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More to the North Star Than Meets the Eye
__roo writes "By stretching the capabilities of NASA's Hubble Space Telescope to the limit, astronomers have photographed the close companion of Polaris for the first time. This sequence of images shows that the North Star, Polaris is really a triple star system. 'The star we observed is so close to Polaris that we needed every available bit of Hubble's resolution to see it'" said astronomer Nancy Evans of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts."
"sequence of images shows that the North Star, Polaris is really a triple star system."
Damit! OK, so which star do I point my sextant at then if I'm trying to find my latitude? Modern science complicates things so much!
[Yes this is a joke, for those who don't get astronomy humour.]
Saskboy's blog is good. 9 out of 10 dentists agree.
The Hubble already has a repalcement in the works. It is called The James Webb Space Telescope and is scheduled to go up in 2013. More about the JWST
According to google calculator:
2 000 000 000 miles = 21.5155818 Astronomical Units
which puts it just inside the closest approach of Saturn, but well outside Jupiter's orbit.
Polaris ---> O
Polaris Ab---->.
Polaris A --------->o
From the article: "The companion proved to be less than two-tenths of an arcsecond from Polaris... At the system's distance of 430 light-years, that translates into a separation of about 2 billion miles."
I did a little googling, and found that Neptune's orbit is just over 2 billion miles from the Sun. So for reference, Hubble has directly imaged two distant objects that could fit inside our own solar system.
I think they could have gotten more "Oomph!" from their press release if they'd mentioned this fact. Also, they may have wanted to measure the distance in a standard publicity unit, such as roundtrip NY-LA distances ("A little over 350,000 round-trips from New York to Los Angeles").
Stressed? Me? Of course not. Stress is what a rubber band feels before it breaks, silly.
Actually, I'm not sure that there's anything in this observation that Hubble is needed for. AO is limited in the ultraviolet, but this observation could have been made in the visisble spectrum, I would expect. As such, any of the more recent large telescopes with AO should have been able to make this observation. It just so happens that it was done with Hubble instead.
For those not aware, AO is "Addaptive Optics". This is how you use ground-based scopes, but compensate for the atmosphere. It usually involves deforming a physical mirror, though I think there are some AO systems that work purely digitally. I'm not sure. IANAA.
AO was perfected after Hubble went up, and many ground-based scopes have gotten imaging that's just as detailed (more so in some cases) as Hubble is capable of. I have an astronomer friend who was fond of showing off some photos that he had from AO scopes off of relatively old, retrofitted systems that he claimed were better imaging that Hubble had been able to get from the same objects.
It's a triple star system if they're all rotating around a common centre of gravity, even if PolarisB seems to be quite an outsider (although on the scale they're showing it is probably still at a distance similar to a Kuiper belt object (rough guess) whilst this Ab star is at Saturn distance from A.
I suppose it is possible that Ab is behind A and thus appears further away, but I'm sure they've done their maths and checked it over a lot before releasing the PR.
The North Star: Robots In Disguise
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Adaptive optics systems are necessarily ground-based. The actuators and the lenses required are too bulky and heavy to be lugged into orbit. The atmosphere absorbs much incoming radiation. (Thank god, or we'd all literally be toast.) Scientists interested in the ultraviolet have to use space-based telescopes. Hence, the Hubble replacement does not focus on the visible because AO can take care of that from Earth, since we can build arbitrarily large arrays.
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Your first comment is true in the general 3-body problem, but certain cases are actually stable over a long period of time. Namely, when two of the bodies are in a very tight orbit which is not significantly perturbed by the 3rd body.
So, the system approximates a stable two body system.
Another similar case is 4 stars, where there are two close pairs in orbit around each other. This idea can be extrapolated to any number of stars as long as each pair is not significantly perturbed by its non-pair neighbors.
HCG 50a = 2MASX J11170638+5455016
11h17m06.4s +54d55m02s
Yes, someone always posts this when the death of the hubble is brought up, but what they never do is pay attention that the JWST can't see all that Hubble sees. They're built to look at different parts of the spectrum (yes, there is overlap), so one will never actually replace the capabilites of the other. They would however complement eachother's abilities.
- AMW
Where did you get this? There are many reasonably stable three-plus body systems. ("reasonably stable" meaning that they'll last the lifetime of the stars, but could still be disrupted by passing stars, etc.)
The classic example is a close binary with a distant third. The distant star essentially sees the binaries as a point. The binaries see the gravitational attraction of the third star as essentially flat (since the tidal forces drop off as 1/r^3). This doesn't mean non-zero, it just means that the attraction of the "near" star won't be higher than the attraction of the "far" star. IIRC that's why the moon is slowly pulling away from the earth -- the sun is slowly pulling the earth and the moon apart.
Another example is a pair of close binaries. Again each binary is overwhelmingly dominated by its pair, with the gravitational attraction of the other pair as essentially flat.
For every complex problem there is an answer that is clear, simple, and wrong. -- H L Mencken
astronomers have photographed the close companion of Polaris
Waitaminute. Polaris is GAY?