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154 results on '"Rucker, Helmut O."'

1. First observation of the solar Type III burst decay and its interpretation

Author

Melnik, Valentin N., Konovalenko, Alexandr A., Yerin, Sergey M., Bubnov, Igor M., Brazhenko, Anatoliy I., Frantsuzenko, Anatoliy V., Dorovskyy, Vladimir V., Shevchuk, Mykola V., and Rucker, Helmut O.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

A decay of Type III burst into two Type III bursts was registered during solar observations by GURT and URAN-2 radio telescopes on April 18, 2017. Such phenomenon was observed for the first time. Newborn Type III bursts have drift rates smaller than that of decaying Type III burst. Such decays of Type III bursts were predicted by a gas-dynamic theory of high-energy electron beams propagating through the thermal background plasma. In the frame of this theory Type III sources are beam-plasma structures moving with constant velocities. In our case the sum of velocities of newborn Type III sources equals the velocity of decaying Type III source. The last one is 0.33c in the case of fundamental radio emission and 0.2c at the harmonic radio emission of Type III burst. The density ratio of slow and fast newborn Type III sources is about 3., Comment: 11 pages, 5 figures

Published
2019
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4. Dispersion-like phenomena in Jovian decametric S-bursts: Tabooed Facts

Author

Arkhypov, Oleksiy V. and Rucker, Helmut O.

Subjects
Astrophysics - Earth and Planetary Astrophysics, Physics - Space Physics
Abstract

The dominant viewpoint on Jovian decametric S-burst emission neglects the time delay of the radiation, although its base theory of electron cyclotron maser instability allows a significant decreasing of X-mode group velocity near the cutoff frequency at the bottom of source region. We searched for effects of the frequency-related delay of radiation in broadband Jovian radio storms consisting of periodic S-bursts (S-burst trains) at 16 to 30 MHz. It was found that up to 1% of bursts in a train are of distorted meandering shape in dynamic spectrum, where the emission from one radio source was observed at several frequencies simultaneously. It is difficult to explain such spectra in terms of radio waves beaming or causality without significant frequency-related delay of radio emission. We found experimentally that the frequency drift rate of middle lines of such events coincides with the drift rate of disturbances in common S-bursts. This indicates a general distortion of the dynamic spectrum of S-bursts. As a result, the correlation method for the measurement of the spectral distortion is proposed. Using this method, we found the approximation coefficients for the distortion in 32 spectra of 8 Io-B storms. The corrected spectra formally show that S-burst trains do not move mainly outward from Jupiter, as it is usually assumed, but fly in the opposite direction. Our simulation confirms that the dispersion is capable in principle to reproduce the found spectral distortion. Hence, the dispersion-like phenomena in Jovian S-bursts deserve discussion because they have no satisfactory explanations in terms of traditional approach., Comment: 20 pages, 15 figures

Published
2014

10. Radio emission of supermassive hot Jupiters and giant free floating planets

Author

Weber, Christof, Erkaev, Nikolai, Ivanov, Viktor, Odert, Petra, Griessmeier, Jean-Mathias, Fossati, Luca, Lammer, Helmut, Rucker, Helmut O., and POTHIER, Nathalie

Subjects
[SDU] Sciences of the Universe [physics]
Abstract

In this study we explore if supermassive hot Jupiters can maintain source regions for radio emission, and if this emission can propagate to an observer outside the system. We study planets like Tau Bootis b (5.84 Jupiter masses and 1.06 Jupiter radii) at different orbital distances (between its real orbit of 0.046 and 0.2 au). The strong gravity of such a planet and efficient radiative cooling keeps the upper atmosphere in an (almost) hydrostatic state and the exobase stays very close to the planet. This makes it a good candidate for observations in the radio range. Conditions are expected to be similar as for Jupiter. Therefore, unlike hot Jupiters with lower mass, like HD 209458b and HD 189733b, supermassive hot Jupiters are expected to be in general better targets for radio observances. Furthermore, we investigate the object SIMP J01365662+0933473, which has recently been detected in the radio range, and is probably the first planetary mass object ever detected in radio. We study the possibility of a large moon or maybe planet in orbit, which would be a plasma source for the generation of the strong radio emission of this free floating planet/brown dwarf.

Published
2019

12. Neptune's non-thermal radio emissions - Phenomenology and source locations

Author

Rabl, Gerald K. F, Ladreiter, H.-P, Rucker, Helmut O, and Kaiser, Michael L

Subjects
Lunar And Planetary Exploration
Abstract

During the inbound and the outbound leg of Voyager 2's encounter with Neptune, the Planetary Radio Astronomy (PRA) experiment aboard the spacecraft detected short radio bursts at frequencies within the range of about 500-1300 kHz, and broad-banded smoothly varying emission patterns within the frequency range from about 40-800 kHz. Both emissions can be described in terms of a period of 16.1 hours determining Neptune's rotation period. Furthermore, just near closest approach, a narrow-banded smoothly varying radio component was observed occurring between 600 and 800 kHz. After giving a brief overview about some general characteristics of Neptune's nonthermal radio emission, the source locations of Neptune's emission components are determined, using an offset tilted dipole model for Neptune's magnetic field. Assuming that the emission originates near the electron gyrofrequency a geometrical beaming model is developed in order to fit the observed emission episodes.

Published
1992

42. Influence of the solar wind/interplanetary medium on Saturnian kilometric radiation

Author

Rucker, Helmut O and Desch, M. D

Subjects
Lunar And Planetary Exploration
Abstract

Previous studies on the periodicities of the Saturnian kilometric radiation (SKR) suggested a considerable solar wind influence on the occurrence of SKR, so it was obvious to investigate the relationship between parameters of the solar wind/interplanetary medium and this Saturnian radio component. Voyager 2 data from the Plasma Science experiment, the Magnetometer experiment and the Planetary Radio Astronomy experiment were used to analyze the external control of SKR. Out of the examined quantities known to be important in controlling magnetospheric processes this investigation yielded a dominance of the solar wind momentum, ram pressure and kinetic energy flux, in stimulating SKR and controlling its activity and emitted energy, and confirmed the results of the Voyager 1 analysis.

Published
1990

43. NenuFAR : instrument description and science case

Author

Zarka, Philippe, Tagger, Michel, Azarian, Sylvain, Barsuglia, Matteo, Boone, F, Bosma, Albert, Briand, Carine, Cecconi, Baptiste, Célestin, Sébastien, Combes, Françoise, Corbel, Stéphane, Courte, Cyril, Dallier, Richard, Dumez-Viou, Cédric, Ferrari, Chiara, Fialkov, A, Girard, Julien N., Grießmeier, Jean-Mathias, Lamy, Laurent, Lanz, T, Levrier, F., Panchenko, M., Pandey-Pommier, M, Tasse, Cyril, Torchinsky, Steve, Atemkeng, M, Bonafede, A, Boyer, R, Branchesi, Marica, Chassande-Mottin, E, Coffre, Andrée, Cognard, Ismael, Dabbech, A, Denis, Laurent, El Korso, M. N., Falgarone, Edith, Ferrari, A, Ferrière, Katia, Fevotte, C, Fullekrug, M, Guiderdoni, Bruno, Guillemot, Lucas, Hess, Sébastien L G, Hessels, J, Kondratiev, Vlad, Konovalenko, A, Koopmans, Leon, Larzabal, P, Lehnert, M, Loh, Alan, Macario, G, Maintoux, J, Maintoux, J J, Martin, Lilian, Masson, Sophie, Miville-Deschenes, Marc-Antoine, Oberoi, D, Petiteau, Antoine, Pinçon, Jean-Louis, Revenu, B, Rible, F, Richard, C, Rucker, Helmut O, Salomé, Philippe, Semelin, Benoit, Serylak, Maciej, Smirnov, Oleg, Stappers, B, Theureau, Gilles, van Driel, Wim, Vaubaillon, Jérémie, Vazza, F, Vergani, S, and Was, M

Subjects
Radioastronomy, Low Frequency
Abstract

This document presents the NenuFAR (New Extension in Nançay Upgrading LOFAR) science case.&nbsp

Published
2014
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44. Study of empirical electron density models using stereoscopic observations of solar Type III burst

Author

Boudjada, Mohammed Y., Al-Haddad, Emad, Galopeau, Patrick H. M., Maksimovic, Milan, Rucker, Helmut O., Cardon, Catherine, Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), University of Applied Sciences [Graz], HELIOS - 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), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Physics::Space Physics, [SDU.ASTR.SR] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics
Abstract

International audience; We study the properties of solar Type III radio bursts that were simultaneously observed by RPWS/Cassini, URAP/Ulysses and WAVES/Wind experiments. The observations covered a time interval of about one year during which the spacecraft trajectories where localized in the ecliptic plane for Wind and Cassini, and at high heliographic latitudes (of about -75°) for Ulysses spacecraft. The data set consists of the flux density and the arrival time as a function of frequency in the range of a few kHz to 16 MHz. This leads us to determine the time profiles associated to the electron beam evolution along the interplanetary magnetic field where the trajectory is supposed to be an Archimedean spiral. We assume that the trajectories are contained in the plane of the ecliptic and the velocity of the solar wind is constant and equal to 400 km/s. Several empirical models of electron density are considered in the estimation of the electron beam evolution. We show that some of these models may be used to outline the real Type III burst trajectory, and others not. We discuss the particularity of each model and we attempt to classify them taking into consideration the different regions where the radio was propagating, i.e. the solar corona (few solar radii) and the interplanetary medium up to the orbit of the Earth (~ 1 AU) and Jupiter (~ 5 AU).

Published
2014

45. Juno model rheometry and simulation

Author

Sampl, Manfred, primary, Macher, Wolfgang, additional, Oswald, Thomas, additional, Plettemeier, Dirk, additional, Rucker, Helmut O., additional, and Kurth, William S., additional

Published
2016
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48. AKR modulations controlled by Earth's rotation, as observed by STEREO

Author

Panchenko, Mykhaylo, Khodachenko, Maxim L., Kislyakov, A. G., Rucker, Helmut O., Hanasz, J., Zarka, Philippe, Kaiser, Michael L., Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-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 Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Physique des plasmas, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2008

49. The search of planetary and stellar decameter wavelength radio emissions by the use of the world largest radio telescope

Author

Konovalenko, Alexander A., Rucker, Helmut O., Lecacheux, Alain, Zarka, Philippe, Grießmeier, Jean-Mathias, Melnik, Valentin N., Et Al., Et Al., Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-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 Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Physique des plasmas, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2008

50. LOFAR-CM: A low frequency array station in the Carpathian Mountains

Author

Rucker, Helmut O., Karlsson, R., Konovalenko, Alexander A., Zarka, Philippe, Oswald, T. H., Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-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 Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Physique des plasmas, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2008

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