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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

197 CANDIDATES AND 104 VALIDATED PLANETS IN K2's FIRST FIVE FIELDS

Crossfield, Ian J. M., Ciardi, David R., Petigura, Erik A., Sinukoff, Evan, Schlieder, Joshua E., Howard, Andrew W., Beichman, Charles A., Isaacson, Howard, Dressing, Courtney D., Christiansen, Jessie L., Fulton, Benjamin J., Lepine, Sebastien, Weiss, Lauren, Hirsch, Lea, Livingston, John, Baranec, Christoph, Law, Nicholas M., Riddle, Reed, Ziegler, Carl, Howell, Steve B., Horch, Elliott, Everett, Mark, Teske, Johanna, Martinez, Arturo O., Obermeier, Christian, Benneke, Bjorn, Scott, Nic, Deacon, Niall, Aller, Kimberly M., Hansen, Brad M. S., Mancini, Luigi, Ciceri, Simona, Brahm, Rafael, Jordan, Andres, Knutson, Heather A., Henning, Thomas, Bonnefoy, Michael, Liu, Michael C., Crepp, Justin R., Lothringer, Joshua, Hinz, Phil, Bailey, Vanessa, Skemer, Andrew, Defrere, Denis 02 September 2016 (has links)
We present 197 planet candidates discovered using data from the first year of the NASA K2 mission (Campaigns 0-4), along with the results of an intensive program of photometric analyses, stellar spectroscopy, high-resolution imaging, and statistical validation. We distill these candidates into sets of 104 validated planets (57 in multi-planet systems), 30 false positives, and 63 remaining candidates. Our validated systems span a range of properties, with median values of R-P = 2.3 R-circle plus, P = 8.6 days, T-eff = 5300 K, and Kp = 12.7 mag. Stellar spectroscopy provides precise stellar and planetary parameters for most of these systems. We show that K2 has increased by 30% the number of small planets known to orbit moderately bright stars (1-4 R-circle plus, Kp = 9-13. mag). Of particular interest are 76 planets smaller than 2 R-circle plus, 15 orbiting stars brighter than Kp = 11.5. mag, 5 receiving Earth-like irradiation levels, and several multi-planet systems-including 4 planets orbiting the M dwarf K2-72 near mean-motion resonances. By quantifying the likelihood that each candidate is a planet we demonstrate that our candidate sample has an overall false positive rate of 15%-30%, with rates substantially lower for small candidates (<2 R-circle plus) and larger for candidates with radii >8 R-circle plus and/or with P < 3 days. Extrapolation of the current planetary yield suggests that K2 will discover between 500 and 1000 planets in its planned four-year mission, assuming sufficient follow-up resources are available. Efficient observing and analysis, together with an organized and coherent follow-up strategy, are essential for maximizing the efficacy of planet-validation efforts for K2, TESS, and future large-scale surveys.
32

SPITZER OBSERVATIONS CONFIRM AND RESCUE THE HABITABLE-ZONE SUPER-EARTH K2-18b FOR FUTURE CHARACTERIZATION

Benneke, Björn, Werner, Michael, Petigura, Erik, Knutson, Heather, Dressing, Courtney, Crossfield, Ian J. M., Schlieder, Joshua E., Livingston, John, Beichman, Charles, Christiansen, Jessie, Krick, Jessica, Gorjian, Varoujan, Howard, Andrew W., Sinukoff, Evan, Ciardi, David R., Akeson, Rachel L. 12 January 2017 (has links)
The recent detections of two transit events attributed to the super-Earth candidate K2-18b have provided the unprecedented prospect of spectroscopically studying a habitable-zone planet outside the solar system. Orbiting a nearby M2.5 dwarf and receiving virtually the same stellar insolation as Earth, K2-18b would be a prime candidate for the first detailed atmospheric characterization of a habitable-zone exoplanet using the Hubble Space Telescope (HST) and James Webb Space Telescope (JWST). Here, we report the detection of a third transit of K2-18b near the predicted transit time using the Spitzer Space Telescope. The Spitzer detection demonstrates the periodic nature of the two transit events discovered by K2, confirming that K2-18 is indeed orbited by a super-Earth in a 33 day orbit, ruling out the alternative scenario of two similarly sized, long-period planets transiting only once within the 75 day Kepler Space Telescope (K2) observation. We also find, however, that the transit event detected by Spitzer occurred 1.85 hr (7 sigma) before the predicted transit time. Our joint analysis of the Spitzer and K2 photometry reveals that this early occurrence of the transit is not caused by transit timing variations, but the result of an inaccurate ephemeris due to a previously undetected data anomaly in the K2 photometry. We refit the ephemeris and find that K2-18b would have been lost for future atmospheric characterizations with HST and JWST if we had not secured its ephemeris shortly after the discovery. We caution that immediate follow-up observations as presented here will also be critical for confirming and securing future planets discovered by the Transiting Exoplanet Survey Satellite (TESS), in particular if only two transit events are covered by the relatively short 27-day TESS campaigns.
33

3.6 AND 4.5 μm SPITZER PHASE CURVES OF THE HIGHLY IRRADIATED HOT JUPITERS WASP-19b AND HAT-P-7b

Wong, Ian, Knutson, Heather A., Kataria, Tiffany, Lewis, Nikole K., Burrows, Adam, Fortney, Jonathan J., Schwartz, Joel, Shporer, Avi, Agol, Eric, Cowan, Nicolas B., Deming, Drake, Désert, Jean-Michel, Fulton, Benjamin J., Howard, Andrew W., Langton, Jonathan, Laughlin, Gregory, Showman, Adam P., Todorov, Kamen 27 May 2016 (has links)
We analyze full-orbit phase curve observations of the transiting hot Jupiters WASP-19b and HAT-P-7b at 3.6 and 4.5 mu m, obtained using the Spitzer Space Telescope. For WASP-19b, we measure secondary eclipse depths of 0.485% +/- 0.024% and 0.584% +/- 0.029% at 3.6 and 4.5 mu m, which are consistent with a single blackbody with effective temperature 2372 +/- 60 K. The measured 3.6 and 4.5 mu m secondary eclipse depths for HAT-P-7b are 0.156% +/- 0.009% and 0.190% +/- 0.006%, which are well described by a single blackbody with effective temperature 2667 +/- 57 K. Comparing the phase curves to the predictions of one-dimensional and three-dimensional atmospheric models, we find that WASP-19b's dayside emission is consistent with a model atmosphere with no dayside thermal inversion and moderately efficient day-night circulation. We also detect an eastward-shifted hotspot, which suggests the presence of a superrotating equatorial jet. In contrast, HAT-P-7b's dayside emission suggests a dayside thermal inversion and relatively inefficient day-night circulation; no hotspot shift is detected. For both planets, these same models do not agree with the measured nightside emission. The discrepancies in the model-data comparisons for WASP-19b might be explained by high-altitude silicate clouds on the nightside and/or high atmospheric metallicity, while the very low 3.6 mu m nightside planetary brightness for HAT-P-7b may be indicative of an enhanced global C/O ratio. We compute Bond albedos of 0.38 +/- 0.06 and 0 (<0.08 at 1 sigma) for WASP-19b and HAT-P-7b, respectively. In the context of other planets with thermal phase curve measurements, we show that WASP-19b and HAT-P-7b fit the general trend of decreasing day-night heat recirculation with increasing irradiation.
34

Exceptional outburst of the blazar CTA 102 in 2012: the GASP–WEBT campaign and its extension

Larionov, V. M., Villata, M., Raiteri, C. M., Jorstad, S. G., Marscher, A. P., Agudo, I., Smith, P. S., Acosta-Pulido, J. A., ˙arévalo, M. J., Arkharov, A. A., Bachev, R., Blinov, D. A., Borisov, G., Borman, G. A., Bozhilov, V., Bueno, A., Carnerero, M. I., Carosati, D., Casadio, C., Chen, W. P., Clemens, D. P., Di Paola, A., Ehgamberdiev, Sh. A., Gómez, J. L., González-Morales, P. A., Griñón-Marín, A., Grishina, T. S., Hagen-Thorn, V. A., Ibryamov, S., Itoh, R., Joshi, M., Kopatskaya, E. N., Koptelova, E., Lázaro, C., Larionova, E. G., Larionova, L. V., Manilla-Robles, A., Metodieva, Y., Milanova, Yu. V., Mirzaqulov, D. O., Molina, S. N., Morozova, D. A., Nazarov, S. V., Ovcharov, E., Peneva, S., Ros, J. A., Sadun, A. C., Savchenko, S. S., Semkov, E., Sergeev, S. G., Strigachev, A., Troitskaya, Yu. V., Troitsky, I. S. 21 September 2016 (has links)
After several years of quiescence, the blazar CTA 102 underwent an exceptional outburst in 2012 September-October. The flare was tracked from gamma-ray to near-infrared (NIR) frequencies, including Fermi and Swift data as well as photometric and polarimetric data from several observatories. An intensive Glast-Agile support programme of the Whole Earth Blazar Telescope (GASP-WEBT) collaboration campaign in optical and NIR bands, with an addition of previously unpublished archival data and extension through fall 2015, allows comparison of this outburst with the previous activity period of this blazar in 2004-2005. We find remarkable similarity between the optical and gamma-ray behaviour of CTA 102 during the outburst, with a time lag between the two light curves of approximate to 1 h, indicative of cospatiality of the optical and gamma-ray emission regions. The relation between the gamma-ray and optical fluxes is consistent with the synchrotron self-Compton (SSC) mechanism, with a quadratic dependence of the SSC gamma -ray flux on the synchrotron optical flux evident in the post-outburst stage. However, the gamma -ray/optical relationship is linear during the outburst; we attribute this to changes in the Doppler factor. A strong harder-when-brighter spectral dependence is seen both the in gamma-ray and optical non-thermal emission. This hardening can be explained by convexity of the UV-NIR spectrum that moves to higher frequencies owing to an increased Doppler shift as the viewing angle decreases during the outburst stage. The overall pattern of Stokes parameter variations agrees with a model of a radiating blob or shock wave that moves along a helical path down the jet.
35

ELEVEN MULTIPLANET SYSTEMS FROM K2 CAMPAIGNS 1 AND 2 AND THE MASSES OF TWO HOT SUPER-EARTHS

Sinukoff, Evan, Howard, Andrew W., Petigura, Erik A., Schlieder, Joshua E., Crossfield, Ian J. M., Ciardi, David R., Fulton, Benjamin J., Isaacson, Howard, Aller, Kimberly M., Baranec, Christoph, Beichman, Charles A., Hansen, Brad M. S., Knutson, Heather A., Law, Nicholas M., Liu, Michael C., Riddle, Reed, Dressing, Courtney D. 09 August 2016 (has links)
We present a catalog of 11 multiplanet systems from Campaigns 1 and 2 of the K2 mission. We report the sizes and orbits of 26 planets split between seven two-planet systems and four three-planet systems. These planets stem from a systematic search of the K2 photometry for all dwarf stars observed by K2 in these fields. We precisely characterized the host stars with adaptive optics imaging and analysis of high-resolution optical spectra from Keck/HIRES and medium-resolution spectra from IRTF/SpeX. We confirm two planet candidates by mass detection and validate the remaining 24 candidates to >99% confidence. Thirteen planets were previously validated or confirmed by other studies, and 24 were previously identified as planet candidates. The planets are mostly smaller than Neptune (21/26 planets), as in the Kepler mission, and all have short periods (P < 50 days) due to the duration of the K2 photometry. The host stars are relatively bright (most have Kp < 12.5 mag) and are amenable to follow-up characterization. For K2-38, we measured precise radial velocities using Keck/HIRES and provide initial estimates of the planet masses. K2-38b is a short-period super-Earth with a radius of 1.55 +/- 0.16 R-circle plus, a mass of 12.0 +/- 2.9M(circle plus), and a high density consistent with an iron-rich composition. The outer planet K2-38c is a lower-density sub-Neptune-size planet with a radius of 2.42 +/- 0.29 R-circle plus and a mass of 9.9 +/- 4.6M(circle plus) that likely has a substantial envelope. This new planet sample demonstrates the capability of K2 to discover numerous planetary systems around bright stars.
36

K2 DISCOVERS A BUSY BEE: AN UNUSUAL TRANSITING NEPTUNE FOUND IN THE BEEHIVE CLUSTER

Obermeier, Christian, Henning, Thomas, Schlieder, Joshua E., Crossfield, Ian J. M., Petigura, Erik A., Howard, Andrew W., Sinukoff, Evan, Isaacson, Howard, Ciardi, David R., David, Trevor J., Hillenbrand, Lynne A., Beichman, Charles A., Howell, Steve B., Horch, Elliott, Everett, Mark, Hirsch, Lea, Teske, Johanna, Christiansen, Jessie L., Lépine, Sébastien, Aller, Kimberly M., Liu, Michael C., Saglia, Roberto P., Livingston, John, Kluge, Matthias 07 December 2016 (has links)
Open clusters have been the focus of several exoplanet surveys, but only a few planets have so far been discovered. The Kepler spacecraft revealed an abundance of small planets around small cool stars, therefore, such cluster members are prime targets for exoplanet transit searches. Kepler's new mission, K2, is targeting several open clusters and star-forming regions around the ecliptic to search for transiting planets around their low-mass constituents. Here, we report the discovery of the first transiting planet in the intermediate-age (800 Myr) Beehive cluster (Praesepe). K2-95 is a faint (Kp = 15.5 mag) M3.0 +/- 0.5 dwarf from K2's Campaign 5 with an effective temperature of 3471 +/- 124 K, approximately solar metallicity and a radius of 0.402 +/- 0.050 R-circle dot. We detected a transiting planet with a radius of 3.47(-0.53)(+0.78)R(circle plus) and an orbital period of 10.134 days. We combined photometry, medium/high-resolution spectroscopy, adaptive optics/speckle imaging, and archival survey images to rule out any false-positive detection scenarios, validate the planet, and further characterize the system. The planet's radius is very unusual as M-dwarf field stars rarely have Neptune-sized transiting planets. The comparatively large radius of K2-95b is consistent with the other recently discovered cluster planets K2-25b (Hyades) and K2-33b (Upper Scorpius), indicating systematic differences in their evolutionary states or formation. These discoveries from K2 provide a snapshot of planet formation and evolution in cluster environments and thus make excellent laboratories to test differences between field-star and cluster planet populations.
37

Estudo de alguns indicadores fluorescentes para oxigênio em solução aquosa / Study of some fluorescent indicator for oxygen in aqueous solution

Stein, Luciene Cristina 16 April 2004 (has links)
Complexos de rutênio (II) tris(2,2\'-bipiridina) e 5,10, 15,20-tetrakis(1-metilpiridínio-4-il) porfirina de paládio (II) foram empregados como indicadores da concentração de oxigênio dissolvido em solução aquosa, baseando-se no efeito supressor do oxigênio na fluorescência desses íons complexos. Soluções aquosas desses complexos foram empregadas como indicadoras luminescentes, para verificar a eficiência de um sistema de degaseificação aplicado para remoção de oxigênio de amostras de solução. O uso do íon rutênio (II) tris(2,2\'-bipiridina) como indicador foi avaliado no monitoramento do consumo de oxigênio na reação de autoxidação de S(IV) catalisada por Mn(II) e pelo complexo de Ni(II)/tetraglicina. / The complexes of tris(2,2\'-bipyridyl)ruthenium(II) and 5,10,15,20-tetrakis(1-methilpyridyl-4) porphyrin palladium (II), were used as luminescent probes of dissolved oxygen in aqueous solutions, based on the quenching effect of oxygen in fluorescence spectrometry. Aqueous solutions of these complexes served as a luminescent probe to check the performance of one flow degassing device applied to the removal of oxygen from sample solution. The ion tris(2,2\'-bipyridyl)ruthenium(II) was used as one probe to evaluate the oxygen consumption on the autoxidation reactions of S(IV) catalyzed by Mn(II) and Ni(II)/tetraglycine complex.
38

Portable capillary electrophoresis system with LED-absorbance photometric and LED-induced fluorescence detection : Design, characterisation and testing

Stjernlöf, Anna January 2008 (has links)
<p>Capillary electrophoresis (CE) has a wide range of applications in the field of analytical chemistry. In general the most expensive part in a CE system is the detector due to the fact that the detector must have a high sensitivity for small detection volumes and low concentrations. Building portable instruments is one way to make the instruments cheaper and has the advantage that they can be used virtually everywhere. However, downscaling of CE instruments puts some extra demands on the detector. This report describes the design and building of two homemade light-emitting diode (LED) based detectors; a LEDabsorbance photometric detector (LED-AP) and a LED-induced fluorescence (LED-IF) detector. The main goal was to install them inside a portable CE and make a simple separation. The performance of the two detectors had to be evaluated before the main goal could be achieved. p-Nitrophenol was used to create a sensitivity graph for the LED-AP detector, calculating the upper linearity to 5.6 mM when the sensitivity had dropped 10 % caused by non-linearity. The sensitivity graph also showed that the detector had an effective pathlength of 74.2 µm and a stray light of 4.5 % for a 75 µm i.d fused-silica capillary. The LED-IF detector was evaluated by determining the limit of detection (LOD) for fluorescein, at a signal to noise ratio of 3. The LOD was 0.72 µM ± 0.01 µM when immersion oil was used to limit the light scattering from the optic fibres in to the capillary and 0.58 µM ±0.02 µM when silicone oil was used. Without doing any improvements only the LED-AP detector could be used in the portable CE. As a common application area for portable CE instruments is environmental analysis, indirect detection using p-nitrophenol as a probe for separating anions was done to test the system. All analytes were eluted in less than 4 minutes.</p>
39

Picking Up an Object from a Pile of Objects

Ikeuchi, Katsushi, Horn, Berthold K.P., Nagata, Shigemi, Callahan, Tom, Fein, Oded 01 May 1983 (has links)
This paper describes a hand-eye system we developed to perform the binpicking task. Two basic tools are employed: the photometric stereo method and the extended Gaussian image. The photometric stereo method generates the surface normal distribution of a scene. The extended Gaussian image allows us to determine the attitude of the object based on the normal distribution. Visual analysis of an image consists of two stages. The first stage segments the image into regions and determines the target region. The photometric stereo system provides the surface normal distribution of the scene. The system segments the scene into isolated regions using the surface normal distribution rather than the brightness distribution. The second stage determines object attitude and position by comparing the surface normal distribution with the extended-Gaussian-image. Fingers, with LED sensor, mounted on the PUMA arm can successfully pick an object from a pile based on the information from the vision part.
40

Portable capillary electrophoresis system with LED-absorbance photometric and LED-induced fluorescence detection : Design, characterisation and testing

Stjernlöf, Anna January 2008 (has links)
Capillary electrophoresis (CE) has a wide range of applications in the field of analytical chemistry. In general the most expensive part in a CE system is the detector due to the fact that the detector must have a high sensitivity for small detection volumes and low concentrations. Building portable instruments is one way to make the instruments cheaper and has the advantage that they can be used virtually everywhere. However, downscaling of CE instruments puts some extra demands on the detector. This report describes the design and building of two homemade light-emitting diode (LED) based detectors; a LEDabsorbance photometric detector (LED-AP) and a LED-induced fluorescence (LED-IF) detector. The main goal was to install them inside a portable CE and make a simple separation. The performance of the two detectors had to be evaluated before the main goal could be achieved. p-Nitrophenol was used to create a sensitivity graph for the LED-AP detector, calculating the upper linearity to 5.6 mM when the sensitivity had dropped 10 % caused by non-linearity. The sensitivity graph also showed that the detector had an effective pathlength of 74.2 µm and a stray light of 4.5 % for a 75 µm i.d fused-silica capillary. The LED-IF detector was evaluated by determining the limit of detection (LOD) for fluorescein, at a signal to noise ratio of 3. The LOD was 0.72 µM ± 0.01 µM when immersion oil was used to limit the light scattering from the optic fibres in to the capillary and 0.58 µM ±0.02 µM when silicone oil was used. Without doing any improvements only the LED-AP detector could be used in the portable CE. As a common application area for portable CE instruments is environmental analysis, indirect detection using p-nitrophenol as a probe for separating anions was done to test the system. All analytes were eluted in less than 4 minutes.

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