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Four different - and spectacular - views into a stellar nursery
If you’ve ever been a parent, then when your kid was a newborn you’re aware of bipolar outflow, whether you know the term or not. It’s when you have two streams of matter (it can be in various states, and oh boy can it be) ejected from a single object in opposite directions.
For a new parent it’s unpleasant (it’s unclear in many cases how it is for the baby), but in other circumstances it can be beautiful.
Like, when the newborn is a baby star. Behold!
That is a Hubble Space Telescope image of one part of a large nebula (a gas and dust cloud) called NGC 1333. Distance measurements vary, but it’s probably about 1,000 light years away, and is actually birthing stars. Some of the stars in it are less than two million years old, which qualifies them as newborns.
There’s actually a lot to see in this shot. The images are taken in the near-infrared, the kind of light that can pierce through interstellar dust better than visible light, so we’re seeing inside the nebula. Dust makes light from stars behind it look redder, so the stars on the right are deep inside or on the far side of NGC 1333 from us.
The bright star on the lower left is BD +30 547, a young star associated with the nebula that, were you to see it by eye, would look pretty red. However, in the infrared filters used here, it appears whitish. You can see bluish (remember, really still infrared-ish) nebulosity around it; that’s gas and dust reflecting the light of the star back to us, so we call that a reflection nebula.
But more interesting is the odd lozenge-shaped structure above it. That is, I believe, a cavity carved in the nebula by several young stars inside it. They are blowing fierce winds of subatomic particles, and that’s pushing the material around them away, like a snowplow plowing up snow.
But look inside that cavity and you’ll see several bluish structures. Those are called Herbig-Haro Objects, and are special young stars. These are stars that are very young, still with a disk of gas and dust around them from which they formed. The stars themselves are likely spinning rapidly too, and they have powerful magnetic fields that are being wound up like tornadoes from their poles. Material caught in those fields gets ejected from the star, and this forms highly focused (astronomers would say collimated) twin jets of matter screaming away from the star’s poles, up and down at ridiculously high speeds, usually hundreds of kilometers per second.
Bipolar outflow!
There are five of them in this region, called HH7 – 11. I was a little confused on the numbering, but happily, I found an annotated map of the region in a paper published in 2000 (see Figure 1 in that paper) which guides the way: HH 7 is the blue spot at the top left, HH8 is to the upper left of the cavity, HH9 to the upper right, HH10 is the long one in the cavity, and HH11 is the one just inside the cavity to the lower right. These all mark the locations of newborn stars, blasting out gas. Just like newborn humans.
It’s interesting to see more of this nebula. Here’s an image of it taken by my friend Travis Rector using a 4-meter telescope at Kitt Peak, Arizona:
Oh wow! This is rotated about 90° counterclockwise to the Hubble image. The brightish star just to the lower right of center is BD +30 547, and the string of deep red blobs just to the upper left of it is the cavity in the Hubble image. They look red here because of all the dust; they look blue in the Hubble image because that’s an infrared image translated into visible light.
As you can see, the bottom part of the nebula is deeply red where it’s not black; in some places the dust is so thick it utterly blocks the light from stars behind it. The upper part is blue, and is another reflection nebula.
This is a popular object with astronomers, and was also observed with the Spitzer Space Telescope, which looks much farther out in to the infrared than Hubble can, far enough where the warm dust itself glows. NGC 1333 looks like an entirely different beast to Spitzer:
Wow! This has roughly the same orientation as the visible light image, but is a slightly tighter shot. There are even more Herbig-Haro Objects in here; the one on the right of center has curved jets! That may be due to precession; the star is wobbling very slowly as it spins, like a top that’s starting to spin down. Over time, the direction of the jet changes, like a sprinkler shooting out water, giving it a curved appearance.
Wanna see it look really different, though? Then how about this:
Yes, that’s still NGC 1333, but now you’re seeing the X–rays coming from it, detected using the Chandra X-ray Observatory. The dots are all X-ray sources: The young stars in the nebula! It’s not clear what is causing them to emit X-rays, which takes a lot of energy, but it’s likely something to do with their strong magnetic fields interacting with gas in the disks surrounding them. Particles swept up in magnetic fields can gain vast amounts of energy that they then radiate away as X-rays.
[Note: If you want yet another view, take a gander at this amazing composite Robert Gendler put together using various telescopes.]
I’ve said this before (a zillion times): What you see in astronomy depends on how you see it. And look what happens when you change your eyes! You see deeper into the nebula, grasp the forces forming stars and blowing vast bubbles in the gas, or watch as star and gas interact via magnetism on a scale billions or even trillions of kilometers long.
Even the familiar becomes unfamiliar when viewed a different way, but that’s the point, isn’t it? When you do, you learn something new, and appreciate it in a different way. In the Universe as it is in life, it pays dividends to appreciate different things in different ways. You get a much richer view of all around you when you do.
