The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
D M Harrington - One of the best experts on this subject based on the ideXlab platform.
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alpha virginis line profile variations and Orbital Elements
Astronomy and Astrophysics, 2016Co-Authors: D M Harrington, Gloria Koenigsberger, Enrique Olguin, I Ilyin, S V Berdyugina, Bruno Lara, E MorenoAbstract:Context. Alpha Virginis (Spica) is a B-type binary system whose proximity and brightness allow detailed investigations of the internal structure and evolution of stars undergoing time-variable tidal interactions. Previous studies have led to the conclusion that the internal structure of Spica’s primary star may be more centrally condensed than predicted by theoretical models of single stars, raising the possibility that the interactions could lead to effects that are currently neglected in structure and evolution calculations. The key parameters in confirming this result are the values of the Orbital eccentricity e , the apsidal period U , and the primary star’s radius, R 1 . Aims. The aim of this paper is to analyze the impact that Spica’s line profile variability has on the derivation of its Orbital Elements and to explore the use of the variability for constraining R 1 . Methods. We use high signal-to-noise and high spectral resolution observations obtained in 2000, 2008, and 2013 to derive the Orbital Elements from fits to the radial velocity curves. We produce synthetic line profiles using an ab initio tidal interaction model. Results. The general variations in the line profiles can be understood in terms of the tidal flows, whose large-scale structure is relatively fixed in the rotating binary system reference frame. Fits to the radial velocity curves yield e = 0.108 ± 0.014. However, the analogous RV curves from theoretical line profiles indicate that the distortion in the lines causes the fitted value of e to depend on the argument of periastron; i.e., on the epoch of observation. As a result, the actual value of e may be as high as 0.125. We find that U = 117.9 ± 1.8, which is in agreement with previous determinations. Using the value R 1 = 6.8 R ⊙ derived by Palate et al. (2013) the value of the observational internal structure constant k 2,obs is consistent with theory. We confirm the presence of variability in the line profiles of the secondary star.
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alpha virginis line profile variations and Orbital Elements
arXiv: Solar and Stellar Astrophysics, 2016Co-Authors: D M Harrington, Gloria Koenigsberger, Enrique Olguin, I Ilyin, S V Berdyugina, Bruno Lara, E MorenoAbstract:Abridged: Alpha Virginis is a binary system whose proximity and brightness allow detailed investigations of the internal structure and evolution of stars undergoing time-variable tidal interactions. Previous studies have led to the conclusion that the internal structure of Spica's primary star may be more centrally condensed than predicted by theoretical models of single stars, raising the possibility that the interactions could lead to effects that are currently neglected in structure and evolution calculations. The key parameters in confirming this result are the values of the Orbital eccentricity $e$, the apsidal period $U$, and the primary star's radius, R_1. We analyze the impact that line profile variability has on the derivation of its Orbital Elements and R_1. We use high SNR observations obtained in 2000, 2008, and 2013 to derive the Orbital Elements from fits to the radial velocity curves. We produce synthetic line profiles using an ab initio tidal interaction model. Results: The variations in the line profiles can be understood in terms of the tidal flows, whose large-scale structure is relatively fixed in the rotating binary system reference frame. Fits to the radial velocity curves yield $e$=0.108$\pm$0.014. However, the analogous RV curves from theoretical line profiles indicate that the distortion in the lines causes the fitted value of $e$ to depend on the argument of periastron; i.e., on the epoch of observation. As a result, the actual value of $e$ may be as high as 0.125. We find that $U$=117.9$\pm$1.8, which is in agreement with previous determinations. Using the value $R_1=6.8 R_\odot$ derived by Palate et al. (2013) the value of the observational internal structure constant $k_{2,obs}$ is consistent with theory. We confirm the presence of variability in the line profiles of the secondary star.
John E. Chambers - One of the best experts on this subject based on the ideXlab platform.
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short term dynamical interactions among extrasolar planets
2013Co-Authors: Gregory Laughlin, John E. ChambersAbstract:We show that short-term perturbations among massive planets in multiple planet systems can result in radial velocity variations of the central star that differ substantially from velocity variations derived assuming the planets are executing independent Keplerian motions. We discuss two fitting methods that can lead to an improved dynamical description of multiple planet systems. In the first method, the osculating Orbital Elements are determined via a Levenberg-Marquardt minimization scheme driving an N-body integrator. The second method is an improved analytic model in which Orbital Elements are allowed to vary according to a simple model for resonant interactions between the planets. Both of these methods can determine the true masses for the planets by eliminating the sin i degeneracy inherent in fits that assume independent Keplerian motions. We apply our fitting methods to the GJ 876 radial velocity data and argue that the mass factors for the two planets are likely in the 1.25-2.0 range.
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terrestrial planet formation around individual stars within binary star systems
arXiv: Astrophysics, 2007Co-Authors: Elisa V. Quintana, Fred C. Adams, Jack J. Lissauer, John E. ChambersAbstract:We calculate herein the late stages of terrestrial planet accumulation around a solar type star that has a binary companion with semimajor axis larger than the terrestrial planet region. We perform more than one hundred simulations to survey binary parameter space and to account for sensitive dependence on initial conditions in these dynamical systems. As expected, sufficiently wide binaries leave the planet formation process largely unaffected. As a rough approximation, binary stars with periastron $q_B > 10$ AU have minimal effect on terrestrial planet formation within $\sim 2$ AU of the primary, whereas binary stars with $q_B \la$ 5 AU restrict terrestrial planet formation to within $\sim$ 1 AU of the primary star. Given the observed distribution of binary Orbital Elements for solar type primaries, we estimate that about 40 -- 50 percent of the binary population is wide enough to allow terrestrial planet formation to take place unimpeded. The large number of simulations allows for us to determine the distribution of results -- the distribution of plausible terrestrial planet systems -- for effectively equivalent starting conditions. We present (rough) distributions for the number of planets, their masses, and their Orbital Elements.
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short term dynamical interactions among extrasolar planets
arXiv: Astrophysics, 2001Co-Authors: Gregory Laughlin, John E. ChambersAbstract:We show that short-term perturbations among massive planets in multiple planet systems can result in radial velocity variations of the central star which differ substantially from velocity variations derived assuming the planets are executing independent Keplerian motions. We discuss two alternate fitting methods which can lead to an improved dynamical description of multiple planet systems. In the first method, the osculating Orbital Elements are determined via a Levenberg-Marquardt minimization scheme driving an N-body integrator. The second method is an improved analytic model in which Orbital Elements are allowed to vary according to a simple model for resonant interactions between the planets. Both of these methods can determine the true masses for the planets by eliminating the sin(i) degeneracy inherent in fits that assume independent Keplerian motions. We apply our fitting methods to the GJ876 radial velocity data (Marcy et al. 2001), and argue that the mass factors for the two planets are likely in the 1.25-2.0 range
E Moreno - One of the best experts on this subject based on the ideXlab platform.
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alpha virginis line profile variations and Orbital Elements
Astronomy and Astrophysics, 2016Co-Authors: D M Harrington, Gloria Koenigsberger, Enrique Olguin, I Ilyin, S V Berdyugina, Bruno Lara, E MorenoAbstract:Context. Alpha Virginis (Spica) is a B-type binary system whose proximity and brightness allow detailed investigations of the internal structure and evolution of stars undergoing time-variable tidal interactions. Previous studies have led to the conclusion that the internal structure of Spica’s primary star may be more centrally condensed than predicted by theoretical models of single stars, raising the possibility that the interactions could lead to effects that are currently neglected in structure and evolution calculations. The key parameters in confirming this result are the values of the Orbital eccentricity e , the apsidal period U , and the primary star’s radius, R 1 . Aims. The aim of this paper is to analyze the impact that Spica’s line profile variability has on the derivation of its Orbital Elements and to explore the use of the variability for constraining R 1 . Methods. We use high signal-to-noise and high spectral resolution observations obtained in 2000, 2008, and 2013 to derive the Orbital Elements from fits to the radial velocity curves. We produce synthetic line profiles using an ab initio tidal interaction model. Results. The general variations in the line profiles can be understood in terms of the tidal flows, whose large-scale structure is relatively fixed in the rotating binary system reference frame. Fits to the radial velocity curves yield e = 0.108 ± 0.014. However, the analogous RV curves from theoretical line profiles indicate that the distortion in the lines causes the fitted value of e to depend on the argument of periastron; i.e., on the epoch of observation. As a result, the actual value of e may be as high as 0.125. We find that U = 117.9 ± 1.8, which is in agreement with previous determinations. Using the value R 1 = 6.8 R ⊙ derived by Palate et al. (2013) the value of the observational internal structure constant k 2,obs is consistent with theory. We confirm the presence of variability in the line profiles of the secondary star.
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alpha virginis line profile variations and Orbital Elements
arXiv: Solar and Stellar Astrophysics, 2016Co-Authors: D M Harrington, Gloria Koenigsberger, Enrique Olguin, I Ilyin, S V Berdyugina, Bruno Lara, E MorenoAbstract:Abridged: Alpha Virginis is a binary system whose proximity and brightness allow detailed investigations of the internal structure and evolution of stars undergoing time-variable tidal interactions. Previous studies have led to the conclusion that the internal structure of Spica's primary star may be more centrally condensed than predicted by theoretical models of single stars, raising the possibility that the interactions could lead to effects that are currently neglected in structure and evolution calculations. The key parameters in confirming this result are the values of the Orbital eccentricity $e$, the apsidal period $U$, and the primary star's radius, R_1. We analyze the impact that line profile variability has on the derivation of its Orbital Elements and R_1. We use high SNR observations obtained in 2000, 2008, and 2013 to derive the Orbital Elements from fits to the radial velocity curves. We produce synthetic line profiles using an ab initio tidal interaction model. Results: The variations in the line profiles can be understood in terms of the tidal flows, whose large-scale structure is relatively fixed in the rotating binary system reference frame. Fits to the radial velocity curves yield $e$=0.108$\pm$0.014. However, the analogous RV curves from theoretical line profiles indicate that the distortion in the lines causes the fitted value of $e$ to depend on the argument of periastron; i.e., on the epoch of observation. As a result, the actual value of $e$ may be as high as 0.125. We find that $U$=117.9$\pm$1.8, which is in agreement with previous determinations. Using the value $R_1=6.8 R_\odot$ derived by Palate et al. (2013) the value of the observational internal structure constant $k_{2,obs}$ is consistent with theory. We confirm the presence of variability in the line profiles of the secondary star.
S V Berdyugina - One of the best experts on this subject based on the ideXlab platform.
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alpha virginis line profile variations and Orbital Elements
Astronomy and Astrophysics, 2016Co-Authors: D M Harrington, Gloria Koenigsberger, Enrique Olguin, I Ilyin, S V Berdyugina, Bruno Lara, E MorenoAbstract:Context. Alpha Virginis (Spica) is a B-type binary system whose proximity and brightness allow detailed investigations of the internal structure and evolution of stars undergoing time-variable tidal interactions. Previous studies have led to the conclusion that the internal structure of Spica’s primary star may be more centrally condensed than predicted by theoretical models of single stars, raising the possibility that the interactions could lead to effects that are currently neglected in structure and evolution calculations. The key parameters in confirming this result are the values of the Orbital eccentricity e , the apsidal period U , and the primary star’s radius, R 1 . Aims. The aim of this paper is to analyze the impact that Spica’s line profile variability has on the derivation of its Orbital Elements and to explore the use of the variability for constraining R 1 . Methods. We use high signal-to-noise and high spectral resolution observations obtained in 2000, 2008, and 2013 to derive the Orbital Elements from fits to the radial velocity curves. We produce synthetic line profiles using an ab initio tidal interaction model. Results. The general variations in the line profiles can be understood in terms of the tidal flows, whose large-scale structure is relatively fixed in the rotating binary system reference frame. Fits to the radial velocity curves yield e = 0.108 ± 0.014. However, the analogous RV curves from theoretical line profiles indicate that the distortion in the lines causes the fitted value of e to depend on the argument of periastron; i.e., on the epoch of observation. As a result, the actual value of e may be as high as 0.125. We find that U = 117.9 ± 1.8, which is in agreement with previous determinations. Using the value R 1 = 6.8 R ⊙ derived by Palate et al. (2013) the value of the observational internal structure constant k 2,obs is consistent with theory. We confirm the presence of variability in the line profiles of the secondary star.
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alpha virginis line profile variations and Orbital Elements
arXiv: Solar and Stellar Astrophysics, 2016Co-Authors: D M Harrington, Gloria Koenigsberger, Enrique Olguin, I Ilyin, S V Berdyugina, Bruno Lara, E MorenoAbstract:Abridged: Alpha Virginis is a binary system whose proximity and brightness allow detailed investigations of the internal structure and evolution of stars undergoing time-variable tidal interactions. Previous studies have led to the conclusion that the internal structure of Spica's primary star may be more centrally condensed than predicted by theoretical models of single stars, raising the possibility that the interactions could lead to effects that are currently neglected in structure and evolution calculations. The key parameters in confirming this result are the values of the Orbital eccentricity $e$, the apsidal period $U$, and the primary star's radius, R_1. We analyze the impact that line profile variability has on the derivation of its Orbital Elements and R_1. We use high SNR observations obtained in 2000, 2008, and 2013 to derive the Orbital Elements from fits to the radial velocity curves. We produce synthetic line profiles using an ab initio tidal interaction model. Results: The variations in the line profiles can be understood in terms of the tidal flows, whose large-scale structure is relatively fixed in the rotating binary system reference frame. Fits to the radial velocity curves yield $e$=0.108$\pm$0.014. However, the analogous RV curves from theoretical line profiles indicate that the distortion in the lines causes the fitted value of $e$ to depend on the argument of periastron; i.e., on the epoch of observation. As a result, the actual value of $e$ may be as high as 0.125. We find that $U$=117.9$\pm$1.8, which is in agreement with previous determinations. Using the value $R_1=6.8 R_\odot$ derived by Palate et al. (2013) the value of the observational internal structure constant $k_{2,obs}$ is consistent with theory. We confirm the presence of variability in the line profiles of the secondary star.
M Mayor - One of the best experts on this subject based on the ideXlab platform.
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multiplicity among solar type stars iv the coravel radial velocities and the spectroscopic orbits of nearby k dwarfs
Astronomy and Astrophysics, 2018Co-Authors: J L Halbwachs, M Mayor, S UdryAbstract:Context. The statistical properties of binary stars are clues for understanding their formation process. A radial velocity survey was carried on amongst nearby G-type stars and the results were published in 1991. Aims. The survey of radial velocity measurements was extended towards K-type stars. Methods. A sample of 261 K-type stars was observed with the spectrovelocimeter CORAVEL (COrrelation RAdial VELocities). Those stars with a variable radial velocity were detected on the basis of the P(chi^2) test. The Orbital Elements of the spectroscopic binaries were then derived. Results. The statistical properties of binary stars were derived from these observations and published in 2003. We present the catalogue of the radial velocity measurements obtained with CORAVEL for all the K stars of the survey and the Orbital Elements derived for 34 spectroscopic systems. In addition, the catalogue contains eight G-type spectroscopic binaries that have received additional measurements since 1991 and for which the Orbital Elements are revised or derived for the first time.
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red giants in open clusters xiii Orbital Elements of 156 spectroscopic binaries
Astronomy and Astrophysics, 2007Co-Authors: J C Mermilliod, J Andersen, D W Latham, M MayorAbstract:Context. The identification and characterisation of spectroscopic binaries with red-giant primaries in open clusters is important for a proper understanding of the colour-magnitude diagrams of the clusters. Moreover, the Orbital eccentricities and axial rotations of these binaries are valuable probes into the inner structure and tidal interaction of the stars. Aims. We report on a comprehensive, long-term monitoring programme aiming to improve our knowledge of such binary systems. Methods. The radial velocities of 1309 red giants in 187 open clusters in the whole sky have been monitored with the Coravel and CfA spectrometers for 20 years, with a typical accuracy of 0.4 km s −1 per observation. Results. In total, 289 spectroscopic binaries were detected in the sample. We present first orbits for 67 systems and improved Elements for another 64 previously published orbits, based on additional observations. For completeness, 25 published orbits are listed as well. The orbits are based on a total of 4039 observations, an average of 26 per system. Orbital periods range from 41.5 to 14 722 days (40 yrs), eccentricities from 0.00 to 0.81. The remaining 133 systems have too long periods, too few observations, and/or inadequate phase coverage for an orbit determination at this time. Conclusions. This paper provides a dramatic increase in the body of homogeneous Orbital data available for red-giant spectroscopic binaries in open clusters. It will form the basis for a comprehensive discussion of membership, kinematics, and stellar and tidal evolution in the parent clusters.
