'Free Planet'? 'Free Star'?

[Sunspace]

Woke up today with a question from a dream…

IS there any reason a star couldn’t be traveling independently through space, and not be part of a galactic system? Do we know of any such ‘free stars’?

Likewise, could there be a ‘free planet’ that is not part of a stellar system?

[Coriolanus]

Nothing can travel independantly through Cosmos. Gravitational attraction is everywhere. Your ‘Free Star’ would have to produce thrust to counteract the yolk of gravity.

[rsa]

There are certainly free stars. The Virgo cluster seems to have 1 trillion of them.

http://hubblesite.org/newscenter/archive/1997/02/text

NASA’s Hubble Space Telescope has found a long sought population of “stellar outcasts” — stars tossed out of their home galaxy into the dark emptiness of intergalactic space. This is the first time stars have been found more than 300,000 light-years (three Milky Way diameters) from the nearest big galaxy.

The isolated stars dwell in the Virgo cluster of galaxies, about 60 million light-years away. The results suggest this population of “lone stars” accounts for 10 percent of the Virgo cluster’s mass, or 1 trillion Sun-like stars adrift among the 2,500 galaxies in Virgo.

<snip>

Intergalactic stars have been predicted to exist as a result of galaxy interactions and mergers early in a galaxy cluster’s history. These close encounters should have ripped stars out of their home galaxies and tossed them into intergalactic space, where they drift free of the gravitational influence of any single galaxy.

I’m not too sure about free planets but I would guess that they are possible but probably not numerous.

[Squink]

Interstellar planets

Called “interstellar planets” because they would exist between the stars but no longer in orbit around an original parent star, they have never been directly observed or proved to even exist. But based on what scientists know about the way matter should fall together in forming a solar system, such Earth- like planets could definitely have been formed.

Over a period of several million years, one of two things happened to these planets: either they slammed into Jupiter and made it even bigger, or else they came so close to Jupiter that they were catapulted by gravity completely out of the solar system, never to return.

[Sunspace]

Cool! I should have more questions in dreams! Obviously my dreams are directly connected to the universe, while my waking life is obscured by such distractions as work and commuting.

[Chronos]

The biggest problem with free planets, scientifically speaking, is not that we think they don’t exist, but that it’s extremely difficult to detect them. You can, in principle, detect them when/if they momentarily pass in front of a background star and gravitationally focus the light from that star. Numerous objects have been detected in this way, but it’s not completely clear just what those objects are. Some of them are probably Jupiterlike objects.

[eburacum45]

Some discussion of freefloating planets here.
Anything smaller than 13 x Jupiter is not really a brown dwarf… Quite a few objects of this size have been seen in the Orion Nebula, if the planetary interpretation is correct.

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http://www.orionsarm.com/

[ZenBeam]

Squink’s link says

Called “interstellar planets” because they would exist between the stars but no longer in orbit around an original parent star, they have never been directly observed or proved to even exist.

There was a picture a while ago that was thought to be an interstellar planet. This was only a couple years ago, more recent than the article in the link. I had it as my screen background for a while, but I don’t think I have it anymore.