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Scott B Gaudi - One of the best experts on this subject based on the ideXlab platform.
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observational constraints on trojans of transiting Extrasolar Planets
The Astrophysical Journal, 2006Co-Authors: Eric B Ford, Scott B GaudiAbstract:Theoretical studies predict that Trojans are likely a frequent by-product of planet formation and evolution. We present a novel method of detecting Trojan companions to transiting Extrasolar Planets that involves comparing the midtime of eclipse with the time of the stellar reflex velocity null. We demonstrate that this method offers the potential to detect terrestrial-mass Trojans using existing ground-based observatories. This method rules out Trojan companions to HD 209458b and HD 149026b more massive than13 and 25 at a 99.9% confidence M level. Such a Trojan would be dynamically stable, would not yet have been detected by photometric or spectroscopic monitoring, and would be unrecognizable from radial velocity observations alone. We outline the future prospects for this method and show that the detection of a “Hot Trojan” of any mass would place a significant constraint on theories of orbital migration. Subject headings: celestial mechanics — planetary systems: formation — techniques: photometric — techniques: radial velocities
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observational constraints on trojans of transiting Extrasolar Planets
arXiv: Astrophysics, 2006Co-Authors: Eric B Ford, Scott B GaudiAbstract:Theoretical studies predict that Trojans are likely a frequent byproduct of planet formation and evolution. We present a novel method of detecting Trojan companions to transiting Extrasolar Planets which involves comparing the time of central eclipse with the time of the stellar reflex velocity null. We demonstrate that this method offers the potential to detect terrestrial-mass Trojans using existing ground-based observatories. This method rules out Trojan companions to HD 209458b and HD 149026b more massive than ~13 Earth masses and \~25 Earth masses at a 99.9% confidence level. Such a Trojan would be dynamically stable, would not yet have been detected by photometric or spectroscopic monitoring, and would be unrecognizable from radial velocity observations alone. We outline the future prospects for this method, and show that the detection of a "Hot Trojan" of any mass would place a significant constraint on theories of orbital migration.
William M. Farrell - One of the best experts on this subject based on the ideXlab platform.
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Magnetospheric Emission from Extrasolar Planets
Astrophysics, 2009Co-Authors: Joseph Lazio, T. S. Bastian, William M. Farrell, G. Bryden, J. M. Griessmeier, Gregg Hallinan, J. C. Kasper, Thomas B. H. Kuiper, A. Lecacheux, W. MajidAbstract:Abstract : The magnetospheric emissions from Extrasolar Planets represent a science frontier for the next decade. All of the solar system giant Planets and the Earth produce radio emissions as a result of interactions between their magnetic fields and the solar wind. In the case of the Earth, its magnetic field may contribute to its habitability by protecting its atmosphere from solar wind erosion and by preventing energetic particles from reaching its surface. Indirect evidence for at least some Extrasolar giant Planets also having magnetic fields includes the modulation of emission lines of their host stars phased with the planetary orbits, likely due to interactions between the stellar and planetary magnetic fields. If magnetic fields are a generic property of giant Planets, then Extrasolar giant Planets should emit at radio wavelengths allowing for their direct detection. Existing observations place limits comparable to the flux densities expected from the strongest emissions. Additional sensitivity at low radio frequencies coupled with algorithmic improvements likely will enable a new means of detection and characterization of Extrasolar Planets within the next decade.
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Radio Detection of Extrasolar Planets: Present and Future Prospects
2004Co-Authors: T. Joseph W. Lazio, William M. FarrellAbstract:The five “magnetic” Planets in the solar system (Earth and the four gas giants) emit at radio frequencies because solar-wind powered electron currents deposit energy in their magnetic polar regions. We summarize predictions of the radio emission from the known Extrasolar Planets and initial detection efforts. Most of the known Extrasolar Planets should emit in the frequency range 10–1000 MHz and, under favorable circumstances, some may have flux densities above 0.1 Jy. The current limits set by observations with the Very Large Array (VLA) and the Giant Metrewave Radio Telescope (GMRT) are consistent with but generally do not provide strong constraints on the predictions. Future radio telescopes, such as the Long Wavelength Array (LWA), the Mileura Widefield Array (MWA), Low Frequency Array (LOFAR) and the Square Kilometer Array (SKA), should be able to detect the known Extrasolar Planets or place austere limits on their radio emission. Planets with masses much lower than those in the current census will probably radiate below 10 MHz and will require a space-based array.
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The Radiometric Bode's Law and Extrasolar Planets
arXiv: Astrophysics, 2004Co-Authors: T. Joseph W. Lazio, William M. Farrell, Jill Dietrick, Elizabeth Greenlees, Emily Hogan, Christopher Jones, L. A. HennigAbstract:We predict the radio flux densities of the Extrasolar Planets in the current census, making use of an empirical relation--the radiometric Bode's Law--determined from the five ``magnetic'' Planets in the solar system (Earth and the four gas giants). Radio emission from these Planets results from solar-wind powered electron currents depositing energy in the magnetic polar regions. We find that most of the known Extrasolar Planets should emit in the frequency range 10--1000 MHz and, under favorable circumstances, have typical flux densities as large as 1 mJy. We also describe an initial, systematic effort to search for radio emission in low radio frequency images acquired with the Very Large Array. The limits set by the VLA images (~ 300 mJy) are consistent with, but do not provide strong constraints on, the predictions of the model. Future radio telescopes, such as the Low Frequency Array (LOFAR) and the Square Kilometer Array (SKA), should be able to detect the known Extrasolar Planets or place austere limits on their radio emission. Planets with masses much lower than those in the current census will probably radiate below 10 MHz and will require a space-based array.
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The Radiometric Bode’s Law and Extrasolar Planets
The Astrophysical Journal, 2004Co-Authors: T. Joseph W. Lazio, William M. Farrell, Jill Dietrick, Elizabeth Greenlees, Emily Hogan, Christopher Jones, L. A. HennigAbstract:We predict the radio flux densities of the Extrasolar Planets in the current census, making use of an empirical relation—the radiometric Bode's law—determined from the five "magnetic" Planets in the solar system (the Earth and the four gas giants). Radio emission from these Planets results from solar wind-powered electron currents depositing energy in the magnetic polar regions. We find that most of the known Extrasolar Planets should emit in the frequency range 10-1000 MHz and, under favorable circumstances, have typical flux densities as large as 1 mJy. We also describe an initial, systematic effort to search for radio emission in low radio frequency images acquired with the Very Large Array (VLA). The limits set by the VLA images (≈300 mJy) are consistent with, but do not provide strong constraints on, the predictions of the model. Future radio telescopes, such as the Low Frequency Array and the Square Kilometer Array, should be able to detect the known Extrasolar Planets or place austere limits on their radio emission. Planets with masses much lower than those in the current census will probably radiate below 10 MHz and will require a space-based array.
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The radio search for Extrasolar Planets with LOFAR
Planetary and Space Science, 2004Co-Authors: William M. Farrell, M. D. Desch, P. Zarka, T. J. W. Lazio, T. J. Bastian, B.p. RyabovAbstract:Abstract The Low Frequency Array (LOFAR) will come on line with unprecedented radio sensitivity and resolution between 10 and 240 MHz. Such a system will provide a factor of 10–30 improvement in sensitivity in the pursuit of the weak radio emission from Extrasolar Planets. To date, previous examinations of Extrasolar planetary systems with the most advanced radio telescopes have yielded a negative result. However, the improvement in sensitivity by LOFAR over current systems will increase the likelihood of Extrasolar planet detection in the radio. We apply radiometric models derived previously from the study of Planets in our solar system to the known Extrasolar Planets, and demonstrate that approximately 3–5 of them should emit in the proper frequency range and with enough power to possibly become detectable at Earth with LOFAR.
Dimitar D Sasselov - One of the best experts on this subject based on the ideXlab platform.
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tidal evolution of close in Extrasolar Planets high stellar q from new theoretical models
The Astrophysical Journal, 2011Co-Authors: K Penev, Dimitar D SasselovAbstract:In recent years it has been shown that the tidal coupling between Extrasolar Planets and their stars could be an important mechanism leading to orbital evolution. Both the tides the planet raises on the star and vice versa are important and dissipation efficiencies ranging over four orders of magnitude are being used. In addition, the discovery of Extrasolar Planets extremely close to their stars has made it clear that the estimates of the tidal quality factor, Q, of the stars based on Jupiter and its satellite system and on main-sequence binary star observations are too low, resulting in lifetimes for the closest Planets orders of magnitude smaller than their age. We argue that those estimates of the tidal dissipation efficiency are not applicable for stars with spin periods much longer than the Extrasolar Planets' orbital period. We address the problem by applying our own values for the dissipation efficiency of tides, based on our numerical simulations of externally perturbed volumes of stellar-like convection. The range of dissipation we find for main-sequence stars corresponds to stellar Q{sub *} of 10{sup 8} to 3 x 10{sup 9}. The derived orbit lifetimes are comparable to or much longer than the ages of themore » observed Extrasolar planetary systems. The predicted orbital decay transit timing variations due to the tidal coupling are below the rate of ms yr{sup -1} for currently known systems, but within reach of an extended Kepler mission provided such objects are found in its field.« less
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tidal evolution of close in Extrasolar Planets high stellar q from new theoretical models
arXiv: Solar and Stellar Astrophysics, 2011Co-Authors: K Penev, Dimitar D SasselovAbstract:In recent years it has been shown that the tidal coupling between Extrasolar Planets and their stars could be an important mechanism leading to orbital evolution. Both the tides the planet raises on the star and vice versa are important and dissipation efficiencies ranging over four orders of magnitude are being used. In addition, the discovery of Extrasolar Planets extremely close to their stars has made it clear that the estimates of the tidal quality factor, Q, of the stars based on Jupiter and its satellite system and on main sequence binary star observations are too low, resulting in lifetimes for the closest Planets orders of magnitude smaller than their age. We argue that those estimates of the tidal dissipation efficiency are not applicable for stars with spin periods much longer than the Extrasolar Planets' orbital period. We address the problem by applying our own values for the dissipation efficiency of tides, based on our numerical simulations of externally perturbed volumes of stellar-like convection. The range of dissipation we find for main-sequence stars corresponds to stellar $Q_*$ of $10^8$ to $3{\times}10^9$. The derived orbit lifetimes are comparable to, or much longer than the ages of the observed Extrasolar planetary systems. The predicted orbital decay transit timing variations due to the tidal coupling are below the rate of ms/yr for currently known systems, but within reach of an extended Kepler mission provided such objects are found in its field.
Eric B Ford - One of the best experts on this subject based on the ideXlab platform.
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using transit timing observations to search for trojans of transiting Extrasolar Planets
arXiv: Astrophysics, 2007Co-Authors: Eric B Ford, Matthew J HolmanAbstract:Theoretical studies predict that Trojans are likely a frequent byproduct of planet formation and evolution. We examine the sensitivity of transit timing observations for detecting Trojan companions to transiting Extrasolar Planets. We demonstrate that this method offers the potential to detect terrestrial-mass Trojans using existing ground-based observatories. We compare the transit timing variation (TTV) method with other techniques for detecting Extrasolar Trojans and outline the future prospects for this method.
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origins of eccentric Extrasolar Planets testing the planet planet scattering model
arXiv: Astrophysics, 2007Co-Authors: Eric B Ford, Frederic A RasioAbstract:(Abridged) In planetary systems with two or more giant Planets, dynamical instabilities can lead to collisions or ejections through strong planet--planet scattering. Previous studies for simple initial configurations with two equal-mass Planets revealed some discrepancies between the results of numerical simulations and the observed orbital elements of Extrasolar Planets. Here, we show that simulations with two unequal mass Planets starting on nearly circular orbits predict a reduced frequency of collisions and a broader range of final eccentricities. The two-planet scattering model can easily reproduce the observed eccentricities with a plausible distribution of planet mass ratios. Further, the two-planet scattering model predicts a maximum eccentricity of about 0.8, independent of the distribution of planet mass ratios, provided that both Planets are initially place on nearly circular orbits. This compares favorably with current observations and will be tested by future planet discoveries. The combination of planet--planet scattering and tidal circularization may be able to explain the existence of some giant Planets with very short period orbits. Orbital migration due to planet scattering could play an important role in explaining the increased rate of giant Planets with very short period orbits. We also re-examine and discuss various possible correlations between eccentricities and other properties of observed Extrasolar Planets. We demonstrate that the observed distribution of planet masses, orbital periods, and eccentricities can provide constraints for models of planet formation and evolution.
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observational constraints on trojans of transiting Extrasolar Planets
The Astrophysical Journal, 2006Co-Authors: Eric B Ford, Scott B GaudiAbstract:Theoretical studies predict that Trojans are likely a frequent by-product of planet formation and evolution. We present a novel method of detecting Trojan companions to transiting Extrasolar Planets that involves comparing the midtime of eclipse with the time of the stellar reflex velocity null. We demonstrate that this method offers the potential to detect terrestrial-mass Trojans using existing ground-based observatories. This method rules out Trojan companions to HD 209458b and HD 149026b more massive than13 and 25 at a 99.9% confidence M level. Such a Trojan would be dynamically stable, would not yet have been detected by photometric or spectroscopic monitoring, and would be unrecognizable from radial velocity observations alone. We outline the future prospects for this method and show that the detection of a “Hot Trojan” of any mass would place a significant constraint on theories of orbital migration. Subject headings: celestial mechanics — planetary systems: formation — techniques: photometric — techniques: radial velocities
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observational constraints on trojans of transiting Extrasolar Planets
arXiv: Astrophysics, 2006Co-Authors: Eric B Ford, Scott B GaudiAbstract:Theoretical studies predict that Trojans are likely a frequent byproduct of planet formation and evolution. We present a novel method of detecting Trojan companions to transiting Extrasolar Planets which involves comparing the time of central eclipse with the time of the stellar reflex velocity null. We demonstrate that this method offers the potential to detect terrestrial-mass Trojans using existing ground-based observatories. This method rules out Trojan companions to HD 209458b and HD 149026b more massive than ~13 Earth masses and \~25 Earth masses at a 99.9% confidence level. Such a Trojan would be dynamically stable, would not yet have been detected by photometric or spectroscopic monitoring, and would be unrecognizable from radial velocity observations alone. We outline the future prospects for this method, and show that the detection of a "Hot Trojan" of any mass would place a significant constraint on theories of orbital migration.
L. A. Hennig - One of the best experts on this subject based on the ideXlab platform.
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The Radiometric Bode's Law and Extrasolar Planets
arXiv: Astrophysics, 2004Co-Authors: T. Joseph W. Lazio, William M. Farrell, Jill Dietrick, Elizabeth Greenlees, Emily Hogan, Christopher Jones, L. A. HennigAbstract:We predict the radio flux densities of the Extrasolar Planets in the current census, making use of an empirical relation--the radiometric Bode's Law--determined from the five ``magnetic'' Planets in the solar system (Earth and the four gas giants). Radio emission from these Planets results from solar-wind powered electron currents depositing energy in the magnetic polar regions. We find that most of the known Extrasolar Planets should emit in the frequency range 10--1000 MHz and, under favorable circumstances, have typical flux densities as large as 1 mJy. We also describe an initial, systematic effort to search for radio emission in low radio frequency images acquired with the Very Large Array. The limits set by the VLA images (~ 300 mJy) are consistent with, but do not provide strong constraints on, the predictions of the model. Future radio telescopes, such as the Low Frequency Array (LOFAR) and the Square Kilometer Array (SKA), should be able to detect the known Extrasolar Planets or place austere limits on their radio emission. Planets with masses much lower than those in the current census will probably radiate below 10 MHz and will require a space-based array.
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The Radiometric Bode’s Law and Extrasolar Planets
The Astrophysical Journal, 2004Co-Authors: T. Joseph W. Lazio, William M. Farrell, Jill Dietrick, Elizabeth Greenlees, Emily Hogan, Christopher Jones, L. A. HennigAbstract:We predict the radio flux densities of the Extrasolar Planets in the current census, making use of an empirical relation—the radiometric Bode's law—determined from the five "magnetic" Planets in the solar system (the Earth and the four gas giants). Radio emission from these Planets results from solar wind-powered electron currents depositing energy in the magnetic polar regions. We find that most of the known Extrasolar Planets should emit in the frequency range 10-1000 MHz and, under favorable circumstances, have typical flux densities as large as 1 mJy. We also describe an initial, systematic effort to search for radio emission in low radio frequency images acquired with the Very Large Array (VLA). The limits set by the VLA images (≈300 mJy) are consistent with, but do not provide strong constraints on, the predictions of the model. Future radio telescopes, such as the Low Frequency Array and the Square Kilometer Array, should be able to detect the known Extrasolar Planets or place austere limits on their radio emission. Planets with masses much lower than those in the current census will probably radiate below 10 MHz and will require a space-based array.
