The reason we can see any of the nebula and the stars in the foreground is because those hot young stars in the foreground have carved out a large hole in the nebula with their strong solar winds and intense radiation. In fact, that radiation is what is causing the nebula in the background to glow in the first place.

One just has to imagine that the small yellow star creating the bubble is blasting particles into the gas cloud in the background, and also into the foreground, it’s just that there’s no gas cloud in the foreground, since that part of the cloud has already been eaten away by the blue giants. Even if it were obscured by a dense cloud of dust in the foreground, we would still see it, even if just a little bit – remember that the red in this image is infrared light, which such a nebula is transparent to. However, none of the “southern” jet is visible at all.

We can also tell that this really is a jet of energetic particles, largely because it looks exactly like the kind of jet that comes out of black holes, just on a much smaller scale.

I don’t agree with any of those interpretations, or most of the others posted.

The 4th possibilty: Phil is totally right about what this feature is and that all such systems with protoplanetary disks (proplyds) DO possess opposing (bipolar) jets, but the other jet in this particular case is simply OBSCURED by much denser dust in that direction, being blown INTO the dense part of the cloud, whereas the visible jet has blown out more or less towards us into the relatively clear LESS dense region, rendering it visible to us on this side of the dust cloud within which the star was born.

You can see two other examples of exactly the same phenomenon to the lower right of that one in the hi-res image. One is located almost directly below the bright foreground star near the center of the image: it shows a bubble being blown out into the more rarefied region to the right. Interestingly, there is a also a diffuse patch of light located on the opposite side to the left (to the left of that other bright star that is almost certainly oriented with its jet axis pointed directly at us, but don’t let its placement there confuse you) that seems to be exactly placed on the same axis: that may be interpreted as the terminus of the opposite bubble whose light manages to filter through and out from behind the intervening dust cloud.

The other fainter example further to the lower right beautifully exhibits a hybrid between the ‘sandwich’ proplyd Phil features and the his example in which dust strongly absorbs one of the jets. Notice how the diffuse cone to the upper-right is significantly brighter than the opposite cone aimed to the lower left. This example clearly shows how the emission of one polar jet can be prefentially suppressed by intervening dust compared to the other.

It all depends on the orientation of these systems’ axes and where they are located with respect to their formative dust cloud as well as what position an observer happens to be viewing the complex from: if we looked at this region from the ‘back side’, the chances are that we would probably see the jet bubbles that are strongly dimmed from the earth-side while the bright jets we see from Earth would be strongly dimmed.

How do I ‘know’ this is right? BAH! I DON’T! But a proper or at least more satisfying interpretation of star-forming nebulae doesn’t come just from unambiguous observational data. It is also informed by ‘artistic intuition’ and an ability to visualize otherwise abstract forms like a glowing cloud into 3-dimensional shape that remains consistent with the ‘flat’ 2-d image. If it is more an ‘art’ than a ‘science’, so be it.

‘Art’ may be provisional, but what science isn’t? After all, plenty of intuition and imagination goes into the formulation of scientific hypotheses all the time. In fact, science would be impossible if we could not visualize trial possibilities and pose them as questions which may be awarded an answer.

Whether art or science is brought bear or both are employed in tandem (inevitably the latter, like it or not), in cases of astronomical image interpretation like these one is nevertheless compelled to take into account the geometry of the cloud system, that is, its POTENTIAL shape, size and density distribution as well as the positions of the stars embedded in it, in order to arrive at a simplest (Occam’s razor) and therefore more elegant and satisfying interpretation that nevertheless remains consistent with what we DO have to work with: a breathtakingly gorgeous yet maddeningly FLAT 2-d image.

How ignorant must I sound! I know very well about Interstellar Clouds from a long time ago yet never viewed Orion that way. If ever it was written, I somehow mentally dropped that concept out of what I read. I just looked at the image and must have burned into my brain the general shape and look of the radiating nebula and took it that it must have had a single point of origin; and yet knew that just one star couldn’t account for that much nebula.

How possible is it for a single star to create such a sizeable nebula? Is this what we are in the ‘middle’ of observing with Eta Carinae?

Massive nebulae like the Orion Nebula and other star-forming nebulae in galaxies are generally called “Interstellar Clouds.” They are dense structures within a galaxy that consist of dust and gas and the gravity that material creates sparks star formation. Planetary nebula and supernova nebula can form within a nebula like Orion. Stars and even the nebulae they create are pretty small compared to the the size of an interstellar cloud.

Can the Orion nebula be attributed to one supernova (or hypernova) or is it actually the result of successive supernovae occuing in the same ‘burb’? I mean, it may not be the largest supernova, but it is a heavyweight among them. How possible is it that such a nebula could originate from one star going super/hypernova? Or am I not thinking BIG enough?

Well, let me give you some “reasonable speculations”.

I guess, since the energy of these jets is not as high as in, say, a jet of a super massive black hole in an Active Galactic Nuclei (AGN). Therefore, the intensity of the jet is also reduced. Similarly, the synchrotron radiation of the electrons should mainly be in the radio part, making the jet faint in the optical and infrared. Maybe a radio picture could show them.

What also plays an important role, is relativistic beaming. If electrons move close to the speed of light (and I assume they do in a jet of young star, similarly to their larger cousins), the emitted synchrotron radiation is given off mainly in the forward direction. So, if the jet is not pointed directly at us, it is even fainter (while it can be extremely bright when it heads straight for us).

It could also be that the jet is too narrow, and is thusly not able to give off enough radiation to be detected.

This would I can imagine at the moment. But there could also be other reasons.

The waves in front of the jets are shock fronts, and we see them because they run through the cloud like water waves, compressing the material, making it hot enough to glow.

Here’s a link that shows both M42 (classic Great Nebula in Orion), and M43 that this picture is of. I have no clue what exact part of M43 this image is taken from. But M43 is the smaller blob to the upper left.

http://www.celestronimages.com/details.php?image_id=5390

To get to the question I had attempted to pose: how feasible is it that the jets produced from a star such as the one in question would not be clearly visible in the bands shown in the picture?

Well, actually every star produces jets in its infant state.
As Phil described, the star forms a disk around itself, which produces planets but also keeps the star growing. It’s an accretion disk. However, matter of that disk does not fall on the star quite easily, since it revolves around the star. To get rid of this motion, you need some kind of friction.
Classical friction is not sufficient, but magnetic fields can help a lot. So, the interaction of magnetic fields with the disk helps transferring some of the angular motion from one particle to another. The one that loses the motion falls onto the star, while the other one is accelerated outward. Since the particles are charged, the accelerated one follows the magnetic field lines and is rushing up to the poles, where it is released into the jet.

This is more or less the picture of the accretion process, which occurs in many different systems like young stars, neutron stars or black holes. Whenever something wants to gain more mass, it must shoot out jets.
(Btw: This is an active field of research, and many problems are not yet solved, but the basics (as outlined above) seem to be clear.)

First, I would guess that the top jet is angled at least 20 degrees (yes, pulling that number out of my bottom) into the plane of the picture, such that the bottom jet would seem to be entering a rather empty area. Second, I would guess that the jets are some form of radiation/high energy particles. Of course, I can’t think of what kind of star could produce such jets off the top of my head, and in any even I am fairly certain that such stars would not be found in a stellar nursery (unless they are some sort of creepy star, hanging out with the babies like that).

(Forgive my rambling, but I am dealing with the competing influences of a lack of sleep, and the excitement of having my first {non-humid} night on my school’s telescope start in less than 3 hours.)

While we all seem to be quoting and reminiscing TV shows, then I’ll add one to join in with Mike R…

Sauron: You cannot hide. I see you. There is no life in the void. Only death.

(I know… probably cheesy, but I couldn’t help myself!)

Or how about the bottom middle one, that has a small dot about a mm to the left? It doesn´t have two sets of refraction spikes but, could that be a binary system too?

I guess the fact that I “heard” it in Horshack’s voice would date me as well?

Man, did you just date yourself with that opening line!

Looking at the “embiggened” version, all the stars have a cross-shape of four rays radiating outward from a central point. I’ve read that this is due to light refraction around the struts that hold Hubble’s secondary mirror in place. However, two stars (one just above the “ear” and one at the bottom of the frame) have TWO sets of spikes.

Does that mean that they are binary systems, with two stars close together, or is there some other reason?

Furthermore, the star above the “ear” has two vertical spikes, but only one horizontal one. The one near the bottom has two of each. Does this mean that in the first case, the binary is side-by-side with respect to Hubble (horizontal, but not vertical, separation of point-sources)?

Thanks for indulging me – I love this stuff!

[Rushes for the brain bleach.]

Don’t believe me?

Oh BA, I always believe you!

Well, *almost* always anyhow.

Great images & write-up.

Yup, my infant did the same thing.

I’ve always wondered what those random areas of gas around stars that are emitting infrared glow. Is it just the shape of the gas near them being heated, or are they emitting energy in a certain way to create that shape? An example being right below the bright star in the very middle. Other imagines of Orion have tons of these.

Also, that bright star on the far left-middle, what’s with all the stars around it? It seems like, if they were background stars they wouldn’t be so apparent, so are they somehow closer or in nay way related to that bright star? In that one super large Orion picture that Phil posted a few months ago, there were tons of these stars with objects that appeared to be right beside them. I just assumed they were binary pairs. I don’t know how prevalent they are though.

Or not. Could be just a bunch of electro-plasma.