Mapping the Milky Way: Radio telescopes give clues to structure, history

Jan 09, 2013
Red areas mark locations of a string of newly-discovered HII regions stretching across a portion of the MIlky Way. CREDIT: HRDS Survey Team, NRAO/AUI/NSF (radio); Axel Mellinger (optical)

(Phys.org)—Astronomers have discovered hundreds of previously-unknown sites of massive star formation in the Milky Way, including the most distant such objects yet found in our home Galaxy. Ongoing studies of these objects promise to give crucial clues about the structure and history of the Milky Way.

The scientists found regions where massive young stars or clusters of such stars are forming. These regions, which astronomers call HII (H-two) regions, serve as markers of the Galaxy's structure, including its and central bar.

"We're vastly improving the census of our Galaxy, and that's a key to understanding both its current nature and its past history, including the history of possible mergers with other galaxies," said Thomas Bania, of Boston University. Bania and his colleagues presented their work to the 's meeting in Long Beach, California.

The astronomers are using the National Science Foundation's (NSF) Green Bank Telescope (GBT) in West Virginia and Arecibo Telescope in Puerto Rico, and data from NASA's Spitzer and WISE (Widefield Explorer) satellites. They plan to expand the effort to include Australian radio telescopes.

The effort began with a survey of the Milky Way using the GBT. The scientists looked for HII regions by seeking faint emission of at that are unobscured by the dust in the Galaxy's disk. By detecting these emissions, dubbed radio recombination lines, or RRLs, the GBT survey more than doubled the number of known HII regions in the Milky Way. They continued that work using the Arecibo Telescope, finding additional objects, including the largest HII region yet found, nearly 300 light-years across.

This video is not supported by your browser at this time.
Video of HII region locations strung across a portion of the Milky Way. Credit: Brian Kent, Bill Saxton, John Stoke, NRAO/AUI/NSF

Data from previous surveys with radio and , including Spitzer and WISE, helped to guide the new search. Later work analyzed similar emissions of helium and .

"The great sensitivity of the GBT and the Arecibo telescope, along with advanced electronics, made our new surveys possible," said Dana Balser, of the National Radio Astronomy Observatory (NRAO).

"Data from WISE shows about 2,000 new HII-region candidates that we are studying with the GBT to confirm," said Loren Anderson, of West Virginia University.

The work so far has helped refine astronomers' understanding of the Galaxy's structure. They found concentrations of in a poorly-understood spiral arm and at the end of the Galaxy's central bar.

"HII regions are the best tracers of the Milky Way's spiral structure, and this work is an excellent way to improve the map of our Galaxy," Bania said.

Another major focus of the surveys is to study chemical variations in different regions of the Galaxy. Variations in the abundance of elements heavier than hydrogen can trace the history of star formation, and also indicate regions possibly containing material incorporated into the Galaxy through mergers with other galaxies throughout its history.

"We've already been surprised to learn that the thin, tenuous gas between the stars is not as well-mixed as we thought," Balser said. "Finding areas that are chemically different from their surroundings can point to where gas clouds or smaller galaxies may have fallen into the Milky Way," he added.

"Just as geologists traverse the landscape, mapping different rock types to reconstruct the Earth's history, we're working to improve the map of our Galaxy to advance our understanding of its structure and its history," Bania said. "The are our tools for making these new and better maps."

Explore further: Spectacular supernova's mysteries revealed

Related Stories

A new, distant arm of the Milky Way galaxy

Jun 13, 2011

(PhysOrg.com) -- Our Milky Way galaxy, like other spiral galaxies, has a disk with sweeping arms of stars, gas, and dust that curve around the galaxy like the arms of a huge pinwheel.

Neighbor galaxies may have brushed closely: research

Jun 11, 2012

(Phys.org) -- Two of our Milky Way's neighbor galaxies may have had a close encounter billions of years ago, recent studies with the National Science Foundation's Green Bank Telescope (GBT) indicate. The new ...

NGC 3344: Hubble sees galaxy in a spin

Oct 22, 2012

(Phys.org)—NGC 3344 is a glorious spiral galaxy around half the size of the Milky Way, which lies 25 million light-years distant. We are fortunate enough to see NGC 3344 face-on, allowing us to study its ...

New Hydrogen Clouds in the M81 Group of Galaxies

Jan 10, 2008

A composite radio-optical image shows five new clouds of hydrogen gas discovered using the National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT). The spiral galaxy M81 and its satellite, ...

Recommended for you

Spectacular supernova's mysteries revealed

16 hours ago

(Phys.org) —New research by a team of UK and European-based astronomers is helping to solve the mystery of what caused a spectacular supernova in a galaxy 11 million light years away, seen earlier this ...

Supernova seen in two lights

18 hours ago

(Phys.org) —The destructive results of a mighty supernova explosion reveal themselves in a delicate blend of infrared and X-ray light, as seen in this image from NASA's Spitzer Space Telescope and Chandra ...

Toothpaste fluorine formed in stars

Aug 21, 2014

The fluorine that is found in products such as toothpaste was likely formed billions of years ago in now dead stars of the same type as our sun. This has been shown by astronomers at Lund University in Sweden, ...

Swirling electrons in the whirlpool galaxy

Aug 20, 2014

The whirlpool galaxy Messier 51 (M51) is seen from a distance of approximately 30 million light years. This galaxy appears almost face-on and displays a beautiful system of spiral arms.

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

gwrede
5 / 5 (2) Jan 10, 2013
The video in this article is an excellent example of the current trend "towards multimedia". The content of the video is nothing more than what already is visible in the picture at the top of the article.

The only reason for the video is that "This Article Includes Video". Merely conning a few extra readers, costs wasted time, wasted hard drive, wasted bandwidth, and lessens respect for the writers and their institution.