Evidence for ET?

[Jehanne]

That would be totally different. The sort of “planet” that are believed to form independently of any Star are really miniature star in their own right in terms of composition, just too small to actual ignite or sustain thermal nuclear fussion like normal star.  They are still enormous objects, likely on average much more massive than Jupiter.

I am to understand that matter doesn't conglomerate in progressively larger chunks? That the smallest such accumulated mass would "likely on average much more massive than Jupiter"?

Jupiter emits twice as much EM as it absorbs from the Sun. If there were large numbers of Jupiter-sized objects in interstellar spaces (MACHOS), they would have been detected via gravitational lensing, occultations, etc. Such objects have not been found in large numbers. Ergo, most large objects form around stars.