Dynamical Modeling of M13 Proper Motions

Structure of proper motions in a sunspot penumbra

The dangers of deprojection of proper motions

We re-examine the method of deprojection of proper motions, which has been used for finding the velocity ellipsoid of stars in the nearby Galaxy. This method is only legitimate if the lines of sight to the individual stars are uncorrelated with the stars’ velocities. Very simple models are used to show that spurious results similar to ones recently reported are obtained when velocity dispersion...

Constraining the Proper Motions of Two Magnetars

We attempt to measure the proper motions of two magnetars — the soft gamma-ray repeater SGR 1900+14 and the anomalous X-ray pulsar 1E 2259+586 — using two epochs of Chandra observations separated by ∼ 5 yr. We perform extensive tests using these data, archival data, and simulations to verify the accuracy of our measurements and understand their limitations. We find 90% upper limits on the prope...

Proper orthogonal decomposition of solar photospheric motions.

The spatiotemporal dynamics of the solar photosphere is studied by performing a proper orthogonal decomposition (POD) of line of sight velocity fields computed from high resolution data coming from the MDI/SOHO instrument. Using this technique, we are able to identify and characterize the different dynamical regimes acting in the system. Low-frequency oscillations, with frequencies in the range...

Proper Motions of Ansae in Ngc

Para la nebulosa planetaria NGC 7009, presentamos una comparación de dos conjuntos de datos sin publicar del archivo del Very Large Array tomados con una separación temporal de 8.09 años para confirmar los movimientos propios observados en el óptico en sus ansas. Determinamos valores de 23±6 y 34±10 mas año para las ansas este y oeste, respectivamente. Hay evidencia marginal de que las densidad...