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Hmm, thanks. I did a little more searching and reading about this with my new vocabulary (bending spacetime). It seems like photons also bend spacetime.

More info here. All of it contradictory :) http://www.physicsforums.com/showthread.php?t=287888

So I'm still wondering if it is proper to think of a star's gravitational field being caused not just by its matter, but also by all the photons it has pumped out over its lifetime.

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It doesn't make any sense to define a gravity field by photons. They're massless, so they don't attract anything, and most of the photons a star has produced over its lifetime are speeding away across the universe billions of light years away from it.

Only things with mass can attract other objects with the gravitational force. Photons aren't in that category.

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