At www.scientificamerican.com/article/exocomets-around-beta-pictoris/ … again, this is a piece of French observation and research beginning way back in 1986. The astronomer, Anne-Marie Legrange, and colleagues, witness something peculiar. Beta Pictoris seemed to be in the process of assembling its own planetary system. After months of trying to work out what was going on and what exactly they might have seen they came out with an odd explanation – for the time. They offered up what seemed to be an unlikely explanation. They said they were seeing starlight shining through giant plumes of gas pouring off icy objects plunging through the disc of gas towards the star. That is, they were looking at comets.
Now, in 2014, Lagrange and the other French astronomers have an article in Nature (Oct 23rd) and they have gone so far to compile a catalogue of exocomets, and so far there are 500 to date. One problem notes – where is the water in the comets – which is back to the old theory of icy comets. They have found no evidence of water at Beta Pistoris. Are the comets water rich?