24 October 2012

Vista Captures 9 Gigapixel Image of the Center Of The Milky Way Galaxy

The Visible and Infrared Survey Telescope for Astronomy (VISTA) captured a nine gigapixel image of the center of the Milky Way Galaxy. Astronomers have used this image to catalog more than 84 million stars within it.

Because of the high resolution of the image (108,200 by 81,500 pixel), if printed in regular resolution as that of a book, the image would be 9 meters wide by 7 meters tall. This is one of the biggest astronomical images ever produced.

VISTA gigapixel mosaic of the central parts of the Milky Way

“By observing in detail the myriads of stars surrounding the centre of the Milky Way we can learn a lot more about the formation and evolution of not only our galaxy, but also spiral galaxies in general,” explains Roberto Saito (Pontificia Universidad Católica de Chile, Universidad de Valparaíso and The Milky Way Millennium Nucleus, Chile), lead author of the study.

This central area of the Milky Way, called the Bulge, has a large concentration of very old stars but is obscured by dust. Dust in space usually called space clouds are massive cosmic structures. The largest, called giant molecular clouds, reach diameters of 100 light-years (9.5×1014 kilometers) and densities of around 100 particles per cubic centimeter (cm3).

To truly appreciate the image, it is best to view the zoomable image here: Vista Gigapixel Zoomable Image

To get around the obstruction, they used infrared light. With this wavelength, astronomers were able to see the stars surrounding the center of the Milky Way galaxy without the obstructing dust clouds.

They then prepared a color-magnitude diagram for each star in the area, all 84 million stars. A color-magnitude diagram is graph that plots the brightness of the object against its color. Using different image filters, they also measured the color of the objects. With the color-magnitude diagram, astronomers cataloged the properties of the stars such as its temperature, mass, and age.

This is the first time that the entire Bulge has been subject to this image and data processing technique. This study contains more than ten times more stars than any previous studies.

Video: Center of the Milky Way As Imaged By Vista

“Each star occupies a particular spot in this diagram at any moment during its lifetime. Where it falls depends on how bright it is and how hot it is. Since the new data gives us a snapshot of all the stars in one go, we can now make a census of all the stars in this part of the Milky Way,” explains Dante Minniti.

The new colour–magnitude diagram of the bulge contains a treasure trove of information about the structure and content of the Milky Way. One interesting result revealed in the new data is the large number of faint red dwarf stars. These are prime candidates around which to search for small exoplanets using the transit method.

“One of the other great things about the VVV survey is that it’s one of the ESO VISTA public surveys. This means that we’re making all the data publicly available through the ESO data archive, so we expect many other exciting results to come out of this great resource," concludes Roberto Saito.


84 Million Stars and Counting— VISTA creates largest ever catalog of center of our galaxy
Pontificia Universidad Católica de Chile
European Southern Observatory (ESO)
Visible and Infrared Survey Telescope for Astronomy (VISTA)
Visible and Infrared Survey Telescope for Astronomy - ESO site
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