origin of comets & KBOs

[border_ruffian]

I've heard that from the metal composition of our solar system, scientists know that the sun is at least a second- or third-generation star; does this mean that some of the comets or KBOs could have formed from the sun's predecessor stars?<br />

 

[CalliArcale]

It is entirely possible. In fact, the specimens collected recently by the Stardust spacecraft are consistent with that notion -- they contain substances that probably predate the solar system. (Results at present are extremely preliminary, so take this with a grain of salt, and watch for more news on the Stardust results as they work meticulously through the microscopic samples.) <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[border_ruffian]

If the sun is second- or third-generation, could it be possible that our solar system is as well? Might there have been other planets revolving around the sun's predecessors?<br /><br /><br />

 

[CalliArcale]

Yes; in fact, many scientists are of the opinion that the Earth and the other major planets formed after the Sun did, from the remains of whatever was here before.<br /><br />But Earth, being sufficiently large, will have melted these primordial dust particles into an unrecognizable blob as it accreted. So we can't test this theory by examining the Earth. Instead, we have to look at something with less mass, which won't have obliterated the particles that make it up. Something like a comet. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[border_ruffian]

Didn't the Sun also get the materials it needed to form from its predecessor stars after they have exploded as novae? -- the same stars from which formed comets and KBOs? <br /><br />But scientists who collect spacedusts from the upper atmosphere or through missions like Genesis or Stardust have identified microscopic dust grains that have isotopic compositions that just don't match our own sun. Why wouldn't it match? Isn't it the same stuff being recycled over and over again as stars form, live, die, and form again?<br />