Pregnant Young Sun

A story in today’s Wall Street Journal (link) reports on the discovery of what may be a new planet forming in the gaseous disk surrounding a young sun quite near us in the Milky May. Near is 335 light years from here. The sun’s name is HD100546. The “planet” is an asymmetry in the gas disk; the point where the asymmetry is observed also emits strong radiation. I note this here for future reference. Of the two theories of planet formation, one has particles, large and small, colliding and cohering as they circle a sun and then, slowly, aggregating into planets. This would suggests that the asteroid belt in our own system has simply failed to “get with the program.” The other model is that planet formation is a spontaneous process that takes place in the wake of a star's own formation—the planets forming, much as the one reported today, from the same raw materials that gave birth to the sun and soon after—thus while a good deal of dynamism is moving that disk of gases and dust. I’ve long favored this second view—and prefer to imagine that the asteroid belt is the record of some planet that got shattered in some collision. The discoverer here is Sascha Quanz, of the ETH University in Switzerland, working with his team at one of two observatories operated by the European Southern Observatory in the Atacama Desert of Chile. The one used was not reported but was probably Paranal, the location of the Very Large Telescope.