The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
D. Goldberg - One of the best experts on this subject based on the ideXlab platform.
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On the Mass-Ratio Distribution of Spectroscopic Binaries
The Astrophysical Journal, 2003Co-Authors: D. Goldberg, Tsevi Mazeh, David W. LathamAbstract:In this paper we derive the Mass-Ratio and secondary-Mass distributions of a large, well-defined, complete sample of 129 spectroscopic binaries with periods between 1 and 2500 days. The binaries, whose orbits were published recently, were detected by a systematic radial-velocity survey of a sample of more than 1400 large proper motion stars. Three features stand out in the Mass-Ratio distribution: a rise as the Mass Ratio goes down to q ~ 0.2, a sharp drop below q ~ 0.2, and a smaller peak at q ~ 0.8. Another way to characterize the results is to state that the distribution includes two populations, one with a high asymmetric peak at q ~ 0.2 and another with a smaller peak at q ~ 0.8, while the minimum between the two populations is centered at q ~ 0.55. The size of the binary sample allows us to divide it into two subsamples and look for differences in the Mass-Ratio distributions of the two subsamples. We performed two different divisions: one into Galactic halo versus disk populations, and the other into high- and low-Mass primary stars (above and below 0.67 M☉). The former division yields differences with moderate statistical significance of 88%, while the latter is more significant at a level of 97%. Our analysis suggests that the rise toward low Mass Ratios does not appear in the Mass-Ratio distribution of the halo binaries. The other sepaRation shows a broad peak at Mass Ratio of q ~ 0.8-1 for the subsample of binaries with low-Mass primaries but no corresponding peak in the subsample with high-Mass primaries. We discuss our findings and their application to theories of binary formation.
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The Mass-Ratio distribution of the spectroscopic binaries in the Pleiades.
Astronomy and Astrophysics, 1994Co-Authors: D. Goldberg, Tsevi MazehAbstract:This is a short study of the Mass-Ratio distribution of the short-period binaries in the Pleiades. The study is based on a complete, though extremely small, sample of binaries, out of the thorough radial-velocity survey of Mermilliod et al. (1992). The sample of nine spectroscopic binaries is analysed with a recently published algorithm, which is free of the disadvantages of some of the previous approaches to the problem. The emerging trend of the Mass-Ratio distribution is flat, or perhaps slightly rising toward unity, similar to that of the nearby binaries with G-dwarf primaries recently found
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The Mass-Ratio Distribution of Short-Period Binaries
International Astronomical Union Colloquium, 1992Co-Authors: T. Mareh, D. GoldbergAbstract:Abstract We present a new algorithm to derive the Mass-Ratio distribution of an observed sample of spectroscopic binaries. The algorithm replaces each binary of unknown inclination by an ensemble of virtual systems with a distribution of inclinations. We show that contrary to a widely held assumption the orientations of each virtual ensemble should not be distributed randomly in space. A few iteRations are needed to find the true Mass-Ratio distribution. Numerical simulations clearly demonstrate the advantage of the new algorithm over the classical method. We have applied the new algorithm to the recent large sample of G-dwarf spectroscopic binaries, and got a uniform or perhaps a slightly rising linear Mass-Ratio distribution. This result suggests that the Mass-Ratio distributions of short-period and long-period binaries are substantially different. It also indicates that the Mass distribution of the secondary stars is not the same as that of the single stars.
Tsevi Mazeh - One of the best experts on this subject based on the ideXlab platform.
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On the Mass-Ratio Distribution of Spectroscopic Binaries
The Astrophysical Journal, 2003Co-Authors: D. Goldberg, Tsevi Mazeh, David W. LathamAbstract:In this paper we derive the Mass-Ratio and secondary-Mass distributions of a large, well-defined, complete sample of 129 spectroscopic binaries with periods between 1 and 2500 days. The binaries, whose orbits were published recently, were detected by a systematic radial-velocity survey of a sample of more than 1400 large proper motion stars. Three features stand out in the Mass-Ratio distribution: a rise as the Mass Ratio goes down to q ~ 0.2, a sharp drop below q ~ 0.2, and a smaller peak at q ~ 0.8. Another way to characterize the results is to state that the distribution includes two populations, one with a high asymmetric peak at q ~ 0.2 and another with a smaller peak at q ~ 0.8, while the minimum between the two populations is centered at q ~ 0.55. The size of the binary sample allows us to divide it into two subsamples and look for differences in the Mass-Ratio distributions of the two subsamples. We performed two different divisions: one into Galactic halo versus disk populations, and the other into high- and low-Mass primary stars (above and below 0.67 M☉). The former division yields differences with moderate statistical significance of 88%, while the latter is more significant at a level of 97%. Our analysis suggests that the rise toward low Mass Ratios does not appear in the Mass-Ratio distribution of the halo binaries. The other sepaRation shows a broad peak at Mass Ratio of q ~ 0.8-1 for the subsample of binaries with low-Mass primaries but no corresponding peak in the subsample with high-Mass primaries. We discuss our findings and their application to theories of binary formation.
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The Mass-Ratio distribution of the spectroscopic binaries in the Pleiades.
Astronomy and Astrophysics, 1994Co-Authors: D. Goldberg, Tsevi MazehAbstract:This is a short study of the Mass-Ratio distribution of the short-period binaries in the Pleiades. The study is based on a complete, though extremely small, sample of binaries, out of the thorough radial-velocity survey of Mermilliod et al. (1992). The sample of nine spectroscopic binaries is analysed with a recently published algorithm, which is free of the disadvantages of some of the previous approaches to the problem. The emerging trend of the Mass-Ratio distribution is flat, or perhaps slightly rising toward unity, similar to that of the nearby binaries with G-dwarf primaries recently found
Y.-g. Yang - One of the best experts on this subject based on the ideXlab platform.
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Deep, Low Mass Ratio Overcontact Binary Systems. V. The Lowest Mass Ratio Binary V857 Herculis
The Astronomical Journal, 2005Co-Authors: Sheng-bang Qian, Lei Zhu, B. Soonthornthum, J.-z. Yuan, Y.-g. YangAbstract:Charge-coupled device (CCD) photometric light curves in the B, V, and R bands of the complete eclipsing binary star V857 Her are presented. It is shown that the light curves of the W UMa-type binary are symmetric and of A type according to Binnendijk's classification. Our four epochs of light minimum along with others compiled from the literature were used to revise the period and study the period change. Weak evidence indicates that the orbital period of V857 Her may show a continuous increase at a rate of dP/dt = +2.90 x 10(-7) days yr(-1). The photometric parameters of the system were determined with the 2003 version of the Wilson-Devinney code. It is shown that V857 Her is a deep overcontact binary system with f = 83.8% +/- 5.1%. The derived Mass Ratio of q = 0.06532 +/- 0.0002 suggests that it has the lowest Mass Ratio among overcontact binary systems. As the orbital period increases, the decrease of the Mass Ratio will cause it to evolve into a single rapidly rotating star when it meets the more familiar criterion that the orbital angular momentum be less than 3 times the total spin angular momentum. To understand the evolutionary state of the system, long-term photometric monitoring and spectroscopic observations will be required.
Sinan Melih Nigdeli - One of the best experts on this subject based on the ideXlab platform.
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Mass Ratio factor for optimum tuned Mass damper strategies
International Journal of Mechanical Sciences, 2013Co-Authors: Gebrail Bekdaş, Sinan Melih NigdeliAbstract:Abstract Conventional expressions proposed for the optimum design of tuned Mass dampers (TMD) are a rapid source to reach the information on frequency and damping Ratios. These expressions are related to a preselected Mass Ratio. The effect of Mass Ratio was investigated by conducting analyses carried out under different earthquakes records for SDOF structures with various periods. Results showed that Mass Ratio, external excitation and period of the structure are effective on the performance of the TMD. Also, the usage of the expressions is not feasible in some situations. For that reason, a metaheuristic algorithm called Harmony Search (HS) was employed to find more feasible results. The comparisons between proposed method and simple expressions showed that the optimum parameters are more economical and feasible for HS approach.
Andrew Gould - One of the best experts on this subject based on the ideXlab platform.
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ogle 2017 blg 1434lb eighth q 1 10 4 Mass Ratio microlens planet confirms turnover in planet Mass Ratio function
Acta Astronomica, 2018Co-Authors: A Udalski, Yoonhyun Ryu, Sedighe Sajadian, Andrew Gould, P Mroz, R Poleski, M K SzymanskiAbstract:We report the discovery of a cold Super-Earth planet (mp=4.4±0.5 M⊕) orbiting a low-Mass (M=0.23±0.03) M⊙ dwarf at projected sepaRation a⊥=1.18±0.10 a.u., i.e., about 1.9 times the distance the snow line. The system is quite nearby for a microlensing planet, DL=0.86±0.09 kpc. Indeed, it was the large lens-source relative parallax πrel=1.0 mas (combined with the low Mass M) that gave rise to the large, and thus well-measured, "microlens parallax" πE∝(πrel/M)1/2 that enabled these precise measurements. OGLE-2017-BLG-1434Lb is the eighth microlensing planet with planet-host Mass Ratio q<1×10-4. We apply a new planet-detection sensitivity method, which is a variant of "V/Vmax", to seven of these eight planets to derive the Mass-Ratio function in this regime. We find dN/d lnq ∝ qp, with p=1.05+0.78-0.68, which confirms the "turnover" in the Mass function found by Suzuki et al. relative to the power law of opposite sign n=-0.93±0.13 at higher Mass Ratios q≳2×10-4. We combine our result with that of Suzuki et al. to obtain p=0.73+0.42-0.34.
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ogle 2017 blg 1434lb eighth q 1 10 4 Mass Ratio microlens planet confirms turnover in planet Mass Ratio function
arXiv: Earth and Planetary Astrophysics, 2018Co-Authors: A Udalski, Yoonhyun Ryu, Sedighe Sajadian, Andrew Gould, P Mroz, R Poleski, M K SzymanskiAbstract:We report the discovery of a cold Super-Earth planet (m_p=4.4 +/- 0.5 M_Earth) orbiting a low-Mass (M=0.23 +/- 0.03 M_Sun) M dwarf at projected sepaRation a_perp = 1.18 +/- 0.10 AU, i.e., about 1.9 times the snow line. The system is quite nearby for a microlensing planet, D_Lens = 0.86 +/- 0.09 kpc. Indeed, it was the large lens-source relative parallax pi_rel=1.0 mas (combined with the low Mass M) that gave rise to the large, and thus well-measured, "microlens parallax" that enabled these precise measurements. OGLE-2017-BLG-1434Lb is the eighth microlensing planet with planet-host Mass Ratio q < 1 * 10^-4. We apply a new planet-detection sensitivity method, which is a variant of "V/V_max", to seven of these eight planets to derive the Mass-Ratio function in this regime. We find dN/d(ln q) ~ q^p, with p = 1.05 (+0.78,-0.68), which confirms the "turnover" in the Mass function found by Suzuki et al. relative to the power law of opposite sign n = -0.93 +/- 0.13 at higher Mass Ratios q >~ 2 * 10^-4. We combine our result with that of Suzuki et al. to obtain p = 0.73 (+0.42,-0.34).
