WorldWideScience

Sample records for ground-hugging ejecta flow

  1. A formation mechanism for concentric ridges in ejecta surrounding impact craters in a layer of fine glass beads

    Science.gov (United States)

    Suzuki, Ayako I.; Nakamura, Akiko M.; Kadono, Toshihiko; Wada, Koji; Yamamoto, Satoru; Arakawa, Masahiko

    2013-07-01

    Ejecta patterns are experimentally examined around craters formed in a layer of glass beads by vertical impacts at low velocities. The diameters of the constituent glass beads of three different targets range 53-63 μm, 90-106 μm, and 355-500 μm. The impact velocities and ambient pressures range from a few to 240 m s-1 and from 500 Pa to the atmospheric pressure, respectively. Various ejecta patterns are observed around craters and are classified into two major classes based on whether they have concentric ridges or not. We propose a possible formation model for the ridges in which the wake created by a projectile as it passes through the atmosphere causes the crater rim to collapse: The model can explain the observation that the degree of collapse of the resultant crater rim depends on the impact velocity and ambient pressure. Using the ratio between the hydrodynamic drag of the airflow induced by the wake and the gravitational force of the degraded part of the rim, we calculate the critical conditions of the impact velocity and ambient pressure necessary for the wake to erode the rim. The conditions turn out to be roughly consistent with the boundary between the two morphological classes. As a result, it is possible that the projectile wake triggers the collapse of the crater rim, leading to a ground-hugging flow that settles to form the distal ridge observed in this study. This mechanism may play a role in producing ejecta morphologies on planetary bodies with atmosphere.

  2. Chicxulub Ejecta Dynamics

    Science.gov (United States)

    OKeefe, John D.; Stewart, Sarah T.; Ahrens, Thomas J.

    2001-01-01

    We modeled in detail the ejecta dynamics associated with the Chicxulub impact. We determined: (1) ejecta trajectories, (2) stratigraphic motions, (3) depth of ejecta stages, (4) thermodynamic histories of the ejecta particles, and (5) the final ejecta distribution. Additional information is contained in the original extended abstract.

  3. Butterfly Ejecta

    Science.gov (United States)

    2003-01-01

    [figure removed for brevity, see original site] Released 4 September 2003In the heavily cratered southern highlands of Mars, the type of crater seen in this THEMIS visible image is relatively rare. Elliptical craters with 'butterfly' ejecta patterns make up roughly 5% of the total crater population of Mars. They are caused by impactors which hit the surface at oblique, or very shallow angles. Similar craters are also seen in about the same abundance on the Moon and Venus.Image information: VIS instrument. Latitude -24.6, Longitude 41 East (319 West). 19 meter/pixel resolution.Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  4. Butterfly Ejecta

    Science.gov (United States)

    2003-01-01

    [figure removed for brevity, see original site] Released 4 September 2003In the heavily cratered southern highlands of Mars, the type of crater seen in this THEMIS visible image is relatively rare. Elliptical craters with 'butterfly' ejecta patterns make up roughly 5% of the total crater population of Mars. They are caused by impactors which hit the surface at oblique, or very shallow angles. Similar craters are also seen in about the same abundance on the Moon and Venus.Image information: VIS instrument. Latitude -24.6, Longitude 41 East (319 West). 19 meter/pixel resolution.Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  5. Ejecta Yardangs

    Science.gov (United States)

    2004-01-01

    [figure removed for brevity, see original site] Released 15 July 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth. Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms. The yardangs in today's image are the remains of the rim and ejecta of the large impact crater at the top right of the image. The black pixels are due to exposure saturation. Image information: VIS instrument. Latitude -1.9, Longitude 152.8 East (207.2 West). 19 meter/pixel resolution. Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter

  6. Chicxulub Impact Ejecta in Belize

    Science.gov (United States)

    Ocampo, A.; Pope, K.; Fischer, A.; Alvarez, W.; Fouke, B.; Asaro, F.; Webster, C., Jr.; Vega, F.; Smith, J.; Fritsche, A. E.

    1997-01-01

    Chicxulub ejecta deposits in Belize provide the closest exposures of ejecta to the crater and the only exposures of proximal ejecta deposited in a terrestrial environment. A quarry on Albion Island in northern Belize exposes Late Cretaceous, possibly Maastrichtian, carbonate platform sediments that were folded, eroded, and subaerially weathered prior to the deposition of coarse ejecta from Chicxulub. These ejecta deposits are composed of a basal, about 1-m-thick clay and dolomite Spheroid Bed overlain by a about 15-m-thick coarse Diamictite Bed. Many and perhaps most of the clay spheroids are altered glass. Many dolomite spheroids have concentric layers and angular cores are probably of accretionary lapilli origin. A slight Ir concentration (111-152 ppt) was detected in the base of the Spheroid Bed. The Diamictite Bed contains about 10% altered glass, rare shocked quartz, 3-8 m diameter boulders and striated and polished cobbles, one with a penetrating rock chip that plastically deformed the cobble. Ejecta deposits extend to the surface at Albion and the maximum thickness in this area is not known. Ejecta deposits are exposed in several roadside quarries in the Cayo District of central Belize. The Late Cretaceous here is also represented by carbonate platform sediments. The upper surface of the carbonate platform is a highly irregular and extensively recrystallized horizon possibly representing deep karst weathering. Approximately 30 in of diamictite overlies this horizon with a texture similar to the Diamictite Bed at the Albion quarry, but with a more diverse lithology. In three locations the Cayo diamictites, contain red clay layers with abundant polished and striated limestone pebbles and cobbles called Pook's Pebbles, several of which have penetrating rock chips and ablated surfaces. We interpret the Albion Spheroid Bed as a deposit from the impact vapor plume and the Albion and Cayo diamictites as the result of a turbulent flow that contained debris derived

  7. A Precambrian proximal ejecta blanket from Scotland

    Science.gov (United States)

    Amor, Kenneth; Hesselbo, Stephen P.; Porcelli, Don; Thackrey, Scott; Parnell, John

    2008-04-01

    Ejecta blankets around impact craters are rarely preserved onEarth. Although impact craters are ubiquitous on solid bodiesthroughout the solar system, on Earth they are rapidly effaced,and few records exist of the processes that occur during emplacementof ejecta. The Stac Fada Member of the Precambrian Stoer Groupin Scotland has previously been described as volcanic in origin.However, shocked quartz and biotite provide evidence for high-pressureshock metamorphism, while chromium isotope values and elevatedabundances of platinum group metals and siderophile elementsindicate addition of meteoritic material. Thus, the unit isreinterpreted here as having an impact origin. The ejecta blanketreaches >20 m in thickness and contains abundant dark green,vesicular, devitrified glass fragments. Field observations suggestthat the deposit was emplaced as a single fluidized flow thatformed as a result of an impact into water-saturated sedimentarystrata. The continental geological setting and presence of groundwatermake this deposit an analogue for Martian fluidized ejecta blankets.

  8. Double-layered ejecta craters on Mars: morphology, formation, and a comparison with the Ries ejecta blanket

    Science.gov (United States)

    Kenkmann, Thomas; Wulf, Gerwin; Sturm, Sebastian; Pietrek, Alexa

    2015-04-01

    The ejecta blankets of impact craters in volatile-rich environments often show characteristic layered ejecta morphologies. The so-called double-layer ejecta (DLE) craters are probably the most confusing crater types showing two ejecta layers with distinct morphologies. A phenomenological ejecta excavation and emplacement model for DLE craters is proposed based on a detailed case study of the Martian crater Steinheim - a textbook like, pristine DLE crater - and studies of other DLE craters [1]. The observations show that DLE craters on Mars are the result of an impact event into a rock/ice mixture that produces large amounts of shock-induced vaporization and melting of ground ice. The deposits of the ejecta curtain are wet in the distal part and dryer in composition in the proximal part. As a result, the outer ejecta layer is emplaced as medial and distal ejecta that propagate outwards in a fluid saturated debris flow mode after landing overrunning previously formed secondary craters. In contrast, the inner ejecta layer is formed by a translational slide of the proximal ejecta deposits. This slide overruns and superimposes parts of the outer ejecta layer. Basal melting of the ice components of the ejecta volumes at the transient crater rim is induced by frictional heating and the enhanced pressure at depth. The results indicate similar processes also for other planetary bodies with volatile-rich environments, such as Ganymede, Europa or the Earth. The Ries crater on Earth has a similar ejecta thickness distribution as DLE craters on Mars [2]. Here basal sliding and fluidization of the ejecta increases outward by the entrainment of locally derived Tertiary sands and clays, that are saturated with groundwater. References: [1] Wulf, G. & Kenkmann, T. (2015) Met. Planet. Sci. (in press); [2] Sturm, S., Wulf. G., Jung, D. & Kenkmann, T. (2013) Geology 41, 531-534.

  9. Molecules in supernova ejecta

    CERN Document Server

    Cherchneff, Isabelle

    2011-01-01

    The first molecules detected at infrared wavelengths in the ejecta of a Type II supernova, namely SN1987A, consisted of CO and SiO. Since then, confirmation of the formation of these two species in several other supernovae a few hundred days after explosion has been obtained. However, supernova environments appear to hamper the synthesis of large, complex species due to the lack of microscopically-mixed hydrogen deep in supernova cores. Because these environments also form carbon and silicate dust, it is of importance to understand the role played by molecules in the depletion of elements and how chemical species get incorporated into dust grains. In the present paper, we review our current knowledge of the molecular component of supernova ejecta, and present new trends and results on the synthesis of molecules in these harsh, explosive events.

  10. Impact melt rocks from the Ries structure, Germany: an origin as impact melt flows?

    Science.gov (United States)

    Osinski, Gordon R.

    2004-10-01

    The production of impact melt rocks and glasses is a characteristic feature of hypervelocity impact events on Earth and other planetary bodies. This investigation represents the first detailed study of an unusual series of coherent impact melt rocks intermittently exposed around the periphery of the ~24-km diameter, ~14.5 Ma Ries impact structure, Germany. Optical and analytical scanning electron microscopy (SEM) reveals that the groundmass comprises sanidine, plagioclase, quartz and ilmenite (decreasing order of abundance) with the interstices filled by either fresh or devitrified glassy mesostasis. Primary crystallites display skeletal, dendritic and/or spherulitic textures indicating rapid crystallization from a melt. The mesostasis is characterized by extreme chemical heterogeneity (e.g., FeO and Al 2O 3 contents from ~1 to ~62-80 wt.%). This is likely due to a combination of crystal-liquid fractionation during rapid cooling and crystallization of an originally incompletely homogenized melt. Vapor phase crystallization of sanidine and cristobalite occurred in miarolitic cavities during late-stage cooling of the impact melts. The most likely protolith for the impact melt rocks are granitic rocks present in the crystalline basement target. The high volatile content of the mesostasis suggests that a large volatile component was retained from this protolith. Field observations together with analytical data and micro-textures indicate that the Ries impact melt rocks were molten at the time of, and after, deposition. Field relations with other impactites also suggest that these rocks were emplaced subsequent to the excavation stage of crater formation and that they are not, therefore, ballistic ejecta. Thus, it is proposed that the Ries impact melt rocks were emplaced as ground-hugging impact melt flows that emanated from different regions of the evolving transient cavity during the modification stage of crater formation. This is consistent with, and in fact

  11. Chicxulub Impact Ejecta From Albion Island, Belize

    Science.gov (United States)

    Ocampo, A.; Pope, K.; Fischer, A.; Alvarez, W.; Fouke, B.; Webster, C.; Vega, F.; Smit, J.; Fritsche, A.; Claeys, P.

    1999-01-01

    Impact ejecta from the Albion Formation are exposed in northern Belize. The ejecta come from the outer portion of the continuous ejecta blanket of the Chicxulub crater, which is located 360 km to the northwest.

  12. Ejecta emplacement: from distal to proximal

    Science.gov (United States)

    Artemieva, N.

    2008-09-01

    Introduction Most part of impact ejecta is deposited ballistically at some distance from a crater, defined by ejection velocity V and ejection angle α: d=v2sinα/g. In case of giant impacts, planetary curvature should be taken into account [1]. Combined with ejecta scaling [2], these relations allow to define ejecta thickness as a function of distance. Ejecta from large craters are deposited at velocity high enough to mobilize substrate material and to thicken ejecta deposits [3]. Ballistic approximation is valid for airless bodies (if impact vaporization is not vast) or for proximal ejecta of large impact craters, where ejecta mass per unit area is substantially greater than the mass of involved vapor/atmosphere (M-ratio). Deposition of distal ejecta, in which ejecta mass is negligible compared to the atmosphere, may be also treated in a simplified manner, i.e. as 1) passive motion of ejected particles within an impact plume and 2) later, as sedimentation of particles in undisturbed atmosphere (equilibrium between gravity and drag). In all intermediate M-ratio values, impact ejecta move like a surge, i.e. dilute suspension current in which particles are carried in turbulent flows under the influence of gravity. Surges are well-known for near-surface explosive tests, described in detail for volcanic explosions (Plinian column collapse, phreato-magmatic eruption, lateral blast), and found in ejecta from the Chicxulub [4] and the Ries [5]. Important aspects of surge transport include its ability to deposit ejecta over a larger area than that typical of continuous ballistic ejecta and to create multiple ejecta layers. Numerical model Two-phase hydrodynamics. Surges should be modeled in the frame of two-phase hydrodynamics, i.e. interaction between solid/molten particles and atmospheric gas/impact vapor should be taken into account. There are two techniques of solving equations for dust particle motion in a gas flow. The first one describes solid/molten particles as a

  13. Venusian extended ejecta deposits as time-stratigraphic markers

    Science.gov (United States)

    Izenberg, Noam R.

    1992-12-01

    Use of impact crater ejects at time-stratigraphic markers was established during lunar geologic mapping efforts. The basic premise is that the deposition of impact ejecta, either by itself or mixed with impact-excavated material, is superimposed on a surface. The deposit becomes an observable, mappable unit produced in a single instant in geologic time. Up to two-thirds of Venus craters exhibit extended ejecta deposits. A reconnaissance survey of 336 craters (about 40 percent of the total population) was conducted. About half the craters examined were located in and around the Beta-Atla-Themis region, and half were spread over the western hemisphere of the planet. The survey was conducted using primarily C1-MIDR images. The preliminary survey shows: (1) of the 336 craters, 223 were found to have extended ejecta deposits. This proportion is higher than that found in other Venus crater databases by up to a factor of 2. (2) 53 percent of all extended ejecta craters were unambiguously superimposed on all volcanic and tectonic units. Crater Annia Faustina's associated parabolic ejecta deposit is clearly superimposed on volcanic flows coming from Gula Mons to the west. Parabola material from Faustina has covered the lava flows, smoothing the surface and reducing its specific backscatter cross section. The stratigraphy implies that the parabola material is the youngest observable unit in the region. (3) 12 percent of extended ejecta deposits are superimposed by volcanic materials. Crater Hwangcini has extended ejecta that has been covered by volcanic flows from a dome field to the northwest, implying that the volcanic units were emplaced subsequent to the ejecta deposit and are the youngest units in the locality. (4) It is difficult to determine the stratigraphic relationships of the remaining extended ejecta deposits in SAR at C1-MIDR resolution. Examination of higher resolution images and application of the other Magellan datasets in systematic manner should resolve

  14. Ejecta evolution during cone impact

    KAUST Repository

    Marston, Jeremy

    2014-07-07

    We present findings from an experimental investigation into the impact of solid cone-shaped bodies onto liquid pools. Using a variety of cone angles and liquid physical properties, we show that the ejecta formed during the impact exhibits self-similarity for all impact speeds for very low surface tension liquids, whilst for high-surface tension liquids similarity is only achieved at high impact speeds. We find that the ejecta tip can detach from the cone and that this phenomenon can be attributed to the air entrainment phenomenon. We analyse of a range of cone angles, including some ogive cones, and impact speeds in terms of the spatiotemporal evolution of the ejecta tip. Using superhydrophobic cones, we also examine the entry of cones which entrain an air layer.

  15. Ejecta evolution during cone impact

    Science.gov (United States)

    Marston, Jeremy; Vakarelski, Ivan; Thoroddsen, Sigurdur

    2013-11-01

    We present results from an experimental study of the impact of conical shaped bodies into a pool of liquid. By varying the cone angle, impact speed and liquid physical properties, we examine a broad parameter space and seek to find conditions when self-similarity can be observed during this phenomena. We use high-speed imaging to capture the early-time motion of the liquid ejecta which emanates from the tip of the cone and travels up along the cone surface. Surprisingly, we find that the detachment of the ejecta can be simply described by air entrainment relationships derived from coating experiments.

  16. Physics of the Inner Ejecta

    Science.gov (United States)

    Hamann, Fred

    Eta Carinae's inner ejecta are dominated observationally by the bright Weigelt blobs and their famously rich spectra of nebular emission and absorption lines. They are dense (n e ˜ 107-108 cm- 3), warm (T e ˜ 6,000-7,000 K) and slow moving ( ˜ 40 km s- 1) condensations of mostly neutral (H0) gas. Located within 1,000 AU of the central star, they contain heavily CNO-processed material that was ejected from the star about a century ago. Outside the blobs, the inner ejecta include absorption-line clouds with similar conditions, plus emission-line gas that has generally lower densities and a wider range of speeds (reaching a few hundred km s- 1) compared to the blobs. The blobs appear to contain a negligible amount of dust and have a nearly dust-free view of the central source, but our view across the inner ejecta is severely affected by uncertain amounts of dust having a patchy distribution in the foreground. Emission lines from the inner ejecta are powered by photoionization and fluorescent processes. The variable nature of this emission, occurring in a 5.54years "event" cycle, requires specific changes to the incident flux that hold important clues to the nature of the central object.

  17. The flow structure of pyroclastic density currents: evidence from particle models and large-scale experiments

    Science.gov (United States)

    Dellino, Pierfrancesco; Büttner, Ralf; Dioguardi, Fabio; Doronzo, Domenico Maria; La Volpe, Luigi; Mele, Daniela; Sonder, Ingo; Sulpizio, Roberto; Zimanowski, Bernd

    2010-05-01

    Pyroclastic flows are ground hugging, hot, gas-particle flows. They represent the most hazardous events of explosive volcanism, one striking example being the famous historical eruption of Pompeii (AD 79) at Vesuvius. Much of our knowledge on the mechanics of pyroclastic flows comes from theoretical models and numerical simulations. Valuable data are also stored in the geological record of past eruptions, i.e. the particles contained in pyroclastic deposits, but they are rarely used for quantifying the destructive potential of pyroclastic flows. In this paper, by means of experiments, we validate a model that is based on data from pyroclastic deposits. It allows the reconstruction of the current's fluid-dynamic behaviour. We show that our model results in likely values of dynamic pressure and particle volumetric concentration, and allows quantifying the hazard potential of pyroclastic flows.

  18. Erosion of ejecta at Meteor Crater, Arizona

    Science.gov (United States)

    Grant, John A.; Schultz, Peter H.

    1993-01-01

    New methods for estimating erosion at Meteor Crater, Arizona, indicate that continuous ejecta deposits beyond 1/4-1/2 crater radii from the rim have been lowered less than 1 m on the average. This conclusion is based on the results of two approaches: coarsening of unweathered ejecta into surface lag deposits and calculation of the sediment budget within a drainage basin on the ejecta. Preserved ejecta morphologies beneath thin alluvium revealed by ground-penetrating radar provide qualitative support for the derived estimates. Although slightly greater erosion of less resistant ejecta locally has occurred, such deposits were limited in extent, particularly beyond 0.25R-0.5R from the present rim. Subtle but preserved primary ejecta features further support our estimate of minimal erosion of ejecta since the crater formed about 50,000 years ago. Unconsolidated deposits formed during other sudden extreme events exhibit similarly low erosion over the same time frame; the common factor is the presence of large fragments or large fragments in a matrix of finer debris. At Meteor Crater, fluvial and eolian processes remove surrounding fines leaving behind a surface lag of coarse-grained ejecta fragments that armor surfaces and slow vertical lowering.

  19. Distal ejecta - an efficient tool to study ancient impacts?

    Science.gov (United States)

    Artemieva, N.

    2011-12-01

    Ejecta from impact craters received a scientific attention not too many years ago, after the revolutionary discovery of the global K-Pg layer and its Ir-anomaly. Impact ejecta are subjected to quick erosion and, hence, are not widely presented on Earth. However, globally distributed ejecta from the largest terrestial craters may be locally preserved even if the crater itself is totally obliterated. The oldest craters on Earth, Vredefort and Sudbury, are ~1.5 Gyr younger than then oldest Archean spherule layers [1-2]. These ejecta layers potentially allow to extract an important information regarding a projectile type/size, the Earth's crust and ocean. Recent numerical modeling of the K-Pg layer [3] successfully reproduced ejecta distribution around the globe including chemical composition, shock metamorphic features, and pressure-temperature history of deposited materials. It has been shown that the main components of global ejecta are projectile and sediments (the uppermost layer of the target), while materials from the crystalline basement represent the minor component and have been transported non-ballistically by atmospheric flows. These results could serve as a benchmark for the modeling of ancient impacts. As the Archean layers are much thicker and the spherules are larger, we can speculate about much larger and more frequent impacts. A few questions should be addressed via numerical modeling: 1) are these ejecta layers proximal layers of relatively small impacts or distal layers of giant impacts; 2) is there any correlation between layers at different locations;.3) why there are no any shocked minerals within these layers; 3) why the composition of spherules is mainly basaltic? In this paper the modeling results are compared with available observations (mainly on K-Pg boundary) and then are extrapolated to much larger impacts. [1] Lowe D.R., Byerly G. R., Asaro F., Kyte F. T. (1989) Science 245:959-962. [2] Simonson, B. M. and B. P. Glass (2004) Annual

  20. Insights into complex layered ejecta emplacement and subsurface stratigraphy in Chryse Planitia, Mars, through an analysis of THEMIS brightness temperature data

    Science.gov (United States)

    Jones, Eriita; Caprarelli, Graziella; Osinski, Gordon R.

    2016-06-01

    Layered ejecta craters on Mars have been interpreted to indicate the presence of volatiles in the substrate, making them important targets for the investigation of sites of astrobiological significance. If the ejecta are associated with the presence of water in the substratum, specific surface grain size trends are expected. In this study we explore the distribution of grain sizes in the layered ejecta of impact craters located in Chryse Planitia, using Thermal Emission Imaging System (THEMIS) thermal infrared data. Ejecta grain size trends, in conjunction with ejecta mobility and lobateness values, are applied to assess the degree of surface flow of the ejecta, and in turn to constrain the plausible volatile abundance, cohesion, and fine particle content of the target materials. Craters with a larger fraction of small grain sizes in their ejecta showed greater ejecta mobility and lobateness, consistent with a water-rich and/or a low-cohesion target. Craters displaying decreasing grain size with increasing radius had smaller diameters and lower ejecta mobility and lobateness, indicating only a minimal component of surface ejecta flow. Ejecta grain size trends varied with crater diameter, from which the presence of vertical compositional stratigraphy in Chryse Planitia is inferred and interpreted. Our observations are synthesized into a number of plausible geologic scenarios for Chryse Planitia.

  1. High-resolution studies of double-layered ejecta craters: Morphology, inherent structure, and a phenomenological formation model

    Science.gov (United States)

    Wulf, Gerwin; Kenkmann, Thomas

    2015-02-01

    The ejecta blankets of impact craters in volatile-rich environments often possess characteristic layered ejecta morphologies. The so-called double-layered ejecta (DLE) craters are characterized by two ejecta layers with distinct morphologies. The analysis of high-resolution image data, especially HiRISE and CTX, provides new insights into the formation of DLE craters. A new phenomenological excavation and ejecta emplacement model for DLE craters is proposed based on a detailed case study of the Martian crater Steinheim—a well-preserved DLE crater—and studies of other DLE craters. The observations show that the outer ejecta layer is emplaced as medial and distal ejecta that propagate outwards in a debris avalanche or (if saturated with water) a debris flow mode after landing, overrunning previously formed secondary craters. In contrast, the inner ejecta layer is formed by a translational slide of the proximal ejecta deposits during the emplacement stage that overrun and superimpose parts of the outer ejecta layer. Based on our model, DLE craters on Mars are the result of an impact event into a rock/ice mixture that produces large amounts of shock-induced vaporization and melting of ground ice, leading to high ejection angles, proximal landing positions, and an ejecta curtain with relatively wet (in terms of water in liquid form) composition in the distal part versus dryer composition in the proximal part. As a consequence, basal melting of ice components in the ejecta at the transient crater rim, which is induced by frictional heating and the enhanced pressure at depth, initiates an outwards directed collapse of crater rim material in a translational slide mode. Our results indicate that similar processes may also be applicable for other planetary bodies with volatile-rich environments, such as Ganymede, Europa, and the Earth.

  2. A possible formation mechanism of rampart-like ejecta pattern in a laboratory

    Science.gov (United States)

    Suzuki, A.; Kadono, T.; Nakamura, A. M.; Arakawa, M.; Wada, K.; Yamamoto, S.

    2011-12-01

    /s. Eventually, we have succeeded to capture the formation of the rampart-like ridges with high-speed video camera. Our experiments clarify that the rampart-like ridges are formed by the thin, radial ejecta flow that originates around the crater rim, other than the sedimentation of ejecta decelerated by the ambient atmosphere. A wake of the projectile going through the atmosphere might be responsible for the crater rim collapsed, which results in initiating the radial ejecta flow. Additionally, it is found that erodible surface (i.e. a particle layer in this case) is essential to produce the rampart-like ridges.

  3. Preflow stresses in Martian rampart ejecta blankets - A means of estimating the water content

    Science.gov (United States)

    Woronow, A.

    1981-01-01

    Measurements of extents of rampart ejecta deposits as a function of the size of the parent craters support models which, for craters larger than about 6 km diameter, constrain ejecta blankets to all have a similar maximum thickness regardless of the crater size. These volatile-rich ejecta blankets may have failed under their own weights, then flowed radially outward. Assuming this to be so, some of the physicomechanical properties of the ejecta deposits at the time of their emplacement can then be determined. Finite-element studies of the stress magnitudes, distributions, and directions in hypothetical Martian rampart ejecta blankets reveal that the material most likely failed when the shear stresses were less than 500 kPa and the angle of internal friction was between 26 and 36 deg. These figures imply that the ejecta has a water content between 16 and 72%. Whether the upper limit or the lower limit is more appropriate depends on the mode of failure which one presumes: namely, viscous flow of plastic deformation.

  4. Phase Doppler anemometry as an ejecta diagnostic

    Science.gov (United States)

    Bell, D. J.; Chapman, D. J.

    2017-01-01

    When a shock wave is incident on a free surface, micron sized pieces of the material can be ejected from that surface. Phase Doppler Anemometry (PDA) is being developed to simultaneously measure the sizes and velocities of the individual shock induced ejecta particles; providing an important insight into ejecta phenomena. The results from experiments performed on the 13 mm bore light gas gun at the Institute of Shock Physics, Imperial College London are presented. Specially grooved tin targets were shocked at pressures of up to 14 GPa, below the melt on release pressure, to generate ejecta particles. These experiments are the first time that PDA has been successfully fielded on dynamic ejecta experiments. The results and current state of the art of the technique are discussed along with the future improvements required to optimise performance and increase usability.

  5. Chicxulub Ejecta Blanket Deposits From Belize

    Science.gov (United States)

    Ocampo, A.

    1995-01-01

    The Chicxulub impact into a thick sequence of carbonates and sulfates released over a trillion tons of volatiles. The importance of the explosive release of such a large mass of volatiles has been greatly underestimated in studies of ejecta depositional processes. Proximal Chicxulub ejecta blanket deposits recent discovered on Albion Island in Belize provide a key to understanding the role of volatile-rich target material during large impact events.

  6. Simulating regolith ejecta due to gas impingement

    Science.gov (United States)

    Chambers, Wesley Allen; Metzger, Philip; Dove, Adrienne; Britt, Daniel

    2016-10-01

    Space missions operating at or near the surface of a planet or small body must consider possible gas-regolith interactions, as they can cause hazardous effects or, conversely, be employed to accomplish mission goals. They are also directly related to a body's surface properties; thus understanding these interactions could provide an additional tool to analyze mission data. The Python Regolith Interaction Calculator (PyRIC), built upon a computational technique developed in the Apollo era, was used to assess interactions between rocket exhaust and an asteroid's surface. It focused specifically on threshold conditions for causing regolith ejecta. To improve this model, and learn more about the underlying physics, we have begun ground-based experiments studying the interaction between gas impingement and regolith simulant. Compressed air, initially standing in for rocket exhaust, is directed through a rocket nozzle at a bed of simulant. We assess the qualitative behavior of various simulants when subjected to a known maximum surface pressure, both in atmosphere and in a chamber initially at vacuum. These behaviors are compared to prior computational results, and possible flow patterns are inferred. Our future work will continue these experiments in microgravity through the use of a drop tower. These will use several simulant types and various pressure levels to observe the effects gas flow can have on target surfaces. Combining this with a characterization of the surface pressure distribution, tighter bounds can be set on the cohesive threshold necessary to maintain regolith integrity. This will aid the characterization of actual regolith distributions, as well as informing the surface operation phase of mission design.

  7. Mercurian impact ejecta: Meterorites and mantle

    CERN Document Server

    Gladman, B

    2008-01-01

    We have examined the fate of impact ejecta liberated from the surface of Mercury due to impacts by comets or asteroids, in order to study (1) meteorite transfer to Earth, and (2) re-accumulation of an expelled mantle in giant-impact scenarios seeking to explain Mercury's large core. In the context of meteorite transfer, we note that Mercury's impact ejecta leave the planet's surface much faster (on average) than other planet's in the Solar System because it is the only planet where impact speeds routinely range from 5-20 times the planet's escape speed. Thus, a large fraction of mercurian ejecta may reach heliocentric orbit with speeds sufficiently high for Earth-crossing orbits to exist immediately after impact, resulting in larger fractions of the ejecta reaching Earth as meteorites. We calculate the delivery rate to Earth on a time scale of 30 Myr and show that several percent of the high-speed ejecta reach Earth (a factor of -3 less than typical launches from Mars); this is one to two orders of magnitude ...

  8. Orbital Evolution of Impact Ejecta from Ganymede

    Science.gov (United States)

    Alvarellos, Jose Luis; Zahnle, Kevin J.; Dobrovolskis, Anthony R.; Hamill, Patrick

    2002-11-01

    We have numerically computed the orbital evolution of ˜10 3 particles representing high-speed ejecta from Gilgamesh, the largest impact basin on Ganymede. The integration includes the four Galilean satellites, Jupiter (including J2 and J4), Saturn, and the Sun. The integrations last 100,000 years. The particles are ejected at a variety of speeds and directions, with the fastest particles ejected at 1.4 times the escape speed vesc≡ 2GM G/R G of Ganymede. Ejecta with speeds v0.96 vesc, most particles escape Ganymede and achieve orbits about Jupiter. Eventually most (˜71%) of the jovicentric particles hit Ganymede, with 92% of these hitting within 1000 years. The accretion rate scales as 1/ t. Their impact sites are randomly distributed, as expected for planetocentric debris. We estimate that most of the resulting impact craters are a few kilometers across and smaller. The rest of the escaping ejecta are partitioned as follows: ˜3% hit Io; ˜10% hit Europa; ˜13% hit Callisto; 2% reach heliocentric space; and less than ˜1% hit Jupiter. Only two particles survived the entire 10 5-year integration. Ejecta from large impact events do not appear to be a plausible source of large craters on the Galilean satellites; however, such ejecta may account for the majority of small craters.

  9. In plain sight: the Chesapeake Bay crater ejecta blanket

    Directory of Open Access Journals (Sweden)

    D. L. Griscom

    2012-02-01

    Full Text Available The discovery nearly two decades ago of a 90 km-diameter impact crater below the lower Chesapeake Bay has gone unnoted by the general public because to date all published literature on the subject has described it as "buried". To the contrary, evidence is presented here that the so-called "upland deposits" that blanket ∼5000 km2 of the U.S. Middle-Atlantic Coastal Plain (M-ACP display morphologic, lithologic, and stratigraphic features consistent with their being ejecta from the 35.4 Ma Chesapeake Bay Impact Structure (CBIS and absolutely inconsistent with the prevailing belief that they are of fluvial origin. Specifically supporting impact origin are the facts that (i a 95 %-pure iron ore endemic to the upland deposits of southern Maryland, eastern Virginia, and the District of Columbia has previously been proven to be impactoclastic in origin, (ii this iron ore welds together a small percentage of well-rounded quartzite pebbles and cobbles of the upland deposits into brittle sheets interpretable as "spall plates" created in the interference-zone of the CBIS impact, (iii the predominantly non-welded upland gravels have long ago been shown to be size sorted with an extreme crater-centric gradient far too large to have been the work of rivers, but well explained as atmospheric size-sorted interference-zone ejecta, (iv new evidence is provided here that ~60 % of the non-welded quartzite pebbles and cobbles of the (lower lying gravel member of the upland deposits display planar fractures attributable to interference-zone tensile waves, (v the (overlying loam member of the upland deposits is attributable to base-surge-type deposition, (vi several exotic clasts found in a debris flow topographically below the upland deposits can only be explained as jetting-phase crater ejecta, and (vii an allogenic granite boulder found among the upland deposits is deduced to have been launched into space and sculpted by hypervelocity air friction

  10. Eta Carinae -- Physics of the Inner Ejecta

    CERN Document Server

    Hamann, Fred

    2012-01-01

    Eta Carinae's inner ejecta are dominated observationally by the bright Weigelt blobs and their famously rich spectra of nebular emission and absorption lines. They are dense (n_e ~ 10^7 to 10^8 cm^-3), warm (T_e ~ 6000 to 7000 K) and slow moving (~40 km/s) condensations of mostly neutral (H^0) gas. Located within 1000 AU of the central star, they contain heavily CNO-processed material that was ejected from the star about a century ago. Outside the blobs, the inner ejecta include absorption-line clouds with similar conditions, plus emission-line gas that has generally lower densities and a wider range of speeds (reaching a few hundred km/s) compared to the blobs. The blobs appear to contain a negligible amount of dust and have a nearly dust-free view of the central source, but our view across the inner ejecta is severely affected by uncertain amounts of dust having a patchy distribution in the foreground. Emission lines from the inner ejecta are powered by photoionization and fluorescent processes. The variabl...

  11. Dust Formation and Survival in Supernova Ejecta

    CERN Document Server

    Bianchi, S

    2007-01-01

    The presence of dust at high redshift requires efficient condensation of grains in SN ejecta, in accordance with current theoretical models. Yet, observations of the few well studied SNe and SN remnants imply condensation efficiencies which are about two orders of magnitude smaller. Motivated by this tension, we have (i) revisited the model of Todini & Ferrara (2001) for dust formation in the ejecta of core collapse SNe and (ii) followed, for the first time, the evolution of newly condensed grains from the time of formation to their survival - through the passage of the reverse shock - in the SN remnant. We find that 0.1 - 0.6 M_sun of dust form in the ejecta of 12 - 40 M_sun stellar progenitors. Depending on the density of the surrounding ISM, between 2-20% of the initial dust mass survives the passage of the reverse shock, on time-scales of about 4-8 x 10^4 yr from the stellar explosion. Sputtering by the hot gas induces a shift of the dust size distribution towards smaller grains. The resulting dust ex...

  12. Distal ejecta from lunar impacts: Extensive regions of rocky deposits

    Science.gov (United States)

    Bandfield, Joshua L.; Cahill, Joshua T. S.; Carter, Lynn M.; Neish, Catherine D.; Patterson, G. Wesley; Williams, Jean-Pierre; Paige, David A.

    2017-02-01

    Lunar Reconnaissance Orbiter (LRO) Diviner Radiometer, Mini-RF, and LRO Camera data were used to identify and characterize rocky lunar deposits that appear well separated from any potential source crater. Two regions are described: 1) A ∼18,000 km2 area with elevated rock abundance and extensive melt ponds and veneers near the antipode of Tycho crater (167.5°E, 42.5°N). This region has been identified previously, using radar and imaging data. 2) A much larger and more diffuse region, covering ∼730,000 km2, centered near 310°E, 35°S, containing elevated rock abundance and numerous granular flow deposits on crater walls. The rock distributions in both regions favor certain slope azimuths over others, indicating a directional component to the formation of these deposits. The spatial distribution of rocks is consistent with the arrival of ejecta from the west and northwest at low angles (∼10-30°) above the horizon in both regions. The derived age and slope orientations of the deposits indicate that the deposits likely originated as ejecta from the Tycho impact event. Despite their similar origin, the deposits in the two regions show significant differences in the datasets. The Tycho crater antipode deposit covers a smaller area, but the deposits are pervasive and appear to be dominated by impact melts. By contrast, the nearside deposits cover a much larger area and numerous granular flows were triggered. However, the features in this region are less prominent with no evidence for the presence of impact melts. The two regions appear to be surface expressions of a distant impact event that can modify surfaces across wide regions, resulting in a variety of surface morphologies. The Tycho impact event may only be the most recent manifestation of these processes, which likely have played a role in the development of the regolith throughout lunar history.

  13. Evolutionary signatures in complex ejecta and their driven shocks

    Science.gov (United States)

    Farrugia, C.; Berdichevsky, D.

    2004-10-01

    We examine interplanetary signatures of ejecta-ejecta interactions. To this end, two time intervals of inner-heliospheric (≤1AU) observations separated by 2 solar cycles are chosen where ejecta/magnetic clouds are in the process of interacting to form complex ejecta. At the Sun, both intervals are characterized by many coronal mass ejections (CMEs) and flares. In each case, a complement of observations from various instruments on two spacecraft are examined in order to bring out the in-situ signatures of ejecta-ejecta interactions and their relation to solar observations. In the first interval (April 1979), data are shown from Helios-2 and ISEE-3, separated by ~0.33AU in radial distance and 28° in heliographic longitude. In the second interval (March-April 2001), data from the SOHO and Wind probes are combined, relating effects at the Sun and their manifestations at 1AU on one of Wind's distant prograde orbits. At ~0.67AU, Helios-2 observes two individual ejecta which have merged by the time they are observed at 1AU by ISEE-3. In March 2001, two distinct Halo CMEs (H-CMEs) are observed on SOHO on 28-29 March approaching each other with a relative speed of 500kms-1 within 30 solar radii. In order to isolate signatures of ejecta-ejecta interactions, the two event intervals are compared with expectations for pristine (isolated) ejecta near the last solar minimum, extensive observations on which were given by Berdichevsky et al. (2002). The observations from these two event sequences are then intercompared. In both event sequences, coalescence/merging was accompanied by the following signatures: heating of the plasma, acceleration of the leading ejecta and deceleration of the trailing ejecta, compressed field and plasma in the leading ejecta, disappearance of shocks and the strengthening of shocks driven by the accelerated ejecta. A search for reconnection signatures at the interface between the two ejecta in the March 2001 event was inconclusive because the

  14. A class of ejecta transport test problems

    Energy Technology Data Exchange (ETDEWEB)

    Hammerberg, James E [Los Alamos National Laboratory; Buttler, William T [Los Alamos National Laboratory; Oro, David M [Los Alamos National Laboratory; Rousculp, Christopher L [Los Alamos National Laboratory; Morris, Christopher [Los Alamos National Laboratory; Mariam, Fesseha G [Los Alamos National Laboratory

    2011-01-31

    Hydro code implementations of ejecta dynamics at shocked interfaces presume a source distribution function ofparticulate masses and velocities, f{sub 0}(m, v;t). Some of the properties of this source distribution function have been determined from extensive Taylor and supported wave experiments on shock loaded Sn interfaces of varying surface and subsurface morphology. Such experiments measure the mass moment of f{sub o} under vacuum conditions assuming weak particle-particle interaction and, usually, fully inelastic capture by piezo-electric diagnostic probes. Recently, planar Sn experiments in He, Ar, and Kr gas atmospheres have been carried out to provide transport data both for machined surfaces and for coated surfaces. A hydro code model of ejecta transport usually specifies a criterion for the instantaneous temporal appearance of ejecta with source distribution f{sub 0}(m, v;t{sub 0}). Under the further assumption of separability, f{sub 0}(m,v;t{sub 0}) = f{sub 1}(m)f{sub 2}(v), the motion of particles under the influence of gas dynamic forces is calculated. For the situation of non-interacting particulates, interacting with a gas via drag forces, with the assumption of separability and simplified approximations to the Reynolds number dependence of the drag coefficient, the dynamical equation for the time evolution of the distribution function, f(r,v,m;t), can be resolved as a one-dimensional integral which can be compared to a direct hydro simulation as a test problem. Such solutions can also be used for preliminary analysis of experimental data. We report solutions for several shape dependent drag coefficients and analyze the results of recent planar dsh experiments in Ar and Xe.

  15. Chicxulub High-Altitude Ballistic Ejecta from Central Belize

    Science.gov (United States)

    Pope, K. O.; Ocampo, A. C.

    2000-01-01

    Chicxulub ejecta are found in central Belize, 475 km southeast of the impact crater center. These deposits are ballistic ejecta launched along high-altitude trajectories above the atmosphere and deposited as a discontinuous sheet on the terminal Cretaceous land surface.

  16. The Crater Ejecta Distribution on Ceres

    Science.gov (United States)

    Schmedemann, Nico; Neesemann, Adrian; Schulzeck, Franziska; Krohn, Katrin; Gathen, Isabel; Otto, Katharina; Jaumann, Ralf; Michael, Gregory; Raymond, Carol; Russell, Christopher

    2017-04-01

    Since March 6 2015 the Dawn spacecraft [1] has been in orbit around the dwarf planet Ceres. At small crater diameters Ceres appears to be peppered with secondary craters that often align in chains or form clusters. Some of such possible crater chains follow curved geometries and are not in a radial orientation with respect to possible source craters [2]. Ceres is a fast rotating body ( 9 h per revolution) with comparatively low surface gravity ( 0.27 m/s2). A substantial fraction of impact ejecta may be launched with velocities similar to Ceres' escape velocity (510 m/s), which implies that many ejected particles follow high and long trajectories. Thus, due to Ceres' fast rotation the distribution pattern of the reimpacting ejected material is heavily affected by Coriolis forces that results in a highly asymmetrical and curved pattern of secondary crater chains. In order to simulate flight trajectories and distribution of impact ejected material for individual craters on Ceres we used the scaling laws by [3] adjusted to the Cerean impact conditions [4] and the impact ejecta model by [5]. These models provide the starting conditions for tracer particles in the simulation. The trajectories of the particles are computed as n-body simulation. The simulation calculates the positions and impact velocities of each impacting tracer particle with respect to the rotating surface of Ceres, which is approximated by a two-axis ellipsoid. Initial results show a number of interesting features in the simulated deposition geometries of specific crater ejecta. These features are roughly in agreement with features that can be observed in Dawn imaging data of the Cerean surface. For example: ray systems of fresh impact craters, non-radial crater chains and global scale border lines of higher and lower color ratio areas. Acknowledgment: This work has been supported by the German Space Agency (DLR) on behalf of the Federal Ministry for Economic Affairs and Energy, Germany, grants 50 OW

  17. Sanidine holocrystalline ejecta from central Sabatini Volcanic District, Latium (Italy). II. Intergranular ejecta and minerogenetic deductions

    Energy Technology Data Exchange (ETDEWEB)

    Capitanio, F.; Mottana, A.

    1998-12-31

    The Sanidine holocrystalline ejecta with intergranular texture from the central Sabatini Volcanic District contain high-T feldspars, out-of-equilibrium K- and Na- Ca-feldspar, and two pyroxene generations formed at different depths, as well as many mineral phases which indicate high f (H{sub 2}O) and/or f(O{sub 2}). A simple evolution model by fractional crystallization, in a plutonic or hypoabissal domain, has been derived from the mineralogical assemblages present in both the isotropic and intergranular type of ejecta. The intergranular type, the crystallization of which began at deeper levels than the isotropic one, underwent multiple pyroxene-liquidus re-equilibration during a quick magma ascent to shallower levels.

  18. Evolution of fluid-like granular ejecta generated by sphere impact

    KAUST Repository

    Marston, Jeremy

    2012-05-01

    We present results from an experimental study of the speed and shape of the ejecta formed when a solid sphere impacts onto a granular bed. We use high-speed imaging at frame rates up to 100 000 f.p.s. to provide direct measurement of individual grain velocities and ejecta angles as well as the overall evolution of the granular ejecta. For larger grain sizes, the emergence velocities of the grains during the early stage flow, i.e. before the main ejecta curtain forms, increase with the kinetic energy of the impacting sphere but are inversely proportional to the time from impact. We also observe that the fastest grains, which can obtain velocities up to five times that of the impacting sphere (V g/V 0 = 5), generally emerge at the earliest times and with the lowest ejection angles. As the grain size is decreased, a more fluid-like behaviour is observed whereby the ejected material first emerges as a thin sheet of grains between the sphere and the bed surface, which is also seen when a sphere impacts a liquid pool. In this case, the sheet velocity is approximately double that of the impacting sphere (V s/V 0 = 2) and independent of the bulk packing fraction. For the finest grains we provide evidence of the existence of a vortex ring inside the ejecta curtain where grains following the air flow are entrained through the curtain. In contrast to predictions from previous studies, we find that the temporal evolution of the ejecta neck radius is not initially quadratic but rather approaches a square-root dependence on time, for the finest grains with the highest impact kinetic energy. The evolution therefore approaches that seen for the crown evolution in liquid drop impacts. By using both spherical glass beads and coarse sands, we show that the size and shape distribution are critical in determining the post-impact dynamics whereby the sands exhibit a qualitatively different response to impact, with grains ejected at lower speeds and at later times than for the glass

  19. Accretion by a Neutron Star Moving at a High Kick Velocity in the Supernova Ejecta

    Institute of Scientific and Technical Information of China (English)

    Xu Zhang; Ye Lu; Yong-Heng Zhao

    2007-01-01

    We suggest a two-dimensional time dependent analytic model to describe the accretion of matter onto a neutron star moving at a high speed across the ejecta left in the aftermath of a supernova explosion. The formation of a strange star resulting from the accretion is also addressed. The newborn neutron star is assumed to move outward at a kick velocity of vns ~ 103 km s-1, and the accretion flow is treated as a dust flow. When the neutron star travels across the ejecta with high speed, it sweeps up material, and when the accreted mass has reached a critical value, the neutron star will undergo a phase transition,for instance, to become a strange star. Our results show that the accretion rate decreases in a complicated way in time, not just a power law dependence: it drops much faster than the power law derived by Colpi et al. We also found that the total accreted mass and the phase transition of the neutron star depend sensitively on the velocity of supernova ejecta.

  20. Chicxulub ejecta plume: Influence of sedimentary target rock, volatiles and atmosphere

    Science.gov (United States)

    Salge, T.

    Terrestrial impact structures provide evidence for cratering processes on planetary bodies with an atmosphere and volatiles in the target rocks. The target of the Chicxulub impact structure (˜180 km Ø) was composed of (1) a ˜3 km thick sedimentary and, thus, extremely volatile-rich target sequence, and (2) a crystalline silicate basement. The suevites of El Guayal ˜520 km SW from the crater centre and UNAM-7 near the crater rim recorded the distinct behaviour of sedimentary target rock, water and atmospheric interactions during ejecta emplacement. El Guayal: A ˜10 m thick suevite sequence contains shocked minerals, altered (to clay minerals) silicate melt and spherulitic carbonate melt particles. Fusion of silicate melt with carbonate induced calcite recrystallisation at >750°C. Release of CO2 is indicated by voids in silicate melt at the contact with calcite. Accretionary lapilli 350°C by slaking and from silicate melt particles. Conclusions: The following sequence of processes is proposed: (1) Vapour release changed ejecta distribution from ballistic to flow-like transport. (2) Ejecta plume collapse separated suevite from impactor material that had been lifted into the stratosphere. (3) Fusion of the different target components initiated a hot gas-driven lateral transport in a basal flow. (4) Accretionary lapilli formed in a coherent turbulent ash cloud. Acknowledgements: TS kindly thanks P. Claeys for providing samples, R. Tagle for PGE analyses and H. Stosnach for introduction to TXRF analyses.

  1. Evolutionary signatures in complex ejecta and their driven shocks

    Directory of Open Access Journals (Sweden)

    C. J. Farrugia

    2004-11-01

    Full Text Available We examine interplanetary signatures of ejecta-ejecta interactions. To this end, two time intervals of inner-heliospheric (≤1AU observations separated by 2 solar cycles are chosen where ejecta/magnetic clouds are in the process of interacting to form complex ejecta. At the Sun, both intervals are characterized by many coronal mass ejections (CMEs and flares. In each case, a complement of observations from various instruments on two spacecraft are examined in order to bring out the in-situ signatures of ejecta-ejecta interactions and their relation to solar observations. In the first interval (April 1979, data are shown from Helios-2 and ISEE-3, separated by ~0.33AU in radial distance and 28° in heliographic longitude. In the second interval (March-April 2001, data from the SOHO and Wind probes are combined, relating effects at the Sun and their manifestations at 1AU on one of Wind's distant prograde orbits. At ~0.67AU, Helios-2 observes two individual ejecta which have merged by the time they are observed at 1AU by ISEE-3. In March 2001, two distinct Halo CMEs (H-CMEs are observed on SOHO on 28-29 March approaching each other with a relative speed of 500kms-1 within 30 solar radii. In order to isolate signatures of ejecta-ejecta interactions, the two event intervals are compared with expectations for pristine (isolated ejecta near the last solar minimum, extensive observations on which were given by Berdichevsky et al. (2002. The observations from these two event sequences are then intercompared. In both event sequences, coalescence/merging was accompanied by the following signatures: heating of the plasma, acceleration of the leading ejecta and deceleration of the trailing ejecta, compressed field and plasma in the leading ejecta, disappearance of shocks and the strengthening of shocks driven by the accelerated ejecta. A search for reconnection signatures at the interface between the two ejecta in the March 2001 event was

  2. (U) An Analytic Study of Piezoelectric Ejecta Mass Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Tregillis, Ian Lee [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-16

    We consider the piezoelectric measurement of the areal mass of an ejecta cloud, for the specific case where ejecta are created by a single shock at the free surface and fly ballistically through vacuum to the sensor. To do so, we define time- and velocity-dependent ejecta “areal mass functions” at the source and sensor in terms of typically unknown distribution functions for the ejecta particles. Next, we derive an equation governing the relationship between the areal mass function at the source (which resides in the rest frame of the free surface) and at the sensor (which resides in the laboratory frame). We also derive expressions for the analytic (“true”) accumulated ejecta mass at the sensor and the measured (“inferred”) value obtained via the standard method for analyzing piezoelectric voltage traces. This approach enables us to derive an exact expression for the error imposed upon a piezoelectric ejecta mass measurement (in a perfect system) by the assumption of instantaneous creation. We verify that when the ejecta are created instantaneously (i.e., when the time dependence is a delta function), the piezoelectric inference method exactly reproduces the correct result. When creation is not instantaneous, the standard piezo analysis will always overestimate the true mass. However, the error is generally quite small (less than several percent) for most reasonable velocity and time dependences. In some cases, errors exceeding 10-15% may require velocity distributions or ejecta production timescales inconsistent with experimental observations. These results are demonstrated rigorously with numerous analytic test problems.

  3. Fates of satellite ejecta in the Saturn system, II

    Science.gov (United States)

    Alvarellos, José Luis; Dobrovolskis, Anthony R.; Zahnle, Kevin J.; Hamill, Patrick; Dones, Luke; Robbins, Stuart

    2017-03-01

    We assess the fates of ejecta from the large craters Aeneas on Dione and Ali Baba on Enceladus (161 and 39 km in diameter, respectively), as well as that from Herschel (130 km in diameter) on Mimas. The ejecta are treated either as 'spalls' launched from hard surfaces, or as 'rubble' launched from a weak rubble pile regolith. Once in orbit we consider the ejecta as massless test particles subject to the gravity of Saturn and its classical satellites. The great majority of escaped ejecta get swept up by the source moons. The best fit to the ejecta population decay is a stretched exponential with exponent near 1/2 (Dobrovolskis et al., Icarus 188, 481-505, 2007). We bracket the characteristic ejecta sizes corresponding to Grady-Kipp fragments and spalls. Based on this and computed impact velocities and incidence angles, the resulting sesquinary craters, if they exist, should have diameters on the order of a few meters to a few km. The observed longitude distribution of small craters on Mimas along with the findings of Bierhaus et al. that small moons should not have a secondary crater population (Icarus 218, 602-621, 2012) suggest that the most likely place to find sesquinary craters in the Saturn system is the antapex of Mimas.

  4. Searching for Biosignatures in Exoplanetary Impact Ejecta

    Science.gov (United States)

    Cataldi, Gianni; Brandeker, Alexis; Thébault, Philippe; Singer, Kelsi; Ahmed, Engy; de Vries, Bernard L.; Neubeck, Anna; Olofsson, Göran

    2017-08-01

    With the number of confirmed rocky exoplanets increasing steadily, their characterization and the search for exoplanetary biospheres are becoming increasingly urgent issues in astrobiology. To date, most efforts have concentrated on the study of exoplanetary atmospheres. Instead, we aim to investigate the possibility of characterizing an exoplanet (in terms of habitability, geology, presence of life, etc.) by studying material ejected from the surface during an impact event. For a number of impact scenarios, we estimate the escaping mass and assess its subsequent collisional evolution in a circumstellar orbit, assuming a Sun-like host star. We calculate the fractional luminosity of the dust as a function of time after the impact event and study its detectability with current and future instrumentation. We consider the possibility to constrain the dust composition, giving information on the geology or the presence of a biosphere. As examples, we investigate whether calcite, silica, or ejected microorganisms could be detected. For a 20 km diameter impactor, we find that the dust mass escaping the exoplanet is roughly comparable to the zodiacal dust, depending on the exoplanet's size. The collisional evolution is best modeled by considering two independent dust populations, a spalled population consisting of nonmelted ejecta evolving on timescales of millions of years, and dust recondensed from melt or vapor evolving on much shorter timescales. While the presence of dust can potentially be inferred with current telescopes, studying its composition requires advanced instrumentation not yet available. The direct detection of biological matter turns out to be extremely challenging. Despite considerable difficulties (small dust masses, noise such as exozodiacal dust, etc.), studying dusty material ejected from an exoplanetary surface might become an interesting complement to atmospheric studies in the future.

  5. Proximal Multi-layered Ejecta of the Haughton Impact Crater (Devon Island, High Arctic); Insights into Emplacement Mechanisms of Layered Ejecta

    Science.gov (United States)

    Thackrey, S.; Lee, P.; Mason, C. E.; Parnell, J.

    2008-03-01

    We report the discovery of a well preserved, proximal multi-layered ejecta deposit on the NW sector of the Haughton impact crater. The deposit provides evidence that subsurface volatiles plays a vital role in the emplacement of layered ejecta.

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

    Science.gov (United States)

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

    2013-01-01

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

  7. (U) An Analytic Examination of Piezoelectric Ejecta Mass Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Tregillis, Ian Lee [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-02

    Ongoing efforts to validate a Richtmyer-Meshkov instability (RMI) based ejecta source model [1, 2, 3] in LANL ASC codes use ejecta areal masses derived from piezoelectric sensor data [4, 5, 6]. However, the standard technique for inferring masses from sensor voltages implicitly assumes instantaneous ejecta creation [7], which is not a feature of the RMI source model. To investigate the impact of this discrepancy, we define separate “areal mass functions” (AMFs) at the source and sensor in terms of typically unknown distribution functions for the ejecta particles, and derive an analytic relationship between them. Then, for the case of single-shock ejection into vacuum, we use the AMFs to compare the analytic (or “true”) accumulated mass at the sensor with the value that would be inferred from piezoelectric voltage measurements. We confirm the inferred mass is correct when creation is instantaneous, and furthermore prove that when creation is not instantaneous, the inferred values will always overestimate the true mass. Finally, we derive an upper bound for the error imposed on a perfect system by the assumption of instantaneous ejecta creation. When applied to shots in the published literature, this bound is frequently less than several percent. Errors exceeding 15% may require velocities or timescales at odds with experimental observations.

  8. NOx production and rainout from Chicxulub impact ejecta reentry

    Science.gov (United States)

    Parkos, Devon; Alexeenko, Alina; Kulakhmetov, Marat; Johnson, Brandon C.; Melosh, H. Jay

    2015-12-01

    The Chicxulub impact 66.0 Ma ago initiated the second biggest extinction in the Phanerozoic Eon. The cause of the concurrent oceanic nitrogen isotopic anomaly, however, remains elusive. The Chicxulub impactor struck the Yucatán peninsula, ejecting 2 × 1015 kg of molten and vaporized rock that reentered globally as approximately 1023 microscopic spherules. Here we report that modern techniques indicate that this ejecta generates 1.5 × 1014 moles of NOx, which is enough to cause the observed nitrogen enrichment of the basal layer. Additionally, reentry-based NO production would explain the anomalously heavy isotopic composition of the observed nitrogen. We include N, O, N2, O2, and NO species in simulations of nonequilibrium chemically reacting flow around a reentering spherule. We then determine the net production of NO from all the spherules and use turbulence models to determine how quickly this yield diffuses through the atmosphere. Upon reaching the stratosphere and troposphere, cloud moisture absorbs the NOx and forms nitric acid. We model this process and determine the acidity of the resulting precipitation, which peaks about 1 year after the impact. The precipitation ultimately reaches the upper ocean, where we assume that the well-mixed surface layer is 100 m deep. We then model the naturally occurring carbonate/bicarbonate buffer and determine the net pH. We find that insufficient NOx reaches the ocean to directly cause the observed end-Cretaceous oceanic extinction via acidification and buffer removal. However, the resulting nitrates are sufficient to explain the concurrent nitrogen isotopic anomaly and facilitate an end-Cretaceous algae bloom.

  9. Modelling circumplanetary ejecta clouds at low altitudes: a probabilistic approach

    CERN Document Server

    Christou, Apostolos A

    2014-01-01

    A model is presented of a ballistic, collisionless, steady state population of ejecta launched at randomly distributed times and velocities and moving under constant gravity above the surface of an airless planetary body. Within a probabilistic framework, closed form solutions are derived for the probability density functions of the altitude distribution of particles, the distribution of their speeds in a rest frame both at the surface and at altitude and with respect to a moving platform such as an orbiting spacecraft. These expressions are validated against numerically-generated synthetic populations of ejecta under lunar surface gravity. The model is applied to the cases where the ejection speed distribution is (a) uniform (b) a power law. For the latter law, it is found that the effective scale height of the ejecta envelope directly depends on the exponent of the power law and increases with altitude. The same holds for the speed distribution of particles near the surface. Ejection model parameters can, t...

  10. Ejecta model development at pRad (u)

    Energy Technology Data Exchange (ETDEWEB)

    Buttler, William T [Los Alamos National Laboratory; Oro, David M [Los Alamos National Laboratory; Dimonte, Guy [Los Alamos National Laboratory; Terrones, Guillermo [Los Alamos National Laboratory; Morris, Christopher [Los Alamos National Laboratory; Bainbridge, J R [Los Alamos National Laboratory; Hogan, Gary E. [Los Alamos National Laboratory; Hollander, Brian J. [Los Alamos National Laboratory; Holtkamp, David B. [Los Alamos National Laboratory; Kwiathowski, Kris [Los Alamos National Laboratory; Marr-Lyon, Mark [Los Alamos National Laboratory; Mariam, Fesseha G. [Los Alamos National Laboratory; Merrill, Frank E [Los Alamos National Laboratory; Nedrow, Paul [Los Alamos National Laboratory; Saunders, Alexander [Los Alamos National Laboratory; Schwartz, C L [Los Alamos National Laboratory; Stone, B [Los Alamos National Laboratory; Tupa, Dale [Los Alamos National Laboratory; Vogan-McNeil, Wendy S [Los Alamos National Laboratory

    2010-02-09

    In July 2009 we fielded three explosively (HE) driven Richtmyer-Meshkov instability experiments at the LANSCE Proton Radiography Facility (pRad), and in August of 2009 we fielded one flyer plate experiment on the pRad 40 mm powder gun. One HE experiment was done in vacuum, and the other two within four atmospheres of noble gasses: Xe and Ne. These two gases were chosen to study the viscous effects on ejecta formation. It is unexpected, but the viscosity {eta} of Ne is twice that of Xe, and, due to the atomic mass difference between the two, the kinematic viscosity ({eta}/{rho}) of Ne is about ten times that of Xe. The results showed that ejecta formation is sensitively linked to the gas density, which implies that the Weber number is more important in ejecta formation than the Reynolds number.

  11. Hydrodynamical interaction of mildly relativistic ejecta with an ambient medium

    CERN Document Server

    Suzuki, Akihiro; Shigeyama, Toshikazu

    2016-01-01

    Hydrodynamical interaction of spherical ejecta freely expanding at mildly relativistic speeds into an ambient cold medium is studied in semi-analytical and numerical ways to investigate how ejecta produced in energetic stellar explosions dissipate their kinetic energy through the interaction with the surrounding medium. We especially focus on the case in which the circumstellar medium is well represented by a steady wind at a constant mass-loss rate having been ejected from the stellar surface prior to the explosion. As a result of the hydrodynamical interaction, the ejecta and circumstellar medium are swept by the reverse and forward shocks, leading to the formation of a geometrically thin shell. We present a semi-analytical model describing the dynamical evolution of the shell and compare the results with numerical simulations. The shell can give rise to bright emission as it gradually becomes transparent to photons. while it is optically thick. We develop an emission model for the expected emission from th...

  12. Chicxulub Ejecta Impact Trenches And Terminal Impact

    Science.gov (United States)

    Page, R. L.

    2013-05-01

    DISCOVERY During a Pacific voyage from E. Australia to the US on a small sailing research vessel what appears to be two Chicxulub impact trenches were discovered in the ocean floor at depths of 4,627m and 3,519m. DESCRIPTION Trench A begins at a depth of 4,627m, 704km from the Chicxulub impact and is 18km long, 5km wide and 225m deep. Trench B begins at a depth of 3,519m, 732km from the Chixculub impact and is 23km long, 7 km wide and 400m deep. At the end of Trench B is what appears to be a debris deposit 5km long. Their relationship to the Chicxulub impact seems confirmed by their central axis, which when extended intersect at the Chicxulub impact at N Lat 21.33, W Long 89.5. Down range 286km from the end of Trench B is what appears to be the terminal impact of the object that created the two trenches. This is in the form of several large boulders, small seamounts, and islands in shallower depths indicating breakup of the object 1040km from the Chicxulub impact. The trenches are in an area of the Caribbean where currents prevented them from being silted in, preserving their physical form on the ocean floor. The object that created the trenches could have been large ejecta from the impact or possibly part of the asteroid that separated before impact or upon impact and carried on 1000km down range. The trajectory of both trenches is an upward angle of about 3 degrees. This indicates that the trajectory of the object was at a low angle, very high velocity and was deflected slightly upward upon impact with the ocean floor 4,627 below sea level. RESEARCH The first two phases of 10 phases consisting of mapping, exploration, research, and documentation of the impacts have been completed. Phase 1 consisted of assembling available sea floor data of the area of the impacts. Phase 2 consisted of selecting aerial and under water images from Google Earth, preparing bathymetric mapping from a GEBCO_08. BODC raster analysis with 50m contour intervals of the impact area

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

    Energy Technology Data Exchange (ETDEWEB)

    Arendt, Richard G. [CRESST, University of Maryland, Baltimore County, Baltimore, MD 21250 (United States); Dwek, Eli; Kober, Gladys [NASA Goddard Space Flight Center, Code 665, Greenbelt, MD 20771 (United States); Rho, Jeonghee [SETI Institute, 189 Bernardo Avenue, Mountain View, CA 94043 (United States); Hwang, Una, E-mail: Richard.G.Arendt@nasa.gov [NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States)

    2014-05-01

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

  14. The Links Between Target Properties and Layered Ejecta Craters in Acidalia and Utopia Planitiae Mars

    Science.gov (United States)

    Jones, E.; Osinski, G. R.

    2013-08-01

    Layered ejecta craters on Mars may form from excavation into subsurface volatiles. We examine a new catalogue of martian craters to decipher differences between the single- and double-layered ejecta populations in Acidalia and Utopia.

  15. Erosion and Ejecta Reaccretion on 243 Ida and Its Moon

    Science.gov (United States)

    Geissler, Paul; Petit, Jean-Marc; Durda, Daniel D.; Greenberg, Richard; Bottke, William; Nolan, Michael; Moore, Jeffrey

    1996-03-01

    Galileo images of Asteroid 243 Ida and its satellite Dactyl show surfaces which are dominantly shaped by impact cratering. A number of observations suggest that ejecta from hypervelocity impacts on Ida can be distributed far and wide across the Ida system, following trajectories substantially affected by the low gravity, nonspherical shape, and rapid rotation of the asteroid. We explore the processes of reaccretion and escape of ejecta on Ida and Dactyl using three-dimensional numerical simulations which allow us to compare the theoretical effects of orbital dynamics with observations of surface morphology. The effects of rotation, launch location, and initial launch speed are first examined for the case of an ideal triaxial ellipsoid with Ida's approximate shape and density. Ejecta launched at low speeds (V≪Vesc) reimpact near the source craters, forming well-defined ejecta blankets which are asymmetric in morphology between leading and trailing rotational surfaces. The net effect of cratering at low ejecta launch velocities is to produce a thick regolith which is evenly distributed across the surface of the asteroid. In contrast, no clearly defined ejecta blankets are formed when ejecta is launched at higher initial velocities (V∼Vesc). Most of the ejecta escapes, while that which is retained is preferentially derived from the rotational trailing surfaces. These particles spend a significant time in temporary orbit around the asteroid, in comparison to the asteroid's rotation period, and tend to be swept up onto rotational leading surfaces upon reimpact. The net effect of impact cratering with high ejecta launch velocities is to produce a thinner and less uniform soil cover, with concentrations on the asteroids' rotational leading surfaces. Using a realistic model for the shape of Ida (P. Thomas, J. Veverka, B. Carcich, M. J. S. Belton, R. Sullivan, and M. Davies 1996,Icarus120, 000-000), we find that an extensive color/albedo unit which dominates the

  16. Scenario Of The 4 kyr Extraterrestrial Impact : Crater Location, Ejecta-Dispersion and Consequences.

    Science.gov (United States)

    Courty, M.; Abbott, D. H.; Cortese, G.; Crisci, A.; Crosta, X.; de Wever, P.; Fedoroff, M.; Greenwood, P.; Grice, K.; Mermoux, M.; Scharer, U.; Smith, D. C.; Thiemens, M. H.

    2006-12-01

    The 4 kyr BP impact event has been identified from deep-sea, soil and archaeological records as the worldwide pulverisation of a volatile-rich debris jet(1). High resolution sequences show two stages of ejecta fallout linked to the impact-triggered doublet gaseous regime(2): scattered solid debris at the ground surface and spray of the vaporized hot fireball with thermal blast and local ignition. Ejecta debris consist of flow- textured impact glass, impact breccia and incompletely melted marine clasts: volcano-clastic sandy mudstone, calcareous mud, granite-gneiss, schists, volcanic breccia, kerogen and algal mud. Marine microfossils, organo-mineral markers, and the debris-fallout spatial pattern indicate two potential impact craters: an Antarctic source with an admixture of volcanic glass and ice rafted debris, from the vicinity of Heard Island and the Kerguelen plateau; a low latitude, shallow water one with hydrocarbons possibly from the Gulf of Mexico. Fine mixing of target materials from far distant source craters emphasizes a unique impact-ejecta. This matches the theoretical view of a debris jet channelled along the corridor cut through the atmosphere by the incoming projectile, raised upward, and dispersed widely(3). The isotopic anomaly of the sulphur phase in the kerogen volatile-component, indicating mass independent fractionation due to photolytic transformation, suggests launching at great heights, beyond the O2-O3 UV shield, responsible for climate disturbances. The incomplete melting of target rocks and global dispersion of impact breccia out of the craters would result from splash of small-sized projectile at rather great water depth and a low angle impact (10-15 degrees) into porous, highly compressible marine sediments. The spatially variable distribution of the organo-mineral and melt components, and the wide range of phase transformation reflect nonequilibrium shock-melting and micro-scale thermal processes in the heterogeneous vapor plume

  17. Non-stationary Rayleigh-Taylor instability in supernovae ejecta

    CERN Document Server

    Ribeyre, X; Tikhonchuk, V T; Bouquet, S; Sanz, J; Ribeyre, Xavier; Hallo, Ludovic; Tikhonchuk, Vladimir; Bouquet, Serge; Sanz, Javier

    2005-01-01

    The Rayleigh-Taylor instability plays an important role in the dynamics of several astronomical objects, in particular, in supernovae (SN) evolution. In this paper we develop an analytical approach to study the stability analysis of spherical expansion of the SN ejecta by using a special transformation in the co-moving coordinate frame. We first study a non-stationary spherical expansion of a gas shell under the pressure of a central source. Then we analyze its stability with respect to a no radial, non spherically symmetric perturbation of the of the shell. We consider the case where the polytropic constant of the SN shell is $\\gamma=5/3$ and we examine the evolution of a arbitrary shell perturbation. The dispersion relation is derived. The growth rate of the perturbation is found and its temporal and spatial evolution is discussed. The stability domain depends on the ejecta shell thickness, its acceleration, and the perturbation wavelength.

  18. The Axially Symmetric Ejecta of Supernova 1987A

    CERN Document Server

    Wang, L; Höflich, P; Khokhlov, A; Baade, D; Branch, D; Challis, P M; Filippenko, A V; Fransson, C; Garnavich, P M; Kirshner, R P; Lundqvist, P; McCray, R; Panagia, N; Pun, C S J; Phillips, M M; Sonneborn, G; Suntzeff, N B

    2002-01-01

    Extensive early observations proved that the ejecta of supernova 1987A (SN 1987A) are aspherical. Fifteen years after the supernova explosion, the Hubble Space Telescope has resolved the rapidly expanding ejecta. The late-time images and spectroscopy provide a geometrical picture that is consistent with early observations and suggests a highly structured, axially symmetric geometry. We present here a new synthesis of the old and new data. We show that the Bochum event, presumably a clump of $^{56}$Ni, and the late-time image, the locus of excitation by $^{44}$Ti, are most naturally accounted for by sharing a common position angle of about 14\\degree, the same as the mystery spot and early speckle data on the ejecta, and that they are both oriented along the axis of the inner circumstellar ring at 45\\degree to the plane of the sky. We also demonstrate that the polarization represents a prolate geometry with the same position angle and axis as the early speckle data and the late-time image and hence that the geo...

  19. Direct Ejecta Velocity Measurements of Tycho's Supernova Remnant

    CERN Document Server

    Sato, Toshiki

    2016-01-01

    We present the first direct ejecta velocity measurements of Tycho's supernova remnant (SNR). Chandra's high angular resolution images reveal a patchy structure of radial velocities in the ejecta that can be separated into distinct redshifted, blueshifted, and low velocity ejecta clumps or blobs. The typical velocities of the redshifted and blueshifted blobs are <~ 7,800 km/s and <~ 5,000 km/s, respectively. The highest velocity blobs are located near the center, while the low velocity ones appear near the edge as expected for a generally spherical expansion. Systematic uncertainty on the velocity measurements from gain calibration was assessed by carrying out joint fits of individual blobs with both the ACIS-I and ACIS-S detectors. We identified an annular region (~3.3'-3.5'), where the surface brightness in the Si, S, and Fe K lines reaches a peak while the line width reaches a minimum value. These minimum line widths correspond to ion temperatures of ~1 MeV for each of the three species, in excellent ...

  20. Evolution of the 1919 Ejecta of V605 Aquilae

    CERN Document Server

    Clayton, Geoffrey C; Long, Lindsey A; Meyer, Paul I; Sugerman, Ben E K; Montiel, Edward; Sparks, William B; Meakes, M G; Chesneau, O; De Marco, O

    2013-01-01

    New imaging of V605 Aql, was obtained in 2009 with HST/WFPC2, which had a nova-like outburst in 1919, and is located at the center of the planetary nebula (PN), Abell 58. This event has long been ascribed to a final helium shell flash, but it has been suggested recently that it may instead have been an ONe nova. The new images provide an 18 year baseline for the expansion of the ejecta from the 1919 event. In addition, the central star has been directly detected in the visible for the first time since 1923, when it faded from sight due to obscuration by dust. The expansion of the ejecta has a velocity of ~200 km/s, and an angular expansion rate of ~10 mas/yr, consistent with a 1919 ejection. This implies a geometric distance of 4.6 kpc for V605 Aql, consistent with previous estimates. The gas mass in the central knot of ejecta was previously estimated to be 5 x 10^-5 M(Sun). It is estimated that warm dust associated with this gas has a mass of ~10^-5 M(Sun). There is also evidence for a significant amount, 10...

  1. Nucleosynthesis in the Ejecta of Neutron Star Mergers

    CERN Document Server

    Martin, Dirk; Arcones, Almudena; Korobkin, Oleg; Thielemann, Friedrich-Karl

    2015-01-01

    Heavy elements like gold, platinum or uranium are produced in the r-process, which needs neutron-rich and explosive environments. Neutron star mergers are a promising candidate for an r-process site. They exhibit three different channels for matter ejection fulfilling these conditions: dynamic ejecta due to tidal torques, neutrino-driven winds and evaporating matter from the accretion disk. We present a first study of the integrated nucleosynthesis for a neutrino-driven wind from a neutron star merger with a hyper-massive neutron star. Trajectories from a recent hydrodynamical simulation are divided into four different angle regions and post-processed with a reaction network. We find that the electron fraction varies around $Y_e \\approx 0.1 - 0.4$, but its distribution differs for every angle of ejection. Hence, the wind ejecta do not undergo a robust r-process, but rather possess distinct nucleosynthesis yields depending on the angle range. Compared to the dynamic ejecta, a smaller amount of neutron-rich mat...

  2. EVOLUTION OF THE 1919 EJECTA OF V605 AQUILAE

    Energy Technology Data Exchange (ETDEWEB)

    Clayton, Geoffrey C.; Montiel, Edward [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Bond, Howard E.; Sparks, William B.; Meakes, M. G. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Long, Lindsey A.; Meyer, Paul I.; Sugerman, Ben E. K. [Department of Physics and Astronomy, Goucher College, 1021 Dulaney Valley Road, Baltimore, MD 21204 (United States); Chesneau, O. [Observatoire de la Cote d' Azur-CNRS-UMR 6203, Dept Gemini, Avenue Copernic, F-06130 Grasse (France); De Marco, O., E-mail: gclayton@fenway.phys.lsu.edu, E-mail: emonti2@lsu.edu, E-mail: bond@stsci.edu, E-mail: sparks@stsci.edu, E-mail: mgmeakes@gmail.com, E-mail: ben.sugerman@goucher.edu, E-mail: olivier.chesneau@ob-azur.fr, E-mail: orsola@science.mq.edu.au [Department of Physics, Macquarie University, Sydney, NSW 2109 (Australia)

    2013-07-10

    New imaging of V605 Aql, was obtained in 2009 with HST/WFPC2, which had a nova-like outburst in 1919, and is located at the center of the planetary nebula (PN), A58. This event has long been ascribed to a final helium shell flash, but it has been suggested recently that it may instead have been an ONe nova. The new images provide an 18 yr baseline for the expansion of the ejecta from the 1919 event. In addition, the central star has been directly detected in the visible for the first time since 1923, when it faded from sight due to obscuration by dust. The expansion of the ejecta has a velocity of {approx}200 km s{sup -1}, and an angular expansion rate of {approx}10 mas yr{sup -1}, consistent with a 1919 ejection. This implies a geometric distance of 4.6 kpc for V605 Aql, consistent with previous estimates. The gas mass in the central knot of ejecta was previously estimated to be 5 Multiplication-Sign 10{sup -5} M{sub Sun }. It is estimated that warm dust associated with this gas has a mass of {approx}10{sup -5} M{sub Sun }. There is also evidence for a significant amount, 10{sup -3} M{sub Sun }, of cold (75 K) dust, which may be associated with its PN. The knot ejected in 1919 is asymmetrical and is approximately aligned with the asymmetry of the surrounding PN. Polarimetric imaging was obtained to investigate whether the 2001 spectrum of V605 Aql was obtained primarily in scattered light from dust in the central knot, but the signal-to-noise in the data was insufficient to measure the level of polarization.

  3. Neutron star kicks and their relationship to supernovae ejecta mass

    Science.gov (United States)

    Bray, J. C.; Eldridge, J. J.

    2016-10-01

    We propose a simple model to explain the velocity of young neutron stars. We attempt to confirm a relationship between the amount of mass ejected in the formation of the neutron star and the `kick' velocity imparted to the compact remnant resulting from the process. We assume that the velocity is given by vkick = α (Mejecta/Mremnant) + β . To test this simple relationship, we use the BPASS (Binary Population and Spectral Synthesis) code to create stellar population models from both single and binary star evolutionary pathways. We then use our Remnant Ejecta and Progenitor Explosion Relationship (REAPER) code to apply different α and β values, and three different `kick' orientations then record the resulting velocity probability distributions. We find that while a single star population provides a poor fit to the observational data, the binary population provides an excellent fit. Values of α = 70 km s-1 and β = 110 km s-1 reproduce the Hobbs et al. observed two-dimensional velocities, and α = 70 km s-1 and β = 120 km s-1 reproduce their inferred three-dimensional velocity distribution for nearby single neutron stars with ages less than 3 Myr. After testing isotropic, spin-axis aligned and orthogonal to spin-axis `kick' orientations, we find no statistical preference for a `kick' orientation. While ejecta mass cannot be the only factor that determines the velocity of supernova compact remnants, we suggest that it is a significant contributor and that the ejecta-based `kick' should replace the Maxwell-Boltzmann velocity distribution currently used in many population synthesis codes.

  4. Lateral Translation of Explosion Crater Ejecta: A Working Model Based Upon Pellet Experiments

    Science.gov (United States)

    1975-08-19

    empiric-al ejecta studies to a variety of, telds and ,eologic-al settings, and (2) characteri-ing * the relative threat the total ejecta eavironment...inmqict cratering protesi . C-urrent thenrwie.s ies•t-•,. the cratering of impart crater frwmationt arn basedt primartly upon (1) small -cale imnpact expe...ial thrown farther travels faster so that the total ejecta deposit can reflect , variety of depositional processes ranging from the low velocity

  5. Spatial Distribution of Mg-rich Ejecta in LMC Supernova Remnant N49B

    Science.gov (United States)

    Park, Sangwook; Bhalerao, Jayant

    2017-01-01

    The supernova remnant (SNR) N49B in the Large Magellanic Cloud is a peculiar example of a core-collapse SNR that shows the shocked metal-rich ejecta enriched only in Mg without evidence for a similar overabundance in O and Ne. Based on archival Chandra data, we present results from our extensive spatially resolved spectral analysis of N49B. We find that the Mg-rich ejecta gas extends from the central regions of the SNR out to the southeastern outermost boundary of the SNR. This elongated feature shows an overabundance for Mg similar to that of the main ejecta region at the SNR center, and its electron temperature appears to be higher than the central main ejecta gas. We estimate that the Mg mass in this southeastern elongated ejecta feature is ∼10% of the total Mg ejecta mass. Our estimated lower limit of >0.1 M⊙ on the total mass of the Mg-rich ejecta confirms the previously suggested large mass for the progenitor star (M ≳ 25 M⊙). We entertain scenarios of an SNR expanding into a nonuniform medium and an energetic jet-driven supernova in an attempt to interpret these results. However, with the current results, the origins of the extended Mg-rich ejecta and the Mg-only-rich nature of the overall metal-rich ejecta in this SNR remain elusive.

  6. Formation of Dust in the Ejecta of Type Ia Supernovae

    CERN Document Server

    Nozawa, Takaya; Kozasa, Takashi; Tanaka, Masaomi; Nomoto, Ken'ichi; Umeda, Hideyuki

    2011-01-01

    We investigate the formation of dust grains in the ejecta of Type Ia supernovae (SNe Ia), adopting the carbon-deflagration W7 model. In the calculations of dust formation, we apply the nucleation and grain growth theory and consider the two cases with and without formation of CO and SiO molecules. The results of the calculations show that for the sticking probability of alpha_j=1, C, silicate, Si, and FeS grains can condense at early times of ~100--300 days after the explosion, whereas Fe and SiC grains cannot form substantially. Due to the low gas density in SNe Ia with no H-envelope, the average radii of the newly formed grains are generally below 0.01 micron, being much smaller than those in Type II-P SNe. This supports our previous conclusion that the radius of dust formed in the ejecta is smaller in SNe with less massive envelopes. The total dust mass ranges from 3x10^{-4} M_sun to 0.2 M_sun for alpha_j=0.1--1, depending on whether or not CO and SiO molecules are formed. We also estimate the optical dept...

  7. THE TERMINAL VELOCITY OF THE DEEP IMPACT DUST EJECTA

    Directory of Open Access Journals (Sweden)

    M. Rengel

    2009-01-01

    Full Text Available The collision of the projectile released from NASA Deep Impact spacecraft on the nucleus of comet 9P/Tempel 1 generated a hot plume. Afterwards ejecta were created, and material moved slowly in a form of a dust cloud, which dissipated during several days after the impact. Here we report a study about the distribution of terminal velocities of the particles ejected by the impact. This is performed by the development and application of an illconditioned inverse problem approach. We model the light-curves as seen by the Narrow Angle Camera (NAC of OSIRIS onboard the ESA spacecraft Rosetta, and we compare them with the OSIRIS observations. Terminal velocities are derived using a maximum likelihood estimator. The dust velocity distribution is well constrained, and peaks at around 220 m s-1, which is in good agreement with published estimates of the expansion velocities of the dust cloud. Measured and modeled velocity of the dust cloud suggests that the impact ejecta were quickly accelerated by the gas in the cometary coma. This analysis provides a more thorough understanding of the properties (velocity and mass of dust of the Deep Impact dust cloud.

  8. Neutron Star Kicks and their Relationship to Supernovae Ejecta Mass

    CERN Document Server

    Bray, J C

    2016-01-01

    We propose a simple model to explain the velocity of young neutron stars. We attempt to confirm a relationship between the amount of mass ejected in the formation of the neutron star and the `kick' velocity imparted to the compact remnant resulting from the process. We assume the velocity is given by $v_{\\rm kick}=\\alpha\\,(M_{\\rm ejecta} / M_{\\rm remnant}) + \\beta\\,$. To test this simple relationship we use the BPASS (Binary Population and Spectral Synthesis) code to create stellar population models from both single and binary star evolutionary pathways. We then use our Remnant Ejecta and Progenitor Explosion Relationship (REAPER) code to apply different $\\alpha$ and $\\beta$ values and three different `kick' orientations then record the resulting velocity probability distributions. We find that while a single star population provides a poor fit to the observational data, the binary population provides an excellent fit. Values of $\\alpha=70\\, {\\rm km\\,s^{-1}}$ and $\\beta=110\\,{\\rm km\\,s^{-1}}$ reproduce the \\c...

  9. Overlapping Ballistic Ejecta Fields: Separating Distinct Blasts at Kings Bowl, Idaho

    Science.gov (United States)

    Borg, C.; Kobs-Nawotniak, S. E.; Hughes, S. S.; Sears, D. W. G.; Heldmann, J. L.; Lim, D. S. S.; Haberle, C. W.; Sears, H.; Elphic, R. C.; Kobayashi, L.; Garry, W. B.; Neish, C.; Karunatillake, S.; Button, N.; Purcell, S.; Mallonee, H.; Ostler, B.

    2015-12-01

    Kings Bowl is a ~2200ka pit crater created by a phreatic blast along a volcanic fissure in the eastern Snake River Plain (ESRP), Idaho. The main crater measures approximately 80m in length, 30m in width, and 30m in depth, with smaller pits located nearby on the Great Rift fissure, and has been targeted by the FINESSE team as a possible analogue for Cyane Fossae, Mars. The phreatic eruption is believed to have occurred due to the interaction of groundwater with lava draining back into the fissure following a lava lake high stand, erupting already solidified basalt from this and previous ERSP lava flows. The contemporaneous draw back of the lava with the explosions may conceal some smaller possible blast pits as more lava drained into the newly formed pits. Ballistic ejecta from the blasts occur on both sides of the fissure. To the east, the ballistic blocks are mantled by fine tephra mixed with eolian dust, the result of a westerly wind during the explosions. We use differential GPS to map the distribution of ballistic blocks on the west side of the fissure, recording position, percent vesiculation, and the length of 3 mutually perpendicular axes for each block >20cm along multiple transects parallel to the fissure. From the several hundred blocks recorded, we have been able to separate the ballistic field into several distinct blast deposits on the basis of size distributions and block concentration. The smaller pits identified from the ballistic fields correspond broadly to the northern and southern limits of the tephra/dust field east of the fissure. Soil formation and bioturbation of the tephra by sagebrush have obliterated any tephrostratigraphy that could have been linked to individual blasts. The ballistic block patterns at Kings Bowl may be used to identify distinct ejecta groups in high-resolution imagery of Mars or other planetary bodies.

  10. Ejecta velocity distribution of impact craters formed on quartz sand: Effect of projectile density on crater scaling law

    Science.gov (United States)

    Tsujido, Sayaka; Arakawa, Masahiko; Suzuki, Ayako I.; Yasui, Minami

    2015-12-01

    In order to clarify the effects of projectile density on ejecta velocity distributions for a granular target, impact cratering experiments on a quartz sand target were conducted by using eight types of projectiles with different densities ranging from 11 g cm-3 to 1.1 g cm-3, which were launched at about 200 m s-1 from a vertical gas gun at Kobe University. The scaling law of crater size, the ejection angle of ejecta grains, and the angle of the ejecta curtain were also investigated. The ejecta velocity distribution obtained from each projectile was well described by the π-scaling theory of v0/√{gR} =k2(x0/R)-1/μ, where v0, g, R and x0 are the ejection velocity, gravitational acceleration, crater radius and ejection position, respectively, and k2 and μ are constants mostly depending on target material properties (Housen, K.R., Holsapple, K.A. [2011]. Icarus 211, 856-875). The value of k2 was found to be almost constant at 0.7 for all projectiles except for the nylon projectile, while μ increased with the projectile density, from 0.43 for the low-density projectile to 0.6-0.7 for the high-density projectile. On the other hand, the π-scaling theory for crater size gave a μ value of 0.57, which was close to the average of the μ values obtained from ejecta velocity distributions. The ejection angle, θ, of each grain decreased slightly with distance, from higher than 45° near the impact point to 30-40° at 0.6 R. The ejecta curtain angle is controlled by the two elementary processes of ejecta velocity distribution and ejection angle; it gradually increased from 52° to 63° with the increase of the projectile density. The comparison of our experimental results with the theoretical model of the crater excavation flow known as the Z-model revealed that the relationship between μ and θ obtained by our experiments could not be described by the Z-model (Maxwell, D.E. [1977]. In: Roddy, D.J., Pepin, R.O., Merrill, R.B. (Eds.), Impact and Explosion Cratering

  11. Analysis of Regolith Simulant Ejecta Distributions from Normal Incident Hypervelocity Impact

    Science.gov (United States)

    Edwards, David L.; Cooke, William; Suggs, Rob; Moser, Danielle E.

    2008-01-01

    The National Aeronautics and Space Administration (NASA) has established the Constellation Program. The Constellation Program has defined one of its many goals as long-term lunar habitation. Critical to the design of a lunar habitat is an understanding of the lunar surface environment; of specific importance is the primary meteoroid and subsequent ejecta environment. The document, NASA SP-8013 'Meteoroid Environment Model Near Earth to Lunar Surface', was developed for the Apollo program in 1969 and contains the latest definition of the lunar ejecta environment. There is concern that NASA SP-8013 may over-estimate the lunar ejecta environment. NASA's Meteoroid Environment Office (MEO) has initiated several tasks to improve the accuracy of our understanding of the lunar surface ejecta environment. This paper reports the results of experiments on projectile impact into powdered pumice and unconsolidated JSC-1A Lunar Mare Regolith simulant targets. Projectiles were accelerated to velocities between 2.45 and 5.18 km/s at normal incidence using the Ames Vertical Gun Range (AVGR). The ejected particles were detected by thin aluminum foil targets strategically placed around the impact site and angular ejecta distributions were determined. Assumptions were made to support the analysis which include; assuming ejecta spherical symmetry resulting from normal impact and all ejecta particles were of mean target particle size. This analysis produces a hemispherical flux density distribution of ejecta with sufficient velocity to penetrate the aluminum foil detectors.

  12. Ejecta Production in Microgravity from Low Velocity Impacts in Regolith

    Science.gov (United States)

    Colwell, J. E.; Dove, A.; Brisset, J.; Rascon, A. N.; Brightwell, K.

    2015-12-01

    We report on the results of the third PRIME (Physics of Regolith Impacts in Microgravity Experiment) campaign on-board the NASA C-9 airplane in August 2014. The objective of PRIME is to study low-velocity impacts of cm-scale particles into planetary regolith under reduced gravity and microgravity conditions, measuring how dust on the surfaces of planetary ring particles, planetesimals and asteroids dissipates energy in the collision and the mass-velocity distribution of any ejecta produced in the impact. PRIME can perform impacts into granular materials at speeds of ~5-50 cm/s in microgravity. Impacts are performed in vacuum and projectiles are spherical particles launched by a spring designed to provide the desired impact energy. The target materials studied are quartz sand and JSC-1 lunar regolith simulant, filled to a depth of 2 cm in the target tray. Projectile materials are quartz, brass, and stainless steel to provide a range of impact energies at constant impact velocity. Impacts are performed in isolated chambers and up to 8 experiments can be performed per flight. The data collected consists of video recordings of the impacts, taken with a high resolution video camera at 120 frames per second. The impacts observed during the PRIME-3 campaign resulted in 9 marble rebounds and 15 impacts with ejecta. Seven of these 15 were at accelerations of ~0.05 g while the remaining impacts were performed in free fall. For each rebound observed, the coefficient of restitution of the impact was measured and for each collision that produced ejecta, the ejected particles were tracked to determine their initial velocities. The PRIME-3 campaign successfully extended the region of the parameter field explored by investigating impacts at velocities lower than observed during previous campaigns while collecting new data on impacts at asteroid gravity levels. We present our new results and combine them with results from previous similar experiments and discuss applications to

  13. Dust in the Early Universe: Dust Formation in the Ejecta of Population III Supernovae

    CERN Document Server

    Nozawa, T; Umeda, H; Maeda, K; Nomoto, K; Nozawa, Takaya; Kozasa, Takashi; Umeda, Hideyuki; Maeda, Keiichi; Nomoto, Ken'ichi

    2003-01-01

    We investigate the formation of dust grains in the ejecta of population III supernovae including pair--instability supernovae, applying a theory of non-- steady state nucleation and grain growth. In the calculations, the time evolution of gas temperature in theejecta, which strongly affects the number density and size of newly formed grains, is calculated by solving the radiative transfer equation taking account of the energy deposition of radio active elements. Two extreme cases are considered for the mixing of elements in the ejecta; unmixed and uniformly mixed cases within the He--core. The results of calculations are summarized as the followings; in the unmixed ejecta, a variety of grain species condense, reflecting the difference of the elemental composition at the formation site in the ejecta, otherwise only oxide grains condense in the uniformly mixed ejecta. The average size of newly formed grains spans the range of three orders of magnitude, depending on the grain species and the formation condition,...

  14. The reionization of unshocked ejecta in SN 1006

    Science.gov (United States)

    Hamilton, Andrew J. S.; Fesen, Robert A.

    1988-01-01

    The validity of carbon-deflagration models white dwarf models for type Ia supernovae is investigated by examining whether most of the iron in the center of SN 1006 exists in forms other than Fe II, such as iron grains or other ionic stages of iron, as the models require. The possible ways in which iron can be hidden in SN 1006 are reviewed, and an argument on observational grounds is made against any appreciable fraction of iron in grains or Fe I. Various mechanisms for ionizing unshocked iron beyond Fe II are discussed; the most probable mechanism for ionizing the iron appears to be photoionization by UV and X-ray emission from reverse-shocked ejecta. A detailed model for this reverse-shcok photoionization mechanism is described.

  15. Is the Ejecta of ETA Carinae Overabundant or Overexcited

    Science.gov (United States)

    Gull, Theodore; Davidson, Kris; Johansson, Sveneric; Damineli, Augusto; Ishibashi, Kaxunori; Corcoran, Michael; Hartman, Henrick; Viera, Gladys; Nielsen, Krister

    2003-01-01

    The ejecta of Eta Carinae, revealed by HST/STIS, are in a large range of physical conditions. As Eta Carinae undergoes a 5.52 period, changes occur in nebular emission and nebular absorption. "Warm" neutral regions, partially ionized regions, and fully ionized regions undergo significant changes. Over 2000 emission lines, most of Fe-like elements, have been indentified in the Weigelt blobs B and D. Over 500 emission lines have been indentified in the Strontium Filament. An ionized Little Homunculus is nestled within the neutral-shelled Homunculus. In line of sight, over 500 nebular absorption lines have been identified with up to twenty velocity components. STIS is following changes in many nebular emission and absorption lines as Eta Carinae approaches the minimum, predicted to be in June/July 2003, during the General Assembly. Coordinated observations with HST, CHANDRA, RXTE, FUSE, UVES/VLT, Gemini and other observatories are following this minimum.

  16. Is the Ejecta of Eta Carinae Overabundant or Overexcited?

    Science.gov (United States)

    Gull, Theodore; Davidson, Kris; Johansson, Sveneric; Damineli, Augusto; Ishibashi, Kazunori; Corcoran, Michael; Hartman, Henrick; Viera, Gladys; Nielsen, Krister; Eta Carinae Teams

    The ejecta of Eta Carinae revealed by HST/STIS are in a large range of physical conditions. As Eta Carinae undergoes a 5.52 period changes occur in nebular emission and nebular absorption. ""Warm"" neutral regions partially ionized regions and fully ionized regions undergo significant changes. Over 2000 emission lines most of Fe-like elements have been indentified in the Weigelt blobs B and D. Over 500 emission lines have been identifed in the Strontium Filament. An ionized Little Homunculus is nestled within the neutral-shelled Homunculus. In line of sight over 500 nebular absorption lines have been identified with up to twenty velocity components. STIS is following changes in many nebular emission and absorption lines as Eta Carinae approaches the minimum predicted to be in June/July 2003 during the General Assembly. Coordinated observations with HST CHANDRA RXTE FUSE UVES/VLT Gemini and other observatories are following this minimum.

  17. On the evolution of ejecta fragments in compact supernova remnants

    CERN Document Server

    Cid-Fernandes, R; Rózyczka, M; Franco, J; Terlevich, R J; Tenorio-Tagle, G; Miller, W

    1996-01-01

    We examine the evolution of inhomogeneities (fragments) of supernova ejecta in compact supernova remnants by means of hydrodynamical modeling and simplified analytical calculations. Under the influence of intense post-shock cooling the fragments become strongly compressed as they traverse the hot shocked region between the reverse and outer shocks of the remnant. We find that the most likely outcome of the interaction of fragments with the reverse shock and the hot shocked region is their disruption resulting in generation of secondary fragments. Secondary fragments arriving at the thin and dense outer shell of the remnant give rise to brief X-ray flashes. Under suitable conditions the primary fragments may traverse the hot shocked region without being completely destroyed, to eventually reach the outer shell as dense, elongated structures. Collisions of such fragments with the shell are likely to give rise to powerful X-ray flares.

  18. The Ejecta of Eta Carinae as Studied by STIS

    Science.gov (United States)

    Gull, Theodore R.; Oegerle, William R. (Technical Monitor)

    2002-01-01

    The Space Telescope Imaging Spectrograph has been used to study the emission and absorption spectra of ejecta surrounding Eta Carinae. Discussion will be presented on the overall structure of the Homunculus, the Weigelt blobs and the Strontium filament. Three visits have been accomplished with the Position Angle precisely the same and covering the Central Source and Weigelt Blobs B and D. Deep spectra have been done at several positions to obtain the overall velocity structure of the Homunculus and the disk region. Mapping has been done with the STIS medium dispersion gratings set near H beta and H alpha. We have obtained full coverage of the strontium filament from 1640 Angstroms to 10300 Angstroms. The structure and physical properties will be described.

  19. Pyroclastic flow deposits on Venus as indicators of renewed magmatic activity

    Science.gov (United States)

    Campbell, Bruce A.; Morgan, Gareth A.; Whitten, Jennifer L.; Carter, Lynn M.; Glaze, Lori S.; Campbell, Donald B.

    2017-07-01

    Radar bright deposits on Venus that have diffuse margins suggest eruptions that distribute debris over large areas due to ground-hugging flows from plume collapse. We examine deposits in eastern Eistla, western Eistla, Phoebe, and Dione Regiones using Magellan data and Earth-based radar maps. The radar bright units have no marginal lobes or other features consistent with viscous flow. Their morphology, radar echo strength, polarization properties, and microwave emissivity are consistent with mantling deposits composed of few centimeters or larger clasts. This debris traveled downhill up to 100 km on modest slopes and blanketed lava flows and tectonic features to depths of tens of centimeters to a few meters over areas up to 40 × 103 km2. There is evidence for ongoing removal and exhumation of previously buried terrain. A newly identified occurrence is associated with a ridge belt south of Ushas Mons. We also note radar bright streaks of coarse material west of Rona Chasma that reflect the last traces of a deposit mobilized by winds from the formation of Mirabeau crater. If the radar bright units originate by the collapse of eruption columns, with coarse fragmental material entrained and fluidized by hot gases, then their extent suggests large erupted volatile (CO2 or H2O) amounts. We propose that these deposits reflect the early stage of renewed magmatic activity, with volatile-rich, disrupted magma escaping through vents in fractured regions of the upper crust. Rapidly eroding under Venus surface conditions or buried by subsequent eruptions, these markers of recently renewed activity have disappeared from older regions.

  20. Exploring a Detonation Nature of Mesoscopic Perturbations and Ejecta Formation from the Mesoscale Probing of the PBX-driven Liners

    Science.gov (United States)

    Plaksin, Igor; Guiruis, Raafat; Rodrigues, Luis; Mendes, Ricardo; Plaksin, Svyatoslav; Fernandes, Eduardo; Ferreira, Claudia

    2015-06-01

    Ejecting debris from free surface of liner is of considerable interest at optimization of explosive devices, in which the PBX-driven liner effects shock compression of gaseous matter. Following factors were historically considered as main drivers of material ejection: granular microstructure of liner material, roughness and surface defects of liner, and shock pressure time history in PBX-driven liner. In contrast to existing models, we are considering the small scale fluctuations of detonation flow as probable dominating factor of surface jetting in the PBX-driven collapsing liners. Obtained experimental evidence is indicative that jetting from the liners is caused by meso-scale perturbations of PBX detonations, which are identified as (1) ejecta of overdriven detonation products through detonation front, (2) ejecta-driven detonation cells, and (3) galloping detonation front motion. Spatially resolved scenarios of each of phenomena (1-3) were obtained in experiments with copper-liners and HMX-based PBXs fabricated on maximum packing density of crystalline constituents. Both the DRZ-induced perturbations translated to a PBX-driven liner and the ejected debris were recorded and quantitatively measured in the mesoscale range with application of the 96-channel optical analyzer MCOA-UC. Work was supported by the ONR and ONR Global Grants N00014-12-1-0477 and N62909-12-1-7131 with Drs. Clifford Bedford and John Zimmerman Program Managers.

  1. Long-term dynamical evolution of dusty ejecta from Deimos

    Science.gov (United States)

    Makuch, Martin; Krivov, Alexander V.; Spahn, Frank

    2005-04-01

    We re-assess expected properties of the presumed dust belt of Mars formed by impact ejecta from Deimos. Previous studies have shown that dynamics of Deimos particles are dominated by two perturbing forces: radiation pressure (RP) and Mars' oblateness (J2). At the same time, they have demonstrated that lifetimes of particles, especially of grains about ten of micrometers in size, may reach more than 104 years. On such timescales, the Poynting-Robertson drag (PR) becomes important. Here we provide a study of the dynamics under the combined action of all three perturbing forces. We show that a PR decay of the semimajor axes leads to an adiabatic decrease of amplitudes and periods of oscillations in orbital inclinations predicted in the framework of the underlying RP+J2 problem. Furthermore, we show that smallest of the long-lived Deimos grains (radius≈5- 10μm) may reach a chaotic regime, resulting in unpredictable and abrupt changes of their dynamics. The particles just above that size ( ≈10- 15μm) should be the most abundant in the Deimos torus. Our dynamical analysis, combined with a more accurate study of the particle lifetimes, provides corrections to earlier predictions about the dimensions and geometry of the Deimos torus. In addition to a population, appreciably inclined and shifted towards the Sun, the torus should contain a more contracted, less asymmetric, and less tilted component between the orbits of Phobos and Deimos.

  2. Planet formation from the ejecta of common envelopes

    CERN Document Server

    Schleicher, Dominik R G

    2013-01-01

    The close binary system NN Serpentis must have gone through a common envelope phase before the formation of its white dwarf. During this phase, a substantial amount of mass was lost from the envelope. The recently detected orbits of circumbinary planets were suggested to be inconsistent with planet formation before the mass loss. We explore whether new planets may have formed from the ejecta of the common envelope, and derive the expected planetary mass as a function of radius. We employ the model of \\citet{Kashi11} to estimate the amount of mass that is retained during the ejection event, and infer the properties of the resulting disk from the conservation of mass and angular momentum. The resulting planetary masses are estimated from models with and without radiative feedback. We show that the observed planetary masses can be reproduced for appropriate model parameters. Photoheating can stabilize the disks in the interior, potentially explaining the observed planetary orbits on scales of a few AU. We compar...

  3. Overview of the Chicxulub impactite and proximal ejecta

    Science.gov (United States)

    Claeys, Ph

    2003-04-01

    Several types of impactites have now been recovered from the various wells drilled in the Chicxulub crater in Yucatan. The old Pemex wells (Yucatan 6 and Chicxulub 1) contain a highly heterogeneous and stratified suevite, which upper unit is unusually rich in carbonates, impact breccia and a possibly an impact melt at the very bottom of C1. They are located towards the crater center (C1), on the flank of the peak ring (Y6). The thickness of impactite in this zone exceeds 250 m. The UNAM wells just outside the crater rim reveal sedimentary breccia and a fall-out suevite richer in silicate melt and basement fragments, than its crater equivalent. There, the thickness of the impactite was probably several hundred meters, considering that its top might have been eroded. It can also be speculated that a cover of fall-back suevite extended over the ejecta blanket in Yucatan, all the way to Belize and perhaps even to the region of Tabasco, in Southern Mexico. The recently drilled Yaxcopoil contains about 100 m of impactites, which is currently under study. Preliminary data seem to show less variability than the material recovered from Y6. As in the UNAM well, the impactite is dominated by basement material, and shows alternating severely altered and better preserved horizons.

  4. Ejecta Exchange, Color Evolution in the Pluto System, and Implications for KBOs and Asteroids with Satellites

    CERN Document Server

    Stern, S A

    2008-01-01

    We examine the ability of impacts by Kuiper Belt debris to cause regolith exchange between objects in the Pluto system. We find that ejecta velocities from KB impacts are too low to escape from Pluto and Charon. However, ejecta can escape Nix and Hydra, and is capable of covering one another to depths as high as 10s of meters, and Charon and Pluto, perhaps to depths up to several 10s of cm. Although Pluto's annual atmospheric frost deposition cycle will cover such imported debris on timescales faster than it is emplaced, no such masking mechanism is available on Hydra, Nix, and Charon. As a result, ejecta exchange between these bodies is expected to evolve their colors, albedos, and other photometric properties to be similar. We examined the ability of ejecta exchange to work for other Kuiper Belt binaries and found the process can be effective in many cases. This process may also operate in asteroid binary systems.

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

    Science.gov (United States)

    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.

  6. Model calculations of the proximal and globally distributed distal ejecta from the Chicxulub impact crater

    Science.gov (United States)

    Durda, Daniel D.; Kring, David A.; Pierazzo, Elisabetta; Melosh, H. J.

    1997-03-01

    The origin of the K/T boundary sequence of impact ejecta of the Chicxulub impact crater has been reexamined by constructing a computer simulation of the launch and deposition of both low- and high-energy ejecta. The distribution of low- and high-energy ejecta following a vertical impact is illustrated based on 20,000 tracer particles. The distribution is also shown for a 25 deg oblique impact from the southeast. Most of the high-energy ejecta stays within 50,000 km of Earth, with several percent reaching 100,000 km or more before reentering the atmosphere. About 25 percent of the material reaccretes within 2 hrs, about 50 percent within 8 hrs, and about 75 percent within about 72 hrs. At least 20-30 percent of the ejected material escapes the Earth. The implications of these findings for the postimpact environment are considered.

  7. Properties of Ejecta Blanket Deposits Surrounding Morasko Meteorite Impact Craters (Poland)

    Science.gov (United States)

    Szokaluk, M.; Muszyński, A.; Jagodziński, R.; Szczuciński, W.

    2016-08-01

    Morasko impact craters are a record of the fall of a meteorite into the soft sediments. The presented results illustrate the geological structure of the area around the crater as well as providing evidence of the occurrence of ejecta blanket.

  8. Simulated meteorite impacts and volcanic explosions: Ejecta analyses and planetary implications

    Science.gov (United States)

    Gratz, A. J.; Nellis, W. J.

    1992-01-01

    Past cratering studies have focused primarily on crater morphology. However, important questions remain about the nature of crater deposits. Phenomena that need to be studied include the distribution of shock effects in crater deposits and crater walls; the origin of mono- and polymict breccia; differences between local and distal ejecta; deformation induced by explosive volcanism; and the production of unshocked, high-speed ejecta that could form the lunar and martian meteorites found on the Earth. To study these phenomena, one must characterize ejecta and crater wall materials from impacts produced under controlled conditions. New efforts at LLNL simulate impacts and volcanism and study resultant deformation. All experiments use the two-stage light-gas gun facility at LLNL to accelerate projectiles to velocities of 0.2 to 4.3 km/s, including shock pressures of 0.9 to 50 GPa. We use granite targets and novel experimental geometries to unravel cratering processes in crystalline rocks. We have thus far conducted three types of simulations: soft recovery of ejecta, 'frozen crater' experiments, and an 'artificial volcano. Our ejecta recovery experiments produced a useful separation of impactites. Material originally below the projectile remained trapped there, embedded in the soft metal of the flyer plate. In contrast, material directly adjacent to the projectile was jetted away from the impact, producing an ejecta cone that was trapped in the foam recovery fixture. We find that a significant component of crater ejecta shows no signs of strong shock; this material comes from the near-surface 'interference zone' surrounding the impact site. This phenomenon explains the existence of unshocked meteorites on the Earth of lunar and martian origin. Impact of a large bolide on neighboring planets will produce high-speed, weakly shocked ejecta, which may be trapped by the Earth's gravitational field. 'Frozen crater' experiments show that the interference zone is highly

  9. Investigating the retention of bright and dark ejecta from small rayed craters on mars

    Science.gov (United States)

    Calef, Fred J., III

    2010-12-01

    Impact cratering is one of the principal geologic processes operating throughout the solar system. On Mars, small rayed impact craters (SRC) form continuously and randomly on the surface. Ejecta retention, the timespan and ability of excavated ejecta to remain in place around a crater rim, records a lineage of recent surface processes. However, the timescales under which small rayed craters are produced and their origin, whether terrestrial or cosmic, plays an important role in further investigating surface processes and possible recent climate variations. By examining thousands of randomly chosen panchromatic images from the Mars Orbiter Camera Narrow Angle (MOCNA) camera, a population of 630 SRC was catalogued across three equatorial and two polar regions on Mars. The survey of MOCNA images also revealed intriguing Enigmatic Linear Features (ELFs) in the northern hemisphere of Mars, which a short side study revealed to be a unique form of dust-devil track. From statistically examining several physical parameters, dust deposition and periglacial erosion were found to be the major factors affecting ejecta retention for the SRC. SRC morphology revealed ejecta retention sequences that followed four stages of ejecta retention from the initial impact to eventual erasure from the surface. By reconstructing the current cratering rate from estimates of atmospheric filtering, it was possible to calculate the ejecta retention age across Mars. In general, SRC ejecta are retained on the surface for <100 ka. Based on ejecta morphology and retention age estimates, a possible shift from depositional to erosional processes just south of the Martian equator is suspected to have occurred within this timeframe.

  10. The effects of red supergiant mass loss on supernova ejecta and the circumburst medium

    CERN Document Server

    van Loon, Jacco Th

    2009-01-01

    Massive stars becoming red supergiants lose a significant amount of their mass during that brief evolutionary phase. They then either explode as a hydrogen-rich supernova (SN Type II), or continue to evolve as a hotter supergiant (before exploding). The slow, dusty ejecta of the red supergiant will be over-run by the hot star wind and/or SN ejecta. I will present estimates of the conditions for this interaction and discuss some of the implications.

  11. Discovery of Outlying, High-Velocity Oxygen-Rich Ejecta in Cassiopeia A

    CERN Document Server

    Fesen, R A; Morse, J; Chevalier, R A; Borkowski, K J; Dopita, M A; Gerardy, C L; Lawrence, S S; Raymond, J C; Van den Bergh, S

    2006-01-01

    Hubble Space Telescope images of the young Galactic supernova remnant Cassiopeia A reveal a far larger population of outlying, high-velocity knots of ejecta with a broader range of chemical properties than previously suspected. We identify three main classes of outer ejecta: 1) Knots dominated by [N II] 6548,6583 emission; 2) Knots dominated by oxygen emission lines especially [O II] 7319,7330; and 3) Knots with emission line strengths similar to the [S II] strong FMK ejecta commonly seen in the main emission shell. The discovery of a significant population of O-rich ejecta situated in between the suspected N-rich outer photospheric layer and S-rich FMK-like ejecta suggests that the Cas A progenitor's chemical layers were not completely disrupted by the supernova explosion outside of the remnant's NE and SW high velocity `jet' regions. In addition, we find the majority of O-rich outer ejecta at projected locations out beyond (v = 6500 - 9000 km/s) the remnant's fastest moving Fe-rich X-ray emission material (...

  12. Comparison of Ejecta Distributions from Normal Incident Hypervelocity Impact on Lunar Regolith Simulant

    Science.gov (United States)

    Edwards, David L.; Cooke, William; Scruggs, Rob; Moser, Danielle E.

    2008-01-01

    The National Aeronautics and Space Administration (NASA) is progressing toward long-term lunar habitation. Critical to the design of a lunar habitat is an understanding of the lunar surface environment; of specific importance is the primary meteoroid and subsequent ejecta environment. The document, NASA SP-8013, was developed for the Apollo program and is the latest definition of the ejecta environment. There is concern that NASA SP-8013 may over-estimate the lunar ejecta environment. NASA's Meteoroid Environment Office (MEO) has initiated several tasks to improve the accuracy of our understanding of the lunar surface ejecta environment. This paper reports the results of experiments on projectile impact into powered pumice and unconsolidated JSC-1A Lunar Mare Regolith stimulant (JSC-1A) targets. The Ames Vertical Gun Range (AVGR) was used to accelerate projectiles to velocities in excess of 5 km/s and impact the targets at normal incidence. The ejected particles were detected by thin aluminum foil targets placed around the impact site and angular distributions were determined for ejecta. Comparison of ejecta angular distribution with previous works will be presented. A simplistic technique to characterize the ejected particles was formulated and improvements to this technique will be discussed for implementation in future tests.

  13. Supernova ejecta with a relativistic wind from a central compact object: a unified picture for extraordinary supernovae

    Science.gov (United States)

    Suzuki, Akihiro; Maeda, Keiichi

    2017-04-01

    The hydrodynamical interaction between freely expanding supernova ejecta and a relativistic wind injected from the central region is studied in analytic and numerical ways. As a result of the collision between the ejecta and the wind, a geometrically thin shell surrounding a hot bubble forms and expands in the ejecta. We use a self-similar solution to describe the early dynamical evolution of the shell and carry out a two-dimensional special relativistic hydrodynamic simulation to follow further evolution. The Rayleigh-Taylor instability inevitably develops at the contact surface separating the shocked wind and ejecta, leading to the complete destruction of the shell and the leakage of hot gas from the hot bubble. The leaking hot materials immediately catch up with the outermost layer of the supernova ejecta and thus different layers of the ejecta are mixed. We present the spatial profiles of hydrodynamical variables and the kinetic energy distributions of the ejecta. We stop the energy injection when a total energy of 1052 erg, which is 10 times larger than the initial kinetic energy of the supernova ejecta, is deposited into the ejecta and follow the subsequent evolution. From the results of our simulations, we consider expected emission from supernova ejecta powered by the energy injection at the centre and discuss the possibility that superluminous supernovae and broad-lined Ic supernovae could be produced by similar mechanisms.

  14. Discovery of Outlying, High-Velocity O-Rich Ejecta in Cas A

    Science.gov (United States)

    Fesen, R.; Hammell, M.; Morse, J.; Borkowski, K.; Chevalier, R.; Dopita, M.; Lawrence, S.; Raymond, J.; van den Bergh, S.

    2004-12-01

    We present Hubble Space Telescope WFPC2 and ACS images of the Galactic supernova remnant Cas A taken in 2000, 2002, and 2004 which reveal the presence of numerous outlying ejecta knots whose optical emission is dominated by oxygen lines including [O I] 6300,6364 A, and [O II] 7319,7330 A. These ejecta are found immediately behind the faster moving [N II] 6548,6583 A dominated ejecta knots and are seen (in projection) to lie slightly ahead or roughly coincident with the remnant's forward blast wave as detected in deep Chandra X-ray images (Hwang et al. 2004, ApJL, in press). Proper motion derived projected expansion velocities indicate this O-rich layer is expanding at 8000 -- 8500 km/s, or some 500 km/s slower than the outer N-rich material. Location of O-dominated ejecta knots in the eastern portion of the remnant behind N-rich ejecta but ahead of the remnant's outermost S,Si-rich ejecta as seen in X-ray emission maps, suggests that: 1) With the exception of the NE-SW jet regions, the Cas A SN largely retained the progenitor's He,N -- O -- S,Si abundance zones, and 2) Fingers of X-ray emitting, Fe-rich material seen along the eastern limb at larger radial distances than S,Si-rich ejecta did not significantly penetrate the progenitor's O-rich or He,N-rich outer layers. This research was funded by NASA HST GO programs 8281, 9238, and 9890.

  15. Effect of impact angles on ejecta and crater shape of aluminum alloy 6061-T6 targets in hypervelocity impacts

    Directory of Open Access Journals (Sweden)

    Hayashi K.

    2012-08-01

    Full Text Available The effect of the impact angle of projectiles on the crater shape and ejecta in thick aluminum alloy targets was investigated in hypervelocity impacts. When polycarbonate projectiles and aluminum alloy 6061-T6 target were used, the impact angle of the projectiles clearly affected the crater shape, as expected. The impact angle also affected the ejecta mass, ejecta size and scatter angle. However, the effect at 15∘ and 22.5∘ was not great. When the impact angles were 30∘ and 45∘, the effect was clearly confirmed. The impact angle clearly affected the axial ratio of ejecta fragments, c/a.

  16. Exploring hotspots of pneumococcal pneumonia and potential impacts of ejecta dust exposure following the Christchurch earthquakes.

    Science.gov (United States)

    Pearson, Amber L; Kingham, Simon; Mitchell, Peter; Apparicio, Philippe

    2013-12-01

    The etiology of pneumococcal pneumonia (PP) is well-known. Yet, some events may increase its incidence. Natural disasters may worsen air quality, a risk factor for PP. We investigated spatial/spatio-temporal clustering of PP pre- and post-earthquakes in Christchurch, New Zealand. The earthquakes resulted in deaths, widespread damage and liquefaction ejecta (a source of air-borne dust). We tested for clusters and associations with ejecta, using 97 cases (diagnosed 10/2008-12/2011), adjusted for age and area-level deprivation. The strongest evidence to support the potential role of ejecta in clusters of PP cases was the: (1) geographic shift in the spatio-temporal cluster after deprivation adjustment to match the post-earthquake clusters and; (2) increased relative risk in the fully-adjusted post-earthquake compared to the pre-earthquake cluster. The application of spatial statistics to study PP and ejecta are novel. Further studies to assess the long-term impacts of ejecta inhalation are recommended particularly in Christchurch, where seismic activity continues.

  17. Exchange of ejecta between Telesto and Calypso: Tadpoles, horseshoes, and passing orbits

    CERN Document Server

    Dobrovolskis, Anthony R; Zahnle, Kevin J; Lissauer, Jack J

    2010-01-01

    We have numerically integrated the orbits of ejecta from Telesto and Calypso, the two small Trojan companions of Saturn's major satellite Tethys. Ejecta were launched with speeds comparable to or exceeding their parent's escape velocity, consistent with impacts into regolith surfaces. We find that the fates of ejecta fall into several distinct categories, depending on both the speed and direction of launch. The slowest ejecta follow sub-orbital trajectories and re-impact their source moon in less than one day. Slightly faster debris barely escape their parent's Hill sphere and are confined to tadpole orbits, librating about Tethys' triangular Lagrange points L4 (leading, near Telesto) or L5 (trailing, near Calypso) with nearly the same orbital semi-major axis as Tethys, Telesto, and Calypso. These ejecta too eventually re-impact their source moon, but with a median lifetime of a few dozen years. Those which re-impact within the first ten years or so have lifetimes near integer multiples of 348.6 days (half th...

  18. Spall strength and ejecta production of gold under explosively driven shock wave compression

    Energy Technology Data Exchange (ETDEWEB)

    La Lone, B. M. [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Stevens, G. D. [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Turley, W. D. [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Veeser, L. R. [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Holtkamp, D. B. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2013-12-16

    Explosively driven shock wave experiments were conducted to characterize the spall strength and ejecta production of high-purity cast gold samples. The samples were from 0.75 to 1.84 mm thick and 30 mm in diameter. Peak stresses up to 44 GPa in gold were generated using PBX-9501 high explosive. Sample free surface and ejecta velocities were recorded using photonic Doppler velocimetry techniques. Lithium niobate pins were used to quantify the time dependence of the ejecta density and the total ejected mass. An optical framing camera for time-resolved imaging and a single-image x-ray radiograph were used for additional characterization. Free surface velocities exhibited a range of spall strengths from 1.7 to 2.4 GPa (mean: 2.0 ±0.3 GPa). The pullback signals were faint, minimal ringing was observed in the velocity records, and the spall layer continued to decelerate after first pull back. These results suggest finite tensile strength was present for some time after the initial void formation. Ejecta were observed for every sample with a roughened free surface, and the ejecta density increased with increased surface roughness, which was different in every experiment. The total ejected mass is consistent with the missing mass model.

  19. X-Ray Emitting Ejecta of Supernova Remnant N132D

    CERN Document Server

    Borkowski, Kazimierz J; Reynolds, Stephen P

    2007-01-01

    The brightest supernova remnant in the Magellanic Clouds, N132D, belongs to the rare class of oxygen-rich remnants, about a dozen objects that show optical emission from pure heavy-element ejecta. They originate in explosions of massive stars that produce large amounts of O, although only a tiny fraction of that O is found to emit at optical wavelengths. We report the detection of substantial amounts of O at X-ray wavelengths in a recent 100 ks Chandra ACIS observation of N132D. A comparison between subarcsecond-resolution Chandra and Hubble images reveals a good match between clumpy X-ray and optically emitting ejecta on large (but not small) scales. Ejecta spectra are dominated by strong lines of He- and H-like O; they exhibit substantial spatial variations partially caused by patchy absorption within the LMC. Because optical ejecta are concentrated in a 5 pc radius elliptical expanding shell, the detected ejecta X-ray emission also originates in this shell.

  20. Lunar crater ejecta: Physical properties revealed by radar and thermal infrared observations

    Science.gov (United States)

    Ghent, R. R.; Carter, L. M.; Bandfield, J. L.; Tai Udovicic, C. J.; Campbell, B. A.

    2016-07-01

    We investigate the physical properties, and changes through time, of lunar impact ejecta using radar and thermal infrared data. We use data from two instruments on the Lunar Reconnaissance Orbiter (LRO) - the Diviner thermal radiometer and the Miniature Radio Frequency (Mini-RF) radar instrument - together with Earth-based radar observations. We use this multiwavelength intercomparison to constrain block sizes and to distinguish surface from buried rocks in proximal ejecta deposits. We find that radar-detectable rocks buried within the upper meter of regolith can remain undisturbed by surface processes such as micrometeorite bombardment for >3 Gyr. We also investigate the thermophysical properties of radar-dark haloes, comprised of fine-grained, rock-poor ejecta distal to the blocky proximal ejecta. Using Diviner data, we confirm that the halo material is depleted in surface rocks, but show that it is otherwise thermophysically indistinct from background regolith. We also find that radar-dark haloes, like the blocky ejecta, remain visible in radar observations for craters with ages >3 Ga, indicating that regolith overturn processes cannot replenish their block populations on that timescale.

  1. An HST Survey of the Highest-Velocity Ejecta in Cassiopeia A

    CERN Document Server

    Fesen, Robert A

    2015-01-01

    We present Hubble Space Telescope WFC3/IR images of the Cassiopeia A supernova remnant that survey its high-velocity, S-rich debris in the NE jet and SW counterjet regions through [S III] 9069, 9531 and [S II] 10,287 - 10,370 line emissions. We identify nearly 3400 sulfur emitting knots concentrated in ~120 degree wide opposing streams, almost triple the number previously known. The vast majority of these ejecta knots lie at projected distances well out ahead of the remnant's forward blast wave and main shell ejecta, extending to angular distance of 320" to the NE and 260" to the SW from the center of expansion. Such angular distances imply undecelerated ejecta knot transverse velocities of 15,600 and 12,700 km/s respectively, assuming an explosion date ~1670 AD and a distance of 3.4 kpc. Optical spectra of knots near the outermost tip of the NE ejecta stream show strong emission lines of S, Ca, and Ar. We estimate a total mass ~0.1 Msun and a kinetic energy of at least ~1 x10^50 erg for S-rich ejecta in the ...

  2. Upper Eocene tektite and impact ejecta layer on the Continental Slope off New Jersey

    Science.gov (United States)

    Glass, B. P.; Koeberl, C.; Blum, J. D.; McHugh, C. M. G.

    1998-03-01

    During Leg 150 of the Ocean Drilling Project (ODP) two sites (903C and 904A) were cored which have sediments of the same biostratigraphic age as the upper Eocene tektite-bearing ejecta layer at Deep Sea Drilling Project (DSDP) Site 612. Core 45X from ODP Site 904A (~ 4 km north of Site 612) contains a 5-cm-thick tektite-bearing ejecta layer and Core 56 from Site 903C (~ 8 km north-northwest of Site 904) contains a 2-cm-thick layer of impact ejecta without any tektite or impact glass. Shocked quartz and feldspar grains, with multiple sets of planar deformation features, and abundant coesite-bearing grains are present at both sites. The major oxide contents, trace element compositions, and rare earth element patterns of the Site 904 tektites are similar to those of the Site 612 tektites and to North American tektites (especially bediasites). The Sr and Nd values for one composite tektite sample from Site 904 fall within the range previously obtained for the Site 612 tektites, which defines a linear trend that, if extrapolated, would intersect the values obtained for North American tektites. The water contents of eight tektite fragments from Site 904 range from 0.017 to 0.098 wt. %, and, thus, are somewhat higher than is typical for tektites. The heavy mineral assemblages of the 63 - 125 m size fractions from the ejecta layers at Sites 612, 903, and 904 are all similar. Therefore, we conclude that the ejecta layer at all three sites are from the same impact event and that the tektites at Sites 904 and 612 belong to the North American tektite strewn field. Clinopyroxene-bearing (cpx) spherules occur below, or in the lower part of, the main ejecta layer at all three sites. At all three sites the cpx spherules have been partly or completely replaced with pyrite which preserved the original crystalline textures. Site 612, 903, and 904 cpx spherules are similar to those found in the Caribbean Sea, Gulf of Mexico, central equatorial Pacific, western equatorial Pacific, and

  3. X-ray illumination of the ejecta of Supernova 1987A

    CERN Document Server

    Larsson, J; Östlin, 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

    2011-01-01

    We present the late-time optical light curve of the ejecta of SN 1987A measured from HST imaging observations spanning the past 17 years. We find that the flux from the ejecta declined up to around year 2001, powered by the radioactive decay of 44Ti. Then the flux started to increase, more than doubling by the end of 2009. We show that the increase is the result of energy deposited by X-rays produced in the interaction with the circumstellar medium. We suggest that the change of the dominant energy input to the ejecta, from internal to external, marks the transition from supernova to supernova remnant. The details of the observations and the modelling are described in the accompanying supplementary information.

  4. Magnetohydrodynamic Effects in Propagating Relativistic Ejecta: Reverse Shock and Magnetic Acceleration

    Science.gov (United States)

    Mizuno, Y.; Nishikawa, K.I.; Zhang, B.; Giacomazzo, B.; Hardee, P.E.; Nagataki, S.; Hartmann, D.H.

    2008-01-01

    We solve the Riemann problem for the deceleration of arbitrarily magnetized relativistic ejecta injected into a static unmagnetized medium. We find that for the same initial Lorentz factor, the reverse shock becomes progressively weaker with increasing magnetization s (the Poynting-to-kinetic energy flux ratio), and the shock becomes a rarefaction wave when s exceeds a critical value, sc, defined by the balance between the magnetic pressure in the ejecta and the thermal pressure in the forward shock. In the rarefaction wave regime, we find that the rarefied region is accelerated to a Lorentz factor that is significantly larger than the initial value. This acceleration mechanism is due to the strong magnetic pressure in the ejecta.

  5. Chromium isotope evidence in ejecta deposits for the nature of Paleoproterozoic impactors

    Science.gov (United States)

    Mougel, Bérengère; Moynier, Frédéric; Göpel, Christa; Koeberl, Christian

    2017-02-01

    Non-mass dependent chromium isotopic signatures have been successfully used to determine the presence and identification of extra-terrestrial materials in terrestrial impact rocks. Paleoproterozoic spherule layers from Greenland (Grænsesø) and Russia (Zaonega), as well as some distal ejecta deposits (Lake Superior region) from the Sudbury impact (1849 ± 0.3 Ma) event, have been analyzed for their Cr isotope compositions. Our results suggest that 1) these distal ejecta deposits are all of impact origin, 2) the Grænsesø and Zaonega spherule layers contain a distinct carbonaceous chondrite component, and are possibly related to the same impact event, which could be Vredefort (2023 ± 4 Ma) or another not yet identified large impact event from that of similar age, and 3) the Sudbury ejecta record a complex meteoritic signature, which is different from the Grænsesø and Zaonega spherule layers, and could indicate the impact of a heterogeneous chondritic body.

  6. The interaction of core-collapse supernova ejecta with a companion star

    Science.gov (United States)

    Liu, Zheng-Wei; Tauris, T. M.; Röpke, F. K.; Moriya, T. J.; Kruckow, M.; Stancliffe, R. J.; Izzard, R. G.

    2015-12-01

    Context. The progenitors of many core-collapse supernovae (CCSNe) are expected to be in binary systems. After the SN explosion in a binary, the companion star may suffer from mass stripping and be shock heated as a result of the impact of the SN ejecta. If the binary system is disrupted by the SN explosion, the companion star is ejected as a runaway star, and in some cases as a hypervelocity star. Aims: By performing a series of three-dimensional (3D) hydrodynamical simulations of the collision of SN ejecta with the companion star, we investigate how CCSN explosions affect their binary companion. Methods: We use the BEC stellar evolution code to construct the detailed companion structure at the moment of SN explosion. The impact of the SN blast wave on the companion star is followed by means of 3D smoothed particle hydrodynamics (SPH) simulations using the Stellar GADGET code. Results: For main-sequence (MS) companion stars, we find that the amount of removed stellar mass, the resulting impact velocity, and the chemical contamination of the companion that results from the impact of the SN ejecta strongly increases with decreasing binary separation and increasing explosion energy. Their relationship can be approximately fitted by power laws, which is consistent with the results obtained from impact simulations of Type Ia SNe. However, we find that the impact velocity is sensitive to the momentum profile of the outer SN ejecta and, in fact, may decrease with increasing ejecta mass, depending on the modeling of the ejecta. Because most companion stars to Type Ib/c CCSNe are in their MS phase at the moment of the explosion, combined with the strongly decaying impact effects with increasing binary separation, we argue that the majority of these SNe lead to inefficient mass stripping and shock heating of the companion star following the impact of the ejecta. Conclusions: Our simulations show that the impact effects of Type Ib/c SN ejecta on the structure of MS companion

  7. Spatial Distribution of Mg-Rich Ejecta in LMC Supernova Remnant N49B

    OpenAIRE

    Park, Sangwook; Bhalerao, Jayant

    2016-01-01

    The supernova remnant (SNR) N49B in the Large Magellanic Cloud is a peculiar example of a core-collapse SNR to show the shocked metal-rich ejecta enriched only in Mg without evidence for a similar overabundance in O and Ne. Based on archival Chandra data we present results from our extensive spatially-resolved spectral analysis of N49B. We find that the Mg-rich ejecta gas extends from the central regions of the SNR out to the southeastern outermost boundary of the SNR. This elongated feature ...

  8. Small-body deflection techniques using spacecraft: techniques in simulating the fate of ejecta

    CERN Document Server

    Schwartz, Stephen R; Michel, Patrick; Jutzi, Martin

    2016-01-01

    We define a set of procedures to numerically study the fate of ejecta produced by the impact of an artificial projectile with the aim of deflecting an asteroid. Here we develop a simplified, idealized model of impact conditions that can be adapted to fit the details of specific deflection-test scenarios, such as what is being proposed for the AIDA project. Ongoing studies based upon the methodology described here can be used to inform observational strategies and safety conditions for an observing spacecraft. To account for ejecta evolution, the numerical strategies we are employing are varied and include a large N-Body component, a smoothed-particle hydrodynamics (SPH) component, and an application of impactor scaling laws. Simulations that use SPH-derived initial conditions show high-speed ejecta escaping at low angles of inclination, and very slowly moving ejecta lofting off the surface at higher inclination angles, some of which re-impacts the small-body surface. We are currently investigating the realism...

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

    Science.gov (United States)

    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.

  10. Modeling the Ballistic Behavior of Solid Ejecta from the Deep Impact Cratering Event

    Science.gov (United States)

    Richardson, J. E.; Melosh, H. J.

    2006-03-01

    We describe results from a forward model of the first-order, solid ejecta particle behavior from the impact produced by the Deep Impact mission. The expansion rate of the plume places constraints on the gravity field, mass, and density of Tempel 1.

  11. Detailed Analysis of the Intra-Ejecta Dark Plains of Caloris Basin, Mercury

    Science.gov (United States)

    Buczkowski, Debra L.; Seelos, K. S.

    2010-01-01

    The Caloris basin on Mercury is floored by light-toned plains and surrounded by an annulus of dark-toned material interpreted to be ejecta blocks and smooth, dark, ridged plains. Strangely, preliminary crater counts indicate that these intra-ejecta dark plains are younger than the light-toned plains within the Caloris basin. This would imply a second, younger plains emplacement event, possibly involving lower albedo material volcanics, which resurfaced the original ejecta deposit. On the other hand, the dark plains may be pre-Caloris light plains covered by a thin layer of dark ejecta. Another alternative to the hypothesis of young, dark volcanism is the possibility that previous crater counts have not thoroughly distinguished between superposed craters (fresh) and partly-buried craters (old) and therefore have not accurately determined the ages of the Caloris units. This abstract outlines the tasks associated with a new mapping project of the Caloris basin, intended to improve our knowledge of the geology and geologic history of the basin, and thus facilitate an understanding of the thermal evolution of this region of Mercury.

  12. Simulations and experiments of ejecta generation in twice-shocked metals

    Science.gov (United States)

    Karkhanis, Varad; Ramaprabhu, Praveen; Buttler, William; Hammerberg, James; Cherne, Frank; Andrews, Malcolm

    2016-11-01

    Using continuum hydrodynamics embedded in the FLASH code, we model ejecta generation in recent target experiments, where a metallic surface was loaded by two successive shock waves. The experimental data were obtained from a two-shockwave, high-explosive tool at Los Alamos National Laboratory, capable of generating ejecta from a shocked tin surface in to a vacuum. In both simulations and experiment, linear growth is observed following the first shock event, while the second shock strikes a finite-amplitude interface leading to nonlinear growth. The timing of the second incident shock was varied systematically in our simulations to realize a finite-amplitude re-initialization of the RM instability driving the ejecta. We find the shape of the interface at the event of second shock is critical in determining the amount of ejecta, and thus must be used as an initial condition to evaluate subsequent ejected mass using a source model. In particular, the agreement between simulations, experiments and the mass model is improved when shape effects associated with the interface at second shock are incorporated. This work was supported in part by the (U.S.) Department of Energy (DOE) under Contract No. DE-AC52-06NA2-5396.

  13. The morphology of the ejecta in Supernova 1987A: a study over time and wavelength

    CERN Document Server

    Larsson, Josefin; Kjaer, Karina; Jerkstrand, Anders; Kirshner, Robert P; Leibundgut, Bruno; Lundqvist, Peter; Mattila, Seppo; McCray, Richard; Sollerman, Jesper; Spyromilio, Jason; Wheeler, J Craig

    2012-01-01

    We present a study of the morphology of the ejecta in Supernova 1987A based on images and spectra from the HST as well as integral field spectroscopy from VLT/SINFONI. The HST observations were obtained between 1994 - 2011 and primarily probe the outer hydrogen-rich zones of the ejecta. The SINFONI observations were obtained in 2005 and 2011 and instead probe the [Si I]/[Fe II] emission from the inner regions. We find a strong temporal evolution of the morphology in the HST images, from a roughly elliptical shape before ~5,000 days, to a more irregular, edge-brightened morphology thereafter. We demonstrate that this transition is a natural consequence of the change in the dominant energy source powering the ejecta, from radioactive decay before ~5,000 days to X-ray input from the circumstellar interaction thereafter. The [Si I]/[Fe II] images display a more uniform morphology, which may be due to a remaining significant contribution from radioactivity in the inner ejecta and the higher abundance of these elem...

  14. Dissecting a SN impostor's circumstellar medium: MUSEing about the SHAPE of eta Car's outer ejecta

    CERN Document Server

    Mehner, A; Groh, J H; Vogt, F P A; Baade, D; Boffin, H M J; Davidson, K; de Wit, W J; Humphreys, R M; Martayan, C; Oudmaijer, R D; Rivinius, T; Selman, F

    2016-01-01

    Aims. The structural inhomogeneities and kinematics of massive star nebulae are tracers of their mass-loss history. We conduct a three-dimensional morpho-kinematic analysis of the ejecta of eta Car outside its famous Homunculus nebula. Methods. We carried out the first large-scale integral field unit observations of eta Car in the optical, covering a field of view of 1'x1' centered on the star. Observations with the Multi Unit Spectroscopic Explorer (MUSE) at the Very Large Telescope (VLT) reveal the detailed three-dimensional structure of eta Car's outer ejecta. Morpho-kinematic modeling of these ejecta is conducted with the code SHAPE. Results. The largest coherent structure in eta Car's outer ejecta can be described as a bent cylinder with roughly the same symmetry axis as the Homunculus nebula. This large outer shell is interacting with the surrounding medium, creating soft X-ray emission. We establish the shape and extent of the ghost shell in front of the southern Homunculus lobe and confirm that the NN...

  15. Impact melt-bearing breccias of the Mistastin Lake impact structure: A unique planetary analogue for ground-truthing proximal ejecta emplacement

    Science.gov (United States)

    Mader, M. M.; Osinski, G. R.

    2013-12-01

    in matrix content, melt-fragment concentration, and contact relationships with adjacent impactites. Initial findings suggest differing origins for impact melt-bearing breccias from a single impact event. Three examples are highlighted: 1) Impact melt-bearing breccias, on an inner terrace, formed in boundary zones where hot impact melt flowed over cooler, ballistically emplaced polymict impact breccias. 2) Locally, a dyke of impact melt-bearing breccia suggests that this unit originated as hot lithic flow that moved laterally along the ground and then intruded as a fracture fill into target rocks. 3) A m-scale lens of melt-bearing breccia within the middle of a thick, 80m impact melt rock unit situated on an inner terrace, suggests that this lens may have originated from the crater floor and been incorporated into the melt pond during emplacement (i.e. movement of the melt from the crater floor to terrace shelf). In summary, the Mistastin Lake impact structure displays a multiple layered ejecta sequence that is consistent with, and requires, a multi-stage ejecta emplacement model as proposed by [1]. References: [1] Osinski et al. (2011) EPSL (310:167-181. [2] Melosh (1989) Oxford Univ. 245 pp. [3] French B. M. (1998) LPI Contribution 954,120pp. [4] Mader et al. (2011) 42nd LPSC, No.1608. [5] Mader et al. (2013) 43rd LPSC, No. 2517.

  16. The Three-Dimensional Motions of the Ejecta of Tycho's Supernova Remnant

    Science.gov (United States)

    Williams, Brian J.; Coyle, Nina; Yamaguchi, Hiroya; DePasquale, Joseph M.; Hewitt, John W.; Blondin, John M.; Borkowski, Kazimierz J.; Ghavamian, Parviz; Petre, Robert; Reynolds, Stephen P.

    2017-01-01

    We present the first three-dimensional measurements of the velocity of various ejecta knots in Tycho's supernova remnant, the remains of SN 1572, known to be a Type Ia explosion. When the ejecta knots pass through the reverse shock, they become heated to X-ray emitting temperatures, and Chandra's unmatched spatial resolution combined with the small age of this remnant allows us to watch it expand on measurable timescales. By combining a new epoch of 2015 Chandra X-ray observations with a previous 2003 epoch, we have a 12-year baseline over which we can measure proper motions from nearly 60 "tufts" of Si-rich ejecta, giving us the velocity in the plane of the sky. For the line of sight velocity, we use two different methods: a non-equilibrium ionization model fit to the strong Si and S lines in the 1.2-2.8 keV regime, and a fit consisting of a series of Gaussian lines. These methods give consistent results, and allow us to determine the red or blue shift of each of the knots, and thus, the third dimension of the velocity vector. Assuming a distance of 3.5 kpc, we find total velocities that range from roughly 2400 to 6600 km/s, with mean and median values of 4429 and 4450 km/s, respectively. In the plane of the sky, we find several regions where the ejecta knots have overtaken the forward shock. These regions have proper motions in excess of 6000 km/s. Some Type Ia supernova explosion models predict a velocity asymmetry in the ejecta, where the ejecta on one side of the remnant is moving faster than another side. We find no such velocity asymmetries in Tycho, and discuss our findings in light of various explosion models. Our previous work has shown an asymmetry in the velocity of the forward shock, with speeds in the southwest being significantly higher than those in the northeast. We have attributed this to a measured density gradient in the ISM, and not an asymmetry in the explosion. We compare our measurements with hydrodynamic simulations to show how the forward

  17. Subsurface volatile content of martian double-layer ejecta (DLE) craters

    Science.gov (United States)

    Viola, Donna; McEwen, Alfred S.; Dundas, Colin M.; Byrne, Shane

    2017-03-01

    Excess ice is widespread throughout the martian mid-latitudes, particularly in Arcadia Planitia, where double-layer ejecta (DLE) craters also tend to be abundant. In this region, we observe the presence of thermokarstically-expanded secondary craters that likely form from impacts that destabilize a subsurface layer of excess ice, which subsequently sublimates. The presence of these expanded craters shows that excess ice is still preserved within the adjacent terrain. Here, we focus on a 15-km DLE crater that contains abundant superposed expanded craters in order to study the distribution of subsurface volatiles both at the time when the secondary craters formed and, by extension, remaining today. To do this, we measure the size distribution of the superposed expanded craters and use topographic data to calculate crater volumes as a proxy for the volumes of ice lost to sublimation during the expansion process. The inner ejecta layer contains craters that appear to have undergone more expansion, suggesting that excess ice was most abundant in that region. However, both of the ejecta layers had more expanded craters than the surrounding terrain. We extrapolate that the total volume of ice remaining within the entire ejecta deposit is as much as 74 km3 or more. The variation in ice content between the ejecta layers could be the result of (1) volatile preservation from the formation of the DLE crater, (2) post-impact deposition in the form of ice lenses; or (3) preferential accumulation or preservation of subsequent snowfall. We have ruled out (2) as the primary mode for ice deposition in this location based on inconsistencies with our observations, though it may operate in concert with other processes. Although none of the existing DLE formation hypotheses are completely consistent with our observations, which may merit a new or modified mechanism, we can conclude that DLE craters contain a significant quantity of excess ice today.

  18. Dynamics, nucleosynthesis, and kilonova signature of black hole—neutron star merger ejecta

    Science.gov (United States)

    Fernández, Rodrigo; Foucart, Francois; Kasen, Daniel; Lippuner, Jonas; Desai, Dhruv; Roberts, Luke F.

    2017-08-01

    We investigate the ejecta from black hole—neutron star mergers by modeling the formation and interaction of mass ejected in a tidal tail and a disk wind. The outflows are neutron-rich, giving rise to optical/infrared emission powered by the radioactive decay of r-process elements (a kilonova). Here we perform an end-to-end study of this phenomenon, where we start from the output of a fully-relativistic merger simulation, calculate the post-merger hydrodynamical evolution of the ejecta and disk winds including neutrino physics, determine the final nucleosynthetic yields using post-processing nuclear reaction network calculations, and compute the kilonova emission with a radiative transfer code. We study the effects of the tail-to-disk mass ratio by scaling the tail density. A larger initial tail mass results in fallback matter becoming mixed into the disk and ejected in the subsequent disk wind. Relative to the case of a disk without dynamical ejecta, the combined outflow has lower mean electron fraction, faster speed, larger total mass, and larger absolute mass free of high-opacity Lanthanides or Actinides. In most cases, the nucleosynthetic yield is dominated by the heavy r-process contribution from the unbound part of the dynamical ejecta. A Solar-like abundance distribution can however be obtained when the total mass of the dynamical ejecta is comparable to the mass of the disk outflows. The kilonova has a characteristic duration of 1 week and a luminosity of  ∼ 1041 erg s-1 , with orientation effects leading to variations of a factor  ∼2 in brightness. At early times (< 1 d) the emission includes an optical component from the (hot) Lanthanide-rich material, but the spectrum evolves quickly to the infrared thereafter.

  19. Subsurface volatile content of martian double-layer ejecta (DLE) craters

    Science.gov (United States)

    Viola, Donna; McEwen, Alfred S.; Dundas, Colin M.; Byrne, Shane

    2017-01-01

    Excess ice is widespread throughout the martian mid-latitudes, particularly in Arcadia Planitia, where double-layer ejecta (DLE) craters also tend to be abundant. In this region, we observe the presence of thermokarstically-expanded secondary craters that likely form from impacts that destabilize a subsurface layer of excess ice, which subsequently sublimates. The presence of these expanded craters shows that excess ice is still preserved within the adjacent terrain. Here, we focus on a 15-km DLE crater that contains abundant superposed expanded craters in order to study the distribution of subsurface volatiles both at the time when the secondary craters formed and, by extension, remaining today. To do this, we measure the size distribution of the superposed expanded craters and use topographic data to calculate crater volumes as a proxy for the volumes of ice lost to sublimation during the expansion process. The inner ejecta layer contains craters that appear to have undergone more expansion, suggesting that excess ice was most abundant in that region. However, both of the ejecta layers had more expanded craters than the surrounding terrain. We extrapolate that the total volume of ice remaining within the entire ejecta deposit is as much as 74 km3 or more. The variation in ice content between the ejecta layers could be the result of (1) volatile preservation from the formation of the DLE crater, (2) post-impact deposition in the form of ice lenses; or (3) preferential accumulation or preservation of subsequent snowfall. We have ruled out (2) as the primary mode for ice deposition in this location based on inconsistencies with our observations, though it may operate in concert with other processes. Although none of the existing DLE formation hypotheses are completely consistent with our observations, which may merit a new or modified mechanism, we can conclude that DLE craters contain a significant quantity of excess ice today.

  20. Supernova Ejecta in the Youngest Galactic Supernova Remnant G1.9+0.3

    Science.gov (United States)

    Borkowski, Kazimierz J.; Reynolds, Stephen P.; Hwang, Una; Green, David A.; Petre, Robert; Krishnamurthy, Kalyani; Willett, Rebecca

    2013-01-01

    G1.9+0.3 is the youngest known Galactic supernova remnant (SNR), with an estimated supernova (SN) explosion date of approximately 1900, and most likely located near the Galactic Center. Only the outermost ejecta layers with free-expansion velocities (is) approximately greater than 18,000 km s-1 have been shocked so far in this dynamically young, likely Type Ia SNR. A long (980 ks) Chandra observation in 2011 allowed spatially-resolved spectroscopy of heavy-element ejecta. We denoised Chandra data with the spatio-spectral method of Krishnamurthy et al., and used a wavelet based technique to spatially localize thermal emission produced by intermediate-mass elements (IMEs: Si and S) and iron. The spatial distribution of both IMEs and Fe is extremely asymmetric, with the strongest ejecta emission in the northern rim. Fe K alpha emission is particularly prominent there, and fits with thermal models indicate strongly oversolar Fe abundances. In a localized, outlying region in the northern rim, IMEs are less abundant than Fe, indicating that undiluted Fe-group elements (including 56Ni) with velocities greater than 18,000 km s-1 were ejected by this SN. But in the inner west rim, we find Si- and S-rich ejecta without any traces of Fe, so high-velocity products of O-burning were also ejected. G1.9+0.3 appears similar to energetic Type Ia SNe such as SN 2010jn where iron-group elements at such high free-expansion velocities have been recently detected. The pronounced asymmetry in the ejecta distribution and abundance inhomogeneities are best explained by a strongly asymmetric SN explosion, similar to those produced in some recent 3D delayed-detonation Type Ia models.

  1. SUPERNOVA EJECTA IN THE YOUNGEST GALACTIC SUPERNOVA REMNANT G1.9+0.3

    Energy Technology Data Exchange (ETDEWEB)

    Borkowski, Kazimierz J.; Reynolds, Stephen P. [Department of Physics, North Carolina State University, Raleigh, NC 27695-8202 (United States); Hwang, Una [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Green, David A. [Cavendish Laboratory, 19 J.J. Thomson Ave., Cambridge CB3 0HE (United Kingdom); Petre, Robert [NASA/GSFC, Code 660, Greenbelt, MD 20771 (United States); Krishnamurthy, Kalyani; Willett, Rebecca, E-mail: kborkow@unity.ncsu.edu [Department of Electrical and Computer Engineering, Duke University, Durham, NC 27708 (United States)

    2013-07-01

    G1.9+0.3 is the youngest known Galactic supernova remnant (SNR), with an estimated supernova (SN) explosion date of {approx}1900, and most likely located near the Galactic center. Only the outermost ejecta layers with free-expansion velocities {approx}>18,000 km s{sup -1} have been shocked so far in this dynamically young, likely Type Ia SNR. A long (980 ks) Chandra observation in 2011 allowed spatially resolved spectroscopy of heavy-element ejecta. We denoised Chandra data with the spatio-spectral method of Krishnamurthy et al., and used a wavelet-based technique to spatially localize thermal emission produced by intermediate-mass elements (IMEs; Si and S) and iron. The spatial distribution of both IMEs and Fe is extremely asymmetric, with the strongest ejecta emission in the northern rim. Fe K{alpha} emission is particularly prominent there, and fits with thermal models indicate strongly oversolar Fe abundances. In a localized, outlying region in the northern rim, IMEs are less abundant than Fe, indicating that undiluted Fe-group elements (including {sup 56}Ni) with velocities >18,000 km s{sup -1} were ejected by this SN. However, in the inner west rim, we find Si- and S-rich ejecta without any traces of Fe, so high-velocity products of O-burning were also ejected. G1.9+0.3 appears similar to energetic Type Ia SNe such as SN 2010jn where iron-group elements at such high free-expansion velocities have been recently detected. The pronounced asymmetry in the ejecta distribution and abundance inhomogeneities are best explained by a strongly asymmetric SN explosion, similar to those produced in some recent three-dimensional delayed-detonation Type Ia models.

  2. THE MORPHOLOGY OF THE EJECTA IN SUPERNOVA 1987A: A STUDY OVER TIME AND WAVELENGTH

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, Josefin [KTH, Department of Physics, and the Oskar Klein Centre, AlbaNova, SE-106 91 Stockholm (Sweden); Fransson, Claes; Lundqvist, Peter; Sollerman, Jesper [Department of Astronomy and the Oskar Klein Centre, Stockholm University, AlbaNova, SE-106 91 Stockholm (Sweden); Kjaer, Karina; Leibundgut, Bruno; Spyromilio, Jason [ESO, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany); Jerkstrand, Anders [Astrophysics Research Centre, School of Maths and Physics, Queens University Belfast, Belfast BT7 1NN (United Kingdom); Kirshner, Robert P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-78, Cambridge, MA 02138 (United States); Mattila, Seppo [Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Vaeisaelaentie 20, FI-21500 Piikkioe (Finland); McCray, Richard [JILA, University of Colorado, Boulder, CO 80309-0440 (United States); Wheeler, J. Craig [Department of Astronomy, University of Texas, Austin, TX 78712-0259 (United States)

    2013-05-01

    We present a study of the morphology of the ejecta in Supernova 1987A based on images and spectra from the Hubble Space Telescope (HST) as well as integral field spectroscopy from VLT/SINFONI. The HST observations were obtained between 1994 and 2011 and primarily probe the outer H-rich zones of the ejecta. The SINFONI observations were obtained in 2005 and 2011 and instead probe the [Si I]+[Fe II] emission from the inner regions. We find a strong temporal evolution of the morphology in the HST images, from a roughly elliptical shape before {approx}5000 days, to a more irregular, edge-brightened morphology with a ''hole'' in the middle thereafter. This transition is a natural consequence of the change in the dominant energy source powering the ejecta, from radioactive decay before {approx}5000 days to X-ray input from the circumstellar interaction thereafter. The [Si I]+[Fe II] images display a more uniform morphology, which may be due to a remaining significant contribution from radioactivity in the inner ejecta and the higher abundance of these elements in the core. Both the H{alpha} and the [Si I]+[Fe II] line profiles show that the ejecta are distributed fairly close to the plane of the inner circumstellar ring, which is assumed to define the rotational axis of the progenitor star. The H{alpha} emission extends to higher velocities than [Si I]+[Fe II], as expected from theoretical models. There is no clear symmetry axis for all the emission. Instead, we find that the emission is concentrated to clumps and that the emission is distributed somewhat closer to the ring in the north than in the south. This north-south asymmetry may be partially explained by dust absorption. We compare our results with explosion models and find some qualitative agreement, but note that the observations show a higher degree of large-scale asymmetry.

  3. Are eruptions from linear fissures and caldera ring dykes more likely to produce pyroclastic flows?

    Science.gov (United States)

    Jessop, D. E.; Gilchrist, J.; Jellinek, A. M.; Roche, O.

    2016-11-01

    Turbulent volcanic jets are produced by highly-energetic explosive eruptions and may form buoyant plumes that rise many tens of kilometres into the atmosphere to form umbrella clouds or collapse to generate ground-hugging pyroclastic flows. Ash injected into the atmosphere can be transported for many hundreds of kilometres with the potential to affect climate, disrupt global air travel and cause respiratory health problems. Pyroclastic flows, by contrast, are potentially catastrophic to populations and infrastructure close to the volcano. Key to which of these two behaviours will occur is the extent to which the mechanical entrainment and mixing of ambient air into the jet by large (entraining) eddies forming the jet edge changes the density of the air-ash mixture: low entrainment rates lead to pyroclastic flows and high entrainment rates give rise to buoyant plumes. Recent experiments on particle-laden (multi-phase) volcanic jets from flared and straight-sided circular openings suggest that the likelihood for buoyant plumes will depend strongly on the shape and internal geometry of the vent region. This newly recognised sensitivity of the fate of volcanic jets to the structure of the vent is a consequence of a complex dynamic coupling between the jet and entrained solid particles, an effect that has generally been overlooked in previous studies. Building on this work, here we use an extensive series of experiments on multi-phase turbulent jets from analogue linear fissures and annular ring fractures to explore whether the restrictive vent geometry during cataclysmic caldera-forming (CCF) eruptions will ultimately lead a relatively greater frequency of pyroclastic flows than eruptions from circular vents on stratovolcanoes. Our results, understood through scaling analyses and a one-dimensional theoretical model, show that entrainment is enhanced where particle motions contribute angular momentum to entraining eddies. However, because the size of the entraining

  4. X-RAY EJECTA KINEMATICS OF THE GALACTIC CORE-COLLAPSE SUPERNOVA REMNANT G292.0+1.8

    Energy Technology Data Exchange (ETDEWEB)

    Bhalerao, Jayant; Park, Sangwook [Department of Physics, University of Texas at Arlington, P.O. Box 19059, Arlington, TX 76019 (United States); Dewey, Daniel [MIT Kavli Institute, Cambridge, MA 02139 (United States); Hughes, John P. [Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854-8019 (United States); Mori, Koji [Department of Applied Physics, University of Miyazaki, 1-1 Gakuen Kibanadai-nishi, Miyazaki 889-2192 (Japan); Lee, Jae-Joon, E-mail: jayant.bhalerao@mavs.uta.edu [Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of)

    2015-02-10

    We report on the results from the analysis of our 114 ks Chandra High Energy Transmision Grating Spectrometer observation of the Galactic core-collapse supernova remnant G292.0+1.8. To probe the three-dimensional structure of the clumpy X-ray emitting ejecta material in this remnant, we measured Doppler shifts in emission lines from metal-rich ejecta knots projected at different radial distances from the expansion center. We estimate radial velocities of ejecta knots in the range of –2300 ≲ v{sub r}  ≲ 1400 km s{sup –1}. The distribution of ejecta knots in velocity versus projected-radius space suggests an expanding ejecta shell with a projected angular thickness of ∼90'' (corresponding to ∼3 pc at d = 6 kpc). Based on this geometrical distribution of the ejecta knots, we estimate the location of the reverse shock approximately at the distance of ∼4 pc from the center of the supernova remnant, putting it in close proximity to the outer boundary of the radio pulsar wind nebula. Based on our observed remnant dynamics and the standard explosion energy of 10{sup 51} erg, we estimate the total ejecta mass to be ≲8 M {sub ☉}, and we propose an upper limit of ≲35 M {sub ☉} on the progenitor's mass.

  5. Ejecta of Eta Carinae: What We Learn about N-Rich Chemistry

    Science.gov (United States)

    Gull, Theodore

    2006-01-01

    At least one member of the binary system, Eta Carinae, is in the late stages of CNO-cycle. At least ten solar masses of ejecta make up the Homunculus, a neutral bi-polar shell ejected in the 1840s and the Little Homunculus, an internal, ionized bi-polar shell ejected in the 1890s. HST/STIS and VLTAJVES high dispersion spectroscopy revealed absorptions of multiple elements and diatomic molecules in these shells, some, such as V II and Sr II have not been seen previously in the ISM. The skirt region between the bi-lobes includes the very bright Weigelt blobs, within 0.1 to 0.3" of the central source, and the more distant, unusual Strontium Filament, a neutral emission nebula photoexcited by Balmer continuum, but shielded by Fe II from Lyman radiation. The 600+ emission lines are due to metals usually tied up in dust, but underabundances of C and O prevent precipitation as oxides onto the dust grains. Indications are that Ti/Ni is 100X solar, likely due not to nuclear processing, but the very different photo-excitation environments coupled with N-rich, C-, O-poor chemistry. In the Homunculus, level populations of the molecules indicate 60K gas; the metal absorption lines, 760K; that of the Little Homunculus 6400K during the broad spectroscopic maximum, relaxing to 5000K for the few month long minimum. Lyman radiation, including both continuum and Lyman lines, is trapped across periastron. leading to temporary relaxation of the ejecta. These ejecta are a treasure trove of information on material thrown out of massive stars in the CNO-cycle, well before the helium burning phase. Curiously, spectra of three very recent SWIFT GRBs indicate the presence of warm, photoexcited ejecta in the vicinity of the protoGRBs, but obviously of very different abundances. However, the ejecta of Eta Carinae promise to be a nearby example of massive ejecta, the study of which should lead to increased insight of earlier, very distant massive stars.

  6. Dissecting a supernova impostor's circumstellar medium: MUSEing about the SHAPE of η Carinae's outer ejecta

    Science.gov (United States)

    Mehner, A.; Steffen, W.; Groh, J. H.; Vogt, F. P. A.; Baade, D.; Boffin, H. M. J.; Davidson, K.; de Wit, W. J.; Humphreys, R. M.; Martayan, C.; Oudmaijer, R. D.; Rivinius, T.; Selman, F.

    2016-11-01

    Aims: The role of episodic mass loss is one of the outstanding questions in massive star evolution. The structural inhomogeneities and kinematics of their nebulae are tracers of their mass-loss history. We conduct a three-dimensional morpho-kinematic analysis of the ejecta of η Car outside its famous Homunculus nebula. Methods: We carried out the first large-scale integral field unit observations of η Car in the optical, covering a field of view of 1'× 1' centered on the star. Observations with the Multi Unit Spectroscopic Explorer (MUSE) at the Very Large Telescope (VLT) reveal the detailed three-dimensional structure of η Car's outer ejecta. Morpho-kinematic modeling of these ejecta is conducted with the code SHAPE. Results: The largest coherent structure in η Car's outer ejecta can be described as a bent cylinder with roughly the same symmetry axis as the Homunculus nebula. This large outer shell is interacting with the surrounding medium, creating soft X-ray emission. Doppler velocities of up to 3000 km s-1 are observed. We establish the shape and extent of the ghost shell in front of the southern Homunculus lobe and confirm that the NN condensation can best be modeled as a bowshock in the orbital/equatorial plane. Conclusions: The SHAPE modeling of the MUSE observations provides a significant gain in the study of the three-dimensional structure of η Car's outer ejecta. Our SHAPE modeling indicates that the kinematics of the outer ejecta measured with MUSE can be described by a spatially coherent structure, and that this structure also correlates with the extended soft X-ray emission associated with the outer debris field. The ghost shell immediately outside the southern Homunculus lobe hints at a sequence of eruptions within the time frame of the Great Eruption from 1837-1858 or possibly a later shock/reverse shock velocity separation. Our 3D morpho-kinematic modeling and the MUSE observations constitute an invaluable dataset to be confronted with future

  7. Asteroid Impact Deflection and Assessment (AIDA) mission - Properties of Impact Ejecta

    Science.gov (United States)

    Hamilton, Douglas P.; Fahnestock, Eugene G.; Schwartz, Stephen R.; Murdoch, Naomi; Asphaug, Erik; Cheng, Andrew F.; Housen, Kevin R.; Michel, Patrick; Miller, Paul L.; Stickle, Angela; Tancredi, Gonzalo; Vincent, Jean-Baptiste; Wuennemann, Kai; Yu, Yang; AIDA Impact Simulation Working Group

    2016-10-01

    The Asteroid Impact Deflection and Assessment (AIDA) mission is composed of NASA's Double Asteroid Redirection Test (DART) mission and ESA's Asteroid Impact Monitor (AIM) rendezvous mission. The DART spacecraft is designed to impact the small satellite of near-Earth asteroid 65803 Didymos in October 2022, while the in-situ AIM spacecraft observes. AIDA's Modeling and Simulation of Impact Outcomes Working Group is tasked with investigating properties of the debris ejected from the impact. The orbital evolution of this ejecta has important implications for observations that the AIM spacecraft will take as well as for the safety of the spacecraft itself. Ejecta properties including particle sizes, bulk densities, and velocities all depend on the poorly-known physical properties of Didymos' moon. The moon's density, internal strength, and especially its porosity have a strong effect on all ejecta properties. Making a range of assumptions, we perform a suite of numerical simulations to determine the fate of the ejected material; we will use simulation predictions to optimize AIM observations and safety. Ultimately, combining AIM's observations of the ejecta with detailed numerical simulations will help constrain key satellite parameters.We use distinct types of numerical tools to explore ejecta properties based on additional target parameters (different forms of friction, cohesion), e.g., the shock physics code iSALE, smoothed particle hydrodynamics codes, and the granular code PKDGRAV. Given the large discrepancy between the 6 km/s impact speed of DART and the moon's 6 cm/s escape speed, a great challenge will be to determine properties of the low-speed ejecta. Very low-speed material relevant to the safety of the AIM spacecraft and its ability to conduct its observations may loft from the crater at late stages of the impact process, or from other locations far from the impact site due to seismic energy propagation. The manner in which seismic waves manifests in

  8. Impact ejecta-induced melting of surface ice deposits on Mars

    Science.gov (United States)

    Weiss, David K.; Head, James W.

    2016-12-01

    Fluvial features present around impact craters on Mars can offer insight into the ancient martian climate and its relationship to the impact cratering process. The widespread spatial and temporal distribution of surface ice on Mars suggests that the interaction between impact cratering and surface ice could have been a relatively frequent occurrence. We explore the thermal and melting effects on regional surface ice sheets in this case, where an impact event occurs in regional surface ice deposits overlying a regolith/bedrock target. We provide an estimate for the post-impact temperature of martian ejecta as a function of crater diameter, and conduct thermal modeling to assess the degree to which contact melting of hot ejecta superposed on surface ice deposits can produce meltwater and carve fluvial features. We also evaluate whether fluvial features could form as a result of basal melting of the ice deposits in response to the thermal insulation provided by the overlying impact ejecta. Contact melting is predicted to occur immediately following ejecta emplacement over the course of hundreds of years to tens of kyr. Basal melting initiates when the 273 K isotherm rises through the crust and reaches the base of the ice sheet ∼0.1 to ∼1 Myr following the impact. We assess the range of crater diameters predicted to produce contact and basal melting of surface ice sheets, as well as the melt fluxes, volumes, timescales, predicted locations of melting (relative to the crater), and the associated hydraulic and hydrologic consequences. We find that the heat flux and surface temperature conditions required to produce contact melting are met throughout martian history, whereas the heat flux and surface temperature conditions to produce basal melting are met only under currently understood ancient martian thermal conditions. For an impact into a regional ice sheet, the contact and basal melting mechanisms are predicted to generate melt volumes between ∼10-1 and 105 km3

  9. Asymmetric High-Velocity Ejecta in the Youngest Galactic SNR G1.9+0.3

    Science.gov (United States)

    Borkowski, Kazimierz

    2014-11-01

    Chandra has revealed highly asymmetric supernova ejecta in G1.9+0.3. Iron dominates thermal emission in the radio-bright northern rim, while only intermediate-mass elements are found along the SE-NW axis. The measured X-ray expansion rates decrease radially by about 60% along this axis from 0.84% yr^{-1) to 0.52% yr^{-1}. This corresponds to undecelerated ages of 120 - 190 yr, confirming the young age of G1.9+0.3, and implying that the blast wave is much more decelerated than the reverse shock. Only the outermost ejecta with very high (>18,000 km s^{-1}) free-expansion velocities have been shocked so far. We discuss G1.9+0.3 in the framework of recent asymmetric 3D delayed-detonation Type Ia explosions from Seitenzahl et al. (2013). Their N3 model provides the best match.

  10. Synthetic line and continuum linear-polarisation signatures of axisymmetric type II supernova ejecta

    CERN Document Server

    Dessart, Luc

    2011-01-01

    We present synthetic single-line and continuum linear-polarisation signatures due to electron scattering in axially-symmetric Type II supernovae (SNe) which we calculate using a Monte Carlo and a long-characteristic radiative-transfer code. Aspherical ejecta are produced by prescribing a latitudinal scaling or stretching of SN ejecta inputs obtained from 1-D non-LTE time-dependent calculations. We study polarisation signatures as a function of inclination, shape factor, wavelength, line identity, post-explosion time. At early times, cancellation and optical-depth effects make the polarisation intrinsically low, causing complicated sign reversals with inclination or continuum wavelength, and across line profiles. While the line polarisation is positive (negative) for an oblate (prolate) morphology at the peak and in the red wing, the continuum polarisation may be of any sign. These complex polarisation variations are produced not just by the asymmetric distribution of scatterers but also of the flux. Our early...

  11. Geologic Mapping of Bakhuysen Crater, Mars: Analogies to the Ries Impact Ejecta with Insights into Martian Impact Melt

    Science.gov (United States)

    Caudill, C. M.; Osinski, G. R.; Tornabene, L. L.

    2016-08-01

    In this study, we report the mapping and geologic interpretation of 150-km diameter Bakhuysen Crater, Mars, which supports previous work suggesting similar mechanisms of multi-unit ejecta emplacement on other comparable rocky bodies.

  12. Properties of Ejecta Generated at High-Velocity Perforation of Thin Bumpers made from Different Constructional Materials

    Science.gov (United States)

    Myagkov, N. N.; Shumikhin, T. A.; Bezrukov, L. N.

    2013-08-01

    The series of impact experiments were performed to study the properties of ejecta generated at high-velocity perforation of thin bumpers. The bumpers were aluminum plates, fiber-glass plastic plates, and meshes weaved of steel wire. The projectiles were 6.35 mm diameter aluminum spheres. The impact velocities ranged from 1.95 to 3.52 km/s. In the experiments the ejecta particles were captured with low-density foam collectors or registered with the use of aluminum foils. The processing of the experimental results allowed us to estimate the total masses, spatial and size distributions, and perforating abilities of the ejecta produced from these different bumpers. As applied to the problem of reducing the near-Earth space pollution caused by the ejecta, the results obtained argue against the use of aluminum plates as first (outer) bumper in spacecraft shield protection.

  13. Experimental hypervelocity impact into quartz sand - Distribution and shock metamorphism of ejecta

    Science.gov (United States)

    Stoeffler, D.; Gault, D. E.; Wedekind, J.; Polkowski, G.

    1975-01-01

    Results are presented for vertical impacts of 0.3-g cylindrical plastic projectiles into noncohesive quartz sand in which vertical and horizontal reference strate were employed by using layers of colored sand. The impacts were performed at velocities of 5.9-6.9 km/sec with a vertical gun ballistic range. The craters, 30-33 cm in diameter, reveal a radial decay of the ejecta mass per unit area with a power of -2.8 to -3.5. Material displaced from the upper 15% of the crater depth d is represented within the whole ejecta blanked, material from deeper than 28% of d is deposited inside 2 crater radii, and no material from deeper than 33% of d was ejected beyond the crater rim. Shock-metamorphosed particles (glassy agglutinates, cataclastic breccias, and comminuted quartz) amount to some 4% of the total displaced mass and indicate progressive zones of decay of shock intensity from a peak pressure of 300 kbar. The shock-metamorphosed particles and the shock-induced change in the grain size distribution of ejected samples have close analogies to the basic characteristics of the lunar regolith. Possible applications to regolith formation and to ejecta formations of large-scale impact craters are discussed.

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

    Science.gov (United States)

    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.

  15. SULFUR MOLECULE CHEMISTRY IN SUPERNOVA EJECTA RECORDED BY SILICON CARBIDE STARDUST

    Energy Technology Data Exchange (ETDEWEB)

    Hoppe, Peter [Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, 55128 Mainz (Germany); Fujiya, Wataru [Department of Earth and Planetary Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Zinner, Ernst, E-mail: peter.hoppe@mpic.de, E-mail: fujiya@eps.s.u-tokyo.ac.jp, E-mail: ekz@wustl.edu [Laboratory for Space Sciences and Physics Department, Campus Box 1105, Washington University, St. Louis, MO 63130 (United States)

    2012-02-15

    We studied about 3400 presolar silicon carbide (SiC) grains from the Murchison CM2 meteorite for C- and Si-isotopic compositions. Among these grains we identified 7 unusual or type C SiC (U/C) grains, characterized by isotopically heavy Si, and 36 supernova type X SiC grains, characterized by isotopically light Si. Selected U/C and X grains were also measured for S-, Mg-Al-, and Ca-Ti-isotopic compositions. We show that the U/C grains incorporated radioactive {sup 44}Ti, which is evidence that they formed in the ejecta of Type II supernova (SNII) explosions. Abundances of radioactive {sup 26}Al and {sup 44}Ti are compatible with those observed in X grains. U/C and X grains carry light S with enrichments in {sup 32}S of up to a factor of 2.7. The combination of heavy Si and light S observed in U/C grains is not consistent with abundance predictions of simple supernova models. The isotope data suggest preferential trapping of S from the innermost supernova zones, the production site of radioactive {sup 44}Ti, by the growing silicon carbide particles. A way to achieve this is by sulfur molecule chemistry in the still unmixed ejecta. This confirms model predictions of molecule formation in SNII ejecta and shows that sulfur molecule chemistry operates in the harsh and hot environments of stellar explosions.

  16. Gravitational waves and mass ejecta from binary neutron star mergers: Effect of the mass-ratio

    CERN Document Server

    Dietrich, Tim; Tichy, Wolfgang; Bernuzzi, Sebastiano; Bruegmann, Bernd

    2016-01-01

    We present new (3+1)D numerical relativity simulations of the binary neutron star (BNS) merger and postmerger phase. We focus on a previously inaccessible region of the binary parameter space spanning the binary's mass-ratio $q\\sim1.00-1.75$ for different total masses and equations of state, and up to $q\\sim2$ for a stiff BNS system. We study the mass-ratio effect on the gravitational waves (GWs) and on the possible electromagnetic emission associated to dynamical mass ejecta. We compute waveforms, spectra, and spectrograms of the GW strain including all the multipoles up to $l=4$. The mass-ratio has a specific imprint on the GW multipoles in the late-inspiral-merger signal, and it affects qualitatively the spectra of the merger remnant. The multipole effect is also studied by considering the dependency of the GW spectrograms on the source's sky location. Unequal mass BNSs produce more ejecta than equal mass systems with ejecta masses and kinetic energies depending almost linearly on $q$. We estimate luminosi...

  17. Modeling post-explosion anisotropies of ejecta in SNR Cassiopeia A

    Science.gov (United States)

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

    2016-06-01

    Supernova remnats (SNRs) show a complex morphology characterized by an inhomogeneous spatial distribution of ejecta, believed to reflect pristine structures and features of the progenitor supernova (SN) explosion. Filling the gap between SN explosions and their remnants is very important for a comprehension of the origin of present-day structure of ejecta in SNRs and to probe and constraint current models of SN explosions. The SNR Cassiopeia A (Cas A) is an attractive laboratory for studying the SNe-SNRs connection, being one of the best studied SNRs for which its 3D structure is known. We present a three-dimensional hydrodynamic model describing the evolution of Cas A from the immediate aftermath of the SN explosion to its expansion through the interstellar medium, taking into account the distribution of element abundances of the ejecta, the back reaction of accelerated cosmic rays at the shock front, and the deviations from equilibrium of ionizazion for the most important elements. We use the model to derive the physical parameters characterizing the SN explosion and reproducing the today morphology of Cas A.

  18. The Density and Mass of Unshocked Ejecta in Cassiopeia A through Low Frequency Radio Absorption

    CERN Document Server

    DeLaney, Tracey; Rudnick, Lawrence; Perley, R A

    2014-01-01

    Characterizing the ejecta in young supernova remnants is a requisite step towards a better understanding of stellar evolution. In Cassiopeia A the density and total mass remaining in the unshocked ejecta are important parameters for modeling its explosion and subsequent evolution. Low frequency (<100 MHz) radio observations of sufficient angular resolution offer a unique probe of unshocked ejecta revealed via free-free absorption against the synchrotron emitting shell. We have used the Very Large Array plus Pie Town Link extension to probe this cool, ionized absorber at 9 arcseconds and 18.5 arcseconds resolution at 74 MHz. Together with higher frequency data we estimate an electron density of 4.2 electrons per cubic centimeters and a total mass of 0.39 Solar masses with uncertainties of a factor of about 2. This is a significant improvement over the 100 electrons per cubic centimeter upper limit offered by infrared [S III] line ratios from the Spitzer Space Telescope. Our estimates are sensitive to a numb...

  19. Supernova Ejecta in the Youngest Galactic Supernova Remnant G1.9+0.3

    CERN Document Server

    Borkowski, K J; Hwang, U; Green, D A; Petre, R; Krishnamurthy, K; Willett, R

    2013-01-01

    G1.9+0.3 is the youngest known Galactic supernova remnant (SNR), with an estimated supernova (SN) explosion date of about 1900, and most likely located near the Galactic Center. Only the outermost ejecta layers with free-expansion velocities larger than about 18,000 km/s have been shocked so far in this dynamically young, likely Type Ia SNR. A long (980 ks) Chandra observation in 2011 allowed spatially-resolved spectroscopy of heavy-element ejecta. We denoised Chandra data with the spatio-spectral method of Krishnamurthy et al., and used a wavelet-based technique to spatially localize thermal emission produced by intermediate-mass elements (IMEs: Si and S) and iron. The spatial distribution of both IMEs and Fe is extremely asymmetric, with the strongest ejecta emission in the northern rim. Fe Kalpha emission is particularly prominent there, and fits with thermal models indicate strongly oversolar Fe abundances. In a localized, outlying region in the northern rim, IMEs are less abundant than Fe, indicating tha...

  20. Freely Expanding X-ray Ejecta Knots in Kepler's Supernova Remnant

    Science.gov (United States)

    Hughes, John Patrick; Sato, Toshiki

    2017-08-01

    Using archival data from the Chandra X-ray Observatory, we measure the proper motions and radial velocities of compact X-ray bright knots in Kepler's supernova remnant (SNR). The high speed ejecta knots are morphologically and kinematically distinct from the rest of the ejecta and appear only in specific, limited locations. The highest speed knots show both large proper motions and high radial velocities with estimated space velocities of 10,000 km/s, similar to the typical Si velocity seen in Type Ia supernovae near maximum light. The proper motions of five knots extrapolate back over the age of the remnant to a consistent central position, defining a kinematic center for Kepler's SNR. Our new explosion center agrees well with previous determinations, but suffers less from systematic uncertainty. These five knots are expanding at close to the free expansion rate (expansion indices of 0.75 speeds and expansion indices consistent with decelerated ejecta knots. The differences in the expansion rates are likely a function of differences in the ambient medium density surrounding Kepler’s SNR.

  1. The interaction of core-collapse supernova ejecta with a companion star

    CERN Document Server

    Liu, Zheng-Wei; Roepke, Friedrich K; Moriya, Takashi J; Kruckow, Matthias; Stancliffe, Richard J; Izzard, Robert G

    2015-01-01

    The progenitors of many CCSNe are expected to be in binary systems. After the SN explosion, the companion may suffer from mass stripping and be shock heated as a result of the impact of the SN ejecta. If the binary system is disrupted, the companion is ejected as a runaway or hypervelocity star. By performing a series of 3D hydrodynamical simulations of the collision of SN ejecta with the companion star, we investigate how CCSN explosions affect their companions. We use the BEC code to construct the detailed companion structure at the time of SN explosion. The impact of the SN blast wave on the companion is followed by means of 3D SPH simulations using the Stellar GADGET code. For main-sequence (MS) companions, we find that the amount of removed mass, impact velocity, and chemical contamination of the companion that results from the impact of the SN ejecta, strongly increases with decreasing binary separation and increasing explosion energy. Their relationship can be approximately fitted by power laws, which ...

  2. The Contribution of Chemical Abundances in Nova Ejecta to the Interstellar Medium

    CERN Document Server

    Li, Fanger; Lu, Guoliang; Wang, Zhaojun

    2016-01-01

    According to the nova model from \\citet{Yaron2005} and \\citet{Jose1998} and using Monte Carlo simulation method, we investigate the contribution of chemical abundances in nova ejecta to the interstellar medium (ISM) of the Galaxy. We find that the ejected mass by classical novae (CNe) is about $2.7\\times10^{-3}$ $ \\rm M_\\odot\\ {\\rm yr^{-1}}$. In the nova ejecta, the isotopic ratios of C, N and O, that is, $^{13}$C/$^{12}$C, $^{15}$N/$^{14}$N and $^{17}$O/$^{16}$O, are higher about one order of magnitude than those in red giants. We estimate that about 10$\\%$, 5$\\%$ and 20$\\%$ of $^{13}$C, $^{15}$N and $^{17}$O in the ISM of the Galaxy come from nova ejecta, respectively. However, the chemical abundances of C, N and O calculated by our model can not cover all of observational values. This means that there is still a long way to go for understanding novae.

  3. Survival of organic compounds in ejecta from hypervelocity impacts on ice

    Science.gov (United States)

    Bowden, S. A.; Parnell, J.; Burchell, M. J.

    2009-01-01

    Hypervelocity impacts (HVIs) where organic-bearing ice constitutes the target material are important in several aspects of planetary and space science: (1) sampling of planetary surfaces using a hypervelocity projectile to impact the surface and eject surface materials for measurement or collection by a spacecraft; (2) the transfer of organic material between planetary bodies; and (3) providing energy for chemical processes involving surface materials. While small organic molecules (~6 carbon atoms), if present in surface materials, will likely be present in HVI-ejecta, uncertainty remains for larger organic molecules. It is the larger molecular weight compounds which could constitute direct evidence of life, and thus their survival within an HVI-ejecta plume is of key importance when evaluating strategies for life detection on icy bodies. It is not currently known what large organic molecules, and in what concentrations, may be present on icy bodies in the Solar System, but it is highly likely some will be more chemically stable during a HVI than others. Accordingly, in this study we examined a range of chemicals (β,β carotene, stearic acid and anthracene) with molecular weights between 178 and 536 daltons, and three different types of chemical structure. The compounds were solvated in a dimethylsulfoxide/water mixture and frozen. The frozen targets were impacted with steel spheres 1 and 1.5 mm in diameter at velocities of about 4.9 km s-1. Ice ejected during the impact was collected and underwent chemical analysis. The most labile compound (β,β carotene) was only detected (in small amounts) in the ejecta (and only that emitted at the lowest angles of ejection), although the other compounds were present in larger quantities and at a range of ejection angles. A concentration gradient was observed within the ejecta as a function of angle of ejection. This was not the same for both stearic acid and anthracene: the greatest concentrations of stearic acid were

  4. Flow Transformation in Pyroclastic Density Currents: Entrainment and Granular Dynamics during the 2006 eruption of Tungurahua

    Science.gov (United States)

    Dufek, J.; Benage, M. C.; Geist, D.; Harpp, K. S.

    2013-12-01

    Pyroclastic density currents are ground hugging flows composed of hot gases, fragments of juvenile magmatic material, and entrained clasts from the conduit or the edifice over which the flows have traveled. The interior of these flows are opaque to observation due to their large ash content, but recent investigations have highlighted that there are likely strong gradients in particle concentration and segregation of particle sizes in these particle-laden gravity currents. Pyroclastic density currents refer to a broad range of phenomena from dense flows in which the dynamics are dominated by frictional interaction between particles (dense granular flows), to gas fluidized flows, to dilute flows dominated by particle-gas turbulent interaction. However, abrupt flow transformation (e.g. from dense to dilute pyroclastic density currents) can arise due to energy exchange across multiple length scales and phases, and understanding these flow transformations is important in delineating the entrainment and erosion history of these flows, interpretations of their deposits, and in better understanding the hazards they present. During the 2006 eruption of Tungurahua, Ecuador numerous, dense pyroclastic density currents descended the volcano as result of boiling-over or low column collapse eruptions. The deposits of these flows typically have pronounced snouts and levees, and are often dominated by large, clasts (meter scale in some locations). There is an exceptional observational record of these flows and their deposits, permitting detailed field constraints of their dynamics. A particularly interesting set of flows occurred on Aug. 17, 2006 during the paroxysmal phase of the eruption that descended the slope of the volcano, filled in the river channel of the Chambo river, removing much of the larger clasts from the flow, and resulting in a dilute ';surge' that transported finer material across the channel and uphill forming dune features on the opposite bank of the river. We

  5. Numerical simulation on mixing process of ejecta and gas%微喷颗粒与气体混合过程的数值模拟研究

    Institute of Scientific and Technical Information of China (English)

    王裴; 孙海权; 邵建立; 秦承森; 李欣竹

    2012-01-01

    Ejecta mixing takes place at the interface between metal and gas under shock loading, i.e., the transport process of ejecta from metal surface appears in the gas. In this paper, adopting disperse particles instead of the initial ejecta, we simulate the ejection mixing process according to two-phase flow of gas and particle. We give the numerical results of the evolution process of the mixing, and analyze the effects of initial gas pressure and particle size on the mixing zone. The pneumatic break is observed from the numerical simulations, which can lead to evident reduction of the particle and then become an important factor affecting the evolution of mixture; also, our simulations are consistent with the corresponding measurements, showing that the gas and particle two-phase flow model is an effective method to simulate the ejection mixing.%冲击波作用下金属与气体界面将发生微喷混合现象,即金属表面产生的微喷射物质在气体中的输运过程.提出采用散体颗粒分布代替微喷初始状态,基于气体一颗粒两相流模型对微喷混合现象进行了模拟研究.数值模拟给出了微喷混合的动力学演化过程,分析了初始气体压力和颗粒尺寸因素对混合层的影响规律;在数值模拟中发现了微喷颗粒的气动破碎现象,这可导致颗粒尺度明显减小,成为影响微喷混合演化性质的重要物理因素.本文模拟结果与相关实验结果取得一致,初步表明,气粒两相流模型是模拟微喷混合过程的一种有效方法.

  6. Probing Supernova Ejecta Dust with Stellar Lightbulbs: MID-IR Imaging of G54.1+0.3

    Science.gov (United States)

    Borkowski, Kazimierz

    2015-10-01

    Stellar explosions govern the interstellar dust lifecycle. In the early Universe, supernovae (SN) injected the first heavy elements into the interstellar medium (ISM). A significant fraction of ejecta was dust, but most of it might have been destroyed in supernova remnant's (SNR) reverse shocks. Our current understanding of both formation of dust in SNe and destruction of dust in shock waves is poor. We propose to observe young SNR G54.1+0.3 with the SOFIA telescope in order to advance our knowledge of dust formation in SNe. Progenitor of SN that produced G54.1+0.3 exploded in a stellar cluster containing a number of hot O and B stars. These stars heat ejecta dust to high temperatures, providing us with a unique opportunity to study its properties prior to arrival of a reverse shock and to shed light on formation of dust in SNe. Ejecta dust heated by the stellar ultraviolet radiation in the vicinity of hot stars emits most efficiently in the infrared spectral window accessible only to SOFIA. The proposed observations will provide spectral and spatial information crucial for understanding of ejecta dust properties such as its temperature, composition, and spatial distribution. We propose to do multi-band imaging observations with FORCAST in four filters to learn about spectral and spatial distribution of ejecta dust in the vicinity of hot stars. The high spatial resolution of SOFIA is crucial to our investigation, and only SOFIA can observe this dust at wavelengths where it emits radiation most efficiently. High-spatial resolution FORCAST images obtained in this investigation will be interpreted in the framework of radiatively-heated ejecta dust. When combined with Spitzer IRAC and MIPS images, and Herschel PACS images, we expect a dramatic advance in understanding of properties of ejecta dust that has not yet been processed by SNR shocks.

  7. The LCROSS Ejecta Plume Revealed: First Characterization from Earth-based Imaging

    Science.gov (United States)

    Miller, C.; Chanover, N.; Hermalyn, B.; Strycker, P. D.; Hamilton, R. T.; Suggs, R. M.

    2012-12-01

    On October 9, 2009, the Lunar Crater Observation and Sensing Satellite (LCROSS) struck the floor of Cabeus crater. We observed the LCROSS impact site at 0.5-second intervals throughout the time of impact in the V-band (491 to 591 nm) using the Agile camera on the 3.5 m telescope at the Apache Point Observatory. Our initial analysis of these images showed that the ejecta plume could be no brighter than 9.5 magnitudes/arcsec^2. (Chanover et al. 2011, JGR). We subsequently applied a Principal Component Analysis (PCA) technique to filter out time-varying seeing distortions and image registration errors from an 8-minute sequence of images centered on the LCROSS impact time and unambiguously detected the evolving plume below the noise threshold. This is the first and only reported image detection of the LCROSS plume from ground-based instruments. Our detection is consistent with an ejecta plume that reaches peak brightness between 12 and 20 seconds after impact and fades to an undetectable level within 90 seconds after impact. This is consistent with in situ observations made by the LCROSS Shepherding Satellite (LCROSS S/SC) and the Lunar Reconnaissance Orbiter (LRO) that observed the impact from above (Colaprete et al., and Hayne et. al., 2010, Science). To test our detection method, we compared the brightness profiles derived from our impact image sequence to those extracted from a sequence with a simulated ejecta pattern. We performed 3-D ballistic simulations of trial impacts, starting with initial particle ejection angles and velocities derived from laboratory measurements made with the NASA Ames Vertical Gun of impacts of hollow test projectiles (Hermalyn et. al., 2012, Icarus). We extracted images from these simulations at 0.5-second intervals, combined them with a computer generated lunar landscape, and introduced image distortions due to time-varying seeing conditions and instrumental noise sources to produce a synthetic ejecta image sequence. We then re

  8. Radar scattering mechanisms within the meteor crater ejecta blanket: Geologic implications and relevance to Venus

    Science.gov (United States)

    Garvin, J. B.; Campbell, B. A.; Zisk, S. H.; Schaber, Gerald G.; Evans, C.

    1989-01-01

    Simple impact craters are known to occur on all of the terrestrial planets and the morphologic expression of their ejecta blankets is a reliable indicator of their relative ages on the Moon, Mars, Mercury, and most recently for Venus. It will be crucial for the interpretation of the geology of Venus to develop a reliable means of distinguishing smaller impact landforms from volcanic collapse and explosion craters, and further to use the observed SAR characteristics of crater ejecta blankets (CEB) as a means of relative age estimation. With these concepts in mind, a study was initiated of the quantitative SAR textural characteristics of the ejecta blanket preserved at Meteor Crater, Arizona, the well studied 1.2 km diameter simple crater that formed approx. 49,000 years ago from the impact of an octahedrite bolide. While Meteor Crater was formed as the result of an impact into wind and water lain sediments and has undergone recognizable water and wind related erosion, it nonetheless represents the only well studied simple impact crater on Earth with a reasonably preserved CEB. Whether the scattering behavior of the CEB can provide an independent perspective on its preservation state and style of erosion is explored. Finally, airborne laser altimeter profiles of the microtopography of the Meteor Crater CEB were used to further quantify the subradar pizel scale topographic slopes and RMS height variations for comparisons with the scattering mechanisms computed from SAR polarimetry. A preliminary assessment was summarized of the L-band radar scattering mechanisms within the Meteor Crater CEB as derived from a NASA/JPL DC-8 SAR Polarimetry dataset acquired in 1988, and the dominant scattering behavior was compared with microtopographic data (laser altimeter profiles and 1:10,000 scale topographic maps).

  9. Geologic Mapping of Ejecta Deposits in Oppia Quadrangle, Asteroid (4) Vesta

    Science.gov (United States)

    Garry, W. Brent; Williams, David A.; Yingst, R. Aileen; Mest, Scott C.; Buczkowski, Debra L.; Tosi, Federico; Schafer, Michael; LeCorre, Lucille; Reddy, Vishnu; Jaumann, Ralf; Pieters, Carle M.; Russell, Christopher T.; Raymond, Carol A.

    2014-01-01

    Oppia Quadrangle Av-10 (288-360 deg E, +/- 22 deg) is a junction of key geologic features that preserve a rough history of Asteroid (4) Vesta and serves as a case study of using geologic mapping to define a relative geologic timescale. Clear filter images, stereo-derived topography, slope maps, and multispectral color-ratio images from the Framing Camera on NASA's Dawn spacecraft served as basemaps to create a geologic map and investigate the spatial and temporal relationships of the local stratigraphy. Geologic mapping reveals the oldest map unit within Av-10 is the cratered highlands terrain which possibly represents original crustal material on Vesta that was then excavated by one or more impacts to form the basin Feralia Planitia. Saturnalia Fossae and Divalia Fossae ridge and trough terrains intersect the wall of Feralia Planitia indicating that this impact basin is older than both the Veneneia and Rheasilvia impact structures, representing Pre-Veneneian crustal material. Two of the youngest geologic features in Av-10 are Lepida (approximately 45 km diameter) and Oppia (approximately 40 km diameter) impact craters that formed on the northern and southern wall of Feralia Planitia and each cross-cuts a trough terrain. The ejecta blanket of Oppia is mapped as 'dark mantle' material because it appears dark orange in the Framing Camera 'Clementine-type' colorratio image and has a diffuse, gradational contact distributed to the south across the rim of Rheasilvia. Mapping of surface material that appears light orange in color in the Framing Camera 'Clementine-type' color-ratio image as 'light mantle material' supports previous interpretations of an impact ejecta origin. Some light mantle deposits are easily traced to nearby source craters, but other deposits may represent distal ejecta deposits (emplaced greater than 5 crater radii away) in a microgravity environment.

  10. Gravitational waves and mass ejecta from binary neutron star mergers: Effect of the mass ratio

    Science.gov (United States)

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

    2017-01-01

    We present new (3 +1 )D numerical relativity simulations of the binary neutron star (BNS) merger and postmerger phase. We focus on a previously inaccessible region of the binary parameter space spanning the binary's mass ratio q ˜1.00 - 1.75 for different total masses and equations of state, and up to q ˜2 for a stiff BNS system. We study the mass ratio effect on the gravitational waves (GWs) and on the possible electromagnetic (EM) emission associated with dynamical mass ejecta. We compute waveforms, spectra, and spectrograms of the GW strain including all the multipoles up to l =4 . The mass ratio has a specific imprint on the GW multipoles in the late-inspiral-merger signal, and it affects qualitatively the spectra of the merger remnant. The multipole effect is also studied by considering the dependency of the GW spectrograms on the source's sky location. Unequal mass BNSs produce more ejecta than equal mass systems with ejecta masses and kinetic energies depending almost linearly on q . We estimate luminosity peaks and light curves of macronova events associated with the mergers using a simple approach. For q ˜2 the luminosity peak is delayed for several days and can be up to 4 times larger than for the q =1 cases. The macronova emission associated with the q ˜2 BNS is more persistent in time and could be observed for weeks instead of a few days (q =1 ) in the near infrared. Finally, we estimate the flux of possible radio flares produced by the interaction of relativistic outflows with the surrounding medium. Also in this case a large q can significantly enhance the emission and delay the peak luminosity. Overall, our results indicate that the BNS merger with a large mass ratio has EM signatures distinct from the equal mass case and more similar to black hole-neutron star binaries.

  11. Properties of Neutrino-driven Ejecta from the Remnant of a Binary Neutron Star Merger: Pure Radiation Hydrodynamics Case

    Science.gov (United States)

    Fujibayashi, Sho; Sekiguchi, Yuichiro; Kiuchi, Kenta; Shibata, Masaru

    2017-09-01

    We performed general relativistic, long-term, axisymmetric neutrino radiation hydrodynamics simulations for the remnant formed after a binary neutron star merger, which consists of a massive neutron star and a torus surrounding it. As an initial condition, we employ the result derived in a three-dimensional, numerical relativity simulation for the binary neutron star merger. We investigate the properties of neutrino-driven ejecta. Due to the pair-annihilation heating, the dynamics of the neutrino-driven ejecta are significantly modified. The kinetic energy of the ejecta is about two times larger than that in the absence of pair-annihilation heating. This suggests that the pair-annihilation heating plays an important role in the evolution of merger remnants. The relativistic outflow, which is required for driving gamma-ray bursts, is not observed because the specific heating rate around the rotational axis is not sufficiently high, due to the baryon loading caused by the neutrino-driven ejecta from the massive neutron star. We discuss the condition for launching the relativistic outflow and the nucleosynthesis in the ejecta.

  12. Suzaku study on the Ejecta of the Supernova Remnant G272.2$-$3.2

    CERN Document Server

    Kamitsukasa, Fumiyoshi; Nakajima, Hiroshi; Hayashida, Kiyoshi; Mori, Koji; Katsuda, Satoru; Uchida, Hiroyuki; Tsunemi, Hiroshi

    2015-01-01

    We report re-analyses of the Suzaku observations of the Galactic supernova remnant (SNR), G272.2$-$3.2, for which the previous studies were limited below 3 keV. With careful data reduction and background subtraction, we discover the K-shell lines of Ar, Ca, and Fe above 3 keV. The X-ray spectrum of G272.2$-$3.2 consists of two components, a low-temperature collisional ionization equilibrium (CIE) plasma ($kT_{\\rm e} \\sim 0.2$ keV) and a high-temperature non-equilibrium ionization (NEI) plasma ($kT_{\\rm e} = 0.6$-$3$ keV). The CIE plasma has solar abundances over the entire area, hence it would originate from the interstellar medium. On the other hand, the abundances of the NEI plasma increase toward the inner region, suggesting the ejecta origin. The line center energy of the Fe K-shell emission ($\\sim 6.4$ keV) suggests that the ejecta are recently heated by the reverse shock, a common feature in Type Ia SNRs.

  13. The effect of ambient pressure on ejecta sheets from free-surface ablation

    KAUST Repository

    Marston, J. O.

    2016-04-16

    We present observations from an experimental study of the ablation of a free liquid surface promoted by a focused laser pulse, causing a rapid discharge of liquid in the form of a very thin conical-shaped sheet. In order to capture the dynamics, we employ a state-of-the-art ultra-high-speed video camera capable of capturing events at (Formula presented.) fps with shutter speeds down to 20 ns, whereby we were able to capture not only the ejecta sheet, but also the shock wave, emerging at speeds of up to 1.75 km/s, which is thus found to be hypersonic (Mach 5). Experiments were performed at a range of ambient pressures in order to study the effect of air drag on the evolution of the sheet, which was always observed to dome over, even at pressures as low as 3.8 kPa. At reduced pressures, the extended sheet evolution led to the formation of interference fringe patterns from which, by comparison with the opening speed of rupture, we were able to determine the ejecta thickness. © 2016, Springer-Verlag Berlin Heidelberg.

  14. Abundance anomalies in metal-poor stars from Population III supernova ejecta hydrodynamics

    CERN Document Server

    Sluder, Alan; Safranek-Shrader, Chalence; Milosavljevic, Milos; Bromm, Volker

    2015-01-01

    We present a simulation of the long-term evolution of a Population III supernova remnant in a cosmological minihalo. Employing passive Lagrangian tracer particles, we investigate how chemical stratification and anisotropy in the explosion can affect the abundances of the first low-mass, metal-enriched stars. We find that reverse shock heating can leave the inner mass shells at entropies too high to cool, leading to carbon-enhancement in the re-collapsing gas. This hydrodynamic selection effect could explain the observed incidence of carbon-enhanced metal-poor (CEMP) stars at low metallicity. We further explore how anisotropic ejecta distributions, recently seen in direct numerical simulations of core-collapse explosions, may translate to abundances in metal-poor stars. We find that some of the observed scatter in the Population II abundance ratios can be explained by an incomplete mixing of supernova ejecta, even in the case of only one contributing enrichment event. We demonstrate that the customary hypothes...

  15. Effects of the Core-collapse Supernova Ejecta Impact on a Rapidly Rotating Massive Companion Star

    Science.gov (United States)

    Zhu, Chunhua; Lü, Guoliang; Wang, Zhaojun

    2017-02-01

    We investigate the effects of the core-collapse supernova (CCSN) ejecta on a rapidly rotating and massive companion star. We show that the stripped mass is twice as high as that of a massive but nonrotating companion star. In close binaries with orbital periods of about 1 day, the stripped masses reach up to ∼ 1 {M}ȯ . By simulating the evolutions of the rotational velocities of the massive companion stars based on different stripped masses, we find that the rotational velocity decreases greatly for a stripped mass higher than about 1 {M}ȯ . Of all the known high-mass X-ray binaries (HMXBs), Cygnus X-3 and 1WGA J0648.024418 have the shortest orbital periods, 0.2 and 1.55 days, respectively. The optical counterpart of the former is a Wolf-Rayet star, whereas it is a hot subdwarf for the latter. Applying our model to the two HMXBs, we suggest that the hydrogen-rich envelopes of their optical counterparts may have been stripped by CCSN ejecta.

  16. Relativistic ejecta from X-ray flash XRF 060218 and the rate of cosmic explosions.

    Science.gov (United States)

    Soderberg, A M; Kulkarni, S R; Nakar, E; Berger, E; Cameron, P B; Fox, D B; Frail, D; Gal-Yam, A; Sari, R; Cenko, S B; Kasliwal, M; Chevalier, R A; Piran, T; Price, P A; Schmidt, B P; Pooley, G; Moon, D-S; Penprase, B E; Ofek, E; Rau, A; Gehrels, N; Nousek, J A; Burrows, D N; Persson, S E; McCarthy, P J

    2006-08-31

    Over the past decade, long-duration gamma-ray bursts (GRBs)--including the subclass of X-ray flashes (XRFs)--have been revealed to be a rare variety of type Ibc supernova. Although all these events result from the death of massive stars, the electromagnetic luminosities of GRBs and XRFs exceed those of ordinary type Ibc supernovae by many orders of magnitude. The essential physical process that causes a dying star to produce a GRB or XRF, and not just a supernova, is still unknown. Here we report radio and X-ray observations of XRF 060218 (associated with supernova SN 2006aj), the second-nearest GRB identified until now. We show that this event is a hundred times less energetic but ten times more common than cosmological GRBs. Moreover, it is distinguished from ordinary type Ibc supernovae by the presence of 10(48) erg coupled to mildly relativistic ejecta, along with a central engine (an accretion-fed, rapidly rotating compact source) that produces X-rays for weeks after the explosion. This suggests that the production of relativistic ejecta is the key physical distinction between GRBs or XRFs and ordinary supernovae, while the nature of the central engine (black hole or magnetar) may distinguish typical bursts from low-luminosity, spherical events like XRF 060218.

  17. Shared origin for seven of Mars Trojans - impact ejecta from Mars?

    Science.gov (United States)

    Polishook, David; Jacobson, Seth A.; Aharonson, Oded

    2016-10-01

    Seven out of nine Mars Trojans belong to an orbital grouping that started to spread about 109 years ago (Cuk et al. 2015). We spectrally observed two of them (311999 and 385250) using the IRTF telescope and found that both present an identical olivine-rich reflectance spectrum, that is similar to the reflectance spectrum of (5261) Eureka, the largest of these seven Trojans (Rivkin et al. 2007). These measurements confirm the shared origin of the seven. Moreover, olivine-rich reflectance spectra is rare within asteroids, but is visible in numerous locations on Mars and is found within SNC meteorites that are argued to originate from Mars (Chassigny, ALHA77005; McSween 1985). This spectral resemblance encourages us to suggest that the seven Trojans are impact ejecta from Mars' plutonic rock. We will present dynamical calculations showing how the impact ejecta could have been caught in L5 and that there are enough size-relevant craters on Mars surface to produce these seven Trojans.

  18. Radioactivity and thermalization in the ejecta of compact object mergers and their impact on kilonova light curves

    CERN Document Server

    Barnes, Jennifer; Wu, Meng-Ru; Mart'inez-Pinedo, Gabriel

    2016-01-01

    One of the most promising electromagnetic signatures of compact object mergers are kilonovae: approximately isotropic radioactively-powered transients that peak days to weeks post-merger. Key uncertainties in modeling kilonovae include the emission profiles of the radioactive decay products---non-thermal beta- and alpha-particles, fission fragments, and gamma-rays---and the efficiency with which they deposit their energy in the ejecta. The total radioactive energy and the efficiency of its thermalization sets the luminosity budget and is therefore necessary for predicting kilonova light curves. We outline the uncertainties in r-process decay, describe the physical processes by which the energy of the decay products is absorbed in the ejecta, and present time-dependent thermalization efficiencies for each particle type. We determine the net heating efficiency and explore its dependence on r-process yields---in particular, the production of translead nuclei that undergo alpha-decay---and on the ejecta's mass, v...

  19. Characteristics of ejecta and alluvial deposits at Meteor Crater, Arizona and Odessa Craters, Texas: Results from ground penetrating radar

    Science.gov (United States)

    Grant, J. A.; Schultz, P. H.

    1991-01-01

    Previous ground penetrating radar (GRP) studies around 50,000 year old Meteor Crater revealed the potential for rapid, inexpensive, and non-destructive sub-surface investigations for deep reflectors (generally greater than 10 m). New GRP results are summarized focusing the shallow sub-surfaces (1-2 m) around Meteor Crater and the main crater at Odessa. The following subject areas are covered: (1) the thickness, distribution, and nature of the contact between surrounding alluvial deposits and distal ejecta; and (2) stratigraphic relationships between both the ejecta and alluvium derived from both pre and post crater drainages. These results support previous conclusions indicating limited vertical lowering (less than 1 m) of the distal ejecta at Meteor Crater and allow initial assessment of the gradational state if the Odessa craters.

  20. A unified model for the spectrophotometric development of classical and recurrent novae: the role of asphericity of the ejecta

    CERN Document Server

    Shore, Steven N

    2013-01-01

    There is increasing evidence that the geometry, and not only the filling factors, of nova ejecta is important in the interpretation of their spectral and photometric developments. Ensembles of spectra and light curves have provided general typographies. This Letter suggests how these can be unified.The observed spread in the maximum magnitude - rate of decline (MMRD) relation is argued to result from the range of opening angles and inclination of the ejecta, and not only to their masses and velocities. The spectroscopic classes can be similarly explained and linked to the behavior of the light curves. The secondary maximum observed in some dust forming novae is a natural consequence of the asphericity. Neither secondary ejections nor winds are needed to explain the phenomenology. The spectrophotometric development of classical novae can be understood within a single phenomenological model with bipolar, although not jet-like, mass ejecta. High resolution spectropolarimetry will be an essential analytical tool.

  1. Imprints of the ejecta-companion interaction in Type Ia supernovae: main-sequence, subgiant, and red giant companions

    Science.gov (United States)

    Boehner, P.; Plewa, T.; Langer, N.

    2017-02-01

    We study supernova ejecta-companion interactions in a sample of realistic semidetached binary systems representative of Type Ia supernova progenitor binaries in a single-degenerate scenario. We model the interaction process with the help of a high-resolution hydrodynamic code assuming cylindrical symmetry. We find that the ejecta hole has a half-opening angle of 40-50° with the density by a factor of 2-4 lower, in good agreement with the previous studies. Quantitative differences from the past results in the amounts and kinematics of the stripped companion material and levels of contamination of the companion with the ejecta material can be explained by different model assumptions and effects due to numerical diffusion. We analyse and, for the first time, provide simulation-based estimates of the amounts and of the thermal characteristics of the shock-heated material responsible for producing a prompt, soft X-ray emission. Besides the shocked ejecta material, considered in the original model by Kasen, we also account for the stripped, shock-heated envelope material of stellar companions, which we predict partially contributes to the prompt emission. The amount of the energy deposited in the envelope is comparable to the energy stored in the ejecta. The total energy budget available for the prompt emission is by a factor of about 2-4 smaller than originally predicted by Kasen. Although the shocked envelope has a higher characteristic temperature than the shocked ejecta, the temperature estimates of the shocked material are in good agreement with the Kasen's model. The hottest shocked plasma is produced in the subgiant companion case.

  2. Ejecta cloud from the AIDA space project kinetic impact on the secondary of a binary asteroid: I. mechanical environment and dynamical model

    Science.gov (United States)

    Yu, Yang; Michel, Patrick; Schwartz, Stephen R.; Naidu, Shantanu P.; Benner, Lance A. M.

    2017-01-01

    An understanding of the post-impact dynamics of ejecta clouds are crucial to the planning of a kinetic impact mission to an asteroid, and also has great implications for the history of planetary formation. The purpose of this article is to track the evolution of ejecta produced by AIDA mission, which targets for kinetic impact the secondary of near-Earth binary asteroid (65803) Didymos on 2022, and to feedback essential informations to AIDA's ongoing phase-A study. We present a detailed dynamic model for the simulation of an ejecta cloud from a binary asteroid that synthesizes all relevant forces based on a previous analysis of the mechanical environment. We apply our method to gain insight into the expected response of Didymos to the AIDA impact, including the subsequent evolution of debris and dust. The crater scaling relations from laboratory experiments are employed to approximate the distributions of ejecta mass and launching speed. The size distribution of fragments is modeled with a power law fitted from observations of real asteroid surface. A full-scale demonstration is simulated using parameters specified by the mission. We report the results of the simulation, which include the computed spread of the ejecta cloud and the recorded history of ejecta accretion and escape. The violent period of the ejecta evolution is found to be short, and is followed by a stage where the remaining ejecta is gradually cleared. Solar radiation pressure proves to be efficient in cleaning dust-size ejecta, and the simulation results after two weeks shows that large debris on polar orbits (perpendicular to the binary orbital plane) has a survival advantage over smaller ejecta and ejecta that keeps to low latitudes.

  3. Asteroid Impact Deflection and Assessment (AIDA) mission - Full-Scale Modeling and Simulation of Ejecta Evolution and Fates

    Science.gov (United States)

    Fahnestock, Eugene G.; Yu, Yang; Hamilton, Douglas P.; Schwartz, Stephen; Stickle, Angela; Miller, Paul L.; Cheng, Andy F.; Michel, Patrick; AIDA Impact Simulation Working Group

    2016-10-01

    The proposed Asteroid Impact Deflection and Assessment (AIDA) mission includes NASA's Double Asteroid Redirection Test (DART), whose impact with the secondary of near-Earth binary asteroid 65803 Didymos is expected to liberate large amounts of ejecta. We present efforts within the AIDA Impact Simulation Working Group to comprehensively simulate the behavior of this impact ejecta as it moves through and exits the system. Group members at JPL, OCA, and UMD have been working largely independently, developing their own strategies and methodologies. Ejecta initial conditions may be imported from output of hydrocode impact simulations or generated from crater scaling laws derived from point-source explosion models. We started with the latter approach, using reasonable assumptions for the secondary's density, porosity, surface cohesive strength, and vanishingly small net gravitational/rotational surface acceleration. We adopted DART's planned size, mass, closing velocity, and impact geometry for the cratering event. Using independent N-Body codes, we performed Monte Carlo integration of ejecta particles sampled over reasonable particle size ranges, and over launch locations within the crater footprint. In some cases we scaled the number of integrated particles in various size bins to the estimated number of particles consistent with a realistic size-frequency distribution. Dynamical models used for the particle integration varied, but all included full gravity potential of both primary and secondary, the solar tide, and solar radiation pressure (accounting for shadowing). We present results for the proportions of ejecta reaching ultimate fates of escape, return impact on the secondary, and transfer impact onto the primary. We also present the time history of reaching those outcomes, i.e., ejecta clearing timescales, and the size-frequency distribution of remaining ejecta at given post-impact durations. We find large numbers of particles remain in the system for several

  4. Nano particles as the primary cause for long-term sunlight suppression at high southern latitudes following the Chicxulub impact - evidence from ejecta deposits in Belize and Mexico

    DEFF Research Database (Denmark)

    Vajda, Vivi; Ocampo, Adriana; Ferrow, Embaie

    2015-01-01

    Life on Earth was sharply disrupted 66 Ma ago as an asteroid hit the sea-floor in what is today Yucatan Peninsula, Mexico. Approximately 600 km3 of sedimentary rock were vapourized, ejected into the atmosphere and subsequently deposited globally as an ejecta apron and fallout layer. Proximal ejecta...

  5. The role of ejecta in the small crater populations on the mid-sized saturnian satellites

    Science.gov (United States)

    Bierhaus, Edward B.; Dones, Luke; Alvarellos, José Luis; Zahnle, Kevin

    2012-03-01

    We find evidence, by both observation and analysis, that primary crater ejecta play an important role in the small crater (less than a few km) populations on the saturnian satellites, and more broadly, on cratered surfaces throughout the Solar System. We measure crater populations in Cassini images of Enceladus, Rhea, and Mimas, focusing on image data with scales less than 500 m/pixel. We use recent updates to crater scaling laws and their constants (Housen, K.R., Holsapple, K.A. [2011]. Icarus 211, 856-875) to estimate the amount of mass ejected in three different velocity ranges: (i) greater than escape velocity, (ii) less than escape velocity and faster than the minimum velocity required to make a secondary crater (vmin), and (iii) velocities less than vmin. Although the vast majority of mass on each satellite is ejected at speeds less than vmin, our calculations demonstrate that the differences in mass available in the other two categories should lead to observable differences in the small crater populations; the predictions are borne out by the measurements we have made to date. In particular, Rhea, Tethys, and Dione have sufficient surface gravities to retain ejecta moving fast enough to make secondary crater populations. The smaller satellites, such as Enceladus but especially Mimas, are expected to have little or no traditional secondary populations because their escape velocities are near the threshold velocity necessary to make a secondary crater. Our work clarifies why the Galilean satellites have extensive secondary crater populations relative to the saturnian satellites. The presence, extent, and sizes of sesquinary craters (craters formed by ejecta that escape into temporary orbits around Saturn before re-impacting the surface, see Dobrovolskis, A.R., Lissauer, J.J. [2004]. Icarus 169, 462-473; Alvarellos, J.L., Zahnle, K.J., Dobrovolskis, A.R., Hamill, P. [2005]. Icarus 178, 104-123; Zahnle, K., Alvarellos, J.L., Dobrovolskis, A.R., Hamill, P. [2008

  6. Dropping the Ball: The effect of anisotropic granular materials on ejecta and impact crater shape

    CERN Document Server

    Drexler, Philip; Arratia, Paulo

    2013-01-01

    In this fluid dynamics video, we present an experimental investigation of the shape of impact craters in granular materials. Complex crater shapes, including polygons, have been observed in many terrestrial planets as well as moons and asteroids. We release spherical projectiles from different heights above a granular bed (sand). The experiments demonstrate two different techniques to create non-circular impact craters, which we measure by digitizing the final crater topography. In the first method, we create trenches in the sand to mimic fault lines or valleys on a planetary target. During impact, ejecta move faster in the direction of the trenches, creating nearly elliptical craters with the major axis running parallel to the trench. Larger trenches lead to more oblong craters. In the second method, a hose beneath the surface of the sand injects nitrogen gas. The pressure of the gas counters the hydrostatic pressure of the sand, greatly reducing static friction between grains above the injection point, with...

  7. Gravitational waves and mass ejecta from binary neutron star mergers: Effect of the stars' rotation

    CERN Document Server

    Dietrich, Tim; Ujevic, Maximiliano; Tichy, Wolfgang

    2016-01-01

    We present new (3+1) dimensional numerical relativity simulations of the binary neutron star (BNS) mergers that take into account the NS spins. We consider different spin configurations, aligned or antialigned to the orbital angular momentum, for equal and unequal mass BNS and for two equations of state. All the simulations employ quasiequilibrium circular initial data in the constant rotational velocity approach, i.e. they are consistent with Einstein equations and in hydrodynamical equilibrium. We study the NS rotation effect on the energetics, the gravitational waves (GWs) and on the possible electromagnetic (EM) emission associated to dynamical mass ejecta. For dimensionless spin magnitudes of $\\chi\\sim0.1$ we find that spin-orbit interactions and also spin-induced-quadrupole deformations affect the late-inspiral-merger dynamics. The latter is, however, dominated by finite-size effects. Spin (tidal) effects contribute to GW phase differences up to 5 (20) radians accumulated during the last eight orbits to...

  8. ELEMENTAL ABUNDANCES IN THE EJECTA OF OLD CLASSICAL NOVAE FROM LATE-EPOCH SPITZER SPECTRA

    Energy Technology Data Exchange (ETDEWEB)

    Helton, L. Andrew; Vacca, William D. [SOFIA Science Center, USRA, NASA Ames Research Center, M.S. N232-11, Moffett Field, CA 94035 (United States); Gehrz, Robert D.; Woodward, Charles E.; Shenoy, Dinesh P. [Minnesota Institute for Astrophysics, School of Physics and Astronomy, 116 Church Street S.E., University of Minnesota, Minneapolis, MN 55455 (United States); Wagner, R. Mark [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Evans, Aneurin [Astrophysics Group, Keele University, Keele, Staffordshire ST5 5BG (United Kingdom); Krautter, Joachim [Landessternwarte-Zentrum fuer Astronomie der Universitaet, Koenigstuhl, D-69117 Heidelberg (Germany); Schwarz, Greg J. [American Astronomical Society, 2000 Florida Avenue, NW, Suite 400, Washington, DC 20009 (United States); Starrfield, Sumner, E-mail: ahelton@sofia.usra.edu [School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287 (United States)

    2012-08-10

    We present Spitzer Space Telescope mid-infrared IRS spectra, supplemented by ground-based optical observations, of the classical novae V1974 Cyg, V382 Vel, and V1494 Aql more than 11, 8, and 4 years after outburst, respectively. The spectra are dominated by forbidden emission from neon and oxygen, though in some cases, there are weak signatures of magnesium, sulfur, and argon. We investigate the geometry and distribution of the late time ejecta by examination of the emission line profiles. Using nebular analysis in the low-density regime, we estimate lower limits on the abundances in these novae. In V1974 Cyg and V382 Vel, our observations confirm the abundance estimates presented by other authors and support the claims that these eruptions occurred on ONe white dwarfs (WDs). We report the first detection of neon emission in V1494 Aql and show that the system most likely contains a CO WD.

  9. Afterglow Light Curves of Jetted Gamma-ray Burst Ejecta in Stellar Winds

    Institute of Scientific and Technical Information of China (English)

    Xue-Feng Wu; Zi-Gao Dai; Yong-Feng Huang; Hai-Tao Ma

    2004-01-01

    Optical and radio afterglows arising from shocks by relativistic conical ejecta running into pre-burst massive stellar winds are revisited. Under the homogeneous thin-shell approximation and a realistic treatment for the lateral expansion of jets, our results show that a notable break exists in the optical light curve in most cases we calculated in which the physical parameters are varied within reasonable ranges. For a relatively tenuous wind which cannot decelerate the relativistic jet to cause a light curve break within days, the wind termination shock due to the ram pressure of the surrounding medium occurs at a small radius, namely, a few times 1017 cm. In such a structured wind environment, the jet will pass through the wind within several hours and run into the outer uniform dense medium. The resulting optical light curve flattens with a shallower drop after the jet encounters the uniform medium, and then declines deeply, triggered by runaway lateral expansion.

  10. Life near the Roche limit - Behavior of ejecta from satellites close to planets

    Science.gov (United States)

    Dobrovolskis, A. R.; Burns, J. A.

    1980-01-01

    A study of the dynamics of nearby debris from impact craters was made to explain the distinctive features seen on Phobos, Deimis, and Amalthea. The planetary tides and satellite rotation were considered, and the usual pseudo-energy (Jacobi) integral was numerically calculated in the framework of a restricted body problem where satellites are modelled as triaxial ellipsoids rather than point masses. Iso-contours of this integral show that Deimos and Amalthea are entirely closed by Roche lobes, and the surfaces of their model ellipsoids lie nearly along equipotentials. Presently, the surface of Phobos overflows its Roche lobe, except for regions within a few km of the sub-Mars and anti-Mars points. The behavior of crater ejecta from the satellites of Mars were also examined by numerical integration of trajectories for particles leaving their surfaces in the equatorial plane.

  11. Unmelted Meteoritic Debris Collected from Eltanin Ejecta in Polarstern Cores from Expedition ANT XII/4

    Science.gov (United States)

    Kyte, Frank T.

    2002-01-01

    A total of 1.7g of unmelted meteorite particles have been recovered from FS Polarstern piston cores collected on expedition ANT XII/4 that contain ejecta from the Eltanin impact event. Most of the mass (1.2 g) is a large, single specimen that is a polymict breccia, similar in mineralogy and chemistry to howardites or the silicate fraction of mesosiderites. Most of the remaining mass is in several large individual pieces (20-75mg each) that are polymict breccias, fragments dominated by pyroxene, and an igneous rock fragment. The latter has highly fractionated REE, similar to those reported in mafic clasts from mesosiderites. Other types of specimens identified include fragments dominated by maskelynite or olivine. These pieces of the projectile probably survived impact by being blown off the back surface of the Eltanin asteroid during its impact into the Bellingshausen Sea.

  12. Ejecta Cloud from a Kinetic Impact on the Secondary of a Binary Asteroid: I. Mechanical Environment and Dynamic Model

    CERN Document Server

    Yu, Yang; Schwartz, Stephen R; Naidu, Shantanu P; Benner, Lance A M

    2016-01-01

    An understanding of the post-impact dynamics of ejecta clouds are crucial to the planning of a kinetic impact mission to an asteroid, and also has great implications for the history of planetary formation. The purpose of this article to track the evolution of ejecta produced by AIDA mission, which targets for kinetic impact the secondary of near-Earth binary asteroid 65803 Didymos on 2022, and to feedback essential informations to AIDA's ongoing phase-A study. We present a detailed dynamic model for the simulation of an ejecta cloud from a binary asteroid that synthesizes all relevant forces based on a previous analysis of the mechanical environment. We apply our method to gain insight into the expected response of Didymos to the AIDA impact, including the subsequent evolution of debris and dust. The crater scaling relations from laboratory experiments are employed to approximate the distributions of ejecta mass and launching speed. The size composition of fragments is modeled with a power law fitted from obs...

  13. Ejecta Particle-Size Measurements in Vacuum and Helium Gas using Ultraviolet In-Line Fraunhofer Holography

    Energy Technology Data Exchange (ETDEWEB)

    Sorenson, D. S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pazuchanics, P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Johnson, R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Malone, R. M. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Kaufman, M. I. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Tibbitts, A. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Tunnell, T. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Marks, D. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Capelle, G. A. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Grover, M. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Marshall, B. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Stevens, G. D. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Turley, W. D. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); LaLone, B. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States)

    2014-06-01

    An ultraviolet (UV) in-line Fraunhofer holography diagnostic has been developed for making high-resolution spatial measurements of ejecta particles traveling at many mm/μsec. This report will discuss the development of the diagnostic, including the high-powered laser system and high-resolution optical relay system. In addition, we will also describe the system required to reconstruct the images from the hologram and the corresponding analysis of those images to extract particles. Finally, we will present results from six high-explosive (HE), shock-driven Sn-ejecta experiments. Particle-size distributions will be shown that cover most of the ejecta velocities for experiments conducted in a vacuum, and helium gas environments. In addition, a modification has been made to the laser system that produces two laser pulses separated by 6.8 ns. This double-pulsed capability allows a superposition of two holograms to be acquired at two different times, thus allowing ejecta velocities to be measured directly. Results from this double-pulsed experiment will be described.

  14. Ejecta Particle-Size Measurements in Vacuum and Helium Gas using Ultraviolet In-Line Fraunhofer Holography

    Energy Technology Data Exchange (ETDEWEB)

    Sorenson, Danny S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pazuchanics, Peter [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Johnson, Randall P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Malone, R. M. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Kaufman, M. I. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Tibbitts, A. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Tunnell, T. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Marks, D. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Capelle, G. A. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Grover, M. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Marshall, B. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Stevens, G. D. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Turley, W. D. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); LaLone, B. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States)

    2014-06-25

    An Ultraviolet (UV) in-line Fraunhofer holography diagnostic has been developed for making high-resolution spatial measurements of ejecta particles traveling at many mm/μsec. This report will discuss the development of the diagnostic including the high-powered laser system and high-resolution optical relay system. In addition, the system required to reconstruct the images from the hologram and the corresponding analysis of those images to extract particles will also be described. Finally, results from six high-explosive (HE), shock-driven Sn ejecta experiments will be presented. Particle size distributions will be shown that cover most of the ejecta velocities for experiments conducted in a vacuum, and helium gas environments. In addition, a modification has been made to the laser system that produces two laser pulses separated by 6.8 ns. This double-pulsed capability allows a superposition of two holograms to be acquired at two different times, thus allowing ejecta velocities to be measured directly. Results from this double pulsed experiment will be described.

  15. ROLE OF EJECTA CLUMPING AND BACK-REACTION OF ACCELERATED COSMIC RAYS IN THE EVOLUTION OF TYPE Ia SUPERNOVA REMNANTS

    Energy Technology Data Exchange (ETDEWEB)

    Orlando, S.; Bocchino, F.; Miceli, M. [INAF-Osservatorio Astronomico di Palermo ' G. S. Vaiana' , Piazza del Parlamento 1, 90134 Palermo (Italy); Petruk, O. [Institute for Applied Problems in Mechanics and Mathematics, Naukova Street, 3-b Lviv 79060 (Ukraine); Pumo, M. L., E-mail: orlando@astropa.inaf.it [INAF-Osservatorio Astronomico di Padova, Vicolo dell' Osservatorio 5, 35122 Padova (Italy)

    2012-04-20

    We investigate the role played by initial clumping of ejecta and by efficient acceleration of cosmic rays (CRs) in determining the density structure of the post-shock region of a Type Ia supernova remnant (SNR) through detailed three-dimensional MHD modeling. Our model describes the expansion of an SNR through a magnetized interstellar medium, including the initial clumping of ejecta and the effects on shock dynamics due to back-reaction of accelerated CRs. The model predictions are compared to the observations of SN 1006. We found that the back-reaction of accelerated CRs alone cannot reproduce the observed separation between the forward shock and the contact discontinuity unless the energy losses through CR acceleration and escape are very large and independent of the obliquity angle. On the contrary, the clumping of ejecta can naturally reproduce the observed small separation and the occurrence of protrusions observed in SN 1006, even without the need of accelerated CRs. We conclude that forward shock-contact discontinuity separation is a probe of the ejecta structure at the time of explosion rather than a probe of the efficiency of CR acceleration in young SNRs.

  16. Ejecta Particle-Size Measurements in Vacuum and Helium Gas using Ultraviolet In-Line Fraunhofer Holography

    Energy Technology Data Exchange (ETDEWEB)

    Sorenson, D. S. [LANL; Pazuchanics, P. [LANL; Johnson, R. [LANL; Malone, R. M. [NSTec; Kaufman, M. I. [NSTec; Tibbitts, A. [NSTec; Tunnell, T. [NSTec; Marks, D. [NSTec; Capelle, G. A. [NSTec; Grover, M. [NSTec; Marshall, B. [NSTec; Stevens, G. D. [NSTec; Turley, W. D. [NSTec; LaLone, B. [NSTec

    2014-06-30

    An ultraviolet (UV) in-line Fraunhofer holography diagnostic has been developed for making high-resolution spatial measurements of ejecta particles traveling at many mm/μsec. This report will discuss the development of the diagnostic, including the high-powered laser system and high-resolution optical relay system. In addition, we will also describe the system required to reconstruct the images from the hologram and the corresponding analysis of those images to extract particles. Finally, we will present results from six high-explosive (HE), shock-driven Sn-ejecta experiments. Particle-size distributions will be shown that cover most of the ejecta velocities for experiments conducted in a vacuum, and helium gas environments. In addition, a modification has been made to the laser system that produces two laser pulses separated by 6.8 ns. This double-pulsed capability allows a superposition of two holograms to be acquired at two different times, thus allowing ejecta velocities to be measured directly. Results from this double-pulsed experiment will be described.

  17. Impacts into quartz sand: Crater formation, shock metamorphism, and ejecta distribution in laboratory experiments and numerical models

    Science.gov (United States)

    Wünnemann, Kai; Zhu, Meng-Hua; Stöffler, Dieter

    2016-10-01

    We investigated the ejection mechanics by a complementary approach of cratering experiments, including the microscopic analysis of material sampled from these experiments, and 2-D numerical modeling of vertical impacts. The study is based on cratering experiments in quartz sand targets performed at the NASA Ames Vertical Gun Range. In these experiments, the preimpact location in the target and the final position of ejecta was determined by using color-coded sand and a catcher system for the ejecta. The results were compared with numerical simulations of the cratering and ejection process to validate the iSALE shock physics code. In turn the models provide further details on the ejection velocities and angles. We quantify the general assumption that ejecta thickness decreases with distance according to a power-law and that the relative proportion of shocked material in the ejecta increase with distance. We distinguish three types of shock metamorphic particles (1) melt particles, (2) shock lithified aggregates, and (3) shock-comminuted grains. The agreement between experiment and model was excellent, which provides confidence that the models can predict ejection angles, velocities, and the degree of shock loading of material expelled from a crater accurately if impact parameters such as impact velocity, impactor size, and gravity are varied beyond the experimental limitations. This study is relevant for a quantitative assessment of impact gardening on planetary surfaces and the evolution of regolith layers on atmosphereless bodies.

  18. Distal Impact Ejecta at Paleocene-Eocene Boundary sections on the Atlantic Margin

    Science.gov (United States)

    Schaller, M. F.; Fung, M. K.; Wright, J. D.; Katz, M. E.; Kent, D. V.

    2016-12-01

    A rapid global warming event 56 million years ago at the Paleocene-Eocene (P-E) boundary (the Paleocene-Eocene Thermal Maximum, PETM) was accompanied by an abrupt negative carbon isotope excursion (CIE) observed globally. We report the discovery of silicate glass spherules in a discrete stratigraphic layer coincident with the P-E boundary from several marine sections on the Atlantic coastal plain and offshore. The spherules are found in the onset of the CIE that defines the P-E boundary at each site. They average 275 mm in diameter, have rotational and splash form morphologies, surficial microcraters, and are translucent colorless to brown, green and black. Energy dispersive x-ray spectroscopy from grain mounts and polished sections of representative spherules show that they have related major oxide chemistries of up to 50% silica, with the remainder comprised of CaO, FeO, and Al2O3, which all vary in relative proportion with silica content. The chemistries of the spherules form a population that is distinct from impact ejecta from other major strewn fields, such as the Cretaceous-Paleogene microtektites, but show more variability than is expected from volcanism. Field transmission infrared spectroscopy on a subset of spherules reveals water content bond-bending vibration from 464 to 460 cm-1, consistent with observations from other Raman studies of quartz experimentally shocked to high peak pressures of 25.8 GPa. The summation of these characteristics is consistent with features of melt-drop microtektites and microkrystites from other known impact strewn fields. We therefore interpret the P-E boundary spherules as a component of a distal impact ejecta layer, indicating that an extraterrestrial impact was coincident with the onset of the CIE.

  19. The Ultraviolet Spectrum of η Carinae: Investigation of the Ejecta Absorption

    Science.gov (United States)

    Nielsen, K. E.; Gull, T. R.; Vieira Kober, G.

    2005-03-01

    We have investigated the far- through mid-UV (1150-2360 Å) spectrum of η Carinae during the late stages of its broad maximum using the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) moderate dispersion echelle modes. The η Car spectrum is a mixture of absorption and emission lines from the surrounding nebula superimposed on broad stellar wind features. This paper provides a description of the observed spectrum including the wind features, the interstellar absorption, and the emission spectrum from the surrounding nebula, but with the emphasis on the absorption spectrum formed in the foreground ejecta. The ejecta absorption spectrum has a complicated velocity structure in which two velocity structures, at -146 and -513 km s-1, are easily distinguished. These two velocity components, formed in different regions of the η Car nebula, have in an earlier analysis been identified and demonstrated to have very different spectral characteristics. The slower velocity component is time variable over the spectroscopic period and is characterized by spectral lines from mainly singly ionized iron-peak elements, while the faster one shows transitions from neutral and singly ionized elements in addition to molecular lines from the hydrogen Lyman bands. The high-velocity H2 lines dominate great parts of the spectrum with over 800 identified transitions from energy levels up to 30,000 cm-1. The STIS MAMA data provide the tool for spatial investigations of the central parts of η Car. H I Lyα pumped and semiforbidden emission lines are observed to be formed east of the central source toward Weigelt blobs B and C, located up to 0.2" from the central source. The complete spectrum, with nebular and interstellar line identifications, is available in the electronic edition of the paper. Laboratory for Astronomy and Solar Physics, Code 681, Goddard Space Flight Center, Greenbelt, MD 20771.

  20. Subeffusive Ejecta At Mount Vesuvius: Evidence For A "shallow" Magma Reservoir

    Science.gov (United States)

    Cigolini, C.; Ruffini, R.; Laiolo, M.

    Subeffusive ejecta of the 1944 eruption of Mount Vesuvius are tephritic clinopyroxene-rich porphyries and italites. These materials are associated to pyroclas- tic deposits of phono-tephritic composition. Tephrytic porphyries show a hypidiomor- phic granular texture and consist of phenocrystic leucite, diopsidic clinopyroxene, olivine and phlogopite on a holocrystalline matrix of leucite, plagioclase, phlogopite. Titanomagnetite and apatite are accessory phases. Sampled italites ejecta are charac- terized by an orthocumulithic texture consisting of a crystals leucite and interstitial brownish glass. This glass includes rare elongated microphenocrysts of plagioclase and subordinated clinopyroxene. REE patterns for the tephritic porphyries are com- parable with those of recent lavas and tephra and show a sligthly higher enrichment in HREE (up to 10 times the average chondrite). Spider diagrams, normalized to pri- mordial mantle values, indicate that the tephritic porphyries lack a negative anomaly in Ta which, in turn, is strongly negative within the lavas. This is due to the higher content of phenocrystic clinopyroxene (with a high mineral/melt partition coefficient) within the tephritic porphyries. Thermobarometric estimates indicate that leucite is in equilibrium with a tephritic melt at pressures of 5.7-6 kbar for temperatures ranging 1100-1200 C. Moreover, selected reactions for the assemblage Ol+Cpx+An+SiO2 (liq) define equilibrium pressures of 3.2-5 kbar [both for hydrous (with about 2 wt % H2O) and anhydrous conditions] for temperatures ranging 1150-1200 C. These esti- mates suggests the existence of a secondary "shallow" reservoir located at a depth of about 10-18 Km below Mount Vesuvius, which is consistent with recent petrological and geophysical data.

  1. The Host Galaxies of Fast-Ejecta Core-Collapse Supernovae

    Science.gov (United States)

    Kelly, Patrick L.; Filippenko, Alexei V.; Modjaz, Maryam; Kocevski, Daniel

    2014-01-01

    Spectra of broad-lined Type Ic supernovae (SN Ic-BL), the only kind of SN observed at the locations of long-duration gamma-ray bursts (LGRBs), exhibit wide features indicative of high ejecta velocities ((is) approximately 0.1c). We study the host galaxies of a sample of 245 low-redshift (z (is) less than 0.2) core-collapse SN, including 17 SN Ic-BL, discovered by galaxy-untargeted searches, and 15 optically luminous and dust-obscured z (is) less than 1.2 LGRBs. We show that, in comparison with SDSS galaxies having similar stellar masses, the hosts of low-redshift SN Ic- BL and z (is) is less than 1.2 LGRBs have high stellar-mass and star-formation-rate densities. Core-collapse SN having typical ejecta velocities, in contrast, show no preference for such galaxies. Moreover, we find that the hosts of SN Ic-BL, unlike those of SN Ib/Ic and SN II, exhibit high gas velocity dispersions for their stellar masses. The patterns likely reflect variations among star-forming environments, and suggest that LGRBs can be used as probes of conditions in high-redshift galaxies. They may be caused by efficient formation of massive binary progenitors systems in densely star-forming regions, or, less probably, a higher fraction of stars created with the initial masses required for a SN Ic-BL or LGRB. Finally, we show that the preference of SN Ic-BL and LGRBs for galaxies with high stellar-mass and star-formation-rate densities cannot be attributed to a preference for low metal abundances but must reflect the influence of a separate environmental factor.

  2. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Estimated thickness of ejecta deposits compared to to crater rim heights. Ph.D. Thesis

    Science.gov (United States)

    Leake, M. A.

    1982-01-01

    The area of the continuous ejecta deposits on mercury was calculated to vary from 2.24 to 0.64 times the crater's area for those of diameter 40 km to 300 km. Because crater boundaries on the geologic map include the detectable continuous ejecta blanket, plains exterior to these deposits must consist of farther-flung ejecta (of that or other craters), or volcanic deposits flooding the intervening areas. Ejecta models are explored.

  3. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Estimated thickness of ejecta deposits compared to to crater rim heights. Ph.D. Thesis

    Science.gov (United States)

    Leake, M. A.

    1982-01-01

    The area of the continuous ejecta deposits on mercury was calculated to vary from 2.24 to 0.64 times the crater's area for those of diameter 40 km to 300 km. Because crater boundaries on the geologic map include the detectable continuous ejecta blanket, plains exterior to these deposits must consist of farther-flung ejecta (of that or other craters), or volcanic deposits flooding the intervening areas. Ejecta models are explored.

  4. Estimates of primary ejecta and local material for the Orientale basin: Implications for the formation and ballistic sedimentation of multi-ring basins

    Science.gov (United States)

    Xie, Minggang; Zhu, Meng-Hua

    2016-04-01

    A clear understanding of thickness distributions of primary ejecta and local material is critical to interpreting the process of ballistic sedimentation, provenances of lunar samples, the evolution of the lunar surface, and the origin of multi-ring basins. The youngest lunar multi-ring basin, Orientale, provides the best preserved structure for determining the thicknesses of primary ejecta and local material. In general, the primary ejecta thickness was often estimated using crater morphometry. However, previous methods ignored either crater erosion, the crater interior geometry, or both. In addition, ejecta deposits were taken as mostly primary ejecta. And, as far as we know, the local material thickness had not been determined for the Orientale. In this work, we proposed a model based on matching measurements of partially filled pre-Orientale craters (PFPOCs) with the simulations of crater erosion to determine their thicknesses. We provided estimates of primary ejecta thickness distribution with the thickness of 0.85 km at Cordillera ring and a decay power law exponent of b = 2.8, the transient crater radius of 200 km, excavation volume of 2.3 ×106 km3, primary ejecta volume of 2.8 ×106 km3. These results suggest that previous works (e.g., Fassett et al., 2011; Moore et al., 1974) might overestimate the primary ejecta thicknesses of Orientale, and the primary ejecta thickness model of Pike (1974a) for multi-ring basins may give better estimates than the widely cited model of McGetchin et al. (1973) and the scaling law for impacts into Ottawa Sand (Housen et al., 1983). Structural uplift decays slower than previously thought, and rim relief is mostly rim uplift for Orientale. The main reason for rim uplift may be the fracturing and squeezing upward of the surrounding rocks. The proportion of local material to ejecta deposits increases with increasing radial distance from basin center, and the thickness of local material is larger than that of primary ejecta at

  5. Studying the nucleus of comet 9P/Tempel 1 using the structure of the Deep Impact ejecta cloud at the early stages of its development

    CERN Document Server

    Kolokolova, Ludmilla; A`Hearn, Michael; King, Ashley; Wolff, Michael

    2016-01-01

    We present an attempt to extract information about the comet 9P/Tempel 1 nucleus from the characteristics of the ejecta cloud produced by the impactor of the Deep Impact mission. For this purpose we use two techniques. We first study the shadow cast on the nucleus surface by the ejecta cloud and investigate how areas of different brightness are related to the varying optical thickness or albedo of the ejecta cloud. The shadow was seen during the first 2.0 seconds after the impact (afterward it became obscured by the ejecta cloud). We have found that all brightness variations in the shadow are the result of the surface inhomogeneities, indicating that during first 2.0 seconds the ejecta cloud was homogeneous within the MRI spatial resolution. Our second technique is to study the obscuration of the nucleus limb by the ejecta. This study covers the period 0.76- 68.8 seconds after impact and is based on comparison of the ejecta cloud brightness on the limb and just beyond the limb. At this stage we do see inhomog...

  6. Dating Kaali Crater (Estonia) based on charcoal emplaced within proximal ejecta blanket

    Science.gov (United States)

    Losiak, Anna; Wild, Eva Maria; Huber, Matthew S.; Wisniowski, Tomasz; Paavel, Kristiina; Jõeleht, Argo; Välja, Rudolf; Plado, Jüri; Kriiska, Aivar; Wilk, Jakob; Zanetti, Michael; Geppert, Wolf D.; Kulkov, Alexander; Steier, Peter; Pirkovic, Irena

    2015-04-01

    The Kaali impact field consists of nine identified craters located on the Saaremaa Island in Estonia. The largest crater is 110 m in diameter (centered around 58°22'21.94"N, 22°40'09.91" E). It was formed by impact of an IAB iron meteoroid into Silurian dolomite target rocks covered by up to a few meters of glacial till (Veski et al. 2007). The age of the Kaali impact structure is still a matter of debate, and the estimates provided by different authors vary considerably between ~6400 BC (Raukas et al. 1995, Moora et al. 2012) and ~400 BC (Rasmussen et al. 2000, Veski et al. 2001). These ages were derived by 14C dating of marker horizons, characterized by a slightly elevated iridium content within the nearby Piila bog yielding a calibrated age of 800-400 BC (Rasmussen et al. 2000, Veski et al. 2001) and occurrences of glassy siliceous material in the Piila bog (~6400 BC: Raukas et al. 1995) or iron microspherules in an organic-rich layer of the Reo gravel pit (6400 BC: Moora et al. 2012). However, the source of the foreign material within those layers was never unequivocally connected with the Kaali crater. 14C dating of material from post-impact organic sediments within Kaali impact craters yielded ages between 1800-1500 BC (Saarse et al. 1991, Veski et al. 2004) and 1450-400 BC (Aaloe et al. 1963). These dates underestimate the age of impact as organic sediments within the crater started to form at unknown period after the impact. On the other hand, Veski et al. (2004) suggested a reservoir effect that might have caused artificially "aging" of the organic matter because the crater was emplaced within Silurian dolomite which is rich in old carbon. The aim of this study is to determine the age of the Kaali crater by 14C dating of organic material covered by the continuous layer of proximal ejecta. This research was conducted in conjunction with a new structural investigation of Kaali Main (Zanetti et al. 2015). Ten samples collected from different locations

  7. The Search for Sustainable Subsurface Habitats on Mars, and the Sampling of Impact Ejecta

    Directory of Open Access Journals (Sweden)

    Paula Lindgren

    2010-07-01

    Full Text Available On Earth, the deep subsurface biosphere of both the oceanic and the continental crust is well known for surviving harsh conditions and environments characterized by high temperatures, high pressures, extreme pHs, and the absence of sunlight. The microorganisms of the terrestrial deep biosphere have an excellent capacity for adapting to changing geochemistry, as the alteration of the crust proceeds and the conditions of their habitats slowly change. Despite an almost complete isolation from surface conditions and the surface biosphere, the deep biosphere of the crustal rocks has endured over geologic time. This indicates that the deep biosphere is a self-sufficient system, independent of the global events that occur at the surface, such as impacts, glaciations, sea level fluctuations, and climate changes. With our sustainable terrestrial subsurface biosphere in mind, the subsurface on Mars has often been suggested as the most plausible place to search for fossil Martian life, or even present Martian life. Since the Martian surface is more or less sterile, subsurface settings are the only place on Mars where life could have been sustained over geologic time. To detect a deep biosphere in the Martian basement, drilling is a requirement. However, near future Mars sample return missions are limited by the mission’s payload, which excludes heavy drilling equipment and restrict the missions to only dig the topmost meter of the Martian soil. Therefore, the sampling and analysis of Martian impact ejecta has been suggested as a way of accessing the deeper Martian subsurface without using heavy drilling equipment. Impact cratering is a natural geological process capable of excavating and exposing large amounts of rock material from great depths up to the surface. Several studies of terrestrial impact deposits show the preservation of pre-impact biosignatures, such as fossilized organisms and chemical biological markers. Therefore, if the Martian

  8. Geochemistry of K/T-boundary Chicxulub ejecta of NE-Mexico

    Science.gov (United States)

    Harting, M.; Deutsch, A.; Rickers, K.

    2003-12-01

    Many K/T sections all over the world contain impact spherules supposed related to the Chicxulub event. This study focus on ejecta layers in NE-Mexican profiles. We carried out systematic XRF and synchrotron radiation measurements on such spherules at the HASYLAB and ANKA facilities as well as microprobe analyses (CAMECA SX50). Area scans on tektite-like material of the Bochil section reveal a pronounced zonation in the inner part, dominated by Ba and Sr whereas secondary CaCO3 dominates in the altered margin. The composition of the spherules from the Mesa-Juan Perez section differ significantly from the Beloc (Haiti) and Bochil tektite glasses. At Mesa-Juan Perez, spherules are either extremely rich in Fe and Ca or consist of smectite, some of those carry carbonate inclusions. Yttrium, La and Ce are zoned within the smectite with concentrations below the detection limit and up to 20 æg/g The Ca-rich inclusions are enriched in Y (up to 35 æg/g) and La (18 æg/g) and, compared to the surrounding smectite, also in Ce (up to 34 æg/g). The Ce enrichment in spherules from the Mesa-Juan Perez section indicates impact-melted carbonates of the Yucatan carbonate platform as possible precursor rocks. Recent investigations focus on the chemistry of melt rock samples from the PEMEX wells Yucatan-6 and Chicxulub-1: Their average composition (mean of 250 data points in wt-percent ) is 61.6 for SiO2, 0.16 for TiO2, 18.07 for Al2O3, 0.01 for Cr2O3, 1.98 for Na2O, 1.5 for FeO, 0.05 for MnO, 0.01 for NiO, 0.31 for MgO, 9.14 for K2O, 3.44 for CaO, and 0.01 for SO2. These results are in some cases comparable to the geochemistry of ejecta glasses, e.g. from Beloc (Haiti).

  9. Lateral and Vertical Heterogeneity of Thorium in the Procellarum KREEP Terrane: As Reflected in the Ejecta Deposits of Post-Imbrium Craters

    Science.gov (United States)

    Gillis, J. J.; Jolliff, B. L.

    1999-01-01

    discussed above and their ejecta, with the goal of describing the materials they excavate. One interpretation for the origin of the high-Th material is that subsurface KREEPy materials have been excavated by impact craters. The material excavated may be either volcanic KREEP (e,g., Apennine Bench Formation), KREEPy impact-melt breccia formed by the Imbrium impact (e.g., Fra Mauro Formation), or other KREEP-rich crustal material. Determining which type of material is responsible for the elevated Th and its extent is important to understanding the premare and possibly the prebasin stratigraphy of the Imbrium-Procellarum Region. Merging the 5 deg. Th data with the shaded relief map, we observe that the highest Th concentrations are not related to pre-Imbrium upper crustal materials. The Apennines, Alpes, and Caucasus Mountains represent the pre-Imbrian highlands material and do not express concentrations of Th, FeO, and TiO2 as high as the most Th-fich materials exposed within the Procellarum KREEP Terrane. We observe that, in general, these massifs contain 10-14 wt% FeO and 4-7 ppm Th. Determining whether the Th signal is from KREEP basalts or KREEPy impact-melt breccias cannot be done with the Clementine data because the two rock types are compositionally and mineralogically too similar (e.g., the Th-rich, mafic impact-melt breccias in the Apollo sample collection are dominated by a KREEP-basalt like component. Mapping-the distribution and sizes of craters and whether they display elevated Th concentrations or not, should reveal the depth and thickness of the KREEP-rich materials, and whether they are ubiquitous (i.e., impact-melt breccia) or more randomly distributed; this might be taken as an indicator of localized KREEP-basalt flows. Within the southeastern region of the Imbrium basin, there are two Th hot spots. The first is associated with the crater Aristillus, and the latter with the Apennine Bench Formation. Adjacent to these two hot spots are craters with a lower Th

  10. Impact of weak interactions of free nucleons on the r-process in dynamical ejecta from neutron-star mergers

    CERN Document Server

    Goriely, Stephane; Just, Oliver; Pllumbi, Else; Janka, Hans-Thomas

    2015-01-01

    We investigate beta-interactions of free nucleons and their impact on the electron fraction (Y_e) and r-process nucleosynthesis in ejecta characteristic of binary neutron star mergers (BNSMs). For that we employ trajectories from a relativistic BNSM model to represent the density-temperature evolutions in our parametric study. In the high-density environment, positron captures decrease the neutron richness at the high temperatures predicted by the hydrodynamic simulation. Circumventing the complexities of modelling three-dimensional neutrino transport, (anti)neutrino captures are parameterized in terms of prescribed neutrino luminosities and mean energies, guided by published results and assumed as constant in time. Depending sensitively on the adopted neutrino-antineutrino luminosity ratio, neutrino processes increase Y_e to values between 0.25 and 0.40, still allowing for a successful r-process compatible with the observed solar abundance distribution and a significant fraction of the ejecta consisting of r...

  11. Recycled stellar ejecta as fuel for star formation and implications for the origin of the galaxy mass-metallicity relation

    CERN Document Server

    Segers, Marijke C; Schaye, Joop; Bower, Richard G; Furlong, Michelle; Schaller, Matthieu; Theuns, Tom

    2015-01-01

    We use cosmological, hydrodynamical simulations from the EAGLE and OWLS projects to assess the significance of recycled stellar ejecta as fuel for star formation. The fractional contributions of stellar mass loss to the cosmic star formation rate (SFR) and stellar mass densities increase with time, reaching $35 \\%$ and $19 \\%$, respectively, at $z=0$. The importance of recycling increases steeply with galaxy stellar mass for $M_{\\ast} < 10^{10.5}$ M$_{\\odot}$, and decreases mildly at higher mass. This trend arises from the mass dependence of feedback associated with star formation and AGN, which preferentially suppresses star formation fuelled by recycling. Recycling is more important for satellites than centrals and its contribution decreases with galactocentric radius. The relative contribution of AGB stars increases with time and towards galaxy centers. This is a consequence of the more gradual release of AGB ejecta compared to that of massive stars, and the preferential removal of the latter by outflow...

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

    Energy Technology Data Exchange (ETDEWEB)

    Matsuura, M.; Barlow, M. J. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Dwek, E. [Observational Cosmology Laboratory Code 665, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Babler, B. [Department of Astronomy, 475 North Charter Street, University of Wisconsin, Madison, WI 53706 (United States); Baes, M.; Fritz, Jacopo [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, B-9000 Gent (Belgium); Meixner, M. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Cernicharo, José [Departamento de Astrofísica, Centro de Astrobiología, CSIC-INTA, Ctra. de Torrejón a Ajalvir km 4, E-28850 Madrid (Spain); Clayton, Geoff C. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Dunne, L. [Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch 8140 (New Zealand); Fransson, C.; Lundqvist, P. [The Oskar Klein Centre, Department of Astronomy, Stockholm University, Albanova, SE-10691 Stockholm (Sweden); Gear, Walter; Gomez, H. L. [School of Physics and Astronomy, Cardiff University, Cardiff CF24 3AA (United Kingdom); Groenewegen, M. A. T. [Koninklijke Sterrenwacht van België, Ringlaan 3, 1180 Brussel (Belgium); Indebetouw, R. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); Ivison, R. J. [SUPA, Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Jerkstrand, A. [Astrophysics Research Centre, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Lebouteiller, V. [AIM, CEA/Saclay, L' Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Lim, T. L., E-mail: mikako@star.ucl.ac.uk [RAL Space, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom); 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.

  13. The Vakkejokk Breccia: An Early Cambrian proximal impact ejecta layer in the North-Swedish Caledonides

    Science.gov (United States)

    Ormö, J.; Nielsen, A. T.; Alwmark, C.

    2017-04-01

    The ≤27 m thick Vakkejokk Breccia is intercalated in autochthon Lower Cambrian along the Caledonian front north of Lake Torneträsk, Lapland, Sweden. The spectacular breccia is here interpreted as a proximal ejecta layer associated with an impact crater, probably 2-3 km in size, located below Caledonian overthrusts immediately north of the main breccia section. The impact would have taken place in a shallow-marine environment 520 Ma ago. The breccia comprises i) a strongly disturbed lower polymict subunit with occasional, in themselves brecciated, crystalline mega-clasts locally exceeding 50 m surrounded by contorted sediments; ii) a middle, commonly normally graded, crystalline-rich, polymict subunit, in turn locally overlain by iii) a thin fine-grained quartz sandstone, impact crater, even causing some net outwards mobilization of the sediments. The middle subunit and the uppermost quartz sandstone are considered resurge deposits. The top conglomerate may be caused by subsequent wave reworking and slumping of material from the elevated rim. Quartz grains showing planar deformation features are present in the graded polymict subunit and the upper sandstone, that is, the inferred resurge deposits.

  14. A 3D Kinematic Study of the Northern Ejecta "Jet" of the Crab Nebula

    CERN Document Server

    Black, Christine S

    2014-01-01

    We present [O III] 4959,5007 emission line spectra (FWHM = 40 km/s) of the Crab Nebula's northern ejecta `jet'. These data, along with a recent [O III] image of the Crab, are used to build 3-dimensional models of the jet and adjacent remnant nebulosity to better understand the jet's properties and possible formation. We find that the jet's radial velocities range from -190 to +480 km/s with transverse velocities from 1600 to 2650 km/s from base to tip. The jet appears virtually hollow in [O III] emission with the exception of some material at the jet's base where the it connects with the remnant. Our 3D reconstructions indicate that the jet is elliptical in shape and slightly funnel-like rather than a straight cylindrical tube as previously thought. At the base of the jet we find evidence for a significant opening or "channel" in the Crab's main nebula shell. Our analysis of the jet's expansion properties and location supports the theory that the jet may simply represent the highest velocity component of the ...

  15. Type Ia Supernova Colors and Ejecta Velocities: Hierarchical Bayesian Regression with Non-Gaussian Distributions

    CERN Document Server

    Mandel, Kaisey S; Kirshner, Robert P

    2014-01-01

    We investigate the correlations between the peak intrinsic colors of Type Ia supernovae (SN Ia) and their expansion velocities at maximum light, measured from the Si II 6355 A spectral feature. We construct a new hierarchical Bayesian regression model and Gibbs sampler to estimate the dependence of the intrinsic colors of a SN Ia on its ejecta velocity, while accounting for the random effects of intrinsic scatter, measurement error, and reddening by host galaxy dust. The method is applied to the apparent color data from BVRI light curves and Si II velocity data for 79 nearby SN Ia. Comparison of the apparent color distributions of high velocity (HV) and normal velocity (NV) supernovae reveals significant discrepancies in B-V and B-R, but not other colors. Hence, they are likely due to intrinsic color differences originating in the B-band, rather than dust reddening. The mean intrinsic B-V and B-R color differences between HV and NV groups are 0.06 +/- 0.02 and 0.09 +/- 0.02 mag, respectively. Under a linear m...

  16. The interplay between chemistry and nucleation in the formation of carbonaceous dust in supernova ejecta

    CERN Document Server

    Lazzati, Davide

    2015-01-01

    Core-collapse supernovae are considered to be important contributors to the primitive dust enrichment of the interstellar medium in the high-redshift universe. Theoretical models of dust formation in stellar explosions have so far provided controversial results and a generally poor fit to the observations of dust formation in local supernovae. We present a new methodology for the calculation of carbonaceous dust formation in young supernova remnants. Our new technique uses both the nucleation theory and a chemical reaction network to allow us to compute the dust growth beyond the molecular level as well as to consider chemical erosion of the forming grains. We find that carbonaceous dust forms efficiently in the core of the ejecta, but takes several years to condensate, longer than previously estimated. It forms unevenly and remains concentrated in the inner part of the remnant. These results support the role of core-collapse supernovae as dust factories and provide new insight on the observations of SN 1987A...

  17. Relativistic ejecta from XRF 060218 and the complete census of cosmic explosions

    CERN Document Server

    Soderberg, A M; Burrows, D N; Cameron, P B; Cenko, S B; Chevalier, R A; Fox, D B; Frail, D A; Gal-Yam, A; Gehrels, N; Kasliwal, M; Kulkarni, S R; McCarthy, P J; Moon, D S; Nakar, E; Nousek, J A; Penprase, B E; Perrson, S E; Piran, T; Pooley, G; Price, P A; Sari, R; Schmidt, B P

    2006-01-01

    Over the last decade, long-duration gamma-ray bursts (GRBs) and X-ray flashes (XRFs) have been revealed to be a rare variety of Type Ibc supernova (SN). While all these events result from the death of massive stars, the electromagnetic luminosities of GRBs and XRFs exceed those of ordinary Type Ibc SNe by many orders of magnitude. The essential physical process that causes a dying star to produce a GRB or XRF, and not just an SN, remains the crucial open question. Here we present radio and X-ray observations of XRF 060218 (associated with SN 2006aj), the second nearest GRB identified to-date, which allow us to measure its total energy and place it in the larger context of cosmic explosions. We show that this event is 100 times less energetic but ten times more common than cosmological GRBs. Moreover, it is distinguished from ordinary Type Ibc SNe by the presence of 10^48 erg of mildly-relativistic ejecta, along with a central engine which produces X-rays for weeks after the explosion. This suggests that the p...

  18. Rotation Periods of Binary Asteroids with Large Separations - Confronting the Escaping Ejecta Binaries Model with Observations

    CERN Document Server

    Polishook, D; Prialnik, D

    2010-01-01

    Durda et al. (2004), using numerical models, suggested that binary asteroids with large separation, called Escaping Ejecta Binaries (EEBs), can be created by fragments ejected from a disruptive impact event. It is thought that six binary asteroids recently discovered might be EEBs because of the high separation between their components (~100 > a/Rp > ~20). However, the rotation periods of four out of the six objects measured by our group and others and presented here show that these suspected EEBs have fast rotation rates of 2.5 to 4 hours. Because of the small size of the components of these binary asteroids, linked with this fast spinning, we conclude that the rotational-fission mechanism, which is a result of the thermal YORP effect, is the most likely formation scenario. Moreover, scaling the YORP effect for these objects shows that its timescale is shorter than the estimated ages of the three relevant Hirayama families hosting these binary asteroids. Therefore, only the largest (D~19 km) suspected astero...

  19. Discovery of CH and OH in the -513 km s-1 Ejecta of Eta Carinae

    CERN Document Server

    Verner, E; Nielsen, K E; Gull, T R; Kober, G V; Corcoran, M

    2005-01-01

    The very massive star, Eta Carinae, is enshrouded in an unusual complex of stellar ejecta, which is highly depleted in C and O, and enriched in He and N. This circumstellar gas gives rise to distinct absorption components corresponding to at least 20 different velocities along the line-of-sight. The velocity component at -513 kms-1 exhibits very low ionization with predominantly neutral species of iron-peak elements. Our statistical equilibrium/photoionization modeling indicates that the low temperature (T = 760 K) and high density (n_H=10^7 cm^-3) of the -513 kms-1 component is conducive to molecule formation including those with the elements C and O. Examination of echelle spectra obtained with the Space Telescope Imaging Spectrograph (STIS) aboard the confirms the model's predictions. The molecules, H_2, CH, and most likely OH, have been identified in the -513 kms-1 absorption spectrum. This paper presents the analysis of the HST/STIS spectra with the deduced column densities for CH, OH and C I, and upper ...

  20. Spatial distribution of X-ray emitting ejecta in Tycho's SNR: indications of shocked Titanium

    CERN Document Server

    Miceli, M; Troja, E; Orlando, S

    2015-01-01

    Young supernova remnants show a characteristic ejecta-dominated X-ray emission that allows us to probe the products of the explosive nucleosynthesis processes and to ascertain important information about the physics of the supernova explosions. Hard X-ray observations have recently revealed the radioactive decay lines of 44Ti at ~67.9 keV and ~78.4 keV in the Tycho's SNR. We here analyze the set of XMM-Newton archive observations of the Tycho's SNR. We produce equivalent width maps of the Fe K and Ca XIX emission lines and find indications for a stratification of the abundances of these elements and significant anisotropies. We then perform a spatially resolved spectral analysis by identifying five different regions characterized by high/low values of the Fe K equivalent width. We find that the spatial distribution of the Fe K emission is correlated with that of the Cr XXII. We also detect the Ti K-line complex in the spectra extracted from the two regions with the highest values of the Fe and Cr equivalent w...

  1. Condensation of dust in the ejecta of type II-P supernovae

    CERN Document Server

    Sarangi, Arkaprabha

    2014-01-01

    Aims: We study the production of dust in Type II-P supernova by coupling the gas-phase chemistry to the dust nucleation and condensation phases. We consider two supernova progenitor masses with homogeneous and clumpy ejecta to assess the chemical type and quantity of dust that forms. Grain size distributions are derived as a function of post-explosion time. Methods: The chemistry of the gas phase and the simultaneous formation of dust clusters are described by a chemical network. The formation of key species (CO, SiO) and dust clusters of silicates, alumina, silica, metal carbides and sulphides, pure metals, and amorphous carbon is considered. The master equations describing the chemistry of the nucleation phase are coupled to a dust condensation formalism based on Brownian coagulation. Results: Type II-P supernovae produce dust grains of various chemical compositions and size distributions as a function of time. The grain size distributions gain in complexity with time, are slewed towards large grains, and d...

  2. Radioactive decay products in neutron star merger ejecta: heating efficiency and $\\gamma$-ray emission

    CERN Document Server

    Hotokezaka, Kenta; Tanaka, Masaomi; Bamba, Aya; Terada, Yukikatsu; Piran, Tsvi

    2015-01-01

    The radioactive decay of the freshly synthesized $r$-process nuclei ejected in compact binary mergers power optical/infrared macronovae (kilonovae) that follow these events. The light curves depend critically on the energy partition among the different products of the radioactive decay and this plays an important role in estimates of the amount of ejected $r$-process elements from a given observed signal. We study the energy partition and $\\gamma$-ray emission of the radioactive decay. We show that $20$-$50\\%$ of the total radioactive energy is released in $\\gamma$-rays on timescales from hours to a month. The number of emitted $\\gamma$-rays per unit energy interval has roughly a flat spectrum between a few dozen keV and $1$ MeV so that most of this energy is carried by $\\sim 1$ MeV $\\gamma$-rays. However at the peak of macronova emission the optical depth of the $\\gamma$-rays is $\\sim 0.02$ and most of the $\\gamma$-rays escape. The loss of these $\\gamma$-rays reduces the heat deposition into the ejecta and h...

  3. Afterglow Light Curves from Jetted Gamma-ray Burst Ejecta in Stellar Winds

    CERN Document Server

    Wu, X F; Huang, Y F; Ma, H T

    2003-01-01

    We revisit optical and radio afterglows arising from the shocks by relativistic conical ejecta running into pre-burst massive stellar winds. Under the homogeneous thin-shell approximation and the realistic treatment for lateral expansion of jets, our results show that a notable break of optical light curve within one decade in time indeed exists in most cases of our calculations by varying physical parameters within reasonable ranges. We rectify the conclusions of previous works on the jet+wind model, which claimed that there was no sharp break as the transition time lasts for two decades. Even for a relatively tenuous wind which cannot decelerate the relativistic jet to cause a sharp break within days, the wind termination shock due to the ram pressure balance by surrounding medium occurs at a small radius, i.e. several times $10^{17}$ cm. The jet will pass through the wind environment within several hours and run into the outer uniform dense medium. The resulting optical light curve flattens with a shallowe...

  4. A DECADE-BASELINE STUDY OF THE PLASMA STATES OF EJECTA KNOTS IN CASSIOPEIA A

    Energy Technology Data Exchange (ETDEWEB)

    Rutherford, John; Dewey, Daniel; Figueroa-Feliciano, Enectali; Heine, Sarah N. T.; Canizares, C. R.; Bastien, Fabienne A.; Sato, Kosuke, E-mail: enectali@mit.edu, E-mail: jmrv@mit.edu [Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2013-05-20

    We present the analysis of 21 bright X-ray knots in the Cassiopeia A supernova remnant from observations spanning 10 yr. We performed a comprehensive set of measurements to reveal the kinematic and thermal state of the plasma in each knot, using a combined analysis of two high energy resolution High Energy Transmission Grating (HETG) and four medium energy resolution Advanced CCD Imaging Spectrometer (ACIS) sets of spectra. The ACIS electron temperature estimates agree with the HETG-derived values for approximately half of the knots studied, yielding one of the first comparisons between high resolution temperature estimates and ACIS-derived temperatures. We did not observe the expected spectral evolution-predicted from the ionization age and density estimates for each knot-in all but three of the knots studied. The incompatibility of these measurements with our assumptions has led us to propose a dissociated ejecta model, with the metals unmixed inside the knots, which could place strong constraints on supernova mixing models.

  5. HST Images Flash Ionization of Old Ejecta by the 2011 Eruption of Recurrent Nova T Pyxidis

    CERN Document Server

    Shara, Michael M; Schaefer, Bradley E; Bond, Howard E; Godon, Patrick; Mac Low, Mordecai-Mark; Pagnotta, Ashley; Prialnik, Dina; Sion, Edward M; Toraskar, Jayashree; Williams, Robert E

    2015-01-01

    T Pyxidis is the only recurrent nova surrounded by knots of material ejected in previous outbursts. Following the eruption that began on 2011 April 14.29, we obtained seven epochs (from 4 to 383 days after eruption) of Hubble Space Telescope narrowband Ha images of T Pyx . The flash of radiation from the nova event had no effect on the ejecta until at least 55 days after the eruption began. Photoionization of hydrogen located north and south of the central star was seen 132 days after the beginning of the eruption. That hydrogen recombined in the following 51 days, allowing us to determine a hydrogen atom density of at least 7e5 cm^-3 - at least an order of magnitude denser than the previously detected, unresolved [NII] knots surrounding T Pyx. Material to the northwest and southeast was photoionized between 132 and 183 days after the eruption began. 99 days later that hydrogen had recombined. Both then (282 days after outburst) and 101 days later, we detected almost no trace of hydrogen emission around T Pyx...

  6. Radioactivity and Thermalization in the Ejecta of Compact Object Mergers and Their Impact on Kilonova Light Curves

    Science.gov (United States)

    Barnes, Jennifer; Kasen, Daniel; Wu, Meng-Ru; Martínez-Pinedo, Gabriel

    2016-10-01

    One promising electromagnetic signature of compact object mergers are kilonovae: approximately isotropic radioactively powered transients that peak days to weeks post-merger. Key uncertainties in kilonova modeling include the emission profiles of the radioactive decay products—non-thermal β -particles, α -particles, fission fragments, and γ -rays—and the efficiency with which their kinetic energy is absorbed by the ejecta. The radioactive energy emitted, along with its thermalization efficiency, sets the luminosity budget and is therefore crucial for predicting kilonova light curves. We outline uncertainties in the radioactivity, describe the processes by which the decay products transfer energy to the ejecta, and calculate time-dependent thermalization efficiencies for each particle type. We determine the net thermalization efficiency and explore its dependence on r-process yields—in particular, the production of α -decaying translead nuclei—and on ejecta mass, velocity, and magnetic fields. We incorporate our results into detailed radiation transport simulations, and calculate updated kilonova light curve predictions. Thermalization effects reduce kilonova luminosities by a factor of roughly 2 at peak, and by an order of magnitude at later times (15 days or more after explosion). We present analytic fits to time-dependent thermalization efficiencies, which can be used to improve light curve models. We revisit the putative kilonova that accompanied gamma-ray burst 130603B, and estimate the mass ejected in that event. We find later time kilonova light curves can be significantly impacted by α -decay from translead isotopes; data at these times may therefore be diagnostic of ejecta abundances.

  7. Dynamical ejecta from precessing neutron star-black hole mergers with a hot, nuclear-theory based equation of state

    Science.gov (United States)

    Foucart, F.; Desai, D.; Brege, W.; Duez, M. D.; Kasen, D.; Hemberger, D. A.; Kidder, L. E.; Pfeiffer, H. P.; Scheel, M. A.

    2017-02-01

    Neutron star-black hole binaries are among the strongest sources of gravitational waves detectable by current observatories. They can also power bright electromagnetic signals (gamma-ray bursts, kilonovae), and may be a significant source of production of r-process nuclei. A misalignment of the black hole spin with respect to the orbital angular momentum leads to precession of that spin and of the orbital plane, and has a significant effect on the properties of the post-merger remnant and of the material ejected by the merger. We present a first set of simulations of precessing neutron star-black hole mergers using a hot, composition dependent, nuclear-theory based equation of state (DD2). We show that the mass of the remnant and of the dynamical ejecta are broadly consistent with the result of simulations using simpler equations of state, while differences arise when considering the dynamics of the merger and the velocity of the ejecta. We show that the latter can easily be understood from assumptions about the composition of low-density, cold material in the different equations of state, and propose an updated estimate for the ejecta velocity which takes those effects into account. We also present an updated mesh-refinement algorithm which allows us to improve the numerical resolution used to evolve neutron star-black hole mergers.

  8. Experimental study on the ejecta-velocity distributions caused by low-velocity impacts on quartz sand

    Science.gov (United States)

    Tsujido, S.; Arakawa, M.; Suzuki, A. I.; Yasui, M.

    2014-07-01

    Introduction: Regolith formation on asteroids is caused by successive impacts of small bodies. The ejecta velocity distribution during the crater formation process is one of the most important physical properties related to the surface-evolution process, and the distribution is also necessary to reconstruct the planetary-accretion process among planetesimals. The surface of small bodies, such as asteroids and planetesimals in the solar system, could have varying porosity, strength, and density, and the impact velocity could vary across a wide range from a few tens of m/s to several km/s. Therefore, it is necessary to conduct impact experiments by changing the physical properties of the target and the projectile in a wide velocity range in order to constrain the crater-formation process applicable to the small bodies in the solar system. Housen and Holsapple (2011) compiled the data of ejecta velocity distribution with various impact velocities, porosities, grain sizes, grain shapes, and strengths of the targets, and they improved their ejecta scaling law. But the ejecta velocity data is not enough for varying projectile densities and for impact velocities less than 1 km/s. In this study, to investigate the projectile density dependence of the ejecta velocity distribution at a low velocity region, we conducted impact experiments with projectile densities from 1.1 to 11.3 g/cm^3. Then, we try to determine the effect of projectile density on the ejecta velocity distribution by means of the observation of each individual ejecta grain. Experimental methods: We made impact cratering experiments by using a vertical-type one-stage light-gas gun (V-LGG) set at Kobe University. Targets were quartz sand (irregular shape) and glass beads (spherical shape) with the grain size of 500 μ m (porosity 44.7 %). The target container with the size of 30 cm was set in a large vacuum chamber with air pressure less than 10^3 Pa. The projectile materials that we used were lead, copper

  9. Role of ejecta clumping and back-reaction of accelerated cosmic rays in the evolution of Type Ia supernova remnants

    CERN Document Server

    Orlando, S; Miceli, M; Petruk, O; Pumo, M L

    2012-01-01

    We investigate the role played by initial clumping of ejecta and by efficient acceleration of cosmic rays (CRs) in determining the density structure of the post-shock region of a Type Ia supernova remnant (SNR) through detailed 3D MHD modeling. Our model describes the expansion of a SNR through a magnetized interstellar medium (ISM), including the initial clumping of ejecta and the effects on shock dynamics due to back-reaction of accelerated CRs. The model predictions are compared to the observations of SN 1006. We found that the back-reaction of accelerated CRs alone cannot reproduce the observed separation between the forward shock (FS) and the contact discontinuity (CD) unless the energy losses through CR acceleration and escape are very large and independent of the obliquity angle. On the contrary, the clumping of ejecta can naturally reproduce the observed small separation and the occurrence of protrusions observed in SN 1006, even without the need of accelerated CRs. We conclude that FS-CD separation i...

  10. Multiphase flow modelling of explosive volcanic eruptions using adaptive unstructured meshes

    Science.gov (United States)

    Jacobs, Christian T.; Collins, Gareth S.; Piggott, Matthew D.; Kramer, Stephan C.

    2014-05-01

    from the sudden high-velocity inflow of gas and ash; the formation of a particle-laden plume rising several hundred metres into the atmosphere; the eventual collapse of the plume which generates a volcanic ash fountain and a fast ground-hugging pyroclastic density current; and the growth of a dilute convective region that rises above the ash fountain as a result of buoyancy effects. The results from Fluidity are also compared with results from MFIX, a fixed structured mesh-based multiphase flow code, that uses the same set-up. The key flow features are also captured in MFIX, providing at least some confidence in the plausibility of the numerical results in the absence of quantitative field data. Finally, it is shown by a convergence analysis that Fluidity offers the same solution accuracy for reduced computational cost using an adaptive mesh, compared to the same simulation performed with a uniform fixed mesh.

  11. Indications of a Si-rich bilateral jet of ejecta in the Vela SNR observed with XMM-Newton

    Science.gov (United States)

    García, F.; Suárez, A. E.; Miceli, M.; Bocchino, F.; Combi, J. A.; Orlando, S.; Sasaki, M.

    2017-08-01

    Context. The Vela supernova remnant displays several ejecta, which are fragment-like features protruding beyond the front of its primary blast shock wave. They appear to be "shrapnel", bowshock-shaped relics of the supernova explosion. One of these pieces of shrapnel (A), located in the northeastern edge of the remnant, is peculiar because its X-ray spectrum exhibits a high Si abundance, in contrast to the other observed ejecta fragments, which show enhanced O, Ne, and Mg abundances. Aims: In this Letter we present the analysis of another ejecta fragment located opposite to shrapnel A with respect to the center of the shell, in the southwestern boundary of the remnant, named shrapnel G. We aim to fully characterize its X-ray emission to gather new information about the core-collapse supernova explosion mechanism. Methods: We thoroughly analyzed a dedicated XMM-Newton observation of shrapnel G by producing background-subtracted and exposure-corrected maps in different energy ranges, which we complemented with a spatially resolved spectral analysis of the X-ray emission. Results: The fragment presents a bowshock-like shape with its anti-apex pointing to the center of the remnant. Its X-ray spectrum is best fit by a thermal plasma out of equilibrium of ionization with low O and Fe, roughly solar Ne and Mg, and a significantly high Si abundance, which is required to fit a very clear Si line at 1.85 keV. Its chemical composition and spectral properties are compatible with those of shrapnel A, which is located on the opposite side of the remnant. Conclusions: As a consequence of the nucleosynthesis, pieces of Si-rich shrapnel are expected to originate in deeper layers of the progenitor star compared to ejecta with lower-Z elements. A high velocity and density contrast with respect to the surrounding ejecta are necessary to make shrapnel A and G overtake the forward shock. The line connecting shrapnel A and G crosses almost exactly the expansion center of the remnant

  12. Perfect fluid flow from granular jet impact

    CERN Document Server

    Ellowitz, Jake; Zhang, Wendy W

    2012-01-01

    Experiments on the impact of a densely-packed jet of non-cohesive grains onto a fixed target show that the impact produces an ejecta sheet comprised of particles in collimated motion. The ejecta sheet leaves the target at a well-defined angle whose value agrees quantitatively with the sheet angle produced by water jet impact. Motivated by these experiments, we examine the idealized problem of dense granular jet impact onto a frictionless target in two dimensions. Numerical results for the velocity and pressure fields within the granular jet agree quantitatively with predictions from an exact solution for 2D perfect-fluid impact. This correspondence demonstrates that the continuum limit controlling the coherent collective motion in dense granular impact is Euler flow.

  13. TYPE Ia SUPERNOVA COLORS AND EJECTA VELOCITIES: HIERARCHICAL BAYESIAN REGRESSION WITH NON-GAUSSIAN DISTRIBUTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Mandel, Kaisey S.; Kirshner, Robert P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Foley, Ryan J., E-mail: kmandel@cfa.harvard.edu [Astronomy Department, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States)

    2014-12-20

    We investigate the statistical dependence of the peak intrinsic colors of Type Ia supernovae (SNe Ia) on their expansion velocities at maximum light, measured from the Si II λ6355 spectral feature. We construct a new hierarchical Bayesian regression model, accounting for the random effects of intrinsic scatter, measurement error, and reddening by host galaxy dust, and implement a Gibbs sampler and deviance information criteria to estimate the correlation. The method is applied to the apparent colors from BVRI light curves and Si II velocity data for 79 nearby SNe Ia. The apparent color distributions of high-velocity (HV) and normal velocity (NV) supernovae exhibit significant discrepancies for B – V and B – R, but not other colors. Hence, they are likely due to intrinsic color differences originating in the B band, rather than dust reddening. The mean intrinsic B – V and B – R color differences between HV and NV groups are 0.06 ± 0.02 and 0.09 ± 0.02 mag, respectively. A linear model finds significant slopes of –0.021 ± 0.006 and –0.030 ± 0.009 mag (10{sup 3} km s{sup –1}){sup –1} for intrinsic B – V and B – R colors versus velocity, respectively. Because the ejecta velocity distribution is skewed toward high velocities, these effects imply non-Gaussian intrinsic color distributions with skewness up to +0.3. Accounting for the intrinsic-color-velocity correlation results in corrections to A{sub V} extinction estimates as large as –0.12 mag for HV SNe Ia and +0.06 mag for NV events. Velocity measurements from SN Ia spectra have the potential to diminish systematic errors from the confounding of intrinsic colors and dust reddening affecting supernova distances.

  14. Rotation periods of binary asteroids with large separations - Confronting the Escaping Ejecta Binaries model with observations

    Science.gov (United States)

    Polishook, D.; Brosch, N.; Prialnik, D.

    2011-03-01

    Durda et al. (Durda, D.D., Bottke, W.F., Enke, B.L., Merline, W.J., Asphaug, E., Richardson, D.C., Leinhardt, Z.M. [2004]. Icarus 170, 243-257), using numerical models, suggested that binary asteroids with large separation, called Escaping Ejecta Binaries (EEBs), can be created by fragments ejected from a disruptive impact event. It is thought that six binary asteroids recently discovered might be EEBs because of the high separation between their components (∼100 > a/Rp > ∼20). However, the rotation periods of four out of the six objects measured by our group and others and presented here show that these suspected EEBs have fast rotation rates of 2.5-4 h. Because of the small size of the components of these binary asteroids, linked with this fast spinning, we conclude that the rotational-fission mechanism, which is a result of the thermal YORP effect, is the most likely formation scenario. Moreover, scaling the YORP effect for these objects shows that its timescale is shorter than the estimated ages of the three relevant Hirayama families hosting these binary asteroids. Therefore, only the largest (D ∼ 19 km) suspected asteroid, (317) Roxane, could be, in fact, the only known EEB. In addition, our results confirm the triple nature of (3749) Balam by measuring mutual events on its lightcurve that match the orbital period of a nearby satellite in addition to its distant companion. Measurements of (1509) Esclangona at different apparitions show a unique shape of the lightcurve that might be explained by color variations.

  15. NEUTRON-STAR MERGER EJECTA AS OBSTACLES TO NEUTRINO-POWERED JETS OF GAMMA-RAY BURSTS

    Energy Technology Data Exchange (ETDEWEB)

    Just, O.; Janka, H.-T.; Schwarz, N. [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching (Germany); Obergaulinger, M. [Departament d´Astronomia i Astrofísica, Universitat de València, Edifici d´Investigació Jeroni Muñoz, C/ Dr. Moliner, 50, E-46100 Burjassot (València) (Spain); Bauswein, A., E-mail: ojust@mpa-garching.mpg.de, E-mail: thj@mpa-garching.mpg.de [Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)

    2016-01-10

    We present the first special relativistic, axisymmetric hydrodynamic simulations of black hole-torus systems (approximating general relativistic gravity) as remnants of binary-neutron star (NS–NS) and neutron star–black hole (NS–BH) mergers, in which the viscously driven evolution of the accretion torus is followed with self-consistent energy-dependent neutrino transport and the interaction with the cloud of dynamical ejecta expelled during the NS–NS merging is taken into account. The modeled torus masses, BH masses and spins, and the ejecta masses, velocities, and spatial distributions are adopted from relativistic merger simulations. We find that energy deposition by neutrino annihilation can accelerate outflows with initially high Lorentz factors along polar low-density funnels, but only in mergers with extremely low baryon pollution in the polar regions. NS–BH mergers, where polar mass ejection during the merging phase is absent, provide sufficiently baryon-poor environments to enable neutrino-powered, ultrarelativistic jets with terminal Lorentz factors above 100 and considerable dynamical collimation, favoring short gamma-ray bursts (sGRBs), although their typical energies and durations might be too small to explain the majority of events. In the case of NS–NS mergers, however, neutrino emission of the accreting and viscously spreading torus is too short and too weak to yield enough energy for the outflows to break out from the surrounding ejecta shell as highly relativistic jets. We conclude that neutrino annihilation alone cannot power sGRBs from NS–NS mergers.

  16. Impact of weak interactions of free nucleons on the r-process in dynamical ejecta from neutron star mergers

    Science.gov (United States)

    Goriely, S.; Bauswein, A.; Just, O.; Pllumbi, E.; Janka, H.-Th.

    2015-10-01

    We investigate β-interactions of free nucleons and their impact on the electron fraction (Ye) and r-process nucleosynthesis in ejecta characteristic of binary neutron star mergers (BNSMs). For that we employ trajectories from a relativistic BNSM model to represent the density-temperature evolutions in our parametric study. In the high-density environment, positron captures decrease the neutron richness at the high temperatures predicted by the hydrodynamic simulation. Circumventing the complexities of modelling three-dimensional neutrino transport, (anti)neutrino captures are parametrized in terms of prescribed neutrino luminosities and mean energies, guided by published results and assumed as constant in time. Depending sensitively on the adopted νe-bar{ν }_e luminosity ratio, neutrino processes increase Ye to values between 0.25 and 0.40, still allowing for a successful r-process compatible with the observed solar abundance distribution and a significant fraction of the ejecta consisting of r-process nuclei. If the νe luminosities and mean energies are relatively large compared to the bar{ν }_e properties, the mean Ye might reach values >0.40 so that neutrino captures seriously compromise the success of the r-process. In this case, the r-abundances remain compatible with the solar distribution, but the total amount of ejected r-material is reduced to a few per cent, because the production of iron-peak elements is favoured. Proper neutrino physics, in particular also neutrino absorption, have to be included in BNSM simulations before final conclusions can be drawn concerning r-processing in this environment and concerning observational consequences like kilonovae, whose peak brightness and colour temperature are sensitive to the composition-dependent opacity of the ejecta.

  17. Probing the Physical Conditions of Supernova Ejecta with the Measured Sizes of Presolar Al2O3 Grains

    OpenAIRE

    2015-01-01

    A few particles of presolar Al2O3 grains with sizes above 0.5 mum are believed to have been produced in the ejecta of core-collapse supernovae (SNe). In order to clarify the formation condition of such large Al2O3 grains, we investigate the condensation of Al2O3 grains for wide ranges of the gas density and cooling rate. We first show that the average radius and condensation efficiency of newly formed Al2O3 grains are successfully described by a non-dimensional quantity "Lambda_on" defined as...

  18. The disposition of impact ejecta resulting from the AIDA-DART mission to binary asteroid 65803 Didymos: an independent investigation

    Science.gov (United States)

    Richardson, James E.; O'Brien, David P.

    2016-10-01

    If all goes as planned, in the year 2020 a joint ESA and NASA mission will be launched that will rendezvous with the near-Earth binary asteroid system 65803 Didymos in the fall of 2022. The European component, the Asteroid Impact & Deflection Assessment (AIDA) spacecraft will arrive first and characterize the system, which consists of a ~800 m diameter primary and a ~160 m diameter secondary, orbiting a common center of mass at a semi-major axis distance of ~1200 m with a orbital period of 11.9 hr. Following system characterization, the AIDA spacecraft will remove to a safe distance while the NASA component, the 300 kg Double Asteroid Redirection Test (DART) spacecraft collides with the trailing edge of the secondary body (with respect to the binary's retrograde mutual orbit). Meanwhile, the AIDA spacecraft will conduct observations of this impact and its aftermath, specifically looking for changes made to the primary, the secondary, and their mutual orbit as a result of the DART collision. Of particular interest is the ballistic flight and final disposition of the ejecta produced by the impact cratering process, not just from the standpoint of scientific study, but also from the standpoint of AIDA spacecraft safety.In this study, we investigate a series of hypothetical DART impacts utilizing a semi-empirical, numerical impact ejecta plume model originally developed for the Deep Impact mission and designed specifically with impacts on small bodies in mind. The resulting excavated mass is discretized into 7200 individual tracer particles, each representing a unique combination of speed, mass, and ejected direction. The trajectory of each tracer is computed numerically under the gravitational influence of both primary and secondary, along with the effects of solar radiation pressure. Each tracer is followed until it either impacts a body or escapes the system, whereupon tracking is continued in the heliocentric frame using an N-body integrator. Various impact

  19. GK Per (Nova Persei 1901): HST Imagery and Spectroscopy of the Ejecta, and First Spectrum of the Jet-Like Feature

    CERN Document Server

    Shara, Michael M; De Marco, Orsola; Mizusawa, Trisha; Williams, Robert; Livio, Mario

    2012-01-01

    We have imaged the ejecta of GK Persei (Nova Persei 1901 A.D.) with the Hubble Space Telescope (HST), revealing hundreds of cometary-like structures. One or both ends of the structures often show a brightness enhancement relative to the structures' middle sections, but there is no simple regularity to their morphologies (in contrast with the Helix nebula). Some of the structures' morphologies suggest the presence of slow-moving or stationary material with which the ejecta is colliding, while others suggest shaping from a wind emanating from GK Per itself. A detailed expansion map of the nova's ejecta was created by comparing HST images taken in successive years. WFPC2 narrowband images and STIS spectra demonstrate that the physical conditions in the ejecta vary strongly on spatial scales much smaller than those of the ejecta. Directly measuring accurate densities and compositions, and hence masses of this and other nova shells, will demand data at least as resolved spatially as those presented here. The filli...

  20. Flow Fields at Tooting Crater, Mars

    Science.gov (United States)

    Mouginis-Mark, P. J.; Garbeil, H.

    2007-12-01

    HiRISE images of the impact crater Tooting (~29 km dia., located at 23.4°N, 207.5°E) on Mars have revealed a remarkable series of lobate flows on the southern rim, wall and floor of the crater. The origin of these flows has not yet been determined, but their spatial distribution and morphology could indicate that they are flows of impact melt, mudflows, or lava flows. Tooting crater shows numerous signs of being very young (very few superposed impact craters, very high depth/diameter ratio, high thermal inertia ejecta, and a well preserved set of secondary craters), and so allows detailed analysis of these unusual flows, which appear to be almost pristine. We have developed a 2-meter digital elevation model of Tooting using stereo HiRISE images to characterize the flows, which in general are relief close to the crater rim crest. Five discrete segments of this flow exist, including a 1.3 km segment with a discrete 15 m wide central channel and three lobate distal margins. (3) A set of 7 lobes ~700 m long on the inner S wall. These lobes have very well defined central channels ~25 m wide and levees 30 m thick and 300 m wide. These flows no doubt formed in an unusual environment, probably including extensive amounts of impact melt, volatiles released from the substrate, and highly unstable slopes on the crater rim. Tooting crater therefore displays a novel planetary flow field; the correct identification of the origin of these flows holds significance for understanding the role of volatiles in the impact cratering process, the potential of thermal anomalies existing within the crater cavity for extended period of time, and the emplacement of the ejecta. We are therefore developing numerical models, based on the rheology of lava flows, in order to help to resolve the origin of this flow field.

  1. Neutron-star merger ejecta as obstacles to neutrino-powered jets of gamma-ray bursts

    CERN Document Server

    Just, Oliver; Janka, H -Thomas; Bauswein, Andreas; Schwarz, Nicole

    2015-01-01

    We present the first relativistic hydrodynamic simulations of black hole-torus systems as remnants of binary-neutron star (NS-NS) and neutron star-black hole (NS-BH) mergers, in which the viscously driven evolution of the accretion torus is followed with a self-consistent treatment of the energy-dependent neutrino transport and of neutrino-antineutrino annihilation, which initiates relativistic, collimated outflows above the poles of the BH. Moreover, we include the interaction of these polar outflows with the dynamical ejecta that are expelled during the NS-NS merging. The modeled torus masses, BH masses and spins, and the ejecta masses, velocities, and spatial distributions are adopted from relativistic merger simulations. We find that energy deposition by neutrino annihilation can accelerate outflows with initially high Lorentz factors along polar low-density funnels, but only in mergers with extremely low baryon pollution in the polar regions. NS-BH mergers, where polar mass ejection during the merging ph...

  2. Fe K and ejecta emission in SNR G15.9+0.2 with XMM-Newton

    CERN Document Server

    Maggi, Pierre

    2016-01-01

    Aims: We present a study of the Galactic supernova remnant SNR G15.9+0.2 with archival XMM-Newton observations. Methods: EPIC data are used to investigate the morphological and spectral properties of the remnant, searching in particular for supernova ejecta and Fe K line emission. By comparing the SNR's X-ray absorption column density with the atomic and molecular gas distribution along the line of sight, we attempt to constrain the distance to the SNR. Results: Prominent line features reveal the presence of ejecta. Abundance ratios of Mg, Si, S, Ar, and Ca strongly suggest that the progenitor of SNR G15.9+0.2 was a massive star with a main sequence mass likely in the range 20-25 $M_{\\odot}$, strengthening the physical association with a candidate central compact object detected with Chandra. Using EPIC's collective power, Fe K line emission from SNR G15.9+0.2 is detected for the first time. We measure the line properties and find evidence for spatial variations. We discuss how the source fits within the samp...

  3. The Type Ic SN 2007gr: a census of the ejecta from late-time optical-infrared spectra

    CERN Document Server

    Mazzali, P A; Valenti, S; Kotak, R; Hunter, D

    2010-01-01

    Nebular spectra of Supernovae (SNe) offer an unimpeded view of the inner region of the ejecta, where most nucleosynthesis takes place. Optical spectra cover most, but not all of the emitting elements, and therefore offer only a partial view of the products of the explosion. Simultaneous optical-infrared spectra, on the other hand, contain emission lines of all important elements, from C and O through to the Intermediate Mass Elements (IME) Mg, Si, S, Ca, and to Fe and Ni. In particular, Si and S are best seen in the IR. The availability of IR data makes it possible to explore in greater detail the results of the explosion. SN\\,2007gr is the first Type Ic SN for which such data are available. Modelling the spectra with a NLTE code reveals that the inner ejecta contain $\\sim 1 \\Msun$ of material within a velocity of $\\approx 4500$\\,\\kms. %The spectrum is powered by \\Nifs, in an amount ($0.076 \\Msun$) consistent with that %derived from the early-time data. The same mass of \\Nifs\\ derived from the light curve pea...

  4. Inferring supernova IIb/Ib/Ic ejecta properties from light curves and spectra: Correlations from radiative-transfer models

    CERN Document Server

    Dessart, Luc; Woosley, Stan; Livne, Eli; Waldman, Roni; Yoon, Sung-Chul; Langer, Norbert

    2016-01-01

    We present 1-D non-Local-Thermodynamic-Equilibrium time-dependent radiative-transfer simulations for a large grid of supernovae (SNe) IIb/Ib/Ic that result from the terminal explosion of the mass donor in a close-binary system. Our sample covers ejecta masses $M_{\\rm e}$ of 1.7$-$5.2M$_\\odot$, kinetic energies $E_{\\rm kin}$ of 0.6$-$5.0$\\times$10$^{51}$erg, and $^{56}$Ni masses of 0.05$-$0.30M$_\\odot$. We find a strong correlation between the $^{56}$Ni mass and the photometric properties at maximum, and between the rise time to bolometric maximum and the post-maximum decline rate. We confirm the small scatter in ($V-R$) at 10d past $R$-band maximum. The quantity $V_{\\rm m} \\equiv \\sqrt{2E_{\\rm kin}/M_{\\rm e}}$ is comparable to the Doppler velocity measured from HeI 5875\\AA\\ at maximum in SNe IIb/Ib, although some scatter arises from the uncertain level of chemical mixing. The OI7772\\AA\\ line may be used for SNe Ic, but the correspondence deteriorates with higher ejecta mass/energy. We identify a temporal reve...

  5. Dynamical ejecta from precessing neutron star-black hole mergers with a hot, nuclear-theory based equation of state

    CERN Document Server

    Foucart, Francois; Brege, Wyatt; Duez, Matthew D; Kasen, Daniel; Hemberger, Daniel A; Kidder, Lawrence E; Pfeiffer, Harald P; Scheel, Mark A

    2016-01-01

    Neutron star-black hole binaries are among the strongest sources of gravitational waves detectable by current observatories. They can also power bright electromagnetic signals (gamma-ray bursts, kilonovae), and may be a significant source of production of r-process nuclei. A misalignment of the black hole spin with respect to the orbital angular momentum leads to precession of that spin and of the orbital plane, and has a significant effect on the properties of the post-merger remnant and of the material ejected by the merger. We present a first set of simulations of precessing neutron star-black hole mergers using a hot, composition dependent, nuclear-theory based equation of state (DD2). We show that the mass of the remnant and of the dynamical ejecta are broadly consistent with the result of simulations using simpler equations of state, while differences arise when considering the dynamics of the merger and the velocity of the ejecta. We show that the latter can easily be understood from assumptions about ...

  6. Three-dimensional simulations of the interaction between Type Ia supernova ejecta and their main sequence companions

    CERN Document Server

    Liu, Z W; Roepke, F K; Edelmann, P; Wang, B; Kromer, M; Hillebrandt, W; Han, Z W

    2012-01-01

    The identity of the progenitor systems of SNe Ia is still uncertain. In the single-degenerate (SD) scenario, the interaction between the SN blast wave and the outer layers of a main sequence (MS) companion star strips off H-rich material which is then mixed into the ejecta. Strong contamination of the SN ejecta with stripped material could lead to a conflict with observations of SNe Ia. This constrains the SD progenitor model. In this work, our previous simulations based on simplified progenitor donor stars have been updated by adopting more realistic progenitor-system models that result from fully detailed, state-of-the-art binary evolution calculations. We use Eggleton's stellar evolution code including the optically thick accretion wind model and the possibility of the effects of accretion disk instabilities to obtain realistic models of companions for different progenitor systems. The impact of the SN blast wave on these companion stars is followed in three-dimensional hydrodynamic simulations employing t...

  7. GK Per (Nova Persei 1901): HUBBLE SPACE TELESCOPE IMAGERY AND SPECTROSCOPY OF THE EJECTA, AND FIRST SPECTRUM OF THE JET-LIKE FEATURE

    Energy Technology Data Exchange (ETDEWEB)

    Shara, Michael M.; Zurek, David; Mizusawa, Trisha [Department of Astrophysics, American Museum of Natural History, Central Park West and 79th street, New York, NY 10024-5192 (United States); De Marco, Orsola [Department of Physics, Macquarie University, Sydney (Australia); Williams, Robert; Livio, Mario [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2012-06-15

    We have imaged the ejecta of GK Persei (Nova Persei 1901 A.D.) with the Hubble Space Telescope (HST), whose 0.1 arcsec resolution reveals hundreds of cometary-like structures with long axes aligned toward GK Per. One or both ends of the structures often show a brightness enhancement relative to the structures' middle sections, but there is no simple regularity to their morphologies (in contrast with, for example, the Helix nebula). Some of structures' morphologies suggest the presence of slow-moving or stationary material with which the ejecta is colliding, while others suggest shaping from a wind emanating from GK Per itself. The most detailed expansion map of any classical nova's ejecta was created by comparing HST images taken in successive years. Wide Field and Planetary Camera 2 narrowband images and Space Telescope Imaging Spectrograph spectra demonstrate that the physical conditions in this nova's ejecta vary strongly on spatial scales much smaller than those of the ejecta. Directly measuring accurate densities and compositions, and hence masses of this and other nova shells, will demand data at least as resolved spatially as those presented here. The filling factor of the ejecta is 1% or less, and the nova ejecta mass must be less than 10{sup -4} M{sub Sun }. A modest fraction of the emission nebulosities vary in brightness by up to a factor of two on timescales of one year. Finally, we present the deepest images yet obtained of a jet-like feature outside the main body of GK Per nebulosity, and the first spectrum of that feature. Dominated by strong, narrow emission lines of [N II], [O II], [O III], and [S II], this feature is probably a shock due to ejected material running into stationary interstellar matter, slowly moving ejecta from a previous nova episode, or circumbinary matter present before 1901. An upper limit to the mass of the jet is of order a few times 10{sup -6} M{sub Sun }. If the jet mass is close to this limit then the

  8. A solar-type star polluted by calcium-rich supernova ejecta inside the supernova remnant RCW 86

    Science.gov (United States)

    Gvaramadze, Vasilii V.; Langer, Norbert; Fossati, Luca; Bock, Douglas C.-J.; Castro, Norberto; Georgiev, Iskren Y.; Greiner, Jochen; Johnston, Simon; Rau, Arne; Tauris, Thomas M.

    2017-06-01

    When a massive star in a binary system explodes as a supernova, its companion star may be polluted with heavy elements from the supernova ejecta. Such pollution has been detected in a handful of post-supernova binaries 1 , but none of them is associated with a supernova remnant. We report the discovery of a binary G star strongly polluted with calcium and other elements at the position of the candidate neutron star [GV2003] N within the young galactic supernova remnant RCW 86. Our discovery suggests that the progenitor of the supernova that produced RCW 86 could have been a moving star, which exploded near the edge of its wind bubble and lost most of its initial mass because of common-envelope evolution shortly before core collapse, and that the supernova explosion might belong to the class of calcium-rich supernovae — faint and fast transients 2,3 , the origin of which is strongly debated 4-6 .

  9. The Influence of Neutrinos on r-Process Nucleosynthesis in the Ejecta of Black Hole-Neutron Star Mergers

    CERN Document Server

    Roberts, Luke F; Duez, Matthew D; Faber, Joshua A; Foucart, Francois; Lombardi, James C; Ning, Sandra; Ott, Christian D; Ponce, Marcelo

    2016-01-01

    During the merger of a black hole and a neutron star, baryonic mass can become unbound from the system. Because the ejected material is extremely neutron-rich, the r-process rapidly synthesizes heavy nuclides as the material expands and cools. In this work, we map general relativistic models of black hole-neutron star (BHNS) mergers into a Newtonian smoothed particle hydrodynamics (SPH) code and follow the evolution of the thermodynamics and morphology of the ejecta until the outflows become homologous. We investigate how the subsequent evolution depends on our mapping procedure and find that the results are robust. Using thermodynamic histories from the SPH particles, we then calculate the expected nucleosynthesis in these outflows while varying the level of neutrino irradiation coming from the postmerger accretion disk. We find that the ejected material robustly produces r-process nucleosynthesis even for unrealistically high neutrino luminosities, due to the rapid velocities of the outflow. Nonetheless, we...

  10. Thermal X-ray emission from shocked ejecta in Type Ia Supernova Remnants. Prospects for explosion mechanism identification

    CERN Document Server

    Badenes, C; Borkowski, K J; Dominguez, I; Badenes, Carles; Bravo, Eduardo; Borkowski, Kazimierz J.; Dominguez, Inmaculada

    2003-01-01

    The explosion mechanism behind Type Ia supernovae is a matter of continuing debate. The diverse attempts to identify or at least constrain the physical processes involved in the explosion have been only partially successful so far. In this paper we propose to use the thermal X-ray emission from young supernova remnants originated in Type Ia events to extract relevant information concerning the explosions themselves. We have produced a grid of thermonuclear supernova models representative of the paradigms currently under debate: pure deflagrations, delayed detonations, pulsating delayed detonations and sub-Chandrasekhar explosions, using their density and chemical composition profiles to simulate the interaction with the surrounding ambient medium and the ensuing plasma heating, non-equilibrium ionization and thermal X-ray emission of the ejecta. Key observational parameters such as electron temperatures, emission measures and ionization time scales are presented and discussed. We find that not only is it poss...

  11. Analysis of ejecta fate from proposed man-made impactors into near-Earth objects --- a NEOShield study

    Science.gov (United States)

    Schwartz, S.; Michel, P.; Jutzi, M.

    2014-07-01

    Asteroids measuring 100 meters across tend to impact the Earth once every 5,000 years on average [1]. Smaller bodies enter into the Earth's atmosphere more frequently, but may detonate before reaching the surface. Conversely, impacts from larger bodies are more rare [2], but can come with devastating global consequences to living species. In 2005, a United States Congressional mandate called for NASA to detect, by 2020, 90 percent of near-Earth objects (NEOs) having diameters of 140 meters or greater [3]. One year prior, ESA's Near-Earth Object Mission Advisory Panel (NEOMAP) recommended the study of a kinetic impactor mission as a priority in the framework of NEO risk assessment [4]. A ''Phase-A'' study of such a mission, Don Quixote, took place at ESA until 2007. In accordance with NEOMAP and with the Target NEO Global Community's recommendations in 2011 [5], the NEOShield Project is being funded for 3.5 years by the European Commission in its FP7 program. NEOShield began in 2012 and is primarily, but not exclusively, a European consortium of research institutions and engineering industries that aims to analyze promising mitigation options and provide solutions to the critical scientific and technical obstacles involved in confronting threats posed by the small bodies in the neighborhood of the Earth's orbit [6]. To further explore the NEO threat mitigation via the strategy of kinetic impact, building upon the Don Quixote study, the idea is to target a specific NEO for impact and attempt to quantify the response. How long do ejecta remain aloft and where do they end up? Fragments that are ejected at high speeds escape, but what about material moving at or near the escape speed of the NEO or that suffer energy-dissipating collisions after being ejected? Where would be a ''safe'' location for an observing spacecraft during and subsequent to the impact? Here, we outline the early phases of an ongoing numerical investigation of the fate of the material ejected from a

  12. Analysis of the flux and polarization spectra of the type Ia supernova SN 2001el: Exploring the geometry of the high-velocity Ejecta

    Energy Technology Data Exchange (ETDEWEB)

    Kasen, Daniel; Nugent, Peter; Wang, Lifan; Howell, D.A.; Wheeler, J. Craig; Hoeflich, Peter; Baade, Dietrich; Baron, E.; Hauschildt, P.H.

    2003-01-15

    SN 2001el is the first normal Type Ia supernova to show a strong, intrinsic polarization signal. In addition, during the epochs prior to maximum light, the CaII IR triplet absorption is seen distinctly and separately at both normal photospheric velocities and at very high velocities. The unusual, high-velocity triplet absorption is highly polarized, with a different polarization angle than the rest of the spectrum. The unique observation allows us to construct a relatively detailed picture of the layered geometrical structure of the supernova ejecta: in our interpretation, the ejecta layers near the photosphere (v approximately 10,000 km/s) obey a near axial symmetry, while a detached, high-velocity structure (v approximately 18,000-25,000 $ km/s) of CaII line opacity deviates from the photospheric axisymmetry. By partially obscuring the underlying photosphere, the high-velocity structure causes a more incomplete cancellation of the polarization of the photospheric light, and so gives rise to the polarization peak of the high-velocity IR triplet feature. In an effort to constrain the ejecta geometry, we develop a technique for calculating 3-D synthetic polarization spectra and use it to generate polarization profiles for several parameterized configurations. In particular, we examine the case where the inner ejecta layers are ellipsoidal and the outer, high-velocity structure is one of four possibilities: a spherical shell, an ellipsoidal shell, a clumped shell, or a toroid. The synthetic spectra rule out the clearly discriminated if observations are obtained from several different lines of sight. Thus, assuming the high velocity structure observed for SN 2001el is a consistent feature of at least known subset of type Ia supernovae, future observations and analyses such as these may allow one to put strong constraints on the ejecta geometry and hence on supernova progenitors and explosion mechanisms.

  13. Fingerprinting the K/T impact site and determining the time of impact by U-Pb dating of single shocked zircons from distal ejecta

    Science.gov (United States)

    Krogh, T. E.; Kamo, S. L.; Bohor, B. F.

    1993-01-01

    U-Pb isotopic dating of single 1 - 3 micrograms zircons from K/T distal ejecta from a site in the Raton Basin, Colorado provides a powerful new tool with which to determine both the time of the impact event and the age of the basement at the impact site. Data for the least shocked zircons are slightly displaced from the 544 +/- 5 Ma primary age for a component of the target site, while those for highly shocked and granular grains are strongly displaced towards the time of impact at 65.5 +/- 3.0 Ma. Such shocked and granular zircons have never been reported from any source, including explosive volcanic rocks. Zircon is refractory and has one of the highest thermal blocking temperatures; hence, it can record both shock features and primary and secondary ages without modification by post-crystallization processes. Unlike shocked quartz, which can come from almost anywhere on the Earth's crust, shocked zircons can be shown to come from a specific site because basement ages vary on the scale of meters to kilometers. With U-Pb zircon dating, it is now possible to correlate ejecta layers derived from the same target site, test the single versus multiple impact hypothesis, and identify the target source of impact ejecta. The ages obtained in this study indicate that the Manson impact site, Iowa, which has basement rocks that are mid-Proterozoic in age, cannot be the source of K/T distal ejecta. The K/T distal ejecta probably originated from a single impact site because most grains have the same primary age.

  14. Near infrared spectroscopy of the type IIn SN 2010jl: evidence for high velocity ejecta

    CERN Document Server

    Borish, H Jacob; Chevalier, Roger A; Breslauer, Benjamin M; Kingery, Aaron M; Privon, George C

    2014-01-01

    The Type IIn supernova SN 2010jl was relatively nearby and luminous, allowing detailed studies of the near-infrared (NIR) emission. We present 1-2.4 micron spectroscopy over the age range of 36 to 565 days from the earliest detection of the supernova. On day 36, the Paschen H lines show an unresolved emission component along with a symmetric broad component that can be modeled as the result of electron scattering by a thermal distribution of electrons. Over the next hundreds of days, the broad components of the H lines shift to the blue by 700 km/s, as is also observed in optical lines. The narrow lines do not show a shift, indicating they originate in a different region. He I 10830 and 20587 lines both show an asymmetric broad emission component, with a shoulder on the blue side that varies in prominence and velocity from -5500 km/s on day 108 to -4000 km/s on day 219. This component may be associated with the higher velocity flow indicated by X-ray observations of the supernova. The absence of the feature i...

  15. Nano particles as the primary cause for long-term sunlight suppression at high southern latitudes following the Chicxulub impact - evidence from ejecta deposits in Belize and Mexico

    DEFF Research Database (Denmark)

    Vajda, Vivi; Ocampo, Adriana; Ferrow, Embaie;

    2015-01-01

    Life on Earth was sharply disrupted 66 Ma ago as an asteroid hit the sea-floor in what is today Yucatan Peninsula, Mexico. Approximately 600 km3 of sedimentary rock were vapourized, ejected into the atmosphere and subsequently deposited globally as an ejecta apron and fallout layer. Proximal ejecta...... deposits occur in Belize and southern Mexico where the so called Albion island spheroid bed is superimposed on the target rock (the Barton Creek Formation). We analysed the spheroid bed via Mössbauer spectroscopy, petrology, XRD, and palynology at several sites ~ 350-500 km distance from the crater centre....... Our results show that the relative concentrations of Fe in nano-phase goethite (α-FeOOH) are very high in the spheroid bed samples from Albion Island (Belize) and from Ramonal South (Mexico), but are low to absent in the spheroid bed at Ramonal North, and in the Cretaceous target rock. Moreover, our...

  16. Probing the Physical Conditions of Supernova Ejecta with the Measured Sizes of Presolar Al2O3 Grains

    CERN Document Server

    Nozawa, Takaya; Hasegawa, Yasuhiro; Kozasa, Takashi

    2015-01-01

    A few particles of presolar Al2O3 grains with sizes above 0.5 mum are believed to have been produced in the ejecta of core-collapse supernovae (SNe). In order to clarify the formation condition of such large Al2O3 grains, we investigate the condensation of Al2O3 grains for wide ranges of the gas density and cooling rate. We first show that the average radius and condensation efficiency of newly formed Al2O3 grains are successfully described by a non-dimensional quantity "Lambda_on" defined as the ratio of the timescale with which the supersaturation ratio increases to the collision timescale of reactant gas species at dust formation. Then, we find that the formation of submicron-sized Al2O3 grains requires at least ten times higher gas densities than those presented by one-dimensional SN models. This indicates that presolar Al2O3 grains identified as a SN origin might be formed in dense gas clumps, allowing us to propose that the measured sizes of presolar grains can be a powerful tool to constrain the physic...

  17. SPATIAL DISTRIBUTION OF X-RAY EMITTING EJECTA IN TYCHO’S SNR: INDICATIONS OF SHOCKED TITANIUM

    Energy Technology Data Exchange (ETDEWEB)

    Miceli, M. [Dipartimento di Fisica and Chimica, Università di Palermo, Piazza del Parlamento 1, I-90134 Palermo (Italy); Sciortino, S.; Orlando, S. [INAF-Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134 Palermo (Italy); Troja, E., E-mail: miceli@astropa.unipa.it [NASA, Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2015-06-01

    Young supernova remnants (SNRs) show characteristic ejecta-dominated X-ray emission that allows us to probe the products of explosive nucleosynthesis processes and to ascertain important information about the physics of supernova explosions. Hard X-ray observations have recently revealed the presence of the radioactive decay lines of {sup 44}Ti at ∼67.9 and ∼78.4 keV in Tycho’s SNR. Here, we analyze a set of XMM-Newton archive observations of Tycho’s SNR. We produce equivalent width (EW) maps of the Fe K and Ca xix emission lines and find indications for a stratification of the abundances of these elements and significant anisotropies. We then perform spatially resolved spectral analysis by identifying five different regions characterized by high/low values of the Fe K EW. We find that the spatial distribution of the Fe K emission is correlated with that of Cr xxii. We also detect the Ti K line complex in the spectra extracted from the two regions with the highest values of Fe and Cr EWs. The Ti line emission remains undetected in regions where Fe and Cr EWs are low. Our results indicate that the post-shock Ti is spatially colocated with other iron-peak nuclei in Tycho’s SNR, in agreement with the predictions of multi-D models of SNe Ia.

  18. Noachian Impact Ejecta on Murray Ridge and Pre-impact Rocks on Wdowiak Ridge, Endeavour Crater, Mars: Opportunity Observations

    Science.gov (United States)

    Mittlefehldt, D. W.; Gellert, R.; Ming, D. W.; Morris, R. V.; Schroeder, C.; Yen, A. S.; Farrand, W. H.; Arvidson, R. E.; Franklin, B. J.; Grant, J. A.; hide

    2015-01-01

    Mars Exploration Rover Opportunity has been exploring Meridiani Planum since January 2004, and has completed 4227% of its primary mission. Opportunity has been investigating the geology of the rim of 22 km diameter Endeavour crater, first on the Cape York segment and now on Cape Tribulation. The outcrops are divided York; (ii) the Shoemaker fm, impact breccias representing ejecta from the crater; into three formations: (i) the lower Matijevic fm, a pre-impact lithology on Cape and (iii) the upper Grasberg fm, a post-impact deposit that drapes the lower portions of the eroded rim segments. On the Cape Tribulation segment Opportunity has been studying the rocks on Murray Ridge, with a brief sojourn to Wdowiak Ridge west of the rim segment. team member Thomas Wdowiak, who died in 2013.) One region of Murray Ridge has distinctive CRISM spectral characteristics indicating the presence of a small concentration of aluminous smectite based on a 2.2 micron Al-OH combination band (hereafter, the Al-OH region).

  19. Early Formation of Dust in the Ejecta of Type Ib SN 2006jc and Temperature and Mass of the Dust

    CERN Document Server

    Nozawa, T; Tominaga, N; Sakon, I; Tanaka, M; Suzuki, T; Nomoto, K; Maeda, K; Umeda, H; Limongi, M; Onaka, T

    2008-01-01

    SN 2006jc is a peculiar supernova (SN), in which the formation of dust has been confirmed at an early epoch of ~50 days after the explosion. We investigate the possibility of such an earlier formation of dust grains in the expanding ejecta of SN 2006jc, applying the Type Ib SN model that is developed to reproduce the observed light curve. We find that the rapid decrease of the gas temperature in SN 2006jc enables the condensation of C grains in the C-rich layer at 40--60 days after the explosion, which is followed by the condensation of silicate and oxide grains until ~200 days. The average radius of each grain species is confined to be less than 0.01 micron due to the low gas density at the condensation time. The calculated total dust mass reaches to ~1.5 Msun, of which C dust shares 0.7 Msun. On the other hand, based on the calculated dust temperature, we show that the dust species and mass evaluated to reproduce the spectral energy distribution observed by AKARI and MAGNUM at day 200 are different from tho...

  20. Thermal X-Ray Emission from Shocked Ejecta in Type Ia Supernova Remnants II: Parameters Affecting the Spectrum

    CERN Document Server

    Badenes, C; Bravo, E

    2005-01-01

    The supernova remnants left behind by Type Ia supernovae provide an excellent opportunity for the study of these enigmatic objects. In a previous work, we showed that it is possible to use the X-ray spectra of young Type Ia supernova remnants to explore the physics of Type Ia supernovae and identify the relevant mechanism underlying these explosions. Our simulation technique is based on hydrodynamic and nonequilibrium ionization calculations of the interaction of a grid of Type Ia explosion models with the surrounding ambient medium, coupled to an X-ray spectral code. In this work we explore the influence of two key parameters on the shape of the X-ray spectrum of the ejecta: the density of the ambient medium around the supernova progenitor and the efficiency of collisionless electron heating at the reverse shock. We also discuss the performance of recent 3D simulations of Type Ia SN explosions in the context of the X-ray spectra of young SNRs. We find a better agreement with the observations for Type Ia supe...

  1. Ejecta, Dust, and Synchrotron Radiation in B0540-69.3: A More Crab-Like Remnant than the Crab

    CERN Document Server

    Williams, Brian J; Reynolds, Stephen P; Raymond, John C; Long, Knox S; Morse, Jon A; Blair, William P; Ghavamian, Parviz; Sankrit, Ravi; Hendrick, Sean P; Smith, R Chris; Points, Sean; Winkler, P Frank

    2008-01-01

    We present near and mid-infrared observations of the pulsar-wind nebula (PWN) B0540-69.3 and its associated supernova remnant made with the {\\it Spitzer Space Telescope}. We report detections of the PWN with all four IRAC bands, the 24 $\\mu$m band of MIPS, and the Infrared Spectrograph (IRS). We find no evidence of IR emission from the X-ray/radio shell surrounding the PWN resulting from the forward shock of the supernova blast wave. The flux of the PWN itself is dominated by synchrotron emission at shorter (IRAC) wavelengths, with a warm dust component longward of 20 $\\mu$m. We show that this dust continuum can be explained by a small amount ($\\sim 1-3 \\times 10^{-3} \\msun$) of dust at a temperature of $\\sim 50-65$ K, heated by the shock wave generated by the PWN being driven into the inner edge of the ejecta. This is evidently dust synthesized in the supernova. We also report the detection of several lines in the spectrum of the PWN, and present kinematic information about the PWN as determined from these l...

  2. The influence of neutrinos on r-process nucleosynthesis in the ejecta of black hole-neutron star mergers

    Science.gov (United States)

    Roberts, Luke F.; Lippuner, Jonas; Duez, Matthew D.; Faber, Joshua A.; Foucart, Francois; Lombardi, James C., Jr.; Ning, Sandra; Ott, Christian D.; Ponce, Marcelo

    2017-02-01

    During the merger of a black hole and a neutron star, baryonic mass can become unbound from the system. Because the ejected material is extremely neutron-rich, the r-process rapidly synthesizes heavy nuclides as the material expands and cools. In this work, we map general relativistic models of black hole-neutron star mergers into a Newtonian smoothed particle hydrodynamics (SPH) code and follow the evolution of the thermodynamics and morphology of the ejecta until the outflows become homologous. We investigate how the subsequent evolution depends on our mapping procedure and find that the results are robust. Using thermodynamic histories from the SPH particles, we then calculate the expected nucleosynthesis in these outflows while varying the level of neutrino irradiation coming from the post-merger accretion disc. We find that the ejected material robustly produces r-process nucleosynthesis even for unrealistically high neutrino luminosities, due to the rapid velocities of the outflow. None the less, we find that neutrinos can have an impact on the detailed pattern of the r-process nucleosynthesis. Electron neutrinos are captured by neutrons to produce protons while neutron capture is occurring. The produced protons rapidly form low-mass seed nuclei for the r-process. These low-mass seeds are eventually incorporated into the first r-process peak at A ˜ 78. We consider the mechanism of this process in detail and discuss if it can impact galactic chemical evolution of the first peak r-process nuclei.

  3. 22Ne and 23Na ejecta from intermediate-mass stars: the impact of the new LUNA rate for 22Ne(p, γ)23Na

    Science.gov (United States)

    Slemer, A.; Marigo, P.; Piatti, D.; Aliotta, M.; Bemmerer, D.; Best, A.; Boeltzig, A.; Bressan, A.; Broggini, C.; Bruno, C. G.; Caciolli, A.; Cavanna, F.; Ciani, G. F.; Corvisiero, P.; Davinson, T.; Depalo, R.; Di Leva, A.; Elekes, Z.; Ferraro, F.; Formicola, A.; Fülöp, Zs.; Gervino, G.; Guglielmetti, A.; Gustavino, C.; Gyürky, G.; Imbriani, G.; Junker, M.; Menegazzo, R.; Mossa, V.; Pantaleo, F. R.; Prati, P.; Straniero, O.; Szücs, T.; Takács, M. P.; Trezzi, D.

    2017-03-01

    We investigate the impact of the new LUNA rate for the nuclear reaction 22Ne(p, γ)23Na on the chemical ejecta of intermediate-mass stars, with particular focus on the thermally pulsing asymptotic giant branch (TP-AGB) stars that experience hot-bottom burning. To this aim, we use the PARSEC and COLIBRI codes to compute the complete evolution, from the pre-main sequence up to the termination of the TP-AGB phase, of a set of stellar models with initial masses in the range 3.0-6.0 M⊙ and metallicities Zi = 0.0005, 0.006 and 0.014. We find that the new LUNA measures have much reduced the nuclear uncertainties of the 22Ne and 23Na AGB ejecta that drop from factors of ≃10 to only a factor of few for the lowest metallicity models. Relying on the most recent estimations for the destruction rate of 23Na, the uncertainties that still affect the 22Ne and 23Na AGB ejecta are mainly dominated by the evolutionary aspects (efficiency of mass-loss, third dredge-up, convection). Finally, we discuss how the LUNA results impact on the hypothesis that invokes massive AGB stars as the main agents of the observed O-Na anticorrelation in Galactic globular clusters. We derive quantitative indications on the efficiencies of key physical processes (mass-loss, third dredge-up, sodium destruction) in order to simultaneously reproduce both the Na-rich, O-poor extreme of the anticorrelation and the observational constraints on the CNO abundance. Results for the corresponding chemical ejecta are made publicly available.

  4. Binary stellar mergers with marginally bound ejecta: excretion discs, inflated envelopes, outflows, and their luminous transients

    Science.gov (United States)

    Pejcha, Ondřej; Metzger, Brian D.; Tomida, Kengo

    2016-09-01

    We study mass-loss from the outer Lagrange point (L2) in binary stellar mergers and their luminous transients by means of radiative hydrodynamical simulations. Previously, we showed that for binary mass ratios 0.06 ≲ q ≲ 0.8, synchronous L2 mass-loss results in a radiatively inefficient, dust-forming unbound equatorial outflow. A similar outflow exists irrespective of q if the ratio of the sound speed to the orbital speed at the injection point is sufficiently large, ε ≡ cT/vorb ≳ 0.15. By contrast, for cold L2 mass-loss (ε ≲ 0.15) from binaries with q ≲ 0.06 or q ≳ 0.8, the equatorial outflow instead remains marginally bound and falls back to the binary over tens to hundreds of binary orbits, where it experiences additional tidal torquing and shocking. As the bound gas becomes virialized with the binary, the luminosity of the system increases slowly at approximately constant photosphere radius, causing the temperature to rise. Subsequent evolution depends on the efficiency of radiative cooling. If the bound atmosphere is able to cool efficiently, as quantified by radiative diffusion time being shorter than the advection time (tdiff/tadv ≪ 1), then the virialized gas collapses to an excretion disc, while for tdiff/tadv ≳ 1 an isotropic wind is formed. Between these two extremes, an inflated envelope transports the heat generated near the binary to the surface by meridional flows. In all cases, the radiated luminosity reaches a fraction ˜10-2 to 10-1 of dot{M}v_orb^2/2, where dot{M} is the mass outflow rate. We discuss the implications of our results for transients in the luminosity gap between classical novae and supernovae, such as V1309 Sco and V838 Mon.

  5. The Distinct Behavior of Sedimentary Target Rocks During the Chicxulub Impact Event: Observations at Proximal and Distal Ejecta Deposits at K-Pg Sites El Guayal, La Lajilla, and Drill Cores UNAM-7 and ODP 207

    Science.gov (United States)

    Salge, T.; Goran, D.; Schulte, P.; Deutsch, A.

    2013-08-01

    EDS/EBSD analysis indicate melting and dissociation of carbonates and sulfates. Reformation of calcite would cause a prolongued release of thermal energy that may have initiated a delayed vapor release. It could force the gas driven ejecta transport.

  6. Modeling SNR Cassiopeia A from the Supernova Explosion to its Current Age: The role of post-explosion anisotropies of ejecta

    CERN Document Server

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

    2016-01-01

    The remnants of core-collapse supernovae (SNe) have complex morphologies that may reflect asymmetries and structures developed during the progenitor SN explosion. Here we investigate how the morphology of the SNR Cassiopeia A (Cas A) reflects the characteristics of the progenitor SN with the aim to derive the energies and masses of the post-explosion anisotropies responsible for the observed spatial distribution of Fe and Si/S. We model the evolution of Cas A from the immediate aftermath of the progenitor SN to the three-dimensional interaction of the remnant with the surrounding medium. The post-explosion structure of the ejecta is described by small-scale clumping of material and larger-scale anisotropies. The hydrodynamic multi-species simulations consider an appropriate post-explosion isotopic composition of the ejecta. The observed average expansion rate and shock velocities can be well reproduced by models with ejecta mass $M_{\\rm ej}\\approx 4M_{\\odot}$ and explosion energy $E_{\\rm SN}\\approx 2.3\\times ...

  7. The spectroscopic evolution of the recurrent nova T Pyxidis during its 2011 outburst. II.The optically thin phase and the structure of the ejecta in recurrent novae

    CERN Document Server

    Shore, S N; Aquino, I De Gennaro; Augusteijn, T; Walter, F M; Starrfield, S; Sion, E M

    2012-01-01

    We continue our study of the physical properties of the recurrent nova T Pyx, focussing on the structure of the ejecta in the nebular stage of expansion during the 2011 outburst. The nova was observed contemporaneously with the Nordic Optical Telescope (NOT), at high resolution spectroscopic resolution (R ~ 65000) on 2011 Oct. 11 and 2012 Apr. 8 (without absolute flux calibration), and with the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope, at high resolution (R ~ 30000) on 2011 Oct. 10 and 2012 Mar. 28 (absolute fluxes). We use standard plasma diagnostics (e.g. [O III] and [N II] line ratios and the H$\\beta$ line fluxes) to constrain electron densities and temperatures. Using Monte Carlo modeling of the ejecta, we derive the structure and filling factor from comparisons to the optical and ultraviolet line profiles. The ejecta can be modeled using an axisymmetric conical -- bipolar -- geometry with a low inclination of the axis to the line of sight, i=15+/-5 degrees, compatible...

  8. $^{22}$Ne and $^{23}$Na ejecta from intermediate-mass stars: The impact of the new LUNA rate for $^{22}$Ne(p,$\\gamma$)$^{23}$Na

    CERN Document Server

    Slemer, A; Piatti, D; Aliotta, M; Bemmerer, D; Best, A; Boeltzig, A; Bressan, A; Broggini, C; Bruno, C G; Caciolli, A; Cavanna, F; Ciani, G F; Corvisiero, P; Davinson, T; Depalo, R; Di Leva, A; Elekes, Z; Ferraro, F; Formicola, A; F\\", Zs; l\\",; p,; Gervino, G; Guglielmetti, A; Gustavino, C; Gy\\", G; rky,; Imbriani, G; Junker, M; Menegazzo, R; Mossa, V; Pantaleo, F R; Prati, P; Straniero, O; Sz\\", T; cs,; Tak\\', M P; cs,; Trezzi, D

    2016-01-01

    We investigate the impact of the new LUNA rate for the nuclear reaction $^{22}$Ne$(p,\\gamma)^{23}$Na on the chemical ejecta of intermediate-mass stars, with particular focus on the thermally-pulsing asymptotic giant branch (TP-AGB) stars that experience hot-bottom burning. To this aim we use the PARSEC and COLIBRI codes to compute the complete evolution, from the pre-main sequence up to the termination of the TP-AGB phase, of a set of stellar models with initial masses in the range $3.0\\,M_{\\odot} - 6.0\\,M_{\\odot}$, and metallicities $Z_{\\rm i}=0.0005$, $Z_{\\rm i}=0.006$, and $Z_{\\rm i} = 0.014$. We find that the new LUNA measures have much reduced the nuclear uncertainties of the $^{22}$Ne and $^{23}$Na AGB ejecta, which drop from factors of $\\simeq 10$ to only a factor of few for the lowest metallicity models. Relying on the most recent estimations for the destruction rate of $^{23}$Na, the uncertainties that still affect the $^{22}$Ne and $^{23}$Na AGB ejecta are mainly dominated by evolutionary aspects (e...

  9. The 3-Dimensional Inner and Outer Structure of Ejecta Around Eta Carinae as Detected by the STIS

    Science.gov (United States)

    Ishibashi, Kazunori; Fisher, Richard R. (Technical Monitor)

    2000-01-01

    The HST/STIS instrument was used successfully to perform a complete mapping of the Homunculus nebula at two wavelength ranges including H-alpha and H-beta with a spectral resolving power of about 5000 and a spatial resolution of 0.1". The individual spectra were merged to synthesize three-dimensional data cubes that contain a set of images of Eta Car with spatial resolution of 0.10 to 0.251, sliced at velocity increment of 10 -- 30 km/s. For the first time this unique method allows us to diagnose the origin of intrinsic narrow emission structure of the nebula with high spatial and velocity resolution. Our initial analysis revealed the inner emission structure appeared to trace an elongated bipolar shell (possibly other shells as well) with a scale size of an arcsecond (i.e., "little homunculus in the Homunculus"). Furthermore, the mapping data cube revealed that the "fan" or "paddle" -- often referred as the source of peculiar blue-shifted intrinsic emissions including the Strontium cloud -- is not the source of intrinsic emissions. The fan is not even a part of the equatorial disk, but is spatially separated from the peculiar emission structure. Indeed we suggest that the fan is a surface of the Northwest lobe, possibly revealed by a blowout of the equatorial disk. We will use a number of visualization techniques (tomographic animations and simple 3-D models) to show these structures. These new results have strong impact upon future numerical modelings of the Homunculus nebula and of understanding of the evolution of the ejecta powered by the central source(s).

  10. The 3-Dimensional Inner and Outer Structure of Ejecta Around Eta Carinae as Detected by the STIS

    Science.gov (United States)

    Ishibashi, Kazunori; Fisher, Richard R. (Technical Monitor)

    2000-01-01

    The HST/STIS instrument was used successfully to perform a complete mapping of the Homunculus nebula at two wavelength ranges including H-alpha and H-beta with a spectral resolving power of about 5000 and a spatial resolution of 0.1". The individual spectra were merged to synthesize three-dimensional data cubes that contain a set of images of Eta Car with spatial resolution of 0.10 to 0.251, sliced at velocity increment of 10 -- 30 km/s. For the first time this unique method allows us to diagnose the origin of intrinsic narrow emission structure of the nebula with high spatial and velocity resolution. Our initial analysis revealed the inner emission structure appeared to trace an elongated bipolar shell (possibly other shells as well) with a scale size of an arcsecond (i.e., "little homunculus in the Homunculus"). Furthermore, the mapping data cube revealed that the "fan" or "paddle" -- often referred as the source of peculiar blue-shifted intrinsic emissions including the Strontium cloud -- is not the source of intrinsic emissions. The fan is not even a part of the equatorial disk, but is spatially separated from the peculiar emission structure. Indeed we suggest that the fan is a surface of the Northwest lobe, possibly revealed by a blowout of the equatorial disk. We will use a number of visualization techniques (tomographic animations and simple 3-D models) to show these structures. These new results have strong impact upon future numerical modelings of the Homunculus nebula and of understanding of the evolution of the ejecta powered by the central source(s).

  11. The Stickney Crater ejecta secondary impact crater spike on Phobos: Implications for the age of Stickney and the surface of Phobos

    Science.gov (United States)

    Ramsley, Kenneth R.; Head, James W.

    2017-04-01

    A global and uniformly distributed spike of secondary impact craters on Phobos with diameters (D) craters up to D 2 km were produced by Stickney Crater ejecta, including secondary craters within the surface area of Stickney Crater. The global exposure of Phobos to Stickney secondary impacts was facilitated by the desynchronized orbital/rotational period of Phobos that was produced by the impulse of the Stickney impact event. In our model we apply the Tsiolkovsky rocket equation to calculate the total available Stickney impact acceleration impulse delta-v (Δv) and further calculate the effective impulse by incorporating the energy conversion inefficiencies of the crater formation process. We also calculate the pre- and post-impact Phobos moment of inertia that further contributes to the desynchronizing effect. The majority of the Stickney ejecta that exited from Phobos was trapped in orbits around Mars until it later accumulated back onto Phobos over a period of craters observed inside Stickney Crater approximate the size/frequency distribution (SFD) of Stickney secondary impacts, it is infeasible to derive an age for Stickney Crater based on an assumption of background impacts ( 2.8-4.2 Ga according to Schmedemann et al. (2014)). In view of how crater-counting is unworkable for age-dating Stickney Crater we conclude an alternate age for Stickney Crater of 0.1-0.5 Ga that is constrained instead by the boulder evidence of Thomas et al. (2000), the boulder destruction rate analysis of Basilevsky et al. (2013, 2015), and the observed space weathering of Phobos regolith (Cipriani et al., 2011; Pieters et al., 2014). Assessing several implications of our model we 1) summarize the crater SFD and temporal nature of the Stickney secondary impact spike on Phobos, 2) predict the global equivalent thickness of deposits on Phobos from Stickney ejecta and subsequent secondary impact gardening, 3) examine the hypothesis that the Stickney impact was a trailing hemisphere event on

  12. Secondary hydroeruptions in pyroclastic-flow deposits: Examples from Mount St. Helens

    Science.gov (United States)

    Moyer, T.C.; Swanson, D.A.

    1987-01-01

    Secondary hydroeruptions occur in pyroclastic-flow deposits when water or ice is trapped beneath hot pyroclastic debris and rapidly heated to steam. These eruptions display various styles of activity including fumarolic degassing, tephra fountaining, and explosive cratering. The deposits, which occupy the layer 3 stratigraphic position on the top of pyroclastic-flow units, can be distinguished from ash-cloud material by lateral thickness variation, clast composition, and other sedimentary features. The ejecta of secondary hydroeruptions comprise a subset of hydrovolcanic pyroclastic deposits. A small secondary hydroeruption observed on the Mount St. Helens pumice plain in 1981 produced tephra that was emplaced ballistically, by deposition from base surges, and by fallout from an eruption column. Stratigraphic descriptions and grain-size analysis of the ejecta from several secondary craters on the pumice plain demonstrate that the bedforms produced by a hydroeruption change with crater diameter. In particular, craters of small diameter are surrounded by interbedded ripple-laminated ash horizons and nonstratified, fines-depleted units; large craters have ejecta ramparts comprised of coarse dunes and antidunes. These bedform changes are related to a progressive increase in eruptive energy, which produces base surges of greater power and eruptive columns of greater height. We suggest that the style of activity displayed during a secondary hydroeruption is controlled by both the total thermal energy of the system and the permeability of the pyroclastic overburden. ?? 1987.

  13. A burst in a wind bubble and the impact on baryonic ejecta: high-energy gamma-ray flashes and afterglows from fast radio bursts and pulsar-driven supernova remnants

    Science.gov (United States)

    Murase, Kohta; Kashiyama, Kazumi; Mészáros, Peter

    2016-09-01

    Tenuous wind bubbles, which are formed by the spin-down activity of central compact remnants, are relevant in some models of fast radio bursts (FRBs) and superluminous supernovae (SNe). We study their high-energy signatures, focusing on the role of pair-enriched bubbles produced by young magnetars, rapidly rotating neutron stars, and magnetized white dwarfs. (i) First, we study the nebular properties and the conditions allowing for escape of high-energy gamma-rays and radio waves, showing that their escape is possible for nebulae with ages of ≳10-100 yr. In the rapidly rotating neutron star scenario, we find that radio emission from the quasi-steady nebula itself may be bright enough to be detected especially at sub-mm frequencies, which is relevant as a possible counterpart of pulsar-driven SNe and FRBs. (ii) Secondly, we consider the fate of bursting emission in the nebulae. We suggest that an impulsive burst may lead to a highly relativistic flow, which would interact with the nebula. If the shocked nebula is still relativistic, pre-existing non-thermal particles in the nebula can be significantly boosted by the forward shock, leading to short-duration (maybe millisecond or longer) high-energy gamma-ray flashes. Possible dissipation at the reverse shock may also lead to gamma-ray emission. (iii) After such flares, interactions with the baryonic ejecta may lead to afterglow emission with a duration of days to weeks. In the magnetar scenario, this burst-in-bubble model leads to the expectation that nearby (≲10-100 Mpc) high-energy gamma-ray flashes may be detected by the High-Altitude Water Cherenkov Observatory and the Cherenkov Telescope Array, and the subsequent afterglow emission may be seen by radio telescopes such as the Very Large Array. (iv) Finally, we discuss several implications specific to FRBs, including constraints on the emission regions and limits on soft gamma-ray counterparts.

  14. GHRS observations of mass-loaded flows in Abell 78

    Science.gov (United States)

    Harrington, J. Patrick; Borkowski, Kazimierz J.; Tsvetanov, Zlatan

    1995-01-01

    Spectroscopic observations of the central star of the planetary nebula Abell 78 were obtained with the Goddard High Resolution Spectrograph (GHRS) onboard the Hubble Space Telescope (HST) in the vicinity of the C IV lambda 1548.2, 1550.8 doublet. We find a series of narrow absorption features superposed on the broad, P Cygni stellar wind profile. These features are seen in both components of the doublet at heliocentric radial velocities of -18, -71, -131, and -192 km/s. At higher velocities, individual components are no longer distinct but, rather, merge into a continuous absorption extending to approximately -385 km/s. This is among the highest velocities ever detected for gas in a planetary nebula. The -18 km/s feature originates in an outer envelope of normal composition, while the -71 km/s feature is produced in the wind-swept shell encircling an irregular wind-blown bubble in the planetary nebula center. The hydrogen-poor ejecta of Abell 78, consisting of dense knots with wind-blown tails, are located in the bubble's interior, in the vicinity of the stellar wind termination shock. The high-velocity C IV lambda 154 absorption features can be explained as due to parcels of ejecta being accelerated to high velocities as they are swept up by the stellar wind during its interaction with dense condensations of H-poor ejecta. As the ablated material is accelerated, it will partially mix with the stellar wind, creating a mass-loaded flow. The abundance anomalies seen at the rim of the bubble attest to the transport of H-poor knot material by such a flow.

  15. Dynamics of large-scale solar-wind streams obtained by the double superposed epoch analysis. 2. CIR.vs.Sheath and MC.vs.Ejecta comparisons

    CERN Document Server

    Yermolaev, Yu I; Nikolaeva, N S; Yermolaev, M Yu

    2016-01-01

    This work is a continuation of our previous paper [Yermolaevetal2015] which describes the average temporal profiles of interplanetary plasma and field parameters in large-scale solar-wind (SW) streams: CIR, ICME (both MC and Ejecta) and Sheath as well as the interplanetary shock (IS). Like in the previous work we use data of OMNI database, our catalog of large-scale solar-wind phenomena during 1976--2000 [Yermolaevetal2009] and the double superposed epoch analysis (DSEA) method [Yermolaevetal2010]: re-scaling the duration of interval for all types in such a manner that, respectively, beginning and end for all intervals of selected type coincide. We present new detailed results of comparison of two pair phenomena: (1) both types of compression regions (CIR.vs.Sheath) and (2) both types of ICMEs (MC.vs.Ejecta). Obtained data allows us to suggest that the formation of all types of compression regions has the same physical mechanism irrespective of piston (High-Speed Stream (HSS) or ICME) type and differences are...

  16. Dense Fe-Rich Ejecta in Supernova Remnants DEM L238 and DEM L249: A New Class of Type Ia Supernova?

    CERN Document Server

    Borkowski, K J; Reynolds, S P

    2006-01-01

    We present observations of two LMC supernova remnants (SNRs), DEM L238 and DEM L249, with the Chandra and XMM-Newton X-ray satellites. Bright central emission, surrounded by a faint shell, is present in both remnants. The central emission has an entirely thermal spectrum dominated by strong Fe L-shell lines, with the deduced Fe abundance in excess of solar and not consistent with the LMC abundance. This Fe overabundance leads to the conclusion that DEM L238 and DEM L249 are remnants of thermonuclear (Type Ia) explosions. The shell emission originates in gas swept up and heated by the blast wave. A standard Sedov analysis implies about 50 solar masses in both swept-up shells, SNR ages between 10,000 and 15,000 yr, low (< 0.05 cm^-3) preshock densities, and subluminous explosions with energies of 3x10^50 ergs. The central Fe-rich supernova ejecta are close to collisional ionization equilibrium. Their presence is unexpected, because standard Type Ia SNR models predict faint ejecta emission with short ionizati...

  17. Abundances in the Ejecta of Core Collapse Supernova Remnants, G350.1-0.3 and G349.7+0.2

    CERN Document Server

    Yasumi, Masato; Nakashima, Shinya; Uchida, Hiroyuki; Sugawara, Ryusuke; Tsuru, Takeshi Go; Tanaka, Takaaki; Koyama, Katsuji

    2014-01-01

    We present Suzaku results of the two Galactic supernova remnants (SNRs), G350.1-0.3 and G349.7+0.2. We find Al and Ni K alpha lines from both the SNRs for the first time, in addition to previously detected K-shell lines of Mg, Si, S, Ar, Ca and Fe. The spectra are well described by two optically thin thermal plasmas: a low-temperature (low-kT) plasma in collisional ionization equilibrium and a high-temperature (high-kT) plasma in non-equilibrium ionization. Since the low-kT plasma has solar metal abundances, it is thought to be of interstellar medium origin. The high-kT plasma has super-solar abundances, hence it is likely to be of ejecta origin. The abundance patterns of the ejecta components are similar to those of core-collapse supernovae with the progenitor mass of ~15-25 M_solar for G350.1-0.3 and ~35-40 M_solar for G349.7+0.2. We find extremely high abundances of Ni compared to Fe (Z_Ni/Z_Fe ~8). Based on the measured column densities between the SNRs and the near sky background, we propose that G350.1-...

  18. The Importance of Physical Models for Deriving Dust Masses in Supernova Ejecta I: Radiatively Heated Dust Surrounding the Crab's Pulsar Wind Nebula

    CERN Document Server

    Temim, Tea

    2013-01-01

    Recent far-infrared (IR) observations of supernova remnants (SNRs) have revealed significantly large amounts of newly-condensed dust in their ejecta, comparable to the total mass of available refractory elements. The dust masses derived from these observations assume that all the grains of a given species radiate at the same temperature, regardless of the dust heating mechanism or grain radius. In this paper, we derive the dust mass in the ejecta of the Crab Nebula, using a physical model for the heating and radiation from the dust. We adopt a power-law distribution of grain sizes and two different dust compositions, and calculate the heating rate of each dust grain by the radiation from the pulsar wind nebula (PWN). We find that the grains attain a continuous range of temperatures, depending on their size and composition. The best-fit model to the observed IR spectrum consist of amorphous carbon grains with a total mass of 0.027+/-0.003 Msun. We find that the power-law size distribution of dust grains is cha...

  19. Sun-to-Earth Characteristics of Two Coronal Mass Ejections Interacting near 1 AU: Formation of a Complex Ejecta and Generation of a Two-Step Geomagnetic Storm

    CERN Document Server

    Liu, Ying D; Wang, Rui; Luhmann, Janet G; Richardson, John D; Lugaz, Noé

    2014-01-01

    On 2012 September 30 - October 1 the Earth underwent a two-step geomagnetic storm. We examine the Sun-to-Earth characteristics of the coronal mass ejections (CMEs) responsible for the geomagnetic storm with combined heliospheric imaging and in situ observations. The first CME, which occurred on 2012 September 25, is a slow event and shows an acceleration followed by a nearly invariant speed in the whole Sun-Earth space. The second event, launched from the Sun on 2012 September 27, exhibits a quick acceleration, then a rapid deceleration and finally a nearly constant speed, a typical Sun-to-Earth propagation profile for fast CMEs \\citep{liu13}. These two CMEs interacted near 1 AU as predicted by the heliospheric imaging observations and formed a complex ejecta observed at Wind, with a shock inside that enhanced the pre-existing southward magnetic field. Reconstruction of the complex ejecta with the in situ data indicates an overall left-handed flux rope-like configuration, with an embedded concave-outward shoc...

  20. SUN-TO-EARTH CHARACTERISTICS OF TWO CORONAL MASS EJECTIONS INTERACTING NEAR 1 AU: FORMATION OF A COMPLEX EJECTA AND GENERATION OF A TWO-STEP GEOMAGNETIC STORM

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ying D.; Yang, Zhongwei; Wang, Rui [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China); Luhmann, Janet G. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Richardson, John D. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Lugaz, Noé, E-mail: liuxying@spaceweather.ac.cn [Space Science Center, University of New Hampshire, Durham, NH 03824 (United States)

    2014-10-01

    On 2012 September 30-October 1 the Earth underwent a two-step geomagnetic storm. We examine the Sun-to-Earth characteristics of the coronal mass ejections (CMEs) responsible for the geomagnetic storm with combined heliospheric imaging and in situ observations. The first CME, which occurred on 2012 September 25, is a slow event and shows an acceleration followed by a nearly invariant speed in the whole Sun-Earth space. The second event, launched from the Sun on 2012 September 27, exhibits a quick acceleration, then a rapid deceleration, and finally a nearly constant speed, a typical Sun-to-Earth propagation profile for fast CMEs. These two CMEs interacted near 1 AU as predicted by the heliospheric imaging observations and formed a complex ejecta observed at Wind, with a shock inside that enhanced the pre-existing southward magnetic field. Reconstruction of the complex ejecta with the in situ data indicates an overall left-handed flux-rope-like configuration with an embedded concave-outward shock front, a maximum magnetic field strength deviating from the flux rope axis, and convex-outward field lines ahead of the shock. While the reconstruction results are consistent with the picture of CME-CME interactions, a magnetic cloud-like structure without clear signs of CME interactions is anticipated when the merging process is finished.

  1. The Importance of Physical Models for Deriving Dust Masses and Grain Size Distributions in Supernova Ejecta. I. Radiatively Heated Dust in the Crab Nebula

    Science.gov (United States)

    Temim, Tea; Dwek, Eli

    2013-01-01

    Recent far-infrared (IR) observations of supernova remnants (SNRs) have revealed significantly large amounts of newly condensed dust in their ejecta, comparable to the total mass of available refractory elements. The dust masses derived from these observations assume that all the grains of a given species radiate at the same temperature, regardless of the dust heating mechanism or grain radius. In this paper, we derive the dust mass in the ejecta of the Crab Nebula, using a physical model for the heating and radiation from the dust. We adopt a power-law distribution of grain sizes and two different dust compositions (silicates and amorphous carbon), and calculate the heating rate of each dust grain by the radiation from the pulsar wind nebula. We find that the grains attain a continuous range of temperatures, depending on their size and composition. The total mass derived from the best-fit models to the observed IR spectrum is 0.019-0.13 Solar Mass, depending on the assumed grain composition. We find that the power-law size distribution of dust grains is characterized by a power-law index of 3.5-4.0 and a maximum grain size larger than 0.1 micron. The grain sizes and composition are consistent with what is expected for dust grains formed in a Type IIP supernova (SN). Our derived dust mass is at least a factor of two less than the mass reported in previous studies of the Crab Nebula that assumed more simplified two-temperature models. These models also require a larger mass of refractory elements to be locked up in dust than was likely available in the ejecta. The results of this study show that a physical model resulting in a realistic distribution of dust temperatures can constrain the dust properties and affect the derived dust masses. Our study may also have important implications for deriving grain properties and mass estimates in other SNRs and for the ultimate question of whether SNe are major sources of dust in the Galactic interstellar medium and in

  2. THE IMPORTANCE OF PHYSICAL MODELS FOR DERIVING DUST MASSES AND GRAIN SIZE DISTRIBUTIONS IN SUPERNOVA EJECTA. I. RADIATIVELY HEATED DUST IN THE CRAB NEBULA

    Energy Technology Data Exchange (ETDEWEB)

    Temim, Tea; Dwek, Eli, E-mail: tea.temim@nasa.gov [Observational Cosmology Lab, Code 665, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2013-09-01

    Recent far-infrared (IR) observations of supernova remnants (SNRs) have revealed significantly large amounts of newly condensed dust in their ejecta, comparable to the total mass of available refractory elements. The dust masses derived from these observations assume that all the grains of a given species radiate at the same temperature, regardless of the dust heating mechanism or grain radius. In this paper, we derive the dust mass in the ejecta of the Crab Nebula, using a physical model for the heating and radiation from the dust. We adopt a power-law distribution of grain sizes and two different dust compositions (silicates and amorphous carbon), and calculate the heating rate of each dust grain by the radiation from the pulsar wind nebula. We find that the grains attain a continuous range of temperatures, depending on their size and composition. The total mass derived from the best-fit models to the observed IR spectrum is 0.019-0.13 M{sub Sun }, depending on the assumed grain composition. We find that the power-law size distribution of dust grains is characterized by a power-law index of 3.5-4.0 and a maximum grain size larger than 0.1 {mu}m. The grain sizes and composition are consistent with what is expected for dust grains formed in a Type IIP supernova (SN). Our derived dust mass is at least a factor of two less than the mass reported in previous studies of the Crab Nebula that assumed more simplified two-temperature models. These models also require a larger mass of refractory elements to be locked up in dust than was likely available in the ejecta. The results of this study show that a physical model resulting in a realistic distribution of dust temperatures can constrain the dust properties and affect the derived dust masses. Our study may also have important implications for deriving grain properties and mass estimates in other SNRs and for the ultimate question of whether SNe are major sources of dust in the Galactic interstellar medium and in

  3. Ejecta patterns of Meteor Crater, Arizona derived from the linear un-mixing of TIMS data and laboratory thermal emission spectra

    Science.gov (United States)

    Ramsey, Michael S.; Christensen, Philip R.

    1992-01-01

    -grained sandstone, while the upper Moqui member is a fissile siltstone. Ejecta from these units are preserved as inverted stratigraphy up to 2 crater radii from the rim. The mineralogical contrast between the units, relative lack of post-emplacement erosion and ejecta mixing provide a unique site to apply the un-mixing model. Selection of the aforementioned units as endmembers reveals distinct patterns in the ejecta of the crater.

  4. Flow visualization

    CERN Document Server

    Merzkirch, Wolfgang

    1974-01-01

    Flow Visualization describes the most widely used methods for visualizing flows. Flow visualization evaluates certain properties of a flow field directly accessible to visual perception. Organized into five chapters, this book first presents the methods that create a visible flow pattern that could be investigated by visual inspection, such as simple dye and density-sensitive visualization methods. It then deals with the application of electron beams and streaming birefringence. Optical methods for compressible flows, hydraulic analogy, and high-speed photography are discussed in other cha

  5. Binary Stellar Mergers with Marginally-Bound Ejecta: Excretion Disks, Inflated Envelopes, Outflows, and their Luminous Transients

    CERN Document Server

    Pejcha, Ondrej; Tomida, Kengo

    2016-01-01

    We study mass loss from the outer Lagrange point (L2) in binary stellar mergers and their luminous transients by means of radiative hydrodynamical simulations. Previously, we showed that for binary mass ratios 0.06 0.15. By contrast, for cold L2 mass-loss (\\epsilon 0.8, the equatorial outflow instead remains marginally-bound and falls back to the binary over tens to hundreds of binary orbits, where it experiences additional tidal torqueing and shocking. As the bound gas becomes virialized with the binary, the luminosity of the system increases slowly at approximately constant photosphere radius, causing the temperature to rise. Subsequent evolution depends on the efficiency of radiative cooling. If the bound atmosphere is able to cool efficiently, as quantified by radiative diffusion time being shorter than the advection time (t_diff/t_adv 10 an isotropic wind is formed. Between these two extremes, an inflated envelope transports the heat generated near the binary to the surface by meridional flows. In all...

  6. The candidate luminous blue variable G79.29+0.46: a comprehensive study of its ejecta through a multiwavelength analysis

    CERN Document Server

    Agliozzo, C; Umana, G; Flagey, N; Buemi, C; Ingallinera, A; Trigilio, C; Leto, P

    2014-01-01

    We present a multiwavelength analysis of the nebula around the candidate luminous blue variable G79.29+0.46. The study is based on our radio observations performed at the Expanded Very Large Array and at the Green Bank Telescope and on archival infrared datasets, including recent images obtained by the Herschel Space Observatory. We confirm that the radio central object is characterized by a stellar wind and derive a current mass-loss rate of about 1.4x10-6 Msun yr-1. We find the presence of a dusty compact envelope close to the star, with a temperature between 40 and 1200 K. We estimate for the outer ejecta an ionised gas mass of 1.51 Msun and a warm (60--85 K) dust mass of 0.02 Msun. Diagnostics of the far-infrared spectra indicate the presence of a photo-dissociation region around the ionised gas. Finally, we model the nebula with the photo-ionization code CLOUDY, using as input parameters those estimated from our analysis. We find for the central star a luminosity of 10^5.4 Lsun and an effective temperatu...

  7. Secondary craters from large impacts on Europa and Ganymede: Ejecta size-velocity distributions on icy worlds, and the scaling of ejected blocks

    Science.gov (United States)

    Singer, Kelsi N.; McKinnon, William B.; Nowicki, L. T.

    2013-09-01

    We have mapped fields of secondary craters around three large primary craters on Europa and Ganymede and estimated the size and velocity of the fragments that formed the secondaries using updated scaling equations for ice impacts. We characterize the upper envelope of the fragment size-velocity distribution to obtain a function for the largest fragments at a given ejection velocity. Power-law velocity exponents found in our study of icy satellite secondary fields are compared to the exponents found for similar studies of mercurian, lunar, and martian craters; for all but basin-scale impacts, fragment size decreases more slowly with increasing ejection velocity than on rocky bodies. Spallation theory provides estimates of the size of ejected spall plates at a given velocity, but this theory predicts fragments considerably smaller than are necessary to form most of our observed secondaries. In general, ejecta fragment sizes scale with primary crater diameter and decrease with increasing ejection velocity, υej, by 1/υej or greater, and point-source scaling implies a relation between the two. The largest crater represented in any of these studies, Gilgamesh on Ganymede, exhibits a relatively steep velocity dependence. Extrapolating the results to the escape speed for each icy moon yields the size of the largest fragment that could later re-impact to form a so-called sesquinary crater, either on the parent moon or a neighboring satellite. We find that craters above 2 km in diameter on Europa and Ganymede are unlikely to be sesquinaries.

  8. Evolution of Dust in Primordial Supernova Remnants: Can Dust Grains Formed in the Ejecta Survive and be Injected into the Early Interstellar Medium?

    CERN Document Server

    Nozawa, Takaya; Habe, Asao; Dwek, Eli; Umeda, Hideyuki; Tominaga, Nozomu; Maeda, Keiichi; Nomoto, Ken'ichi

    2007-01-01

    We investigate the evolution of dust that formed at Population III supernova (SN) explosions and its processing through the collisions with the reverse shocks resulting from the interaction of the SN ejecta with the ambient medium. In particular, we investigate the transport of the shocked dust within the SN remnant (SNR), and its effect on the chemical composition, the size distribution, and the total mass of dust surviving in SNR. We find that the evolution of the reverse shock, and hence its effect on the processing of the dust depends on the thickness of the envelope retained by the progenitor star. Furthermore, the transport and survival of the dust grains depend on their initial radius, a_{ini}, and composition: For Type II SNRs expanding into the interstellar medium (ISM) with a density of n_{H,0}=1 cm^{-3}, small grains with a_{ini} ~ 0.2 micron are ejected into the ISM without decreasing their sizes significantly. We find that the total mass fraction of dust that is destroyed by the reverse shock ra...

  9. Morphology of Cryogenic Flows and Channels on Dwarf Planet Ceres

    Science.gov (United States)

    Krohn, Katrin; Jaumann, Ralf; Otto, Katharina A.; von der Gathen, Isabel; Matz, Klaus-Dieter; Buczkowski, Debra L.; Williams, David A.; Pieters, Carle M.; Preusker, Frank; Roatsch, Thomas; Stephan, Katrin; Wagner, Roland J.; Russell, Christopher T.; Raymond, Carol A.

    2016-04-01

    Cereś surface is affected by numerous impact craters and some of them show features such as channels or multiple flow events forming a smooth, less cratered surface, indicating possible post-impact resurfacing [1,2]. Flow features occur on several craters on Ceres such as Haulani, Ikapati, Occator, Jarimba and Kondos in combination with smooth crater floors [3,4], appearing as extended plains, ponded material, lobate flow fronts and in the case of Haulani lobate flows originating from the crest of the central ridge [3] partly overwhelming the mass wasting deposits from the rim. Haulanís crater flanks are also affected by multiple flow events radiating out from the crater and partly forming breakages. Flows occur as fine-grained lobes with well-defined margins and as smooth undifferentiated streaky flows covering the adjacent surface. Thus, adjacent craters are covered by flow material. Occator also exhibits multiple flows but in contrast to Haulani, the flows originating from the center overwhelm the mass wasting deposits from the rim [4]. The flows have a "bluish" signature in the FC color filters ratio. Channels occur at relatively fresh craters. They also show the "bluish" signature like the flows and plains. Only few channels occur at older "reddish" craters. They are relatively fresh incised into flow features or crater ejecta. Most are small, narrow and have lobated lobes with predominant distinctive flow margins. The widths vary between a few tens of meters to about 3 km. The channels are found on crater flanks as well as on the crater floors. The occurrence of flow features indicates viscous material on the surface. Those features could be formed by impact melt. However, impact melt is produced during the impact, assuming similar material properties as the ejecta it is expected to have nearly the same age as the impact itself, but the flows and plains are almost free of craters, thus, they seem to be much younger than the impact itself. In addition, the

  10. Scientific Objectives of Small Carry-on Impactor (SCI) and Deployable Camera 3 Digital (DCAM3-D): Observation of an Ejecta Curtain and a Crater Formed on the Surface of Ryugu by an Artificial High-Velocity Impact

    Science.gov (United States)

    Arakawa, M.; Wada, K.; Saiki, T.; Kadono, T.; Takagi, Y.; Shirai, K.; Okamoto, C.; Yano, H.; Hayakawa, M.; Nakazawa, S.; Hirata, N.; Kobayashi, M.; Michel, P.; Jutzi, M.; Imamura, H.; Ogawa, K.; Sakatani, N.; Iijima, Y.; Honda, R.; Ishibashi, K.; Hayakawa, H.; Sawada, H.

    2016-10-01

    The Small Carry-on Impactor (SCI) equipped on Hayabusa2 was developed to produce an artificial impact crater on the primitive Near-Earth Asteroid (NEA) 162173 Ryugu (Ryugu) in order to explore the asteroid subsurface material unaffected by space weathering and thermal alteration by solar radiation. An exposed fresh surface by the impactor and/or the ejecta deposit excavated from the crater will be observed by remote sensing instruments, and a subsurface fresh sample of the asteroid will be collected there. The SCI impact experiment will be observed by a Deployable CAMera 3-D (DCAM3-D) at a distance of ˜1 km from the impact point, and the time evolution of the ejecta curtain will be observed by this camera to confirm the impact point on the asteroid surface. As a result of the observation of the ejecta curtain by DCAM3-D and the crater morphology by onboard cameras, the subsurface structure and the physical properties of the constituting materials will be derived from crater scaling laws. Moreover, the SCI experiment on Ryugu gives us a precious opportunity to clarify effects of microgravity on the cratering process and to validate numerical simulations and models of the cratering process.

  11. Scientific Objectives of Small Carry-on Impactor (SCI) and Deployable Camera 3 Digital (DCAM3-D): Observation of an Ejecta Curtain and a Crater Formed on the Surface of Ryugu by an Artificial High-Velocity Impact

    Science.gov (United States)

    Arakawa, M.; Wada, K.; Saiki, T.; Kadono, T.; Takagi, Y.; Shirai, K.; Okamoto, C.; Yano, H.; Hayakawa, M.; Nakazawa, S.; Hirata, N.; Kobayashi, M.; Michel, P.; Jutzi, M.; Imamura, H.; Ogawa, K.; Sakatani, N.; Iijima, Y.; Honda, R.; Ishibashi, K.; Hayakawa, H.; Sawada, H.

    2017-07-01

    The Small Carry-on Impactor (SCI) equipped on Hayabusa2 was developed to produce an artificial impact crater on the primitive Near-Earth Asteroid (NEA) 162173 Ryugu (Ryugu) in order to explore the asteroid subsurface material unaffected by space weathering and thermal alteration by solar radiation. An exposed fresh surface by the impactor and/or the ejecta deposit excavated from the crater will be observed by remote sensing instruments, and a subsurface fresh sample of the asteroid will be collected there. The SCI impact experiment will be observed by a Deployable CAMera 3-D (DCAM3-D) at a distance of ˜1 km from the impact point, and the time evolution of the ejecta curtain will be observed by this camera to confirm the impact point on the asteroid surface. As a result of the observation of the ejecta curtain by DCAM3-D and the crater morphology by onboard cameras, the subsurface structure and the physical properties of the constituting materials will be derived from crater scaling laws. Moreover, the SCI experiment on Ryugu gives us a precious opportunity to clarify effects of microgravity on the cratering process and to validate numerical simulations and models of the cratering process.

  12. Flow Control

    Science.gov (United States)

    2013-04-08

    an aerodynamic design. A few examples of this type of flow control are winglets , fins, or dimples on a golf ball. The other type of flow control is...represented the density states of the flow field. The first parameter was the composition of the regression vector, Θ j. This regression vector was...Development Using Proper Orthogonal De- composition and Volterra Theory. In AIAA 2003-1922, 2003. A. Mani, M. Wang, and P. Moin. Resolution requirements

  13. Rotating flow

    CERN Document Server

    Childs, Peter R N

    2010-01-01

    Rotating flow is critically important across a wide range of scientific, engineering and product applications, providing design and modeling capability for diverse products such as jet engines, pumps and vacuum cleaners, as well as geophysical flows. Developed over the course of 20 years' research into rotating fluids and associated heat transfer at the University of Sussex Thermo-Fluid Mechanics Research Centre (TFMRC), Rotating Flow is an indispensable reference and resource for all those working within the gas turbine and rotating machinery industries. Traditional fluid and flow dynamics

  14. Network Flows

    Science.gov (United States)

    1988-12-01

    Researchers have suggested other solution strategies, using ideas from nonlinear progamming for solving this general separable convex cost flow problems. Some...plane methods and branch and bound procedures of integer programming, primal-dual methods of linear and nonlinear programming, and polyhedral methods...Combinatorial Optimization: Networks and Matroids), Bazaraa and Jarvis [1978] (Linear Programming and Network Flows), Minieka [1978] (Optimization Algorithms for

  15. Vortical flows

    CERN Document Server

    Wu, Jie-Zhi; Zhou, Ming-De

    2015-01-01

    This book is a comprehensive and intensive book for graduate students in fluid dynamics as well as scientists, engineers and applied mathematicians. Offering a systematic introduction to the physical theory of vortical flows at graduate level, it considers the theory of vortical flows as a branch of fluid dynamics focusing on shearing process in fluid motion, measured by vorticity. It studies vortical flows according to their natural evolution stages,from being generated to dissipated. As preparation, the first three chapters of the book provide background knowledge for entering vortical flows. The rest of the book deals with vortices and vortical flows, following their natural evolution stages. Of various vortices the primary form is layer-like vortices or shear layers, and secondary but stronger form is axial vortices mainly formed by the rolling up of shear layers.  Problems are given at the end of each chapter and Appendix, some for helping understanding the basic theories, and some involving specific ap...

  16. Worldwide environmental impacts from the eruption of Thera

    Science.gov (United States)

    Lamoreaux, P. E.

    1995-10-01

    The eruptions of Thera (Santorini) between 1628 and 1450 BC constituted a natural catastrophe unparalleled in all of history. The last major eruption in 1450 BC destroyed the entire Minoan Fleet at Crete at a time when the Minoans dominated the Mediterranean world. In addition, there had to be massive loss of life from ejecta gases, volcanic ash, bombs, and flows. The collapse of a majestic mountain into a caldera 15 km in diameter caused a giant ocean wave, a tsunami, that at its source was estimated in excess of 46 m high. The tsunami destroyed ships as far away as Crete (105 km) and killed thousands of people along the shorelines in the eastern Mediterranean area. At distant points in Asia Minor and Africa, there was darkness from ash fallout, lightning, and destructive earthquakes. Earthquake waves emanating from the epicenter near the ancient volcano were felt as far away as the Norwegian countries. These disturbances caused great physical damage in the eastern Mediterranean and along the rift valley system from Turkey to the south into central Africa. They caused major damage and fires in north Africa from Sinai to Alexandria, Egypt. Volcanic ash spread upward as a pillar of fire and clouds into the atmosphere and blocked out the sun for many days. The ash reached the stratosphere and moved around the world where the associated gases and fine particulate matter impacted the atmosphere, soils, and waters. Ground-hugging, billowing gases moved along the water surface and destroyed all life downwind, probably killing those who attempted to flee from Thera. The deadly gases probably reached the shores of north Africa. Climatic changes were the aftermath of the eruption and the atmospheric plume was to eventually affect the bristlecone pine of California; the bog oaks of Ireland, England, and Germany, and the grain crops of China. Historical eruptions at Krakatau, Tambora, Vesuvius, and, more currently, eruptions at Nevado del Ruiz, Pinatubo, and Mount Saint

  17. Non-Thermal Radio Emission from Colliding Flows in Classical Nova V1723 Aql

    CERN Document Server

    Weston, Jennifer H S; Metzger, Brian D; Zheng, Yong; Chomiuk, Laura; Krauss, Miriam I; Linford, Justin; Nelson, Thomas; Mioduszewski, Amy; Rupen, Michael P; Finzell, Tom; Mukai, Koji

    2015-01-01

    The importance of shocks in nova explosions has been highlighted by the recent discovery of \\gamma-ray producing novae by Fermi. We use over three years of multi-band radio observations of nova V1723 Aql with the Karl G. Jansky Very Large Array (VLA) to show that shocks between fast and slow flows within the ejecta led to the acceleration of particles and the production of synchrotron radiation. Approximately one month after the start of V1723 Aql's eruption in 2010 September, shocks in the ejecta produced an unexpected radio flare, ultimately resulting in a radio light curve with a multi-peaked structure. More than a year after the start of the eruption, the radio emission became consistent with emanating from an expanding thermal remnant with a mass of $2\\times10^{-4}$ M$_\\odot$ and a temperature of $10^4$ K. However, the brightness temperature of greater than $10^6$ K at low frequencies during the first two months was too high to be due to thermal emission from the small amount of X-ray producing shock-hea...

  18. Lubrication Flows.

    Science.gov (United States)

    Papanastasiou, Tasos C.

    1989-01-01

    Discusses fluid mechanics for undergraduates including the differential Navier-Stokes equations, dimensional analysis and simplified dimensionless numbers, control volume principles, the Reynolds lubrication equation for confined and free surface flows, capillary pressure, and simplified perturbation techniques. Provides a vertical dip coating…

  19. Flow Separation

    Science.gov (United States)

    1975-11-01

    Born, Constantin Caratheodory, Richard Couiant, Kurt Friedrichs, Werner Heisenberg, Gustav Herglotz, Erich von Hoist, Pascual Jordan, Walther Nernst...existence of these two flow regimes in boundary layers was discovered by PRANDTL when EIFFEL [8] published in 1912 his measurements on the drag of...simultaneously by G. EIFFEL in Paris and became so successful that other wind tunnels were modelled after it in many countries. Fig. 18 gives an impression of

  20. Media Flow

    DEFF Research Database (Denmark)

    Kabel, Lars

    2016-01-01

    News and other kinds of journalistic stories, 16-17 hours a day, all year round, on all platforms, also the moderated social media. The key research thesis behind this article is that the continuous and speedy stream of news stories and media content now is becoming the centre of the production...... processes and the value creation in converged multimedia newsrooms. The article identify new methods and discuss editorial challenges in handling media flow....

  1. Flow and Flow Decay of Refractory Castables

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhiqiang; Bjom Myhre; Bjorn Sandberg

    2003-01-01

    Installation of refractoty castables depend not only on flow, but also on how soon the flow is lost because of setting. The loss of flow (flow decay) has always been one of the main problems of refractory castable manufacturers,a problem that has not been too well described in literature. The flow decay has been studied for a castable system based on alumina, pointing out some general trends. The flow decay was found very temperature sensitive, being strongly accelerated by termperature increases. To compensate for excessive flow loss, a retarder like citric acid may be used. Thus flow decay was measured as a function of citric acid (retarder) addition at 35 ℃ .

  2. Chips Off an Old Lava Flow

    Science.gov (United States)

    Taylor, G. J.

    2007-12-01

    Photogeologic and remote sensing studies of the Moon show that many light-colored, smooth areas in the highlands contain craters surrounded by dark piles of excavated debris. The dark deposits resemble the dark basalts that make up the lunar maria. They contain the same diagnostic minerals (especially high-calcium pyroxene) and chemical compositions (high iron oxide) as do mare basalts. The deposits formed when vast amounts of material ejected during the formation of giant impact basins covered pre-existing lava plains. Since the smooth plains are older than the youngest impact basin (about 3.8 billion years old), the lavas must have erupted before formation of the visible maria. In fact, they were visible maria for a while eons ago, but were buried by ejecta when the basins formed. We have samples of these ancient mare basalts. They reside in breccias collected from the lunar highlands. Age dating indicates that the chips have ages of 3.9 billion years and older. The oldest dated mare basalt in the Apollo collection is 4.23 billion years. Now Kentaro Terada (Hiroshima University, Japan), Mahesh Anand (Open University, UK), Anna Sokol and Addi Bischoff (Institute for Planetology, Muenster, Germany), and Yuji Sano (The University of Tokyo, Japan) have determined the age of pieces of an ancient lava flow in a lunar meteorite, Kalahari 009, found in Botswana in 1999. The team dated this very low-titanium mare basalt by using an ion microprobe to measure the isotopic composition of lead and uranium in phosphate minerals. They found that the basalt fragments in the rock have an age of about 4.35 (plus or minus 0.15) billion years. This overlaps with the ages of chemically-distinct igneous rocks from the highlands, indicating that diverse magmas were being produced early in the history of the Moon.

  3. Ultrasonic flow meter

    NARCIS (Netherlands)

    Lötters, Joost Conrad; Snijders, G.J.; Volker, A.W.F.

    2014-01-01

    The invention relates to an ultrasonic flow meter comprising a flow tube for the fluid whose flow rate is to be determined. The flow meter comprises a transmitting element for emitting ultrasonic waves, which is provided on the outer jacket of the flow tube. A receiving element, which is provided on

  4. Pyritic ash-flow tuff, Yucca Mountain, Nevada -- A discussion

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, S.I.; Larson, L.T.; Noble, D.C. [Univ. of Nevada, Reno, NV (United States)

    1994-12-31

    Textural and mineralogic evidence exists for at least one episode of widespread hydrothermal alteration of volcanic rocks deep in Yucca Mountain, Nevada. Despite this evidence, Castor et al. infer that most of the pyrite found in tuffs at Yucca Mountain was introduced as ejecta (lithic fragments) incorporated during the eruptions of the tuffs, rather than by in-situ hydrothermal activity. Their conclusions appear to be based on their observation that most of the pyrite resides in unaltered to variably altered and veined lithic fragments, whereas pyrite-bearing veins are absent in the tuff matrix, titanomagnetite and mafic phenocrysts in the matrix are generally not replaced by pyrite, and feldspar phenocrysts in the pyritic tuff matrix are generally unaltered. Castor et al. dismiss the much smaller quantities of pyrite disseminated in the tuff matrix, including relatively rare pyritized hornblende and biotite grains, as xenolithic as well. The pyritic tuffs belong to large-volume, subalkaline rhyolite ash-flow units (ca. > 150 to 250 km{sup 3} each). The interpretation of Castor et al. has broad implications for the temperature, fO{sub 2} and fS{sub 2} of major ash flow eruptions. Pyrite origin also bears on the nature of past fluid flow and water-rock reactions at Yucca Mountain, which in turn are important factors in assessing the potential for currently undiscovered mineral resources in the area of the proposed nuclear waste repository. We have studied core and cuttings from the same drill holes studied by Castor et al., as well as other drill holes. It is our contention that the inconsistent lateral and stratigraphic distribution of the pyrite, textural features of the pyrite, and phase stability considerations are incompatible with the {open_quotes}lithic{close_quotes} origin of Castor et al., and are more reasonably explained by in-situ formation from hydrothermal fluids containing low, but geochemically significant, concentrations of reduced sulfur.

  5. Gas flow measurement using laminar flow elements

    Energy Technology Data Exchange (ETDEWEB)

    Weigand, J. [Meriam Instrument, Cleveland, OH (United States)

    1994-12-31

    An instrument that measures gas volumetric flow rate using a capillary tube laminar-flow principle is described. Irs construction, operation, accuracy, and rangeability are presented. Discussion includes integrating the differential-pressure-producing flowmeter with appropriate temperature find pressure devices to produce a digital flowmeter system capable of measuring volumetric and mass flow rates. Typical applications are described.

  6. Flow of Aqueous Humor

    Science.gov (United States)

    ... Home Flow of Aqueous Humor Flow of Aqueous Humor Most, but not all, forms of glaucoma are ... remains normal when some of the fluid (aqueous humor) produced by the eye's ciliary body flows out ...

  7. Performance of Hayabusa2 DCAM3-D Camera for Short-Range Imaging of SCI and Ejecta Curtain Generated from the Artificial Impact Crater Formed on Asteroid 162137 Ryugu (1999 JU3)

    Science.gov (United States)

    Ishibashi, K.; Shirai, K.; Ogawa, K.; Wada, K.; Honda, R.; Arakawa, M.; Sakatani, N.; Ikeda, Y.

    2017-07-01

    Deployable Camera 3-D (DCAM3-D) is a small high-resolution camera equipped on Deployable Camera 3 (DCAM3), one of the Hayabusa2 instruments. Hayabusa2 will explore asteroid 162137 Ryugu (1999 JU3) and conduct an impact experiment using a liner shooting device called Small Carry-on Impactor (SCI). DCAM3 will be detached from the Hayabusa2 spacecraft and observe the impact experiment. The purposes of the observation are to know the impact conditions, to estimate the surface structure of asteroid Ryugu, and to understand the physics of impact phenomena on low-gravity bodies. DCAM3-D requires high imaging performance because it has to image and detect multiple targets of different scale and radiance, i.e., the faint SCI before the shot from 1-km distance, the bright ejecta generated by the impact, and the asteroid. In this paper we report the evaluation of the performance of the CMOS imaging sensor and the optical system of DCAM3-D. We also describe the calibration of DCAM3-D. We confirmed that the imaging performance of DCAM3-D satisfies the required values to achieve the purposes of the observation.

  8. Properties and Radial Trends of Coronal Mass Ejecta and Their Associated Shocks Observed by Ulysses in the Ecliptic Plane. Appendix 2; Repr. from Journal of Geophysical Research, v. 105, 2000 p 12,617-12,626

    Science.gov (United States)

    Riley, Pete; Gosling, J. T.; McComas, D. J.; Forsyth, R. J.

    2001-01-01

    In this paper, magnetic and plasma measurements are used to analyze 17 interplanetary coronal mass ejections (CMEs) identified by Ulysses during its in-ecliptic passage to Jupiter. We focus on the expansion characteristics of these CMEs (as inferred from the time rate of change of the velocity profiles through the CMEs) and the properties of 14 forward shocks unambiguously associated with these CMEs. We highlight radial trends from 1 to 5.4 AU. Our results indicate that the CMEs are generally expanding at all heliocentric distances. With regard to the shocks preceding these ejecta, we note the following: (1) There is a clear tendency for the shock speed (in the upstream frame of reference) to decrease with increasing heliocentric distance as the CMEs transfer momentum to the ambient solar wind and slow down; (2) 86% of the shock fronts are oriented in the ecliptic plane such that their normals point westward (i.e., in the direction of planetary motion about the Sun), (3) 86% of the shocks are propagating toward the heliographic equator; and (4) no clear trend was found in the strength of the shocks versus heliocentric distance. These results are interpreted using simple dynamical arguments and are supported by fluid and magnetohydrodynamic (MHD) simulations.

  9. Performance of Hayabusa2 DCAM3-D Camera for Short-Range Imaging of SCI and Ejecta Curtain Generated from the Artificial Impact Crater Formed on Asteroid 162137 Ryugu (1999 JU3)

    Science.gov (United States)

    Ishibashi, K.; Shirai, K.; Ogawa, K.; Wada, K.; Honda, R.; Arakawa, M.; Sakatani, N.; Ikeda, Y.

    2016-11-01

    Deployable Camera 3-D (DCAM3-D) is a small high-resolution camera equipped on Deployable Camera 3 (DCAM3), one of the Hayabusa2 instruments. Hayabusa2 will explore asteroid 162137 Ryugu (1999 JU3) and conduct an impact experiment using a liner shooting device called Small Carry-on Impactor (SCI). DCAM3 will be detached from the Hayabusa2 spacecraft and observe the impact experiment. The purposes of the observation are to know the impact conditions, to estimate the surface structure of asteroid Ryugu, and to understand the physics of impact phenomena on low-gravity bodies. DCAM3-D requires high imaging performance because it has to image and detect multiple targets of different scale and radiance, i.e., the faint SCI before the shot from 1-km distance, the bright ejecta generated by the impact, and the asteroid. In this paper we report the evaluation of the performance of the CMOS imaging sensor and the optical system of DCAM3-D. We also describe the calibration of DCAM3-D. We confirmed that the imaging performance of DCAM3-D satisfies the required values to achieve the purposes of the observation.

  10. Optimal Power Flow with Power Flow Routers

    OpenAIRE

    2016-01-01

    Power flow routing is an emerging control paradigm for the dynamic control of electric power flows. In this paper, we propose a generic model of a power flow router (PFR) and incorporate it into the optimal power flow (OPF) problem. First, a generic PFR architecture is proposed to encapsulate the desired functions of PFRs. Then, the load flow model of PFRs is developed and incorporated into the OPF framework. To pursue global optimality of the non-convex PFR-incorporated OPF (PFR-OPF) problem...

  11. Flow Distances on Open Flow Networks

    CERN Document Server

    Guo, Liangzhu; Shi, Peiteng; Wang, Jun; Huang, Xiaohan; Zhang, Jiang

    2015-01-01

    Open flow network is a weighted directed graph with a source and a sink, depicting flux distributions on networks in the steady state of an open flow system. Energetic food webs, economic input-output networks, and international trade networks, are open flow network models of energy flows between species, money or value flows between industrial sectors, and goods flows between countries, respectively. Flow distances (first-passage or total) between any given two nodes $i$ and $j$ are defined as the average number of transition steps of a random walker along the network from $i$ to $j$ under some conditions. They apparently deviate from the conventional random walk distance on a closed directed graph because they consider the openness of the flow network. Flow distances are explicitly expressed by underlying Markov matrix of a flow system in this paper. With this novel theoretical conception, we can visualize open flow networks, calculating centrality of each node, and clustering nodes into groups. We apply fl...

  12. Evolution and Flow.

    Science.gov (United States)

    Csikszentmihalyi, Mihaly

    1997-01-01

    Presents flow theory in the context of evolution. Defines the elements of "flow" and contends that flow results in an optimal state of inner harmony which improves one's chance for survival. Identifies consequences of flow for creativity, peak performance, talent development, productivity, self-esteem, and stress reduction. Examines the…

  13. Impact crater relaxation on Dione and Tethys and relation to past heat flow

    Science.gov (United States)

    White, Oliver L.; Schenk, Paul M.; Bellagamba, Anthony W.; Grimm, Ashley M.; Dombard, Andrew J.; Bray, Veronica J.

    2017-05-01

    Relating relaxation of impact crater topography to past heat flow through the crusts of icy satellites is a technique that has been applied to satellites around Jupiter and Saturn. We use global digital elevation models of the surfaces of Dione and Tethys generated from Cassini data to obtain crater depth/diameter (d/D) data. Relaxation is found to affect craters down to smaller diameters on these satellites compared to Rhea. We perform relaxation simulations in order to assess the heat flow necessary to relax craters on Dione and Tethys to their present morphologies. Heat flows exceeding 60 mW m-2 are required to relax several craters on both satellites, and relaxation appears to be subject to geographical controls. On Dione, we define a 'relaxation dichotomy' that separates the more relaxed craters in sparsely cratered plains from the less relaxed craters in heavily cratered terrain. The configuration of this dichotomy resembles that of the structural-geological dichotomy on Enceladus, implying that a similar resonance-induced tidal heating mechanism concentrated in the southern hemisphere may have affected both satellites. Defining geographical distribution of relaxation on Tethys is hindered by the presence of the young Odysseus impact and its associated ejecta.

  14. Thermal flow micro sensors

    OpenAIRE

    Elwenspoek, M.

    1999-01-01

    A review is given on sensors fabricated by silicon micromachining technology using the thermal domain for the measurement of fluid flow. Attention is paid especially to performance and geometry of the sensors. Three basic types of thermal flow sensors are discussed: anemometers, calorimetric flow sensors and time of flight flow sensors. Anemometers may comprise several heaters and temperature sensors and from a geometric point of view are similar sometimes for calorimetric flow sensors. We fi...

  15. Ricci flow coupled with harmonic map flow

    CERN Document Server

    Müller, Reto

    2009-01-01

    We investigate a new geometric flow which consists of a coupled system of the Ricci flow on a closed manifold M with the harmonic map flow of a map phi from M to some closed target manifold N with a (possibly time-dependent) positive coupling constant alpha. This system can be interpreted as the gradient flow of an energy functional F_alpha which is a modification of Perelman's energy F for the Ricci flow, including the Dirichlet energy for the map phi. Surprisingly, the coupled system may be less singular than the Ricci flow or the harmonic map flow alone. In particular, we can always rule out energy concentration of phi a-priori - without any assumptions on the curvature of the target manifold N - by choosing alpha large enough. Moreover, if alpha is bounded away from zero it suffices to bound the curvature of (M,g(t)) to also obtain control of phi and all its derivatives - a result which is clearly not true for alpha = 0. Besides these new phenomena, the flow shares many good properties with the Ricci flow...

  16. Introduction to compressible fluid flow

    CERN Document Server

    Oosthuizen, Patrick H

    2013-01-01

    IntroductionThe Equations of Steady One-Dimensional Compressible FlowSome Fundamental Aspects of Compressible FlowOne-Dimensional Isentropic FlowNormal Shock WavesOblique Shock WavesExpansion Waves - Prandtl-Meyer FlowVariable Area FlowsAdiabatic Flow with FrictionFlow with Heat TransferLinearized Analysis of Two-Dimensional Compressible FlowsHypersonic and High-Temperature FlowsHigh-Temperature Gas EffectsLow-Density FlowsBibliographyAppendices

  17. Flow Element Models

    DEFF Research Database (Denmark)

    Heiselberg, Per; Nielsen, Peter V.

    Air distribution in ventilated rooms is a flow process that can be divided into different elements such as supply air jets, exhaust flows, thermal plumes, boundary layer flows, infiltration and gravity currents. These flow elements are isolated volumes where the air movement is controlled...... by a restricted number of parameters, and the air movement is fairly independent of the general flow in the enclosure. In many practical situations, the most convenient· method is to design the air distribution system using flow element theory....

  18. Unsteady flow volumes

    Energy Technology Data Exchange (ETDEWEB)

    Becker, B.G.; Lane, D.A.; Max, N.L.

    1995-03-01

    Flow volumes are extended for use in unsteady (time-dependent) flows. The resulting unsteady flow volumes are the 3 dimensional analog of streamlines. There are few examples where methods other than particle tracing have been used to visualize time varying flows. Since particle paths can become convoluted in time there are additional considerations to be made when extending any visualization technique to unsteady flows. We will present some solutions to the problems which occur in subdivision, rendering, and system design. We will apply the unsteady flow volumes to a variety of field types including moving multi-zoned curvilinear grids.

  19. Dynamic power flow controllers

    Science.gov (United States)

    Divan, Deepakraj M.; Prasai, Anish

    2017-03-07

    Dynamic power flow controllers are provided. A dynamic power flow controller may comprise a transformer and a power converter. The power converter is subject to low voltage stresses and not floated at line voltage. In addition, the power converter is rated at a fraction of the total power controlled. A dynamic power flow controller controls both the real and the reactive power flow between two AC sources having the same frequency. A dynamic power flow controller inserts a voltage with controllable magnitude and phase between two AC sources; thereby effecting control of active and reactive power flows between two AC sources.

  20. Runout distance and dynamic pressure of pyroclastic density currents: Evidence from 18 May 1980 blast surge of Mount St. Helens

    Science.gov (United States)

    Gardner, J. E.; Andrews, B. J.

    2016-12-01

    Pyroclastic density currents (flows and surges) are one of the most deadly hazards associated with volcanic eruptions. Understanding what controls how far such currents will travel, and how their dynamic pressure evolves, could help mitigate their hazards. The distance a ground hugging, pyroclastic density current travels is partly limited by when it reverses buoyancy and lifts off into the atmosphere. The 1980 blast surge of Mount St. Helens offers an example of a current seen to lift off. Before lofting, it had traveled up to 20 km and leveled more than 600 km3 of thick forest (the blowdown zone). The outer edge of the devastated area - where burned trees that were left standing (the singe zone) - is where the surge is thought to have lifted off. We recently examined deposits in the outer parts of the blowdown and in the singe zone at 32 sites. The important finding is that the laterally moving surge travelled into the singe zone, and hence the change in tree damage does not mark the run out distance of the ground hugging surge. Eyewitness accounts and impacts on trees and vehicles reveal that the surge consisted of a fast, dilute "overcurrent" and a slower "undercurrent", where most of the mass (and heat) was retained. Reasonable estimates for flow density and velocity show that dynamic pressure of the surge (i.e., its ability to topple trees) peaked near the base of the overcurrent. We propose that when the overcurrent began to lift off, the height of peak dynamic pressure rose above the trees and stopped toppling them. The slower undercurrent continued forward, burning trees but it lacked the dynamic pressure needed to topple them. Grain-size variations argue that it slowed from 30 m/s when it entered the singe zone to 3 m/s at the far end. Buoyancy reversal and liftoff are thus not preserved in the deposits where the surge lofted upwards.

  1. A Nonideal Flow Experiment.

    Science.gov (United States)

    Gonzalez-Velasco, Juan Ramon; Elorriaga, Javier Bilbao

    1984-01-01

    Considers the deviation from the ideal flows of both a backmix tank and a backmix tank followed by a flow vessel. Background information, apparatus used, and experimental procedures are provided. Typical results are also provided and discussed. (JN)

  2. Counting RG flows

    OpenAIRE

    Gukov, Sergei

    2016-01-01

    Interpreting renormalization group flows as solitons interpolating between different fixed points, we ask various questions that are normally asked in soliton physics but not in renormalization theory. Can one count RG flows? Are there different "topological sectors" for RG flows? What is the moduli space of an RG flow, and how does it compare to familiar moduli spaces of (supersymmetric) dowain walls? Analyzing these questions in a wide variety of contexts --- from counting RG walls to AdS/C...

  3. Thermal flow micro sensors

    NARCIS (Netherlands)

    Elwenspoek, M.

    1999-01-01

    A review is given on sensors fabricated by silicon micromachining technology using the thermal domain for the measurement of fluid flow. Attention is paid especially to performance and geometry of the sensors. Three basic types of thermal flow sensors are discussed: anemometers, calorimetric flow se

  4. Free surface flow focusing

    NARCIS (Netherlands)

    Peters, I.R.

    2012-01-01

    Reducing the area through which a fluid is allowed to flow often leads to an increase of flow velocity. A familiar example of this is a garden hose, where one can change the rather weak stream that usually flows out into a strong jet by narrowing the orifice at the end of the hose. In this example,

  5. Integer Equal Flows

    Energy Technology Data Exchange (ETDEWEB)

    Meyers, C A; Schulz, A S

    2009-01-07

    The integer equal flow problem is an NP-hard network flow problem, in which all arcs in given sets R{sub 1}, ..., R{sub {ell}} must carry equal flow. We show this problem is effectively inapproximable, even if the cardinality of each set R{sub k} is two. When {ell} is fixed, it is solvable in polynomial time.

  6. OpenFlow cookbook

    CERN Document Server

    Smiler S, Kingston

    2015-01-01

    This book is intended for network protocol developers, SDN controller application developers, and academics who would like to understand and develop their own OpenFlow switch or OpenFlow controller in any programming language. With basic understanding of OpenFlow and its components, you will be able to follow the recipes in this book.

  7. Distributed Power Flow Controller

    NARCIS (Netherlands)

    Yuan, Z.

    2010-01-01

    In modern power systems, there is a great demand to control the power flow actively. Power flow controlling devices (PFCDs) are required for such purpose, because the power flow over the lines is the nature result of the impedance of each line. Due to the control capabilities of different types of P

  8. Free surface flow focusing

    NARCIS (Netherlands)

    Peters, I.R.

    2012-01-01

    Reducing the area through which a fluid is allowed to flow often leads to an increase of flow velocity. A familiar example of this is a garden hose, where one can change the rather weak stream that usually flows out into a strong jet by narrowing the orifice at the end of the hose. In this example,

  9. STOCHASTIC FLOWS OF MAPPINGS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper, the stochastic flow of mappings generated by a Feller convolution semigroup on a compact metric space is studied. This kind of flow is the generalization of superprocesses of stochastic flows and stochastic diffeomorphism induced by the strong solutions of stochastic differential equations.

  10. Distributed Power Flow Controller

    NARCIS (Netherlands)

    Yuan, Z.

    2010-01-01

    In modern power systems, there is a great demand to control the power flow actively. Power flow controlling devices (PFCDs) are required for such purpose, because the power flow over the lines is the nature result of the impedance of each line. Due to the control capabilities of different types of P

  11. Flow lab.: flow visualization and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chung Kyun; Cho, Won Jin; Hahn, Pil Soo [Korea Atomic Energy Research Institute, Taejeon (Korea, Republic of)

    2005-11-15

    The experimental setups for flow visualization and processes identification in laboratory scale (so called Flow Lab.) has developed to get ideas and answer fundamental questions of flow and migration in geologic media. The setup was made of a granite block of 50x50cm scale and a transparent acrylate plate. The tracers used in this experiments were tritiated water, anions, and sorbing cations as well as an organic dye, eosine, to visualize migration paths. The migration plumes were taken with a digital camera as a function of time and stored as digital images. A migration model was also developed to describe and identify the transport processes. Computer simulation was carried out not only for the hydraulic behavior such as distributions of pressure and flow vectors in the fracture but also for the migration plume and the elution curves.

  12. Stable Flows over Time

    Directory of Open Access Journals (Sweden)

    Jannik Matuschke

    2013-08-01

    Full Text Available In this paper, the notion of stability is extended to network flows over time. As a useful device in our proofs, we present an elegant preflow-push variant of the Gale-Shapley algorithm that operates directly on the given network and computes stable flows in pseudo-polynomial time, both in the static flow and the flow over time case. We show periodical properties of stable flows over time on networks with an infinite time horizon. Finally, we discuss the influence of storage at vertices, with different results depending on the priority of the corresponding holdover edges.

  13. Signal flow analysis

    CERN Document Server

    Abrahams, J R; Hiller, N

    1965-01-01

    Signal Flow Analysis provides information pertinent to the fundamental aspects of signal flow analysis. This book discusses the basic theory of signal flow graphs and shows their relation to the usual algebraic equations.Organized into seven chapters, this book begins with an overview of properties of a flow graph. This text then demonstrates how flow graphs can be applied to a wide range of electrical circuits that do not involve amplification. Other chapters deal with the parameters as well as circuit applications of transistors. This book discusses as well the variety of circuits using ther

  14. Separation of flow

    CERN Document Server

    Chang, Paul K

    2014-01-01

    Interdisciplinary and Advanced Topics in Science and Engineering, Volume 3: Separation of Flow presents the problem of the separation of fluid flow. This book provides information covering the fields of basic physical processes, analyses, and experiments concerning flow separation.Organized into 12 chapters, this volume begins with an overview of the flow separation on the body surface as discusses in various classical examples. This text then examines the analytical and experimental results of the laminar boundary layer of steady, two-dimensional flows in the subsonic speed range. Other chapt

  15. Explosions inside Ejecta and Most Luminous Supernovae

    CERN Document Server

    Blinnikov, S I

    2008-01-01

    The extremely luminous supernova SN2006gy is explained in the same way as other SNIIn events: light is produced by a radiative shock propagating in a dense circumstellar envelope formed by a previous weak explosion. The problems in the theory and observations of multiple-explosion SNe IIn are briefly reviewed.

  16. Dynamics of Enceladus South Pole Ejecta

    Science.gov (United States)

    Makuch, Martin; Schmidt, J.; Spahn, F.

    2007-10-01

    The Saturnian moon Enceladus was recently found to be a potent source of gas and dust particles. There was an active region observed on the south pole of Enceladus with jets spraying material in the space. The ejected dust particles are considered to be the main source of the faint E ring. In our work we investigate the long-term dynamics of icy particles ejected from the south pole of Enceladus. The motion of the ejected grains, being subject to many perturbation forces, strongly depends on particle properties (e.g. size, charge etc.). We study the resulting spatial distribution of particles in the E ring. Primarily we focus on the structure of the ring in the vicinity of Enceladus. In our study we also concentrated on processes limiting particle lifetime. These are mainly collisions with Enceladus and other Saturnian satellites or main ring, as well as the sputtering of particles by plasma ions bombardment. Modeling the equilibrium between particle sources and sinks we found the size distribution which is expected to be observed in the E ring.

  17. Group flow, complex flow, unit vector flow, and the (2+ϵ)-flow conjecture

    DEFF Research Database (Denmark)

    Thomassen, Carsten

    2014-01-01

    If F is a (possibly infinite) subset of an abelian group Γ, then we define f(F,Γ) as the smallest natural number such that every f(F,Γ)-edge-connected (finite) graph G has a flow where all flow values are elements in F. We prove that f(F,Γ) exists if and only if some odd sum of elements in F equals...... some even sum. We discuss various instances of this problem. We prove that every 6-edge-connected graph has a flow whose flow values are the three roots of unity in the complex plane. If the edge-connectivity 6 can be reduced, then it can be reduced to 4, and the 3-flow conjecture follows. We prove...... that every 14-edge-connected graph has a flow whose flow values are the five roots of unity in the complex plane. Any such flow is balanced modulo 5. So, if the edge-connectivity 14 can be reduced to 9, then the 5-flow conjecture follows, as observed by F. Jaeger. We use vector flow to prove that, for each...

  18. Concentric Split Flow Filter

    Science.gov (United States)

    Stapleton, Thomas J. (Inventor)

    2015-01-01

    A concentric split flow filter may be configured to remove odor and/or bacteria from pumped air used to collect urine and fecal waste products. For instance, filter may be designed to effectively fill the volume that was previously considered wasted surrounding the transport tube of a waste management system. The concentric split flow filter may be configured to split the air flow, with substantially half of the air flow to be treated traveling through a first bed of filter media and substantially the other half of the air flow to be treated traveling through the second bed of filter media. This split flow design reduces the air velocity by 50%. In this way, the pressure drop of filter may be reduced by as much as a factor of 4 as compare to the conventional design.

  19. TRANSIMS traffic flow characteristics

    CERN Document Server

    Nagel, K; Pieck, M; Donnelly, R; Barrett, C L; Nagel, Kai; Stretz, Paula; Pieck, Martin; Donnelly, Rick; Barrett, Christopher L.

    1997-01-01

    Knowledge of fundamental traffic flow characteristics of traffic simulation models is an essential requirement when using these models for the planning, design, and operation of transportation systems. In this paper we discuss the following: a description of how features relevant to traffic flow are currently under implementation in the TRANSIMS microsimulation, a proposition for standardized traffic flow tests for traffic simulation models, and the results of these tests for two different versions of the TRANSIMS microsimulation.

  20. Polyoxometalate flow battery

    Science.gov (United States)

    Anderson, Travis M.; Pratt, Harry D.

    2016-03-15

    Flow batteries including an electrolyte of a polyoxometalate material are disclosed herein. In a general embodiment, the flow battery includes an electrochemical cell including an anode portion, a cathode portion and a separator disposed between the anode portion and the cathode portion. Each of the anode portion and the cathode portion comprises a polyoxometalate material. The flow battery further includes an anode electrode disposed in the anode portion and a cathode electrode disposed in the cathode portion.

  1. A neural flow estimator

    DEFF Research Database (Denmark)

    Jørgensen, Ivan Harald Holger; Bogason, Gudmundur; Bruun, Erik

    1995-01-01

    This paper proposes a new way to estimate the flow in a micromechanical flow channel. A neural network is used to estimate the delay of random temperature fluctuations induced in a fluid. The design and implementation of a hardware efficient neural flow estimator is described. The system...... is implemented using switched-current technique and is capable of estimating flow in the μl/s range. The neural estimator is built around a multiplierless neural network, containing 96 synaptic weights which are updated using the LMS1-algorithm. An experimental chip has been designed that operates at 5 V...

  2. Supersonic flows over cavities

    Institute of Scientific and Technical Information of China (English)

    Tianwen FANG; Meng DING; Jin ZHOU

    2008-01-01

    The characteristics of supersonic cold flows over cavities were investigated experimentally and numer-ically, and the effects of cavities of different sizes on super-sonic flow field were analyzed. The results indicate that the ratio of length to depth L/D within the range of 5-9 has little relevance to integral structures of cavity flow. The bevel angle of the rear wall does not alter the overall structure of the cavity flow within the range of 30°-60°, but it can exert obvious effect on the evolvement of shear layer and vortexes in cavities.

  3. Retinal flow cytometer.

    Science.gov (United States)

    Alt, C; Veilleux, I; Lee, H; Pitsillides, C M; Côté, D; Lin, C P

    2007-12-01

    The in vivo flow cytometer is an instrument capable of continuous, real-time monitoring of fluorescently labeled cells in the circulation without the need to draw blood samples. However, the original system probes a single vessel in the mouse ear; the small sample volume limits the sensitivity of the technique. We describe an in vivo retinal flow cytometer that simultaneously probes five artery-vein pairs in the mouse eye by circularly scanning a small laser spot rapidly around the optic nerve head. We demonstrate that the retinal flow cytometer detects about five times more cells per minute than the original in vivo flow cytometer does in the ear.

  4. Excess flow shutoff valve

    Energy Technology Data Exchange (ETDEWEB)

    Kiffer, Micah S.; Tentarelli, Stephen Clyde

    2016-02-09

    Excess flow shutoff valve comprising a valve body, a valve plug, a partition, and an activation component where the valve plug, the partition, and activation component are disposed within the valve body. A suitable flow restriction is provided to create a pressure difference between the upstream end of the valve plug and the downstream end of the valve plug when fluid flows through the valve body. The pressure difference exceeds a target pressure difference needed to activate the activation component when fluid flow through the valve body is higher than a desired rate, and thereby closes the valve.

  5. Asymmetric flow networks

    OpenAIRE

    Olaizola Ortega, María Norma; Valenciano Llovera, Federico

    2012-01-01

    This paper provides a new model of network formation that bridges the gap between the two benchmark models by Bala and Goyal, the one-way flow model, and the two-way flow model, and includes both as particular extreme cases. As in both benchmark models, in what we call an "asymmetric flow" network a link can be initiated unilaterally by any player with any other, and the flow through a link towards the player who supports it is perfect. Unlike those models, in the opposite direction there is ...

  6. The other spectral flow

    CERN Document Server

    Gato-Rivera, Beatriz; Gato-Rivera, Beatriz; Rosado, Jose Ignacio

    1995-01-01

    Recently we showed that the spectral flow acting on the N=2 twisted topological theories gives rise to a topological algebra automorphism. Here we point out that the untwisting of that automorphism leads to a spectral flow on the untwisted N=2 superconformal algebra which is different from the usual one. This "other" spectral flow does not interpolate between the chiral ring and the antichiral ring. In particular, it maps the chiral ring into the chiral ring and the antichiral ring into the antichiral ring. We discuss the similarities and differences between both spectral flows. We also analyze their action on null states.

  7. Flow chemistry is starting to flow

    NARCIS (Netherlands)

    Duisterwinkel, A.E.

    2012-01-01

    One good thing about this symposium on flow chemistry is that at least half of the papers was on actual applications: summarized one member of the audience of the IPIT symposium in Rotterdam, 25 May 2012. This remark can be viewed as a compliment to the organizer, TNO, a Dutch contract research orga

  8. Biomimetic Flow Sensors

    NARCIS (Netherlands)

    Casas, J.; Liu, Chang; Krijnen, G.J.M.

    2012-01-01

    Biomimetic flow sensors are biologically inspired devices that measure the speed and direction of fluids. This survey starts by describing the role and functioning of airflow-sensing hairs in arthropods and in fishes, carries on with the biomimetic MEMS implementations, both for air and water flow s

  9. RG Flows and Bifurcations

    CERN Document Server

    Gukov, Sergei

    2016-01-01

    Interpreting RG flows as dynamical systems in the space of couplings we produce a variety of constraints, global (topological) as well as local. These constraints, in turn, rule out some of the proposed RG flows and also predict new phases and fixed points, surprisingly, even in familiar theories such as O(N) model, QED-3, or QCD-4.

  10. Reversed extension flow

    DEFF Research Database (Denmark)

    Nielsen, Jens Kromann; Rasmussen, Henrik K.

    2008-01-01

    Afilament stretching rheometer (FSR) was used for measuring the start-up of uni-axial elongational flow followed by reversed bi-axial flow, both with a constant elongational rate. A narrow molecular mass distribution linear polystyrene with a molecular weight of 145 kg / mole wis subjected to the...

  11. AUTO-EXPANSIVE FLOW

    Science.gov (United States)

    Physics suggests that the interplay of momentum, continuity, and geometry in outward radial flow must produce density and concomitant pressure reductions. In other words, this flow is intrinsically auto-expansive. It has been proposed that this process is the key to understanding...

  12. Secondary Flows in Turbomachines

    Science.gov (United States)

    1990-02-01

    flow angle boundary layer velocity defect parameter 0 tangential flow angle a chord 0’ blade angle f wake profile model (Pohlhausen polynomial ) Y stagger...dconmpuser ce dernier en un 6coulement lUngitUdinial skd ant tutte direktkofl et kin 6&oulement, tranbversal directement hi6 A la vortikitt secondaire

  13. Forecasting freight flows

    DEFF Research Database (Denmark)

    Lyk-Jensen, Stéphanie

    2011-01-01

    Trade patterns and transport markets are changing as a result of the growth and globalization of international trade, and forecasting future freight flow has to rely on trade forecasts. Forecasting freight flows is critical for matching infrastructure supply to demand and for assessing investment...

  14. Vortex flow hysteresis

    Science.gov (United States)

    Cunningham, A. M., Jr.

    1986-01-01

    An experimental study was conducted to quantify the hysteresis associated with various vortex flow transition points and to determine the effect of planform geometry. The transition points observed consisted of the appearance (or disappearance) of trailing edge vortex burst and the transition to (or from) flat plate or totally separated flows. Flow visualization with smoke injected into the vortices was used to identify the transitions on a series of semi-span models tested in a low speed tunnel. The planforms tested included simple deltas (55 deg to 80 deg sweep), cranked wings with varying tip panel sweep and dihedral, and a straked wing. High speed movies at 1000 frames per second were made of the vortex flow visualization in order to better understand the dynamics of vortex flow, burst and transition.

  15. Data flow modeling techniques

    Science.gov (United States)

    Kavi, K. M.

    1984-01-01

    There have been a number of simulation packages developed for the purpose of designing, testing and validating computer systems, digital systems and software systems. Complex analytical tools based on Markov and semi-Markov processes have been designed to estimate the reliability and performance of simulated systems. Petri nets have received wide acceptance for modeling complex and highly parallel computers. In this research data flow models for computer systems are investigated. Data flow models can be used to simulate both software and hardware in a uniform manner. Data flow simulation techniques provide the computer systems designer with a CAD environment which enables highly parallel complex systems to be defined, evaluated at all levels and finally implemented in either hardware or software. Inherent in data flow concept is the hierarchical handling of complex systems. In this paper we will describe how data flow can be used to model computer system.

  16. Flows around bacterial swarms

    Science.gov (United States)

    Dauparas, Justas; Lauga, Eric

    2015-11-01

    Flagellated bacteria on nutrient-rich substrates can differentiate into a swarming state and move in dense swarms across surfaces. A recent experiment (HC Berg, Harvard University) measured the flow in the fluid around the swarm. A systematic chiral flow was observed in the clockwise direction (when viewed from above) ahead of a E.coli swarm with flow speeds of about 10 μm/s, about 3 times greater than the radial velocity at the edge of the swarm. The working hypothesis is that this flow is due to the flagella of cells stalled at the edge of a colony which extend their flagellar filaments outwards, moving fluid over the virgin agar. In this talk we quantitatively test his hypothesis. We first build an analytical model of the flow induced by a single flagellum in a thin film and then use the model, and its extension to multiple flagella, to compare with experimental measurements.

  17. Vega flow assurance system

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, Marit; Munaweera, Sampath

    2010-07-01

    Vega is a gas condensate field located at the west coast of Norway and developed as a tie-in to the Gjoea platform. Operator is Statoil, production startup is estimated to the end of 2010. Flow assurance challenges are high reservoir pressure and temperature, hydrate and wax control, liquid accumulation and monitoring the well/template production rates. The Vega Flow Assurance System (FAS) is a software that supports monitoring and operation of the field. The FAS is based FlowManagerTM designed for real time systems. This is a flexible tool with its own steady state multiphase- and flow assurance models. Due to the long flowlines lines and the dynamic behavior, the multiphase flow simulator OLGA is also integrated in the system. Vega FAS will be used as: - An online monitoring tool - An offline what-if simulation and validation tool - An advisory control system for well production allocation. (Author)

  18. Flow in bedrock canyons.

    Science.gov (United States)

    Venditti, Jeremy G; Rennie, Colin D; Bomhof, James; Bradley, Ryan W; Little, Malcolm; Church, Michael

    2014-09-25

    Bedrock erosion in rivers sets the pace of landscape evolution, influences the evolution of orogens and determines the size, shape and relief of mountains. A variety of models link fluid flow and sediment transport processes to bedrock incision in canyons. The model components that represent sediment transport processes are increasingly well developed. In contrast, the model components being used to represent fluid flow are largely untested because there are no observations of the flow structure in bedrock canyons. Here we present a 524-kilometre, continuous centreline, acoustic Doppler current profiler survey of the Fraser Canyon in western Canada, which includes 42 individual bedrock canyons. Our observations of three-dimensional flow structure reveal that, as water enters the canyons, a high-velocity core follows the bed surface, causing a velocity inversion (high velocities near the bed and low velocities at the surface). The plunging water then upwells along the canyon walls, resulting in counter-rotating, along-stream coherent flow structures that diverge near the bed. The resulting flow structure promotes deep scour in the bedrock channel floor and undercutting of the canyon walls. This provides a mechanism for channel widening and ensures that the base of the walls is swept clear of the debris that is often deposited there, keeping the walls nearly vertical. These observations reveal that the flow structure in bedrock canyons is more complex than assumed in the models presently used. Fluid flow models that capture the essence of the three-dimensional flow field, using simple phenomenological rules that are computationally tractable, are required to capture the dynamic coupling between flow, bedrock erosion and solid-Earth dynamics.

  19. Gas Flow Detection System

    Science.gov (United States)

    Moss, Thomas; Ihlefeld, Curtis; Slack, Barry

    2010-01-01

    This system provides a portable means to detect gas flow through a thin-walled tube without breaking into the tubing system. The flow detection system was specifically designed to detect flow through two parallel branches of a manifold with only one inlet and outlet, and is a means for verifying a space shuttle program requirement that saves time and reduces the risk of flight hardware damage compared to the current means of requirement verification. The prototype Purge Vent and Drain Window Cavity Conditioning System (PVD WCCS) Flow Detection System consists of a heater and a temperature-sensing thermistor attached to a piece of Velcro to be attached to each branch of a WCCS manifold for the duration of the requirement verification test. The heaters and thermistors are connected to a shielded cable and then to an electronics enclosure, which contains the power supplies, relays, and circuit board to provide power, signal conditioning, and control. The electronics enclosure is then connected to a commercial data acquisition box to provide analog to digital conversion as well as digital control. This data acquisition box is then connected to a commercial laptop running a custom application created using National Instruments LabVIEW. The operation of the PVD WCCS Flow Detection System consists of first attaching a heater/thermistor assembly to each of the two branches of one manifold while there is no flow through the manifold. Next, the software application running on the laptop is used to turn on the heaters and to monitor the manifold branch temperatures. When the system has reached thermal equilibrium, the software application s graphical user interface (GUI) will indicate that the branch temperatures are stable. The operator can then physically open the flow control valve to initiate the test flow of gaseous nitrogen (GN2) through the manifold. Next, the software user interface will be monitored for stable temperature indications when the system is again at

  20. Control of Unstable Flows

    Institute of Scientific and Technical Information of China (English)

    刘曾荣; 茅坚民

    2003-01-01

    Without introducing a discrete model, unstable continuous flows in a neighbourhood of an unstable stationary point can be stabilized. The linear part of the vector field of disturbing the flow can be managed to become the state variable multiplied by a negative constant. The nonlinear part of the vector field keeps to be unchanged,therefore flows far away from the stationary point are almost unaffected by the disturbance. The control method is easy to be used, even for practical problems for which a priori analytical knowledge of system dynamics is unavailable.

  1. Validated dynamic flow model

    DEFF Research Database (Denmark)

    Knudsen, Torben

    2011-01-01

    The purpose with this deliverable 2.5 is to use fresh experimental data for validation and selection of a flow model to be used for control design in WP3-4. Initially the idea was to investigate the models developed in WP2. However, in the project it was agreed to include and focus on a additive...... model turns out not to be useful for prediction of the flow. Moreover, standard Box Jenkins model structures and multiple output auto regressive models proves to be superior as they can give useful predictions of the flow....

  2. Cash flow statement

    Directory of Open Access Journals (Sweden)

    Pavlović Miloš

    2013-01-01

    Full Text Available A cash flow is "bloodstream" of business and without constant cash flow a company would not be able to function. The cash flow statement is statutory financial report that provides information to the interested parties on cash inflows and outflows from operating, investing and financing activities during the accounting period. This paper will discuss the origin and significance of the cash slow statement; in addition, we will define the main categories of this statement and present the methodology of its composition in accordance with IAS 7.

  3. Geophysical fluid flow experiment

    Science.gov (United States)

    Broome, B. G.; Fichtl, G.; Fowlis, W.

    1979-01-01

    The essential fluid flow processes associated with the solar and Jovian atmospheres will be examined in a laboratory experiment scheduled for performance on Spacelab Missions One and Three. The experimental instrumentation required to generate and to record convective fluid flow is described. Details of the optical system configuration, the lens design, and the optical coatings are described. Measurement of thermal gradient fields by schlieren techniques and measurement of fluid flow velocity fields by photochromic dye tracers is achieved with a common optical system which utilizes photographic film for data recording. Generation of the photochromic dye tracers is described, and data annotation of experimental parameters on the film record is discussed.

  4. Micro flows in foams

    Science.gov (United States)

    Koehler, Stephan; Hilgenfeldt, Sascha; Stone, Howard; Weeks, Eric

    2002-11-01

    Foam drainage, the flow of liquid through foams, has been extensively studied macroscopically, on the scale of many bubbles. We use a confocal microscope to determine the flow-field in a single channel, and find good agreement with a model based upon surface rheology (R. A. Leonard and R. Lemlich, AIChE J. 11, p. 25-29 (1965)). The microscopic measurements show different types of flows depending on the type of surfactant used to stabilize the foam, which has also been observed on the macroscopic level. Surprisingly we find very little mixing in the nodes, the regions where four different channels intersect.

  5. Small-Gap Flows

    Science.gov (United States)

    1984-04-01

    34’OF CALIFORNIA# BERKELEY, CA 5.1720 ft (45 642-141 SMALL- GAP FLOWS BY E. 0. TUCK REPORT No. NAUE 84-1 CONTRACT N00014-84-K-OU26 APRIL i984...Mechanics, 41 (1970) 769-792. 11 3. Shallow-Water Waves at Discontinuities Shallow-water waves represent perhaps the prototype small- gap flow , the...solving (4.4) we need "initial" conditions at the starting station z = 0, and "exit" conditions at the station z = L where the gap flow merges with the

  6. Bypass Flow Study

    Energy Technology Data Exchange (ETDEWEB)

    Richard Schultz

    2011-09-01

    The purpose of the fluid dynamics experiments in the MIR (Matched Index of-Refraction) flow system at Idaho National Laboratory (INL) is to develop benchmark databases for the assessment of Computational Fluid Dynamics (CFD) solutions of the momentum equations, scalar mixing, and turbulence models for the flow ratios between coolant channels and bypass gaps in the interstitial regions of typical prismatic standard fuel element (SFE) or upper reflector block geometries of typical Modular High-temperature Gas-cooled Reactors (MHTGR) in the limiting case of negligible buoyancy and constant fluid properties. The experiments use Particle Image Velocimetry (PIV) to measure the velocity fields that will populate the bypass flow study database.

  7. Initiation of slug flow

    Energy Technology Data Exchange (ETDEWEB)

    Hanratty, T.J.; Woods, B.D. [Univ. of Illinois, Urbana, IL (United States)

    1995-12-31

    The initiation of slug flow in a horizontal pipe can be predicted either by considering the stability of a slug or by considering the stability of a stratified flow. Measurements of the shedding rate of slugs are used to define necessary conditions for the existence of a slug. Recent results show that slugs develop from an unstable stratified flow through the evolution of small wavelength waves into large wavelength waves that have the possibility of growing to form a slug. The mechanism appears to be quite different for fluids with viscosities close to water than for fluids with large viscosities (20 centipoise).

  8. Pulsatile prosthetic valve flows.

    Science.gov (United States)

    Phillips, W M; Snyder, A; Alchas, P; Rosenberg, G; Pierce, W S

    1980-01-01

    The laser Doppler system has been established as a useful tool for eliciting the properties of simulated cardiovascular flows, and thus for comparative studies of flow properties of prosthetic valves. Significant differences among valve types and between models of one type have been documented. The complex variations of velocity profiles with time show that comparisons must be made for unsteady pulsatile rather than steady flow, despite the volume and complexity of the data required. Future studies will include methods of compacting the data presentation and improving the details of the experimental stimulation.

  9. Complex Flow Workshop Report

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2012-05-01

    This report documents findings from a workshop on the impacts of complex wind flows in and out of wind turbine environments, the research needs, and the challenges of meteorological and engineering modeling at regional, wind plant, and wind turbine scales.

  10. Hovering in Oscillatory Flows

    CERN Document Server

    Huang, Yangyang; Kanso, Eva

    2015-01-01

    We investigate the hovering dynamics of rigid bodies with up-down asymmetry placed in oscillating background flows. Recent experiments on inanimate pyramid-shaped objects in oscillating flows with zero mean component demonstrate that the resulting aerodynamic forces are sufficient to keep the object aloft. The mechanisms responsible for this lift production are fundamentally unsteady and depend on the shed vorticity. Here, we consider a model system of a two-dimensional flyer and compute the unsteady, two-way coupling between the flyer and the surrounding fluid in the context of the vortex sheet model. We examine in detail the flow properties (frequency and speed) required for hovering and their dependence on the flyer's characteristics (mass and geometry). We find that the aerodynamic effort required to hover is an intrinsic property of the flyer itself: a given flyer requires a constant amount of effort to hover, irrespective of the frequency and speed of the oscillating flow. This physical insight will pot...

  11. Visualising patient flow.

    Science.gov (United States)

    Jensen, Andrew; Boyle, Justin; Khanna, Sankalp

    2012-01-01

    We describe the development of a method to distil routinely collected clinical data into patient flow information to aid hospital bed management. Using data from state-wide emergency department and inpatient clinical information systems, a user-friendly interface was developed to visualise patient flow conditions for a particular hospital. The historical snapshots employ a variable time scale, allowing flow to be visualised across a day, week, month or year. Flow information includes occupancy, arrival and departure rates, length-of-stay and access block observations, which can be filtered by age, departure status, diagnosis, elective status, triage category, and admission unit. The tool may be helpful in supporting hospital bed managers in their daily decision making.

  12. Cash Flow Planning.

    Science.gov (United States)

    Littman, George W., III

    1979-01-01

    Proper cash flow planning allows a school business administrator to determine the availability of cash for operating expenses, the need for bank loans to cover these expenses, and the availability of idle cash for investment. (Author)

  13. Multicomponent flow modeling

    Institute of Scientific and Technical Information of China (English)

    GIOVANGIGLI; Vincent

    2012-01-01

    We present multicomponent flow models derived from the kinetic theory of gases and investigate the symmetric hyperbolic-parabolic structure of the resulting system of partial differential equations.We address the Cauchy problem for smooth solutions as well as the existence of deflagration waves,also termed anchored waves.We further discuss related models which have a similar hyperbolic-parabolic structure,notably the SaintVenant system with a temperature equation as well as the equations governing chemical equilibrium flows.We next investigate multicomponent ionized and magnetized flow models with anisotropic transport fluxes which have a different mathematical structure.We finally discuss numerical algorithms specifically devoted to complex chemistry flows,in particular the evaluation of multicomponent transport properties,as well as the impact of multicomponent transport.

  14. Martian Lava Flows

    Science.gov (United States)

    2005-01-01

    19 October 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows lava flows at the southeast base of the giant volcano, Olympus Mons. The flat plain in the south-southeast (bottom/lower right) portion of the image is younger than and cuts off the ends of many of the lava flows that came from the northwest (upper left). Many of the lava flows in this image exhibit channels with levees bounding their margins. As each lava flow was advancing, its outer margins cooled and hardened, forming a channel or tube through which the molten rock continued to advance. Location near: 17.2oN, 129.0oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Winter

  15. Cash flow statement

    National Research Council Canada - National Science Library

    Pavlović Miloš; Bogdanović Jovan

    2013-01-01

    .... The cash flow statement is statutory financial report that provides information to the interested parties on cash inflows and outflows from operating, investing and financing activities during the accounting period...

  16. Shocklets in compressible flows

    Institute of Scientific and Technical Information of China (English)

    袁湘江; 男俊武; 沈清; 李筠

    2013-01-01

    The mechanism of shocklets is studied theoretically and numerically for the stationary fluid, uniform compressible flow, and boundary layer flow. The conditions that trigger shock waves for sound wave, weak discontinuity, and Tollmien-Schlichting (T-S) wave in compressible flows are investigated. The relations between the three types of waves and shocklets are further analyzed and discussed. Different stages of the shocklet formation process are simulated. The results show that the three waves in compressible flows will transfer to shocklets only when the initial disturbance amplitudes are greater than the certain threshold values. In compressible boundary layers, the shocklets evolved from T-S wave exist only in a finite region near the surface instead of the whole wavefront.

  17. The disappearance of flow

    CERN Document Server

    Soff, S; Hartnack, C; Stöcker, H; Greiner, W; Soff, S; Bass, S A; Hartnack, C; Stöcker, H; Greiner, W

    1995-01-01

    We investigate the disappearance of collective flow in the reaction plane in heavy-ion collisions within a microscopic model (QMD). A systematic study of the impact parameter dependence is performed for the system Ca+Ca. The balance energy strongly increases with impact parameter. Momentum dependent interactions reduce the balance energies for intermediate impact parameters b\\approx4.5 fm. Dynamical negative flow is not visible in the laboratory frame but does exist in the contact frame for the heavy system Au+Au. For semi-peripheral collisions of Ca+Ca with b\\approx6.5 fm a new two-component flow is discussed. Azimuthal distributions exhibit strong collectiv flow signals, even at the balance energy.

  18. Web life: Ice Flows

    Science.gov (United States)

    2016-11-01

    Computer and video gamers of a certain vintage will have fond memories of Lemmings, a game in which players must shepherd pixelated, suicidal rodents around a series of obstacles to reach safety. At first glance, Ice Flows is strikingly similar.

  19. Flow Cytometry Section

    Data.gov (United States)

    Federal Laboratory Consortium — The primary goal of the Flow Cytometry Section is to provide the services of state-of-the-art multi-parameter cellular analysis and cell sorting for researchers and...

  20. Flow cytometry bioinformatics.

    Directory of Open Access Journals (Sweden)

    Kieran O'Neill

    Full Text Available Flow cytometry bioinformatics is the application of bioinformatics to flow cytometry data, which involves storing, retrieving, organizing, and analyzing flow cytometry data using extensive computational resources and tools. Flow cytometry bioinformatics requires extensive use of and contributes to the development of techniques from computational statistics and machine learning. Flow cytometry and related methods allow the quantification of multiple independent biomarkers on large numbers of single cells. The rapid growth in the multidimensionality and throughput of flow cytometry data, particularly in the 2000s, has led to the creation of a variety of computational analysis methods, data standards, and public databases for the sharing of results. Computational methods exist to assist in the preprocessing of flow cytometry data, identifying cell populations within it, matching those cell populations across samples, and performing diagnosis and discovery using the results of previous steps. For preprocessing, this includes compensating for spectral overlap, transforming data onto scales conducive to visualization and analysis, assessing data for quality, and normalizing data across samples and experiments. For population identification, tools are available to aid traditional manual identification of populations in two-dimensional scatter plots (gating, to use dimensionality reduction to aid gating, and to find populations automatically in higher dimensional space in a variety of ways. It is also possible to characterize data in more comprehensive ways, such as the density-guided binary space partitioning technique known as probability binning, or by combinatorial gating. Finally, diagnosis using flow cytometry data can be aided by supervised learning techniques, and discovery of new cell types of biological importance by high-throughput statistical methods, as part of pipelines incorporating all of the aforementioned methods. Open standards, data

  1. Yamabe flow on Berwald manifolds

    Science.gov (United States)

    Azami, Shahroud; Razavi, Asadollah

    2015-12-01

    Studying the geometric flow plays a powerful role in mathematics and physics. We introduce the Yamabe flow on Finsler manifolds and we will prove the existence and uniqueness for solution of Yamabe flow on Berwald manifolds.

  2. Retinal flow cytometer

    OpenAIRE

    Alt, C.; Veilleux, I.; H. Lee; Pitsillides, C. M.; Côté, D.; Lin, C.P.

    2007-01-01

    The in vivo flow cytometer is an instrument capable of continuous, real-time monitoring of fluorescently labeled cells in the circulation without the need to draw blood samples. However, the original system probes a single vessel in the mouse ear; the small sample volume limits the sensitivity of the technique. We describe an in vivo retinal flow cytometer that simultaneously probes five artery–vein pairs in the mouse eye by circularly scanning a small laser spot rapidly around the optic nerv...

  3. Stability of parallel flows

    CERN Document Server

    Betchov, R

    2012-01-01

    Stability of Parallel Flows provides information pertinent to hydrodynamical stability. This book explores the stability problems that occur in various fields, including electronics, mechanics, oceanography, administration, economics, as well as naval and aeronautical engineering. Organized into two parts encompassing 10 chapters, this book starts with an overview of the general equations of a two-dimensional incompressible flow. This text then explores the stability of a laminar boundary layer and presents the equation of the inviscid approximation. Other chapters present the general equation

  4. Fanno Flow in Microchannels

    Directory of Open Access Journals (Sweden)

    M.A. Al-Nimr

    2012-12-01

    Full Text Available In this study, the Fanno flow problem has been theoretically investigated using both, first order and second order velocity-slip boundary conditions models and then compared to the no-slip boundary conditions solution. The objective is to study the behavior of the flow predicted by the two slip models. Then, an attempt will be made to establish criteria for using the no-slip and the two velocity-slip models. The Fanno flow is an ideal gas adiabatic flow in constant area duct with friction. It is found that the velocity profile for the two velocity-slip models has the same shape as the no-slip model velocity profile but with an amount of slip at the wall which increases as the Knudsen number, Kn, increases. Also the effect of the slip has on the compressible flow characteristics have been examined. It shows that as the Kn increases, the skin friction coefficient Cf and the Darcy friction coefficient f decrease. Overall, it is concluded that for an adiabatic compressible flow in circular microchannel, for Kn≤0.01 there is no need to apply any velocity-slip model as the no-slip model gives sufficiently accurate predictions. As for the range 0.01≤Kn≤0.1, the first order velocity slip model should be applied and so for this range, there is no necessity to use the second order velocity-slip model.

  5. Sperm Motility in Flow

    Science.gov (United States)

    Guasto, Jeffrey; Juarez, Gabriel; Stocker, Roman

    2012-11-01

    A wide variety of plants and animals reproduce sexually by releasing motile sperm that seek out a conspecific egg, for example in the reproductive tract for mammals or in the water column for externally fertilizing organisms. Sperm are aided in their quest by chemical cues, but must also contend with hydrodynamic forces, resulting from laminar flows in reproductive tracts or turbulence in aquatic habitats. To understand how velocity gradients affect motility, we subjected swimming sperm to a range of highly-controlled straining flows using a cross-flow microfluidic device. The motion of the cell body and flagellum were captured through high-speed video microscopy. The effects of flow on swimming are twofold. For moderate velocity gradients, flow simply advects and reorients cells, quenching their ability to cross streamlines. For high velocity gradients, fluid stresses hinder the internal bending of the flagellum, directly inhibiting motility. The transition between the two regimes is governed by the Sperm number, which compares the external viscous stresses with the internal elastic stresses. Ultimately, unraveling the role of flow in sperm motility will lead to a better understanding of population dynamics among aquatic organisms and infertility problems in humans.

  6. Jamming in Hopper Flow

    Science.gov (United States)

    Sadighpour, Sepehr; Mort, Paul; Behringer, R. P.

    2007-11-01

    It known that the flow rate, m, of sand from a hopper is independent of the amount of material in the hopper due to stress screening. This is the basis for the Beverloo equation which relates m to an effective fluidized region near the outlet. We use the screening idea to characterize the probability of jamming for flow from a hopper. We focus on the probability Ps(t) = 1 - Pj(t) that flow has continued without a jam, a `survival' probability. Screening suggests that in time dt, the jamming probability is dPj= dt/T, where T is a constant characteristic time. Simple analysis gives Ps(t) = (-t/T) where t is the time since the start of flow. We can also write Ps(M) = [-M/(mT)], where M is the mass that has flowed out. We have carried out experiments in a quasi-2D hopper to test this idea. Our sand grains are photoelastic disks confined between two Plexiglas sheets. We obtain two types of data, first, data for s(t) and second, photoelastic images showing the force structures within the hopper during flow. We find that Ps is well described by an exponential. Ongoing work seeks to relate T to the properties of the material near the outlet.

  7. A Cryogenic Flow Sensor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced Technologies Group, Inc. proposes the development of a Cryogenic Flow Sensor (CFS) for determining mass flow of cryogens in spacecraft propellant...

  8. Oscillatory flow chemical reactors

    Directory of Open Access Journals (Sweden)

    Slavnić Danijela S.

    2014-01-01

    Full Text Available Global market competition, increase in energy and other production costs, demands for high quality products and reduction of waste are forcing pharmaceutical, fine chemicals and biochemical industries, to search for radical solutions. One of the most effective ways to improve the overall production (cost reduction and better control of reactions is a transition from batch to continuous processes. However, the reactions of interests for the mentioned industry sectors are often slow, thus continuous tubular reactors would be impractically long for flow regimes which provide sufficient heat and mass transfer and narrow residence time distribution. The oscillatory flow reactors (OFR are newer type of tube reactors which can offer solution by providing continuous operation with approximately plug flow pattern, low shear stress rates and enhanced mass and heat transfer. These benefits are the result of very good mixing in OFR achieved by vortex generation. OFR consists of cylindrical tube containing equally spaced orifice baffles. Fluid oscillations are superimposed on a net (laminar flow. Eddies are generated when oscillating fluid collides with baffles and passes through orifices. Generation and propagation of vortices create uniform mixing in each reactor cavity (between baffles, providing an overall flow pattern which is close to plug flow. Oscillations can be created by direct action of a piston or a diaphragm on fluid (or alternatively on baffles. This article provides an overview of oscillatory flow reactor technology, its operating principles and basic design and scale - up characteristics. Further, the article reviews the key research findings in heat and mass transfer, shear stress, residence time distribution in OFR, presenting their advantages over the conventional reactors. Finally, relevant process intensification examples from pharmaceutical, polymer and biofuels industries are presented.

  9. Through flow analysis within axial flow turbomachinery blade rows

    Science.gov (United States)

    Girigoswami, H.

    1986-09-01

    Using Katsanis' Through Flow Code, inviscid flow through an axial flow compressor rotor blade as well as flow through inlet guide vanes are analyzed and the computed parameters such as meridional velocity distribution, axial velocity distribution along radial lines, and velocity distribution over blade surfaces are presented.

  10. Flow: Statistics, visualization and informatics for flow cytometry

    Directory of Open Access Journals (Sweden)

    Kepler Thomas B

    2008-06-01

    Full Text Available Abstract Flow is an open source software application for clinical and experimental researchers to perform exploratory data analysis, clustering and annotation of flow cytometric data. Flow is an extensible system that offers the ease of use commonly found in commercial flow cytometry software packages and the statistical power of academic packages like the R BioConductor project.

  11. Unraveling ultrafiltration of polysaccharides with flow field flow fractionation

    NARCIS (Netherlands)

    Ven, van de Wilbert; Pünt, Ineke; Kemperman, Antoine; Wessling, Matthias

    2009-01-01

    We used flow field flow fractionation (flow-FFF) coupled with multi-angle-light scattering (MALS) to study the conformation of alginate molecules in ultrapure water and in a 10 mM salt solution. In particular, we investigated the behavior of alginates under filtration conditions. The flow-FFF result

  12. Rokhlin Dimension for Flows

    Science.gov (United States)

    Hirshberg, Ilan; Szabó, Gábor; Winter, Wilhelm; Wu, Jianchao

    2017-07-01

    We introduce a notion of Rokhlin dimension for one parameter automorphism groups of {C^*}-algebras. This generalizes Kishimoto's Rokhlin property for flows, and is analogous to the notion of Rokhlin dimension for actions of the integers and other discrete groups introduced by the authors and Zacharias in previous papers. We show that finite nuclear dimension and absorption of a strongly self-absorbing {C^*}-algebra are preserved under forming crossed products by flows with finite Rokhlin dimension, and that these crossed products are stable. Furthermore, we show that a flow on a commutative {C^*}-algebra arising from a free topological flow has finite Rokhlin dimension, whenever the spectrum is a locally compact metrizable space with finite covering dimension. For flows that are both free and minimal, this has strong consequences for the associated crossed product {C^{*}}-algebras: Those containing a non-zero projection are classified by the Elliott invariant (for compact manifolds this consists of topological {K}-theory together with the space of invariant probability measures and a natural pairing given by the Ruelle-Sullivan map).

  13. Upscaling of Forchheimer flows

    KAUST Repository

    Aulisa, Eugenio

    2014-08-01

    In this work we propose upscaling method for nonlinear Forchheimer flow in heterogeneous porous media. The generalized Forchheimer law is considered for incompressible and slightly-compressible single-phase flows. We use recently developed analytical results (Aulisa et al., 2009) [1] and formulate the resulting system in terms of a degenerate nonlinear flow equation for the pressure with the nonlinearity depending on the pressure gradient. The coarse scale parameters for the steady state problem are determined so that the volumetric average of velocity of the flow in the domain on fine scale and on coarse scale are close. A flow-based coarsening approach is used, where the equivalent permeability tensor is first evaluated following streamline methods for linear cases, and modified in order to take into account the nonlinear effects. Compared to previous works (Garibotti and Peszynska, 2009) [2], (Durlofsky and Karimi-Fard) [3], this approach can be combined with rigorous mathematical upscaling theory for monotone operators, (Efendiev et al., 2004) [4], using our recent theoretical results (Aulisa et al., 2009) [1]. The developed upscaling algorithm for nonlinear steady state problems is effectively used for variety of heterogeneities in the domain of computation. Direct numerical computations for average velocity and productivity index justify the usage of the coarse scale parameters obtained for the special steady state case in the fully transient problem. For nonlinear case analytical upscaling formulas in stratified domain are obtained. Numerical results were compared to these analytical formulas and proved to be highly accurate. © 2014.

  14. Shaped Recess Flow Control

    Science.gov (United States)

    Shyam, Vikram (Inventor); Poinsatte, Philip (Inventor); Thurman, Douglas (Inventor)

    2017-01-01

    One or more embodiments of techniques or systems for shaped recess flow control are provided herein. A shaped recess or cavity can be formed on a surface associated with fluid flow. The shaped recess can be configured to create or induce fluid effects, temperature effects, or shedding effects that interact with a free stream or other structures. The shaped recess can be formed at an angle to a free stream flow and may be substantially "V" shaped. The shaped recess can be coupled with a cooling channel, for example. The shaped recess can be upstream or downstream from a cooling channel and aligned in a variety of manners. Due to the fluid effects, shedding effects, and temperature effects created by a shaped recess, lift-off or separation of cooling jets of cooling channels can be mitigated, thereby enhancing film cooling effectiveness.

  15. Flow Based Algorithm

    Directory of Open Access Journals (Sweden)

    T. Karpagam

    2012-01-01

    Full Text Available Problem statement: Network topology design problems find application in several real life scenario. Approach: Most designs in the past either optimize for a single criterion like shortest or cost minimization or maximum flow. Results: This study discussed about solving a multi objective network topology design problem for a realistic traffic model specifically in the pipeline transportation. Here flow based algorithm focusing to transport liquid goods with maximum capacity with shortest distance, this algorithm developed with the sense of basic pert and critical path method. Conclusion/Recommendations: This flow based algorithm helps to give optimal result for transporting maximum capacity with minimum cost. It could be used in the juice factory, milk industry and its best alternate for the vehicle routing problem.

  16. Particles in flows

    CERN Document Server

    Galdi, Giovanni; Nečasová, Šárka

    2017-01-01

    This book aims to face particles in flows from many different, but essentially interconnected sides and points of view. Thus the selection of authors and topics represented in the chapters, ranges from deep mathematical analysis of the associated models, through the techniques of their numerical solution, towards real applications and physical implications. The scope and structure of the book as well as the selection of authors was motivated by the very successful summer course and workshop "Particles in Flows'' that was held in Prague in the August of 2014. This meeting revealed the need for a book dealing with this specific and challenging multidisciplinary subject, i.e. particles in industrial, environmental and biomedical flows and the combination of fluid mechanics, solid body mechanics with various aspects of specific applications.

  17. Robust Optical Flow Estimation

    Directory of Open Access Journals (Sweden)

    Javier Sánchez Pérez

    2013-10-01

    Full Text Available n this work, we describe an implementation of the variational method proposed by Brox etal. in 2004, which yields accurate optical flows with low running times. It has several benefitswith respect to the method of Horn and Schunck: it is more robust to the presence of outliers,produces piecewise-smooth flow fields and can cope with constant brightness changes. Thismethod relies on the brightness and gradient constancy assumptions, using the information ofthe image intensities and the image gradients to find correspondences. It also generalizes theuse of continuous L1 functionals, which help mitigate the effect of outliers and create a TotalVariation (TV regularization. Additionally, it introduces a simple temporal regularizationscheme that enforces a continuous temporal coherence of the flow fields.

  18. Interactive Flow in Exercise Pedagogy

    Science.gov (United States)

    Lloyd, Rebecca; Smith, Stephen

    2006-01-01

    A phenomenology of the bodily experience of interactive flow adds to Csikszentmihalyi's flow theory. Whereas Csikszentmihalyi attended to teachers' and students' experiences of flow separately, this inquiry explores flow through three water-inspired layers of physical interaction between fitness professionals and their clients. Teaching fitness is…

  19. Multiscale Image Based Flow Visualization

    NARCIS (Netherlands)

    Telea, Alexandru; Strzodka, Robert

    2006-01-01

    We present MIBFV, a method to produce real-time, multiscale animations of flow datasets. MIBFV extends the attractive features of the Image-Based Flow Visualization (IBFV) method, i.e. dense flow domain coverage with flow-aligned noise, real-time animation, implementation simplicity, and few (or no)

  20. Mechanics of fluid flow

    CERN Document Server

    Basniev, Kaplan S; Chilingar, George V 0

    2012-01-01

    The mechanics of fluid flow is a fundamental engineering discipline explaining both natural phenomena and human-induced processes, and a thorough understanding of it is central to the operations of the oil and gas industry.  This book, written by some of the world's best-known and respected petroleum engineers, covers the concepts, theories, and applications of the mechanics of fluid flow for the veteran engineer working in the field and the student, alike.  It is a must-have for any engineer working in the oil and gas industry.

  1. Transport hub flow modelling

    OpenAIRE

    Despagne, Wilfried; Frenod, Emmanuel

    2014-01-01

    Purpose: The purpose of this paper is to investigate the road freight haulage activity. Using the physical and data flow information from a freight forwarder, we intend to model the flow of inbound and outbound goods in a freight transport hub. Approach: This paper presents the operation of a road haulage group. To deliver goods within two days to any location in France, a haulage contractor needs to be part of a network. This network handles the processing of both physical goods and data. We...

  2. Gas speed flow transducer

    Directory of Open Access Journals (Sweden)

    Godovaniouk V. N.

    2011-08-01

    Full Text Available The design of a gas speed flow transducer using the coupling of gas speed and heat streams within the transducer itself is proposed. To maintain the heat balance between two thermoresistors under gas stream at different temperatures, it provides energy consumption monitoring. The detailed combined planar technology for the transducer production is presented. The worked-out measurement procedure allows to make measurements in the temperature range. Information enough to organize production of cheap, reliable and precise gas speed flow transducers is given.

  3. Turbulent mixing and afterburn in post-detonation flow with dense particle clouds

    Science.gov (United States)

    Gottiparthi, Kalyana C.; Menon, Suresh

    2017-01-01

    Augmentation of the impact of an explosive is routinely achieved by packing metal particles in the explosive charge. When detonated, the particles in the charge are ejected and dispersed. The ejecta influences the post-detonation combustion processes that bolster the blast wave and determines the total impact of the explosive. While the classical Eulerian-Lagrangian (EL) methods can accurately handle the post-detonation mixing zone in the dilute regime, the Eulerian-Eulerian (EE) method is preferred for the initial dense clustering. Here, we summarize the results obtained using both EL and EE methods as well as demonstrate a new hybrid EE-EL approach. The EL method, which is also developed to handle both dense and dilute flows using the discrete equation method, is used initially to study the dispersion of a relatively dense particle shell by blast waves. The results show distinct clustering of particles that later leads to the formation of jet-like structures as seen in experiments. Then, the hybrid EE-EL method is used to study the dispersion of dense clouds from explosives packed with aluminum (reactive) or steel (inert) particles. A transitioning criterion is used to smoothly transfer the initially dense Eulerian mass to Lagrangian particles when dilute. Results are presented to demonstrate that the approach is computationally efficient and accurate for certain ranges of particle sizes and loading. It is shown that mixing between the ambient and post-detonation products can be enhanced when particles are present in the flow. Furthermore, the afterburn of aluminum particles increases in the average gas-phase temperature by 100 K - 200 K when compared to a case with non-reacting particles. More studies are still needed to establish a robust strategy for wider applications.

  4. Flow on noisy terrains

    DEFF Research Database (Denmark)

    Tsirogiannis, Konstantinos; Haverkort, Herman

    2011-01-01

    Computing watersheds on triangulated terrain models in a robust manner is a difficult task as it is sensitive to noise that appears in the elevation values of the input. This is amplified by the existence of many very small watersheds (corresponding to spurious minima) that obscure the overall hy...... to use a robust flow model together with exact arithmetic....

  5. Bottleneck flows in networks

    CERN Document Server

    Punnen, Abraham P

    2007-01-01

    The bottleneck network flow problem (BNFP) is a generalization of several well-studied bottleneck problems such as the bottleneck transportation problem (BTP), bottleneck assignment problem (BAP), bottleneck path problem (BPP), and so on. In this paper we provide a review of important results on this topic and its various special cases. We observe that the BNFP can be solved as a sequence of $O(\\log n)$ maximum flow problems. However, special augmenting path based algorithms for the maximum flow problem can be modified to obtain algorithms for the BNFP with the property that these variations and the corresponding maximum flow algorithms have identical worst case time complexity. On unit capacity network we show that BNFP can be solved in $O(\\min \\{{m(n\\log n)}^{{2/3}}, m^{{3/2}}\\sqrt{\\log n}\\})$. This improves the best available algorithm by a factor of $\\sqrt{\\log n}$. On unit capacity simple graphs, we show that BNFP can be solved in $O(m \\sqrt {n \\log n})$ time. As a consequence we have an $O(m \\sqrt {n \\l...

  6. Infinitesimal Conical Supersonic Flow

    Science.gov (United States)

    Busemann, Adolf

    1947-01-01

    The calculation of infinitesimal conical supersonic flow has been applied first to the simplest examples that have also been calculated in another way. Except for the discovery of a miscalculation in an older report, there was found the expected conformity. The new method of calculation is limited more definitely to the conical case.

  7. Flow Injection Analysis

    DEFF Research Database (Denmark)

    Hansen, Elo Harald

    1998-01-01

    Learning objectives:* To provide an introduction to automated assays* To describe the basic principles of FIA * To demonstrate the capabilities of FIA in relation to batch assays and conventional continuous flow systems* To show that FIA allows one to augment existing analytical techniques* To sh...

  8. Probabilistic Load Flow

    DEFF Research Database (Denmark)

    Chen, Peiyuan; Chen, Zhe; Bak-Jensen, Birgitte

    2008-01-01

    This paper reviews the development of the probabilistic load flow (PLF) techniques. Applications of the PLF techniques in different areas of power system steady-state analysis are also discussed. The purpose of the review is to identify different available PLF techniques and their corresponding...

  9. Power flow controller

    NARCIS (Netherlands)

    Ferreira, J.A.; Yuan, Z.; De Haan, S.W.H.

    2008-01-01

    The invention relates to a power flow controller, comprising at least one first converter coupled with a power transmission line, and at least one second converter coupled with a power source, wherein said power source operates at a predeter-mined first frequency and connects to the power transmissi

  10. Epiglottal Flow Physics

    Science.gov (United States)

    Pollard, Andrew; Shinneeb, Abdul-Monsif

    2011-11-01

    PIV measurements have been made at three locations in the pharynx/larynx region in the ETA model, one along the central sagittal plane and two cross-sectional planes. The measurements were made at a flow rate of 9.04 l/min which corresponds approximately to 10 l/min in the prototype. The corresponding Reynolds number Re based on the inlet condition is 716. Two thousand images were acquired at each location at a framing rate of 2 Hz. The mean velocity fields were then calculated. In addition,the data was analysed by the proper orthogonal decomposition (POD) technique to expose vortical structures. Only few modes were used for the POD reconstruction which recovered about 60% of the turbulent kinetic energy. The results showed that the flow is characterised by regions of re-circulation, jet-like, and sink-like flows. In addition, the POD-reconstructed fields revealed some interesting features that occur in the human pharynx/larynx region near the epiglottis such as tearing and pairing processes, as well as the interaction between the flows induced by the structures. Funded by NSERC.

  11. Delta Flow Modulator

    NARCIS (Netherlands)

    Stamhuis, Eize; Lengkeek, W

    2015-01-01

    A support structure (2) is installed in or near a water (50). The support structure is holding a deltalike-wing (3) under an angle of incidence relative to an incoming flow (54), caused by at least a prevailing current in the water, thus generating a vortex (77). The action of the vortex is

  12. Quaternions and ideal flows

    Energy Technology Data Exchange (ETDEWEB)

    Eshraghi, H [Iran University of Science and Technology (IUST), School of Physics, Institute for Studies in Theoretical Physics and Mathematics, Tehran (Iran, Islamic Republic of); Gibbon, J D [Department of Mathematics, Imperial College London, London SW7 2AZ (United Kingdom)

    2008-08-29

    After a review of some of the recent works by Holm and Gibbon on quaternions and their application to Lagrangian flows, particularly the incompressible Euler equations and the equations of ideal MHD, this paper investigates the compressible and relativistic Euler equations using these methods.

  13. Let It Flow

    Institute of Scientific and Technical Information of China (English)

    Alphonce Shiundu

    2011-01-01

    @@ AFRICA'S Gold Coast, otherwise known as the Republic of Ghana, marked the first 100 days since its oil taps began running, on March 25, 2011.The oil in question flows from the country s offshore Iubilee oilfield, recognized by the stakeholders to be the largest oil discovery in West Africa in the last 10 to 15 years.

  14. Experimental Investigation of Stator Flow in Diagonal Flow Fan

    Institute of Scientific and Technical Information of China (English)

    Jie Wang; Yoichi Kinoue; Norimasa Shiomi; Toshiaki Setoguchi; Kenji Kaneko; Yingzi Jin

    2008-01-01

    perimental investigations were conducted for the internal flow of the stator of the diagonal flow fan. Comer separation near the hub surface and the suction surface of the stator blade are focused on. At the design flow rate, the values of the axial velocity and the total pressure at stator outlet decrease near the suction surface at around the hub surface by the influence of the comer wall. At low flow rate of 80-90 % of the design flow rate, the comer separation between the suction surface and the hub surface can be found, which become widely spread at 80 % of the design flow rate.

  15. Experimental investigation of stator flow in diagonal flow fan

    Science.gov (United States)

    Wang, Jie; Kinoue, Yoichi; Shiomi, Norimasa; Setoguchi, Toshiaki; Kaneko, Kenji; Jin, Yingzi

    2008-12-01

    Experimental investigations were conducted for the internal flow of the stator of the diagonal flow fan. Corner separation near the hub surface and the suction surface of the stator blade are focused on. At the design flow rate, the values of the axial velocity and the total pressure at stator outlet decrease near the suction surface at around the hub surface by the influence of the corner wall. At low flow rate of 80-90 % of the design flow rate, the corner separation between the suction surface and the hub surface can be found, which become widely spread at 80 % of the design flow rate.

  16. Numerical Analysis for the Air Flow of Cross Flow Fan

    Science.gov (United States)

    Sakai, Hirokazu; Tokushge, Satoshi; Ishikawa, Masatoshi; Ishihara, Takuya

    There are many factors for designing the cross flow fan. Therefore, the performance of cross flow fan is not clear yet. We can analyze the transient flow of a cross flow fan using sliding mesh approach. One of the tasks using Computational Fluid Dynamics (CFD) is a way of modeling for analysis heat exchangers with cross flow fan. These tasks are very important for design. The paper has a modeling of heat exchangers and meshing the fan blades. The next tasks, we focus the ability of cross flow fan when we change the geometry of fan blades.

  17. How to use your peak flow meter

    Science.gov (United States)

    Peak flow meter - how to use; Asthma - peak flow meter; Reactive airway disease - peak flow meter; Bronchial asthma - peak flow meter ... If your airways are narrowed and blocked due to asthma, your peak flow values drop. You can ...

  18. Flow networks analysis and optimization of repairable flow networks, networks with disturbed flows, static flow networks and reliability networks

    CERN Document Server

    Todinov, Michael T

    2013-01-01

    Repairable flow networks are a new area of research, which analyzes the repair and flow disruption caused by failures of components in static flow networks. This book addresses a gap in current network research by developing the theory, algorithms and applications related to repairable flow networks and networks with disturbed flows. The theoretical results presented in the book lay the foundations of a new generation of ultra-fast algorithms for optimizing the flow in networks after failures or congestion, and the high computational speed creates the powerful possibility of optimal control

  19. Self-Organized Network Flows

    CERN Document Server

    Helbing, D; Lämmer, S; Helbing, Dirk; Siegmeier, Jan; L\\"{a}mmer, Stefan

    2007-01-01

    A model for traffic flow in street networks or material flows in supply networks is presented, that takes into account the conservation of cars or materials and other significant features of traffic flows such as jam formation, spillovers, and load-dependent transportation times. Furthermore, conflicts or coordination problems of intersecting or merging flows are considered as well. Making assumptions regarding the permeability of the intersection as a function of the conflicting flows and the queue lengths, we find self-organized oscillations in the flows similar to the operation of traffic lights.

  20. FLOW-Methode - Methodenbeschreibung zur Anwendung von FLOW

    CERN Document Server

    Stapel, Kai

    2012-01-01

    Information of many kinds is flowing in software projects and organizations. Requirements have to flow from the customer to the developers. Testers need to know the requirements as well. Boundary conditions and design decisions have to be at the right place at the right time. Information flow analysis with FLOW facilitates modeling of mode and route of the flow of information and experience independent of the development methodology. Experience often acts as a control factor, because experienced developers can process and route information more efficiently. Therefore, experience needs to be at the right place at the right time, too. However, most valuable experiences never get documented. Since information and experience is flowing in agile as well as in traditional environments, the FLOW method does not distinguish between agile and traditional, but only between how the flows are shaped. ---- In Softwareprojekten flie{\\ss}en vielerlei Informationen. Anforderungen m\\"ussen vom Kunden zu den Entwicklern gelang...

  1. Load flow analysis using decoupled fuzzy load flow under critical ...

    African Journals Online (AJOL)

    user

    of power system, reliable fuzzy load flow is developed to overcome the limitations of the ... of power mismatches are taken as two inputs for fuzzy logic controller. ..... Programming Based Load Flow Algorithm For Systems Containing Unified ...

  2. Discrete Morse flow for Ricci flow and Porous Media equation

    CERN Document Server

    Ma, Li

    2012-01-01

    In this paper, we study the discrete Morse flow for the Ricci flow on football, which is the 2-sphere with removed north and south poles and with the metric $g_0$ of constant scalar curvature, and and for Porous media equation on a bounded regular domain in the plane. We show that with a suitable assumption about $g(0)$ we have a weak approximated discrete Morse flow for the approximated Ricci flow and Porous media equation on any time intervals.

  3. Slow viscous flow

    CERN Document Server

    Langlois, William E

    2014-01-01

    Leonardo wrote, 'Mechanics is the paradise of the mathematical sciences, because by means of it one comes to the fruits of mathematics' ; replace 'Mechanics' by 'Fluid mechanics' and here we are." -    from the Preface to the Second Edition Although the exponential growth of computer power has advanced the importance of simulations and visualization tools for elaborating new models, designs and technologies, the discipline of fluid mechanics is still large, and turbulence in flows remains a challenging problem in classical physics. Like its predecessor, the revised and expanded Second Edition of this book addresses the basic principles of fluid mechanics and solves fluid flow problems where viscous effects are the dominant physical phenomena. Much progress has occurred in the nearly half a century that has passed since the edition of 1964. As predicted, aspects of hydrodynamics once considered offbeat have risen to importance. For example, the authors have worked on problems where variations in viscosity a...

  4. Wet solids flow enhancemant

    Energy Technology Data Exchange (ETDEWEB)

    Caram, H.S.; Foster, N.; Wildman, D.J. [USDOE Pittsburgh Energy Technology Center, PA (United States)

    1996-12-31

    WE used glass beads of different sizes as.a model system to study the flow enhancing properties of Octadecyltrichlorosilane (OTS). 0TS provides Si(CH{sub 2}){sub 17}CH{sub 3} groups that bind with the surface hydrox groups to make it hydrophobic. Experimental data showed, indeed, that surface hydrophobicity promotes the flow of wet granular materials. Mixtures of different percentage of silanized/unsilanized particles were prepared for tensile strength measurements. The tensile strength decreased as more silanized particles were added to the samples. The relationship between dimensionless tensile strength and void fraction followed the correlation found by Pierrat (1994). Contact angles were larger for the silanized particles, as compared with unsilanized ones.

  5. Structural power flow measurement

    Energy Technology Data Exchange (ETDEWEB)

    Falter, K.J.; Keltie, R.F.

    1988-12-01

    Previous investigations of structural power flow through beam-like structures resulted in some unexplained anomalies in the calculated data. In order to develop structural power flow measurement as a viable technique for machine tool design, the causes of these anomalies needed to be found. Once found, techniques for eliminating the errors could be developed. Error sources were found in the experimental apparatus itself as well as in the instrumentation. Although flexural waves are the carriers of power in the experimental apparatus, at some frequencies longitudinal waves were excited which were picked up by the accelerometers and altered power measurements. Errors were found in the phase and gain response of the sensors and amplifiers used for measurement. A transfer function correction technique was employed to compensate for these instrumentation errors.

  6. Bondi flow revisited

    CERN Document Server

    Datta, Satadal

    2016-01-01

    Newtonian spherically symmetric transonic accretion has been studied by including the mass of the accreting matter, while considering the growth of the accretor itself to be negligibly small. A novel iterative method has been introduced to accomplish that task. It has been demonstrated that the inclusion of the mass of the fluid changes the critical properties of the flow as well as the topological phase portraits of the stationary integral solution.

  7. Leukocytes in capillary flow.

    Science.gov (United States)

    Schmid-Schönbein, G W; Lee, J

    1995-01-01

    During disease, the flow of blood cells through the capillary network is one of the most perilous events in the microcirculation. Capillary distensibility, cytoplasmic activity of endothelial cells, red cells and leukocytes play an important role in capillary perfusion. Occlusion of capillaries is one of the early signs of vascular failure and is encountered in many different conditions and organs. Adhesion of leukocytes to the endothelium via expression of membrane adhesion molecules leads to microvascular entrapment with capillary occlusion.

  8. Flow Encountering Abrupt Topography

    Science.gov (United States)

    2013-09-30

    deeper depths near 350 m at Helen Reef, northward flow of relatively salty water is seen. This salty water may serve as a tracer and may indicate...need further scrutiny since this system is intended for deep waters . Doppler sonars included the Hydrographic Doppler Sonar System (HDSS) with 50 and...each were done for bathymetry mapping. During the cross-shore surveys, additional deep water bathymetry was obtained with a majority of the area around

  9. Flow og fordybelse

    DEFF Research Database (Denmark)

    Andersen, Frans Ørsted

    2010-01-01

    Artiklen handler om flow og fordybelse i et nyt tværfagligt / naturfagligt undervisningskoncept, "Overvågningens dilemma", til brug i folkeskolens 7.-9.kl. og på gymnasiale uddannelser. Konceptet sætter fokus på den overvågning der foregår og er mulig i nutidens IT og hi-tec samfund og der arbejd...

  10. TEP process flow diagram

    Energy Technology Data Exchange (ETDEWEB)

    Wilms, R Scott [Los Alamos National Laboratory; Carlson, Bryan [Los Alamos National Laboratory; Coons, James [Los Alamos National Laboratory; Kubic, William [Los Alamos National Laboratory

    2008-01-01

    This presentation describes the development of the proposed Process Flow Diagram (PFD) for the Tokamak Exhaust Processing System (TEP) of ITER. A brief review of design efforts leading up to the PFD is followed by a description of the hydrogen-like, air-like, and waterlike processes. Two new design values are described; the mostcommon and most-demanding design values. The proposed PFD is shown to meet specifications under the most-common and mostdemanding design values.

  11. Studies in transonic flow

    OpenAIRE

    Mohan, S. R.

    1983-01-01

    This thesis is divided into, two distinct parts. Part I describes the design and development of an intermittent cryogenic wind-tunnel, in which the cold conditions are generated by the expansion of high pressure gas. The device uses a light piston moving in a tube and conditions during the running time are maintained constant by 'tuning' the piston motion, i. e. by Imatchingt the volumetric flow rate entering and leaving the tube. The results of the pilot tunnel (running tim...

  12. Projectile Base Flow Analysis

    Science.gov (United States)

    2007-11-02

    S) AND ADDRESS(ES) DCW Industries, Inc. 5354 Palm Drive La Canada, CA 91011 8. PERFORMING ORGANIZATION...REPORT NUMBER DCW -38-R-05 9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) U. S. Army Research Office...Turbulence Modeling for CFD, Second Edition, DCW Industries, Inc., La Cañada, CA. Wilcox, D. C. (2001), “Projectile Base Flow Analysis,” DCW

  13. Flow Control Technology

    Science.gov (United States)

    2010-07-01

    downstream of the propeller system. Figure 16 and Figure 17 show the ADV used by Huxley and Hartman [5] as well as a flow diagram for their...Max 17° Figure 23: Power Coefficient of Asymmetric Test Trials vs. Sinusoid pitch schedule. The aim of the work by Huxley and Hartman [5] was...Fagley, Ph.D. candidate, worked with Cadets Thiago Huxley and Christopher Hartman on a feedback controlled cycloidal wave energy converter in

  14. Transonic swirling nozzle flow

    Science.gov (United States)

    Keith, Theo G., Jr.; Pawlas, Gary E.

    1991-06-01

    A numerical model of viscous transonic swirling flow in axisymmetric nozzles is developed. MacCormack's implicit Gauss-Seidel method is applied to the thin-layer Navier-Stokes equations in transformed coordinates. Numerical results are compared with experimental data to validate the method. The effect of swirl and viscosity on nozzle performance are demonstrated by examining wall pressures, Mach contours, and integral parameters.

  15. Flow pattern in reverse-flow centrifugal separators

    NARCIS (Netherlands)

    Peng, W; Hoffmann, AC; Boot, PJAJ; Udding, A; Dries, HWA; Ekker, A; Kater, J

    2002-01-01

    Experimental flow patterns, determined by Laser Doppler Anemometry (LDA) for two types of reverse-flow centrifugal separators, are presented. The flow patterns in (a) a conventional cylinder-on-cone cyclone with tangential inlet and (b) a swirl tube with vane-generated swirl and a cylindrical body a

  16. Arterial secondary blood flow patterns visualized with vector flow ultrasound

    DEFF Research Database (Denmark)

    Pedersen, Mads Møller; Pihl, Michael Johannes; Hansen, Jens Munk

    2011-01-01

    This study presents the first quantification and visualisation of secondary flow patterns with vector flow ultrasound. The first commercial implementation of the vector flow method Transverse Oscillation was used to obtain in-vivo, 2D vector fields in real-time. The hypothesis of this study...

  17. Flow Injection Analysis

    DEFF Research Database (Denmark)

    Hansen, Elo Harald

    2004-01-01

    This chapter provides an introduction to automated chemical analysis, which essentially can be divided into two groups: batch assays, where the solution is stationary while the container is moved through a number of stations where various unit operations performed; and continuous-flow procedures,......, but it permits thr execution of novel and unique analytical procedures which are difficult or even impossible by conventional means. The performance and applicability of FIA, SI and LOV are illustrated by a series of practical examples.......This chapter provides an introduction to automated chemical analysis, which essentially can be divided into two groups: batch assays, where the solution is stationary while the container is moved through a number of stations where various unit operations performed; and continuous-flow procedures......, where the system is stationary while the solution moves through a set of conduits in which all required manipulations are performed. Emphasis is placed on flow injection analysis (FIA) and its further developments, that is, sequential injection analysis (SIA) and the Lab-on-Valve (LOV) approach. Since...

  18. Conversational flow promotes solidarity.

    Science.gov (United States)

    Koudenburg, Namkje; Postmes, Tom; Gordijn, Ernestine H

    2013-01-01

    Social interaction is fundamental to the development of various aspects of "we-ness". Previous research has focused on the role the content of interaction plays in establishing feelings of unity, belongingness and shared reality (a cluster of variables referred to as solidarity here). The present paper is less concerned with content, but focuses on the form of social interaction. We propose that the degree to which conversations flow smoothly or not is, of itself, a cue to solidarity. We test this hypothesis in samples of unacquainted and acquainted dyads who communicate via headsets. Conversational flow is disrupted by introducing a delay in the auditory feedback (vs. no delay). Results of three studies show that smoothly coordinated conversations (compared with disrupted conversations and a control condition) increase feelings of belonging and perceptions of group entitativity, independently of conversation content. These effects are driven by the subjective experience of conversational flow. Our data suggest that this process occurs largely beyond individuals' control. We conclude that the form of social interaction is a powerful cue for inferring group solidarity. Implications for the impact of modern communication technology on developing a shared social identity are discussed.

  19. Conversational flow promotes solidarity.

    Directory of Open Access Journals (Sweden)

    Namkje Koudenburg

    Full Text Available Social interaction is fundamental to the development of various aspects of "we-ness". Previous research has focused on the role the content of interaction plays in establishing feelings of unity, belongingness and shared reality (a cluster of variables referred to as solidarity here. The present paper is less concerned with content, but focuses on the form of social interaction. We propose that the degree to which conversations flow smoothly or not is, of itself, a cue to solidarity. We test this hypothesis in samples of unacquainted and acquainted dyads who communicate via headsets. Conversational flow is disrupted by introducing a delay in the auditory feedback (vs. no delay. Results of three studies show that smoothly coordinated conversations (compared with disrupted conversations and a control condition increase feelings of belonging and perceptions of group entitativity, independently of conversation content. These effects are driven by the subjective experience of conversational flow. Our data suggest that this process occurs largely beyond individuals' control. We conclude that the form of social interaction is a powerful cue for inferring group solidarity. Implications for the impact of modern communication technology on developing a shared social identity are discussed.

  20. Magnetohydrodynamics of blood flow.

    Science.gov (United States)

    Keltner, J R; Roos, M S; Brakeman, P R; Budinger, T F

    1990-10-01

    The changes in hydrostatic pressure and electrical potentials across vessels in the human vasculature in the presence of a large static magnetic field are estimated to determine the feasibility of in vivo NMR spectroscopy at fields as high as 10 T.A 10-T magnetic field changes the vascular pressure in a model of the human vasculature by less than 0.2%. An exact solution to the magnetohydrodynamic equations describing a conducting fluid flowing transverse to a static magnetic field in a nonconducting, straight, circular tube is used. This solution is compared to an approximate solution that assumes that no magnetic fields are induced in the fluid and that has led previous investigators to predict significant biological effects from static magnetic fields. Experimental results show that the exact solution accurately predicts the magnetohydrodynamic slowing of 15% NaCl flowing transverse to 2.3- and 4.7-T magnetic fields for fluxes below 0.5 liter/min while the approximate solution predicts a much more retarded flow.

  1. Numerical Investigation on the Separated Flow of Axial Flow Stator in Diagonal Flow Fan

    Science.gov (United States)

    Kinoue, Yoichi; Shiomi, Norimasa; Setoguchi, Toshiaki; Kaneko, Kenji; Jin, Yingzi

    2010-06-01

    Experimental and numerical investigations were conducted for the internal flow of the stator of the diagonal flow fan. Corner separation near the hub surface and the suction surface of the stator blade are focused on. At low flow rate of 80% of the design flow rate, the corner separation between the suction surface and the hub surface can be found in both experimental and numerical results. Separation vortices are found in the computed oil flow on both suction and hub surfaces at 80% of the design flow rate in the three-dimensional numerical simulation.

  2. Optical diagnostics of intermittent flows

    DEFF Research Database (Denmark)

    Okulov, V.L.; Naumov, I.V.; Sørensen, Jens Nørkær

    2007-01-01

    The efficiency of combined use of different optical techniques for flow diagnostics is demonstrated with the practically important case of intense swirling flows. It is shown that, when applied separately, commonly used optical measuring techniques, such as laser Doppler anemometry and particle...... image velocimetry, frequently give erroneous results, especially for the transition flow and developed nonstationary flow. However, their combined use in diagnostics of unsteady (intermittent) flows significantly improves both the temporal and spatial resolution of measurements. Such a complex approach...... is for the first time applied for diagnostics of the flow pattern in a closed cylinder with a rotating end face with the aim of studying the changeover from the steady axisymmetric to unsteady asymmetric flow over a wide range of flow parameters. It is found that such a transition is notable for azimuthal...

  3. A Cryogenic Flow Sensor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Based on the success of the phase I effort, Advanced Technologies Group, Inc. proposes the development of a Cryogenic Flow Sensor (CFS) for determining mass flow of...

  4. Flow list and test results

    Data.gov (United States)

    U.S. Environmental Protection Agency — These data accompany the manuscript 'Critical Review of Elementary Flows in LCA Data'. Each file presents a subgroup of the elementary flows (data used for analysis)...

  5. Asymmetric reactions in continuous flow

    Directory of Open Access Journals (Sweden)

    Xiao Yin Mak

    2009-04-01

    Full Text Available An overview of asymmetric synthesis in continuous flow and microreactors is presented in this review. Applications of homogeneous and heterogeneous asymmetric catalysis as well as biocatalysis in flow are discussed.

  6. Virtual Flow Simulator

    Energy Technology Data Exchange (ETDEWEB)

    2015-10-05

    Virtual Flow Simulator (VFS) is a state-of-the-art computational fluid mechanics (CFD) package that is capable of simulating multi-physics/multi-phase flows with the most advanced turbulence models (RANS, LES) over complex terrains. The flow solver is based on the Curvilinear Immersed Boundary (CURVIB) method to handle geometrically complex and moving domains. Different modules of the VFS package can provide different simulation capabilities for specific applications ranging from the fluid-structure interaction (FSI) of solid and deformable bodies, the two-phase free surface flow solver based on the level set method for ocean waves, sediment transport models in rivers and the large-scale models of wind farms based on actuator lines and surfaces. All numerical features of VFS package have been validated with known analytical and experimental data as reported in the related journal articles. VFS package is suitable for a broad range of engineering applications within different industries. VFS has been used in different projects with applications in wind and hydrokinetic energy, offshore and near-shore ocean studies, cardiovascular and biological flows, and natural streams and river morphodynamics. Over the last decade, the development of VFS has been supported and assisted with the help of various United States companies and federal agencies that are listed in the sponsor lists. In this version, VFS-Wind contains all the necessary modeling tools for wind energy applications, including land-based and offshore wind farms. VFS is highly scalable to run on either desktop computers or high performance clusters (up to 16,000 CPUs). This released version comes with a detailed user’s manual and a set of case studies designed to facilitate the learning of the various aspects of the code in a comprehensive manner. The included documentation and support material has been elaborated in a collaboration effort with Sandia National Labs under the contract DE-EE0005482. The VFS

  7. Property fund flows and returns

    OpenAIRE

    Stephen L. Lee

    2000-01-01

    This study is concerned with the impacts on property returns from property fund flows, and with the possibility of a reverse transmission from property fund flows to property returns. In other words this study investigates whether property returns “cause” fund flow changes, or whether fund flow changes “cause” property returns, or causality works in both directions.\\ud \\ud \\ud \\ud

  8. SPECIFIC SOLUTIONS GROUNDWATER FLOW EQUATION

    OpenAIRE

    Syahruddin, Muhammad Hamzah

    2014-01-01

    Geophysic publication Groundwater flow under surface, its usually slow moving, so that in laminer flow condition can find analisys using the Darcy???s law. The combination between Darcy law and continuity equation can find differential Laplace equation as general equation groundwater flow in sub surface. Based on Differential Laplace Equation is the equation that can be used to describe hydraulic head and velocity flow distribution in porous media as groundwater. In the modeling Laplace e...

  9. Wilsonian flows and background fields

    CERN Document Server

    Litim, Daniel F; Litim, Daniel F.; Pawlowski, Jan M.

    2002-01-01

    We study exact renormalisation group flows for background field dependent regularisations. It is shown that proper-time flows are approximations to exact background field flows for a specific class of regulators. We clarify the role of the implicit scale dependence introduced by the background field. Its impact on the flow is evaluated numerically for scalar theories at criticality for different approximations and regularisations. Implications for gauge theories are discussed.

  10. Property fund flows and returns

    OpenAIRE

    Lee, Stephen L.

    2000-01-01

    This study is concerned with the impacts on property returns from property fund flows, and with the possibility of a reverse transmission from property fund flows to property returns. In other words this study investigates whether property returns “cause” fund flow changes, or whether fund flow changes “cause” property returns, or causality works in both directions.\\ud \\ud \\ud \\ud

  11. Bulk flow scaling for turbulent channel and pipe flows

    CERN Document Server

    Chen, Xi; She, Zhen-Su

    2016-01-01

    We report a theory deriving bulk flow scaling for canonical wall-bounded flows. The theory accounts for the symmetries of boundary geometry (flat plate channel versus circular pipe) by a variational calculation for a large-scale energy length, which characterizes its bulk flow scaling by a simple exponent, i.e. $m=4$ for channel and 5 for pipe. The predicted mean velocity shows excellent agreement with several dozen sets of quality empirical data for a wide range of the Reynolds number (Re), with a universal bulk flow constant $\\kappa\\approx0.45$. Predictions for dissipation and turbulent transport in the bulk flow are also given, awaiting data verification.

  12. Electroosmotic shear flow in microchannels

    NARCIS (Netherlands)

    Mampallil, Dileep; Ende, van den Dirk

    2013-01-01

    We generate and study electroosmotic shear flow in microchannels. By chemically or electrically modifying the surface potential of the channel walls a shear flow component with controllable velocity gradient can be added to the electroosmotic flow caused by double layer effects at the channel walls.

  13. Large amplitude oscillatory elongation flow

    DEFF Research Database (Denmark)

    Rasmussen, Henrik K.; Laillé, Philippe; Yu, Kaijia

    2008-01-01

    A filament stretching rheometer (FSR) was used for measuring the elongation flow with a large amplitude oscillative elongation imposed upon the flow. The large amplitude oscillation imposed upon the elongational flow as a function of the time t was defined as epsilon(t) =(epsilon) over dot(0)t + ...

  14. Localized turbulence in pipe flow

    NARCIS (Netherlands)

    Kuik, D.J.

    2011-01-01

    In this thesis the transition to turbulence in pipe flow is investigated. At low Reynolds numbers, the flow returns to the laminar state spontaneously. At high Reynolds number a small perturbation causes the flow to suddenly become turbulent. In the intermediate regime localized turbulence is observ

  15. Decorrelation-based blood flow velocity estimation: effect of spread of flow velocity, linear flow velocity gradients, and parabolic flow.

    NARCIS (Netherlands)

    Lupotti, F.A.; Steen, A.F.W. van der; Mastik, F.; Korte, C.L. de

    2002-01-01

    In recent years, a new method to measure transverse blood flow, based on the decorrelation of the radio frequency (RF) signals has been developed. In this paper, we investigated the influence of nonuniform flow on the velocity estimation. The decorrelation characteristics of transverse blood flow us

  16. Risk assessment future cash flows

    OpenAIRE

    Chachina H. G.

    2012-01-01

    This article is about risk assessment in planning future cash flows. Discount rate in DCF-model must include four factors: risk cash flow, inflation, value of investments, turnover assets. This has an influence net present value cash flow and make his incomparable.

  17. Flow around a line obstacle

    NARCIS (Netherlands)

    Jacobs, A.F.G.

    1983-01-01

    Shear layer flows which are strongly disturbed, often occur in nature as well as in engineering practice. Up to now little is known about this class of flows. This is Partly explained by the complexity of these flows and partly by a lack of experimental data. The objective of this study is: first, t

  18. EMBEDDING FLOWS AND SMOOTH CONJUGACY

    Institute of Scientific and Technical Information of China (English)

    ZHANGMEIRONG; LIWEIGU

    1997-01-01

    The authors use the functional equation for embedding vector fields to study smooth embedding flows of one-dimensional diffeomorphisms. The existence and uniqueness for smooth embedding flows and vector fields are proved. As an application of embedding flows, some classification results about local and giobal diffeomorphisms under smooth conjugacy are given.

  19. Risk assessment future cash flows

    OpenAIRE

    Chachina H. G.

    2012-01-01

    This article is about risk assessment in planning future cash flows. Discount rate in DCF-model must include four factors: risk cash flow, inflation, value of investments, turnover assets. This has an influence net present value cash flow and make his incomparable.

  20. Online traffic flow model applying dynamic flow-density relation

    CERN Document Server

    Kim, Y

    2002-01-01

    This dissertation describes a new approach of the online traffic flow modelling based on the hydrodynamic traffic flow model and an online process to adapt the flow-density relation dynamically. The new modelling approach was tested based on the real traffic situations in various homogeneous motorway sections and a motorway section with ramps and gave encouraging simulation results. This work is composed of two parts: first the analysis of traffic flow characteristics and second the development of a new online traffic flow model applying these characteristics. For homogeneous motorway sections traffic flow is classified into six different traffic states with different characteristics. Delimitation criteria were developed to separate these states. The hysteresis phenomena were analysed during the transitions between these traffic states. The traffic states and the transitions are represented on a states diagram with the flow axis and the density axis. For motorway sections with ramps the complicated traffic fl...

  1. Arroyo el Mimbral, Mexico, K/T unit: Origin as debris flow/turbidite, not a tsunami deposit

    Science.gov (United States)

    Bohor, Bruce F.; Betterton, William J.

    1993-01-01

    Coarse, spherule-bearing, elastic units have been discovered at 10 marine sites that span the K/T boundary in northeastern Mexico. We examined one of the best exposed sites in Arroyo el Mimbral, northwest of Tampico. The Mimbral outcrop displays a layered elastic unit up to 3 m thick enclosed by marly limestones of the Mendez (Latest Maastrichian) and Velasco (Earliest Danian) Formations. At its thickest point, this channelized elastic unit is comprised of 3 subunits: (1) a basal, poorly-sorted, ungraded calcareous spherule bed 1 m thick containing relict impact glass and shocked mineral grains, (2) a massive set of laminated calcite-cemented sandstones up to 2 m thick with plant debris at its base, (3) capped by a thin (up to 20 cm) set of rippled sandstone layers separated by silty mudstone drapes containing a small (921 pg/g) iridium anomaly. This tripartite elastic unit is conformably overlain by marls of the Velasco Formation. We also visited the La Lajilla site east of Ciudad Victoria; its stratigraphy is similar to Mimbral's, but its elastic beds are thinner and less extensive laterally. The Mimbral elastic unit has been interpreted previously as being deposited by a megawave or tsunami produced by an asteroid impact on nearby Yucatan (Chicxulub crater). However, a presumed 400-m paleodepth of water at the Mimbral site, channeling of the spherule subunit into the underlying Mendez Formation marls, and the overtopping of the basal, spherule-bearing subunit by the laminated sandstone subunit, all suggest a combined debris flow/turbidite origin for this elastic unit similar to that proposed for Upper Pleistocene sand/silt beds occurring elsewhere in the Gulf of Mexico. In this latter model, the sediment source region for the elastic unit is the lower continental shelf and slope escarpment. For the K/T unit at Mimbral, we propose that thick ejecta blanket deposits composed mostly of spherules were rapidly loaded onto the lower shelf and slope from an impact

  2. Let It Flow

    Institute of Scientific and Technical Information of China (English)

    Alphonce; Shiundu

    2011-01-01

    Ghana’s Jubilee oilfield output projected to more than double by year-end AFRICA’S Gold Coast,otherwise known as the Republic of Ghana,marked the first 100 days since its oil taps began running,on March 25,2011.The oil in question flows from the country’s offshore Jubilee oilfield, recognized by the stakeholders to be the largest oil discovery in West Africa in the last 10 to 15 years. This discovery has injected an air of optimism amongst Ghana-

  3. Providing Compassion through Flow

    Directory of Open Access Journals (Sweden)

    Lydia Royeen

    2015-07-01

    Full Text Available Meg Kral, MS, OTR/L, CLT, is the cover artist for the Summer 2015 issue of The Open Journal of Occupational Therapy. Her untitled piece of art is an oil painting and is a re-creation of a photograph taken while on vacation. Meg is currently supervisor of outpatient services at Rush University Medical Center. She is lymphedema certified and has a specific interest in breast cancer lymphedema. Art and occupational therapy serve similar purposes for Meg: both provide a sense of flow. She values the outcomes, whether it is a piece of art or improved functional status

  4. Continuous information flow fluctuations

    Science.gov (United States)

    Rosinberg, Martin Luc; Horowitz, Jordan M.

    2016-10-01

    Information plays a pivotal role in the thermodynamics of nonequilibrium processes with feedback. However, much remains to be learned about the nature of information fluctuations in small-scale devices and their relation with fluctuations in other thermodynamics quantities, like heat and work. Here we derive a series of fluctuation theorems for information flow and partial entropy production in a Brownian particle model of feedback cooling and extend them to arbitrary driven diffusion processes. We then analyze the long-time behavior of the feedback-cooling model in detail. Our results provide insights into the structure and origin of large deviations of information and thermodynamic quantities in autonomous Maxwell's demons.

  5. Disorders of lymph flow.

    Science.gov (United States)

    Witte, C L; Witte, M H

    1995-04-01

    Disturbances in blood capillary exchange of fluid, macromolecules, and cells across intact and abnormal microvessels and deranged lymphatic transport are integral, interacting components in disorders of tissue swelling. Lymphedema or low-output failure of the lymph circulation is often indolent for many years before lymphatic insufficiency (failure) and tissue swelling emerge and persist. Superimposed occult or overt infection (lymphangitis) are probably major contributors to progressive limb deformity (elephantiasis). Long-standing lymphedema is characterized by trapping in the skin and subcutaneous tissue of fluid, extravasated plasma proteins, and other macromolecules: impaired immune cell trafficking; abnormal processing of autologous and foreign antigens; heightened susceptibility to superimposed infection; local immunodysregulation; defective lymphatic (lymphangion) propulsion from an imbalance of mediators regulating vasomotion; soft-tissue overgrowth; scarring and hypertrophy; and exuberant angiogenesis occasionally culminating in vascular tumors (Fig. 8). In contrast to the blood circulation, where flow depends primarily on the propulsive force of the myocardium, lymph propulsion depends predominately on intrinsic truncal contraction, a phylogenetic vestige of amphibian lymph hearts. Whereas venous "plasma" flows rapidly (2-3 l/min) against low vascular resistance, lymph flows slowly (1-2 ml/min) against high vascular resistance. On occasion, impaired transport of intestinal lymph may be associated with reflux and accumulation and leakage of intestinal chyle in a swollen leg. Although the term "lymphedema" is usually reserved for extremity swelling, the pathogenesis of a wide variety of visceral disorders also may be traceable to defective tissue fluid and macromolecular circulation and impaired cell trafficking of lymphocytes and macrophages. Thus, lymph stasis, with impaired tissue fluid flow, underlies or complicates an indolent subclinical course with

  6. Cash flow management.

    Science.gov (United States)

    Kamenetzky, S A

    1993-06-01

    In the face of decreasing reimbursement and increasing expenses, careful cash flow management has assumed an increasingly important role in developing and maintaining a successful ophthalmology practice. Funds must be collected as promptly and efficiently as possible, and retained and invested until needed by the practice to pay expenses. Office collection techniques and suggestions for dealing with third-party payers are presented. Managed care contracting and the inherent risks involved are discussed. Advice on accounts payable management is provided, and suggestions for investment of idle funds are outlined. This information should allow the formulation of a practical plan to maximize profitability in each ophthalmology practice.

  7. Resting cerebral blood flow

    Science.gov (United States)

    Ances, B M.; Sisti, D; Vaida, F; Liang, C L.; Leontiev, O; Perthen, J E.; Buxton, R B.; Benson, D; Smith, D M.; Little, S J.; Richman, D D.; Moore, D J.; Ellis, R J.

    2009-01-01

    Objective: HIV enters the brain soon after infection causing neuronal damage and microglial/astrocyte dysfunction leading to neuropsychological impairment. We examined the impact of HIV on resting cerebral blood flow (rCBF) within the lenticular nuclei (LN) and visual cortex (VC). Methods: This cross-sectional study used arterial spin labeling MRI (ASL-MRI) to measure rCBF within 33 HIV+ and 26 HIV− subjects. Nonparametric Wilcoxon rank sum test assessed rCBF differences due to HIV serostatus. Classification and regression tree (CART) analysis determined optimal rCBF cutoffs for differentiating HIV serostatus. The effects of neuropsychological impairment and infection duration on rCBF were evaluated. Results: rCBF within the LN and VC were significantly reduced for HIV+ compared to HIV− subjects. A 2-tiered CART approach using either LN rCBF ≤50.09 mL/100 mL/min or LN rCBF >50.09 mL/100 mL/min but VC rCBF ≤37.05 mL/100 mL/min yielded an 88% (29/33) sensitivity and an 88% (23/26) specificity for differentiating by HIV serostatus. HIV+ subjects, including neuropsychologically unimpaired, had reduced rCBF within the LN (p = 0.02) and VC (p = 0.001) compared to HIV− controls. A temporal progression of brain involvement occurred with LN rCBF significantly reduced for both acute/early (<1 year of seroconversion) and chronic HIV-infected subjects, whereas rCBF in the VC was diminished for only chronic HIV-infected subjects. Conclusion: Resting cerebral blood flow (rCBF) using arterial spin labeling MRI has the potential to be a noninvasive neuroimaging biomarker for assessing HIV in the brain. rCBF reductions that occur soon after seroconversion possibly reflect neuronal or vascular injury among HIV+ individuals not yet expressing neuropsychological impairment. GLOSSARY AEH = acute/early HIV infection; ANOVA = analysis of variance; ASL-MRI = arterial spin labeling MRI; CART = classification and regression tree; CBF = cerebral blood flow; CH = chronic HIV

  8. Flow in air conditioned rooms

    DEFF Research Database (Denmark)

    Nielsen, Peter V.

    1974-01-01

    Flow in air conditioned r ooms is examined by means of model experiments . The different gearnetries giving unsteady, steady three- dimensional and steady twodimensional flow are determined . Velacity profiles and temperature profiles are measured in some of the geometries. A numerical solution...... of the flow equations is demonstrated and the flow in air conditioned rooms in case of steady two dimensional flow is predi cted. Compari son with measured results is shown i n the case of small Archimedes numbers, and predictions are shown at high Archimedes numbers. A numerical prediction of f low and heat...

  9. Minimal flows and their extensions

    CERN Document Server

    Auslander, J

    1988-01-01

    This monograph presents developments in the abstract theory of topological dynamics, concentrating on the internal structure of minimal flows (actions of groups on compact Hausdorff spaces for which every orbit is dense) and their homomorphisms (continuous equivariant maps). Various classes of minimal flows (equicontinuous, distal, point distal) are intensively studied, and a general structure theorem is obtained. Another theme is the ``universal'' approach - entire classes of minimal flows are studied, rather than flows in isolation. This leads to the consideration of disjointness of flows, w

  10. Flow tracing based on current

    Institute of Scientific and Technical Information of China (English)

    蔡兴国; 曹海龙

    2001-01-01

    Analyses the flow tracing based on power flow, points out that the detachment of reactive power and active power is unrealiable and concludes that the current is the real basic of flow tracing,and proposes the new flow tracing model based on current, which devides the current into active current and reactive current, analyses the theory about the matrix to deal with the precision and realization of the flow tracing, and then proposes a new pricing model by fixed rate and marginal rate, which keeps not only economy information such as congestion cost in marginal cost based pricing, but also benefits to make both ends meet.

  11. Exotic RG Flows from Holography

    CERN Document Server

    Kiritsis, Elias; Pimenta, Leandro Silva

    2016-01-01

    Holographic RG flows are studied in an Einstein-dilaton theory with a general potential. The superpotential formalism is utilized in order to characterize and classify all solutions that are associated to asymptotically AdS space-times. Such solutions correspond to holographic RG flows and are characterized by their holographic $\\beta$-functions. Novel solutions are found that have exotic properties from a RG point-of view. Some have $\\beta$-functions that are defined patch-wise and lead to flows where the $\\beta$-function changes sign without the flow stopping. Others describe flows that end in non-neighboring extrema in field space. Finally others describe regular flows between two minima of the potential and correspond holographically to flows driven by the VEV of an irrelevant operator in the UV CFT.

  12. Exotic RG flows from holography

    Energy Technology Data Exchange (ETDEWEB)

    Kiritsis, Elias [APC, Universite Paris 7, CNRS/IN2P3, CEA/IRFU, Obs. de Paris, Sorbonne Paris Cite (France); Crete Center for Theoretical Physics, Institute for Theoretical and Computational Physics, Department of Physics, University of Crete, Heraklion (Greece); Crete Center for Quantum Complexity and Nanotechnology, Department of Physics, University of Crete, Heraklion (Greece); Nitti, Francesco; Silva Pimenta, Leandro [APC, Universite Paris 7, CNRS/IN2P3, CEA/IRFU, Obs. de Paris, Sorbonne Paris Cite (France)

    2017-02-15

    Holographic RG flows are studied in an Einstein-dilaton theory with a general potential. The superpotential formalism is utilized in order to characterize and classify all solutions that are associated with asymptotically AdS space-times. Such solutions correspond to holographic RG flows and are characterized by their holographic β-functions. Novel solutions are found that have exotic properties from a RG point-of view. Some have β-functions that are defined patch-wise and lead to flows where the β-function changes sign without the flow stopping. Others describe flows that end in non-neighboring extrema in field space. Finally others describe regular flows between two minima of the potential and correspond holographically to flows driven by the VEV of an irrelevant operator in the UV CFT. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Monolithic Continuous-Flow Bioreactors

    Science.gov (United States)

    Stephanopoulos, Gregory; Kornfield, Julia A.; Voecks, Gerald A.

    1993-01-01

    Monolithic ceramic matrices containing many small flow passages useful as continuous-flow bioreactors. Ceramic matrix containing passages made by extruding and firing suitable ceramic. Pores in matrix provide attachment medium for film of cells and allow free movement of solution. Material one not toxic to micro-organisms grown in reactor. In reactor, liquid nutrients flow over, and liquid reaction products flow from, cell culture immobilized in one set of channels while oxygen flows to, and gaseous reaction products flow from, culture in adjacent set of passages. Cells live on inner surfaces containing flowing nutrient and in pores of walls of passages. Ready access to nutrients and oxygen in channels. They generate continuous high yield characteristic of immobilized cells, without large expenditure of energy otherwise incurred if necessary to pump nutrient solution through dense biomass as in bioreactors of other types.

  14. Experimental investigation of cavity flows

    Energy Technology Data Exchange (ETDEWEB)

    Loeland, Tore

    1998-12-31

    This thesis uses LDV (Laser Doppler Velocimetry), PIV (Particle Image Velocimetry) and Laser Sheet flow Visualisation to study flow inside three different cavity configurations. For sloping cavities, the vortex structure inside the cavities is found to depend upon the flow direction past the cavity. The shape of the downstream corner is a key factor in destroying the boundary layer flow entering the cavity. The experimental results agree well with numerical simulations of the same geometrical configurations. The results of the investigations are used to find the influence of the cavity flow on the accuracy of the ultrasonic flowmeter. A method to compensate for the cavity velocities is suggested. It is found that the relative deviation caused by the cavity velocities depend linearly on the pipe flow. It appears that the flow inside the cavities should not be neglected as done in the draft for the ISO technical report on ultrasonic flowmeters. 58 refs., 147 figs., 2 tabs.

  15. AC Optimal Power Flow

    Energy Technology Data Exchange (ETDEWEB)

    2016-10-04

    In this work, we have implemented and developed the simulation software to implement the mathematical model of an AC Optimal Power Flow (OPF) problem. The objective function is to minimize the total cost of generation subject to constraints of node power balance (both real and reactive) and line power flow limits (MW, MVAr, and MVA). We have currently implemented the polar coordinate version of the problem. In the present work, we have used the optimization solver, Knitro (proprietary and not included in this software) to solve the problem and we have kept option for both the native numerical derivative evaluation (working satisfactorily now) as well as for analytical formulas corresponding to the derivatives being provided to Knitro (currently, in the debugging stage). Since the AC OPF is a highly non-convex optimization problem, we have also kept the option for a multistart solution. All of these can be decided by the user during run-time in an interactive manner. The software has been developed in C++ programming language, running with GCC compiler on a Linux machine. We have tested for satisfactory results against Matpower for the IEEE 14 bus system.

  16. Blood flow and microgravity

    Science.gov (United States)

    Bureau, Lionel; Coupier, Gwennou; Dubois, Frank; Duperray, Alain; Farutin, Alexander; Minetti, Christophe; Misbah, Chaouqi; Podgorski, Thomas; Tsvirkun, Daria; Vysokikh, Mikhail

    2017-01-01

    The absence of gravity during space flight can alter cardio-vascular functions partially due to reduced physical activity. This affects the overall hemodynamics, and in particular the level of shear stresses to which blood vessels are submitted. Long-term exposure to space environment is thus susceptible to induce vascular remodeling through a mechanotransduction cascade that couples vessel shape and function with the mechanical cues exerted by the circulating cells on the vessel walls. Central to such processes, the glycocalyx - i.e. the micron-thick layer of biomacromolecules that lines the lumen of blood vessels and is directly exposed to blood flow - is a major actor in the regulation of biochemical and mechanical interactions. We discuss in this article several experiments performed under microgravity, such as the determination of lift force and collective motion in blood flow, and some preliminary results obtained in artificial microfluidic circuits functionalized with endothelium that offer interesting perspectives for the study of the interactions between blood and endothelium in healthy condition as well as by mimicking the degradation of glycocalyx caused by long space missions. A direct comparison between experiments and simulations is discussed. xml:lang="fr"

  17. Air Traffic Flow Management

    CERN Document Server

    Ganu, Hrishikesh V

    2008-01-01

    Air Traffic Flow Management is the regulation of air traffic in order to avoid exceeding airport or flight sector capacity in handling traffic, and to ensure that available capacity is used efficiently. We have tried to explore the logic behind the claims by Bertsimas et.al about integral solutions to the LP relaxation of the Traffic Flow Management Problem(TFMP). Polyhedral theory only indicates that the stronger TFMP formulation of Bertsimas et.al might lead to integral solutions in some cases. Our computations indicate that the encouraging results reported by Bertsimas et.al are not merely fortuitous or due to their specific data set. Indeed, we found that the TFMP had integral solutions even in case of artificial data sets generated to include severe conflicts in the flight schedules. In our limited tests with 4-5 scenarios, we obtained non-integral solutions only once. This is of significant practical importance because, the LP relaxation can be solved even on small machines with low memory and processor...

  18. Active flows on trees

    Science.gov (United States)

    Forrow, Aden; Woodhouse, Francis G.; Dunkel, Jörn

    2016-11-01

    Coherent, large scale dynamics in many nonequilibrium physical, biological, or information transport networks are driven by small-scale local energy input. We introduce and explore a generic model for compressible active flows on tree networks. In contrast to thermally-driven systems, active friction selects discrete states with only a small number of oscillation modes activated at distinct fixed amplitudes. This state selection can interact with graph topology to produce different localized dynamical time scales in separate regions of large networks. Using perturbation theory, we systematically predict the stationary states of noisy networks. Our analytical predictions agree well with a Bayesian state estimation based on a hidden Markov model applied to simulated time series data on binary trees. While the number of stable states per tree scales exponentially with the number of edges, the mean number of activated modes in each state averages 1 / 4 the number of edges. More broadly, these results suggest that the macroscopic response of active networks, from actin-myosin networks in cells to flow networks in Physarum polycephalum, can be dominated by a few select modes.

  19. Windstreak on Lava Flow

    Science.gov (United States)

    2005-01-01

    [figure removed for brevity, see original site] Today's image of the flows west of Arsia Mons also contains a large windstreak. Note the the surface texture in the 'white' part of the windstreak is more subdued than the rest of the flow. This is because the wind has deposited fine materials in this area. The wind can both erode the surface and cover it with deposits. Image information: VIS instrument. Latitude -7.7, Longitude 227.5 East (132.5 West). 17 meter/pixel resolution. Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  20. Eddy Current Minimizing Flow Plug for Use in Flow Conditioning and Flow Metering

    Science.gov (United States)

    England, John Dwight (Inventor); Kelley, Anthony R. (Inventor)

    2015-01-01

    An eddy-current-minimizing flow plug has open flow channels formed between the plug's inlet and outlet. Each open flow channel includes (i) a first portion that originates at the inlet face and converges to a location within the plug that is downstream of the inlet, and (ii) a second portion that originates within the plug and diverges to the outlet. The diverging second portion is approximately twice the length of the converging first portion. The plug is devoid of planar surface regions at its inlet and outlet, and in fluid flow planes of the plug that are perpendicular to the given direction of a fluid flowing therethrough.

  1. Flow Simulation of Solid Rocket Motors. 2; Sub-Scale Air Flow Simulation of Port Flows

    Science.gov (United States)

    Yeh, Y. P.; Ramandran, N.; Smith, A. W.; Heaman, J. P.

    2000-01-01

    The injection-flow issuing from a porous medium in the cold-flow simulation of internal port flows in solid rocket motors is characterized by a spatial instability termed pseudoturbulence that produces a rather non-uniform (lumpy) injection-velocity profile. The objective of this study is to investigate the interaction between the injection- and the developing axial-flows. The findings show that this interaction generally weakens the lumpy injection profile and affects the subsequent development of the axial flow. The injection profile is found to depend on the material characteristics, and the ensuing pseudoturbulence is a function of the injection velocity, the axial position and the distance from the porous wall. The flow transition (from laminar to turbulent) of the axial-flow is accelerated in flows emerging from smaller pores primarily due to the higher pseudoturbulence produced by the smaller pores in comparison to that associated with larger pores. In flows with rather uniform injection-flow profiles (weak or no pseudoturbulence), the axial and transverse velocity components in the porous duct are found to satisfy the sine/cosine analytical solutions derived from inviscid assumptions. The transition results from the present study are compared with previous results from surveyed literature, and detailed flow development measurements are presented in terms of the blowing fraction, and characterizing Reynolds numbers.

  2. Positron Emission Tomography-Determined Hyperemic Flow, Myocardial Flow Reserve, and Flow Gradient—Quo Vadis?

    Science.gov (United States)

    Leucker, Thorsten M.; Valenta, Ines; Schindler, Thomas Hellmut

    2017-01-01

    Positron emission tomography/computed tomography (PET/CT) applied with positron-emitting flow tracers such as 13N-ammonia and 82Rubidium enables the quantification of both myocardial perfusion and myocardial blood flow (MBF) in milliliters per gram per minute for coronary artery disease (CAD) detection and characterization. The detection of a regional myocardial perfusion defect during vasomotor stress commonly identifies the culprit lesion or most severe epicardial narrowing, whereas adding regional hyperemic MBFs, myocardial flow reserve (MFR), and/or longitudinal flow decrease may also signify less severe but flow-limiting stenosis in multivessel CAD. The addition of regional hyperemic flow parameters, therefore, may afford a comprehensive identification and characterization of flow-limiting effects of multivessel CAD. The non-specific origin of decreases in hyperemic MBFs and MFR, however, prompts an evaluation and interpretation of regional flow in the appropriate context with the presence of obstructive CAD. Conversely, initial results of the assessment of a longitudinal hyperemic flow gradient suggest this novel flow parameter to be specifically related to increases in CAD caused epicardial resistance. The concurrent assessment of myocardial perfusion and several hyperemic flow parameters with PET/CT may indeed open novel avenues of precision medicine to guide coronary revascularization procedures that may potentially lead to a further improvement in cardiovascular outcomes in CAD patients. PMID:28770213

  3. Flow Analysis: A Novel Approach For Classification.

    Science.gov (United States)

    Vakh, Christina; Falkova, Marina; Timofeeva, Irina; Moskvin, Alexey; Moskvin, Leonid; Bulatov, Andrey

    2016-09-01

    We suggest a novel approach for classification of flow analysis methods according to the conditions under which the mass transfer processes and chemical reactions take place in the flow mode: dispersion-convection flow methods and forced-convection flow methods. The first group includes continuous flow analysis, flow injection analysis, all injection analysis, sequential injection analysis, sequential injection chromatography, cross injection analysis, multi-commutated flow analysis, multi-syringe flow injection analysis, multi-pumping flow systems, loop flow analysis, and simultaneous injection effective mixing flow analysis. The second group includes segmented flow analysis, zone fluidics, flow batch analysis, sequential injection analysis with a mixing chamber, stepwise injection analysis, and multi-commutated stepwise injection analysis. The offered classification allows systematizing a large number of flow analysis methods. Recent developments and applications of dispersion-convection flow methods and forced-convection flow methods are presented.

  4. Flow feature detection for grid adaptation and flow visualization

    Science.gov (United States)

    Kallinderis, Yannis; Lymperopoulou, Eleni M.; Antonellis, Panagiotis

    2017-07-01

    Adaptive grid refinement/coarsening is an important method for achieving increased accuracy of flow simulations with reduced computing resources. Further, flow visualization of complex 3-D fields is a major task of both computational fluid dynamics (CFD), as well as experimental data analysis. A primary issue of adaptive simulations and flow visualization is the reliable detection of the local regions containing features of interest. A relatively wide spectrum of detection functions (sensors) is employed for representative flow cases which include boundary layers, vortices, jets, wakes, shock waves, contact discontinuities, and expansions. The focus is on relatively simple sensors based on local flow field variation using 3-D general hybrid grids consisting of multiple types of elements. A quantitative approach for sensors evaluation and comparison is proposed and applied. It is accomplished via the employment of analytic flow fields. Automation and effectiveness of an adaptive grid or flow visualization process requires the reliable determination of an appropriate threshold for the sensor. Statistical evaluation of the distributions of the sensors results in a proposed empirical formula for the threshold. The qualified sensors along with the automatic threshold determination are tested with more complex flow cases exhibiting multiple flow features.

  5. Waves and compressible flow

    CERN Document Server

    Ockendon, Hilary

    2016-01-01

    Now in its second edition, this book continues to give readers a broad mathematical basis for modelling and understanding the wide range of wave phenomena encountered in modern applications.  New and expanded material includes topics such as elastoplastic waves and waves in plasmas, as well as new exercises.  Comprehensive collections of models are used to illustrate the underpinning mathematical methodologies, which include the basic ideas of the relevant partial differential equations, characteristics, ray theory, asymptotic analysis, dispersion, shock waves, and weak solutions. Although the main focus is on compressible fluid flow, the authors show how intimately gasdynamic waves are related to wave phenomena in many other areas of physical science.   Special emphasis is placed on the development of physical intuition to supplement and reinforce analytical thinking. Each chapter includes a complete set of carefully prepared exercises, making this a suitable textbook for students in applied mathematics, ...

  6. Active flows on trees

    CERN Document Server

    Forrow, Aden; Dunkel, Jörn

    2016-01-01

    Coherent, large scale dynamics in many nonequilibrium physical, biological, or information transport networks are driven by small-scale local energy input. We introduce and explore a generic model for compressible active flows on tree networks. In contrast to thermally-driven systems, active friction selects discrete states with only a small number of oscillation modes activated at distinct fixed amplitudes. This state selection interacts with graph topology to produce different localized dynamical time scales in separate regions of large networks. Using perturbation theory, we systematically predict the stationary states of noisy networks and find good agreement with a Bayesian state estimation based on a hidden Markov model applied to simulated time series data on binary trees. While the number of stable states per tree scales exponentially with the number of edges, the mean number of activated modes in each state averages $\\sim 1/4$ the number of edges. More broadly, these results suggest that the macrosco...

  7. Freely flowing conversations

    DEFF Research Database (Denmark)

    Aakjær, Marie Kirstejn; Andrade, David; Dexters, Peter

    2012-01-01

    on - and support “positive deviants” (Pascal, Sternin and Sternin) – courageous individuals and groups (inmates as well as staff) who transform conversations into new actions and behavioral traits that become beckons of an improved future. In the following we explore concrete examples of efforts at improving......Some would say this article is an impossibility - the authors being a project manager from the Department of Prisons an (ex) inmate and a Designer doing an industrial PhD in the prisons. We hope that others may see this article as an embodiment of how taking part in new conversations...... and in regards to rehabilitation efforts. In the context of prisons UDI is inspired by the complexity approach (Stacey 2005). We seek to facilitate freely flowing conversations between inmates, staff and managers – pushing the boundaries of existing norms, roles and beliefs. In the end however we rely...

  8. Saturation of Zonal Flows

    Science.gov (United States)

    Kim, Eun-Jin

    2002-11-01

    Zonal flows (ZF) are generated by drift wave (DW) turbulence and then regulate it near marginality by shear suppression. Since collisions damp ZF while ZF suppress DW, the amplitude of DW turbulence (i.e. turbulent transport) is, in turn, proportional to collisionality. A key question is then what happens away from marginality, namely what is the saturation mechanism of ZF in that regime? This raises the interesting physical question of how ZF interact with mne 0, poloidally non-axisymmetric modes [1], both linearly and non linearly. We investigate this issue by exploring the nonlinear excitation of GKH modes by modulational instability in the background of finite amplitude of DW turbulence, as well as the linear inflection-type instability of ZF. In a simple model with cold ions, we show that ZF can grow faster than the linear GKH for γ/ωGKH modes can be comparable to their linear generation. Here, γ and ω are the growth rate and frequency of DW, and p and k are the characteristic wavenumbers of ZF and DW. These findings imply that the linear analysis of GKH may not always be valid and also that there may be no clear distinction between secondary (ZF) and tertiary mode (GKH). The effect of finite ion temperature fluctuations is incorporated in a simple toroidal ion temperature gradient model, within which both zonal flow and temperature are generated by modulational instability. The phase between the two is calculated self-consistently and shown to be positive. Furthermore, the correction to nonlinear generation of GKH modes appears to be small. [1] We refer to these low mne 0 modes as Generalized Kelvin-Helmholtz (GKH) modes, since they will appear as mne 0 distortions of a shear layer.

  9. NUMERICAL SIMULATIONS OF CAVITATING FLOWS

    Institute of Scientific and Technical Information of China (English)

    Wu Lei

    2003-01-01

    A new model, which involves viscous and multi-phase effects, was given to study cavitating flows. A local compressible model was established by introducing a density-pressure function to account for the two-phase flow of water/vapor and the transition from one phase to the other. An algorithm for calculating variable-density N-S equations of cavitating flow problem was put forward. The present method yields reasonable results for both steady and unsteady cavitating flows in 2D and 3D cases. The numerical results of unsteady character of cavitating flows around hydrofoils coincide well with experimental data. It indicates the feasibility to apply this method to a variety of cavitating flows of practical problems.

  10. Intermittency in spiral Poiseuille flow

    Energy Technology Data Exchange (ETDEWEB)

    Heise, M; Abshagen, J; Menck, A; Pflster, G [Institute of Experimental and Applied Physics, University of Kiel, 24098 Kiel (Germany)

    2005-01-01

    The results of an experimental study on intermittent spiral vortices observed in a counter-rotating Taylor-Couette system with an additional axial through flow, i.e. Spiral-Poiseuille flow, are presented. Convectively unstable upstream propagating spiral vortices appear in the laminar basic flow from an oscillatory instability and in general become absolutely unstable at higher inner cylinder Reynolds number. It is found that at Reynolds numbers above the absolute stability border the spiral vortices become unstable and a complex flow state showing intermittent bursts appears. The intermittent flow state is characterised by an irregular alternation between clearly distinguishable 'laminar' phases corresponding to up-and downstream propagating spiral vortices as well as propagating Taylor vortices. For a sufficiently high rate of axial through flow it is found that intermittency can occur directly from the convectively unstable regime of the upstream propagating spiral vortices.

  11. Joule heating in electrokinetic flow.

    Science.gov (United States)

    Xuan, Xiangchun

    2008-01-01

    Electrokinetic flow is an efficient means to manipulate liquids and samples in lab-on-a-chip devices. It has a number of significant advantages over conventional pressure-driven flow. However, there exists inevitable Joule heating in electrokinetic flow, which is known to cause temperature variations in liquids and draw disturbances to electric, flow and concentration fields via temperature-dependent material properties. Therefore, both the throughput and the resolution of analytic studies performed in microfluidic devices are affected. This article reviews the recent progress on the topic of Joule heating and its effect in electrokinetic flow, particularly the theoretical and experimental accomplishments from the aspects of fluid mechanics and heat/mass transfer. The primary focus is placed on the temperature-induced flow variations and the accompanying phenomena at the whole channel or chip level.

  12. Endovascular blood flow measurement system

    Science.gov (United States)

    Khe, A. K.; Cherevko, A. A.; Chupakhin, A. P.; Krivoshapkin, A. L.; Orlov, K. Yu

    2016-06-01

    In this paper an endovascular measurement system used for intraoperative cerebral blood flow monitoring is described. The system is based on a Volcano ComboMap Pressure and Flow System extended with analogue-to-digital converter and PC laptop. A series of measurements performed in patients with cerebrovascular pathologies allows us to introduce “velocity-pressure” and “flow rate-energy flow rate” diagrams as important characteristics of the blood flow. The measurement system presented here can be used as an additional instrument in neurosurgery for assessment and monitoring of the operation procedure. Clinical data obtained with the system are used for construction of mathematical models and patient-specific simulations. The monitoring of the blood flow parameters during endovascular interventions was approved by the Ethics Committee at the Meshalkin Novosibirsk Research Institute of Circulation Pathology and included in certain surgical protocols for pre-, intra- and postoperative examinations.

  13. The AdaBoost Flow

    CERN Document Server

    Lykov, A; Vaninsky, K

    2011-01-01

    We introduce a dynamical system which we call the AdaBoost flow. The flow is defined by a system of ODEs with control. We show how by a suitable choice of control AdaBoost algorithm of Schapire and Freund and arc-gv algorithm of Breiman can be embedded in the AdaBoost flow. We also show how previously studied by Schapire and Singer confidence rated prediction can be obtained from our continuous time approach. We introduce a new continuous time algorithm which we call superBoost and describe its properties. The AdaBoost flow equations coincide with the equations of dynamics of the nonperiodic Toda system written in terms of spectral variables. This establishes a connection between two seemingly unrelated fields of boosting algorithms and classical integrable models. Finally we explain similarity of the AdaBoost flow with Perelman's ideas to control Ricci flow.

  14. Magnetic heat pump flow director

    Science.gov (United States)

    Howard, Frank S. (Inventor)

    1995-01-01

    A fluid flow director is disclosed. The director comprises a handle body and combed-teeth extending from one side of the body. The body can be formed of a clear plastic such as acrylic. The director can be used with heat exchangers such as a magnetic heat pump and can minimize the undesired mixing of fluid flows. The types of heat exchangers can encompass both heat pumps and refrigerators. The director can adjust the fluid flow of liquid or gas along desired flow directions. A method of applying the flow director within a magnetic heat pump application is also disclosed where the comb-teeth portions of the director are inserted into the fluid flow paths of the heat pump.

  15. Observation Predicates in Flow Logic

    DEFF Research Database (Denmark)

    Nielson, Flemming; Nielson, Hanne Riis; Sun, Hongyan

    2003-01-01

    Motivated by the connection between strong and soft type systems we explore flow analyses with hard constraints on the admissible solutions. We show how to use observation predicates and formula rearrangements to map flow analyses with hard constraints into more traditional flow analyses in such ......Motivated by the connection between strong and soft type systems we explore flow analyses with hard constraints on the admissible solutions. We show how to use observation predicates and formula rearrangements to map flow analyses with hard constraints into more traditional flow analyses...... in such a way that the hard constraints are satisfi ed exactly when the observation predicates report no violations. The development is carried out in a large fragment of a first order logic with negation and also takes care of the transformations necessary in order to adhere to the stratification restrictions...

  16. Flow, affect and visual creativity.

    Science.gov (United States)

    Cseh, Genevieve M; Phillips, Louise H; Pearson, David G

    2015-01-01

    Flow (being in the zone) is purported to have positive consequences in terms of affect and performance; however, there is no empirical evidence about these links in visual creativity. Positive affect often--but inconsistently--facilitates creativity, and both may be linked to experiencing flow. This study aimed to determine relationships between these variables within visual creativity. Participants performed the creative mental synthesis task to simulate the creative process. Affect change (pre- vs. post-task) and flow were measured via questionnaires. The creativity of synthesis drawings was rated objectively and subjectively by judges. Findings empirically demonstrate that flow is related to affect improvement during visual creativity. Affect change was linked to productivity and self-rated creativity, but no other objective or subjective performance measures. Flow was unrelated to all external performance measures but was highly correlated with self-rated creativity; flow may therefore motivate perseverance towards eventual excellence rather than provide direct cognitive enhancement.

  17. Modelling of the Czochralski flow

    OpenAIRE

    Jan Franc

    1998-01-01

    The Czochralski method of the industrial production of a silicon single crystal consists of pulling up the single crystal from the silicon melt. The flow of the melt during the production is called the Czochralski flow. The mathematical description of the flow consists of a coupled system of six P.D.E. in cylindrical coordinates containing Navier-Stokes equations (with the stream function), heat convection-conduction equations, convection-diffusion equation for oxygen impurity and an equation...

  18. Subchannel analysis with flow blockages

    Science.gov (United States)

    Sabotinov, L.

    1985-05-01

    The steady state single-phase three-dimensional flow in the rod bundle geometry of a nuclear pressurized water reactor was calculated with the PHOENICS 84 program. Flow blockages, which may occur under accident conditions, are simulated. Results show that PHOENICS-84 can be applied to calculation of the three-dimensional fields of velocities in fuel rod bundles containing complete flow blockages in cells. The code can treat recirculation zones.

  19. Joseph Cornell's flow learning use

    OpenAIRE

    Lužnik, Anja

    2014-01-01

    Natural science is one of the subjects where nature or natural environment can often be used directly for teaching. Joseph Cornell, who introduced Flow Learning, also emphasises this fact. The main focus of my thesis was how Joseph Cornell’s Flow Learning could be used in our primary schools. I selected some learning objectives out of natural science and technology curriculum which could be achieved with the Flow Learning system using Cornell’s activities. I tested my thesis in practice w...

  20. Reconfigurable Parallel Data Flow Architecture

    CERN Document Server

    Naji, Hamid Reza

    2010-01-01

    This paper presents a reconfigurable parallel data flow architecture. This architecture uses the concepts of multi-agent paradigm in reconfigurable hardware systems. The utilization of this new paradigm has the potential to greatly increase the flexibility, efficiency, expandability of data flow systems and to provide an attractive alternative to the current set of disjoint approaches that are currently applied to this problem domain. The ability of methodology to implement data flow type processing with different models is presented in this paper.

  1. Confined vortices in flow machinery

    Science.gov (United States)

    Escudier, Marcel

    After noting such basic aspects of vortex flows as the concepts of supercritical and subcritical flow and vortex breakdown, swirling flow behavior in various practical devices is discussed. The devices in question encompass swirl-stabilized combustion in industrial combustion chambers, fluidic vortex amplifiers that may be used as large scale valves, turbomachine outlets that can efficiently divert axial throughflow in a tangential direction, 'cyclone' separators, turbine draft tube surge phenomena, and the Ranque-Hilsch refrigeration tube.

  2. Do European capital flows comove?

    OpenAIRE

    Silvio Contessi; Pierangelo DePace

    2008-01-01

    We study the cross-sectional correlations of net, total, and disaggregated capital flows for the major source and recipient European Union countries. We seek evidence of changes in these correlations since the introduction of the euro to understand whether the European Union can be considered a unique entity with regard to its international capital flows. We first use Ng's (2006) "uniform spacing" methodology to rank cross-sectional correlations (i.e., which flows comove more) and to shed lig...

  3. Gross job flows and firms

    OpenAIRE

    Scott Schuh; Robert K. Triest

    1999-01-01

    This paper extends the work of Dunne, Roberts, and Samuelson [3] and Davis, Haltiwanger, and Schuh [2] on gross job flows among manufacturing plants. Gross job creation, destruction, and reallocation have been shown to be important in understanding the birth, growth, and death of plants, and the relation of plant life cycles to the business cycle. However, little is known about job flows between firms or how job flows among plants occur within firms (corporate restructuring). We use informati...

  4. DEBRIS FLOWS AND HYPERCONCENTRATED STREAMFLOWS.

    Science.gov (United States)

    Wieczorek, Gerald F.

    1986-01-01

    Examination of recent debris-flow and hyperconcentrated-streamflow events in the western United States reveals (1) the topographic, geologic, hydrologic, and vegetative conditions that affect initiation of debris flows and (2) the wide ranging climatic conditions that can trigger debris flows. Recognition of these physiographic and climatic conditions has aided development of preliminary methods for hazard evaluation. Recent developments in the application of electronic data gathering, transmitting, and processing systems shows potential for real-time hazard warning.

  5. Low flow hydrology: a review

    CSIR Research Space (South Africa)

    Smakhtin, VU

    2001-01-10

    Full Text Available . In cold or mountainous regions, in addition to the usual catch- ment parameters, low flows are subject to the special influences of ice and snow melting (Bowles and Riley, 1976; Gerard, 1981; Collins, 1982; Fountain and Tangborn, 1985; Gurnell, 1993... the various aspects of the cumulative output of these processes—the low-flow part of a continuous streamflow hydrograph. Low flows are normally derived from groundwater discharge or surface discharge from lakes, marshes, or melting glaciers. Lowest annual...

  6. Quantifying information flow during emergencies

    National Research Council Canada - National Science Library

    Gao, Liang; Song, Chaoming; Gao, Ziyou; Barabási, Albert-László; Bagrow, James P; Wang, Dashun

    2014-01-01

    ... to propagate situational awareness. We study real anomalous events using country-wide mobile phone data, finding that information flow during emergencies is dominated by repeated communications...

  7. Galois Connections for Flow Algebras

    DEFF Research Database (Denmark)

    Filipiuk, Piotr; Terepeta, Michal Tomasz; Nielson, Hanne Riis

    2011-01-01

    We generalise Galois connections from complete lattices to flow algebras. Flow algebras are algebraic structures that are less restrictive than idempotent semirings in that they replace distributivity with monotonicity and dispense with the annihilation property; therefore they are closer...... to the approach taken by Monotone Frameworks and other classical analyses. We present a generic framework for static analysis based on flow algebras and program graphs. Program graphs are often used in Model Checking to model concurrent and distributed systems. The framework allows to induce new flow algebras...

  8. Module bay with directed flow

    Science.gov (United States)

    Torczynski, John R.

    2001-02-27

    A module bay requires less cleanroom airflow. A shaped gas inlet passage can allow cleanroom air into the module bay with flow velocity preferentially directed toward contaminant rich portions of a processing module in the module bay. Preferential gas flow direction can more efficiently purge contaminants from appropriate portions of the module bay, allowing a reduced cleanroom air flow rate for contaminant removal. A shelf extending from an air inlet slit in one wall of a module bay can direct air flowing therethrough toward contaminant-rich portions of the module bay, such as a junction between a lid and base of a processing module.

  9. UZ Flow Models and Submodels

    Energy Technology Data Exchange (ETDEWEB)

    P. Dixon

    2004-02-11

    The purpose of this Model Report is to document the unsaturated zone (UZ) fluid flow and tracer transport models and submodels as well as the flow fields generated utilizing the UZ Flow and Transport Model of Yucca Mountain (UZ Model), Nevada. This work was planned in ''Technical Work Plan (TWP) for: Performance Assessment Unsaturated Zone'' (BSC 2002 [160819], Section 1.10, Work Package AUZM06). The UZ Model has revised, updated, and enhanced the previous UZ Flow Model REV 00 ICN 01 (BSC 2001 [158726]) by incorporation of the conceptual repository design with new grids, recalibration of property sets, and more comprehensive validation effort. The flow fields describe fracture-fracture, matrix-matrix, and fracture-matrix liquid flow rates and their spatial distributions as well as moisture conditions in the UZ system. These 3-D UZ flow fields are used directly by Performance Assessment (PA). The model and submodels evaluate important hydrogeologic processes in the UZ as well as geochemistry and geothermal conditions. These provide the necessary framework to test conceptual hypotheses of flow and transport at different scales and predict flow and transport behavior under a variety of climatic conditions. In addition, this Model Report supports several PA activities, including abstractions, particle-tracking transport simulations, and the UZ Radionuclide Transport Model.

  10. Reactive particles in random flows.

    Science.gov (United States)

    Károlyi, György; Tél, Tamás; de Moura, Alessandro P S; Grebogi, Celso

    2004-04-30

    We study the dynamics of chemically or biologically active particles advected by open flows of chaotic time dependence, which can be modeled by a random time dependence of the parameters on a stroboscopic map. We develop a general theory for reactions in such random flows, and derive the reaction equation for this case. We show that there is a singular enhancement of the reaction in random flows, and this enhancement is increased as compared to the nonrandom case. We verify our theory in a model flow generated by four point vortices moving chaotically.

  11. Surface obstacles in pulsatile flow

    Science.gov (United States)

    Carr, Ian A.; Plesniak, Michael W.

    2016-11-01

    Flows past obstacles mounted on flat surfaces have been widely studied due to their ubiquity in nature and engineering. For nearly all of these studies, the freestream flow over the obstacle was steady, i.e. constant velocity unidirectional flow. Unsteady, pulsatile flows occur frequently in biology, geophysics, biomedical engineering, etc. Our study is aimed at extending the comprehensive knowledge base that exists for steady flows to considerably more complex pulsatile flows. Beyond the important practical applications, characterizing the vortex and wake dynamics of flows around surface obstacles embedded in pulsatile flows can provide insights into the underlying physics in all wake and junction flows. In this study, we experimentally investigated the wake of four canonical surface obstacles: hemisphere, cube, and circular cylinders with aspect ratio of 1:1 and 2:1. Phase-averaged PIV and hot-wire anemometry are used to characterize the dynamics of coherent structures in the wake and at the windward junction of the obstacles. Complex physics occur during the deceleration phase of the pulsatile inflow. We propose a framework for understanding these physics based on self-induced vortex propagation, similar to the phenomena exhibited by vortex rings. This material is based in part upon work supported by the National Science Foundation under Grant Number CBET-1236351, and GW Centeor Biomimetics and Bioinspired Engineering (COBRE).

  12. FLOW PROPERTIES OF COHESIVE NANOPOWDERS

    Institute of Scientific and Technical Information of China (English)

    Jürgen Tomas

    2003-01-01

    The fundamentals of cohesive powder consolidation and flow behaviour using a reasonable combination of particle and continuum mechanics are explained. By means of the model "stiff particles with soft contacts", the influence of elastic-plastic repulsion in particle contacts is demonstrated. With this as the physical basis, the stationary yield locus, instantaneous yield loci and consolidation loci, flow function and compression function are presented. The flow properties of a very cohesive titania nanopowder (ds=200 nm) are shown. These models ara used to evaluate shear cell test results as constitutive functions for computer aided apparatus design for reliable powder flow.

  13. Optic flow and autonomous navigation.

    Science.gov (United States)

    Campani, M; Giachetti, A; Torre, V

    1995-01-01

    Many animals, especially insects, compute and use optic flow to control their motion direction and to avoid obstacles. Recent advances in computer vision have shown that an adequate optic flow can be computed from image sequences. Therefore studying whether artificial systems, such as robots, can use optic flow for similar purposes is of particular interest. Experiments are reviewed that suggest the possible use of optic flow for the navigation of a robot moving in indoor and outdoor environments. The optic flow is used to detect and localise obstacles in indoor scenes, such as corridors, offices, and laboratories. These routines are based on the computation of a reduced optic flow. The robot is usually able to avoid large obstacles such as a chair or a person. The avoidance performances of the proposed algorithm critically depend on the optomotor reaction of the robot. The optic flow can be used to understand the ego-motion in outdoor scenes, that is, to obtain information on the absolute velocity of the moving vehicle and to detect the presence of other moving objects. A critical step is the correction of the optic flow for shocks and vibrations present during image acquisition. The results obtained suggest that optic flow can be successfully used by biological and artificial systems to control their navigation. Moreover, both systems require fast and accurate optomotor reactions and need to compensate for the instability of the viewed world.

  14. Modeling Size Polydisperse Granular Flows

    Science.gov (United States)

    Lueptow, Richard M.; Schlick, Conor P.; Isner, Austin B.; Umbanhowar, Paul B.; Ottino, Julio M.

    2014-11-01

    Modeling size segregation of granular materials has important applications in many industrial processes and geophysical phenomena. We have developed a continuum model for granular multi- and polydisperse size segregation based on flow kinematics, which we obtain from discrete element method (DEM) simulations. The segregation depends on dimensionless control parameters that are functions of flow rate, particle sizes, collisional diffusion coefficient, shear rate, and flowing layer depth. To test the theoretical approach, we model segregation in tri-disperse quasi-2D heap flow and log-normally distributed polydisperse quasi-2D chute flow. In both cases, the segregated particle size distributions match results from full-scale DEM simulations and experiments. While the theory was applied to size segregation in steady quasi-2D flows here, the approach can be readily generalized to include additional drivers of segregation such as density and shape as well as other geometries where the flow field can be characterized including rotating tumbler flow and three-dimensional bounded heap flow. Funded by The Dow Chemical Company and NSF Grant CMMI-1000469.

  15. A Marine Traffic Flow Model

    Directory of Open Access Journals (Sweden)

    Tsz Leung Yip

    2013-03-01

    Full Text Available A model is developed for studying marine traffic flow through classical traffic flow theories, which can provide us with a better understanding of the phenomenon of traffic flow of ships. On one hand, marine traffic has its special features and is fundamentally different from highway, air and pedestrian traffic. The existing traffic models cannot be simply extended to marine traffic without addressing marine traffic features. On the other hand, existing literature on marine traffic focuses on one ship or two ships but does not address the issues in marine traffic flow.

  16. The AdaBoost Flow

    OpenAIRE

    Lykov, A.; Muzychka, S.; Vaninsky, K.

    2011-01-01

    We introduce a dynamical system which we call the AdaBoost flow. The flow is defined by a system of ODEs with control. We show that three algorithms of the AdaBoost family (i) the AdaBoost algorithm of Schapire and Freund (ii) the arc-gv algorithm of Breiman (iii) the confidence rated prediction of Schapire and Singer can be can be embedded in the AdaBoost flow. The nontrivial part of the AdaBoost flow equations coincides with the equations of dynamics of nonperiodic Toda system written in te...

  17. Fundamentals of gas particle flow

    CERN Document Server

    Rudinger, G

    1980-01-01

    Fundamentals of Gas-Particle Flow is an edited, updated, and expanded version of a number of lectures presented on the "Gas-Solid Suspensions” course organized by the von Karman Institute for Fluid Dynamics. Materials presented in this book are mostly analytical in nature, but some experimental techniques are included. The book focuses on relaxation processes, including the viscous drag of single particles, drag in gas-particles flow, gas-particle heat transfer, equilibrium, and frozen flow. It also discusses the dynamics of single particles, such as particles in an arbitrary flow, in a r

  18. Coriolis mass flow rate meters for low flows

    NARCIS (Netherlands)

    Mehendale, A.

    2008-01-01

    The accurate and quick measurement of small mass flow rates (~10 mg/s) of fluids is considered an “enabling technology��? in semiconductor, fine-chemical, and food & drugs industries. Flowmeters based on the Coriolis effect offer the most direct sensing of the mass flow rate, and for this reason do

  19. Coriolis mass flow rate meters for low flows

    NARCIS (Netherlands)

    Mehendale, Aditya

    2008-01-01

    The accurate and quick measurement of small mass flow rates (~10 mg/s) of fluids is considered an "enabling technology" in semiconductor, fine-chemical, and food & drugs industries. Flowmeters based on the Coriolis effect offer the most direct sensing of the mass flow rate, and for this reason do no

  20. Reconsidering Television Program Flows, or Whose Flow Is It Anyway?

    Science.gov (United States)

    White, Mimi

    1995-01-01

    Argues that media flow research needs to be reconceptualized differently from notions of one-way flows that serve coherent national interests, and whose asymmetries can be measured statistically and unambiguously. Argues that global circulation is now complex and contradictory, and that new culturally-based models and methods are needed for…