How to Put Together a Milky Way

For the ground-based telescopes they look just like any other stars, while the Hubble Space Telescope reveals that these distant objects are actually massive clouds of dust and gas, factories for some of the first stars ever to shine light in the universe. These primitive galaxies, dating more than 12 billion years into the past, are relatively small compared to most of the fully developed galaxies and present an active process of stellar formation.

They were discovered by astronomers from Rutgers and Penn State University, with the help of the Hubble Space Telescope, and the scientists argue that they represent a crucial stage in the spiral galaxy formation process, as primitive galaxies pull together, with the help of the gravitational fields, in groups of ten or more to finally form a single spiral galaxy.

Researchers found that these objects coming in multiple shapes and sizes represent a fertile ground for star formation, and are actively emitting ultraviolet light known as Lyman alpha. The Lyman alpha radiation emission usually occurs during the ionization process of the molecular hydrogen cloud, which is stripped of its electrons through friction, and determines a light emission in the ultraviolet spectrum.

The study is part of a project founded by the National Science Foundation, called MUSYC, which plans to study galaxies in the early stages of universe evolution, over a period of five years, in order to determine the exact formation process of spiral galaxies, similar to the Milky Way. By studying certain characteristics of these primitive galaxies, such as luminosity, density, Lyman alpha, and others, astronomers were able to conclude that indeed these are the ancestors of spiral galaxies.

It is natural to believe that galaxies could have not evolved from a single massive cloud of dust, but rather from a series of multiple collisions between several primitive galaxies that contributed to the increase in the mass of the single spiral galaxy, taking into consideration the fact the galactic collisions are common in the universe even today.

Approximations of their size put them at only about 10 to 5 percent of the mass of a fully developed galaxy, and may have a number of stars as low as one fortieth of that observed in our galaxy. No wonder they are distinguishable only from space, as ground-based observations have an imaging resolution ten times lower than telescopes located in Earth's orbit.

Most of these objects are situated in remote regions of the space, and some might look like they were only 2 billion years after the birth of the universe, currently receding into deep space at impressive speeds, as the universe inflates exponentially.