Astronomy & space · University
Distance from an unextinguished distance modulus · formula reference
This simplified model neglects extinction. Apparent and absolute magnitudes must use the same band.
Formula
This simplified model neglects extinction. Apparent and absolute magnitudes must use the same band.
d(pc) = 10^((m−M+5)/5)
Worked example
A star has apparent magnitude 9 and absolute magnitude 4 in one band. Neglect extinction. Find distance in parsecs. Round the final result to 4 decimal places if needed. Answer in pc.
The distance modulus is 5. Rearrange m−M=5 log₁₀(d/10 pc).
100 pc
Prerequisites and checking
Algebra and the topic definitions. Keep units and rounding consistent. State the model conditions before applying the formula.
Further reading and review references
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