Could the Cosmos Get Any More Fascinating???
A long time ago, back when I was in graduate school, I used to collect those “newspapers” you see at the checkout counters in stores. You know the ones I mean—the ones with screaming headlines about alien babies and mutant animals and UFOs. Since I worked on a Hubble Space Telescope instrument team, I was particularly interested in seeing headlines about it. There were two stories that really made me laugh. The first was headlined “Astronomers Discover Galaxy in Shape of Fetus!!!!!!” and the other was “Hubble Space Telescope Takes Image of Heaven!!!!!”
Of course, the image of heaven was an HST image of the Orion Nebula, which is a research heaven for people who are studying starbirth regions. But, there was no galaxy fetus out there. The editors of that story had found a press release about how astronomers had detected a faint rhythmic radio signal from a region in a distant galaxy, probably from a supernova or something. Somehow that got transmogrified into a baby galaxy headlined on a pulp rag.
There ARE lots of interestingly shaped galaxies out there, and this week Hubble Space Telescope astronomers released an image of and story about a distant galaxy that looks similar to a hovering hummingbird, sitting close to another elliptical galaxy. It’s called Arp 142, and it’s a snapshot of galaxies interacting. The whole dance of these two galaxies takes millions and millions of years, so we only get to see freeze-frame images like this one.
So, what’s going on here? Let’s deconstruct the scene. The “hummingbird” shape galaxy was a spiral galaxy before it began interacting with the elliptical just below it. The gravitational pull between the two galaxies warps the spiral and that affects the orbits of its stars and nebulae. Essentially, it warps the spiral, resulting in the shape you see here. You can also see interstellar gas being pulled out of the spiral almost like a giant string of taffy.
The whole process compresses the gas and dust in the galaxy, which triggers star formation. You can see blobs of blue throughout the galaxy—those are starburst knots caused as the gravitational dance continues on. The reddish dust lanes used to be inside the galaxy. Now they’re being thrown out and compressed into the dark veins you see silhouetted against the bright starlight.
The companion elliptical, NGC 2937, is a puffball of stars with little gas or dust present. The stars contained within the galaxy are mostly old, as evidenced by their reddish color. There are no blue stars that would be evidence of recent star formation. While the orbits of this elliptical’s stars may be altered by the encounter, it’s not apparent that the gravitational pull by its neighboring galaxy is having much of an effect.
Above the pair, an unrelated, lone, bluish galaxy, inconsistently cataloged as UGC 5130, appears to be an elongated irregular or an edge-on spiral. Located 230 million light-years away, this galaxy is much closer to us than the colliding pair, and therefore is not interacting with them. It happens to lie along the same line of sight to foreground Milky Way stars caught in the image.
Now, I find this to be a MUCH more satisfying story than the kinds of things you read in the supermarket rags. Nothing their editors can dream up is anywhere NEAR as fascinating as what the actual cosmos is revealing to us through the watchful eye of the Hubble Space Telescope!
