  A small planet is not necessarily a terrestrial planet. Planets that form
beyond the snow line with too little mass to seed rapid gas accretion (<~ 10
Earth masses) should be rich in volatile ices like water and ammonia. Some of
these planets should migrate inward by interacting with a circumstellar disk or
with other planets. Such objects can retain their volatiles for billions of
years or longer at ~1 AU as their atmospheres undergo slow hydrodynamic escape.
These objects could appear in future surveys for extrasolar Earth analogs.
