8 rays are Webb's spikes; the opposite ones are of equal brightness while the local rays and shell segments are brighter to North and East of the WR 140
2 rays are a pair of jets; 2 o'clock one (to North and East of the WR 140) is brighter than 8 o'clock
1 ray, the 11 o'clock one, is in fact just the direction of the densest segments of the shells; those segments are also the most distant parts of each shell (therefore the fastest parts) — and the opposite segments are hard to see but are the most distant parts too
It is obvious that WR 140 is not just any old Wolf-Rayet star, if we compare it with WR 124. Of course, it must be said that the two images are not comparable, because the one of WR 140 was taken by JWST's mid-infrared instrument MIRI, whereas the portrait of WR 124 was taken by Hubble in visible light.
Nevertheless, it is obvious that something remarkable is going on with WR 140.
It is now regarded as the prototype colliding-wind binary.
Shortly after periastron passage [closest passage] every eight years, the infrared brightness increases dramatically and then slowly drops again over a period of months. Here stellar winds collide with the dust formation created by the Wolf-Rayet star, causing the unusual bulges and angles in the concentric shells of dust. The dust typically emitted by Wolf-Rayet systems is not so coherent or concentric as those of WR 140. The dust lanes around Wolf-Rayets are most commonly observed as some variety of spiral. This is thought to be the result of the dueling solar winds in binary systems, which compress clouds of dust into distinct shock fronts. The concentric nature of WR 140's dust shells is not well understood, although it may be related to nuclear processes in the Wolf-Rayet star's core.
So nobody quite knows what is going on with WR 140, although the shells clearly form as a consequence of the two components of the binary star passing close to one another. Their strong winds affect the dust that is produced by WR 140.
The enormous dust production of WR stars happens because the star keeps switching on and switching off helium fusion in a thin shell around its (inert) core:
As the Wolf-Rayet star in WR 140 neared the end of its short life its core ran out of hydrogen to fuse into helium.
The core then began to collapse, but:
This collapse eventually began to slow as it grew more intense and heated the star's interior. Along the edge of the core a thin shell experienced temperatures and pressures sufficient to begin helium fusion.
...
The star began to inflate...
The thin shell of helium fusion eventually caused enough expansion to moderate, or even extinguish its own reaction. The star once again began to collapse.
However, at the surface this loss of internal radiation pressure had the effect of blowing the outermost layers of the star's photosphere into space.
Once more the star began to fuse helium at a greater rate and temporarily regained its former radiation pressure. This helium fusion once again stalled, and the subsequent gravitational collapse dislodged another layer of photosphere into space.
These pulses will continue as long as this cycle of intermittent helium fusion can repeat itself.
WR 140 is not the only WR star to produce concentric shells (or, more likely, a spiral of dust) around itself. WR 112 does so too:
Click to play embedded YouTube video.
WR 112 has been photographed by the Keck Telescope, not by JWST's MIRI. Yeah, there is a difference. Anyway, check out the video. It is interesting.
The astronomer in the video talks about face-on and edge-on WR stars. WR 104 is a face-on one.
The WR star is surrounded by a distinctive spiral Wolf–Rayet nebula, often referred to as a pinwheel nebula. The rotational axis of the binary system, and likely of the two closest stars, is directed approximately towards Earth. Within the next few hundred thousand years, the Wolf–Rayet star is predicted to probably become a core-collapse-supernova with a small chance of producing a long duration gamma-ray burst.
And if WR 104 is to produce a gamma ray burst, it has a small chance of hitting us!! Yikes!!!
It is a good thing that space is big, so that any narrow gamma ray jet has a good chance of missing us!
Ann wrote: ↑Thu Oct 13, 2022 6:12 am
....So nobody quite knows what is going on with WR 140, although the shells clearly form as a consequence of the two components of the binary star passing close to one another. Their strong winds affect the dust that is produced by WR 140. ...
Let me guess at the nature of half-rings in this APOD
They say the binary WR 140 sytem's component are coming closer to each other every 8 years for a short while.|
Now the active one must be shedding most of the dust and gas just in those whiles.
The middle of such time interval can be the moment of the periastron, when the shedded matter is at first at the most depth of the other component's gravity well. This portion of the shedded matter has the dearest price to pay to escape the gravity and so it forms the slowest portion.
Now suppose that every moment of the short time interval around the periastron has its own unique direction of the most of shedding the matter, and that direction correlates with the components' relative positions. If the time interval of the most shedding is spreading over 180° of that direction, the densest fragments will be about 180°.
If all this is true, than those shells are in fact rings
APOD keeps finding all these beautiful things!
Rings around the star;
I wonder what you are!
I wonder how you were made;
Will you stay, or will you fade?
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk. — Garrison Keillor
orin stepanek wrote: ↑Thu Oct 13, 2022 11:39 am
WR140_WebbSchmidt_960.jpg
APOD keeps finding all these beautiful things!
Rings around the star;
I wonder what you are!
I wonder how you were made;
Will you stay, or will you fade?
Looking at the brightest new-born half-ring, the half-rings do fade.
Sadly they are too cold to be represented in a wide range of filters.
I would like to see the fading as bright yellow going dull orange going dark red, but all that Webb can is to show them in one colour.
Well, to show 18 half-rings instead of 2 is an achievement already
I'm doubtful that they are real. In my opinion, real physical light-year-long jets are hardly ever (and possibly never) so perfectly straight (and so perfectly separated by 180 degrees). What we are seeing is probably a photographic effect.
Ann
Edit: Okay, okay, Herbig-Haro 24 is a pretty straight jet (and it has a counterpart almost exactly opposite of it). But these jets still don't look like the apparent "jets" in WR 140.
I'm doubtful that they are real. In my opinion, real physical light-year-long jets are hardly ever (and possibly never) so perfectly straight (and so perfectly separated by 180 degrees). What we are seeing is probably a photographic effect.
Ann
Edit: Okay, okay, Herbig-Haro 24 is a pretty straight jet (and it has a counterpart almost exactly opposite of it). But these jets still don't look like the apparent "jets" in WR 140.
To make strange jets stranger still:
they are not equal in brightness at all, like the matter is moving relativistically fast making the headwind jet brighter.
For an ultra-relativistic pair of jets one may be invisible, like from M87* massive black hole.
I think a neutron star or a white dwarf could produce jets at 0.1c, but they say we have a pair of O stars here…
To make strange jets even more strange:
the one at 2 o'clock, visually crossing dusty half-rings is making their segments brighter and leaving the gaps dark
To make the jets even stranger:
the 2 o'clock is in sync with periastrons, it is where the half-rings are the closest to the center and so the slowest
Last edited by VictorBorun on Thu Oct 13, 2022 10:42 pm, edited 1 time in total.
Postby But why is it squaaaare? » Thu Oct 13, 2022 10:55 pm
The paper in Nat Astro is open (yay, they all should be) at https://www.nature.com/articles/s41550-022-01812-x. Obviously it's a good one and I'm saving it for my next sitting with a beer in my favorite cafe, but just a glance and it (sorta) resolves the big question that jumps out of this picture.
OK, the WR burps once in a while and then the rad pressure pushes it and it makes these rings, but why do they have to be square? Yes there's the Red Rectangle and a few other celestial squares out there but they're really biconic, and here it's not that. So, apparently two intersecting tori can make a squared-off section, in projection; the paper doesn't look too clear about it but conveys awe at how well its model reproduces the outlandish shape. From the paper:
Now, who will grab two paper tubes and a pair of scissors, and build us a model of WR140?
if you look hard or increase gamma where you expect the missing halves of the dusty half-rings
you can actually see some of them:
I tried to draw one full ring, symmetrically, and it fitted
(see the yellow line I displaced to bottom right corner)
But why is it squaaaare? wrote: ↑Thu Oct 13, 2022 10:55 pm
The paper in Nat Astro is open (yay, they all should be) at https://www.nature.com/articles/s41550-022-01812-x. Obviously it's a good one and I'm saving it for my next sitting with a beer in my favorite cafe, but just a glance and it (sorta) resolves the big question that jumps out of this picture.
OK, the WR burps once in a while and then the rad pressure pushes it and it makes these rings, but why do they have to be square? Yes there's the Red Rectangle and a few other celestial squares out there but they're really biconic, and here it's not that. So, apparently two intersecting tori can make a squared-off section, in projection; the paper doesn't look too clear about it but conveys awe at how well its model reproduces the outlandish shape. From the paper:
Now, who will grab two paper tubes and a pair of scissors, and build us a model of WR140?
I don't think the whole rings are rectangles (that you can inscribe into a circle)
I think each full ring is composed of two arcs, in symmetry with each other under 180° rotation,
that the duller arc is dust-poor (it is blown from WR directly away from O companion, with no wind-against-wind compression and little carbon-rich dust formation)
that the closest parts of the arcs are in the directions of O—WR and WR—O at periastrons (those portions have the deepest gravitation well to climb from and therefore are left with the lowest velocity after making their escape),
that for a good half of the 8 year orbital period WR is not being tidally disturbed enough to mix the surface nuclear fusion fuel into the denser region and start the fusion (that's when WR is silent and the gaps between the dust rings form)
that for some reason the periastron moment is not quite in the middle of the dust production interval (can WR be slow to start and slow to stop the blowing?). Were the periastron moment quite in the middle of the dust production interval, each arc would be symmetric under flipping about the periastron direction and the whole ring would be shaped like an eye looking from between eyelids
So the strangely square shape of the dust shells of WR 140 is a consequence of the angles at which we see the nested shells. Think of the shells as two empty toilet rolls. We are looking straight down the tube of one of them, so we see it "round opening". But we are watching the other cylinder from the side, more or less "lying down", so we see its straight edge.
Thanks a bunch, "But why is it squaaaare?"! This is your first post here, no? It's a really good one! Thanks!
Eight prominent and symmetrical diffraction spikes due to the secondary struts and the hexagonal shape of JWST’s primary mirror are present around the saturated core of WR 140 in the MIRI image and exhibit bluer colours than the dust emission (Fig. 1, left). Interestingly, there are two additional asymmetric and ‘redder’ linear features that extend from the core of WR 140 to the northwest and southeast. These linear features are not consistent with known instrumental artefacts from bright point sources, which indicates that their origin is astrophysical and probably attributable to emission from circumstellar dust.
So if these things are attributable to emission from circumstellar dust, does that make them jets? Are we talking about two long narrow "dust pillars"? Or is the dust ubiquitous and just "illuminated" down a narrow "corridor" that makes these narrow dust columns glow in infrared? Could they be similar to a sun pillar shining at infrared wavelengths?
Eight prominent and symmetrical diffraction spikes due to the secondary struts and the hexagonal shape of JWST’s primary mirror are present around the saturated core of WR 140 in the MIRI image and exhibit bluer colours than the dust emission (Fig. 1, left). Interestingly, there are two additional asymmetric and ‘redder’ linear features that extend from the core of WR 140 to the northwest and southeast. These linear features are not consistent with known instrumental artefacts from bright point sources, which indicates that their origin is astrophysical and probably attributable to emission from circumstellar dust.
So if these things are attributable to emission from circumstellar dust, does that make them jets? Are we talking about two long narrow "dust pillars"? Or is the dust ubiquitous and just "illuminated" down a narrow "corridor" that makes these narrow dust columns glow in infrared? Could they be similar to a sun pillar shining at infrared wavelengths?
Let me muse upon "These linear features"
The duller 8 o'clock one is still brighter than the almost non-existing anti-halves of the dust rings.
Another thing: the 8 o'clock ray is hardly minding the gaps.
So both "linear features" seem to be a moment of WR's blowing, the brighter (dustier) one in the direction WR—O→, the duller one in the direction ←WR—O, in a very short periastron extremal interval
But how can it be so narrow?
A dust devil uses a flat plain (slowly formed by Earth's gravity) and winds, flowing and whirling horizontally along the plain.
A sun pillar uses Earth gravity and ice mirrors' orientation.
A sun wake (glade?) uses waves, low hills of water, being top parts of spheres, smearing the reflection of the sun in the water body mirror mostly in the vertical plane holding the observer and the sun.
A Herbig–Haro object's jets use proto-planetary disk circular orbital electric current and polar magnetic field lines
Dust Shells around WR 140 from Webb
Yikes!!! 
