Thermal Background Budgets for Mid-Infrared Direct Imaging of Mature Giant Planets

This study computes a detection budget for a clearly bounded question: At ten microns, where planets emit thermally rather than reflecting starlight, how do planet-star contrasts compare with the visible band, and how much of the budget is set by telescope and sky thermal emission rather than by the planet? A 1000 K planet reaches a ten-micron contrast of 8.872e-04; a 500 K planet reaches 1.412e-06. An Earth-temperature planet gives 1.614e-07, about three orders of magnitude above its reflected-light contrast. A 125 K Jupiter analogue gives only 2.861e-08 at ten microns. All values are computed from published anchor values and stated assumptions by a deposited script; the study is simulated and computed throughout, not measured. Mid-infrared contrasts reward warm planets and punish cold ones, and the zodiacal floor, not telescope temperature, caps the space advantage at roughly a factor of five in signal-to-noise.