Upcoming direct imaging experiments may detect a new class of long-period , highly luminous , tidally powered extrasolar gas giants .
Even though they are hosted by \sim { Gyr } s - “ old ’ main-sequence stars , they can be as “ hot ’ as young Jupiters at \sim 100 { Myr } , the prime targets of direct imaging surveys .
They are on years-long orbits and presently migrating to “ feed ’ the “ hot Jupiters ’ .
They are expected from “ high- e ’ migration mechanisms , in which Jupiters are excited to highly eccentric orbits and then shrink semi-major axis by factor of \sim 10 - 100 due to tidal dissipation at close periastron passages .
The dissipated orbital energy is converted to heat , and if it is deposited deep enough into the atmosphere , the planet likely radiates steadily at luminosity L \sim 100 - 1000 L _ { Jup } ( 2 \times 10 ^ { -7 } -2 \times 10 ^ { -6 } L _ { \odot } ) during a typical \sim { Gyr } migration time scale .
Their large orbital separations and expected high planet-to-star flux ratios in IR make them potentially accessible to high-contrast imaging instruments on 10m-class telescopes . \sim 10 such planets are expected to exist around FGK dwarfs within \sim 50 { pc } .
Long-period RV planets are viable candidates , and the highly eccentric planet HD 20782b at maximum angular separation \sim 0.08 \arcsec is a promising candidate .
Directly imaging these tidally powered Jupiters would enable a direct test of high- e migration mechanisms .
Once detected , the luminosity would provide a direct measurement of the migration rate , and together with mass ( and possibly radius ) estimate , they would serve as a laboratory to study planetary spectral formation and tidal physics .