RE: Supersized rocky planets are out there.
June 3, 2014 at 1:12 pm
(This post was last modified: June 3, 2014 at 1:15 pm by Jackalope.)
(June 3, 2014 at 12:08 pm)Chuck Wrote:(June 3, 2014 at 12:34 am)max-greece Wrote: Interestingly it is 11 billion years old apparently. That's much older than we thought rocky planets could be.
Wouldn't really think so. Most of the materials from which terresterial planets are made were created inside very large, short lived stars that go supernova at the end of their lives. These stars have life expectancies measured in millions, not billions of years.
Current view is Universe is 13.7 billion years old, and the first generation of stars were around by 13 billion years ago.
By the time this planet formed 11 billions ago, the universe already had 2 billion years, enough to go through several dozen of generations of stars that manufactured and distributed terresterial planet material, to prepare the scene for terresterial planet formation.
I wouldn't think so, either. The population III stars (i.e. the oldest metal-free[*] stars) are currently thought to have been (at least in part) supermassive giant stars that went supernova after only a few million years, seeding the area with the first 26 elements (as heavy as iron). None of these stars have ever been observed, their existence is inferred both from cosmological models and observation of quasar spectra. If any long-lived population III stars still exist, they would have to be too small to be observable or go supernova.
The population II stars (relatively metal-poor, compared to later similar population I stars) are believed to have first produced the other elements - pop II stars that we can observe today are *ancient*, up to almost the very beginning of star formation. After several generations of forming short-lived supermassive pop III stars, it's quite conceivable within existing models that there would be early pop II stars that lived fast, died young, producing the elements heavier than iron - and, really, elements heavier than iron are not required to form terrestrial planets.
Kepler 10 is a type G star like our sun, with 70% of the sun's metallicity. Given it's mass, age, and metallicity, it would be within the population II group (our sun is population I). Iron, et al, were obviously present in quantity when Kepler 10 formed (a star with Kepler 10's mass would not produce iron, it would have to be present at time of formation).
I don't see a problem with 11-billion year old rocky planets either.
[*] In this context, "metal" means elements heavier than helium.
