Bondi Hoyle Capture Radius
Compute the Bondi–Hoyle capture scale 2μ/(v²+c_s²) in consistent units; not an accretion-rate estimate.
Description
A Bondi–Hoyle capture scale balances gravity with relative-flow and sound-speed terms.
A Bondi–Hoyle capture scale balances gravity with relative-flow and sound-speed terms. Its characteristic radius alone is not a mass accretion rate.1
Compute the Bondi–Hoyle capture scale 2μ/(v²+c_s²) in consistent units; not an accretion-rate estimate.
When to use Bondi Hoyle Capture Radius
Use this tool to compute the Bondi–Hoyle capture scale 2μ/(v²+c_s²) in consistent units; not an accretion-rate estimate.
Prepare the orbital state or model parameters in one reference frame. Confirm compatible distance/time units and the stated angular and gravitational-parameter conventions.
How to use Bondi Hoyle Capture Radius and understand its results
- Prepare the orbital state or model parameters in one reference frame. Confirm compatible distance/time units and the stated angular and gravitational-parameter conventions.
- Enter mu, relativeSpeed, soundSpeed using the field table and calculation rules, then run the tool.
- Read accretionRadius. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| mu | Gravitational parameter, using the same distance and time units throughout; km³/s² for km and seconds. | number | Required |
| relativeSpeed | Relative speed | number | Required |
| soundSpeed | Sound speed | number | Required |
Enter positive μ and nonnegative flow-relative and sound speeds in matching units. At least one speed must be nonzero so the denominator is positive and finite. The tool returns a length in the unit implied by μ and the velocities.
captureRadius = 2μ/(relativeSpeed²+soundSpeed²) Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| accretionRadius | Accretion radius | number |
{
"input": {
"mu": 10,
"relativeSpeed": 3,
"soundSpeed": 1
},
"output": {
"accretionRadius": 2
}
}Limitations and assumptions
Density, feedback, angular momentum and detailed gas flow are not supplied. The estimate is a model scale, without a predicted accretion rate or a guarantee that matter is captured.
Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.
Alternative or Complementary methods
Use Conic Vis Viva Speed: Evaluate vis-viva for elliptic positive-a or hyperbolic negative-a states with an accessible radius, extending the existing circular-orbit operation. For a complementary task, use Entry Ballistic Coefficient: Compute the mass-to-drag-area ballistic coefficient from supplied aerodynamic reference quantities.
References
-
Bondi Hoyle Capture Radius — tool.io
Similar or alternative tools
- Conic Vis Viva Speed
Evaluate vis-viva for elliptic positive-a or hyperbolic negative-a states with an accessible radius, extending the existing circular-orbit operation.
- Entry Ballistic Coefficient
Compute the mass-to-drag-area ballistic coefficient from supplied aerodynamic reference quantities.