Celestia Forums

Better now edit the stc info to Polaris in Celestia, cause new study is that the North Pole star Polaris is a lot closer than really thought. It was thought it was 434 light-years away, but it is 100 light-years closer. So it is 323 light-years away

Just as simple as this:



http://www.space.com/18717-north-star-d ... ement.html

The famed North Star has been a beacon in the night sky throughout human history, but a new study reveals the star is actually closer to our solar system than previously thought.

Scientists studying the North Star Polaris found that it is about 323 light-years from the sun and Earth, substantially closer than a previous estimate of 434 light-years by a European satellite in the late 1990s. The new distance measurement may help astronomers in the pursuit of several cosmic mysteries, such as the hunt for elusive dark energy, researchers said.

Polaris is what astronomers call a Cepheid variable star, a pulsating star used by scientists to measure distances in space. Astronomers can measure the distance to a Cepheid variable by studying how it changes in brightness over time.

http://www.space.com/15567-north-star-polaris.html

In 1929, by studying the spectrum of Polaris, a third companion star (Polaris C) was discovered. This one, a white dwarf, lies only 18.5 a.u. from Polaris A (about the same distance of the planet Uranus from our sun). Its extreme closeness to the far more brilliant Polaris A explains why it went unseen for so long.

Polaris is actually still drawing closer to the pole and on March 24, 2100, it will be as close to it as it ever will come, just 27.15 arc-minutes or slightly less than the Moon’s apparent diameter. Since it takes about 25,800-years for the Earth’s axis to complete a single wobble, different stars have become the North Star at different times. For example, the star Thuban in the constellation of Draco, the Dragon was the North Star around the year 2600 B.C., during the age of the Pyramid Builders of ancient Egypt. The brightest Guardian, Kochab, was the North Star at the time of Plato, around 400 BC.

And around the year 14,000, earth’s axis will point reasonably close to the star Vega, one of the brightest stars in the sky; perhaps our future descendants will confer the title of North Star on it.

One cool thing about that, is that during that time frame 14k-16k CE, ALF Cen will actually be visible from the Northern Hemisphere, thanks to that exact same precession.

Trust me, I checked. Celestia does have the Earth precess in the later versions.

kristoffer wrote:Better now edit the stc info to Polaris in Celestia, cause new study is that the North Pole star Polaris is a lot closer than really thought. It was thought it was 434 light-years away, but it is 100 light-years closer. So it is 323 light-years away

Just as simple as this:

Code: Select all

Modify "Polaris"
{
 Distance 323
}

http://www.space.com/18717-north-star-d ... ement.html

What a low level of writing about an important science result!

The writer at space.com didn't even consider it necessary to quote the original scientific paper. Since the distance of Polaris is anyhow much larger than what is exploitable by means of standard parallax measurements, it would have been most important to review the used (Cepheid-based) method underlying the new distance determination of this Cepheid variable, to discuss why it is more reliable than the previous one, and what its remaining uncertainties are. All these crucial aspects are hardly touched in this article.

Fridger

olyv wrote:Ola,
Under celestia, Polaris is a single star.
Who can we do a new stc file for this ?

If you were able to provide us with the scientific sources for the many lacking orbital data for this multiple system, then it would be trivial to implement this system in Celestia.

The official distributions of Celestia are NOT based on guesswork...and that's why Polaris still appears as a single star therein.

In celestia.Sci, I'll filter the used star data with the latest scientific catalogs about multiple stars. This will not allow me to render more binary star orbits, yet it is sufficient for a reliable flag on the info popup, indicating whether the selected star is a single one or a multiple system...

Fridger

t00fri wrote:What a low level of writing about an important science result!

The writer at space.com didn't even consider it necessary to quote the original scientific paper. Since the distance of Polaris is anyhow much larger than what is exploitable by means of standard parallax measurements, it would have been most important to review the used (Cepheid-based) method underlying the new distance determination of this Cepheid variable, to discuss why it is more reliable than the previous one, and what its remaining uncertainties are.

The paper is still in press, but the arxiv version is here: http://arxiv.org/abs/1211.6103.

Grant

granthutchison wrote:

t00fri wrote:What a low level of writing about an important science result!

The writer at space.com didn't even consider it necessary to quote the original scientific paper. Since the distance of Polaris is anyhow much larger than what is exploitable by means of standard parallax measurements, it would have been most important to review the used (Cepheid-based) method underlying the new distance determination of this Cepheid variable, to discuss why it is more reliable than the previous one, and what its remaining uncertainties are.

The paper is still in press, but the arxiv version is here: http://arxiv.org/abs/1211.6103.

Grant

Thanks, for the link, Grant. Meanwhile I also had located the preprint. arXiv preprints make up my daily morning reading

Fridger

symaski62 wrote:The brightest Guardian, Kochab, was the North Star at the time of Plato, around 400 BC.

Be caution with statements like these, because it was untrue for Eudoxus (a Plato's pupil), for whom the polar star was the head of the Dragon. For us in our time at the Plato's epoch the statement is correct; for Plato and Eudoxus in their time not.