Astronomy & space · University
Radius ratio from an idealized transit depth
Assume a dark small planet, central transit, no blending and uniform stellar brightness. Depth is a fraction, not a percentage.
Method and conditions
Assume a dark small planet, central transit, no blending and uniform stellar brightness. Depth is a fraction, not a percentage.
Rp/Rstar = sqrt(depth)
Worked examples
A simplified transit has fractional depth 0.0005. Neglect limb darkening and blending. Find planet radius divided by stellar radius. Round the final result to 4 decimal places if needed.
The blocked area ratio is depth, so the radius ratio is sqrt(0.0005).
0.0224
A simplified transit has fractional depth 0.0005. Neglect limb darkening and blending. Find planet radius divided by stellar radius. Round the final result to 4 decimal places if needed.
The blocked area ratio is depth, so the radius ratio is sqrt(0.0005).
0.0224
Try it
A simplified transit has fractional depth 0.0004. Neglect limb darkening and blending. Find planet radius divided by stellar radius. Round the final result to 4 decimal places if needed.
A simplified transit has fractional depth 0.0055. Neglect limb darkening and blending. Find planet radius divided by stellar radius. Round the final result to 4 decimal places if needed.
Check your work
Answers and marking notes
- 0.02
The blocked area ratio is depth, so the radius ratio is sqrt(0.0004).
- 0.0742
The blocked area ratio is depth, so the radius ratio is sqrt(0.0055).
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