Studying the Properties of Spacetime with an Improved Dynamical Model of the Inner Solar System

Studying the Properties of Spacetime with an Improved Dynamical Model of the Inner Solar System

Physical properties of the Sun (orientation of rotation axis, oblateness coefficient <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>J</mi><mrow><mn>2</mn><mo>⊙</...

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Bibliographic Details
Main Authors: Dmitry Pavlov, Ivan Dolgakov
Format: Article
Language:English
Published: MDPI AG 2024-11-01
Series:Universe
Subjects:
sun
radio astronomy
gravitational constant
planetary ephemerides
Online Access:https://www.mdpi.com/2218-1997/10/11/413
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Summary:Physical properties of the Sun (orientation of rotation axis, oblateness coefficient <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>J</mi><mrow><mn>2</mn><mo>⊙</mo></mrow></msub></semantics></math></inline-formula>, and change rate of the gravitational parameter <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mover accent="true"><mi>μ</mi><mo>˙</mo></mover><mo>⊙</mo></msub></semantics></math></inline-formula>) are determined using a dynamical model describing the motion of the Sun, planets, the Moon, asteroids, and Trans-Neptunian objects (TNOs). Among the many kinds of observations used to determine the orbits and physical properties of the bodies, the most important for our study are precise interplanetary ranging data: Earth–Mercury ranges from MESSENGER spacecraft and Earth–Mars ranges from Odyssey and MRO. The findings allow us to improve the model of the Sun in modern planetary ephemerides. First, the dynamically determined direction of the Sun’s pole is ≈2° off the visible axis of rotation of the Sun’s surface, which is corroborated by present knowledge of the Sun’s interior. Second, the change rate of the Sun’s gravitational parameter is found to be smaller (in absolute value) than the nominal value derived from the estimate of mass loss through radiation and solar wind. Possible interpretations are discussed.
ISSN:2218-1997

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