Whether the higher occurrence of giant planets being hosted by metal-rich versus metal-poor stars results from formation or from pollution has been a question of intense debate. We present new patterns that emerge when planet/star systems are separat
ed by stellar [Fe/H], and when systems with stellar companions are separated out. These differences can best be explained if the onset of high eccentricity planet migration is also a time when planet are sent into merge with the star. Planet migration into the star is likely a complementary explanation to the view that systems with higher initial iron abundance form more planets, and that more crowded planets are more likely to scatter into eccentric orbits. Planets of iron-rich single stars have eccentricity distributions that are higher than planets of iron-poor single stars (where rich and poor are stars whose [Fe/H] is above and below solar, respectively). Stars with planets that have a stellar companion comprise a third population of systems in which the stars are preferentially iron-rich. We describe new patterns that are best explained by eccentric planet migration being associated with other planets migrating into the star. Though medium planets are more numerous than giant planets at periods greater than three days, giant planets are more numerous than medium planets at the shortest periods. Since giant planets migrate into the star faster, we show this as evidence of giant planet migration. Planet migration into the star is certain to be an important part of planetary system evolution.
The destruction of planets by migration into the star will release significant amounts of energy and material, which will present opportunities to observational study planets in new ways. To observe planet destruction, it is important to understand t
he processes of how this energy and material is released as planets are destroyed. It is not known how fast the large amounts of energy and material are released, making it difficult to predict how observable planet destruction will be. There is a huge amount of energy made available by falling deep into the stars potential well: Simple calculations show that many of the currently known hot Jupiters can potentially produce events as luminous as a small nova if the energy is released fast enough. To observe these events, the important questions are how will this energy be released, and whether the energy will be released rapidly enough to create an event luminous enough to be found by transient surveys. Alternatively, if planet destruction is slowed by the inward migration alternating with periods of outward migration caused by Roche lobe overflow (RLOF), then the primary signature may be the effects of the release of large amounts of gas. The infall of this gas also may significantly contribute to the systems luminosity. The release of planetary gas may be a searchable signature of planet destruction. Signs of runaway RLOF and outward or alternating RLOF should be searched for. Observing planet destruction will provide a new window for study of exoplanets.
