For the first time, astronomers have been able to accurately measure all of the starlight that has been produced since the creation of the universe 13.7 billion years ago. While the dawn of the universe began with nothing but blackness, after several hundred million years had elapsed it finally began giving us the luminous stars we see now.
As the Daily Mail reports, after the first stars appeared on the scene, their production level increased incredibly fast. Astronomers have now calculated all of the starlight created by stars by looking for photons that managed to escape through the vastness of space. These photons were measured at 4×10 to the power of 84. In other words, this number is four with 84 zeros tacked onto the end of it.
It was astrophysicist Dr. Marco Ajello — and a group of astronomers hailing from Clemson College of Science — who were able to measure this starlight after studying data taken from NASA’s Fermi Gamma-ray Space Telescope. Their goal was to learn more about how stars first formed, and they discovered new ways to measure starlight as part of this research.
All of the starlight that reaches the Earth — excluding of course our own sun, and stars found in the Milky Way — is extremely dim, and would be akin to staring at a 6o-watt light bulb while standing at a distance of 2.5 miles away from the light. To determine how much starlight has been produced, Ajello’s team scrutinized close to nine year’s worth of data taken from gamma-ray signals.
As Dr. Ajello explained, “Gamma-ray photons traveling through a fog of starlight have a large probability of being absorbed. By measuring how many photons have been absorbed, we were able to measure how thick the fog was and also measure, as a function of time, how much light there was in the entire range of wavelengths.”
Dr. Paliya, from the department of physics and astronomy at Clemson, was responsible for studying the gamma-rays of 739 blazars — and was able to measure starlight from many different epochs, including the one when stars first formed.
“By using blazars at different distances from us, we measured the total starlight at different time periods. We measured the total starlight of each epoch – one billion years ago, two billion years ago, six billion years ago, etc – all the way back to when stars were first formed.”
Despite the fact that the production of stars is now not as great as it once was, in just the Milky Way alone seven new stars continue to be created each year.
The new study, which has determined how much starlight has been created since the beginning of the universe, has been published in Science.