Search

Your search keyword '"Broiles, Thomas"' showing total 7 results
Start Over Author "Broiles, Thomas"

Refine your results

more »
7 results on '"Broiles, Thomas"'

1. Ultraviolet Observations of Coronal Mass Ejection Impact on Comet 67P/Churyumov-Gerasimenko by Rosetta Alice

Author

Noonan, John W., Stern, S. Alan, Feldman, Paul D., Broiles, Thomas, Wedlund, Cyril Simon, Edberg, Niklas J. T., Schindhelm, R., Parker, Joel Wm., Keeney, Brian A., Vervack Jr, Ronald J., Steffl, Andrew J., Knight, Matthew M., Weaver, Harold A., Feaga, Lori M., A'Hearn, Michael, and Bertaux, Jean-Loup

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

The Alice ultraviolet spectrograph on the European Space Agency Rosetta spacecraft observed comet 67P/Churyumov-Gerasimenko in its orbit around the Sun for just over two years. Alice observations taken in 2015 October, two months after perihelion, show large increases in the comet's Ly-$\beta$, O I 1304, O I 1356, and C I 1657 $\AA$ atomic emission that initially appeared to indicate gaseous outbursts. However, the Rosetta Plasma Consortium instruments showed a coronal mass ejection (CME) impact at the comet coincident with the emission increases, suggesting that the CME impact may have been the cause of the increased emission. The presence of the semi-forbidden O I 1356 $\AA$ emission multiplet is indicative of a substantial increase in dissociative electron impact emission from the coma, suggesting a change in the electron population during the CME impact. The increase in dissociative electron impact could be a result of the interaction between the CME and the coma of 67P or an outburst coincident with the arrival of the CME. The observed dissociative electron impact emission during this period is used to characterize the O2 content of the coma at two peaks during the CME arrival. The mechanism that could cause the relationship between the CME and UV emission brightness is not well constrained, but we present several hypotheses to explain the correlation., Comment: 11 pages, 7 figures, 3 tables

Published
2018
Full Text
View/download PDF

2. Ultraviolet Observations of Coronal Mass Ejection Impact on Comet 67P/Churyumov–Gerasimenko by Rosetta Alice

Author

Noonan, John W., primary, Stern, S. Alan, additional, Feldman, Paul D., additional, Broiles, Thomas, additional, Wedlund, Cyril Simon, additional, Edberg, Niklas J. T., additional, Schindhelm, Rebecca N., additional, Parker, Joel Wm., additional, Keeney, Brian A., additional, Vervack Jr, Ronald J., additional, Steffl, Andrew J., additional, Knight, Matthew M., additional, Weaver, Harold A., additional, Feaga, Lori M., additional, A’Hearn, Michael, additional, and Bertaux, Jean-Loup, additional

Published
2018
Full Text
View/download PDF

3. Mapping of the cometary plasma density around comet CG/67P at perihelion

Author

Henri, Pierre, Eriksson, Anders, Edberg, Niklas, Béghin, Christian, Décréau, Pierrette, Grard, Réjean, Hamelin, Michel, Johansson, Erik, Lebreton, Jean-Pierre, Mazelle, Christian, Odelstad, Elias, Randriamboarison, Orélien, Schmidt, Walter, Wattieaux, Gaëtan, Winterhalter, Daniel, Vallières, Xavier, Vigren, Erik, Glassmeier, Karl-Heinz, Goetz, Charlotte, Koenders, Christoph, Richter, Ingo, Volwerk, Martin, Burch, James, Broiles, Thomas, Golstein, Ray, Mandt, Kathleen, Mokashi, Prachet, Nilsson, Hans, Sternberg Wieser, Gabriella, Carr, Chris, Cupido, Emanuele, Galand, Marina, Matteini, Lorenzo, Nemeth, Zoltan, Szego, Karoly, Vallat, C., Schwartz, Steven, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Swedish Institute of Space Physics [Uppsala] (IRF), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre d'étude spatiale des rayonnements (CESR), Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Finnish Meteorological Institute (FMI), Plasmas Réactifs Hors Equilibre (LAPLACE-PRHE), LAboratoire PLasma et Conversion d'Energie (LAPLACE), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Austrian Academy of Sciences (OeAW), Southwest Research Institute [San Antonio] (SwRI), Blackett Laboratory, Imperial College London, Wigner Research Centre for Physics [Budapest], Hungarian Academy of Sciences (MTA), European Space Astronomy Centre (ESAC), European Space Agency (ESA), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT), NASA-California Institute of Technology (CALTECH), and Agence Spatiale Européenne = European Space Agency (ESA)

Subjects
[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM]
Abstract

International audience; In August 2015, comet 67P/Churyumov-Gerasimenko, target of the ESA’s Rosetta mission, reached its perihelion at 1.3 AU from the Sun. The Rosetta Plasma Consortium (RPC) onboard the Rosetta spacecraft offers a unique opportunity to analyze the plasma environment during this period. Combining observations from the Mutual Impedance probe (RPC-MIP) and the Langmuir probes (RPC-LAP), we estimate the cometary plasma density. We will present its spatial distribution around the comet when close to perihelion. Combined Mutual impedance and Langmuir probes density measurements are also compared to the density derived from particle measurements (RPC-ICA and RPC-IES). In addition, we will focus on localised, strong variations of the cometary plasma density over short timescales (~ minutes to seconds) observed during this period. These strong plasma density enhancements are interpreted taken into account the electron energy spectrum measured by the Ion and Electron Spectrometer (RPC-IES). Possible correlations of these plasma enhancements with variations in the magnetic field direction measured from the Magnetometer (RPC-MAG) will be discussed.

Published
2015

4. Cold and warm electrons at comet 67P/Churyumov-Gerasimenko

Author

Eriksson, Anders I., Engelhardt, Ilka. A. D., André, Mats, Boström, Rolf, Edberg, Niklas J. T., Johansson, Fredrik L., Odelstad, Elias, Vigren, Erik, Wahlund, Jan-Erik, Henri, P., Lebreton, J. -P, Miloch, W. J., Paulsson, J. J. P., Wedlund, Cyril Simon, Yang, L., Karlsson, T., Jarvinen, R., Broiles, Thomas, Mandt, K., Carr, C. M., Galand, M., Nilsson, H., Norberg, C., Eriksson, Anders I., Engelhardt, Ilka. A. D., André, Mats, Boström, Rolf, Edberg, Niklas J. T., Johansson, Fredrik L., Odelstad, Elias, Vigren, Erik, Wahlund, Jan-Erik, Henri, P., Lebreton, J. -P, Miloch, W. J., Paulsson, J. J. P., Wedlund, Cyril Simon, Yang, L., Karlsson, T., Jarvinen, R., Broiles, Thomas, Mandt, K., Carr, C. M., Galand, M., Nilsson, H., and Norberg, C.

Abstract

Context. Strong electron cooling on the neutral gas in cometary comae has been predicted for a long time, but actual measurements of low electron temperature are scarce. Aims. Our aim is to demonstrate the existence of cold electrons in the inner coma of comet 67P/Churyumov-Gerasimenko and show filamentation of this plasma. Methods. In situ measurements of plasma density, electron temperature and spacecraft potential were carried out by the Rosetta Langmuir probe instrument, LAP. We also performed analytical modelling of the expanding two-temperature electron gas. Results. LAP data acquired within a few hundred km from the nucleus are dominated by a warm component with electron temperature typically 5-10 eV at all heliocentric distances covered (1.25 to 3.83 AU). A cold component, with temperature no higher than about 0.1 eV, appears in the data as short (few to few tens of seconds) pulses of high probe current, indicating local enhancement of plasma density as well as a decrease in electron temperature. These pulses first appeared around 3 AU and were seen for longer periods close to perihelion. The general pattern of pulse appearance follows that of neutral gas and plasma density. We have not identified any periods with only cold electrons present. The electron flux to Rosetta was always dominated by higher energies, driving the spacecraft potential to order -10 V. Conclusions. The warm (5-10 eV) electron population observed throughout the mission is interpreted as electrons retaining the energy they obtained when released in the ionisation process. The sometimes observed cold populations with electron temperatures below 0.1 eV verify collisional cooling in the coma. The cold electrons were only observed together with the warm population. The general appearance of the cold population appears to be consistent with a Haser-like model, implicitly supporting also the coupling of ions to the neutral gas. The expanding cold plasma is unstable, forming filaments that we, Funding: The results presented here are only possible thanks to the combined efforts over 20 yr by many groups and individuals involved in Rosetta, including but not restricted to the ESA project teams at ESTEC, ESOC and ESAC and all people involved in designing, building, testing and operating RPC and LAP. We thank Kathrin Altwegg for discussions of the pulses in LAP and COPS. Rosetta is a European Space Agency (ESA) mission with contributions from its member states and the National Aeronautics and Space Administration (NASA). The work on RPC-LAP data was funded by the Swedish National Space Board under contracts 109/12, 171/12, 135/13, 166/14 and 168/15, and by Vetenskapsradet under contract 621-2013-4191. This work has made use of the AMDA and RPC Quicklook database, provided by a collaboration between the Centre de Donnees de la Physique des Plasmas CDPP (supported by CNRS, CNES, Observatoire de Paris and Universite Paul Sabatier, Toulouse), and Imperial College London (supported by the UK Science and Technology Facilities Council).

Published
2017
Full Text
View/download PDF

5. Statistical analysis of suprathermal electron drivers at 67P/Churyumov-Gerasimenko

Author

Broiles, Thomas W., Burch, J. L., Chae, K., Clark, G., Cravens, T. E., Eriksson, Anders, Fuselier, S. A., Frahm, R. A., Gasc, S., Goldstein, R., Henri, P., Koenders, C., Livadiotis, G., Mandt, K. E., Mokashi, P., Nemeth, Z., Odelstad, Elias, Rubin, M., Samara, M., Broiles, Thomas W., Burch, J. L., Chae, K., Clark, G., Cravens, T. E., Eriksson, Anders, Fuselier, S. A., Frahm, R. A., Gasc, S., Goldstein, R., Henri, P., Koenders, C., Livadiotis, G., Mandt, K. E., Mokashi, P., Nemeth, Z., Odelstad, Elias, Rubin, M., and Samara, M.

Abstract

We use observations from the Ion and Electron Sensor (IES) on board the Rosetta spacecraft to study the relationship between the cometary suprathermal electrons and the drivers that affect their density and temperature. We fit the IES electron observations with the summation of two kappa distributions, which we characterize as a dense and warm population (similar to 10 cm(-3) and similar to 16 eV) and a rarefied and hot population (similar to 0.01 cm(-3) and similar to 43 eV). The parameters of our fitting technique determine the populations' density, temperature, and invariant kappa index. We focus our analysis on the warm population to determine its origin by comparing the density and temperature with the neutral density and magnetic field strength. We find that the warm electron population is actually two separate sub-populations: electron distributions with temperatures above 8.6 eV and electron distributions with temperatures below 8.6 eV. The two sub-populations have different relationships between their density and temperature. Moreover, the two sub-populations are affected by different drivers. The hotter sub-population temperature is strongly correlated with neutral density, while the cooler sub-population is unaffected by neutral density and is only weakly correlated with magnetic field strength. We suggest that the population with temperatures above 8.6 eV is being heated by lower hybrid waves driven by counterstreaming solar wind protons and newly formed, cometary ions created in localized, dense neutral streams. To the best of our knowledge, this represents the first observations of cometary electrons heated through wave-particle interactions., QC 20200602

Published
2016
Full Text
View/download PDF

6. Statistical analysis of suprathermal electron drivers at 67P/Churyumov–Gerasimenko

Author

Broiles, Thomas W., primary, Burch, J. L., additional, Chae, K., additional, Clark, G., additional, Cravens, T. E., additional, Eriksson, A., additional, Fuselier, S. A., additional, Frahm, R. A., additional, Gasc, S., additional, Goldstein, R., additional, Henri, P., additional, Koenders, C., additional, Livadiotis, G., additional, Mandt, K. E., additional, Mokashi, P., additional, Nemeth, Z., additional, Odelstad, E., additional, Rubin, M., additional, and Samara, M., additional

Published
2016
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results