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Recent results from Institute for Astronomy at the University of Hawaii at Manoa claim that there is a Jupiter-sized gas giant planet that is independent of a star about 80 light-years from Earth.

The press release refers to this planet as "free-floating" but I assume that it must be in some kind of predictable orbital path.

What is the orbital path of this newly discovered planet?

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An interesting question could be as to what are the chances that this rogue planet be caught in the gravitational field of a star in its path. –  user8 Oct 11 '13 at 7:46

3 Answers 3

up vote 10 down vote accepted

There is no "orbital path" detected, that's why it is a "free-floating planet". There is no radial velocity mesured, but the informations given by its kinematic location show that it belongs to the beta Pictoris group, that is a stellar group.

For more dirty details, have a look at the submitted paper on PSO J318.5-22: http://arxiv.org/abs/1310.0457

Comment: Apart from that (the following reflects my personal opinion) the term "free-floating planet" is ill-chosen; it is clearly a very low-mass object, but since it is not orbiting around another larger object, it seems to me that the term "planet" is not pertinent. I think that it should be consider more than a "very low-mass brown-dwarf". The problem arises from IAU definition of a brown-dwarf and a exoplanet, that is probably not well-fitted for this kind of objects (and that is not really physical). You will notice, by the way, that this object is moving in a stellar group, which kind of reinforce my point.

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It will probably be in an orbital path around the centre of the galaxy... –  Dieudonné Jan 30 at 19:02

We don't know the full story about the trajectory of the rogue planet PSO J318.5-22, more observations are needed.

Even though (according to the article you linked in the question) the planet is not orbiting a star, it is moving with a stellar group. The The β Pictoris Moving Group (Zuckerman et al. 2001), which is

17 star systems, each with one or more characteristics indicative of extreme youth, that are moving through space together with β Pic.

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This rogue planet orbits the center of the galaxy Milk Way, (or rather, the center of mass of the system PSO J318 - rest of MW, wherever it is localised) just like the Sun and the other stars.

But I think the details of this orbit, that is eccentricity, period, inclination, etc are not well known. If PSO J318.5-22 be confirmed as a Beta Pictoris association member, I guess it will have an orbit similar to the other members of this association/moving group.

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