SUMMARY: Astronomers from the Harvard-Smithsonian Center for Astrophysics have discovered a massive planetary zone forming around the star system TW Hydrae. By probing this vast disk of material with the National Science Foundation's Very Large Array in the radio spectrum, they have detected that rocks and pebbles extend outward for at least 1.6 billion km (1 billion miles). These chunks of rock will slowly clump together, eventually forming larger and larger planets over millions of years. This is the first time astronomers have seen this intermediate stage, after pure dust, but before planets.

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Nice.

It would be interesting to see a time-line for the formation of stars and planets with markers showing which stars we have observed at which stage of this time-line. I am curious as to how the initial mass function changes the pace and nature of planet formation. This might need to be a correction factor for each star on the time-line.

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Forming opinions as we speak

The observational data keeps getting better and better. I will look around to see if somone has tried to create such a catalogue. Now would be a good time to begin compiling one. This appears to be a sun-like star with a sun-like location for its giant planet. The fact that there is already a gas giant favors the model that gas giants form like their stars and not from accretion IMHO. Watching this system over millions of years would answer that question, though. It would also be interesting to watch for a few million years to see if the gas giant spirals iin closer to the parent star due to interactions with the existing disc.

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Quid hoc ad aeternitatum
The conversion of complex and abstract ideas into simple and concrete ones is the essential function of teacher of a body of knowledge.

As promised, I have been busy searching the web for catalogs of planetary discs. Not much luck so far, but I did find a nice article that describes a catalog of high mass stars with suspected planetary systems. http://www.spaceref.com/news/viewpr.html?pid=7122
The above is a link to an interesting aticle that should help you track down a catalog made by Michael Barlow and Vincent Mannings in 1998 of this class of systems.
http://www.blackwell-synergy.com/links/doi...bs/?cookieSet=1
The above link is to a site with some journal references to that particular catalog.
http://www.jb.man.ac.uk/~abstract/abstract...html#abstract49

The above is a link to an abstract about a survey of T-Tauri stars for discs


If you are interested in planets in general and not just discs, there are a few extrasolar planets catalogs out there.
http://vo.obspm.fr/exoplanetes/encyclo/catalog.php
This is a link to a more recent one. Tracking down which are young systems with discs will be your responsibility, however.
I will post if I find a more comprehensive list of stars with protoplanetary discs. I agree that one is needed if there isn't one yet.

__________________
Quid hoc ad aeternitatum
The conversion of complex and abstract ideas into simple and concrete ones is the essential function of teacher of a body of knowledge.

I just found a good collection of articles with references to stars with protoplanetary discs. So far it is the closest thing to a catalog that I can find.
http://astron.berkeley.edu/~kalas/disksite...es/library.html

__________________
Quid hoc ad aeternitatum
The conversion of complex and abstract ideas into simple and concrete ones is the essential function of teacher of a body of knowledge.

Thats a cool discovery i wonder if the system will every support life.