Temperature evolution over time of Jupiter-like FFPs heated by red giant radiation before ejection. Shown is the approximate temperature evolution of Jupiter-like FFPs, assuming they initially orbited a Sun-like host star with initial SMAs of 1.5 au (blue curve), 2 au (cyan), 3 au (yellow), or 5 au (magenta). Ejection is assumed to have occurred at the end of the AGB phase, either through the WD kick directly or orbital instability. The unheated expected temperature of an approximately 10 Gyr old Jupiter-like planet is shown in red as comparison. The planets retain an elevated temperature for many millions of years. The stellar mass and luminosity evolution was calculated using the stellar evolution code SSE (J. R. Hurley et al. 2000). On the order of 2% of the stellar energy flux was estimated to reach the planetary interior heat reservoir.