Re: Evidence of Vega planetary system

Dan Goodman wrote:

> If I remember correctly, the last I'd heard 1) stars like Vega weren't
> supposed to have planets and 2) If they did, they wouldn't have life.

I don't know of any definitive suggestion that stars like Vega shouldn't
have planets.  In fact, we already long since knew about Vega's
protoplanetary disk, so that idea was already shot to hell.  If it can
have a protoplanetary disk, it can certainly have planets.  All you need
is a little time.

As for life-bearing planets, that's a whole different story.  Vega's
time on the main sequence is probably way too short to allow its planets
to harbor life -- not only is there not much time, but the same
brightening effect that the Sun experienced since it's ZAMS will be much
more profound and severe with an A V star.  It's possible life might
develop, but it's hard to believe it would take hold before it was
snuffed out by the changing environment.

That being said, I don't see how your comment about life has any
connection with the press release you quoted.  The press release doesn't
mention anything about Earth-like planets, only that there might be
enough room inside the protoplanetary disk for terrestrial planets to be
present, should the model be correct.  Nothing about planets at
Earth-like insolations, nothing about Earth-like planets, nothing about
life.  There's a long way to go from the possibility of terrestrial
planets to life on Earth-like planets.  Note that even the presence of
the Neptune-sized planet is inferred, not directly observed!

Note that the scenario of a Neptune-like planet pushing out the
protoplanetary disk and forming a sort of Kuiper belt is similar to what
we think happened in our Solar System.

        http://www.space.com/scienceastronomy/mystery_monday_031201.html

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