Strange and Lovely Starburst Galaxy Seen by Hubble

Bad Astronomy
The entire universe in blog form
May 20 2013 11:51 AM

Galaxies Are Weird and Weirdly Beautiful

Galaxies, on the whole, are very pretty. I find that interesting, actually; we didn’t evolve to see galaxies with our naked eyes, and they exert no selective pressure on us to breed, so when we find them so attractive it must be coincidence. Their shape, color, and structure just so happen to fit our definition of beauty. Appreciating the art of the Universe is a collateral benefit of evolution.

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

And then there’s this galaxy, prosaically named J125013.50+073441.5 (after its coordinates on the sky). I have to admit I’m admiring its strange appeal.

A swirl of star formation
The strange and lovely wreckage of a cosmic collision. Click to galactinate.

Photo by ESA/Hubble & NASA, M. Hayes

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What an odd thing! It's located about 500 million light years away, and has clearly suffered a massive collision—while it does have spiral arms, the overall structure is a mess, indicating some large disturbance happened not too long ago. Most likely another galaxy came along, and the mutual gravity of the two drew them together, creating chaos in their structures. There’s no other nearby galaxy in the image, so I suspect the two wound up merging, and we’re catching it a few hundred million years after the event. The ring in the center and the small straight spurs around it are relatively common features seen in the aftermath of collisions as well, formed by the gravitational interaction of one galaxy as it plunges into another.

The image, taken using Hubble Space Telescope, is rather unusual, spanning a wide range of wavelengths of light. It’s a composite of three observations, one in the ultraviolet (shown as blue in the image), one in visible light which accentuates normal starlight (shown as green), and near-infrared which highlights dust (red).

Ultraviolet light is emitted by young, massive, hot stars (and the gas surrounding them, lit by the intense radiation), and those tend to be born in spiral arms. That’s why the arms look blue. There's so much ultraviolet light being emitted, so much star formation going on, that J1250 is labeled a "starburst galaxy"—again, that tends to be an effect of galaxy collisions, when massive clouds of gas slam into each other, collapse, and furiously form stars. The dust is all over the place, and really does look like it was stirred up by the collision. Dust is actually made of complex organic (carbon chain) molecules, created when stars are born and when they die.

Light and dust in a nearby starburst galaxy
The galaxy J082354.96—"Cinderella's Slipper"—which is also a part of the LARS observations.

Photo by ESA/Hubble & NASA, M. Hayes

In the Hubble release for this image, they mention this galaxy was observed as part of the Lyman Alpha Reference Sample research; a survey to look at galaxies that emit a lot of a special kind of ultraviolet light called Lyman Alpha. As it happens, I wrote about this survey recently when Hubble released a spectacular image of another targeted galaxy, which I think should be called Cinderella’s Slipper.

The survey is helping astronomers understand galaxy formation and evolution by looking at nearby galaxies that can be used as models for far more distant ones. Closer ones are easier to study, while more distant ones may appear only as dots. The closer ones allow us to separate out various features (like the center of the galaxy versus an extended halo of gas) that are unresolved in the more distant galaxies. It’s a clever idea, and very useful for understanding what galaxies were like when the Universe was much younger.

And it does provide us with a bit of eye candy along with that nutritional brain fodder, too. I’m not an evolutionary biologist, so I’m no expert in the whys and wherefores of our appreciation of the beauty of the Universe. But I do know what looks lovely to me, and I also know that the science behind that beauty adds to it, giving it depth and personality. Art is always supplemented by the knowledge of how it came to be…especially when it’s on a grand a scale as the cosmos itself.

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