New JWST Pillars of Creation image is a treat, not a trick

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Just a touch of humor

Happy Halloween!

On this day every year I see a lot of posts from sciencey types connecting the holiday to their own fields, which is great! Fun, and informational.

But when it comes to abject spookiness — and I may be biased here, but the evidence bears me out — astronomy wins.

Don’t believe me? Let’s takes a sample of various types of astronomical objects and see how you’d fare near them.

Object Effect

Normal stars       Vaporize you, irradiate you

Black holes          Irradiate you, tear you apart, blast you with winds, eat you whole

Nebulae               Irradiate you, suffocate you

Space                   Suffocate you, eventually freeze you

Magnetars Very seriously vaporize you, tear you apart

Neutron stars      Vaporize you, tear you apart, turn you into a kinetic bomb on impact

Exoplanets (so far) Freeze you, poison you, vaporize you, drown you

Brown dwarfs     Freeze you, vaporize you, crush you, poison you

Earth                   Almost all of the above under many circumstances, but also a narrow window of habitability

I can think of more, but there’s a generous amount of overlap in murdery characteristics of stuff out there. You get the picture. Also, to be pedantic, and to quote Rick Sanchez (warning; cursing in that link), literally everything is in space, so I could, if I chose, include every other field of science as a subset. But that would be arrogant, so I won’t.

Happy science Halloween!

Pic o’ the Letter

A cool or lovely or mind-bending astronomical image/video with a description so you can grok it

Continuing with today’s holiday theme…

A couple of weeks ago astronomers released an incredible JWST image of the iconic Pillars of Creation, towering clouds of dust in the center of the Eagle Nebula.

A few days ago they released a second JWST image of the Pillars, and besides being jaw-droppingly spectacular it’s also honestly pretty spooky!

Holy three-headed dragons! It reminds me of King Ghidora.

What a fantastic shot. The colors are so eerie and dramatic! But what’s going on here? What are we seeing? And why does it look so different from the JWST image released a couple of week ago? Where are all the stars?

This image was taken using MIRI, the Mid-Infrared Instrument, a camera on JWST. The telescope is designed to look at infrared light, which has wavelengths longer than our eye can see. But like visible light there is a spectrum of infrared light. Technically speaking the longest wavelength, or reddest color, your eye can detect is about 0.75 microns. Anything longer than that out to about 1,000 microns ( = 1 mm) is considered infrared, though the definitions are a little arbitrary.

The Near-Infrared Camera (or NIRCam) on JWST looks at light from about 0.6 microns (or just inside the visible light range) out to 5 microns. MIRI takes over from there, going from about 5 to 28 microns. They see a lot of similar things but in different ways.

Slight tangent: Dying stars can have a lot of silicon and carbon in their upper atmospheres. Huge shock waves can move through the stars, slamming into this stuff and changing its structure, creating tiny grains of silicates (rocky material) and long-chain molecules of carbon called polycyclic aromatic hydrocarbons, or PAHs (basically, and seriously, soot). This material is then blown out into space, which we generically call dust.

MIRI uses filters to select certain wavelengths of infrared to see. In the image of the Pillars, what you see as blue is actually light at a wavelength of 7.7 microns. Green is 11.3 microns, and red 15 microns.

This is where it gets cool: PAHs emit light at characteristic wavelengths in the infrared, like at 7.7 and 11.3 microns. Aha! Look again at the image; see how the pillars look bluish and in some places somewhat green? That’s because those huge structures are loaded with dust, including PAHs. The MIRI image is telling you where that material is. That’s a big reason we use filters in astronomical images, to select out specific kinds of light that tell us about specific kinds of molecules and atoms.

The redder material in the background is more diffuse dust and possibly cold gas that glows dimly at 15 microns.

All those dusty grains are really good at absorbing visible light, so the pillars look dark in visible light images, blocking the light from stars embedded in or behind the dust. But in the infrared that light can get through. So in the original Hubble image taken in 1995 you don’t see many background stars because their light is blocked, while in the NIRCam image released recently there are tons more stars in the background, because their light can penetrate the dust.

But then why aren’t there a zillion stars in the new MIRI image? That’s because of a different reason: Most stars just don’t put out much light at those wavelengths. In other words, at mid-infrared colors they’re a lot dimmer. The dust is bright and the stars faint, so in the image you don’t see many stars.

Interpreting astronomical images can be tricky. You need to know what regime of light you’re looking at (infrared, visible, ultraviolet, etc.), what filters were used, what kinds of objects are in the image, how those objects reflect or emit light, and much more. And there’s usually more than one reason you’re seeing what you see… and not seeing what you don’t see.

The European Space Agency released a cool image where you can use a slider to compare the MIRI and NIRCam images. I suggest taking a look, because it’s cool to see the difference, and honestly fun (sorry I can’t embed it here for you).

And this gets funner. As I wrote in my article about the other JWST image, the pillars are huge towers of dense gas and dust — the longest is several light-years long. Just off the image to the upper right is a binary star, a pair of very massive and luminous stars just blasting out light. This radiation erodes away the gas and dust in the nebula, blowing it back. But there are dense clots of material in the nebula as well, which are harder to erode. The parts of these clumps facing those stars gets hit, and the material evaporated off them gets blown away in the direction downstream from the stars. This is just like how sandbars form as water flows around obstacles in a creek.

The tips of the towers are where there’s more dense material, and the towers themselves are made of material protected from the stellar onslaught. Everything else has gotten blown away.

As it happens, stars form in dense knots of gas and dust, and that’s happening here too! For example, the shot above shows a smaller finger of material about halfway along the longest trunk of the Pillars. See that red star right at the tip? That’s a star still forming from all that stuff. It’s no coincidence it’s right at the tip of that finger; that’s where the densest material is, so that’s what forms the star and protects the matter downstream, creating the finger in the first place! That star may have a disk of material around it forming planets, and that disk is bright enough at mid-infrared wavelengths to be seen through all the junk around it. But it’s much fainter in the NIRCam image, and barely visible in the original Hubble image.

Again, interpreting images like this can be tough. There’s a lot going on. But that’s why observations like this are so enduring. If things in space were dull there wouldn’t be much to see. When things are complicated and intricate and different forces and matter interact, well, things are a lot more interesting, aren’t they?

And the science, oh my, the science. There is so much to learn from observations like this. And remember, the Sun was born in a nebula of gas and dust, so literally and truly you exist because of structures like this.

When we gaze out into the Universe, what we see is a reflection of ourselves.

That’s not spooky at all. It’s amazing.

Et alia

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