scholarly journals Stabilization of spacecraft orbital orientation mode without saturation of on board gyro system

2018 ◽  
pp. 1-30 ◽  
Author(s):  
Aleksandr Ivanovich Ignatov ◽  
Victor Vasil’yevich Sazonov
Keyword(s):  
Gyro System ◽  
Orbital Orientation

scholarly journals Testing the relativistic Doppler boost hypothesis for supermassive binary black holes candidates via broad emission line profiles

2019 ◽  
Vol 491 (3) ◽  
pp. 4023-4030 ◽  
Author(s):  
Zihao Song ◽  
Junqiang Ge ◽  
Youjun Lu ◽  
Xiang Ji
Keyword(s):  
Black Holes ◽  
Emission Lines ◽  
Binary Black Holes ◽  
Broad Emission ◽  
Line Region ◽  
Two Samples ◽  
Region Model ◽  
Orbital Orientation ◽  
The Continuum

ABSTRACT Optical periodicity QSOs found by transient surveys are suggested to be subparsec supermassive binary black holes (BBHs). An intriguing interpretation for the periodicity of some of those QSOs is that the continuum is radiated from the accretion disc associated with the BBH secondary component and modulated by the periodical rotation of the secondary via Doppler-boost effect. Close to edge-on orbital orientation can lead to more significant Doppler-boost effect and thus are preferred for these systems, which is distinct from those normal type-1 QSOs with more or less face-on orientations. Therefore, the profiles of broad lines emitted from these Doppler-modulated systems may be significantly different from other systems that are not Doppler modulated. We investigate the properties of the broad emission lines of optical-periodicity QSOs, including both a sample of QSOs that can be interpreted by the Doppler-modulated effects and a sample that cannot. We find that there is no obvious difference in the profiles and other properties of various (stacked) broad emission lines of these two samples, though a simple broad line region model would suggest significant differences. Our finding raises a challenge to the Doppler boost hypothesis for some of those BBHs candidates with optical periodicity.

Probing two-particle orbital orientation of bound states

2005 ◽  
Vol 70 (1) ◽  
pp. 81-87 ◽  
Author(s):  
J Berakdar ◽  
N. M Kabachnik
Keyword(s):  
Bound States ◽  
Orbital Orientation

Masticatory stress, orbital orientation and the evolution of the primate postorbital bar

2000 ◽  
Vol 38 (5) ◽  
pp. 667-693 ◽  
Author(s):  
Matthew J. Ravosa ◽  
Vivian E. Noble ◽  
William L. Hylander ◽  
Kirk R. Johnson ◽  
Erica M. Kowalski
Keyword(s):  
Masticatory Stress ◽  
Orbital Orientation

Asymptotic analysis of a model gyro system

2013 ◽  
Vol 49 (6) ◽  
pp. 760-764 ◽  
Author(s):  
Yu. A. Konyaev ◽  
D. V. Mikhailov ◽  
E. Yu. Romanova
Keyword(s):  
Asymptotic Analysis ◽  
Gyro System

scholarly journals Prospects for detecting the astrometric signature of Barnard’s Star b

2019 ◽  
Vol 623 ◽  
pp. A10 ◽  
Author(s):  
L. Tal-Or ◽  
S. Zucker ◽  
I. Ribas ◽  
G. Anglada-Escudé ◽  
A. Reiners
Keyword(s):  
Orbital Period ◽  
Mass Range ◽  
Periodic Signal ◽  
Wide Field ◽  
Space Telescope ◽  
Single Epoch ◽  
Low Amplitude ◽  
Orbital Orientation ◽  
True Mass

A low-amplitude periodic signal in the radial velocity (RV) time series of Barnard’s Star was recently attributed to a planetary companion with a minimum mass of ~3.2 M⊕ at an orbital period of ~233 days. The relatively long orbital period and the proximity of Barnard’s Star to the Sun raises the question whether the true mass of the planet can be constrained by accurate astrometric measurements. By combining the assumption of an isotropic probability distribution of the orbital orientation with the RV-analysis results, we calculated the probability density function of the astrometric signature of the planet. In addition, we reviewed the astrometric capabilities and limitations of current and upcoming astrometric instruments. We conclude that Gaia and the Hubble Space Telescope (HST) are currently the best-suited instruments to perform the astrometric follow-up observations. Taking the optimistic estimate of their single-epoch accuracy to be ~30μas, we find a probability of ~10% to detect the astrometric signature of Barnard’s Star b with ~50 individual-epoch observations. In case of no detection, the implied mass upper limit would be ~8 M⊕, which would place the planet in the super-Earth mass range. In the next decade, observations with the Wide-Field Infrared Space Telescope (WFIRST) may increase the prospects of measuring the true mass of the planet to ~99%.

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