New recipe for dwarf galaxies

There is more than one path forming a dwarf galaxy, and NASA's Galaxy Evolution Explorer has found the new formula. For the first time, NASA spacecraft recognized dwarf galaxies formed from something that was nothing special but the original remaining gas from the original universe. Dwarf galaxies are a fairly small set of stars that often orbit around other larger galaxies like our Milky Way galaxy.

This finding surprised astronomers by most galaxies formed in connection with a mysterious material called dark matter or from a metal-containing gas. The young galaxies observed by the Galaxy Evolution Explorer formed from gas do not contain both dark matter and metal. Although it has not been observed before, this new dwarf galaxy may be more common in the universe sooner and farther than where the primitive gas is.

Astronomers also observed that unexpected galaxies formed inside the Leo Belt - a cloud of large hydrogen and helium forming a rugged-looking pathway surrounding two large galaxies in the constellation. Why Leo. This cloud is thought to be a primitive object - ancient physical remnants maintained quite intact since the universe existed in the first days. Discovered 25 years ago by radio waves, the Leo belt cannot be seen with ordinary light.

"This curious object has been studied for decades by the world's leading telescopes that operate on optical and radio wavelengths," said David Thilker of Johns Hopkins University, Baltimore. 'But when we look at the belt through the Galaxy Evolution Explorer very sensitive to ultraviolet rays, we can see evidence that has turned away the formation of big stars recently. This is really beyond our expectations. We are witnessing galaxies forming from a cloud of primitive gas'.

In a recent study, Thilker and colleagues found the ultraviolet traces of young stars emanating from several clumps of gas within the Leo Belt. He said: 'We think these young, complex stars are actually dwarf galaxies, though, according to astronomers studying radio waves, the gases that make up these galaxies are not available. dark matter. Almost all of the other galaxies we know are dominated by dark matter, which acts as a seed for a collection of glowing components including stars, gas and dust. What we see happening in the Leo Belt is a new way of forming dwarf galaxies from the rest of the galaxy's long-standing material. '

The unique ultraviolet image brought by NASA's Galaxy Evolution Explorer, showed for the first time dwarf galaxies formed from the remaining primitive gas from the original universe. (Photo: NASA / JPL-Caltech / DSS)

The universe in which we live has two large galaxies - the Milky Way and the Andromeda galaxy - each of which contains hundreds of billions of stars. Besides these two tycoons, there is a Triangulum galaxy with several tens of billions of stars, more than the number of stars of more than 40 dwarf galaxies. Each dwarf galaxy contains only a few billion stars. Dark matter is not observed but can be identified by its gravitational force. It is a major component of both dwarf galaxies and giant galaxies, except for one exception, the tidal dwarf galaxy.

Tidal dwarf galaxies coalesce from gases recycled from other galaxies, which are also separate from most dark matter associated with them at an early stage. They are formed when colliding galaxies and their gravity blocks interact with each other. In this violent collision, galactic material streams will be pulled out of the parent galaxy and the halos of dark matter surrounding them.

Because they lack dark matter, new galaxies observed in the Leo Belt resemble tidal dwarf galaxies but they are fundamentally different. Gas material creates tidal dwarf galaxies circled throughout the galaxy. It is enriched with metal - or heavier elements than helium. Metal is produced when stars form. Thilker said: 'The Leo Ring dwarf galaxies are made up of mostly non-metallic materials. This finding allows us to study how star formation in gas has never been enriched with metal. '

Large primitive gas clouds similar to the Leo Belt may be more common in the early universe, so there may still be many dark, dwarf, dwarf galaxies awaiting discovery.

The results of the new study of star formation in the Leo Belt are published in the February 2009 issue of Nature.

Caltech directed the Galaxy Evolution Explorer project and was responsible for operating science and analyzing information. NASA's Jet Propulsion Laboratory in Pasadena, California manages the project while building research equipment. The project was developed according to NASA's Explorers Program managed by Goddard Space Flight Center. South Korea and France are companions in the project.