Investigations of the Rotation Pole from the Morphology of Dust Fans of Comet 81P/Wild 2

2004 ◽  
Vol 616 (2) ◽  
pp. 1278-1283 ◽  
Author(s):  
R. Vasundhara ◽  
Pavan Chakraborty
Keyword(s):  
Rotation Pole

scholarly journals Observational evidence for polar spots

1996 ◽  
Vol 176 ◽  
pp. 289-298 ◽  
Author(s):  
Klaus G. Strassmeier
Keyword(s):  
Image Reconstruction ◽  
Observational Evidence ◽  
Doppler Imaging ◽  
Stellar Rotation ◽  
Rotation Pole ◽  
Ill Posed

“Are results from ill-posed problems, like Doppler-imaging, conclusive at all?” and “Could polar spots be simple image-reconstruction artifacts?” are often asked questions. Although I can not definitively answer them, I will present observational evidence for the existence of cool starspots at or very near a stellar rotation pole.

scholarly journals Spin rotation, Chandler wobble and free core nutation of isolated multi-layer pulsars

2012 ◽  
Vol 8 (S291) ◽  
pp. 392-392
Author(s):  
Alexander Gusev ◽  
Irina Kitiashvili
Keyword(s):  
Neutron Star ◽  
Differential Rotation ◽  
Heat Dissipation ◽  
Inner Core ◽  
Outer Core ◽  
Chandler Wobble ◽  
Time Of Arrival ◽  
Layer Model ◽  
Free Core Nutation ◽  
Rotation Pole

AbstractAt present time there are investigations of precession and nutation for very different celestial multi-layer bodies: the Earth (Getino 1995), Moon (Gusev 2010), planets of Solar system (Gusev 2010) and pulsars (Link et al. 2007). The long-periodic precession phenomenon was detected for few pulsars: PSR B1828-11, PSR B1557-50, PSR 2217+47, PSR 0531+21, PSR B0833-45, and PSR B1642-03. Stairs, Lyne & Shemar (2000) have found that the arrival-time residuals from PSR B1828-11 vary periodically with a different periods. According to our model, the neutron star has the rigid crust (RC), the fluid outer core (FOC) and the solid inner core (SIC). The model explains generation of four modes in the rotation of the pulsar: two modes of Chandler wobble (CW, ICW) and two modes connecting with free core nutation (FCN, FICN) (Gusev & Kitiashvili 2008). We are propose the explanation for all harmonics of Time of Arrival (TOA) pulses variations as precession of a neutron star owing to differential rotation of RC, FOC and crystal SIC of the pulsar PSR B1828-11: 250, 500, 1000 days. We used canonical method for interpretation TOA variations by Chandler Wobble (CW) and Free Core Nutation (FCN) of pulsar.The two - layer model can explain occurrence twin additional fashions in rotation pole motion of a NS: CW and FCN. In the frame of the three-layer model we investigate the free rotation of dynamically-symmetrical PSR by Hamilton methods. Correctly extending theory of SIC-FOC-RC differential rotation for neutron star, we investigated dependence CW, ICW, FCN and FICN periods from flatness of different layers of pulsar.Our investigation showed that interaction between rigid crust, RIC and LOC can be characterized by four modes of periodic variations of rotation pole: CW, retrograde Free Core Nutation (FCN), prograde Free Inner Core Nutation (FICN) and Inner Core Wobble (ICW). In the frame of the three-layer model we proposed the explanation for all pulse fluctuations by differential rotation crust, outer core and inner core of the neutron star and received estimations of dynamical flattening of the pulsar inner and outer cores, including the heat dissipation. We have offered the realistic model of the dynamical pulsar structure and two explanations of the feature of flattened of the crust, the outer core and the inner core of the pulsar.

scholarly journals On the Correlation between Earthquake Occurrence and Disturbances in the Path of the Rotation Pole

1972 ◽  
Vol 48 ◽  
pp. 215-220 ◽  
Author(s):  
Michael A. Chinnery ◽  
Fred J. Wells
Keyword(s):  
Observational Studies ◽  
Polar Motion ◽  
Theoretical Calculations ◽  
Large Earthquake ◽  
Chandler Wobble ◽  
Earthquake Occurrence ◽  
Rotation Pole

The hypothesis that earthquakes may be the principal excitation of the Chandler motion of the rotation pole is examined in the light of recent theoretical and observational developments. There is some doubt about the amount of excitation by a large earthquake necessary to maintain the Chandler Wobble, but it appears to be about 10 ft. Theoretical calculations for the Alaskan Earthquake (M = 8½) give available excitations in the range 1–5 ft, but there are considerable uncertainties in these calculations. Earthquakes may be able to provide all of the required excitation, or only a small portion (10% or less). The problem is confused by observational studies, which show differences between various sets of data on polar motion which seem to be larger than the expected error in each set. The earthquake hypothesis, though reasonable, is still very much open to debate.

scholarly journals Long-Period Nutational-Precessional Motions of the Instantaneous Earth Rotation Pole

2020 ◽  
Vol 162 (4) ◽  
pp. 467-480
Author(s):  
V.Yu. Belashov ◽  
◽  
E.S. Belashova ◽  
O.A. Kharshiladze ◽  
◽  
...  
Keyword(s):  
Earth Rotation ◽  
Long Period ◽  
Rotation Pole

Constraints on the Rheology of the Earth's Deep Mantle from Decadal Observations of the Earth's Figure Axis and Rotation Pole

2020 ◽  
Author(s):  
Alexandre Couhert ◽  
Christian Bizouard ◽  
Flavien Mercier ◽  
Kristel Chanard ◽  
Marianne Greff ◽  
...  
Keyword(s):  
Time Scales ◽  
Global Constraints ◽  
Geological Time ◽  
Rotation Pole ◽  
The Earth ◽  
Vlbi Data ◽  
Data Yield ◽  
External Forces ◽  
Short Time

<p>The over four decades long record of Satellite Laser Ranging (SLR) observations to a variety of historical geodetic spherical satellites makes it possible to directly observe the long-term (seasonal to decadal time scales) displacement of the Earth’s mean axis of maximum inertia, namely its principal figure axis, with respect to the crust, through the determination of the degree-2 order-1 geopotential coefficients over the 34-year period 1984—2017.</p><p>On the other hand, the pole coordinate time series (mainly from GPS and VLBI data), yield the motion of the rotation pole with even a greater accuracy.</p><p>The time-dependent nature of the response of the Earth’s mantle to external forces, where it behaves either elastically on short time scales (seconds) or like a viscous fluid over geological time scales (millions of years), is poorly constrained at decadal periods. Here we propose to relate oscillations of the figure axis to those of the Earth’s rotation pole (through the Euler-Liouville equations) to study the mass-related excitation of polar motion and provide global constraints on the rheological properties of the deep Earth.</p>

Observations of the Celestial Ephemeris Pole

1995 ◽  
Vol 10 ◽  
pp. 232-236 ◽  
Author(s):  
R.S. Gross
Keyword(s):  
Reference Frame ◽  
Polar Motion ◽  
Resonance Effects ◽  
Rotation Pole ◽  
The North ◽  
Geophysical Excitation ◽  
Spin Parameter ◽  
Fixed Reference ◽  
Motion Parameters ◽  
Excitation Processes

AbstractSpace-geodetic measurement systems are capable of determining: (1) a terrestrial, body-fixed reference frame defined in practice by the stated positions and secular motions of a set of observing stations, (2) a celestial, space-fixed reference frame defined in practice by the stated locations of celestial objects, and (3) the rotation parameters linking these two frames together. Five parameters are conventionally used to specify the orientation of the terrestrial frame with respect to the celestial frame: two nutation parameters, two polar motion parameters, and one spin parameter. The celestial ephemeris pole (CEP) is defined as the north pole of that axis about which the spin parameter (UT1) is measured. The two nutation parameters locate the CEP in the celestial frame, and the two polar motion parameters locate the CEP in the terrestrial frame. By examining the frame transformation matrices, an expression relating the location of the rotation pole to that of the CEP can be derived. In order to compare theoretical predictions with observations, results of models for the effect on the nutations of geophysical excitation processes such as diurnal oceanic current and sea level height variations should not only be given in terms of the location of the CEP (rather than of the rotation pole), but must also account for the resonance effects of the free core nutation.

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