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Sample records for holmstrm karin jrverud

  1. Photometry of Karin family asteroids

    NASA Astrophysics Data System (ADS)

    Hahn, G.; Mottola, S.; Sen, A. K.; Harris, A. W.; Kührt, E.; Mueller, M.

    2006-12-01

    We have performed photometric observations in the V-band of two asteroids belonging to the Karin asteroid family, (11728) Einer and (93690) 2000 VE21 , using the 2-m Himalayan Chandra Telescope, Hanle and 2k ×4k pixels CCD imager. We obtained measurements during two nights (November 25 and 26, 2005) which enabled information on the rotational periods and the lightcurve amplitudes of the asteroids to be derived. In addition, we derived the absolute magnitudes H, improving previously published values. These observations were performed to complement the IR observations obtained for a set of Karin family asteroids with the Spitzer space telescope.

  2. 832 Karin: Absence of rotational spectral variations

    NASA Astrophysics Data System (ADS)

    Vernazza, Pierre; Rossi, Alessandro; Birlan, Mirel; Fulchignoni, Marcello; Nedelcu, Alin; Dotto, Elisabetta

    2007-11-01

    832 Karin is the largest member of the young Karin cluster that formed 5.75±0.05 Myr ago in the outer main belt. Surprisingly, recent near-IR spectroscopy measurements [Sasaki, T., Sasaki, S., Watanabe, J., Sekiguchi, T., Yoshida, F., Kawakita, H., Fuse, T., Takato, N., Dermawan, B., Ito, T., 2004. Astrophys. J. 615 (2), L161-L164] revealed that Karin's surface shows different colors as a function of rotational phase. It was interpreted that 832 Karin shows us the reddish space-weathered exterior surface of the parent body as well as an interior face, which has not had time to become space-weathered. This result is at odds with recent results including seismic and geomorphic modeling, modeling of the Karin cluster formation and measurements of the space weathering rate. Consequently, we aimed to confirm/infirm this surprising result by sampling Karin's spectrum well throughout its rotation. Here, we present new visible (0.45-0.95 μm) and near-infrared (0.7-2.5 μm) spectroscopic observations of 832 Karin obtained in January and April 2006, covering most of Karin's longitudes. In the visible range, we find that Karin shows no rotational spectral variations. Similarly, we find that Karin exhibits very little (to none) spectral variations with rotation in the near-IR range. Our results imply that 832 Karin has a homogeneous surface, in terms of composition and surface age. Our results also imply that the impact that generated the family refreshed entirely Karin's surface, and probably the surfaces of all members.

  3. The Spin Vector of (832) Karin

    NASA Astrophysics Data System (ADS)

    Slivan, Stephen M.; Molnar, L. A.

    2010-10-01

    We observed rotation lightcurves of Koronis family and Karin cluster member (832) Karin during its four consecutive apparitions in 2006-2009, and combined the new observations with previously published lightcurves to determine its spin vector orientation and preliminary model shape. Karin is a prograde rotator with a period of 18.352 h, spin obliquity near 41°, and pole ecliptic longitude near either 51° or 228°. Although the two ambiguous pole solutions are near the clustered pole solutions of four Koronis family members whose spins are thought to be trapped in a spin-orbit resonance (Vokrouhlický et al., 2003), Karin does not seem to be trapped in the resonance; this is consistent with the expectation that the 6 My age of Karin (Nesvorný et al., 2002) is too young for YORP torques to have modified its spin since its formation. The spin vector and shape results for Karin will constrain family formation models that include spin properties, and we discuss the Karin results in the context of the other members of the Karin cluster, the Karin parent body, and the parent body's siblings in the Koronis family.

  4. Spitzer Survey of the Karin Cluster Asteroids

    NASA Astrophysics Data System (ADS)

    Harris, Alan W.; Mueller, M.; Lisse, C.; Cheng, A.; Osip, D.

    2007-10-01

    The Karin cluster is one of the youngest known families of main-belt asteroids, dating back to a collisional event only 5.8 Myr ago. Using the Spitzer Space Telescope we have sampled the thermal continua of 17 Karin cluster asteroids, down to the smallest members discovered so far, in order to derive accurate sizes and study the physical properties of their surfaces. The albedos of the observed Karins appear to be very similar. The albedos, pv, have a mean of 0.17 and a standard deviation of 0.04, compared to pv = 0.15 ± 0.05 for 832 Karin itself (for H = 11.2 ± 0.3). The derived diameters range from 20 km for 832 Karin to 1.9 km for 93690, with uncertainties of 10%. The Karins data show no evidence of albedo dependence on size, and the small range of albedos is consistent with all program targets being S-type bodies. There is some evidence for higher values of thermal inertia amongst the smaller family members, which may be indicative of coarser regolith. These results are preliminary, pending outstanding Spitzer observations and further analysis. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA.

  5. 832 Karin Shows No Rotational Spectral Variations

    NASA Astrophysics Data System (ADS)

    Chapman, Clark R.; Enke, B.; Merline, W. J.; Nesvorny, D.; Tamblyn, P.; Young, E. F.

    2006-09-01

    Sasaki et al. (2004, 2005) claimed that 832 Karin, the brightest member of the very young (5.75 Myr) Karin cluster of the Koronis family, shows dramatically different colors as a function of rotational phase. It was interpreted that Karin is a fragment of the recently broken-up asteroid, showing the reddish space-weathered exterior surface of the precursor asteroid as well as an interior face, which has not had time to become space-weathered. On five nights during UT 7-14 January 2006, we observed Karin with the SpeX instrument, 0.8-2.5 microns, on the IRTF. We sampled its spectrum well throughout its rotation. We analyzed the data in 50 deg. intervals of rotational longitude; some longitudes were sampled during two different nights. We find that Karin exhibits minimal spectral variations with rotation, certainly nothing of the magnitude reported by Sasaki et al. Since our data resemble Sasaki et al.'s "blue" and "green" sets, we suggest that their "red" set is spurious. Indeed, it is difficult to understand how the reported color change could have occurred during such a modest interval ( 4%) of rotational longitude. (Note that we have not determined Karin's pole position nor the phase of the Sasaki et al. data within our own coverage, so the refutation of dramatic color change is not absolutely secure.) Karin and its family members are not quite as red as typical S-types, yet have shallow absorption bands. Perhaps the space-weathering process affecting these young asteroids has had time to reduce spectral contrast, but has not operated long enough to redden them -- an intermediate case of space weathering, which has gone to completion for older main-belt asteroids of these sizes. Supported by the NASA Planetary Astronomy Program. T. Sasaki et al. 2004. ApJ 615, L161-L164; T. Sasaki et al. 2005. LPSC XXXVI, 1590.pdf.

  6. Spectroscopic characterization of the Karin family

    NASA Astrophysics Data System (ADS)

    Vernazza, P.; Fulchignoni, M.; Birlan, M.; Dotto, E.; Rossi, A.; Fornasier, S.; Marzari, F.; Nesvorny, D.

    2005-08-01

    The Karin asteroidal family was firstly identified by Nesvorny et al. (2002, Nature 417) who numerically integrated the orbits of 39 known members. More recently Nesvorny and Bottke (2004) analyzed a wider sample of objects and, taking into account also the Yarkovsky effect, identified the common origin of 90 family members at 5.75±0.05 Myr in the past. This is an exceptionally young age for an asteroid family. In fact, other known families are thought to be much older, 100 Myr to Gyrs old. We carried out visible and near-infrared spectroscopy of several members of the Karin family. We observed 5 member of the Karin family on November 2003 using the IRTF telescope. These data confirm that 832 Karin is an S-type asteroid (as indicated by Binzel, private communication), characterized by strong absorption features of olivine and pyroxene at about 1 and 2 μ m. Visible spectra for 20 objects were later obtained in December, 2004 with EMMI/NTT (ESO, La Silla) and with MOS/CFHT (Mauna Kea, Hawaii). Fifteen of these objects (832 Karin among them), have S-type spectra with the maximum of each spectra located at a very similar wavelength. This result sustain the hypothesis of a common origin. Five other spectra obtained seem rather primitive (B,C types). We analysed the spectra of the Karin cluster in the context of the Koronis family. This analysis reveals that the spectra are less red than those of the Koronis members. Moreover, we can interpret them as less mature surfaces. Finally, we made an interpretation of the surface composition of 832 Karin, using the Shkuratov scattering model.

  7. Spin vectors in the Koronis family: III. (832) Karin

    NASA Astrophysics Data System (ADS)

    Slivan, Stephen M.; Molnar, Lawrence A.

    2012-08-01

    Studies of asteroid families constrain models of asteroid collisions and evolution processes, and the Karin cluster within the Koronis family is among the youngest families known (Nesvorný, D., Bottke, Jr., W.F., Dones, L., Levison, H.F. [2002]. Nature 417, 720-722). (832) Karin itself is by far the largest member of the Karin cluster, thus knowledge of Karin's spin vector is important to constrain family formation and evolution models that include spin, and to test whether its spin properties are consistent with the Karin cluster being a very young family. We observed rotation lightcurves of Karin during its four consecutive apparitions in 2006-2009, and combined the new observations with previously published lightcurves to determine its spin vector orientation and preliminary model shape. Karin is a prograde rotator with a period of (18.352 ± 0.003) h, spin obliquity near (42 ± 5)°, and pole ecliptic longitude near either (52 ± 5)° or (230 ± 5)°. The spin vector and shape results for Karin will constrain models of family formation that include spin properties; in the meantime we briefly discuss Karin's own spin in the context of those of other members of the Karin cluster and the parent body's siblings in the Koronis family.

  8. Lightcurves of the Karin family asteroids

    NASA Astrophysics Data System (ADS)

    Yoshida, Fumi; Ito, Takashi; Dermawan, Budi; Nakamura, Tsuko; Takahashi, Shigeru; Ibrahimov, Mansur A.; Malhotra, Renu; Ip, Wing-Huen; Chen, Wen-Ping; Sawabe, Yu; Haji, Masashige; Saito, Ryoko; Hirai, Masanori

    2016-05-01

    The Karin family is a young asteroid family formed by an asteroid breakup 5.8 Myr ago. Since the members of this family probably have not experienced significant orbital or collisional evolution yet, it is possible that they still preserve properties of the original family-forming event in terms of their spin state. We carried out a series of photometric observations of the Karin family asteroids, and here we report on the analysis of the lightcurves including the rotation period of eleven members. The mean rotation rate of the Karin family members turned out to be much lower than those of near-Earth asteroids or small main belt asteroids (diameter D < 12 km), and even lower than that of large main belt asteroids (D > 130 km). We investigated a correlation between the peak-to-trough variation and the rotation period of the eleven Karin family asteroids, and found a possible trend that elongated members have lower spin rates, and less elongated members have higher spin rates. However, this trend has to be confirmed by another series of future observations.

  9. Karin cluster formation by asteroid impact

    NASA Astrophysics Data System (ADS)

    Nesvorný, David; Enke, Brian L.; Bottke, William F.; Durda, Daniel D.; Asphaug, Erik; Richardson, Derek C.

    2006-08-01

    Insights into collisional physics may be obtained by studying the asteroid belt, where large-scale collisions produced groups of asteroid fragments with similar orbits and spectra known as the asteroid families. Here we describe our initial study of the Karin cluster, a small asteroid family that formed 5.8±0.2 Myr ago in the outer main belt. The Karin cluster is an ideal 'natural laboratory' for testing the codes used to simulate large-scale collisions because the observed fragments produced by the 5.8-Ma collision suffered apparently only limited dynamical and collisional erosion. To date, we have performed more than 100 hydrocode simulations of impacts with non-rotating monolithic parent bodies. We found good fits to the size-frequency distribution of the observed fragments in the Karin cluster and to the ejection speeds inferred from their orbits. These results suggest that the Karin cluster was formed by a disruption of an ≈33-km-diameter asteroid, which represents a much larger parent body mass than previously estimated. The mass ratio between the parent body and the largest surviving fragment, (832) Karin, is ≈0.15-0.2, corresponding to a highly catastrophic event. Most of the parent body material was ejected as fragments ranging in size from yet-to-be-discovered sub-km members of the Karin cluster to dust grains. The impactor was ≈5.8 km across. We found that the ejections speeds of smaller fragments produced by the collision were larger than those of the larger fragments. The mean ejection speeds of >3-km-diameter fragments were ≈10 ms. The model and observed ejection velocity fields have different morphologies perhaps pointing to a problem with our modeling and/or assumptions. We estimate that ˜5% of the large asteroid fragments created by the collision should have satellites detectable by direct imaging (separations larger than 0.1 arcsec). We also predict a large number of ejecta binary systems with tight orbits. These binaries, located in the

  10. Age of the Karin Cluster of Asteroids

    NASA Astrophysics Data System (ADS)

    Cheng, A. F.; Knezevic, Z.; Cellino, A.; Dell'Oro, A.

    2005-12-01

    The Karin Cluster, the youngest known asteroid family, was formed by a catastrophic disruption event about 5.8 million years ago. We have undertaken extensive numerical orbital integrations to confirm and refine the cluster age and to refine cluster membership. The Karin Cluster is important because its members have a precisely known, common formation age, enabling new tests of models for asteroid fragmentation, orbital evolution, surface space weathering, and regolith formation and evolution, but it is necessary to distinguish cluster members from background objects in a densely populated region of the main asteroid belt, close to the center of the Koronis family. We have performed full orbital integrations of 122 numbered asteroids backwards in time over the last 10 million years, to calculate filtered mean Keplerian elements at 500 year time resolution. These calculations show that the age of the Karin cluster is 5.7635 ± 0.0005 Myr, consistent with prior work. The calculations also confirm 54 numbered asteroids as cluster members, and they identify as interlopers some objects included in previous cluster lists.

  11. Color Variation of a Very Young Asteroid, Karin

    NASA Astrophysics Data System (ADS)

    Ito, Takashi; Yoshida, Fumi

    2007-02-01

    We present current results of our long-term campaign to make photometric observations of the new-born Karin family asteroids, especially those of (832) Karin. Karin, an S-type main-belt asteroid, is the largest member of the Karin family. This asteroid is likely a large fragment of a disruption event in the main asteroid belt that occurred about 5.8 million years ago. We obtained multi-color photometric observations of this asteroid in 2003 and 2004. We have reported a potential surface color variation of this asteroid, which indicates the existence of both mature and fresh surfaces on it. However, as of 2004 September, this asteroid apparently does not show a strong surface color difference, which might give us some insight into its spin axis orientation and shape. This is quite an interesting result, but it has to be confirmed by future observations.

  12. Physical characterization of the Karin family

    NASA Astrophysics Data System (ADS)

    Vernazza, P.; Birlan, M.; Rossi, A.; Dotto, E.; Nesvorny, D.; Brunetto, R.; Fornasier, S.; Fulchignoni, M.; Renner, S.

    2006-12-01

    Aims.The Karin cluster is a small asteroid family that formed 5.8 ± 0.2 Myr ago in the outer main belt. This is an exceptionally young age for an asteroid family. To investigate the composition and homogeneity of the members of this family, we started a spectroscopic survey in the visible and in the near-IR. Methods: .We observed 24 Karin asteroid members in the visible and 6 members in the near-IR. Results: .In the visible range, all the objects share the same characteristics: a maximum around λ = 0.75 μm, and a spectral slope spanning a continuous but limited range; in the NIR, our spectra show a similar behaviour. Our results suggest global homogeneity of the parent body and none of the investigated objects seems to be an interloper. These results are consistent with the dynamical hypothesis of a common origin. Finally, the range of spectral slopes is similar with the range of slopes for OC meteorites. We interpret this result as an indication of a low degree of spatial alteration for the observed surfaces. This result is coherent with the young age of the family.

  13. VizieR Online Data Catalog: Properties of asteroids in Karin cluster (Carruba+, 2016)

    NASA Astrophysics Data System (ADS)

    Carruba, V.; Nesvorny, D.; Vokrouhlicky, D.

    2016-07-01

    Many new asteroids have been discovered since the last dynamical analysis of the Karin cluster. Here we repeat the analysis of Nesvorny & Bottke (2004Icar..170..324N) with an orbital catalog that contains nearly seven times more asteroids than there were available back in 2004. We revise the Karin family membership by applying the usual clustering method on the new orbital catalog. The taxonomical and albedo interlopers are eliminated. We then apply a more stringent criterion of the Karin family membership by requiring that orbits converged with each other ~5.75Myr ago. In Table1, we report the list of 480 identified Karin cluster members. (1 data file).

  14. Young Asteroid 832 Karin shows no rotational spectral variations

    NASA Astrophysics Data System (ADS)

    Chapman, C. R.; Enke, B.; Merline, W. J.; Tamblyn, P.; Nesvorný, D.; Young, E. F.; Olkin, C.

    2007-11-01

    We have made near-IR spectral observations of the very young (5.75 Myr) S-type asteroid 832 Karin, well sampled in rotational phase over its 18.35-h period. We find no significant variations in its reflectance spectrum. Karin, the brightest member of the Karin cluster (a sub-family of the larger, older Koronis dynamical family), was shown to be exceptionally young by Nesvorný et al. [Nesvorný, D., Bottke, W.F., Dones, L., Levison, H., 2002. Nature 417, 720-722], using backward numerical integration of orbital elements of cluster members. Their precise dating of the collisional breakup gives us an opportunity, for the first time and without age-dating of physical samples, to monitor time-evolution of processes, like space weathering, that operate on timescales of ˜1-10 Myr. Sasaki et al. [Sasaki, T., Sasaki, S., Watanabe, J., Sekiguchi, T., Yoshida, F., Kawakita, H., Fuse, T., Takato, N., Dermawan, B., Ito, T., 2004. Astrophys. J. 615, L161-L164; Sasaki, T., Sasaki, S., Watanabe, J., Sekiguchi, T., Yoshida, F., Ito., T., Kawakita, H., Fuse, T., Takato, N., Dermawan, B., 2005. Lunar Planet. Sci. XXXVI. Abstract #1590] had made similar measurements of Karin, although more sparsely sampled than ours, and claimed dramatically different colors as a function of rotational phase. Sasaki et al. interpreted their data to be showing the reddish, space-weathered exterior surface of the precursor asteroid, as well as an interior face, which had not had time to become space-weathered. On five nights over 2006 January 7-14 UT, we observed Karin with the SpeX (0.8-2.5 μm) spectrometer of the IRTF. We analyze data in 30° intervals of rotational longitude, some of which we sampled on two different nights. The spectra are consistent with little or no spectral variation as the asteroid rotates; certainly there are no changes as large as previously reported. The previous observations were probably spurious. Our average spectrum resembles the "blue" spectrum of Sasaki et al., which

  15. A newborn asteroid 832 Karin with old and new surfaces SUBARU spectroscopy

    NASA Astrophysics Data System (ADS)

    Sasaki, Sho; Sasaki, Takanori; Watanabe, Jun-ichi; Yoshida, Fumi; Kawakita, Hideyo; Takato, Naruhisa; Dermawan, Budi; Fuse, Tetsuharu; Ito, Takashi; Sekiguchi, Tomohiko

    2006-01-01

    The mismatch between reflectance spectra of most common asteroids (S-type asteroids) and most common meteorites (ordinary chondrites) is thought to be caused by space weathering. Recent study of celestial mechanics has led to the discovery of a young group of S-type asteroids, "Karin cluster group", which is thought to be remnants of a collisional breakup only 5.8 million years ago. We performed near-infrared spectroscopy of the brightest asteroid 832 Karin among this cluster group. For different rotational phases of Karin, we derived different spectra such as reddened spectrum like that of S-type asteroid and unreddened spectrum like that of ordinary chondrites. These findings indicate that a part of Karin may retain spectrally mature surface of its parent body. Although Karin might have formed from gravitational accumulation from catastrophic collision of its parent body, there would be some color heterogeneity on its surface if Karin collected materials which derived the weathered surface of the parent body.

  16. A Robust Survey of the Physical Properties of the Karin Cluster Asteroids

    NASA Astrophysics Data System (ADS)

    Harris, Alan; Cheng, Andrew; Fitzsimmons, Alan; Hicks, Michael; Lisse, Carey; Lowry, Stephen; Mueller, Michael; Osip, Dave

    2005-06-01

    The Karin cluster is by far the youngest known family of main-belt asteroids, dating back to a collisional event only 5.8+/-0.2 Myr ago. We propose to sample the thermal continua of 17 Karin cluster asteroids of different sizes, down to the smallest members discovered so far, in order to derive accurate sizes and study the physical properties of their surfaces. Our aims include a study of trends in thermal inertia and albedo with size. The analysis will be based on sophisticated thermal models that will provide important insight into thermal inertia and regolith coverage. The widely used 'standard thermal model' leads to serious errors in thermal studies of small asteroids and is not adequate for a detailed study of the physical characteristics of Karin cluster members. The following questions are amongst those addressed by this program: 1. Are the distributions of sizes and albedos compatible with the Karin cluster being the result of a single catastrophic collision 5.8+/-0.2 Myr ago (Nesvorny et al., 2002)? 2. Are the sizes and thermal properties of the Karin-cluster members compatible with the claim of Nesvorny and Bottke (2004) that the Yarkovsky Effect is responsible for an apparent non-gravitational drift of their orbital motion? 3. Does the retention of a significant thermally insulating layer of regolith depend on asteroid size? If so, what are the consequences for modeling the Yarkovsky effect and the delivery of main-belt asteroids into near-Earth orbits? 4. Is there a correlation between albedo and size among the Karin cluster members similar to that evident for near-Earth asteroids in the same size range? If so, what are the consequences for models of age-dependent space weathering? (the Karin cluster members all have the same age).

  17. Detection of the YORP Effect for Small Asteroids in the Karin Cluster

    NASA Astrophysics Data System (ADS)

    Carruba, V.; Nesvorný, D.; Vokrouhlický, D.

    2016-06-01

    The Karin cluster is a young asteroid family thought to have formed only ≃ 5.75 Myr ago. The young age can be demonstrated by numerically integrating the orbits of Karin cluster members backward in time and showing the convergence of the perihelion and nodal longitudes (as well as other orbital elements). Previous work has pointed out that the convergence is not ideal if the backward integration only accounts for the gravitational perturbations from the solar system planets. It improves when the thermal radiation force known as the Yarkovsky effect is accounted for. This argument can be used to estimate the spin obliquities of the Karin cluster members. Here we take advantage of the fast growing membership of the Karin cluster and show that the obliquity distribution of diameter D≃ 1{--}2 km Karin asteroids is bimodal, as expected if the YORP effect acted to move obliquities toward extreme values (0° or 180°). The measured magnitude of the effect is consistent with the standard YORP model. The surface thermal conductivity is inferred to be 0.07–0.2 W m‑1 K‑1 (thermal inertia ≃ 300{--}500 J m‑2 K‑1 s{}-1/2). We find that the strength of the YORP effect is roughly ≃ 0.7 of the nominal strength obtained for a collection of random Gaussian spheroids. These results are consistent with a surface composed of rough, rocky regolith. The obliquity values predicted here for 480 members of the Karin cluster can be validated by the light-curve inversion method.

  18. Difference in Degree of Space Weathering on the Newborn Asteroid Karin

    NASA Astrophysics Data System (ADS)

    Sasaki, T.; Sasaki, S.; Watanabe, J. I.; Sekiguchi, T.; Yoshida, F.; Ito, T.; Kawakita, H.; Fuse, T.; Takato, N.; Dermawan, B.

    2005-03-01

    Here we report a near-infrared spectroscopy of the newborn asteroid Karin. For different rotational phases, we derived different spectra such as reddened spectrum like that of S- type asteroid and un-reddened spectrum like that of ordinary chondrite.

  19. Details of Recent Collisions of Asteroids 832 Karin and 158 Koronis

    NASA Astrophysics Data System (ADS)

    Molnar, Lawrence A.; Haegert, M. J.

    2009-09-01

    We present analysis of the membership and dynamics of two recently formed asteroid clusters: 832 Karin (5.72 My) and 158 Koronis (15.0 My). The unprecedented detail of both collisions (one catastrophic and one not) provides rigorous tests of asteroid collision models. We use the AstDyS catalog of analytic proper elements to identify asteroids with high quality orbits that are dynamically near the Karin cluster (873 objects), and use the OrbFit software to compute precise synthetic proper elements. We define a cut in five dimensional phase space to determine Karin membership. The key to an effective cut is the use of two linear combinations of elements: a combination of the longitudes that is independent of the Yarkovsky drift and a combination of eccentricity and drift-corrected semimajor axis. Karin cluster membership is increased to 387 objects, four times the previously published number. Highlights of analysis include a size-frequency distribution with significant curvature, and two clusters in the histogram of spin obliquities (inferred from the Yarkovsky drift of the longitudes). The latter is consistent with capture of the smallest members (diameters less than 2 km) in Slivan states. Removal of the Karin members from the sample reveals a previously unknown cluster of 151 objects resulting from a recent non-catastrophic collision with Koronis (which has 98.7% of the total mass). With an age of 15 My, individual longitudes have drifted by as much as 540 degrees due to the Yarkovsky effect, yet it remains possible to unwrap the angles and determine membership. Highlights of the analysis include final speeds relative to Koronis less than the escape speed and a pronounced preference for outflow directions in a small cone. The mass of the material launched below escape speed likely exceeds that of the escaped objects. Funded by a Kuiper endowment and a Calvin Research Fellowship.

  20. A survey of Karin cluster asteroids with the Spitzer Space Telescope

    NASA Astrophysics Data System (ADS)

    Harris, Alan W.; Mueller, Michael; Lisse, Carey M.; Cheng, Andrew F.

    2009-01-01

    The Karin cluster is one of the youngest known families of main-belt asteroids, dating back to a collisional event only 5.8±0.2 Myr ago. Using the Spitzer Space Telescope we have photometrically sampled the thermal continua (3.5-22 μm) of 17 Karin cluster asteroids of different sizes, down to the smallest members discovered so far, in order to make the first direct measurements of their sizes and albedos and study the physical properties of their surfaces. Our targets are also amongst the smallest main-belt asteroids observed to date in the mid-infrared. The derived diameters range from 17.3 km for 832 Karin to 1.5 km for 75176, with typical uncertainties of 10%. The mean albedo is p=0.215±0.015, compared to 0.20±0.07 for 832 Karin itself (for H=11.2±0.3), consistent with the view that the Karin asteroids are closely related physically as well as dynamically. The albedo distribution ( 0.12⩽p⩽0.32) is consistent with the range associated with S-type asteroids but the variation from one object to another appears to be significant. Contrary to the case for near-Earth asteroids, our data show no evidence of an albedo dependence on size. However, the mean albedo is lower than expected for young, fresh "S-type" surfaces, suggesting that space weathering can darken main-belt asteroid surfaces on very short timescales. Our data are also suggestive of a connection between surface roughness and albedo, which may reflect rejuvenation of weathered surfaces by impact gardening. While the available data allow only estimates of lower limits for thermal inertia, we find no evidence for the relatively high values of thermal inertia reported for some similarly sized near-Earth asteroids. Our results constitute the first observational confirmation of the legitimacy of assumptions made in recent modeling of the formation of the Karin cluster via a single catastrophic collision 5.8±0.2 Myr ago.

  1. Polarimetric evidence of close similarity between members of the Karin and Koronis dynamical families

    NASA Astrophysics Data System (ADS)

    Cellino, A.; Delbò, M.; Bendjoya, Ph.; Tedesco, E. F.

    2010-10-01

    We present the results of a campaign of polarimetric observations of small asteroids belonging to the Karin and Koronis families, carried out at the ESO Cerro Paranal Observatory using the VLT-Kueyen 8-m telescope. The Karin family is known to be very young, having likely been produced by the disruption of an original member of the Koronis family less than 6 Myr ago. The purpose of our study was to derive polarimetric properties for a reasonable sample of objects belonging to the two families, in order to look for possible systematic differences between them, to be interpreted in terms of differences in surface properties, in particular albedo. In turn, systematic albedo differences might be caused by different times of exposure to space weathering processes experienced by the two groups of objects. The results of our analysis indicate that no appreciable difference exists between the polarimetric properties of Karin and Koronis members. We thus find that space-weathering mechanisms may be very efficient in affecting surface properties of S-class asteroids on very short timescales. This result complements some independent evidence found by recent spectroscopic studies of very young families.

  2. Testing the Deployment Repeatability of a Precision Deployable Boom Prototype for the Proposed SWOT Karin Instrument

    NASA Technical Reports Server (NTRS)

    Agnes, Gregory S.; Waldman, Jeff; Hughes, Richard; Peterson, Lee D.

    2015-01-01

    NASA's proposed Surface Water Ocean Topography (SWOT) mission, scheduled to launch in 2020, would provide critical information about Earth's oceans, ocean circulation, fresh water storage, and river discharge. The mission concept calls for a dual-antenna Ka-band radar interferometer instrument, known as KaRIn, that would map the height of water globally along two 50 km wide swaths. The KaRIn antennas, which would be separated by 10 meters on either side of the spacecraft, would need to be precisely deployable in order to meet demanding pointing requirements. Consequently, an effort was undertaken to design build and prototype a precision deployable Mast for the KaRIn instrument. Each mast was 4.5-m long with a required dilitation stability of 2.5 microns over 3 minutes. It required a minimum first mode of 7 Hz. Deployment repeatability was less than +/- 7 arcsec in all three rotation directions. Overall mass could not exceed 41.5 Kg including any actuators and thermal blanketing. This set of requirements meant the boom had to be three times lighter and two orders of magnitude more precise than the existing state of the art for deployable booms.

  3. Modeling asteroid surfaces from observations and irradiation experiments: The case of 832 Karin

    NASA Astrophysics Data System (ADS)

    Brunetto, Rosario; Vernazza, Pierre; Marchi, Simone; Birlan, Mirel; Fulchignoni, Marcello; Orofino, Vincenzo; Strazzulla, Giovanni

    2006-10-01

    We define a new approach to model asteroidal space weathering. We started from recent results of ion irradiation experiments (60-400 keV) of meteorites and silicates to give an accurate description of space weathering, and we included its effects in the Shkuratov model. We found that the reddening and darkening process (in the range 0.3-2.5 μm) does not significantly affect the position or relative intensities of the mafic silicate absorption features and it mainly affects the continuum of reflectance spectra. This continuum is parameterized by a C coefficient, which is strongly related with the number of displacements per unit area (damage parameter); we consequently obtained an exposure time curve, and corresponding astrophysical timescales. We applied this new description of space weathering to model observed spectra of Asteroid 832 Karin, in the 0.4-2.4 μm spectral region. The obtained exposure time is slightly lower than the age of the impact and collisional breakup which originated the Karin asteroidal family, i.e., about 5.75×10 years.

  4. A spectral model for irradiated silicates: application to asteroid 832 Karin

    NASA Astrophysics Data System (ADS)

    Brunetto, R.; Vernazza, P.; Marchi, S.; Birlan, M.; Fulchignoni, M.; Orofino, V.; Strazzulla, G.

    We define a new approach to space weathering of airless bodies, and include its effect in the Shkuratov model. We start from recent results of ion irradiation experiments (60-400 keV) of meteorites and silicates; we find that the reddening and darkening process (in the range 0.3-2.5 microns) mainly affects the continuum of reflectance spectra (parameterized by a Cs coefficient), but it does not significantly affect the position or relative intensities of the mafic silicate absorption features. The Cs coefficient is strongly related with the number of displacements per unit area (damage parameter); we consequently obtain an exposure time curve, and corresponding astrophysical timescales. We apply this new description of space weathering to model observed spectra of asteroid 832 Karin, in the 0.4-2.4 microns spectral region. The obtained exposure time is slightly lower than the age of the impact and collisional breakup which originated the Karin asteroidal family, i.e. about 5.75 My.

  5. Onboard Interferometric SAR Processor for the Ka-Band Radar Interferometer (KaRIn)

    NASA Technical Reports Server (NTRS)

    Esteban-Fernandez, Daniel; Rodriquez, Ernesto; Peral, Eva; Clark, Duane I.; Wu, Xiaoqing

    2011-01-01

    An interferometric synthetic aperture radar (SAR) onboard processor concept and algorithm has been developed for the Ka-band radar interferometer (KaRIn) instrument on the Surface and Ocean Topography (SWOT) mission. This is a mission- critical subsystem that will perform interferometric SAR processing and multi-look averaging over the oceans to decrease the data rate by three orders of magnitude, and therefore enable the downlink of the radar data to the ground. The onboard processor performs demodulation, range compression, coregistration, and re-sampling, and forms nine azimuth squinted beams. For each of them, an interferogram is generated, including common-band spectral filtering to improve correlation, followed by averaging to the final 1 1-km ground resolution pixel. The onboard processor has been prototyped on a custom FPGA-based cPCI board, which will be part of the radar s digital subsystem. The level of complexity of this technology, dictated by the implementation of interferometric SAR processing at high resolution, the extremely tight level of accuracy required, and its implementation on FPGAs are unprecedented at the time of this reporting for an onboard processor for flight applications.

  6. KaRIn on SWOT: modeling and simulation of near-nadir Ka-band interferometric SAR images

    NASA Astrophysics Data System (ADS)

    Fjørtoft, Roger; Koudogbo, Fifamè; Duro, Javier; Ruiz, Christian; Gaudin, Jean-Marc; Mallet, Alain; Pourthie, Nadine; Lion, Christine; Ordoqui, Patrick; Arnaud, Alain

    2010-10-01

    The principal instrument of the wide-swath altimetry mission SWOT is KaRIn, a Ka-band interferometric SAR system operating on near-nadir swaths on both sides of the satellite track. Due to the short wavelength and particular observation geometry, there are very limited reports on the backscattering from natural surfaces. Simulators that cover both radiometric and geometric aspects are therefore developed in the framework of the CNES phase 0 and A studies of SWOT. This article presents the modeling and simulation approaches that have been adopted, and shows some preliminary simulation results.

  7. KaRIN: an Instrument for Measuring High-Resolution Sea-Surface Topography and Fresh Water Extent, Stage, and Slope

    NASA Astrophysics Data System (ADS)

    Rodriguez, E.; Moller, D.; Enjolras, V.

    2006-12-01

    Traditional nadir profiling altimeters, such as Topex, Jason, or IceSat, are incaple of fully sampling the space- time signatures of both ocean mesoscale and submesoscale phenomena and changes in river discharge. To overcome this limitation, we present an instrument concept, the Ka-band Radar Interferometer (KaRIN), which is able to provide the appropriate space-time sampling to sample these phenomena with a height and slope accuracy suitable to resolve topographic signatures for both ocean and land hydrology applications. Although ocean and hydrlogic applications are quite different, the required sampling characteristics are similar. Both applications require global coverage up to high latitudes (78deg). Measurement of ocean mesoscale and submesoscale phenomena requires a temporal revisit time on the order of 10 days and a height accuracy of about 2cm over a spatial scale of 2km. The sampling of river discharge requires an approximately weekly revisit time, an ability to image water bodies (to determine extent) with a spatial resolution of 100m, a height accuracy better than 10cm and a slope accuracy of 1cm/1km, after averaging over a river area equivalent to 1km x 1km. The similarity in measurement requirements allows for the possibility of meeting both ocean and hydrology requirements with a single instrument. The KaRIN instrument builds on the interferometric SAR concept demonstrated by the NASA Shuttle Radar Topography Mission (SRTM), and the Wide-Swath Ocean Altimeter concept, which was studied by NASA as a potential complement to the Ocean Surface Topography Mission (OSTM). Two major modifications are made to these systems to achieve the desired performance: the spatial sampling requirement implies that full synthetic aperture must be used. Second, achieving the desired height and slope accuracy with a realizable spaceborne instrument requires using a Ka-band (0.8 cm wavelength) radar at near nadir incidence. To validate the science performance of the

  8. Response to commentaries by Karin Rolanda Jongsma and Suzanne van de Vathorst, and Oliver Hallich.

    PubMed

    Buller, Thomas

    2015-08-01

    The authors of the two commentaries raise some interesting and important objections to my paper, 'Advance Consent, Critical Interests, and Dementia Research'. In my response I try to show that the objections raised can be understood as general objections against advance directives, rather than against research directives in particular. Since my main argument in the paper is that if we accept advance directives for treatment then we should accept them for research, arguments showing that we should not accept advance directives at all are consistent with my point of view. PMID:25887513

  9. 75 FR 76482 - Federal Housing Administration (FHA): FHA Maximum Loan Limits for 2011

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-08

    .../ . FOR FURTHER INFORMATION CONTACT: Karin B. Hill, Director, Office of Single Family Program Development.../. Dated: November 29, 2010. Karin Hill, Director, Office of Single Family Program Development....

  10. KARIN: The Ka-Band Radar Interferometer for the Proposed Surface Water and Ocean Topography (SWOT) Mission

    NASA Technical Reports Server (NTRS)

    Esteban-Fernandez, Daniel; Peral, Eva; McWatters, Dalia; Pollard, Brian; Rodriguez, Ernesto; Hughes, Richard

    2013-01-01

    Over the last two decades, several nadir profiling radar altimeters have provided our first global look at the ocean basin-scale circulation and the ocean mesoscale at wavelengths longer than 100 km. Due to sampling limitations, nadir altimetry is unable to resolve the small wavelength ocean mesoscale and sub-mesoscale that are responsible for the vertical mixing of ocean heat and gases and the dissipation of kinetic energy from large to small scales. The proposed Surface Water and Ocean Topography (SWOT) mission would be a partnership between NASA, CNES (Centre National d'Etudes Spaciales) and the Canadian Space Agency, and would have as one of its main goals the measurement of ocean topography with kilometer-scale spatial resolution and centimeter scale accuracy. In this paper, we provide an overview of all ocean error sources that would contribute to the SWOT mission.

  11. 75 FR 40819 - Reliability Standards Development and NERC and Regional Entity Enforcement; Notice Soliciting...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-14

    ... Technical Conference, 75 FR 36,385 (June 18, 2010). Anyone with questions pertaining to the technical conference or this notice should contact either Karin Larson at 202-502-8236, Karin.Larson@ferc.gov...

  12. 75 FR 3240 - Center for Scientific Review; Notice of Closed Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-20

    ...: Karin F. Helmers, PhD, Scientific Review Officer, Center for Scientific Review, National Institutes of... Institutes of Health, 6701 Rockledge Drive, Bethesda, MD 20892, (Virtual Meeting.) Contact Person: Karin...

  13. Antipsychotics Don't Ease Delirium in Hospitalized Patients

    MedlinePlus

    ... a patient with delirium," said lead researcher Dr. Karin Neufeld, clinical director of psychiatry at Johns Hopkins ... obvious, but they are important," he added. SOURCES: Karin Neufeld, M.D., M.P.H., clinical director, ...

  14. The Surface Water and Ocean Topography Mission (SWOT): the Ka-band Radar Interferometer (KaRIn) for water level measurements at all scales

    NASA Astrophysics Data System (ADS)

    Rodriguez, Ernesto; Esteban-Fernandez, Daniel

    2010-10-01

    The Surface Water and Ocean Topography (SWOT) mission will study ocean mesoscale and submesoscale phenomena and provide an inventory of storage change and discharge for fresh water bodies and rivers. In this paper, we examine the combination of measurements that will be used by SWOT to achieve a globally consistent data set. We introduce a new channel in the SWOT measurement that combines data transmitted by the interferometer antennas and received by the radiometer antenna allows the closing of the SWOT nadir coverage gap. This new mode also allows for improved calibration between the nadir altimeter and the interferometer, resulting in consistent range measurements. Consistency in the phase measurements is achieved using a mixture of cross-over calibration combined with optimal estimation of system error drift.

  15. Photometric Observation of Young Asteroid Family in 2006-2010 at Maidanak Observatory, Uzbekistan

    NASA Astrophysics Data System (ADS)

    Yoshida, F.; Nozawa, Y.; Ito, T.; Takahashi, S.; Okita, K.; Ibrahimov, M.; Ehgamberdiev, S.; Marshalkina, A.; Karimov, R.; Burhonov, O.; Tillayev, Y.; Hafizov, B.; Yanagisawa, T.; Kurosaki, H.; Yoshikawa, M.; Urakawa, S.; Ohtani, H.

    2012-05-01

    We observed 43 young family asteroids (Karin, Iannini, Veritas) and 7 old family asteroids (Koronis, Themis) at Maidanak Observatory, then determined their rotation period, lightcurve amplitude, B-V, V-R, V-I colors.

  16. Reflectance Spectra of Members of Very Young Asteroid Families

    NASA Astrophysics Data System (ADS)

    Chapman, C. R.; Enke, B.; Merline, W. J.; Nesvorný, D.; Tamblyn, P.; Young, E. F.

    2009-03-01

    We present SpeX infrared spectra for members of the dynamically young Datura, Iannini, Karin, and Veritas asteroid families (plus Koronis and Themis family controls). S-types are space-weathered on timescales of a few million years.

  17. 75 FR 35021 - Reliability Standards Development and NERC and Regional Entity Enforcement; Notice of Technical...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-21

    ... conference may be directed to: Karin L. Larson, Office of the General Counsel--Energy Markets, Federal Energy Regulatory Commission, 888 First Street, NE., Washington, DC 20426, (202) 502-8236,...

  18. Probing Asteroid Families for Evidence of Ultraviolet Space Weathering Effects

    NASA Astrophysics Data System (ADS)

    Vilas, Faith

    2005-07-01

    We propose six HST orbits to obtain UV reflectance spectra covering 200-460 nm of two Vesta asteroid family members, asteroid 832 Karin, and two Karin family members. These observations extend work done under a Cycle 13 AR grant, where we analyzed all of the existing IUE and HST S-class asteroids in the MAST database to investigate the effects of space weathering at UV wavelengths. Our hypothesis is that the manifestation of space weathering at UV wavelengths is a spectral bluing, in contrast with a spectral reddening at visible-NIR wavelengths, and that UV wavelengths can be more sensitive to relatively small amounts of weathering than longer wavelengths. The proposed observations will address two objectives: {1} Measure the UV-visible spectra of 832 Karin and two members of the young Karin family {absolute age of 5.8 My}, in order to determine whether intermediate space weathering is observable in objects likely pristine when they originated from the interior of Karin's pa rent body. {2} Measure the UV-visible spectra of two members of the Vesta family to compare with our analysis of IUE Vesta spectra. These observations will probe Vesta's interior, and test our hypothesis by contrasting the apparent amount of alteration on the surfaces of Vestoids with excavated material on Vesta.

  19. 78 FR 45541 - Center for Scientific Review ;Notice of Closed Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-29

    ... Committee: Center for Scientific Review Special Emphasis Panel; OppNet RFA: Culture, Health and Wellbeing... HUMAN SERVICES National Institutes of Health Center for Scientific Review ;Notice of Closed Meeting... Call). Contact Person: Karin F Helmers, Ph.D., Scientific Review Officer, Center for Scientific...

  20. Getting It Done: Leading Academic Success in Unexpected Schools

    ERIC Educational Resources Information Center

    Chenoweth, Karin; Theokas, Christina

    2011-01-01

    "Getting It Done" describes in clear and helpful detail what leaders of successful high-poverty and high-minority schools have done to promote and sustain student achievement. It follows two celebrated books by Karin Chenoweth: "It's Being Done," which established that the work of educating all children is possible, and "How It's Being Done,"…

  1. Astronaut James Wetherbee briefed on use of Sky Genie

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Astronaut James D. Wetherbee, STS-63 mission commander, is briefed on the use of Sky Genie device by Karin L. Porter. The device would aid in emergency egress operations aboard a troubled Space Shuttle. Porter, an employee of Rockwell International, helps train astronauts in egress procedures at JSC's Shuttle mockup and integration laboratory.

  2. Psycholinguistics and Foreign Language Learning. Papers from a Conference (Stockholm, Sweden and Abo, Finland, October 25-26, 1982). Meddelanden fran Stiftelsens for Abo Akademi Forskningsinstitut Nr.86.

    ERIC Educational Resources Information Center

    Ringbom, Hakan, Ed.

    At irregular intervals, beginning in 1977, Swedish-Finnish conferences on contrastive and applied linguistics have been arranged in Stockholm and Turko/Abo. This volume presents most of the papers given at the 1982 conference. Papers include: "Free Recall of Mixed Language Lists. Error Patterns in Bilingual Memory" (Karin Aronsson, Anja Metsola,…

  3. "Oya?"--O, Ja! Reading "Jugendliteratur" in the German Classroom.

    ERIC Educational Resources Information Center

    Moffit, Gisela

    1998-01-01

    Makes a plea for reading authentic "Jugendliteratur" in the foreign-language classroom. Focuses on the reasons for inclusions of this literature, discusses some of the reasons for its omission, and offers solutions to the problems perceived. Strategies for reading whole texts are shared and applied to the reading of "Oya" by Karin Konig, Hanne…

  4. How It's Being Done: Urgent Lessons from Unexpected Schools

    ERIC Educational Resources Information Center

    Chenoweth, Karin

    2009-01-01

    "How It's Being Done" offers much-needed help to educators, providing detailed accounts of the ways in which unexpected schools--those with high-poverty and high-minority student populations--have dramatically boosted student achievement and diminished (and often eliminated) achievement gaps. "How It"s Being Done" builds on Karin Chenoweth's…

  5. Persistent Discourses in Physics Education: Gender Neutrality and the Gendering of Competence

    ERIC Educational Resources Information Center

    Gonsalves, Allison

    2014-01-01

    In her article, Karin Due presents us with a contradiction in physics: the construction of physics as a symbolically masculine discipline alongside a simultaneous discourse of the "gender-neutrality" of the discipline. Due's article makes an important contribution to the study of the gendering of physics practices, particularly in…

  6. 77 FR 39499 - Center For Scientific Review; Notice of Closed Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-03

    ... HUMAN SERVICES National Institutes of Health Center For Scientific Review; Notice of Closed Meetings... Committee: Center for Scientific Review Special Emphasis Panel Revisions on the Protections for Human...: Karin F. Helmers, Ph.D., Scientific Review Officer, Center for Scientific Review, National Institutes...

  7. Astronaut Eileen Collins is briefed on use of Sky Genie

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Astronaut Eileen M. Collins, STS-63 mission pilot, is briefed on the use of Sky Genie device by Karin L. Porter. The device would aid in emergency egress operations aboard a troubled Space Shuttle. Porter, an employee of Rockwell International, helps train astronauts in egress procedures at JSC's Shuttle mockup and integration laboratory.

  8. The Role of Shared Knowledge in Science: The Failure of the Constructivist Programme in the Sociology of Science.

    ERIC Educational Resources Information Center

    Freudenthal, Gad

    1984-01-01

    Discusses various aspects of contructivism, focusing on the work of Karin Knorr-Cetina. Indicates that an internal critique of Knorr's arguments for the relativist program in the sociology highlights the role of shared knowledge in science and that Knorr's analysis produces new insights concerning the necessity and nature of scientific consensus.…

  9. Varia. Working Papers in Linguistics No. 47.

    ERIC Educational Resources Information Center

    Dowty, David, Ed.; And Others

    1995-01-01

    Papers in phonology, psycholinguistics, and syntax include: "Discriminating between Syntactic and Semantic Processing: Evidence from Event-Related Potentials" (Kim Ainsworth-Darnell); "The Syntactic Structure of Chinese Formal Focus" (Qian Gao); "Employing a Multimodal Logic in an Approach to German Pronoun Fronting" (Karin Golde); "The…

  10. 75 FR 66038 - Planning Resource Adequacy Assessment Reliability Standard

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-27

    ...-6652 or toll-free at 1-866-208-3676. FOR FURTHER INFORMATION CONTACT: Karin L. Larson (Legal Information), Office of the General Counsel, Federal Energy Regulatory Commission, 888 First Street, NE., Washington, DC 20426, (202) 502-8236. Scott Sells (Technical Information), Office of Electric...

  11. Astronaut C. Michael Foale is briefed on use of Sky Genie

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Astronaut C. Michael Foale, STS-63 mission specialist, is briefed on the use of Sky Genie device by Karin L. Porter. The device would aid in emergency egress operations aboard a troubled Space Shuttle. Porter, an employee of Rockwell International, helps train astronauts in egress procedures at JSC's Shuttle mockup and integration laboratory.

  12. Epistemic Practices and Object Relations in Professional Work

    ERIC Educational Resources Information Center

    Nerland, Monika; Jensen, Karen

    2012-01-01

    Professional practice is embedded in complex dynamics of knowledge that are present within, but reach beyond, local work. Knowledge is generated from a manifold of sources, and further developed and circulated in professional communities as practitioners are confronted with non-routine problems. Drawing on the work of Karin Knorr Cetina and her…

  13. Space weathering: from laboratory to observations .

    NASA Astrophysics Data System (ADS)

    Brunetto, R.; Orofino, V.; Strazzulla, G.

    An ongoing research program in our laboratories is focusing on the effects of laser ablation and ion irradiation on silicates, meteorites, and ices, as a simulation of space weathering on Solar System minor bodies (asteroids, Trans-Neptunian Objects, etc.). Spectroscopic results show a general reddening and darkening of the various materials in the 0.3-2.7 mu m range. Laboratory data are then compared with observations, through spectral characterization and scattering models, indicating that space weathering is a very efficient process both in the inner and outer Solar System. In particular, we demonstrated that the majority of TNOs and Centaurs can develop an organic crust mantle produced after irradiation of simple C-bearing molecules. Another relevant result is that the exposure to surface space weathering of asteroid 832 Karin, as calculated from our experiments and models, is in agreement with a dynamical time-scale, i.e. the age of the corresponding Karin family.

  14. Perspectives on Positioning, Interaction, and Learning in Small-Group Discussion: Possibilities for Extending the Analytic Lens

    ERIC Educational Resources Information Center

    Kittleson, Julie M.; Wilson, Rachel E.

    2014-01-01

    In this forum piece, we respond to Karin Due's study of social dynamics in groups of students in physics class and gender issues that play out in this context. We discuss two threads that appear in Due's paper: one pertains to patterns of talk within groups and how these patterns open up possibilities for learning, the other pertains to…

  15. ASBMB Journal Club - Office of Cancer Clinical Proteomics Research

    Cancer.gov

    On Wednesday, November 12, 2014 from 2:00 PM to 3:00 PM EST, Daniel Liebler, PhD (Vanderbilt University) and Karin Rodland, PhD (Pacific Northwestern National Laboratory) and Ruedi Aebersold, PhD (Swiss Federal Institute of Technology) will share their research insight as part of the ASBMB Journal Club.  Both Doctors Liebler and Rodland are Principal Investigators in the NCI’s Clinical Proteomic Tumor Analysis Consortium.

  16. Physical properties of asteroid dust bands and their sources

    NASA Astrophysics Data System (ADS)

    Nesvorný, David; Vokrouhlický, David; Bottke, William F.; Sykes, Mark

    2006-03-01

    Disruptive collisions in the main belt can liberate fragments from parent bodies ranging in size from several micrometers to tens of kilometers in diameter. These debris bodies group at initially similar orbital locations. Most asteroid-sized fragments remain at these locations and are presently observed as asteroid families. Small debris particles are quickly removed by Poynting-Robertson drag or comminution but their populations are replenished in the source locations by collisional cascade. Observations from the Infrared Astronomical Satellite (IRAS) showed that particles from particular families have thermal radiation signatures that appear as band pairs of infrared emission at roughly constant latitudes both above and below the Solar System plane. Here we apply a new physical model capable of linking the IRAS dust bands to families with characteristic inclinations. We use our results to constrain the physical properties of IRAS dust bands and their source families. Our results indicate that two prominent IRAS bands at inclinations ≈2.1° and ≈9.3° are byproducts of recent asteroid disruption events. The former is associated with a disruption of a ≈30-km asteroid occurring 5.8 Myr ago; this event gave birth to the Karin family. The latter came from the breakup of a large >100-km-diameter asteroid 8.3 Myr ago that produced the Veritas family. Using an N-body code, we tracked the dynamical evolution of ≈10 6 particles, 1 μm to 1 cm in diameter, from both families. We then used these results in a Monte Carlo code to determine how small particles from each population undergo collisional evolution. By computing the thermal emission of particles, we were able to compare our results with IRAS observations. Our best-fit model results suggest the Karin and Veritas family particles contribute by 5-9% in 10-60-μm wavelengths to the zodiacal cloud's brightness within 50° latitudes around the ecliptic, and by 9-15% within 10° latitudes. The high brightness of

  17. The resolution of inflammation: anti-inflammatory roles for NF-kappaB.

    PubMed

    Lawrence, Toby; Fong, Carol

    2010-04-01

    Inflammation is a salutary response to insult or injury that normally resolves with no detriment to the host. While the mechanisms and mediators that regulate the onset of inflammation have been well characterized we still know relatively little about the endogenous mechanisms that terminate the inflammatory response (Lawrence and Gilroy, 2007). Nuclear factor (NF)-kappaB is a generic term for a family of ubiquitous transcription factors with diverse physiological functions (Bonizzi and Karin, 2004; Caamano and Hunter, 2002). NF-kappaB transcription factors are formed by dimerisation of Rel proteins; RelA (p65), c-Rel, RelB, p50, p52. Various hetero or homodimers of Rel proteins can be formed in a tissue and stimulus specific manner, genetic evidence suggests these transcription factors have a critical role in cell survival and pro-inflammatory signalling pathways, which have been extensively reviewed elsewhere (Bonizzi and Karin, 2004; Caamano and Hunter, 2002). The critical role for NF-kappaB in pro-inflammatory gene expression has led to an enormous effort to develop inhibitors of this pathway for the treatment of chronic inflammation (Karin et al., 2004). However, recent research using modern molecular genetic approaches has revealed new anti-inflammatory roles for NF-kappaB that may have important implications for targeting this pathway in the treatment of inflammatory diseases. In this review we will discuss the emerging role of NF-kappaB in the resolution of inflammation and some of the potential mechanisms attributed to this function. PMID:20026420

  18. The Surface Water and Ocean Topography Mission: a mission concept to study the world's oceans and fresh water

    NASA Astrophysics Data System (ADS)

    Vaze, Parag; Albuys, Vincent; Esteban-Fernandez, Daniel; Lafon, Thierry; Lambin, Juliette; Mallet, Alain; Rodriguez, Ernesto

    2010-10-01

    The Surface Water and Ocean Topography (SWOT) is a planned satellite mission to study the world's oceans and terrestrial surface water bodies. The SWOT mission concept has been proposed jointly by the global Hydrology and Oceanography science communities to make the first global survey of the Earth's surface water, observe the fine details of the ocean's surface topography, and measure how water bodies change over time. SWOT was one of 15 missions listed in the 2007 National Research Council's Decadal Survey for Earth science as a mission that NASA should implement in the incoming decade. This mission concept builds upon the heritage of prior missions and technologies such as Topex/Poseidon, Jason-1/ 2, the Shuttle Radar Topography Mission (SRTM), and the initial development of the Wide Swatch Ocean Altimeter intended for the Ocean Surface Topography Mission/Jason-2. The key measurement capability for SWOT is provided by a Ka-band synthetic aperture radar interferometer (KaRIn). With an orbit altitude of 970 km, the KaRIn instrument provides a high-resolution swath width of 120 km enabling global coverage (~90%) of the world's ocean's and fresh water bodies. The KaRIn measurement is being designed to provide a spatial resolution of 1 km for the oceans (after on-board processing), and 100 m for land water, both at centimetric accuracy. An additional instrument suite similar to the Jason series will complement KaRIn: a Ku-band nadir altimeter, a Microwave Radiometer and Precision Orbit Determination (POD) systems. To enable this challenging measurement performance, the SWOT mission concept is designed to overcome several challenges, such as very high raw data rate (320 Mbps), large on-board data volumes, high power demand, stringent pointing and stability requirements, and ground data processing systems, to produce meaningful science data products to our user community. The SWOT mission concept is being developed as a cooperative effort between NASA and CNES. This

  19. Koronis binaries and the role of families in binary frequency

    NASA Astrophysics Data System (ADS)

    Merline, W. J.; Tamblyn, P. M.; Nesvorny, D.; Durda, D. D.; Chapman, C. R.; Dumas, C.; Owen, W. M.; Storrs, A. D.; Close, L. M.; Menard, F.

    2005-08-01

    Our ground-based adaptive optics observations of many larger Koronis members show no binaries, while our HST survey of smaller Koronis members (say smaller than 10 km) shows a surprising 20% binary fraction. Admittedly, this is from small-number statistics, but we nonetheless calculate a 99% confidence that the binary fraction is different from the 2% we observe among the larger (over 20km) main belt asteroids as a whole. In addition, we estimate that among the two young families (Karin and Veritas) that we surveyed for binaries in our HST Cy 13 program, the binary fraction appears to be less than 5%. These young families both have significantly smaller progenitors than the Koronis family. We have speculated that progenitor size may be a more important factor than age in determination of binary frequency. But here we suggest an alternative idea, that the binary fraction may be more related to what part of the family's size distribution is sampled. Our HST program targeted objects of the same physical sizes, but was clearly sampling further down the size distribution (to smaller sizes, relative to the largest remnant) in the Koronis sample than was the case for Karin and Veritas, which we sampled mostly at the larger sizes, relatively. Our SPH collision models are estimating the typical size-frequency distributions to be expected from catastrophic and non-catastrophic impact events. But they are also appear to be showing that the largest fragments from a collision are less likely to form binaries (as co-orbiting ejecta pairs) than are the smaller fragments. Thus, it might be expected that we would have found fewer binaries among Karin and Veritas than among the Koronis sample. In fact, models of the Karin breakup show binary formation to be unlikely in the size range measured. It some might be tempted to tie the small end of the main-belt binary population to the binaries seen among the NEAs (also small and also showing about 20% fraction), given the 20% fraction

  20. Koronis asteroid dust within Antarctic ice

    NASA Astrophysics Data System (ADS)

    Genge, Matthew J.

    2008-09-01

    Here I report the first discovery of large numbers of ordinarychondrite-derived micro-meteorites (MMs) recovered fromAntarctic ice. Ordinary chondrite-derived MMs comprise70% coarse-grained igneous particles and are identified on thebasis of their distribution of petrologic types, accessory mineralogy,and minor element compositions, all of which are very similarto those of millimeter-sized igneous objects known as chondrules,from ordinary chondrites, and largely distinct from those ofother meteorite groups. The majority of ordinary chondrite-derivedMMs are unequilibrated materials; however, 15% are equilibrated,indicating parent body metamorphism, and have compositions consistentwith both H (high iron) and L (low iron) chondrites. The totalabundance of ordinary chondrite-derived MMs of ~18% issimilar to predictions by numerical calculations for the abundanceof dust generated by the recent breakup of the Karin group asteroidsof the Koronis asteroid family, suggesting that these asteroidsare the main source of the particles. These MMs represent thefirst to be associated with a known asteroid and imply thatthe Karin group progenitor asteroid was a rubble-pile asteroidthat sampled different depths within the original internallymetamorphosed Koronis parent body.

  1. Persistent discourses in physics education: gender neutrality and the gendering of competence

    NASA Astrophysics Data System (ADS)

    Gonsalves, Allison

    2014-06-01

    In her article, Karin Due presents us with a contradiction in physics: the construction of physics as a symbolically masculine discipline alongside a simultaneous discourse of the "gender-neutrality" of the discipline. Due's article makes an important contribution to the study of the gendering of physics practices, particularly in group dynamics, and how this serves to simultaneously reinforce the two competing discourses of physics as a masculine discipline, and the discourse of physics as a gender neutral discipline. Due also suggests that an implication of this contradiction is a limited number of available positions for girls in physics compared to those available to boys. I wish to take up this observation and discuss how available positions for boys and girls in physics are related quite closely to two other concepts discussed in Due's article: competence and recognition.

  2. Origin of the Near-Ecliptic Circumsolar Dust Band

    NASA Astrophysics Data System (ADS)

    Nesvorný, David; Bottke, William F.; Vokrouhlický, David; Sykes, Mark; Lien, David J.; Stansberry, John

    2008-06-01

    The zodiacal dust bands are bright infrared (IR) strips produced by thermal emission from circumsolar rings of particles. Two of the three principal dust bands, known as β and γ, were previously linked to the recent asteroid collisions that produced groups of fragments, so-called asteroid families, near the orbits of (832) Karin and (490) Veritas. The origin of the third, near-ecliptic α band has been unknown until now. Here we report the discovery of a recent breakup of a >20 km diameter asteroid near α's originally suspected source location in the Themis family. Numerical modeling and observations of the α-band thermal emission from the Spitzer Space Telescope indicate that the discovered breakup is the source of α-band particles. The recent formation of all principal dust bands implies a significant time variability of the circumstellar debris disks.

  3. Perspectives on positioning, interaction, and learning in small-group discussion: possibilities for extending the analytic lens

    NASA Astrophysics Data System (ADS)

    Kittleson, Julie M.; Wilson, Rachel E.

    2014-06-01

    In this forum piece, we respond to Karin Due's study of social dynamics in groups of students in physics class and gender issues that play out in this context. We discuss two threads that appear in Due's paper: one pertains to patterns of talk within groups and how these patterns open up possibilities for learning, the other pertains to ways in which gender is constructed within groups and made visible via discourse. Our comments are intended to provide alternative ways of thinking about such issues. We hope to provide insight into how to deepen analyses of group dynamics and gender because research in both areas is important in terms of understanding how social contexts support and/or constrain learning, gender identity, and the like.

  4. Observations of Members of Very Young Asteroid Families

    NASA Astrophysics Data System (ADS)

    Chapman, C. R.; Merline, W. J.; Nesvorny, D.; Tamblyn, P. M.; Young, E. F.

    2005-08-01

    Several asteroid families or clusters have been found [cf. D. Nesvorny et al. 2003, Ap.J. 591:486-497] to have very short dynamical ages. The Veritas family of C-type asteroids, Karin cluster within the S-type Koronis family, and the Iannini cluster (apparently S-type) formed about 8.3, 5.8, and <5 Myr ago, respectively. If one or more kinds of asteroidal processes (e.g. spin evolution, space weathering, devolatilization of near-surface materials, satellite formation and evolution) operate on timescales comparable with or slower than several Myr, then we may expect to observe different physical properties for members of these recently formed families than for older family members. During the first year of our multifaceted observing program, we have used numerous facilities (IRTF/MIRSI, IRTF/SPeX, HST, Spitzer, CTIO 0.9m, KPNO 0.9m and 2.1m, VLT AO, Gemini AO, and Keck AO), during 14 different runs, to obtain about 100 different observational datasets for members of the 3 young families plus numerous additional observations of controls (e.g. Themis family and non-Karin members of the Koronis family). Techniques employed include lightcurve photometry, visible colorimetry, near-IR spectral reflectance, thermal IR, and AO search for satellites. We discuss representative results from these observations. Theoretical synthesis of the data must await a more complete sampling of these family asteroids by the different techniques. This work is being supported primarily by the NASA Planetary Astronomy Program and by the observing facilities listed.

  5. New insights on the Karoo shale gas potential from borehole KZF-1 (Western Cape, South Africa)

    NASA Astrophysics Data System (ADS)

    Campbell, Stuart A.; Götz, Annette E.; Montenari, Michael

    2016-04-01

    A study on world shale reserves conducted by the Energy Information Agency (EIA) in 2013 concluded that there could be as much as 390 Tcf recoverable reserves of shale gas in the southern and south-western parts of the Karoo Basin. This would make it the 8th-largest shale gas resource in the world. However, the true extent and commercial viability is still unknown, due to the lack of exploration drilling and modern 3D seismic. Within the framework of the Karoo Research Initiative (KARIN), two deep boreholes were drilled in the Eastern and Western Cape provinces of South Africa. Here we report on new core material from borehole KZF-1 (Western Cape) which intersected the Permian black shales of the Ecca Group, the Whitehill Formation being the main target formation for future shale gas production. To determine the original source potential for shale gas we investigated the sedimentary environments in which the potential source rocks formed, addressing the research question of how much sedimentary organic matter the shales contained when they originally formed. Palynofacies indicates marginal marine conditions of a stratified basin setting with low marine phytoplankton percentages (acritarchs, prasinophytes), good AOM preservation, high terrestrial input, and a high spores:bisaccates ratio (kerogen type III). Stratigraphically, a deepening-upward trend is observed. Laterally, the basin configuration seems to be much more complex than previously assumed. Furthermore, palynological data confirms the correlation of marine black shales of the Prince Albert and Whitehill formations in the southern and south-western parts of the Karoo Basin with the terrestrial coals of the Vryheid Formation in the north-eastern part of the basin. TOC values (1-6%) classify the Karoo black shales as promising shale gas resources, especially with regard to the high thermal maturity (Ro >3). The recently drilled deep boreholes in the southern and south-western Karoo Basin, the first since the

  6. Seine estuary modelling and AirSWOT measurements validation

    NASA Astrophysics Data System (ADS)

    Chevalier, Laetitia; Lyard, Florent; Laignel, Benoit

    2013-04-01

    In the context of global climate change, knowing water fluxes and storage, from the global scale to the local scale, is a crucial issue. The future satellite SWOT (Surface Water and Ocean Topography) mission, dedicated to the surface water observation, is proposed to meet this challenge. SWOT main payload will be a Ka-band Radar Interferometer (KaRIn). To validate this new kind of measurements, preparatory airborne campaigns (called AirSWOT) are currently being designed. AirSWOT will carry an interferometer similar to Karin: Kaspar-Ka-band SWOT Phenomenology Airborne Radar. Some campaigns are planned in France in 2014. During these campaigns, the plane will fly over the Seine River basin, especially to observe its estuary, the upstream river main channel (to quantify river-aquifer exchange) and some wetlands. The present work objective is to validate the ability of AirSWOT and SWOT, using a Seine estuary hydrodynamic modelling. In this context, field measurements will be collected by different teams such as GIP (Public Interest Group) Seine Aval, the GPMR (Rouen Seaport), SHOM (Hydrographic and Oceanographic Service of the Navy), the IFREMER (French Research Institute for Sea Exploitation), Mercator-Ocean, LEGOS (Laboratory of Space Study in Geophysics and Oceanography), ADES (Data Access Groundwater) ... . These datasets will be used first to validate locally AirSWOT measurements, and then to improve a hydrodynamic simulations (using tidal boundary conditions, river and groundwater inflows ...) for AirSWOT data 2D validation. This modelling will also be used to estimate the benefit of the future SWOT mission for mid-latitude river hydrology. To do this modelling,the TUGOm barotropic model (Toulouse Unstructured Grid Ocean model 2D) is used. Preliminary simulations have been performed by first modelling and then combining to different regions: first the Seine River and its estuarine area and secondly the English Channel. These two simulations h are currently being

  7. Spectro-dynamical asteroid families in the main belt

    NASA Astrophysics Data System (ADS)

    Bus, S.

    2014-07-01

    Spectral observations of collisionally-derived asteroid families continue to provide strong evidence that the surfaces of members from each family are spectrally homogeneous. This apparent homogeneity provides motivation to use new approaches in combining physical observations, such as spectral colors or albedo, with orbital parameters for the identification of family members and interlopers (e.g. [1,2]). The work described here uses the combined Sloan Digital Sky Survey colors (fourth release of the SDSS Moving Object Catalog [3]) and proper orbital elements from the Asteroids-Dynamics Site (AstDyS [4]) for 39,147 asteroids with semimajor axes between 2.1 and 3.2 au to search for ''spectro-dynamical'' families. The analysis is designed to identify groupings of asteroids that form statistically significant peaks in number density compared to the background population for a fixed spectral color distribution. A number of techniques from multivariate analysis are folded together and have been calibrated to accommodate asteroid families of different size, shape, and number density. In the final phase of the analysis, the number density for asteroids within a given spectral range is represented by 2-dimensional contour slices through proper-element space, and a visual inspection is made to confirm the reality of each grouping. Some families show evidence of complex structure that may be indicative of multiple collisional events over the history of the family. An example of this is the Karin family, which is located within the older, much larger Koronis family [5]. While both families are composed of asteroids classified as S-types, there is a significant color difference between the Koronis and Karin asteroids that is used to distinguish between members of the two families. In the same way, the Vesta family appears to be comprised of two distributions of asteroids that are offset in proper-element space and exhibit a statistically significant difference in the shape of

  8. Evaluation of New Fluorescent Lipophosphoramidates for Gene Transfer and Biodistribution Studies after Systemic Administration.

    PubMed

    Belmadi, Nawal; Berchel, Mathieu; Denis, Caroline; Berthe, Wilfried; Sibiril, Yann; Le Gall, Tony; Haelters, Jean-Pierre; Jaffres, Paul-Alain; Montier, Tristan

    2015-01-01

    The objective of lung gene therapy is to reach the respiratory epithelial cells in order to deliver a functional nucleic acid sequence. To improve the synthetic carrier's efficacy, knowledge of their biodistribution and elimination pathways, as well as cellular barriers faced, depending on the administration route, is necessary. Indeed, the in vivo fate guides the adaptation of their chemical structure and formulation to increase their transfection capacity while maintaining their tolerance. With this goal, lipidic fluorescent probes were synthesized and formulated with cationic lipophosphoramidate KLN47 (KLN: Karine Le Ny). We found that such formulations present constant compaction properties and similar transfection results without inducing additional cytotoxicity. Next, biodistribution profiles of pegylated and unpegylated lipoplexes were compared after systemic injection in mice. Pegylation of complexes led to a prolonged circulation in the bloodstream, whereas their in vivo bioluminescent expression profiles were similar. Moreover, systemic administration of pegylated lipoplexes resulted in a transient liver toxicity. These results indicate that these new fluorescent compounds could be added into lipoplexes in small amounts without perturbing the transfection capacities of the formulations. Such additional properties allow exploration of the in vivo biodistribution profiles of synthetic carriers as well as the expression intensity of the reporter gene. PMID:26540038

  9. Scientists Outline Volcanic Ash Risks to Aviation

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2011-01-01

    The ash clouds that belched out of Iceland's Eyjafjallajökull volcano last spring and dispersed over much of Europe, temporarily paralyzing aviation, were vast smoke signal warnings about the hazard that volcanic ash poses for air traffic around the world. At a 15 December news briefing at the AGU Fall Meeting in San Francisco, two experts with the U.S. Geological Survey (USGS) presented an overview of the damage airplanes can sustain from rock fragment- and mineral fragment-laden ash, an update on efforts to mitigate the hazard of ash, and an outline of further measures that are needed to address the problem. Between 1953 and 2009, there were 129 reported encounters of aircraft with volcanic ash clouds, according to a newly released USGS document cited at the briefing. The report, “Encounters of aircraft with volcanic ash clouds: A compilation of known incidents, 1953-2009,” by Marianne Guffanti, Thomas Casadevall, and Karin Budding, indicates that 26 encounters involved significant damage to the airplanes; nine of those incidents resulted in engine shutdown during flight. The report, which does not focus on the effects on airplanes of cumulative exposure to dilute ash and does not include data since 2009, indicates that “ash clouds continue to pose substantial risks to safe and efficient air travel globally.”

  10. FPA helps 33,000 young people get "sexwise".

    PubMed

    1995-01-01

    "Sexwise," an FPA information campaign for teens on sex and relationships, ran March 4-24 in London and Manchester, areas where teenage pregnancy rates are among the highest in England. It was sponsored by the Department of Health in support of "The health of the nation" goal of reducing teenage pregnancies in England by 50% by the year 2000. The average age of first sexual intercourse is 17 years. Although 94% of young people feel their parents should be their primary sources of sex information, they actually receive most of it from their friends and the media. One-eighth of teenage mothers surveyed by FPA and Middlesex University said that they only discussed contraception with their parents after they became pregnant. According to Karin Pappenheim, FPA Head of Publicity, the FPA wants to "enable young people to make informed decisions about whether and when to have sex while giving them the facts they need to avoid unplanned pregnancy and sexually transmitted diseases." Radio advertisements, which were produced by Laing Henry and featured Terry Christian (presenter for "The Word" on channel 4) and LTB (rappers), publicized the "Sexwise" helpline. Calls were free and confidential. Free copies of the FPA booklet, "Sexuality," were available upon request. Ads also appeared in "Just 17" and "Big," and on posters in Manchester pubs, clubs, and discos. PMID:12319464

  11. [The "top ten" of Finnish medicine].

    PubMed

    Leikola, A

    1998-01-01

    In the early 1980s the Wellcome Institute was planning a biographical dictionary on the world's most eminent physicians. The quota reserved for Finland was ten names, and having been asked by Dr. Karin Johannisson, Uppsala, to participate in the project, I undertook the task of choosing them and providing a short biography of each. For this, I asked the advice of ten experts on the history of Finnish medicine, and a "top ten" list was then compiled. The list extended from Johan Haartman, "the father of Finnish medicine", till the Nobel Prize winner Ragnar Granit and the famous pediatrist Arvo Ylppo, who were still alive in the 1980s. The biographies were sent to the editor of the dictionary, but it seems that the work was never published. As I had saved all my correspondence about the matter, it seemed now, fifteen years afterwards, interesting to publish a short report of the project, including an account of how the "top ten" list had been achieved. PMID:11625413

  12. Extended Solar System Structures Observed by WISE

    NASA Astrophysics Data System (ADS)

    Sykes, Mark V.; Masci, Frank; Cutri, Roc; Walker, Russell; Mainzer, Amy; Bauer, James; Stevenson, Rachel; Tricarico, Pasquale

    2014-11-01

    Extended structures associated with recent asteroid collisions and comets were detected by the Infrared Astronomical Satellite, which conducted the first survey of the thermal emission of the sky in 1983. Twenty-seven years later, the Wide-field Infrared Survey Explorer (WISE), conducted a more sensitive survey of the sky at wavelengths spanning the shorter IRAS bandpasses and detected many of these same structures. Initial identifications include asteroid dust bands associated with collisions giving rise to the Karin and Beagle clusters within the Koronis and Themis asteroid families, respectively. An additional pair of bands is associated with the collision giving rise to the Veritas asteroid family. Comet trails associated with short-period comets have also been observed. Type 2 trails, detected by IRAS and possibly associated with asteroid collisions within the past few thousand years, have yet to be identified. Because WISE is significantly more sensitive than IRAS in the mid-infrared, it has detected some trails extending much further over their orbits and will greatly expand the catalog of trails detected in addition to those observed by IRAS and Spitzer (the latter by targeted observations). WISE and the yet more sensitive NEOCAM survey telescope will provide important insights into the recent collisional history of the asteroid belt and the nature and evolution of comets.

  13. Reversible Avalanches and Criticality in Amorphous Solids

    NASA Astrophysics Data System (ADS)

    Reichhardt, Charles

    2015-03-01

    Despite its importance for basic science and industry, the physical process that causes a solid to change its shape permanently under external deformation is still not well understood. In this paper we use molecular dynamics simulations of amorphous solids under oscillatory shear to study this phenomenon, and show that at a critical strain amplitude, the size of the cooperative atomic motion that allows for a permanent deformation diverges. We compare this non-equilibrium critical behavior to that of a ``front depinning'' transition. This viewpoint, based on fluctuations and statistics, is complementary to the dynamical ``transition to chaos'' which was previously identified at the same strain amplitude. Below this irreversibile-depinning transition, we observe large avalanches which are completely repetitive with each shear strain cycle. This suggests that while avalanches on their own do not cause irreversible deformation, it is likely that the irreversibility transition and the ``depinning-like'' transition are two aspects of the same phenomena. One implication is that the transition could be detected before the onset of irreversible flow by an analysis of the power spectra of avalanches. Work done in collaboration with Ido Regev, Karin Dahmen, John Weber, and Turab Lookman.

  14. Yarkovsky/YORP chronology of asteroid families

    NASA Astrophysics Data System (ADS)

    Vokrouhlický, D.; Brož, M.; Bottke, W. F.; Nesvorný, D.; Morbidelli, A.

    2006-05-01

    Asteroid families are the byproducts of catastrophic collisions whose fragments form clusters in proper semimajor axis, eccentricity, and inclination space. Although many families have been observed in the main asteroid belt, only two very young families, Karin and Veritas, have well-determined ages. The ages of other families are needed, however, if we hope to infer information about their ejection velocity fields, space weathering processes, etc. In this paper, we developed a method that allows us to estimate the ages of moderately young asteroid families (approximately in between 0.1 and 1 Gyr). We apply it to four suitable cases—Erigone, Massalia, Merxia, and Astrid—and derive their likely ages and approximate ejection velocity fields. We find that Erigone and Merxia were produced by large catastrophic disruption events (i.e., parent body ⩾100 km) that occurred approximately 280 and 330 Myr ago, respectively. The Massalia family was likely produced by a cratering event on Asteroid (20) Massalia less than 200 Myr ago. Finally, the Astrid family, which was produced by the disruption of a 60-70 km asteroid, is 100-200 Myr old, though there is considerable uncertainty in this result. We estimate that the initial ejection velocities for these families were only a few tens of meters per second, consistent with numerical hydrocode models of asteroid impacts. Our results help to verify that asteroid families are constantly undergoing dynamical orbital evolution from thermal (Yarkovsky) forces and spin vector evolution from thermal (YORP) torques.

  15. Asteroid family classification from very large catalogues

    NASA Astrophysics Data System (ADS)

    Lemaitre, Anne

    2005-02-01

    The paper presents a review of the recent contributions and open questions concerning the families of asteroids. Due to the availability of very large catalogues (synthetic and analytical proper elements of the asteroids and large observational surveys of their spectra) and to the introduction of non gravitational forces in their determination, the concept of static family has disappeared, to be replaced by this of dynamical families. The proper elements are not constant anymore but are ageing on very long timescales. The size distributions of the populations of asteroids, in and out the families, their ages, the ejection velocities of the fragments after an impact, have been reconsidered by several teams of research, with this new approach. Parallel numerical simulations of collisions and fragmentations of bodies have showed that most of the asteroids are likely rubble piles or agglomerates than monolithic blocks. The methods of classification have been refined and combine, in their newest versions, the dynamics and the observations, working now on 5 dimensional space instead of 3. A series of sub families of the large well-known families have been recently identified, using catalogues with more than 100 000 asteroids (the cluster Karin for example).

  16. Evaluation of New Fluorescent Lipophosphoramidates for Gene Transfer and Biodistribution Studies after Systemic Administration

    PubMed Central

    Belmadi, Nawal; Berchel, Mathieu; Denis, Caroline; Berthe, Wilfried; Sibiril, Yann; Le Gall, Tony; Haelters, Jean-Pierre; Jaffres, Paul-Alain; Montier, Tristan

    2015-01-01

    The objective of lung gene therapy is to reach the respiratory epithelial cells in order to deliver a functional nucleic acid sequence. To improve the synthetic carrier’s efficacy, knowledge of their biodistribution and elimination pathways, as well as cellular barriers faced, depending on the administration route, is necessary. Indeed, the in vivo fate guides the adaptation of their chemical structure and formulation to increase their transfection capacity while maintaining their tolerance. With this goal, lipidic fluorescent probes were synthesized and formulated with cationic lipophosphoramidate KLN47 (KLN: Karine Le Ny). We found that such formulations present constant compaction properties and similar transfection results without inducing additional cytotoxicity. Next, biodistribution profiles of pegylated and unpegylated lipoplexes were compared after systemic injection in mice. Pegylation of complexes led to a prolonged circulation in the bloodstream, whereas their in vivo bioluminescent expression profiles were similar. Moreover, systemic administration of pegylated lipoplexes resulted in a transient liver toxicity. These results indicate that these new fluorescent compounds could be added into lipoplexes in small amounts without perturbing the transfection capacities of the formulations. Such additional properties allow exploration of the in vivo biodistribution profiles of synthetic carriers as well as the expression intensity of the reporter gene. PMID:26540038

  17. Estimating continental hydrology parameters from existing space missions: the need for a dedicated surface water mission

    NASA Astrophysics Data System (ADS)

    Mognard, N. M.; Cazenave, A.; Alsdorf, D. E.; Rodriguez, E.

    2006-12-01

    Different instruments on board Earth observing satellite missions that were designed either for ocean missions or land surface classification have been used to retrieve continental surface hydrology parameters. Conventional altimeter profilers that have been designed for measuring the ocean surface topography provide limited use for surface hydrology. Analysis of conventional altimeter time series over lakes and rivers clearly indicates superimposed seasonal and interannual variabilities while the synergy of altimeter water height estimate with the water extent provided by radiometers is a means of estimating water volume variations. The synergy with the GRACE gravimetry mission, which estimates the variations of the integrated water mass, can provide estimates of the underground water mass variability. However, profiling altimetric methods of measuring water surface elevations and their changes are incapable of capturing the inherent dynamics of all continental surface waters. For example, using a profiling altimeter and a 16-day orbital repeat cycle, like that of Terra, misses about 30 percent of the rivers and 70 percent of the lakes in the global data bases. An international team is proposing the Water Elevation Recovery mission (WatER), a high-resolution, image- based approach with two-dimensional acquisitions of water surface elevations h, dh/dt, and dh/dx required to answer important hydrologic questions. A key technology of the WatER mission is a Ka-band Radar INterferometer (KaRIN) which is a near-nadir viewing, 120 km wideswath based instrument that uses interferometric SAR processing of the returned pulses to yield single-look 5m azimuth and 10m to 70m range resolution, with an elevation accuracy of approximately 50 cm. Polynomial based averaging of heights along the water body increases the height accuracy to about 3 cm. The entire globe is covered twice every 16 days and orbit subcycles allow the average visit to be about half this time at low to mid

  18. WatER: The proposed Water Elevation Recovery satellite mission

    NASA Astrophysics Data System (ADS)

    Alsdorf, D.; Mognard, N.; Rodriguez, E.; Participants, W.

    2005-12-01

    Surface fresh water is essential for life, yet we have surprisingly poor knowledge of the spatial and temporal dynamics of surface water storage and discharge globally. The core mission objective is to describe and understand the continental water cycle and the hydrological processes (e.g., floodplain hydraulics) at work in a river basin. The key question that will be answered by WatER is: "Where is water stored on Earth's land surfaces, and how does this storage vary in space and time?" WatER will facilitate societal needs by (1) improving our understanding of flood hazards; (2) freely providing water volume information to countries who critically rely on rivers that cross political borders; and (3) mapping the variations in water bodies that contribute to disease vectors (e.g., malaria). Conventional altimeter profiles are, without question, incapable of supplying the measurements needed to address scientific and societal questions. WatER will repeatedly measure the spatially distributed water surface elevations (h) of wetlands, rivers, lakes, reservoirs, etc. Successive h measurements yield dh/dt, (t is time), hence a volumetric change in water stored or lost. Individual images of h yield dh/dx (x is distance), hence surface water slope, which is necessary for estimating streamflow. WatER's main instrument is a Ka-band radar interferometer (KaRIN) which is the only technology capable of supplying the required imaging capability of h. KaRIN has a rich heritage based on (1) the many highly successful ocean observing radar altimeters, (2) the Shuttle Radar Topography Mission (SRTM), and (3) the development effort of the Wide Swath Ocean Altimeter (WSOA). The interferometric altimeter is a near-nadir viewing, 120 km wideswath based instrument that uses interferometric SAR processing of the returned pulses to yield single-look 5m azimuth and 10m to 70m range resolution, with an elevation accuracy of approximately 50 cm. Polynomial based averaging of heights along the

  19. NASA Tech Briefs, December 2011

    NASA Technical Reports Server (NTRS)

    2011-01-01

    Topics covered include: 1) SNE Industrial Fieldbus Interface; 2) Composite Thermal Switch; 3) XMOS XC-2 Development Board for Mechanical Control and Data Collection; 4) Receiver Gain Modulation Circuit; 5) NEXUS Scalable and Distributed Next-Generation Avionics Bus for Space Missions; 6) Digital Interface Board to Control Phase and Amplitude of Four Channels; 7) CoNNeCT Baseband Processor Module; 8) Cryogenic 160-GHz MMIC Heterodyne Receiver Module; 9) Ka-Band, Multi-Gigabit-Per-Second Transceiver; 10) All-Solid-State 2.45-to-2.78-THz Source; 11) Onboard Interferometric SAR Processor for the Ka-Band Radar Interferometer (KaRIn); 12) Space Environments Testbed; 13) High-Performance 3D Articulated Robot Display; 14) Athena; 15) In Situ Surface Characterization; 16) Ndarts; 17) Cryo-Etched Black Silicon for Use as Optical Black; 18) Advanced CO2 Removal and Reduction System; 19) Correcting Thermal Deformations in an Active Composite Reflector; 20) Umbilical Deployment Device; 21) Space Mirror Alignment System; 22) Thermionic Power Cell To Harness Heat Energies for Geothermal Applications; 23) Graph Theory Roots of Spatial Operators for Kinematics and Dynamics; 24) Spacesuit Soft Upper Torso Sizing Systems; 25) Radiation Protection Using Single-Wall Carbon Nanotube Derivatives; 26) PMA-PhyloChip DNA Microarray to Elucidate Viable Microbial Community Structure; 27) Lidar Luminance Quantizer; 28) Distributed Capacitive Sensor for Sample Mass Measurement; 29) Base Flow Model Validation; 30) Minimum Landing Error Powered-Descent Guidance for Planetary Missions; 31) Framework for Integrating Science Data Processing Algorithms Into Process Control Systems; 32) Time Synchronization and Distribution Mechanisms for Space Networks; 33) Local Estimators for Spacecraft Formation Flying; 34) Software-Defined Radio for Space-to-Space Communications; 35) Reflective Occultation Mask for Evaluation of Occulter Designs for Planet Finding; and 36) Molecular Adsorber Coating

  20. Size and Age Dependence of Koronis Family Colors

    NASA Astrophysics Data System (ADS)

    Molnar, L. A.

    2011-10-01

    The ancient and massive Koronis family now has four identified subfamilies (asteroid families made by the breakup of fragments of the ancient collision), with ages running from 5.7 to 290 My. This presents unique opportunities to explore space weathering processes, along with dynamical processes such as collisions and binary formation and destruction. Analysis of family members with accurate SDSS measurements shows a correlation of average subfamily color with age that for the first time is highly statistically significant. Yet Thomas et al. (2011) report a size dependence of the colors of the ancient family that demands caution when comparing subfamilies with differing size distributions. Reanalyis of the Thomas et al. data show the reported break near asteroid diameter 5 km is not significant. However, analysis of the much more extensive SDSS data set show a significant break past diameter 2.5 km, with smaller objects systematically bluer. The break is not present in the Karin subfamily (the youngest at 5.7 My), but is already fully developed in the Eriphyla subfamily (only 220 My). The reddening trend with age remains even when comparing only asteroids of similar size, confirming the presence of space weathering phenomena. The meaning of the trend with size is not immediately clear. We consider briefly the strengths and weaknesses of several interpretations of the bluer colors for small objects: 1) those objects receive more jolts from random collisions capable of shaking the regolith and exposing fresh material beneath; 2) those objects receive more jolts from the cycle of fission and recombination driven by YORP; and 3) the lower gravity on those objects retains regolith less well.

  1. Lunar and Planetary Science XXXVI, Part 18

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Topics discussed include: PoDS: A Powder Delivery System for Mars In-Situ Organic, Mineralogic and Isotopic Analysis Instruments Planetary Differentiation of Accreting Planetesimals with 26Al and 60Fe as the Heat Sources Ground-based Observation of Lunar Surface by Lunar VIS/NIR Spectral Imager Mt. Oikeyama Structure: First Impact Structure in Japan? Central Mounds in Martian Impact Craters: Assessment as Possible Perennial Permafrost Mounds (Pingos) A Further Analysis of Potential Photosynthetic Life on Mars New Insight into Valleys-Ocean Boundary on Mars Using 128 Pixels per Degree MOLA Data: Implication for Martian Ocean and Global Climate Change; Recursive Topography Based Surface Age Computations for Mars: New Insight into Surficial Processes That Influenced Craters Distribution as a Step Toward the Formal Proof of Martian Ocean Recession, Timing and Probability; Laser-induced Breakdown Spectroscopy: A New Method for Stand-Off Quantitative Analysis of Samples on Mars; Milk Spring Channels Provide Further Evidence of Oceanic, >1.7-km-Deep Late Devonian Alamo Crater, Southern Nevada; Exploration of Martian Polar Residual Caps from HEND/ODYSSEY Data; Outflow Channels Influencing Martian Climate: Global Circulation Model Simulations with Emplaced Water; Presence of Nonmethane Hydrocarbons on Pluto; Difference in Degree of Space Weathering on the Newborn Asteroid Karin; Circular Collapsed Features Related to the Chaotic Terrain Formation on Mars; A Search for Live (sup 244)Pu in Deep-Sea Sediments: Preliminary Results of Method Development; Some Peculiarities of Quartz, Biotite and Garnet Transformation in Conditions of Step-like Shock Compression of Crystal Slate; Error Analysis of Remotely-Acquired Mossbauer Spectra; Cloud Activity on Titan During the Cassini Mission; Solar Radiation Pressure and Transient Flows on Asteroid Surfaces; Landing Site Characteristics for Europa 1: Topography; and The Crop Circles of Europa.

  2. Multiverse: Increasing Diversity in Earth and Space Science Through Multicultural Education

    NASA Astrophysics Data System (ADS)

    Peticolas, L. M.; Raftery, C. L.; Mendez, B.; Paglierani, R.; Ali, N. A.; Zevin, D.; Frappier, R.; Hauck, K.; Shackelford, R. L., III; Yan, D.; Thrall, L.

    2015-12-01

    Multiverse at the University of California, Berkeley Space Sciences Laboratory provides earth and space science educational opportunities and resources for a variety of audiences, especially for those who are underrepresented in the sciences. By way of carefully crafted space and earth science educational opportunities and resources, we seek to connect with people's sense of wonder and facilitate making personal ties to science and the learning process in order to, ultimately, bring the richness of diversity to science and make science discovery accessible for all. Our audiences include teachers, students, education and outreach professionals, and the public. We partner with NASA, the National Science Foundation, scientists, teachers, science center and museum educators, park interpreters, and others with expertise in reaching particular audiences. With these partners, we develop resources and communities of practice, offer educator workshops, and run events for the public. We will will present on our pedagogical techniques, our metrics for success, and our evaluation findings of our education and outreach projects that help us towards reaching our vision: We envision a world filled with science literate societies capable of thriving with today's technology, while maintaining a sustainable balance with the natural world; a world where people develop and sustain the ability to think critically using observation and evidence and participate authentically in scientific endeavors; a world where people see themselves and their culture within the scientific enterprise, and understand science within the context that we are all under one sky and on one Earth. Photo Caption: Multiverse Team Members at our Space Sciences Laboratory from left to right: Leitha Thrall, Daniel Zevin, Bryan Mendez, Nancy Ali, Igor Ruderman, Laura Peticolas, Ruth Paglierani, Renee Frappier, Rikki Shackelford, Claire Raftery, Karin Hauck, and Darlene Yan.

  3. Well-ordered science and Indian epistemic cultures: toward a polycentered history of science.

    PubMed

    Ganeri, Jonardon

    2013-06-01

    This essay defends the view that "modern science," as with modernity in general, is a polycentered phenomenon, something that appears in different forms at different times and places. It begins with two ideas about the nature of rational scientific inquiry: Karin Knorr Cetina's idea of "epistemic cultures," and Philip Kitcher's idea of science as "a system of public knowledge," such knowledge as would be deemed worthwhile by an ideal conversation among the whole public under conditions of mutual engagement. This account of the nature of scientific practice provides us with a new perspective from which to understand key elements in the philosophical project of Jaina logicians in the seventh, eighth, and ninth centuries C.E. Jaina theory seems exceptionally well targeted onto two of the key constituents in the ideal conversation--the classification of all human points of view and the representation of end states of the deliberative process. The Buddhist theory of the Kathāvatthu contributes to Indian epistemic culture in a different way: by supplying a detailed theory of how human dialogical standpoints can be revised in the ideal conversation, an account of the phenomenon Kitcher labels "tutoring." Thus science in India has its own history, one that should be studied in comparison and contrast with the history of science in Europe. In answer to Joseph Needham, it was not 'modern science' which failed to develop in India or China but rather non-well-ordered science, science as unconstrained by social value and democratic consent. What I argue is that this is not a deficit in the civilisational histories of these countries, but a virtue. PMID:23961693

  4. 2012 Aspen Winter Conference New Paradigms for Low-Dimensional Electronic Materials, February 5-10, 2012

    SciTech Connect

    Moore, Joel; Rabe, Karin; Nayak, Chetan; Troyer, Matthias

    2012-05-01

    Aspen Center for Physics Project Summary DOE Budget Period: 10/1/2011 to 9/30/2012 Contract # DE-SC0007479 New Paradigms for Low-Dimensional Electronic Materials The 2012 Aspen Winter Conference on Condensed Matter Physics was held at the Aspen Center for Physics from February 5 to 10, 2012. Seventy-four participants from seven countries, and several universities and national labs attended the workshop titled, New Paradigms for Low-Dimensional Electronic Materials. There were 34 formal talks, and a number of informal discussions held during the week. Talks covered a variety of topics related to DOE BES priorities, including, for example, advanced photon techniques (Hasan, Abbamonte, Orenstein, Shen, Ghosh) and predictive theoretical modeling of materials properties (Rappe, Pickett, Balents, Zhang, Vanderbilt); the full conference schedule is provided with this report. The week's events included a public lecture (Quantum Matters given by Chetan Nayak from Microsoft Research) and attended by 234 members of the public, and a physics caf© geared for high schoolers that is a discussion with physicists conducted by Kathryn Moler (Stanford University) and Andrew M. Rappe (University of Pennsylvania) and attended by 67 locals and visitors. While there were no published proceedings, some of the talks are posted online and can be Googled. The workshop was organized by Joel Moore (University of California Berkeley), Chetan Nayak (Microsoft Research), Karin Rabe (Rutgers University), and Matthias Troyer (ETH Zurich). Two organizers who did not attend the conference were Gabriel Aeppli (University College London & London Centre for Nanotechnology) and Andrea Cavalleri (Oxford University & Max Planck Hamburg).

  5. Dislocation dynamics, plasticity and avalanche statistics using the phase-field crystal model

    NASA Astrophysics Data System (ADS)

    Angheluta, Luiza

    2013-03-01

    The plastic deformation of stressed crystalline materials is characterized by intermittency and scaling behavior. The sudden strain bursts arise from collective interactions between depinned crystal defects such as dislocations. Recent experiments on sheared nanocrystals provide insights into the connection between the crystal plasticity and the mean field theory of the depinning transition, based on the similar power-law statistics of avalanche events. However, a complete theoretical formulation of this connection is still lacking, as are high quality numerical data. Phase field crystal modelling provides an efficient numerical approach to simulating the dynamics of dislocations in plastic flows at finite temperature. Dislocations are naturally created as defects in a periodic ground state that is being sheared, without any ad hoc creation and annihilation rules. These crystal defects interact and annihilate with one another, generating a collective effect of avalanches in the global plastic strain rate. We examine the statistics of plastic avalanches both at finite and zero temperatures, and find good agreement with the predictions of the mean field interface depinning theory. Moreover, we predict universal scaling forms for the extreme statistics of avalanches and universal relations between the power-law exponents of avalanche duration, size and extreme value. These results account for the observed power-law distribution of the maximum amplitudes in acoustic emission experiments of crystal plasticity, but are also broadly applicable to other systems in the mean-field interface depinning universality class, ranging from magnets to earthquakes. The work reported here was performed in collaboration with: Georgios Tsekenis, Michael LeBlanc, Patrick Y Chan, Jon Dantzig, Karin Dahmen, and Nigel Goldenfeld. The work was supported by the Center for Physics of Geological Processes (Norway) through a post-doctoral grant, the National Science Foundation through grant NSF

  6. Assimilation of wide swath altimetry to improve modelling of the Ob river, in western Siberia

    NASA Astrophysics Data System (ADS)

    Biancamaria, Sylvain; Durand, Michael; Andreadis, Kostas; Bates, Paul; Boone, Aaron; Mognard, Nelly; Rodriguez, Ernesto; Alsdorf, Doug; Lettenmaier, Dennis

    2010-05-01

    Variations in the hydrologic cycle of Arctic rivers, due to climate change, have far-reaching consequences on the global water and carbon cycles, as well as the thermohaline circulation in the ocean. Thus, being able to monitor and accurately model Arctic rivers is a crucial issue for the understanding of changes in the Arctic water cycle. The Ob River is one of the largest rivers in the Arctic, contributing nearly 15% of total freshwater flow into the Arctic Ocean. A model of the lower Ob River has been implemented, by coupling the land surface scheme ISBA (Interactions between Soil, Biosphere and Atmosphere), developed by the CNRM (Centre National de Recherche Meteorologique, France), with the flood inundation model LISFLOOD-FP, developed by the University of Bristol, UK. The scarcity of in situ data in the Ob River basin leads to large errors in the modelling. The forecast error has been assumed to be only due to uncertainties on forcing data (precipitation and air temperature). These errors can be reduced by implementing an Ensemble Kalman smoother for assimilating remotely sensed water levels from satellite altimeters. Data from the future Surface Water and Ocean Topography (SWOT) satellite wide swath altimeter mission will be particularly well adapted to improve the modelling of the Arctic rivers. Every few days, the Ka Radar Interferometer (KaRIN) on board SWOT will provide, for the first time, a global estimate of surface water elevation (with a vertical accuracy of a few cm). The SWOT data have been simulated and assimilated to estimate and quantify their potential to reduce the modelling errors. Preliminary results, using a local Ensemble Kalman Smoother over a 3 day time frame, show that assimilation of SWOT measurements (for a 22-day repeat orbit) leads to a decrease of model prediction errors by a factor of 2.4.

  7. Improving a modelling of the Ob river, in western Siberia, by assimilating wide swath altimetry data

    NASA Astrophysics Data System (ADS)

    Biancamaria, S.; Durand, M. T.; Andreadis, K.; Bates, P. D.; Boone, A.; Mognard, N. M.; Rodriguez, E.; Alsdorf, D. E.; Lettenmaier, D. P.

    2009-12-01

    Arctic rivers are a main source of fresh water to the Arctic Ocean: they represent nearly 10% of the world’s river runoff, whereas the Arctic Ocean represents only 6% of the global ocean surface area. Therefore, changes in their hydrological regime due to global warming could impact not only the thermohaline circulation, but also the carbon cycle (via their floodplains) and the human societies living in high latitudes. Thus, being able to model major arctic rivers and therefore predict how they may respond to global warming is a crucial issue. The upcoming Surface Water and Ocean Topography (SWOT) satellite mission will use a wide swath Ka-band Radar Interferometer (KaRIN) to acquire elevations of terrestrial water surfaces at unprecedented spatial and temporal resolutions, and will observe all continental water bodies between 78°N and 78°S. These measurements will be of broad interest for the hydrology community in general and for hydrologic/hydraulic modelling in particular. SWOT measurements will explicitly characterize the spatial and temporal surface water variations; thus, assimilating SWOT measurements into hydraulic models has great potential for estimating river discharge. This study presents hydrological modelling of the lower Ob river, in Western Siberia. The Ob is the third largest arctic river and contributes to nearly 15% of the total freshwater flow into the Arctic Ocean. The hydrological modelling has been performed by coupling the land surface scheme ISBA (Interactions between Soil, Biosphere and Atmosphere) with the flood inundation model LISFLOOD-FP. Virtual SWOT data have been computed within the context of a synthetic data assimilation experiment. We use the Ensemble Kalman Filter and Smoother to better assess the potential of the SWOT measurements to provide information about river discharge. Preliminary results show that these measurements could decrease the modelling errors almost to 50% for the nominal satellite orbit. Yet, these

  8. Surface Water and Ocean Topography (SWOT) mission

    NASA Astrophysics Data System (ADS)

    Neeck, Steven P.; Lindstrom, Eric J.; Vaze, Parag V.; Fu, Lee-Lueng

    2012-09-01

    The Surface Water Ocean Topography (SWOT) mission was recommended in 2007 by the National Research Council's Decadal Survey, "Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond", for implementation by NASA. The SWOT mission is a partnership between two communities, the physical oceanography and the hydrology, to share high vertical accuracy and high spatial resolution topography data produced by the science payload, principally a Ka-band radar Interferometer (KaRIn). The SWOT payload also includes a precision orbit determination system consisting of GPS and DORIS receivers, a Laser Retro-reflector Assembly (LRA), a Jason-class nadir radar altimeter, and a JASON-class radiometer for tropospheric path delay corrections. The SWOT mission will provide large-scale data sets of ocean sea-surface height resolving scales of 15km and larger, allowing the characterization of ocean mesoscale and submesoscale circulation. The SWOT mission will also provide measurements of water storage changes in terrestrial surface water bodies and estimates of discharge in large (wider than 100m) rivers globally. The SWOT measurements will provide a key complement to other NASA spaceborne global measurements of the water cycle measurements by directly measuring the surface water (lakes, reservoirs, rivers, and wetlands) component of the water cycle. The SWOT mission is an international partnership between NASA and the Centre National d'Etudes Spatiales (CNES). The Canadian Space Agency (CSA) is also expected to contribute to the mission. SWOT is currently nearing entry to Formulation (Phase A). Its launch is targeted for October 2020.

  9. Defining the Flora Family: Reflectance Properties and Age

    NASA Astrophysics Data System (ADS)

    Dykhuis, Melissa J.; Molnar, Lawrence A.; Van Kooten, Samuel J; Greenberg, Richard

    2014-05-01

    The Flora family resides in the densely populated inner main belt, bounded in semimajor axis by the ν6 secular resonance and the Jupiter 3:1 mean motion resonance. The presence of several large families that overlap dynamically with the Floras (e.g. the Vesta, Baptistina, and Nysa-Polana families), and the removal of a significant fraction of Floras via the nearby ν6 resonance have historically complicated the Flora family's distinction in both proper orbital elements and reflectance properties. Here we use orbital information from AstDyS, color information from SDSS, and albedo information from WISE, to obtain the characteristic orbital and reflectance properties of the Floras, by sampling the core of the family in multidimensional phase space. We find the characteristic Flora SDSS colors to be a* = 0.127 ± 0.012 and i-z = -0.038 ± 0.008; the characteristic Flora albedo is pV = 0.295 ± 0.006. These properties allow us to select a high-purity sample of Floras with similar orbital and reflectance properties as required for a detailed dynamical study. We then use the young Karin family, for which we have an age determined via direct backward integration of members' orbits, to calibrate the Yarkovsky drift rates for the Flora family without having to estimate the Floras' material properties. The size-dependent dispersion of the Flora members in semimajor axis (the "V" plot) then yields an age for the family of 940+160-120 My. We discuss the effects on our age estimate of two independent processes that both introduce obliquity variations among the family members on short (My) timescales: 1) the capture of Flora members in spin-orbit resonance, and 2) YORP-driven obliquity variation through YORP cycles. Accounting for these effects does not significantly change the age determination.

  10. Towards a Global Model of the Zodiacal Cloud

    NASA Astrophysics Data System (ADS)

    Espy, Ashley J.; Dermott, S.; Kehoe, T. J.

    2006-09-01

    The Zodiacal Cloud, the debris disk of our own solar system, is still the subject of much debate as to the source of its particles, i.e., what are the relative contributions of asteroidal and cometary material to the cloud. The Zodiacal Cloud consists of a broad, low-frequency background, with superimposed high-frequency dust bands, which are the key to deciphering the relative contributions, since they are known to be asteroidal and associated with specific, young, asteroid families, such as Veritas and Karin. The dust bands only exist outside 2AU due to the secular resonance at 2AU dispersing the fine structure of the dust bands into the background cloud. Thus, the bands represent only the tip-of-the-iceberg of the total asteroidal contribution to the cloud, the extent of which can be found by investigating the dynamical and collisional evolution of the asteroidal family dust particles. Through this evolution of particles, we can model the observed line-of-sight dust band flux profiles, which are scans of ecliptic latitude. The models are based on the dynamics, and compared to filtered observations to constrain the models. The effects of collisions, size-frequency distribution, distribution of cross sectional area with semi-major axis, and the total area are the parameters that are varied and constrained. There is a wealth of archival data, including IRAS, COBE, and MSX, as well as the upcoming Spitzer data, which both overlap and extend over a wide range of ecliptic longitudes, wavebands, and solar elongations. We will use the parameters constrained by the observational data, to extend the model to the background cloud, yielding a global model of the asteroidal contribution to the cloud. We present current models and parameters, as well as a preliminary determination of the asteroidal contribution to the Zodiacal cloud.

  11. Whither Cometary Dust?

    NASA Astrophysics Data System (ADS)

    Lisse, Carey M.

    2010-10-01

    In this paper I will discuss recent findings that have important implications for our understanding of the formation and evolution of primitive solar system dust, including: - Nesvorny et al. (2010), following up on their dynamical analyses of the zodiacal dust bands as sourced by the breakup of the Karin (5Mya) and Veritas (8Mya) asteroid families, argue that over 90% of the interplanetary dust cloud at 1 AU comes from JFC comets with near-circularized, low inclination orbits. This implies that the noted IPD collections of anhydrous and hydrous dust particles are likely to be from Oort cloud and JFC comets, respectively, not from asteroids and comets as thought in the past. Hydrous dust particles from comets like 85P/Wild2 and 9P/Tempel 1 would be consistent with results from the STARDUST and Deep Impact experiments. - Estimates of the dust particle size distributions (PSDs) in the comae of 85P/Wild2 (Green et al. 2004, 2007) and 73P/SW-3 (Sitko et al. 2010, Vaubaillon & Reach 2010) and in the trails of comets (Reach et al. 2007) have broken power law structure, with a plateau enhancement of particles of 1 mm - 1 cm in size. This size is also the size of most chondritic inclusions, and the predicted size range of the "aggregational barrier", where collisions between dust particles become destructive. - Studies of the albedo and polarization properties of cometary dust (Kolokolova et al. 2007) suggest there are 2 major groupings, one with low scattering capability and one with high. While these families could possibly have been explained by systematics in the PSDs of the emitted dust, independent work by Lisse et al. (2008) on the mineralogy of a number of highly dusty comets has shown evidence for one family of comets with highly crystalline dust and another with highly amorphous dust.

  12. On the Nature of the Dust in the Debris Disk around HD 69830

    NASA Astrophysics Data System (ADS)

    Lisse, C. M.; Beichman, C. A.; Bryden, G.; Wyatt, M. C.

    2007-03-01

    We have used the infrared mineralogical model derived from the Spitzer IRS observations of the Deep Impact experiment to study the nature of the dust in the debris found around the K0 V star HD 69830. Using a robust approach to determine the bulk average mineralogical composition of the dust, we show it to be substantially different from that found for comets 9P/Tempel 1 and C/Hale-Bopp 1995 O1 or for the comet-dominated YSO HD 100546. Lacking in carbonaceous and ferrous materials but including small icy grains, the composition of the HD 69830 dust most closely resembles that of a disrupted P- or D-type asteroid. The amount of mass responsible for the observed emission is the equivalent of a 30 km radius, 2500 kg m-3 sphere, while the radiative temperature of the dust implies that the bulk of the observed material is at ~1.0 AU from the central source, coincident with the 2:1 and 5:2 mean motion resonances of the outermost of three Neptune-sized planets detected by Lovis and coworkers. In our solar system, P- and D-type asteroids are both large and numerous in the outer main belt and near Jupiter (e.g., the Hildas and Trojans) and have undergone major disruptive events to produce debris disk-like structures (cf. the Karin and Veritas families 5-8 Myr ago). The short-lived nature of the small and icy dust implies that the disruption occurred within the last year, or that replenishment due to ongoing collisional fragmentation is occurring.

  13. A Census of Asteroid Families Between the J5/2 and J7/3 Resonances

    NASA Astrophysics Data System (ADS)

    Molnar, Lawrence A.; McKay, C. L.

    2010-10-01

    Significant theoretical progress has been made in recent years in modeling the history of the main asteroid belt. In particular, the size-frequency distributions of individual collisions (as a function of impact properties) and the collisional rate (as a function of target size) have been computed. In this work we test these results against observations of asteroids between the J5/2 and J7/3 mean motion resonances. We select this particular zone because 1) the asteroid density is low enough that the extent and membership of all families may be determined unambiguously, 2) the boundary resonances isolate it from families in other zones, and 3) other resonances within the zone have had relatively little effect on the orbits of its families. In particular, we computed synthetic proper elements for 16,111 multiopposition asteroids. We used proper a, e, i and absolute magnitude to identify membership in 19 collisional families. For two of these_the Karin and Koronis clusters_we also used proper longitudes of node and perihelion. The absolute magnitude is important for excluding large interlopers when a Yarkovsky signature clearly identifies them as such. For example, (293) Brasilia is probably not a member of the family previously identified as the Brasilia family. We corrected size-frequency distribution (SFDs) using the local background rates. Finally, we inferred collisional ages (or limits) from evidence of Yarkovsky broadening of the distribution in a. We will present and discuss the empirical collision rate function implied by our results and the SFDs of the families and of the background asteroids. We will also present and discuss the average Sloan Digital Sky Survey colors for each family. This work was funded by a Kuiper endowment and a Calvin Research Fellowship.

  14. Surface heterogeneity of small asteroids

    NASA Astrophysics Data System (ADS)

    Sasaki, Sho

    A rubble pile model of asteroid origin would predict averaged rather homogeneous surface of an asteroid. Previous spacecraft observations (mostly S-type asteroids) did not show large color/albedo variation on the surface. Vesta would be exceptional since HST observation suggested that its surface should be heterogeneous due to the impact excavation of the interior. As for a young asteroid (832) Karin (age being 5Ma), Sasaki et al. (2004) detected variation of infrared spectra which could be explained by the difference of the space weathering degree. They discussed the possibility of the survival of the old surface. However, the variation was not confirmed by later observation (Chapman et al., 2007; Vernazza et al., 2007). Recent observation of a small (550m) asteroid Itokawa by Hayabusa spacecraft revealed that Itokawa is heterogeneous in color and albedo although the overall rocky structure is considered as a rubble pile (Saito et al., 2006). The color difference can be explained by the difference of weathering degree (Ishiguro et al., 2008). The heterogeneity could be explained by mass movement caused by rapid rotation from YORP effect (Scheeres et al., 2007) or seismic shaking (Sasaki, 2006). Probably small silicate asteroids without significant regolith could have heterogeneous in color and albedo. On large asteroids (˜ a few 10km), regolith reaccumulation should have covered the underlying heterogeneity. References: Chapman, C. R. et al (2007) Icarus, 191, 323-329 Ishiguro, M. et al. (2008) MAPS, in press. Saito, J. et al. (2006) Science, 312, 1341-1344 Sasaki, S. (2006) in Spacecraft Reconnaissance of Asteroid and Comet Interiors Sasaki, T. et al (2004) Astrophys. J. 615, L161-L164 Scheeres, D. J. (2007) Icarus 188, 425-429 Vernazza, P. et al. (2007) Icarus 191, 330-336.

  15. High Latitude Dust Bands in the Main Asteroid Belt: Fingerprints of Recent Breakup Events

    NASA Astrophysics Data System (ADS)

    Bottke, William; Durda, Daniel; Jayaraman, Sumita; Lien, David; Nesvorny, David; Reach, William; Stansberry, John; Sykes, Mark; Walker, Russell

    2005-06-01

    The present population of main belt asteroids is largely the result of many past collisions. Ideally, the fragments produced by each impact event could help us understand the collisional processes that shaped the planets during early epochs. Most known asteroid fragment families, however, are very old and thus have undergone significant collisional and dynamical evolution since their formation. This evolution masks the properties of the original collisions. To overcome this problem, our team has used numerical methods and a large database of asteroid orbits to identify several families produced by recent disruption events (<< few tens of My). Not only have these young families undergone little collisional and dynamical evolution, but several of them appear to be the source of dust bands observed by IRAS (e.g., the Karin and Veritas families, both which are < 10 My old; Nesvorny et al. 2002; 2003). Here we propose to use Spitzer observations to investigate the structure of high latitude dust bands in the main asteroid belt. Our results indicate that 2 faint dust bands identified by IRAS, the J/K band at proper inclination i = 12 deg and the M/N band at i = 15 deg, were produced by break up events associated with asteroids (4652) Iannini and (1521) Seinajoki, respectively. Numerical integration work by our team suggests the former family is < 5 My old, making it the youngest family yet discovered in the main belt. Taking advantage of the increased sensitivity of Spitzer over IRAS, we will determine the dust production rate and size distribution in the high latitude bands, relate them to the Zodiacal Cloud, and use this data to constrain main belt collisional processes.

  16. An ensemble-based reanalysis approach for estimating river bathymetry from the upcoming SWOT mission

    NASA Astrophysics Data System (ADS)

    Yoon, Y.; Durand, M. T.; Merry, C. J.; Clark, E.; Alsdorf, D. E.

    2011-12-01

    In spite of the critical role of river discharge in land surface hydrology, global gauging networks are sparse and even have been in decline. Over the past decade, researchers have been trying to better estimate river discharge using remote sensing techniques to complement the existing in-situ gage networks. The upcoming Surface Water and Ocean Topography (SWOT) mission will directly provide simultaneous spatial mapping of inundation area (A) and inland water surface elevation (WSE) data (i.e., river, lakes, wetlands, and reservoirs), both temporally (dh/dt) and spatially (dh/dx), with the Ka-band Radar INterferometer (KaRIN). With these observations, the SWOT mission will provide the measurements of water storage changes in terrestrial surface water bodies. However, because the SWOT will measure WSE, not the true depth to the river bottom, the cross section channel bathymetry will not be fully measured. Thus, estimating bathymetry is important in order to produce accurate estimates of river discharge from the SWOT data. In previous work, a local ensemble Kalman filter (LEnKF) was used to estimate the river bathymetry, given synthetic SWOT observations and WSE predictions by the LISFLOOD-FP hydrodynamic model. However, the accuracy of river bathymetry was highly affected by the severe bias of boundary inflows due to the mathematical relationship for the assimilation. The bias in model is not accounted for the data assimilation. Here, we focus on correcting the forecast bias for the LEnKF scheme to result in the improvement of river bathymetry estimates. To correct the forecast bias and improve the accuracy, we combined the LEnKF scheme with continuity and momentum equations. To evaluate the reanalysis approach, the error of bathymetry was evaluated by comparing with the true value and previous work. In addition, we examined the sensitivity to the bathymetry estimate for estimating the river discharge.

  17. Sestrin2 promotes LKB1-mediated AMPK activation in the ischemic heart

    PubMed Central

    Morrison, Alex; Chen, Li; Wang, Jinli; Zhang, Ming; Yang, Hui; Ma, Yina; Budanov, Andrei; Lee, Jun Hee; Karin, Michael; Li, Ji

    2015-01-01

    The regulation of AMPK in the ischemic heart remains incompletely understood. Recent evidence implicates the role of Sestrin2 in the AMPK signaling pathway, and it is hypothesized that Sestrin2 plays an influential role during myocardial ischemia to promote AMPK activation. Sestrin2 protein was found to be expressed in adult cardiomyocytes and accumulated in the heart during ischemic conditions. Sestrin2 knockout (KO) mice were used to determine the importance of Sestrin2 during ischemia and reperfusion (I/R) injury. When wild-type (WT) and Sestrin2 KO mice were subjected to in vivo I/R, myocardial infarct size was significantly greater in Sestrin2 KO compared with WT hearts. Similarly, Langendorff perfused hearts indicated exacerbated postischemic contractile function in Sestrin2 KO hearts compared with WT. Ischemic AMPK activation was found to be impaired in the Sestrin2 KO hearts. Immunoprecipitation of Sestrin2 demonstrated an association with AMPK. Moreover, liver kinase B1 (LKB1), a major AMPK upstream kinase, was associated with the Sestrin2-AMPK complex in a time-dependent manner during ischemia, whereas this interaction was nearly abolished in Sestrin2 KO hearts. Thus, Sestrin2 plays an important role in cardioprotection against I/R injury, serving as an LKB1-AMPK scaffold to initiate AMPK activation during ischemic insults.—Morrison, A., Chen, L. Wang, J., Zhang, M., Yang, H., Ma, Y., Budanov, A., Lee, J. H., Karin, M., Li, J. Sestrin2 promotes LKB1-mediated AMPK activation in the ischemic heart. PMID:25366347

  18. Infrared Sources in the Small Magellanic Cloud: First Results

    NASA Astrophysics Data System (ADS)

    Simon, J. D.; Bolatto, A. D.; Stanimirovic, S.; Shah, R. Y.; Leroy, A.; Sandstrom, K.

    2008-03-01

    We have imaged the entire Small Magellanic Cloud (SMC), one of the two nearest star-forming dwarf galaxies, in all seven IRAC and MIPS bands. The low mass and low metallicity (1/6 solar) of the SMC make it the best local analog for primitive galaxies at high redshift. By studying the properties of dust and star formation in the SMC at high resolution, we can gain understanding of similar distant galaxies that can only be observed in much less detail. In this contribution, we present a preliminary analysis of the properties of point sources detected in the Spitzer Survey of the Small Magellanic Cloud (S^{3}MC). We find ˜400,000 unresolved or marginally resolved sources in our IRAC images, and our MIPS 24 μm mosaic contains ˜17,000 point sources. Source counts decline rapidly at the longer MIPS wavelengths. We use color-color and color-magnitude diagrams to investigate the nature of these objects, cross-correlate their positions with those of known sources at other wavelengths, and show examples of how these data can be used to identify interesting classes of objects such as carbon stars and young stellar objects. For additional examples of some of the questions that can be studied with these data, please see the accompanying contributions by Alberto Bolatto (survey information and images), Adam Leroy (dust and gas in a low-metallicity environment), Karin Sandstrom (far infrared-radio continuum correlation), and Snežana Stanimirović (on a young supernova remnant in the SMC). The mosaic images and point source catalogs we have made have been released to the public on our website (http://celestial.berkeley.edu/spitzer).

  19. Dynamical and Collisional Evolution of Asteroidal Dust Particles and the Structure of the Solar System Dust Bands

    NASA Astrophysics Data System (ADS)

    Dermott, S. F.; Kehoe, T. J. J.; Mahoney-Hopping, L.

    2005-12-01

    Recent modeling of the solar system dust bands has shown a significant discrepancy between the mean proper inclinations of the "ten-degree" band and the Eos asteroid family, its putative source. This has led to the suggestion that the dust bands did not result from the gradual comminution of large, ancient asteroid families but were instead produced by recent catastrophic disruptions of asteroids, such as those that generated the Karin cluster and the Veritas family. The small particles produced in such collisional events spiral rapidly into the Sun under the effect of Poynting-Robertson (P-R) drag. Larger particles have correspondingly longer P-R drag lifetimes but are more likely to be fragmented by inter-particle collisions. It is these large particles and their collisional fragments that we observe today as the dust bands, the decaying remnant of a much larger influx of material. The structure of the dust bands is therefore determined by the combined dynamical and collisional behavior of a realistic size distribution of particles. We present the results of numerical simulations showing the evolution of asteroidal dust particles under the effects of radiation pressure, P-R drag, solar wind drag, planetary perturbations, and stochastic size changes due to particle fragmentation. These results reveal that: (i) the orientation of the mean plane of symmetry of the dust bands outside 2AU is dominated by the effect of Jupiter as it evolves through its secular cycle and it is for this reason that we are able to observe the bands; (ii) the effect of inter-particle collisions introduces dispersion in the distribution of the particle orbits; and (iii) the inner edge to the dust bands at 2AU is a consequence of the effect of secular resonances dispersing particle orbits to the extent that the dust band signal merges into the flux from the background zodiacal cloud.

  20. Retrieving High Precision River Stages and Slopes from Space

    NASA Astrophysics Data System (ADS)

    Rodriguez, E.; Moller, D.

    2005-12-01

    Conventional radar altimetry has been successful in retrieving water level measurements at altimeter crossings with an accuracy of 10cm to 20cm. Although promising, this measurement accuracy is insufficient to provide global monitoring of fresh water bodies, as has been proposed by the WatER mission, for instance. In this paper we examine in detail the error sources that a near-nadir synthetic aperture radar interferometer, such as the KaRIN instrument proposed to meet the WatER requirements, will be subject to and demonstrate that with appropriate calibration techniques, measurements of river stage with an accuracy of approximately 5 cm and river slope with an accuracy of 1 cm/1km can be obtained. In the first part, we examine the main error contributors to the height measurements and quantify the expected magnitude of the errors. The errors sources examined include tropospheric effects, spacecraft orbit and attitude stability, the effect of vegetation, and the effect of topographic lay-over. These sources of error are examined analytically and also with the help of an instrument simulation which includes all error sources to generate simulated measurements. Simulated performance results will be presented for the Ohio river basin and for the Amazon basin at the Solimoes/Puros confluence. In the second part, we examine calibration techniques to mitigate the errors mentioned above and demonstrate the feasibility of achieving the height and slope performance given in the first paragraph. Simulated calibration results will be presented for both Ohio and Amazon basins. Finally, we propose a method for processing the interferometer data to optimally filter random measurement noise and provide high precision estimates of river stage and slope which can be assimilated simply into hydrologic models or used in conjunction with ancillary data or physical assumptions to provide estimates of river discharge.

  1. Recent Breakups in the Asteroid Belt

    NASA Astrophysics Data System (ADS)

    Nesvorny, D.

    2005-08-01

    Much of what we see in the asteroid belt today is a consequence of past collisions, which shaped the size-frequency distribution of asteroids and led to their heavily-cratered surfaces. Perhaps the most remarkable features of the belt are the asteroid families [1]. An asteroid family is a group of asteroid fragments with similar orbits and spectra produced by a collisional breakup of a large parent body. More than fifty families have been identified to date in the main belt [2]. These structures, when properly analyzed, hold important clues to the interior structure of asteroids, the physics of large scale collisions, and the overall evolution of the main belt since its formation [3]. Most of the known families are very old and thus have experienced significant dynamical and collisional erosion since their formation. This makes it difficult to clearly distinguish between features produced by the original breakup and those produced by on-going processes. Recent dynamical studies, however, have identified several asteroid families that are extremely young: the Iannini, Karin and Veritas families apparently formed at <5, 5.8 and 8.3 Ma, respectively [4,5]. These families represent nearly pristine examples of ejected fragments produced by disruptive asteroid collisions, because the observed remnants of recent breakups have apparently suffered limited dynamical and collisional erosion. Here we will discuss how studies of young asteroid families help us glean insights into the physics of large scale collisions, dynamical processes that affect small bodies in the Solar System, and the surface and interior properties of asteroids. [1] Hirayama, 1918, AJ 31, 185--188. [2] Zappala et al., 2002, In Asteroids III, pp. 619-629. [3] Bottke et al., 2005, Icarus, 175, 111-140. [4] Nesvorny et al., 2002, Nature 417, 720--722. [5] Nesvorny et al., 2003, ApJ 591, 486--497.

  2. A New Solar System Dust Band

    NASA Astrophysics Data System (ADS)

    Espy, Ashley J.; Dermott, S. F.; Kehoe, T. J.; Jayaraman, S.

    2007-10-01

    The relative proportions of asteroidal and cometary material in the zodiacal cloud is an evolving debate. The determination of the asteroidal component is constrained through the study of the dust bands (the fine-structure component superimposed on the broad background cloud), since they have been confidently linked to specific, young, asteroid family disruptions in the main belt. These disruptions represent recent injections of dust into the cloud and thus hold the key to determining at least a minimum value of the asteroidal contribution. There are currently known to be three dust band pairs, one at approximately 10 degrees corresponding to the Veritas family and two central band pairs near the ecliptic, one of which corresponds to the Karin cluster of the Koronis family. However, through careful co-adding of almost all the pole-to-pole intensity scans in the mid infrared wavebands of the IRAS data set, a new solar system dust band has been found at approximately 17 degrees inclination. We think this is a confirmation of the M/N partial band pair suggested by Sykes (1988). The new dust band appears to be mostly, yet not completely formed, which we attribute to the young age of the likely sources. We will present dynamical modeling of the new band which allows us to determine the most likely source and amount of cross-sectional area of dust in the band. This is turn allows us to put constraints on the size of the precursor and amount of dust contributed by this source to the background cloud. Since the band is incomplete, the dynamics of the distribution of the node will allow us to put loose constraints on the time of formation of this band and compare with the ages of the potential sources. This work is funded by NASA GSRP.

  3. Evidence from IRAS for a very young, partially formed dust band

    NASA Astrophysics Data System (ADS)

    Espy, Ashley J.; Dermott, Stanley F.; Kehoe, Thomas J. J.; Jayaraman, Sumita

    2009-02-01

    The relative proportions of asteroidal and cometary materials in the zodiacal cloud is an ongoing debate. The determination of the asteroidal component is constrained through the study of the Solar System dust bands (the fine-structure component superimposed on the broad background cloud), since they have been confidently linked to specific, young, asteroid families in the main belt. The disruptions that produce these families also result in the injection of dust into the cloud and thus hold the key to determining at least a minimum value for the asteroidal contribution to the zodiacal cloud. There are currently known to be at least three dust band pairs, one at approximately 9.35° associated with the Veritas family and two central band pairs near the ecliptic, one of which is associated with the Karin subcluster of the Koronis family. Through careful co-adding of almost all the pole-to-pole intensity scans in the mid-infrared wavebands of the Infrared Astronomical Satellite (IRAS) data set, we find strong evidence for a partial Solar System dust band, that is, a very young dust band in the process of formation, at approximately 17° latitude. We think this is a confirmation of the M/N partial band pair first suggested by Sykes [1988. IRAS observations of extended zodiacal structures. Astrophys. J. 334, L55-L58]. The new dust band appears at some but not all ecliptic longitudes, as expected for a young, partially formed dust band. We present preliminary modeling of the new, partial dust band which allows us to put constraints on the age of the disruption event, the inclination and node of the parent body at the time of disruption, and the quantity of dust injected into the zodiacal cloud.

  4. Size-frequency distributions of fragments from SPH/ N-body simulations of asteroid impacts: Comparison with observed asteroid families

    NASA Astrophysics Data System (ADS)

    Durda, Daniel D.; Bottke, William F.; Nesvorný, David; Enke, Brian L.; Merline, William J.; Asphaug, Erik; Richardson, Derek C.

    2007-02-01

    We investigate the morphology of size-frequency distributions (SFDs) resulting from impacts into 100-km-diameter parent asteroids, represented by a suite of 161 SPH/N-body simulations conducted to study asteroid satellite formation [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]. The spherical basalt projectiles range in diameter from 10 to 46 km (in equally spaced mass increments in logarithmic space, covering six discrete sizes), impact speeds range from 2.5 to 7 km/s (generally in 1 km/s increments), and impact angles range from 15° to 75° (nearly head-on to very oblique) in 15° increments. These modeled SFD morphologies match very well the observed SFDs of many known asteroid families. We use these modeled SFDs to scale to targets both larger and smaller than 100 km in order to gain insights into the circumstances of the impacts that formed these families. Some discrepancies occur for families with parent bodies smaller than a few tens of kilometers in diameter (e.g., 832 Karin), however, so due caution should be used in applying our results to such small families. We find that ˜20 observed main-belt asteroid families are produced by the catastrophic disruption of D >100 km parent bodies. Using these data as constraints, collisional modeling work [Bottke Jr., W.F., Durda, D.D., Nesvorný, D., Jedicke, R., Morbidelli, A., Vokrouhlický, D., Levison, H.F., 2005b. Icarus 179, 63-94] suggests that the threshold specific energy, QD∗, needed to eject 50% of the target body's mass is very close to that predicted by Benz and Asphaug [Benz, W., Asphaug, E., 1999. Icarus 142, 5-20].

  5. On Hilbert-Huang Transform Based Synthesis of a Signal Contaminated by Radio Frequency Interference or Fringes

    NASA Technical Reports Server (NTRS)

    Kizhner, Semion; Shiri, Ron S.; Vootukuru, Meg; Coletti, Alessandro

    2015-01-01

    Norden E. Huang et al. had proposed and published the Hilbert-Huang Transform (HHT) concept correspondently in 1996, 1998. The HHT is a novel method for adaptive spectral analysis of non-linear and non-stationary signals. The HHT comprises two components: - the Huang Empirical Mode Decomposition (EMD), resulting in an adaptive data-derived basis of Intrinsic Mode functions (IMFs), and the Hilbert Spectral Analysis (HSA1) based on the Hilbert Transform for 1-dimension (1D) applied to the EMD IMF's outcome. Although paper describes the HHT concept in great depth, it does not contain all needed methodology to implement the HHT computer code. In 2004, Semion Kizhner and Karin Blank implemented the reference digital HHT real-time data processing system for 1D (HHT-DPS Version 1.4). The case for 2-Dimension (2D) (HHT2) proved to be difficult due to the computational complexity of EMD for 2D (EMD2) and absence of a suitable Hilbert Transform for 2D spectral analysis (HSA2). The real-time EMD2 and HSA2 comprise the real-time HHT2. Kizhner completed the real-time EMD2 and the HSA2 reference digital implementations respectively in 2013 & 2014. Still, the HHT2 outcome synthesis remains an active research area. This paper presents the initial concepts and preliminary results of HHT2-based synthesis and its application to processing of signals contaminated by Radio-Frequency Interference (RFI), as well as optical systems' fringe detection and mitigation at design stage. The Soil Moisture Active Passive (SMAP mission (SMAP) carries a radiometer instrument that measures Earth soil moisture at L1 frequency (1.4 GHz polarimetric - H, V, 3rd and 4th Stokes parameters). There is abundant RFI at L1 and because soil moisture is a strategic parameter, it is important to be able to recover the RFI-contaminated measurement samples (15% of telemetry). State-of-the-art only allows RFI detection and removes RFI-contaminated measurements. The HHT-based analysis and synthesis facilitates

  6. Laboratory investigations on hydrate formation and dissociation in sediments - analogies and differences to natural systems

    NASA Astrophysics Data System (ADS)

    Schicks, J. M.; Spangenberg, E.; Priegnitz, M.; Heeschen, K. U.; Thaler, J.; Abendroth, S.

    2014-12-01

    this contribution we present the experimental set up and discuss the results with regard to the analogies and differences to natural systems. [1] Jürgen Mienert, Maarten Vanneste, Stefan Bünz, Karin Andreassen, Haflidi Haflidason, Hans Petter Sejrup, Marine and Petroleum Geology 22 (2005) 233-244.

  7. Sizes and Albedos of Young C-type Asteroids

    NASA Astrophysics Data System (ADS)

    Tamblyn, Peter; Chapman, Clark; Durda, Dan; Merline, William; Nesvorny, David

    2005-06-01

    We propose to measure the sizes and albedos of 8 very young C-type asteroids with IRAC 8um and near-simultaneous ground-based visible photometry. Asteroid families are created from major collisions between asteroids and are identified from clustering of orbital elements. Co-I Nesvorny has recently identified an exceptionally-young family (Veritas) and precisely-dated it at only 8.3+/-0.5 Myr (just 0.2% of the age of the solar system). We will compare our results for this family with those obtained by our similar Spitzer GO-1 program where we study an even younger S-type family, Karin. C-type asteroids are composed of primitive material (as opposed to the more processed silicate-rich S-types) and comprise the majority of asteorids in the Main Belt, yet their compositions and properties remain elusive. These recent breakup events provide unparalleled opportunities to study compositions, dynamics, and collisions of asteroids. They allow tests of the rates of physical processes that happen on time scales comparable with the family age. Space weathering, for example, appears to affect C- and S-type asteroids very differently. We will test directly whether the Veritas fragments have similar albedos; we will also test if their albedos differ from those of similar asteroids with much older surfaces by study of a second C-type family, Themis. We will compare our observations with those made of larger asteroids of both families, from a companion ground-based program. We will quantify any correlation of size with albedo, a dominant uncertainty in standard size estimates. The size distribution will be used to calibrate hydrocode models of asteroid collisions. To do this will require observations at the smallest practical sizes. In addition, the measured sizes will be immediately applicable to a novel measurement of the Yarkovsky Effect. We have already demonstrated in our GO-1 program that we can make similar Spitzer observations and provide the ground-based visible support.

  8. Predicting polarization and nonlinear dielectric response of arbitrary perovskite superlattice sequences

    NASA Astrophysics Data System (ADS)

    Wu, Xifan

    2008-03-01

    A complete theory of epitaxial perovskite superlattices requires an understanding both of epitaxial strain effects and of electrostatic boundary conditions. Here, focusing on the latter issue, weootnotetextIn collaboration with Massimiliano Stengel, Karin M. Rabe and David Vanderbilt. have carried out first-principles calculations of the nonlinear dielectric properties of short-period ``bicolor'' and ``tricolor'' CaTiO3/SrTiO3/BaTiO3 superlattices having the in-plane lattice constant of SrTiO3. In particular, we have calculated the layer polarizations pj as defined using the Wannier-based method of Wu, Di'eguez, Rabe and VanderbiltootnotetextX. Wu, O. Di'eguez, K. Rabe and D. Vanderbilt, Phys. Rev. Lett. 97, 107602 (2006). for each neutral BaO, SrO, CaO, or TiO2 layer. We use a cluster expansion (CE) technique to model the layer polarizations pj of a selected set of bicolor superlattices as a function of the displacement field D (which is uniform throughout the insulating superlattice), the chemical identity of the layer itself, and the chemical identity of its neighboring layers. We find that pj is a strongly localized function of its chemical environments at fixed D field, i.e., the dependence on the identity of the neighboring layers decays rapidly with distance. This localized property enables us to arrive at a truncated and simplified CE model which can accurately predict pj(D) in arbitrary layer sequences, both bicolor and tricolor. A similar approach is used to model the dependence of the c lattice constant. With all this information in hand, we can predict the polarization, piezoelectric and nonlinear dielectric response of arbitrary superlattice sequences. The power of the approach is demonstrated by showing that a model fitted only to calculations on inversion-symmetric bi-color superlattices can successfully predict the inversion symmetry breaking in tricolor superlattices such as 2SrTiO3/1BaTiO3/1CaTiO3.

  9. Defining the Flora Family: Orbital properties, reflectance properties and age

    NASA Astrophysics Data System (ADS)

    Dykhuis, Melissa J.; Molnar, Lawrence; Van Kooten, Samuel J.; Greenberg, Richard

    2014-11-01

    The Flora family resides in the densely populated inner main belt, bounded in semimajor axis by the ν6 secular resonance and the Jupiter 3:1 mean motion resonance. The presence of several large families that overlap dynamically with the Floras (e.g., the Vesta, Baptistina, and Nysa-Polana families), and the removal of a significant fraction of Floras via the nearby ν6 resonance complicates the Flora family's distinction in both proper orbital elements and reflectance properties. Here we use orbital information from the Asteroids Dynamic Site (AstDyS), color information from the Sloan Digital Sky Survey (SDSS), and albedo information from the Wide-field Infrared Survey Explorer (WISE) to obtain the median orbital and reflectance properties of the Floras by sampling the core of the family in multidimensional phase space. We find the median Flora SDSS colors to be a∗ = 0.126 ± 0.007 and i -z =-0.037±0.007 ; the median Flora albedo is pV = 0.291 ± 0.012. These properties allow us to define ranges for the Flora family in orbital and reflectance properties, as required for a detailed dynamical study. We use the young Karin family, for which we have an age determined via direct backward integration of members' orbits, to calibrate the Yarkovsky drift rates for the Flora family without having to estimate the Floras' material properties. The size-dependent dispersion of the Flora members in semimajor axis (the "V" plot) then yields an age for the family of 950-170+200 My, with the uncertainty dominated by the uncertainty in the material properties of the family members (e.g., density and surface thermal properties). We discuss the effects on our age estimate of two independent processes that both introduce obliquity variations among the family members on short (My) timescales: (1) the capture of Flora members in spin-orbit resonance, and (2) YORP-driven obliquity variation through YORP cycles. Accounting for these effects does not significantly change this age

  10. Redetermination of the Space Weathering Rate Using Spectra of Iannini Asteroid Family Members

    NASA Astrophysics Data System (ADS)

    Willman, Mark; Jedicke, R.; Nesvorny, D.; Moskovitz, N.; Ivezic, Z.; Fevig, R.

    2007-12-01

    We have obtained moderate S/N ( 85) spectra at a realized resolution of R 100 for 11 members of the Iannini family, until recently the youngest known family at under 5 million years of age. The spectra were acquired using ESI in its low-resolution prism mode on the Keck II telescope. The family members belong to the S class of asteroids with perhaps some K class members. The Iannini family members's average spectral slope, the slope of the best-fit line constrained to pivot about 1 at 550 nm, is (0.30±0.04)/μm, matching that previously reported using SDSS color photometry. Using our spectra for this family as well as new observations of Karin family members and new classifications of some older families we revised the space weathering rate of S class asteroids. We parameterize the space weathering rate of the principal component color of the spectrum (PC1), which is correlated with the spectral slope, as PC1(t) = PC1(0) + Δ PC1[1 - \\exp^{-(t/κ)α}]. Our revised rate suggests that the characteristic time scale for space weathering is τ = 570 ± 220 Myr and that new S class clusters will have an initial color of PC1(0) = 0.31 ± 0.04. This rate is in better agreement with lab measurements, supporting the use of space weathering as a dating method. Under the assumption that all the spectra should be identical, since the members all derive from the same parent body and are presumably covered with similar regolith, we combined them to obtain a high-S/N composite spectrum for the family. While the combined spectrum is clearly within the S/K class we note the appearance of a 'green feature' near 550 nm that has not previously been identified in asteroid spectra. We tentatively identify it as a feature in the pyroxene spectra as observed in the lab.

  11. Sustainable Seas Student Intertidal Monitoring Project at Duxbury Reef in Bolinas, CA (Invited)

    NASA Astrophysics Data System (ADS)

    Soave, K.; Dean, A.; Darakananda, K.; Ball, O.; Butti, C.; Yang, G.; Vetter, M.; Grimaldi, Z.

    2009-12-01

    Sustainable Seas Student Intertidal Monitoring Project at Duxbury Reef in Bolinas, CA Kathy Soave, Amy Dean, Olivia Ball, Karin Darakananda, Matt Vetter, Grant Yang, Charlotte Butti, Zoe Grimaldi The Sustainable Seas Student Monitoring Project at the Branson School in Ross, CA has monitored Duxbury Reef in Bolinas, CA since 1999, in cooperation with the Farallones Marine Sanctuary Association and the Gulf of Farallones National Marine Sanctuary. Goals of the project include: 1) To monitor the rocky intertidal habitat and develop a baseline database of invertebrates and algal density and abundance; 2) To contribute to the conservation of the rocky intertidal habitat through education of students and visitors about intertidal species and the requirements for maintaining a healthy, diverse intertidal ecosystem; 3) To increase stewardship in the Gulf of the Farallones National Marine Sanctuary; and 4) To contribute abundance and population data on key algae and invertebrate species to the national database, LiMPETS (Long Term Monitoring Program & Experiential Training for Students). Student volunteers complete an intensive training course on the natural history of intertidal invertebrates and algae, identification of key species, rocky intertidal monitoring techniques, and history of the sanctuary. Students identify and count key invertebrate and algae species along two permanent transects (A and B) and using randomly determined points within a permanent 100 m2 area, three times per year (fall, winter, and late spring). Using the data collected since 2004, we will analyze the population densities, seasonal abundance and long-term population trends of key algal and invertebrate species. Future analyses and investigations will include intertidal abiotic factors (including water temperature and human foot-traffic) to enhance insights into the workings of the Duxbury Reef ecosystem, in particular, the high intertidal zone which experiences the greatest amount of human

  12. Lunar and Planetary Science XXXV: Asteroids, Meteors, Comets

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Reports included:Long Term Stability of Mars Trojans; Horseshoe Asteroids and Quasi-satellites in Earth-like Orbits; Effect of Roughness on Visible Reflectance Spectra of Planetary Surface; SUBARU Spectroscopy of Asteroid (832) Karin; Determining Time Scale of Space Weathering; Change of Asteroid Reflectance Spectra by Space Weathering: Pulse Laser Irradiation on Meteorite Samples; Reflectance Spectra of CM2 Chondrite Mighei Irradiated with Pulsed Laser and Implications for Low-Albedo Asteroids and Martian Moons; Meteorite Porosities and Densities: A Review of Trends in the Data; Small Craters in the Inner Solar System: Primaries or Secondaries or Both?; Generation of an Ordinary-Chondrite Regolith by Repetitive Impact; Asteroid Modal Mineralogy Using Hapke Mixing Models: Validation with HED Meteorites; Particle Size Effect in X-Ray Fluorescence at a Large Phase Angle: Importance on Elemental Analysis of Asteroid Eros (433); An Investigation into Solar Wind Depletion of Sulfur in Troilite; Photometric Behaviour Dependent on Solar Phase Angle and Physical Characteristics of Binary Near-Earth-Asteroid (65803) 1996 GT; Spectroscopic Observations of Asteroid 4 Vesta from 1.9 to 3.5 micron: Evidence of Hydrated and/or Hydroxylated Minerals; Multi-Wavelength Observations of Asteroid 2100 Ra-Shalom: Visible, Infrared, and Thermal Spectroscopy Results; New Peculiarities of Cometary Outburst Activity; Preliminary Shape Modeling for the Asteroid (25143) Itokawa, AMICA of Hayabusa Mission; Scientific Capability of MINERVA Rover in Hayabusa Asteroid Mission; Characteristics and Current Status of Near Infrared Spectrometer for Hayabusa Mission; Sampling Strategy and Curation Plan of Hayabusa Asteroid Sample Return Mission; Visible/Near-Infrared Spectral Properties of MUSES C Target Asteroid 25143 Itokawa; Calibration of the NEAR XRS Solar Monitor; Modeling Mosaic Degradation of X-Ray Measurements of 433 Eros by NEAR-Shoemaker; Scattered Light Remediation and Recalibration of

  13. HSTOF ENA observations and energetic ion distributions in the heliosheath

    NASA Astrophysics Data System (ADS)

    Czechowski, A.; Hilchenbach, M.; Hsieh, K. C.

    2012-05-01

    caused by the charge-exchange and the escape losses. We dedicate this work to the memory of our longstanding coworker and dear colleague Karin Bamert.

  14. Obituary: Einar A. Tandberg-Hanssen (1921-2011)

    NASA Astrophysics Data System (ADS)

    Gary, G.; Emslie, A.; Hathaway, David; Moore, Ronald

    2011-12-01

    Dr. Einar Andreas Tandberg-Hanssen was born on 6 August 1921, in Bergen, Norway, and died on July 22, 2011, in Huntsville, AL, USA, due to complications from ALS (Amyotrophic lateral sclerosis, often referred to as Lou Gehrig's disease). His parents were administrator Birger Tandberg-Hanssen (1883-1951) and secretary Antonie "Mona" Meier (1895-1967). He married Erna Rönning (27 October 1921 - 22 November 1994), a nurse, on 22 June 1951. She was the daughter of Captain Einar Rönning (1890-1969) and Borghild Lyshaug (1897-1980). Einar and Erna had two daughters, Else Biesman (and husband Allen of Rapid City, SD, USA) and Karin Brock (and husband Mike of Gulf Shores, AL, USA). At the time of his death Einar had eight grandchildren and eight great-grandchildren. Dr. Tandberg-Hanssen was an internationally-known member of the solar physics community, with over a hundred published scientific papers and several books, including Solar Activity (1967), Solar Prominences (1974), The Physics of Solar Flares (1988) and The Nature of Solar Prominences (1995). Einar grew up in Langesund and Skien, Norway, where he took the qualifying exams at Skien High School in 1941. After the war he studied natural sciences at the University of Oslo and received his undergraduate degree in astronomy in 1950. He worked as a research assistant in the Institute of Theoretical Astrophysics at the University of Oslo for three intervals in the 1950s, interspersed by fellowships at the Institut d'Astrophysique in Paris, Caltech in Pasadena, CA, the High Altitude Observatory in Boulder, CO, and the Cavendish Laboratory in the UK (at the invitation of British radio-astronomer Sir Martin Ryle). He earned a doctorate in astrophysics at the University in Oslo in 1960 with a dissertation titled "An Investigation of the Temperature Conditions in Prominences with a Special Study of the Excitation of Helium." From 1959-61, Tandberg-Hanssen was a professor at the University in Oslo. He then traveled back to

  15. NASA Announces 2009 Astronomy and Astrophysics Fellows

    NASA Astrophysics Data System (ADS)

    2009-02-01

    WASHINGTON -- NASA has selected fellows in three areas of astronomy and astrophysics for its Einstein, Hubble, and Sagan Fellowships. The recipients of this year's post-doctoral fellowships will conduct independent research at institutions around the country. "The new fellows are among the best and brightest young astronomers in the world," said Jon Morse, director of the Astrophysics Division in NASA's Science Mission Directorate in Washington. "They already have contributed significantly to studies of how the universe works, the origin of our cosmos and whether we are alone in the cosmos. The fellowships will serve as a springboard for scientific leadership in the years to come, and as an inspiration for the next generation of students and early career researchers." Each fellowship provides support to the awardees for three years. The fellows may pursue their research at any host university or research center of their choosing in the United States. The new fellows will begin their programs in the fall of 2009. "I cannot tell you how much I am looking forward to spending the next few years conducting research in the U.S., thanks to the fellowships," said Karin Oberg, a graduate student in Leiden, The Netherlands. Oberg will study the evolution of water and ices during star formation when she starts her fellowship at the Smithsonian Astrophysical Observatory in Cambridge, Mass. People Who Read This Also Read... Milky Way's Super-efficient Particle Accelerators Caught in The Act Cosmic Heavyweights in Free-for-all Galaxies Coming of Age in Cosmic Blobs Cassiopeia A Comes Alive Across Time and Space A diverse group of 32 young scientists will work on a wide variety of projects, such as understanding supernova hydrodynamics, radio transients, neutron stars, galaxy clusters and the intercluster medium, supermassive black holes, their mergers and the associated gravitational waves, dark energy, dark matter and the reionization process. Other research topics include

  16. Preface: SQM2006

    NASA Astrophysics Data System (ADS)

    Barish, Kenneth; Zhong Huang, Huan; Kapusta, Joseph; Odyniec, Grazyna; Rafelski, Johann; Whitten, Charles A., Jr.

    2006-12-01

    served as conference coordinator. She and her crew organized all the conference activities and she has been essential for the success of the conference. Staff members from UCLA, Vahe Ghazikhanian, Stephen Trentalange, Mauro Leonardo, Josephine Morrell, Friedel Adler, Tuyet-Hong Truong-Ung, Leticia Cabeza, Karin Nachtigal, Martin Simon, Dylan Thein, Lingyu Xu and Craig Reaves, and graduate students Jingguo Ma, Johan Gonzalez, Xiaoyan Lin, Priscilla Kurnadi and David Staszak, also provided essential support for the conference. We wish to thank Tony Chan, Dean of Physical Sciences at UCLA, Lawrence Berkeley National Laboratory, Brookhaven National Laboratory and the UCLA Department of Physics and Astronomy for financial support of the conference. Their sponsorship allowed many graduate students and junior physicists to attend the conference. We also thank the SQM2006 International Advisory Committee for their valuable input to the scientific programme and conference arrangement.

  17. The Hawaii trails project: comet-hunting in the main asteroid belt

    NASA Astrophysics Data System (ADS)

    Hsieh, H. H.

    2009-10-01

    Context: The mysterious solar system object 133P/(7968) Elst-Pizarro is dynamically asteroidal, yet displays recurrent comet-like dust emission. Two scenarios were hypothesized to explain this unusual behavior: 1) 133P is a classical comet from the outer solar system that has evolved onto a main-belt orbit or 2) 133P is a dynamically ordinary main-belt asteroid on which subsurface ice has recently been exposed. If 1) is correct, the expected rarity of a dynamical transition onto an asteroidal orbit implies that 133P could be alone in the main belt. In contrast, if 2) is correct, other icy main-belt objects should exist and could also exhibit cometary activity. Aims: Believing 133P to be a dynamically ordinary, yet icy main-belt asteroid, I set out to test the primary prediction of the hypothesis: that 133P-like objects should be common and could be found by an appropriately designed observational survey. Methods: I conducted just such a survey - the Hawaii Trails Project - of selected main-belt asteroids in a search for objects displaying cometary activity. Optical observations were made of targets selected from among the Themis, Koronis, and Veritas asteroid families, the Karin asteroid cluster, and low-inclination, kilometer-scale outer-belt asteroids, using the Lulin 1.0 m, small and moderate aperture research telescope system (SMARTS) 1.0 m, University of Hawaii 2.2 m, southern astrophysical research (SOAR) 4.1 m, Gemini North 8.1 m, Subaru 8.2 m, and Keck I 10 m telescopes. Results: I made 657 observations of 599 asteroids, discovering one active object now known as 176P/LINEAR, leading to the identification of the new cometary class of main-belt comets (MBCs). These results suggest that there could be ~100 currently active MBCs among low-inclination, kilometer-scale outer-belt asteroids. Physically and statistically, MBC activity is consistent with initiation by meter-sized impactors. The estimated rate of impacts and sizes of resulting active sites, however

  18. Redetermination of the space weathering rate using spectra of Iannini asteroid family members

    NASA Astrophysics Data System (ADS)

    Willman, Mark; Jedicke, Robert; Nesvorný, David; Moskovitz, Nicholas; Ivezić, Željko; Fevig, Ronald

    2008-06-01

    We have obtained moderate S/N (˜85) spectra at a realized resolution of R˜100 for 11 members of the Iannini family, until recently the youngest known family at under 5 million years of age [Nesvorný, D., Bottke, W.F., Levison, H.F., Dones, L., 2003. Astrophys. J. 591, 486-497, 720-771]. The spectra were acquired using the Echellette Spectrograph and Imager in its low-resolution prism mode on the Keck II telescope. The family members belong to the S-complex of asteroids with perhaps some K class members. The Iannini family members' average spectral slope, defined as the slope of the best-fit line constrained to pivot about 1 at 550 nm, is (0.30±0.04)/μm, matching the (0.26±0.03)/μm reported by Jedicke et al. [Jedicke, R., Nesvorný, D., Whiteley, R.J., Ivezić, Ž., Jurić, M., 2004. Nature 429, 275-277] using SDSS [Ivezić, Ž., Jurić, M., Lupton, R.H., Tabachnik, S., Quinn, T., 2002. In: Tyson, J.A., Wolff, S. (Eds.), Survey and Other Telescope Technologies and Discoveries. In: Proc. SPIE, vol. 4836. SPIE, Bellingham, pp. 98-103] color photometry. Using our spectra for this family as well as new observations of Karin family members [Vernazza, P., Birlan, M., Rossi, A., Dotto, E., Nesvorný, D., Brunetto, R., Fornasier, S., Fulchignoni, M., Renner, S., 2006. Astron. Astrophys. 460, 945-951] and new classifications of some older families we have revised the space weathering rate of S-complex asteroids originally determined by Jedicke et al. [Jedicke, R., Nesvorný, D., Whiteley, R.J., Ivezić, Ž., Jurić, M., 2004. Nature 429, 275-277]. Following Jedicke et al. [Jedicke, R., Nesvorný, D., Whiteley, R.J., Ivezić, Ž., Jurić, M., 2004. Nature 429, 275-277] we parameterize the space weathering rate of the principal component color of the spectrum ( PC), which is correlated with the spectral slope, as PC(t)=PC(0)+ΔPC[1-exp]. Our revised rate suggests that the characteristic time scale for space weathering is τ=570±220 Myr and that new S-complex clusters

  19. Book Review: Beitraege zur Astronomiegeschichte, Band 5 (Acta Historica Astronomiae Vol. 15)

    NASA Astrophysics Data System (ADS)

    Duerbeck, H. W.; Dick, W. R.; Hamel, J.

    2002-12-01

    Pisa and the librarian Pozzetti at Bologna, and Karin Reich describes and edits Bessel's boo

  20. Unravelling the Mystery of Massive Star Birth - All Stars are Born the Same Way

    NASA Astrophysics Data System (ADS)

    2010-07-01

    of a screw on the International Space Station, or more than ten times the resolution possible with current visible-light telescopes in space. With this unique capability, complemented by observations done with another of ESO's telescopes, the 3.58-metre New Technology Telescope at La Silla, Kraus and colleagues were able to detect a disc around IRAS 13481-6124. "This is the first time we could image the inner regions of the disc around a massive young star", says Kraus. "Our observations show that formation works the same for all stars, regardless of mass." The astronomers conclude that the system is about 60 000 years old, and that the star has reached its final mass. Because of the intense light of the star - 30 000 times more luminous than our Sun - the disc will soon start to evaporate. The flared disc extends to about 130 times the Earth-Sun distance - or 130 astronomical units (AU) - and has a mass similar to that of the star, roughly twenty times the Sun. In addition, the inner parts of the disc are shown to be devoid of dust. "Further observations with the Atacama Large Millimeter/submillimeter Array (ALMA), currently being constructed in Chile, could provide much information on these inner parts, and allow us to better understand how baby massive stars became heavy," concludes Kraus. More information This research was presented in a paper to appear in this week issue of Nature ("A hot compact dust disk around a massive young stellar object", by S. Kraus et al.). The team is composed of Stefan Kraus (University of Michigan, USA), Karl-Heinz Hofmann, Karl M. Menten, Dieter Schertl, Gerd Weigelt, Friedrich Wyrowski, and Anthony Meilland (Max-Planck-Institut für Radioastronomie, Bonn, Germany),Karine Perraut (Laboratoire d'Astrophysique de Grenoble, France), Romain Petrov and Sylvie Robbe-Dubois (Université de Nice Sophia-Antipolis/CNRS/Observatoire de la Côte d'Azur, France), Peter Schilke (Universität zu Köln, Germany), and Leonardo Testi (ESO).

  1. Obituary: Einar A. Tandberg-Hanssen (1921-2011)

    NASA Astrophysics Data System (ADS)

    Gary, G.; Emslie, A.; Hathaway, David; Moore, Ronald

    2011-12-01

    Dr. Einar Andreas Tandberg-Hanssen was born on 6 August 1921, in Bergen, Norway, and died on July 22, 2011, in Huntsville, AL, USA, due to complications from ALS (Amyotrophic lateral sclerosis, often referred to as Lou Gehrig's disease). His parents were administrator Birger Tandberg-Hanssen (1883-1951) and secretary Antonie "Mona" Meier (1895-1967). He married Erna Rönning (27 October 1921 - 22 November 1994), a nurse, on 22 June 1951. She was the daughter of Captain Einar Rönning (1890-1969) and Borghild Lyshaug (1897-1980). Einar and Erna had two daughters, Else Biesman (and husband Allen of Rapid City, SD, USA) and Karin Brock (and husband Mike of Gulf Shores, AL, USA). At the time of his death Einar had eight grandchildren and eight great-grandchildren. Dr. Tandberg-Hanssen was an internationally-known member of the solar physics community, with over a hundred published scientific papers and several books, including Solar Activity (1967), Solar Prominences (1974), The Physics of Solar Flares (1988) and The Nature of Solar Prominences (1995). Einar grew up in Langesund and Skien, Norway, where he took the qualifying exams at Skien High School in 1941. After the war he studied natural sciences at the University of Oslo and received his undergraduate degree in astronomy in 1950. He worked as a research assistant in the Institute of Theoretical Astrophysics at the University of Oslo for three intervals in the 1950s, interspersed by fellowships at the Institut d'Astrophysique in Paris, Caltech in Pasadena, CA, the High Altitude Observatory in Boulder, CO, and the Cavendish Laboratory in the UK (at the invitation of British radio-astronomer Sir Martin Ryle). He earned a doctorate in astrophysics at the University in Oslo in 1960 with a dissertation titled "An Investigation of the Temperature Conditions in Prominences with a Special Study of the Excitation of Helium." From 1959-61, Tandberg-Hanssen was a professor at the University in Oslo. He then traveled back to

  2. VLBA Changes Picture of Famous Star-Forming Region

    NASA Astrophysics Data System (ADS)

    2007-10-01

    Using the supersharp radio "vision" of the National Science Foundation's Very Long Baseline Array (VLBA), astronomers have made the most precise measurement ever of the distance to a famous star-forming region. The measurement -- to the heavily studied Orion Nebula -- changes scientists' understanding of the characteristics of the young stars in the region. Parallax Diagram Trigonometric Parallax method determines distance to star by measuring its slight shift in apparent position as seen from opposite ends of Earth's orbit. CREDIT: Bill Saxton, NRAO/AUI/NSF Star Track Apparent track of star GMR A in the Orion Nebula Cluster, showing shift caused by Earth's orbital motion and star's movement in space. CREDIT: Sandstrom et al., NRAO/AUI/NSF Click on Images for Larger Files "This measurement is four times more precise than previous distance estimates. Because our measurement reduces the distance to this region, it tells us that the stars there are less bright than thought before, and changes the estimates of their ages," said Geoff Bower, an astronomer at the University of California at Berkeley. Bower, along with Karin Sandstrom, J.E.G. Peek, Alberto Bolatto and Richard Plambeck, all of Berkeley, published their findings in the October 10 edition of the Astrophysical Journal. The scientists determined the distance to a star called GMR A, one of a cluster of stars in the Orion Nebula, by measuring the slight shift in the star's apparent position in the sky caused by the Earth's motion around the Sun. Observing the star when the Earth is on opposite sides of its annual orbit allows astronomers to measure the angle of this small shift and thus provides a direct trigonometric calculation of its distance. "By using this technique, called parallax, we get a direct measurement that does not depend on various assumptions that are required to use less-direct methods," Bower said. "Only a telescope with the remarkable ability to see fine detail that is provided by the VLBA is

  3. Book Review: Beitraege zur Astronomiegeschichte, Band 5 (Acta Historica Astronomiae Vol. 15)

    NASA Astrophysics Data System (ADS)

    Duerbeck, H. W.; Dick, W. R.; Hamel, J.

    2002-12-01

    Pisa and the librarian Pozzetti at Bologna, and Karin Reich describes and edits Bessel's book critique of Gauss' Theoria Motus. How many one-time astronomers have to earn their living in other ways, become distracted from astronomical research, and vanish from the horizon of astronomical history? In the ninth paper, Hans-Joachim Ilgauds has traced the life of Georg Koch (1851-1905), who started his career as an astronomer at Leipzig Observatory in 1874. Later Koch worked at Hamburg Observatory, and then became an employee at the statistical office in Kiel, and finally director of the statistical office of the Hamburg revenue service. He was a collaborator for the statistical yearbook of German cities, and also contributed to a book investigating the causes and the impact of the cholera epidemic of 1892 in Hamburg. The last two papers deal with the circumstances of the discovery of the first Near-Earth asteroid (433) Eros. It was recorded on photographic plates taken at the Urania-Sternwarte Berlin and at Nice Observatory. The Berlin observer Witt announced the discovery, and only later, the Nice observer Charlois published a position of Eros. While all plates have disappeared, the authors Hans Scholl and Lutz D. Schmadel could prove that the Nice plate was poorly guided and Charlois would have been unable to discover the object. From a copy of the Berlin plate, published 50 years after the discovery by Witt's co-observer F. Linke, the exact position was determined, and the time of observation (which had not been published) was derived. The second article, by Lutz D. Schmadel, deals with the life of the Eros co-discoverer Felix Linke (1879-1959), who later worked in statistic offices, was a frequent writer of popular scientific articles, and later the editor of a journal, "Technik im Hotel'', and author of a book of the same title. As can be seen from the summaries given above, this collection of essays deals mainly with historical events that occurred in Germany and

  4. a Passage to the Universe

    NASA Astrophysics Data System (ADS)

    1995-11-01

    a concluding Press Conference , during which the outcome of this unique event will be summarized by the participants and the organisers: Monday, November 20, 1995, 15:30 pm, at the ESO Headquarters, Karl-Schwarzschild-Strasse 2, D-85748 Garching, Germany List of National First-Prize Winners Belgium: Mr. Freddy Allemeersch (Teacher), Mr. Pieter De Ceuninck, Mr. Jeroen Staelens (Onze-Lieve-Vrouwecollege, Brugge) Denmark: Mr. Joern C. Olsen, Mr. Henrik Struckmann, Mr. Uffe A. Hansen, Mr. Mogens Winther (Teacher) (Soenderborg Amtsgymnasium) Finland: Mr. Reima Eresmaa, Ms. Laura Elina Nykyri, Ms. Reetamaija Janhonen (Cygnaeues-Lukeo, Jyvaeskylae and Jyvaeskylaen Lyseon Lukeo) France: Mr. Rene Cavaroz (Teacher), Mr. Vincent Hardy, Mr. Antoine Lesuffleur (Lycee Chartier, Bayeux) Germany: Ms. Dorothee Barth, Mr. Walter Czech (Teacher), Mr. Uwe Kranz, Ms. Karin Wieland (Immanuel-Kant-Gymnasium, Leinfelden-Echterdingen, Baden-Wuerttemberg) Greece: Ms. Agni Ioannidi, Ms. Elena Katifori, Mr. Vassilis Samiotis, Mr. Vassillos Tzotzes (Teacher) (Second Varvakelo Experimental Lyceum, Athens) Ireland: Mr. Declan Maccuarta (Teacher), Mr. Colm Mcloughlin (St. Peter's College, Wexford, Co. Wexford) Italy: Mr. Pasquale Ciarletta, Ms. Francesca D'elia, Ms. Ada Fortugna (Teacher), Mr. Alfredo Pudano (Liceo Scientifico `Leonardo da Vinci', Reggio Calabria) The Netherlands: Mr. Alex De Beer, Mr. Klaas Huijbregts, Mr. Ruud Nellen (Norbertuscollege, Rosendaal) Spain: Mr. Aritz Atela Aio, Mr. Julen Sarasola Manich (Teacher), Mr. Jon Huertas Rodriquez (Txorierri Batxilergoko Institua, Derio Bizkaia) Sweden: Mr. Rahman Amanullah, Mr. Kjell L. Bonander (Teacher), Mr. Tomas Oppelstrup, Ms. Christin Wiedemann (Saltsjoebadens Samskola, Saltsjoebaden) United Kingdom: Mr. Michael Ching, Dr. Richard Field (Teacher) (Oundle School, Peterborough) National Committees Further information about the national contests may be obtained from the National Committees: Belgium: Dr. C. Sterken, Vrije Universiteit

  5. Congratulations to Carey King

    NASA Astrophysics Data System (ADS)

    Hall, Charles A. S.

    2012-03-01

    importance of these more comprehensive EROIs but we do understand that our usual methods of including only energy used directly (e.g. to run a pump) or indirectly (e.g. to manufacture the steel forms used) greatly underestimates the total amount of energy needed to produce energy. In conclusion, Carey King appears to be one of the real rising energy stars as energy becomes again much more important. He is very bright, original and is a very hard worker. I look forward to much exciting, innovative and important work from his endeavors. References Barnett H and Morse C 1963 Scarcity and Growth: The Economics of Natural Resource Availability (Baltimore, MD: Johns Hopkins Press) Cleveland C J, Costanza R, Hall C A S and Kaufmann R 1984 Energy and the United States economy: a biophysical perspective Science 225 890-7 Denison E F 1989 Estimates of Productivity Change by Industry, an Evaluation and an Alternative (Washington, DC: The Brookings Institution) Hall C A S 1972 Migration and metabolism in a temperate stream ecosystem Ecology 53 585-604 Hall C A S and Cleveland C J 1981 Petroleum drilling and production in the United States: yield per effort and net energy analysis Science 211 576-9 Hall C A S and Klitgaard K 2011 Energy and the Wealth of Nations: Understanding the Biophysical Economy (New York: Springer) Kaufmann R 2004 The mechanisms for autonomous energy efficiency increases: a cointegration analysis of the US Energy/GDP Ratio The Energy Journal 25 63-86 King C W 2010 Energy intensity ratios as net energy measures of United States energy production and expenditures Environ. Res. Lett. 5 044006 Murphy D J and Hall C A S 2011 Energy return on investment, peak oil, and the end of economic growth in 'Ecological Economics Reviews' ed Robert Costanza, Karin Limburg and Ida Kubiszewski Ann. N.Y. Acad. Sci. 1219 52-72 Solow R M 1974 The economics of resources or the resources of economics American Economic Review 66 1-14 Odum H T 1973 Environment, Power and Society (New York