07Dec2012

The North Star Debate: Distance To Polaris Re-Defined.

Throughout history, mankind has looked to the North Star – Polaris – as a steady companion in the night sky. However, despite all we know about this star, there’s a mystery.

What has never been clearly understood is its distance from Earth, a problem now resolved by astronomer David Turner and his colleagues. As we know, Polaris is one of the nearest Cepheid variables – a pulsating star whose regular “heartbeats” help define distance through the Hubble Constant.

Finding the north star using ursa major, the big dipper.

Having a well-defined distance for this star will not only help refine Edwin Hubble’s work, but will also help constrain parameters for another cosmic mystery – dark energy.

By having a clear-cut distance to Polaris, astronomers would be able to solidify their calibrations of Cepheid relations and establish a more accurate cosmic distance scale.

Why don’t we have accurate measurements to the North Star? The Polaris system, which consists of a primary star and two companions, was defined by the Hipparcos satellite as 434 light years, yet some studies placed it closer to the Sun. Now a study published in the Astrophysical Journal Letters done by Dr. Turner show it may be much closer at 323 light years.

This new distance is based on high-resolution spectral analysis. Ironically, this discrepancy between figures translates to a 30% relative uncertainty… which means that astronomers are more able to accurately calculate the distance to some galaxies orbiting the Milky Way with more accuracy, despite being about 500 times further away!

“Polaris presents certain anomalies that have so far defied a straightforward interpretation,” noted Turner. He went on to add, “Our high-resolution spectroscopic observations of Polaris may signal the beginning of a new era in understanding the star.”

Original Story Source: CASCA Press Release. Submitted by Tammy Plotner for “Dave Reneke’s World of Space and Astronomy News.

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