Friday, May 13, 2016

Insterstellar dust affects astronomical observations

Could this affect the appearance that the universe is expanding at an accelerating rate?

Public Release: 9-Mar-2016
All we are is dust in the interstellar wind
NSF-funded researcher creates a map of dust in the Milky Way galaxy
National Science Foundation


Although dust only makes up about 1 percent of the interstellar medium (the stuff between the stars), it can have big effects on astronomical observations. Dust has a bad reputation because it gets in the way by absorbing and scattering the visible light from objects such as far-off galaxies and stars, making them difficult or impossible to observe with optical telescopes.

The scattering effect dust has is known as "reddening" -- dust scatters the blue light coming from an object, making it appear redder. This occurs because dust has a greater effect on light with short wavelengths, such as blue. A similar effect is what causes sunsets to appear red.

Astronomers can tell a lot about a star simply by its color, so this reddening effect can trick us into thinking a star is cooler and dimmer than it actually is. However, thanks to NSF-funded astronomers like Doug Finkbeiner of the Harvard-Smithsonian Center for Astrophysics, we can now correct for dust reddening and recover a star's intrinsic color.


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