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Martin Houde - One of the best experts on this subject based on the ideXlab platform.
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the carter constant for inclined Orbits about a massive kerr black hole near circular near polar Orbits
arXiv: General Relativity and Quantum Cosmology, 2011Co-Authors: P G Komorowski, S R Valluri, Martin HoudeAbstract:In an extreme mass-ratio binary black hole system, a non-equatorial orbit will list (i.e. increase its angle of inclination, {\iota}) as it evolves in Kerr spacetime. The abutment, a set of evolving, near-polar, Retrograde Orbits, for which the instantaneous Carter constant (Q) is at its maximum value (Q_{X}) for given values of latus rectum (l) and eccentricity (e), has been introduced as a laboratory in which the consistency of dQ/dt with corresponding evolution equations for dl/dt and de/dt might be tested independently of a specific radiation back-reaction model. To demonstrate the use of the abutment as such a laboratory, a derivation of dQ/dt, based only on published formulae for dl/dt and de/dt, was performed for elliptical Orbits on the abutment. The resulting expression for dQ/dt matched the published result to the second order in e. We believe the abutment is a potentially useful tool for improving the accuracy of evolution equations to higher orders of e and l^{1}.
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carter constant for near circular near polar elliptical Orbits about a massive kerr black hole
2011Co-Authors: P G Komorowski, S R Valluri, Martin HoudeAbstract:In an extreme mass-ratio binary black hole system, a non-equatorial orbit will list (i.e. increase its angle of inclination, {\iota}) as it evolves in Kerr spacetime. The abutment, a set of evolving, near-polar, Retrograde Orbits, for which the instantaneous Carter constant (Q) is at its maximum value (Q_{X}) for given values of latus rectum (l) and eccentricity (e), has been introduced as a laboratory in which the consistency of dQ/dt with corresponding evolution equations for dl/dt and de/dt might be tested independently of a specific radiation back-reaction model. To demonstrate the use of the abutment as such a laboratory, a derivation of dQ/dt, based only on published formulae for dl/dt and de/dt, was performed for elliptical Orbits on the abutment. The resulting expression for dQ/dt matched the published result to the second order in e. We believe the abutment is a potentially useful tool for improving the accuracy of evolution equations to higher orders of e and l^{1}.
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the carter constant for inclined Orbits about a massive kerr black hole i circular Orbits
Classical and Quantum Gravity, 2010Co-Authors: P G Komorowski, S R Valluri, Martin HoudeAbstract:In an extreme binary black hole system, an orbit will increase its angle of inclination ( ) as it evolves in Kerr spacetime. We focus our attention on the behaviour of the Carter constant (Q) for near-polar Orbits; and develop an analysis that is independent of and complements radiation reaction models. For a Schwarzschild black hole, the polar Orbits represent the abutment between the prograde and Retrograde Orbits at which Q is at its maximum value for given values of latus rectum ( ~) and eccentricity (e). The introduction of spin ( ~ S = jJj=M 2 ) to the massive black hole causes this boundary, or abutment, to be moved towards greater orbital inclination; thus it no longer cleanly separates prograde and Retrograde Orbits. To characterise the abutment of a Kerr black hole (KBH), we first investigated the last stable orbit (LSO) of a test-particle about a KBH, and then extended this work to general Orbits. To develop a better understanding of the evolution of Q we developed analytical formulae for Q in terms of ~, e, and ~ S to describe elliptical Orbits at the abutment, polar Orbits, and last stable Orbits (LSO). By knowing the analytical form of @Q=@~ at the abutment, we were able to test a 2PN flux equation for Q. We also used these formulae to numerically calculate the @=@ ~ of hypothetical circular Orbits that evolve along the abutment. From these values we have determined that@=@ ~ = 122:7 ~
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The Carter Constant for Inclined Orbits About a Massive Kerr Black Hole: I. circular Orbits
Classical and Quantum Gravity, 2010Co-Authors: P G Komorowski, S R Valluri, Martin HoudeAbstract:In an extreme binary black hole system, an orbit will increase its angle of inclination (i) as it evolves in Kerr spacetime. We focus our attention on the behaviour of the Carter constant (Q) for near-polar Orbits; and develop an analysis that is independent of and complements radiation reaction models. For a Schwarzschild black hole, the polar Orbits represent the abutment between the prograde and Retrograde Orbits at which Q is at its maximum value for given values of latus rectum (l) and eccentricity (e). The introduction of spin (S = |J|/M2) to the massive black hole causes this boundary, or abutment, to be moved towards greater orbital inclination; thus it no longer cleanly separates prograde and Retrograde Orbits. To characterise the abutment of a Kerr black hole (KBH), we first investigated the last stable orbit (LSO) of a test-particle about a KBH, and then extended this work to general Orbits. To develop a better understanding of the evolution of Q we developed analytical formulae for Q in terms of l, e, and S to describe elliptical Orbits at the abutment, polar Orbits, and last stable Orbits (LSO). By knowing the analytical form of dQ/dl at the abutment, we were able to test a 2PN flux equation for Q. We also used these formulae to numerically calculate the di/dl of hypothetical circular Orbits that evolve along the abutment. From these values we have determined that di/dl = -(122.7S - 36S^3)l^-11/2 -(63/2 S + 35/4 S^3) l^-9/2 -15/2 S l^-7/2 -9/2 S l^-5/2. Thus the abutment becomes an important analytical and numerical laboratory for studying the evolution of Q and i in Kerr spacetime and for testing current and future radiation back-reaction models for near-polar Retrograde Orbits.
Giovanni Carraro - One of the best experts on this subject based on the ideXlab platform.
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surface composition and dynamical evolution of two Retrograde objects in the outer solar system 2008 yb3 and 2005 vd
Astronomy and Astrophysics, 2013Co-Authors: N Pinillaalonso, A Alvarezcandal, M D Melita, V Lorenzi, J Licandro, J M Carvano, D Lazzaro, Giovanni CarraroAbstract:Most of the objects in the trans-Neptunian belt (TNb) and related populations move in prograde Orbits with low eccentricity and inclination. However, the list of icy minor bodies moving in Orbits with an inclination above 40 has increased in recent years. The origin of these bodies, and in particular of those objects in Retrograde Orbits, is not well determined, and di erent scenarios are considered, depending on their inclination and perihelion. In this paper, we present new observational and dynamical data of two objects in Retrograde Orbits, 2008 YB3 and 2005 VD. We find that the surface of these extreme objects is depleted of ices and does not contain the ‘ultra-red’ matter typical of some Centaurs. Despite small di erences, these objects share common colors and spectral characteristics with the Trojans, comet nuclei, and the group of grey Centaurs. All of these populations are supposed to be covered by a mantle of dust responsible for their reddish- to neutral-color. To investigate if the surface properties and dynamical evolution of these bodies are related, we integrate their Orbits for 10 8 years to the past. We find a remarkable di erence in their dynamical evolutions: 2005 VD’s evolution is dominated by a Kozai resonance with planet Jupiter while that of 2008 YB3 is dominated by close encounters with planets Jupiter and Saturn. Our models suggest that the immediate site of provenance of 2005 VD is the in the Oort cloud, whereas for 2008 YB3 it is in the trans-Neptunian region. Additionally, the study of their residence time shows that 2005 VD has spent a larger lapse of time moving in Orbits in the region of the giant planets than 2008 YB3. Together with the small di erences in color between these two objects, with 2005 VD being more neutral than 2008 YB3, this fact suggests that the surface of 2005 VD has su ered a higher degree of processing, probably related to cometary activity episodes.
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surface composition and dynamical evolution of two Retrograde objects in the outer solar system 2008 yb3 and 2005 vd
arXiv: Earth and Planetary Astrophysics, 2013Co-Authors: N Pinillaalonso, A Alvarezcandal, M D Melita, V Lorenzi, J Licandro, J M Carvano, D Lazzaro, Giovanni CarraroAbstract:Most of the objects in the trans-Neptunian belt (TNb) and related populations move in prograde Orbits with low eccentricity and inclination. However, the list of icy minor bodies moving in Orbits with an inclination above 40 deg. has increased in recent years. The origin of these bodies, and in particular of those objects in Retrograde Orbits, is not well determined, and different scenarios are considered. In this paper, we present new observational and dynamical data of two objects in Retrograde Orbits, 2008 YB3 and 2005 VD. We find that the surface of these extreme objects is depleted of ices and does not contain the 'ultra-red' matter typical of some Centaurs. Despite small differences, these objects share common colors and spectral characteristics with the Trojans, comet nuclei, and the group of grey Centaurs. All of these populations are supposed to be covered by a mantle of dust responsible for their reddish- to neutral-color. To investigate if the surface properties and dynamical evolution of these bodies are related, we integrate their Orbits for 10^(8) years to the past. We find a remarkable difference in their dynamical evolutions: 2005 VD' s evolution is dominated by a Kozai resonance with planet Jupiter while that of 2008 YB3 is dominated by close encounters with planets Jupiter and Saturn. Our models suggest that the immediate site of provenance of 2005 VD is the in the Oort cloud, whereas for 2008 YB3 it is in the trans-Neptunian region. Additionally, the study of their residence time shows that 2005 VD has spent a larger lapse of time moving in Orbits in the region of the giant planets than 2008 YB3. Together with the small differences in color between these two objects, with 2005 VD being more neutral than 2008 YB3, this fact suggests that the surface of 2005 VD has suffered a higher degree of processing, probably related to cometary activity episodes.
A Alvarezcandal - One of the best experts on this subject based on the ideXlab platform.
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surface composition and dynamical evolution of two Retrograde objects in the outer solar system 2008 yb3 and 2005 vd
Astronomy and Astrophysics, 2013Co-Authors: N Pinillaalonso, A Alvarezcandal, M D Melita, V Lorenzi, J Licandro, J M Carvano, D Lazzaro, Giovanni CarraroAbstract:Most of the objects in the trans-Neptunian belt (TNb) and related populations move in prograde Orbits with low eccentricity and inclination. However, the list of icy minor bodies moving in Orbits with an inclination above 40 has increased in recent years. The origin of these bodies, and in particular of those objects in Retrograde Orbits, is not well determined, and di erent scenarios are considered, depending on their inclination and perihelion. In this paper, we present new observational and dynamical data of two objects in Retrograde Orbits, 2008 YB3 and 2005 VD. We find that the surface of these extreme objects is depleted of ices and does not contain the ‘ultra-red’ matter typical of some Centaurs. Despite small di erences, these objects share common colors and spectral characteristics with the Trojans, comet nuclei, and the group of grey Centaurs. All of these populations are supposed to be covered by a mantle of dust responsible for their reddish- to neutral-color. To investigate if the surface properties and dynamical evolution of these bodies are related, we integrate their Orbits for 10 8 years to the past. We find a remarkable di erence in their dynamical evolutions: 2005 VD’s evolution is dominated by a Kozai resonance with planet Jupiter while that of 2008 YB3 is dominated by close encounters with planets Jupiter and Saturn. Our models suggest that the immediate site of provenance of 2005 VD is the in the Oort cloud, whereas for 2008 YB3 it is in the trans-Neptunian region. Additionally, the study of their residence time shows that 2005 VD has spent a larger lapse of time moving in Orbits in the region of the giant planets than 2008 YB3. Together with the small di erences in color between these two objects, with 2005 VD being more neutral than 2008 YB3, this fact suggests that the surface of 2005 VD has su ered a higher degree of processing, probably related to cometary activity episodes.
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surface composition and dynamical evolution of two Retrograde objects in the outer solar system 2008 yb3 and 2005 vd
arXiv: Earth and Planetary Astrophysics, 2013Co-Authors: N Pinillaalonso, A Alvarezcandal, M D Melita, V Lorenzi, J Licandro, J M Carvano, D Lazzaro, Giovanni CarraroAbstract:Most of the objects in the trans-Neptunian belt (TNb) and related populations move in prograde Orbits with low eccentricity and inclination. However, the list of icy minor bodies moving in Orbits with an inclination above 40 deg. has increased in recent years. The origin of these bodies, and in particular of those objects in Retrograde Orbits, is not well determined, and different scenarios are considered. In this paper, we present new observational and dynamical data of two objects in Retrograde Orbits, 2008 YB3 and 2005 VD. We find that the surface of these extreme objects is depleted of ices and does not contain the 'ultra-red' matter typical of some Centaurs. Despite small differences, these objects share common colors and spectral characteristics with the Trojans, comet nuclei, and the group of grey Centaurs. All of these populations are supposed to be covered by a mantle of dust responsible for their reddish- to neutral-color. To investigate if the surface properties and dynamical evolution of these bodies are related, we integrate their Orbits for 10^(8) years to the past. We find a remarkable difference in their dynamical evolutions: 2005 VD' s evolution is dominated by a Kozai resonance with planet Jupiter while that of 2008 YB3 is dominated by close encounters with planets Jupiter and Saturn. Our models suggest that the immediate site of provenance of 2005 VD is the in the Oort cloud, whereas for 2008 YB3 it is in the trans-Neptunian region. Additionally, the study of their residence time shows that 2005 VD has spent a larger lapse of time moving in Orbits in the region of the giant planets than 2008 YB3. Together with the small differences in color between these two objects, with 2005 VD being more neutral than 2008 YB3, this fact suggests that the surface of 2005 VD has suffered a higher degree of processing, probably related to cometary activity episodes.
J Licandro - One of the best experts on this subject based on the ideXlab platform.
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surface composition and dynamical evolution of two Retrograde objects in the outer solar system 2008 yb3 and 2005 vd
Astronomy and Astrophysics, 2013Co-Authors: N Pinillaalonso, A Alvarezcandal, M D Melita, V Lorenzi, J Licandro, J M Carvano, D Lazzaro, Giovanni CarraroAbstract:Most of the objects in the trans-Neptunian belt (TNb) and related populations move in prograde Orbits with low eccentricity and inclination. However, the list of icy minor bodies moving in Orbits with an inclination above 40 has increased in recent years. The origin of these bodies, and in particular of those objects in Retrograde Orbits, is not well determined, and di erent scenarios are considered, depending on their inclination and perihelion. In this paper, we present new observational and dynamical data of two objects in Retrograde Orbits, 2008 YB3 and 2005 VD. We find that the surface of these extreme objects is depleted of ices and does not contain the ‘ultra-red’ matter typical of some Centaurs. Despite small di erences, these objects share common colors and spectral characteristics with the Trojans, comet nuclei, and the group of grey Centaurs. All of these populations are supposed to be covered by a mantle of dust responsible for their reddish- to neutral-color. To investigate if the surface properties and dynamical evolution of these bodies are related, we integrate their Orbits for 10 8 years to the past. We find a remarkable di erence in their dynamical evolutions: 2005 VD’s evolution is dominated by a Kozai resonance with planet Jupiter while that of 2008 YB3 is dominated by close encounters with planets Jupiter and Saturn. Our models suggest that the immediate site of provenance of 2005 VD is the in the Oort cloud, whereas for 2008 YB3 it is in the trans-Neptunian region. Additionally, the study of their residence time shows that 2005 VD has spent a larger lapse of time moving in Orbits in the region of the giant planets than 2008 YB3. Together with the small di erences in color between these two objects, with 2005 VD being more neutral than 2008 YB3, this fact suggests that the surface of 2005 VD has su ered a higher degree of processing, probably related to cometary activity episodes.
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surface composition and dynamical evolution of two Retrograde objects in the outer solar system 2008 yb3 and 2005 vd
arXiv: Earth and Planetary Astrophysics, 2013Co-Authors: N Pinillaalonso, A Alvarezcandal, M D Melita, V Lorenzi, J Licandro, J M Carvano, D Lazzaro, Giovanni CarraroAbstract:Most of the objects in the trans-Neptunian belt (TNb) and related populations move in prograde Orbits with low eccentricity and inclination. However, the list of icy minor bodies moving in Orbits with an inclination above 40 deg. has increased in recent years. The origin of these bodies, and in particular of those objects in Retrograde Orbits, is not well determined, and different scenarios are considered. In this paper, we present new observational and dynamical data of two objects in Retrograde Orbits, 2008 YB3 and 2005 VD. We find that the surface of these extreme objects is depleted of ices and does not contain the 'ultra-red' matter typical of some Centaurs. Despite small differences, these objects share common colors and spectral characteristics with the Trojans, comet nuclei, and the group of grey Centaurs. All of these populations are supposed to be covered by a mantle of dust responsible for their reddish- to neutral-color. To investigate if the surface properties and dynamical evolution of these bodies are related, we integrate their Orbits for 10^(8) years to the past. We find a remarkable difference in their dynamical evolutions: 2005 VD' s evolution is dominated by a Kozai resonance with planet Jupiter while that of 2008 YB3 is dominated by close encounters with planets Jupiter and Saturn. Our models suggest that the immediate site of provenance of 2005 VD is the in the Oort cloud, whereas for 2008 YB3 it is in the trans-Neptunian region. Additionally, the study of their residence time shows that 2005 VD has spent a larger lapse of time moving in Orbits in the region of the giant planets than 2008 YB3. Together with the small differences in color between these two objects, with 2005 VD being more neutral than 2008 YB3, this fact suggests that the surface of 2005 VD has suffered a higher degree of processing, probably related to cometary activity episodes.
A Spagna - One of the best experts on this subject based on the ideXlab platform.
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the kinematic properties of bhb and rr lyrae stars towards the anticentre and the north galactic pole the transition between the inner and the outer halo
Monthly Notices of the Royal Astronomical Society, 2012Co-Authors: T D Kinman, C Cacciari, A Bragaglia, R L Smart, A SpagnaAbstract:We identify 51 blue horizontal branch (BHB) stars, 12 possible BHB stars and 58 RR Lyrae stars in Anticentre fields. Their selection does not depend on their kinematics. Light curves and ephemerides are given for seven previously unknown RR Lyrae stars. All but four of the RR Lyrae stars are of Oosterhoff type I. Our selection criteria for BHB stars give results that agree with those used by Smith et al. and Ruhland et al. We use five methods to determine distances for the BHB stars and three methods for the RR Lyrae stars to get distances on a uniform scale. Absolute proper motions [largely derived from the Second Guide Star Catalogue (GSCII) and Sloan Digital Sky Survey (Seventh Data Release) data bases] are given for these stars; radial velocities are given for 31 of the BHB stars and 37 of the RR Lyrae stars. Combining these data for BHB and RR Lyrae stars with those previously found in fields at the North Galactic Pole, we find that Retrograde Orbits dominate for galactocentric distances greater than 12.5 kpc. The majority of metal-poor stars in the solar neighbourhood are known to be concentrated in a L⊥ versus Lz angular momentum plot. We show that the ratio of the number of outliers to the number in the main concentration increases with galactocentric distance. The location of these outliers with L⊥ and Lz shows that the halo BHB and RR Lyrae stars have more Retrograde Orbits and a more spherical distribution with increasing galactocentric distance. Six RR Lyrae stars are identified in the H99 group of outliers; the small spread in their [Fe/H] suggests that they could have come from a single globular cluster. Another group of outliers contains two pairs of RR Lyrae stars; the stars in each pair have similar properties.
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the kinematic properties of bhb and rr lyrae stars towards the anticentre and the north galactic pole the transition between the inner and the outer halo
arXiv: Astrophysics of Galaxies, 2012Co-Authors: T D Kinman, C Cacciari, A Bragaglia, R L Smart, A SpagnaAbstract:We identify 51 blue horizontal branch (BHB) stars, 12 possible BHB stars and 58 RR Lyrae stars in Anticentre fields. Their selection does not depend on their kinematics. Light curves and ephemerides are given for 7 previously unknown RR Lyrae stars. All but 4 of the RR Lyrae stars are of Oosterhoff type I. Our selection criteria for BHB stars give results that agree with those used by Smith et al. (2010) and Ruhland et al. (2011). We use 5 methods to determine distances for the BHB stars and 3 methods for the RR Lyrae stars to get distances on a uniform scale. Absolute proper motions (largely derived from the GSCII and SDSS (DR7) databases) are given for these stars; radial velocities are given for 31 of the BHB stars and 37 of the RR Lyrae stars. Combining these data for BHB and RR Lyrae stars with those previously found in fields at the North Galactic Pole, we find that Retrograde Orbits dominate for galactocentric distances greater than 12.5 kpc. The majority of metal-poor stars in the solar neighbourhood are known to be concentrated in a Lperp vs. Lz angular momentum plot. We show that the ratio of the number of outliers to the number in the main concentration increases with galactocentric distance. The location of these outliers with Lperp and Lz shows that the halo BHB and RR Lyrae stars have more Retrograde Orbits and a more spherical distribution with increasing galactocentric distance. Six RR Lyrae stars are identified in the H99 group of outliers; the small spread in their [Fe/H] suggests that they could have come from a single globular cluster. Another group of outliers contains two pairs of RR Lyrae stars; the stars in each pair have similar properties.
