Exo objects Q&A

[just this man you know]

I had a couple of questions abouth extra solar objects:
1; How come there hasn't been a discovery of a exo trojan planet (follow up is it expected that we will find them some day)?
2; What would be the name of a (exo): moon; double planet and trojan?

[ugordan]

Objects in L4 and L5 Lagrange points by definition must be small bodies (relative to parent bodies) in order to have a stable configuration - typically those would be asteroids. It's hence extremely unlikely we'll be able to detect trojans for exoplanets already discovered, given how we're struggling to find even Earth-mass planets with our current detection sensitivity.

We don't even have a good census of Uranus and Neptune trojans in our solar system and still they are vastly easier to detect than stuff many lightyears away.

[just this man you know]

thank you for answering. But I was under the impression that a Trojan would be relativly stable so long as it stayed under 10% of the parents body.

(meaning a Jupiter sized planet could have a trojan the size of Neptune)

Am I incorrect? (in saying that trojans could be massive gas giants)

My sources are http://en.wikipedia.org/wiki/Moon_Formation

(edit grammer error)

[jebbo]

I had a couple of questions about extra solar objects:
1; How come there hasn't been a discovery of a exo trojan planet (follow up is it expected that we will find them some day)?

As said above, L4/L5 objects must be much smaller than the parent body.  This means they would be even harder to find.  Also, my guess is configurations with very large trojans would be very rare . . .

2; What would be the name of a (exo): moon; double planet and trojan?

There is no IAU naming convention for exomoons yet (as we haven't found any yet, but people are looking), but it is a fair bet it will be something like <star name><planet letter><moon number>, where planet name is a lowercase letter (from "b") and moon number is, well, a number:-).

For double planets and trojans, I imagine each would be named individually.  To describe architectures, I guess an extension of the current one for stars might work, so a double star with a double planet might be expressed something like "(AB)(bc)" . . .