Linear Doppler Beaming Amplitude
Compute a small-velocity Doppler-beaming flux semi-amplitude using a supplied band-dependent coefficient and consistent velocity units.
Description
Doppler beaming changes observed flux at small radial velocities through a band-dependent coefficient.
Doppler beaming changes observed flux at small radial velocities through a band-dependent coefficient. A flux semi-amplitude is a fractional modulation, not a velocity estimate by itself.1
Compute a small-velocity Doppler-beaming flux semi-amplitude using a supplied band-dependent coefficient and consistent velocity units.
When to use Linear Doppler Beaming Amplitude
Use this tool to compute a small-velocity Doppler-beaming flux semi-amplitude using a supplied band-dependent coefficient and consistent velocity units.
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 Linear Doppler Beaming Amplitude 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 radialVelocitySemiAmplitude, lightSpeed, beamingCoefficient using the field table and calculation rules, then run the tool.
- Read fractionalFluxSemiAmplitude, partsPerMillion. 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 |
|---|---|---|---|
| radialVelocitySemiAmplitude | Radial velocity semi amplitude | number | Required |
| lightSpeed | Light speed | number | Required |
| beamingCoefficient | Beaming coefficient | number | Required |
Enter a nonnegative radial-velocity semi-amplitude, positive light speed in the same velocity unit and nonnegative coefficient. Velocity/lightSpeed must be strictly below 0.01. The tool returns the fractional semi-amplitude and parts per million; zero velocity or coefficient returns zero.
fractionalAmplitude = coefficient × radialVelocitySemiAmplitude/lightSpeed; ppm = fraction × 10⁶ Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| fractionalFluxSemiAmplitude | Fractional flux semi amplitude | number |
| partsPerMillion | Parts per million | number |
{
"input": {
"radialVelocitySemiAmplitude": 30,
"lightSpeed": 300000,
"beamingCoefficient": 4
},
"output": {
"fractionalFluxSemiAmplitude": 0.0004,
"partsPerMillion": 400
}
}Limitations and assumptions
The coefficient is supplied rather than derived from a spectrum or bandpass. Relativistic corrections, other brightness variations and a time-dependent light curve are not modeled.
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 Near Resonance Ttv Scale: Evaluate a supplied near-resonance TTV scaling coefficient P·mass-ratio/(π·|Δ|); free eccentricity, exact resonance and mass inference are not modeled. For a complementary task, use Oberth Specific Energy Comparison: Compare specific orbital-energy gains from the same instantaneous prograde burn at two supplied speeds.
References
-
Linear Doppler Beaming Amplitude — tool.io
Similar or alternative tools
- Near Resonance Ttv Scale
Evaluate a supplied near-resonance TTV scaling coefficient P·mass-ratio/(π·|Δ|); free eccentricity, exact resonance and mass inference are not modeled.
- Oberth Specific Energy Comparison
Compare specific orbital-energy gains from the same instantaneous prograde burn at two supplied speeds.