Calculate stellar motion using wavelength change, Doppler ratio, and speed. See examples, formulas, and practical usage steps. Track redshift and blueshift results across responsive input panels.
| Object | Line | Reference wavelength (nm) | Observed wavelength (nm) | Velocity (km/s) | Direction |
|---|---|---|---|---|---|
| Sirius A | Hydrogen H-alpha | 656.28 | 656.85 | 260.27 | Redshift |
| Betelgeuse | Hydrogen H-alpha | 656.28 | 655.94 | -155.35 | Blueshift |
| Rigel | Sodium D | 589.00 | 589.42 | 213.70 | Redshift |
| Vega | Calcium K | 393.37 | 393.15 | -167.71 | Blueshift |
Stellar velocity is the speed of a star along our line of sight. It is often called radial velocity. This calculator estimates that motion from wavelength shift, frequency shift, or direct redshift input. It supports both classical and relativistic approaches.
In spectroscopy, a known reference line is compared with an observed line. When the observed wavelength is longer, the source is moving away. That pattern is called redshift. When the observed wavelength is shorter, the source is moving closer. That pattern is called blueshift.
This page is useful for chemistry-adjacent spectroscopy work because line identification and measurement discipline matter. The same careful handling of reference transitions, observed peaks, and instrument output supports reliable calculations. Good inputs lead to better velocity estimates.
The wavelength mode is practical when you already have rest and observed wavelengths from a spectrum. The frequency mode is helpful when your data source reports frequencies. The direct redshift mode is fast when a previous pipeline already produced a z value.
The relativistic option is the better choice for larger shifts. It accounts for high-speed motion more accurately. The classical approximation is simpler and works best for small shifts. Showing both options helps you compare results and understand the impact of the model.
The result block reports redshift, beta, velocity in meters per second, velocity in kilometers per second, and the percentage of light speed. That summary is useful for reporting, cross-checking, and exporting into notes or lab-style records.
The graph gives a quick visual comparison between reference and observed values. The example table shows sample spectral lines and estimated motion. Together, these features turn a basic equation into a more complete workflow for teaching, review, and practical spectral analysis.
Wavelength shift: z = (λobserved − λreference) / λreference
Frequency shift: z = (freference / fobserved) − 1
Relativistic beta: β = ((1 + z)2 − 1) / ((1 + z)2 + 1)
Velocity: v = βc
Classical approximation: v ≈ zc
Here, c is the speed of light. A positive velocity means recession. A negative velocity means approach.
It estimates stellar radial velocity from spectral shift data. You can use wavelengths, frequencies, or a direct redshift value. The result shows direction and speed.
Use it when the shift is not tiny or when you want the safer scientific choice. It better represents motion at higher fractions of light speed.
A positive value means the object is receding from the observer. That matches redshift, where observed wavelengths become longer than reference wavelengths.
A negative value means the object is approaching the observer. That matches blueshift, where observed wavelengths become shorter than reference wavelengths.
Yes. The calculator supports frequency-based input. It converts the frequency relationship into redshift and then estimates velocity with your chosen model.
Some observation tools or research notes already provide z. This mode avoids re-entering spectral values and gives a fast velocity estimate from that existing result.
They are sample teaching values for demonstration. They help show how redshift and blueshift affect the output and how the table can be organized.
No. It is a practical calculator for quick estimates. High-precision work still needs calibration checks, line fitting, uncertainty analysis, and instrument corrections.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.