Lines of stars that we see in the sky

My question is about the patterns we see in the night sky. It's "well known" that the shapes and layouts of most of the constellations we can see would be totally different when seen from other parts of the Galaxy. That's because it's just fortuitous that we can see something in the various groups that allow our brains spot a pattern. We love patterns and constellations are an excellent way of referencing places in the heavens.

However, if you look at images of many star clusters (visibly identifiable and named because the structures stand out), you can see that many of them are similar colours and magnitudes. Take the Pleiades asterism, for instance.

If you look at the line of fainter stars heading from the centre to 6 O'clock then that stands out. Also there is a less definite line heading our to about 10 O'clock. It seems that most of this cluster were formed as about the same time and they have a lot in common. They are relatively near each other. So would we see the same string if we moved across (left to right, perhaps)? There are many other examples of these threadlike patterns in many images of star groups.

This video shows a simulation of star formation within a nebula and it suggests that many of the stars are formed along threads. Is this what we see when we see these lines or is it just in our heads? Could it be just Canals on Mars of are we actually seeing the (result of the) formation process? That video is very entertaining so, even if you think I'm being fanciful, take a look.

I think it’s just the human eye playing tricks because they wouldn’t necessarily be in a line from a different vantage point.

Devin-M said:

I think it’s just the human eye playing tricks because they wouldn’t necessarily be in a line from a different vantage point.

I realise that any apparent random row of stars would look different from another angle but does that have to apply a line of stars with common origin and distance? That simulation seems to imply that thread-like structures may occur - at least at some stage during stellar development. We're not just dealing with tea leaves here.

Our brains look for patterns when we are bored.

Do stars form along lines, or once formed, do they follow each other in lines (during the mating season), or are we just bored?

Apart from gravity, how might lines of stars communicate?

Are the arms of a spiral galaxy, spirals of matter, or spirals (or waves) of luminosity on an isotropic background?

wikipedia said:

Breeding season begins in late June and extends through September. Males will form lines up to ten individuals long, the youngest echidna trailing last, that follow the female and attempt to mate. During a mating season an echidna may switch between lines. This is known as the "train" system.

https://en.wikipedia.org/wiki/Echidna#Reproduction

Baluncore said:

Our brains look for patterns when we are bored.

We look for patterns when we are hungry or threatened, rather than bored. I don't think we needed to think about things when we were in standby mode in the ancient past.

Baluncore said:

Apart from gravity, how might lines of stars communicate?

Apart from our friend Dark Matter, gravity explains a lot about the structure of things. The arms of the galaxy are thought to be due to density waves from interactions (g) between stars. The arms / waves do not move at the same speed as the stars, as with many other wave phenomena.

I think that animation has a credible source (it certainly cost a lot of processor time). It seems to be accepted that patterns are created by gravitational interactions between very large numbers of massive objects so why not go along with the idea of threads. The only objection could be the time scales involved.

There are ~10,000 naked eye stars. So ~5000 per hemisphere. So 12.5 million lines between them. Assume the are 90 degrees long and 1/20 degree wide (the moon is 1/2 degree) that's 50 million square degrees covered by lines. There are 20,000 square degrees in the northern hemisphere, so on average a spot in space has 2500 lines going through it.

You need to go somewhere around 3rd magnitude before you get a substantial area of the sky not between two such stars.

Vanadium 50 said:

There are ~10,000 naked eye stars. So ~5000 per hemisphere. So 12.5 million lines between them. Assume the are 90 degrees long and 1/20 degree wide (the moon is 1/2 degree) that's 50 million square degrees covered by lines. There are 20,000 square degrees in the northern hemisphere, so on average a spot in space has 2500 lines going through it.

You need to go somewhere around 3rd magnitude before you get a substantial area of the sky not between two such stars.

You've tried to do a sort of Drake equation there. A good approach but you'd have to define what would constitute a line - say at least five stars and a deviation of say 20% of the spacing. I do realise that there is an instinctive reaction against considering it could be anything more than 'in your head'. I suppose the data is all there, from Gaia and it would be possible to identify actual lines of stars in 3D. But that's big boys' calculations.

Sounds like we need some kind of artificial intelligence to compare it to......hey, wait a minute.....

sophiecentaur said:

You've tried to do a sort of Drake equation there.

I don't see how Drake enters into it. This is a combinatorics problem, plain and simple.

sophiecentaur said:

but you'd have to define what would constitute a line

And I did - between the two endpoints and 1/10 the apprant width of the moon in thickness.

I picked that because I didn't have an alternative - it's your problem, feel free to define it any way you like. However, with 2500 lines going through each point, the exact definition will make little difference. You can only change the answer by requiring the endpoint stars to be much closer, much brighter (I did an example) or the lines to be much thinner (although eventually parallax will limit this).

An alternative is to look at something called a two-point correlation function. This deals with angular separation, not putative lines, and it shows a very weak correlation. Some stars optically close to each other are in fact physically close (Mizar and Alcor) and others are not (Alpha Capricornae). For this to show a signal, you need to get to pretty dim stars (then the galactic plane becomes visible - or rather, the dust makes more stars invisible)

By the way, the same argument can be used with Ley Lines. "Spooky things are happening - and we're near the intersection of two Ley Lines!"

You could define a cylinder length and width then consider how many sets of 3 or more stars in a given star field fit within the imaginary cylinder. If no sets of 3 stars fit in the cylinder the line is imaginary.

Vanadium 50 said:

And I did - between the two endpoints and 1/10 the apprant width of the moon in thickness.

Up to a point but that's only half way there. The actual numbers count and, in my question, I'm requiring several stars to constitute a suitable thread. I'm not considering just any old identifiable string of stars. The only way to prove or disprove my idea would be with actual evidence from Gaia data, filtering the candidate stars for characteristics such as age and probable origin.

Sorry but the Lay Lines thing is a bit of a straw man. The evidence for Lay Lines has been considered and rejected and that's not surprising because there's no Science there. I don't believe in spooky any more than you do. I was not so much proposing my own theory (verboten) as asking whether a correlation has been suggested as being credible or even found.

Vanadium 50 said:

This deals with angular separation, not putative lines, and it shows a very weak correlation.

I didn't understand this bit. Is that "weak correlation based on actual data?

Perhaps I could re-state my question in the form "Are there any actual strings of stars and what could have caused them?"

sophiecentaur said:

in my question, I'm requiring several stars to constitute a suitable thread.

Then this depends on how many is "many" and how close is "close".

Your question is whether we see more than would be expected from chance alone. To do that, you need to define the condition well enough to figure out what chance alone predicts. My point is that chance alone produced a high number of apparent lines, probably more than most people think.

Ad yes, Ley lines are bogus. That makes them great a a null hypothesis, since there can't possibly be anything beyond random chance.

I'm reminded of:

We have the stars we see, and we cannot change them.
The statistics of probability are irrelevant to the patterns we see, partly because we evolved to look at patterns, only in this one sky.

PeroK said:

The Old Grey Whistle Test

Is that like MTV for old people?
(Then again, these days MTV is MTV for old people)

Vanadium 50 said:

Is that like MTV for old people?

It was an iconic British live rock show from the 1970s hosted by "whispering" Bob Harris. It featured some unique performances over the years from Bowie to Captain Beefheart to Curtis Mayfield and hundreds more.

It was on last thing at night on BBC 2, in the days when there were only three channels, which shutdown around midnight.

Every New Year's Eve there was the OGWT "pick of the year", featuring the best from the past year. My mother tormented herself one year by sitting up (long past her bedtime) with my brother and me until eventually Reelin' in the Years by Steely Dan proved the last straw and we were driven off to bed.

Lots of episodes are on YouTube if you want a trip down memory lane.

sophiecentaur said:

TL;DR Summary: Many stars are parts of star clusters. The parts of many of those clusters actually lie within the same region and the evidence for this is their common chemical fingerprints. How likely is it that a particular 'line of stars' would appear a line from other frames?

It's "well known" that the shapes and layouts of most of the constellations we can see would be totally different when seen from other parts of the Galaxy

Drew this up a few years ago.

sophiecentaur said:

TL;DR Summary: Many stars are parts of star clusters. The parts of many of those clusters actually lie within the same region and the evidence for this is their common chemical fingerprints. How likely is it that a particular 'line of stars' would appear a line from other frames?

This video shows a simulation of star formation within a nebula and it suggests that many of the stars are formed along threads. Is this what we see when we see these lines or is it just in our heads?

When I watch the simulation video, to my eye the “threads” look curved. Also from my experience using a gravity simulator software package, if we initially place 3 stars actually in a straight line, they likely won’t stay that way for long. Likely one gets ejected, the other 2 form a binary. Or if they are in a straight line with no initial relative velocity they might even collide and go supernova.

Devin-M said:

When I watch the simulation video, to my eye the “threads” look curved. Also from my experience using a gravity simulator software package, if we initially place 3 stars actually in a straight line, they likely won’t stay that way for long.

You have a point regarding stability but that, I would think, is more suitable for binary and triple star formations. Most binary are very close together; closer than the separations of components of the threads I'm interested in. And the threads needn't actually have long lifetimes if they are in new star (so-called) nurseries. That simulation talks in terms of millions of years which is long for observation but short compared with other processes.

I did the simulation. Three stars in a row, initial 1 light year separation, zero initial velocity.... exciting part 4:30... system lasts about 2.5 million years.

Devin-M said:

I did the simulation. Three stars in a row, initial 1 light year separation, zero initial velocity.... exciting part 4:30... system lasts about 2.5 million years.

Should I be seeing three stars? I can only see two (apart from the wallpaper behind the action). If they have zero velocity then they will be attracted to each other and, as there is no Angular Momentum, they will collide. They only need a small amount of tangential velocity component to take up a mutual orbit without colliding. One interesting thing about gravity is that inverse square law which still works over the light years but the tiny forces over those distances still get things moving mutually. And what's a couple of million years when we're dealing with more than 30 Billion years since the start.

However, with respect, this is nothing like the simulation I posted. There is no wallpaper on that display. Any mass of gas and dust will have a net angular momentum and that will be conserved throughout the life of the object(s). The simulation (the one I posted) takes a huge number of particles with random velocities and plots the way they will interact. Stars are formed as gravitational potential energy transfers into KE and then thermal energy etc. etc. As I don't know the spacings or velocities (I guess I could find out) then I don't know whether that line of stars in Pleaides is actually a 'thread' of stars. I was rather hoping that someone on PF

sophiecentaur said:

Should I be seeing three stars? I can only see two (apart from the wallpaper behind the action).

OK I see them now. Problem is that, in the video, you very soon zoom the left one out of the picture and that's when I was looking. But my comment stands. Your initial conditions doom them to collision and that's not we observe. There would be no binary stars if they started off that way. And, of course, the reference frame for 'zero angular momentum' is questionable. IS there, in fact, such a frame in the Universe?

sophiecentaur said:

And, of course, the reference frame for 'zero angular momentum' is questionable. IS there, in fact, such a frame in the Universe?

Yes. Zero angular momentum is relative to each other.

There was a thread recently about whether two observers in an otherwise massless universe would even experience angular rotation. They would; they would pirouette around each other and their inertia would manifest as a centrifugal force.

DaveC426913 said:

Yes. Zero angular momentum is relative to each other.

There was a thread recently about whether two observers in an otherwise massless universe would even experience angular rotation. They would; they would pirouette around each other and their inertia would manifest as a centrifugal force.

Orbit the common CM and maintain net angular momentum. …… and so on for millions of objects.

Getting cluster stars in a line is like that party-trick of finding people with same birthday...

How many guests before you get a match ?? Surprisingly few...

FWIW, 'Ley Lines', most of them are total twaddle at best, as the land-marks they reference are modern. (*) But, if you go back to the original guy, he logged many genuine sight-lines for pack-horse trails and drove roads between eg ridge crossings and river fords. Essential when land was still blanketed by old-growth 'wild-woods' with bears, wolves, boar etc etc...

*) And the less said about trans-continental 'alignments' the better, given proponents' enthusiastic use of inappropriate map projections rather than 'Great Circles'...