The Nebular Theory: Proplyds

What Evidence do we have of a Nebular Theory-type development?

We have observed discs of gas and dust around other stars. We can also see evidence of stars and planets forming in clouds of gas and dust; young planet systems in the making are called Proplyds. Other disk-forming evidence found throughout the Universe includes spiral galaxies. Computer modeling is used to model formation of stellar systems, like our solar system.

A Hubble Space Telescope view of a small portion of the Orion Nebula, captured by the Wide Field and Planetary Camera 2, reveals five young stars. Four of the stars are surrounded by gas and dust trapped as the stars formed, but were left in orbit about the star. These are possibly protoplanetary disks, or proplyds, that might evolve on to agglomerate planets. The proplyds which are closest to the hottest stars of the parent star cluster are seen as bright objects, while the object farthest from the hottest stars is seen as a dark object. The field of view is only 0.14 light-years across.
NASA Hubble Space TelescopePublic Domain | Image courtesy of NASA / ESA.

This Hubble Space Telescope image shows a flattened disk of dust and debris which surrounds the star Beta Pictoris. Planets and other bodies, like moons, asteroids, and comets, will form out of this disk of dust and debris.
NASA Hubble Space TelescopePublic Domain | Image courtesy of NASA / ESA.

The top view, taken with NASA's Hubble Space Telescope, shows light reflected off dust in a debris disk around the young star AU Microscopii. The bottom frame labels features in this image, while the white lines on the disk indicate the light polarization direction. The image shows the flattened disk, appearing like Saturn's rings, but seen almost exactly edge-on. Normally, starlight would be so bright that the debris disk could not be seen. But astronomers used the coronagraph on Hubble's Advanced Camera for Surveys, which blocked out most of the starlight. The black circle in the center of the image is the coronagraph's occulting disk. The disk in this image extends to about 8 billion miles from the star, or three times farther than Neptune is from the Sun. In other observations, the disk has been traced to at least 11 billion miles.
NASA Hubble Space TelescopePublic Domain | Image courtesy of NASA / ESA.