alpha emission from supernova debris inside the reverse shock that may be due to excitation by nonthermal particles accelerated by the shock.

  17. Hard-X-ray emission lines from the decay of 44Ti in the remnant of supernova 1987A.

    PubMed

    Grebenev, S A; Lutovinov, A A; Tsygankov, S S; Winkler, C

    2012-10-18

    It is assumed that the radioactive decay of (44)Ti powers the infrared, optical and ultraviolet emission of supernova remnants after the complete decay of (56)Co and (57)Co (the isotopes that dominated the energy balance during the first three to four years after the explosion) until the beginning of active interaction of the ejecta with the surrounding matter. Simulations show that the initial mass of (44)Ti synthesized in core-collapse supernovae is (0.02-2.5) × 10(-4) solar masses (M circled dot). Hard X-rays and γ-rays from the decay of this (44)Ti have been unambiguously observed from Cassiopeia A only, leading to the suggestion that values of the initial mass of (44)Ti near the upper bound of the predictions occur only in exceptional cases. For the remnant of supernova 1987A, an upper limit to the initial mass of (44)Ti of <10(-3) M circled dot has been obtained from direct X-ray observations, and an estimate of (1-2) × 10(-4) M circled dot has been made from infrared light curves and ultraviolet spectra by complex and model-dependent computations. Here we report observations of hard X-rays from the remnant of supernova 1987A in the narrow band containing two direct-escape lines of (44)Ti at 67.9 and 78.4 keV. The measured line fluxes imply that this decay provided sufficient energy to power the remnant at late times. We estimate that the initial mass of (44)Ti was (3.1 ± 0.8) × 10(-4), which is near the upper bound of theoretical predictions.

  18. REVIEWS OF TOPICAL PROBLEMS Rotational explosion mechanism for collapsing supernovae and the two-stage neutrino signal from supernova 1987A in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Imshennik, Vladimir S.

    2011-02-01

    The two-stage (double) signal produced by the outburst of the close supernova (SN) in the Large Magellanic Cloud, which started on and involved two neutrino signals during the night of 23 February 1987 UT, is theoretically interpreted in terms of a scenario of rotationally exploding collapsing SNs, to whose class the outburst undoubtedly belongs. This scenario consists of a set of hydrodynamic and kinetic models in which key results are obtained by numerically solving non-one-dimensional and nonstationary problems. Of vital importance in this context is the inclusion of rotation effects, their role being particularly significant precisely in terms of the question of the transformation of the original collapse of the presupernova iron core to the explosion of the SN shell, with an energy release on a familiar scale of 1051 erg. The collapse in itself leads to the birth of neutron stars (black holes) emitting neutrino and gravitational radiation signals of gigantic intensity, whose total energy significantly (by a factor of hundreds) exceeds the above-cited SN burst energy. The proposed rotational scenario is described briefly by artificially dividing it into three (or four) characteristic stages. This division is dictated by the physical meaning of the chain of events a rotating iron core of a sufficiently massive (more than 10M) star triggers when it collapses. An attempt is made to quantitatively describe the properties of the associated neutrino and gravitational radiations. The review highlights the interpretation of the two-stage neutrino signal from SN 1987A, a problem which, given the present status of theoretical astrophysics, cannot, in the author's view, be solved without including rotation effects.

  19. Supernova 1987A!

    PubMed

    Woosley, S E; Phillips, M M

    1988-05-06

    Light from the brightest supernova in almost 400 years arrived at Earth on 23 February 1987. Although located 160,000 light years away in a satellite galaxy of our own known as the Large Magellanic Cloud, this supernova's relative proximity compared to all others that have been observed in modern times has allowed observations, which were never possible before, to be made from space, from detectors on the ground and carried by balloons and airplanes, and from neutrino detectors deep underground. What emerges is a greater understanding of one of the most violent events in the universe, the death of a massive star. For the most part, theoretical expectations have been borne out, but some major surprises have made the event all the more fascinating.

  20. Mid- and Far-IR Spectroscopy of the Nebular Phase of SN1987A

    NASA Technical Reports Server (NTRS)

    Wooden, Diane; Witteborn, Fred C. (Technical Monitor)

    1997-01-01

    The mid- and far-infrared (IR) spectra of the nebular phase of SM 987A spans 250 days through more than 1000 days after the event. Analysis of the spectra, largely obtained from the Kuiper Airborne Observatory, leads to a rich picture of the structure of the supernebula. The evidence for dust grain formation. In the nebula after about 580 days will be reviewed. The dust continuum emission spectrum was gray and dust appears to have condensed in optically thick 'clumps' throughout a significant fraction of the nebula. Additional information is contained in the original extended abstract.

  1. Zooming in on Supernova 1987A

    NASA Video Gallery

    The video begins with a nighttime view of the Small and Large Magellanic clouds, satellite galaxies of our Milky Way. It then zooms into a rich star-birth region in the Large Magellanic Cloud. Nest...

  2. Supernova 1987A: 18 Months later

    SciTech Connect

    Schramm, D.N.

    1989-01-01

    An overview of the significance for physics of the closest visual supernova in almost 400 years is presented. The supernova occurred in the Large Magellanic Cloud (LMC), /approximately/50 kpc away. The supernova star was a massive star of /approximately/15--20M. Observations now show that it was once a red-giant but lost its outer envelope. The lower than standard luminosity and higher observed velocities are a natural consequence of the pre-supernova star being a blue rather than a red (supergiant). Of particular importance to physicists is the detection of neutrinos from the event by detectors in the United States and Japan. Not only did this establish extra-solar system neutrino astronomy, but it also constrained the properties of neutrino. It is shown that the well established Kamioka-IMB neutrino burst experimentally implies an event with about 2--4 /times/ 10/sup 53/ergs emitted in neutrinos and a temperature, T/sub /bar /nu/e//, of between 4 and 4.5 MeV. This event is in excellent agreement with what one would expect from the gravitational core collapse of a massive star. A neutrino detection, such as that reported earlier in Mt. Blanc, would require more than the rest mass energy of a neutron star to be converted to neutrinos, if it were to have its origin in the LMC. Thus it is probably unrelated to the supernova. The anticipated frequency of collapse events in our Galaxy, will also be discussed with a rate as high as 1/10 year shown to be not unreasonable. 61 refs.

  3. Supernova 1987A: 18 months later

    NASA Technical Reports Server (NTRS)

    Schramm, David N.

    1989-01-01

    An overview of the significance for physics of the closest visual supernova in almost 400 years is presented. The supernova occurred in the Large Magellanic Cloud (LMC), approx. 50 kpc away. The supernova star was a massive star of approx. 15 to 20 solar mass. Observations now show that it was once a red giant but lost its outer envelope. The lower than standard luminosity and higher observed velocities are a natural consequence of the pre-supernova star being a blue rather than a red (supergiant). Of particular importance to physicsts is the detection of neutrinos from the event by detectors in the United States and Japan. Not only did this establish extra-solar system neutrino astronomy, but it also constrained the properties of neutrino. It is shown that the well established Kamioka-IMB neutrino burst experimentally implies an event with about 2 to 4 x 10 to the 53rd power ergs emitted in neutrinos and a temperature, T sub nu e, of between 4 and 4.5 MeV. This event is in excellent agreement with what one would expect from the gravitational core collapse of a massive star. The anticipated frequency of collapse events in our Galaxy is discussed.

  4. Analysis of the data recorded by the Mont Blanc neutrino detector andby the Maryland and Rome gravitational wave detectors during SN1987A.

    NASA Astrophysics Data System (ADS)

    Aglietta, M.; Amaldi, E.; Badino, G.; Bassan, M.; Bologna, G.; Bonifazi, P.; Castagnoli, C.; Castellano, M. G.; Castellina, A.; Coccia, E.; Cosmelli, C.; Dadykin, V. L.; Frasca, S.; Fulgione, W.; Galeotti, P.; Gretz, D.; Kalchukov, F. F.; Malguin, A. S.; Modena, I.; Pallottino, G. V.; Pizzella, G.; Rapagnani, P.; Ricci, F.; Ryassny, V. G.; Ryazhskaya, O. G.; Saavedra, O.; Trinchero, G.; Vannaroni, G.; Vernetto, S.; Weber, J.; Wilmot, G.; Zatsepin, G. T.

    The data recorded by the gravitational wave and neutrino detectors have been analyzed over a period of 18h that includes the Mont Blanc 5ν burst occurrence time. A correlation is found during a period of about two hours roughly centered on the 5ν burst, independently between Maryland and Mont Blanc and Rome and Mont Blanc. The probability that these two correlations be due to chance is of the order of 3×10-6.

  5. Correlations between muons and low energy pulses at LSD of the Mont Blanc laboratory near the time of SN 1987A explosion.

    NASA Astrophysics Data System (ADS)

    Dadykin, V. L.; Khalchukov, F. F.; Korchagin, P. V.; Korolkova, E. V.; Kudryavtsev, V. A.; Mal'Gin, A. S.; Ryasny, V. G.; Ryazhskaya, O. G.; Yakushev, V. F.; Zatsepin, G. T.; Aglietta, M.; Badino, G.; Bologna, G.; Castagnoli, C.; Castellina, A.; Fulgione, W.; Galeotti, P.; Saavedra, O.; Trinchero, G.; Vernetto, S.

    The authors have analysed the data of LSD from February 10, 1987, to March 7, 1987, in order to search for autocorrelations between all pulses detected by LSD with energy higher than 5 MeV like those that occurred at ≡3:00 UT on February 23, 1987, between the pulses detected by three neutrino telescopes and two gravitational wave antennae. The authors have found 9 pairs of correlated pulses (muon + low energy pulse) from 5:42 UT to 10:13 UT on February 23, 1987.

  6. Analysis of the data recorded by the Mont Blanc neutrino detector and by the Maryland and Rome gravitational-wave detectors during SN 1987 A

    NASA Astrophysics Data System (ADS)

    Aglietta, M.; Badino, G.; Bologna, G.; Castagnoli, C.; Castellina, A.

    1989-02-01

    The paper presents data recorded by the neutrino detector on Mont Blanc and by gravitational wave detectors in Maryland and Rome. The data were obtained over a period of several days and include the occurrence of the Mont Blanc five-neutrino burst. A correlation is found during a period of about two hours roughly centered on the five-neutrino burst, independently between Maryland and Mont Blanc and Rome and Mont Blanc. The probability that these two correlations are due to chance is of the order of between 10 to the -6th and 10 to the -5th.

  7. Correlation between the Maryland and Rome gravitational-wave detectors and the Mont Blanc, Kamioka and IMB particle detectors during SN 1987A.

    NASA Astrophysics Data System (ADS)

    Aglietta, M.; Castellina, A.; Fulgione, W.; Trinchero, G.; Vernetto, S.; Astone, P.; Badino, G.; Bologna, G.; Bassan, M.; Coccia, E.; Modena, I.; Bonifazi, P.; Castellano, M. G.; Visco, M.; Castagnoli, C.; Galeotti, P.; Saavedra, O.; Cosmelli, C.; Frasca, S.; Pallottino, G. V.; Pizzella, G.; Rapagnani, P.; Ricci, F.; Majorana, E.; Gretz, D.; Weber, J.; Wilmot, G.

    1991-11-01

    Following a previously found correlation between the gravitational-wave detectors and the Mont Blanc particle detector, the authors have searched for a similar correlation between the data of the experiments mentioned in the title. They have found that both the Kamioka and the IMB data have a correlation with the gravitational-wave data that occurs with the same characteristics and at the same time of that already found with Mont Blanc. This correlation extends for a period of one or two hours centred at the hour 2:45 UT of 23 February 1987. It shows that the particle detector signals are delayed with respect to the gravitational-wave detector signals by (1.2±0.5)s. The probability that the additional correlation due to Kamioka and IMB is only accidental is estimated of the order of 10-3 or 10-4.

  8. SN 1978K: An evolved supernova outside our Local Group detected at millimetre wavelengths

    NASA Astrophysics Data System (ADS)

    Ryder, S. D.; Kotak, R.; Smith, I. A.; Tingay, S. J.; Kool, E. C.; Polshaw, J.

    2016-11-01

    Supernova 1978K is one of the oldest-known examples of the class of Type IIn supernovae that show evidence for strong interaction between the blast wave and a dense, pre-existing circumstellar medium. Here we report detections of SN 1978K at both 34 GHz and 94 GHz, making it only the third extragalactic supernova (after SN 1987A and SN 1996cr) to be detected at late-times at these frequencies. We find SN 1978K to be >400 times more luminous than SN 1987A at millimetre wavelengths in spite of the roughly nine year difference in ages, highlighting the risk in adopting SN 1987A as a template for the evolution of core-collapse supernovae in general. Additionally, from new VLBI observations at 8.4 GHz, we measure a deconvolved diameter for SN 1978K of 5 milli-arcsec, and a corresponding average expansion velocity of <1500 km s-1. These observations provide independent evidence of an extremely dense circumstellar medium surrounding the progenitor star.

  9. STIS CHEMICALLY ANALYZES THE RING AROUND SUPERNOVA 1987A

    NASA Technical Reports Server (NTRS)

    2002-01-01

    he Hubble Space Telescope's Wide Field and Planetary Camera 2 (WFPC2) is back at work, capturing this black-and-white image of the 'butterfly wing'-shaped nebula, NGC 2346. The nebula is about 2,000 light-years away from Earth in the direction of the constellation Monoceros. It represents the spectacular 'last gasp' of a binary star system at the nebula's center. The image was taken on March 6, as part of the recommissioning of the Hubble Space Telescope's previously installed scientific instruments following the successful servicing of the HST by NASA astronauts in February. WFPC2 was installed in HST during the servicing mission in 1993. At the center of the nebula lies a pair of stars that are so close together that they orbit around each other every 16 days. This is so close that, even with Hubble, the pair of stars cannot be resolved into its two components. One component of this binary is the hot core of a star that has ejected most of its outer layers, producing the surrounding nebula. Astronomers believe that this star, when it evolved and expanded to become a red giant, actually swallowed its companion star in an act of stellar cannibalism. The resulting interaction led to a spiraling together of the two stars, culminating in ejection of the outer layers of the red giant. Most of the outer layers were ejected into a dense disk, which can still be seen in the Hubble image, surrounding the central star. Later the hot star developed a fast stellar wind. This wind, blowing out into the surrounding disk, has inflated the large, wispy hourglass-shaped wings perpendicular to the disk. These wings produce the butterfly appearance when seen in projection. The total diameter of the nebula is about one-third of a light-year, or 2 trillion miles. Our own Sun will eject a nebula about 5 billion years from now. However, the Sun is not a double star, so its nebula may well be more spherical in shape. The image was taken through a filter that shows the light of glowing nitrogen atoms. Scientists are still testing and calibrating the newly installed instruments on Hubble , the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) and the Space Telescope Imaging Spectrograph (STIS). These instruments will be ready to make observations in a few weeks. Credit: Massimo Stiavelli (STScI), and NASA other team member: Inge Heyer (STScI) Image files in GIF and JPEG format and captions may be accessed on the Internet via anonymous ftp from oposite.stsci.edu in /pubinfo.

  10. The Reconceptualization of Curriculum Studies, 1987: A Personal Retrospective.

    ERIC Educational Resources Information Center

    Pinar, William F.

    1988-01-01

    Relates how historical developments initiated the curriculum reform movement, which caused curriculum studies to become vulnerable to reconceptualization. Traces the movement from Sputnik in 1957 through reconceptualists' opposition to the mainstream field in the 1970s. The opposition has now become the field itself, which is characterized by…

  11. The great Chinese fire of 1987 - A view from space

    NASA Technical Reports Server (NTRS)

    Cahoon, Donald R., Jr.; Levine, Joel S.; Cofer, Wesley R., III; Miller, James E.; Minnis, Patrick; Tennille, Geoffrey M.; Yip, Tommy W.; Stocks, Brian J.; Heck, Patrick W.

    1991-01-01

    One of the largest forest fires ever recorded burned in the People's Republic of China (PRC) and the Soviet Union in May 1987. The fire covered over 1.0 million hectares in the PRC and almost 4 million hectares in the Soviet Union. The progress and areal extent of the fire were measured using satellite images analyzed in the imaging facilities at NASA-Langley and Forestry Canada. The analyses show the utility and value of satellite measurements to assess the areal extent and geographical distribution of fires, and have important implications for future measurements to be obtained from space platforms, such as the Earth Observing System.

  12. Interstellar lines in the spectrum of supernova 1987a

    NASA Technical Reports Server (NTRS)

    Jenkins, Edward B.; Joseph, Charles L.

    1988-01-01

    The primary interest was to analyze the interstellar lines produced by gases along the line of sight which resides in the galactic plane and halo, as well as material in the Large Magellanic Cloud or the immediate environment of the supernovae. The ionization and fine-structure excitation of assorted atoms were intrepreted. The goal was to learn more about conditions in various regions of space and identify the probable origins for some velocity components whose locations were uncertain.

  13. Radiation induced thyroid neoplasms 1920 to 1987: A vanishing problem

    SciTech Connect

    Mehta, M.P.; Goetowski, P.G.; Kinsella, T.J.

    1989-06-01

    Radiation for benign diseases has been implicated as an etiologic factor in thyroid cancer. From 1930-60, over 2 million children may have been exposed to therapeutic radiation and it is estimated that up to 7% may develop thyroid cancer after a 5-40 year latency. Thyroid stimulating hormone, secondary to radioinduced hypothyroidism, has been implicated as causative in animals. Such data has led to expensive screening programs in high risk patients. Because of a decline in irradiation for benign diseases in children over the last 2 decades, we questioned whether the incidence of radiation induced thyroid neoplasms (RITN) was also decreasing. Twenty-six of 227 patients (11%) with thyroid malignancies seen at our institution from 1974-87 had a history of previous head and neck irradiation. These included 13 papillary, 3 follicular, and 7 mixed carcinomas as well as 2 lymphomas and 1 synovial cell sarcoma. None of these 26 patients had abnormal thyroid function tests at presentation. Mean latency from irradiation to the diagnosis of thyroid cancer was 25.4 years (6-55 year range). Compared to the reported increasing incidence of RITN from 1940-70, there appears to be a significant decrease since 1970. Based on our analysis, the use of expensive screening programs in high risk populations may no longer be warranted. Additionally, the routine use of thyroid replacement in previously irradiated chemically hypothyroid patients is not recommended.30 references.

  14. The dust masses in the remnants of Cas A, SN1993J and SN 1980K

    NASA Astrophysics Data System (ADS)

    Barlow, Mike; Bevan, Antonia

    2016-06-01

    Using a recently developed 3D Monte Carlo dust line-scattering and absorption code, Bevan & Barlow (2016, MNRAS) have modeled the red-blue line asymmetries in the late-time Hα and [O i] spectra of SN 1987A caued by the preferential absorption by internal dust particles of redshifted photons from the far side of the ejecta. They found dust masses that grew from ≤ 10-3 M⊙ on day 714 to ≥ 0.10 M⊙ by day 3604, a trend that agrees with the day 615 - 9200 SED modeling results of Wesson et al. (2015) for SN 1987A, for which Herschel and ALMA observations indicate a dust mass of ˜0.7 M⊙ by day 9200. Similar red-blue emission line asymmetries are often observed in the late-time optical spectra of other supernova ejecta and remnants. With the aim of increasing the number of SNR dust mass determinations, we have modeled the red-blue emission line asymmetries in the late-time optical spectra of SN 1993J and SN 1980K published by Milisavljevic & Fesen (2013), as well as modeling similar red-blue line asymmetries seen in the integrated optical spectrum of Cas A published by Milisavljevic et al. (2013). Depending on grain composition, clumped dust masses of 0.1-0.4 M⊙ are required to provide fits to the Year-31 Hα and [O i] line profiles of SN 1980K, while fits to the Year-16 [O ii] and [O iii] line profiles of SN 1993J require up to 0.18 M⊙ of clumped ejecta dust. For Cas A, the fits to its [O i], [O ii] and [O iii] integrated line profiles require about 1 M⊙ of internal dust to be present.

  15. Evolving into a remnant: optical observations of SN 1978K at three decades

    NASA Astrophysics Data System (ADS)

    Kuncarayakti, H.; Maeda, K.; Anderson, J. P.; Hamuy, M.; Nomoto, K.; Galbany, L.; Doi, M.

    2016-05-01

    We present new optical observations of the supernova SN 1978K, obtained in 2007 and 2014 with the Very Large Telescope. We discover that the supernova has not faded significantly, even more than three decades after its explosion. The spectrum exhibits numerous narrow (FWHM ≲600 km s-1) emission lines, indicating that the supernova blastwave is persistently interacting with dense circumstellar material (CSM). Evolution of emission lines indicates that the supernova ejecta is slowly progressing through the reverse shock, and has not expanded past the outer edge of the circumstellar envelope. We demonstrate that the CSM is not likely to be spherically distributed, with mass of ≲1 M⊙. The progenitor mass loss rate is estimated as ≳0.01 M⊙ yr-1. The slowly fading late-time light curve and spectra show striking similarity with SN 1987A, indicating that a rate at which the CSM is being swept-up by the blastwave is gradually decaying and SN 1978K is undergoing similar evolution to become a remnant. Due to its proximity (4 Mpc), SN 1978K serves as the next best example of late-time supernova evolution after SN 1987A.

  16. THIRTY YEARS OF SN 1980K: EVIDENCE FOR LIGHT ECHOES

    SciTech Connect

    Sugerman, Ben E. K.; Andrews, Jennifer E.; Barlow, Michael J.; Clayton, Geoffrey C.; Ercolano, Barbara; Ghavamian, Parviz; Kennicutt, Robert C. Jr.; Krause, Oliver; Meixner, Margaret; Otsuka, Masaaki

    2012-04-20

    We report optical and mid-infrared photometry of SN 1980K between 2004 and 2010, which shows slow monotonic fading consistent with previous spectroscopic and photometric observations made 8-17 yr after outburst. The slow rate of change over two decades suggests that this evolution may result from scattered and thermal light echoes off of extended circumstellar material. We present a semi-analytic dust radiative-transfer model that uses an empirically corrected effective optical depth to provide a fast and robust alternative to full Monte Carlo radiative-transfer modeling for homogenous dust at low to intermediate optical depths. We find that unresolved echoes from a thin circumstellar shell 14-15 lt-yr from the progenitor, and containing {approx}< 0.02 M{sub Sun} of carbon-rich dust, can explain the broadband spectral and temporal evolution. The size, mass, and dust composition are in good agreement with the contact discontinuity observed in scattered echoes around SN 1987A. The origin of slowly changing high-velocity [O I] and H{alpha} lines is also considered. We propose an origin in shocked high-velocity metal-rich clumps of ejecta, rather than arising in the impact of ejecta on slowly moving circumstellar material, as is the case with hot spots in SN 1987A.

  17. Explosion Calculations of SN1087

    NASA Technical Reports Server (NTRS)

    Wooden, Diane H.; Morrison, David (Technical Monitor)

    1994-01-01

    Explosion calculations of SNT1987A generate pictures of Rayleigh-Taylor fingers of radioactive Ni-56 which are boosted to velocities of several thousand km/s. From the KAO observations of the mid-IR iron lines, a picture of the iron in the ejecta emerges which is consistent with the "frothy iron fingers" having expanded to fill about 50% of the metal-rich volume of the ejecta. The ratio of the nickel line intensities yields a high ionization fraction of greater than or equal to 0.9 in the volume associated with the iron-group elements at day 415, before dust condenses in the ejecta. From the KAO observations of the dust's thermal emission, it is deduced that when the grains condense their infrared radiation is trapped, their apparent opacity is gray, and they have a surface area filling factor of about 50%. The dust emission from SN1987A is featureless: no 9.7 micrometer silicate feature, nor PAH features, nor dust emission features of any kind are seen at any time. The total dust opacity increases with time even though the surface area filling factor and the dust/gas ratio remain constant. This suggests that the dust forms along coherent structures which can maintain their radial line-of-sight opacities, i.e., along fat fingers. The coincidence of the filling factor of the dust and the filling factor of the iron strongly suggests that the dust condenses within the iron, and therefore the dust is iron-rich. It only takes approximately 4 x 10(exp -4) solar mass of dust for the ejecta to be optically thick out to approximately 100 micrometers; a lower limit of 4 x 10(exp -4) solar mass of condensed grains exists in the metal-rich volume, but much more dust could be present. The episode of dust formation started at about 530 days and proceeded rapidly, so that by 600 days 45% of the bolometric luminosity was being emitted in the IR; by 775 days, 86% of the bolometric luminosity was being reradiated by the dust. Measurements of the bolometric luminosity of SN1987A from

  18. A massive hypergiant star as the progenitor of the supernova SN 2005gl.

    PubMed

    Gal-Yam, A; Leonard, D C

    2009-04-16

    Our understanding of the evolution of massive stars before their final explosions as supernovae is incomplete, from both an observational and a theoretical standpoint. A key missing piece in the supernova puzzle is the difficulty of identifying and studying progenitor stars. In only a single case-that of supernova SN 1987A in the Large Magellanic Cloud-has a star been detected at the supernova location before the explosion, and been subsequently shown to have vanished after the supernova event. The progenitor of SN 1987A was a blue supergiant, which required a rethink of stellar evolution models. The progenitor of supernova SN 2005gl was proposed to be an extremely luminous object, but the association was not robustly established (it was not even clear that the putative progenitor was a single luminous star). Here we report that the previously proposed object was indeed the progenitor star of SN 2005gl. This very massive star was likely a luminous blue variable that standard stellar evolution predicts should not have exploded in that state.

  19. Formation of quark phases in compact stars and SN explosion

    SciTech Connect

    Drago, A.; Pagliara, G.; Pagliaroli, G.; Villante, F. L.; Vissani, F.

    2008-10-13

    We describe possible scenarios of quark deconfinement in compact stars and we analyze their astrophysical implications. The quark deconfinement process can proceed rapidly, as a strong deflagration, releasing a huge amount of energy in a short time and generating an extra neutrino burst. If energy is tranferred efficiently to the surface, like e.g. in the presence of convective instabilities, this burst could contribute to revitalize a partially failed SN explosion. We discuss how the neutrino observations from SN1987A would fit in this scenario. Finally, we focus on the fate of massive and rapidly rotating progenitors, discussing possible time separations between the moment of the core collapse and the moment of quark deconfinement. This mechanism can be at the basis of the interpretation of gamma ray bursts in which lines associated with heavy elements are present in the spectrum.

  20. Massive stars dying alone: Extremely remote environments of SN2009ip and SN2010jp

    NASA Astrophysics Data System (ADS)

    Smith, Nathan

    2014-10-01

    We propose an imaging study of the astonishingly remote environments of two recent supernovae (SNe): SN2009ip and SN2010jp. Both were unusual Type IIn explosions that crashed into dense circumstellar material (CSM) ejected by the star shortly before explosion. The favored progenitors of these SNe are very massive luminous blue variable (LBV) stars. In fact, SN2009ip presents an extraordinay case where the LBV-like progenitor was actually detected directly in archival HST data, and where we obtained spectra and photometry for numerous pre-SN eruptions. No other SN has this treasure trove of detailed information about the progenitor (not even SN1987A). SN2010jp represents a possible collapsar-powered event, since it showed evidence of a fast bipolar jet in spectra and a low 56Ni mass; this would be an analog of the black-hole forming explosions that cause gamma ray bursts, but where the relativistic jet is damped by a residual H envelope on the star. In both cases, the only viable models for these SNe involve extremely massive (initial masses of 40-100 Msun) progenitor stars. This seems at odds with their extremely remote environments in the far outskirts of their host galaxies, with no detected evidence for an underlying massive star population in ground-based data (nor in the single shallow WFPC2/F606W image of SN2009ip). Here we propose deep UV HST images to search for any mid/late O-type stars nearby, deep red images to detect any red supergiants, and an H-alpha image to search for any evidence of ongoing star formation in the vicinity. These observations will place important and demanding constraints on the initial masses and ages of these progenitors.

  1. State of the World: 1987. A Worldwatch Institute Report on Progress toward a Sustainable Society.

    ERIC Educational Resources Information Center

    Brown, Lester R.; And Others

    This book was developed to highlight the risks that confront societies, and to indicate the most promising avenues for preemptive policies and actions. The document contains chapters on: (1) the emergence of change; (2) analyzing demographic factors; (3) assessing the future of urbanization; (4) reassessing nuclear power (including an analysis of…

  2. News Source Use in the Crash of 1987: A Study of Four National Media.

    ERIC Educational Resources Information Center

    Lasorsa, Dominic L.; Reese, Stephen D.

    1990-01-01

    Examines coverage of the stock market crash in 1987 by CBS Evening News, "Newsweek," the "New York Times," and "Wall Street Journal." Finds that print media favored Wall Street sources whereas CBS favored government sources. Finds that news media favor high prestige sources and that use of different sources results in…

  3. ARGX-87: Accident Response Group Exercise, 1987: A Broken Arrow mini exercise. [Training

    SciTech Connect

    Schuld, E.P.; Cruff, D.F.

    1987-07-01

    A Broken Arrow mini exercise dubbed ''Accident Response Group Exercise - 1987'' (ARGX-87) was conducted on June 1, 1987 at the Lawrence Livermore National Laboratory (LLNL) and Sandia National Laboratories, Livermore (SNLL). The exercise started at 0445 PDT with a call from the Department of Energy (DOE) - EOC in Washington, DC, to the Albuquerque Operations (AL - ) - EOC. AL, in turn, called the Laboratory off-hour emergency number (Fire Dispatcher), who called the Laboratory Emergency Duty Officer (LEDO). The LEDO then contacted the Accident Response Group (ARG) Senior Scientific Advisor. Calls were placed to assemble appropriate members of the ARG in the ALERT Center. No phone number for SNLL was available at the Albuquerque Operations EOC, so a controller injected a message to SNLL to get them involved in the exercise. The messages received at the Laboratory identified the Air Force line item weapon system involved in the accident and the accident location. As people arrived at the ALERT Center they began discussing the details of the accident. They also started working the deployment logistics and other issues. Travel arrangements for the HOT SPOT equipment and ARG personnel were made for immediate deployment to the accident site in North Dakota. The exercise was terminated at 0840 as planned. While certain procedural deficiencies were noted, the exercise was considered a valuable learning experience. The results and observations from this experience will be used to refine the operating procedures and the training program.

  4. The Continuing Growth of Hunger, Homelessness, and Poverty in America's Cities: 1987. A 26-City Survey.

    ERIC Educational Resources Information Center

    Reyes, Lilia M.; Waxman, Laura DeKoven

    This survey assesses the status of hunger, homelessness, and poverty in cities in the United States during 1987. The findings include the following: (1) the number of the homeless and the poor had increased and was expected to continue to increase; (2) the demand for emergency food assistance and emergency shelter assistance had increased and was…

  5. Mass Loss and Pre-SN Evolution of Massive Stars

    NASA Astrophysics Data System (ADS)

    Smith, N.

    2010-06-01

    I review the role that mass loss plays in the pre-SN evolution of massive stars in a variety of different scenarios, and what observable effect it may have on the resulting SN. The amount of mass lost, its speed, and how soon before core collapse the material is removed can have a dramatic effect on the resulting SN light curve and spectrum. Massive stars trek across the HR diagram as they evolve, and the SN can look very different depending on where along this path core collapse occurs; it may not depend solely on initial mass. The most extreme pre-SN mass ejections in massive luminous blue variables (LBVs) have recently (and surprisingly) been linked to the very luminous Type IIn supernovae with circumstellar interaction that dominates the spectrum and enhances the visual luminosity. In some cases these objects require strong LBV-like shell ejections in the decades immediately before a SN. Strong winds or episodic mass loss of luminous red supergiants (RSGs) and yellow hypergiants may also lead to less extreme Type IIn events. Post-RSG blue supergiants like SN 1987A's progenitor and lower-luminosity LBVs like HD 168625 are also candidates for Type II SNe with visible circumstellar material. Finally, progenitors that successfully shed their H envelopes (either through LBV eruptions, strong winds, or binary mass transfer) die as Type Ib or Ic supernovae, and some of these also show evidence for immediate pre-SN shell ejections. Many of the potential progenitors of Types Ib, Ic, IIn, IIb, and II-L overlap in their range of probable initial mass, and I will point to some open questions about how they fit together in the context of stellar evolution, and the roles of mass loss and initial mass in determining their relative rates.

  6. Offsite radiation doses from Hanford Operations for the years 1983 through 1987: A comparison of results calculated by two methods

    SciTech Connect

    Soldat, J.K.

    1989-10-01

    This report compares the results of the calculation of potential radiation doses to the public by two different environmental dosimetric systems for the years 1983 through 1987. Both systems project the environmental movement of radionuclides released with effluents from Hanford operations; their concentrations in air, water, and foods; the intake of radionuclides by ingestion and inhalation; and, finally, the potential radiation doses from radionuclides deposited in the body and from external sources. The first system, in use for the past decade at Hanford, calculates radiation doses in terms of 50-year cumulative dose equivalents to body organs and to the whole body, based on the methodology defined in ICRP Publication 2. This system uses a suite of three computer codes: PABLM, DACRIN, and KRONIC. In the new system, 50-year committed doses are calculated in accordance with the recommendations of the ICRP Publications 26 and 30, which were adopted by the US Department of Energy (DOE) in 1985. This new system calculates dose equivalent (DE) to individual organs and effective dose equivalent (EDE). The EDE is a risk-weighted DE that is designed to be an indicator of the potential health effects arising from the radiation dose. 16 refs., 1 fig., 38 tabs.

  7. Review of the General Information Programme, 1977-1987. A Compilation of Information on Its Characteristics, Activities and Accomplishments.

    ERIC Educational Resources Information Center

    Roberts, Kenneth H.

    This booklet covers the development of Unesco's General Information Program (PGI), which was created in 1977 to insure a coherent development of Unesco's work in the areas of scientific and technological information, documentation, libraries, and archives. A description of the history of the organization and its predecessors, the structure of the…

  8. United States Catholic Elementary and Secondary Schools, 1986-1987. A Statistical Report on Schools, Enrollment, & Staffing.

    ERIC Educational Resources Information Center

    Bredeweg, Frank H.

    This publication contains the core school, enrollment, and staffing data of the National Catholic Educational Association's historical file. A page of statistical highlights of the current status of Catholic schools is followed by (1) an introductory essay by Frank H. Bredeweg, C.S.B., which briefly describes the growth of American Catholic…

  9. X-Rays from the Explosion Site: Fifteen Years of Light Curves of SN 1993J

    NASA Technical Reports Server (NTRS)

    Chandra, Poonam; Dwarkadas, Vikram V.; Ray, Alak; Immler, Stefan; Pooley, David

    2009-01-01

    We present a comprehensive analysis of the X-ray light curves of SN 1993J in a nearby galaxy M81. This is the only supernova other than SN 1987A, which is so extensively followed in the X-ray bands. Here we report on SN 1993J observations with the Chandra in the year 2005 and 2008, and Swift observations in 2005, 2006 and 2008. We combined these observations with all available archival data of SN 1993J, which includes ROSAT, ASCA, Chandra, and XMM-Newton, observations from 1993 April to 2006 August. In this paper we report the X-ray light curves of SN 1993J, extending up to fifteen years, in the soft (0.3-2.4 keV), hard (2-8 keV) and combined (0.3-8 keV) bands. The hard and soft-band fluxes decline at different rates initially, but after about 5 years they both undergo a t(sup -1) decline. The soft X-rays, which are initially low, start dominating after a few hundred days. We interpret that most of the emission below 8 keV is coming from the reverse shock which is radiative initially for around first 1000-2000 days and then turn into adiabatic shock. Our hydrodynamic simulation also confirms the reverse shock origin of the observed light curves. We also compare the Ha line luminosity of SN 1993J with its X-ray light curve and note that the Ha line luminosity has a fairly high fraction of the X-ray emission, indicating presence of clumps in the emitting plasma.

  10. A new precise mass for the progenitor of the Type IIP SN 2008bk

    NASA Astrophysics Data System (ADS)

    Maund, Justyn R.; Mattila, Seppo; Ramirez-Ruiz, Enrico; Eldridge, John J.

    2014-02-01

    The progenitor of the Type IIP supernova (SN) 2008bk was discovered in pre-explosion g'r'i'IYJHKs images, acquired with European Southern Observatory Very Large Telescope FOcal Reducer and low dispersion Spectrograph, High Acuity Wide field K-band Imager and Infrared Spectrometer and Array Camera instruments and the Gemini Multi-Object Spectrograph-South instrument. The wealth of pre-explosion observations makes the progenitor of this SN one of the best studied, since the detection of the progenitor of SN 1987A. Previous analyses of the properties of the progenitor were hampered by the limited quality of the photometric calibration of the pre-explosion images and the crowded nature of the field containing the SN. We present new late-time observations of the site of SN 2008bk acquired with identical instrument and filter configurations as the pre-explosion observations, and confirm that the previously identified red supergiant (RSG) star was the progenitor of this SN and has now disappeared. Image subtraction techniques were used to conduct precise photometry of the now missing progenitor, independently of blending from any nearby stars. The nature of the surrounding stellar population and their contribution to the flux attributed to the progenitor in the pre-explosion images are probed using Hubble Space Telescope Wide Field Camera 3 Ultraviolet-Visible/Infrared observations. In comparison with MARCS synthetic spectra, we find the progenitor was a highly reddened RSG with luminosity log (L/{L}_{{⊙}})=4.84^{+0.10}_{-0.12}, corresponding to an initial mass of M_init=12.9^{+1.6}_{-1.8} M_{{⊙}}. The temperature of the progenitor was hotter than previously expected for RSGs (T ˜ 4330 K), but consistent with new temperatures derived for RSGs using spectral energy distribution fitting techniques. We show that there is evidence for significant extinction of the progenitor, possibly arising in the circumstellar medium, but that this dust yields a similar reddening law

  11. SN REFSDAL: PHOTOMETRY AND TIME DELAY MEASUREMENTS OF THE FIRST EINSTEIN CROSS SUPERNOVA

    SciTech Connect

    Rodney, S. A.; Strolger, L.-G.; Brammer, G.; Kelly, P. L.; Filippenko, A. V.; Bradač, M.; Foley, R. J.; Graur, O.; Hjorth, J.; Selsing, J.; Jha, S. W.; McCully, C.; Molino, A.; Riess, A. G.; Schmidt, K. B.; Sharon, K.; Treu, T.; and others

    2016-03-20

    We present the first year of Hubble Space Telescope imaging of the unique supernova (SN) “Refsdal,” a gravitationally lensed SN at z = 1.488 ± 0.001 with multiple images behind the galaxy cluster MACS J1149.6+2223. The first four observed images of SN Refsdal (images S1–S4) exhibited a slow rise (over ∼150 days) to reach a broad peak brightness around 2015 April 20. Using a set of light curve templates constructed from SN 1987A-like peculiar Type II SNe, we measure time delays for the four images relative to S1 of 4 ± 4 (for S2), 2 ± 5 (S3), and 24 ± 7 days (S4). The measured magnification ratios relative to S1 are 1.15 ± 0.05 (S2), 1.01 ± 0.04 (S3), and 0.34 ± 0.02 (S4). None of the template light curves fully captures the photometric behavior of SN Refsdal, so we also derive complementary measurements for these parameters using polynomials to represent the intrinsic light curve shape. These more flexible fits deliver fully consistent time delays of 7 ± 2 (S2), 0.6 ± 3 (S3), and 27 ± 8 days (S4). The lensing magnification ratios are similarly consistent, measured as 1.17 ± 0.02 (S2), 1.00 ± 0.01 (S3), and 0.38 ± 0.02 (S4). We compare these measurements against published predictions from lens models, and find that the majority of model predictions are in very good agreement with our measurements. Finally, we discuss avenues for future improvement of time delay measurements—both for SN Refsdal and for other strongly lensed SNe yet to come.

  12. Columbia University Participation in the Infrared Space Observatory (ISO) Guest Obs. Program: Evolution of Near-Infrared Lines from the Formation of Supernova Remnant 1987A

    NASA Technical Reports Server (NTRS)

    Crotts, Arlin P. S.

    2000-01-01

    The goal of this project is to determine the mass loss history of a sample of seven mass losing Asymptotic Giant Branch stars. This is done by observing their circumstellar dust shells which contain a record of the most recent mass loss history. The further away from the star we are able to detect this increasingly fainter dust emission the further back we can look into the mass loss history.

  13. High-Velocity Star Formation in the Large Magellanic Cloud.

    PubMed

    Graff; Gould

    2000-05-01

    Light-echo measurements show that SN 1987A is 425 pc behind the LMC disk. It is continuing to move away from the disk at 18 km s-1. Thus, it has been suggested that SN 1987A was ejected from the LMC disk. However, SN 1987A is a member of a star cluster, so this entire cluster would have to have been ejected from the disk. We show that the cluster was formed in the LMC disk, with a velocity perpendicular to the disk of about 50 km s-1. Such high-velocity formation of a star cluster is unusual, having no known counterpart in the Milky Way.

  14. Older Americans Act Amendments of 1987: A Summary of Provisions. Public Law 100-175. An Information Paper Prepared for Use by the Special Committee on Aging. United States Senate, 100th Congress, 1st Session.

    ERIC Educational Resources Information Center

    O'Shaughnessy, Carol

    The Older American Act Amendments of 1987 (Public Law 100-175) contain no major overhaul of the Act, but new provisions do significantly expand certain service components of the state and area agency on aging program under title III to address the special needs of certain populations, including the frail elderly living at home, residents of…

  15. Curvas de luz de supernovas ricas en hidrógeno

    NASA Astrophysics Data System (ADS)

    Rojas Kaufmann, M. L.; Bersten, M.

    2016-08-01

    Type II supernovae (SNe II) are the most common type of explosions in the Universe. There is a small and peculiar subgroup of those objects that show light curves similar to the famous SN 1987A. In this work we present an analysis of how the variation of certain physical parameters such as the mass and radius of the progenitor star, the energy of the explosion and the amount of radioactive material impact on the light curve of these objects, based on models that simulate the stellar explosions. In particular, we analyze the case of SN 2009mw, one of the few supernovae with similar characteristics to the SN 1987A.

  16. Liquidus Projections of Sn-Co-Ni and Sn-Rich Sn-Ag-Co-Ni Systems

    NASA Astrophysics Data System (ADS)

    Chen, Sinn-wen; Chen, Tung-Kai; Hsu, Chia-ming; Chang, Jui-shen; Pan, Kevin

    2014-07-01

    Alloys based on Sn and Sn-Ag are commonly used as Pb-free solders, and Ni is frequently used in barrier layers. Co has been studied as a possible alloying element in both solders and barrier layers. Thus, the Sn-Co-Ni and Sn-Ag-Co-Ni alloy systems are important for electronic soldering. Forty-nine Sn-Co-Ni alloys and 24 Sn-rich Sn-Ag-Co-Ni alloys were prepared. The primary solidification phases of these as-cast alloys were determined, and based on these results and the available phase diagrams of the constituent systems, the liquidus projections of Sn-Co-Ni ternary and Sn-Ag-Co-Ni quaternary systems at 90 at.% and 95 at.% Sn were determined. In the Sn-Co-Ni system, no ternary compound was found; (Ni,Co)3Sn2 and (Ni,Co) are continuous solid solutions, and there are eight kinds of primary solidification phases: Sn, CoSn3, CoSn2, CoSn, (Ni,Co)3Sn2, (Ni,Co), Ni3Sn, and Ni3Sn4. In the 90 at.% and 95 at.% Sn isoplethal sections of the Sn-Ag-Co-Ni liquidus projection, the primary solidification phases are CoSn2, CoSn, Ni3Sn4, and Ag3Sn.

  17. Synthesis, photocatalytic and antimicrobial properties of SnO2, SnS2 and SnO2/SnS2 nanostructure.

    PubMed

    Fakhri, Ali; Behrouz, Sajjad; Pourmand, Melika

    2015-08-01

    Nanoscale SnO2, SnS2 and SnO2/SnS2 were synthesized by hydrothermal treatment method and characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), Barrett-Joyner-Halenda (BJH) and UV-vis spectra. The photocatalytic activity of SnO2, SnS2 and SnO2/SnS2 were tested with Enrofloxacin antibiotic. The tetragonal and hexagonal SnO2 and SnS2 phase was confirmed through XRD, respectively. The photocatalytic results indicated that the SnO2/SnS2 enhanced the photocatalytic activity and could be effectively used as photocatalyst for degradation of Enrofloxacin antibiotic pollutant. The results of antibacterial experiment under visible light irradiation demonstrate that the SnO2/SnS2 nanocomposite exhibit enhanced antibacterial efficiency compared with pure SnO2 and SnS2. The antifungal activity of the nanoscale SnO2, SnS2 and SnO2/SnS2 against Candida albicans was assessed using the disc-diffusion susceptibility tests. It was seen that the antifungal activity of SnO2/SnS2 nanocomposite is higher than the pure SnO2 and SnS2 toward pathogenic C. albicans.

  18. Type Ia supernova diversity: Studies of SN 2007qd, SN 2008Q and SN 2011fe

    NASA Astrophysics Data System (ADS)

    McClelland, Colin M.

    Type Ia supernovae (SN Ia) have proven to be incredibly useful as distance indicators and in nuclear astrophysics, but there remain many unanswered questions as to their nature. We examine three particular SN Ia at length in an attempt to provide constraints on both their theory and their application to cosmology. We first present SN 2007qd, one of the lowest-luminosity SN Ia ever discovered. It appears to belong to the SN 2002cx-like subclass of peculiar SN Ia. We observe and analyze the photospheric-phase spectra and photometry for this event and determine that, despite its extreme nature, it still appears to be a thermonuclear event rather than a core-collapse SN Ic. We also discover a possible relation between the luminosity and the low expansion velocities (2000˜7000 km/s) of similar events, and determine that they constitute a well-defined group of SN Ia. From the explosion kinematics and the content of the spectra, we argue that SN 2007qd was likely caused by a pure deflagration of a carbon and oxygen white dwarf. We then consider SN 2008Q, a SN Ia that exploded in the same early-type host galaxy as the peculiar SN 2000cx. This provided a chance for a direct comparison of two SN Ia at the same distance, extinction and host environment. We combine photometry from the ultraviolet through to the mid-infrared (MIR) and create a picture of how this SN evolved bolometrically over a span of two years. We discover that SN 2008Q was relatively bright in the ultraviolet, and characterize the possible existence of a class of SN Ia with similar UV excesses. We identify intrinsic differences between SN 2008Q and SN 2000cx, and discuss what this means for the variation in explosion and nebular physics in SN Ia events. We present next the mid-infrared and optical decay of SN 2011fe. This SN Ia exploded in the nearby galaxy M101, allowing observations of high signal-to-noise during the later phases. We examine this SN with Spitzer/IRAC MIR photometry and discover that the

  19. SN Candidates from CRTS

    NASA Astrophysics Data System (ADS)

    Drake, A. J.; Mahabal, A. A.; Djorgovski, S. G.; Graham, M. J.; Williams, R.; Catelan, M.; Beshore, E. C.; Larson, S. M.; Boattini, A.; Gibbs, A.; Hill, R.; Kowalski, R.; Christensen, E.

    2009-02-01

    The Catalina Real-time Transient Survey has so far discovered over six hundred significant optical transients. Here we report on seven probable SN discoveries made with CSS images between UT dates Jan 20th and Feb 19th.

  20. SN 2014bc, SN2014bi and SN 1981K not detected in radio

    NASA Astrophysics Data System (ADS)

    Bietenholz, Michael; Bartel, Norbert

    2014-08-01

    We report on 10 GHz Jansky Very Large Array radio observations of SN 2014bc (Psn J12185771+4718113; Smartt et al CBET #3877) and SN 2014bi (PSN J12060299+4729335; Kumar et al, CBET #3892), as well as SN 1981K.

  1. SN Environments in LEGUS

    NASA Astrophysics Data System (ADS)

    Van Dyk, Schuyler D.; LEGUS Team

    2017-01-01

    From the LEGUS multi-band data we can analyze the stellar environments of recent supernovae (SNe), attempt to recover emission from the aging SNe, and search for light echoes around them. We can attempt to constrain the properties of the SN progenitor, based on age estimates for stellar populations in the immediate SN environments. The sites of 15 SNe of various types can be isolated in these images. I will briefly provide a summary of what we have learned about these SNe from their LEGUS environments. A few of these environments have been analyzed and published by other teams. In addition, two SNe occurred shortly after observations were made of two of the galaxies in our sample, NGC 4258 and NGC 1566. I will talk about the inferences we can make regarding the progenitors of these two core-collapse events. In general, the LEGUS dataset will be a valuable resource for identifying the progenitors of future SNe.

  2. Research and technology, 1988

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Flight projects and mission definition studies for 1988 are briefly described. Technology research is presented in the following areas: sensors and space technology; space communication systems; system and software engineering; user space data systems; and techniques. Studies are presented for the following space and Earth science areas: atmospheres, SN 1987A, astronomy, high energy astrophysics, land and climate, solar systems, and oceans.

  3. Continuous Dust Formation in SNe 2010jl and 2011ja

    NASA Astrophysics Data System (ADS)

    Krafton, Kelsie; Clayton, Geoffrey; Andrews, Jennifer; Barlow, Michael; De Looze, Ilse

    2016-08-01

    Studies in the last 10 years of dust formation in core-collapse supernovae (CCSNe) have found only small amounts, ~0.001 solar masses. This is far less than the amount needed to account for the large masses of dust seen in some high redshift galaxies. However, the recent discovery of ~1 solar mass of cold dust in the ejecta of SN 1987A has has caused a complete re-evaluation of dust formation in CCSNe. It has been suggested that the CCSNe are continuously forming dust so that by the time they are about 25 years old they will have dust masses similar to SN 1987A. However, there is a wide time gap between the CCSNe that have been studied recently and SN 1987A. We plan to use the sensitivity of Spitzer to detect dust emission from CCSNe 5 or more years after explosion. Radiative transfer models will be used to estimate the dust masses. This proposal is to continue our study of two interesting SNe 2010jl and 2011ja. These observations are part of a long term study requiring multiple epochs of Spitzer observations to look for evidence of continuous dust formation. These observations will help shed light on the mystery of dust in SN 1987A.

  4. L'astronomie dans le monde

    NASA Astrophysics Data System (ADS)

    Manfroid, J.

    2014-02-01

    Gaia; GRBs et trous noirs; Champ magnétique à la surface d’une Mira; L’astéroïde 2014AA; SN 1987A; Azote cométaire; Fomalhaut; Étoiles multiples; Spirales; Pourquoi y a-t-il des étoiles massives ?; Nébuleuse du Crabe; Un pulsar et deux naines blanches

  5. Report of the High Energy Physics Advisory Panel (HEPAP) subpanel on high energy gamma ray and neutrino astronomy

    SciTech Connect

    Gaisser, T.K.; Gordon, H.A.; Melissinos, A.; Rosen, S.P.; Ruderman, M.A.; Turner, M.S.; Zeller, M.

    1988-11-01

    This report contains information on topics of neutrino and gammay-ray astronomy. Some of the topics discussed are: SN1987A, statistics and variability, background rejection and muons, relation between photon and neutrinos, sensitivity of gamma-ray experiments, comparison of air Cherenkov experiments, air shower experiment, and underground experiments. (LSP)

  6. Pair production of helicity-flipped neutrinos in supernovae

    NASA Technical Reports Server (NTRS)

    Perez, Armando; Gandhi, Raj

    1989-01-01

    The emissivity was calculated for the pair production of helicity-flipped neutrinos, in a way that can be used in supernova calculations. Also presented are simple estimates which show that such process can act as an efficient energy-loss mechanism in the shocked supernova core, and this fact is used to extract neutrino mass limits from SN 1987A neutrino observations.

  7. Search for neutrino radiation from gravitational collapses of stars using the LSD detector under Mont Blanc

    NASA Astrophysics Data System (ADS)

    Dadykin, V. L.; Zatsepin, G. T.; Korol'Kova, E. V.; Korchagin, V. B.; Korchagin, P. V.; Kudryavtsev, V. A.; Mal'Gin, A. S.; Ryazhskaya, O. G.; Ryasnyj, V. G.; Talochkin, V. P.

    1993-04-01

    An analysis of LSD data for the period from August 1985 to November 1991 does not reveal possible candidates for neutrino bursts from gravitational collapses of stars, except for the event of February 23, 1987, which may be related to SN 1987A. Upper bounds are obtained for neutrino fluxes from relict supernovae.

  8. Progresses of Search for Gravitational Wave Events Using TAMA300 Data

    NASA Astrophysics Data System (ADS)

    Kanda, N.; Ando, M.; Nakano, H.; Soida, K.; Tagoshi, H.; Takahashi, H.; Tatsumi, D.; Tsunesada, Y.; TAMA Collaboration

    2003-07-01

    We implemented and evaluated the Gravitational wave event search in TAMA 300 data analysis. Our searches are for the inspiral gravitational wave from coalescing compact binary, Black Hole (BH) quasi-normal ringing, supernova bursts, and continuous wave from SN1987a remnant. Using TAMA's over 2000 hours of observation data, we have progresses of the searches and improved the upper limits.

  9. Electronic Structure and Defect Physics of Tin Sulfides: SnS, Sn2S3 , and Sn S2

    NASA Astrophysics Data System (ADS)

    Kumagai, Yu; Burton, Lee A.; Walsh, Aron; Oba, Fumiyasu

    2016-07-01

    The tin sulfides SnS, Sn2S3 , and Sn S2 are investigated for a wide variety of applications such as photovoltaics, thermoelectrics, two-dimensional electronic devices, Li ion battery electrodes, and photocatalysts. For these applications, native point defects play important roles, but only those of SnS have been investigated theoretically in the literature. In this study, we consider the band structures, band-edge positions, and thermodynamical stability of the tin sulfides using a density functional that accounts for van der Waals corrections and the G W0 approximation. We revisit the point-defect properties, namely, electronic and atomic structures and energetics of defects, in SnS and newly examine those in Sn S2 and Sn2S3 with a comparison to those in SnS. We find that Sn S2 shows contrasting defect properties to SnS: Undoped SnS shows p -type behavior, whereas Sn S2 shows n type, which are mainly attributed to the tin vacancies and tin interstitials, respectively. We also find that the defect features in Sn2S3 can be described as a combination of those in SnS and Sn S2 , intrinsically Sn2S3 showing n -type behavior. However, the conversion to p type can be attained by doping with a large monovalent cation, namely, potassium. The ambipolar dopability, coupled with the earth abundance of its constituents, indicates great potential for electronic applications, including photovoltaics.

  10. Observational Evidence for Mixing and Dust Condensation in Core-Collapse Supernovae

    NASA Technical Reports Server (NTRS)

    Wooden, Diane; Young, Richard E. (Technical Monitor)

    1997-01-01

    Recent findings of isotopic anomalies of Ca-44 (the decay product of Ti-44) and the enhanced ratio of Si-28/Si-30 in SiC grains X, TiC subgrains, and graphite dust grains within primitive meteorites provides strong evidence that these presolar grains came from core-collapse supernovae. The chemical composition of the presolar grains requires macroscopic mixing of newly nucleo-synthesized elements from explosive silicon burning at the innermost zone of the ejects to higher velocities where C exists and where C/O > 1 in either the outer edge of the oxygen zone or in the He-C zone. To date, the only core-collapse supernova observed to form dust is the brightest supernova of the past four centuries, SN1987A in the Large Magellanic Cloud. Observations of SN1987A confirm large scale macroscopic mixing occurs in the explosions of massive stars. Rayleigh-Taylor instabilities macroscopically mix most of the ejects into regions which are still chemically homogeneous and which cool with different time scales. Only small clumps in the ejects are microscopically mixed. Observations show that dust condensed in the ejects of SN1987A after approx.500 days in the Fe-rich gas. Neither silicates nor SiC grains were seen in the dust emission spectrum of SN1987A. SN1987A, the Rosetta Stone of core-collapse supernovae, shows that while the mixing required to explain presolar grains occurs, the rapid cooling of the Fe zone and the sustained high temperatures of the O-Si, O-C, and He-C zones favor the formation of iron-rich rather than oxygen- or carbon-rich grains.

  11. PROTEUS-SN User Manual

    SciTech Connect

    Shemon, Emily R.; Smith, Micheal A.; Lee, Changho

    2016-02-16

    PROTEUS-SN is a three-dimensional, highly scalable, high-fidelity neutron transport code developed at Argonne National Laboratory. The code is applicable to all spectrum reactor transport calculations, particularly those in which a high degree of fidelity is needed either to represent spatial detail or to resolve solution gradients. PROTEUS-SN solves the second order formulation of the transport equation using the continuous Galerkin finite element method in space, the discrete ordinates approximation in angle, and the multigroup approximation in energy. PROTEUS-SN’s parallel methodology permits the efficient decomposition of the problem by both space and angle, permitting large problems to run efficiently on hundreds of thousands of cores. PROTEUS-SN can also be used in serial or on smaller compute clusters (10’s to 100’s of cores) for smaller homogenized problems, although it is generally more computationally expensive than traditional homogenized methodology codes. PROTEUS-SN has been used to model partially homogenized systems, where regions of interest are represented explicitly and other regions are homogenized to reduce the problem size and required computational resources. PROTEUS-SN solves forward and adjoint eigenvalue problems and permits both neutron upscattering and downscattering. An adiabatic kinetics option has recently been included for performing simple time-dependent calculations in addition to standard steady state calculations. PROTEUS-SN handles void and reflective boundary conditions. Multigroup cross sections can be generated externally using the MC2-3 fast reactor multigroup cross section generation code or internally using the cross section application programming interface (API) which can treat the subgroup or resonance table libraries. PROTEUS-SN is written in Fortran 90 and also includes C preprocessor definitions. The code links against the PETSc, METIS, HDF5, and MPICH libraries. It optionally links against the MOAB library and

  12. SAO RAS SN candidates classifications

    NASA Astrophysics Data System (ADS)

    Fatkhullin, T. A.; Moskvitin, A. S.

    2016-08-01

    We observed SN candidates (AT 2016eow, AT 2016enu and AT 2016enf) with the BTA/Scorpio-I on August, 4. Direct images in the R band and long-slit spectra in the range of 3600-7600AA (resolution FWHM = 10A) were obtained.

  13. X-ray studies of Remnants of Core-Collapse Supernovae

    NASA Astrophysics Data System (ADS)

    Lopez, Laura

    2017-01-01

    Supernovae (SNe) play an essential role in the Universe, and they are detected routinely through dedicated surveys. However, most of these SNe are often too distant (1-100 Mpc) to resolve the SN ejecta and immediate surroundings of the exploded stars. Fortunately, supernova remnants (SNRs), including SN 1987A, offer the means to study explosions and dynamics at sub-pc scales. SNRs are observable for up to 100,000 years after the explosions across the electromagnetic spectrum, and almost 400 SNRs have now been identified in the Milky Way and nearby galaxies. In this talk, I will review recent advances in the understanding of core-collapse (CC) SNe based on studies of X-ray studies of SNRs. In particular, I will focus on SN 1987A and other young CC SNRs, highlighting investigations of their explosion (a)symmetries, heavy metal (like iron and titanium) abundances, progenitors, and particle acceleration.

  14. Structure and vibrational dynamics of interfacial Sn layers in Sn/Si multilayers

    NASA Astrophysics Data System (ADS)

    Cuenya, B. Roldan; Keune, W.; Sturhahn, W.; Toellner, T. S.; Hu, M. Y.

    2001-12-01

    The structure and vibrational dynamics of room-temperature-grown nanoscale Sn/amorphous (a-)Si multilayers have been studied by x-ray diffraction, Raman scattering, 119Sn Mössbauer spectroscopy, and 119Sn nuclear-resonant inelastic x-ray scattering (NRIXS) of synchrotron radiation. With increasing Sn-layer thickness, the formation of β-Sn was observed, except at the Sn/Si interfaces, where a 10-Å-thick metastable pure amorphous-α-Sn-like layer remains stabilized. By means of NRIXS we have measured the Sn-projected vibrational density of states (VDOS) in these multilayers (in particular, at the interfaces), and in 500-Å-thick epitaxial α-Sn films on InSb(001) as a reference. Further, the Sn-specific Lamb-Mössbauer factor (f factor), mean kinetic energy per atom, mean atomic force constant, and vibrational entropy per atom were obtained. The VDOS of the amorphous-α-Sn-like interface layer is observed to be distinctly different from that of (bulk) α-Sn and β-Sn, and its prominent vibrational energies are found to scale with those of amorphous Ge and Si. The observed small difference in vibrational entropy (ΔS/kB=+0.17+/-0.05 per atom) between α-Sn and interfacial amorphous-α-like Sn does not account for the stability of the latter phase.

  15. Geochemistry of tin (Sn) in Chinese coals.

    PubMed

    Qu, Qinyuan; Liu, Guijian; Sun, Ruoyu; Kang, Yu

    2016-02-01

    Based on 1625 data collected from the published literature, the geochemistry of tin (Sn) in Chinese coals, including the abundance, distribution, modes of occurrence, genetic types and combustion behavior, was discussed to make a better understanding. Our statistic showed the average Sn of Chinese coal was 3.38 mg/kg, almost two times higher than the world. Among all the samples collected, Guangxi coals occupied an extremely high Sn enrichment (10.46 mg/kg), making sharp contrast to Xinjiang coals (0.49 mg/kg). Two modes of occurrence of Sn in Chinese coals were found, including sulfide-bounded Sn and clay-bounded Sn. In some coalfields, such as Liupanshui, Huayingshan and Haerwusu, a response between REEs distribution and Sn content was found which may caused by the transportation of Sn including clay minerals between coal seams. According to the responses reflecting on REEs patterns of each coalfield, several genetic types of Sn in coalfields were discussed. The enrichment of Sn in Guangxi coals probably caused by Sn-rich source rocks and multiple-stage hydrothermal fluids. The enriched Sn in western Guizhou coals was probably caused by volcanic ashes and sulfide-fixing mechanism. The depletion of Sn in Shengli coalfield, Inner Mongolia, may attribute to hardly terrigenous input and fluids erosion. As a relative easily volatilized element, the Sn-containing combustion by-products tended to be absorbed on the fine particles of fly ash. In 2012, the emission flux of Sn by Chinese coal combustion was estimated to be 0.90 × 10(9) g.

  16. Evaporation Mechanism of Sn and SnS from Liquid Fe: Part III. Effect of C on Sn Removal

    NASA Astrophysics Data System (ADS)

    Jung, Sung-Hoon; Kang, Youn-Bae; Seo, Jeong-Do; Park, Joong-Kil; Choi, Joo

    2015-02-01

    To understand the effect of C on Sn evaporation from liquid iron in the view of ferrous scrap recycling, the evaporation of Sn from various liquid Fe-C-S-Sn alloys was experimentally investigated. A series of gas-liquid reactions was carried out at 1873 K (1600 °C) using an electromagnetic levitation melting technique, where mass transfers in gas phase and liquid phase did not significantly affect the reaction rate. It was found that CS2(g) is a major gas species evaporating from Fe-C-S alloy (initial S content [pct S]0: 0.028 to 0.502 mass pct), and Fe-C-S-Sn alloy ([pct S]0: 0.063 to 0.560 mass pct), thereby competing with SnS for S in the liquid alloy. A model equation for the evaporation rate of CS2(g) was established using the experimental data for the Fe-C-S alloys. The chemical reaction rate constant for the CS2(g) evaporation () was obtained as 4.24 × 10-12 m7 mol-2 s-1, and the residual rate constant () was 4.24 × 10-16 m7 mol-2 s-1, both at 1873 K (1600 °C). Roll of C on the evaporation of Sn in Fe-C-Sn alloy was confirmed to be the increase of activity coefficient of Sn. By taking into account (1) the evaporation of Sn(g), SnS(g), and CS2(g), and (2) the increasing activity coefficient of Sn and S by C, a comprehensive model for the evaporation rate of Sn and S in the Fe-C-Sn-S alloy was developed. The calculation results by the developed model in the present study showed good agreement with the experimental results. Some applications of the current model are presented in the view of increasing the Sn removal rate.

  17. Calculated late time spectra of supernovae

    SciTech Connect

    Axelrod, T.S.

    1987-10-30

    We consider here the nebular phase spectra of supernovae whose late time luminosity is provided by the radioactive decay of /sup 56/Ni and /sup 56/Co synthesized in the explosion. A broad variety of supernovae are known or suspected to fall in this category. This includes all SNIa and SNIb, and at least some SNII, in particular SN1987a. At sufficiently late times the expanding supernova becomes basically nebular in character due to its decreasing optical depth. The spectra produced during this stage contain information on the density and abundance structure of the entire supernova, as opposed to spectra near maximum light which are affected only by the outermost layers. A numerical model for nebular spectrum formation is therefore potentially very valuable for answering currently outstanding questions about the post-explosion supernova structure. As an example, we can hope to determine the degree of mixing which occurs between the layers of the ''onion-skin'' abundance structure predicted by current one dimensional explosion calculations. In the sections which follow, such a numerical model is briefly described and then applied to SN1972e, a typical SNIa, SN1985f, an SNIb, and finally to SN1987a. In the case of SN1987a predicted spectra are presented for the wavelength range from 1 to 100 microns at a time 300 days after explosion. 18 refs., 6 figs.

  18. SN 1961V: From Alpha to Omega?

    NASA Astrophysics Data System (ADS)

    Van Dyk, Schuyler D.; Filippenko, Alexei V.; Cenko, Bradley S.; Shields, Joseph C.

    2013-06-01

    The extraordinary object SN 1961V in NGC 1058 remains controversial to this day. It has long been considered the prototypical "supernova impostor," i.e., the giant eruption of a highly massive star with energetics that rival true supernovae. However, a number of arguments have been put forward that SN 1961V actually was a true SN, and that the explosion followed a sustained powerful outburst from its precursor star, much like the amazing SN 2009ip and other recent events. We will briefly discuss the debate that has roiled over SN 1961V, and we will also present evidence, including from new observations, which may indicate that the precursor has survived. Determining the true nature of SN 1961V will inform our understanding of the late stages of pre-SN evolution for the most massive stars.

  19. Influence of the Sn oxidation state in ferromagnetic Sn-doped In2O3 nanowires

    NASA Astrophysics Data System (ADS)

    Maloney, Francis Scott; Wang, Wenyong

    2016-12-01

    Sn-doped indium oxide nanowires were grown using a vapor-liquid-solid technique (VLS). The Sn content of the nanowires was tunable based on the source powder ratios used in the VLS process. The oxidation state of the Sn ions was examined using x-ray photoelectron spectroscopy. It was found that Sn2+ was the dominant ionic species in samples over 6% (atomic percentage) Sn. The nanowires were found to be ferromagnetic at room temperature, and their saturation magnetization increased with increasing Sn concentration, which could be associated with the spin-splitting of a defect band that was encouraged by the imbalance of Sn2+ to Sn4+ species at high Sn concentrations.

  20. La5Zn2Sn

    PubMed Central

    Oshchapovsky, Igor; Pavlyuk, Volodymyr; Dmytriv, Grygoriy; Chumak, Igor; Ehrenberg, Helmut

    2011-01-01

    A single crystal of penta­lanthanum dizinc stannide, La5Zn2Sn, was obtained from the elements in a resistance furnace. It belongs to the Mo5SiB2 structure type, which is a ternary ordered variant of the Cr5B3 structure type. The space is filled by bicapped tetra­gonal anti­prisms from lanthanum atoms around tin atoms sharing their vertices. Zinc atoms fill voids between these bicapped tetra­gonal anti­prisms. All four atoms in the asymmetric unit reside on special positions with the following site symmetries: La1 (..m); La2 (4/m..); Zn (m.2m); Sn (422). PMID:22219730

  1. Spectra ID of recent SN

    NASA Astrophysics Data System (ADS)

    Challis, Peter

    2013-12-01

    P. Challis, Harvard-Smithsonian Center for Astrophysics (CfA), on behalf of the CfA Supernova Group, report spectra (range 320-860 nm) of various SN obtained during Dec. 24-27 UT by P. Challis, S. Gottilla (MMTO.org), and E. Marin (MMTO.org) with the MMT 6.5-m telescope (+ Blue Channel). Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J.

  2. Effects of interlayer Sn-Sn lone pair interaction on the band gap of bulk and nanosheet SnO

    NASA Astrophysics Data System (ADS)

    Umezawa, Naoto; Zhou, Wei

    2015-03-01

    Effects of interlayer lone-pair interactions on the electronic structure of SnO are firstly explored by the density-functional theory. Our comprehensive study reveals that the band gap of SnO opens as increase in the interlayer Sn-Sn distance. The effect is rationalized by the character of band edges which consists of bonding and anti-bonding states from interlayer lone pair interactions. The band edges for several nanosheets and strained double-layer SnO are estimated. We conclude that the double-layer SnO is a promising material for visible-light driven photocatalyst for hydrogen evolution. This work is supported by the Japan Science and Technology Agency (JST) Precursory Research for Embryonic Science and Technology (PRESTO) program.

  3. SN X-ray Progenitor?

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Identifying stars that explode, right before they explode, is a tricky proposition since the end of starlife comes swiftly: in thermonuclear deflagrations, in nuclear exhaustion, or maybe in a rapid swirling merger of two dead stellar cores. On the right in the image above is an image of the galaxy NGC 1404 taken by the UV/optical Telescope (UVOT) on the Swift observatory. The circle surrounds SN 2007on, a supernova of Type Ia produced by the explosion of a white dwarf star in a binary system. These types of supernovae are important since they are believed to be 'standard candles', events which have the same intrinsic brightness which can serve as an important yardstick to measure cosmic distances. On the left is an image of the same galaxy taken by the Chandra X-ray observatory four years before the supernova. Conspicuous in the SN source circle is a bright source in the Chandra image, believed to be emission from a compact object+normal star companion: a similar system to the supposed precursor of SN 2007on. If true this would be the first time a Type Ia supernova precursor has ever been seen. But astronomers are still debating whether the Chandra source really is the precursor or not; it seems there's a slight but significant difference in the location of the Chandra source and the supernova. Stay tuned for more developments.

  4. Controlling the antibacterial activity of CuSn thin films by varying the contents of Sn

    NASA Astrophysics Data System (ADS)

    Kang, Yujin; Park, Juyun; Kim, Dong-Woo; Kim, Hakjun; Kang, Yong-Cheol

    2016-12-01

    We investigated antibacterial activity of CuSn thin films against Gram positive Staphylococcus aureus (S. aureus). CuSn thin films with different Cu to Sn ratios were deposited on Si(100) by radio frequency (RF) magnetron sputtering method using Cu and Sn metal anodes. The film thickness was fixed at 200 nm by varying the sputtering time and RF power on the metal targets. The antibacterial test was conducted in various conditions such as different contact times and Cu to Sn ratios in the CuSn films. The antibacterial activities of CuSn thin films increased as the ratio of Cu and the contact time between the film and bacteria suspension increased execpt in the case of CuSn-83. The oxidation states of Cu and Sn and the chemical composition of CuSn thin films before and after the antibacterial test were investigated by X-ray photoelectron spectroscopy (XPS). When the contact time was fixed, the Cu species was further oxidized as the RF power on Cu target increased. The intensity of Sn 3d decreased with increasing Cu ratio. When the sample was fixed, the peak intensity of Sn 3d decreased as the contact time increased due to the permeation of Sn into the cell.

  5. Research into the microstructure and mechanical behavior of eutectic Bi-Sn and In-Sn

    SciTech Connect

    Goldstein, J.L.F.; Mei, Z.; Morris, J.W. Jr. |

    1993-08-01

    This manuscript reports on research into two low-melting, lead-free solder alloys, eutectic Bi-Sn and eutectic In-Sn. The microstructures were found to depend on both cooling rate and substrate, with the greatest variability in the In-Sn alloy. The nature of the intermetallic layer formed at the solder-substrate interface depends on both the solder and the substrate (Cu versus Ni). Also, the microstructure of the Bi-Sn can recrystallize during deformation, which is not the case with In-Sn. Data from creep and constant strain rate tests are given for slowly cooled samples. The creep behavior of In-Sn is constant with temperature, but the creep seems to be controlled by the In-rich phase in In-Sn on Cu and by the Sn-rich phase in In-Sn on Ni. Bi-Sn exhibits different creep behavior at temperatures above 40 {degrees}C than at 20 {degrees}C or lower. Stress-strain curves of Bi-Sn on Cu and In-Sn on Cu are similar, while In-Sn on Ni behaves differently. This is explained in terms of the deformation patterns in the alloys.

  6. Process modules for GeSn nanoelectronics with high Sn-contents

    NASA Astrophysics Data System (ADS)

    Schulte-Braucks, C.; Glass, S.; Hofmann, E.; Stange, D.; von den Driesch, N.; Hartmann, J. M.; Ikonic, Z.; Zhao, Q. T.; Buca, D.; Mantl, S.

    2017-02-01

    This paper systematically studies GeSn n-FETs, from individual process modules to a complete device. High-k gate stacks and NiGeSn metallic contacts for source and drain are characterized in independent experiments. To study both direct and indirect bandgap semiconductors, a range of 0-14.5 at.% Sn-content GeSn alloys are investigated. Special emphasis is placed on capacitance-voltage (C-V) characteristics and Schottky-barrier optimization. GeSn n-FET devices are presented including temperature dependent I-V characteristics. Finally, as an important step towards implementing GeSn in tunnel-FETs, negative differential resistance in Ge0.87Sn0.13 tunnel-diodes is demonstrated at cryogenic temperatures. The present work provides a base for further optimization of GeSn FETs and novel tunnel FET devices.

  7. Scaling supernova hydrodynamics to the laboratory

    SciTech Connect

    Kane, J. O.

    1999-06-01

    Supernova (SN) 1987A focused attention on the critical role of hydrodynamic instabilities in the evolution of supernovae. To test the modeling of these instabilities, we are developing laboratory experiments of hydrodynamic mixing under conditions relevant to supernovae. Initial results were reported in J. Kane et al., Astrophys. J.478, L75 (1997) The Nova laser is used to shock two-layer targets, producing Richtmyer-Meshkov (RM) and Rayleigh-Taylor (RT) instabilities at the interfaces between the layers, analogous to instabilities seen at the interfaces of SN 1987A. Because the hydrodynamics in the laser experiments at intermediate times (3-40 ns) and in SN 1987A at intermediate times (5 s-104 s) are well described by the Euler equations, the hydrodynamics scale between the two regimes. The experiments are modeled using the hydrodynamics codes HYADES and CALE, and the supernova code PROMETHEUS, thus serving as a benchmark for PROMETHEUS. Results of the experiments and simulations are presented. Analysis of the spike and bubble velocities in the experiment using potential flow theory and a modified Ott thin shell theory is presented. A numerical study of 2D vs. 3D differences in instability growth at the O-He and He-H interface of SN 1987A, and the design for analogous laser experiments are presented. We discuss further work to incorporate more features of the SN in the experiments, including spherical geometry, multiple layers and density gradients. Past and ongoing work in laboratory and laser astrophysics is reviewed, including experimental work on supernova remnants (SNRs). A numerical study of RM instability in SNRs is presented.

  8. Topological crystalline insulator SnTe nanoribbons

    NASA Astrophysics Data System (ADS)

    Dahal, Bishnu R.; Dulal, Rajendra P.; Pegg, Ian L.; Philip, John

    2017-03-01

    Topological crystalline insulators are systems in which a band inversion that is protected by crystalline mirror symmetry gives rise to nontrivial topological surface states. SnTe is a topological crystalline insulator. It exhibits p-type conductivity due to Sn vacancies and Te antisites, which leads to high carrier density in the bulk. Thus growth of high quality SnTe is a prerequisite for understanding the topological crystalline insulating behavior. We have grown SnTe nanoribbons using a solution method. The width of the SnTe ribbons varies from 500 nm to 2 μm. They exhibit rock salt crystal structure with a lattice parameter of 6.32 Å. The solution method that we have adapted uses low temperature, so the Sn vacancies can be controlled. The solution grown SnTe nanoribbons exhibit strong semiconducting behavior with an activation energy of 240 meV. This activation energy matches with the calculated band gap for SnTe with a lattice parameter of 6.32 Å, which is higher than that reported for bulk SnTe. The higher activation energy makes the thermal excitation of bulk charges very difficult on the surface. As a result, the topological surfaces will be free from the disturbance caused by the thermal excitations

  9. Correction to ATel 10128: Spectral Comparison Object SN 1999em -> SN 1999ee

    NASA Astrophysics Data System (ADS)

    Wang, Xiaofeng

    2017-02-01

    We report a correction to the spectroscopic classification announced in ATel #10128. The spectral comparison shows that SN 2017bke is similar to type Ia supernova SN 1999ee (which was incorrectly typed as SN 1999em) at t = -7 days from the maximum light. We apologize for any confusion caused by this typo error.

  10. Analysis of IUE Observations of Supernovae

    NASA Technical Reports Server (NTRS)

    Kirshner, Robert P.

    1996-01-01

    This program supported the analysis of IUE observations of supernovae. One aspect was a Target-of-Opportunity program to observe bright supernovae which was applied to SN 1993J in M81, and another was continuing analysis of the IUE data from SN 1987A. Because of its quick response time, the IUE satellite has continued to provide useful data on the ultraviolet spectra of supernovae. Even after the launch of the Hubble Space Telescope, which has much more powerful ultraviolet spectrometers, the IUE has enabled us to obtain early and frequent measurements of ultraviolet radiation: this information has been folded in with our HST data to create unique observations of supernova which can be interpreted to give powerful constraints on the physical properties of the exploding stars. Our chief result in the present grant period was the completion of a detailed reanalysis of the data on the circumstellar shell of SN 1987A. The presence of narrow high-temperature mission lines from nitrogen-rich gas close to SN 1987A has been the principal observational constraint on the evolution of the supernova's progenitor. Our new analysis shows that the onset of these lines, their rise to maximum, and their subsequent fading can be understood in the context of a model for the photoionization of circumstellar matter.

  11. Calorimetric studies of Cu-Li, Li-Sn, and Cu-Li-Sn.

    PubMed

    Fürtauer, S; Tserenjav, E; Yakymovych, A; Flandorfer, H

    2013-06-01

    Integral molar enthalpies of mixing were determined by drop calorimetry for Cu-Li-Sn at 1073 K along five sections xCu/xSn ≈ 1:1, xCu/xSn ≈ 2:3, xCu/xSn ≈ 1:4, xLi/xSn ≈ 1:1, and xLi/xSn ≈ 1:4. The integral and partial molar mixing enthalpies of Cu-Li and Li-Sn were measured at the same temperature, for Li-Sn in addition at 773 K. All binary data could be described by Redlich-Kister-polynomials. Cu-Li shows an endothermic mixing effect with a maximum in the integral molar mixing enthalpy of ∼5300 J · mol(-1) at xCu = 0.5, Li-Sn an exothermic minimum of ∼ -37,000 J · mol(-1) at xSn ∼ 0.2. For Li-Sn no significant temperature dependence between 773 K and 1073 K could be deduced. Our measured ternary data were fitted on the basis of an extended Redlich-Kister-Muggianu model for substitutional solutions. Additionally, a comparison of these results to the extrapolation model of Chou is given.

  12. GeSn/SiGeSn photonic devices for mid-infrared applications: experiments and calculations

    NASA Astrophysics Data System (ADS)

    Han, Genquan; Zhang, Qingfang; Liu, Yan; Zhang, Chunfu; Hao, Yue

    2016-11-01

    In this work, a fully strained GeSn photodetector with Sn atom percent of 8% is fabricated on Ge buffer on Si(001) substrate. The wavelength λ of light signals with obvious optical response for Ge0.92Sn0.08 photodetector is extended to 2 μm. The impacts of compressive strain introduced during the epitaxial growth of GeSn on Ge/Si are studied by simulation. Besides, the tensile strain engineering of GeSn photonic devices is also investigated. Lattice-matched GeSn/SiGeSn double heterostructure light emitting diodes (LEDs) with Si3N4 tensile liner stressor are designed to promote the further mid-infrared applications of GeSn photonic devices. With the releasing of the residual stress in Si3N4 liner, a large biaxial tensile strain is induced in GeSn active layer. Under biaxial tensile strain, the spontaneous emission rate rsp and internal quantum efficiency ηIQE for GeSn/SiGeSn LED are significantly improved.

  13. Band structure in 113Sn

    NASA Astrophysics Data System (ADS)

    Banerjee, P.; Ganguly, S.; Pradhan, M. K.; Sharma, H. P.; Muralithar, S.; Singh, R. P.; Bhowmik, R. K.

    2016-07-01

    The structure of collective bands in 113Sn, populated in the reaction 100Mo(19F,p 5 n ) at a beam energy of 105 MeV, has been studied. A new positive-parity sequence of eight states extending up to 7764.9 keV and spin (39 /2+) has been observed. The band is explained as arising from the coupling of the odd valence neutron in the g7 /2 or the d5 /2 orbital to the deformed 2p-2h proton configuration of the neighboring even-A Sn isotope. Lifetimes of six states up to an excitation energy of 9934.9 keV and spin 47 /2-belonging to a Δ I =2 intruder band have been measured for the first time, including an upper limit for the last state, from Doppler-shift-attenuation data. A moderate average quadrupole deformation β2=0.22 ±0.02 is deduced from these results for the five states up to spin 43 /2- . The transition quadrupole moments decrease with increase in rotational frequency, indicating a reduction of collectivity with spin, a feature common for terminating bands. The behavior of the kinematic and dynamic moments of inertia as a function of rotational frequency has been studied and total Routhian surface calculations have been performed in an attempt to obtain an insight into the nature of the states near termination.

  14. Gamma-producing radioactivities from supernovae

    NASA Astrophysics Data System (ADS)

    Woosley, S. E.; Pinto, Philip A.

    1988-09-01

    The production of three isotopes critical to astronomical γ-ray spectroscopy, 44Ti, 56Co, and 57Co, is briefly reviewed along with the information each contains. Emphasis is placed on SN 1987A, the only Type II supernova likely to be seen in γ-lines for decases to come. The 847 keV line from 56Co decay in this supernova should peak approximately 400 days after its explosion with a flux of about 1×10-3 cm-2 s-1. For comparison, the second best candidate, a Type Ia in the Virgo cluster (20 Mpc) gives a peak flux 100 times smaller than this 100 days after the explosion. 57Co decay in SN 1987A will also present a potentially detectable signal ~1×10-4 cm-2 s-1 in 1989 through 1991. 44Ti, chiefly from Type I supernovae, is a wild card, but may be responsible for the diffuse pair background.

  15. On relative supernova rates and nucleosynthesis roles

    NASA Technical Reports Server (NTRS)

    Arnett, W. David; Schramm, David N.; Truran, James W.

    1989-01-01

    It is shown that the Ni-56-Fe-56 observed in SN 1987A argues that core collapse supernovae may be responsible for more than 50 percent of the iron in the galaxy. Furthermore it is argued that the time averaged rate of thermonuclear driven Type I supernovae may be at least an order of magnitude lower than the average rate of core collapse supernovae. The present low rate of Type II supernovae (below their time averaged rate of approx. 1/10 yr) is either because the past rate was much higher because many core collapse supernovae are dim like SN 1987A. However, even in this latter case they are only an order of magnitude dimmer that normal Type II's due to the contribution of Ni-56 decay to the light curve.

  16. On relative supernova rates and nucleosynthesis roles

    NASA Technical Reports Server (NTRS)

    Arnett, W. David; Schramm, David N.; Truran, James W.

    1988-01-01

    It is shown that the Ni-56-Fe-56 observed in SN 1987A argues that core collapse supernovae may be responsible for more that 50 percent of the iron in the galaxy. Furthermore it is argued that the time averaged rate of thermonuclear driven Type I supernovae may be at least an order of magnitude lower than the average rate of core collapse supernovae. The present low rate of Type II supernovae (below their time averaged rate of approx. 1/10 yr) is either because the past rate was much higher because many core collapse supernovae are dim like SN 1987A. However, even in this latter case they are only an order of magnitude dimmer that normal Type II's due to the contribution of Ni-56 decay to the light curve.

  17. Plasmon annihilation into Kaluza-Klein gravitons: New astrophysical constraints on large extra dimensions?

    SciTech Connect

    Das, Prasanta Kumar; Satheeshkumar, V. H.; Suresh, P. K.

    2008-09-15

    In the large extra dimensional Kaluza-Klein (KK) scenario, where the usual standard model (SM) matter is confined to a 3+1-dimensional hypersurface called the 3-brane and gravity can propagate to the bulk (D=4+d, d being the number of extra spatial dimensions), the light graviton KK modes can be produced inside the supernova core due to the usual nucleon-nucleon bremstrahlung, electron-positron, and photon-photon annihilations. This photon inside the supernova becomes a plasmon due to the plasma effect. In this paper, we study the energy-loss rate of SN 1987A due to the KK gravitons produced from the plasmon-plasmon annihilation. We find that the SN 1987A cooling rate leads to the conservative bound M{sub D}>22.9 TeV and 1.38 TeV for the case of two and three spacelike extra dimensions.

  18. Electrodeposition of nanostructured Sn-Zn coatings

    NASA Astrophysics Data System (ADS)

    Salhi, Y.; Cherrouf, S.; Cherkaoui, M.; Abdelouahdi, K.

    2016-03-01

    The electrodeposition of Sn-Zn coating at ambient temperature was investigated. The bath consists of metal salts SnCl2·2H2O and ZnSO4·7H2O and sodium citrate (NaC6H5Na3O7·2H2O) as complexing agent. To prevent precipitation, the pH is fixed at 5. Reducing tin and zinc through Sncit2- and ZnHcit- complex respectively is confirmed by the presence of two cathodic peaks on the voltammogram. The kinetic of tin (II) reduction process is limited by the SnCit2- dissociation. The SEM and TEM observations have showed that the coating consists of a uniform Sn-Zn layer composed of fine grains on which tin aggregates grow up. XRD revealed peaks corresponding to the hexagonal Zn phase and the tetragonal β-Sn phase.

  19. SN2009ip at Very Late Times

    NASA Astrophysics Data System (ADS)

    Bigley, Andrew Christopher; Graham, Melissa Lynn

    2016-01-01

    The 2012 eruption of SN 2009ip resembled a Type IIn supernovae, dominated by emission from interaction of the ejecta with circumstellar material, but the question remains: was the 2012 outburst of SN 2009ip truly the terminal explosion of a massive star? We present time series photometric and spectroscopic data for the transient SN2009ip from 260 to 1026 days after the peak of its 2012 outburst. These data were collected at the Las Cumbres Observatory Global Telescope Network and Keck Observatory. We will show that SN 2009ip continues to decline linearly in brightness at very late epochs, analyze the evolution in flux and asymmetry of the Balmer emission lines, and investigate the geometry of the circumstellar material from the progenitor star system and the true nature of SN 2009ip.

  20. Synthesis of Epitaxial Films Based on Ge-Si-Sn Materials with Ge/GeSn, Ge/GeSiSn, and GeSn/GeSiSn Heterojunctions

    NASA Astrophysics Data System (ADS)

    Timofeev, V. A.; Kokhanenko, A. P.; Nikiforov, A. I.; Mashanov, V. I.; Tuktamyshev, A. R.; Loshkarev, I. D.

    2015-11-01

    Results of investigations into the synthesis of heterostructures based on Ge-Si-Sn materials by the method of low-temperature molecular beam epitaxy are presented. The formation of epitaxial films during structure growth has been controlled by the reflection high-energy electron diffraction method. Films with Ge/GeSn, Ge/GeSiSn, and GeSn/GeSiSn heterojunctions are grown with Sn content changing from 2 to 10 % at temperatures in the interval 150-350°C. The stressed state, the composition, and the lattice parameter are studied by the x-ray diffraction method using Omega-scan curves and reciprocal space maps. A tensile strain in the Ge film during Ge/Ge0.9Sn0.1/Si structure growth has reached 0.86%.

  1. Direct observation of Sn crystal growth during the lithiation and delithiation processes of SnO(2) nanowires.

    PubMed

    Zhang, Li Qiang; Liu, Xiao Hua; Perng, Ya-Chuan; Cho, Jea; Chang, Jane P; Mao, Scott X; Ye, Zhi Zhen; Huang, Jian Yu

    2012-11-01

    Tin (Sn) crystal growth on Sn-based anodes in lithium ion batteries is hazardous for reasons such as possible short-circuit failure by Sn whiskers and Sn-catalyzed electrolyte decomposition, but the growth mechanism of Sn crystals during battery cycling is not clear. Here we report different growth mechanisms of Sn crystal during the lithiation and delithiation processes of SnO(2) nanowires revealed by in situ transmission electron microscopy (TEM). Large spherical Sn nanoparticles with sizes of 20-200nm grew instantaneously upon lithiation of a single-crystalline SnO(2) nanowire at large current density (j>20A/cm(2)), which suppressed formation of the Li(x)Sn alloy but promoted agglomeration of Sn atoms. Control experiments of Joule-heating (j≈2400A/cm(2)) the pristine SnO(2) nanowires resulted in melting of the SnO(2) nanowires but not Sn particle growth, indicating that the abnormal Sn particle growth was induced by both chemical reduction (i.e., breaking the SnO(2) lattice to produce Sn atoms) and agglomeration of the Sn atoms assisted by Joule heating. Intriguingly, Sn crystals grew out of the nanowire surface via a different "squeeze-out" mechanism during delithiation of the lithiated SnO(2) nanowires coated with an ultra-thin solid electrolyte LiAlSiO(x) layer. It is attributed to the negative stress gradient generated by the fast Li extraction in the surface region through the Li(+)-conducting LiAlSiO(x) layer. Our previous studies showed that Sn precipitation does not occur in the carbon-coated SnO(2) nanowires, highlighting the effect of nanoengineering on tailoring the electrochemical reaction kinetics to suppress the hazardous Sn whiskers or nanoparticles formation in a lithium ion battery.

  2. More Supernova Surprises

    DTIC Science & Technology

    2010-09-24

    SEP 2010 2. REPORT TYPE 3. DATES COVERED 00-00-2010 to 00-00-2010 4. TITLE AND SUBTITLE More Supernova Surprises 5a. CONTRACT NUMBER 5b. GRANT...PERSPECTIVES More Supernova Surprises ASTRONOMY J. Martin Laming Spectroscopic observations of the supernova SN1987A are providing a new window into high...a core-collapse supernova ) have stretched and motivated research that has expanded our knowledge of astrophysics. The brightest such event in

  3. Growing Magnetic Fields in Central Compact Objects

    NASA Astrophysics Data System (ADS)

    Bernal, C. G.; Page, D.

    2011-10-01

    We study the effects of growth models of magnetic fields in Central Compact Objects (CCOs). Such a field evolution is not a new idea (Blandford, Applegate, & Hernquist 1983) but the evolutionary implications not have been followed up completely (Michel 1994). We discussed the new class of neutron stars which belong to five main types that have mainly been recognized in the last ten years. The possibility that a rapid weakly magnetized pulsar might have formed in SN1987A is commented.

  4. 1051 Ergs: The Evolution of Shell Supernova Remnants

    DTIC Science & Technology

    1997-11-15

    3 and that SNR 1987A will become a strong source in X-ray, optical, IR, UV , and radio. Gaensler showed the radio morphology already observed for SNR...study physical pro- cesses taking place in collisionless shocks. In particular, UV observations of SN 1006 indicate that only a small fraction of...phase shell-type emission, often in the same remnant. Dickel, in an overview, emphasized this by showing a gallery of multiwavelength SNR images

  5. An event observed by the Mont Blanc underground neutrino detector on February 23, 1987

    NASA Astrophysics Data System (ADS)

    Dadykin, V. L.; Zatsepin, G. T.; Korchaguin, V. B.; Korchaguin, P. V.; Malgin, A. S.; Ryazhskaya, O. G.; Ryassny, V. G.; Talochkin, V. P.; Khalchukov, F. F.; Yakushev, V. F.; Aglietta, M.; Badino, G.; Bologna, G.; Vernetto, S.; Galeotti, P.; Castagnoli, C.; Castellina, A.; Saavedra, O.; Trinchero, G.; Fulgione, W.

    1988-02-01

    An analysis is made of the event detected by the Soviet-Italian neutrino scintillation detector (LSD) beneath Mont Blanc on Februrary 23, 1987 at 2:52:37 UT. Corrected energies of the pulses of the event have been determined along with the probability of event imitiation by the background. The LSD data are compared with Kamiokande and IMB data. The possibility that the observed event may be connected with the explosion of SN 1987A is examined.

  6. Correlation between background events detected by the Mont Blanc neutrino detector and by the Baksan Neutrino Telescope on 23.02.1987.

    NASA Astrophysics Data System (ADS)

    Alexeyev, E. N.; Alexeyeva, L. N.; Klimenko, N. F.; Kogaj, I. M.; Krivosheina, I. V.; Poddubny, V. A.; Zakidyshev, V. N.

    The Mont Blanc and Baksan neutrino detector data were compared for the period 00:00 - 10:00 UT on 23 February 1987. During one hour (1:45 - 2:45 UT) a correlation between Mont Blanc events, which are mainly caused by natural radioactivity, and Baksan high energy cosmic ray muons has been found. This correlation can probably be associated with SN 1987A.

  7. High resolution gamma-ray astronomy - Observations and predictions of line shapes

    NASA Technical Reports Server (NTRS)

    Bhattacharya, Dipen; Gehrels, Neil

    1991-01-01

    The shapes of gamma-ray lines carry unique information about the physical processes and conditions in astrophysical sites. Galactic center and SN 1987A lines have been observationally resolved allowing their shapes to be studied. There are also significant new theoretical results concerning line shapes from Type I supernovae, supernova remnants and the interstellar medium. New work is presented on a simple treatment of line profiles for rotating disks and spherical shells.

  8. Dynamic viscosities of pure tin and Sn-Ag, Sn-Cu, and Sn-Ag-Cu eutectic melts

    NASA Astrophysics Data System (ADS)

    Rozhitsina, E. V.; Gruner, S.; Kaban, I.; Hoyer, W.; Sidorov, V. E.; Popel', P. S.

    2011-02-01

    The dynamic viscosities of the melts of pure tin and eutectic Sn-Ag, Sn-Cu, and Sn-Ag-Cu alloys are studied in heating followed by cooling, and the maximum heating temperature was 1200°C. An irreversible decrease in the viscosity is found in the temperature range 800-1000°C in the polytherms of all melts. This finding is related to the loss of a local order in a melt and can be used to develop temperature regimes for the production of lead-free solders.

  9. 119Sn Mössbauer studies on ferromagnetic and photocatalytic Sn-TiO2 nanocrystals

    NASA Astrophysics Data System (ADS)

    Ganeshraja, Ayyakannu Sundaram; Nomura, Kiyoshi; Wang, Junhu

    2016-12-01

    Diluted Sn doped TiO2 nanocrystals (Sn/Ti ratio: x ≤ 1.37 %) were synthesized by a simple hydrothermal method using pure reagents without any surfactant and dispersant material. The XRD of these samples showed an anatase phase, anatase and rutile mixed phases, and a rutile phase of TiO2 and SnO2 with the increase of Sn dopant concentrations. 119Sn Mössbauer spectra gave the broad peaks, which were decomposed into doublets and sextets because almost all these samples showed magnetic hysteresis even at room temperature. The titanium oxides doped with x ≤ 0.12 % showed the relatively large magnetic hysteresis and high photocatalytic activity. Mössbauer spectra of samples doped with x > 0.3 % were analyzed by one doublet and two sextets although the samples showed weak ferromagnetism. Three kinds of Sn species may be distinguished as Sn 4+ substituted TiO2 and two different magnetic arrangements of Sn doped TiO2: one with more oxygen defects and other at the interface of TiO2 and precipitated SnO2 containing Ti atoms. The correlation between various amounts of Sn sites and photocatalytic activity and/ or magnetic property was discussed.

  10. Temperature dependence of the quadrupole interaction of69Ge Tl and113Sn Sn

    NASA Astrophysics Data System (ADS)

    Semmler, W.; Raghavan, P.; Senba, M.; Raghavan, R. S.

    1981-03-01

    The quadrupole interaction constants of69Ge T1 and113Sn Sn were measured by means of the perturbed angular distribution technique as a function of temperature in the range of 80K≦T≦508 K and 80K≦T≦480 K, respectively. Isomeric states in69Ge and113Sn were populated by the heavy ion reactions56Fe(16O, 2 p n) and100Mo(16O, 3 n) and recoil implanted into polycrystalline Tl- and single crystalline Sn-backings. In the case of113Sn Sn, where the quadrupole coupling is weak, a special single crystal geometry was employed to enhance the sensitivity of the measurement. Within the limits of the errors the temperature dependence for both systems follows the empirical T1.5-dependence. While a strong temperature dependence comparable to In In is observed for69Ge T1, that for113Sn Sn is weaker than expected. The strength of the temperature dependence for113Sn Sn does not agree with the predictions of a lattice vibration model proposed recently for the temperature dependence of the quadrupole interaction.

  11. SN candidate in NGC 3106

    NASA Astrophysics Data System (ADS)

    Drake, A. J.; Djorgovski, S. G.; Mahabal, A. A.; Graham, M. J.; Williams, R.; Catelan, M.; Beshore, E. C.; Larson, S. M.; Gibbs, A.; Christensen, E.

    2009-06-01

    We report the discovery of a SN candidate found by the Catalina Real-time Transient Survey (CRTS) in NGC 3106.

    IDDateRADecMagMag hostz host
    CSS090625:100407+311229 2009-06-25 UT 04:03:46 10:04:06.78 31:12:29.0 16.1 12.7 0.021
    For finding charts, discovery images, lightcurves, etc., please see: http://voeventnet.cacr.caltech.edu/feeds/ATEL/CRTS.

  12. Comparison of Catabolic Rates of sn-1, sn-2, and sn-3 Fatty Acids in Triacylglycerols Using (13)CO2 Breath Test in Mice.

    PubMed

    Beppu, Fumiaki; Kawamatsu, Takashi; Yamatani, Yoshio; Nagai, Toshiharu; Yoshinaga, Kazuaki; Mizobe, Hoyo; Yoshida, Akihiko; Kubo, Atsushi; Kanda, Jota; Gotoh, Naohiro

    2017-01-01

    Fatty acids in triacylglycerols (TAGs) are catabolized after digestion. However, the catabolic rates of the fatty acids at the sn-1, sn-2, and sn-3 positions of TAGs have not been compared. To elucidate the differences, we studied the catabolic rates of (13)C-labeled palmitic acid, oleic acid, and capric acid at the sn-1, sn-2, or sn-3 position of TAGs using isotope-ratio mass spectrometry. Specifically, we measured the (13)C-to-(12)C ratio in CO2 (Δ(13)C (‰)) exhaled by mice. For all analyzed fatty acids, we observed significant differences between sn-2 and other binding positions. In contrast, no significant difference was detected between the sn-1 and sn-3 positions. These results indicated that the catabolic rates of fatty acids are strongly influenced by their positions in TAGs.

  13. Sn Attenuation in the Middle-East

    NASA Astrophysics Data System (ADS)

    Ku, W.; Kaviani, A.; Bao, X.; Sandvol, E. A.

    2015-12-01

    The Turkish-Iranian Plateau and Zagros Mountains, a dominant tectonic feature in the Middle-East, were formed as a result of the continental collision (between Arabian plate and Eurasia plates). In order to better understand the nature of the lithosphere mantle and origin of the measure seismic velocity anomalies we have made detailed measurements of the uppermost mantle attenuation using the high frequency regional phase Sn. In order to measure Sn attenuation. We have collected a large data set consisting of 18 years (1995-2012) of waveforms recorded by 305 permanent and temporary stations. We used a bandpass filter (0.1-0.5Hz) to identify efficient longer period Sn phases. In order to determine Sn Q we applied a Two Station Method (TSM) and Reverse Two Station Method (RTM) to eliminate the source effects. We have used the LSQR algorithm to tomographically map Sn attenuation tomography across the Middle-East. We also determined the Sn propagation efficiencies visually and tomographically map qualitatively assigned Sn propagation efficiencies across the Middle-East. The Sn Attenuation Tomography show moderately low Q values beneath the Turkish-Iranian Plateau (~250) and high Q values beneath the south Caspian sea (~400) and Arabian shield (~400). We also observe high Q values beneath the Zagros mountains (~450) that is consistent with the Arabian plate underthrusting beneath the Eurasia plate. The Sn Efficiency Tomography shows high attenuation within the Turkish-Iranian Plateau and low attenuation in the Arabian Plate and across the Caspian Sea. This is consistent with prior studies that suggest a hot and thin lithosphere beneath the Turkish-Iranian Plateau and it also suggests that intrinsic attenuation is the dominant component in Sn Q across the Turkish-Iranian Plateau. Due to the signal-to-noise criterion to select amplitudes and the efficiency criterion to select two-station and reverse-two-station paths for the inversion, the data are left-censored and the

  14. JVLA observations of SN2013bv

    NASA Astrophysics Data System (ADS)

    Kamble, Atish; Soderberg, Alicia

    2013-05-01

    We report radio observations with the Jansky Very Large Array of the Type Ic supernova SN2013bv discovered by Zhang et al.(CBET #3499) on April 9.51 UT and spectroscopically classified as broad-lined supernova similar to SN1998bw by Silverman et al. (CBET #3499). On 2013 April 27.0 UT, we triggered VLA observations at the position of SN2013bv at 4.8 & 7.1 GHz. No radio emission is detected in either of the frequency bands at the position of the supernova down to 3-sigma RMS level of 7 microJy.

  15. Type Determination for SN 2005ea

    NASA Astrophysics Data System (ADS)

    Gal-Yam, A.; Leonard, D. C.

    2005-10-01

    A. Gal-Yam and D. Leonard report for the CCCP: We have observed SN 2005ea (Gray and Lane; IAUC #8600) with the DBSP spectrograph mounted on the Hale 200" telescope at Palomar Observatory on 2005 October 25 UT, under poor conditions. Reduction of the noisy red spectrum shows it is similar to that of SN Ia 1994D around 30 days after maximum light (Filippenko 1997, ARA&A, 35, 309). We therefore tentatively identify this event as a type Ia SN.

  16. Long-rising Type II supernovae from Palomar Transient Factory and Caltech Core-Collapse Project

    NASA Astrophysics Data System (ADS)

    Taddia, F.; Sollerman, J.; Fremling, C.; Migotto, K.; Gal-Yam, A.; Armen, S.; Duggan, G.; Ergon, M.; Filippenko, A. V.; Fransson, C.; Hosseinzadeh, G.; Kasliwal, M. M.; Laher, R. R.; Leloudas, G.; Leonard, D. C.; Lunnan, R.; Masci, F. J.; Moon, D.-S.; Silverman, J. M.; Wozniak, P. R.

    2016-04-01

    Context. Supernova (SN) 1987A was a peculiar hydrogen-rich event with a long-rising (~84 d) light curve, stemming from the explosion of a compact blue supergiant star. Only a few similar events have been presented in the literature in recent decades. Aims: We present new data for a sample of six long-rising Type II SNe (SNe II), three of which were discovered and observed by the Palomar Transient Factory (PTF) and three observed by the Caltech Core-Collapse Project (CCCP). Our aim is to enlarge this small family of long-rising SNe II, characterizing their differences in terms of progenitor and explosion parameters. We also study the metallicity of their environments. Methods: Optical light curves, spectra, and host-galaxy properties of these SNe are presented and analyzed. Detailed comparisons with known SN 1987A-like events in the literature are shown, with particular emphasis on the absolute magnitudes, colors, expansion velocities, and host-galaxy metallicities. Bolometric properties are derived from the multiband light curves. By modeling the early-time emission with scaling relations derived from the SuperNova Explosion Code (SNEC) models of MESA progenitor stars, we estimate the progenitor radii of these transients. The modeling of the bolometric light curves also allows us to estimate other progenitor and explosion parameters, such as the ejected 56Ni mass, the explosion energy, and the ejecta mass. Results: We present PTF12kso, a long-rising SN II that is estimated to have the largest amount of ejected 56Ni mass measured for this class. PTF09gpn and PTF12kso are found at the lowest host metallicities observed for this SN group. The variety of early light-curve luminosities depends on the wide range of progenitor radii of these SNe, from a few tens of R⊙ (SN 2005ci) up to thousands (SN 2004ek) with some intermediate cases between 100 R⊙ (PTF09gpn) and 300 R⊙ (SN 2004em). Conclusions: We confirm that long-rising SNe II with light-curve shapes closely

  17. 119 Sn NMR studies on the heavy fermion compound CeSn3

    NASA Astrophysics Data System (ADS)

    Crocker, John; Kim, Andrew; Klavins, Peter; Curro, Nicholas

    2015-03-01

    CeSn3 does not exhibit long-range order at low temperatures, thus it provides an interesting baseline for NMR studies of the Knight shift. We report the synthesis and characterization of single crystals of CeSn3, as well as 119Sn nuclear magnetic resonance (NMR) measurements from 4.5K to room temperature. Our data reveal a broad peak in the knight shift (K) at Tmax ~ 135K, and a knight shift anomaly at T* ~ 85K.

  18. Host Galaxy Spectra of Stripped SN from the Palomar Transient Factory: SN Progenitor Diagnostics and the SN-GRB Connection

    NASA Astrophysics Data System (ADS)

    Modjaz, Maryam; Gal-Yam, Avishay; Arcavi, Iair

    2012-02-01

    Stripped core-collapse supernovae (Stripped SNe) are powerful cosmic engines that energize and enrich the ISM and that sometimes accompany GRBs, but the exact mass and metallicity range of their massive progenitors is not known, nor the detailed physics of the explosion. We propose to continue conducting the first uniform and statistically significant study of host galaxies of 60 stripped SNe from the same innovative, homogeneous and galaxy-unbiased survey Palomar Transient Factory in order to determine the environmental conditions that influence the various kinds of massive stellar deaths. By obtaining spectra of the immediate host environments of our sample of stripped SN, we will (1) measure local abundances in order to differentiate between the two progenitor scenarios for stripped SN and (2) derive stellar population ages, masses and star formation histories via detailed stellar population synthesis models. Moreover, we will test if natal chemical abundance has effects on basic SN characteristics, such as peak luminosity. Any observed trends will have ramifications on SN and GRB explosion models and imply important demographic SN considerations. Our dataset will provide a crucial complimentary set to host galaxy studies of long-duration GRBs and pave the way for host studies of transients and SN found via upcoming surveys such as LSST.

  19. EBSD Investigation of Cu-Sn IMC Microstructural Evolution in Cu/Sn-Ag/Cu Microbumps During Isothermal Annealing

    NASA Astrophysics Data System (ADS)

    Wang, S. J.; Hsu, L. H.; Wang, N. K.; Ho, C. E.

    2014-01-01

    The microstructural evolution of Cu/Sn-Ag (~5 μm)/Cu Cu-bump-on-line (CuBOL) joints during isothermal annealing at 180°C was examined using a field-emission scanning electron microscope equipped with an electron backscatter diffraction (EBSD) system. Cu6Sn5 and Cu3Sn were the two key intermetallic compound (IMC) species that appeared in the CuBOL joints. After annealing for 24 h (= t), the solder had completely converted to Cu-Sn IMCs, forming an "IMC" joint with Cu/Cu3Sn/Cu6Sn5/Cu3Sn/Cu structure. EBSD analyses indicated that the preferred orientation of the hexagonal Cu6Sn5 (η) was , while the preferred orientation was (100) for the monoclinic Cu6Sn5 structure (η'). Upon increasing t to 72 h, Cu6Sn5 entirely transformed into Cu3Sn, and the IMC joint became Cu/Cu3Sn/Cu accordingly. Interestingly, the grain size and crystallographic orientation of Cu3Sn displayed location dependence. Detailed EBSD analyses in combination with transmission electron microscopy on Cu3Sn were performed in the present study. This research offers better understanding of crystallographic details, including crystal structure, grain size, and orientation, for Cu6Sn5 and Cu3Sn in CuBOL joints after various annealing times.

  20. Electrochemical properties of Ti-Ni-Sn materials predicted by 119Sn Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Ladam, A.; Aldon, L.; Lippens, P.-E.; Olivier-Fourcade, J.; Jumas, J.-C.; Cenac-Morthe, C.

    2016-12-01

    The electrochemical activity of TiNiSn, TiNi 2Sn and Ti 6Sn 5 compounds considered as negative electrode materials for Li-ion batteries has been predicted from the isomer shift- Hume-Rothery electronic density correlation diagram. The ternary compounds were obtained from solid-state reactions and Ti 6Sn 5 by ball milling. The 119Sn Mössbauer parameters were experimentally determined and used to evaluate the Hume-Rothery electronic density [e av]. The values of [e av] are in the region of Li-rich Li-Sn alloys for Ti 6Sn 5 and outside this region for the ternary compounds, suggesting that the former compound is electrochemically active but not the two latter ones. Electrochemical tests were performed for these different materials confirming this prediction. The close values of [e av] for Ti 6Sn 5 and Li-rich Li-Sn alloys indicate that the observed good capacity retention could be related to small changes in the global structures during cycling.

  1. Transparent Conducting Properties of SrSnO3 and ZnSnO3

    DOE PAGES

    Ong, Khuong P.; Fan, Xiaofeng; Subedi, Alaska; ...

    2015-04-29

    We report optical properties of doped n-type SrSnO3 and ZnSnO3 in relation to potential application as transparent conductors. We find that the orthorhombic distortion of the perovskite structure in SrSnO3 leads to absorption in the visible as the doping level is increased. This arises from interband transitions. We find that strain tuning could modify this absorption, but does not eliminate it. On the other hand, we find that ZnSnO3 although also having a non-cubic structure, can retain excellent transparency when doped, making it a good candidate transparent conductor.

  2. Effect of Sn addition on the microstructure and superelasticity in Ti-Nb-Mo-Sn alloys.

    PubMed

    Zhang, D C; Yang, S; Wei, M; Mao, Y F; Tan, C G; Lin, J G

    2012-09-01

    Ti-7.5Nb-4Mo-xSn (x=0-4at%) alloys were developed as the biomedical materials. The effect of the Sn content on the microstructure and superelasticity of the alloys was investigated. It is found that Sn is a strong stabilizer of the β phase, which is effective in suppressing the formation of α″ and ω phases in the alloys. Moreover, the Sn addition has a significant impact on the mechanical properties of the alloys. With the increase of Sn addition, the yield stress of the alloys increase, but their elastic modulus, the fracture strength and the ductility decrease, and the deformation mode of the alloys changes from (322) twining to α″ transformation and then to slip. The Ti-7.5Nb-4Mo-1Sn and Ti-7.5Nb-4Mo-3Sn alloys exhibit a good superelasticity with a high σ(SIM) due to the relatively high athermal ω phases containing or the solution hardening at room temperature. Under the maximum strain of 5%, Ti-7.5Nb-4Mo-3Sn (at%) alloy exhibits higher super elastic stability than that of Ti-7.5Nb-4Mo-1Sn alloy.

  3. The Material Properties of CsSnBr3 and CsBr:Sn-1% and Their Potential as Scintillator Detector Material

    DTIC Science & Technology

    2010-03-01

    to be in the 4+ state. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 45. The SnO XANES shows the shift of the Sn in CsSnBr3... SnO +2, SnO2 4+ were used to perform this analysis due to their known oxidation states. The analysis shows the Sn within the CsBr:Sn-1% to be in a 4...character- ized truth samples are available. Along with SnO2 and SnO powder samples, an Sn powder sample was also used. The Sn was used as a practice

  4. Anomalous creep in Sn-rich solder joints

    SciTech Connect

    Song, Ho Geon; Morris Jr., John W.; Hua, Fay

    2002-03-15

    This paper discusses the creep behavior of example Sn-rich solders that have become candidates for use in Pb-free solder joints. The specific solders discussed are Sn-3.5Ag, Sn-3Ag-0.5Cu, Sn-0.7Cu and Sn-10In-3.1Ag, used in thin joints between Cu and Ni-Au metallized pads.

  5. Aperiodic SiSn/Si multilayers for thermoelectric applications

    NASA Astrophysics Data System (ADS)

    Tonkikh, A. A.; Zakharov, N. D.; Eisenschmidt, C.; Leipner, H. S.; Werner, P.

    2014-04-01

    We report on novel defect-free SiSn/Si heterostructures grown pseudomorphically on Si(001) substrates using temperature-modulated molecular beam epitaxy. This approach results in a sustainable epitaxial growth for SiSn/Si multilayers. Transmission electron microscopy and electron diffraction manifest that SiSn layers possess a diamond lattice structure. X-ray diffraction reveals up to 9.5 at% Sn in the crystal lattice of SiSn layers.

  6. Asiago spectroscopic classification of SN2017awk.

    NASA Astrophysics Data System (ADS)

    Tomasella, L.; Benetti, S.; Cappellaro, E.; Elias-Rosa, N.; Ochner; Pastorello, P.; Turatto, M.; Terreran, G

    2017-02-01

    The Asiago Transient Classification Program (Tomasella et al. 2014, AN, 335, 841) reports the spectroscopic observation of ASASSN-17co The target was supplied by All Sky Automated Survey for SuperNovae (ASAS-SN).

  7. Magnetic Moments of States in 110Sn.

    NASA Astrophysics Data System (ADS)

    Kumbartzki, G. J.

    2016-06-01

    The semi-magic Sn isotopes with Z = 50 are the subject of extensive experimental and theoretical studies. The measured B(E2) values to the 21 + states for the neutron-deficient side of the isotope chain suggest enhanced collectivity when fewer particles are available if the proton shell is not broken. Magnetic moments which are sensitive to proton and neutron contributions to the wave functions of the states could provide critical and relevant information. Magnetic moments were previously measured only for the even stable and a few neutron-rich unstable Sn isotopes. A measurement of the g factors of excited states in 110Sn using the transient field technique was performed at the 88-Inch Cyclotron at the LBNL in Berkeley. The 110Sn nuclei were produced via an α-particle transfer to 106Cd.

  8. Nb3Sn for Radio Frequency Cavities

    SciTech Connect

    Godeke, A.

    2006-12-18

    In this article, the suitability of Nb3Sn to improve theperformance of superconducting Radio-Frequency (RF)cavities is discussed.The use of Nb3Sn in RF cavitiesis recognized as an enabling technology toretain a veryhigh cavity quality factor (Q0) at 4.2 K and tosignificantly improve the cavity accelerating efficiency per unitlength(Eacc). This potential arises through the fundamental properties ofNb3Sn. The properties that are extensively characterized in theliterature are, however, mainly related to improvements in currentcarrying capacity (Jc) in the vortex state. Much less is available forthe Meissner state, which is of key importance to cavities. Relevantdata, available for the Meissner state is summarized, and it is shown howthis already validates the use of Nb3Sn. In addition, missing knowledgeis highlighted and suggestions are given for further Meissner statespecific research.

  9. SN 1054: A pulsar-powered supernova?

    NASA Astrophysics Data System (ADS)

    Li, Shao-Ze; Yu, Yun-Wei; Huang, Yan

    2015-11-01

    The famous ancient supernova SN 1054 could have been too bright to be explained in the “standard” radioactive-powered supernova scenario. As an alternative attempt, we demonstrate that the spin-down of the newly born Crab pulsar could provide a sufficient energy supply to make SN 1054 visible at daytime for 23 days and at night for 653 days, where a one-zone semi-analytical model is employed. Our results indicate that SN 1054 could be a “normal” cousin of magnetar-powered superluminous supernovae. Therefore, SN 1054-like supernovae could be a probe to uncover the properties of newly born neutron stars, which provide initial conditions for studies on neutron star evolutions.

  10. Asiago spectroscopic classification of SN2017mf

    NASA Astrophysics Data System (ADS)

    Ochner, P.; Benetti, S.; Tomasella, L.; Cappellaro, E.; Elias-Rosa, N.; Pastorello, P.; Turatto, M.; Terreran, G

    2017-01-01

    The Asiago Transient Classification Program (Tomasella et al. 2014, AN, 335, 841) reports the spectroscopic observation of SN2017mf. The observation was performed with the Asiago 1.22-m Galileo Telescope (+ Boller & Chivens spectrograph).

  11. Optical properties of {beta}-Sn films

    SciTech Connect

    Takeuchi, Katsuki; Adachi, Sadao

    2009-04-01

    Optical properties of white tin ({beta}-Sn) have been investigated using spectroscopic ellipsometry in the photon-energy range between 0.6 and 6.5 eV at room temperature. The {beta}-Sn films are deposited by vacuum evaporation on Si(001) substrates. The structural properties of the films are evaluated by x-ray diffraction and ex situ atomic force microscopy. The measured {epsilon}(E) spectra reveal distinct structures at several interband critical points in the Brillouin zone of {beta}-Sn. These spectra are analyzed on the basis of a simplified model of the interband transitions, including the free-carrier absorption between the filled and empty electronic states. Dielectric-related optical constants, such as the complex refractive index, absorption coefficient, and normal-incidence reflectivity, of bulk {beta}-Sn films are also presented.

  12. Investigation of Sn Whisker Growth in Electroplated Sn and Sn-Ag as a Function of Plating Variables and Storage Conditions

    NASA Astrophysics Data System (ADS)

    Chang, Jaewon; Kang, Sung K.; Lee, Jae-Ho; Kim, Keun-Soo; Lee, Hyuck Mo

    2014-01-01

    Sn whiskers are becoming a serious reliability issue in Pb-free electronic packaging applications. Among the numerous Sn whisker mitigation strategies, minor alloying additions to Sn have been proven effective. In this study, several commercial Sn and Sn-Ag baths of low-whisker formulations are evaluated to develop optimum mitigation strategies for electroplated Sn and Sn-Ag. The effects of plating variables and storage conditions, including plating thickness and current density, on Sn whisker growth are investigated for matte Sn, matte Sn-Ag, and bright Sn-Ag electroplated on a Si substrate. Two different storage conditions are applied: an ambient condition (30°C, dry air) and a high-temperature/high-humidity condition (55°C, 85% relative humidity). Scanning electron microscopy is employed to record the Sn whisker growth history of each sample up to 4000 h. Transmission electron microscopy, x-ray diffraction, and focused ion beam techniques are used to understand the microstructure, the formation of intermetallic compounds (IMCs), oxidation, the Sn whisker growth mechanism, and other features. In this study, it is found that whiskers are observed only under ambient conditions for both thin and thick samples regardless of the current density variations for matte Sn. However, whiskers are not observed on Sn-Ag-plated surfaces due to the equiaxed grains and fine Ag3Sn IMCs located at grain boundaries. In addition, Sn whiskers can be suppressed under the high-temperature/high-humidity conditions due to the random growth of IMCs and the formation of thick oxide layers.

  13. The system SnTe-InSe

    SciTech Connect

    Gurshumov, A.P.; Alidzhanov, M.A.; Aliev, A.S.; Gadzhiev, T.G.; Mamedov, N.A.

    1986-03-01

    This paper discusses the nature of the interaction and physicochemical properties of the alloys of the system SnTe-InSe. The DTA was performed on an NTR-74 pyrometer, XPA on a Dron-2.0 diffractometer and MSA on an MIM-7 metallographic microscope. The microhardness of the samples was determined on a PMT-3 microhardness tester. The congruently melting compound SnInTeSe and solid solutions based on the starting components are formed in the system.

  14. Particle-hole states in Sn 120

    NASA Technical Reports Server (NTRS)

    Leonard, R. F.

    1972-01-01

    The 45 MeV deuteron beam from the Berkeley 88-inch cyclotron was used to study the particle-hole states in Sn-120. The present work resolved a number of individual levels and compared their strength and excitation energy with that observed in the Sn-120(d, He-3) reaction, which was also remeasured. A schematic diagram of the scattering system is given along with a description.

  15. Raman spectral shift versus strain and composition in GeSn layers with 6%-15% Sn content

    NASA Astrophysics Data System (ADS)

    Gassenq, A.; Milord, L.; Aubin, J.; Pauc, N.; Guilloy, K.; Rothman, J.; Rouchon, D.; Chelnokov, A.; Hartmann, J. M.; Reboud, V.; Calvo, V.

    2017-03-01

    GeSn alloys are the subject of intense research activities as these group IV semiconductors present direct bandgap behaviors for high Sn contents. Today, the control of strain becomes an important challenge to improve GeSn devices. Strain micro-measurements are usually performed by Raman spectroscopy. However, different relationships linking the Raman spectral shifts to the built-in strain can be found in the literature. They were deduced from studies on low Sn content GeSn layers (i.e., xSn < 8%) or on GeSiSn layers. In this work, we have calibrated the GeSn Raman relationship for really high Sn content GeSn binaries (6 < xSn < 15%). We have used fully strained GeSn layers and fully relaxed GeSn under-etched microstructures to clearly differentiate the contributions of strain and chemical composition on the Ge-Ge Raman spectral shift. We have shown that the GeSn Raman-strain coefficient for high Sn contents is higher compared with that for pure Ge.

  16. Diffusivities and Atomic Mobilities of Sn-Ag and Sn-In Melts

    NASA Astrophysics Data System (ADS)

    Chen, Wei-Min; Zhang, Li-Jun; Du, Yong; Huang, Bai-Yun

    2014-04-01

    The recently developed Arrhenius formula for the modified Sutherland equation was employed to calculate the self- and impurity diffusivities in liquid Sn, Ag, and In. The reliability of the calculated self- and impurity diffusivities was validated by comparing the presently calculated results with critically reviewed literature data. Based on reliable tracer and chemical diffusivities available in literature, the atomic mobility parameters in Sn-Ag and Sn-In melts were then evaluated with the aid of the available thermodynamic description for the liquid phase. Comprehensive comparisons showed that most of the measured and theoretical diffusivities in Sn-Ag and Sn-In melts can be reasonably reproduced by the currently obtained atomic mobilities. Moreover, the atomic mobilities were further verified by comparing the model-predicted concentration profiles with the measured ones in various liquid Sn-In diffusion couples. In addition, a simulation of Ag dissolution into liquid Sn-Ag solder during a reflow process was performed via the presently obtained atomic mobilities in the Sn-Ag melt.

  17. Formation of SnO2 Nanowires Using Thermal Evaporation of SnO.

    PubMed

    Lin, Yu-Yun; Lin, Che-Yu; Chen, Ching-Yi; Li, Yuan-Yao

    2015-12-01

    SnO2 nanowires (NWs) were grown on a catalyst-coated silicon wafer via the thermal evaporation of SnO powder at 20-30 mTorr. Three types of catalyst, namely Fe, Pt, and Au, were used for the synthesis of the SnO2 NWs. The results show that Pt and Au can be used for the formation of SnO2 NWs. Depending on the experimental conditions, the diameter and length of the SnO2 NWs obtained with Au catalyst are in the ranges of 20-65 nm and a few hundred nanometers to a few micrometers, respectively. The size of the Au nanocatalyst greatly affects the diameter of the SnO2 NWs. With increasing particle size of the Au catalyst, the diameter of the SnO2 NWs increased. In addition, the results show that the synthesis of SnO2 NWs can be conducted at 500 degrees C, which is compatible with low-temperature processes.

  18. STRUCTURE AND HIGH-FIELD PERFORMANCE OF JELLY ROLL PROCESSED Nb{sub 3}Sn WIRES USING Sn-Ta AND Sn-Ti BASED ALLOY SHEET

    SciTech Connect

    Tachikawa, K.; Tsuyuki, T.; Hayashi, Y.; Nakata, K.; Takeuchi, T.

    2008-03-03

    Sn-Ta based alloy buttons of different compositions were prepared by the melt diffusion process among constituent metal powders, and then pressed into plates. Meanwhile Sn-Ti based alloy plates were sliced from the melt and cast ingot. Resulting Sn-based alloy plates were rolled into thin sheets. The Sn-based alloy sheet was laminated with a Nb sheet, and wound into a Jelly Roll (JR) composite. The composite was encased in a sheath, and fabricated into a thin wire followed by the heat treatment. The application of hydrostatic extrusion is useful at the initial stage of the fabrication. The JR wires using Sn-Ta and Sn-Ti based alloy sheets show a non-Cu J{sub c} of {approx}250 A/mm{sup 2} and {approx}150 A/mm{sup 2} at 20 T and 22 T, respectively, at 4.2 K. It has been found that the Nb impregnates into the Sn-based alloy layers during the reaction, and Nb{sub 3}Sn layers are synthesized by the mutual diffusion between the Nb sheet and the Sn-based alloy sheet without formation of voids. Sn-Ti based alloy sheets are attractive due to their easiness of mass production. Structure and high-field performance of JR processed Nb{sub 3}Sn wires prepared from Sn-based alloy sheets with different compositions are compared in this article.

  19. Chemistry, growth kinetics, and epitaxial stabilization of Sn2+ in Sn-doped SrTiO3 using (CH3)6Sn2 tin precursor

    NASA Astrophysics Data System (ADS)

    Wang, Tianqi; Pitike, Krishna Chaitanya; Yuan, Yakun; Nakhmanson, Serge M.; Gopalan, Venkatraman; Jalan, Bharat

    2016-12-01

    PbTiO3-based ferroelectrics have impressive electroactive properties, originating from the Pb2+ 6s2 electron lone-pair, which cause large elastic distortion and electric polarization due to cooperative pseudo Jahn-Teller effect. Recently, tin-based perovskite oxide (SnTiO3) containing Sn2+ and a chemistry similar to that of the 6s2 lone-pair has been identified as a thermally stable, environmentally friendly substitute for PbTiO3-based ferroelectrics. However experimental attempts to stabilize Sn2+ on the A-site of perovskite ATiO3 have so far failed. In this work, we report on the growth of atomically smooth, epitaxial, and coherent Sn-alloyed SrTiO3 films on SrTiO3 (001) substrates using a hybrid molecular beam epitaxy approach. With increasing Sn concentration, the out-of-plane lattice parameter first increases in accordance with the Vegard's law and then decreases for Sn(Sr+Ti+Sn/) at. % ratio > 0.1 due to the incorporation of Sn2+ at the A-site. Using a combination of high-resolution X-ray photoelectron spectroscopy and density functional calculations, we show that while majority of Sn is on the B-site, there is a quantitatively unknown fraction of Sn being consistent with the A-site occupancy making SrTiO3 polar. A relaxor-like ferroelectric local distortion with monoclinic symmetry, induced by A-site Sn2+, was observed in Sn-doped SrTiO3 with Sn(Sr+Ti+Sn/) at. % ratio = 0.1 using optical second harmonic generation measurements. The role of growth kinetics on the stability of Sn2+ in SrTiO3 is discussed.

  20. Ferromagnetism of Fe3Sn and Alloys

    PubMed Central

    Sales, Brian C.; Saparov, Bayrammurad; McGuire, Michael A.; Singh, David J.; Parker, David S.

    2014-01-01

    Hexagonal Fe3Sn has many of the desirable properties for a new permanent magnet phase with a Curie temperature of 725 K, a saturation moment of 1.18 MA/m. and anisotropy energy, K1 of 1.8 MJ/m3. However, contrary to earlier experimental reports, we found both experimentally and theoretically that the easy magnetic axis lies in the hexagonal plane, which is undesirable for a permanent magnet material. One possibility for changing the easy axis direction is through alloying. We used first principles calculations to investigate the effect of elemental substitutions. The calculations showed that substitution on the Sn site has the potential to switch the easy axis direction. However, transition metal substitutions with Co or Mn do not have this effect. We attempted synthesis of a number of these alloys and found results in accord with the theoretical predictions for those that were formed. However, the alloys that could be readily made all showed an in-plane easy axis. The electronic structure of Fe3Sn is reported, as are some are magnetic and structural properties for the Fe3Sn2, and Fe5Sn3 compounds, which could be prepared as mm-sized single crystals. PMID:25387850

  1. Ferromagnetism of Fe3Sn and alloys

    DOE PAGES

    Sales, Brian C.; Saparov, Bayrammurad; McGuire, Michael A.; ...

    2014-11-12

    Hexagonal Fe3Sn has many of the desirable properties for a new permanent magnet phase with a Curie temperature of 725 K, a saturation moment of 1.18 MA/m. and anisotropy energy, K1 of 1.8 MJ/m3. However, contrary to earlier experimental reports, we found both experimentally and theoretically that the easy magnetic axis lies in the hexagonal plane, which is undesirable for a permanent magnet material. One possibility for changing the easy axis direction is through alloying. We used first principles calculations to investigate the effect of elemental substitutions. The calculations showed that substitution on the Sn site has the potential tomore » switch the easy axis direction. Transition metal substitutions with Co or Mn do not have this effect. We attempted synthesis of a number of these alloys and found results in accord with the theoretical predictions for those that were formed. However, the alloys that could be readily made all showed an in-plane easy axis. The electronic structure of Fe3Sn is reported, as are some are magnetic and structural properties for the Fe3Sn2, and Fe5Sn3 compounds, which could be prepared as mm-sized single crystals.« less

  2. Enthalpies of Formation of (Cu,Ni)3Sn, (Cu,Ni)6Sn5-HT and (Ni,Cu)3Sn2-HT.

    PubMed

    Schmetterer, C; Rodriguez-Hortala, M; Flandorfer, H

    Standard enthalpies of formation of ternary phases in the Cu-Ni-Sn system were determined along sections at 25, 41 and 45.5 at.% Sn applying tin solution drop calorimetry. Generally, the interaction of Ni with Sn is much stronger than that of Cu with Sn. Along all sections the enthalpy of formation changes almost linearly with the mutual substitution of Cu and Ni within the respective homogeneity ranges. Thus no additional ternary interaction promoting the formation of further Cu-Ni-Sn phases can be assumed. The results are discussed and compared with literature values relevant to this system.

  3. Particle Acceleration in SN1006 Shock Waves

    NASA Technical Reports Server (NTRS)

    Raymond, John C.; Ghavamian, Parviz; Sonneborn, George (Technical Monitor)

    2003-01-01

    This grant is for the analysis of FUSE observations of particle acceleration in supernova remnant SN1006 shock waves. We have performed quick look analysis of the data, but because the source is faint and because the O VI emission lines on SN1006 are extremely broad, extreme care is needed for background subtraction and profile fitting. Moreover, the bulk of the analysis in will consist of model calculations. The Ly beta and O VI lines are clearly detected at the position in the NW filament of SN1006, but not in the NE position where non-thermal X-rays are strong. The lack of O VI emission in the NE places an upper limit on the pre-shock density there.

  4. Nb3Sn Artificial Pinning Microstructures

    SciTech Connect

    Dietderich, D.R.; Scanlan, R.M.

    1996-12-12

    Extension of the APC approach to Nb{sub 3}Sn requires that a second phae be incorporated into the Nb{sub 3}Sn layer. The second phase would increase pinning strength by either reducing the grain size or by the second phase pinning the flux itwelf. The following criteria for elements to be candidates for the APC approach are: (1) they must form intermetallic compounds with Cu or Sn and (2) they must have negligible solubility in Cu and Nb or they must be strong oxide formers. many of the rare earth elements satisfy these criteria. To circumvent the large strains required to produce wires with a fine distribution of the second phase, film deposition techniques have been used. Critical current densities for Nb films doped with Ti and Y are about 4,000 A/mm{sup 2} at 6T and 4.2 K.

  5. Interplay between relaxation and Sn segregation during thermal annealing of GeSn strained layers

    NASA Astrophysics Data System (ADS)

    Comrie, C. M.; Mtshali, C. B.; Sechogela, P. T.; Santos, N. M.; van Stiphout, K.; Loo, R.; Vandervorst, W.; Vantomme, A.

    2016-10-01

    The effect of thermal annealing on epitaxial GeSn (6.5% Sn) strained layers grown on Ge-buffered Si(100) wafers has been investigated using Rutherford backscattering spectrometry and X-ray diffraction to unambiguously determine the Sn substitutional content as well as the elastic strain in the layers. Vacuum annealing at temperatures below 400 °C for 20 min has no noticeable effect on the strain in the epitaxial layers. Once the temperature was raised above 400 °C, however, relaxation of the layer sets in and the GeSn layer has essentially completely relaxed following a 20 min anneal at 650 °C. Using Rutherford backscattering and channelling spectrometry to provide compositional information as a function of depth enables one to monitor the effect of the thermal anneal on the Sn distribution throughout the layer, and also to directly extract their substitutional fraction (i.e., their solubility in the lattice). The results obtained show that when the relaxation initially sets in both the Ge and the Sn remain firmly bound in substitutional lattice sites and it is only around 600 °C, and after substantial relaxation has taken place, that Sn is finally expelled from lattice sites and diffuses to the surface of the sample.

  6. Survey for the Binary Progenitor in SN1006 and Update on SN1572

    NASA Astrophysics Data System (ADS)

    Ruiz-Lapuente, Pilar; Hernández, Jonay González; Tabernero, Hugo; Montes, David; Canal, Ramon; Mendez, Javier; Bedin, Luigi

    2013-01-01

    We have completed a survey down to R = 15 mag of the stars within a circle of 4 arcmin radius around the nominal center of the remnant of SN 1006, one of the three historical Type Ia supernovae (the other two being SN 1572 and SN 1604), in search of a possible surviving binary companion of the white dwarf whose explosion gave rise to the supernova. The stellar parameters (effective temperature, surface gravity, and metallicity), as well as the radial velocities of all the stars, have been measured from spectra obtained with the UVES spectrograph at the VLT, and from the former and the available photometry, distances have been determined. Chemical abundances of the Fe-peak elements Cr, Mn, Co, and Ni have also been measured to check for possible contamination of the stellar surface by the supernova ejecta. The limiting magnitude of the survey would allow us to find stellar companions of the red-giant type, subgiant stars, and main-sequence stars down to F5-6. Unlike in SN 1572, where a subgiant of type G0-1 has been proposed as the companion of SN 1572, for SN 1006 we can discard the possibility that SN 1006 had a red giant or subgiant companion.

  7. Segregation of Sn and Sb in a ternary Cu(1 0 0)SnSb alloy

    NASA Astrophysics Data System (ADS)

    Asante, J. K. O.; Terblans, J. J.; Roos, W. D.

    2005-12-01

    Surface segregation studies of Sn and Sb in Cu(1 0 0)-0.14 at.% Sn-0.12 at.% Sb ternary alloy, have been done by making use of Auger Electron Spectroscopy. The method of Linear Temperature Ramp (LTR) was employed, whereby the sample was heated and cooled linearly at a constant rate. The positive heating rate showed both a kinetic segregation profile, as well as a narrow equilibrium segregation region, at higher temperatures. The equilibrium segregation profile was extended by cooling the sample. Sn was first to segregate to the surface due to its higher diffusion coefficient, mainly from a smaller activation energy ESn. Sb, due to its higher segregation energy, eventually replaced Sn from the surface. The modified Darken model was used to simulate the profile yielding the following segregation parameters: Do(Sn) = 6.3 × 10 -6 m 2/s, Do(Sb) = 2.8 × 10 -5 m 2/s; ESn = 175.4 kJ/mol, ESb = 186.3 kJ/mol; ΔGSn°=64.2 kJ/mol, ΔGSb°=84.3 kJ/mol; ΩCu-Sn = 3.4 kJ/mol, ΩCu-Sb = 15.9 kJ/mol and ΩSn-Sb = -5.4 kJ/mol.

  8. Origin of the SN2 benzylic effect.

    PubMed

    Galabov, Boris; Nikolova, Valia; Wilke, Jeremiah J; Schaefer, Henry F; Allen, Wesley D

    2008-07-30

    The S N2 identity exchange reactions of the fluoride ion with benzyl fluoride and 10 para-substituted derivatives (RC6H 4CH 2F, R = CH3, OH, OCH 3, NH2, F, Cl, CCH, CN, COF, and NO2) have been investigated by both rigorous ab initio methods and carefully calibrated density functional theory. Groundbreaking focal-point computations were executed for the C6H5CH 2F + F (-) and C 6H 5CH2Cl + Cl (-) SN2 reactions at the highest possible levels of electronic structure theory, employing complete basis set (CBS) extrapolations of aug-cc-pV XZ (X = 2-5) Hartree-Fock and MP2 energies, and including higher-order electron correlation via CCSD/aug-cc-pVQZ and CCSD(T)/aug-cc-pVTZ coupled cluster wave functions. Strong linear dependences are found between the computed electrostatic potential at the reaction-center carbon atom and the effective SN2 activation energies within the series of para-substituted benzyl fluorides. An activation strain energy decomposition indicates that the SN2 reactivity of these benzylic compounds is governed by the intrinsic electrostatic interaction between the reacting fragments. The delocalization of nucleophilic charge into the aromatic ring in the SN2 transition states is quite limited and should not be considered the origin of benzylic acceleration of SN2 reactions. Our rigorous focal-point computations validate the benzylic effect by establishing SN2 barriers for (F (-), Cl (-)) identity exchange in (C6H5CH2F, C6H 5CH2Cl) that are lower than those of (CH3F, CH3Cl) by (3.8, 1.6) kcal mol (-1), in order.

  9. On the Sn loss from thin films of the material system Cu-Zn-Sn-S in high vacuum

    NASA Astrophysics Data System (ADS)

    Weber, A.; Mainz, R.; Schock, H. W.

    2010-01-01

    In this paper the Sn loss from thin films of the material system Cu-Zn-Sn-S and the subsystems Cu-Sn-S and Sn-S in high vacuum is investigated. A combination of in situ x-ray diffractometry and x-ray fluorescence (XRF) at a synchrotron light source allowed identifying phases, which tend to decompose and evaporate a Sn-containing compound. On the basis of the XRF results a quantification of the Sn loss from the films during annealing experiments is presented. It can be shown that the evaporation rate from the different phases decreases according to the order SnS→Cu2SnS3→Cu4SnS4→Cu2ZnSnS4. The phase SnS is assigned as the evaporating compound. The influence of an additional inert gas component on the Sn loss and on the formation of Cu2ZnSnS4 thin films is discussed.

  10. Electronic structure and optical property of p-type Zn-doped SnO2 with Sn vacancy

    NASA Astrophysics Data System (ADS)

    Guipeng, Sun; Jinliang, Yan; Peijiang, Niu; Delan, Meng

    2016-02-01

    The electronic structures and optical properties of intrinsic SnO2, Zn-doped SnO2, SnO2 with Sn vacancy (VSn) and Zn-doped SnO2 with Sn vacancy are explored by using first-principles calculations. Zn-doped SnO2 is a p-type semiconductor material, whose Fermi level shifts into the valence band when Zn atoms substitute Sn atoms, and the unoccupied states on the top of the valence band come from Zn 3d and O 2p states. Sn vacancies increase the relative hole number of Zn-doped SnO2, which results in a possible increase in the conductivity of Zn-doped SnO2. The Zn-doped SnO2 shows distinct visible light absorption, the increased absorption can be seen apparently with the presence of Sn vacancies in the crystal, and the blue-shift of optical spectra can be observed. Project supported by the National Natural Science Foundation of China (No. 10974077) and the Innovation Project of Shandong Graduate Education, China (No. SDYY13093).

  11. Aluminum-stabilized NB3SN superconductor

    DOEpatents

    Scanlan, Ronald M.

    1988-01-01

    An aluminum-stabilized Nb.sub.3 Sn superconductor and process for producing same, utilizing ultrapure aluminum. Ductile components are co-drawn with aluminum to produce a conductor suitable for winding magnets. After winding, the conductor is heated to convert it to the brittle Nb.sub.3 Sn superconductor phase, using a temperature high enough to perform the transformation but still below the melting point of the aluminum. This results in reaction of substantially all of the niobium, while providing stabilization and react-in-place features which are beneficial in the fabrication of magnets utilizing superconducting materials.

  12. Shell model calculation for Te and Sn isotopes in the vicinity of {sup 100}Sn

    SciTech Connect

    Yakhelef, A.; Bouldjedri, A.

    2012-06-27

    New Shell Model calculations for even-even isotopes {sup 104-108}Sn and {sup 106,108}Te, in the vicinity of {sup 100}Sn have been performed. The calculations have been carried out using the windows version of NuShell-MSU. The two body matrix elements TBMEs of the effective interaction between valence nucleons are obtained from the renormalized two body effective interaction based on G-matrix derived from the CD-bonn nucleon-nucleon potential. The single particle energies of the proton and neutron valence spaces orbitals are defined from the available spectra of lightest odd isotopes of Sb and Sn respectively.

  13. Spectrum synthesis of the Type Ia supernovae SN 1992A and SN 1981B

    NASA Technical Reports Server (NTRS)

    Nugent, Peter; Baron, E.; Hauschildt, Peter H.; Branch, David

    1995-01-01

    We present non-local thermodynamic equilibrium (non-LTE) synthetic spectra for the Type Ia supernovae SN 1992A and SN 1981B, near maximum light. At this epoch both supernovae were observed from the UV through the optical. This wide spectral coverage is essential for determining the density structure of a SN Ia. Our fits are in good agreement with observation and provide some insight as to the differences between these supernovae. We also discuss the application of the expanding photosphere method to SNe Ia which gives a distance that is independent of those based on the decay of Ni-56 and Cepheid variable stars.

  14. Anomalous thermoelectric power behaviour in PrSn 3 and NdSn 3

    NASA Astrophysics Data System (ADS)

    Kletowski, Z.

    2006-03-01

    Results of the thermoelectric power (TEP) measurements done on monocrystalline samples of RESn 3 compounds (RE=La, Pr, Nd, and Gd) are presented for the temperature range of 5.5-300 K. It was found that the TEP is positive and weakly temperature dependent at temperatures T>100 K. For T<100 K pronounced anomalies have been observed for the PrSn 3 and the NdSn 3 compounds in the vicinity of 10 K.We argue that the Kondo and crystal field effects cause these anomalies. A shape of the TEP anomaly found for PrSn 3 resembles very much that observed in the electrical resistivity.

  15. Global properties of nuclei from {sup 100}Sn to {sup 132}Sn

    SciTech Connect

    Isakov, V. I.

    2013-07-15

    The paper presents the results of both microscopical and semi-empirical calculations of single-particle characteristics, nuclear binding, and one-nucleon separation energies of nuclei, as well as their root-mean-square radii, energy levels and transition rates in the long chain of Sn isotopes. We consider nuclei from the extremely neutron-deficient {sup 100}Sn up to neutron excess {sup 136}Sn, where the experimental information is available by now. The comprehensive comparison with the experimental data is carried out.

  16. Effects of plasma treatment on the growth of SnO2 nanorods from SnO2 thin films

    NASA Astrophysics Data System (ADS)

    Huang, Hui; Tan, O. K.; Lee, Y. C.; Tse, M. S.; Guo, J.; White, T.

    2006-02-01

    SnO2 thin films have been deposited by radio-frequency inductively coupled plasma-enhanced chemical vapour deposition using dibutyltin diacetate as the precursor. The as-deposited SnO2 thin films were post-treated in the inductively coupled plasma. After plasma treatment, uniform SnO2 nanorods were grown on the SnO2 thin films. The nanorods were formed by a sputtering-redeposition mechanism. The effects of the conditions of the plasma treatment on the morphology of plasma-treated SnO2 thin films were studied. The plasma power and the gaseous composition of the plasma had a great effect on the growth of SnO2 nanorods from SnO2 thin films. The type of plasma was also very critical, and no nanorods were grown on the SnO2 thin films treated in capacitively coupled plasma.

  17. New Polytypoid SnO2(ZnO:Sn)m Nanowire: Characterization and Calculation of its Electronic Structure

    SciTech Connect

    Cao, B.; Shi, T.; Zheng, S.; Ikuhara, Y. H.; Zhou, W.; Wood, D.; Al-Jassim, M.; Yan, Y.

    2012-03-01

    A new SnO{sub 2}(ZnO:Sn){sub m} polytypoid nanowire has been synthesized through a two-step chemical vapor deposition (CVD) method. Cs-corrected scanning transmission electron microscopy (STEM) studies indicate the crystal structure consists of an alternating stack of a Sn-O octahedral layer and a (Sn/Zn)-O wurtzite slab. First-principles density-functional theory (DFT) calculations suggest Sn atoms in the Sn-doped ZnO slabs have both 4- and 6-fold coordination, forming an inversion boundary of polarity. The SnO{sub 2}(ZnO:Sn){sub m} nanowires may exhibit unique anisotropic electronic properties: poor conductivity along the wire axis, but metallic conductivity along the diametrical directions according to the calculations.

  18. Sputtering deposition of P-type SnO films with SnO₂ target in hydrogen-containing atmosphere.

    PubMed

    Hsu, Po-Ching; Hsu, Chao-Jui; Chang, Ching-Hsiang; Tsai, Shiao-Po; Chen, Wei-Chung; Hsieh, Hsing-Hung; Wu, Chung-Chih

    2014-08-27

    In this work, we had investigated sputtering deposition of p-type SnO using the widely used and robust SnO2 target in a hydrogen-containing reducing atmosphere. The effects of the hydrogen-containing sputtering gas on structures, compositions, optical, and electrical properties of deposited SnOx films were studied. Results show that polycrystalline and SnO-dominant films could be readily obtained by carefully controlling the hydrogen gas ratio in the sputtering gas and the extent of reduction reaction. P-type conductivity was unambiguously observed for SnO-dominant films with traceable Sn components, exhibiting a p-type Hall mobility of up to ∼3 cm(2) V(-1) s(-1). P-type SnO thin-film transistors using such SnO-dominant films were also demonstrated.

  19. YPdSn and YPd{sub 2}Sn: Structure, {sup 89}Y solid state NMR and {sup 119}Sn Moessbauer spectroscopy

    SciTech Connect

    Hoeting, Christoph; Eckert, Hellmut; Langer, Thorsten; Schellenberg, Inga; Poettgen, Rainer

    2012-06-15

    The stannides YPdSn and YPd{sub 2}Sn were synthesized by high-frequency melting of the elements in sealed tantalum tubes. Both structures were refined on the basis of single crystal X-ray diffractometer data: TiNiSi type, Pnma, a=715.4(1), b=458.8(1), c=789.1(1) pm, wR2=0.0461, 510 F{sup 2} values, 20 variables for YPdSn and MnCu{sub 2}Al type, Fm3 Macron m, a=671.44(8), wR2=0.0740, 55 F{sup 2} values, 5 parameters for YPd{sub 2}Sn. The yttrium atoms in the new stannide YPdSn are coordinated by two tilted Pd{sub 3}Sn{sub 3} hexagons (ordered AlB{sub 2} superstructure). In the Heusler phase YPd{sub 2}Sn each yttrium atom has octahedral tin coordination and additionally eight palladium neighbors. The cubic site symmetry of yttrium is reflected in the {sup 119}Sn Moessbauer spectrum which shows no quadrupole splitting. In contrast, YPdSn shows a single signal at {delta}=1.82(1) mm/s subjected to quadrupole splitting of {Delta}E{sub Q}=0.93(1) mm/s. Both compounds have been characterized by high-resolution {sup 89}Y solid state NMR spectroscopy, which indicates the presence of strong Knight shifts. The spectrum of YPd{sub 2}Sn is characterized by an unusually large linewidth, suggesting the presence of a Knight shift distribution reflecting local disordering effects. The range of {sup 89}Y Knight shifts of several binary and ternary intermetallic yttrium compounds is briefly discussed. - Graphical abstract: YPdSn and YPd{sub 2}Sn: Structure, {sup 89}Y solid state NMR and {sup 119}Sn Moessbauer spectroscopy. Highlights: Black-Right-Pointing-Pointer Synthesis and structure of ternary stannides YPdSn and YPd{sub 2}Sn. Black-Right-Pointing-Pointer {sup 119}Sn Moessbauer spectroscopic investigation of YPdSn and YPd{sub 2}Sn. Black-Right-Pointing-Pointer {sup 89}Y solid state NMR of intermetallics.

  20. A search for radiative neutrino decay from supernovae

    NASA Technical Reports Server (NTRS)

    Svoboda, Robert C.

    1993-01-01

    Two supernovae have been identified in the COMPTEL data base as being the best sources to investigate for evidence of gamma-ray emission caused by radiative neutrino decay. These are SN1987a and SN1993J. A detailed simulation has shown us that we can expect a gain in sensitivity 1-3 orders of magnitude (depending on neutrino mass) over previous results. Instrument response is now being modeled using a SPARC10 computer acquired for this study. A library of simulated gamma-ray lines is being produced for COMPTEL as a by-product of this effort.

  1. Gamma ray line observations with OSSE

    NASA Technical Reports Server (NTRS)

    Kurfess, J. D.; Grove, J. E.; Johnson, W. N.; Murphy, R. J.; Share, G. H.; Purcell, W. R.; Leising, M. D.; Harris, M. J.

    1997-01-01

    Observations from the oriented scintillation spectrometer experiment of the gamma ray lines originating from a variety of Galactic center sources are reviewed. Extensive observations were acquired of the Galactic center region, including the 0.511 MeV positron annihilation line and associated positronium continuum and Al-26 emission. The results reviewed include: Co-57 from SN 1987A; limits on Co-56 from SN 1991T; gamma ray lines from solar flares; searches for Ti-44 emission from Cas A, and searches for C-12 and O-16 lines from the Orion region.

  2. Metallic Sn spheres and SnO2@C core-shells by anaerobic and aerobic catalytic ethanol and CO oxidation reactions over SnO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Kim, Won Joo; Lee, Sung Woo; Sohn, Youngku

    2015-08-01

    SnO2 has been studied intensely for applications to sensors, Li-ion batteries and solar cells. Despite this, comparatively little attention has been paid to the changes in morphology and crystal phase that occur on the metal oxide surface during chemical reactions. This paper reports anaerobic and aerobic ethanol and CO oxidation reactions over SnO2 nanoparticles (NPs), as well as the subsequent changes in the nature of the NPs. Uniform SnO2@C core-shells (10 nm) were formed by an aerobic ethanol oxidation reaction over SnO2 NPs. On the other hand, metallic Sn spheres were produced by an anaerobic ethanol oxidation reaction at 450 °C, which is significantly lower than that (1200 °C) used in industrial Sn production. Anaerobic and aerobic CO oxidation reactions were also examined. The novelty of the methods for the production of metallic Sn and SnO2@C core-shells including other anaerobic and aerobic reactions will contribute significantly to Sn and SnO2-based applications.

  3. Metallic Sn spheres and SnO2@C core-shells by anaerobic and aerobic catalytic ethanol and CO oxidation reactions over SnO2 nanoparticles.

    PubMed

    Kim, Won Joo; Lee, Sung Woo; Sohn, Youngku

    2015-08-24

    SnO2 has been studied intensely for applications to sensors, Li-ion batteries and solar cells. Despite this, comparatively little attention has been paid to the changes in morphology and crystal phase that occur on the metal oxide surface during chemical reactions. This paper reports anaerobic and aerobic ethanol and CO oxidation reactions over SnO2 nanoparticles (NPs), as well as the subsequent changes in the nature of the NPs. Uniform SnO2@C core-shells (10 nm) were formed by an aerobic ethanol oxidation reaction over SnO2 NPs. On the other hand, metallic Sn spheres were produced by an anaerobic ethanol oxidation reaction at 450 °C, which is significantly lower than that (1200 °C) used in industrial Sn production. Anaerobic and aerobic CO oxidation reactions were also examined. The novelty of the methods for the production of metallic Sn and SnO2@C core-shells including other anaerobic and aerobic reactions will contribute significantly to Sn and SnO2-based applications.

  4. Metallic Sn spheres and SnO2@C core-shells by anaerobic and aerobic catalytic ethanol and CO oxidation reactions over SnO2 nanoparticles

    PubMed Central

    Kim, Won Joo; Lee, Sung Woo; Sohn, Youngku

    2015-01-01

    SnO2 has been studied intensely for applications to sensors, Li-ion batteries and solar cells. Despite this, comparatively little attention has been paid to the changes in morphology and crystal phase that occur on the metal oxide surface during chemical reactions. This paper reports anaerobic and aerobic ethanol and CO oxidation reactions over SnO2 nanoparticles (NPs), as well as the subsequent changes in the nature of the NPs. Uniform SnO2@C core-shells (10 nm) were formed by an aerobic ethanol oxidation reaction over SnO2 NPs. On the other hand, metallic Sn spheres were produced by an anaerobic ethanol oxidation reaction at 450 °C, which is significantly lower than that (1200 °C) used in industrial Sn production. Anaerobic and aerobic CO oxidation reactions were also examined. The novelty of the methods for the production of metallic Sn and SnO2@C core-shells including other anaerobic and aerobic reactions will contribute significantly to Sn and SnO2-based applications. PMID:26300041

  5. GMRT observations of SN 2016bkv

    NASA Astrophysics Data System (ADS)

    Chandra, Poonam; Nayana, A. J.

    2016-04-01

    We observed SN 2016bkv, discovered by K. Itagaki (https://wis-tns.weizmann.ac.il//object/2016bkv) on 2016 March 21.70 UT, with the Giant Metrewave Radio Telescope (GMRT) on 2016 April 03.53 UT in 1390 MHz band.

  6. Reaction mechanisms: Stripping down SN2

    NASA Astrophysics Data System (ADS)

    Orr-Ewing, Andrew J.

    2012-07-01

    The mechanism of the SN2 reaction is fundamental to understanding and controlling the stereochemistry of organic reactions, but surrounding solvent molecules may complicate the textbook picture. Micro-solvation studies have now explored the stereochemical consequences of the presence of one or two solvent molecules.

  7. Multiepoch Spectropolarimetry of SN 2011fe

    NASA Astrophysics Data System (ADS)

    Milne, Peter A.; Williams, G. Grant; Porter, Amber; Smith, Paul S.; Smith, Nathan; Leising, Mark D.; Jannuzi, Buell T.; Green, E. M.

    2017-01-01

    We present multiple spectropolarimetric observations of the nearby Type Ia supernova (SN) 2011fe in M101, obtained before, during, and after the time of maximum apparent visual brightness. The excellent time coverage of our spectropolarimetry has allowed better monitoring of the evolution of polarization features than is typical, which has allowed us new insight into the nature of normal SNe Ia. SN 2011fe exhibits time-dependent polarization in both the continuum and strong absorption lines. At early epochs, red wavelengths exhibit a degree of continuum polarization of up to 0.4%, likely indicative of a mild asymmetry in the electron-scattering photosphere. This behavior is more common in subluminous SNe Ia than in normal events, such as SN 2011fe. The degree of polarization across a collection of absorption lines varies dramatically from epoch to epoch. During the earliest epoch, a λ4600–5000 Å complex of absorption lines shows enhanced polarization at a different position angle than the continuum. We explore the origin of these features, presenting a few possible interpretations, without arriving at a single favored ion. During two epochs near maximum, the dominant polarization feature is associated with the Si ii λ6355 Å absorption line. This is common for SNe Ia, but for SN 2011fe the polarization of this feature increases after maximum light, whereas for other SNe Ia, that polarization feature was strongest before maximum light.

  8. Characteristics of Reactive Ni3Sn4 Formation and Growth in Ni-Sn Interlayer Systems

    NASA Astrophysics Data System (ADS)

    Lis, Adrian; Kenel, Christoph; Leinenbach, Christian

    2016-06-01

    The near-isothermal growth and formation of Ni3Sn4 intermetallic compounds (IMC) in Ni-Sn interlayer systems was studied in the solid state at 473 K (200 °C) and under solid-liquid conditions at 523 and 573 K (250 °C and 300 °C) from an initial state of a few seconds. Scalloped solid-state IMC formation was mainly driven by grain boundary diffusion of Ni through the IMC layer combined with the grain coarsening of the IMC layer. Under solid-liquid conditions, the formation of faceted and needle-shaped Ni3Sn4 grains as well as an atypical IMC growth behavior with similar parabolic growth constants for 523 K and 573 K (250 °C and 300 °C) was observed within the first 180 seconds of the holding time, and IMC growth occurred as an isothermal solidification from the Ni-saturated Sn melt. Due to the progressive densification of the IMC layer and the diffusion-controlled growth, the kinetics slowed down by approximately one order of magnitude after 180 seconds of annealing. The final stage was characterized by the formation of IMC islands ahead of the interfacial Ni3Sn4 layer. Needle-like IMC growth was effectively suppressed under combined solid-state and solid-liquid conditions. Textured Ni3Sn4 IMC formation at the Ni-Sn interface was approved with pole figure measurements. The activation energy Q for solid-liquid IMC formation was calculated as 43.3 kJ/mol, and processing maps for IMC growth and Sn consumption were derived as functions of temperature and time, respectively.

  9. SN 2013fs & SN 2013fr: Filling the gaps between Type IIn and Type IIP supernovae

    NASA Astrophysics Data System (ADS)

    Bullivant, Christopher William; Smith, Nathan; Milne, Peter; LOSS, PESSTO, LCOGT

    2017-01-01

    Type IIn supernovae (SNe IIn), characterized by narrow lines in their spectra, display some of the greatest diversity in environments and explosion characteristics, despite representing only about 9% of all core collapse supernovae. The narrow lines are indicative of circumstellar material (CSM) ejected by the progenitor during the late stages of massive star evolution. Consequently, SNe IIn can be attributed to a wide range of progenitors with strong mass loss. Previous research has suggested a continuum between Type IIn and IIP, and Type IIP and IIL supernovae. We present early time photometry and spectroscopy of SN 2013fs and SN 2013fr, both objects initially classified as type IIn supernovae, across a wide range of wavelengths. These both exhibit signs of early time CSM interaction and are spectroscopically similar at discovery, but rapidly diverge as they evolve. We discuss the implications of this highly divergent evolution on the efforts to link SNe IIn and SNe IIP, as SN 2013fs and SN 2013fr both occupy positions in between very bright SNe IIn like SN 1998S and more typical SNe IIP like SN 1999em.

  10. Gap formation in the semimetal U 2Ru 2Sn: evidence from 119Sn NMR investigations

    NASA Astrophysics Data System (ADS)

    Baenitz, M.; Rabis, A.; Paschen, S.; Senthilkumaran, N.; Steglich, F.; Tran, V. H.; de V. du Plessis, P.; Strydom, A. M.

    2003-05-01

    We report measurements of the 119Sn nuclear spin-lattice relaxation rate 1/ T1 and the Knight shift K for polycrystalline U 2Ru 2Sn powder samples as a function of temperature. The T dependence of 1/ T1 is very similar to that of CeNiSn with the only difference that the temperature scale is increased roughly by a factor of 10. Therefore a first estimate gives a (pseudo-) gap value of Δ/k B≈140 K ( ≈14 K for CeNiSn). At low temperatures similar to CeNiSn a T1T=constant behaviour is observed which indicates the presence of a residual density of states at the Fermi level N( EF) in the pseudo-gap. Knight shift measurements on oriented polycrystalline powder samples show nearly no magnetic anisotropy, whereas the temperature dependence roughly follows the behaviour of the magnetic susceptibility. First investigations on the non-magnetic reference compound Th 2Ru 2Sn are also discussed.

  11. SN2012ca: a stripped envelope core-collapse SN interacting with dense circumstellar medium

    NASA Astrophysics Data System (ADS)

    Inserra, C.; Smartt, S. J.; Scalzo, R.; Fraser, M.; Pastorello, A.; Childress, M.; Pignata, G.; Jerkstrand, A.; Kotak, R.; Benetti, S.; Della Valle, M.; Gal-Yam, A.; Mazzali, P.; Smith, K.; Sullivan, M.; Valenti, S.; Yaron, O.; Young, D.; Reichart, D.

    2014-01-01

    We report optical and near-infrared observations of SN2012ca with the Public ESO Spectroscopy Survey of Transient Objects (PESSTO), spread over one year since discovery. The supernova (SN) bears many similarities to SN1997cy and to other events classified as Type IIn but which have been suggested to have a thermonuclear origin with narrow hydrogen lines produced when the ejecta impact a hydrogen-rich circumstellar medium (CSM). Our analysis, especially in the nebular phase, reveals the presence of oxygen, magnesium and carbon features. This suggests a core-collapse explanation for SN2012ca, in contrast to the thermonuclear interpretation proposed for some members of this group. We suggest that the data can be explained with a hydrogen- and helium-deficient SN ejecta (Type I) interacting with a hydrogen-rich CSM, but that the explosion was more likely a Type Ic core-collapse explosion than a Type Ia thermonuclear one. This suggests that two channels (both thermonuclear and stripped envelope core-collapse) may be responsible for these SN 1997cy-like events.

  12. Origin of Galactic Type-Ia supernovae: SN 1572 and SN 1006

    NASA Astrophysics Data System (ADS)

    González-Hernández, J. I.; Ruiz-Lapuente, P.; Tabernero, H. M.; Montes, D.; Canal, R.; Méndez, J.; Bedin, L. R.

    2015-05-01

    We have been searching for surviving companions of progenitors of Galactic Type-Ia supernovae, in particular SN 1572 and SN 1006. These companion stars are expected to show peculiarities: (i) to be probably more luminous than the Sun, (ii) to have high radial velocity and proper motion, (iii) to be possibly enriched in metals from the SNIa ejecta, and (iv) to be located at the distance of the SNIa remnant. We have been characterizing possible candidate stars using high-resolution spectroscopic data taken at 10m-Keck and 8.2m-VLT facilities. We have identified a very promising candidate companion (Tycho G) for SN 1572 (see Ruiz-Lapuente et al. 2004; however for a different view see Kerzendorf et al., 2012) but we have not found any candidate companion for SN 1006, suggesting that SN event occurred in 1006 could have been the result of the merging of two white dwarfs (see González-Hernández et al., 2012). Adding these results to the evidence from the other direct searches, the clear minority of cases (20% or less) seem to disfavour the single-degenerate channel or that preferentially the single-degenerate escenario would involve main-sequence companions less massive than the Sun. Therefore, it appears to be very important to continue investigating these and other Galactic Type-Ia SNe such as the Johannes Kepler SN 1604.

  13. SN 2010as and Transitional Ib/c Supernovae

    NASA Astrophysics Data System (ADS)

    Folatelli, Gastón

    2014-01-01

    We present intensive photometric and spectroscopic observations of SN 2010as carried out by the Millennium Center for Supernova Studies (MCSS) and the Carnegie Supernova Project (CSP). The SN belongs to the transitional type Ibc (SN Ibc) that is characterized by the slow appearance of weak helium lines with low expansion velocities. We find a wide variety of photometric properties among otherwise spectroscopically similar SN Ibc. A hydrodynamical model is used to provide physical properties of SN 2010as in comparison with the bolometric light curve and expansion velocity.

  14. 70 °C synthesis of high-Sn content (25%) GeSn on insulator by Sn-induced crystallization of amorphous Ge

    SciTech Connect

    Toko, K. Oya, N.; Suemasu, T.; Saitoh, N.; Yoshizawa, N.

    2015-02-23

    Polycrystalline GeSn thin films are fabricated on insulating substrates at low temperatures by using Sn-induced crystallization of amorphous Ge (a-Ge). The Sn layer stacked on the a-Ge layer (100-nm thickness each) had two roles: lowering the crystallization temperature of a-Ge and composing GeSn. Slow annealing at an extremely low temperature of 70 °C allowed for a large-grained (350 nm) GeSn layer with a lattice constant of 0.590 nm, corresponding to a Sn composition exceeding 25%. The present investigation paves the way for advanced electronic optical devices integrated on a flexible plastic substrate as well as on a Si platform.

  15. Chemically Resolved Structure of the Sn/Ge(111) Surface

    NASA Astrophysics Data System (ADS)

    Lee, Tien-Lin; Warren, Samantha; Cowie, Bruce C. C.; Zegenhagen, Jörg

    2006-02-01

    The structure and chemical states of the Sn/Ge(111) surface are characterized by x-ray standing waves combined with photoemission. For the room temperature 3×3 phase two chemical components, approximately 0.4 eV apart, are observed for both Sn 3d and 4d core levels. Our model-independent, x-ray standing wave analysis shows unambiguously that the two components originate from Sn adatoms located at two different heights separated vertically by 0.23 Å, in favor of a model composed of a fluctuating Sn layer. Contrary to the most accepted scenario, the stronger Sn 3d and 4d components, which appear at the lower binding-energy sides and account for 2/3 of the Sn adatoms, are identified to be associated with the higher Sn position, manifesting their filled valence state character.

  16. Interfacial Reactions in Sn-Ag/Co Couples

    NASA Astrophysics Data System (ADS)

    Chen, Sinn-wen; Chen, Tung-Kai; Chang, Jui-shen; Hsu, Chia-ming; Chen, Wei-An

    2014-02-01

    Sn-Ag alloys are important solders, and Co and Co alloys are investigated as barrier layers. Interfacial reactions in Sn-Ag/Co couples were examined in this study for Ag contents of 1.0 wt.%, 2.0 wt.%, and 3.5 wt.% and reaction temperatures of 250°C, 200°C, and 150°C. Only CoSn3 formed in Sn-Ag/Co couples reacted at 250°C, but both CoSn3 and Ag3Sn formed in couples reacted at 200°C and 150°C. The reaction layer was 100 μm thick in Sn-3.5 wt.%Ag/Co couples reacted at 200°C for 110 h. The reaction rates were lower if Ag was added, but remained very fast compared with those for Ni and Ni-based substrates.

  17. Beta Decay of 101Sn

    SciTech Connect

    Kavatsyuk, O.; Mazzocchi, C.; Janas, Z.; Banu, A.; Batist, L.; Becker, F.; Blazhev, A.; Bruchle, W.; Doring, J.; Faestermann, T.; Gorska, M.; Grawe, H.; Jungclaus, A.; Karny, M.; Kavatsyuk, M.; Klepper, O.; Kirchner, R.; La Commara, M.; Miernik, K.; Mukha, I.; Plettner, C.; Plochocki, A.; Roeckl, E.; Romoli, M.; Rykaczewski, Krzysztof Piotr; Schadel, M.; Schmidt, K.; Schwengner, R.; Zylicz, J.

    2007-01-01

    The {beta} decay of the very neutron-deficient isotope 101Sn was studied at the GSI on-line mass separator using silicon detectors for recording charged particles and germanium detectors for {gamma}-ray spectroscopy. Based on the {beta}-delayed proton data the production cross-section of 101Sn in the 50Cr + 58Ni fusion-evaporation reaction was determined to be about 60nb. The half-life of 101Sn was measured to be 1.9(3)s. For the first time {beta}-delayed {gamma}-rays of 101Sn were tentatively identified, yielding weak evidence for a cascade of 352 and 1065keV transitions in 101In. The results for the 101Sn decay as well as those from previous work on the 103Sn decay are discussed by comparing them to predictions obtained from shell model calculations employing a new interaction in the 88Sr to 132Sn model space.

  18. Liquid-Phase Separation in the Interdendritic Region After Growth of Primary β-Sn in Undercooled Sn-2.8Ag-0.3Cu Melt

    NASA Astrophysics Data System (ADS)

    Takamatsu, Yoshiko; Esaka, Hisao; Shinozuka, Kei

    2012-08-01

    An unusual microstructure consisting of both Sn-Ag3Sn and Sn-Cu6Sn5 binary eutectic structures is observed in actual solder balls. In this study, the solidification process of the Sn-Ag3Sn binary eutectic structure after the growth of primary β-Sn in an undercooled Sn-2.8Ag-0.3Cu alloy was investigated by using thermal analysis and interruption tests to understand the formation of the unusual microstructure. First, fine Ag-enriched liquid zones formed around β-Sn after the growth of primary β-Sn. The Ag-enriched zones then gradually enlarged with the accumulation of Ag from the remnant liquid with a decrease in temperature. This indicated that the liquid-phase separation occurred in the remnant liquid after the nucleation of β-Sn. Eventually, when the temperature of the specimen decreased to approximately the binary eutectic temperature, eutectic Ag3Sn nucleated in the Ag-enriched zones. From interruption tests, we determined the precursor of the Sn-Ag3Sn binary eutectic structure before the beginning of Sn-Ag3Sn binary eutectic solidification. This finding corresponds to the precursor of the Sn-Cu6Sn5 binary eutectic structure observed in the Sn-1.0Ag-0.5Cu alloy.

  19. Lattice Thermal Conductivity of the Binary and Ternary Group-IV Alloys Si-Sn, Ge-Sn, and Si-Ge-Sn

    NASA Astrophysics Data System (ADS)

    Khatami, S. N.; Aksamija, Z.

    2016-07-01

    Efficient thermoelectric (TE) energy conversion requires materials with low thermal conductivity and good electronic properties. Si-Ge alloys, and their nanostructures such as thin films and nanowires, have been extensively studied for TE applications; other group-IV alloys, including those containing Sn, have not been given as much attention as TEs, despite their increasing applications in other areas including optoelectronics. We study the lattice thermal conductivity of binary (Si-Sn and Ge-Sn) and ternary (Si-Ge-Sn) alloys and their thin films in the Boltzmann transport formalisms, including a full phonon dispersion and momentum-dependent boundary-roughness scattering. We show that Si-Sn alloys have the lowest conductivity (3 W /mK ) of all the bulk alloys, more than 2 times lower than Si-Ge, attributed to the larger difference in mass between the two constituents. In addition, we demonstrate that thin films offer an additional reduction in thermal conductivity, reaching around 1 W /mK in 20-nm-thick Si-Sn, Ge-Sn, and ternary Si-Ge-Sn films, which is near the conductivity of amorphous SiO2 . We conclude that group-IV alloys containing Sn have the potential for high-efficiency TE energy conversion.

  20. X-ray photoelectron spectroscopy study of SnO2 and SnO2+x thin films.

    PubMed

    Jeong, Jin; Lee, Bong Ju

    2013-01-01

    SnO2 thin films were fabricated using low-pressure thermal chemical vapor deposition. The results of X-ray photoelectron spectroscopy revealed that the SiO2 layer with an O1S-binding energy of 531.2 eV was formed before the SnO2 layer with an O1S-binding energy of 530.5 eV was formed. In the beginning, the SnO2 thin film showed Sn3d5-binding energy peaks of 485 eV and 486.5 eV. Subsequently, it grew in the direction of 486.5 eV. The Sn3d5-binding strength of the SnO2+x thin film that was annealed in oxygen atmosphere was weaker than that of the SnO2 thin film. Additionally, the Sn3d5-binding strength decreased linearly as the depth of the thin film increased. The surface O1S-binding strength of the SnO2+x thin film annealed in oxygen atmosphere was stronger than that of the SnO2 thin film; however, this strength became weaker than that that of the SnO2 thin film when the depth of the thin film was 2500A or higher.

  1. Phase equilibria of the Sn-Ag-Cu-Ni quaternary system at the sn-rich corner

    NASA Astrophysics Data System (ADS)

    Chen, Sinn-Wen; Chang, Cheng-An

    2004-10-01

    Knowledge of phase equilibria of the Sn-Ag-Cu-Ni quaternary system at the Sn-rich corner is important for the understanding of the interfacial reactions at the Sn-Ag-Cu/Ni contacts, which are frequently encountered in recent microelectronic products. Various Sn-Ag-Cu-Ni alloys were prepared and equilibrated at 250°C. The alloys were then quenched and analyzed. The phases were determined by metallography, compositional analysis, and x-ray diffraction (XRD) analysis. No quaternary phases were found. The isoplethal sections at 60at.%Sn, 70at.%Sn, 80at.%Sn, and 90at.%Sn at 250°C are determined. The phase equilibrium relationship was proposed based on the quaternary experimental results and the 250°C isothermal sections of the four constituent ternary systems, Sn-Ag-Cu, Sn-Ag-Ni, Sn-Cu-Ni, and Cu-Ag-Ni. Because there are no ternary phases in all these three systems, all the compounds are in fact binary compounds with various solubilities of the other two elements.

  2. 119Sn Mössbauer parameters as predictive tool for future Sn-based negative electrode materials

    NASA Astrophysics Data System (ADS)

    Naille, S.; Jumas, J.-C.; Lippens, P.-E.; Olivier-Fourcade, J.

    Thanks to the 119Sn Mössbauer hyperfine parameters, it is possible to analyze and predict Li reaction mechanisms with Sn-based negative electrodes for Li-ion batteries. The present approach is based on the interpretation of the 119Sn Mössbauer hyperfine parameters: isomer shift (δ) and quadrupole splitting (Δ) by considering: (i) the analysis of the 119Sn Mössbauer hyperfine parameters of the Li-Sn alloys used as model compounds, (ii) their interpretation from some physicochemical parameters (Li/Sn ratio, crystal structure, electronic density as defined by Hume-Rothery), and (iii) the proposition of an experimental based model to understand Li lithiation/delithiation mechanisms and predict electrochemical performances for Sn-based compounds including the effects of volume variations, particle coalescence or SEI formation.

  3. Oxidation of SnO to SnO{sub 2} thin films in boiling water at atmospheric pressure

    SciTech Connect

    Nose, K. Suzuki, A. Y.; Oda, N.; Kamiko, M.; Mitsuda, Y.

    2014-03-03

    We demonstrated that SnO is oxidized to SnO{sub 2} in boiling water. (001)-oriented SnO thin films were pulsed-laser deposited onto a glass substrate. The Sn valence number changed from (II) to (IV) by keeping SnO films in boiling water at atmospheric pressure for 5 h. Optical transparency of the obtained SnO{sub 2} films was greater than 95% in the visible light range. The SnO{sub 2} films possessed an amorphous structure, and exhibited dielectric properties. Atomic force microscopy and Fourier transform infrared spectroscopy revealed granular structures and the existence of –OH groups, which may account for the diffusion of oxidants within the film.

  4. SnO and SnO·CoO nanocomposite as high capacity anode materials for lithium ion batteries

    SciTech Connect

    Das, B. Reddy, M.V.; Chowdari, B.V.R

    2016-02-15

    Highlights: • The preparation methods are simple, low cost and can be scaled up for large production. • SnO is cheap, non-toxic and eco-friendly. • SnO shows high reversible capacity (Theoretical reversible capacity: 875 mA h g{sup −1}). • We showed high reversible capacity and columbic efficiency for SnO and SnO based composites. • We addressed the capacity degradation by introducing secondary phase (CoO and CNT etc.) - Abstract: We prepared SnO nanoparticles (SnO–S) and SnO·CoO nanocomposites (SnO·CoO–B) as anodes for lithium ion batteries (LIBs) by chemical and ball-milling approaches, respectively. They are characterized by X-ray diffraction and TEM techniques. The Li- storage performance are evaluated by galvanostatic cycling and cyclic voltammetry. The SnO–S and SnO·CoO–B showed improved cycling performance due to their finite particle size (i.e. nano-size) and presence of secondary phase (CoO). Better cycling stability is noticed for SnO·CoO–B with the expense of their reversible capacity. Also, addition of carbon nanotubes (CNT) to SnO–S further improved the cycling performance of SnO–S. When cycled at 60 mA g{sup −1}, the first-cycle reversible capacities of 635, 590 and 460 (±10) mA h g{sup −1} are noticed for SnO–S, SnO@CNT and SnO·CoO–B, respectively. The capacity fading observed are 3.7 and 1.8 mA h g{sup −1} per cycle for SnO–S and SnO@CNT, respectively; whereas 1–1.2 mA h g{sup −1} per cycle for SnO·CoO–B. All the samples show high coulombic efficiency, 96–98% in the range of 5–50 cycles.

  5. Mode-Specific SN2 Reaction Dynamics.

    PubMed

    Wang, Yan; Song, Hongwei; Szabó, István; Czakó, Gábor; Guo, Hua; Yang, Minghui

    2016-09-01

    Despite its importance in chemistry, the microscopic dynamics of bimolecular nucleophilic substitution (SN2) reactions is still not completely elucidated. In this publication, the dynamics of a prototypical SN2 reaction (F(-) + CH3Cl → CH3F + Cl(-)) is investigated using a high-dimensional quantum mechanical model on an accurate potential energy surface (PES) and further analyzed by quasi-classical trajectories on the same PES. While the indirect mechanism dominates at low collision energies, the direct mechanism makes a significant contribution. The reactivity is found to depend on the specific reactant vibrational mode excitation. The mode specificity, which is more prevalent in the direct reaction, is rationalized by a transition-state-based model.

  6. LARP Long Nb3Sn Quadrupole Design

    SciTech Connect

    Ambrosio, G.; Andreev, N.; Anerella, M.; Barzi, E.; Bossert, R.; Caspi, S.; Chlachidize, G.; Dietderich, D.; Feher, S.; Ferracin, P.; Ghosh, A.; Hafalia, R.; Hannaford, R.; Kashikhin, V.V.; Kerby, J.; Lamm, M.; Lietzke, A.; McInturff, A.; Muratore, J.; Nobrega, F.; Novitsky, I.; Sabbi, G.L.; Schmalzle, J.; Tartaglia, M.; Turrioni, D.; Wanderer, P.; Whitson, G.; Zlobin, A.V.

    2008-06-01

    A major milestone for the LHC Accelerator Research Program (LARP) is the test, by the end of 2009, of two 4m-long quadrupole magnets (LQ) wound with Nb{sub 3}Sn conductor. The goal of these magnets is to be a proof of principle that Nb{sub 3}Sn is a viable technology for a possible LHC luminosity upgrade. The design of the LQ is based on the design of the LARP Technological Quadrupoles, presently under development at FNAL and LBNL, with 90-mm aperture and gradient higher than 200 T/m. The design of the first LQ model will be completed by the end of 2007 with the selection of a mechanical design. In this paper we present the coil design addressing some fabrication technology issues, the quench protection study, and three designs of the support structure.

  7. SnET2: clinical update

    NASA Astrophysics Data System (ADS)

    Razum, Nicholas J.; Snyder, Albert B.; Doiron, Daniel R.

    1996-04-01

    Tin Ethyl Etiopurpurin, SnET2, is a synthetic chlorin analog presently in Phase-II/III clinical trials for the treatment of cutaneous cancers. Trials to date include the treatment of basal cell carcinomas, squamous cell carcinomas, breast adenocarcinomas metastatic to the chest wall and cutaneous Kaposi's sarcomas in AIDS patients. Results to date have shown significant clinical responses for drug doses between 1.0 mg/kg and 1.6 mg/kg, with the threshold for Kaposi's sarcoma being slightly higher than in other indications. Light doses from 100 J/cm2 to 300 J/cm2 were delivered from 24 to 72 hours post SnET2 infusion. Induced transient skin photosensitivity at the lower therapeutic doses has been mild, lasting approximately a week. Results of the Phase I and II trials are presented.

  8. LARP Long Nb3Sn Quadrupole Design.

    SciTech Connect

    Ambrosio,G.; Andreev, N.; Anerella, M.; Barzi, E.; Bossert, R.; Caspi, S.; Chlachidize, G.; Dietderich, D.; Feher, S.; Felice, H.; Ferracin, P.; Ghosh, A.; Hafalia, A.R.; Hannaford, C.R.; Kashikhin, V.V.; Kerby, J.; Lamm, M.; Lietzke, A.; McInturff, A.; Muratore, J.; Nobrega, F.; Novitsky, I.; Sabbi, G.L.; Schmalzle, J.; Tartaglia, M.; Turrioni, D.; Wanderer, P.; Whitson, G.; Zlobin, A.V.

    2007-08-27

    A major milestone for the LHC Accelerator Research Program (LARP) is the test, by the end of 2009, of two 4m-long quadrupole magnets (LQ) wound with Nb{sub 3}Sn conductor. The goal of these magnets is to be a proof of principle that Nb{sub 3}Sn is a viable technology for a possible LHC luminosity upgrade. The design of the LQ is based on the design of the LARP Technological Quadrupoles, presently under development at FNAL and LBNL, with 90-mm aperture and gradient higher than 200 T/m. The design of the first LQ model will be completed by the end of 2007 with the selection of a mechanical design. In this paper we present the coil design addressing some fabrication technology issues, the quench protection study, and three designs of the support structure.

  9. LARP Long Nb3Sn Quadrupole Design

    SciTech Connect

    Ambrosio, G.; Andreev, N.; Anerella, M.; Barzi, E.; Bossert, R.; Caspi, S.; Chlachidze, G.; Dietderich, D.; Feher, S.; Felice, H.; Ferracin, P.; /Fermilab /Brookhaven /LBL, Berkeley /Texas A-M

    2007-08-01

    A major milestone for the LHC Accelerator Research Program (LARP) is the test, by the end of 2009, of two 4m-long quadrupole magnets (LQ) wound with Nb3Sn conductor. The goal of these magnets is to be a proof of principle that Nb3Sn is a viable technology for a possible LHC luminosity upgrade. The design of the LQ is based on the design of the LARP Technological Quadrupoles, presently under development at FNAL and LBNL, with 90-mm aperture and gradient higher than 200 T/m. The design of the first LQ model will be completed by the end of 2007 with the selection of a mechanical design. In this paper we present the coil design addressing some fabrication technology issues, the quench protection study, and three designs of the support structure.

  10. Syntheses and structures of Sc2Nb(4–x)Sn5, YNb6Sn6, and ErNb6Sn5: exploratory studies in ternary rare-earth niobium stannides.

    PubMed

    Yue, Cheng-Yang; Lei, Xiao-Wu

    2012-02-20

    Three new rare-earth (RE) niobium stannides, namely, Sc(2)Nb(4-x)Sn(5) (x = 0.37, 0.52), YNb(6)Sn(6), and ErNb(6)Sn(5), have been obtained by reacting the mixture of corresponding pure elements at high temperature and structurally characterized by single-crystal X-ray diffraction studies. Sc(2)Nb(4-x)Sn(5) crystallizes in the orthorhombic space group Ibam (No. 72) and belongs to the V(6)Si(5) type. Its structure features a three-dimensional (3D) network composed of two-dimensionally (2D) corrugated [Nb(2)Sn(2)] and [Nb(2)Sn(3)] layers interconnected via Nb-Sn bonds, forming one type of one-dimensional (1D) narrow tunnels along the c axis occupied by Sc atoms. YNb(6)Sn(6) crystallizes in the hexagonal space group P6/mmm (No. 191) and adopts the HfFe(6)Ge(6) type, and ErNb(6)Sn(5) crystallizes in the trigonal space group R3m (No. 166) and belongs to the LiFe(6)Ge(5) type. Their structures both feature 3D networks based on 2D [Nb(3)Sn], [Sn(2)], and [RESn(2)] layers (RE = Y, Er). In YNb(6)Sn(6), one type of [Nb(3)Sn] layer is interconnected by [Sn(2)] and [YSn(2)] layers via Nb-Sn bonds to form a 3D network. However, in ErNb(6)Sn(5), two types of [Nb(3)Sn] layers are interlinked by [Sn(2)] and [ErSn(2)] layers via Nb-Sn bonds into a 3D framework. Electronic structure calculations and magnetic property measurements for "Sc(2)Nb(4)Sn(5)" and YNb(6)Sn(6) indicate that both compounds show semimetallic and temperature-independent diamagnetic behavior.

  11. 119Sn CEMS study of Sb doped SnO2 film

    NASA Astrophysics Data System (ADS)

    Nomura, K.; Kuzmann, E.; Garg, V. K.; de Oliveira, A. C.; Stichleutner, S.; Homonnay, Z.

    2016-12-01

    Sb doped SnO2 films prepared by DC sputtering and heating were characterized by 119Sn conversion electron Mössbauer spectrometry (CEMS). An asymmetric doublet was observed in the Mössbauer spectra of 1 %, 3 %, and 10 % Sb doped SnO2 films. The peak ratios of doublets are considered to be due to the columnar crystal growth on the substrate. With the doping level of Sb, both the isomer shift ( δ) and the quadrupole splitting (Δ) increased. After annealing, δ increased and Δ decreased for each sample. These results suggest the followings. The electron doping of the SnO2 lattice by pentavalent Sb induces the increase of the electron density at the SnIV nucleus. The annealing process leads to more complete accommodation of the Sb dopant that results in more effective electron doping and therefore increasing isomer shift for tin. Simultaneously, the distortion of the lattice caused by Sb is relaxed and the quadrupole splitting decreases.

  12. N→Sn-Coordinated Stannaoxidoborates Containing a SnB4O6 Unit.

    PubMed

    Mairychová, Barbora; Kityk, I V; Maciag, Artur; Bureš, Filip; Klikar, Milan; Růžička, Aleš; Dostál, Libor; Jambor, Roman

    2016-02-15

    We report here the synthesis of new N→Sn-coordinated stannaoxidoborates H[LSnB4O6R4] {L = [2,6-(Me2NCH2)C6H3](-) and R = Ph (6), 4-Br-Ph (7), 3,5-(CF3)2-Ph (8), and 4-CHO-Ph (9)} containing a nonsymmetric SnB4O6 unit. Compounds 6-9 represent new derivatives of the pentaborates [B5O6R4](-) in which the central boron is substituted by a tin atom. Compounds 6-9 were characterized by means of elemental analysis, electrospray ionization mass spectrometry, and NMR spectroscopy and in the case of 6-8 also by single-crystal X-ray diffraction analysis. The structures of N→Sn-coordinated stannaoxidoborates 6-8 consist of a spirobicyclic arrangement, with two six-membered SnB2O3 rings at the tin atom providing the new stannaoxidoborate [LSnB4O6R4](-) motif, which is compensated for by the proton atom coordinated to the Me2N group of the ligand L. The linear and thermal properties of 6-9 were studied with the help of electronic absorption spectra and differential scanning calorimetry. In addition, the presence of the nonsymmetric stannaoxidoborate SnB4O6 unit in 6, 7, and 9 prompted us to investigate their second-order nonlinear-optical properties.

  13. SAO RAS spectral classification of SN candidates

    NASA Astrophysics Data System (ADS)

    Fatkhullin, T. A.; Moskvitin, A. S.

    2016-08-01

    We observed five SN candidates (AT 2016eld, AT 2016eku, MASTER OT J225939.54+020859.6, AT 2016ekw and AT 2016elw) with the BTA/Scorpio-I on the night of August, 2/3. Direct images in the V band and long-slit spectra in the range of 3600-7600AA (resolution FWHM = 10A) were obtained.

  14. VERY LATE PHOTOMETRY OF SN 2011fe

    SciTech Connect

    Kerzendorf, W. E.; Taubenberger, S.; Seitenzahl, I. R.; Ruiter, A. J.

    2014-12-01

    The Type Ia supernova SN 2011fe is one of the closest supernovae of the past decades. Due to its proximity and low dust extinction, this object provides a very rare opportunity to study the extremely late time evolution (>900 days) of thermonuclear supernovae. In this Letter, we present our photometric data of SN 2011fe taken at an unprecedented late epoch of ≈930 days with GMOS-N mounted on the Gemini North telescope (g = 23.43 ± 0.28, r = 24.14 ± 0.14, i = 23.91 ± 0.18, and z = 23.90 ± 0.17) to study the energy production and retention in the ejecta of SN 2011fe. Together with previous measurements by other groups, our result suggests that the optical supernova light curve can still be explained by the full thermalization of the decay positrons of {sup 56}Co. This is in spite of theoretical predicted effects (e.g., infrared catastrophe, positron escape, and dust) that advocate a substantial energy redistribution and/or loss via various processes that result in a more rapid dimming at these very late epochs.

  15. Epitaxial Technologies for SiGeSn High Performance Optoelectronic Devices

    DTIC Science & Technology

    2015-04-29

    SiSn, GeSn, and SiGeSn on Si substrate has been demonstrated. Both SnCl4 and SnD4 are used as Sn precursors for GeSn and SiGeSn growth. So far 276...2014) 40 10 10 40 0 15 0 Number of round (Oct.~Dec. 2014) 5* 34 0 2 34 12 22 Number of round (Jan.~ Mar . 2015) 4** 0 0 43 5 0 0 Total Number...to Si substrate peak, while incorporating of Sn shifts the peak away from the Si substrate peak, which agrees well with theoretical study. Figure

  16. A facile inexpensive route for SnS thin film solar cells with SnS2 buffer

    NASA Astrophysics Data System (ADS)

    Gedi, Sreedevi; Minna Reddy, Vasudeva Reddy; Pejjai, Babu; Jeon, Chan-Wook; Park, Chinho; K. T., Ramakrishna Reddy

    2016-05-01

    Environment-friendly SnS based thin film solar cells with SnS2 as buffer layer were successfully fabricated from a facile inexpensive route, chemical bath deposition (CBD). Layer studies revealed that as-grown SnS and SnS2 films were polycrystalline; (1 1 1)/(0 0 1) peaks as the preferred orientation; 1.3 eV/2.8 eV as optical band gaps; and showed homogeneous microstructure with densely packed grains respectively. Ionization energy and electron affinity values were found by applying photoemission yield spectroscopy (PYS) to the CBD deposited SnS and SnS2 films for the first time. These values obtained as 5.3 eV and 4.0 eV for SnS films; 6.9 eV and 4.1 eV for SnS2 films. The band alignment of SnS/SnS2 junction showed TYPE-II heterostructure. The estimated conduction and valance band offsets were 0.1 eV and 1.6 eV respectively. The current density-voltage (J-V) measurements of the cell showed open circuit voltage (Voc) of 0.12 V, short circuit current density (Jsc) of 10.87 mA cm-2, fill factor (FF) of 39% and conversion efficiency of 0.51%.

  17. Electrochemical properties of Sn-decorated SnO nanobranches as an anode of Li-ion battery.

    PubMed

    Shin, Jeong Ho; Song, Jae Yong

    2016-01-01

    Sn-based oxide materials as an anode of lithium ion batteries (LIBs) suffer from the unavoidable mechanical stress originated from huge volume changes during lithiation/delithiation reactions. We synthesized the hierarchical SnO nanobranches (NBs) decorated with Sn nanoparticles on Cu current collector using a vapor transport method. The Sn-decorated SnO NBs as an anode of LIB showed good electrochemical performance with high reversible capacity retention of as high as 502 mAh/g and rate capability of 455 mAh/g at a current density of 2.0 A/g after 50 cycles. Through the morphological and crystal structure analyses after the charge and discharge processes, it was found that the morphology of Sn-decorated SnO NBs was transformed to nanoporous layered-structure, composed of Sn and lithium oxide, during the repeated lithiation/delithiation reactions. The free-volume of Sn-decorated SnO NBs and nanoporous layered-structure effectively accommodate the huge volume changes and enhance the electrochemical cyclability by facilitating the diffusion of Li-ions.

  18. Hierarchical Graphene-Encapsulated Hollow SnO2@SnS2 Nanostructures with Enhanced Lithium Storage Capability.

    PubMed

    Xu, Wangwang; Xie, Zhiqiang; Cui, Xiaodan; Zhao, Kangning; Zhang, Lei; Dietrich, Grant; Dooley, Kerry M; Wang, Ying

    2015-10-14

    Complex hierarchical structures have received tremendous attention due to their superior properties over their constitute components. In this study, hierarchical graphene-encapsulated hollow SnO2@SnS2 nanostructures are successfully prepared by in situ sulfuration on the backbones of hollow SnO2 spheres via a simple hydrothermal method followed by a solvothermal surface modification. The as-prepared hierarchical SnO2@SnS2@rGO nanocomposite can be used as anode material in lithium ion batteries, exhibiting excellent cyclability with a capacity of 583 mAh/g after 100 electrochemical cycles at a specific current of 200 mA/g. This material shows a very low capacity fading of only 0.273% per cycle from the second to the 100th cycle, lower than the capacity degradation of bare SnO2 hollow spheres (0.830%) and single SnS2 nanosheets (0.393%). Even after being cycled at a range of specific currents varied from 100 mA/g to 2000 mA/g, hierarchical SnO2@SnS2@rGO nanocomposites maintain a reversible capacity of 664 mAh/g, which is much higher than single SnS2 nanosheets (374 mAh/g) and bare SnO2 hollow spheres (177 mAh/g). Such significantly improved electrochemical performance can be attributed to the unique hierarchical hollow structure, which not only effectively alleviates the stress resulting from the lithiation/delithiation process and maintaining structural stability during cycling but also reduces aggregation and facilitates ion transport. This work thus demonstrates the great potential of hierarchical SnO2@SnS2@rGO nanocomposites for applications as a high-performance anode material in next-generation lithium ion battery technology.

  19. Photovoltaic properties of Cu2ZnSnS4 cells fabricated using ZnSnO and ZnSnO/CdS buffer layers

    NASA Astrophysics Data System (ADS)

    Tajima, Shin; Umehara, Mitsutaro; Mise, Takahiro

    2016-11-01

    To improve the photovoltaic properties of Cu2ZnSnS4 (CZTS) photovoltaic cells, we investigated the use of novel buffer layer materials. We found that Zn1- x Sn x O y fabricated by atomic layer deposition functioned as an effective buffer layer. The short-circuit current density increased by 10% because of a decrease in the absorption loss in the short-wavelength region. With Zn0.70Sn0.30O y layers, the conversion efficiency was 5.7%. To reduce interface recombination, a thin CdS layer was inserted between the ZnSnO and CZTS layers. The CZTS cells fabricated using ZnSnO/CdS double buffer layers showed a high open-circuit voltage of 0.81 V.

  20. Characterization of eutectic Sn-Bi solder joints

    NASA Astrophysics Data System (ADS)

    Mei, Z.; Morris, J. W.

    1992-06-01

    This report presents experimental results on 58Bi-42Sn solder joints, optical and SEM microstructures of their matrix and of their interface with copper, solidification behavior studied by differential scanning calorimetry, wettability to copper, creep, and low cycle fatigue. These results are discussed in comparison with 60Sn-40Pb solder, and with three low temperature solders, 52In-48Sn, 43Sn-43Pb-14Bi, and 40In-40Sn-20Pb. The 58Bi-42Sn solder paste with RMA flux wets Cu matrix with a wetting angle of 35° and had a 15° C undercooling during solidification. The constitutive equation of the steady state shear strain rate, and the Coffin-Manson relation constants for the low cycle shear fatigue life at 65° C have been determined. The test results show that this solder has the best creep resistance but the poorest fatigue strength compared with the other four solders.

  1. Premaximum observations of the type Ia SN 1990N

    NASA Technical Reports Server (NTRS)

    Leibundgut, Bruno; Kirshner, Robert P.; Filippenko, Alexei V.; Shields, Joseph C.; Foltz, Craig B.; Phillips, Mark M.; Sonneborn, George

    1991-01-01

    Spectroscopic and photometric observations of SN 1990N were obtained at ultraviolet and optical wavelengths, beginning 14 days before maximum light. The early observations reveal important differences from spectra of SN Ia's around maximum light. Photometry and spectroscopy obtained after maximum show that SN 1990N is a typical SN Ia and that most of the observed differences are due to the early epoch of the observations. The most significant characteristics are (1) the high velocities of Ca and Si up to 22,000 km/s; (2) the presence of Co and Fe 2 weeks before maximum; and (3) the more rapid increase in the UV flux compared to the optical. The most popular models for white dwarf deflagration that have provided the standard interpretation for SN Ia's at maximum light do not reproduce the high velocities of Ca II and Si II lines observed in SN 1990N.

  2. Superelastic properties of biomedical (Ti-Zr)-Mo-Sn alloys.

    PubMed

    Ijaz, Muhammad Farzik; Kim, Hee Young; Hosoda, Hideki; Miyazaki, Shuichi

    2015-03-01

    A new class of Ti-50Zr base biomedical superelastic alloys was developed in this study. The (Ti-Zr)-Mo-Sn alloys exhibited a shape memory effect and superelastic property by adjusting Mo and Sn contents. The (Ti-Zr)-1.5Mo-3Sn alloy revealed the most stable superelasticity among (Ti-Zr)-(1-2)Mo-(2-4)Sn alloys. The superelastic recovery strain showed a strong dependence on heat treatment temperature after cold working in the (Ti-Zr)-1.5Mo-3Sn alloy. The superelastic recovery strain increased as the heat treatment temperature increased although the critical stress for slip decreased. The (Ti-Zr)-1.5Mo-3Sn alloy heat treated at 1073K exhibited excellent superelastic properties with a large recovery strain as large as 7% which is due to the strong {001}β<110>β recrystallization texture.

  3. Similar K@Au10Sn10 Polyhedra in the Markedly Different Structures of KAu4Sn6 and KAu3Sn3. Syntheses and Characterization

    SciTech Connect

    Li, B.; Corbett, J.

    2008-03-18

    These compounds were synthesized by high-temperature reactions of the elements in welded Ta tubes and characterized by X-ray diffraction methods and linear muffin-tin orbital (LMTO) calculations. AAu{sub 4}Sn{sub 6} (A = K, Rb) have a new structural type (Fddd, Z = 8), and KAu{sub 3}Sn{sub 3} (Pmmn, Z = 2) is isostructural with SrAu{sub 3}In{sub 3}. Both orthorhombic structures contain similar condensed K{at}Au{sub 10}Sn{sub 10} polyhedral building blocks, which can be described as overall 6-8-6 arrangements of planar rings or, alternatively, as hexagonal prisms centered by K and augmented about the waists by 8-rings of Au and Sn. However, the 3D Au-Sn networks differ appreciably in both composition and the modes of condensation. In KAu{sub 3}Sn{sub 3}, the prisms stack by sharing both hexagonal faces with like neighbors along a, whereas those in KAu{sub 4}Sn{sub 6} condense in a complex zigzag network. Compared with related indium systems, the structure change from KAu{sub 4}In{sub 6} (P{sub 6}m2, Z = 1) to KAu{sub 4}Sn{sub 6} apparently illustrates the effect of complex factors such as atom size and valence electron counts on structure, whereas the SrAu{sub 3}In{sub 3} and KAu{sub 3}Sn{sub 3} pair are isotypic. Both compounds are Pauli-paramagnetic and inert to water at room temperature for several days. Tight-binding electronic structure (LMTO) calculations emphasize the dominance and strength of the heteroatomic Au-Sn bonding.

  4. Phonons Near Lattice Instabilities in Thermoelectric SnSe, SnTe, and PbTe

    NASA Astrophysics Data System (ADS)

    Delaire, Olivier; Li, Chen; Hong, Jiawang; Ma, Jie; May, Andrew; Bansal, Dipanshu; Ehlers, Georg; Chi, Songxue; Hong, Tao

    A number of high-performance thermoelectric materials are found in the vicinity of lattice instabilities, including PbTe, SnTe, SnSe, tetrahedrites, Cu2Se, among others. The large phonon anharmonicity found in such compounds suppresses the lattice thermal conductivity, a key aspect of their thermoelectric efficiency. In this presentation, we will discuss results from our recent investigations of phonons in these materials using inelastic neutron scattering and first-principles simulations, focusing on anharmonic effects near lattice instabilities. Commonalities will be highlighted, including connections between strong anharmonicity and the electronic structure and bonding.

  5. Giant resonances in {sup 112}Sn and {sup 124}Sn: Isotopic dependence of monopole resonance energies

    SciTech Connect

    Lui, Y.-W.; Youngblood, D.H.; Tokimoto, Y.; Clark, H.L.; John, B.

    2004-07-01

    The giant resonance region from 10 MeVSn and {sup 124}Sn has been studied with inelastic scattering of 240 MeV {alpha} particles at small angles including 0 deg. . Essentially, all of the expected isoscalar E0-E3 strength was located in both nuclei. The isotopic dependence of the giant monopole resonance energies was found to be consistent with relativistic and nonrelativistic calculations for interactions with K{sub NM}{approx}220-240 MeV.

  6. Macrosegregation and nucleation in undercooled Pb-Sn alloys

    NASA Technical Reports Server (NTRS)

    Degroh, Henry C., III

    1989-01-01

    A novel technique resulting in large undercoolings in bulk samples (23 g) of lead-tin alloys was developed. Samples of Pb-12.5 wt percent Sn, Pb-61.9 wt.% Sn, and Pb-77 wt.% Sn were processed with undercoolings ranging from 4 to 34 K and with cooling rates varying between 0.04 and 4 K/s. The nucleation behavior of the Pb-Sn system was found to be nonreciprocal. The solid Sn phase effectively nucleated the Pb phase of the eutectic; however, large undercoolings developed in Sn-rich eutectic liquid in the presence of the solid Pb phase. This phenomenon is believed to be mainly the result of differences in interfacial energies between solid Sn-eutectic liquid, and solid Pb-eutectic liquid rather than lattice misfit between Pb and Sn. Large amounts of segregation developed in the highly undercooled eutectic ingots. This macrosegregation was found to increase as undercooling increases. Macrosegregation in these undercooled eutectic alloys was found to be primarily due to a sink/float mechanism and the nucleation behavior of the alloy. Lead-rich dendrites are the primary phase in the undercooled eutectic system. These dendrites grow rapidly into the undercooled bath and soon break apart due to recalescence and Sn enrichment of the liquid. These fragmented Pb dendrites are then free to settle to the bottom portion of the ingot causing the macrosegregation observed in this study. A eutectic Pb-Sn alloy undercooled 20 K and cooled at 4 K/s had a composition of about Pb-72 wt.% Sn at the top and 55% Sn at the bottom.

  7. Macrosegregation and nucleation in undercooled Pb-Sn alloys

    NASA Technical Reports Server (NTRS)

    Degroh, Henry C., III

    1989-01-01

    A technique resulting in large undercoolings in bulk samples (23g) of lead-tin alloys was developed. Samples of Pb-12.5 wt percent Sn, Pb-61 wt percent Sn, and Pb-77 wt percent Sn were processed with undercoolings ranging from 4 to 34 K and with cooling rates varying between 0.04 and 4 K/sec. The nucleation behavior of the Pb-Sn system was found to be nonreciprocal. The solid Sn phase effectively nucleated the Pb phase of the eutectic; however, large undercoolings developed in Sn-rich eutectic liquid in the presence of the solid Pb phase. This phenomenon is believed to be mainly the result of differences in interfacial energies between solid Sn-eutectic liquid, and solid Pb-eutectic liquid rather than lattice misfit between Pb and Sn. Large amounts of segregation developed in the highly undercooled eutectic ingots. This macrosegregation was found to increase as undercooling increases. Macrosegregation in these undercooled eutectic alloys was found to be primarily due to a sink/float mechanism and the nucleation behavior of the alloy. Lead-rich dendrites are the primary phase in the undercooled eutectic system. These dendrites grow rapidly into the undercooled bath and soon break apart due to recalescence and Sn enrichment of the liquid. These fragmented Pb dendrites are then free to settle to the bottom portion of the ingot causing the macrosegregation observed in this study. A eutectic Pb-Sn alloy undercooled 20 K and cooled at 4 K/sec had a composition of about Pb-72 wt percent Sn at the top and 55 percent Sn at the bottom.

  8. Pressureless Bonding by Use of Cu and Sn Mixed Nanoparticles

    NASA Astrophysics Data System (ADS)

    Ishizaki, Toshitaka; Watanabe, Ryota

    2014-12-01

    Because of high thermal and electrical conductivity, high melting point, and low cost, bonding by sintering of Cu nanoparticles is promising as a new method to replace the Pb-rich solders currently used in high-temperature applications. However, it is difficult to achieve sufficient strength by using this method because, in the absence of applied pressure, oxidized surfaces inhibit sintering. In this study, we report pressureless bonding of Cu plates with Ni layers by use of Cu and Sn mixed nanoparticles. Bonding was achieved without pressure from 250°C to 350°C in hydrogen by use of pure Cu nanoparticles, and by using mixtures of Cu and Sn nanoparticles in which the amount of Sn varied from 10 to 50 wt.%. The highest strength bonds were obtained by use of Cu-10 wt.% Sn mixed nanoparticles, because the sinterability of the Cu nanoparticles is enhanced by diffusion of Sn into Cu to form an appropriate amount of Cu-Sn intermetallic compounds (IMC) and diminish microvoids. However, when the amount of Sn was greater than 10 wt.%, Cu-Sn IMC were formed to such an extent that the significant reduction of Cu-rich layers led to reduced strength. When the bonding temperature was 350°C, Sn diffused into Cu so much that microvoids were formed in the Sn-rich layer. Because the number of microvoids increased as the amount of Sn was increased, the shear strength could not be enhanced by bonding at higher temperature when the amount of Sn was greater than 30 wt.%.

  9. Cajal bodies and snRNPs - friends with benefits.

    PubMed

    Staněk, David

    2016-09-14

    Spliceosomal snRNPs are complex particles that proceed through a fascinating maturation pathway. Several steps of this pathway are closely linked to nuclear non-membrane structures called Cajal bodies. In this review, I summarize the last 20 y of research in this field. I primarily focus on snRNP biogenesis, specifically on the steps that involve Cajal bodies. I also evaluate the contribution of the Cajal body in snRNP quality control and discuss the role of snRNPs in Cajal body formation.

  10. Synthesis and characterization of (Sn,Zn)O alloys

    DOE PAGES

    Bikowski, Andre; Holder, Aaron; Peng, Haowei; ...

    2016-09-29

    SnO exhibits electrical properties that render it promising for solar energy conversion applications, but it also has a strongly indirect band gap. Recent theoretical calculations predict that this disadvantage can be mitigated by isovalent alloying with other group-II oxides such as ZnO. Here, we synthesized new metastable isovalent (Sn,Zn)O alloy thin films by combinatorial reactive co-sputtering and characterized their structural, optical and electrical properties. The alloying of ZnO into SnO leads to a change of the valence state of the tin from Sn0 via Sn2+ to Sn4+, which can be counteracted by reducing the oxygen partial pressure during the deposition.more » The optical characterization of the smooth <10 at. % Sn1-xZnxO thin films showed an increase in the absorption coefficient in the range from 1 to 2 eV, which is consistent with the theoretical predictions for the isovalent alloying. However, the experimentally observed alloying effect may be convoluted with the effect of local variations of the Sn oxidation state. As a result, this effect would have to be minimized to improve the (Sn,Zn)O optical and electrical properties for their use as absorbers in solar energy conversion applications.« less

  11. Swift/XRT monitoring observations of SN2011dh

    NASA Astrophysics Data System (ADS)

    Campana, S.; Burrows, D. N.

    2011-06-01

    SN 2011dh (Silverman et al. 2001, Atel #3398; Reiland et al. 2011, CBET #2736) has been monitored by Swift with 14 observations up to now. Here we report on the first 6 observations, spanning the June 3-6, 2011 interval, with 21.2 ks effective exposure time. An X-ray source was positively detected at the location of SN 2011dh with a high signal-to-noise ratio (S/N~8). This source was not present in deep observations taken in 2007, and we tentatively associate it with SN 2001dh, in agreement with Margutti & Soderberg (2011, ATel #3400) results.

  12. Process for the manufacture of 117Sn diethylenetriaminepentaacetic acids

    DOEpatents

    Srivastava, Suresh C.; Li, Zizhong; Meinken, George

    2003-01-01

    Novel methods are provided for the manufacture of .sup.117m Sn(Sn.sup.4+) DTPA. The method allows the use of DTPA, a toxic chelating agent, in an approximately 1:1 ratio to .sup.117m Sn(Sn.sup.4+) via either aqueous conditions, or using various organic solvents, such as methylene chloride. A pharmaceutical composition manufactured by the novel method is also provided, as well as methods for treatment of bone tumors and pain associated with bone cancer using the pharmaceutical composition of the invention.

  13. Synthesis and characterization of (Sn,Zn)O alloys

    SciTech Connect

    Bikowski, Andre; Holder, Aaron; Peng, Haowei; Siol, Sebastian; Norman, Andrew; Lany, Stephan; Zakutayev, Andriy

    2016-09-29

    SnO exhibits electrical properties that render it promising for solar energy conversion applications, but it also has a strongly indirect band gap. Recent theoretical calculations predict that this disadvantage can be mitigated by isovalent alloying with other group-II oxides such as ZnO. Here, we synthesized new metastable isovalent (Sn,Zn)O alloy thin films by combinatorial reactive co-sputtering and characterized their structural, optical and electrical properties. The alloying of ZnO into SnO leads to a change of the valence state of the tin from Sn0 via Sn2+ to Sn4+, which can be counteracted by reducing the oxygen partial pressure during the deposition. The optical characterization of the smooth <10 at. % Sn1-xZnxO thin films showed an increase in the absorption coefficient in the range from 1 to 2 eV, which is consistent with the theoretical predictions for the isovalent alloying. However, the experimentally observed alloying effect may be convoluted with the effect of local variations of the Sn oxidation state. As a result, this effect would have to be minimized to improve the (Sn,Zn)O optical and electrical properties for their use as absorbers in solar energy conversion applications.

  14. SnO2 nanoparticle-functionalized boron nitride nanotubes.

    PubMed

    Zhi, Chunyi; Bando, Yoshio; Tang, Chengchun; Golberg, Dmitri

    2006-05-04

    Boron nitride nanotubes (BNNTs) were synthesized by a carbon-free chemical vapor deposition method using boron and metal oxide as reactants. Then SnO(2) nanoparticles were functionalized on them via a simple wet chemistry method. Detailed transmission electron microscopy (TEM) observations reveal that SnO(2) nanoparticles may cover the tube surface or be encapsulated in tube channels. The lattice distances of both BNNT and SnO(2) have been changed due to the strong interactions between them. The band gap energy of SnO(2) particles is found enlarged due to the size effect and interaction with BNNTs.

  15. Real-time study of electromigration in Sn Blech structure

    NASA Astrophysics Data System (ADS)

    Ho, C. E.; Hsieh, W. Z.; Yang, C. H.; Lee, P. T.

    2016-12-01

    Electromigration has become a critical issue for reliability in Sn-based conducting materials that are used in advanced microelectronic packages with micro-joint integration. In this study, a Blech structure was used to characterize the Sn electromigration behavior of various strip lengths (L0 = 10-100 μm). We established a mathematical model based on the fundamental electromigration theory to describe the correlation between the residual strip length (L) and the current stressing time (t). A three-stage mechanism was proposed to rationalize the Sn electromigration in the Blech structure. A good agreement between the mathematical model and experimental data was obtained, advancing our understanding of Sn electromigration.

  16. Thermodynamic, Kinetic, Structural, and Computational Studies of the Ph3Sn-H, Ph3Sn-SnPh3, and Ph3Sn-Cr(CO)3C5Me5 Bond Dissociation Enthalpies.

    PubMed

    Cai, Xiaochen; Majumdar, Subhojit; Fortman, George C; Koppaka, Anjaneyulu; Serafim, Leonardo; Captain, Burjor; Temprado, Manuel; Hoff, Carl D

    2016-10-05

    The kinetics of the reaction of Ph3SnH with excess •Cr(CO)3C5Me5 = •Cr, producing HCr and Ph3Sn-Cr, was studied in toluene solution under 2-3 atm CO pressure in the temperature range of 17-43.5 °C. It was found to obey the rate equation d[Ph3Sn-Cr]/dt = k[Ph3SnH][•Cr] and exhibit a normal kinetic isotope effect (kH/kD = 1.12 ± 0.04). Variable-temperature studies yielded ΔH(‡) = 15.7 ± 1.5 kcal/mol and ΔS(‡) = -11 ± 5 cal/(mol·K) for the reaction. These data are interpreted in terms of a two-step mechanism involving a thermodynamically uphill hydrogen atom transfer (HAT) producing Ph3Sn• and HCr, followed by rapid trapping of Ph3Sn• by excess •Cr to produce Ph3Sn-Cr. Assuming an overbarrier of 2 ± 1 kcal/mol in the HAT step leads to a derived value of 76.0 ± 3.0 kcal/mol for the Ph3Sn-H bond dissociation enthalpy (BDE) in toluene solution. The reaction enthalpy of Ph3SnH with excess •Cr was measured by reaction calorimetry in toluene solution, and a value of the Sn-Cr BDE in Ph3Sn-Cr of 50.4 ± 3.5 kcal/mol was derived. Qualitative studies of the reactions of other R3SnH compounds with •Cr are described for R = (n)Bu, (t)Bu, and Cy. The dehydrogenation reaction of 2Ph3SnH → H2 + Ph3SnSnPh3 was found to be rapid and quantitative in the presence of catalytic amounts of the complex Pd(IPr)(P(p-tolyl)3). The thermochemistry of this process was also studied in toluene solution using varying amounts of the Pd(0) catalyst. The value of ΔH = -15.8 ± 2.2 kcal/mol yields a value of the Sn-Sn BDE in Ph3SnSnPh3 of 63.8 ± 3.7 kcal/mol. Computational studies of the Sn-H, Sn-Sn, and Sn-Cr BDEs are in good agreement with experimental data and provide additional insight into factors controlling reactivity in these systems. The structures of Ph3Sn-Cr and Cy3Sn-Cr were determined by X-ray crystallography and are reported. Mechanistic aspects of oxidative addition reactions in this system are discussed.

  17. Effect of pressure on the Curie temperature of Mn2RuSn and Mn2PdSn

    NASA Astrophysics Data System (ADS)

    Adachi, Y.; Watanabe, T.; Kanomata, T.; Hayasaka, M.; Endo, K.; Nishihara, H.; Xu, X.; Kainuma, R.

    2017-04-01

    Effect of pressure on the Curie temperature TC of the Mn-rich Heusler alloys Mn2RuSn and Mn2PdSn has been investigated by measuring the temperature dependence of initial permeability at various pressures up to 10 kbar. It was found that the Curie temperatures of Mn2RuSn and Mn2PdSn decrease with increasing pressure. The pressure derivatives of TC were estimated to be -0.59 K/kbar for Mn2RuSn and -0.80 K/kbar for Mn2PdSn. On the basis of the experimental results, the relationship between the magnetic transition temperature and the Mn-Mn distance is discussed.

  18. High-temperature heat capacity of stannates Pr2Sn2O7 and Nd2Sn2O7

    NASA Astrophysics Data System (ADS)

    Denisova, L. T.; Irtyugo, L. A.; Beletskii, V. V.; Denisov, V. M.

    2016-07-01

    Oxide compounds Pr2Sn2O7 and Nd2Sn2O7 have been obtained by solid-phase synthesis. The effect of temperature on the heat capacity of Pr2Sn2O7 (360-1045 K) and Nd2Sn2O7 (360-1030 K) has been studied using differential scanning calorimetry. The thermodynamic properties of the compounds (changes in enthalpy, entropy, and the reduced Gibbs energy) have been calculated by the experimental data of C p = f( T).

  19. Combination of SN-38 with gefitinib or imatinib overcomes SN-38-resistant small-cell lung cancer cells.

    PubMed

    Takigawa, Nagio; Takeyama, Masami; Kozuki, Toshiyuki; Shibayama, Takuo; Hisamoto, Akiko; Kiura, Katsuyuki; Tada, Atsuhiko; Hotta, Katsuyuki; Umemura, Shigeki; Ohashi, Kadoaki; Fujiwara, Yoshiro; Takata, Saburo; Ichihara, Eiki; Osawa, Masahiro; Tabata, Masahiro; Tanimoto, Mitsune; Takahashi, Kiyoshi

    2007-05-01

    Irinotecan is one of the effective anticancer agents for small-cell lung cancer (SCLC) and 7-ethyl-10-hydroxy-campthothecin (SN-38) is an active metabolite of irinotecan. Gefitinib and imatinib are tyrosine kinase inhibitors which have clinical activities in several malignancies and they are also potent inhibitors of breast cancer resistance protein (BCRP) transporter, which confers the resistance of topoisomerase I inhibitors including SN-38 and topotecan. The cytotoxicity of SN-38, gefitinib and imatinib for the SN-38-resistant cells (SBC-3/SN-38) from human SCLC cells, SBC-3, was evaluated using AlamarBlue assay. The drug concentration required to inhibit the growth of tumor cells by 50% (IC50) for 96-h exposure was used to evaluate the cytotoxicity. BCRP expression was determined by Western blotting and immunofluorescence staining. Intracellular topotecan accumulation was evaluated by flow cytometry. No differences were observed in the IC50 values (mean +/- SD) of the tyrosine kinase inhibitors between the SBC-3 cells and the SBC-3/SN-38 cells: 15+/-1.6 and 12+/-2.8 microM of gefitinib, respectively; 15+/-0.51 and 14+/-3.9 microM of imatinib, respectively. The SBC-3/SN-38 was 9.5-fold more resistant to SN-38 than the parental SBC-3. The SBC-3/SN-38 restored sensitivity to SN-38 when combined with 8 microM gefitinib or 8 microM imatinib, even though the IC50 values of SN-38 combined with gefitinib or imatinib in the SBC-3 cells did not change. BCRP was equally overexpressed in the SBC-3/SN-38 with and without gefitinib or imatinib. In addition, the BCRP expression on the SBC-3/SN-38 cell membrane with and without gefitinib seemed to be equal. Gefitinib increased intracellular accumulation of topotecan in the SBC-3/SN-38 cells. Gefitinib or imatinib reversed SN-38-resistance in these SCLC cells, possibly due to intracellular accumulation of SN-38 without any change in BCRP quantity. Irinotecan with gefitinib or imatinib might be effective for SCLC refractory to

  20. High-pressure high-temperature crystal growth of equiatomic rare earth stannides RENiSn and REPdSn

    SciTech Connect

    Heymann, Gunter; Heying, Birgit; Rodewald, Ute Ch.; Janka, Oliver; Huppertz, Hubert; Pöttgen, Rainer

    2016-04-15

    The two series of equiatomic rare earth (RE) stannides RENiSn and REPdSn were systematically studied with respect to high-pressure modifications. The normal-pressure (NP) low-temperature (LT) modifications were synthesized by arc-melting and subsequently treated under high-pressure (P{sub max}=11.5 GPa) and high-temperature (T{sub max}=1570 K) conditions in a Walker-type multi-anvil press. The pressure and temperature conditions were systematically varied in order to improve the crystallization conditions. The new ZrNiAl-type high-pressure modifications HP-RENiSn (RE=Sc, Y, La, Gd–Lu) and HP-REPdSn (RE=Y, Sm–Dy) were obtained in 80 mg quantities, several of them in X-ray pure form. Some of the REPdSn stannides with the heavy rare earth elements show high-temperature (HT) modifications. The structures of HP-ScNiSn, HP-GdNiSn, HP-DyNiSn (both ZrNiAl-type), NP-YbNiSn, and HT-ErPdSn (both TiNiSi-type) were refined from single crystal diffractometer data, indicating full ordering of the transition metal and tin sites. TiNiSi-type NP-EuPdSn transforms to MgZn{sub 2}-type HP-EuPdSn: P6{sub 3}/mmc, a=588.5(2), c=917.0(3) pm, wR2=0.0769, 211 F{sup 2} values, 11 variables. The structure refinement indicated statistical occupancy of the palladium and tin sites on the tetrahedral network. The X-ray pure high-pressure phases were studied with respect to their magnetic properties. HP-YPdSn is a Pauli paramagnet. The susceptibility data of HP-TbNiSn, HP-DyNiSn, HP-GdPdSn, and HP-TbPdSn show experimental magnetic moments close to the free ion values of RE{sup 3+} and antiferromagnetic ordering at low temperature with the highest Néel temperature of 15.8 K for HP-TbPdSn. HP-SmPdSn shows the typical Van Vleck type behavior along with antiferromagnetic ordering at T{sub N}=5.1 K. HP-EuPdSn shows divalent europium and antiferromagnetic ordering at 8.9 K followed by a spin reorientation at 5.7 K. - Graphical abstract: Packing of the polyhedra in the high-pressure phase of EuPdSn

  1. 'Pd20Sn13' revisited: crystal structure of Pd6.69Sn4.31.

    PubMed

    Klein, Wilhelm; Jin, Hanpeng; Hlukhyy, Viktor; Fässler, Thomas F

    2015-07-01

    The crystal structure of the title compound was previously reported with composition 'Pd20Sn13' [Sarah et al. (1981 ▸). Z. Metallkd, 72, 517-520]. For the original structure model, as determined from powder X-ray data, atomic coordinates from the isostructural compound Ni13Ga3Ge6 were transferred. The present structure determination, resulting in a composition Pd6.69Sn4.31, is based on single crystal X-ray data and includes anisotropic displacement parameters for all atoms as well as standard uncertainties for the atomic coordinates, leading to higher precision and accuracy for the structure model. Single crystals of the title compound were obtained via a solid-state reaction route, starting from the elements. The crystal structure can be derived from the AlB2 type of structure after removing one eighth of the atoms at the boron positions and shifting adjacent atoms in the same layer in the direction of the voids. One atomic site is partially occupied by both elements with a Pd:Sn ratio of 0.38 (3):0.62 (3). One Sn and three Pd atoms are located on special positions with site symmetry 2. (Wyckoff letter 3a and 3b).

  2. Seismic Attenuation of Sn phase beneath the Ordos Plateau

    NASA Astrophysics Data System (ADS)

    Pan, J.; Chen, Y.; Chen, Y. J.; Sandvol, E. A.

    2015-12-01

    We have used attenuation tomography of the regional seismic phase Sn to characterize the uppermost mantle shear wave Q (Qs) over a large part of northern China. The Sn phase is often a difficult phase to identify for continental paths since it usually has a relatively small amplitude compared to the regional phase Lg. Also Sn is often a high frequency phase and thus it is often blocked for paths that cross tectonically active regions. We have used the unprecedented amount of national network and temporary stations that were deployed across China over the last five years to be able to successfully identify Sn phases and use them to measure Sn Q using a reverse two station method. The initial waveforms was filtered with the frequency band of 0.5-3 Hz, and Sn time window was computed using velocities range of 4.3-4.7 km/s. Sn waveforms from 43 earthquakes recorded by 63 stations were manually picked out in order to obtain the ratio of Sn amplitude from each two-station pair. Those ratios describe Sn attenuation along each inter-station path. We have used to approaches: the two-station method was used to isolate factors, such as source, and earth response, and calculate inter-station Q value. And LSQR algorithm was used to obtain tomographically map lateral variations in Sn Q. We find relatively low uppermost mantle Q anomaly is consistent with the Weihe graben, a young active rifting system with hot uppermantle. Low Q value also appears in the southern part of the Ordos plateau, which shows the opposite result to the characteristics of lithospheric mantle in a craton. This may be a result of scattering attenuation of Sn or possible thermal erosion of the lithospheric root beneath the southern Ordos.

  3. Swift Observations of SN 2007aa

    NASA Astrophysics Data System (ADS)

    Immler, S.; Brown, P. J.; Milne, P.

    2007-03-01

    Swift Ultraviolet/Optical Telescope (UVOT) and X-Ray Telescope (XRT) observed the type II SN 2007aa (CBET #850, IAUC #8814) on 2007-02-24.63 UT. The following UVOT magnitudes were measured: V = 15.8 (322 s exposure time), B = 16.4 (367 s), U = 16.9 (367 s), UVW1 [181-321nm] = 18.6 (737 s), UVM2 [166-268 nm] > 19.5 (3-sigma upper limit; 236 s), and UVW2 [112-264 nm] = 19.7 (725 s). The magnitudes have not been corrected for extinction.

  4. Effect on properties of 42Sn58Bi solder joint by adding the 96.5Sn3.5Ag

    NASA Astrophysics Data System (ADS)

    Tang, Qinghua; Pan, Xiaoguang; Wu, C. M. L.; Chan, Y. C.

    2000-05-01

    The different composition in 42Sn58Bi and 96.5Sn3.5Ag system has been studied. The reflow conditions of various composition pastes were studied, and a suitable adding of Sn-Ag paste could raise the soldering temperature of paste. It was found that the shear tensile strength of solder joint could be improved after adding suitable Sn-Ag to Sn-Bi paste by testing the solder joint tension. The thermal fatigue properties were studied through performed thermal annealing and thermal shocking. The shear tensile strength of solder joints for adding suitable Sn-Ag is higher than the pure Sn- Bi after thermal shocking. The solder property, mechanical and fatigue failure properties of solder joint for adding suitable Sn-Ag could be improved. It was found that suitable Sn-Ag could decrease the porosity in Sn-Bi solder joint thought X-ray and SEM analysis.

  5. Thermodynamic understanding of Sn whisker growth on the Cu surface in Cu(top)-Sn(bottom) bilayer system upon room temperature aging

    SciTech Connect

    Huang, Lin; Jian, Wei; Lin, Bing; Wang, Jiangyong; Wen, Yuren; Gu, Lin

    2015-06-07

    Sn whiskers are observed by scanning electron microscope on the Cu surface in Cu(top)-Sn(bottom) bilayer system upon room temperature aging. Only Cu{sub 6}Sn{sub 5} phase appears in the X-ray diffraction patterns and no Sn element is detected in the Cu sublayer by scanning transmission electron microscopy. Based on the interfacial thermodynamics, the intermetallic Cu{sub 6}Sn{sub 5} compound phase may form directly at the Sn grain boundary. Driven by the stress gradient during the formation of Cu{sub 6}Sn{sub 5} compound at Sn grain boundaries, Sn atoms segregate onto the Cu surface and accumulate to form Sn whisker.

  6. SrZn{sub 2}Sn{sub 2} and Ca{sub 2}Zn{sub 3}Sn{sub 6} - two new Ae-Zn-Sn polar intermetallic compounds (Ae: alkaline earth metal)

    SciTech Connect

    Stegmaier, Saskia; Faessler, Thomas F.

    2012-08-15

    SrZn{sub 2}Sn{sub 2} and Ca{sub 2}Zn{sub 3}Sn{sub 6}, two closely related new polar intermetallic compounds, were obtained by high temperature reactions of the elements. Their crystal structures were determined with single crystal XRD methods, and their electronic structures were analyzed by means of DFT calculations. The Zn-Sn structure part of SrZn{sub 2}Sn{sub 2} comprises (anti-)PbO-like {l_brace}ZnSn{sub 4/4}{r_brace} and {l_brace}SnZn{sub 4/4}{r_brace} layers. Ca{sub 2}Zn{sub 3}Sn{sub 6} shows similar {l_brace}ZnSn{sub 4/4}{r_brace} layers and {l_brace}Sn{sub 4}Zn{r_brace} slabs constructed of a covalently bonded Sn scaffold capped by Zn atoms. For both phases, the two types of layers are alternatingly stacked and interconnected via Zn-Sn bonds. SrZn{sub 2}Sn{sub 2} adopts the SrPd{sub 2}Bi{sub 2} structure type, and Ca{sub 2}Zn{sub 3}Sn{sub 6} is isotypic to the R{sub 2}Zn{sub 3}Ge{sub 6} compounds (R=La, Ce, Pr, Nd). Band structure calculations indicate that both SrZn{sub 2}Sn{sub 2} and Ca{sub 2}Zn{sub 3}Sn{sub 6} are metallic. Analyses of the chemical bonding with the electron localization function (ELF) show lone pair like basins at Sn atoms and Zn-Sn bonding interactions between the layers for both title phases, and covalent Sn-Sn bonding within the {l_brace}Sn{sub 4}Zn{r_brace} layers of Ca{sub 2}Zn{sub 3}Sn{sub 6}. - Graphical abstract: Crystal structures of the new Ae-Zn-Sn polar intermetallic phases SrZn{sub 2}Sn{sub 2} and Ca{sub 2}Zn{sub 3}Sn{sub 6}. Highlights: Black-Right-Pointing-Pointer New polar intermetallic phases SrZn{sub 2}Sn{sub 2} and Ca{sub 2}Zn{sub 3}Sn{sub 6}. Black-Right-Pointing-Pointer Obtained by high temperature reactions of the elements. Black-Right-Pointing-Pointer Single crystal XRD structure determination and DFT electronic structure calculations. Black-Right-Pointing-Pointer Closely related crystal and electronic structures. Black-Right-Pointing-Pointer Metallic conductivity coexisting with lone pairs and covalent bonding

  7. Reactivity of dicoordinated stannylones (Sn0) versus stannylenes (SnII): an investigation using DFT-based reactivity indices.

    PubMed

    Broeckaert, Lies; Frenking, Gernot; Geerlings, Paul; De Proft, Frank

    2013-10-07

    The reactivity of dicoordinated Sn(0) compounds, stannylones, is probed using density functional theory (DFT)-based reactivity indices and compared with the reactivity of dicoordinated Sn(II) compounds, stannylenes. For the former compounds, the influence of different types of electron-donating ligands, such as cyclic and acyclic carbenes, stannylenes and phosphines, on the reactivity of the central Sn atom is analyzed in detail. Sn(0) compounds are found to be relatively soft systems with a high nucleophilicity, and the plots of the Fukui function f(-) for an electrophilic attack consistently predict the highest reactivity on the Sn atom. Next, complexes of dicoordinated Sn compounds with different Lewis acids of variable hardness are computed. In a first part, the double-base character of stannylones is demonstrated in interactions with the hardest Lewis acid H(+). Both the first and second proton affinities (PAs) are high and are well correlated with the atomic charge on the Sn atom, probing its local hardness. These observations are also in line with electrostatic potential plots that demonstrate that the tin atom in Sn(0) compounds bears a higher negative charge in comparison to Sn(II) compounds. Stannylones and stannylenes can be distinguished from each other by the partial charges at Sn and by various reactivity indices. It also becomes clear that there is a smooth transition between the two classes of compounds. We furthermore demonstrate both from DFT-based reactivity indices and from energy decomposition analysis, combined with natural orbitals for chemical valence (EDA-NOCV), that the monocomplexed stannylones are still nucleophilic and as reactive towards a second Lewis acid as towards the first one. The dominating interaction is a strong σ-type interaction from the Sn atom towards the Lewis acid. The interaction energy is higher for complexes with the cation Ag(+) than with the non-charged electrophiles BH(3), BF(3), and AlCl(3).

  8. Spectropolarimetry of the Type IIb SN 2008aq*

    NASA Astrophysics Data System (ADS)

    Stevance, H. F.; Maund, J. R.; Baade, D.; Höflich, P.; Patat, F.; Spyromilio, J.; Wheeler, J. C.; Clocchiatti, A.; Wang, L.; Yang, Y.; Zelaya, P.

    2016-09-01

    We present optical spectroscopy and spectropolarimetry of the Type IIb SN 2008aq 16-d and 27-d post-explosion. The spectrum of SN 2008aq remained dominated by Hα P Cygni profile at both epochs, but showed a significant increase in the strength of the helium features, which is characteristic of the transition undergone by supernovae between Type IIb and Type Ib. Comparison of the spectra of SN 2008aq to other Type IIb SNe (SN 1993J, SN 2011dh, and SN 2008ax) at similar epochs revealed that the helium lines in SN 2008aq are much weaker, suggesting that its progenitor was stripped to a lesser degree. SN 2008aq also showed significant levels of continuum polarization at pcont = 0.70 (±0.22) per cent in the first epoch, increasing to pcont = 1.21 (±0.33) per cent by the second epoch. Moreover, the presence of loops in the q - u planes of Hα and He I in the second epoch suggests a departure from axial symmetry.

  9. Do π-conjugative effects facilitate SN2 reactions?

    PubMed

    Wu, Chia-Hua; Galabov, Boris; Wu, Judy I-Chia; Ilieva, Sonia; Schleyer, Paul von R; Allen, Wesley D

    2014-02-26

    Rigorous quantum chemical investigations of the SN2 identity exchange reactions of methyl, ethyl, propyl, allyl, benzyl, propargyl, and acetonitrile halides (X = F(-), Cl(-)) refute the traditional view that the acceleration of SN2 reactions for substrates with a multiple bond at Cβ (carbon adjacent to the reacting Cα center) is primarily due to π-conjugation in the SN2 transition state (TS). Instead, substrate-nucleophile electrostatic interactions dictate SN2 reaction rate trends. Regardless of the presence or absence of a Cβ multiple bond in the SN2 reactant in a series of analogues, attractive Cβ(δ(+))···X(δ(-)) interactions in the SN2 TS lower net activation barriers (E(b)) and enhance reaction rates, whereas repulsive Cβ(δ(-))···X(δ(-)) interactions increase E(b) barriers and retard SN2 rates. Block-localized wave function (BLW) computations confirm that π-conjugation lowers the net activation barriers of SN2 allyl (1t, coplanar), benzyl, propargyl, and acetonitrile halide identity exchange reactions, but does so to nearly the same extent. Therefore, such orbital interactions cannot account for the large range of E(b) values in these systems.

  10. THE PRODUCTION RATE OF SN Ia EVENTS IN GLOBULAR CLUSTERS

    SciTech Connect

    Washabaugh, Pearce C.; Bregman, Joel N. E-mail: jbregman@umich.edu

    2013-01-01

    In globular clusters, dynamical evolution produces luminous X-ray emitting binaries at a rate about 200 times greater than in the field. If globular clusters also produce SN Ia at a high rate, it would account for many of the SN Ia production in early-type galaxies and provide insight into their formation. Here we use archival Hubble Space Telescope (HST) images of nearby galaxies that have hosted an SN Ia to examine the rate at which globular clusters produce these events. The location of the SN Ia is registered on an HST image obtained before the event or after the supernova (SN) faded. Of the 36 nearby galaxies examined, 21 had sufficiently good data to search for globular cluster hosts. None of the 21 SNe have a definite globular cluster counterpart, although there are some ambiguous cases. This places an upper limit to the enhancement rate of SN Ia production in globular clusters of about 42 at the 95% confidence level, which is an order of magnitude lower than the enhancement rate for luminous X-ray binaries. Even if all of the ambiguous cases are considered as having a globular cluster counterpart, the upper bound for the enhancement rate is 82 at the 95% confidence level, still a factor of several below that needed to account for half of the SN Ia events. Barring unforeseen selection effects, we conclude that globular clusters are not responsible for producing a significant fraction of the SN Ia events in early-type galaxies.

  11. Field quality study in Nb(3)Sn accelerator magnets

    SciTech Connect

    Kashikhin, V.V.; Ambrosio, G.; Andreev, N.; Barzi, E.; Bossert, R.; DiMarco, J.; Kashikhin, V.S.; Lamm, M.; Novitski, I.; Schlabach, P.; Velev, G.; Yamada, R.; Zlobin, A.V.; /Fermilab

    2005-05-01

    Four nearly identical Nb{sub 3}Sn dipole models of the same design were built and tested at Fermilab. It provided a unique opportunity of systematic study the field quality effects in Nb{sub 3}Sn accelerator magnets. The results of these studies are reported in the paper.

  12. Microstructural evolution of eutectic Au-Sn solder joints

    SciTech Connect

    Song, Ho Geon

    2002-05-01

    Current trends toward miniaturization and the use of lead(Pb)-free solder in electronic packaging present new problems in the reliability of solder joints. This study was performed in order to understand the microstructure and microstructural evolution of small volumes of nominally eutectic Au-Sn solder joints (80Au-20Sn by weight), which gives insight into properties and reliability.

  13. The Influence of Cu on Metastable NiSn4 in Sn-3.5Ag- xCu/ENIG Joints

    NASA Astrophysics Data System (ADS)

    Belyakov, S. A.; Gourlay, C. M.

    2016-01-01

    We have investigated the effect of small amounts of Cu on suppression of metastable βSn-NiSn4 eutectic growth in solder joints between Sn-3.5Ag- xCu solders and Ni-based substrates. For Sn-3.5Ag/electroless nickel immersion gold (ENIG) and Sn-3.5Ag/Ni solder joints we showed that the eutectic mixture contains βSn, Ag3Sn, and metastable NiSn4. It was found that addition of only 0.005 wt.% Cu to Sn-3.5Ag- xCu/ENIG or Sn-3.5Ag- xCu/Ni joints promoted formation of a stable βSn-Ni3Sn4 eutectic and that both Ni3Sn4 and NiSn4 occur in the eutectic at this Cu level. We also showed that for complete prevention of formation of metastable NiSn4 during eutectic solidification of the solder joint, addition of at least 0.3 wt.% Cu was required.

  14. Large-scale solid-state synthesis of Sn-SnO2 nanoparticles from layered SnO by sunlight: a material for dye degradation in water by photocatalytic reaction.

    PubMed

    Sinha, Arun Kumar; Pradhan, Mukul; Sarkar, Sougata; Pal, Tarasankar

    2013-03-05

    Phase pure spherical Sn-SnO2 nanoparticles (∼ 50 nm) in gram level have been synthesized from well-defined SnO microplates (∼ 2.0 μm) using focused solar irradiation. The first step of the reaction involves simple stirring of a strong NaOH solution with fine SnCl2·2H2O powder. Precipitated blue black microplates of SnO are finally transformed into high band gap Sn-SnO2 nanoparticles with sunlight. During the solid-state photodecomposition of microplates, spherical SnO2 nanoparticles along with tiny Sn(0) particles are evolved simultaneously. Tiny Sn(0) particles, improved surface area, stability toward adverse environmental conditions, and inherited negative surface charge electrostatically stabilize the Sn-SnO2 particle rendering it excellent water dispersible. The presence of Sn(0) nanoparticles in spherical SnO2 nanoparticles improves the charge (electrons and holes) separation efficiency. Then, the as-prepared particles selectively invite cationic dye molecules to the particle surface due to negative surface charge and degrade the dyes at a faster rate under UV light.

  15. Detection of the Sn(III) intermediate and the mechanism of the Sn(IV)/Sn(II) electroreduction reaction in bromide media by cyclic voltammetry and scanning electrochemical microscopy.

    PubMed

    Chang, Jinho; Bard, Allen J

    2014-01-08

    Fast-scan cyclic voltammetry (CV) and scanning electrochemical microscopy (SECM) were used to investigate the reduction of Sn(IV) as the hexabromo complex ion in a 2 M HBr-4 M NaBr medium. CV at scan rates to 100 V/s and SECM indicated the reaction pathway involves ligand-coupled electron transfer via an ECEC-DISP process: (1) one-electron reduction of Sn(IV)Br6(2-) to Sn(III)Br6(3-); (2) bromide dissociation of the reduced Sn(III)Br6(3-) to Sn(III)Br5(2-); (3) disproportionation of the reduced 2Sn(III)Br5(2-) to Sn(IV)Br5(-) and Sn(II)Br5(3-); (4) one-electron reduction of Sn(III)Br5(2-) to Sn(II)Br5(3-); (5) bromide dissociation from Sn(II)Br5 to Sn(II)Br4(2-). The intermediate Sn(III) species was confirmed by SECM(3-), where the Sn(III) generated at the Au tip was collected on a Au substrate in the tip generation/substrate collection mode when the distance between the tip and substrate was a few hundred nanometers.

  16. Mössbauer measurements on SnSe2

    NASA Astrophysics Data System (ADS)

    Bibicu, I.; Lőrinczi, A.; Popescu, M.

    2010-11-01

    Tin chalcogenides SnX2 and SnX, where X = S, Se and Te present a particularly interest for their electronic properties and applications in gas sensors. The state of tin in these materials is important for understanding of the sensing effect and improvement of the sensor performances. Mössbauer spectroscopy is a widely used technique for the analysis of the local electronic structure or chemical bonding in solids. In this paper we applied Mössbauer technique for the investigation of bulk and thin films of SnSe2 chalcogenide. The films of SnSe2 chalcogenide were obtained by the methods: PLD ("Pulsed laser deposition") and PED ("Pulsed electron deposition"). Mössbauer measurements were performed by transmission (TMS), respectively conversion electron spectroscopy (CEMS). By CEMS spectroscopy surfaces, coatings and thin films containing Sn can be studied on substrates and to various depths up to 1000 nanometers.

  17. The structure of 100Sn and neighbouring nuclei

    NASA Astrophysics Data System (ADS)

    Faestermann, T.; Górska, M.; Grawe, H.

    2013-03-01

    The nuclear structure in the 100Sn region is reviewed. State-of-the-art experimental techniques involving stable and radioactive beam facilities have enabled access to exotic nuclei in its next neighbourhood. The analysis of experimental data has established the shell structure and its evolution towards N=Z=50, seniority conservation and proton-neutron interaction in the g9/2 orbit, the super-allowed Gamow-Teller decay of 100Sn, masses and half lives along the rp-path, and super-allowed α decay beyond 100Sn. The status of theoretical approaches in shell model and mean-field investigations is described and their predictive power assessed. Structure features of 100Sn and its doubly-magic neighbours 56Ni at N=Z, 132Sn and 78Ni at N≫Z are compared. An outlook is given on future developments of experimental and theoretical methods.

  18. Anomalous surface phase formation on Pt sub 3 Sn <110>

    SciTech Connect

    Haner, A.N.; Ross, P.N. ); Bardi, U. . Dipt. di Chimica)

    1990-06-01

    LEED analysis of the clean annealed surface of a {l angle}110{r angle} oriented Pt{sub 3}Sn single crystal surface indicates the formation of a multilayer surface phase which does not have the L1{sub 2} bulk structure. LEISS analysis indicates a surface stoichiometry of ca. 1:1 with Sn atoms displaced ca. 1.4 above the plane of Pt atoms. The surface phase is hypothesized to be a rhombic distortion of the {l angle}0001{r angle} plant of PtSn, which has a B8{sub 1} (NiAs-type) bulk structure. It is not clear whether the phase forms by precipitation of PtSn due to a slight (0.5%) stoichiometric excess of Sn in the bulk, or due to multilayer reconstruction driven by surface segregation. 20 refs., 3 figs.

  19. Sn-doped hematite nanostructures for photoelectrochemical water splitting.

    PubMed

    Ling, Yichuan; Wang, Gongming; Wheeler, Damon A; Zhang, Jin Z; Li, Yat

    2011-05-11

    We report on the synthesis and characterization of Sn-doped hematite nanowires and nanocorals as well as their implementation as photoanodes for photoelectrochemical water splitting. The hematite nanowires were prepared on a fluorine-doped tin oxide (FTO) substrate by a hydrothermal method, followed by high temperature sintering in air to incorporate Sn, diffused from the FTO substrate, as a dopant. Sn-doped hematite nanocorals were prepared by the same method, by adding tin(IV) chloride as the Sn precursor. X-ray photoelectron spectroscopy analysis confirms Sn(4+) substitution at Fe(3+) sites in hematite, and Sn-dopant levels increase with sintering temperature. Sn dopant serves as an electron donor and increases the carrier density of hematite nanostructures. The hematite nanowires sintered at 800 °C yielded a pronounced photocurrent density of 1.24 mA/cm(2) at 1.23 V vs RHE, which is the highest value observed for hematite nanowires. In comparison to nanowires, Sn-doped hematite nanocorals exhibit smaller feature sizes and increased surface areas. Significantly, they showed a remarkable photocurrent density of 1.86 mA/cm(2) at 1.23 V vs RHE, which is approximately 1.5 times higher than that of the nanowires. Ultrafast spectroscopy studies revealed that there is significant electron-hole recombination within the first few picoseconds, while Sn doping and the change of surface morphology have no major effect on the ultrafast dynamics of the charge carriers on the picosecond time scales. The enhanced photoactivity in Sn-doped hematite nanostructures should be due to the improved electrical conductivity and increased surface area.

  20. Ternary Phases (Heusler) in the System Ti-Co-Sn

    NASA Astrophysics Data System (ADS)

    Kosinskiy, Andrey; Karlsen, Ole Bjørn; Sørby, Magnus H.; Prytz, Øystein

    2016-12-01

    Some of the Heusler-phases ( XY 2 Z and XYZ) are known to have large homogeneity ranges which can be useful for tuning material properties. In this work, we have revised the isothermal section of the Ti-Co-Sn system at 973 K (700 °C). A total of 29 ternary compositions, mostly in the regions TiCo2- x Sn for 0 ≤ x ≤ 1 and Ti1+ y Co2Sn1- y for 0 ≤ y ≤ 1, were prepared by arc-melting, then ball-milled and annealed. The resulting annealed powder samples were studied by applying the Rietveld method to X-ray and neutron powder diffraction data. Half-Heusler TiCoSn was not observed. The Heusler phase observed in TiCo2- x Sn has compositions ranging from TiCo1.52Sn to TiCo2Sn and has the half-Heusler structure where the excess of Co is located on the semi-filled tetrahedral site 4 d (¾, ¾, ¾) in the space group F-43 m. At 1273 K (1000 °C), this solid solubility is expanded from TiCo2Sn to TiCo with full solid solubility where Ti is gradually replacing Sn (Ti1+ y Co2Sn1- y for 0 ≤ y ≤ 1), while at 973 K (700 °C) there is a small solubility gap for 0.0 ≤ y ≤ 0.2.

  1. Contact angle measurements of Sn-Ag and Sn-Cu lead-free solders on copper substrates

    NASA Astrophysics Data System (ADS)

    Arenas, Mario F.; Acoff, Viola L.

    2004-12-01

    In this study, the contact angles of four lead-free solders, namely, Sn-3.5Ag, Sn-3.5Ag-4.8Bi, Sn-3.8Ag-0.7Cu, and Sn-0.7Cu (wt.%), were measured on copper substrates at different temperatures. Measurements were performed using the sessile-drop method. Contact angles ranging from 30° to 40° after wetting under vacuum with no fluxes and between 10° and 30° with rosin mildly activated (RMA) and rosin activated (RA) fluxes were obtained. The Sn-3.5Ag-4.8Bi exhibited the lowest contact angles, indicating improved wettability with the addition of bismuth. For all soldering alloys, lower contact angles were observed using RMA flux. Intermetallics formed at the solder/Cu interface were identified as Cu6Sn5 adjacent to the solder and Cu3Sn adjacent to the copper substrate. The Cu3Sn intermetallic phase was generally not observed when RMA flux was used. The effect of temperature on contact angle was dependent on the type of flux used.

  2. Antioxidant behavior of 1-feruloyl-sn-glycerol and 1,3-diferuloyl-sn-glycerol in phospholipid liposomes 1

    Technology Transfer Automated Retrieval System (TEKTRAN)

    1-Feruloyl-sn-glycerol (FG) and 1,3-diferuloyl-sn-glycerol (DFG) are two natural plant compounds that may be useful in cosmeceutical, food, and skin care applications because of excellent antioxidant properties. FG and DFG enzymatically synthesized through esterification of glycerol and soybean oil...

  3. Pulse number controlled laser annealing for GeSn on insulator structure with high substitutional Sn concentration

    NASA Astrophysics Data System (ADS)

    Moto, Kenta; Matsumura, Ryo; Sadoh, Taizoh; Ikenoue, Hiroshi; Miyao, Masanobu

    2016-06-01

    Crystalline GeSn-on-insulator structures with high Sn concentration (>8%), which exceeds thermal equilibrium solid-solubility (˜2%) of Sn in Ge, are essential to achieve high-speed thin film transistors and high-efficiency optical devices. We investigate non-thermal equilibrium growth of Ge1-xSnx (0 ≤ x ≤ 0.2) on quartz substrates by using pulsed laser annealing (PLA). The window of laser fluence enabling complete crystallization without film ablation is drastically expanded (˜5 times) by Sn doping above 5% into Ge. Substitutional Sn concentration in grown layers is found to be increased with decreasing irradiation pulse number. This phenomenon can be explained on the basis of significant thermal non-equilibrium growth achieved by higher cooling rate after PLA with a lower pulse number. As a result, GeSn crystals with substitutional Sn concentration of ˜12% are realized at pulse irradiation of single shot for the samples with the initial Sn concentration of 15%. Raman spectroscopy and electron microscopy measurements reveal the high quality of the grown layer. This technique will be useful to fabricate high-speed thin film transistors and high-efficiency optical devices on insulating substrates.

  4. Original electrochemical mechanisms of CaSnO{sub 3} and CaSnSiO{sub 5} as anode materials for Li-ion batteries

    SciTech Connect

    Mouyane, M.; Womes, M.; Jumas, J.C.; Olivier-Fourcade, J.; Lippens, P.E.

    2011-11-15

    Calcium stannate (CaSnO{sub 3}) and malayaite (CaSnSiO{sub 5}) were synthesized by means of a high temperature solid-state reaction. Their crystal structures and morphologies were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy; their electrochemical properties were analyzed by galvanostatic tests. The amorphization of the initial electrode materials was followed by XRD. The first discharge of the oxides CaSnO{sub 3} and CaSnSiO{sub 5} shows a plateau at low potential, which is due to the progressive formation of Li-Ca-Sn and/or Li-Sn alloys as shown by {sup 119}Sn Moessbauer spectroscopy. The results reveal similar electrochemical mechanisms for CaSnO{sub 3} and CaSnSiO{sub 5} but they completely differ from those related to SnO{sub 2}. - Graphical abstract: {sup 119}Sn Moessbauer spectra at the end of the first discharge of CaSnO{sub 3} (dashed line) and CaSnSiO{sub 5} (solid line) anodes for Li-ion batteries. Inset shows that relative amounts of Sn(0) based alloys formed during the first discharge are similar for CaSnO{sub 3} and CaSnSiO{sub 5} pristine materials. Highlights: > CaSnSiO{sub 5} and CaSnO{sub 3} as anode materials for Li-ion batteries. > X-ray diffraction and Moessbauer spectroscopy, to explain the electrochemical mechanisms. > Similar mechanisms for the two compounds but different from those of SnO{sub 2} due to Ca.

  5. Origin of high Coulombic loss during sodiation in Na-Sn battery

    NASA Astrophysics Data System (ADS)

    Byeon, Young-Woon; Choi, Yong-Seok; Ahn, Jae-Pyoung; Lee, Jae-Chul

    2017-03-01

    Electrochemical sodiation is performed in crystalline Sn foil using in situ scanning electron microscopy (SEM) to simultaneously measure the changes in the electrical resistivity and volume of the Sn anode in a Na-Sn battery. We observe that sodiation causes an increase in the Sn anode resistivity by six orders of magnitude. Ab initio molecular dynamics simulations of the Na-Sn alloy system demonstrate that the increased resistivity of the anode is caused by the formation of an electrically resistive amorphous NaSn phase (a-NaSn) with a pseudogap. It is also observed that the formation of a-NaSn is always accompanied by a large volume expansion of ∼200%, causing the development of residual tensile stress. The residual stress in turn alters the electronic structure of the a-NaSn phase, further increasing the resistivity of a-NaSn and thus decreasing the energy efficiency of the Na-Sn battery.

  6. Research on structure of Cu2ZnSn(S, Se)4 thin films with high Sn-related phases

    NASA Astrophysics Data System (ADS)

    Li, Peng-yu; Xue, Yu-ming; Liu, Hao; Xia, Dan; Song, Dian-you; Feng, Shao-jun; Sun, Hai-tao; Yu, Bing-bing; Qiao, Zai-xiang

    2016-11-01

    Cu2ZnSn(S, Se)4 (CZTSSe) thin films were deposited on flexible substrates by three evaporation processes at high temperature. The chemical compositions, microstructures and crystal phases of the CZTSSe thin films were respectively characterized by inductively coupled plasma optical emission spectrometer (ICP-OES), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman scattering spectrum. The results show that the single-step evaporation method at high temperature yields CZTSSe thin films with nearly pure phase and high Sn-related phases. The elemental ratios of Cu/(Zn+Sn)=1.00 and Zn/Sn=1.03 are close to the characteristics of stoichiometric CZTSSe. There is the smooth and uniform crystalline at the surface and large grain size at the cross section for the films, and no other phases exist in the film by XRD and Raman shift measurement. The films are no more with the Sn-related phase deficiency.

  7. Thermoelectric SnS and SnS-SnSe solid solutions prepared by mechanical alloying and spark plasma sintering: Anisotropic thermoelectric properties

    PubMed Central

    Asfandiyar; Wei, Tian-Ran; Li, Zhiliang; Sun, Fu-Hua; Pan, Yu; Wu, Chao-Feng; Farooq, Muhammad Umer; Tang, Huaichao; Li, Fu; Li, Bo; Li, Jing-Feng

    2017-01-01

    P–type SnS compound and SnS1−xSex solid solutions were prepared by mechanical alloying followed by spark plasma sintering (SPS) and their thermoelectric properties were then studied in different compositions (x = 0.0, 0.2, 0.5, 0.8) along the directions parallel (//) and perpendicular (⊥) to the SPS–pressurizing direction in the temperature range 323–823 Κ. SnS compound and SnS1−xSex solid solutions exhibited anisotropic thermoelectric performance and showed higher power factor and thermal conductivity along the direction ⊥ than the // one. The thermal conductivity decreased with increasing contents of Se and fell to 0.36 W m−1 K−1 at 823 K for the composition SnS0.5Se0.5. With increasing selenium content (x) the formation of solid solutions substantially improved the electrical conductivity due to the increased carrier concentration. Hence, the optimized power factor and reduced thermal conductivity resulted in a maximum ZT value of 0.64 at 823 K for SnS0.2Se0.8 along the parallel direction. PMID:28240324

  8. Thermoelectric SnS and SnS-SnSe solid solutions prepared by mechanical alloying and spark plasma sintering: Anisotropic thermoelectric properties.

    PubMed

    Asfandiyar; Wei, Tian-Ran; Li, Zhiliang; Sun, Fu-Hua; Pan, Yu; Wu, Chao-Feng; Farooq, Muhammad Umer; Tang, Huaichao; Li, Fu; Li, Bo; Li, Jing-Feng

    2017-02-27

    P-type SnS compound and SnS1-xSex solid solutions were prepared by mechanical alloying followed by spark plasma sintering (SPS) and their thermoelectric properties were then studied in different compositions (x = 0.0, 0.2, 0.5, 0.8) along the directions parallel (//) and perpendicular (⊥) to the SPS-pressurizing direction in the temperature range 323-823 Κ. SnS compound and SnS1-xSex solid solutions exhibited anisotropic thermoelectric performance and showed higher power factor and thermal conductivity along the direction ⊥ than the // one. The thermal conductivity decreased with increasing contents of Se and fell to 0.36 W m(-1) K(-1) at 823 K for the composition SnS0.5Se0.5. With increasing selenium content (x) the formation of solid solutions substantially improved the electrical conductivity due to the increased carrier concentration. Hence, the optimized power factor and reduced thermal conductivity resulted in a maximum ZT value of 0.64 at 823 K for SnS0.2Se0.8 along the parallel direction.

  9. Thermoelectric SnS and SnS-SnSe solid solutions prepared by mechanical alloying and spark plasma sintering: Anisotropic thermoelectric properties

    NASA Astrophysics Data System (ADS)

    Asfandiyar; Wei, Tian-Ran; Li, Zhiliang; Sun, Fu-Hua; Pan, Yu; Wu, Chao-Feng; Farooq, Muhammad Umer; Tang, Huaichao; Li, Fu; Li, Bo; Li, Jing-Feng

    2017-02-01

    P–type SnS compound and SnS1‑xSex solid solutions were prepared by mechanical alloying followed by spark plasma sintering (SPS) and their thermoelectric properties were then studied in different compositions (x = 0.0, 0.2, 0.5, 0.8) along the directions parallel (//) and perpendicular (⊥) to the SPS–pressurizing direction in the temperature range 323–823 Κ. SnS compound and SnS1‑xSex solid solutions exhibited anisotropic thermoelectric performance and showed higher power factor and thermal conductivity along the direction ⊥ than the // one. The thermal conductivity decreased with increasing contents of Se and fell to 0.36 W m‑1 K‑1 at 823 K for the composition SnS0.5Se0.5. With increasing selenium content (x) the formation of solid solutions substantially improved the electrical conductivity due to the increased carrier concentration. Hence, the optimized power factor and reduced thermal conductivity resulted in a maximum ZT value of 0.64 at 823 K for SnS0.2Se0.8 along the parallel direction.

  10. Syntheses of Cu2SnS3 and Cu2ZnSnS4 nanoparticles with tunable Zn/Sn ratios under multibubble sonoluminescence conditions.

    PubMed

    Park, Jongpil; Song, Miyeon; Jung, Won Mok; Lee, Won Young; Kim, Hanggeun; Kim, Youngkwon; Hwang, Chahwan; Shim, Il-Wun

    2013-08-07

    Cu2ZnSnS4 (CZTS) nanoparticles were synthesized by sonochemical reactions under multibubble sonoluminescence (MBSL) conditions. First, Cu2SnS3 (CTS) nanoparticles were synthesized by the sonochemical method with a 91.3% yield. Second, ZnS was coated on Cu2SnS3 nanoparticles by the same method. Then, they were transformed into CZTS nanoparticles of 90-300 nm diameter by heating them at 450 °C for 1 hour. The ratios between Zn and Sn could be controlled from 0.20 to 1.32 by adjusting the relative concentrations of Cu2SnS3 and ZnCl2. With relatively lower Zn : Sn ratios (0.20-0.41), there was a mixture of CTS and CZTS nanoparticles. The prepared nanoparticles show different band gaps from 1.19 to 1.52 eV depending on the zinc to tin ratio. In this sonochemical method without using any toxic or high temperature solvents, the specific stoichiometric element ratios in CZTS were controllable on demand and their experimental results were always reproducible in separate syntheses. The CZTS nanoparticles were investigated by using X-ray diffraction, a UV-Vis spectrophotometer, a scanning electron microscope, Raman spectroscopy, and a high resolution-transmission electron microscope.

  11. A Massive Shell of Supernova-formed Dust in SNR G54.1+0.3

    NASA Astrophysics Data System (ADS)

    Temim, Tea; Dwek, Eli; Arendt, Richard G.; Borkowski, Kazimierz J.; Reynolds, Stephen P.; Slane, Patrick; Gelfand, Joseph D.; Raymond, John C.

    2017-02-01

    While theoretical models of dust condensation predict that most refractory elements produced in core-collapse supernovae (SNe) efficiently condense into dust, a large quantity of dust has so far only been observed in SN 1987A. We present an analysis of observations from the Spitzer Space Telescope, Herschel Space Observatory, Stratospheric Observatory for Infrared Astronomy, and AKARI of the infrared shell surrounding the pulsar wind nebula in the supernova remnant G54.1+0.3. We attribute a distinctive spectral feature at 21 μm to a magnesium silicate grain species that has been invoked in modeling the ejecta-condensed dust in Cas A, which exhibits the same spectral signature. If this species is responsible for producing the observed spectral feature and accounts for a significant fraction of the observed infrared continuum, we find that it would be the dominant constituent of the dust in G54.1+0.3, with possible secondary contributions from other compositions, such as carbon, silicate, or alumina grains. The total mass of SN-formed dust required by this model is at least 0.3 M ⊙. We discuss how these results may be affected by varying dust grain properties and self-consistent grain heating models. The spatial distribution of the dust mass and temperature in G54.1+0.3 confirms the scenario in which the SN-formed dust has not yet been processed by the SN reverse shock and is being heated by stars belonging to a cluster in which the SN progenitor exploded. The dust mass and composition suggest a progenitor mass of 16–27 M ⊙ and imply a high dust condensation efficiency, similar to that found for Cas A and SN 1987A. The study provides another example of significant dust formation in a Type IIP SN explosion and sheds light on the properties of pristine SN-condensed dust.

  12. Layer-dependent properties of SnS2 and SnSe2 two-dimensional materials

    NASA Astrophysics Data System (ADS)

    Gonzalez, Joseph M.; Oleynik, Ivan I.

    2016-09-01

    The layer-dependent structural, electronic, and vibrational properties of SnS2 and SnSe2 are investigated using first-principles density functional theory (DFT). The in-plane lattice constants, interlayer distances and binding energies are found to be layer-independent. Bulk SnS2 and SnSe2 are both indirect band gap semiconductors with Eg=2.18 and 1.07 eV , respectively. Few-layer and monolayer 2D systems also possess an indirect band gap, which is increased to 2.41 and 1.69 eV for single layers of SnS2 and SnSe2. The effective mass theory of 2D excitons, which takes into account the combined effect of the anisotropy, nonlocal 2D screening and layer-dependent 3D screening, predicts strong excitonic effects. The binding energy of indirect excitons in monolayer samples, Ex˜0.9 eV , is substantially reduced to Ex=0.14 eV in bulk SnS2 and Ex=0.09 eV in bulk SnSe2. The layer-dependent Raman spectra display a strong decrease of intensities of the Raman active A1 g mode upon decreasing the number of layers down to a monolayer, by a factor of 7 in the case of SnS2 and a factor of 20 in the case of SnSe2, which can be used to identify the number of layers in a 2D sample.

  13. Facile fabrication of Dy2Sn2O7-SnO2 nanocomposites as an effective photocatalyst for degradation and removal of organic contaminants.

    PubMed

    Zinatloo-Ajabshir, Sahar; Morassaei, Maryam Sadat; Salavati-Niasari, Masoud

    2017-07-01

    Dy2Sn2O7-SnO2 nanocomposites were synthesized through a facile way utilizing propane-1,2-diol as novel polymerization agent and trimesic acid as new stabilization agent. Effects of different polymerization agents, calcination temperature and various stabilization agents on the size and shape of the Dy2Sn2O7-SnO2 nanocomposites were investigated. It was found that changing these synthesis factors has great role in controlling size and shape of Dy2Sn2O7-SnO2 nanocomposites. The as-produced Dy2Sn2O7-SnO2 nanostructures were analyzed using FT-IR, HRTEM, DR-UV-vis, EDS, XRD, and FESEM. This is the first attempt on the investigation of photocatalytic behavior of nanostructured Dy2Sn2O7-SnO2. The influences of Dy2Sn2O7-SnO2 amount and type of illumination light on the photocatalytic behavior of the nanocrystalline Dy2Sn2O7-SnO2 were also investigated. The ability for the decomposition of the water pollutants including eosin Y, eriochrome black T, erythrosine and methyl orange were studied through photocatalytic experiments.

  14. Genome-wide analysis of SnRK gene family in Brachypodium distachyon and functional characterization of BdSnRK2.9.

    PubMed

    Wang, Lianzhe; Hu, Wei; Sun, Jiutong; Liang, Xiaoyu; Yang, Xiaoyue; Wei, Shuya; Wang, Xiatian; Zhou, Yi; Xiao, Qiang; Yang, Guangxiao; He, Guangyuan

    2015-08-01

    The sucrose non-fermenting 1 (SNF1)-related protein kinases (SnRKs) play key roles in plant signaling pathways including responses to biotic and abiotic stresses. Although SnRKs have been systematically studied in Arabidopsis and rice, there is no information concerning SnRKs in the new Poaceae model plant Brachypodium distachyon. In the present study, a total of 44 BdSnRKs were identified and classified into three subfamilies, including three members of BdSnRK1, 10 of BdSnRK2 and 31 of BdSnRK3 (CIPK) subfamilies. Phylogenetic reconstruction, chromosome distribution and synteny analyses suggested that BdSnRK family had been established before the dicot-monocot lineage parted, and had experienced rapid expansion during the process of plant evolution since then. Expression analysis of the BdSnRK2 subfamily showed that the majority of them could respond to abiotic stress and related signal molecules treatments. Protein-protein interaction and co-expression analyses of BdSnRK2s network showed that SnRK2s might be involved in biological pathway different from that of dicot model plant Arabidopsis. Expression of BdSnRK2.9 in tobacco resulted in increased tolerance to drought and salt stresses through activation of NtABF2. Taken together, comprehensive analyses of BdSnRKs would provide a basis for understanding of evolution and function of BdSnRK family.

  15. Host Galaxy Spectra and Consequences for SN Typing from the SDSS SN Survey

    SciTech Connect

    Olmstead, Matthew D.; Brown, Peter J.; Sako, Masao; Bassett, Bruce; Bizyaev, Dmitry; Brinkmann, J.; Brownstein, Joel R.; Brewington, Howard; Campbell, Heather; D’Andrea, Chris B.; Dawson, Kyle S.; Ebelke, Garrett L.; Frieman, Joshua A.; Galbany, Lluís; Garnavich, Peter; Gupta, Ravi R.; Hlozek, Renee; Jha, Saurabh W.; Kunz, Martin; Lampeitl, Hubert; Malanushenko, Elena; Malanushenko, Viktor; Marriner, John; Miquel, Ramon; Montero-Dorta, Antonio D.; Nichol, Robert C.; Oravetz, Daniel J.; Pan, Kaike; Schneider, Donald P.; Simmons, Audrey E.; Smith, Mathew; Snedden, Stephanie A.

    2014-03-06

    We present the spectroscopy from 5254 galaxies that hosted supernovae (SNe) or other transient events in the Sloan Digital Sky Survey II (SDSS-II). Obtained during SDSS-I, SDSS-II, and the Baryon Oscillation Spectroscopic Survey (BOSS), this sample represents the largest systematic, unbiased, magnitude limited spectroscopic survey of supernova (SN) host galaxies. Using the host galaxy redshifts, we test the impact of photometric SN classification based on SDSS imaging data with and without using spectroscopic redshifts of the host galaxies. Following our suggested scheme, there are a total of 1166 photometrically classified SNe Ia when using a flat redshift prior and 1126 SNe Ia when the host spectroscopic redshift is assumed. For 1024 (87.8%) candidates classified as likely SNe Ia without redshift information, we find that the classification is unchanged when adding the host galaxy redshift. Using photometry from SDSS imaging data and the host galaxy spectra, we also report host galaxy properties for use in future nalysis of SN astrophysics. Finally, we investigate the differences in the interpretation of the light curve properties with and without knowledge of the redshift. When using the SALT2 light curve fitter, we find a 21% increase in the number of fits that converge when using the spectroscopic redshift. Without host galaxy redshifts, we find that SALT2 light curve fits are systematically biased towards lower photometric redshift estimates and redder colors in the limit of low signal-to-noise data. The general improvements in performance of the light curve fitter and the increased diversity of the host galaxy sample highlights the importance of host galaxy spectroscopy for current photometric SN surveys such as the Dark Energy Survey and future surveys such as the Large Synoptic Survey Telescope.

  16. An optimal hydrodynamic model for the normal type IIP supernova 1999em

    NASA Astrophysics Data System (ADS)

    Utrobin, V. P.

    2007-01-01

    Context: There is still no consensus about progenitor masses of type IIP supernovae. Aims: We study a normal type IIP SN 1999em in detail and compare it to a peculiar type IIP SN 1987A. Methods: We computed the hydrodynamic and time-dependent atmosphere models interpreting simultaneously both the photometric and spectroscopic observations. Results: The bolometric light curve of SN 1999em and the spectral evolution of its Hα line are consistent with a presupernova radius of 500 ± 200~R⊙, an ejecta mass of 19.0 ± 1.2~M⊙, an explosion energy of (1.3±0.1) × 1051 erg, and a radioactive 56Ni mass of 0.036 ± 0.009~M⊙. A mutual mixing of hydrogen-rich and helium-rich matter in the inner layers of the ejecta guarantees a good fit of the calculated light curve to that observed. Based on the hydrodynamic models in the vicinity of the optimal model, we derive the approximate relationships between the basic physical and observed parameters. The hydrodynamic and atmosphere models of SN 1999em are inconsistent with the short distance of 7.85 Mpc to the host galaxy. Conclusions: .We find that the hydrogen recombination in the atmosphere of a normal type IIP SN 1999em, as well as most likely other type IIP supernovae at the photospheric epoch, is essentially a time-dependent phenomenon. It is also shown that in normal type IIP supernovae the homologous expansion of the ejecta in its atmosphere takes place starting from nearly the third day after the supernova explosion. A comparison of SN 1999em with SN 1987A reveals two very important results for supernova theory. First, the comparability of the helium core masses and the explosion energies implies a unique explosion mechanism for these core collapse supernovae. Second, the optimal model for SN 1999em is characterized by a weaker 56Ni mixing up to ≈660 km s-1 compared to a moderate 56Ni mixing up to ~3000 km s-1 in SN 1987A, hydrogen being mixed deeply downward to ~650 km s-1.

  17. SN2' versus SN2 reactivity: control of regioselectivity in conversions of Baylis-Hillman adducts.

    PubMed

    Baidya, Mahiuddin; Remennikov, Grygoriy Y; Mayer, Peter; Mayr, Herbert

    2010-01-25

    TiCl(4)-induced Baylis-Hillman reactions of alpha,beta-unsaturated carbonyl compounds with aldehydes yield the (Z)-2-(chloromethyl)vinyl carbonyl compounds 5, which react with 1,4-diazabicyclo[2.2.2]octane (DABCO), quinuclidine, and pyridines to give the allylammonium ions 6. Their combination with less than one equivalent of the potassium salts of stabilized carbanions (e.g. malonate) yields methylene derivatives 8 under kinetically controlled conditions (S(N)2' reactions). When more than one equivalent of the carbanions is used, a second S(N)2' reaction converts 8 into their thermodynamically more stable allyl isomers 9. The second-order rate constants for the reactions of 6 with carbanions have been determined photometrically in DMSO. With these rate constants and the previously reported nucleophile-specific parameters N and s for the stabilized carbanions, the correlation log k (20 degrees C)=s(N + E) allowed us to calculate the electrophilicity parameters E for the allylammonium ions 6 (-19 < E < -18). The kinetic data indicate the S(N)2' reactions to proceed via an addition-elimination mechanism with a rate-determining addition step.

  18. The magic nature of 132Sn explored through the single-particle states of 133Sn

    SciTech Connect

    Jones, K. L.; Adekola, Aderemi S; Bardayan, Daniel W; Blackmon, Jeff C; Chae, K. Y.; Chipps, K.; Cizewski, J. A.; Erikson, Luke; Harlin, Christopher W; Hatarik, Robert; Kapler, R.; Kozub, R. L.; Liang, J Felix; Livesay, Jake; Ma, Zhanwen; Moazen, Brian; Nesaraja, Caroline D; Nunes, F. M.; Pain, S. D.; Patterson, N. P.; Shapira, Dan; ShrinerJr., J. F.; Smith, Michael Scott; Swan, T. P.; Thomas, J. S.

    2010-05-01

    Atomic nuclei have a shell structure1 in which nuclei with magic numbers of neutrons and protons are analogous to the noble gases in atomic physics. Only ten nuclei with the standard magic numbers of both neutrons and protons have so far been observed. The nuclear shell model is founded on the precept that neutrons and protons can move as independent particles in orbitals with discrete quantum numbers, subject to a mean field generated by all the other nucleons. Knowledge of the properties of single-particle states outside nuclear shell closures in exotic nuclei is important2 5 for a fundamental understanding of nuclear structure and nucleosynthesis (for example the r-process, which is responsible for the production of about half of the heavy elements). However, as a result of their short lifetimes, there is a paucity of knowledge about the nature of single-particle states outside exotic doubly magic nuclei. Here we measure the single-particle character of the levels in 133Sn that lies outside the double shell closure present at the short-lived nucleus 132Sn. We use an inverse kinematics technique that involves the transfer of a single nucleon to the nucleus. The purity of the measured single-particle states clearly illustrates the magic nature of 132Sn.

  19. SnSAG5 is an alternative surface antigen of Sarcocystis neurona strains that is mutually exclusive to SnSAG1.

    PubMed

    Crowdus, Carolyn A; Marsh, Antoinette E; Saville, Willliam J; Lindsay, David S; Dubey, J P; Granstrom, David E; Howe, Daniel K

    2008-11-25

    Sarcocystis neurona is an obligate intracellular parasite that causes equine protozoal myeloencephalitis (EPM). Previous work has identified a gene family of paralogous surface antigens in S. neurona called SnSAGs. These surface proteins are immunogenic in their host animals, and are therefore candidate molecules for development of diagnostics and vaccines. However, SnSAG diversity exists in strains of S. neurona, including the absence of the major surface antigen gene SnSAG1. Instead, sequence for an alternative SnSAG has been revealed in two of the SnSAG1-deficient strains. Herein, we present data characterizing this new surface protein, which we have designated SnSAG5. The results indicated that the protein encoded by the SnSAG5 sequence is indeed a surface-associated molecule that has characteristics consistent with the other SAGs identified in S. neurona and related parasites. Importantly, Western blot analyses of a collection of S. neurona strains demonstrated that 6 of 13 parasite isolates express SnSAG5 as a dominant surface protein instead of SnSAG1. Conversely, SnSAG5 was not detected in SnSAG1-positive strains. One strain, which was isolated from the brain of a sea otter, did not express either SnSAG1 or SnSAG5. Genetic analysis with SnSAG5-specific primers confirmed the presence of the SnSAG5 gene in Western blot-positive strains, while also suggesting the presence of a novel SnSAG sequence in the SnSAG1-deficient, SnSAG5-deficient otter isolate. The findings provide further indication of S. neurona strain diversity, which has implications for diagnostic testing and development of vaccines against EPM as well as the population biology of Sarcocystis cycling in the opossum definitive host.

  20. Parametrized dielectric functions of amorphous GeSn alloys

    SciTech Connect

    D'Costa, Vijay Richard Wang, Wei; Yeo, Yee-Chia; Schmidt, Daniel

    2015-09-28

    We obtained the complex dielectric function of amorphous Ge{sub 1−x}Sn{sub x} (0 ≤ x ≤ 0.07) alloys using spectroscopic ellipsometry from 0.4 to 4.5 eV. Amorphous GeSn films were formed by room-temperature implantation of phosphorus into crystalline GeSn alloys grown by molecular beam epitaxy. The optical response of amorphous GeSn alloys is similar to amorphous Ge and can be parametrized using a Kramers-Kronig consistent Cody-Lorentz dispersion model. The parametric model was extended to account for the dielectric functions of amorphous Ge{sub 0.75}Sn{sub 0.25} and Ge{sub 0.50}Sn{sub 0.50} alloys from literature. The compositional dependence of band gap energy E{sub g} and parameters associated with the Lorentzian oscillator have been determined. The behavior of these parameters with varying x can be understood in terms of the alloying effect of Sn on Ge.

  1. Interfacial reactions in the Sn-Ag/Au couples

    NASA Astrophysics Data System (ADS)

    Chen, Sinn-Wen; Yen, Yee-Wen

    2001-09-01

    Ag-Sn alloys are one of the most promising lead-free solders. Their reactions with Au substrates have been examined by using the reaction couple technique. Sn-3.5wt.%Ag/Au and Sn-25wt.%Ag/Au couples have been prepared and reacted at 120, 150, 180 and 200 C for various lengths of time. Three phases, δ-AuSn, ɛ2-AuSn2, and η-AuSn4, are found in all the couples. The thickness of the reaction layers inccreases with higher temperatures and longer reaction time, and their growth rates are described by using the parabolic law. Arrhenius equation is used to describe the temperature dependence of the growth rates. The activation energy of the growth of the intermetallic layers in both kinds of the reaction couples is similar and is determined to be 76.74 KJ/mole. Based on the reaction path knowledge and interfacial morphology, it is concluded that Sn is the fastest diffusion species in the couples.

  2. How Can The SN-GRB Time Delay Be Measured?

    NASA Technical Reports Server (NTRS)

    Norris, J. P.; Bonnell, J. T.

    2003-01-01

    The connection between SNe and GRBs, launched by SN 1998bw / GRB 980425 and clinched by SN 2003dh / GRB 030329-with the two GRBs differing by a factor of approximately 50000 in luminosity-so far suggests a rough upper limit of approximately 1-2 days for the delay between SN and GRB. Only four SNe have had nonnegligible coverage in close coincidence with the initial explosion, near the W shock breakout: two Qpe II, and two Type IC, SN 1999ex and SN 1998bw. For the latter, only a hint of the minimum between the UV maximum and the radioactivity bump served to help constrain the interval between SN and GRB. Swift GRB alerts may provide the opportunity to study many SNe through the UV breakout phase: GRB 980425 look dikes -apparently nearby, low- luminosity, soft-spectrum, long-lag GRBs-accounted for half of BATSE bursts near threshold, and may dominate the Swift yield near threshold, since it has sensitivity to lower energies than did BATSE. The SN to GRB delay timescale should be better constrained by prompt UV/optical observations alerted by these bursts. Definitive delay measurements may be obtained if long-lag bursters are truly nearby: The SNe/GRBs could emit gravitational radiation detectable by LIGO-II if robust non-axisymmetric bar instabilities develop during core collapse, and/or neutrino emission may be detectable as suggested by Meszaros et al.

  3. Tin Compensation for the SnS Based Optoelectronic Devices

    NASA Astrophysics Data System (ADS)

    Wang, S. F.; Wang, W.; Fong, W. K.; Yu, Y.; Surya, C.

    2017-01-01

    In this paper we report the growth of high quality SnS thin films with good crystallinity deposited on two-dimensional (2D) mica substrates. It is believed that the 2D nature of SnS, with strong intra-layer covalent bonds and weak inter-layer van der Waals interactions, is responsible for its relative insensitivity to lattice mismatch. We also investigated the reduction of Sn vacancies in the material using Sn-compensation technique during the material growth process. The experimental results clearly demonstrated substantial enhancements in the electrical and structural properties for films deposited using Sn-compensation technique. A mobility of 51 cm2  V‑1 s‑1 and an XRD rocking curve full width at half maximum of 0.07° were obtained. Sn-compensated SnS/GaN:Si heterojunctions were fabricated and significant improvement in both the I-V characteristics and the spectral responsivities of the devices were characterized.

  4. Tin Compensation for the SnS Based Optoelectronic Devices

    PubMed Central

    Wang, S. F.; Wang, W.; Fong, W. K.; Yu, Y.; Surya, C.

    2017-01-01

    In this paper we report the growth of high quality SnS thin films with good crystallinity deposited on two-dimensional (2D) mica substrates. It is believed that the 2D nature of SnS, with strong intra-layer covalent bonds and weak inter-layer van der Waals interactions, is responsible for its relative insensitivity to lattice mismatch. We also investigated the reduction of Sn vacancies in the material using Sn-compensation technique during the material growth process. The experimental results clearly demonstrated substantial enhancements in the electrical and structural properties for films deposited using Sn-compensation technique. A mobility of 51 cm2  V−1 s−1 and an XRD rocking curve full width at half maximum of 0.07° were obtained. Sn-compensated SnS/GaN:Si heterojunctions were fabricated and significant improvement in both the I-V characteristics and the spectral responsivities of the devices were characterized. PMID:28045033

  5. STM study on the structures of SnSe surfaces

    NASA Astrophysics Data System (ADS)

    Kim, Tae Hoon; Kim, Sang-Ui; Thi Ly, Trinh; Duong, Anh Tuan; Cho, Sunglae; Rhim, S. H.; Kim, Jungdae

    SnSe is a 2 dimensional layered material, and each layer is coupled by van deer Waals forces allowing very easy cleaving though the layer surfaces. SnSe has been studied for various potential applications because of its high stability and elemental abundance in earth. Recently, it was also reported that bulk SnSe has an excellent thermoelectric property of ZT =2.6 at 923 K along the b axis (Zhao et al., Nature 508 373 (2014)). The surface of a single crystal SnSe was studied via a home-built low temperature scanning tunneling microscopy (STM). Clear atomic images of SnSe surfaces were observed at the filled and empty state measurements, and detail atomic structures were analyzed by comparing with DFT simulations. We found that the atomic image of SnSe surfaces measured by STM is not trivial to understand. Only Sn atoms were visible on STM topographic images for the both of filled and empty state probing. This work was supported by the National Research Foundation of Korea(NRF) [Nos. NRF-2013R1A1A1008724, NRF-2009-0093818, and NRF-2014R1A4A1071686].

  6. Origin of low thermal conductivity in SnSe

    NASA Astrophysics Data System (ADS)

    Xiao, Yu; Chang, Cheng; Pei, Yanling; Wu, Di; Peng, Kunling; Zhou, Xiaoyuan; Gong, Shengkai; He, Jiaqing; Zhang, Yongsheng; Zeng, Zhi; Zhao, Li-Dong

    2016-09-01

    We provide direct evidence to understand the origin of low thermal conductivity of SnSe using elastic measurements. Compared to state-of-the-art lead chalcogenides Pb Q (Q =Te , Se, S), SnSe exhibits low values of sound velocity (˜1420 m /s ) , Young's modulus (E ˜27.7 GPa ) , and shear modulus (G ˜9.6 GPa ) , which are ascribed to the extremely weak Sn-Se atomic interactions (or bonds between layers); meanwhile, the deduced average Grüneisen parameter γ of SnSe is as large as ˜3.13, originating from the strong anharmonicity of the bonding arrangement. The calculated phonon mean free path (l ˜ 0.84 nm) at 300 K is comparable to the lattice parameters of SnSe, indicating little room is left for further reduction of the thermal conductivity through introducing nanoscale microstructures and microscale grain boundaries. The low elastic properties indicate that the weak chemical bonding stiffness of SnSe generally causes phonon modes softening which eventually slows down phonon propagation. This work provides insightful data to understand the low lattice thermal conductivity of SnSe.

  7. ASYMMETRIC EJECTA DISTRIBUTION IN SN 1006

    SciTech Connect

    Uchida, Hiroyuki; Koyama, Katsuji; Yamaguchi, Hiroya

    2013-07-01

    We present the results from deep X-ray observations ({approx}400 ks in total) of SN 1006 with Suzaku. The thermal spectrum from the entire supernova remnant (SNR) exhibits prominent emission lines of O, Ne, Mg, Si, S, Ar, Ca, and Fe. The observed abundance pattern in the ejecta components is in good agreement with that predicted by a standard model of Type Ia supernovae (SNe). The spatially resolved analysis reveals that the distribution of the O-burning and incomplete Si-burning products (Si, S, and Ar) is asymmetric, while that of the C-burning products (O, Ne, and Mg) is relatively uniform in the SNR interior. The peak position of the former is clearly shifted by 5' ({approx}3.2 pc at the distance of 2.2 kpc) to the southeast (SE) from the SNR's geometric center. Using the SNR age of {approx}1000 yr, we constrain that the velocity asymmetry (in projection) of the ejecta is {approx}3100 km s{sup -1}. The Fe abundance is also significantly higher in the SE region than in the northwest. Given that the non-uniformity is observed only in the heavier elements (Si through Fe), we argue that SN 1006 originates from an asymmetric explosion, as is expected from recent multidimensional simulations of Type Ia SNe, although we cannot eliminate the possibility that inhomogeneous ambient medium had induced the apparent non-uniformity. Possible evidence for the Cr-K-shell line and line broadening in the Fe-K-shell emission is also found.

  8. Microwave study of superconducting Sn films above and below percolation

    NASA Astrophysics Data System (ADS)

    Beutel, Manfred H.; Ebensperger, Nikolaj G.; Thiemann, Markus; Untereiner, Gabriele; Fritz, Vincent; Javaheri, Mojtaba; Nägele, Jonathan; Rösslhuber, Roland; Dressel, Martin; Scheffler, Marc

    2016-08-01

    The electronic properties of superconducting Sn films ({T}{{c}}≈ 3.8 {{K}}) change significantly when reducing the film thickness down to a few {nm}, in particular close to the percolation threshold. The low-energy electrodynamics of such Sn samples can be probed via microwave spectroscopy, e.g. with superconducting stripline resonators. Here we study Sn thin films, deposited via thermal evaporation—ranging in thickness between 38 and 842 {nm}—which encompasses the percolation transition. We use superconducting Pb stripline resonators to probe the microwave response of these Sn films in a frequency range between 4 and 20 {GHz} at temperatures from 7.2 down to 1.5 {{K}}. The measured quality factor of the resonators decreases with rising temperature due to enhanced losses. As a function of the sample thickness we observe three regimes with significantly different properties: samples below percolation, i.e. ensembles of disconnected superconducting islands, exhibit dielectric properties with negligible losses, demonstrating that macroscopic current paths are required for appreciable dynamical conductivity of Sn at GHz frequencies. Thick Sn films, as the other limit, lead to low-loss resonances both above and below T c of Sn, as expected for bulk conductors. But in an intermediate thickness regime, just above percolation and with labyrinth-like morphology of the Sn, we observe a quite different behavior: the superconducting state has a microwave response similar to the thicker, completely covering films with low microwave losses; but the metallic state of these Sn films is so lossy that resonator operation is suppressed completely.

  9. Direct Measurement of the Supernova Rate in Starburst Galaxies

    NASA Technical Reports Server (NTRS)

    Bregman, J. D.; Temi, P.; Rank, D.

    2000-01-01

    Supernovae play a key role in the dynamics, structure, and chemical evolution of galaxies. The massive stars that end their lives as supernovae live for short enough times that many are still associated with dusty star formation regions when they explode, making them difficult to observe at visible wavelengths. In active star forming regions (galactic nuclei and starburst regions), dust extinction is especially severe. Thus, determining the supernova rate in active star forming regions of galaxies, where the supernova rate can be one or two orders of magnitude higher than the average, has proven to be difficult. From observations of SN1987A, we know that the [NiII] 6.63 micrometer emission line was the strongest line in the infrared spectrum for a period of a year and half after th explosion. Since dust extinction is much less at 6.63 micrometers than at visible wavelengths (A(sub 6.63)/A(sub V) = 0.025), the [NiII] line can be used as a sensitive probe for the detection of recent supernovae. We have observed a sample of starburst galaxies at 6.63 micrometers using ISOCAM to search for the [NiII] emission line characteristic of recent supernovae. We did not detect any [NiII] line emission brighter than a 5-sigma limit of 5 mJy. We can set upper limits to the supernova rate in our sample, scaled ot the rate in M82, of less than 0.3 per year at the 90% confidence level using Bayesian methods. Assuming that a supernova would have a [NiII] line with the same luminosity as observed in SN1987A, we find less than 0.09 and 0.15 per year at the 50% and 67% confidence levels. These rates are somewhat less if a more normal type II supernovae has a [NiII] line luminosity greater than the line in SN1987A.

  10. Direct Measurement of the Supernova Rate in Starburst Galaxies

    NASA Technical Reports Server (NTRS)

    Bregman, Jesse D.; Temi, Pasquale; Rank, David; DeVincenzi, Donald L. (Technical Monitor)

    1999-01-01

    Supernovae play a key role in the dynamics, structure, and chemical evolution of galaxies. The massive stars that end their lives as supernovae live for short times. Many are still associated with dusty star formation regions when they explode, making them difficult to observe at visible wavelengths. In active star forming regions (galactic nuclei and starburst regions), dust extintion is especially severe. Thus, determining the supernova rate in the active star forming regions of galaxies, where the supernova rate can be one or two orders of magnitude higher than the average, has proven to be difficult. From observations of SN1987A, we know that the [NiII] 6.63 micron emission line was the strongest line in the infrared spectrum for a period of a year and a half after the explosion. Since dust extintion is much less at 6.63 pm than at visible wavelengths (A(sub 6.63)/A(sub V) = 0.025), the NiII line can be used as a sensitive probe for the detection of recent supernovae. We have observed a sample of starburst galaxies at 6.63 micron using ISOCAM to search for the NiII emission line characteristic of recent supernovae. We did not detect any NiII line emission brighter than a 5sigma limit of 5 mJy. We can set upper limits to the supernova rate in our sample, scaled to the rate in M82, of less than 0.3 per year at the 90% confidence level using Bayesian methods. Assuming that a supernova would have a NiII with the same luminosity as observed in SN1987A, we find less than 0.09 and 0.15 per year at the 50% and 67% confidence levels. These rates are somewhat less if a more normal type II supernovae has a NiII line luminosity greater than the line in SN1987A.

  11. Analytic Approximation of Carbon Condensation Issues in Type ii Supernovae

    NASA Astrophysics Data System (ADS)

    Clayton, Donald D.

    2013-01-01

    I present analytic approximations for some issues related to condensation of graphite, TiC, and silicon carbide in oxygen-rich cores of supernovae of Type II. Increased understanding, which mathematical analysis can support, renders researchers more receptive to condensation in O-rich supernova gases. Taking SN 1987A as typical, my first analysis shows why the abundance of CO molecules reaches an early maximum in which free carbon remains more abundant than CO. This analysis clarifies why O-rich gas cannot oxidize C if 56Co radioactivity is as strong as in SN 1987A. My next analysis shows that the CO abundance could be regarded as being in chemical equilibrium if the CO molecule is given an effective binding energy rather than its laboratory dissociation energy. The effective binding energy makes the thermal dissociation rate of CO equal to its radioactive dissociation rate. This preserves possible relevance for the concept of chemical equilibrium. My next analysis shows that the observed abundances of CO and SiO molecules in SN 1987A rule out frequent suggestions that equilibrium condensation of SUNOCONs has occurred following atomic mixing of the He-burning shell with more central zones in such a way as to reproduce roughly the observed spectrum of isotopes in SUNOCONs while preserving C/O > 1. He atoms admixed along with the excess carbon would destroy CO and SiO molecules, leaving their observed abundances unexplained. The final analysis argues that a chemical quasiequilibrium among grains (but not gas) may exist approximately during condensation, so that its computational use is partially justified as a guide to which mineral phases would be stable against reactions with gas. I illustrate this point with quasiequilibrium calculations by Ebel & Grossman that have shown that graphite is stable even when O/C >1 if prominent molecules are justifiably excluded from the calculation of chemical equilibrium.

  12. Fusion reactions of Ni,6458+124Sn

    NASA Astrophysics Data System (ADS)

    Jiang, C. L.; Stefanini, A. M.; Esbensen, H.; Rehm, K. E.; Almaraz-Calderon, S.; Avila, M. L.; Back, B. B.; Bourgin, D.; Corradi, L.; Courtin, S.; Fioretto, E.; Galtarossa, F.; Goasduff, A.; Haas, F.; Mazzocco, M. M.; Montanari, D.; Montagnoli, G.; Mijatovic, T.; Sagaidak, R.; Santiago-Gonzalez, D.; Scarlassara, F.; Strano, E. E.; Szilner, S.

    2015-04-01

    Measurements of fusion excitation functions of 58Ni+124Sn and 64Ni+124Sn are extended towards lower energy to cross sections of 1 μ b and are compared to detailed coupled-channels calculations. The calculations clearly show the importance of including transfer reactions in a coupled-channels treatment for such heavy systems. This result is different from the conclusion made in a previous article which claimed that the influence of transfer on fusion is not important for fusion reactions of Ni +Sn . In the energy region studied in this experiment no indication of fusion hindrance has been observed, which is consistent with a systematic study of this behavior.

  13. Electrical and Optical Characterization of Si-Ge-Sn

    DTIC Science & Technology

    2012-03-01

    found to be comparable to Ge, SiGeSn does appear to have promising uses as a photo- detector or solar cell . This is especially true if it possible...this type of efficiency , strain engineering had to be employed. Strain engineering can lead to several issues in making device quality structures...grown on Ge, Si, and GaAs substrates. Since Ge-Sn and Si-Ge-Sn are lattice matched [3] and have shown response in the entire telecom band [4], these all

  14. In vitro synthesis of vertebrate U1 snRNA.

    PubMed Central

    Lund, E; Dahlberg, J E

    1989-01-01

    We have developed a DNA-dependent in vitro transcription system for vertebrate snRNA genes. By isolating the nuclei (germinal vesicles, GVs) of Xenopus laevis oocytes under oil to maintain the in vivo composition of their internal milieu, we are able to prepare nuclei that retain their ability to synthesize snRNAs efficiently. Homogenates of these GVs synthesize correctly initiated and terminated U1 snRNA using exogenous X.laevis U1 genes as templates. The templates may be either injected into the nucleus prior to its isolation or added to the nuclear homogenate. Images PMID:2714253

  15. Electronic structure of Sn/Cu(100)-[Formula: see text].

    PubMed

    Martínez-Blanco, J; Joco, V; Fujii, J; Segovia, P; Michel, E G

    2009-02-04

    We present measurements of the Fermi surface and underlying band structure of Sn/Cu(100)-[Formula: see text]. This phase is observed for a coverage of 0.60-0.65 monolayers. Its electronic structure is characterized by a free-electron-like surface band folded with the reconstruction periodicity. At variance with other surface phases of Sn on Cu(100), no temperature-induced phase transition is observed for this phase from 100 K up to the desorption of Sn.

  16. Spectroscopic identification of SNe 2004ds and SN 2004dt

    NASA Astrophysics Data System (ADS)

    Gal-Yam, Avishay

    2004-08-01

    A. Gal-Yam, D. Fox and S. Kulkarni, California Institute of Technology, report on red spectra (range 550-780 nm) obtained by Kulkarni and Fox on Aug. 13.5 UT at the 10-m Keck I telescope (+ LRIS). The spectrum of of SN 2004ds (IAUC #8386), shows a broad, well-developed P-Cyg H_alpha line and suggests that this is a type II supernova. The spectrum of SN 2004dt (IAUC #8386), shows the distinctive Si II 6100 absorption trough around 6100 Angstrom, indicating this is a young SN Ia.

  17. SN 1991bg - A type Ia supernova with a difference

    NASA Technical Reports Server (NTRS)

    Leibundgut, Bruno; Kirshner, Robert P.; Phillips, Mark M.; Wells, Lisa A.; Suntzeff, N. B.; Hamuy, Mario; Schommer, R. A.; Walker, A. R.; Gonzalez, L.; Ugarte, P.

    1993-01-01

    While SN 1991bg is an unusual type Ia SN in such a feature as the brief duration of the photospheric phase, which ended only two weeks after maximum, it shares with other Ia SNs strong Si II and Ca II lines near maximum light. In addition, the light and color curve slopes are almost identical with the templates at late times. The spectral evolution of SN 1991bg is also unique but not unrecognizable; nevertheless, the peculiarities associated with this event complicate the fundamental question as to whether the Ia SNs make good standard candles.

  18. VizieR Online Data Catalog: Soft X-ray emission of Type Ia SN progenitors (Nielsen+, 2012)

    NASA Astrophysics Data System (ADS)

    Nielsen, M. T. B.; Voss, R.; Nelemans, G.

    2013-04-01

    By searching the Chandra Data Archive, we found pre-explosion images taken with the Advanced CCD Imaging Spectrometer (ACIS-S) at the positions of 10 nearby (<25Mpc) SNe Ia. The SNe in question are SN2002cv, SN2003cg, SN2004W, SN2006X, SN2006dd, SN2006mr, SN2007gi, SN2007sr, SN2008fp and SN2011fe. No obvious sources were found on the pre-explosion images for any of these SNe. For SN2002cv, SN2003cg, SN2004W, SN2006X, SN2006dd, SN2006mr, SN2007gi and SN2008fp, only a single pre-explosion Chandra image exists for each of the SNe, and SN2006dd and SN2006mr are on the same image. Several of these images have long (>30ks) exposure times. For SN2007sr and SN2011fe, multiple pre-explosion Chandra images exist, and these can be combined to give very long (several 100ks) exposure times. (3 data files).

  19. Cu6Sn5 Morphology Transition and Its Effect on Mechanical Properties of Eutectic Sn-Ag Solder Joints

    NASA Astrophysics Data System (ADS)

    Yang, Ming; Li, Mingyu; Wang, Ling; Fu, Yonggao; Kim, Jongmyung; Weng, Lvqian

    2011-02-01

    The morphologies of Cu6Sn5 grains formed at the interface between Sn-3.5Ag (wt.% unless otherwise specified) and Cu substrates were studied in this work. Reflow experiments were performed for 60 s at peak temperatures of 513 K, 533 K, 543 K, and 553 K. Two morphologies of interfacial Cu6Sn5 grains were observed in wetting reactions: prism type, above 543 K, and scallop type, below 533 K. During aging, the two morphologies gradually transitioned to layer type. These three morphologies could be transformed into each other as long as the corresponding condition changed. The morphology transition of Cu6Sn5 in the wetting reaction was explained by the change in Jackson's parameter with temperature. In addition, the effect of the Cu content in molten solder on interfacial Cu6Sn5 grains was examined. Significant differences in shear strength were observed for solder joints with different interfacial Cu6Sn5 morphologies in the case of a lower shear height. Joint strength is discussed in terms of the microstructure of the solder matrix and the morphology of interfacial Cu6Sn5 grains.

  20. The rotational spectra, potential function, Born-Oppenheimer breakdown, and magnetic shielding of SnSe and SnTe.

    PubMed

    Bizzocchi, Luca; Giuliano, Barbara M; Hess, Mareike; Grabow, Jens-Uwe

    2007-03-21

    The pure rotational spectra of 27 isotopic species of SnSe and SnTe have been measured in the frequency range of 5-24 GHz using a Fabry-Perot-type resonator pulsed-jet Fourier-transform microwave spectrometer. Gaseous samples of both chalcogenides were prepared by laser ablation of suitable target rods and were stabilized in supersonic jets of Ar. Global multi-isotopolog analyses of all available high-resolution data produced spectroscopic Dunham parameters Y01, Y11, Y21, Y31, Y02, and Y12 for both species, as well as Born-Oppenheimer breakdown (BOB) coefficients delta01 for Sn, Se, and Te. A direct fit of the same data sets to an appropriate radial Hamiltonian yielded analytic potential energy functions and BOB radial functions for the X 1Sigma+ electronic state of both SnSe and SnTe. Additionally, the magnetic hyperfine interaction produced by the dipolar nuclei 119Sn, 117Sn, 77Se, and 125Te was observed, yielding first determinations of the corresponding spin-rotation coupling constants.

  1. The rotational spectra, potential function, Born-Oppenheimer breakdown, and magnetic shielding of SnSe and SnTe

    NASA Astrophysics Data System (ADS)

    Bizzocchi, Luca; Giuliano, Barbara M.; Hess, Mareike; Grabow, Jens-Uwe

    2007-03-01

    The pure rotational spectra of 27 isotopic species of SnSe and SnTe have been measured in the frequency range of 5-24GHz using a Fabry-Pérot-type resonator pulsed-jet Fourier-transform microwave spectrometer. Gaseous samples of both chalcogenides were prepared by laser ablation of suitable target rods and were stabilized in supersonic jets of Ar. Global multi-isotopolog analyses of all available high-resolution data produced spectroscopic Dunham parameters Y01, Y11, Y21, Y31, Y02, and Y12 for both species, as well as Born-Oppenheimer breakdown (BOB) coefficients δ01 for Sn, Se, and Te. A direct fit of the same data sets to an appropriate radial Hamiltonian yielded analytic potential energy functions and BOB radial functions for the XΣ+1 electronic state of both SnSe and SnTe. Additionally, the magnetic hyperfine interaction produced by the dipolar nuclei Sn119, Sn117, Se77, and Te125 was observed, yielding first determinations of the corresponding spin-rotation coupling constants.

  2. Effect of Nb on the Growth Behavior of Co3Sn2 Phase in Undercooled Co-Sn Melts

    NASA Astrophysics Data System (ADS)

    Kang, Jilong; Xu, Wanqiang; Wei, Xiuxun; Ferry, Michael; Li, Jinfu

    2016-12-01

    The growth behavior of the primary β-Co3Sn2 phase in (Co67Sn33)100- x Nb x ( x = 0, 0.5, 0.8, 1.0) hypereutectic alloys at different melt undercoolings was investigated systematically. The growth pattern of the β-Co3Sn2 phase at low undercooling changes with the Nb content from fractal seaweed ( x = 0, 0.5) into dendrite ( x = 0.8) and then returns to fractal seaweed ( x = 1.0) as a response to the changes in interface energy anisotropy and interface kinetic anisotropy. As undercooling increases, the dendritic growth of the β-Co3Sn2 phase in (Co67Sn33)99.2Nb0.8 alloy gives way to fractal seaweed growth at an undercooling of 32 K (-241 °C). At larger undercooling, the fractal seaweed growth is further replaced by compact seaweed growth, which occurred in the other three alloys investigated. The growth velocity of the β-Co3Sn2 phase slightly increases at low and intermediate undercooling but clearly decreases at larger undercooling due to the Nb addition. The growth velocity sharply increases as the growth pattern of the Co3Sn2 phase transits from fractal seaweed into compact seaweed.

  3. Band alignments at strained Ge1‑x Sn x /relaxed Ge1‑y Sn y heterointerfaces

    NASA Astrophysics Data System (ADS)

    Lan, H.-S.; Liu, C. W.

    2017-04-01

    Type-I, type-II, reverse type-I, and reverse type-II band alignments are found theoretically in strained Ge1‑x Sn x (0  ⩽  x  ⩽  0.3) grown on relaxed Ge1‑y Sn y substrates (0  ⩽  y  ⩽  0.3) using the model-solid theory. The prerequisite bandgaps, and energy difference between the top valence band edge and the average valence band position of GeSn are obtained by the nonlocal empirical pseudopotential method. For the indirect-gap (L valleys) Ge1‑x Sn x on relaxed Ge1‑y Sn y , the band alignments are type-I and reverse type-I under biaxial compressive strain (x  >  y) and biaxial tensile strain (x  <  y), respectively. For the direct-gap (Γ valley) Ge1‑x Sn x on relaxed Ge1‑y Sn y , the biaxial compressive strain yields type-I and type-II alignment, while the biaxial tensile strain yields reverse type-I and reverse type-II alignments.

  4. Semiconducting ZnSnN2 thin films for Si/ZnSnN2 p-n junctions

    NASA Astrophysics Data System (ADS)

    Qin, Ruifeng; Cao, Hongtao; Liang, Lingyan; Xie, Yufang; Zhuge, Fei; Zhang, Hongliang; Gao, Junhua; Javaid, Kashif; Liu, Caichi; Sun, Weizhong

    2016-04-01

    ZnSnN2 is regarded as a promising photovoltaic absorber candidate due to earth-abundance, non-toxicity, and high absorption coefficient. However, it is still a great challenge to synthesize ZnSnN2 films with a low electron concentration, in order to promote the applications of ZnSnN2 as the core active layer in optoelectronic devices. In this work, polycrystalline and high resistance ZnSnN2 films were fabricated by magnetron sputtering technique, then semiconducting films were achieved after post-annealing, and finally Si/ZnSnN2 p-n junctions were constructed. The electron concentration and Hall mobility were enhanced from 2.77 × 1017 to 6.78 × 1017 cm-3 and from 0.37 to 2.07 cm2 V-1 s-1, corresponding to the annealing temperature from 200 to 350 °C. After annealing at 300 °C, the p-n junction exhibited the optimum rectifying characteristics, with a forward-to-reverse ratio over 103. The achievement of this ZnSnN2-based p-n junction makes an opening step forward to realize the practical application of the ZnSnN2 material. In addition, the nonideal behaviors of the p-n junctions under both positive and negative voltages are discussed, in hope of suggesting some ideas to further improve the rectifying characteristics.

  5. Defect-free high Sn-content GeSn on insulator grown by rapid melting growth

    PubMed Central

    Liu, Zhi; Cong, Hui; Yang, Fan; Li, Chuanbo; Zheng, Jun; Xue, Chunlai; Zuo, Yuhua; Cheng, Buwen; Wang, Qiming

    2016-01-01

    GeSn is an attractive semiconductor material for Si-based photonics. However, large lattice mismatch between GeSn and Si and the low solubility of Sn in Ge limit its development. In order to obtain high Sn-content GeSn on Si, it is normally grown at low temperature, which would lead to inevitable dislocations. Here, we reported a single-crystal defect-free graded GeSn on insulator (GSOI) stripes laterally grown by rapid melting growth (RMG). The Sn-content reaches to 14.2% at the end of the GSOI stripe. Transmission electron microscopy observation shows the GSOI stripe without stacking fault and dislocations. P-channel pseudo metal-oxide-semiconductor field effect transistors (MOSFETs) and metal-semiconductor-metal (MSM) Schottky junction photodetectors were fabricated on these GSOIs. Good transistor performance with a low field peak hole mobility of 402 cm2/Vs is obtained, which indicates a high-quality of this GSOI structure. Strong near-infrared and short-wave infrared optical absorption of the MSM photodetectors at 1550 nm and 2000 nm were observed. Owing to high Sn-content and defect-free, responsivity of 236 mA/W@-1.5 V is achieved at 1550 nm wavelength. In addition, responsivity reaches 154 mA/W@-1.5 V at 2000 nm with the optical absorption layer only 200 nm-thick, which is the highest value reported for GeSn junction photodetectors until now. PMID:27941825

  6. Defect-free high Sn-content GeSn on insulator grown by rapid melting growth

    NASA Astrophysics Data System (ADS)

    Liu, Zhi; Cong, Hui; Yang, Fan; Li, Chuanbo; Zheng, Jun; Xue, Chunlai; Zuo, Yuhua; Cheng, Buwen; Wang, Qiming

    2016-12-01

    GeSn is an attractive semiconductor material for Si-based photonics. However, large lattice mismatch between GeSn and Si and the low solubility of Sn in Ge limit its development. In order to obtain high Sn-content GeSn on Si, it is normally grown at low temperature, which would lead to inevitable dislocations. Here, we reported a single-crystal defect-free graded GeSn on insulator (GSOI) stripes laterally grown by rapid melting growth (RMG). The Sn-content reaches to 14.2% at the end of the GSOI stripe. Transmission electron microscopy observation shows the GSOI stripe without stacking fault and dislocations. P-channel pseudo metal-oxide-semiconductor field effect transistors (MOSFETs) and metal-semiconductor-metal (MSM) Schottky junction photodetectors were fabricated on these GSOIs. Good transistor performance with a low field peak hole mobility of 402 cm2/Vs is obtained, which indicates a high-quality of this GSOI structure. Strong near-infrared and short-wave infrared optical absorption of the MSM photodetectors at 1550 nm and 2000 nm were observed. Owing to high Sn-content and defect-free, responsivity of 236 mA/W@-1.5 V is achieved at 1550 nm wavelength. In addition, responsivity reaches 154 mA/W@-1.5 V at 2000 nm with the optical absorption layer only 200 nm-thick, which is the highest value reported for GeSn junction photodetectors until now.

  7. Effects of Sn addition on the microstructure, mechanical properties and corrosion behavior of Ti–Nb–Sn alloys

    SciTech Connect

    Moraes, Paulo E.L.; Contieri, Rodrigo J.; Lopes, Eder S.N.; Robin, Alain; Caram, Rubens

    2014-10-15

    Ti and Ti alloys are widely used in restorative surgery because of their good biocompatibility, enhanced mechanical behavior and high corrosion resistance in physiological media. The corrosion resistance of Ti-based materials is due to the spontaneous formation of the TiO{sub 2} oxide film on their surface, which exhibits elevated stability in biological fluids. Ti–Nb alloys, depending on the composition and the processing routes to which the alloys are subjected, have high mechanical strength combined with low elastic modulus. The addition of Sn to Ti–Nb alloys allows the phase transformations to be controlled, particularly the precipitation of ω phase. The aim of this study is to discuss the microstructure, mechanical properties and corrosion behavior of cast Ti–Nb alloys to which Sn has been added. Samples were centrifugally cast in a copper mold, and the microstructure was characterized using optical microscopy, scanning electron microscopy and X-ray diffractometry. Mechanical behavior evaluation was performed using Berkovich nanoindentation, Vickers hardness and compression tests. The corrosion behavior was evaluated in Ringer's solution at room temperature using electrochemical techniques. The results obtained suggested that the physical, mechanical and chemical behaviors of the Ti–Nb–Sn alloys are directly dependent on the Sn content. - Graphical abstract: Effects of Sn addition to the Ti–30Nb alloy on the elastic modulus. - Highlights: • Sn addition causes reduction of the ω phase precipitation. • Minimum Vickers hardness and elastic modulus occurred for 6 wt.% Sn content. • Addition of 6 wt.% Sn resulted in maximum ductility and minimum compression strength. • All Ti–30Nb–XSn (X = 0, 2, 4, 6, 8 and 10%) alloys are passive in Ringer's solution. • Highest corrosion resistance was observed for 6 wt.% Sn content.

  8. Follow-Up Observations of SN1999GI in NGC 3184

    NASA Astrophysics Data System (ADS)

    Schlegel, Eric

    1999-09-01

    Type II supernovae may all be X-ray sources but differences in behavior are becoming visible: normal SN II's fade quickly while the abnormal SN IIn's last for months, perhaps years. These suppositions are based upon very limited statistics: 2 normal SN II's and about 4-6 SN IIn's. The turn-on times are unknown, as are the half-lives. Two normal SN II's observed in the X-ray band are SN1980K (Canizares et al. 1982) and SN1999em (Fox & Lewin 1999, IAU Circ 7318). The turn-on time of these SNe appear to be nearly immediate. Radio and X-ray emission should be correlated, yet are not: SN1980K was an early radio source; SN1999em has not yet been detected. But a correlation with radio emission must be suspect with so little data. SN1999gi,the target of this TOO, represents a potential third norm

  9. Investigation into the Efficacy of Val-SN-38, a Valine-Ester Prodrug of the Anti-Cancer Agent SN-38

    PubMed Central

    Kwak, Eun-Young; Choi, Min-Koo; Yang, Su-Geun; Shim, Chang-Koo; Shim, Won-Sik

    2012-01-01

    We recently reported that Val-SN-38, a novel valine ester prodrug of SN-38, had greatly improved the intracellular accumulation of SN-38 in MCF-7 cell line, probably through enhanced uptake via amino acid transporters. In the present study, the efficacy of Val-SN-38 was further investigated both in vitro and in vivo. It was found that the in vitro cytotoxic effect of Val-SN-38 was similar to that of SN-38. Moreover, Val-SN-38 exhibited an equal potency to that of SN-38 in survival experiments in vivo. Because these results seemed to be contrary to the previous finding, further investigation was performed to find out the underlying cause of the contradiction. As only the lactone form is known to have cytotoxic activity, the proportion of lactone in Val-SN-38 and SN-38 was determined, but no differences were found. However, it turned out that Val-SN-38 had poor stability compared with SN-38, which resulted in a decrease in beneficial efficacy for Val-SN-38. Overall, the present study showed that a valine-added prodrug approach could be advantageous provided that the stability of the compound can be ensured. We believe this is a noteworthy study that unravels the discrepancy between intracellular accumulation and efficacy of valine-added prodrug. PMID:24130931

  10. Lithiation of Li2SnO3 and Li2SnS3 in context of Li-ion battery materials

    NASA Astrophysics Data System (ADS)

    Howard, Jason; Holzwarth, N. A. W.

    The closed pack layered crystal material (space group 15 (C 2 / c)) Li2 SnO3 has been studied as a possible anode material since the late 1990's. The material undergoes an irreversible decomposition to Li2 O and LiX Sn alloys during the first lithiation cycle. The crystal material Li2 SnS3 of the same structure was recently proposed as an electrolyte material. The question is posed whether Li2 SnS3 would be a good electrolyte or whether it could function as an anode material similar to Li2 SnO3 . In this research a model is proposed for the lithiation process of Li2 SnO3 and Li2 SnS3 ; Li - Li2 SnS3 interfaces are also examined. The results show Li2 SnO3 begins to decompose at approximately Li2 + 0 . 5 SnO3 . In Li2 SnS3 the lithiation process shows it can lithiate to Li2 + 1 SnS3 without significant lattice distortion, volume expansion, or decomposition. Li - Li2 SnS3 interfaces are shown to be unstable, showing the formation of Li2 S . Supported by NSF Grant DMR-1105485 and DMR-1507942.

  11. 119Sn-NMR investigations on superconducting Ca3Ir4Sn13: Evidence for multigap superconductivity

    DOE PAGES

    Sarkar, R.; Petrovic, C.; Bruckner, F.; ...

    2015-09-25

    In this study, we report bulk superconductivity (SC) in Ca3Ir4Sn13 by means of 119Sn nuclear magnetic resonance (NMR) experiments. Two classical signatures of BCS superconductivity in spin-lattice relaxation rate (1/T1), namely the Hebel–Slichter coherence peak just below the Tc, and the exponential decay in the superconducting phase, are evident. The noticeable decrease of 119Sn Knight shift below Tc indicates spin-singlet superconductivity. The temperature dependence of the spin-lattice relaxation rate 119(1/T1) is convincingly described by the multigap isotropic superconducting gap. NMR experiments do not witness any sign of enhanced spin fluctuations.

  12. Investigation by Mössbauer spectroscopy of Sn redox transformations during H2/O2 titration on Pt/Al2O3Sn-Cl and Pt/Al2O3SnIn-Cl naphtha reforming catalysts

    NASA Astrophysics Data System (ADS)

    Jahel, Ali; Avenier, Priscilla; Lacombe, Sylvie; Olivier-Fourcade, Josette; Jumas, Jean-Claude

    2010-03-01

    Bimetallic Pt/Al2O3Sn-Cl and trimetallic Pt/Al2O3SnIn-Cl catalysts were characterized by H2/O2 double titration and 119Sn Mössbauer spectroscopy. The addition of Sn or both Sn and In to the monometallic Pt/Al2O3-Cl catalyst leads to an increase in the volume of chemisorbed O2 at each titration. For bimetallic and trimetallic catalysts the increase in the Pt dispersion, calculated from the second oxygen titre, abnormally surpasses the barrier of 100%. Characterization of samples obtained after each step of the H2/O2 titration sequence using 119Sn Mössbauer spectroscopy allowed to follow the redox transformations of Sn species suspected of contributing to O2 consumption. 119Sn Mössbauer spectra show that after reduction unalloyed metalic Sn and PtSn alloy phases are formed in bi- and trimetallic catalysts respectively. These metallic phases are oxidized upon the first oxygen titre into the so-called PtxSn(O) oxometalic phases. The index calculated from this titre thus expresses the Pt-Sn bimetallic character and is called the bimetallicity index (BMI). These latter phases further undergo reduction and regeneration (oxidation) upon the second O2 titre and thus contribute to the calculated Pt dispersion as well.

  13. Astrophysics and cosmology confront the 17 keV neutrino

    NASA Technical Reports Server (NTRS)

    Kolb, Edward W.; Turner, Michael S.

    1991-01-01

    A host of astrophysical and cosmological arguments severely constrain the properties of a 17 keV Dirac neutrino. Such a neutrino must have interactions beyond those of the standard electroweak theory to reduce its cosmic abundance (through decay or annihilation) by a factor of two hundred. A predicament arises because the additional helicity states of the neutrino necessary to construct a Dirac mass must have interactions strong enough to evade the astrophysical bound from SN 1987A, but weak enough to avoid violating the bound from primordial nucleosynthesis.

  14. Neutron stars: A cosmic hadron physics laboratory

    NASA Technical Reports Server (NTRS)

    Pines, David

    1989-01-01

    A progress report is given on neutron stars as a cosmic hadron physics laboratory. Particular attention is paid to the crustal neutron superfluid, and to the information concerning its properties which may be deduced from observations of pulsar glitches and postglitch behavior. Current observational evidence concerning the softness or stiffness of the high density neutron matter equation of state is reviewed briefly, and the (revolutionary) implications of a confirmation of the existence of a 0.5 ms pulsar at the core of (Supernova) SN1987A are discussed.

  15. Positron Survival in Type II Supernovae

    DTIC Science & Technology

    1989-05-01

    56Co (daughter of 56Ni) or 4Ti. He predicted that both of these nuclei should be produced during explosive nucleosynthesis . The production of this...turned to cobalt at times of interest to us. I have therefore assumed that 56Co was the explosive nucleosynthesis product. The half-life of 56Co is 78.8...sixth edition, John Wiley and Sons, Inc., 1967, p. 189. Nomoto, K., et al. , "SN 1987A: Progenitor, Nucleosynthesis and Light Curves", 1988, preprint

  16. Ultraviolet observations of LMC nova 1988

    NASA Technical Reports Server (NTRS)

    Starrfield, S.; Stryker, L. L.; Sonneborn, G.; Sparks, Warren M.; Sion, E. M.; Wagner, R. M.; Ferland, Gary; Gallagher, J. S.; Wade, R.; Williams, R. E.

    1988-01-01

    The IUE obtained ultraviolet spectra of a nova in an external galaxy. The spectral features do not seem unusual for a nova at maximum but it is hoped to be able to follow it for a long enough time to be able to study the high ionization lines that appear when the density drops to lower values (the nebular stage). A high dispersion spectrum was also obtained to assist in the line identification and to study the line of sight to the LMC 1 deg of arc away from SN 1987A.

  17. Ultraviolet observations of LMC nova 1988

    SciTech Connect

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

    1988-01-01

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

  18. Solar Neutrino flare detection in Hyperkamiokande and SK

    NASA Astrophysics Data System (ADS)

    Fargion, Daniele

    2016-07-01

    The possible buid and near activity of a Megaton neutrino detection in HyperKamiokande and the older SK implementation by Gadolinium liqid might open to future detection of largest solar flare (pion trace at tens MeV) electron neutrino and antineutrino. The multiwave detection of X-gamma and neutrino event might offer a deep view of such solar acelleration and of neutrino flavor mix along its flight. The possoble near future discover of such events will open a third neutrino astronomy windows after rarest SN 1987A and persistent Solar nuclear signals.

  19. Muon-induced spallation backgrounds in DUNE

    NASA Astrophysics Data System (ADS)

    Zhu, Guanying; Li, Shirley; Beacom, John

    2017-01-01

    Galactic supernovae are rare, just a few per century, so it is important to be prepared. If we are, then the long-baseline detector DUNE could detect thousands of events, compared to the tens from SN 1987A. An important question is backgrounds from muon-induced spallation reactions. We simulate particle energy-loss processes in liquid argon, and compare relevant isotope yields with those in the water-Cherenkov detector SuperK. Our approach will help optimize the design of DUNE and further benefit the study of supernova neutrinos. GZ, SWL, and JFB are supported by NSF Grant PHY-1404311.

  20. Active search strategies and the SETI protocols - Is there a conflict?

    NASA Astrophysics Data System (ADS)

    Lemarchand, Guillermo A.; Tarter, Donald E.

    1993-10-01

    The widely approved Declaration of Principles Concerning Activities following the Detection of Extraterrestrial Intelligence and the Proposed Protocol for Sending of Communications to Extraterrestrial Intelligence are examined with respect to how they apply to active as opposed to passive search strategies by radio astronomers. This article maintains that the existing protocols do not and should not impede active search strategies. An active search strategy based on the transmission of an interstellar terrestrial message using the synchronization of the SN 1987A hyperboloid is described. A brief discussion is made concerning the social 'pros' and 'cons' of an active search for humanity.

  1. Plasmon effects in light scalar and pseudo-scalar emission from a supernova.

    NASA Astrophysics Data System (ADS)

    Altherr, T.

    1991-05-01

    The emission of light scalars and pseudo-scalars (axion-like particles) coupled to the chromo/electric field from a QCD/AED plasma at high temperature and very high density is studied in detail. The calculation is then applied to the SN 1987A event for which new bounds on the Peccei-Quinn symmetry breaking scale fa are derived, fa ⪆ 3×109GeV in presence of a quark-gluon core and fa ⪆ 107GeV, which is the same bound as the one obtained from red giant stars, by considering axion emission from the electron gas.

  2. Atomic and molecular supernovae

    NASA Technical Reports Server (NTRS)

    Liu, Weihong

    1997-01-01

    Atomic and molecular physics of supernovae is discussed with an emphasis on the importance of detailed treatments of the critical atomic and molecular processes with the best available atomic and molecular data. The observations of molecules in SN 1987A are interpreted through a combination of spectral and chemical modelings, leading to strong constraints on the mixing and nucleosynthesis of the supernova. The non-equilibrium chemistry is used to argue that carbon dust can form in the oxygen-rich clumps where the efficient molecular cooling makes the nucleation of dust grains possible. For Type Ia supernovae, the analyses of their nebular spectra lead to strong constraints on the supernova explosion models.

  3. Probing low-scale quantum gravity with high-energy neutrinos

    SciTech Connect

    Ennadifi, Salah Eddine

    2013-05-15

    Motivated by the quantum structure of space-time at high scales M{sub QG}, we study the propagation behavior of the high-energy neutrino within the quantum gravity effect. We consider the possible induced dispersive effect and derive the resulting vacuum refraction index {eta}{sub vac}(E{sub {nu}}) Asymptotically-Equal-To 1 + E{sub {nu}}{sup 2}/M{sub QG}{sup 2}. Then, by referring to the SN1987A and basing on the recorded neutrino data we approach the corresponding scale M{sub QG} Asymptotically-Equal-To 10{sup 4} GeV.

  4. Radioactivities and gamma-rays from supernovae

    NASA Technical Reports Server (NTRS)

    Woosley, S. E.

    1991-01-01

    An account is given of the implications of several calculations relevant to the estimation of gamma-ray signals from various explosive astronomical phenomena. After discussing efforts to constrain the amounts of Ni-57 and Ti-44 produced in SN 1987A, attention is given to the production of Al-27 in massive stars and SNs. A 'delayed detonation' model of type Ia SNs is proposed, and the gamma-ray signal which may be expected when a bare white dwarf collapses directly into a neutron star is discussed.

  5. Astrophysical and cosmological constraints to neutrino properties

    NASA Technical Reports Server (NTRS)

    Kolb, Edward W.; Schramm, David N.; Turner, Michael S.

    1989-01-01

    The astrophysical and cosmological constraints on neutrino properties (masses, lifetimes, numbers of flavors, etc.) are reviewed. The freeze out of neutrinos in the early Universe are discussed and then the cosmological limits on masses for stable neutrinos are derived. The freeze out argument coupled with observational limits is then used to constrain decaying neutrinos as well. The limits to neutrino properties which follow from SN1987A are then reviewed. The constraint from the big bang nucleosynthesis on the number of neutrino flavors is also considered. Astrophysical constraints on neutrino-mixing as well as future observations of relevance to neutrino physics are briefly discussed.

  6. Probing low-scale quantum gravity with high-energy neutrinos

    NASA Astrophysics Data System (ADS)

    Ennadifi, Salah Eddine

    2013-05-01

    Motivated by the quantum structure of space-time at high scales M QG, we study the propagation behavior of the high-energy neutrino within the quantum gravity effect. We consider the possible induced dispersive effect and derive the resulting vacuum refraction index ηvac( E ν) ≃ 1 + E {ν/2}/ M {QG/2}. Then, by referring to the SN1987A and basing on the recorded neutrino data we approach the corresponding scale M QG ≃ 104 GeV.

  7. Mass determination of neutrinos

    NASA Technical Reports Server (NTRS)

    Chiu, Hong-Yee

    1988-01-01

    A time-energy correlation method has been developed to determine the signature of a nonzero neutrino mass in a small sample of neutrinos detected from a distant source. The method is applied to the Kamiokande II (Hirata et al., 1987) and IMB (Bionta et al., 1987) observations of neutrino bursts from SN 1987A. Using the Kamiokande II data, the neutrino rest mass is estimated at 2.8 + 2.0, - 1.4 eV and the initial neutrino pulse is found to be less than 0.3 sec full width, followed by an emission tail lasting at least 10 sec.

  8. Astrophysics and cosmology confront the 17-keV neutrino

    NASA Technical Reports Server (NTRS)

    Kolb, Edward W.; Turner, Michael S.

    1991-01-01

    A host of astrophysical and cosmological arguments severely constrain the properties of a 17 keV Dirac neutrino. Such a neutrino must have interactions beyond those of the standard electroweak theory to reduce its cosmic abundance (through decay or annihilation) by a factor of two hundred. A predicament arises because the additional helicity states of the neutrino necessary to construct a Dirac mass must have interactions strong enough to evade the astrophysical bound from SN 1987A, but weak enough to avoid violating the bound from primordial nucleosynthesis.

  9. 3 Neutrino mass experiments fit a strange 3 + 3 model, but will KATRIN reveal the model's unique 3-part signature?

    NASA Astrophysics Data System (ADS)

    Ehrlich, R.

    2016-12-01

    Evidence is presented in support of an unconventional 3 + 3 model of the neutrino mass eigenstates with specific m2 > 0 and m2 < 0 masses. The two large m2 > 0 masses of the model were originally suggested based on a SN 1987A analysis, and they were further supported by several dark matter fits. The new evidence for one of the m2 > 0 mass values comes from an analysis of published data from the three most precise tritium β - decay experiments. The KATRIN experiment by virtue of a unique 3-part signature should either confirm or reject the model in its entirety.

  10. Light Echoes of Historic Transients

    NASA Astrophysics Data System (ADS)

    Rest, Armin; Sinnott, B.; Welch, D. L.; Prieto, J. L.; Bianco, F.

    2014-01-01

    Light echoes, light from a variable source scattered off dust, have been observed for over a century. The recent discovery of light echoes around centuries-old supernovae in the Milky Way and the Large Magellanic Cloud have allowed the spectroscopic characterization of these events, even without contemporaneous photometry and spectroscopy using modern instrumentation. Here we review the recent scientific advances using light echoes of ancient and historic transients, and focus on our latest work on SN 1987A's and Eta Carinae's light echoes.

  11. The GRAD high-altitude balloon flight over Antarctica

    NASA Technical Reports Server (NTRS)

    Eichhorn, G.; Coldwell, R. L.; Dunnam, F. E.; Rester, A. C.; Trombka, J. I.; Starr, R.

    1989-01-01

    The Gamma Ray Advanced Detector (GRAD) consists of a n-type germanium detector inside an active bismuth-germanate Compton and charged particle shield with additional active plastic shielding across the aperture. It will be flown on a high-altitude balloon at 36 km altitude at a latitude of 78 deg S over Antarctica for observations of gamma radiation emitted by the radioactive decay of Co-56 in the supernova SN1987A, for assessment of the performance of bismuth-germanate scintillation material in the radiation environment of near space, for gathering information on the gamma-ray background over Antarctica, and for testing fault-tolerant software.

  12. New experimental results on neutrino mixing and decay.

    NASA Astrophysics Data System (ADS)

    Oberauer, L.; von Feilitzsch, F.; Hagner, C.; Kempf, G.; Mößbauer, R. L.; Declais, Y.; Kajfasz, E.

    The search for neutrino decay is a sensitive method to look for very small neutrino mixing parameter. The authors report about the status of an decay experiment performed at a reactor in Bugey and present preliminary new experimental limits on the coupling of a heavy neutrino to the electron state. Additionally new experimental lifetime bounds on the radiative decay mode are given. Rigid laboratory limits on this decay mode for the hypothetical 17 keV neutrino are presented. Limits on the radiative decay of a 17 keV neutrino obtained from the supernova SN 1987A are discussed.

  13. Electrodeposition of Pb-free Sn alloys in pulsed current

    NASA Astrophysics Data System (ADS)

    Neveu, B.; Lallemand, F.; Poupon, G.; Mekhalif, Z.

    2006-03-01

    A pulsed electrodeposition method is applied to the preparation of Pb-free Sn alloys solder bumps for flip-chip bonding with the aid of a photolithography. Sn-Ag alloy films with near eutectic compositions (Sn-3.5% Ag) were obtained using a pyrophosphate-iodide plating baths regardless under direct or pulsed current. The composition and the morphology of electrodeposits were examinated by SEM and X-ray photoelectron spectroscopy (XPS). The main results revealed that the organic additives affect the electrochemical reduction of tin-silver and the direct consequence on making Sn-Ag alloy is a decreased deposition rate. However, the addition of additives in the plating bath suppressed the dendritic tin-silver growth by adsorption on the deposited surface. Pulsed electrodeposition is shown to be an interesting approach to elaborate bumps with smooth and homogeneous surfaces.

  14. Physical properties of single crystalline BaSn{sub 5}

    SciTech Connect

    Lin, Xiao; Budko, Sergey; Canfield, Paul

    2012-01-30

    We present a comprehensive study of the binary intermetallic superconductor, BaSn{sub 5}. High-quality single crystalline BaSn{sub 5} was grown out of a Sn flux. Detailed thermodynamic and transport measurements were performed to study BaSn{sub 5}'s normal and superconducting state properties. This material appears to be a strongly coupled, multiband superconductor. H{sub c2}(T) is almost isotropic. De Haas–van Alphen oscillations were observed and two effective masses were estimated from the FFT spectra. Hydrostatic pressure causes a decrease in the superconducting transition temperature at the rate of ≈−0.053 ± 0.001 K/kbar.

  15. SnS2 Thin Film Deposition by Spray Pyrolysis

    NASA Astrophysics Data System (ADS)

    Jaber, Abdallah Yahia; Alamri, Saleh Noaiman; Aida, Mohammed Salah

    2012-06-01

    Tin disulfide (SnS2) thin films have been synthesized using a simplified spray pyrolysis technique using a perfume atomizer. The films were deposited using two different solutions prepared by the dilution of SnCl2 and thiourea in distilled water and in methanol. The obtained films have a microcrystalline structure. The film deposited using methanol as the solvent is nearly stochiometric SnS2 with a spinel phase having a (001) preferential orientation. The film prepared with an aqueous solution is Sn-rich. Scanning electronic microscopy (SEM) images reveal that the film deposited with the aqueous solution is rough and is formed with large wires. However, the film deposited with methanol is dense and smooth. Conductivity measurements indicate that the aqueous solution leads to an n-type semiconductor, while methanol leads to a p-type semiconductor.

  16. Stille couplings catalytic in tin: a "Sn-F" approach.

    PubMed

    Maleczka, R E; Gallagher, W P

    2001-12-27

    A new tin recycling method for Stille couplings catalytic in tin is reported. PMHS made hypercoordinate by KF((aq)) allows Me(3)SnH to be efficiently recycled during a Pd(0)-catalyzed hydrostannation/Stille cascade. Relative to previously disclosed protocols, reaction times are shorter and because this process is believed to proceed through a Me(3)SnF intermediate the hazards and problems associated with trimethyltins are also diminished.[reaction: see text

  17. GROND followup of DLT17h/SN 2017ahn

    NASA Astrophysics Data System (ADS)

    Chen, Ting-Wan; Schady, Patricia

    2017-02-01

    On behalf of the GROND SN team we observed the field of a Type II supernova DLT17h/SN 2017ahn in NGC3318 (Tartaglia et al. ATel #10058; Hosseinzadeh et al. ATel #10059) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m MPG telescope at the ESO La Silla Observatory (Chile).

  18. Spectroscopic Properties and Potential Energy Curves of SnF +

    NASA Astrophysics Data System (ADS)

    Balasubramanian, K.; Xu, H.

    1995-06-01

    Spectroscopic properties and potential energy curves of several electronic states of SnF+ are computed using the complete active space self-consistent field (CASSCF) followed by first- and second-order configuration interaction (FOCI, SOCI) methods that include up to 1.6 million configurations. Spin-orbit effects were incorporated using the relativistic configuration interaction (RCI) method. Spectroscopic properties of several excited electronic states of SnF+ are reported, none of which is observed at present.

  19. In situ visualization of metallurgical reactions in nanoscale Cu/Sn diffusion couples.

    PubMed

    Yin, Qiyue; Gao, Fan; Gu, Zhiyong; Stach, Eric A; Zhou, Guangwen

    2015-03-21

    The Cu-Sn metallurgical soldering reaction in two-segmented Cu-Sn nanowires is studied by in situ transmission electron microscopy. By varying the relative lengths of Cu and Sn segments, we show that the metallurgical reaction results in a Cu-Sn solid solution for small Sn/Cu length ratio while Cu-Sn intermetallic compounds (IMCs) for larger Sn/Cu length ratios. Upon heating the nanowires to ∼500 °C, two phase transformation pathways occur, η-Cu6Sn5 → ε-Cu3Sn → δ-Cu41Sn11 for nanowires with a long Cu segment and η-Cu6Sn5 → ε-Cu3Sn → γ-Cu3Sn with a short Cu segment. The evolution of Kirkendall voids in the nanowires demonstrates that Cu diffuses faster than Sn in IMCs. Void growth results in the nanowire breakage that shuts off the inter-diffusion of Cu and Sn and thus leads to changes in the phase transformation pathway in the IMCs.

  20. Effect of Sn on methane decomposition over Fe supported catalysts to produce carbon

    NASA Astrophysics Data System (ADS)

    Oliveira, Patrícia F.; Ribeiro, Leandro P.; Rosmaninho, Marcelo G.; Ardisson, José D.; Dias, Anderson; Lago, Rochel M.

    2011-11-01

    In this work, alumina-supported Sn containing Fe catalysts were investigated in CVD reactions (Chemical Vapor Deposition) using methane for carbon production. The catalysts were prepared with 10 wt.% of Fe (as Fe2O3) and 3, 6 and 12 wt.% of Sn (as SnO2) supported on Al2O3 named hereon Fe10Sn3A, Fe5Sn6A and Fe10Sn12A, respectively. These catalysts were characterized by SEM, TPCVD, TPR, TG, Raman, XRD and 57Fe and 119Sn Mössbauer spectroscopy. Methane reacts with Fe10A catalyst (without Sn) in the temperature range 680-900°C to produce mainly Fe0, Fe3C and 20 wt.% of carbon deposition. TPR and TPCVD clearly showed that Sn strongly hinders the CH4 reaction over Fe catalyst. 57Fe Mössbauer suggested that in the presence of Sn the reduction of Fe + 3 by methane becomes very difficult. 119Sn Mössbauer showed Sn + 4 species strongly interact with metallic iron after CVD, producing iron-tin phases such as Fe3SnC and FeSn2. This interaction Sn-Fe increases the CVD temperatures and decreases the carbon yield leading to the production of more organized forms of carbon such as carbon nanotubes, nanofibers and graphite.