Astronomers clash over the distance to the famed North Star

November 30, 2012, Canadian Astronomical Society

Credit: Canadian Astronomical Society
(Phys.org)—The North Star (Polaris) has played an important role in human history, yet knowledge of its fundamental parameters is unsatisfactory. That problem is attributable in large part to uncertainties tied to the star's distance, which have now been resolved in a paper by David Turner and colleagues.

Polaris is the nearest designated as a Cepheid variable. Solid knowledge of the distance to Polaris will facilitate efforts to determine the and constrain parameters for the mysterious dark energy. A reliable distance to Polaris would enable further calibration of the famed Cepheid relations, which lie at the heart of establishing the cosmic distance scale.

The ambiguity concerning the distance to Polaris, or rather the stars that constitute the Polaris system (there exist at least two companions), stems from the fact that the Hipparcos satellite measured its distance to be 133 pc (434 light-years), whereas some other studies placed it closer to the Sun. Turner's paper in the advocates a distance of 99 pc (323 light-years).

The new distance established for Polaris by David Turner and collaborators relies on a high-resolution spectral analysis. The discrepancy between the various distance estimates for Polaris translates into a 30% relative uncertainty, which ironically implies that astronomers know the distances to certain galaxies orbiting the Milky Way (i.e., the ) to better relative accuracy, despite their being some 500 times more distant than Polaris.

"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."

Explore further: The Polaris Cluster

More information: A preprint of the article, which will appear in the Astrophysical Journal Letters, is available here: arxiv.org/abs/1211.6103

Related Stories

The Polaris Cluster

May 28, 2010

(PhysOrg.com) -- A Cepheid star is one whose mass and age results in physical conditions that generate periodic oscillations in its photosphere. A Cepheid thus varies regularly in brightness, with a period proportional to ...

There's More to the North Star Than Meets the Eye

January 9, 2006

We tend to think of the North Star, Polaris, as a steady, solitary point of light that guided sailors in ages past. But there is more to the North Star than meets the eye - two faint stellar companions. The North Star is ...

Cepheids and their 'cocoons'

February 28, 2006

Using ESO's Very Large Telescope Interferometer (VLTI) at Cerro Paranal, Chile, and the CHARA Interferometer at Mount Wilson, California, a team of French and North American astronomers has discovered envelopes around three ...

The little Cepheid that stopped

January 14, 2011

When Hubble first discovered a Cepheid variable in the galaxy M31, the universe grew. Previously, many astronomers had held that the fuzzy “spiral nebulae” were small patches of gas and dust within our own galaxy, ...

Moving Closer to the Grand Spiral

August 1, 2005

An international team of astronomers from Chile, Europe and North America is announcing the most accurate distance yet measured to a galaxy beyond our Milky Way's close neighbours. The distance was determined using the brightness ...

Recommended for you

Exploding stars make key ingredient in sand, glass

November 19, 2018

We are all, quite literally, made of star dust. Many of the chemicals that compose our planet and our bodies were formed directly by stars. Now, a new study using observations by NASA's Spitzer Space Telescope reports for ...

Gravitationally lensed quasars

November 19, 2018

The path of light is bent by mass, an effect predicted by Einstein's theory of gravity, and when a massive galaxy or cluster lies along our line-of-sight to a more distant galaxy its matter will act as a lens to image the ...

A solar sibling identical to the sun

November 19, 2018

An international team led by Instituto de Astrofísica e Ciências do Espaço (IA) researcher Vardan Adibekyan used a novel method to detect solar siblings. The article was published in the journal Astronomy & Astrophysics.

Astronomers discover giant relic of disrupted Tadpole galaxy

November 19, 2018

A team of astronomers from Israel, the U.S. and Russia have identified a disrupted galaxy resembling a giant tadpole, complete with an elliptical head and a long, straight tail, about 300 million light years away from Earth. ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.