Astronomers scared of ever-brightening star

[kalian]

http://www.smh.com.au/articles/2004/06/01/1086037753147.html

Julius Caesar might have said he was as constant as the northern star, but it wasn't much of a boast. Over the past two millennia, the star Polaris has brightened by 250 per cent, astronomers announced today.

...more...

Scared...why? :shrug:

[brokensymmetry]

1. A supernova can ruin your whole day.

But at 400 light years distance, Polaris is probably safe. :)

[kalian]

2. Unless its a hypernova....

:P

[Book Lover]

3. I think she was speaking rhetorically

http://www.nytimes.com/2004/06/01/science/space/01star.html?ex=1086667200&en=2f369908cade1abe&ei=5062&partner=GOOGLE

Astronomers have known for some time that Polaris, the North Star, sitting almost directly over the North Pole, is a Cepheid variable, a type of star that is caught in a cycle of bloating and collapsing because it has exhausted its hydrogen fuel.

...

Yesterday at a meeting of the American Astronomical Society in Denver, astronomers reported that Polaris is even unsteadier than they had thought.

Even Polaris's average brightness has not remained the same, reported Dr. Edward F. Guinan of Villanova University. Measurements over the past half century show it has brightened 10 percent. When he and Scott Engle, an undergraduate, checked older records, they found more surprises.

In the 1800's, Polaris appeared to be 20 percent less bright. In the 1500's, the astronomer Tycho Brahe recorded an even dimmer value. Ptolemy of Alexandria in his star catalog of A.D. 140 listed Polaris as a third magnitude star. Magnitude is a scale devised by the Greek astronomer Hipparchus around 120 B.C. ranking stars from bright (1) to dim (6), a system still in use today.

...

Meanwhile, Dr. David G. Turner of St. Mary's University in Halifax, Nova Scotia, said Polaris was much closer than had been thought. His research indicates that Polaris is 310 light-years away. The current accepted distance to Polaris is 430 light-years.

If Dr. Turner is correct, his findings offer an explanation for why Polaris appears as bright as it does. Until now, astronomers have suggested that the star possesses unusual internal pulsations that pump out additional light, but if it is nearer, that elaborate theory would be unnecessary.


I love the pursuit of science!

[NNadir]

4. Brightening stars forebode plagues, wars, drought, famine, and a

rather unfortunate television season with poorly thought out shows.

[Ilsa]

5. A hypernova will certainly ruin your whole day.

And most of the planet, I take it. Spooky.

[RoyGBiv]

6. Odd...

It'd be interesting to review their findings. They say they have used sources such as observations by Ptolemy in order to determine the "true" brightness over the past 2000 years. Now, I'm curious how these visual observations are reconciled with modern measurements.

[Speck Tater]

9. Ancient observations

are easy to reconcile with modern observations because the brightness scale is rlative to other stars of known brightness. In ancient times they might have recorded that star X is brighter than star Y but dimmer than star Z. If that relative ranking is no longer true then at least one of the three stars in question has changed brightness. With a suitable set of observations it can be determined which has changed, and by how much.

[RoyGBiv]

10. I understand that much...

I'm just confused about the the precision of statements like "X times brighter" now as opposed to then.

Obviously I'm not an expert on this sort of thing. But I have done a lot of historical research and am often faced with the problem of interpreting statements of historical figures that are based on matters of degree. I'm just always suspicious of modern scientific measurements based on these kinds of accounts.

I'm sure these people are aware of these problems. I'm not doubting them exactly, just curious how the conclusions were drawn, and I thank you for the explanation.

[benburch]

7. Scared because...

It is fairly close, only 431 light-years, and because it is not acting as we would expect.

Were it to become a Supernova, for example, we could expect enough radiation in the northern hemisphere to have a real biological effect. Not a Biblical catastrophe, certainly, but enough to elevate cancer rates.

The Crab Nebula, the closest supernova in recorded history was 6500 light-years away.

Also scary intellectually because it means that we either have a problem with our theory of how stars age, or because we don't know much about what sort of object Polaris actually is.

[iamjoy]

8. George Pal Would Say It Is Getting Closer

Waste anything but time.