AstroGrav Help /Data ElementsVersion 5.2.1

# Data Elements

Each object in an AstroGrav simulation has the following eight properties.

• Name
• Type
• Color
• Luminosity
• Mass
• Position
• Velocity

The name, type, color, luminosity, mass, and radius are physical properties that do not vary with the passage of time, and are called the object's physical elements

The position and velocity are properties that vary with the passage of time, and are 3D vector quantities that each require three values to describe. The simplest way to describe the position and velocity is to use the position and velocity components with respect to the origin of the coordinate frame, and these six values are called the object's absolute elements.

An alternative way to describe the position and velocity is to use the position and velocity components with respect to the object's parent, and these six values are called the object's rectangular elements.

While describing the position and velocity with position and velocity components is conceptually simple, it is often not very useful in practice. The six values describing the size, shape, and orientation of the object's orbit, together with the position of the object on its orbit, are usually more appropriate, and are called the object's orbital elements.

This way of describing an orbit is not unique, and there are alternatives to some of the orbital elements that are called the object's other elements.

Finally, there are a set of values that describe the object's relationship to its parent, and these are called the object's structure elements.

To summarise, each object in an AstroGrav simulation is described with the following data elements.

• Physical Elements are the physical properties that do not vary with the passage of time.

• Absolute Elements are the position and velocity components relative to the origin of the coordinate frame.

• Structure Elements are the properties of the object relative to its parent.

• Rectangular Elements are the position and velocity components relative to the object's parent.

• Orbital Elements describe the size, shape, and orientation of the object's orbit, together with the position of the object on its orbit.

• Other Elements are miscellaneous values that each provide a possible alternative to one of the orbital elements.