Just a few days ago, we could see Tunç Tezel and Stéphane Guisard's great APOD, A Tale of Two Hemispheres.
Here we could see the faint glow of the zodiacal light. Where does the zodiacal light come from? Well, look at Vesta. Over the billions of years that Vesta has existed, it has suffered many collisions, as we can see from its heavily cratered surface. Little bits of Vesta have been chipped off, over and over. Where do the chips go? They stay in orbit around the Sun. Billions and trillions of tiny bits chipped off Vesta and other asteroids and moons follow their own orbits around the Sun. Together, these chips create a faint glow as they reflect the light of the Sun.
Of course, our solar system was full of tiny dust grains even before the planets had come into being. Young star Vega, about 350 million years old (see
here) and less than a tenth of the age of the Sun, hasn't given its own asteroids much time to collide or even form. Even so Vega is surrounded by a lot of dust. Therefore many of those dust grains must be primordial - or rather, they must have been there in the gas cloud that Vega formed from. And that is no surprise.
Photo: Andrey Oreshko
Take a look at this image of a star formation region in Corona Australis. Look at that long dark "tail" stretching from the bright bluish star star formation region down towards the lower left. Why is that tail so dark? It is because it is made of gas mixed with gazillions of tiny dust grains. Where do these dust grains come from? They are primarily "cooked up" by bloated red giant stars which are about to turn shed their atmospheres and gradually turn themselves into white dwarfs. As the red giant blows its gassy atmosphere into space, that gas is loaded with dust grains.
Credits:Laurence Sabin, Nick Wright and the IPHAS collaboration.
This is an image of an old planetary nebula. You can see how gas has been thrown out from the central star (which is not obviously visible here) in an irregular pattern. The gas is loaded with dust grains created by processes inside the dying star. But what if this star had planets and cratered asteroids like Vesta? Then the "chips of Vesta" will be mixed with the dust grains created by the dying star.
And if this gas is ever going to be sufficiently compressed to lead to more star formation, then dust grains from a dead sun and from previous asteroids may actually be recycled into the creation of new asteroids, moons and planets.
Ann
