Sydney D'Silva

Ph: (703) 346-7306
Time-Distance Helioseismology
Time-distance helioseismology is a method to study the interior of the Sun by computing travel time of individual acoustic wavepackets as they travel through the Sun between two spatially separated locations on its surface. I have contributed to the theoretical development of this field.
eg.  Theoretical Foundations of Time-Distance Helioseismology

Helioseismic Tomography
Helioseismic tomography is a form of the tomographic techniques adapted to image the interior of the Sun from observations of the acoustic oscillations at the surface. The important adaptation is the computation of travel time through time-distance helioseismology. I have contributed in the aspects of its adaptation and improvement.
eg.  A Note on Helioseismic Tomography

Morphology & Dynamics of Sunspots
This study involves the dynamics of their progenitors -- magnetic flux tubes --- from the region
of their origin (200,000 km beneath the solar surface) through a highly turbulent convectively unstable region. We modeled the flux tube to be a one-dimensional string with all properties of a magnetic flux tube allowed to move in the three-dimensional space of the convection zone. We could successfully explain a number of dynamical and morphological properties of sunspots if the magnetic field strength of the flux tubes at the region of their origin were of the order of 100,000 G. This is order of magnitude larger than the field that would be in energy equipartition with the turbulent motions.
A Theoretical Model for Tilts of Bipolar Magnetic Regions

Publications in Solar Physics and Biology.

A Few Publications:

(1) Sydney D'Silva, Equivalence between Duvall's Law and the Time-Distance Curve,
     The Astrophysical Journal Letters, (2001) 549, L135.
(2) Sydney D'Silva, `Time-Distance Helioseismology at High Frequencies',
     The Astrophysical Journal Letters, (2001) 548, L107.
(3) Sydney D'Silva, `A Note on Helioseismic Tomography',
     The Astrophysical Journal Letters, (2001) 547  L81.

Astronomy Picture of the Day
Picture of the Day
McMath Pierce Solar Telescope
Solar Telescopes
NMNH Museum
Code Samples
Code Samples
Sunspot Formation
Point Location in Equal Balls
Demo of ppower4
A Presentation

The Sun Today The Sun Today

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