Follow the Pointer

A wide-field image of WR-25 and Tr16-244 in the Carina Nebula. Courtesy NASA/ESA Hubble Space Telescope.

My friend Phil Plait has a thing about instances of pareidolia — the tendency of humans to see interesting patterns in things.  It’s a peculiar psychological thing that our primate brains do to us when we see things we don’t immediately understand or can’t place in context. So, for example, you look up at clouds in the sky and see spaceships or dogs playing or sheep sleeping or whatever it is that the cloud seems to resemble. And, of course, there are tendencies among some folks to see things like faces of deities in toast and tortillas, or peeling paint, or the bark on trees. It’s all very amusing and shows you how complex our brains are.

Astronomy images provide hours of merriment for pareidoliacs.  Take this picture, for example.  It’s a Hubble Space Telescope view of a gas and dust cloud where star formation is taking place. Notice in the very top of the picture that there’s a thick cloud of dust in the shape of a pointing finger. At least, that’s what it looks like to me.  And, it  might appear that way to you, too.

Well, you might ask — what’s it pointing to?  Good question, and the answer is what the subject of the image really is:  a pair of massive bright stars down in the lower third of the image that are shining out like a pair of headlights. (Or, if you’re a fan of LOLcats, they look like “cat lazors” charging up.)

This scene is smack in the middle of the Carina Nebula, a huge region where clouds of gas and dust are combining to form new stars. It is about 7,500 light-years away from us, and also contains the luminous blue variable Eta Carinae, which is expected to pop off as a supernova pretty much any time now (in cosmic terms).

It turns out those two bright stars have an interesting connection to the pointy-finger cloud. The bright star in the lower center is called WR-25, and its quite massive — more than 50 times the mass of our Sun.  In fact, it’s really two stars orbiting a common center of mass. They hot, bright, and interacting with each other.

The star to the left of WR-25 is called Tr16-244, and it’s actually three stars orbiting a common center of gravity — a triple-star system. Together, these two star systems are eating away at the clouds of gas and dust. That “cannibalization by radiation” is actually what sculpted the finger-shaped cloud. It’s amost as if the cloud is pointing the finger of blame back to the stars that shaped it — a nice case of cosmic pareidolia.