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New catalog of visible Milky Way charts 219 million stars

Astronomers spent 10 years charting stars brighter than 20th magnitude – that’s about 1 million times fainter than can be seen with the human eye.

View larger. | This new map shows the density of objects within our Milky Way galaxy. It's a small section of a larger map, but it shows in exquisite detail the complex patterns of obscuration in the galaxy, due to interstellar dust.  Image via Hywel Farnhill, University of Hertfordshire.

View larger. | This new map shows the density of objects within our Milky Way galaxy. It’s a small section of a larger map, but it shows in exquisite detail the complex patterns of obscuration in the galaxy, due to interstellar dust. Image via Hywel Farnhill, University of Hertfordshire.

Astronomers at the University of Hertfordshire spent 10 years using a telescope in the Canary Islands to chart no fewer than 219 million stars in our galaxy. Their new catalog is the largest of its kind ever produced. It shows the visible part of the northern part of our home galaxy, the Milky Way. Geert Barentsen led the research, which was published on September 15, 2014 in the journal Monthly Notices of the Royal Astronomical Society.

The image included here, a cut-out from a stellar density map mined directly from the released catalog, illustrates the new view obtained. It’s beautiful. Plus astronomers say that maps like these also serve as useful tests of new-generation models for the Milky Way. We need those models because, after all, we can’t get outside the Milky Way to see what it actually looks like.

These astronomers say their work is an example of modern astronomy’s exploitation of big data. That is, they didn’t just pinpoint these stars, and chart their locations, as astronomers a century ago would have done. Instead, they summarized in 99 different attributes for each of the 219 million detected objects.

From dark sky sites on Earth, on September evenings, our Milky Way galaxy appears to the unaided eye as a starlit band stretching across the sky. This band of light is the edgewise view into our own galaxy, a system stretching across 100,000 light-years, whose disk contains most of the stars in our galaxy, including our sun, and the densest concentrations of dust and gas.

Throughout history, people have peered at this starlit band, struggled to distinguish individual objects within in, and tried to make sense of it.

The new catalog gives scientists a detailed map of the disk of our galaxy that shows how the density of stars varies within the disk. They say it will give all of us new and vivid insight into the structure of the vast system of stars, gas and dust in which we live.

Read more about the new Milky Way catalog from the Royal Astronomical Society

Deborah Byrd

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