Leavitt's Law
Plate 070 Physics Poster
Plate 70 speaks for itself: “Slow is bright.”
The Physics
Henrietta Leavitt found that Cepheid variables with longer pulsation periods are more luminous. Calibrated, the period gives the true brightness, turning Cepheids into distance markers.
M_V = a log₁₀ P + b
- M_V: absolute visual magnitude, dimensionless
- P: pulsation period, days
- a, b: calibration constants
Longer-period Cepheids are brighter. M_V = −2.43(log P − 1) − 4.05.
Sources
- H. S. Leavitt, E. C. Pickering, Harvard Coll. Obs. Circ. 173 (1912).
- G. F. Benedict et al., Astron. J. 133, 1810 (2007).
On the poster
Plate 070, “Leavitt's Law”: the pixel-art plate with its slogan “Slow is bright.”, the key equation and the facts panel shown above. Pixelated Physics. Physics. Personified.
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Field notes
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