When you picture a galaxy in your mind's eye, it's often a spiral with magnificent structure - long, swirling, milky-white arms of stars and gas.

Lowell Observatory astronomer Deidre Hunter has spent most the last 17 years methodically studying unfamiliar galaxies that you might not expect - small, diffuse galaxies: the dwarf irregulars - to learn all she can about star formation and what it can tell her and her colleagues about the birth of the first stars after the Big Bang.
In an NSF-funded project called LITTLE THINGS - for Local Irregulars That Trace Luminosity Extremes (LITTLE) and The HI Nearby Galaxy Survey (THINGS) - Hunter's team is mapping the gasses in these diffuse, enigmatic galaxies to discern the many processes of star formation.
“Star formation in dwarfs today is similar to star formation right after the Big Bang,” Hunter said.
“Stars form out of clouds of gas. Our quest is to figure out what the molecular clouds in these irregular galaxies are, and the processes that form stars.”
The LITTLE THINGS team is closely studying 41 dwarf-irregular galaxies through the lens of numerous data sets. And the galaxies are small, relatively speaking. One, DDO 75, has 1/3500 the mass of the Milky Way. Another, Leo T, was recently discovered in the Local Group of galaxies, the closest neighbors to our own Milky Way.
“Leo T is comparable in brightness to a large star cluster that contains several million stars; in contrast, the Milky Way contains about 300 billion stars,” Hunter said.
Some of the galaxies in our sample area are not much brighter than a large star cluster.”
The process of star formation is very inefficient. Some 50 to 90 percent of the gas present in star-forming molecular clouds, including the gas in the tiny irregular galaxies, remains after stars form.
“This produces the nebulae,” Hunter said. “They are like signposts that say, 'massive stars are found here.'
In a general sense it's like weather clouds on Earth. You need these molecular clouds that form out of the ubiquitous atomic hydrogen gas to precipitate stars.”
Hunter added that there are probably multiple processes going on, which adds to the complexity and time-intensive nature of the LITTLE THINGS study.
In the dwarf galaxies, there's star-induced star formation. There's also turbulence.
“It's not just density, but also the motions of the gas,” Hunter says.
The data sets Hunter and her colleagues are using include optical-wavelength data Hunter already collected and analyzed using research telescopes at Lowell's Anderson Mesa facility near Flagstaff.
But some of the new, key data is in radio wavelengths, and they come from NSF's Very Large Array (VLA) located west of Socorro, New Mexico.
In May of 2007, Hunter was invited to give a talk at the VLA. Afterwards, a scientist with the facility suggested she put in a large proposal, that is, a proposal for a large amount of VLA telescope time.
(Source: LiveScience.com)