‘Time machine’ peers back 13 billion years
No human has ever seen an object as distant as the tiny dot of light that showed up in telescopes April 23.
“Thrilled” is how Socorro astronomer Dale Frail described his emotions the day the Very Large Array radio telescope first spotted the dot.
The image had been traveling 13 billion years to get here. Which means that, for Frail, the VLA is a sort of time machine, conveying the great privilege of allowing him to look back to the very dawn of time.
Frail’s a lucky man, and he knows it.
Faint by the time it reached Earth, light from the exploding star was first detected shortly after midnight New Mexico time by a NASA satellite that scans the sky for signs of unusual explosions in deep space.
Within 20 minutes, a telescope in Hawaii had zeroed in on the coordinates relayed to Earth from the NASA satellite and saw something unusual. Nial Tanvir, a British scientist responsible for the Hawaii telescope, sent out a message to the astronomical community describing it dryly as “a faint source.”
A second telescope in Hawaii picked it up soon afterward, and one by one, astronomers around the world, linked 24/7 by the Internet, turned to look. Telescopes in Chile, the Canary Islands, Japan, Australia and China joined the hunt.
In Socorro, Frail waited patiently. Up the road, the Very Large Array, one of the world’s great telescopes, stood ready.
The array of 27 giant antennas, funded by U.S. taxpayers via the National Science Foundation, collects naturally emitted radio waves from distant objects. Frail likens using it to flying a high-tech fighter jet. Used right, it can do amazing things, and he is thankful taxpayers have given him the privilege of using it.
Astronomers’ technical description of the period when the first stars were forming, soon after the universe was created in a “big bang” 13.7 billion years ago, is “the epoch of re-ionization.” In friendlier language, they call it “the dark ages.”
What were those first stars like?
Figuring out what happened that long ago might seem hopeless, but astronomers have a trick. Used with a bit of cleverness and all the technology they can muster, telescopes allow astronomers to look back in time.
When you stand in front of a mirror, Frail explained by way of example, the image you see comes from light bouncing off your face, hitting the mirror and bouncing back into your eye. Light is fast enough that it seems instantaneous, but it really takes about a nanosecond for the light to get from here to there and back again.
You’re seeing yourself as you looked a nanosecond in the past.
Light takes 8 minutes to travel the 93 million miles from the sun to Earth. So the sun you see in the sky is really what it looked like 8 minutes ago. If the sun suddenly blinked out, Frail said, it would be 8 minutes before we realized it.
Multiply that by the vast expanse of space, and the time it takes for light from distant stars to travel to astronomers’ telescopes means that when they finally see them, they are in effect looking back in time.
But an ordinary star that far away would be impossibly faint, so astronomers must hunt for deep space explosions, the only thing bright enough in far distant space to be seen from Earth. Barely.
That is what Tanvir, Frail and the other astronomers were doing in April. Once they calculated the distance to the object, they realized they were looking at the most distant object ever seen, a star that exploded an estimated 13 billion years ago.
Frail still gets excited talking about his first look at the exploding star, and he talks with pride about the ability of the VLA and the crew running it to see the faint object.
“I really did push the telescope as far as it can go,” Frail said.
But it was enough, and data began streaming in. For more than a month, Frail and his colleagues watched until the stellar embers left behind by the cosmic blast finally faded from view.
In a paper submitted to Astrophysical Journal Letters, Frail and his colleagues describe what their data have told them about that tiny little dot of light.
It was an exploding star, its shock wave slamming into the interstellar gases surrounding it.
Most important, it was among the very first stars in our universe, one more scientific clue to how everything around us came to be, and Frail and his colleagues are lucky enough to have been able to see it.
John Fleck is a reporter and columnist for The Albuquerque Journal. This article originally appeared in the Tuesday, Nov. 3, issue of the Journal.