On two evenings in April, the heavens felt closer. Cloudless and crisp, the stars blazed with a white-hot light, seemingly close enough to touch. High atop Hawaii’s Mauna Kea volcano, two researchers used the most powerful telescopes in the world to search for 43 potential distant galaxies.
However, despite the endless clear sky and two eight-story-tall instruments, only one galaxy stood out. And it was a doozy.
It took 13 billion years for the light from the galaxy — known by its catalog name “z8_GND_5296” — to reach Earth. But it was worth the wait.
Because of its distance we get a glimpse of conditions when the universe was only about 700 million years old
Because of its distance we get a glimpse of conditions when the universe was only about 700 million years old — only 5% of its current age of 13.8 billion years,” said Texas A&M astrophysicist Casey Papovich, who is the second author of a paper published in the most recent edition of Nature.
The galaxy is about 30 billion light-years away from Earth. To put that in perspective, there are 6 trillion miles in a single light-year.
The image below from the Hubble’s CANDELS survey highlights the galaxy with a measured distance. According to the research team, the galaxy’s red color “alerted astronomers that it was likely extremely far away and, thus, seen at an early time after the Big Bang.”
Image: V. Tilvi, Texas A&M University; S.L. Finkelstein, University of Texas at Austin; C. Papovich, Texas A&M University; CANDELS Team and Hubble Space Telescope/NASA
Since we know the universe is expanding, researchers were able to determine the galaxy’s distance by calculating its “redshift,” the measurement of how quickly galaxies move away from us.
“It is like a doppler shift in that the wavelength of any light that we see from objects moving away from us is shifted to longer wavelengths — and therefore it would look ‘redder’ because red light has a longer wavelength than bluer light, hence the name ‘redshift’,” Papovich told Mashable via email.
“In the case of the galaxy we found, the redshift is 7.51,” he said, “which means the object is moving away from us at 97% the speed of light.” That calculates to about 650 million miles per hour. Before this discovery, the furthest galaxy scientists had seen was at redshift 7.2.
Galaxy z8_GND_5296 is special for reasons beyond its distance. It creates about 300 sun-like stars every year. The Milky Way, in comparison, forms one or two of these stars. The researchers are looking for the epoch in the universe when the first stars formed in galaxies. While they’re not quite there yet, this galaxy is filled with these newly created, massive stars that could be 100 times the mass of our sun.
“The stars that make up this very distant galaxy that we’ve found are forging all the elements other than hydrogen and helium — at very early times. For example, all the other elements — carbon, oxygen, nitrogen, iron — are fused in the cores of stars,” Papovich said. “The massive, luminous stars in this distant galaxy will fuse all elements and then return those to the galaxy, where they can be used for form new generations of stars and planets.”
The newly discovered galaxy gives us a glimpse at the universe at a very young age, at a time when it was in transition from an opaque state to the translucent one we see today. This leads to the team’s next big goal: to find the time when the hydrogen in the universe — in the space between galaxies — is neutral. Today, almost all of the hydrogen is ionized.
Essentially, the team will use this data to ask the very fundamental questions about how the Milky Way was formed. Studying the formation of the very first stars, as Papovich puts it, will tell us more about our own origins.
“All the elements other than hydrogen and helium in your body were once made in some now long-dead star. Carl Sagan used to say that we are all literally made of star dust, which is very true,” he said. “If there were no elements larger than hydrogen and helium, none of us would be here to ask the question, ‘where do we come from?’”