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S M Krimigis - One of the best experts on this subject based on the ideXlab platform.
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drift resonant relativistic electron acceleration at the Outer Planets insights from the response of saturn s radiation belts to magnetospheric storms
Icarus, 2018Co-Authors: Elias Roussos, D C Hamilton, P Kollmann, N Krupp, C Paranicas, K Dialynas, N Sergis, D G Mitchell, S M KrimigisAbstract:Abstract The short, 7.2-day orbital period of Cassini’s Ring Grazing Orbits (RGO) provided an opportunity to monitor how fast the effects of an intense magnetospheric storm-time period (days 336–343/2016) propagated into Saturn’s electron radiation belts. Following the storms, Cassini’s MIMI/LEMMS instrument detected a transient extension of the electron radiation belts that in subsequent orbits moved towards the inner belts, intensifying them in the process. This intensification was followed by an equally fast decay, possibly due to the rapid absorption of MeV electrons by the planet’s main rings. Surprisingly, all this cycle was completed within four RGOs, effectively in less than a month. That is considerably faster than the year-long time scales of Saturn’s proton radiation belt evolution. In order to explain this difference, we propose that electron radial transport is partly controlled by the variability of global scale electric fields which have a fixed local time pointing. Such electric fields may distort significantly the orbits of a particular class of energetic electrons that cancel out magnetospheric corotation due to their westward gradient and curvature drifts (termed “corotation-resonant” or “local-time stationary” electrons) and transport them radially between the ring current and the radiation belts within several days and few weeks. The significance of the proposed process is highlighted by the fact that corotation resonance at Saturn occurs for electrons of few hundred keV to several MeV. These are the characteristic energies of seed electrons from the ring current that sustain the radiation belts of the planet. Our model’s feasibility is demonstrated through the use of a simple test-particle simulation, where we estimate that uniform but variable electric fields with magnitudes lower that 1.0 mV/m can lead to a very efficient transport of corotation resonant electrons. Such electric fields have been consistently measured in the magnetosphere, and here we provide additional evidence showing that they may be constantly present all the way down to the Outer edge of Saturn’s main rings, further supporting our model. The implications of our findings are not limited to Saturn. Corotation resonance at Jupiter occurs for electrons with energies above about 10 MeV throughout the quasi-dipolar, energetic particle-trapping region of the magnetosphere. The proposed process could in principle then lead to rapid transport and adiabatic acceleration electrons into ultra-relativistic energies. The observation by Galileo’s EPD/LEMMS instrument of an intense Jovian acceleration event at the orbital distance of Ganymede during the mission’s C22 orbit, when > 11 MeV electron fluxes were preferentially enhanced, provides additional support to our transport model and insights on the origin of that orbit’s extreme energetic electron environment. Finally, if the mode of radial transport that we describe here is a dominant one, radial diffusion coefficients (DLL) would be subject to strong energy, pitch angle and species dependencies.
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saturn s magnetosphere an example of dynamic planetary systems
MODERN CHALLENGES IN NONLINEAR PLASMA PHYSICS: A Festschrift Honoring the Career of Dennis Papadopoulos, 2011Co-Authors: S M KrimigisAbstract:Planetary magnetospheres are prime examples of interacting plasma regimes at different scales. There is the principal interaction with the solar wind that seems to be the main driver of the dynamics at Mercury and Earth. But these inner planet magnetospheres are relatively simple when compared to those of the Outer Planets which are primarily driven by planetary rotation and include internal plasma sources from various moons and rings, in addition to those from the planetary ionospheres and the solar wind. Io’s volcanic source at Jupiter is a prime example, but now Enceladus at Saturn has joined the fray, while Titan is a surprisingly minor player despite its thick nitrogen atmosphere and its continued bombardment by energetic particles. Mass loading of plasma leads to interchange instability in the inner magnetospheres at both Jupiter and Saturn, while ionospheric slippage, among other processes, seems to contribute to a variable rotation period in the spin‐aligned dipole field of Saturn, manifested in a...
Debra A Fischer - One of the best experts on this subject based on the ideXlab platform.
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stellar spin orbit alignment for kepler 9 a multi transiting planetary system with two Outer Planets near 2 1 resonance
The Astronomical Journal, 2018Co-Authors: Songhu Wang, Brett C Addison, Debra A Fischer, John M Brewer, Howard Isaacson, Andrew W Howard, Gregory LaughlinAbstract:We present spectroscopic measurements of the Rossiter–McLaughlin effect for the planet b of the Kepler-9 multi-transiting planetary system. The resulting sky-projected spin–orbit angle is λ = −13° ± 16°, which favors an aligned system and strongly disfavors highly misaligned, polar, and retrograde orbits. Including Kepler-9, there are now a total of four Rossiter–McLaughlin effect measurements for multiplanet systems, all of which are consistent with spin–orbit alignment.
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stellar spin orbit alignment for kepler 9 a multi transiting planetary system with two Outer Planets near 2 1 resonance
arXiv: Earth and Planetary Astrophysics, 2017Co-Authors: Songhu Wang, Brett C Addison, Debra A Fischer, John M Brewer, Howard Isaacson, Andrew W Howard, Gregory LaughlinAbstract:We present spectroscopic measurements of the Rossiter-McLaughlin effect for the planet b of Kepler-9 multi-transiting planet system. The resulting sky-projected spin-orbit angle is $\lambda=-13^{\circ} \pm 16^{\circ}$, which favors an aligned system and strongly disfavors highly misaligned, polar, and retrograde orbits. Including Kepler-9, there are now a total of 4 Rossiter-McLaughlin effect measurements for multiplanet systems, all of which are consistent with spin-orbit alignment.
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planet hunters vi an independent characterization of koi 351 and several long period planet candidates from the kepler archival data
The Astronomical Journal, 2014Co-Authors: Joseph R Schmitt, Debra A Fischer, Ji Wang, Kian J Jek, John C Moriarty, Tabetha S Boyajian, Megan E Schwamb, Chris Lintott, Stuart Lynn, Arfon M SmithAbstract:We report the discovery of 14 new transiting planet candidates in the Kepler field from the Planet Hunters citizen science program. None of these candidates overlapped with Kepler Objects of Interest (KOIs) at the time of submission. We report the discovery of one more addition to the six planet candidate system around KOI-351, making it the only seven planet candidate system from Kepler. Additionally, KOI-351 bears some resemblance to our own solar system, with the inner five Planets ranging from Earth to mini-Neptune radii and the Outer Planets being gas giants; however, this system is very compact, with all seven planet candidates orbiting 1 AU from their host star. A Hill stability test and an orbital integration of the system shows that the system is stable. Furthermore, we significantly add to the population of long period transiting Planets; periods range from 124 to 904 days, eight of them more than one Earth year long. Seven of these 14 candidates reside in their host star's habitable zone.
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planet hunters vi an independent characterization of koi 351 and several long period planet candidates from the kepler archival data
The Astronomical Journal, 2014Co-Authors: Joseph R Schmitt, Debra A Fischer, Ji Wang, Tabetha S Boyajian, Megan E Schwamb, Chris Lintott, Stuart Lynn, Arfon M Smith, John Moriarty, Michael ParrishAbstract:We report the discovery of 14 new transiting planet candidates in the Kepler field from the Planet Hunters citizen science program. None of these candidates overlapped with Kepler Objects of Interest (KOIs) at the time of submission. We report the discovery of one more addition to the six planet candidate system around KOI-351, making it the only seven planet candidate system from Kepler. Additionally, KOI-351 bears some resemblance to our own solar system, with the inner five Planets ranging from Earth to mini-Neptune radii and the Outer Planets being gas giants; however, this system is very compact, with all seven planet candidates orbiting 1 AU from their host star. A Hill stability test and an orbital integration of the system shows that the system is stable. Furthermore, we significantly add to the population of long period transiting Planets; periods range from 124 to 904 days, eight of them more than one Earth year long. Seven of these 14 candidates reside in their host star's habitable zone.
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planet hunters vi an independent characterization of koi 351 and several long period planet candidates from the kepler archival data
arXiv: Earth and Planetary Astrophysics, 2013Co-Authors: Joseph R Schmitt, Debra A Fischer, Ji Wang, Kian J Jek, John C Moriarty, Tabetha S Boyajian, Megan E Schwamb, Chris Lintott, Stuart Lynn, Arfon M SmithAbstract:We report the discovery of 14 new transiting planet candidates in the Kepler field from the Planet Hunters citizen science program. None of these candidates overlapped with Kepler Objects of Interest (KOIs) at the time of submission. We report the discovery of one more addition to the six planet candidate system around KOI-351, making it the only seven planet candidate system from Kepler. Additionally, KOI-351 bears some resemblance to our own solar system, with the inner five Planets ranging from Earth to mini-Neptune radii and the Outer Planets being gas giants; however, this system is very compact, with all seven planet candidates orbiting $\lesssim 1$ AU from their host star. A Hill stability test and an orbital integration of the system shows that the system is stable. Furthermore, we significantly add to the population of long period transiting Planets; periods range from 124-904 days, eight of them more than one Earth year long. Seven of these 14 candidates reside in their host star's habitable zone.
Gregory Laughlin - One of the best experts on this subject based on the ideXlab platform.
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stellar spin orbit alignment for kepler 9 a multi transiting planetary system with two Outer Planets near 2 1 resonance
The Astronomical Journal, 2018Co-Authors: Songhu Wang, Brett C Addison, Debra A Fischer, John M Brewer, Howard Isaacson, Andrew W Howard, Gregory LaughlinAbstract:We present spectroscopic measurements of the Rossiter–McLaughlin effect for the planet b of the Kepler-9 multi-transiting planetary system. The resulting sky-projected spin–orbit angle is λ = −13° ± 16°, which favors an aligned system and strongly disfavors highly misaligned, polar, and retrograde orbits. Including Kepler-9, there are now a total of four Rossiter–McLaughlin effect measurements for multiplanet systems, all of which are consistent with spin–orbit alignment.
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stellar spin orbit alignment for kepler 9 a multi transiting planetary system with two Outer Planets near 2 1 resonance
arXiv: Earth and Planetary Astrophysics, 2017Co-Authors: Songhu Wang, Brett C Addison, Debra A Fischer, John M Brewer, Howard Isaacson, Andrew W Howard, Gregory LaughlinAbstract:We present spectroscopic measurements of the Rossiter-McLaughlin effect for the planet b of Kepler-9 multi-transiting planet system. The resulting sky-projected spin-orbit angle is $\lambda=-13^{\circ} \pm 16^{\circ}$, which favors an aligned system and strongly disfavors highly misaligned, polar, and retrograde orbits. Including Kepler-9, there are now a total of 4 Rossiter-McLaughlin effect measurements for multiplanet systems, all of which are consistent with spin-orbit alignment.
Arfon M Smith - One of the best experts on this subject based on the ideXlab platform.
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planet hunters vi an independent characterization of koi 351 and several long period planet candidates from the kepler archival data
The Astronomical Journal, 2014Co-Authors: Joseph R Schmitt, Debra A Fischer, Ji Wang, Kian J Jek, John C Moriarty, Tabetha S Boyajian, Megan E Schwamb, Chris Lintott, Stuart Lynn, Arfon M SmithAbstract:We report the discovery of 14 new transiting planet candidates in the Kepler field from the Planet Hunters citizen science program. None of these candidates overlapped with Kepler Objects of Interest (KOIs) at the time of submission. We report the discovery of one more addition to the six planet candidate system around KOI-351, making it the only seven planet candidate system from Kepler. Additionally, KOI-351 bears some resemblance to our own solar system, with the inner five Planets ranging from Earth to mini-Neptune radii and the Outer Planets being gas giants; however, this system is very compact, with all seven planet candidates orbiting 1 AU from their host star. A Hill stability test and an orbital integration of the system shows that the system is stable. Furthermore, we significantly add to the population of long period transiting Planets; periods range from 124 to 904 days, eight of them more than one Earth year long. Seven of these 14 candidates reside in their host star's habitable zone.
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planet hunters vi an independent characterization of koi 351 and several long period planet candidates from the kepler archival data
The Astronomical Journal, 2014Co-Authors: Joseph R Schmitt, Debra A Fischer, Ji Wang, Tabetha S Boyajian, Megan E Schwamb, Chris Lintott, Stuart Lynn, Arfon M Smith, John Moriarty, Michael ParrishAbstract:We report the discovery of 14 new transiting planet candidates in the Kepler field from the Planet Hunters citizen science program. None of these candidates overlapped with Kepler Objects of Interest (KOIs) at the time of submission. We report the discovery of one more addition to the six planet candidate system around KOI-351, making it the only seven planet candidate system from Kepler. Additionally, KOI-351 bears some resemblance to our own solar system, with the inner five Planets ranging from Earth to mini-Neptune radii and the Outer Planets being gas giants; however, this system is very compact, with all seven planet candidates orbiting 1 AU from their host star. A Hill stability test and an orbital integration of the system shows that the system is stable. Furthermore, we significantly add to the population of long period transiting Planets; periods range from 124 to 904 days, eight of them more than one Earth year long. Seven of these 14 candidates reside in their host star's habitable zone.
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planet hunters vi an independent characterization of koi 351 and several long period planet candidates from the kepler archival data
arXiv: Earth and Planetary Astrophysics, 2013Co-Authors: Joseph R Schmitt, Debra A Fischer, Ji Wang, Kian J Jek, John C Moriarty, Tabetha S Boyajian, Megan E Schwamb, Chris Lintott, Stuart Lynn, Arfon M SmithAbstract:We report the discovery of 14 new transiting planet candidates in the Kepler field from the Planet Hunters citizen science program. None of these candidates overlapped with Kepler Objects of Interest (KOIs) at the time of submission. We report the discovery of one more addition to the six planet candidate system around KOI-351, making it the only seven planet candidate system from Kepler. Additionally, KOI-351 bears some resemblance to our own solar system, with the inner five Planets ranging from Earth to mini-Neptune radii and the Outer Planets being gas giants; however, this system is very compact, with all seven planet candidates orbiting $\lesssim 1$ AU from their host star. A Hill stability test and an orbital integration of the system shows that the system is stable. Furthermore, we significantly add to the population of long period transiting Planets; periods range from 124-904 days, eight of them more than one Earth year long. Seven of these 14 candidates reside in their host star's habitable zone.
Richard S Lindze - One of the best experts on this subject based on the ideXlab platform.
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gravitational tides in the Outer Planets i implications of classical tidal theory ii interior calculations and estimation of the tidal dissipation factor
The Astrophysical Journal, 1993Co-Authors: Petros J Ioannou, Richard S LindzeAbstract:Classical tidal theory is applied to the gravitational excitation of the atmospheres of the gaseous Planets. The only departure made from classical theory is the retention of the effects of nonhdrostaticity which are important in the deeper atmosphere or wherever one expects extremely small static stability. The meridional structure of the tidal response is shown to depend only on the ratio of the period of gravitational forcing to the period of rotation of the planet. Forcing by the low-inclination orbits of the satellites of Jupiter, Saturn, and Uranus excites primarily symmetric Hough modes. Consideration of the vertical structure equation shows that altho4gh the gravitational tidal forcing is proportional to the first symmetric spherical harmonic with zonal wavenumber 2, the tidal response will be concentrated in higher order meridional structures confined equatorward of 50° N on Jupiter, 76° N on Saturn, and 45° N on Uranus. The meridional structure of these modes resembles the visible banding on these Planets. The excitation of the tides depends on the distribution of static stability in the interior. Estimates are made showing that observation of the tidal response of the Planets at the visible cloud level may be within reach of current observational capability. Detection of this signal is shown to provide information about the thermodynamic structure of the interior. A primary purpose of the present paper, in addition to the above, is the presentation of computational results concerning the eigenvalues and eigenfunctions relevant to gravitational tides in the Outer Planets. Subject headings: Planets and satellites: general
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gravitational tides in the Outer Planets ii interior calculations and estimation of the tidal dissipation factor
The Astrophysical Journal, 1993Co-Authors: Petros J Ioannou, Richard S LindzeAbstract:The theory of excitation of tidal oscillations in a fluid planetary body is formulated, and separable equa tions are derived that extend the results of the classical theory of tides to the nonhydrostatic interiors of Planets. The theory is applied to the example of the gravitational tidal response of Jupiter to forcing by lo. The tidal response is found to crucially depend on the static stability in the interior of the planet, the response of the planet being as much as two to three orders of magnitude greater than the response with a neutral interior. The tidal dissipation factor Q is calculated for Jupiter and found to agree with the values required by the astronomical arguments only if the interior has finite (though small static stability. We are led to the conclusion that the interior of Jupiter must have regions which are stably stratified. Subject headings: Planets and satellites: individual (Jupiter) Jupiter has a rotational period of 9.92 hr and a radius approximately 10 times greater than Earth's and 10 times smaller than the Sun's. The main constituents of the plant, hydrogen (90% by mass) and helium (10%), do not solidify, and because of the low density the mass of the planet is only 318 times greater than Earth's. The planet is primarily made up of a highly compressed but relatively cold liquid, with an inte rior core at probably 0.1 of the planetary radius. The visible atmospheric envelope is approximately at a pressure of 1 bar and a temperature of 150 K, while the pressure at the core is approximately 40 Mbar at a temperature of nearly 20,000 K (Stevenson 1978). Observations on the thermal emission revealed the existence of an interior heat source which accounts for around 35°/o of the 14 W m- 2 emitted to space. While much progress has been made in our understanding of the general structure of the planet (cf. Stevenson 1978), most of the meteorologically relevant information is limited to the region above the visible clouds of the planet. The data for the meteorology of the planet is still scant, making the theories for the observed cloud level circulations speculative (Ingersoll
