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What is the axial orientation of Polaris with respect to the Earth? Answered

So... I know the Earth's axis of rotation currently points (roughly) at Polaris, the North Star.
(which, of course, is why we can navigate by it here on Terra Firma). 

I also know that Polaris is about ~500 ly from us,  has a rotational period (hence an axis), that it's a transitional Cepheid (sp) (a star that varies between a larger, brighter state and a smaller, denser one) , that it has at least two l known, low-output companion stars, and that since the ~1940s it has undergone visible changes in its rotational period and its output.

My excuse and reason  for asking...

First, I did google it. Either no one has asked the question(doubtful), it can't really be determined with our present level of science (could be, idk), or I just didn't use the right search  terms to find the answer (the usual culprit ime) , but in any case, after an off and on search that's spanned the past ~year, I think it's time I ask.

Secondly, the inspiration. I enjoy amateur astronomy.  However, time and equipment and location often limit my grand delusions for the next "Citizen challenges Hubble with stunning new photo of Zeta p3044-a!" award hahahaha.  But the real problem is most often because of my mid-level scope's somewhat limited ability (in comparison to a German equatorial mount) to track consistently and smoothly, and as a result, Polaris becomes an easy target when I get frustrated with the scopes performance on a given night (sometimes it does track brilliantly... for a stepper-driven alt-z, but only sometimes and even then only to the limits of the steps) because the only thing the scope has to track when pointed at the North Star is rotation, which it seems to handle better than both directions of movement (probably needs a new gear or the motor is wearing or my expectations are simply higher than that of my equipment ...).

Of course, I also quite often choose to shoot Polaris when conditions are such that it's the only viable target (for instance, when I'm stuck imaging from my backyard, I have a postage stamp size hole that happens to point at Polaris... which of course basically "doesn't move", pretty much everything else is shrouded by century old, 8-100 ft tall forest during the warmer months, and when I can't drive out to a more suitable location, it's a lucky night when everything is "right", I can even align the mount (it uses a goto controller that requires a 3 star alignment for tracking with any accuracy). So Polaris is a no-brainer, (take some images for arts sake, fine tune the in-situ collimation, data-reduction test sets, etc.) . Either that or do something else... 

Anyway, as a result of all of this, I'm found myself enjoying the simplicity of shooting the North Star and the area around it, and having fun with image processing and even optical train modifications to further the artistic side. And I've read a few articles about it's variability and the ~relatively significant changes in its behavior that have been occurring during the past 50 years that got me to thinking

What I'm wondering is that when I image Polaris, am I looking at it "on its side?", "on axis?", or at some other viewing angle? Not that I'm going to be able to literally "view it on its side" or something, since optically imaging the star beyond that roughly of a point-source isn't practical, but just to know, since the darned question won't get out of my head. (been asking it for the past year quietly to myself and google. I hate to think how many cumulative hours I've spent at it...)




Best Answer 3 years ago

I would say that it is constantly changing with respect to earth. Thinking of just the earth itself, its axis is not straight up and down with respect to its orbital plane so as it goes through its orbit the orientation to anything else will change, including the sun.

Secondly if Polaris itself had a straight up and down axis with respect to its orbiting plane that would have to be in a plane that is absolutly parallel to earths plane of orbit and the chances of that happening in a galaxy that is itself orbiting are next to nill. That fact that it is in a dance with several companions reduces the likely hood even more. It is also entirely posible that the orbital plane of that system is spinning in some direction as well. I am not aware of it having been determined if most of the stars in the galaxy are rotating in the same plane as they orbit the galaxy. Looking at the solar system and the rotation rates of the various planets it is highly unlikely that there is any kind of syncronious mechanism that would cause them to all rotate in the same way, much less in the same direction. Everything is in motion and nothing is lined up with anything else for more than a moment in time.

Oops prematurely closed the question, no offense Vyger. Just as well, this may be too much for ibles.

Yeah, it's possible the companion stars, much smaller though I believe they are, cause it to experience periods of major discontinuities that cause it's axis to remain in constant flux, as you intimate, or simply that we can't measure it at this point.

Thanks everyone for the replies.

Check out the forums at Cloudynights.com you can probably post the question in there.

Yup or one of the others (haven't successfully subscribed to Cloudy Nights although I've tried on multiple occasions).

I had the same issues, but I spoke to one of their admins and they made it happen pretty quick. Its well policed and polite in there.

Sadly, I heard nothing back when I attempted to contact the admin.

No big deal. I figured they were simply keeping within their bandwidth and may have grown too popular to sustain with their own funds beyond particular user count, or as some site are, just being exclusive. I tend to become mired in social sites anyway, regardless of their intent.

I'll pursue with more vigor if it becomes an issue or I get serious about the hobby and do "sum reel larnin" XD. I'm no dummy, but I'm not ashamed to admit that I'm devoid of any serious/academic targeted technical training in astronomy beyond that I got when I was in grade school, and articles I've read during my tenure as an adult. Fortunately, that academic void is offset by other ~related academic pursuits along the way that fill in some of the blanks and assist my Brainputer(tm) to get around some issues they can't settle on their own, along with my tenactiy and bliundering experimentation. .

Yep. Exactly. Very cool... To be honest, I wasn't aware until the changes in my images from session to session made me wonder and I happened to stumble on an article much like the one you cite that correlated to what I was wondering. I've had some very variable sky conditions during astronomy sessions, and at first I ascribed them all to essentially, light pollution (including non man made contributors), but a combination of factors when imaging and processing got me to imagining that something like what's really going on was in fact going on (~433 years ago that is)

The fact that it's shedding large quantities of mass implies that like many other astronomical phenomena, it's probably shedding and axially ejecting that mass, and the way they talk, it sounds as if that ejecta, whether via radial or axial transport, is significant (and possibly even detectable by visible detection, ie, possibly detectable to some degree by an amateur). I would think that from an astronomer's pov, knowing the axial orientation of Polaris, even if only in a general way (on-axis, on-side, oblique?) might be of value, and it's one of those things that astronomical data often includes for other things (obviously, planetary, afaik, galaxies, and many well-known nebulae all have published axial info of one sort or another)

BTW kudos on your terrestrial photo now being pointed to by Google

Lol... Say what? My terrestrial photo?

ok I'm clumsy w compliments but you took those images from the ground however high the hills you climbed, as opposed to space telescopes or I am totally in the dark how you do it.

Well, darn, I wrote a real nice reply, which just got lost by an accidental mouse click. (editorial note: and the lack of message editing and automatic post backup at ibles.)

Anyway, in brief, thanks. I used a small (~5 inch) alt-azimuth newtonian goto mount to capture a series of short (1 sec) exposures "stacked" (aligned and blended, then color-processed in photoshop. Due to its drive system being stepper-motor based, It's not an ideal scope mount (tube has mirror and stuff, mount is what positions the scope tube to a given target, and ideal would be a considerably more expensive German Equatorial mount ... one axis fixed to point at pole star other rotates freely, generally uses higher quality servos rather than discrete-motion steppers) , but even though not ideal, the alt-az works ok-ish if you use it within it's limitations... and sometimes, even when you work slightly outside it. I also bought an old 80mm refractor that I setup in my dining room to shoot Polaris through the window ( yes, any cringing astronomers reading this, I'm well aware that "I can't do that!!!"... schmeh... I parry with "art for art's sake". Ha, take that, you conformist cur!) and that particular game has yield some very surprising output. (see the image I'm attaching to this post)

Sidenote: I use *lots of short samples (< 15 seconds, and mostly more like 1-5 sec) and some processing tricks to overcome (within reason) the inherent S/N issues with the alt-az. Drizzling, one of the processing tricks, seems well suited to dealing with the noise in low quality, short duration samples on a small footprint planetary camera like mine (SBIG STI-C @~640x480px), and it often finds hidden info that I know is in better sampled data but isn't visible using normal processing. It's kinda magic, even if I know the math well enough to know it's not. Still watching stars appear out of the balck in a doubled or tripled footprint black-box output from the drizzling is pretty neato.

* statistical variance is proportional to 1/(sqrt(# samples)

(drizzling: hard to explain in brief. basically interpolates the image data using adjacent pixel data to create a super set (image doubles in size each degree of depth one goes in the interpolation. wiki entry: see > here)

This was shot using my 80mm refractor, by defocusing Polaris through two panes (window and storm ~ 3 inch separation ) of ordinary double strength window glass set at (90 - myGeoLatitude) degrees to the optical axis (think refraction kids...) the panes were carefully cleaned, and no mask was applied. this is all light from the star, refracted through the glass. The first time, I just did it because it was frigid outside, I hadn't shot an image in months, and the sky was pitch black and I was bored. But it kinda got me hooked, once I saw what it offered, antithetical to the astronomy-purist mantra or not. Amazing what coincidence can do. (I *do shoot the more normal stuff too, although this little scope has definite limitations that exceed my demands more often than not)

Anyway, no special tricks (beyond what I already explained) were used to process the photo. just simple color processing) this(and a more tidied "finished photo") is what I got direct from stacking about 700 1-second snapshots. Why?

a) distortions inherent to the scope

b) distortions due to intervening window panes

c) distortions due to the atmosphere

d) (I think) distortions due to magnified coronal imbalance in the defocused star. In any case, it's the light source.

oh, and just two more. the B&W is a png of the source for the one with light blue atop and ~brown below (sorta looks like an African woven shield.. or something... look close.). again. nothing special, no real "tricks (like superimposition or masking) just a bit of stretching and color layer isolation.

Ok too much time spent. I have to shower and get the cat to the vet.

Polaris_lord_of_the_North, raw_stacked.jpgPolaris - Lord_of_the_North_framed.jpgitem5_at_50a_low-q.jpgalien.png

Polaris is arguably a 5 star system....so its a bit complicated.

True. Polaris may (or not) have significant precession about it's own axis due to gravitational interaction with the other members. But if it doesn't precess significantly, we can at least make a general statement about what that tilt is (if such a thing can indeed be measured or inferred at 433ly away). Mass polar ejections, for instance, (as may be occurring now... or occurred, anyway) produce characteristic behaviors in part based on the spin of the star (some are nearly straight line, some corkscrew, etc.), and the evidence of those behaviors often has a predominant directional orientation.