People of a “certain age” might remember all the old jokes about “x-ray eyes” in science fiction stories. Truth is, if we had X-ray eyes, we’d look vastly different than we do as human beings. And we would have had to evolve in the light of a star that gave off massive amounts of X rays and on a planet that didn’t shield us from that radiation. Like I said, if we did, we’d look very different.
Just because we can’t see X rays with our naked eyes doesn’t mean that things in the universe don’t give them off. To be sure, our Sun does give them off — but not as strongly as some objects do. There is some evidence — found by studying starbirth nurseries like the Orion Nebula — that the Sun’s infancy might have been quite a stormy one, marked by blustery stellar winds, outflowing jets, and a much higher amount of X-ray emissions than it shows now. The cause of those emissions and how long they lasted are topics that currently fascinate astronomers who study the early lives of stars.
To chart x-rays coming from stellar newborns, astronomers pointed the Chandra X-Ray Observatory at the Orion Nebula and found bright X-ray sources among the stellar babies just coming to life in that cloud of gas and dust. The x-ray image above shows about a thousand young stars in a 10 light-year-wide region of the Orion Nebula star cluster. These newborns are just blazing away with x-rays produced in the upper atmospheres of these stars. These are regions where the temperatures are millions of degrees hot. The bright stars in the center are part of the Trapezium — an association of stars less than a million years old. Young stars, such as those found in Orion, are known to be much brighter in x-rays than middle-aged stars such as the Sun.
Why are these stars so bright in x-ray emissions? Astronomers think that all the x-ray activity stems from violent flares in strong magnetic fields near the surfaces of these young stars. Although astronomers have known about the high magnetic activity of young stars for a while, the actual physical causes and evolution of the activities are still being figured out. A region rich in hot, young stars — like the Orion Nebula — provides a perfect laboratory to study the active phases of a newborn star’s life.
We’ve come a long way since people could only look up into the sky with naked eyes and wonder about what they saw. Now we explore the sky with multi-wavelength eyes, seeing things that are stranger and more wonderful than the old “x-ray eyes” sci-fi dramatists could ever imagine. Whenever I look at Orion now, I imagine it in infrared, optical, and x-ray wavelengths of light — and marvel at the things astronomy has to teach us.
